California Geology
California Geology
Science Content Standards for California Public Schools
6th Grade – Focus on Earth Sciences
Students know how to explain major features of California geology
(including mountains, faults, volcanoes) in terms of plate tectonics.
From:
Geologic Map of California
California Geological Survey,
California Department of Conservation
For free copy, go to:
http://geology.about.com/library/bl/maps/blcaliforniamap.htm
or:
www.consrv.ca.gov/CGS/information/publications/cgs_notes/note_17/note_17.pdf
•Before 2 billion years - ?? no rocks preserved
•1.5-1.8 billion years - ?? intensely metamorphosed rocks only
•1.2 billion years-900 million years - DIVERGENT BOUNDARY
•800-~300 million years - “passive margin”
•~300-30 million years - CONVERGENT BOUNDARY
•Before 2 billion years - ?? no rocks preserved
added
on late
r
Throughout its history, California has been, at
times, the site of all three types of plate
boundaries (divergent, convergent, transform)
•30 million years to present - TRANSFORM BOUNDARY
*Also, Fig.
6.22 in EST
•1.5-1.8 billion years - ?? intensely metamorphosed rocks only
added
on late
r
1.2 billion years-900 million years - divergent boundary
DeLand (2003)
Pahrump Group sediments were deposited in a
restricted, fault-bounded basin similar to
those found today where continents are
breaking up (e.g., Africa).
1
Geology at a divergent plate margin Today.
Sedimentation in fault-Bounded basins
1.2 billion years-900 million years - Divergent boundary in CA
Deposition of “Pahrump Group” sediments during
breakup of “Rodinia” super-continent ~1.1 Byr
From:
R. Blakey, Northern Arizona University, Paleogeography of the Southwestern United States
Pahrump Group: ~billion-year-old deposits in fault-bounded rift basin
Pahrump Group: ~billion-year-old deposits in failed rift arm
Valley
Death
Valley
Death
Valley
Death
Pahrump Group: ~billion-year-old deposits in failed rift arm (aka, aulacogen)
X-section view of Pahrump Group sediments in Amargosa rift basin
N
Valley
Death
Valley
Death
Site of
new ocean
S
Site of
new ocean
N
S
2
4 formation in Pahrump Group
ite
lom
Do
y
da
on
No
ta
lc
ite
m
lo
Do
ite
lom
Do
gs
rin
Sp
Kingston Peak Formation
ck
Be
on
mati
For
ings
Spr
stal
Cry
Bec
k Sp
ring
s Do
lomit
e
y
da
on
No
Kingston Peak Formation
Crystal Springs and Becks Springs Formations
5 formations in Pahrump Group
Kingston
Range
ite
m
lo
Do
Saddle Peak
and Ibex Hills
gs
rin
Sp
Saddle Peak
and Ibex Hills
ck
Be
Kingston
Range
on
mati
For
ings
Spr
stal
Cry
Kingston
Range
Bec
k Sp
ring
s Do
lomit
e
4 formation in Pahrump Group
rkopp
rkopp
Saddle Peak
and Ibex Hills
Kingston Peak and Noonday Formations
rkopp
Kingston Peak Glacial Deposit
rkopp
rkopp
3
Crystal Springs stromatolites and Kingston Peak diamictite
800-~300 million years - “passive margin”
Deposition of thick sequence (10s of
thousands of ft) of widespread sediment
layers all along the west coast of North
America
Development of a Passive Margin after
Divergent Plate Margin leaves the scene
Passive Margin Today: North Carolina
CA
Passive Margin ~900-300 mya: California
ext
ens
ive
pas
m
sive
s
ent
edim
p
g
n
i
ou
r ly p G r
de
un rum
h
Pa
arg
in s
dep
o
par sition
alle
l to in ext
e
con
tine nsive l
a
nta
l m yers
arg
in
Paleogeography of California’s passive margin sediments
R. Blakey, Northern Arizona University
4
Kingston
Range
California’s passive margin sediments
Kingston
Range
California’s passive margin sediments
John
nie F
orm
ation
California’s passive margin sediments
Paleozoic Life: Trilobites
Woo
d Ca
nyon
Form
ation
Za
bri
ski
eQ
ua
rtz
ite
John
nie F
orm
ation
Stirl
ing F
orm
ation
Northern Salt Spring Hills
Trilobite track and head from Wood Canyon Formation, Salt Spring Hills
Paleozoic Life: Graptolites and Archaeocyathids
5
Graptolites from Inyo Range, California
Archeocyathids from Inyo Range, California
Archeocyathids from Inyo Range, California
Archeocyathids from Inyo Range, California
Paleozoic Life: Molluscs (Bivalves) and Brachiopods
Brachiopods from Bird Springs Formation, Salt Spring Hills, California
6
Paleozoic Life: Echinoderms and Foraminifera
Paleozoic Life: Molluscs (Cephalopods) and Brachiopods
Echinoderms from Bird Springs Formation, Salt Spring Hills, California
Rugose Corals from Salt Spring Hills, California
Belemnites from Salt Spring Hills, California
Metamorphic
“Roof Pendants”
In the Sierra Nevada
7
Passive margin sediments as “Roof Pendants”
in Sierra Nevada
Passive margin
sediments as “Roof
Pendants” in Sierra
Nevada
From:
Geologic Map of California
California Geological Survey,
California Department of Conservation
For free copy, go to:
http://geology.about.com/library/bl/maps/blcaliforniamap.htm
or:
www.consrv.ca.gov/CGS/information/publications/cgs_notes/note_17/note_17.pdf
~300-30 million years - CONVERGENT BOUNDARY
Mesozoic –
Subduction
with
Accretion
and
Collisions
Generation of magma chamber/volcano
complexes, sedimentary basins associated
with subduction zones plus accretion of
continental fragments onto western margin
of North America
Formation of Sierra Nevada batholith 300-30 mya
Remains of 100 my old volcano above Sierra batholith, Ritter Range
8
Mesozoic –
Subduction
with
Accretion
and
Collisions
Accreted Terranes in western North America and California (USGS)
Mesozoic –
Accretion of Terranes
9
30 million years to present - TRANSFORM BOUNDARY
Onset of strike-slip faulting (SAF) on
western margin of California. Northward
translation of subduction zone.
Continuing convergence north of Mendocino triple junction
Present-Day
Plate Boundaries
Strike-slip faulting on
modern transform plate
boundary
Mt. Shasta
Mt. Lassen
10
Strike-slip faulting on
modern transform plate
boundary
Strike-slip faulting on
modern transform plate
boundary: transtension
Strike-slip faulting on
modern transform plate
boundary: transtension
Strike-slip faulting on
modern transform plate
boundary: transtension
Figure 7-7 Harden
Wright and Troxel
Death Valley “Turtleback”
Strike-slip faulting on
modern transform plate
boundary: transpression
11
Transverse Ranges
associated with the
Big Bend in the
San Andreas Fault
Strike-slip faulting on
modern transform plate
boundary: transpression
Glacial Polish and Striations near Bishop Pass
Pleistocene Ice Sheet in Sierra
Harden (2004)
Convict Lake Moraines
Faulted glacial moraines near
Crowley Lake, CA
J. Shelton
12