Downloaded from http://sp.lyellcollection.org/ at Pennsylvania State University on February 20, 2016
A late Atokan regional encrinite (early late Moscovian, Middle
Pennsylvanian) in the Sierra Agua Verde, Sonora state, NW Mexico
B. E. B U I T R O N - S , / ~ N C H E Z l, C. G O M E Z - E S P I N O S A 1, E. A L M A Z A N - V J k Z Q U E Z 2 &
D. V A C H A R D 3
' Universidad Nacional Aut6noma de MOxico, Instituto de Geologia, Departamento de
Paleontologia, Ciudad Universitaria, Delegaci6n Coyoacdn, 14510 MOxico, D. F., Mexico
(e-mail: blancab@servidor, unam. mx)
2Universidad de Sonora, Departamento de Geologia, Boulevard Luis Encinas y Rosales
83000 Hermosillo, Sonora, Mexico
3UniversitO de Lille 1, Sciences de la Terre, UMR 8014 du CNRS, Laboratoire LP3,
Bdtiment SN5, 59655 Villeneuve d'Ascq COdex, France
(e-mail: daniel, [email protected])
Abstract: In the Sierra Agua Verde, central Sonora state, NW Mexico, the La Joya Formation exhibits an alternation (100 m thick) of calcareous siltstone and fossiliferous limestone
with nodular cherts. This latter contains an abundant and diverse late Atokan (i.e. Podolskian
=early late Moscovian, Middle Pennsylvanian) fossil assemblage composed of phylloid
algae, fusulinids, chaetetids, tabulate corals, gastropods, fenestellid bryozoans, spiriferid
and productid brachiopods, crinoids and conodonts. The crinoidal beds constitute a good
example of a regional encrinite. They include several species of the parataxonomic stem
form-genera Cyclocaudex, Cyclocrista, Heterosteleschus, Mooreanteris, Pentagonopterix,
Preptopremnum, Cycloscapus and Pentaridica. Their preservation indicates the combination
of preburial decay on the sea floor and post-burial decay within the sediment. The high degree
of silicification of the crinoids indicates that they were possibly associated with siliceous
organisms (Porifera?), not preserved in the assemblages. The studied thanatocoenosis is typical of tropical shallow seas, and reveals strong biogeographical affinities with the assemblages
of the midcontinental and southern regions of the USA. Particularly, the Atokan crinoids
of central Sonora are similar to those from Kansas and Texas, confirming the close palaeogeographic connection of southern USA and northern Mexico during the Middle Pennsylvanian.
The Sierra Agua Verde is located 120 km eastward of Hermosillo City, Sonora state, in the
'Sierras and Valles del Norte' Mexican subprovince. This range covers a surface area of 255 km 2
and its centre is at 109~176
and
29~176
(Fig. 1). It is composed of
sedimentary, igneous and metamorphic rocks of
Palaeozoic, Mesozoic and Cenozoic age. Geology and palaeontology of the Sierra Agua Verde
were described by Poole et al. (1984), Stewart
et al. (1988, 1999), Minjarez-Sosa et al. (1993),
Ochoa-Granillo & Sosa-Leon (1993), Stewart &
Poole (2002), Mendoza-Madera et al. (2004) and
Buitr6n-Sfinchez et al. (2005a, b). The Palaeozoic
series includes the following formations: Puerto
Blanco, Cuarcita Proveedora, Buelna and
Arrojos (Cambrian); E1 Boquinete (Ordovician);
E1 Pollo (Devonian); Santiago (Mississippian);
La Joya (Pennsylvanian); and Tuntunud6
(Permian).
Material and methods
The La Joya Formation was logged and sampled
bed by bed. All the beds marked as 'crinoids' in
Figure 2 were studied, as well as those of other
Pennsylvanian outcrops from Sonora in order to
investigate several 'regional encrinites' in the
sense of Ausich (1997) and Ginsburg (2005). Our
study of sequence stratigraphy has determined
that the La Joya Formation appears as a
transgressive systems tract (TST), whose main
lithologies are Chaetetes reef mounds (Almaz/mV~zquen et al. 2007), fusulinellid floatstones,
phylloid algae framestones and crinoidal rudstones. These crinoidal rudstones are particularly
abundant and well known in the Mississippian
and Pennsylvanian of the USA, but only a very
few have been studied in Mexico. Our investigation is essentially based on the extraction of
the best-preserved specimens of crinoids for
~kLVARO,J. J., ARETZ,M., BOULVAIN,F., MUNNECKE,A., VACHARD,D. & VENNIN,E. (eds) 2007.
