LEIDSE GEOLOGISCHE
Geological
maps
MEDEDELINGEN, Deel 50, Aflevering 2,
of
the
Southern
Cantabrian
75-114,
pp.
Mountains
1-4-1980
(Spain)
BY
J.F. Savage
AND
D.
Boschma
Abstract
This
compilation
Prof.
by
This
by
L.U.
Only
the
1950.
Hercynian
suprastructures
180°
through
Very
in
The
structural
total
tectogene
is
area
data
accompanying
characterized
minor
giving
the
amounts of
represented.
of the
The
orogene
centripetal
igneous
degree
rock
of
are
a
very
of the
been
well-known
Knee
is
so
slight
to have
²
in
1:50000
strip
a
lend
decollement
more
sheets
than
themselves
thrusting
to
and
completes
150
of Palaeozoic
sequence
sequences
km
shelf
a
the
project
sediments
only interrupted
model.
simple geosynclinal
folding.
initiated
from east to west.
Fold
and
thrust
vergences
of Asturias.
mapped although activity
metamorphism
of the
(re)issue
consistent
Neither of these
exposed here; essentially
pattern
have
by
the
about 400 km
mapped comprises
late-orogenetic flysch-molasse development.
to
systems
and
stratigraphic
de Sitter
of the
part
syn-
vary
of
been
in
form has
some
negligible
for the
been
registered throughout
most
of the
mapping.
Contents
1.
Introduction
76
Alba
Acknowledgements
77
Upper
Formation
Namurian
2.
Stratigraphy
77
Precambrian
80
Mora Formation
Cambro-Ordovician
Stephanian (Cea Group)
95
80
Permian
80
Labra
80
Triassic
Lancara
Formation
81
Triassic
97
83
Jurassic
Luarca
83
Tudanca
84
Cretaceous
Formation
Formation
sheets
Arroyacas
Carazo
(Yuso,
Carrion
and
Formation
Formation
Devonian
La Vid Formation
Compuerto
Lebanza
Abadia
Unit
97
97
Unit
97
98
84
Wealden facies
98
84
Voznuevo
98
84
Bonar Formation
85
Pisuerga)
Jurassic
97
Barrios Formation
Eastern
Formation
98
Tertiary
98
85
Vegaquemada Formation
98
85
Candanedo
98
86
Riacos
Formation
Formation
99
86
86
Formation
Formation
86
Formation
86
3.
Structures
99
Structures
Narcea
of the
Leonides
Anticlinorium
99
99
87
Salce
Unit
Otero Formation
87
Babia
Alta
Unit
100
Caldas
87
Babia
Baja
Unit
100
Huergas Formation
88
Luna
Unit
Piedrasecha Formation
88
Aralla
88
Alba
88
Mirantes
Formation
89
Pedroso
Formation
89
Rozo
Formation
90
Pozo Structure
Ermita Formation
90
Bregón
Vidrieros
90
Cueto
90
Correcilla
Santa Lucia
Formation
Formation
Gustalapiedra
Portilla
Nocedo
Murcia
Lower
Formation
Formation
Cardano
Formation
Carboniferous
Vegamian
90
Formation
Gayo
Instituut
3584 CD
voor
Aardwetenschappen Utrecht, Budapestlaan 4,
Utrecht
Geologisch
Leiden
en
Mineralogisch Instituut,
Garenmarkt
lb,
2311
100
100
Zone
101
Synclinorium
101
Anticline
101
Syncline
101
Unit
101
102
Unit
Negro
102
Unit
102
Unit
103
103
Unit
Bodón
PG
97
Nansa
San Pedro Formation
**
97
and
82
Robledo
*
Formation
Oville Formation
Formigoso
94
94
Formation
Silurian
91
(Upper Ruesga Group)
Westphalian (Yuso Group)
Herreria
Formation
91
Carboniferous
Unit
Forcada
Unit
Armada
and Pallide
Esla Unit
Pardomino
104
104
Subunits
104
105
Ridge
105
76
Las
Salas
Esla
Zone
Nappe
Felechas
References
Syncline
105
Enclosures
106
Map
Valsurvio
Dome
106
I
Sierra
Brezo
107
II
del
Post-Stephanian Hercynian
in
structures
of the Asturides
Bernesga-Torio-Curueno-Porma
IV
San Isidro-Porma
107
V
VI
108
VII
San
Liébana
Upper
Julian
and
Carrión
and Cardano
Carboniferous
Post-Hercynian
A
IV A
Cea-Esla-Porma
108
Monto,
I
II A
III
Picos
Europa
Sections
Luna-Sil
Luna-Bernesga-Torio
Ponga Nappes
de
Sheets
107
the
Leonides
Structures
112
105
Syncline
Salio
Agua
105
s.s
Yuso
109
VIII
110
IX
VI A
Carrion
Nansa
VII A
Deva
VIII A
IX A
Pisuerga
110
flysch
structures
X
Ill
Conclusions
Cross-sections
Ill
Structural
CHAPTER
for
Map
sheets
III and
V and
Sketchmap
1
INTRODUCTION
series of
The present
Cantabrian
that
work,
Dr.
Sitter's
De
known
be
hill'
for
southern
result
of 25
of field
was
with
their
accurately
As
areas.
to
'which
teacher and
In
findings.
young
in-
purpose:
of hitherto
as
the
of
behind
each
de
un-
to
area
started
it
coloured
over
be mapped
thesis, and finally
the
next
kept high
Sitter
by running
area
'doctoraal'
a
lies
pupil,
general
students,
publication
by
double
a
investigation
general map of the
a
concluded
served
and
hence the students had the advantage
both
new,
in
trips
new
group of
a
more
and
part
as
map
be
to
doctor's thesis.
a
In
the
gress
of
port de
area,
course
was
phanian
Pisuerga,
were
1951
the
Sitter
In his
area
limestones
and
quartzites,
area
Visean and
was
year
Ventanilla was also
students
Ste-
concluded
are
upon
top
on
was
seen
Dinantian
discovered (the
to
be
re-
following
years,
introduced in the
1955
Guardo
area,
the
was
field
Valsurvio
was
so
in
of the Carrion River.
units, especially
tinctive from the
and
area
Comte
tage
through
-
with
the
area,
of
same
area
The R£o
the
last
grew,
as
with
in the
the
and
Polentinos
Palaeozoic
east
of view of
were
mapping
not
very
dis-
purpose. This
present
be
to
area
at
the present
was
likely
more
that
no
fields
as
a
the
Leiden
means
he
wish
one
The
At
to
the
very
consolidate
to
penetrate into
work.
at
were
geology
of
based
time
the
on
but should
and
knowledge of
the
maps
short
a
stratigraphy
complete,
palaeontology
the
of
interest
not
the Palaeozoic of
to
and
be
was
area
investigation by specialists
improving
of
vast
produced,
maps
considered
'oeuvre'
A
criticism
1962-meeting
a
to
the
to
stratigraphy
enlarging
volume.
1:100 000
distributed
to
did
colleagues
restricted
sedimentology,
complete
of af-
of the Rio Sil
preferred
The main purpose of the present
in
The
but
area
which
did he
Spanish
base for further
geology, thus
a
project
information.
sources
contribution
slope.
state
same
provoked them
as
Neither
its development, and
the
the
lost.
get
correct
the
to
moment,
area.
southern
as
at
1962
the work established till that date.
up
mixture of rock-unit
by
to
In
compiled and
settle the
to
far from complete,
Cantabrian Mountains is
are
aim
Precambrian lies,
where
the
rapidly.
mapped. Beyond this
Cambrian and
Up till that time rock-stratigraphic
in the Carboniferous
point
Cervera
to
Luna
de Sitter
grew
scale
de Sitter took advantage of the
in Oviedo
the
between
together
progress
time
area
people working
contribution of
stu-
50 students,
1:100 000
primary
was
of
groups
some
work in the Cantabrian Mountains
co-operators it
amongst all
and
the
many
course,
Thus
the knowledge
so
a
that time
at
-
took full advan-
group
Sitter had
of the
information is
some
Asturias,
of Silurian
with
With
de
at
on
of his
geologist:
a
Working with large
map
map
published
as
1963
all grades,
geological
map,
in
g.
general
and
increasing number of
an
e.
-
career
Pierre
by
wartime circumstances
to
thesis, the Leiden
-
Table I).
(see
dents
due
its
Lower
to
sections
westerly
more
with
area
The sequence,
described from this
excellently
unfortunately
unpublished
was
presence
Esla
through Silurian,
sandstones
several
who
interrupted his
serve
tackled,
work
Cambrian
Barruelo
did the problems!
In
from
of Polentinos
been demonstrated).
only recently
In the
the
of
When in 1952 the 'complete'
presented, the link between Cervera and
That
re-
are
around Cervera de
Westphalian C-D in the Sierra Corisa
completed.
years,
unconformably
rest
the
pro-
1950 internal
non-fossiliferous shales
of these limestones (Culm).
in
that the coals
adjoining
established. In the
started
These first
where another student started, it
Dinantian
older
slow.
very
In
age.
de
student.
one
Sitter writes about that
Westphalian
that
with
the
to
marvelous lower Palaeozoic stratigraphy.
fairs.
Cantabrian Mountains
Barruelo
changed when de Sitter moved
Carboniferous had been
field
areas;
obtaining
has
of the
slope
years
direction of Prof.
1950 under the
students,
trained in
interest
of
the
L. U. de Sitter.
struction
to
in
started
of the
maps
Mountains is
in
structural
the
area
and
mapping.
publication
of
the
description
area
is
to
make
available
of the
geology
77
involved should suffice. Those readers interested in
of
detail,
the
of
scriptions
In that
the
less
or
repeat what de Sitter
to
I
beginning
present
de-
want
of
outcrop
emphasize the fact
to
Palaeozoic
mountain
chain
fortuitous portion
of
in
wrote
in
rocks
much
a
the
only
represents
a
larger Her-
cynian block, the present outcrop being determined largely
by
dominated
rocks,
with
particular
Cambro-Ordovician
by
western
from Precambrian
range
half of
one,
in
where rocks
map
Upper Carboniferous.
to
one
Carboniferous
southern
a
the
northern
a
and
little Devonian, and
very
in the
The
two
units have been named the Asturides and Leonides,
and
are
Luna Zone,
south of this line, consist
find
the
we
Carboniferous
of
discordant
synclinorium
Carboniferous
Upper
resting
on
essentially
Precambrian,
in
Cambrian;
Lower
the Cambrian has been thrust
in
role (the
Yuso
the
upper
the
Pisuerga
area), and
Carrion
the
known
end
western
continue but
of thrusts.
and
the
the
diverse
with
with
Just
up.
Lower
over
against
Further
the
splits
the
the
east
thrusting
van
Unit with
in
Esla
further
Cea
or
the Valsurvio
have
into
up
its
southern
It
is
possible
not
how
(and
they)
deter-
'Asturian Knee', and
den Bosch,
mention by
to
contributed
flank
major
contributors
grams
given
northern
its
at
base
Thrust
with
will
thrusting
1968).
name
the
to
sheets.
in
follows
east
first the
and
Devonian
in
the
from
going
the
or
Ordovician
on
of the
Leonides
Between these
we
or
the
find
gradual development of this hiatus.
is
of it would have
none
privilege for
omit
quite
us
all to
in
the
J.
appearance
of
group
haps in the place
many
foreign guests in
to
could
but without that
man
It has
accomplished.
man
been
a
be involved in this work.
the
through
Roest whose
most
been
that this work
of the
not
but
of
maps
the
of
our
our
we
superb
been
cannot
work
of
elevates the
draughting style
figure in
names
has also
years
individual publications
does
dia-
reliability
have
acknowledgement of the
grateful
Miss C. P.
One
clear
one
been
Technical assistance
credited
of
and
Tejerina Syncline,
south
is complete.
sequence
Leo-
complete absence
directly
rests
dis-
the Ruesga
Dome. These units of the
the
the
It
capacities.
the
There
who
everyone
presented. The
maps
found
be
most
have been done by
never
taken
they form
the León Line the Famennian
Carboniferous
Cambrian,
sheets,
Sheet has
Together
the almost
common
north. At
to
again
River this
thrust
many
the gradual disappearance of Devonian rocks
a
not
ACKNOWLEDGEMENTS
Namurian of the
Basin and then
Westphalian rocks, except in
even
do
number
a
eastern
complicated
its
the Bernesga
movement.
cordant Valderrueda
south
and
Leonides
Pardomino Fault along the Porma
Luna-Esla Zone. Still
Lower
structures
Unit
intramontane
a
at
the
Cambrian
before reaching
Synclinorium
which end
nides
Westpha-
contemporaneous directions of
Sitter &
in
finally
of the basement
of the
structure
the
Luna
syncline
one
various
over
and
their
Leonides
of the
Major block faulting
folding (de
Lower
dominant
a
Carrion area),
part
replaced by
mined the curved
also
of
eastern
are
eastern
an
the
of coal-bearing sediments.
sequence
from the
area
of Devonian rocks
zone
Barruelo Basins
and
lian-Stephanian
a
River (the
others from undergraduate students
River.
and
which
Westphalian Curavacas Conglomerate plays
Palaeozoic
Luna
Beleno
Cambro-Ordovi-
of Riafio,
structure,
frontal part of the Leonides. Along the León Line Lower
shows
in
mostly
west
variable
more
the
distinguish
can
structures,
western
a
southern border of the
basins. The Luna Zone is
with
of
central Bernesga-Esla Zone and the
a
Ruesga Zone. On
flank
thrust
separated by the León Line.
The Leonides,
we
and
zone
In
main longitudinal units,
two
are
Asturides
the
folds
Alpine deformation."
an
There
coal
In
more
previous
cian and
I like
Cantabric-Asturian
more
the
to
maps.
context
1962: "From the
that
referred
are
course,
series.
account
and
towns
per-
except
the
villages:
people of Old Castille who have welcomed and accepted
the
generations
of
who
have
friends
field
CHAPTER
worked
who
with
geologists
Castillian hospitality.
Those
there
enriched
the
names
the
many
recall
true
experiences
our
famous
rightly
must
and
during
for
all
faithful
the
long
seasons.
2
STRATIGRAPHY
The availability
of Comte's
valuable advantage
cellent
set
plications
major
meant
For
our
mappable
hence
-
point
mapping
rapidly
of
to
of
-
process.
In
does
the
the
sense,
during
to our
of the
course
it
was
provided
an
an
stratigraphical
contribute
same
lithostratigraphic
deposits
as
regarded from the
it
specialism,
another useful tool
Palaeozoic
of
horizons. Our
should be
view:
developing
work
mapping
towards
in-
Sitter's
subdivision
area,
of
the
along the Bernesga River between
fined
one
the
a
time,
the
Lower
(1959)
Palaeozoic
pre-Devonian
Sitter (1961,
and
in
those
the
of
de-
Comte
names
the
of
the
Devonian
derived from reference sections
subdivision of
units (see
Precambrian
were
but
publications either complete the litho-
elsewhere. Later
stratigraphic
formations,
formations
Portilla Formation
existing
Comte
type section
im-
handcraft.
present
a
Busdongo and La Robla. In the type section,
sedimentology,
de
chose
ex-
this
Table I and
this
area
area,
Fig.
remained
1962a) described
an
or
detail the
pre-
1). The presence of
unknown
until
de
angular unconformity
78
in
Herreria
the
the
derlying
called
Formation. He
unconformity
Mora
them
Slates
to
suggested the rocks
be of Precambrian
and
Greywackes,
age
regional geology of the
brian Mountains. Those either reissued with this volume*
Formation.
or
to
used
in
the
compilation
of
Table II. Unpublished work is
The Department of Structural Geology of the
of Leiden has produced
a
number of
map
Southern Canta-
buting
Mora
now
the
un-
and
University
new
sheets
credited
on
are
listed
in
the individual
sheets.
sheets contri-
Thickness
Comte's subdivision
in
(1959)
Formations
Age
metres
houillers
Schistes
et
de
Grès
Tineo
Prado
Stephanien
houillers
Schistes
de Sabero
>150
-
Grès
et Schistes
lacune
-
de Sama
Westphalien
Calcaire
et Schistes
Calcaire
et
Schistes
de Lena
>1000
Lena
San
de Villanueva
Emilano
(Cuevas)
Calcaire
Griotte
des Canons
de
Puente
Namurien
200-800
de Alba
25-40
Viséen
-
'Couches
de
Vegamian'
±
15
de
1' Ermitage
0-1000
de
Fueyo
±
lacune
Montana
-
(?)
Vegamian
-
Strunien
-
Schistes
lacune
de
Alba
(lacune?)
Toumaisien
-
Grès
Caliza
(?)
Ermita
-
100
(Piedrasecha)
Famennien
Grès
de Nocedo
(Calcaires
de
Valdore)
±
500
Nocedo
-
(lacune?)
-
Frasnien
Calcaires
de la
Portilla
50-80
Portilla
Givetien
Grès
et Schistes
de
220-300
Huergas
Huergas
Eifelien
Calcaires
de
Santa Lucia
(Caldas)
100-250
Santa Lucia
Brosten
Calcschistes
et Calcaires
de
La Vid
180-500
La Vid
Siegenien
Gedinnien
Grès
rouges
de San
Pedro
70-170
San
Pedro
Silurien
Schistes
du
50-100
Formigoso
Formigoso
-
lacune
-
Arenig
Quartzites
Schistes
de
Barrios
et Grès
160-480
d'Oville
Barrios
120-240
Tremadoc
-
Griotte
de Lancara
& Potsdamien
(lacune?)
Oville
-
12-25
Acadien
Dolomites
de Lancara
45-80
Lancara
Géorgien
Grès
de
La
Herreria
>1400
Herreria
-
1 lacune'.')
-
Précambrien
Table
1973).
I. Comte’s
(1959) stratigraphic
subdivisions
and
their
correlation
with
the formations
used
Mora
here
(modified
after
van
Staalduinen,
79
Fig.
1. The
Brouwer,
regional
1968).
and local
correlation
of
Upper
Palaeozoic
formations
throughout
the Cantabrian
Mountains
(modified
after
80
The following
the
articles
Table
II. Some of the
and
flysch
ous
has been largely extracted from
account
later research
molasse
Sheets
Map
the
accompanying
in the
has, however,
listed
in
been
incor-
The bibliography presented here
descriptions
map
well
as
as
in
found
in
the
of the
some
The best-exposed
and in the
N-S
Age.
No fossils
Formation of lowermost Cambrian
-
Formation
van
Date
den
W. J.
Bosch,
all
H. J.
1967
and
Santibanez
Frets,
D.
C.
1965
de Resoba
Cea-Esla-Porma*
Heimig,
M.
H.
Brezo
Kanis,
Valsurvio
Dome
Koopmans,
1956
Nansa-Deva*
Maas,
Pisuerga
Nederlof,
Cea-Esla-Porma*
Rupke,
Yuso Basin
Savage,
J. F.
Yuso*
Savage,
J. F.
Savage,
J. F.
Carrion*
Provisional
Map
of the
Slope
N.
M.
H.
J.
to
de
Sitter, L.
Mountains
van
de
den
Boschma,
Isidro-Porma*
Sjerp,
&
colour. This unconformity plane is
the
N.
type
C.
J.
J.
Sheets
this
Structural
published by
Leiden
Geology,
members
of the
De-
(*indicates
upper 5
PRECAMBRIAN
Herreria'
Porma
den
Bosch,
crops out
not
a
long
Anticlinorium, between the Asturian
dalena where Tertiary
The
name
the
arc,
coast
the Narcea
and La Mag-
crop
work
type
has
locality
been introduced by
lies
along
the
de
River
Luna, south of the village of Mora de Luna.
A
number of short articles
Narcea
Anticlinorium
were
on
Mora
red
1969)
out
was
introduced by Comte
the hacienda of 'La
(north of Cerrecedo)
lower part of the
as
forma-
there.
done
Comte
by
(1959),
Lotze
&
Oele (1964).
of the formation is
exposed south of Irede,
Barrios de Luna, and along the Rio de So-
Lotze
-
of
the
and Sdzuy found trilobites in the upper 55
formation
which
characteristic
are
The
-
published
by
of Lower
Julivert
&
by
a
rest
in
weathering
m
places,
does
resembling
not
lie
the
m
is
thick
accenon
weathering
never
where the
on
formed
the
the base of the Herre-
at
though
weathering
10-25
Mora
the
The conglomerate does
the
directly
generally
below
too.
unconformity
zone
thick.
upon
above the base. At places
Herreria is
This
conglomerate
directly
higher
of rocks
Herreria Formation overlies
ria, generally 0.5-3
sent or
the Precambrian in the
red
a
Mora, and
what
metres
be lower Lower Cambrian,
may
always
deposits overlie it.
Mora Formation
(1962b);
of the
north of Sosas de Laciana.
tuated by
1969)
in
m
characteristic
very smooth.
near
although the
section,
Lithology
Formation (van
20
a
was
Valley
Formation unconformably.
Sitter
to
have
Cambrian, hence the hundreds of
volume).
The Mora Formation
Due
reissued
it
Mora
rhyolite
1965
m
of
de
the
The base
Age.
Map
in
south of Los
1973
sas,
of
'Gres
name
Previous
1967
Veen,
with
the
unconformity
Sdzuy (1961) and especially by
Staalduinen,
partment
the
tion does
1966
D.
van
List
1
tuffs
press
J.
&
van
II.
and
CAMBRO-ORDOVICIAN
1968
W.
U.
Cardaho
Table
sandstones
1962
Luna-Bernesga-Torio*
Arriba
Graded
part of the region.
western
1965
in
U.
L.
a
1967
Bosch,
Sitter,
of
rather
conglomerate with pebbles
a
Herreria Formation,
in press
U.
L.
Sitter,
and
are
exposed along the road
are
encountered,
was
especially in the
Herreria'
de
found.
were
their base
(1959), who chose the section
de
the
NW of the
weathering before the deposition of the unconformable
The
Southern
in
and
structures
below
Cantabrian
of the
NE,
of
sets
degree of
non-metamorphic
are
1959
Southern
Pisuerga*
San
the
The
San Miguel, just
Herrería Formation (van den Bosch,
Geological
of the
Cantabrian
towards
1974
Mountains
SW part
diameter
found.
were
of
and
cross-bedding, graded bedding, flute-
Locally,
of Salce.
in
mainly
graywackes
colour. Several
green
Sedimentary
south
occur,
1962
K.
rocks
load-casts
and
a
Rio de
at
1965
J.
B.
Herreria
Precambrian
a
consists
slates,
zones
with flute-casts
cm
Sierra del
the
abundant. Slumps,
casts
Pisuerga
be of
must
the
as
overlies the Mora
age,
Formation
decreases
colour.
grey
Porma*
Southern
knick
of the
mapped,
dark
Mora
possessing
and
course
upper
area
Bernesga-Torio-Curuerïo- Evers,
it
metamorphic
metamorphism
1968
area
Liébana-Polaciones
The
-
slightly
of the Valdéon-
Map
encountered, but
were
unconformably,
quartzites,
1969
D.
Boschma,
of the Ri'o
west
age.
cleavages
Geological
north of Villabandin
occur
mountain chain
detailed
stratigraphic
Author
Provisional
(1968b),
to
very
Luna-Sil*
sections
striking
Spanish
Lithology.
Sheet
Matte
(1960),
Miguel.
monographs also cited.
palaeontological
and
be
can
Lotze
(1967),
de San
has been restricted
Exhaustive lists of both
text.
literature
foreign
and
our
Garcia
Pastor Gomez (1962) and de Sitter (1962a).
Carbonifer-
also
porated.
articles cited in
Martinez
zone
more
but
not
some-
than
8
m
conglomerate is ab-
the Mora, the base of the
by
zone
a
red
silty clay, closely
of the Mora immediately
81
below
it.
rounded
silty
The
basal
10
pink
of red
30-70
and
but locally
the
red
a
region
some
even
5
shales
silty
green
and
found
were
in
and
The
but
cm,
1.5
consists
over
this
tion.
In
cm.
the
western
between
contacts
found
the
laterally
but
subrounded and,
the
is
sorting
may
to
red
and
in
particles
50
upper
coarse
stones;
beds
Lancara
west,
was
more
of
consist
in the
of dolomite
m,
part
silty
the
of
are
were
by
and
From
tion
is
Leonides
in
lying
formation. The best-exposed
and
of Los
west
Age.
to
grains
of
the
sand-
than 50%
the
de
1100
m
along
850
550
Luna; approximately
mately
the
Approximately
the
NW
m
Rio
south of Los
m
of Salce;
de Sosas.
In
Barrios
approxi-
other
areas
base is absent.
middle
Salce;
-
As
-
posed section
Entire
Astropolithon
300
m
above the base,
in
(Seilacher,
1961), trilobites and Scyphomedusa
& Okulitch,
1967) in the upper 50
Lotze
&
the
west
Lancara
tinuity
as
of the
bedding
-
is
formed
is
and the
Barrios
ooids
Next
groove-like
(deltaic?)
casts
lead
in
to
the
in
the
the
poorly
opinion
quartz
overlying
dolomite of
with
about
10
crystals
aftermath of
which produced the
the
unconformity
folded Precambrian schists known
bed
are
comes
3.60
m
shales
thick,
is
80
cm
in
comes
intercalated.
dolomites and black
containing
chert in the
thickness,
a
black
laminated
shale
overlain
dolomite lies
by
beds
alternation of
a
grey
of
composed
lime-
well-de-
laminated limestone
a
thick, with cross-bedding. On the following
bedded
part.
oolites.
fine-grained
locally
This
oo-
some
upper
the
followed by
completely
dolomites
dolomitic
a
common
thick
are
ex-
the Lanca-
to
arenaceous
cross-bedding;
cm
well
very
de Luna suffices.
small-scale
cross-
laminated argillaceous dolomite,
a
dolomite beds
with
intra-formational breccias.
ripples,
Next
cross-bedding
comes
alterna-
an
shales and dolomites with
cross-bedding. These beds
Sdzuy,
thick-bedded dolomites,
con-
characteristics such
sorts
of flute and
sediments of
near-shore
tectonic
the
the
deposition
movements,
of the Herrerfa
to
rather uniform li-
a
fine black shales
medium
and
lithostratigraphic
sorted
of
Cambrian
overlain
are
weathering
to
a
by
ripples
20
typical
m
of
orange-
brown.
