esas0501temp_KSouthwest-stu

esas0501temp_KSouthwest-stu - The
Cretaceous
Southwest:

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Unformatted text preview: The
Cretaceous
Southwest: Folding,
flooding,
fossil
fuels EARTH
SCIENCE
in ARIZONA
and
the SOUTHWEST Navajo
Coal
Mine,
San
Juan
Basin,
Navajo
Nation,
New
Mexico (U.S.
Geological
Survey,
2007) Where
Cretaceous
rocks
are
found in
today’s
Southwest K U.S. Geological Survey, tapestry.usgs.gov The
Cretaceous
Southwest 2 North
America
at
140
Ma
(Early
Cretaceous) More terranes coming in
 to
NW Subduction, arc
volcanism, compression Terrestrial environments in
the
SW Young Atlantic Ocean Paleogeographic
map
by
R.
Blakey,
NAU The
Cretaceous
Southwest 3 The
Early
Cretaceous
Southwest Mowry
Sea Subduction: Sevier Orogeny Paleogeographic
map
by
R.
Blakey,
NAU The
Cretaceous
Southwest 4 Subduction,
and
Sevier
Orogeny
(130‐80
Ma) W E (After
Humphreys
et
al.,
2003) The
Cretaceous
Southwest 5 The
Sevier
orogeny
(about
130
to
80
Ma) Large
areas
of
the
interior
West
deformed subsidence
97‐90
Ma subsidence
90‐80
Ma subsidence
97‐90
Ma subsidence
90‐80
Ma subsidence
94‐90
Ma subsidence
90‐80
Ma subsidence
94‐90
Ma subsidence
90‐80
Ma Stanley
(2005) The
Cretaceous
Southwest 6 North
America
at
130
Ma
(Early
Cretaceous) Sevier orogen Foreland basins Paleogeographic
map
by
R.
Blakey,
NAU The
Cretaceous
Southwest 7 Just
add
water!


The
Western
Interior
transgressions 115
Ma
(Late
Cretaceous
Period) The
Cretaceous
Southwest Paleogeographic
map by
R.
Blakey,
NAU 8 (Reynolds,
Johnson,
Kelly, Morin,
&
Carter,
2008) W E Western Interior Sea The
middle
of
the continent subsides,
and is
flooded
by
a shallow
sea. (Reynolds,
Johnson,
Kelly,
Morin,
&
Carter,
2008,
after
Blakey) The
Cretaceous
Southwest 9 The
Late
Cretaceous
Western
Interior
Sea : last
major
episode
of
SCISWO 
in
North
America The
Cretaceous
Southwest 10 Time
1 Beach
sand Transgressing
seas
deposit
a sequence
of
sediments Time
2 Mud
over sand Limestone Time
3 Mudstone Reef Limestone
over mud Sandstone Older
units Section
formed during
a
transgression The
Cretaceous
Southwest 11 Reynolds
et
al.
(2008) Time
1 Mud
over limestone Regressing seas reverse the sequence. Time
2 Beach
sand
over mud Sandstone Time
3 Dune
sand Mudstone Section
formed during
a
regression Limestone The
Cretaceous
Southwest Reynolds
et
al.
(2008) 12 Upper
Cretaceous
sedimentary
rocks
in
the
central
Colorado
Plateau record
two
major
NE‐SW
transgressions U.S.
Geological
Survey The
Cretaceous
Southwest 13 SCISWO
! First
Western
Interior
transgression Flooding
the
 foreland
basins Sevier
Mountains Paleogeographic
map
by
R.
Blakey,
NAU The
Cretaceous
Southwest 14 Transgressive
shoreline
deposit:
Dakota
Sandstone Tidal
channel
sand Shoreline sands
and
muds Thin
coal
seams Lichíí
(Red)
Wash,
west
of
Shiprock,
Navajo
Nation,
New
Mexico The
Cretaceous
Southwest 15 As
the
sea
comes
in,
marine
muds
and
then
limestones are
deposited:
Mancos
Shale
and
Greenhorn
Limestone (Removed
by
erosion) Sandstone Mudstone Limestone regression Upper
Mancos
Shale Greenhorn
Limestone (thin
here,
 thicker
to
east) Mudstone transgression Lower
Mancos
Shale Sandstone Just
above
Lichíí
(Red)
Wash,
west
of
Shiprock,
Navajo
Nation,
New
Mexico The
Cretaceous
Southwest 16 Greenhorn
Limestone
deposition
was
thicker in
the
deeper
middle
of
the
Western
Interior
Seaway Eastern Colorado Stanley (2005) The
Cretaceous
Southwest 17 The
Western
Interior
Sea
regressed
partway
back, temporarily
leavingthe
Southwest Emery
Sandstone
(shoreline
returning) Upper
Mancos
Shale East
of
Capitol
Reef
National
Park,
Utah

