Palaeozoic Reefs and Bioaccumulations: Climaticand Evolutionary Controls. Geological Society, London, Special
From:
Publications, 275, 201-209.0305-8719/07l$15.00 9 The Geological Society of London.
Downloaded from http://sp.lyellcollection.org/ at Pennsylvania State University on February 20, 2016
202
B.E. BUITRON-S_ANCHEZ E T AL.
Fig. 1. Locations of (a) Sonora in Mexico and (b) Sierra Agua Verde in Sonora.
taxonomic purposes and a microfacies analysis
from a taphonomic point of view, i.e. the
taphofacies method of Speyer & Brett (1988) and
C6zar (2003). Quantitative analyses based on the
techniques summarized by Holterhoff (1996)
concerning the crinoid biofacies will be applied
to the material (G6mez-Espinosa's PhD 2007);
this preliminary study presents only the systematic and taphonomic data obtained in hand
specimens and thin sections.
Regional encrinites
Regional encrinites were defined as crinoidal
grainstones and packstones composed of more
than 50% by volume of pelmatozoan debris that
are at least 5-10 m thick and 500 km 2 in extension (Ausich 1997; Ginsburg 2005). They are an
example of taphonomic feedback (Kidwell &
Jablonski 1983) by the predominance of one
special skeletal grain type. Regional encrinites
Downloaded from http://sp.lyellcollection.org/ at Pennsylvania State University on February 20, 2016
ATOKAN REGIONAL ENCRINITE OF NW MEXICO
Metres ~ l t
/ ~ I J I Brachiopods
10o_.~[ ~_": =1= =. _=j_== Fusulinids
II , I , IjlCrinoids
I L ' .... , " ~Solitary corals
/ F---i--i-.==- t
8o.-ll I
.
~
,o-lL ',,'
I/
',
Synngopora
','J
| Jr- ['_~_T_--_:.~Fus~,in'ds
/
eO--i ~
/
~
2 - c ; -i - i C.noJ ,
l e,~ I IChaetetid reef
mound
!~-_-=--=~_
"_-_~-_-__~-= Solitary corals
so-I ,, I w l
~
i ".T-'i--iT l
l.,.. I
1
I
I
I Fusulinids
t l
'--'-~ --'~'l
40i ";U--'-----L4
' i ,~
3o-
~
I z /Crinoids
:---
Synngopora
,-i
Brachiopods
Solitary corals
Chaetetids
Syringopora
Brachiopods
203
occur from the Ordovician to the Jurassic, but
the acme of their development in North America
is in the early Mississippian (Osagean) (Ausich
1997; Ginsburg 2005). At this time and during
the Pennsylvanian individual regional encrinites
occur with other carbonate lithofacies in different formations of the USA and northern Mexico.
Three main factors related to the evolutionary
taphonomical and diagenetical history of
crinoids and their skeletal remains are important
for the formation of regional encrinites: (1) the
long geological history of crinoids is marked by
episodes of exceptional abundance, which produce encrinites (Ausich et al. 1999); (2) the stalks
and calyces of crinoids consist of separate plates
and segments held together with ligamental tissue in a labyrinthine cavity system, the stereome;
and (3) the post-mortem decay of this tissue
provides plates of the calyx and more numerous
segments of the stem, which are highly porous
(Ginsburg 2005).
These hydraulically light fragments can be
entrained, transported and redeposited by
currents and orbital wave velocities as low as
16 cm s-1 using the results from flume experiments with crinoid segments from living specimens (Ginsburg 2005). As a result of this ease
of movement, bottom sediments of abundant
crinoidal debris were probably frequently mobile
resulting in the common occurrence of current
bedding and graded bedding of encrinites
(Ausich 1997; Ginsburg 2005). Furthermore, as
highly porous crinoid ossicles are entrained at
lower current velocities than solid carbonate
particle of the same size (e.g. Fliigel 2004), accumulation rates in the encrinite are generally very
high (more than 50% or even 60% of the rock
volume), and the regional encrinites are generally
deposited below normal wave base but within
storm wave base (Fliige12004).
Fossil assemblage in Sierra Agua Verde
Crinoids
Fusulinids
~
Covered base
Limestonewith chert nodules
-~ Siltstone
Fig. 2. Lithological column of the La Joya Formation
in Sierra Agua Verde (Sonora, Mexico). The lower
contact is not exposed in the field. The upper contact
is tectonic (normal fault). Fifteen field samples were
collected in the three levels mentioned as 'Crinoids'.
Each one contains about 100 crinoids, taxonomically
studied.