The dolomitizationof the limestone (member) is partly
cross-bedding, ripple marks and all
Herrerfa
Middle
thick-bedded dolomite
and fossil fragments, and
After the
and
a
shales.
NW of
(van der Meer Mohr
rock
Cambrian
lowermost
of
dolomitic sands,
by
lite, overlain by
m.
The
and lower
formation:
description of the
of Los
and dolomitic black
of
Depositional environment.
east
Cambrian;
Middle
Member:
lie
of Salce.
west
The gradual transition from the Herreria
ra
and
Animal tracks
shales of the
Lower
lowermost
thological composition,
tion of laminated black
Fossils.
basal
Lower Cambrian
upper
to
Lancara Forma-
important thrust
most
complete sections
Member:
Member:
Sdzuy,
Lithology.
stone,
occurs.
-
the
Meer Mohr
der
van
Barrios de Luna, and
Dolomite
-
Limestone
view
the
importance,
great
the
in
of
point
structural
a
of
van
veloped stromatolites, overlain by
Thickness.
Member.
der Meer Mohr (1969).
pebbles
found than in
more
Griotte
Comte (1959), Lotze
silty
quartzites
most
the
by
& Schreuder (1967), and
1959).
dolomitic
level where
at a
published
Cambrian
dolomites are intercalated. The base of
drawn
Member and
been
now.
Dolomite Mem-
& Sdzuy (1961), Oele (1964),
Authigenic
formation, and
drab-coloured
have
(Comte,
pebbles just mentioned,
shales
Limestone
Accounts
Lower
rounded
are
the
ber,
several
casts
1969)
'Dolomies', 'Calcai-
names
de Luna. The type section is inundated
1961J.
good. Heavy minerals and feldspar
underlying
generally
a
1965).
formation is subdivided into the
&
their base,
the
The
(Lotze
be mixed between the quartz grains.
In the
in
markings
to
and 'Griotte de Lancara', named after the village of
Lancara
0.5
and
isolated quartz
apart from the
sole
point
(van den Bosch,
Griotte
of the forma-
at
Formation
Cambrian;
between
load
thicknesses
The
Pardomino
Middle
distributed
quartzites
and
Small
rapidly.
60
region
clay pebbles
or
Bed
of
undulating. Channels with
ripples
quartzites.
observed.
change
the
intercalated in this part
cross-bedding,
in
of
part
white
beds (up
and
thicknesses
in
metres
thickness
thick
very
sandstones,
bed
of
Comte (1959) introduced the
faults
area.
of
rather irregularly
are
with
grading,
also
in
dolomite hori-
of the
medium bed
a
locally thin conglomerates
were
Lancara
with
alternating
coarse-grained
to
thin and
generally sharp,
are
coarse
embedded
-
This
west
medium
layers
are
Bedding
shales
of
succession
dolomite beds
of
amount
lack of
a
hundreds
drab-coloured
shale
silty
50
and
in the
only
beds,
next.
come
quartzites with
occur;
with
flaser
-
dolomite
also extremely
m)
green
ripples
and
cross-bedding
on
beds
Herreria
southward transport direction (Rupke,
1-2
(generally
smaller
a
places
succession,
overlying
and pink
beds
thick) with
sand
sandstones,
thickness,
shale
formed.
were
could be traced
zon
predominantly composed
are
silty
m
Yellow-weathering
shales
m
green
isolated
material,
Observations
the
remaining part of the
Some slumps
and sandstones. At
clay (linsen)
the
white
res'
red
quartzites
the
of
part
and
of
mainly
in diameter in
cm
found. The
quartzites.
overlying
violet,
m,
western
were
consists
m
0.5-1.5
quartzites.
The
of
the
pebbles
white and
the
pebbles
in
matrix;
rhyolite
consists
conglomerate
quartz
west.
on
the
secondary
origin,
because
it
is
not
restricted
bedding plane: small tongues of yellow-weathered
to
mite penetrate into the limestone layers
perpendicular
the bedding (Sjerp,
van
1967; Rupke,
1965;
the
doloto
Staalduinen,
1973). Sandstone dykes also have been observed.
Well-sorted oolites,
and
subrounded
small angular limestone fragments
sandgrains
indicate
depositional environment (Evers,
a
shallow
1967). Van
der
neritic
Meer
Mohr & Schreuder (1967) concluded intertidal conditions
82
the
from
laminated
algal-growth
(stromato-
structures
lites).
The Limestone Member consists of thick-bedded
limestones,
weathering light
finely laminated. Bird's-eye
filled,
4
m
of
are
Sjerp (1967) reports
ferous,
structures
the
main
grey
often
internally
and cavities,
later
found glauconite. The
colour, and
pink
a
and
grey,
frequent. Rupke (1965)
are
upper
bris.
rich
are
in fossil de-
layer which is highly fossili-
a
of brachiopods
component being parts
and trilobites.
The
Member is
and
fossils,
separated
rial.
the
irregular
red
by
with
contact
contacts
were
with
nodules,
bands of angular fossil fragments
At
as
shales
the
well
find
shales.
is well exposed
In
the
transition
2
of
m
red
greenish,
limestone concretions,
and
few
a
griotte
many
northern part
red
of
colour. There
and
yellow
no-
the Oville Shales
to
the church of Lancara: between the
near
last thick griotte bed and the olive
lie
mate-
Limestone Member
found.
The
parallel
hematitic
nodular limestones
grey-green
grey
thin
well-preserved
as
and
the region the griotte in places loses its
dules in
structures
and
black
weathering
beds
green
Oville Siltstone
shales
to
an
with
green
colour,
orange
also found.
were
the
m
Thicknesses
-
in the Luna
area,
up
150
to
and
cross-bedding
bedding
Next
A
poids.
Stromatolites,
-
concentration of
in the
common
very
trilobites,
broken
brachiopods,
car-
trilobite fragments
is
comes
and
(Oele,
and
The
1964).
The
content.
Micas
Comte introduced the
and
selected
a
type
'Gres
name
locality just
south
d'Oville'
of the
village
of
Comte (1959),
Lotze
&
Previous
work
Sdzuy (1961)
done
was
by
Upper Middle Cambrian B
-
Cambrian (Lotze & Sdzuy,
to
Tremadoc (Comte,
1961);
to
uppermost
upper
Upper
Middle Cambrian
1959).
The
-
will be
and
exposed,
There
is
section
used
thick
A
member
bluish
thin,
the
Oville
consists
finely
of
laminated,
the
finely
and
25
laminated,
silty
micaceous
The
Griotte of
sandstone
ed top,
was
siltstones.
type
Both
conite
grains
a
few
metres
above
cm
A
me-
burrow-
the base
(10-20
or
linsen.
a
m
some
weathering yellow, and several
Thinner sandstone beds
were
the
trilobite
found
50
green
shales with
thick, with planar cross-bedding and often
tres
to
of the
thick)
of
also locally encountered in the siltstones.
sandstones
and
the
siltstones
contain
many
fragments, weathering orange-brown, and glau-
grains
are
of
the
same
colour.
These
typical of the entire formation.
glauconite
have
has
fine
coarse,
much
clay
carbonate
subrounded.
generally
and
bedding planes
sharp
sand-
parallel-bedded
parallel bedding is
gradations
also
50%
even
high
a
silty
(member
relatively
many,
are
the
This
1-15
more
in
cm
and
the
of
typical
occur,
the
upper
lower
are
the
The
very
top, and
does
as
5-50
to
part
frequent in
tracks
worm
beds.
Ripples
the
bed thickness
the
in the siltstones, and also become
sole of the
the
towards
pure.
sand-
increases
in
cm
the
impure sandless
abundant
often concentrated
are
become
more
frequent
at
in
part.
mainly
to
with
D
member
composed
of
gradual. This
important
siltstones
sandstones, sandy
is
sandstones
pure
furthermore
and
member
(often
quartz-
of
amounts
argillaceous
impure
siltstones,
the latter three all of the type described above. The quartzsandstones
the top.
Most
become
of the
lamination
part,
the
and
Flaser
linsen
are
The
unstable
was
have
a
structures,
frequent.
presence
Oville is
without
contact
in the
Especially
erosional
clearly
ripples,
of slump
clay
pebbles
structures
deposits
up-
basis.
found
was
in
and
the
indicates
1967).
(Evers,
drawn below the first
thick
se-
cross-bedded quartzites.
Tuffite beds and dolerite sills,
and
towards
show channelling, and
Loading
character of these
The top of the
abundant
more
also found.
channels
cross-bedding
even
sandstones
quence of thick-bedded,
siltstone of
argillaceous
Formation.
siltstones
argillaceous
sandstone bed,
grey
this
of
well
very
the reference section.
the Lancara Formation and the
member
is
Barrios
transition between
gradual
a
as
Los
sandstones
generally
increase
become
upper part.
near
to
part. Burrows
upper
the
Lithology.
on
the
coarse
sandstones
per
Age.
sandy siltstones,
often
grains
and siltstones.
parallel
and Oele (1964).
member is
internal lamination. The bed thickness and the percentage
of
itic
Oville, in the Porma Valley.
This
layers.
sandstones
cement
quartz
between
member C;
itic),
Schistes
et
the
concentrated
are
contacts
stones
parallel
some
matrix, generally about 15-20% but sometimes
is
1969)
shale
silty
alternation of
an
grains,
quartz
varies
ripples
some
in the sandstones;
occur
are
between
shales
silty
Shallow channels,
drab-coloured impure
The transition
den Bosch,
of the
linsen
sandstones
thicknesses of
C). The sandy siltstones contain
griotte.
Oville Formation (van
bed
thickness
cm.
the
to
towards the top;
Fossils.
with
and
thick.
m
shales
The
common.
sandstone
more
Flaser
B).
however, also found. Burrowing is general-
was,
restricted
ly
stone
area.
m;
between 0.2 and 30
stones
the
over
vary
1.5
gradually
m,
(member
more
0.1
from
Thickness.
become
pure,
and
50
or
generally rather
composed of reddish nodular
limestone
25
intercalated
are
25-40
Griotte
limestones
we
After the basal
beds
parallel
metamorphism,
the bedding,
to
were
found
locally
in the various parts of the formation.
Eastward,
parts
only,
a
the formation
can
be
subdivided
lower shale-siltstone member and
into
an
two
upper
sandstone member (van Staalduinen, 1973).
The lower
and
member is composed of
siltstones, with
glauconitic
limestone nodules in
shales
its lower part.
Upwards the number of limestone nodules gradually decreases.
The
stones
beds.
The shales in this member
upper
and
white
Weathered
ferentiate
the
member is
the
overlying
are
fossiliferous.
of
green
sand-
with
green
shale
mainly composed
quartzites alternating
orange-coloured glauconite
quartzites
of the
Barrios Quartzites.
Oville
grains
Formation
diffrom
83
Thickness.
The
-
430
Syncline:
thickness
of La
west
m,
development of the formation
(some
140 m),
under
conditions
several
eroded
which
In
-
and
long)
member
erosion,
In
planes.
the
Abelgas
Poll
(1963) found this member, and also the thick
The
thinnest
silty
shale
m.
in the Aralla Zone
occurs
upper
allow
bedding
Oville is about 220
Fossils.
the
where
in
varies:
Majua 192
deposited
was
is
shown
Esla
area
as
the
50
trilobites (up
m,
Next
of rock
found.
were
Burrows
and
cm
tracks
found throughout the entire formation.
were
Formation (van den Bosch,
Comte (1959),
Barrios',
who
The
type
section,
selected
Previous
Luna.
the
locality
type
work
done
was
and
Los
near
Barrios
Comte
by
de
'Quartzites
name
de
and
(1959)
the formation
In
three
five
members
members
quartzite
could
recognized:
be
shale
silty
two
by
separated
Age.
Due
-
formation is
that
cluded
and
lack
difficult
it
that the
and Lower
the
to
is
as
of the
an
lies between
top
Armoricanas
the Barrios)
Anticlinorium,
Arenig
Comte
largest part of
of
age
this
surface
age,
silty
km
SW
be
to
of
and
age
the southflank of the
on
50
some
same
Narcea
Upper
an
with
lie,
drawn
below
bedded
first
the
thick
In the
glauconite.
in
tions,
lower boundary
the
SSW
succession
sediments
grained
the
found
were
the
of thick,
last
section
type
of
part
formation
of the
quartzite beds, and above
of
rence
The
-
major
and
crossoccur-
other
Leonides,
between
was
bedded
pure
tensive
loading
and
but
the
quartzite
banks than in other places.
bedding,
ings.
separated
The mica
thin
by
flakes
micaceous
flat
very
of great assistance
in
finding
as
part-
phengite
cross-bedding
ings
thicker
are
ripples
were
are
(in
the
found. Bed
for the silty layers and
and
5
for
m
colour of the
(due
to
are
generally
some
dolerites
Rupke
were
the
also
some
quartzites
white
the
this
or
part-
flaser
and
cm
cement).
or
The
pyroclastic
rocks
In
the
in the
less
tion,
but
brown
thicknesses of
found in the
m
are
silty
clay
frequent
iron
were
on
are
not
exposed
cross-
10
than
This
Aralla
part of the
of member E has undergone erosion
weathering
Thickness.
east
100
or
formed
Burrows
there.
m
near
mem-
Zone.
in
many
thin layer of
concentrations
a
also
are
top of the Barrios.
301
-
in
m
the
further
section;
type
Small thicknesses
m.
have
also
been
350 m
tered in the SW part of the Aralla Zone.
Fossils.
-
burrows and tracks
Only
Scolites
na,
(vertical)
vertical) (Seilacher,
Luarca
Between
shales
rocks
Esla
or
area,
midst of the
exposed in the type
in other places in the Abelgas Syncline, 8.5
grey,
more
micaceous.
very
in-
these
planar
or
of member E
metres
eastern
in
frequently
occur
and
were
to
the
encoun-
in the Esla
found: Cruzia-
Glossifungites
(U-shaped,
1967).
Formation
Shales,
in
the
the
van
west
position
Barrios
den
of the
suggests
Luarca
and
Quartzites
secm
of
at
this
level
(member
B).
Luarca
Cantabrian
they
Formation
Formation,
Especially,
stones
nite,
should
(Poll,
are
impure,
and siltstones,
are
the
Formigoso
Bosch (1969) reports 'transitional beds'
be
common
often
in
pure
more
these
burrowed
containing
a
with
bluish
the
dark
than 90% of the
transitional beds.
ferruginous
large
(van den Bosch,
stratigraphic
correlated
The
1963).
rare
Their
area.
shales, however, which constitute
21
of thick-
cross-bedding
steep
lamination
upper
thin bedded and
and often
The
laminated, silty shales and sandy silts, weathering
or
Bed
pink
formation.
black,
Large,
channels
The
top
places,
place.
occur.
not
erosional
an
At the base,
quartzites.
beds with parallel
are
The
took
with
overlain,
completely composed
some
the
quartzites.
more
member.
(1965) reports igneous
The following
of burrowed
m
of the laminated quartzites,
Locally,
green.
12.5
was
On this
where
lie between 0.1
channelling
is
hematite in
found in
sections)
southern
thickest
Where
present.
thicknesses
concentrations
of member C.
area.
the rock has been intensively jointed. Channels and
steep
present
The maximum bed
often
are
bedding plane
the
cross-
shale
silty
been determined
have
clay
sand-
consists of quartz-
with
or
Dark streaks of heavy minerals
Oele (1964).
by
mainly
lamination
parallel
with
casts,
structures are
contact,
are
uncommon.
was
very
Member A of the formation
ite beds with
Torre
ber
Load
iron
top
on
white and pink
erosive
deep
not
are
sec-
fine-
more
with
member E,
bedding also
Lithology.
are
cross-bedding
channels
section.
type
sharp
a
quartzites
The
m.
shales
silty
by
contact,
beds,
age.
1.5
level
one
shales (member D).
These
Upper Arenig
(of the
about
is
suc-
characteristic
steep
observed.
and flaser and linsen
beds in the
In this
found;
very
too.
with
erosional
been
formed in the type section
con-
the
and
also
is
and
quartzites
rock).
planar cross-bedding and
or
weathering horizon
(1959)
and
steep cross-bed-
were
other sections,
many
have
silty
Arenig
Middle Llandeilo. Nollau (1966) found
or
top of the Cuarzitas
lithology
the
fossils,
establish.
to
for the
age
of
tracks
burrows
lamination
a
ripples
A
and
vertical
direction
one
thickness
members.
in
and
15% of the
channelling, but beds
slightly
in the
alternation
an
alternation of clean
an
burrows
many
occurs
balls,
with
begins
with channels
shales (about
partly have
in
of
numerous
pebbles
Oele(1964).
therefore be traced
can
part of this member is composed, in the
upper
silty
cession
1969)
introduced the
member C; it
comes
ding.
green
levels
types of the type encountered in member A,
quartzite beds
with
Barrios
these
NNW;
great distance.
by
10
to
the
to
a
pure
basal
carpoids
km
the
m.
the
50
over
upper
member, in the Belmonte region of Asturias,
amount
sand-
of glauco-
1969). The thickness
84
rapidly decreases from
170
a
of the Luna the beds
east
According
tions
Evers
to
between
boundary
the
are
in the
m
(1967)
the
Barrios
and
exposed north of Felmin,
as
of the
west
area;
found.
not
sharp,
undulating
Formigoso Forma-
represents
a
ed, white
portant hiatus
mation,
after
is
the
deposition of
of
the
of
occurrence
doverian graptolites
the
at
the
base
For-
His main
shales
and
Formigoso
Corral Formations.
The
introduced the
goso'; the type locality lies in the Formigoso
of Villamanfn in the Bernesga
work
Previous
SE
Valley,
Kegel
(1929).
black,
to
grey
have
the
been
Lowermost
(Comte,
thick and
the
of
Lithology.
Upper Llandovery
Upper Wen-
to
Formation.
lower part
The
-
of these
shales
detrital quartz
is
sharp
a
On
contact
Riolago.
in
the
constitute the
ripples
rather
are
the
these
0.5-3
the
tens
of
in
frequent
thickness in
load
shales have
at
of
tens
at
were
pure
the top
A
the
clay
the base
is
only be deduced indirectly
can
In
contrast
correlate the Robledo with
we
the basis of
on
the
lithology,
high-
at
is
-
due
casts
first
a
more
abundant towards
metres,
rock
intercalated.
are
sandstone
type.
beds
beds
Burrows
which
and
have
a
lateral direction. Locally,
In
occur.
with
black
they
metres
graptolite shales,
the
upper
cross-bedding
or
grey
become
colour,
more
ten
occur.
dro
Middle Silurian
to
Formation
the
and
a
more
intensive folding, especially of the finely
de Luna,
now
exposure
Previous
Age.
León
is thus
(Comte,
most
work
'Gres
name
near
pro-
de
San
was
there along
done by
Pedro'
the village of San Pe-
inundated by the Luna Lake.
exists
Upper
-
Lithology.
the
new
Backer
A
new,
road.
(1959) and Comte
Wenlock
Lower
to
Gedinnian
(Comte,
The San
-
in
the black
shales;
brachiopod
in
the
part.
upper
a
few grapto-
A.
The
B.
basal member,
The middle
Formation
consists
of
with
composed of thick red
channel-
red
and
alternation of
an
greenish sandstones
with
he-
matite and chamosite ooids respectively.
C.
The
composed of
upper member,
white quartzites and black
A
Member
sandstone
sandstones,
green
and greenish
shales,
such
beds of the Formigoso,
of
this
up
to
4
m
a
thick,
and
a
ooids.
intercalated.
chiefly
cross-bedded
thin layers of
lower-
chamosite
encountered
member consists
first red
The
rather high percen-
containing
as
are
and
of the
appearance
hematite
containing
generally thin,
are
alternation of
an
shales.
begins with the
bed,
beds
green
in
the
ooids,
upper
The entire
of
red,
re-
thick-
sandstone beds,
shales
or
silts,
and
thin greenish sandstone bed. The red sandstones
mainly
quartz
sandstones
be subdivided into three
member, composed of
shales and
green
locally
1974)
can
ling sandstone beds with hematite ooids.
are
Robledo Formation (Ambrose,
Pedro
members:
mainder
Graptolites
Robledo
age
(van den Bosch, 1969)
type locality
bedded, channelling
-
Beds of Asturias (Poll,
Formation of
(1959).
but in
and
laminated shales.
Fossils.
Furada
Pedro
1959); top: Lower Gedinnian (Brouwer, 1964, 1967).
The variation of thickness in the Formigoso
to
San
1).
and selected
tage of
The
overlain
sequence
thickness.
true
Comte (1959) introduced the
most
Thickness.
lites
exposed
or
of the
green.
partly
Abadia For-
the lower limit is faulted this is
strata
(1974)
Lower
San Pedro
of the
markasite
also found
black
these
a
thick sandstone beds
upper
small
some
thin
a
in thickness
cm
important
most
well-developed
The
of the
just
these
shales.
upper
very
constant
metres,
components
A weathering
often found
These lenses become larger and
top;
main
with
contact
this
the basal layers of
sandstone lenses
the
indica-
most
good
exposed.
levels in the black
Above
the
are
micas and
clay minerals,
are
Formigoso. Markasite and pyrite
er
exposed
of
shales
grains.
found south of
was
shales
formation. The
iron concentration is
an
carbonaceous black
These black
places
many
Barrios
of the formation consists
finely laminated,
very
layer
is
conformably
The
Formation of León
Formigoso
1959).
sediments of the
In
recrystallized
because of the absence of identifiable fossils.
1969) and
1959).
with graptolites.
tive
shales
Robledo is
although
near to
age
bable (Fig.
pure,
probably
section
only,
thrust
Upwards
Arroyacas
The
and
pyrite
The interbedded
taking into consideration the correlation of the overlying
-
lock
with mica
euhedral
together with
Arroyacas with the lower
Age.
Shallow
haematite ooliths.
practically
with Ambrose
Comte (1959) and
sequence.
over
Formi-
Valley.
done by
was
du
Sorting
detected, and ripple marks
as
finely
are
quartzites.
rocks
probably
'Schistes
name
beds
base,
tending
m
sign of cleavage has been found.
no
best,
160 m
Comte (1959)
1
VII: Carrion Sheet) where
by
Formigoso Formation (van den Bosch, 1969)
dark
to
north of Lebanza (Encl.
mation.
SILURIAN
well
the
near
cm
of the thicker
some
common
as
are
although
10
medium-grained
to
be
can
are
haematite,
Upper Llan-
same
of the
im-
an
Barrios
the Luarca Beds in Asturias.
equalling
argument
the
existence
calcareous
from
vary
improve upwards in the
to
channelling
coatings
concluded the
fine-
laminated,
also tends
noncon-
quartzite pebbles.
Comte (1959) also
thicken upwards,
to
and
silty
some
bioturbate. Beds
usually
which is marked by concentrations of well-round-
formity
shale partings,
grains
thickness.
composed
often
The
with
of
a
rounded
hematite
hematite has
often
or
well-rounded
coating of
varying
replaced the original
85
At several
cement.
pebbles
they
containing
proximately
level,
6-15
with
diameter
1959;
den Bosch,
van
Burrows
nes.
in
occur
are
the
show
are
not
(Backer,
Member B
oolitic
with
in the
common
the
at
in
of
4
to
up
Some
but
sharp
direction
lateral
a
rapidly.
very
sandsto-
generally
Bed-thicknesses
most
oolitic
with
is mainly composed of light
iron
hematite
stronger than
The bed
with
of
1
thickness
thickness
very
for
does
prints
are
of the
beds
quartzites,
beds.
found
contain
to
rock
coarse
debris
a
quartzite
beds
of
and
show
of
found. Shell im-
and
grains
the
white
shales,
or
yellowish
quartzitic
sandstone
lamination,
or
ripples
which have
burrows.
They
iron
high
a
Vid is
black
however,
only
have
30%
often
were
and
percentage
and
pebbles
The
fossil
west,
some
nesga area,
al
200
presence
of
the
contain
often
contain
a
70%
cement
but
and
more
at
the
dolomite.
of
quartz
resemble
a
thickness
varies
in the Luna
a
180
of the San
m
150
from
area,
a
100
in the Esla
m
underlying Formigoso
in the
area.
Pedro Formation
in
m
In
as
the
Ber-
gener-
well
as
Formation decreases
towards the north.
Fossils.
and B;
-
The
In general,
of the
the
these
Van
with
western
San
is
area
formation
(1965) correlates his
Pedro
not
1966)
nappe
other
areas
Veen
the
Carazo
of
the
Comte
ferruginous
as
the
as
sequence is
shale-sandstone-quartzite
correlations
area
nappe
of the
formations with
mainly based
are
biostratigraphy (Fig.
those
comparison of
upon
1).
Arroyacas Formation (Ambrose,
The
Brachiopods
brachiopods,
Formation
Arroyacas
often strongly
stones
horizons
is
and shell
imprints
crinoids and
1974)
mainly silty,
mud-
sandy
bioturbate, interbedded with
of splintery,
layers of sandstone.
blue-black
The
shales and
sandstones
are
fewer
even
more
few
a
frequent
and cleaner towards the top of the formation.
The
section
type
by
than
more
north of Lebanza is
100
attributed
merly
the
Carazo
Fossils
The
m.
this
to
Formation
(1965), is
m
by
Member
order
an
abundant and
not
for-
plus
m
of
a
and
Binnekamp (1965)
wrong
but
error
of 75
called
sequence
continuous
not
be in
may
thickness
by
certainly
relatively
are
in members
bryozoans
and
orthocones
The
age
mation
is
van
of magni-
include
brachio-
fixed
Ludlow Stage
brose,
San
turias,
the
by
in
are
determination of
them
of the
This
1974).
characteristics
the
graptolites.
of the uppermost beds of the Arroyacas For-
found
graptolite
which
the
Upper Silurian (Rickards
considered
Pedro and
guide
a
to
belongs
dating together with
in
Am-
lithological
the
correlation with
justify
to
form
Lower
Furada Formations in León and As-
respectively (Fig.
