esas0403temp_TrJSouthwest-stu

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Unformatted text preview: The
Triassic‐Jurassic
Southwest The
Triassic‐Jurassic
Southwest ...red
sand,
the
dark
smoldering
purple
reds
of
ancient
rocks, Chinle,
Shinarump,
and
Moenkopi,
the
old
Triassic
formations
full
of radium,
dinosaurs,
petrified
wood...fatal
evil
monstrous
things, beautiful,
beautiful.


























































Edward
Abbey EARTH
SCIENCE
in ARIZONA
and
the SOUTHWEST (U.S.
Geological
Survey,
2007) Petrified
Forest
National
Park,
Arizona Triassic
global
paleogeography
and
climate Pangaea
still
mostly
intact Gradual
transition
from
dry
Permian
to
wetter
Triassic The
Triassic‐ Jurassic
Southwest Stanley
(2005) 2 Where
Triassic
and
Jurassic
rocks
are
found in
today’s
Southwest J T R The
Triassic‐ Jurassic
Southwest U.S.
Geological
Survey,
tapestry.usgs.gov 3 Northern
Pangaea
at
245
Ma
(Early
Triassic) Future
 North
America Less
arid than
in
 Permian Equatorial Future
 Gulf
of
Mexico Paleogeographic
map
by
R.
Blakey,
NAU The
Triassic‐ Jurassic
Southwest 4 Permo‐Triassic
Southwest Sonoma orogeny Paleogeographic
map
by
R.
Blakey,
NAU The
Triassic‐ Jurassic
Southwest 5 Sonoma
orogeny:
Late
Permian‐Early
Triassic
accretion Golconda thrust Roberts Mountain thrust (Baldridge, 2003; after Levin, 1991) First
event
of
the
“Cordilleran
orogeny” Last
westward‐dipping
subduction;
transition
in
Triassic
to eastward‐dipping
subduction
and
magmatic
arcs
along
margin. The
Triassic‐ Jurassic
Southwest 6 Sonoma
orogeny:
Late
Permian‐Early
Triassic
accretion (Stanley, 2005) The
Triassic‐ Jurassic
Southwest 7 Early
Triassic
Southwest:

slightly
wetter
climate Fluvial
and tidal‐mudflat environments Paleogeographic
map
by
R.
Blakey,
NAU The
Triassic‐ Jurassic
Southwest 8 Fluvial
and
mudflat
sediments: Early
Triassic
Moenkopi
Formation Muds,
channel
sands,
ripples, evaporites
(gypsum) Along
I‐40,
Joseph
City,
Arizona The
Triassic‐ Jurassic
Southwest 9 Middle
to
Late
Triassic
Southwest:
wetter
still How
much of
Ancestral
Rockies
 remained
at
this
time? Low relief Major fluvial systems Arc volcanism upwind Paleogeographic
map
by
R.
Blakey,
NAU The
Triassic‐ Jurassic
Southwest 10 Fluvial
(channel,
floodplain)
and
alluvial
sediments: The
Upper
Triassic
Chinle
Group Exposed beautifully in the Painted Desert of northern Arizona Exposed beautifully in the Painted Desert of northern Arizona Doc Searls (Wikimedia) The
Triassic‐ Jurassic
Southwest 11 The
Chinle
(Chinle‐Dockum)
paleoriver (Baldridge,
2004,
after
Riggs
et
al.,
1996) The
Triassic‐ Jurassic
Southwest 12 fluvial
conglomerates
and
sandstones at
base
of
Chinle
Group Shinarump
Formation: Permian
DeChelly
 Sandstone
(eolian) Tséyi’
(Canyon
de
Chelly),
Navajo
Nation,
Arizona The
Triassic‐ Jurassic
Southwest 13 Thick,
colorful,
slope‐forming
mudstones
and
thin
sandstones
make
up
much
of
the Upper
Triassic
Chinle
Group Bluewater
Creek
Formation Blue
Mesa,
Zuni
Mountains,
New
Mexico The
Triassic‐ Jurassic
Southwest 14 Thick,
colorful,
slope‐forming
mudstones
and
thin
sandstones
make
up
much
of
the Upper
Triassic
Chinle
Group Badlands
formed
on
the Petrified
Forest
Formation
(Blue
Mesa
Member) Paleosol
horizons The
Triassic‐ Jurassic
Southwest Petrified
Forest
National
Park,
Arizona 15 Thick,
colorful,
slope‐forming
mudstones
and
thin
sandstones
make
up
muchof
the Upper
Triassic
Chinle
Group Petrified
Forest
Formation
(Painted
Desert
Member) The
Triassic‐ Jurassic
Southwest Petrified
Forest
National
Park,
Arizona 16 Paleosols
(ancient
soils)
abound
in
the
Chinle
Group Paleosols, Petrified Forest Formation, Painted Desert Member The
Triassic‐ Jurassic
Southwest 17 Uppermost
part
of
the
Chinle
Group Wingate
Sandstone
(Glen
Canyon
Group) Eolian
erg Rock
Point
Fm Transitional Owl
Rock
Fm Fluvial,
lacustrine Tsé
nikání
(Diné,
Round
Rock),
and
badlands,
near
Chinle,
Navajo
Nation,
Arizona The
Triassic‐ Jurassic
Southwest 18 Late
Triassic
arc
volcanism
influenced
Chinle
deposition Arc volcanism upwind Paleogeographic
map
by
R.
Blakey,
NAU The
Triassic‐ Jurassic
Southwest 19 Riotous
colors
from
mineral
pigments Petrified
Forest
Formation,
Painted
Desert
Member, Painted
Desert,
Petrified
Forest
National
Park,
Arizona The
Triassic‐ Jurassic
Southwest 20 Permineralized
(petrified)
wood Logs
of
Triassic
conifers
(Araucarioxylon
arizonicum)
fell
into
Chinle
streams….
 They
became
buried
in
sand
and
gravel
bars enriched
in
SiO2
from
volcanic
ash…. Organic
matter
was
replaced
by
silica…. The
result: Arizona’s state
fossil! Crystal
Forest,
Petrified
Forest
National
Park,
Arizona The
Triassic‐ Jurassic
Southwest 21 Also,
uranium The
Triassic‐ Jurassic
Southwest 22 Dry
(Permian),
to
wet
(Triassic),
to
dry
again… Upper
Triassic‐Lower
Jurassic
Glen
Canyon
Group: mostly
eolian
deposition Wingate Sandstone Upper
Triassic
Chinle
Group: Muds,
sands,
paleosols Lower
Triassic
Moenkopi
Fm: Fluvial
sands
and
muds Upper
Permian
White
Rim
Ss: Eolian
sands White
Rim,
Canyonlands
National
Park,
Utah The
Triassic‐ Jurassic
Southwest 23 Upper
Triassic
Wingate
Sandstone: sands
deposited
in
eolian
erg
environments Comb
Ridge
monocline,
Utah


 The
Triassic‐ Jurassic
Southwest Westwater
Canyon
(Colorado
River),
Utah 24 Jurassic
global
paleogeography
and
climate North
America
rifted
(opening
Atlantic)
away
from
Gondwanaland North
American
climate
became
dry
again
in
Jurassic The
Triassic‐ Jurassic
Southwest Stanley (2005) 25 Pangaea
coming
apart
at
180
Ma
(Early
Jurassic) The
Triassic‐ Jurassic
Southwest 26 Early
Jurassic
Southwest:
extremely
arid Nugget
Ss Aztec
Ss Navajo
Ss A
vast
erg,
 perhaps the
greatest
 in
Earth
history! Vampire
Ss? Paleogeographic
map
by
R.
Blakey,
NAU The
Triassic‐ Jurassic
Southwest 27 Lower
Jurassic
Navajo
Sandstone:
eolian
erg Zion
National
Park,
Utah




 The
Triassic‐ Jurassic
Southwest 28 Lower
Jurassic
Aztec
Sandstone:
eolian
erg (westward
equivalent
of
Navajo
Sandstone) The
Triassic‐ Jurassic
Southwest Silica
Dome,
Valley
of
Fire
State
Park,
Nevada 29 Morrison
Formation San
Rafael
Group Wingate
Sandstone Chinle
Group The
Triassic‐ Jurassic
Southwest Triassic‐Jurassic
rocks,
Lukachukai
Cliffs,
Navajo
Nation,
Arizona 30 ...
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