The studied crinoid fauna has been sampled from
marine fossiliferous limestone of the La Joya
Formation (100 m thick), which is intercalated
with nodular cherts and calcareous siltstone
(Fig. 2). The associated biota includes: calcareous algae (Eugonophyllum sp., Zidella? sp.,
Kamaena? sp., Komia eganensis); problematic
foraminifers (Pachysphaerina pachysphaerica,
Eotuberitina reitlingerae, Insolentitheca horrida);
smaller foraminifers (Endothyra ex gr. bowmani,
Climacammina ex gr. moelleri, Globivalvulina
bulloides); fusulinids (Eostaffella grozdilovae
(=E. acuta of the authors), Millerella sp.,
Pseudostaffella sp., Staffella powwowensis,
Downloaded from http://sp.lyellcollection.org/ at Pennsylvania State University on February 20, 2016
204
B.E. BUITR6N-SANCHEZ ETAL.
Eoschubertella texana, Fusulinella thompsoni, F.
llanoensis, Nipperella? sp.); chaetetids; tabulate
corals (Michelinia sp.) and zaphrentid solitary
corals
(Lophophyllidium
sp.); gastropods
(Euomphalus sp., cf. Donaldina robusta); brachiopods (Spirifer sp.); and conodonts. These fossils
indicate an Atokan age (=Podolskian=early
late Moscovian = Middle Pennsylvanian).
The crinoid fauna (Fig. 3) includes 11 parataxonomic stem species: Cyclocaudex insaturatus
Moore & Jeffords, Cyclocrista martini Miller,
Heterosteleschus keithi Miller, Lamprosterigma
erathense Moore & Jeffords, Lamprosterigma
mirificum Moore & Jeffords, Mooreanteris
waylandensis Miller, Pentagonopterix insculptus
Moore & Jeffords, Preptopremnum laeve Moore
& Jeffords, Preptopremnum rugosum Moore &
Jeffords, Cycloscapus laevis Moore & Jeffords
and Pentaridica simplicis Moore & Jeffords.
This fauna appears similar to those described
in the USA by Moore & Jeffords (1968). The
thanatocoenosis is typical of tropical shallow
seas and shows a strong affinity with the characteristic species of the midcontinental and southern regions of the USA. In particular, the Sonora
Pennsylvanian crinoids show similarities to the
assemblages of Kansas and Texas (Buitr6nSfinchez et al. 2004, 2005a, b). All these regions
are located in tropical and subtropical latitudes
during the Pennsylvanian epoch (Heckel 2002).
They also have much in common with
Eurasiatic-Arctic faunas corresponding to the
same climatic zones during this epoch (see,
for example, the reconstructions of Scotese &
Langford 1995; Ross 1995; Vachard et al. 1997,
2000b, c).
Similarly, fusulinids, calcareous algae and
smaller foraminifers represented in the La Joya
Formation show affinities with Arizona, New
Mexico, Texas and California microfaunas. The
Permian fusulinids (P6rez-Ramos 1992) share
the same affinities. These new data confirm the
palaeogeographical reconstructions of Vachard
et al. (1997, 2000a-c) and Buitr6n-Sfinchez et al.
(2004) in Mexico and Guatemala.
Taphonomical implications
The taphonomical study of crinoids was not
initiated until the 1960s (Ausich et al. 1999).
Crinoids are rarely represented as complete
fossils, commonly they are disarticulated after
death and are preserved as crown parts, cups,
arm ossicles, fragments and stem fragments. A
few days after death the muscles and ligaments
decay, which leads to the disintegration of the
skeleton into isolated elements. In order to be
preserved completely, a crinoid must be deeply
and quickly buried to prevent the reexcavation
by currents or disruption by scavengers and
burrowers (Donovan 1991; Ausich et al. 1999).
In normal marine conditions the echinoderms
usually disarticulate into individual ossicles
within a period of 1-2 weeks, depending on their
construction and environmental factors, but
specifically the arms and cirri of recent crinoids
begin to disarticulate within the 3 first days after
their death, whereas calyx and certain segments
of the arms may be disarticulated after 6 days
(Dornbos & Bottjer 2001).