Formation
Carazo
the
generally gradual:
shales
of dolomite
and again
the thickness
that
m
used.
the
much alike.
very
van
1).
The
A
in member
C; burrows and tracks throughout the entire formation.
(Ambrose,
Carazo
defined by
ber,
Formation
1965;
parallel
ironstones
phosphorite
a
Ambrose
of the formation
c
Quartzite,
deposits,
quartzite.
where
modified by
as
Binnekamp and
the Carazo
ironstone
The
1974; Binnekamp,
Veen, 1965)
prises the members b and
true
The
been
Formation
usually
-
of
stratigraphy
In
(Koopmans,
area
(de Sitter & Boschma,
often gives
particles
carbonate rock.
Thickness.
Valsurvio
area
pods, crinoids, trilobites, pelecypods, bryozoans, corals,
level where the beds adopt the appearance of
rocks,
the
San Pedro but
tude.
dolomitic cement. The base of the La Vid lies
These
the
Pisuerga
stratigraphy.
Veen
appearance.
the La
to
bed
internal
an
phosphorite
speckled
in
the
rough outlines.
Carazo
ripples
of laminated black
distributed ferruginous
The transition
in
only
structures
Current
linsen
were
cross-bedding
levels
cm,
the
Laterally
(brachiopods, bryozoans, crinoids).
the quartzites
more
balls
5-10
greenish sandstones,
much.
quantity
fragments,
of irregularly
and
resembles
is
cement
generally
flaser and
disturbed by
locally
very
than in member A.
usually
and sometimes also
been
the
dolomitic quartzites
These beds
often
is
(chlorite)
original
the
very
mainly
minor
a
red
ooids),
shales. Replacement
silicate
sandstones.
are
common
grey
often
grains,
quartz
sands is
change
as
or
grains,
silicate
green
for
cm
red
consists
generally
how-
of
stratigraphy
1962)
and the total thickness of 350
Locally slump
Member C
and
the
not
more
the
thick
A.
in the
abundant,
and burrows.
of
of
replacement
in member
m
m
very
green
quartz
(iron
iron
by
maximum of 50
a
and
and
coating,
cement
this
common;
coating
consisting
sandstones,
a
of
consisting
silicate
of the original
AND
frequent.
sandstones,
an
The
names
are
internal structures,
very
a
in
cm
channelling, cross-bedded sandstones. Ripples,
ever,
are
4
to
sections
several
sandstones;
changes
no
Ap-
of member A, such
up
EASTERN SHEETS (YUSO, CARRION
PISUERGA)
coarse
of hematite.
pebbles
found
contact.
red
sorted,
badly
1969).
only
were
thickness
beds
in
and flakes
sandstone-shale
bed
phosphorite
encountered
Clay pebbles
in
amount
from the base
m
coarse
was
concretionary structure;
a
large
a
phosphorite grains and
coarse
concentrated
often
are
sandstones
levels
frequently with
occur,
Veen.
van
is
The lower
medium
are
laminated but
with
pellets
to
a
grained,
cross-bedded.
hematite
of
typical
higher proportion
cemented
coarse
sometimes
occasional
are
to
mem-
sandstone and
typified by
the thicker beds often
They
com-
originally
as
ooliths
thinner
and
sequences
of interbedded shale
is
to
be
found.
The
upper
member (c of
Binnekamp
van
Veen) is
silty
in
lower part,
becoming
calcareous
upwards.
The
brown-weathering,
splintery
shales
interbedded
are
with
weathering, well-stratified,
the
and
predominantly shaly;
darkgray,
thin
grained sandstones. The shales
to
are
yellowishbrown
medium bedded fine-
noticeably
less
mica-
86
than
ceous
tion,
and
tailed
are
those
the
of
the
underlying
sandstones
of
brachiopods.
especially
abundant in
casts
Fossils
the
Forma-
Arroyacas
decalcified
typically
with
throughout but
occur
member in
upper
which
brachiopods, lamellibranchs, ostracods, trilobites, pteroand
pods
have
gasteropods
been found.
small
Carazo
where
the
present,
to
less
total of
a
100
well
as
section
400
than
more
B
member
area,
total of 200
a
area
of the members
is reported
A
m
279
and C
m
its
as
of
m
at
Pena
strata
are
rapidly north and southeast
often
Fossils.
in
Brachiopods,
-
member
A;
crinoids,
member B; crinoids,
corals
and
and
Binnekamp
age.
DEVONIAN
top
Formation
(van den Bosch,
introduced
de La Vid'
and
the
'Calcaires
name
selected
section
type
a
Calc-
et
of
east
Gedinnian
Emsian
Middle
to
can
schist
in the
and
top,
on
b.
slates
Sandy
grading upwards
Valley.
ous
Shale
1967).
Vid Formation has been subdivided
Member (B)
and
a
middle Calcare-
upper Crinoidal
an
Lime-
Member (C).
stone
A
The La
-
lower Limestone Member (A),
to
member
however,
an
A
of the La Vid. At several places,
erosional
has
contact
been
gradual transition from the San Pedro
to
found.
In
a
the La Vid, the
thin, white, dolomitic and slightly cross-bedded quartzite
beds in
the
predominant black
with
sandstone
ternate,
lomite) and
upper part
often
with
mica
of
Baja
black
ous,
and
fossil
Luna
shales,
the
olive-green
(largely
is formed
detritus
thin shale
by
and
beds
with
occur
the
grains;
colour. Due
latter
to
member
is
do-
sepa-
parts of the
of
very
the last
calcare-
fossiliferthick
of
very
lime-
sal
detrital
probably
tectonic
several thin, very fos-
limestone lenses
give
with
a
red
shales
to
establish.
calcareous
shales
strongly
limestone
lenses,
1965;
of
calcarenites
coarse
crinoid
same
occur.
at
nation although cross-bedding and
also
broken
A
pods.
with
the
the
distorted.
though
the base. These
horizon of
even
with
slumped hori-
a
common
poorly
ba-
lami-
usually
are
into
pass
brachio-
preserved
white, thin-bedded limestones
pure
well-preserved brachiopods forms the transition
most
characteristic thick
formation. The
of
fauna is
less
and
stromatoporoids
extremely
an
chiopods
rich,
to
massively bedded part of
to
abundant and
consists
corals.
rugose
permost part of the formationis of dark
with
Veen, 1965)
of limestones;
these limestones
Upwards
limestones
shaly
more
Fossils
occur.
or
van
basically
usually medium bedded with parallel
are
well-preserved
The
up-
limestones
muddy
together with lamellibranchs,
fauna
of
bra-
tentaculites
and
gasteropods.
Both
are
the
and
upper
conformable and,
lower
in
dia and Carazo Formations,
at
the type
section
been
tectonically
fossiliferous
to
gradational, with the AbaThe thickness
respectively.
Lebanza, of 160
near
the maximum although
of this formation
contacts
fact
many
m
other sections
truncated.
is
probably
seem to
formation
The
to
seem
thin
out
in those
have
almost
the north and northwest, and the
levels
more
directions
too.
The abundant faunas
Gedinnian
to
yield
determinations of
uppermost Siegenian
Upper
ages.
Abadia Formation (van Veen, 1965)
The Abadia Formation is
pink,
percentage
of
their
disturbance the thickness
high
very fossiliferous.
occur.
grains and iron sithese
chloritoid-
a
soil
limestones.
well-sorted,
strata
certainly thins
fine, often splintery,
debris; furthermore greenish limestones of the
and
by
fossils,
large
detrital,
generally difficult
limestones
green
detrital,
limestone beds,
Member C is mainly composed of red and
detrital
dolomites,
some
metres
contain small pyrite
green
of this member is
In
between
mainly
Several
licate
al-
shales of member B.
green
The shales often
by
several
calcareous shales with
siliferous beds.
thick,
cm
replaced
intact
or
beds.
Units,
locally
Member B consists
and
and
more
grains have been observed. The
member A
much
limestone
stones
flakes
pyrite
some
rated in places
Babia
60
to
up
interbedded with dark shales. In
grains,
quartz
limestones
with
a
and
Lebanza Formation (Binnekamp,
mainly
Dolomite beds and
ous
shales become
dolomitic.
more
members, from
into black slates.
Coarse crystalline
zon
gradual transition takes place from member C of the
San Pedro
three
locally
The Lebanza Formation consists
a
of the Valsurvio
centre
(Comte,
1959); Middle Gedinnian to top Emsian (Brouwer,
into
in
in member
weathered red-yellow sandy shale.
a.
Lithology.
corals
bottom:
to
sericite
1969)
of La Vid in the Bernesga
Middle
and
crinoids
and
(?La Vid, Koopmans, 1962)
out
Light-coloured slates and phyllites,
c.
-
or
Brunton (in
be subdivided into
Age.
as
well
diminished
are
brachiopods
Dome and
village
well
as
bryozoans
crops
the
In the Esla
m.
nappe
trilobites
brachiopods,
This formation
schistes
con-
the west
absent.
Compuerto
Comte (1959)
in
the autochthonous. In general the middle member is
tion is of Gedinnian
Formation
varies
m
C.
m.
faunas identified by
Vid
158
found in the
are
Ambrose, 1972) show that the redefined Carazo Forma-
La
380
some
through the relatively
rapidly
From the type
formation thins
than
The
varies
of its outcrop.
area
of the
thickness
member
siderably:
developed, members A and C
The thickness of the Carazo Formation,
members and beds,
The
-
de-
type,
This
though
two
veloped
shales
as
are
levels
to
have
essentially
of limestone
been
remarkably
despite the tendency
to
are
a
distinguished
siliceous,
shaly interval al-
sufficiently
silty
as
well
de-
members. The
and
nodular limestone
even
sandy
deposition
all levels. The lower, Requejada Limestone Member is
at
a
87
limestone
dark, thin-bedded, silty
into
upwards
ses
dular, limestones. The
and
gradual,
The
and
the base which
wavy-bedded
the
to
passage
nodular
throughout the
at
lighter-coloured,
limestones
Limestone
Upwards
bedding becomes
terbedded with shale
being
nodonts
in
cially
the
particularly
Polentinos
brachiopods,
complete the
be
in
and
pteropods
(Kullmann, 1960;
the
have
enabled
Abadia
(espe-
datings
numerous
Formation
Upper Siegenian
van
is
known
to
(lower?) Eifelian
to
Adrichem Boogaert,
1959) is found
(Comte,
in the
1967).
banks
of the
lower Bernesga
1967)
Santa
in
Valley,
the
Ber-
Lucia
Formation
resistant
are
Huergas Formations.
Because the
general lithologic
pects of the Santa Lucia Formation
Van
part
The
four
quite uniform,
are
limestone
prevalent
the
reddish
a
members
A
The
are
5
irregularly
thick
m
the
precedes
tercalated
stromal banks
colonies
scarce.
The
to
pears
be
argillaceous
black
of
Vid
to
56 m
Santa
of
Lucia
(30-40
m),
marl beds
which
is
com-
built
up
The
bio-
of well-cemented fossil debris
stromatoporoids;
varies
lenses.
in-
corals
rugose
These correlations
Otero
dolomitization and silicification
to
authigenic chert
the bedding plane also
considerably
of Aviados, and
from
even
90
24
m
This
Formation
Otero
consists
reddish-brown
of
Formation consists
of
five
directly
distinct
in
is
detrital
concentrations
Both formations
upper
brachiopods,
biostromal
action and shallower
limestone
of
m
gatus in the
the
as
age
water
40
depth.
are
bed
La
separated
(ca.
the
as
8
m),
greater
Emsian
age
Comte.
Smits (1965) proposed
the
Coo (1974)
cies
the
section
type
the
regards
been found in the
not
of
east
Caldas
1969)
Caldas
name
Formation and
Caldas
m) overlain by
fourth limestone
of
light-grey
dark-grey argillaceous
The
Luna.
De
another fa-
as
best
exposures
Puerto de la
to
Cubilla.
Age.
Upper Emsian
-
Lithology.
A
-
Smits
(1965).
black,
pink
and
Lower Couvinian (Smits,
to
detailed
The
and
red
nodular
than
1965).
of
of the
used
Fossils
stromatolites
sandstones
and
found
were
detrital
in
grey,
the
colours.
marker
is
much
beds.
higher
abundant
so
bird's-eye
limestones
of
same
as
not
are
Santa Lucia. Filled-up cavities,
given by
of them nodular,
material
terrigenous
in the Santa Lucia.
the
be
can
been
consists
some
sandstones
limestones
The percentage of
Formation
limestones,
and
has
description
Caldas
shales
marls,
Red
limestones.
often
as
structures
show
The
cross-
bedding.
Due
to
the
tions and the
that
this
pre-Ermita
upper
uplifts,
the
overlying
forma-
part of the Caldas have been eroded;
erosion
a
karst
landscape
formed
was
so
cavities, filled with red ferruginous sandstone of the
Ermita,
east
occur, even
at 50
m
below the
-
The
a
reddish
upper
part of the
North
of
unconformity.
more
have been
a
region
than
m.
600
Further
m
formation has
Caldas
of the Arroyo de las Rozas 228
Unit,
gas;
member consists
de
Formation
of the Santa Lucia Formation.
de la Cubilla 382
composed
rich
Spirifer cultriju-
zone
lamelli-
indicate
An
Otero Lime-
rich in corals and stromatopo-
are
of León, has
province
it
separated by
The Santa Lucfa limestone
Caldas Formation (van den Bosch,
and
biosparites (50-60 m).
The
layers
Otero Limestone.
apno-
occur.
near
brachiopods,
blankets
The third limestone member is
biomicrites (ca.
of calcareous
of the Santa Lucia Limestone,
zone
Thickness.
determined by
Koopmans,
south of Otero de Guardo
same
and known
eroded everywhere.
wave-built
a
map.
content.
principally
limestone
of the
These
was
fossil
with
his
to
Lucia Formation,
(?Santa
branchs, gastropods, rugose corals and stromatoporoids.
wave
Santa Lucia
according
upon
shales and calcareous shales.
during
a
based
are
of the Rio Carrion,
in
N of Voznue-
The second and third limestone members
by
the
Formation,
1962)
are
vo.
consisting
correlates
(1965)
Abadia
yellowish-
shale and
shale
post-depositional, but
N
the
limestones
of
zone
bituminous
irregular
thickness
of
limestone member,
dules elongated parallel
The
base
gradual:
bedded biostromal limestone banks
are
of
155 and 230
intercalate
dolomitized.
second
by
the
member consists
transition
posed of thickly
and
at
lower
thinly bedded
grey,
which
La Vid Formation is
detrital limestone-lenses still
limestones
grey
his
exist NNW of Caldas and along the road
transition from the
Formation.
Veen
of
selected
as-
could be made.
several
total thickness
to
flanked
resistant argillaceous beds of the La Vid and
differentiation into
speci-
indicate the
m.
roids. An
the village of
at
weathering, and thus form well-exposed ridges
by the less
large
Formation varies between
of Comte (1959)
Sheet (van Staalduinen, 1973). The massive limestone
nesga
of
co-
lamellibranchs
Santa Lucia Formation (155-230 m) (Evers,
Santa Lucia
The
arena-
bryozoal-lime-
a
cultrijugatus
Couvinian.
or
thin-layered
a
Concentrations
m).
of Spirifer
cm)
the Santa Lucia
stone.
The type locality
7
to
m) and
m), separated by
sediments, showing great lateral variations. In the valley
faunas
and
from
age
are
Member) together with corals,
ostracods,
made,
range
Trilobites
in-
faunas.
The extensive
to
Fossils
goniatites and
important.
(4
mens
10
2
layer (ca.
stone
15
(ca.
part (ca.
ceous upper
and
common
sequence.
limestones,
the
medium-bedded,
until nodular limestones
wavy
complete the
throughout
common
confor-
grades
becomes
pyrite
detrital lower part
top of the Emsian
Member
mably from the shales below becoming
the
recur
of the shaly interval.
rest
Polentinos
detrital bands.
no-
shales is
overlying
detrital
pas-
to
to
224
m,
m
and
the north,
near
in the
of limestones, marls
measured between the La
Vid and
been
remained,
and
Puerto
Sobia
shales
the Huer-
considerable part of the formation in the present
must
therefore have been eroded.
88
Fossils.
crinoids,
Brachiopods,
-
corals,
branchs and
bryozoans,
ostracods,
gasteropods, stromatoporoids, Algae,
lamelli-
in
den
Huergas Formation (van
The
'Gres
name
(1959), who
Comte
by
Schistes
et
in
village of Huergas
Bosch,
de Huergas'
selected
work
section
type
a
introduced
was
the
near
carried
was
black
Comte
by
out
slump
Upper Couvinian and
Lower Givetian
(Comte,
The
-
Huergas Formation consists mainly
micaceous
and
carbonaceous
drab-coloured, decalcified, argillaceous
of
shales,
and
sandstones
with
silty
In general the Huergas overlies the Santa Lucia with
sharp contact, but according
is
transition
not
to
Bosch
den
van
After
uncommon.
concretions
clay-ironstone
and
lated.
sometimes
The
versa
is
beds
limestone
from
transition
sandstone and vice
few
a
shale
silty
some
sandstone
interca-
are
to
a
gradual
a
several
follow;
a
(1969)
transition from the Santa Lucia, mainly shales with
beds
argillaceous
of
burrowed,
are
occasional
very
Sandstones
found.
the
In general
very
iron-
decalcified
are
few fossil-rich horizons
a
con-
siltstones,
arenaceous
quartzite.
ferruginous, occasionally
formation is slightly
layers
sandstone formation
a
siltstones,
shales,
silty
sandstones, and
rich
100
dark
of
m
consist
sequence
The
recognized.
of
In
10
50
upper
alternating brown
10
m.
Casts of
m
White
of the
m
brown shales
The
this
and
20
upper
concretions.
badly exposed
sandstones.
to
The
casts
cover
of the
m
sandstones
mudstones, with cross-bedding in the sandstones
uppermost
mo-
brown
load
tracks,
contain
also
and
quartzites
occur
a
is composed of thin-
m
animal
could be
with the
Compared
ley,
the
and
of the
have been found
brachiopods
and
typical.
are
section in the Bernesga Val-
type
Piedrasecha Formation shows
liferous limestone concretions
lent
part
of
the
of
formation,
sandstones and the
However,
contrast
Villas.
coarse
between
contact
could
contact
comparable
a
The
the
upon
the
brown
Ermita-like
the
which
there,
near
have
very
are
be
not
sequence
shales
sandstones
upper
layers,
the Ermita Formation of
The lower limit of this
underlying sandstone/shale
sharp
a
to
to
equiva-
The
sandy
more
and
the fossi-
be the
to
elsewhere.
showing
should perhaps be correlated
should be
is likely
Formation
Huergas
the
shales
more
lower part of the section with
The
mudstones.
the Bernesga section.
gradual.
Huergas Formation is
sisting
of
m
and sandstones form the following
and 30
sequence
The
160
alternating with shale beds.
sequence
quartzites
sequence.
beds
ferruginous
in the mudstone beds.
burrows.
gradual
the
formation. Then follows
about
sequence,
structures
this
the
black
the
often fossi-
are
of
part
thin
of about
sequence
sandstones
section,
1959).
Lithology.
basal
thin ferruginous sandstone beds.
shales with
of
part
of
sequence
following
of
-
the
lower part of the
this
layered
(1959).
Age.
in
especially
notonous
1969)
the Bernesga Valley.
of the previous
Most
The limestone concretions
common.
liferous,
Apart from the concretions,
of Spongae.
spicula
are
quartzitic
sequence.
observed
been
in
de Las
Santiago
deposited
different from
the
sandstones of the Ermita Formation
transgressive
in the Bernesga section.
Thickness.
m
are
den
from
m
the
area
In
area.
lower
100-150
Esla
the
(1965), the thickness is
up
area,
than
more
Staalduinen
Bernesga
the
(1967) only
Porma
Van
1969).
Bosch,
the
Luna
upper
150
reported, from the Abelgas Syncline
200-300
Evers
the
From
-
m
(1973)
reports
to
exposed in
are
Nappe, mapped by Rupke
to
240
m,
and
320
to
up
Thickness
m
in
Gustalapiedra
The
and
pods,
Abadia
and black
wards
Crinoids,
brachiopods,
cephalo-
bryozoans,
are
Piedrasecha Formation (van Staalduinen,
Formation
Staalduinen for the clastic
rocks
deposited
on
top
was
sequence
of
the
introduced
sequence
Bernesga
is
Valley.
present
The
from
Lucia
Santa
secha with the Nocedo and
arbitrary.
change
near
It
is assumed
between
these
Piedrasecha has
thickness decreases
The
shales
type
in
section
which
Portilla
three
van
Formation
This clas-
Luna
the
Ermita Formations is
that there exists
a
formations.
been chosen
to
de
boundary of
western
by
of mainly Devonian
as
type
to
the
Piedra-
purely
with
The
Carrion
and 70
A
are
area
which
A
200
have
concretions of claystone
and
of
of these
the
is
rocks
also
development
in
few, thin, lenticular beds of
is
less
in
total thickness remains
fauna
of
yielded dates
Boogaert, 1967).
m
lime-
while
pyritic,
cleavage
limestone
(Kullmann in
trilobites,
the
eastern
between 50
goniatites,
gasteropods
from
van
has
later Eifelian
Veen,
1965;
cono-
been
van
to
found
Upper
Adrichem
The
Portilla Formation (Evers,
about
overlying
of chloritoid and sericite, in
the
lamellibranchs and
The
section
the
m.
Givetian
locality.
of
but the
specialized
donts,
with
interbedded with the limestones and slates.
proportion
lateral facies
the E.
starts
sandstone
and
appearance
by
the
dark-grey
black limestones. Up-
contact
crystalline
The
influenced
alternating
Cardano Formation. The
crystalloblasts
section.
of
argillaceous
gradational
overlies
conformably
consists
highly deformed sections.
1973)
along the southern limb of the Alba Syncline.
tic
a
medium
slates contain
the type
corals.
Piedrasecha
It
slates and
there is
(van Veen, 1965)
Formation
Formation.
strongly
The
m.
Formation
Gustalapiedra
stones
-
600
nodular limestones of the
the autochthonous.
Fossils.
to
up
(van
according
and
m
300
brown
limestone
The
type
location
(Comte,
bank of the Portilla brook,
1967)
1959) is
W
found
on
the
right
of Matallana-Estación (see
89
also
1972). In the
Reijers,
be
easily
can
separated by
members
limestone bed.
to
to
top,
resistant
developed
both sides.
on
section
grained,
few
goniatites
The
SW
of
Aviados
be
to
Thinly layered, coarse-grained
a.
in
ranging
ing
red
colour
corals
tary
aspect.
from
yellow
and crinoids
Cross-bedding
to
weather-
but
grey,
of
this
give
member
parts
rich
are
Aviados:
flank
reef-building fossils.
in
Torio-section:
15-30
50-60
of
NE
m;
San
The
5-15
compound
Thickness
stromatoporoids
in
the
to
corals
the
SW
bioherms
contrast
rugose
massive
Adrian and
In the latter sections,
m.
have developed. In
deposits
Lucia Formation,
but
limestones.
blue-grey
Well-layered,
stones.
The
of
with
Santa
abundant
are
of Aviados,
5
a
thicker
total thickness of 40
d.
Massive,
lenses:
and
stones
bryozoans,
reef
calcareous
lenses
limestones
account
and
biohermal
the
with
calcareous
SW
brachiopods and
Formation
introduced
'Schistes
up
mined
The
shale
few
dome-shaped
few
a
silicified
Partly
lime-
corals,
stromatoporoids
10-25
are
Upper Givetian
as
the
can
from
10
have
allowed
ranging from the
as
Nocedo
1967).
Formation
The
1969)
'Gres
names
Because
de Fueyo'.
the
de
Nocedo'
Shales
Fueyo
and
have
they have been included in the
the Fueyo Shale Member (Evers,
as
locality for the Nocedo Formation lies
type
in the Bernesga
Valley,
near
the
village
of Nocedo; that
of the Fueyo Member in the Arroyo del Fueyo,
Previous
the
and
Lower
work
300
a
Nocedo
m
Devonian section
ites
Frasnian
deter-
500
and shales
is reduced
Estación,
tribu-
a
to
350
(Comte,
by
of
calcareous
of La
NE
m
Comte
Upthe
near
lower Bernesga Valley,
sandstones,
measured. The
In
Syncline
complete
most
where
quartz-
Formation
Nocedo
in the Torio section
m
250
to
The
described
was
m
were
towards
the
become
coarser
Matallana-
near
Valcueva, and
Pardomino Ridge,
Lower
-
(1959).
175
about
San Adrian. From the Bernesga and Esla Basins
near
Age.
Comte
by
out
out.
crop
Nocedo in the
approximately
m
carried
was
only in the SW limb of the Palomas
west
and
increase
and limestones (Evers,
m.
of the Portilla Formation is
age
level
vary
Adrichem Boogaert,
(van den Bosch,
only been found locally,
does
a
The total thickness of the Portilla Formation is generally
m.
observed
Upper Frasnian (van
to
Comte
per
well-bedded biostromal
shales.
with lenses of reef debris. Thickness:
200
separate hiatus
no
thicknesses
conodont faunas, in particular,
Nocedo
for
Yellow-weathering, calcareous shales and sandstones
to
overlying
condensation of
1967).
sand-
found.
e.
while
m.
village of
Locally,
m.
interfinger
structures
biostromal
but
m,
m.
light-grey
40-60
10-25
generally
thick coarse-grained
m
and
lens
stone
is
and
underlying
and
a
fragments.
tary of the Bernesga, north of Puente de Alba.
are rare.
thickness
the
very precise dating of this formation
Reddish detrital marls and wave-built biostromal lime-
c.
both
remained
conodonts,
biostromal
a
Thickness:
m.
b.
broken shell
suspected,
The
out.
lowermost
soli-
brachiopods,
locally.
occurs
limestones,
arenaceous
Concentrations
brown.
to
40
some
with
abundant
yielded
conformable,
is
sequence
The rich
and NE of San Adrian:
and
are
picked
have
have
however,
limestones,
and
contacts
formations
the
measured from
was
The
phyroblasts.
fine
difficult
are
calcareous shales
to
Matallana-Estación,
near
detrital
reddish,
limits of this formation
following composite
The
base
less
a
resistant limestone
two
gradual transition
a
is
sandstones
or
The
because
set,
field, the Portilla Formation
differentiated into
Frasnian
sand
the
tend
grains
of
cost
the
to
shales
1967).
Middle Nocedo:
and
and
the
at
Middle
Famennian;
Lower
Middle Famennian (Comte,
and
Upper
Member:
Fueyo
1959).
1959).
facies
Lateral
changes
Van den Bosch (1969)
in
the
Luna-Sil
(1973)
nen
stones.
area.
notes
an
Koopmans
facies changes
the Valsurvio
are
points
common
its
to
in
the
argillaceous
Portilla.
character
Lithology.
a
-
size
towards the top
extraordinary thickness of the lime-
tion
takes
Alba
the
also
(1962)
Syncline,
van
mentions
great
in his Valcovero Formation
lateral
equivalent
in
upper
place
beds
and reef-building corals,
brachiopods,
crinoids.
stromatoporoids, bryozoans,
The
brown
quently
been
lar
limestones
exist
with
in the form of
darker
typical
Hercynian facies of
the type
locality
metamorphosed,
shaly
northern
the rocks
giving
rise
to
of beige
partings.
to
ferred orientation of nodules,
strikingly
Europe
have
grey
similar
(Brouwer,
the
beds,
calcareous
very
decalcified
to
the
grained
to
the
top
1964).
base
of this
sandstone
that
so
marls
moulds
formed by
These
limestones
complex
sequence
soft
with
a
of
and
frecri-
of
clastic
coarse-grained yellow
are
topped
(Cremenes
follows
of
remained.
Nappe the formation consists
is
or
argilla-
sandstones have
only
The
consists
especially bryozoans
sandstones.
white
Nocedo
sandstones,
fossiliferous
decalcified,
Esla
the
Nocedo.
arenaceous
again
a
by
medium-
Limestones).
porous
thickness of 40-50
On
decalcified
m.
been tectonized and
slaty cleavage and
as
nodu-
Gradations
specific
peanut shales,
Palentian facies in Cantabria and
In
In
1965)
The Cardano Formation consists
of the
gradual transi-
A
the
drab-coloured, thin-bedded,
noids, brachiopods and
Cardaño Formation (van Veen,
to
diminishing grain
generally
are
lower part
or
with
formation.
Portilla
the
Portilla
limestones,
shales. The often
of the
from
of the
argillaceous.
yellowish,
area.
Solitary
sandstone sequence
Staaldui-
In
ceous
Fossils.
The general aspect of the Nocedo is that of
-
calcareous
well
as
a
chloritoid
prepor-
Thickness.
the
upper
-
About 500
Luna
area
m
some
near
300
the village of Nocedo.
m.
In
From the Esla Nappe,
90
(1965) reports 250
Kupke
however usually
m,
not
recog-
nizable.
Thickness.
of
Fossils.
The
Brachiopods, crinoids, bryozoans
-
Murcia
Formation
Murcia
Formation
of dark-col-
quartzites
to
alternating with thinner, dark-coloured shales. The formaconformably
tion grades
Vidrieros
of
out
the Cardano Formation and
lying
Formation.
with
sandstones
The
mellibranchs of the
load
is
part
The
some
the
near
ite and medium
to
than
10
the
Formation
dano Formation.
limestone lenses
It consists
1965)
interbedded
been
converted
ment.
have
with
typical
The
been
shales.
slates
to
of thin-
the Car-
to
medium-bedded
to
thin-bedded nodular limestone beds
or
both
with
The
peanut shales
oriented
tectonically
shales
have
strong cleavage
in
which
also
are
often
develop-
the
nodules
found.
Trilo-
are
the faunas found, but identification is often
la-
fre-
tectonic
deformation.
thickness
The
most
These
ranging from 10
found
ages
is
1967).
bites, goniatites, conodonts and lamellibranchs make
real quartz-
a
Ermita
thick (Evers,
m
thick; north
The Vidrieros Formation is strikingly similar
The major part of the
concretions.
Sabero-Gordón Line,
less
of No-
village
m
are
small
most
are
medium grained, often
to
usually
quartzitic
whereas
casted
over-
sandstones
Buchiola which
genus
quent inside rounded
formation is fine
well-rounded
basal
fine-grained,
shales, often slates, often yield
These
graded.
and
of
into the
passes
shales.
dark-grey
often cross-bedded
uppermost beds of
the
above
thin-bedded alternations
very
type locality
Vidrieros Formation (van Veen,
consists
sandstones
quartzitic
the
usually
1965)
(van Veen,
Quartzite
well-bedded,
oured,
At the
-
cedo, the Ermita Formation is about 140
rocks
100
to
20
average
in the
m
in
m
extremes.
from Lower Famennian
range
up
hampered by
Tournaisian (van Adrichem Boogaert,
to
lower-
1967).
thickly bedded. Lighter coloured,
very
quartzites
of
typical
are
the
thinner
LOWER
CARBONIFEROUS
sections.
The thickness increases from about
section
to
is
size
than 200
more
also
noticeably
of about 60
further
terminations of the
make
sequences
it
the whole of
130
Much
coarser.
in the type
m
where the grain-
east
thinner
sequences
assumed along the Cardano Line.
m are
identification of the
The
ses
m
lamellibranchs and
conformable
and
over-
de-
under-lying
that this formation
likely
encompas-
Frasnian stage.
the
our
of
Lower
which have
maps
reasonably
and
Despite
the
these
Vidrieros
the
base
of
the
formation is
often
typified
conglomerates which grade upwards into
fied sandstones and
caused by
the
The
limestones.
of
the
underlying
of the
There
is
sandstones
gradual
contact
of it.
South
North of the line,
Formation is
sited
upon
ated
more
the
the
to
a
thick
S from
the boundary
thin
the
N.
overlie
Near
thin
showing
an
Ermita
arbitrary
se-
a
one.
of the Ermita
nature
microconglomerates depoare
Villar del
Huergas
an
Shales
older when situ-
Puerto the
and
Formation
increasing
gap
Ermita
Sandstones.
covers
below
the
the
la
Vid
Ermita
-
the active
ear-
the
to
described.
transgression of
if restricted sedimentation.
Higgins
et
Famennian but
al.
(1964) and
160) indicate
a
the
Ermita
conodont
van
Formation
to
determinations by
Adrichem Boogaert
continuation into the
(1967,
Lower Tournai-
typically
donts
50
to
m
less
are
have
than
beds
have
30
Tournaisian
are
be
to
age
rare
some
reworked,
probably
are
Formation
a
sandy beds and,
they
erosion
also
rocks
do
deposition
The
sharp
upper
in
contact
with
places
most
give rise
to
Evers
nature
of
an
Alba
although
in
of the
over
map
Comte (1959) and
(1967), there have been
chem Boogaert (1967),
al. (1971),
the
of
suspicion of extensive
any
investigations of this unit; Higgins
nying each
late
contact.
original description by
by
per-
A
and the short time-interval between their
not
the
at
afford
suspicion
transition has been described. The
overlying
cephalo-
of these rocks.
age
not
found in the
has been deduced with the possibility
there.
is
occur.
localities. Cono-
variation of the base in view of the
unconformity
et
also
This formation is
m.
Radiolaria
been obtained from
many
black
although
been reported but usually
haps the best indication of the
others
of
nodules,
lamellibranchs, ostracods, brachiopods,
though
some
consists
phosphatic
pods and trilobites in the shales in
Since the
Comte (1959) restricts
Upper
with
fossiliferous but
definition
sian.
belong
already
microconglomeratic
up
sections
often
Formation.
p.
continuing,
shales
even
cherts:
develop-
a
and
Thicknesses
Sabero-Gordón Line
transgressive
marked by
Camplongo the
Shales,
of
Devonian deposits, which
Sandstones
sandy,
between the Nocedo Formation and the
Ermita Formation makes
the
Formations
Formation
Vegamian
mainly
the limestones.
to
The
cherts
transition
gradual
a
Ermita Formation in the
north
Age.
which in fact
well
as
the
excluding
Vegamián Formation
This
sandstones.
Sabero-Gordón Line separates
quence
Near
reddish colour,
a
content
decalci-
part of the formation is often composed of
upper
arenaceous
from the
high iron
micro-
by
coarse
quartz sandstones.
ferruginous
part of the formation often has
ment
on
are
Devonian-Carboniferous boundary has
been recorded by
The
That is
instability during
times,
lithostratigraphic
on
grounds.
liest Carboniferous deposits
Ermita
shown
are
age
Formation (van Staalduinen, 1973)
Ermita
The
Carboniferous
been generally recognized and
correlate
to
easy
biostratigraphic
as
the
units
Two
et
re-
number of
al. (1964),
Winkler Prins
and above the
a
van
Adri-
(1968) and Wagner
descriptions
accompa-
sheet.
Although widespread,
the
outcrops
often
seem
to
be
91
discontinuous, and the unit is
implied by
as
certainly
of the 1:50 000
most
not
persistent
as
&
maps.
Alba Formation
The
Alba
cally
bearing
rich
a
noted from earliest
The
1853).
and
underlying
useful
be
even
de
the colour
overlying
fine
traced
shales
monly
30
rocks
be found
to
and
well
as
that
so
mapping.
of
it
has
been
Red
and
even
and
distances
Boschma
after
may
(Winkler
(modifed
Formation)
quite thin, usually
the
to
crinoid
goniatites,
ossicles
are
Radiolaria in
as
been
texture
often present
are
In addition
m.
corals
solitary
has
this unit off from
set
considerable
over
thicker than
nodonts,
which
-
micritic porcellaneous
as
typi-
-
Verneuil & Collomb,
1968). Again this formation is
Prins,
not
fauna
(e.g.
marker horizon for
a
as
cherts and
green
appearance
'griotte' (nodular) limestone
green,
times
well
as
striking
a
goniatite
fine
very
the limestone
the
has
red, sometimes
a
often
Formation
the
co-
com-
cherts
(Cuevas
and shales.
The
is
Alba frequently overlaps
various
descriptions
(Comte,
1959;
The absence
Alba
that
the
surface.
break
1967;
detrital
overstep
took
place
However,
region
was
clearly
the
visible,
Caliza
de
a
a
would
this
at
indicates
considerably older
in
other
any
important than other hiatuscondensed
with
overlying
the
Caliza
The
age
ranges
(Kullmann,
from Lower Viséan
1962;
mentioned above,
rections of
Lower Namu-
to
Wagner-Gentis,
breaks
There is
anticipated.
in
this
1963)
sequence
enough evidence
not
transgression
etc.
as
but,
have
as
derive
to
attempted by
some
The
Alba Formation is
southern Cantabria,
di-
sequence
it is
1:50 000
maps
phic
reasons,
laterally
(see Fig.
has
and this
that
so
2).
had
considering the thin
However, the outcrop
be
to
exaggerated
generalization
has
again the truly visible
mation is considerably less
than
most
for
maps
of the for-
imply.
well-differentiated,
Visean
veloped
in
the
The
of the
flysch-molasse
garded
as
Lower
Carboniferous lacks
ken'
a
facies
normal
regarded
geosynclinal
assemblage
the
cies
is
complex
so
of
development
that
a
appropriate (Reading,
of southern
even
of
though
re-
the
distrbuion 1968).
ophiolites and the 'bee-
addition the relation between the
not
so
de-
not
sequences have been
typical
as
are
sequence
Upper Carboniferous rocks
majority
units
lithostratigraphic
typical of the earlier Phanerozoic
Cantabria.
Namurian
and
UPPER CARBONIFEROUS
Generally
carbonates
the
on
cartogra-
been extended
extent
(Alba
au-
remarkably persistent trough-
especially
and
be
to
thors.
out
de
in general grad-
ual.
rian
Montan
Where
sequence.
conformable and
Formations)
that
unlikely
seem
and
1971).
where the
rocks
contact
contact
upper
Montana is
localities
at
upon
transition
Varker,
Palaeozoic
it
more
be expected in such
to
&
flysch
contact, and
gradual
a
deposits
Lower
the
at
Wagner
on
in sedimentation
part of the
es
of
of
speak
Evers,
directly
rests
erosion
the
the Vegamian but there
lithologic evidence of erosion
no
simple
the
pre-flysch
(Reading,
flysch
a
In
Present
and molasse fa-
Stalduine,
2.
geosynclinal
1970; Savage,
in
1970).
model is
1979). Mapping
Fig. van
92
Cant bria.
throughout
rocks
Carbonifeus
the
of
lithol gy
and
thicknes
in
vari ton
the
showing
columns
Straigraphic
3.
Fig.
93
of these types of sediments is notoriously difficult and it
is
been
while
that,
significant
named, almost
individual beds
An
often
Basically
data
the
our
of the
permit,
formally
have lived
stantiate the
of
sake
been
would
be
the
succession
the
perpetuated
Within
with
all
distinguished by colour
the lithologic
this
and
way,
vidual
with
of
styles
all
on
the
the
source
of this
primary
role
1966)
information.
are
has
The
with
together
from spot localities but
complex,
be
so
that
indi-
dealing
in clas-
made
the
to
complete
data, neither
1959, 1965, 1971; Racz,
floras
(Wagner,
other articles;
many
structural
dubious. Another major
the
be
to
terrestrial
the relevance
relation between the
-
the
Stock-
1966). The majority of the samples
& Willière,
mans
in
derived from marine Fo-
largely
bibliography of
with
1971,
between
of biostratigraphy
raminifera and Algae (van Ginkel,
1964,
Not
be expressed
in respect of
relationships
the
to
picture
map
the
uncertainty is
may
true
cor-
Russia,
the
marine
of
Algae
N
America and the terrestrial floras of France and GermaMuch
ny.
work
has
been
will
search
even
undoubtedly
terms
throughout the
a
crease
a
through
also
the
Upper
marked
progression
are
the
to
or
seem
marginal
from
to
a
shelf
and
crust
The
and
most
the
mapping
are
to
be
although
history.
Krumbein
shelf
to
there
to
syn-
is
in-
(i.e.
in
do),
area),
thrustsheets
well
as
south
south
of the
be
the
of
which
The
zones
Sloss
interior
(1963) with
developed
upon
between the carbonates
(flysch/molasse)
both
of
which
beds.
in
three, but
A
following
sequence
must
which
is
follows:
which
2)
nor-
lime-
3a)
the
originated
the
3b)
clastic
occasional
wacke-
mudstone
Algae,
and
numerous
brachiopods,
intermediate between
the
other
more
may
be
common
noted
in the
that
fossiliferous
younger
of the
parts
although interfingering and repetition is
be
form
fossiliferous
as
in
de
probably indicates littoral
calcareous
tendency
become
van
mostly micri-
This facies often contains
is
the
normal biostromes;
facies
and
with
facies,
in
occasionally
may
clastic,
which
and
spot.
closely associated with 3a."
more
general
types
2, but it
adequately described
grainstone
and
and
etc.,
Examples
Fig.
single
a
differentiated
Foraminifera,
crinoids,
from
expected
such
usual,
related
closely
sedi-
ments.
The
Carboniferous
siliciclastics
facies
said
types of
which the
(regressive),
fining-upward
growth)
dictable'
include
few
Graaff
can
be
fining-upward
(transgressive)
(1970).
The
(1971a),
'pre-
remainder
Nederlof (1959), Savage
de
van
a
var-
number of
the coarsening-upward
(fluviatile),
of Reading
turbidites;
(1975),
are
fining-upward
sequences
many
Lobato
and
large
a
genesis of only
be understood. These
to
considerably
are
ied, and have been described under
Maas
(1967),
(1974),
Reading (1970). However, Rupke (1977) and Maas (1974)
shown
The
black
and
rocks
shales
the
themselves
beds
are
laterally.
range
in
mainly
deep basin,
Most
beds,
to
the
but
of
but
from
grain-sizes
coarsest
fine
sandstones
boulderbeds
and
mappable olistoliths. Generally lime-
associated
greywackes
massive
other,
through mudstones, siltstones,
conglomerates
stone
of
presence
olistostromes with
and
1979).
at
the
the
3)
be
grainstone patches.
corals,
of Muda,
east
siliciclastics with
by
the massive,
of
conditions,
stone-packstone
facies types.
environments
the Liébana Basin
largely composite
are
which
instead
waters
have
post-
Valsurvio
even
groups;
"1)
are:
facies,
may
sub-littoral
variations
either the
and
agitated
as
facies
unfossiliferous;
stones
to
of the
well-bedded micritic 'lagoonal' facies,
mally
in
(Bernesga
they interfinger with
shown
be
can
main
distinct bioherms
the
(Somie-
west
Upper Carboniferous limestones
bank
biogenetic
These
stages.
Torio
limestone
thickness
true
Graaff (1971b) these
tic
flank
and
are
that these
Mountains
three
of
maps
along the southern bounda-
de Europa,
sequences
the
Cantabrian
terms
Rio
areas
intercalations of
represent
Most
other
contrast
appreciated
not
may
Picos
of
some
must
extreme
Alba Griotte is overlain
minor
only
the
the
of the Sabero-Gordón Line,
the Visean
of
In
of
southern
of the
the siliciclastics.
ry,
the
as
most
thousand
sketch
dominant limestone development in
de Europa),
(Picos
the
and
of the major facies
1970; Savage,
contrasts are
found
sequence
molasse). Local
corresponded
unstable
siliciclastics
north
the
of
areas
a
The
the present distribution of these
and 5) show
include the
(plant
parts of the
interfingering
(Reading,
striking
to
re-
maps.
appropriately for
complex
of
was
considerable revision
our
Carboniferous
flysch
have
basins
continental
some
in
lithologies
same
younger
quite strong,
indicates
would
the
tendency for terrestrial influence
tectonic sediments, but
types
result
the rough indications of
In general
quite
done since
1974), and the continuing
completed (approximately
of
4
2,
than
more
sequences
number of places.
a
types of the Carboniferous for various
two
are
often
are
differing reference sequences used
Foraminifera of
(Figs.
in
oosparitic-pelsparitic
sequence, reference
unambiguous,
nor
lithology
terrain.
the
Admitting
can
mapping, particularly
unexposed
sifying
indi-
defined,
so
the
for
maps
thick
metres
for-
symbol overprinting.
or
differences
are
sub-
to
although the
the
units
variations known
there
within
mappable
proposal,
vidual lenses and beds of sufficiently distinctive
are
were
belief
discovered
and the failure
expectation,
negates
uniformity.
as
Vegamian of the Ruesga Group
of the
rest
well
into
developed
are
Dome. In
subdivi-
as
in
(1962)
Koopmans
and
effectively
have
names
by
this
to
up
3.
Ruesga, Yuso and Cea
groups,
Alba
to
sequences
Namurian, Westphalian and Ste-
formations
them. Only the
arbitrary
variations in thickness
biostratigraphic
a
or
then
even
to
recourse
the
roughly corresponding,
the
to
proposed
mappable
mations
show
maps
actually
be obtained from Fig.
can
sequence,
phanian stages. The
that
force
Upper Carboniferous
be found in Cantabria
sion
been
in the field and
impression of
lithology of the
and
them have
have
loosely defined lithosomes
very
be traced
can
variations
gradual
boundaries.
of
none
fact only
In
mapped.
large number of units
a
they
the
with
can
the finer
pass
into
conglomerates
gradational
grained
are
contacts
shales
conglomerates
in
are
thick
to
common;
94
particularly
sion
laterally
passage,
mudstones. Sharp
of the
mass-emplacement
or
vitational
tions
of
upon
1:50
lithology
000
can
Carbonates of this
as
quence
dark
the
(facies
Sheet but
these
1
types
(but
by
the
on
a
se-
unit
a
and 3) above
named)
not
de
van
units, al-
with
2)
type
Caliza
as
maps
types of
is overlain
Alba Griotte
micrites
subdivision is shown
the
on
three facies
found within
bioclastic limestone (facies
Porma
adequately represented
shown
All
be
to
are
rule
a
of
gra-
varia-
Group)
are
age
Formation.
Graaff (1971b)
though,
that such
maps.
Namurian (Upper Ruesga
de Montana
be
never
ero-
conglomerate by
be obvious
It should
sliding.
into pebble
vertically
or
indicate predepositional
contacts
it.
of
This
Bernesga-
alteration make the distinction in the field
postdiagenetic
difficult.
the
In
with
interfingers
south of the
of the
sence
three facies
thonous
movements
in
at
the
ly
that
these
in
have
been
a
regional tectonic
rock
stage, but
been
age
are
also
A
rare.
very
type
from
chert
the
typical deposit
very
that
(lydite)
It is hardly
it is
has
Upper
stone
ty,
would
with
slump
to
not
far from
certainly
sediments,
the
be
either exhausted
without pebbles
or
and
it
more
sources
and slide
deposits
choked off.
or
the
is
typical
but other gravity
grainflow, fluidized sediment
is
of
ly
carbonate
at
of
-
are
flow
also
to
-
for
turbidi-
be
flysch
shelf
and
flysch
de
1
sequences
Picos
of Westphalian
de Europa and
Graaffs
facies
type
with interbeds of type
near
Westphalin
found
age
near
are
the
only
Riano
interfinger
3
3
(a
(a &
& b),
distrbuion
León
Riano (Fig. 4). The former consist almost entire-
van
of facies
stones
carbonates
of
be found in the
Line
(Yuso
Mud-
matrix
Westphalian (Yuso Group)
to
Group)
and
(Rupke, 1977).
Thick
(modifed
of material from the youngest parts of the 'base-
supply
ment'
Carboniferous
like-
almost
Vegamian Formation,
after
coar-
completely exclusive
shows
experience
The black
derived
could be
the whole
comprise
(p. 93), although
to
Boschma
re-
tectonic
event.
logical that, with erosion and the accretion of
more
more"
occur
controlled by
lydite-bearing microconglomerate.
so.
1967).
little
may
van
&
is
manganifer-
as
Stalduine,
autoch-
as
Brecciation
well
as
is
All
2).
resedimenta-
slide,
sedimentation which
may
conglomerates
this
(Fig.
phenomena signify
of types already referred
being
Alba Griotte
1971b).
contact
Liébana
the
but these will have been small and restricted
not
that this
overlies and
(Ricacabiello Formation, Sjerp,
zones
2)
where, in the ab-
the
slump and
(Fig.
Namurian
be interbedded
Graaff,
Siliciclastics of Namurian
ser
the
siliciclastics
may
de
observed
These
in extent,
or
(van
the change
peatedly.
is the
Europa
except in
limestones
by
limestones
likely
seems
range
de
during
Sabero-Gordón Line
sediments
commonly
than
Picos
down
carbonates,
succeeded
deposits
ous-nodule
It
the
usual basal
conformably
tion
laid
were
1974). Elsewhere siliciclastic flysch
(Maas,
and
the
north,
extreme
carbonates
only
1968).
elsewhere because weathering and
not
the
latter
Present
b). These lime-
westward
sequence of the Central Coal Basin,
into
usually
the
called
4.
Fig.
95
the Lena Formation
on
our
interbeds in the lower part
the
mation;
siliciclastic
much
be
to
(1974) considers
since
younger
of the Picos
the
to
Euro-
thin shaly
de Europa For-
Formation
equivalent
dates he
de
Picos
restricted
Aliva
lateral
a
In the
maps.
terrestrial influence is largely
pa,
that
may
Maas
in fact
quotes have
all
be
been
derived from resedimented limestone bodies.
The siliciclastics of
sequence,
although
they
coarser
beds.
of
portion
Westphalian
occasionally attaining
800
in
has
m
been
the classic
Veen,
1976).
of
rocks
within them demonstrate that
mass
the
1967;
rable
ved
sheets
identified south
Vegamian and
exists
overlap
in
the
1967,
pable horizons
The
the east,
to
(van
de
E
have
typical.
nor
They
eastern
(Martinez
et
Central
al.,
& Boschma,
The
by
most
the
1971)
1966;
van
and
to
the
they
as
the
to
mapping
area,
Garcfa-
1962;
Basin
not
along
common
our
Pisuerga
Occa-
are
(de Sitter
formed
mentioned above,
in
mapping
gradational
are
al-
encoun-
with
contacts
pebbly mudstones and limestone conglomerates (usually
The mapped unit certainly
mapped separately).
conglomerates of various genetic types
of
range
thonous,
marine
zones
interbeds of
marine
limestones
conditions
are
rare,
and,
the
has
of
the
the
probably
alloch-
dominance of
seat-earths
and
land-plant
lithosome.
Cervera
Sheet).
ered
to
slide
&
cordance
with
that
that
rootlet
material
end
of the
unconformity
the
rests
and
(Car-
consid-
once
Yuso Group
Staalduinen,
in
wedge
Curavacas
Pena Prieta
near
(Koopmans,
is
1968),
by
no
1974). The presence of
1967; Maas,
conglomerates
south,
the
on
wedge-shaped form
between
as
of the
van
(Sjerp,
Los
Cintos
(Carrion
area
1970) lessens the significance of the dis-
Sheet; Reading,
so
well
as
shown
very clearly
striking
thicker
Elsewhere
clear
is
out
a
Devonian
define the base
Boschma
1962;
The
upon
de Pisuerga,
rion
means
yields
the
it
Ruesga
by
can
this represents
be
means
taken
the
to
certain
as
regional tectonic
single,
a
rocks
(Namurian)
no
event
as
proposed by Kanis (1956).
Our
show
maps
quence
such
sional,
massive
another
and
indicators
These
that
so
relations
types
they represent
is
sketchy
very
reconstructions
Carboniferous
lavas
of
most
of the extrusives
Perekalina,
soba
slumped,
found. The
While
(Carrion
can
comm.).
pers.