In crinoids the articulations between multicolumnal segments of the column consist only of
intercolumnal ligament, which are zones of structural weakness after death. This was demonstrated in experiments on recent isocrinids. A
similar ligamentary organization of the column
was observed in crinoids of the Early Mississippian. When a column begins to disarticulate
the articulation between segments breaks first,
producing fragments of column of almost equal
length. Finally, when all the through-going ligaments decay, the whole column disarticulates
into individual columnals (Baumiller & Ausich
1992; Ausich & Baumiller 1993). The effects of
physical disturbance on echinoderms were studied by Kidwell & Baumiller (1990). The results
obtained from laboratory experiments with living crinoids indicate that recently dead crinoids
remain articulated through hours of physical disturbance, whereas dead echinoids disarticulate
quickly after physical disturbance. In the La Joya
Formation the majority of crinoids are represented by fragments of columns and a very low
percentage by isolated plates (three specimens
in 10 representative samples, each containing
approximately 100 characteristic elements of
skeleton). Thus, it can be inferred that decay
allowed disarticulation of the arms and calyces,
and a breaking of the intercolumnar ligaments,
but not complete disarticulation of the columns,
are evidenced by columns fragments. The preservation of crinoids in La Joya Formation
probably shows a combination of decay of the
crinoids preburial on the sea floor and decay of
crinoids post-burial within the sediments.
The limestones rich in crinoids exhibit various
taphonomic processes and difference in the depositional environment. Coarse-grained crinoidal
limestones are occasionally interpreted as having
originated as a result of gravity flows (Cook &
Mullins 1983; Martin 1999; Fltigel 2004) but
more frequently as tempestites (e.g. Fliige12004).
This interpretation is confirmed by the Sierra
Agua Verde deposits, owing to the absence of
turbidite figures of turbidites and microfacies
Downloaded from http://sp.lyellcollection.org/ at Pennsylvania State University on February 20, 2016
ATOKAN REGIONAL ENCRINITE OF NW MEXICO
205
Fig. 3. Late Atokan crinoid fauna from Sierra Agua Verde (Sonora, Mexico). All scale bars are 0.700 mm.
(a) Cyclocaudex insaturatus Moore & Jeffords. (b) Cyclocrista martini Miller. (e) Heterosteleschus keithi Miller.
(d) Lamprosterigma mirificum Moore & Jeffords. (e) Lamprosterigma erathense Moore & Jeffords. (f) Cycloscapus
laevis Moore & Jeffords. (g) Preptopremnum laeve Moore & Jeffords. (h) Preptopremnum rugosum Moore &
Jeffords. (i) Mooreanteris waylandensis Miller. (j) Pentagonopterix insculptus Moore & Jeffords and Pentaridica
simplicis Moore & Jeffords. (k) Field picture of the crinoidal rudstones in the Sierra Agua Verde.
Downloaded from http://sp.lyellcollection.org/ at Pennsylvania State University on February 20, 2016
206
B.E. BUITR6N-SANCHEZ ETAL.
analyses that infer tempestites, and probably distal tempestites (according to the criteria summarized by Flfigel 2004, p. 596). The problem is to
understand how and when favourable weak
currents for suspension feeders like crinoids (see
detailed data in Holterhoff 1997) become strong
storm currents, i.e. the interaction of organisms
with moving fluids.
An average accumulation consists of 50%
columnal plates that are totally disarticulated,
5% Fusulinella and very rare smaller foraminifers, 5% fenestellid bryozoa (and rare other
remains of metazoans) and 40% syntaxial sparite
cement. Nevertheless, the associated fusulinellids
are poorly preserved, with many truncation
facets indicating their allochthonous origin
(e.g. Fernfindez-L6pez 2000). The cementation
of the distal tempestites with crinoids is very
rapid and took place very early, as the ossicles
are not affected by compaction or other threedimensional finite strain (compare with Rowan
1991). The character of distal tempestite is also
obvious in associated deposits, namely fusulinellid wackestone-packstone, because of the
homogeneous micritic matrix and the absence
of corrosion features on the fusulinellids, their
oligotipy and the absence of associated photophile green algae, all characteristics indicating
a rapid burial after transport and sorting.
Ginsburg (2005) has underlined that fusulinids
offer many opportunities for taphonomic feedbacks that are comparable to that of crinoidal
debris. Chaetetid reef mounds, which developed
in coeval beds, are located in the lower part of the
photic zone, just below wave base (Almaz~mVfi.zquez et al. 2007) - thus supporting the interpretation of the depositional environments of the
crinoidal beds. The absence of encrusting algae
or foraminifers (e.g. Claracrusta, Calcivertella)
on the fusulinellids corroborates the rapid burial
of the biota within the microfacies, whereas the
absence of ichnofossils in the outcrop indicates
an absence of conditions for the establishment of
an infrabenthic community. Consequently, in the
Atokan Sierra Agua Verde carbonate platform,
the crinoid biotopes have been very productive
in supplying carbonate fragments for the distal
tempestites, first by the ossicles and, secondly,
because the stalked crinoids probably acted as
substrates for the fusulinellids, another important component of the tempestites (Fig. 4). The
chaetetid reef mounds were located in a lower
part of the platform and trapped the sediments
transported by the storm currents, i.e. the fusulinellids floatstones and the crinoid rudstones.