Sheet)
One
has
near
been
latter
Sheet),
well
as
vesicu-
as
has
little
can
considerably,
dacites
as
are
where
bodies
that
so
varying
be classed
include
The
form of the
deformation
relationships.
Un-
litho-
palinspastic
rocks
igneous
around Riano (Yuso
intense
of the
and
and extrusives.
occasionally
been
been obscured by
said
sections
Westphalian
common
have
one
speculative.
very
intrusives
brecciated tuffs
lar
that
so
be
must
basic and acid
particularly
to
enormously.
vary
derstanding of the threedimensional shape
somes
however,
not,
are
the
se-
occa-
the sandstones and shales of the innumer-
to
facies
obvious lithosomes within this
sandstones.
facies
constant
the
the conglomerates, limestones and
as
(Dr. T.
Santibanez de
described
Re-
spilitic
as
(Koopmans, 1962)
The
intrusive
largest
which
Sheet),
is
that
larger
appears
tabular body is exposed along
scribed
as
granodiorite
a
although there
tions
within
the
(andalusite),
net
mass,
shales
tion
of
of
the
the
patchy,
very
it
the
It has been de-
Veen,
(van
even
may
reddish
of the
be
1965),
varia-
composite
a
formed chiastolite
brown
biotite
and
North
gar-
cleavage
are
1962;
low
the
there
been
(Rupke,
Valsurvio
in
Veen,
grade
also
of
the
lower
the
1977).
Dome,
A
in
formaIn
the
chloritoid
Devonian
1965).
ana-
identified
accompanying
common
van
calcifi-
rendering thorough
has
Liébana
and
prehnitization and
rocks
Pyrophyllite
slaty
(Koopmans,
(Carrion
because
considerable internal
albitization,
Anticline
porphyroblasts
dipslope.
a
metamorphism has
many
difficult.
Prieta
map
1965).
Chloritization,
cation affect
the
porphyrite
be
and
muscovite,
(van Veen,
lysis
to
seem
Pena
at
on
shales
general,
greenschist
if
facies
metamorphism is deduced.
been washed into the
before deposition.
From the
vacas
east,
the
since
majority
found in these rocks
sea
autochthonous and
confirm
all
unconformably
Murcia
age.
frequent
The
included
considerable
and
the
This
intrusion. Contact
1971a), respectively.
mappable lithosome is
and
that
although
Alvarez,
Conglomerate
pinchouts
most
for
be
1971a) and
edges of
de Graaff,
and
striking
Curavacas
due
flysch
found but
though considerable difficulties
tered
map-
has been interpreted
are
the
Loygorri
this
map-
1974) in which the sub-
been
the northwestern and
Cuenca
that
so
detailed
to
Liébana developed (Rupke, 1977).
seat-earths
widespread
cover
Graaff,
deep basin (Maas,
as
marine delta of
sionally,
mostly typically
area,
delta
prograding
they
extrapolated
invol-
116). In the absence of good
p.
is
sequence
of the rocks
ages
those
be
1965; Evers,
1965). Conside-
subdivisions have been made.
no
in the Pisuerga
northeast
and
cannot
Line around Prioro,
Ginkel,
van
have
some
maps.
able
1974).
found in
not
Emiliano (Rupke,
1969;
other
been in-
(Maas,
are
age
as
occur-
or
have
many
4) although
León
between the
thrusting
(Evers,
ping
San
near
(Fig.
of the
den Bosch,
van
generalization
a
of Westphalian
Leonide thrust
been
the
limestones
movements
grain-flow
or
In general, rocks
of
1970;
well
as
sediment, and
blocks
(van
common
uncleaved
rence
volved in
in Cura-
as
1974; Reading,
often
typical
allochthonous
pro-
common,
1965). Turbidites
also
are
1967; Maas,
another
unbedded, is
are
are
older
higher
a
thicknesses
variant types
Mudstone,
the
uninterrupted section of
an
measured (van Veen,
and
of
Conglomerates
enormous
1965; Savage,
Lobato,
those
contain
usually
(Carrion Sheet) where
vacas
(Yuso Group)
age
indistinguishable from
lithologically
the gradual pinching
cause
the
the
maximum thickness of the
conglomerates thin
beyond Los
thinning
is
less
Cintos
rapid
very
section
(Carrion Sheet).
but
perhaps
at
Cura-
towards
rapidly
To
more
the
the
west
striking
be-
Stephanian
Sediments
whole
(Cea Group)
of
region,
Stephanian
usually
age
resting
are
scattered
unconformably
older Palaeozoic and Precambrian rocks,
as
over
upon
can
even
the
the
be
96
in
seen
mostly
the
sketchmap
to
easy
they have
5), hence
(Fig.
been
map.
Helmig (1965) provided the first comprehensive study
of these rocks
area
in
what
workers
recent
more
a
the dominance of limnic
emphasizing
the type
as
paralic
sequence
deposits, although
interpret marine intercalations
greater degree (Wagner
al.,
et
1969; Reading,
to a
1970;
van
1972). Very large proportions of marine sediments
Loon,
have been
described from
outlying
such
areas
the
as
Pi-
1959), the Valdeón (Boschma &
Basin (Nederlof,
suerga
1968) and the Picos de Europa (Maas,
Staalduinen,
van
been considered
has
along the Cea River. He called it
1974).
In
the
general
paralic deposits,
and
se" (Reading,
by
are
1970),
some
and
hence
these
Only
sequences.
in
be
can
laterally
to
geographically
in
"...
to
89)
p.
Basin
on
Formation:
a
Westphalian lower cycle with quartzite conglomerates
its base
nian
and
of
are,
of
conglomerates
floras
the
Wagner
(e.g.
and
al.,
et
the rule, for
the
1969).
The
occurrence
maps by the varia-
our
tions in thickness and number of the conglomerate levels
which
and the
1970,
that
in
are
between
the
of the
nature
predictable
the
In
29).
p.
such
bedding
any
our
The
maps.
conditions it
in
on
this
account
Varker (1971),
In
one
of the
and
van
van
area
-
the first
Pisuerga Sheet,
largely
are
usual molasse, and
marginal-,
numerous
no
and
coal
sequence
system of
of
van
coals
studies
will
be
in
not
found
most
have
sequence
discussion
here
which
be
and
were
facies
the
&
studied
the
formed and
in the earlier
as
see
bibliography.
contrasting
be
preserved.
The
1970).
of the
extreme
opposed
'high-destructive'
The
almost
superior
worldwide correlation that
pected, but active
research is
still
in
(Cea
to
might
progress
Stephani
the
of
distrbuion
delta
unique
not
molas e
the
de Graaff (1971a), later conditions allowed
to
Group)
-
evident,
differed;
ternation of marine and terrestrial fossils has
to
many
in Wagner
(Reading,
(modifed
comment-
of alternations of shallow-,
represent
after
likely
lithostrati-
extensively
marine sediments,
deep basin
seams
events
hardly
and
basal unconformity is
the
consisting
cycles in which they
many
and
Graaff (1971a) for
The rocks
may
seems
Loon (1972), Knight (1971).
interpretations of
de
but
rivers
fans" (Reading,
the distances covered
recognized
Boschma
.. .transitional
migrating
bio-
a
over
recent
more
subdivisions have been
ed
of
piedmont
plane will form
graphically correlable horizon
by
facies
sequences
largely conglomeratic
"
van
&
of
level quoted
scale of lateral changes
on
Stalduine,
its
There
detailed knowledge
more
is illustrated
in this sequence
in
conglomerates
the biostratigraphic
modify
may
to
at
Stepha-
a
quartzite conglomerate."
exceptions
course,
the
void of
and
and
conglomerates,
limestone
with
cycle
upper
lower part
limestone
no
1968).
Thus, in fact,
Cea
the
not
(1965,
Valderrueda
grounds
recognized
that,
so
given different for-
Helmig
the
on
changes
of similar lithology and
lithologic and palaeobotanic
cycles
however,
refer
generally
subdivided the succession
two
distinctive
reasonably
constant
or
fan
piedmont
sediments of the molas-
have been
of rocks
patches
distinctive
any
typical
sequences
names,
isolated
.fluviatile,
..
the
distinctive
no means
mation
are
grounds. Within the unit,
lithological
although
"
rocks
al-
yet led
be
Present
5.
ex-
(Wagner,
Fig.
97
1971,
and
1971
Ginkel,
van
with
-
the
Pena Cilda Formation
lie the barely
the
events
brian
Mountains.
felt
Rather
nature
Another
the
with
area
atypical
that in and around
is
and
Picos
they
lar and show
similarities with the
some
Pisuerga succession.
well dated due
They
bearing marine faunas
slide
claims
even
that
Westphalian
relations
the
the
to
around the Picos
Sheets).
in these
lenses
Soto
de
the
Valdeón
some,
seem
de-
stratigraphic
are
Yuso
argued by
least,
that
probable
the
Yuso and
particularly
are
at
very
corre-
units within and
on
common
allochthonous
are
noted that
Sheet;
they
beds
many
limestone
as
are
The Triassic
which
(Maas,
reworked
with
tuffs
exposed
bra
is
the
and
facies.
In
the Pena Labra,
member,
The
and
a
type
or
a
the
At
under
lahar member,
section
must
known
the
to
the
top
belong
included
(1974)
Maas
red
and
mudstones
the Keuper.
to
was
but
the
in
Nansa
This
chosen
formably
consists
on
known
A
salt
the
Triassic
in
the
deposits
of the
m
in the
of
sisting
a
shale.
the
top,
resting
pebbles
The
the
and
intercalations.
About
thinner
a
show
al-
sandstone,
imbrication. At
into
100
cross-bedded
above
m
laterally
and
the
upper
predominantly of silts
neutral in the
shales,
the
boulders
sandstones, alternating with gritbeds and
upwards,
and
The
con-
Pebble beds
cross-bedded
passes
1000
Usually, the
homogeneous,
matrix.
frequently
than
more
quartzitic pebbles
conglomerate
coarse-grained
or
uncon-
conglomerate.
very
of usually
layers
to
Valley.
quartzitic
a
quartzitic-sandstone
with
and
of Lebena
the Nansa
Iithologically
is
well-rounded
coarse
ternate
with
starts
conglomerate
in
E
m
road section of
sequence
facies,
Bunter
the Labra Formation. Thickness of the unit
less
which
red
and
beds
are
of
and
passes
vertically through
a
shales.
parts
very
the
-
the
basal
extensive
sequence
part of the Nansa
coarser
of
a
the
top,
low
angle by
the
a
on
the
SW
La-
Unit
The colour
-
is
con-
pale
is deep purple in the
similar
Labra.
to
the silts
and
Nansa
Unit
The
sequence of clays and marls
into the calciclastic Tudanca Unit.
volcanic agglomerate
for
are
its
Tudanca Unit
This unit
consists
ing micritic,
often
alternating
ly
good
shell beds
were
Unit, but
no
exposure
The
flora
con-
Labra
Carbonifrom the
largely of well-bedded, grey-weather-
recrystallized
with
distinguished.
outcrops.
restricted
JURASSIC
the
slope of
Labra Formation varies
area.
Even
Unit
unit
shales
sandstones
be younger than the youngest
this
may
marls,
gypsiferous
TRIASSIC
breccias,
sandstones of the Triassic
section
type
the Palaeo-
on
sharp angular unconformi-
rocks.
coarse
throughout the
Formation
ferous
tuffaceous
tuff member and red beds
a
accessibility,
siderably
is
Carboniferous
basal conglomerates
Bunter
directly
reposes
dolomites
supposed
are
conglomerate,
along the south slope of the Pena La-
off unconformably
cut
Ligüérzana,
to
north-east in the Nansa Unit.
silts
and
conglomerates
Per-
represented in its germanic red-bed facies
cavernous
thin shale
fact
1974)
volcanic
of
or
been encountered (Salinas de Pisuerga).
has
sists
bra. The lower boundary
ty
Cillamayor
conglomerate is locally developed. The total
Formation
shales, is
from
Towards
change.
not
contain
red
sequence
of Triassic
considerable thickness, and the character does
a
in
PERMIAN
tuffs,
be
to
continental
and from south of Cervera the Creta-
in Wealden facies
fining
A
band
narrow
around
conglomerates).
Labra
supposed
is
orogene
red
Along the southern border the Triassic
age.
varies from about 400
data
more
shown
should be
the
on
be
might
the
Stephanian
erroneously shown
are
unconformable
Group. As
Yuso
Conglomerates
and
but
could
as
Staalduinen (1968)
de Europa (as
sequences
of
are
Cantabrian
the
with older
contact
than
which
of
unconformably by
zoic.
a
406)
east
uppermost
far
as
set
p.
unquestionable.
van
younger
conglomerates (it
slide
and
and
with
the
to
palaeontological
area
405) it would
p.
they correspond
Deva
above,
remains
strata
rocks
(1974,
common
statement
Valdeón
lated these
Maas
less
probably
(1974,
have,
identification
and Boschma
scarce,
"belonging
Stephanian,
positive
of the
position
In
is
from
duced
units
often al-
only
ages
Maas
unconformable basal
an
The
their
that
so
emplacement.
Lower
or
be observed,
strata."
masses
their
maximum for
the
less
Palaeozoic
the
disappears,
reaches
simi-
part of
are
in
a
ceous
in the
the absence of workable coals and flo-
to
The limestones
lochthonous
(Fig. 5).
largely
upper
forms
then it
names
are
folded
deposits,
Stephanian
of
The
mo-Triassic
well known and
less
are
yielded
suggested
the
TRIASSIC AND JURASSIC
sug-
margins,
de Europa
units although
hence
specimen,
age.
covered
movements.
different structural
ras.
their
sequences
the
piniformis
con-
model
faulting
(1974) describes them under different
Maas
account
to
of the
(1975) with strike-slip
intermittent, migratory
Walchia
sedimentary
throughout the Canta-
development of basins
the
favour
would
necessarily
Reading
gested by
trolling
age
were
a
Mames
part of the tuff member NW of San
upper
Permian
over-
Accepting this does not, however, imply that
sequences.
such
unpredictable changes in the
gross,
area
1970). The latter
(Reading,
continuing tectonic activity
postulates
author
for
in this
age
also unconformably
-
deposits
older
The
bibliographies).
truly continental deposits of Stephanian
calcareous
discovered
near
limestones, occasionalshales.
Some
mollusc-
the base of the Tudanca
determinations resulted
in
an
age
indica-
tion.
Maas
rassic
(1974) considered his Tudanca Unit
age.
to
be
of Ju-
98
The
Jurassic
between
limestones
Cervera
de
formably and slightly
whole Jurassic
The
At
marls.
the
lies
the
over
border
lie
of
massive,
be
hardly
well-bedded,
observed.
marls
grey
ammonites and
Next
and
follows
a
limestones
and
and
grey,
plane
of
sequence
which
contain
brachiopods.
Wagner (1955) and de Sitter (1955, 1957) mapped the
Villanueva
tions
of
Limestone
conodonts
(1965) indicate
a
as
and
Jurassic
rock, but determinacollected
goniatites
Lower Carboniferous
a
bly
the
only
Cenomanian and
Turonian
Frets
by
Bohar
The
and
marls.
The
measured
was
Bodas;
the
tension
of
transition
these
CRETACEOUS
marls
built
and
unconformably
the Jurassic
upon
A
great part of the
Palaeozoic
Mountains is bordered
which
ments
the
the
to
Cantabrian
by continental sediWealden
facies
pink
to
red
are
d.
bedded
age
of Burgos,
province
it
is
Wealden clearly
In
to
reported
while in the west,
(Ciry, 1939),
ronian
age
km
rocks
width from
Guardo. Further
the
veloped
the
in
a
be
of
covered
the
They
the
Albian
age
point
to
are
are
in
out
de Pisuerga
in
correlations
zone
in
our
found.
area
de-
are
stone-shale
deposits.
The
individual
limestone
intercalations of
(1967)
to
distinguished
a
Voznuevo
the Wealden and
a
Formation
to
Bonar Formation.
many
E
named after
can
exposures
lenses
a
resemble
hematite
muscovite
pebbles
film.
shading from white
the
village
of
are
Iron
to
upper
carbonaceous clay
lignitic
concentrations,
and
are
the
the
the
mapped
Pebbles
a
litho-
on
fossils
lower
a
consist
detailed
two
have
series
of
con-
sand-
Cretaceous
and
sedimentpetrological
above-mentioned conglomerates
Vegaquemada Formation (Evers,
Evers
defined
of the Voznuevo
from
clay
and
well-
the
large
lignite,
colours,
characteristic
Formation is
sandstones
lenses, but gravel streaks
carbonaceous
dish
type
brown
beds,
are
a
and
1967;
van
still
clay
indicate the lower part of the Upper Cretaceous,
Formation,
Vegaquemada
a
Riacos
exposure
east
Staalduinen,
is
situated
of the village
argillaceous
the
most
or
on
channelling
with
the
sequence
lower part
Only
grainsize
is
when
underlying Voznuevo
distinguished
Formation. The
increasing
of
The
the limestones of the Bonar Formation
Voznuevo
terized by
through the
features.
present, could the sandstones be
of the
the left bank of the
of Vegaquemada. Red-
of argillaceous sandstones.
contacts
Candanedo
sandstones, thin conglomerate
characteristic
unconformable
Formation
a
Formation.
claybeds and micaflakes all
mainly composed
The
vivid
most
composed of finer grained, micaceous
Pollen assemblages
and
generally coated purplish-red
purple,
part
with
clay
strata.
Wealden-facies.
kaolinite
flakes,
features. The
the
be found in the
multicoloured sandstones
rounded quartz
by
where
rocks of the Cuevas facies.
Formation
of Bonar. Along the road from Bonar
gravel pits in these gently south-dipping
The
lenses.
Porma River,
sandstone formation is
Voznuevo 2 km
gravel
(1965)
conclusion
areas
description the reader should consult Mabesoone (1959),
The
Collé,
the
two
or
clastic
more
Voznuevo Formation
to
other
Palaeozoic material. For
who describes
separated by
sub-
on
well-lithified conglomerates with
to
superposed
stratigraphically
are
is based
Tertiary
Basin.
The
1973)
be correlated
This
with
Rupke
sisting of mostly
east
this strip becomes discontinu-
of this
Duero
angular unconformity between those
an
band of
the
the
continental deposits.
Mabesoone (1959) based this
logic
continuous
a
the Cretaceous
area
sediments of
reddish
mostly
existence of
Tu-
sediment.
Evers
Tertiary
pro-
a
Wealden facies; the limestones and marls of
Wealden
and dolomitic limestones
division into Lower and Upper
been
west
marine Cretaceous
marl beds
limestones.
arenaceous
1965).
crop
rocks
lenses
by
indi-
as
on
bedded
of
east, in
Aviados in the
near
lignitic
Cervera
to the
The oldest
ous.
from
pollen
(van Amerom,
Cretaceous
1
arenaceous
Thickly
units.
vince of León,
are-
gravels with lignitic
diachronous deposit.
a
well-cemented
reddish colours.
light-coloured limestones and
Along the southern boundary of the
determinations of the
that it is
and
to
and sandy marls.
is
The
area,
top:
clays,
streaks and lenses.
cate
Porma
to
TERTIARY
They
pink, kaolinitic sands and
to
of the
core
south
comparable
are
Cretaceous.
English
white
the
to
(1939) might
the
marls.
and
stones
1965)
ex-
glauconitic
micaceous sandstones grading
thickly
alternation of
the
Argillaceous sandstones grading into calcareous sand-
c.
Wealden facies (Helmig,
An
naceous
the Palaeozoic rocks.
upon
b.
Las
to
western
found from base
are
and
the
Ciry
to
Coniacian in
age
type-section
Voznuevo
on
Overlying
calcareous sandstones with yellow
conformably
The
west.
according
of the
top
Arenaceous
is
lime-
arenaceous
composition and
path from
limestones.
members
following
to
of Bonar
which
zone,
the
represent
east
along the
village
into coarse-grained,
lie
Amerom,
1967)
composed of
thickness,
from
change gradually
the
age.
Formation (Evers,
Bonar Formation is
stones
a.
The Cretaceous rocks
(van
1965).
Triassic.
slightly breccious limestones in which the bedding
can
con-
of limestones, shales
up
series
a
southern
Cillamayor
and
transgressively
is built
base
the
along
Pisuerga
upper
of the
part
are
from those
is
charac-
sandstones,
and
coarse-grained sandstones in finer sand-
stones.
with
occur.
lenses
proba-
Candanedo
Formation
(Evers,
1967;
van
Staalduinen,
1973)
This formation is
named after the
village
of Candanedo
99
in the lower Porma Valley, where the
beds
merate
The
transition from
the
gradual;
very
bank is
limestone conglo-
best exposed.
are
regarded
the
first
Formation
Vegaquemada
base
limestone
but
boulders
of the Candanedo Forma-
smaller and
are
matrix consists of
cemented
tercalate
the
the
thick
sand
sorted
posits
but
due
are
the
The
frequency
from
the
down
sliding
and
while the
fluviatile de-
best
are
tectonically
dimensions of
un-
of torrential rivers,
courses
Bofiar Formation
mark
explained
by
steepened slopes.
the boulders derived
decrease
towards
the
top,
of Palaeozoic limestone and quartz-
proportion
sandstone pebbles increases.
(van
subdivided the
(1959)
the
Duero Basin
cos
facies of Miocene
NE
deposits
The
Miocene
of
Robles
Coarse
Van
in
sediments,
the
of
quartzites
and sandy clays
the
are
the
rocks.
underlying
and
orange
resting
red
an
striking
bedding
and
channels
are
sand-
almost
5
and
cm,
found. Coarse
were
the
yellow,
beds
clay
to
hori-
upon
white,
conglomerate lenses, with pebbles up
intercalated; locally clay balls
with
characteristic rocks
often white
colours, and
the
have
Riacos Formation.
unconformable
have
Basin
hence
alternating
most
slightly
They
Riello
and
of the Riacos Formation. The beds lie in
zontal position
in
gave
resemble
closely
south
the
included in
boulders
deposits
Vega de Ria-
Staalduinen (1969)
de Laciana,
to
The
Riacos Formation.
name
deposits further
been provisionally
fine
den
van
resembles the red bed
closely
age
of Villayuste.
post-Hercynian
north
stones
1973;
Tertiary
into different facies.
comparable deposits the
and
Staalduinen,
1969)
Mabesoone
The
through several
finer-grained
limestone boulder banks
gravitational
the top.
sandstone lenses that in-
cutting
the shifting
to
size,
limestone conglomerate banks
and filled with
strata
in
m
gravelly material well-
or
Thin red
stratification. Channels
derlying
3
1
rounded rowards
more
coarse
by calcite.
nearly
reach
may
is
conglomerate
tion. In the lower part of the formation, the poorly
limestone
Formation
Bosch,
thick
the
as
Riacos
are
cross-
common.
CHAPTER 3
STRUCTURES
insight
Real
lowing
summarily
The
de
folded
Prado
tending it
into
and French
follike
pioneers
Although
Délépine.
demonstrated
sheets here
the
with
multi-
the greatest
has elaborated and
enlarged
mapping especially by
semidetailed
covered
areas
Southern Cantabria
monumental work
and
Comte
thrust
Leiden school
with
picture
Comte's
early Spanish
expressed,
plicity of the
clarity.
after
Casiado
of
structures
the
that of
on
Barrois,
the
into
first possible
was
by
Upper
ex-
Carboniferous
rocks.
papers,
e.g.:
cia (1974), and
be entered
geometry
has been discussed
structure
to
The
into here. Rather,
of the
rocks
as
it is
in
the
in
their
structure
as
typical
and
structural
large part
ments,
Europa,
thrust
the
the
northern
segment
the
Picos
of
de
the
the
elements
of
the Ponga
arc,
E-W
the
represents
Hence
this
the
thrust
extensive
Europa
arc.
of
parts
Leonide
the
(despite
segment
and
all
The
southern segment of
N-S
folding),
contains
represent all
Asturias'.
the
vergence.
our
area
map
structural
enigmatic
we
complicates
covered
by
laeozoic
and
rocks,
revealed
are
the
evident
vergence
easy
(Riick-
North
picture.
is less
to
the north,
the
with
a
in the
southerly
are
San
also
which
are
vergence.
present
Isidro-Tarna
in
in
The
of
specify.
to
Picos
stacks
older
folded
area
westerly
most
begin
(End. I;
Narcea
maps.
mountains,
LEONIDES
structures
in
there,
the
den Bosch,
van
are
area
the
of
simplest,
the
so
we
Luna-Sil
Sheet
structure
divid-
1969).
tex-
the
de
complete detachment of the, largely lime-
sequences
thrust-sheets
The
shall
further than
go
folded with respect
Carboniferous sequence
sheets
the
and
Upper Carboniferous sedi-
older Palaeozoic. In
see
maps
structures
STRUCTURES OF THE
not
present
the
although backfolding
mostly disharmonically
underlying
stone,
is
not
to
with northerly
thrusting
style,
faltung) and faulting
in
covered by the
of these
the León Line the general picture
A
the
are
Nappes
of
in thrust-folds in
southerly
a
structures
'Knee
and
vergence
again with
these
Together
wellknown
sheets
easterly
an
area
number
The Leonides, south of the León
too.
folding
will
the
of the Palaeozoic
stratigraphy
Line have
area
subdivisions
hoped
expressed
between
be found in the
major
a
but the discussion will
Savage (1979)
interrelationships
tures
in
Julivert (1971), Wagner & Martinez-Gar-
sections. The kinematic analysis
the
Carrion
phenomenon.
The regional
of
pes) with
of
Pa-
multiple
(Ponga Nap-
Anticlinorium
The Narcea Anticlinorium is
the
ing
Zone of Lotze
brian
core
map, and
the
off
the
The
Slates
that
no
that
by
tion.
is
an
very large
(1945). Only
a
W
real
structural
Nevertheless
bedding
and
not
to
covered
such
evidence
mesoscopic
cleavage
been
there
as
structures
of the
by
the
done in
are
is
cut
Herreria Forma-
development
in
the
Mora
be found in the Palaeozoic sediments
essentially
affected this
of the Precam-
are
mapping has
unconformable base
multiple
Asturian/Leonese
small part
and the northeastern flank
former.
shows
a
Cantabrian Zone from the
Precambrian deformation
must
so
have
area.
The attitude of the Palaeozoic sequence demonstrates
the
later
development
of the
major
structure
while
the
large angle of discordance between the base of the Ste-
100
Prado Formation and that of the Cambrian Her-
phanian
reria
the
illustrates
the
Palaeozoic
(the
folding
Hercynian
of
age
least
at
is
sequence
much
otherwise
of
con-
Villasecino Anticline which
folds
lows
Salce Unit
the
The Salce Unit is essentially the SE extension of
Anticlinorium
blockfaulted.
These
of
pattern
outcrop
mation
outliers
faults
but
but
plane faults
along
the
present
Prado
normal
bedding
Lancara For-
the
effect
In
this
the
disappears
and
structure
(de
often
Sitter,
unconformable
the
As
in
or
the
simple, plunging synclines
norium
have
been
The
formed in
overturned
Babia Alta
relatively
-
even
the
otherwise
set
a
Alba
the
-
little dis-
ference of the N-S
of
of
by
The
the
Vid
La
with
upper
folding
two
IA:
the
Formation is
narrow,
(Encl.
9,
flank
synclines
between
al
they
are
folded harmonically.
places,
The
width of the outcrop of the La Vid
their role
in
decoupling these
them
individual
The
12).
of minor folds and faults in
than
younger
into broad
and
complex
but in
the
lower Palaeozoic
Shales demonstrates
syncline
north
with
of
axial
curving
Cospedal,
those
from
artefact
of
those
by later refolding.
so
the
true
an
be-
In
fold
fold
system
fact
the
probably
a
thrusts
of folds
into
axial trend shown
axes
is
anticline and
another pair
WSW
movements,
The
the
as
planes.
telescope
the northern syncline,
an
sequence
interpreted
is
accentuated
plunge
to
the
west
with the angle of plunge increasing in that direction. The
thrusting along
the
a
the
base
of the Lancara Formation into
Carboniferous San Emiliano Formation certainly
strong
easterly
components
may
component
of
also have been
faults around
movement
but
had
other
important.
folded Babia Thrust,
mation has
has
folds
thinned
of
harmonically
structural
sequence
almost all
pattern
is
the Babia
above the
Baja Unit,
La Vid For-
the distinctive Caldas Formation,
to
relatively
long
wavelength
of the Palaeozoic
dominated
by
the
between
folds
The
cal
are
the
is
structure
the
north
in
common
also
the
and
south
south
limb,
termination, and inde-
eastern
Ubina Structure is
those in the
to
West
faults
Asturian
1968).
in
maps)
the
The
thrust
and
west to
(not
&
1
to
den
van
into
on
kinematic
a
anticline
belong
to
Sitter
continues
western
supports
major
seem
(de
system
axial
which
from
movements
fold
The
Unit.
SSW and would
eastern
limbs,
overthrust anticline identi-
an
Babia Alta
Luna
wrench
50
:
model
000
with
here.
east
Unit
The Luna Unit,
rium and the
wedged between the Narcea Anticlino-
Babia Baja Unit, is
long complex Abelgas Syncline
the
Aralla Zone.
The
with
the
San
incorporating
sequence.
narrow,
Rozo
largely
and
has
been
rocks
made
up
the
by
the thrust slices
Thrust
Emiliano
Numerous
partial repetitions
caused
small
by
at
thrust
the
base
and
over
of
of the
refolded
space
The role of the
tions
as
The
opposition
Rozo Thrusts
the
Babia
shell.
early
lies
in
folds.
van
The
E-W
ever,
the
7
is
along
Knee
difficulty
the
the
then be the
of the
in
westerly
in
the
flank, and
structure.
is
particu-
would
a
the
appear
fractured
are
map
to
be
of the
nature
structures may
extension
or
a
the
and
sug-
accepted,
enormous.
nut-
struc-
correlations
somewhere between
westerly
extension of
understanding the
Villasecino Anticline and the Granjos
Line.
seen
of Asturias in
structural
den Bosch in
line
core
be
north
refolding of the thrust sheets
If all
extremely
a
the
(Encl. IA).
the
of Huergas suggests that the
ous
over-
along
of the thrust relations of the Babia and
Unit
Baja
to
either side of the
Much of the
here
tures
on
in the
to
are
detachment horizons
1
larly clear in Sections
is
La Vid and Huergas Forma-
Formigoso,
incompetent,
have been
zone
Abelgas Syncline
Similar thrusts
problem
Baja Unit.
sequence
back-limb thrusting along
relief for the
Babia
the
of the
the north flank of the
the Abelgas Thrust.
syncline,
of
upthrusts, and the whole
geometric problems
in which the Devonian
E-W
double-
south again.
the
Unit
Beneath the
This
the
terminate tectonic thickening of the La Vid Shales in the
gested by
Babia Baja
caused
inter-
the
result of the differences in the
a
sequence
normal
ridden by
In
as
has
broad,
the
Asturias with
axis.
synclinal
Lancara Formation
low.
dominated by the forms
illustrates
gener-
strong variation in
structures
closely.
very
W
strati-
West Astu-
least continu-
Devonian limestone formations have developed
systems
of the
disharmonically
at
anticlines
11
10,
or
sequence,
folded
faulted
Sections
regimes
synchronous
of
part
even
NE
north of Piedrafita de Babia. It is
developed but probably
ous.
the
both
westernmost
which
Leonides,
Parasitic
Bosch,
is the Palaeozoic
Narcea Anticlinorium,
characterized
the
flanks.
the
Unit
pe-
Babia Baja Units might
Syncline
trends of
plunges quite steeply
Unit
Babia Alta
and
Villasecino Anticline the
Tesa
IA:
1, 2 and 3).
Babia Alta
The
of
Syncli-
turbed NE flank of the Narcea Anticlinorium (Encl.
Sections
the
Herreria
Sheet.
Bernesga
vertical
near
1961).
of the
asymmetric probably
in
in
probably
Leonides. However,
Anticlinorium
eastwards although the Cambrian
plunge
is
unconformity
locally
north
stratigraphic
Formations
must
Narcea
the
under the
rapidly
Prado
of
core
from the
triangular-shaped
trend
other
through the Villablino Basin.
on
graphically and structurally the
To
The
folds
divergent
open,
The León Line
the Babia Alta
excluded
plunge
Precambrian
be traced
can
sense
mation is involved.
The
development of
much faulted.
general westerly plunge al-
against the Narcea Anticlinorium here, although
out
an
be
is
a
rian units resemble the Leonides
de-
faulting
boundary
where
For-
sedimentary
E-W
northern
the
especially
appear,
the
unconformable
dictated
velopment during the Stephanian.
dominates,
been extensively
only control
not
the
also
has
which
core
tight, and
so
Emiliano Formation.
ters
of the Narcea
the
San
formable (p. 78)).
not
are
the
How-
strata
SW
be discontinutrend
Fault. This
splay of,
the
of
the
would
León
101
The other feature of the
with
compliance
tightening of
the
the
is
decollement
in
and,
fact,
characteristic
concordance
apparent
rectly
the
overlying
Anticlinorium,
by
Stephanian
These
of
cover
evident in the
of
the
Palaeozoic
Precambrian
the
Villablino Basin
NW
not
been
in the
Mora and
southerly
the
subjected
Herreria
the thrusting
to
under the
and
not
are
Babia Alta Unit
These faults could imply
the other side of the Basin.
that
the
in
di-
Narcea
interrupted
are
disappear
structures
striking
strata
segments
the
Formations have
evident
movements
which
with
folds
and
tion of the Bregon
is
tion
by
no
can
varied
La
in
This
proved.
and
San
ing
Pedro
sociated
with
but the
of the
so
folds
the
at
mostly
do
much
the
to
base
the
tions
but
tight
bounded
at
inclined
are
of
The
where
In
the
eastern
are
by
very
the
isoclinal.
higher
dis-
This
possible
unit
Thrust
The
to
is
mostly
Pedroso
axial
Los
of
Pola
La
is
in fact
present
on
a
of the
Mirantes
Unit
Luna
distinct
the
structures:
Anticline
and
the
Abelgas
the
Alba
core
of
but
of the
the
is
and
simply
ed
to
east
of
sequence
axes
structures
south
Embalse de Luna,
Rio Bernesga
the
repetition
some
complex
structure
in the
west
with respect
variations
in
clearly expressed
to
the
the
the
edge
SW flank of
present in
only
of the sheet.
are
major
thickness
Formation.
the east,
the
are
4
to
is
structure
(Encl.
N of Mirantes
IA:
(Encl.
tight and fre-
well
as
faults.
201;
(Encl.
Sections
The
of
the
7, 8, 9,
the
Rio
a
and
by
IA:
by
E
10)
of
see
and
parasitic
apvan
other
fairly complete,
are
Limestone
number of strike
a
Mateo
San
at
in
syncline
the
has
axial
that the latter has the form of
so
Section
Staalduinen, 1973,
10;
1969,
den Bosch,
van
a
p.
183).
p.
Pedroso Syncline
The
Pedroso Syncline
ticline is
a
axial plane inclined
by
fold but
lated
to
a
the
to
rather
the
downthrow
the
Southern
the
to
axial
be
plunge is
area
in
Zone
continues
the
Flexure
steeper and
which
number of
a
(p.
the
distinct
Pe-
near
folds
splay
isoclinal. The
eastwards
a
to
re-
with
Ill),
nose,
practically
further
relation
step-faults
western
covered by the Bernesga Sheet in
be distinguished
and its
marked
are
obvious
no
synthetic
Boundary
south. At
along the north flank become
Aralla
The flanks
have
to
seem
Mirantes An-
slight easterly plunge
south.
strike faults which
two
the
the north of the
to
fold with
tight
the
through
broad belt with-
structural
elements
can
the Rozo, Pozo and Bregón Units.
-
Unit
Rozo
Unit
west
Mountain and
the La
Plata
due
evident,
cutting
is
possibly
the
in
upwards
area
Nappe
covered
has
been
asymme-
Correcilla Nappe
(Encl. IIA:
the
Lancara
two
if the
correctly
Thrust
Where the
two
being
to
the
the
to
El Rozo
extension
distinct
the
east.
in
thrusts
as
west,
of another,
to
fuller
as
interpreted
thrust
stratigraphy
much
thrusts
far
the
here
earlier
This
Cor-
development in the
the Torio-Curueno Sheet (see below,
the
Rozo
the
as
further
a
east
outcrops further
103). Kinematically,
sheets
bounding
reaches
by
the
southernmost
the
of folded
stretching
finding
In
structures.
sheet which only
recilla
the complex
of Villamanfn
members
convergent fan
Torio
the
cut
being
east
sheet;
map
faulted asymmetric
a
continuation of
double
apparently
Complexity
culminating in
of minor folds in the valley of
As shown
competent
the
to
of the anticline
van
Of
18).
Santa Lucia
are
asymmetrically develop-
structure,
coloured
1973, fig.
the
and from the
IIA)
the
be-
as
San Mateo, 2 km
de Gordon and
in
IIA)
folded. The broad
complexly
only those of Mirantes
the
of Mirantes along the shore
cross-sections
to
in
north of Cuevas,
(Section 5)
within the Cuevas
try increase
to
major
as
de Gordon
errors
south and
Alba Synclinorium
causes
The
clearest just
structures
the
Rozo
in the uppermost Devonian formations. Subsidiary strike
faulting
1
Pedroso
north.
to
Alba Synclinorium
syncline,
Sabero-Gor-
the
as
the anticline between the Alba and
well
as
Barrios
minor folds
The
The
is
zone
tween
indicated
the cross-sections
on
Synclines.
quently faulted
droso,
cross-sec-
Staalduinen, 1973, figs. 20 & 21).
part
Syncline from south
Rozo
as-
development of the
the
the
recumbent,
even
Formation.
is
than
van
the
Synclinorium,
stage of
but in fact represents
box-fold (Encl.
clearly
through this front which
into three
splits
south,
the steep
Lancara
complex
1:50 000 scale (see
Syncline
Zone
zone
boundary between the La
occasionally
extend
not
more
be regarded
may
few cascade folds, probably
Mirantes Anticline is
dón Fault
that little
involving only
the folds
the
to
north by
the
Staalduinen's
Van
map.
Mirantes Anticline
Bernesga
Vid Shale and limestone members. These intraformational
the
on
a
late
a
have
Formation
structure.
the form of
connec-
characterized
Formations;
seen
se-
continua-
a
development of disharmonie fold-
extreme
in the folds
occurs
is
zone
tight, mostly
Santa Lucia Formation is
harmonie. The
west
Devonian
as
with La Vid
contact
folding, usually
Vid
the
mapped
since
clear,
means
be
is
Thrust further east,
Valley San Pedro is
throw
Thrust
of the Bernesga
area
repeating
faults
Abelgas
The
quence.
folds with
parasitic
Staalduinen,
Zone
The Aralla Zone continues into the
Sheet
evident
Cuevas
of intraformational minor folds
(1973) shows that the majority
preciable
Aralla
of the
series
a
not
are
analysis
as
The rocks
13).
developed
(note that San Mateo has been remapped because
rocks.
younger
Section
also
the
despite
sequence
of
core
Leonides
1971; Sava-
realize that
to
long E-W
very
strike-faulting.
on
of the
of the mountain chain (Julivert,
1979). It is also important
ge,
predictable
to
by incompetent levels in the Lan-
feature
a
the
Vid and Huergas Formations. This
La
Formigoso,
cara,
leads
that
so
sequence,
folds
concentric
disharmony facilitated
here is their strict
structures
lithologic
cut
as
southerly origin
interpreted
downwards
the former
thrusts
Formation,
then
into
structure
only effect
a
p.
of the thrust
the
this
implies
underlying
moved north.
double outcrop of
together with portions
of
the
102
south
Oville
and
of
Rodiezmo,
thrust
Inverted
too
small
this
has
slices
scale
a
be
to
20 & 21).
the isoclinal folds
of El
Pozo
refolding
in
the
to
It
west.
folded
The
be
to
all
as
trending
measured
inverted
thrust
only
part
a
seen
on
be
west
expected
rocks
Lena
the
the
to
so
slice of the
Collada de
must
Structure but
interpreted
be
as
Althe
disappear
to
direction,
seems
thrusting/gliding
The
Devonian inlier of
with
The
ly
structure
Pena
at
to
Oville
been
Formation
in
the
northern
flank
through
by comparing
the
rio-Curueno (End. Ill)
The anticline
thrust inverted
fold axis
the
The
further
through
cilla Unit
the Pozo
as
full
the
explain
is
essentially
be related
to
to
the north because
the
to
well
anticline
map),
to
Upper
Prado
the
with
Nappe
Bernesga
some
not
by
rocks,
Pozo Thrust
the
until
folds
This results in
a
west
sign of
no
of
Buiza
the
La
the
and
is
close-
Vid
plane
far
as
nose
Bregón
as
corresponding syncline
a
Rio
but
Bernesga,
Tolledo
and
periclinal
a
San
is
one
Pedro
west-
completely
Formations.
through the Barrios Formation the
cuts
been
have
others
into
thrown
the
all
tight,
La
thought
to
shown
on
the
Campa.
At
the
short
a
in the
seen
There
east.
south
because
there
the
more
Pedroso
the
where
the
on
the
Bregón
even
of the Bregón Unit
rocks
pre-Stephanian
from beneath the
of
exten-
rest
and the Esla Nappe
west
be little
can
do
they
as
outcrop
represent the
Bregón Nappe since these rocks
Formation just
Huergas
and
Bregón
of Lancara Formation is
of the
(not
tip of the Matallana Basin
easternmost
which
Matallana Basin form
and
Syncline
the
a
Mirantes
Anticline.
must
taken
be assumed that all
part
which
We
the south have
structures to
in
the
no
corresponding change in them westwards
could
there.
northerly
accommodate
have
the
conclude
to
of
movement
absence
that
the
the
of
thrusts
the
thrust
deformation
total
is
and that
anything,
we
differences in
see
the Tostructural
over-
the
style
to
be
involved.
quence
but
vergence
correlated with
This
should be regarded
as
that
implies
the
lithological
the
thrust
se-
faults
having been generated in the axial
planes of the folds such
they die
dip
shown
traces
structure
Torio the
is
be
to
Pozo and
as
The
Bregón.
fault plane
Corre-
Lancara of
with
contact
Further
evidence
is
Upper Carboniferous
Correcillas
village
and continues eastwards
bilateral symmetry for
upwards in the incompetent
makes the form of
classic
a
nappe
much
La
way
Vid Shales
more
unlikely.
Cueto
Negro
Unit
North of the Pozo Thrust front the Cueto Negro Unit has
the Cambrian
Valley
off the Correcilla Unit
out
rather than di-
brought into
of
folds,
between
varied little if
with
in the basal
limestones.
just
Pedro
NW almost down the
and
unconformable
reappears
Valdorria cutting
This
error.
south, and the
south
itself. In the Torfo
Carboniferous
San
structure
Unit with
thrust
Limestones
occur
but there is
has
folds in the Palaeozoic of the
as
the
east
plunging
Sheet).
development of this
Rfos
in
Lucia
steeply
The
(N.B.
west.
of the
variations in axial
many
of
an
the
to
in the Torio-Curueno Sheet.
east
is
thrust
continuation
colourprinting
Lancara Formation has been
obscured
the
responsible.
plane. The divergent axial
imply
above
syiisedimenta-
Bernesga (End. II)
is inclined
Between the
cuts
has
still plunges quite steeply
map
rection.
seen
core
by refolding
of the axial
dip
on
del Pozo
out
a
alternations
that of the Pozo
west
developed
Plaza
distinguished from the San Pedro Formation of the
clear
folded
because the
unimposing
very
in the Bernesga Valley the
to
wards, between
It
die
in
southerly of the Leonide
most
it is
between the Rios Bernesga and Luna.
Mountain. There
below
further
have been
Villasimpliz
they both
way
east
Thrust is last
that
likely
which
nose
the
although
involved
similar
appear
overridden syncline of
of the
is
plunging
to
Pozo
zone.
Bregón Unit is
thrust
sion
the
Pozo Structure
The
complex
Unit
Bregón
Santa
down-faulted
a
inadequate
more
movements
overthrust periclinal
a root
and the
indication of the
an
through
evidence of such
no
connected
is
simple faulting
outcrop pattern. It
proximity of
be
may
flank.
Valdepiélago
near
deformation here,
severe
redoubling of the Lancara
curving
the south
on
and brecciation
folding
more
suggest
complications
map.
Carboniferous/Upper
Alonga
complex
m
about
in the surrounding Carboniferous rocks.
Lower
The
Where the thrust
Rozo Nappe but there is
structure
curious
been
number of
a
pp.
that
The isolated strip of Lancara and Oville rocks
Perïa de la Plaza has
and
termination of
eastern
steeply plunging,
a
map
south.
that
in
axis
Further
the
on
the
to
the
at
Syncline
and La Vid rocks
1969,
Bosch,
common
would
300
Aralla, possibly
near
so
than
Barrios Forma-
shown
Montuerto
the Pozo Nappe is tight, with
thrust sheets,
refolding of WNW-ESE
plunge
axes
sheets
be
can
trends
occur
axes
den
van
later
autochthonous
beneath the
indeed
in
fold
result of
trending folds such
ry
to
The
Formations
be less
may
part of the
upper
curving
the
NNE-SSW
a
but
maps
correspond
Oville
well be that
may
on
Staalduinen
van
seem to
and
mostly
50 000
:
1
on
of the folds
Aralla Zone
the
150-151).
most
shown
These folds
the absence of the
seem
been
the Barrios
in
wavelength
the
tion
un-
usually competent Barrios Formation is involved
of the
(cf.
have
been adequately illustrated by
(1973, figs.
as
folding,
autochthonous Lena Formation has taken place.
derlying
as
complex
faulting of the slices together with parts of the
the
through
entirely
again.
the latter,
coin-
cident with the variation in axial plunges found
(p.
103).
the form of a large anticlinorium dominated by the Lower
Cambrian
Palaeozoic
Herreria
Formation
sequence,
dle-Upper Devonian
flanks
and
impossible
the
to
in
in
core.
north
Caldas
western
map
its
The
whole
Formation)
is
seen
termination. Faults
the
of
Leonide facies
Herreria rocks
but
are
the
(Mid-
on
the
almost
they
must
be present in the Sierra de Cueto Negro and in the tight
to
synformal
cause
The
extension of the
of the relations
contact
Formations has
latter should
between
the
part
cover
Lancara and
been mapped
take
Villasecino Anticline, be-
with the Palaeozoic
in the
as
the
stratigraphic
structures
so
rocks.
Herreria
that the
that plunge
to
103
the
is
of such
core
lated in the axial
Anticlines
marker
beds
detailed
in
concentric
recognition of
the
Herrerfa
the
Sierra
section
cross
be
can
do have
interpreted
similar
largely
to
The involvement of the
suggested
cada and
much
structures
the
structural position
the
Leonides
is
also
con-
to
that the anticlinorium
thrusted
makes
comparable
more
(see
east
the
to
the
For-
104), and since
p.
similar,
of
comparable role if
a
be entertained.
may
in the
as
the thrust
striking massif
a
terrain. This is the result of
sheet into
map
refolding
with
large synclinorium
a
the
on
a
of
double-
plunging axis. Rocks from the Middle Cambrian Lancara
Formation
the
to
up
Namurian Caliza
thus been preserved between the Rfos
rueno.
At Villamanin,
thrust,
where
it
developed
at
is
the
Torio
in
which,
Sancenas.
The
into the axial
from Gete
two
of
the anticline
Unit
in
the
complex,
the
Formation.
is
synclinorium
having quite
a
at
with
a
the
clear
very
west
steep
here
de
cutting
be
can
traced
therefore
must
well
the
the
and
the
closure
the
map:
more
folding
occasionally
in
the
it
and
Oville
of
fold
the
axes
here.
of the
thrust
with
the
the axial
typically
form
clearly
folds
itself
their
Formigoso,
The
been
of
most
its
outcrop.
so
affected,
synclinorium,
the
intraformational
largely
theoretically
The smaller folds
disharmonie
upper
over
it
along
minor folding
the interior of
contrast
disharmonie through the varied
makes
of the
revealed
in
nappe.
has
mapping.
zone
a
a
the axis
much
more
syncline
with
the
are
with
an
form
clear.
very
limbs
longer
synclinorium suggesting
latter.
The
axial
directions
simply refolding
than would result from
minor folds
pre-existing
in
but
real
no
has yet been made.
analysis
The Namurian Caliza
together with the
de
Lower
Alba Formations,
the
Formation is folded
Montana
Carboniferous
well
as
Formation although
as
Vegamian and
Upper Devonian Ermita
the
of
extent
these
of folds
types
be traced very far because of the lack of markers
cannot
the
in
of the
is
picture
map
variations
for all
asymmetric
are
relation with
parasitic
vary
Caliza
Montana.
de
These
formed by mesoscopic folds
rocks
well
as
often
are
de-
extensive tectonic
as
The Gayo
is
Unit
only discernable
of the Rio
east
unlikely
which
are
is
in
in Pena Fontón, and terminates against the Porma
Fault
in
cause
In
the
west we
faulted
see
the
overturned). From the
follows
the
entire
thmst
base
of
of
often
and
to
axis
plunges
to
few small
a
Formation for
For
the
W
in the
appear
be found
near
faults
most
and
of Almuzara,
been accompanied by
alization.
Mylonitization
axial
traces
nature.
The
of
the
the
cut
disturbance
Barrios
parts
of
Syncline
affects
the
shows
the
follow
in the Pozo Unit
post-thrusting
of the
unit
axes
fold and the
mean
that
hundred
metres
the tendency
to
steep
to
NNE
folds
to
must
easterly
eastern
have
the
minor
higher
Montuerto
NNW
those further
of the
plunge
developed
west.
extent
In
the
the fault
upwards into the Gayo Unit
dón Unit
to
indicates
the earlier existence of
to
The
the
although the tightness
Caliza de
the north. It is
of
and
miner-
where
some
Formation.
form
of its
cut
and downwards into the
doubled and
the
these
in relation
the
near
Valdecastillo
at
of
near
the former location the
is also evident
nappe
been
last few
La Vid and Huergas Formations have
number
a
considerable lead-zinc
Lancara Formation has
line
demonstrates
shales
of
disharmonically
variation in
at
The
striking
brecciation extends far into the Carboniferous rocks
has
the
San
southern flank
developed
rocks
At
Valdeteja.
almost
the thrust front.
have
pseudotachylitic
Pena Fontón and
are
part
Carboniferous
Upper
Valdeteja and
near
subsidiary
The
where all the beds
Lancara
outcrop.
older formations
synclines
frontal
but,
be-
been eroded.
of this fold the thrust plane
core
against
rests
Emiliano rocks
lenses
of
has
only refer
map
structure
of the
length
sheet
thinner than
dip of the south-inclined axial
the
on
of the
core
is
characteristic plung-
most
terminations.
down the
plane (the symbols
folds in
sheet
sequence
of the
one
pericline
NNW
steeply
the
The
Valley.
inclusion of Carboniferous rocks
the
much of the Devonian
the
ing
Porma
despite
most,
that
concentrated in
and the
Ber-
nesga
termination
reveals
only
folded
strongly
are
stratigraphy of the
nature
towards
the
the
typical
vergence
they
general
dipping
and
are
they
mylonitic
plunge
synclinorium,
unit is
These folds
and the southern
In
Here
west.
plunges
Correcilla
the
beyond
places, notably where the Barrios Formation is
more
intraformational
limited number of places;
this
the
to
but
west,
cross-section,
exact
Horzal,
near
becomes
Montuerto
of
that
developed
Fuentes
While the overthrust is usually overturned in conformity
and
incompetent and detachment
as
west,
east
steep
very
almost
the
extension of the Correcilla
with
Lancara,
East
from
In
rapidly
138) would have it, may
easternmost
through
largely
Thrust,
genetic connexion between
a
p.