Between the crinoid biotopes and these chaetetid
mounds, infaunal organisms were probably
inhabiting the micritic substrate (Fig. 4).
Fig. 4. Reconstruction of the biotopes of crinoids (1)
and fusulinellids (2), with their first accumulations
(1.1 and 2.1)and the final deposits (2.1.1 and 1.1.1)
accumulated around the chaetetid constructions (3) in
the Sierra Agua Verde (Sonora, Mexico). Not to scale.
The accumulation of crinoids may also correspond to colder water inputs, similar to those
reconstructed in the Permian deposits of Oman
(Weidlich 2007). Nevertheless, as indicated
above, these crinoids are interpreted as tropical,
and the possible mixing of cold and warm waters
warrants further discussion in various outcrops
and/or areas (see also the 'Auernig paradox' of
Samankassou 2002 in the Carnic Alps). Other
arguments for possible cold episodes are: (a) that
the skeletal composition of the benthic fauna
in these levels of the Sierra Agua Verde was principally calcium carbonate (Table 1), and poorly
aragonitic, with a dominance of the 'heterozoan
association' on the 'photozoan association' (e.g.
Samankassou 2002); and (b) the existence of
biogenic chert formation (see Beauchamp &
Baud 2002) during the Atokan of Sonora, where
most of microfossils are preserved by silicification and show internal diagenesis as molds with
ornamental features. The source of silica is
organic in origin because there is no evidence of
volcanism or evaporation zones in the studied
area, and because this type of silicification is
common in all the investigated encrinites,
although their provenances and deposit environments vary. The high degree of silicification
suggests the presence of siliceous organisms
(Porifera?); consequently, the apparently
crinoid-dominated accumulations might correspond to crinoid-sponge associations. The
physico-chemical conditions caused the dissolution of these skeletons of associated sponges, and
this dissolved silica penetrated and preserved the
dead organisms. In the microfacies the first
silicifications appear as small points within the
crinoid network. The lithostatic compression can
be inferred preferentially to the sedimentation,
and the silica could also have been mobilized
from the interbedded siltstone from burial
Downloaded from http://sp.lyellcollection.org/ at Pennsylvania State University on February 20, 2016
ATOKAN REGIONAL ENCRINITE OF NW MEXICO
207
Table 1. Original mineralogy composition of the benthicfauna present in Agua Verde range C, common; X, less
common (after Martin 1999)
Taxon
Gastropods
Brachiopods
Sponges
Bryozoans
Echinoderms
Benthic foraminifers
Aragonite
Calcite low Mg
Calcite high Mg
C
C
X
C
C
C
X
Aragonite + Calcite
Silica
C
C
C
X
diagenesis. Therefore, more geochemical investigations are necessary in order to elucidate the
fossil diagenesis of these crinoid accumulations.
Conclusions
9 The crinoid assemblage from the La Joya
Formation is diversified and composed of
11 stem-based species.
9 The crinoids are typical forms of Pennsylvanian age; more precisely, they are late Atokan
in age, as indicated by the associated
Fusulinella.
9 Chaetetids, corals, fusulinellids, calcareous
algae and brachiopods indicate tropical seas
with normal salinity. Therefore, these conditions can be assumed for the crinoids; nevertheless, their possible value as local proxies of
colder waters input is debatable.
9 The biotopes of each group are probably
located in different environments along a
carbonate platform and largely depending on
the current system.
9 Crinoids indicate the presence of a hard substrate where they colonized, and were probably in turn the substrate for many epifaunal
organisms, the fusulinellids for instance.
9 The crinoids of the La Joya Formation, represented by fragments of columns and a very
low percentage of isolated plates, indicate that
decay allowed disarticulation of the arms and
calyx and the breaking of the intercolumnar
ligaments, but not the through-going ligament of columnal plates. These crinoids show
a typical combination of a preburial decay on
the sea bottom and a post-burial decay within
the sediments.
9 Regional encrinites of the La Joya Formation
are the result of in situ accumulations rapidly
reworked by storm waves and resedimented
as distal tempestites.
9 These distal tempestites were finally accumulated near chaetetid bioconstructions developed in another part of the platform. Between
the crinoid biotopes and these constructions
some infaunal organisms probably inhabited
the micritic substrate.
The high degree of silicification of the crinoids
indicates that they were possibly associated
with siliceous organisms (Porifera?), not
preserved in the assemblages.
The thanatocoenoses suggest a strong affinity
with mid-continental and southern regions in
the USA, especially with Kansas and Texas.
The seaways of Sonora, southern USA and
the midcontinent were apparently well connected during the Atokan, as the ecological
conditions were remarkably similar.
The Evaluation-orientation de la Coop6ration
Scientifique, Asociaci6n Nacional de Instituciones
de Educaci6n Superior, Consejo Nacional de Ciencia
y Tecnologia, Universidad Nacional Autonoma de
Mexico project No. MOOU01 'Un estudio sedimentol6gico, micropalentol6gico y geoquimico del
Paleozoico de M6xico', and UNAM-PAPIIT project
No. IN104103-3 'Bioestratigrafia de rocas de plataforma del Pensilvfinico y P~rmico de Sonora, Mdxico',
financially supported this research. We are grateful
to L. Pille for her technical help. We thank the reviewers
T. Kammer, E. Gluchowski and M. Aretz for their
constructive remarks and corrections.
References
ALMAZAN-VAZQUEZ, E., BUITRON-SANCHEZ, B. E.,
VACHARD, D., MENDOZA-MADERA, C. ~ GOMEZESPINOSA, C. 2007. The late Atokan (Moscovian,
Pennsylvanian) chaetetid accumulations of Sierra
Agua Verde, Sonora (NW Mexico): composition,
facies and palaeoenvironmental signals. In: ALVARO,
J. J., ARETZ, M., BOULVAIN,F., MUNNECKE, A.,
VACHARD,D. & VENNIN, E. (eds) Palaeozoic Reefs
and Bioaccumulations: Climatic and Evolutionary
Controls. Geological Society, London, Special
Publications, 2"/5, 189-200.
AusIcH, W. I. 1997. Regional encrinites: a vanished
lithofacies. In: BRETT, C. E. & BAIRD,G. C. (eds)
Paleontological Events, Stratigraphic, Ecologicaland
Evolutionary Implications. Columbia University
Press, New York, 509-520.
Downloaded from http://sp.lyellcollection.org/ at Pennsylvania State University on February 20, 2016
208
B.E. BUITRON-SANCHEZ ET AL.
AUSICH, W. I. & BAUMILLER,T. K. 1993. Taphonomic
method for determining muscular articulations in
fossil crinoids. Palaios, 8, 477484.
AusIcH, W. I., BRETT, C. E. & HESS, H. 1999. Chapter 4
Taphonomy. In" HESS, H., AuSICH, W. I., BRETT, C.
E. & SIMMS, M. J. (eds) Fossil Crinoids. Cambridge
University Press, Cambridge.
BAUMILLER, T. K. & AUSICH, W. I. 1992. The brokenstick model as a null hypothesis for crinoid stalk
taphonomy and as a guide to the distribution
of connective tissue in fossils. Paleobiology, l l ,
105-119.
BEAUCHAMP, B. & BAUD, A. 2002. Growth and demise
of Permian biogenic chert along northwest Pangea:
evidence for end-Permian collapse of thermocline
circulation. Palaeogeography, Palaeoclimatology,
Palaeoecology, 184, 37-63.
BUITRON-SANCHEZ, B. E., ALMAZAN-VAZQUEZ,E. &
VACHARD, D. 2004. Benthic invertebrates, of
Carboniferous-Permian age, from Sonora: their
paleogeographic implications. In: 32nd International
Geological Congress, Florence Italy, Abstract, 202.
BUITRON-SANCHEZ, B. E., ALMAZA,N-VA,ZQUEZ, E. &
VACHARD, D. 2005a. Pennsylvanian crinoids close
to chaetetid 'reef, Sonora, northwestern Mexico.
In: Climatic and Evolutionary Controls on Paleozoic
Reefs and Bioaccumulations, Colloquium 7-9 Sept
2005, Museum national d'Histoire naturelle, Paris,
Abstracts, 16-18.
BUITRON-SANCHEZ, B. E., ALMAZ./~N-V/~ZQUEZ, E.,
VACHARD, D., GOMEZ-ESPINOSA, C. & MENDOZAMADERA, C. 2005b. Crinoides pensilvfinicos
asociados a facies 'arrecifales' de chaetetidos en
Sierra Agua Verde, Estado de Sonora, Mexico.
Geos, Uni6n Geofisica Mexicana, Boletin
Informativo, Epoca II, Reunidn annual 2005, 25, 1.