Curueno Valley
of
faulting
over-
Formation
is
the
Torio. This fold
(1967,
cuts
Santa Lucia
south
swings
the Rio
have existed. The
the
Formation.
thrust
frontal syncline,
a
thrust
Evers
as
the
to
predate the fault although
the
Lancara
the
edge of the unit in
plane
near
the
of
up
form of
Bernesga and Cu-
Bernesga Valley,
however,
northern
de Montana have
from beneath the Rozo
base
the
sequence
the
along the
in the
appears
Valley,
through the
both
gentle
are
In
Gayo Unit
Correcilla Unit forms
well
as
principal role
horizons.
dolomitization.
Correcilla Unit
The
the
played
anticlines
Bregón Units.
Pozo and
along the northern boundary
very
direct connection
not a
a
1968). A
al.,
et
Herreria Formation,
Bodón Units further
more
younger Pa-
1) constructed from the
two,
of the
of
of complications
sort
shows
least
at
as,
those
lack
Negro is
also Martinez Alvarez
we
Robledo
the
inlier of
del Cueto
(End. X: Section
little data that
but
Formation renders
firmation of the presence of the
be expected (see
problem
space
folds. Faults postu-
this
The
impossible.
in
of the
of the Villasecino and
planes
mapping
laeozoic rocks
in view
tight,
express
the
geometrically impossible for
conform entirely
to
in the
it
However,
west.
latter
tempting
Montana of the
to
E-W
imagine
symmetry
that of the Correcilla Unit (p. 104). The dips
Bo-
that this
are
similar
gener-
104
ally
in
overturned
steep,
attributed
the
sidering
folds
cut
San
overturned
flatlying,
primarily
the
in
although
The
some
thrust
refolding
is
con-
plane; however, the
have been
must
attitude
inverted
post-thrusting
the thrust
temporaneous if
north
Emiliano Formation result
beds.
the
to
attitude of
off by
the
to
small folds in the
places
least
at
con-
older.
not
include the
we
Palaeozoic
nian erosion which
Formation
In
maps.
sits
Bodón
Rio
Torio,
Unit
is
only
although
be that this unit is
has
as
the continuation of
than the
younger
nates
of the
Formations.
San
Emiliano
longer that
from the Oville
sing,
of the
section
here
will
the
The
Lancara
of
but
Upper
Montana
horizon
glide
of the
one
many
it
is
but
since
faulting
to
the
been
great
so
in the
as
Formation
Bodóns
two
N
as
dips
never
be
can
the
by
Porma is
clear that
the
less
at
Unit
vertical
The
eastern
the
essentially
the
likely
are
(not all
the
a
on
the map)
Caliza
cross-
that
de
detached
as
ap-
near
small folds
many
well
by
cut
the Porma Fault
as
the
of the fold.
asymmetry
deformed by
strongly
lomitization of the
bed-
component of dextral
a
fit
termination against
Valdecastillo is
and faults
with
would
extensive
do-
Montana Limestones. The
Barrios Formation is also altered from the usual resistant
quartzites
just
west
to
loose
a
sand
of Valdecastillo.
steeply
overturned
steeply
NNE
with
associated with
here
a
few
beds the
for
quarried
The majority
so
that
most
shallower
right
way
mation has clearly been associated with
dicates
least
at
movement
the
sense
a
considerable
although the folds
of
of the beds
the
to
glass-making
fold
up.
axes
east
This
and
extra
are
plunge
not
the fault and in-
clear in
suggesting
is
only
the
Torio
Rios
most
northerly of the Leo-
and
Montana
in the
unit
much
are
these
simply
view
of
that
to
slices
plunging
in
of
As
The
has
been
imbrication
the
is
frequently
map-
much less
very
fault
trend
once
not
are
downplunge
a
is
style
Not
subse-
synclinorium
affording
tectonic
of Montuerto
been
suggesting that,
in the
refolding
although
shown.
have
axes
Z-fold,
deviations
unit.
of
to
the
to
mapped in the
doubled
generally
the
limb of the
the south
Unit.
than
plunging
have been
The breadth of the
large
the
structures
complex
more
small folds
are
sliced-up,
question
a
and
of siliciclastic depo-
in all three thrust slices
folded around
the N-S
strati-
Bodón Unit,
ped between Canseco and Redilluera
than
present
is
The outcrop pattern follows that
formations
reminiscent
of
the termination of the
at
suggested, it
may
indicates
proximity
the
well be
that
of the
overthrust.
an
The
Armada and
Sheets,
correlations
Porma especially
if
-
the
in the
ment
of the
two.
The relation
the
to
is
unconformities.
so
The
although
way
have
movements
thrust units
the
whole
of the
quite
The
steeply
to
the
last
have
contacts
implies
the
units
westerly
of
post-Westphalian
the
contacts
Rupke (1965,
must
would
unconformity
many
suggested by
Thrust
in
pairs
involve-
have been thrust in the
certainly
conclusions about the date of
there
of the
Westphalian and
faulted
extensive
Almost
Leonide
first
exclusively
must
disturbed
as
the
These
by the
picture strongly
map
this phenomenon
cidentally
in
Esla
Bodón
1965).
together with the
correlation with
hardly allow of this.
the
the
and
levels reached
surrounding
close that these rocks
same
-
equivocal;
been observed whereas
is
Oville
last
the
on
appear
Forcada
Rupke,
the
Herreria Formation
rocks
Stephanian
(cf.
suggested by
Barrios
the
to
respectively
are
Devonian erosion
and the
Pallide Subunits
belonging
klippe
as
be
expected
front,
p.
with
59). In-
along
the
rendering general
from relations
movements
limited in significance.
beds
in
the
Armada
and
almost everywhere and
60 degrees
to
between
N
and
Subunits
Pallide
plunging
axes
W
have
dip
50
steeply
folded them
to
yield the existing outcrop pattern. Revision mapping has
revealed
the
that
and
I
:
the
structures
are
synclinal
Viego
50 000
unconformable
The Forcada Unit forms
Formation
the
on
slopes of Pena Forcada, complications
reappears
the
quently
on
Forcada Unit
nides
it.
NW and NE
as
overturned beds.
Reyero
movement.
between the
Oville
the
west
defor-
component of strike-slip
are
de
sequence
Occasional
east
the
abound;
Thrust
Emiliano Formation
faults
parent throw which
well
as
Since
flanks
in the San
above
segment
latter. In the
Sheet
to
is
north
further witness
therefore
thin
Lancara
Armada and Pallide Subunits
be-
where
picture
Caliza
thinner than
west.
or
of
mainly
map
east
root
Bodón
the
not shown
the
steeply,
folds, and it is
the
N-S
sort
than 60° around the Z-foId
these plunge
the
this
near
a
in
Pozo
seen
the
very
a
preserved
Cueto Ne-
considerably especially
The
much
only
faulted-out
from the former. The middle limb of the Z-fold is
several
de
of Valdeteja.
Z-form exhibited
overturned.
seen
is mis-
Caliza
dolomitized. The
strongly
have
varying
of
sequence,
reached deep into the Oville
usually
Occasionally
addition
The lower
Upper Devo-
to
of the Bodón Unit in the Z-fold but the internal
again,
major part of the
refolding of the Leonide Nappes.
section
folds
de
Upper Devonian erosion had reached well
the
almost
west
a
the Rios Curueno and
the
axes,
is
Barrios
great
tween
are
due
not
because
eastern
to
Caliza
the Alba Formation inclusive,
to
probably
Montana
ding
thicker
even
this unit therefore the basal
In
Near Bodón Mountain
gro
the
and
sequence
intervals within the Herreria Formation.
shaly
into
this unit also termi-
east
Herreria Formation and
Carboniferous,
no
forma-
mapped through
main unusual features: the thick
two
are
the
be
the
rate
any
can
in the
structure
a
well
may
the great Porma Fault in the Porma Valley.
against
There
is
To
continuous outcrop.
as
At
Barrios
of the
east
suggested it
been
Cueto Negro (Bernesga Sheet).
tions
definable
clearly
much thinner due
has also been eroded but this is
there is
The
here.
graphically
Bodón Unit
Armada and Pallide Subunits.
section is
map
Upper
appear
probably
are
to
much
structures
more
although largely
Carboniferous
be faulted
detached
at
the
east
concealed
cover.
against
base
further
near
extensive than shown
one
of the
by
the
All of these
another and
Lancara For-
105
mation; however,
the
mation
correlation of the
suggests
Units.
ably
The
absence
due
not
but
cover
a
plane here.
All
Herreria Formation is
of the
likely
to
these
Esla Nappe in the
For-
the
unconformable
suggest
complications
original
an
along the Porma
movements
Fault will have disturbed the relations
observable.
now
de
Valdoré.
which
prob-
slicing of the thrust
upward
an
later
termination although
Barrios
the
Bodón and Pallide
concealment under
to
more
involvement of
Esla
the
X:
8)
indicated
the
comprising
as
the structural sketch
on
Nappe itself in
the Agua Salio
map
the
Ridge,
Pardomino
Valdoré autochthonous, the Las
or
Esla
and
nappe
relation is
tions
5, 6).
Pardomino
Salas Zone and
Las
the E-W trend of the Leonides in
Formation interrupts
absence
known although it
contrast to
seem
to
plex:
and
more
com-
the
completely
have
The
contact.
structurally
are
folds
Lancara
con-
been
even
the Ridge
the
the S
to
stretch of the
of
many
inSW
com-
intraformational
are
Formation
it
is
evident
involve considerable thicknesses of Herreria
that others
and Oville Formations.
Palaeozoic
The
Pardomino
Nappe
is
but
still
is
the
the
strong.
There
the
and
doubling
structures,
with
contrast
reria, Lancara and
the
away
Lancara
from
is
in
and
it
perforce
these
earlier
an
is
forming
constructions also
the unnamed
in
also
Pardomino
so
with
least
is
the uppermost Her-
that,
the
some
La
proba-
was
Vid
are
Formation.
which
Syncline
is
Drag folding and mylonite
developed along this
be observed
Valbuena,
near
component of strike-
Valbuena
structure.
Ridge they
similar
those
X:
Secthat
imply
anticline between
be detached
must
Synclines
to
the latter
(Encl.
that
so
we
may
along the Pardomino
there
tight
along
typically
also
are
as
shown
usual asymmetry
slip fault
the
are
V
whereas
cannot
it
is
the
since
(compare
and
and
former
fractured
heavily
unconformable
whose
Barrios
the
Yuso
Oville
is
still
and
Sheets
Formation
quite
small
by
For-
beneath the
east
established
Esla
disap-
Cea
thick,
faults
that
be mapped.
The
coincides
zone
Line which
is
with
the
regionally
covered
usually
Here the evidence of
of tectonic
can
activity
and
sequence,
the
complex
a
be
read
faults and
history
of
from
folds
important
youngest Car-
by
boniferous deposits.
have
are
strike-
structures
Stephanian
to
the
on
The
VI)).
folded
of
many
sinistral
to
the
west
and
been
mapping
and
little
thinning of
relation
a
the
Salamon,
recently
has
contrast
(Encl.
To
Lechada Formation
Westphalian
relation
although
small and
are
planes of these folds
unconformable
the
map)
often steeply plunging while the
axes
suggests
movements.
beneath
pear
the
stratigraphic
the formations here. The axial
subvertical and the
large number of
the
on
small folds. The latter
many
result of the
a
typified by
than
more
a
the
long history
stratigraphic
recorded
well
may
development, extending far
back beyond the Hercynian
orogeny
(Koopmans, 1962).
decollement
The faults increase in apparent
Ridge
at
Esla
NE
the
to
of
Oville Formations
the
well
very
may
has
off
cuts
structures
redoubling
contact
This fault probably
slip
the
the
would sug-
maps
development
lower
bly preceded by folding.
throw
than the
the
of
north of the Felechas
contact
complicated
more
the
conformably overlying
autochthonous
excellence. The
par
Syncline
gest
these
Zone is
Salas
(many
León
sequence
Ridge
overlying
depth here.
mation around
not
transition beds
E-W
involve
only
if
stratigraphic,
extremities of
although
are
the
exactly
not
boundaries, those
W
the N and
the shaly
-
are
that they
likely
markers
the Torfo Sheet.
on
be
dicated along the
and NE
correlable
truly
seems
plex than indicated
formable
of
within the Herreria Formation
structures
a
since the
through the five structural units there.
cuts
Due
E
its northwest flank
on
way
Porma Fault
the
Lower Cambrian Herreria
of the
Ridge
in
been
Salas Zone
faults
Ridge
particularly striking
In
fact
structures
at
Ridge
the
pattern, and
sections
cross
level of the Lancara Formation,
expect
have
segments, the Felechas and
two
Synclines.
The Pardomino
and
In
older Palaeozoic
the
both
to
Vellila
as
of Valdoré
rocks
Devonian
clear from the outcrop
construction of
the
at
far
as
window
the underlying older Palaeozoic. The former
from
The Las
to
autochthonous
the Agua Salio and Felechas
Unit
The Esla Unit is
(Encl.
the
enter
we
disharmonically folded in respect
the
Esla
the
Agua Salio Syncline
Here
fault;
other faults
while
near
the
absent from the Esla
Esla Nappe
Esla
The
s.s.
Nappe
is
s.s.
unit
a
defined
in
extent
the
above (p.
by
ments
Esla
Pena
the
Syncline,
Corada
Unit
1965; de Sitter,
the
of
X:
the
mentioned
three
seg-
Valdoré and
the
of Sabero; these
are
and
the
Agua Salio Syncline
Encl.
(see
Unit
divided into
Unit
molasse
Stephanian
an
its maximum
definition excludes
Bregón
is
autochthonous
unconformable
the Felechas
with
The outcrop
102).
the
This
Valley.
correlation
possible
covering
as
between the Rios Porma and Cea with
area
Section
6)
(Rupke,
1957).
and other larger thrusts.
The rocks
buena
They
below the Esla
Syncline
mostly
are
faulting
is
the north.
per parts
even
of the
while
be
more
folded
severe
are
many
in
because
east
faulted
Las
are
although
Salas
numerous
in
Zone
folded
to
the up-
of the marked
of the units here.
inverted,
of the Val-
parautochthonous.
and
the
small and
sequence
of
Thrust and
considered
strongly
The folds
graphic thinning
the beds,
must
strati-
To the south
together with the
Felechas
Syncline
The Felechas
rection
by
Formation.
Syncline
the
to
the
The
map
syncline, following,
but
shows
not
the Lancara Formation. The
tric
than
little
as
the
50° N
west
unconformable
map
over
suggests,
is
cut
off in that di-
Cretaceous
the
thrust
always exactly,
structure
the
north
is
Voznuevo
outlining
the
the base
more
of
asymme-
flank dipping
much of its length (ref. overlap
as
Torio
106
This
Sheet).
flank
opposing
implies
plunging NNW,
that
gentle
very
axial
an
along the south
dip
plane dipping north, and
is
attitude
an
for
typical
axis
an
Beneath the
thrust,
appear
towards
the
tions
evident around
the
are
syncline
of
the
Pedro Formation
They
sitic
Vid Formation,
beds
of
between
There
these
is
smaller
folds
eastern
of the syncline
nose
modified by
would
N-S
Salio
Agua
V:
(End.
is
plane
Esla
is
Syncline
the
to
para-
the
have
to
folding comparable,
End.
Sheet;
Felechas
The
it
thrust
is
Valsurvio
indicated
where except
along the
where
of the
the
sharp
and
Rio
the
sheet
vertical.
It
Unit,
must
feature of the
during
thrusting
Rupke
(1965).
Salio
is
Syncline
tempting
be
-
into
the
de
north
of the
rest
individual formation
structures
makes
in the
fault
plunge
at
planar
was
an
and
(1957)
flank of the
Agua
thrusting, and it
structure
various angles
as
a
con-
unconformable
cover
The
sheet
that
suggests
southward beneath this
What
Nappe
be
is
clear
than
inclined
exact
the
the
E-W
extent
to
and
thrust
plane
east
these
near
significance
N-S
eastern
N-S
part
axes,
typified
very
of the
(1962,
Valsurvio
maintain
to
Fig.
1), and the
thrust-folds of
the
Leo-
is
fairly
correlation
vergence of the
consider this
structures
assignment
as
cor-
unit south of the León Line. Koop-
a
summarizes
220)
p.
Esla
uncon-
the
structures
fol-
as
"Several
the
two
sets
found south of
folds
are
de
these
la
folds
have
folding phases
effected
characteristics of
lithological
In
the present
the
area
has been worked
the
different types
units, according
to
the
outcropping rocks.
following
of
sequence
events
...
out:
structures.
differences
lithological
the
and upheaval of
have determined the
caused
of San
zone
mode of
the
by
subsidence
Martin-Camporredondo
deformation in the various
areas.
The
Middle
sandstone
cumbent
isoclinal
This
cleavage.
on
and
only
Upper
folded
are
in
planes
large
dipping
When
of
passing
San
a
in
E-W
re-
nearly horizontal slaty
a
cutting
cross
in
the bedding
to
the
hinges.
The
Devonian quartz sandstones
gether with the massive
axial
slate-limestone-
folded
is almost parallel
cleavage
competent
Devonian
intensively
folds, with
the limbs and
thick
Lower
alternation is
limestones of the Ruesga
E-W
trending isoclinal
from
60°
down
S,
to
folds
nearly
to-
group
with
hori-
cleavage development.
from the Valsurvio dome into the
mode
Martin-Camporredondo
of
zone
deformation
changes with the lithological change from large isoclinal
folds
into
low-angle
ESE-WNW
trends and
over
zon.
the
incompetent
The
about 2.5
maximum
which
overthrusts,
are
thrusted towards
Lower Carboniferous
measured
lateral
the
griotte
have
north
hori-
displacement
is
km.
which
by
axes
Oceja
of
be-
curves
evidence is
near
east
Formation.
The interference of these
south
the
Cea
directions
responsible for the vertical
Remolina. Further
and
that
has been folded along
later
Agua Salio Syncline.
may be
the
but the
cover,
is
of the
the
to
the
disappears
sequence
neath the
may
befitting
in the
85 &
lithologic
northerly
to
the
different
p.
of deformation in these structural
through
developed
-
Sitter
are
East
various formations above
the whole
result that
Esla
the
zontal and without
Barrios. These folds
tenuous.
and
(see
typical
the
it reasonable
and
rect
the
not
are
reappear
sufficiently
names
Nevertheless
complete,
number of intraformatio-
a
with
map
is
sequence
of the
east
distance by
Formation of the Valderrueda
Dome
The
relatively
a
essentially
initiated during the
was
The frontal anticline bears
the
Cea
Stephanian
First generation
map.
upwards
a ramp
by
the
essence
folds
refold-
by
been suggested.
Leonides
some
Where Devonian rocks
every-
sequent result.
nal, parasitic
for
Basin.
south.
syncline,
accepted that this fold
proposed
as
the
to
the
on
folded
remaining
structure
couple the
to
of the
structures
concealed
are
formable
dips
folding and faulting
here
fault
original
In
the change
be accounted for
in the
developed
as
inclined
simple planar fault
a
minor
is
thrust
involves
structure
main fault slices
the
The
quite shallow
to
The
and
Leonides
northern flank of the
which
anticline,
the
Section 6).
frequent than indicated
Esla
thrust
X:
sequence
as
of
complications
more
has
as
axes
and
planes
exposed
Dome
older
The
striking
most
in
seen
varies
asymmetric
is
perhaps
be
Syncline.
the full Lower Palaeozoic
Leonides:
perhaps the
to
nappe
often vertical but
opposite the
of the axial
of
north of Sabe-
lows:
folded
a
Cea
of the constructed
unconformity just
already
The lateral offset
mans
The
terms
isolated patch
ing along N-S
Agua Salio Syncline
example of
the Cea
the
the
contiguous, with those of the Valdoré window.
not
also
to
San
and
seem
logical in
very
and
Lancara below
nides.
been considerably
is
cross-sections
of plunge would then have
Barrios
obvious
no
the
by
suggested connection of the Felechas and Agua
Synclines
ro.
structure.
The
The
but
have dictated the di-
to
covered
do-
nature.
with respect
even
is
intri-
the
of their
something
appear
major fold.
relationship
major
of
core
certainly with the massive
Formation, which would
mensions of the
The
upper
disharmonie probably
are
structure,
also involved in these folds and the
are
basal San Pedro, but
but
The
pattern therefore shows
map
here.
La
mainly the
comprises
cately folded and faulted.
Complica-
extensive tectonic
by
limestones
south.
of the
nose
their elucidation is hampered
lomitization
and
east
formations
younger
much
so
of the Valderrueda Basin.
Salio
consecutively
gradually
rocks
the folds
of the thrust sheets in the Leonides.
because
elucidated,
overturned
Pena.
The
cannot
be
Second generation
In
the
developed with
cleavage,
vage.
First
structures.
Middle and
The
and
Lower Devonian isoclinal
an
which
axial
plane, fracture
deforms the
first
or
folds have
crenulation
generation slaty clea-
attitude of the axial planes is rather flat
second
generation folds
are
often
lying.
difficult
to
107
separate in the field. Near Besande NE-SW
folding
cross
In the
caused
E-W
axial
trends and
large
30°-40° N.
dipping
folds deform the low-angle thrust planes
and other first
minor folds
directed
E-W
both have
occur;
developed
group,
minor folds
as
the
on
the
cutting
recumbent
Yuso
the
minor
bedding
folds.
This
corresponds
group
the
fold has also
cross
than the third generation
structures.
folds
generation
A
is
but
implied,
older
appears
similar
as
the
not
be
age
could
and
of Ruesga
zone
shales
fault
thrust
great
fault
with
subgray-
radiolarian rock...
great, almost isoclinal folds form the
2.
these
folds
can
one
struc-
principal
3.
this
to
structural
4.
overturned towards
are
Orocada
and towards
the
the
SW
SE
in
Pena
in
Picos
de
Cruces and Almonga,
in direction of the axial
change
round
complications
rise
plane gives
Pena
Celada
km
[4
of Pena Redonda],
it
is
that
probable
nected
with
the
this
of
change
compressed
direction is
in the
structure
con-
Devonian
between Ventanilla and San Martin,
5.
the thrust fault bordering the
the
southeast of Pena
west,
continues in
proved.
the
following:
Las
the
and
the
and
limestones
griotte
tight
deformation in
between
ture,
east
N-S
a
beds,
of the
of the Valsurvio dome, between the Otero
core
wacke
Redonda and
deformation of
second
found, the Valsurvio syncline, which
second
dip
unit
besides
contains,
seen
can
group.
and the Hornalejo anticlines,
been
hinges
first
the
to
the Devonian and Ruesga
the
on
structural
[Southern Boundary Fault]
be
Sometimes, the slaty cleavage
through
This
1.
Yu-
limbs of large
contemporaneous formed isoclinal E-W folds, which
about 35° N.
(alpine?) from
by compression
Structure of the Caliza de Montana Series.
detect the
also been found in
The N-S fold direction has
In
a
attitude of their axial planes.
same
so
with
These
Contemporaneous with this
structures.
generation
refolding, N-S
folds
asymmetrical
planes
caused
the second
Martin-Camporredondo
of San
zone
deformation has
turned anticline,
east-southeast...
has been found deforming the first generation folds.
Carrion basin bends
Redonda but
to
another fault
northwesterly direction along the projected
a
extension of the thrust."
Third
generation
The present
been
structures.
day geometry of the Valsurvio
formed by
the
third
Hornalejo anticlines
with
vertical
nearly
plunging
First and
med
this
by
late
be
can
E-W
zone
third
E-W
open
and
planes
The
unconformable
structures,
also
considerably
respectively
have
structures
These
refolding.
into
traced
Besande anticline,
syncline,
scale
axial
second generation
structures
In the
broad
the
Cueto
Cea
been deforbroad
basin
have
structures
concentric minor
A
sures.
micro
or
occurs.
widely spaced micro knick
conjugate sets, resulting
lineations
at an
with
folding
folds often
been
in
angle of 0-30°
sets
of
set
upon accidented
deposition
strata
such
V:
laid
were
than
Sheet)
be
can
of these
direct
a
control
rueda Basin, Esla Sheet).
too
In
look for such
the
del Brezo
Further
the last
east
structural
zo.
p.
423) summarized the
"Broadly outlined,
has
one
between Ventanilla and
San
great overturned anticlinal
the
Devonian,
axial
Ventanilla and
dicularly
of
San
the
to
the
general the structural
one,
near
having
a
causing
and is
the
is
axis.
at
covered
folded
folded
This
Devonian
least by
axial
are
a
folds in the axial
Here
lies
such
Southern
a
on
also
been
as
basins
emphasized by
developing
influenced
only by
not
have de-
going
probably
case.
every
the deposition of
having regard
the
to
structural
major
Boundary Flexure (Evers,
of smaller
subsequently
phy
it is
control of
and
em-
faulting,
the León Line, the Sabero-Gordón Line
features
and
the
structures
is indisputable
them
extent
his discussion
Morgovejo (Valder-
but
origin in
under-
van
south
of
den Bosch
structures
basement
1967).
The
Villablino has
structures
but also by the variations in lithology
The
(1969).
will
have
been
and topogra-
as
well
the
as
confining boundaries of the basins.
between
perpen-
has,
area
STRUCTURES OF THE ASTURIDES
deformations,
two
plane...
Ventanilla is also complicated.
portant features
as
by them...
fold
again,...
northeastern direction and
the
Devonian
Sheet]
south,
major Devonian
therefore, been influenced
one
the
cover
correlation between
fault control
as:
This isoclinal fold in
towards
Martin
older
consider
fold...
overturned
plane
to
structures
Martin [Carrion
Lower Carboniferous rocks
The
the Leonides (the
is found in the Sierra del Bre-
first mapped incidentally)
Kanis (1956,
in
unit
an
In
the
greater
Helmig (1965)
That such
true,
a
'basement'
near
many
Structures
dip.
to
structures
as
uncon-
that
of Valdoré, Encl.
dip.
through
of
to
the
near
original
explained by original
and he cites examples such
far
an
style and
a
veloped is almost certainly
contemporaneous
terrain
is
examples
many
disharmonie with
clearly
are
interpretation
and
are
those of Pena Rionda (4 km E
as
Esla
the unconformable
Sierra
with
down
the Leonides
also make it likely
seen
also frequently form
each other."
to
deformed. There
formity, and the facies
phasizes
expo-
Crenulation cleavage
zones
two
de-
found,
conjugate
a
of
in
structures
of the thrust-fold complex
cover
lying older Palaeozoic in
syncline).
scribed in detail from the griotte and the 'Miranda'
parasitic
open
(Tejerina
of San Martin-Camporredondo only small
generation
Post-Stephanian Hercynian
and
Otero
and E, form together the Valsurvio dome.