COOK, H. E. & MULLINS, H. T. 1983. Basin Margin
Environment. In: SCHOLLE, P. A., BE~OUT, D. G.
& MOORE, C. H. (eds) Carbonate Depositional
Environments. AAPG Memoir, 33, 539-617.
C0ZAR, P. 2003. Foraminiferal taphofacies in the
Mississippian rocks of the Guadiato area, SW
Spain. Facies, 49, 1-18.
DONOVAN, S. K. 1991. The Processes of Fossilization.
Columbia University Press, New York.
DORNBOS, S. Q. & BOTTJER, D. J. 2001. Taphonomy
and environmental distribution of helicoplacoid
echinoderms. Palaios, 16, 197-204.
FERNANDEZ-LOPEZ, S. R. 2000. Temas de Tafonomia.
Universidad Complutense de Madrid.
FLOGEL, E. 2004. Microfacies of Carbonate Rocks,
Analysis, Interpretation and Application. Springer,
Berlin.
GINSBURG, R. N. 2005. Disobedient sediments can
feedback on their transportation, deposition and
geomorphology. Sedimentary Geology, 175, 9-18.
GOMEZ-ESPINOSA, C. 2007. Palaeobiology and taphonomy of the biota of Sierra Agua Verde (late
Moscovian-late Atokan) Sonora, Mexico. Unpublished PhD thesis, Universidad de Sonora, Mexico.
HECKEL, P. H. 2002. Overview of Pennsylvanian
cyclothems in Midcontinent North America and
brief summary of those elsewhere in the world. In:
HILLS, L. V., HENDERSON,C. M. & BAMBER, E. W.
(eds) Carboniferous and Permian of the WorM.
Canadian Society of Petroleum Geologists,
Memoir, 19, 79-98.
HOLTERHOFF, P. F. 1996. Crinoid biofacies in Upper
Carboniferous cyclothems, mid-continent North
America; faunal tracking and the role of regional
processes in biofacies recurrence. Palaeogeography,
Palaeoclimatology, Palaeoecology, 127, 47-81.
HOLTERHOFF, P. F. 1997. Filtration models, guilds, and
biofacies: Crinoid paleoecology of the Stanton Formation (Upper Pennsylvanian), mid-continent,
North America. Palaeogeography, Palaeoclimatology, Palaeoecology, 130, 177-208.
KIDWELL, S. M. & BAUMILLER, T. K. 1990. Experimental disintegration of regular echinoids: roles
of temperature, oxygen, and decay thresholds.
Paleobiology, 16, 247-271.
KIDWELL, S. M. & JABLONSKI,D. 1983. Taphonomic
feedback: ecological consequences of shell accumulations. In: TEVESZ,M. J. S. & MCCALL, P. L. (eds)
Biotic Interactions in Recent and Fossil Benthic
Communities. Topics in Geobiology, 3, 195-248.
MARTIN, R. E. 1999. Taphonomy, a Process Approach.
Cambridge Paleobiology Series, 4. Cambridge
University Press, Cambridge.
MENDOZA-MADERA, C., ALMAZA.N-VA,
ZQUEZ, E.,
BUITRON-SANCHEZ, B. E. & VACHARD, D. 2004.
Bioestratigrafia de la secuencia del Pensilvfinico
en la Sierra Agua Verde, en la porci6n central del
Estado de Sonora. Universidad de Sonora, Divisi6n
de Ciencias Exactas y Naturales, Semana Cultural
XXIX, Resfimenes, 9.
MINJAREZ-SOSA, I., OCHOA, J. G. & SOSA, L. P. 1993.
Geologia de la Sierra Agua Verde, NE de Villa
Pesqueira (Matape). In: GONZALEZ-LE6N, C. &
VEGA-GRANILLO, E. L. (eds) Res•menes, Tercer
simposio de la geologia de Sonora y (treas adyacentes.
Hermosillo, Sonora, MGxico, Universidad de
Sonora y Universidad Nacional Aut6noma de
MGxico, Instituto de Geologia, 83-85.
MOORE, R. C. & JEFEORDS, R. M. 1968. Classification
and nomenclature of fossil crinoids based on studies
of dissociated parts of their columns. University
of Kansas Paleontological Contributions, 46,
Echinodermata, Article 9, 1-86.
OCHOA-GRANILLO, J. A & SOSA-LEON, J. P. 1993.
Geologia y estratigrafia de la Sierra Agua Verde con
Onfasis en el Paleozoico. Professional dissertation,
Universidad de Sonora, MGxico.
PI~REZ-RAMOS, O. 1992. Permian biostratigraphy and
correlation between Southeast Arizona and Sonora.