W
to
both
has
dome
deformation. The
second,
The
the
later
structure
most
plane of the
im-
over-
North of the León Line
much
only
more
is
the
structural
heterogeneous than
style
of
development
in
the
deformation extremely
might be expected in view of
the
has
been
Leonides.
Not
variable,
lateral changes
in
as
the
108
stratigraphic
tions
the
variable. A
more
is underlain by
area
noted, but
already
sequence,
also much
are
with
paraconformable
often
deposits
phanian
structurally
distinction
older
relatively
are
and
here.
often
This
Kanis (1956) and Koopmans (1962)
by
are
Younger Ste-
various folding phases
between
which
age,
rocks.
rare
situations
complex
orienta-
is
in
occur
that
means
conceived
as
style
related
-
of the
major structural developments
described under five
the stratigraphic
to
main types
may
again
once
-
involved:
sequence
thrust and
folded together
Ponga Nappes (San
-
Thick, Upper Carboniferous Carbonates detached and
thrust
mutually
-
Picos de Europa Nappes,
-
Palaeozoic
Lower
Thin,
folded and thrust
independently
Palaeozoic
Lower
Thin,
San
Monto, Carrion,
-
with
together
chada,
The
-
the
Pisuerga,
Curavacas,
little
folded with
sion into
the
Yuso
this structural
Sheet (Encl.
nappes
sequence
Barrios
-
axial
rest
for
the
the base
the
as
in
the
sequence
differs
in
the
probable
show
east
direction
to
most
Zalambral
and
8),
Sjerp
too.
At
displace-
apparent
an
be traced further into the
that
postdate
they
frequently
of real
cut
to
been
mation
in
near
so
Puebla de
are
part
of
the
flysch
of
the
the
the
succes-
been
movement.
faults
maps
those
probable
basement high.
The
Tarna
further
thinner than anywhere
and, except
is
very
near
found in
much
of-
are
Lancara For-
Palaeozoic sequence of the
east
of
axes
thrust
closely
considered
and Pena de
folded
klippen
and
of
that
older
la Cruz,
else
Valdehuesca (Torio-Curueno Sheet),
the
due
the
to
evident.
N-S
to
them
rocks
but
section
with
has
off
cut
the Picos
the
and
Marcos
the
to
north-
of
typical
the
NE
curve
broad,
a
de Sajambre.
repetition
axes
of the
made
northwest in
to
the
so.
obvious
de Europa thrusts
the Upper Carboniferous
on
mapped
Many of the faults
the
to
do
to
NW of Oceja
only
Neoncito
finally
less
round
zone
involve
been
Julivert
although
Sheet).
even
imbricate
steep,
of
and
Some
different
have been
has
analysis
become
Yuso
south.
the
interaction of
traces
many
sequence
almost horizontal and the
are
No
nappes
also
are
Near Pena del Alba
axial
mapped
VI:
northwards
Picos
The
important
Most
Carboniferous
lower
Palaeozoic
faults
associated
by
partially concealed by
there.
unconformity
is
olistoliths of the
de Europa lie
segments
can
mainly
be
north of
carbonate
ly
of
sequence
our
maps
but
in the northern parts of
seen
the Yuso and Nansa-Deva Sheets.
the
The almost exclusiveCarboniferous
Upper
here has enabled the development of thick thrust sheets,
sequence
the
are
E-W.
large
(Encl.
which
Lillo resemble
a
The
east
and
on
there
together with
developed within the
parautochthonous
Isidro,
patterns
but the lack
of
San
but
rocks,
(1973) have shown that it is possible
makes them
repetitions
the
and folded
Picos de Europa
of
The
in
far from
bedding
the
Palaeozoic
these axial planes
fold
Carboniferous
thrust
during
seem to have
steep.
traces
and it is
only
flysch
hiatus
an
component of
of the
associated with
normal, and
refolded about E-W
that the
Multiple
the Pardomino Ridge,
too
sequence
1967).
would
usually
much
of
repetition
upwards through
follow
uncertain.
The
usually
(Sjerp,
the
largest
plunges,
variation
difficult
1965).
Ordovician
Carboniferous
the
west, which
of the
is
been
has
directions
de
not
the Univer-
eroded
part.
existence
clearly
The thrust sheets have
variable
exten-
part of
1962; Julivert,
the
on
much of the Upper Namurian
sion from
major
truncated older Palaeo-
a
detachment horizon,
maps
small
a
The
of the Lancara Formation which again
higher
The
our maps,
the uppermost Devonian and lowermost
deposits
Formation
to
X: 8).
Alvarez,
typified by
are
Carboniferous
only
be read
can
the
X:
(Encl.
not
limestone-bearing
sheets
interference patterns
unit has been investigated by
of Oviedo (Martinez
they
km
of
the
is
Cardano
Since these faults offset the already
sheets
especially
covered by
only partly
are
notably the San Isidro-Porma Sheet with
ten
axis
Isi-
Bar-
of the
component of throw
could
flysch.
thrust
older
but
The Ponga Nappes
very
km
there is
-
E-W trend.
NW-SE
the
E-W fault with
Valdeón, Le-
Ponga Nappes
the
Valdosin
because of
70°
important
most
the
the
evident in the San
with
of
small disharmonie folds
Rio
acts
3
some
an
offset of about 5
vertical
a
Lois-Ciguera,
-
Liébana,
Marana (see Structural Sketchmap, Encl. X).
down
the
almost
an
folded
thrust
evidence of involvement of older rocks
zoic
from
of
Cardano,
flysch
Upper Carboniferous flysch
Thick,
These
dextral
map
the offsets
to
the
coinciding
The
in
axes,
to
some-
Aguila.
folds
up
-
are
due
Probably
displacement
Carboniferous
(Palentian facies) folded and
Carboniferous
Liébana,
sity
A
the
Cofinal
visible
clearly
Formation.
syncline
plunges
than 20° variation from
Ventanilla Fault
from
of those
large wrench faults
Several
Pena del
trend of the
true
of steep
usually tight,
are
near
deformation.
thrust
-
less
probably
as
planes
indicate the
not
rios
the south
axial
the prevalence
ment
(Palentian facies)
sequence
Julian,
-
does
the
emplacement
Westphalian (Sjerp, 1967).
of the thrust sheets
to
the
latter demonstrate
in the Lower
(1967) deduces
Isidro-Porma Sheet),
-
of
outcrop
Line here.
Upper Carboniferous flysch and lowermost Palaeozoic
strata
The folds
dro Sheet,
be roughly
The
area.
nappes
times inclined
im-
practically
possible.
The
Marana
of the
of Upper Carboniferous,
rocks
particular Westphalian (or Moscovian)
in
the
large part of
very
A,
have
the
B, C,
another,
has
been
D).
thrust
basin
flysch
southwards
These
sheets
usually dipping
often accentuated
are
of the
ment
of
mirror
dips
has
cascade
image of
the
stacked
up
Here the
northerly
a
refolding
of
the
one
refolding
along
the
general
steepen-
the
develop-
accompanied by
with
another
Sections
against
dips especially
many
been
folds
one
VIIIA:
north, and extensive
southern margin of the Picos.
ing
over
of Liébana (Encl.
vergence
Leonide
-
the
Nappes
(Encl. VIIIA; Maas, 1974).
The
general
trend
of
the
thrust
sheets
is
E-W
al-
109
6.
Fig.
though the outcrop
and
by
of the Lebanza
Composite diagram
the ENE
to
which probably also
along them
ment
on
(after Ambrose,
the
Yuso
the Nansa-Deva Sheet. They
on
number of WNW
a
NW
to
curves
Thrust
trending sinistral
have
cut
wrench faults
component of vertical
a
Sheet
are
move-
1972).
Silurian/Devonian,
Encl.
VIA,
example,
The
inliers of
The
the
Liébana,
Silurian
The
Carrion
described by
The
most
to
Unit
extensive
most
is
striking
faults
are
folds due
thrust
ror,
on
fault
no
the
the
with
only
and
areally
the
Carrion
smallest
having
scale
we
which
have
on
The
developed
of
E-W just
barbed decoration
never
can
present.
disharmony
striking
the field is
be
the
been
These
shown
fully
important
out
of faulted
the
zo
and
As
the
Carrion and
be
can
er-
Pisuerga
are
-
through Tangua, Pena Cara-
evident
from the
outcrop
of
the
in
cut
seen
at
the
eastern
Thrust originates
have
6
and
for
as,
in variations
the
out
of
core
the
by
the
either
are
Bi-
tightly
southward
Axial
tightly
some
lated foliation
The
is
some
has
not
Monto inlier,
together
been
been
with
briefly
van
quite thin,
have
This
at
the
style
the
base
of
of
detach-
rest
of the
(Encl. VIIIA).
identified in
only
shales
(Fig. 6).
folds.
compressed
quite penetrative although
rocks
end of its outcrop,
the
plane cleavage has been formed in shales in the
of
cores
be
in
has been used in the construction of the
(1962) and
anticlines
Polentinos
plunges
steeper
Synclines
completely
Robledo Formation
ment
largest
of Lebanza has, in
the
are
rocks
and Curueno
or
cross-sections
Sheets).
Three major
local
(Fig.
thrusting.
of
most
folding (N.B.
N
compressed
the extensive
small apparent throw.
and
Devonian
Upper
Lebanza
stratigraphically
structural entities,
feature in
mapping
thrusts
to
and
Veen (1965) and Ambrose (1974).
faulting, much of very
especially
Cardano
Upper Carboniferous rocks.
of these
van
troublesome in
Monto,
Devonian
and
segments of Lower
while
These
south
Arras and Polentinos, result
near
struey, Cortes
developed in the Palentian facies of
structures
VIIA)
verging
of the outcrop pattern.
too.
Monto, San Julian and Carrión
comprise
Formation.
Arroyacas
typically overthrust flanks all
It
is
crenulation cleavage
places.
The
nature
of
usually
can
the
also
crenu-
yet been established.
comprising
some
only
Lower
described
up
to
Upper
now
by
Adrichem Boogaert (1967). The
and the north-dipping pile
subsequently
folded,
Devonian
Carboniferous,
has
Kallmann
sequence
of thrust sheets
resulting
in
structures
110
intricate
too
to
present
on
000
1:50
a
The
scale.
rela-
tionship with the surrounding Upper Carboniferous sediis
ments
unclear
in
Olistostromes
Palentian
latter
Devonian
late
for
roots
in
these
succession
is
thrust
found
not
rocks
have
must
Since
parautochthonous.
overrides
been rooted
Liébana structures,
neighbouring
the
conclude
we
1962). Hence these
have
that
the
be regarded
to
of the
of
as
Picos
Puerto
Valdeón Forma-
as
former
like
and,
sequences
(mapped
the
the
(Gomez,
north
locally
olistostrome-bearing
The
in
nor
are
struc-
younger
that
inlier
Palentian
of
facies
boniferous
flysch.
shows
interpretations
two
The
rocks
Carboniferous flysch
(many
time
in
the
tight
metry of the
inclined
the
to
structures
that their genesis
an
To
fold
south
Some
of the
Unit
Carrion
the
of Devonian
shown
matches
the
on
at
series
asym-
and implies
It
The Liébana and
This is
flysch.
more
trends
the
to
ty of the
type
of the southernmost Car-
west
localities of
the
Upper and Middle Devonian.
of the
sence
The
area.
intense
sequence
tached in the
faulting
is
if
not
with
the
unconformity
Formation is
ravacas
with the relation
the erosion is
a
cut
off.
very
C
m
The
can
Liébana
-
is
show.
very
5
very
interpretive.
-
more
(1974, Encl. IV) is
even
the
those
of Monto,
disturbed
olistostromes.
Carrion
(1971a), and owing
the
flank
of the
attitude is
the
basin
nated
by
surface
that
the
The
but
it
than
our
structures
see
we
ments
due
to
of Maas
map
poor
in
map
Maas
exposure
Devonian of the
clear
had
possibly
just
in
how
the
Pa-
similar
much
to
has
surrounding
X: 8).
regional pattern of
a
de
Sitter
ly that
almost equidimensional unit,
the
to
is
or
of
the
cuts
a
itself.
how
the
in
trace
the
from
separate
flank
may
is
termi-
well be the
Although the fault
sedi-
youngest
very
of
synsedimentary
Boschma,
there
are
a
that
these
maps.
the
se-
extensive
It
divided into
is
As
8).
scale
the
the
North
whole
seen
the
south.
a
sporadic
too
great
as
a
In
general
a
later
subvertical
system of folds with
is
planes. Cleavage
in
cross-sections
interpreted
folding and overturning preceded
a
our
Liébana Ridge
the
from the
unit is
in
area
Liébana/Polaciones
Subunits by
be
can
phase of refolding by
use
sequence between
(1974) and Boschma (1968)
overturned towards
synclinorium
It
accommodation folds
are
Carboniferous flysch
Liébana
Southern
tight
to
open
features.
most
be of
number of
from the confinement of the
bounding
The Liébana Unit of Maas
the
in
1966; Wagner &
dipping axial planes trending NNW.
likely
most
two
depth since there
at
movements
1971).
resulting
to
show
west
of faults.
zone
nearby (de Sitter &
seems
axial
Graaff
cross-sec-
overturned. This
control
The
fundamental feature exists
folds with steeply
and
The
SE, through Barruelo which
structures
Within the basin
is
de
van
IXA)
strongly
structural
a
by
simplicity.
to
N-S-fault, whose sinuous
evidence
the
an
of the Pisuerga Basin (early Stephanian) it is like-
in its development
but the fold sequence
regional analysis
is reasonably clear (Rupke, 1977).
In North Liébana/Polaciones
strata
1:50 000
scale
structures
not
where
inescapable.
1:25 000
resedimented
contrast
structures
mid-Liébana ridge
thin Upper
is
these
seems
generalized and
and
a
the large
in strong
as
divergent
very
suggested by
as
Sheet (Encl.
some
expression
VIIIA),
Pena Prieta,
establish
nothing
development
(Encl.
Cu-
Ponga
Lechada/Curavacas Syn-
emphasized
as
continued
imply
to
seems
For-
Westphalian
of the
area
have
we
the
to
dips steeply
X:
cut
east
sequence
the Pisuerga
to
(Encl.
). Thrust faults may
near
complex
lentian facies is repeated in
been
the
evident and typical Carrion
inlier
In fact
IV
gentle here,
km N
conclusion
much
-C
the base
long history of development
(1974)
fixed
a
generally de-
lower limbs of the folds.
at
some
The
and
varied
are
integral part of those structures,
contrast
structural
primarily
majori-
from the ab-
which affects
folded
van
for the
Middle Devonian Gustalapiedra
shaly
all of
the
provide
Palentian facies
This follows
tightly
mation (End. VIA: Section
The
which is in
These have also been described by
structures.
Veen (1965), and the sequences here
are
e.g.
the
of the
flysch
Leonides
(1957).
those
Carboniferous
less
or
clearest in the Cardano Unit,
continuation
a
differ from
structures
final emplacement of
in
west,
proved possible
not
Varker,
Cardano
above by the involvement of
some
above.
trends,
has
is
probably comparable.
was
Europa
concluded
clines with the folds of the Pisuerga Basin (Encl.
eastern
Liébana and Cardaño
fact
the
described
quence
rion
To
Nappes they form
tions
not
de
again
in the Upper Carboniferous
extreme.
IXA)
sedimentation of the latter. The
as
folds
Car-
being eroded
was
is
Cantabrian Mountains north of the
relief
isolated blocks
it
the
predate
structures
structures
The
(Encl.
faulting.
by
the map) imply that the older series
same
the
explaining
and
Upper Carboniferous flysch
positive
E-F
cross-section
of
occurrence
the
in
within
suggest the second alternative but
certainly
widespread
rocks
and
isolated
apparently
an
Devonian
erosion
pre-Carboniferous
contacts
of
these
Picos
the
against
Mogrovejo,
The Pisuerga Basin is
Julian inlier also forms
The San
the
terminates
north of
the Picos Nappes.
tures.
by
inlier
the
present.
Nappes
of
obvious
no
the frontal thrust
de Remona and Fuente Dé
tion),
at
further
occur
of
uplift
are
exposed
1974; Martinez Alvarez,
1974; Maas,
structures
There
in the Picos
olistoliths
the
confirming
sheets
unconformity.
an
bear
sequence
rocks
where older
inliers
latter
Westphalian.
the
of
suggestive
but
the
The
Thrust
are
younger
(Encl.
Westphalian
VIIIA:
Sheet).
An
within the
possible
(Maas,
overturned,
to
B
and
in
distinguish
C;
sequence
folding
which
may
be
influence of the advancing
normal
Viorno
the
has
but
phases
been
has
it
on
interpreted
nappes
in
the
Syncline
also Nansa-Deva
see
unconformity
Westphalian
of the
large proportion
1974). The deformation would
southwards
pa.
a
becoming
rocks
Sections
angular
only
the
seem
as
recorded
not
proved
basis
to
of it
decrease
implying the
of the Picos de
Euro-
111
The
Liébana
Southern
folds
upright
mostly
and
tight
and
Westphalian
of
Namurian
the
massive
and
The Lechada
the
of the
due
are
sequences
by
to
inclined
slightly
Synclines
the
Southern Liébana
the
Curavacas
detailed analysis
conclusion
that
is
either
the
has
This
to
the
to
ac-
in
underlying
the
axis
of the
of
the
cleavage is
also
witness
on
the
(Encl.
Syncline
two
The
faulted
this
had
fault
does
it
Devonian
to
is
strata
cut
whole
the
also
near
the
out
El
Cura-
probably including
movement
gently westwards, but would
and
plunges
structures
pinching
die
to
seem
of
out
more
or
due
out
the
the
to
less
the
Curavacas
Conglomerates in that direction.
The
Lois-Ciguera Unit
of Riano,
west
on
folds
tight
revealed
the
by
there. The fold trends and
simple
no
tions
as
limestone
to
the south
and
Cea
Cea
structures
tural style
as
have
well
as
tion outcrop make it
probably
at
such
also
bodies,
and Pico
terminate
the
that
at
no
of
depth than
can
as
of Upper
the Valdeón, the
are
posures
analysis
areas
Zone
are
-
determine
generally
while the
another unknown
upper
Carboniferous flysch
Esla Valley and the Ria-
relatively poorly
inadequate
understood.
allow
to
sedimentology of the
factor.
There
is
uncommon.
flank
are
Structures
also
known
with
here
opposing
e.g.
Ex-
thorough
deposits forms
evidence of synsedi-
mentary deformation, and inverted limbs
to
folds
vergence
near
agrees
dipping
but
the folds
to
with the pattern of
the larger faults in the Palaeozoic rocks."
Along
rise
of
most
Mesozoic
and
this
interpreted
(1962)
the
of
with
of
rejuvenation
steeply plunging fold
The
uplift'
p.
giving
been
types of Berg
structures
68).
Villanueva
de
la
Pena
(End. VII: Carrion Sheet) affects all except higher
cene strata
(Alpine)
and has been interpreted
dextral
plies
that
tonic
strata
the
suggesting
a
The
209).
p.
Cotolorno
steep axial
before
dipped steeply
complex,
extended
Mio-
implying Tertiary
the
along
movement
1962,
as
the
over-
have
older
1965,
near
are
core,
structures
143-144; Rupke,
pp.
or
the Palaeozoic
these
'mountain fold-thrust
together
1967,
with
Most
Flexure
Boundary
dip steeply
strata
contact
term.
as
Southern
Tertiary
near the
to
Fault
plunge imthe faulting,
period of
Alpine
tec-
events.
CONCLUSIONS
The
struc-
is present here
we
subsidiary
not
are
syn-
open
gently
generally
be
426)
p.
the
compa-
The change in
faulting
with
to
cover
(1974,
un-
León
within the Cea Forma-
sequence
likely
faults
Maas
Yordas
character
different and
very
Permo-Mesozoic
Sheet,
general pattern which
a
core
abruptly
Formation along the
the
the
flanks...
follow
anticlines
the
move-
the
characterized by faulted
.. .[they are]
and
Southern Cantabrian Mountains afford
wide
folded
to
are
on
Horcadas
not
through
nappes
types,
a
view
of
ranging from classic
multiple cleavage
a
re-
developments
drape folding and slump and slide deformation. These
features
partly,
De
of structural
range
chains
remaining
no-Cervera
clines
the
in
Nansa-Deva
(Koopmans,
the surface.
The
"
writes
and
attention. The opi-
proof.
varia-
Sheet, where the
into massive
been found.
complex
more
Yuso
outcrop
Westphalian succession is
rable
variable, and
where they disappear beneath
west
the
the
folds
Stephanian
Beyond
very
many
Stratigraphic
in Penas Pintas
The
limestone
important controlling factor
on
eastwards
grade
folded.
are
possible.
most
seen
equivalents,
conformable
Line.
be
bands
the lateral
little
can
plunges
seems
probably the
are
because,
are
analysis
of
layers
the
orogenic
margins of
the
to
real
any
structures
in
more
to
are
been
has
later
is that the influence of later
restricted
been
the lack of
the
Of
the
Esla and Yuso Sheets, is distinguished by the pattern of
mapping
of
some
rocks
accumulated incidentally,
only
workers
most
(Evers,
the
to
has
has
ments
turned
of
set
interfingering
nion of
certain that this fault has also
seems
of
and
Syncline
times of folding.
The
de-
impossible
younger
evidence
such
core,
perhaps deserves much
subject
despite
Unit. The apparent throw of
cuts
Hercynian
seen
echelon,
en
Curavacas
match that required
not
long history
a
the
where
Formation. It
vacas
faulted
are
the Carrion
against
N-S
Tejo
structures
termination of
the
affected
probably
is, however,
present. Since the prime object of the
considerable
a
deformation has
of Cantabria. It
distinguish their effects except where
attitude
flatlying
to
much
not
movements
in
structure
Lechada
if
beds.
found
vergences
vertical component of the tectonic transport.
eastern
rocks.
Stephanian
veloped.
Post-Hercynian
led
VIA: cross-section Z-Z'). The generally
slaty
con-
distinctive
bending
opposing
the
higher structural levels
of the
but
drape folds,
movements
towards
being
structures,
1967).
are
illustrated by
flank
involves
essentially
are
Conglomerate,
(Savage,
these
commodate vertical
which
Z),
the
to
cleavage development enabling
extensive
an
Section
POST-HERCYNIAN STRUCTURES
Curavacas
to
having
VIA:
Cleavage, though present, is poorly and sporadically
limestone
conglomerate and
trolled by
similar
This
characterized
in the former.
layers
in
is
differences between the folding styles
south. The
inclusion
Subunit
the
seems
Sitter's
of the
the
purpose
in
of
comments,
Hercynian
a
other
mountain
illustrated,
if only
fundamental difference.
that
we
orogene
only
(see
p.
see
a
77),
chance
are
even
today in view of the growing evidence
fragmentary
It
in
many
symmetry
symptomatic
significant
the world.
to
centripetal
1962
fragment of
more
comparable
are
but
must
issuing
nature
be
these
has
of such
orogenes
elsewhere in
concluded that de Sitter's
maps
to
original
discussion
only been realized in his
either
and further work
(Encl.
time but looks like bearing fruit for
not
stimulate
some
time
own
to come.
112
REFERENCES
Adrichem
H.
Boogaert,
Carboniferous
their
and
(Spain)
Med., 39,
Ambrose,
1967.
van,
of
the
stratigraphic
Devonian
1972.
Carboniferous
The
H.
The
and
stratigraphy
north-west
rocks
J.
assemblage
spores
vince
of
tains
León
of
of the
structure
Cervera
Ph.D.
de
Univ.
thesis,
47/1,
Pre-
Pisuerga,
Palaeozoic
van,
1965.
from
the
(Northern
rocks
of
northern
fan
Cretaceous
Upper
so-called
'Wealden'
Pollen
Spain).
of the
Spores,
et
and
pollen
pro-
7,
1959.
H.,
Nord-León
Die
(eine
Grenzschichten
R.
Furada-Zone
in
Zentral-Asturien
feinstratigraphische
Geol.
Wyoming
flank
and
in
thrusting
Colorado.
Bull.
A.A.P.G.,
J.
Spain).
1965.
G.,
Leidse
W.
J.
Lower
North
Geol.
1969.
Mountains
Devonian
Palencia
Med., 33,
den,
van
Cantabrian
46/11,
(NW
Mountains
of
the
Higgins,
Mountains,
Luna-Sil
Leidse
Spain).
geological
Leidse
(Spain).
Geol.
region,
&
Geol.
in
1964.
8/1-4,
of the
map
Geol.
Southern
Med., 43,
pp.
units
Mappable
Cantabrian
of
the Car-
Mountains.
Le
du
(Espagne
inférieur
Ie
Dévonien
Breviora
des
des
Montag-
Geol.
Astürica,
Montagnes cantabriques
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the
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Sheffield
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and
C.R.
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Chonetidina
43,
Part
near
Wagner-Gentis,
from
&
distribution
Palencia, Spain.
Spain.
Stratotype
Congr.
Winkler
1974.
and
Vie
I,
in
The
(upper Westphalian D, Cantabrian,
Oviedo, 4,
Cantabrian
An
Northwest
—,
1955.
145-202.
pp.
—,
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strata
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ous
Wagner,
V.
post-Leonian
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palaeogeology.
pp.
goniatites
Mountain
5-42.
Productidina
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Leidse
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