Boletin del Departamento de Geologla de la
Universidad de Sonora, 9, 1-74.
POOLE, F. G., STEWART, J. H. & ARMSTRONG, A. K.
1984. Newly Discovered Paleozoic Section in Central
Sonora, in Geological Survey Research 1982. US
Geological Survey, Professional Paper, 1375, 1-66.
Ross, C. A. 1995. Permian fusulinaceans. In: SCHOLLE,
P. A., PERYT, T. M. & ULMER-SCHOLLE,D. S. (eds)
The Permian of Northern Pangea. Volume 1.
Springer, Berlin, 167-185.
ROWAN, M. G. 1991. Three-dimensional finite strain
from crinoid ossicles. Journal of Structural Geology,
13, 1049-1059.
Downloaded from http://sp.lyellcollection.org/ at Pennsylvania State University on February 20, 2016
ATOKAN REGIONAL ENCRINITE OF NW MEXICO
SAMANKASSOU, E. 2002. Cool-water carbonates in a
palaeoequatorial shallow-water environment: The
paradox of the Auernig cyclic sediments (Upper
Pennsylvanian, Carnic Alps, Austria-Italy) and its
implications. Geology, 30, 655-658.
SCOTESE, C. R. ~; LANGFORD, R. P. 1995. Pangea and
the Paleogeography of the Permian. In: SCHOLLE,P.
A., PERYT, T. M. & ULMER-SCHOLLE, D. S. (eds)
The Permian of Northern Pangea, Volume 1: Paleogeography, Paleoclimates, Stratigraphy. Springer,
Berlin, 3-19.
SPEYER, S. E. & BRETT, C. E. 1988. Taphofacies models
for epiric sea environments: Middle Paleozoic
examples. Palaeogeography, Palaeoclimatology,
Palaeoecology, 63, 225-262.
STEWART, J. H. & POOLE, F. G. 2002. Inventory of
Neoproterozoic and Paleozoic strata in Sonora,
Mexico. US Geological Survey, Open-file Report
02-97. http://geopubs.wr.usgs.gov/open-file/of02-97
STEWART, J. H., MADRID, R. J., POOLE, F. G. &
KETNER, K. B. 1988. Studies of Late Proterozoic,
Paleozoic, and Triassic rocks in Sonora, Mexico
(ABS.). In: ALMAZ,kN-Vfi~ZQUEZ,E. & FERNANDEZ,
A. M. A. (eds) Restimenes, Segundo simposio sobre
geologia y mineria de Sonora. Universidad Nacional
Aut6noma de M6xico, Instituto de Geologia, 60-62.
STEWART, J. H., POOLE, F. G., HARRIS, A. G.,
REPETSKI, J. E., WARDLAW,B. R., MAMET, B. L. &
MORALES, R. J. M. 1999. Neoproterozoic (?) to
209
Pennsylvanian inner-shelf, miogeoclinal strata
in Sierra Agua Verde, Sonora, Mexico. Revista
Mexicana de Ciencias Geol6gicas, 16, 35-42.
VACHARD, D., FOURCADE, E. ET AL. 1997. Foraminif&es et algues du Permien du Guatemala. GOobios,
30, 745-784.
VACHARD,D., FLORES DE DKOS,A., BUITRON, B. E. &
GRAJALES-NISHIMURA, M. 2000a. Biostratigraphie
par fusulines des calcaires carbonif~res et permiens
de San Salvador Patlanoaya (Puebla, Mexique).
Gkobios, 33, 5-33.
VACHARD, D., FLORES DE DIOS, A., PANTOJA, J.,
BUITRON, B., ARELLANO,J. & GRAJALES,M. 2000b.
Les fusulinides du Mexique, une revue biostratigraphique et pal6og6ographique. Gbobios, 33,
655-679.
VACHARD,D., VIDAURRE-LEMUS,M., FOURCADE,E. 8r
REQUENA, J. 2000c. New Early Permian fusulinid
assemblage from Guatemala. Comptes Rendus de
l'Acadkmie des Sciences de Paris, 33, 789-796.
WEIDLICH, O. 2007. Permian reef and shelf carbonates
of the Arabian platform and Neo-Tethys as
recorders of climatic and oceanographic changes.
In: /~EVARO, J. J., ARETZ, M., BOULVAIN, F.,
MUNNECKE, A., VACHARD,D. & VENNIN, E. (eds)
Palaeozoic Reefs and Bioaccumulations: Climatic
and Evolutionary Controls. Geological Society,
London, Special Publications, 275, 229-253.