 The
Cretaceous
Southwest S.
Reynolds,
ASU 18 The
Western
Interior
Sea
regressed
partway
back, temporarily
leaving
the
Southwest Point
Lookout
Sandstone Upper
Mancos
Shale Marine
mudstone
(grey,
finely‐bedded) Storm
sands (thin,
brown) Table
Mesa,
south
of
Shiprock, Navajo
Nation,
New
Mexico Shiprock,
Navajo
Nation,
New
Mexico The
Cretaceous
Southwest 19 Black
Mesa,
Arizona: sandstone,
wetland
mudstone,
coal deposited
between
the
two
transgressions The
Cretaceous
Southwest 20 Then
the
Western
Interior
Sea
came
back
once
more: first
bringing
shoreface
(beach)
sandstone Cliff
House
Sandstone (Upper
Cretaceous) Mesa
Verde
National
Park, Colorado L. L. Maher North
America
at
85
Ma
(Late
Cretaceous) Second
and final transgression onto
the
SW Seas
went
as
far as
present‐day Show
Low Paleogeographic
map
by
R.
Blakey,
NAU The
Cretaceous
Southwest 22 Second
transgressive
cycle Lewis
Shale Cliff
House
Sandstone Trujillo
Canyon,
San
Juan
Basin,
New
Mexico The
Cretaceous
Southwest 23 North
America
at
75
Ma
(Late
Cretaceous) Sea
leaves Southwest for
good Paleogeographic
map
by
R.
Blakey,
NAU The
Cretaceous
Southwest 24 The
Late
Cretaceous
Southwest Paleogeographic
map
by
R.
Blakey,
NAU The
Cretaceous
Southwest 25 From
then
on,
only
nonmarine
sedimentary
deposition in
the
Southwest e.g.,
Fruitland
Formation
(Latest
Cretaceous) wetland
muds,
fluvial
sands Bistahí
(Bisti)
Badlands,
San
Juan
Basin,
New
Mexico The
Cretaceous
Southwest 26 But
each
time
the
Western
Interior
Sea
regressed, extensive
wetlands
developed
along
its
western
shores Sevier
Mountains Western
Interior
Sea Western
Interior
Sea Crust
along
mountain
front
is depressed:
Foreland
basins A A’ Extensive coastal wetlands AZ Foreland basin Western
Interior Sea A A’ U.S.
Geological
Survey The
Cretaceous
Southwest 27 Ancient
wetlands
along
the
shore of
the
Western
Interior
Sea Environments Environments Plant
material accumulates
and
is
buried. The
Cretaceous
Southwest Sediments
deposited Sediments
deposited USGS 28 An
Earth
system
interaction
among tectonics,
climate,
and
sedimentary
deposition =
lots
of
plant
matter
got
buried
in
the
Late
Cretaceous! Sevier Mountains Foreland
basins
provided accommodation
space for
thick
peat
deposits Grotzinger
et
al.
(2007) The
Cretaceous
Southwest 29 Plant
matter
from
these
wetlands
became
peat,
then
coal Wetland Increasingly deep
burial partly‐altered plant
matter “brown
coal” ~
70%
C Lithification Grotzinger
et
al.
(2007) “soft
coal”
80‐90%
C Most
Cretaceous
coal
mined
is
of
subbituminous
rank
(~
75‐80%
C) The
Cretaceous
Southwest 30 Fossil
fuels
such
as
coal
are
geological
materials Fossil
fuels
form
when
organic matter
is
deposited
as
sediment and
undergoes
lithification. Heat
and
pressure
gradually “cook”
away
volatiles (e.g.,
O,
H)
and
concentrate
C
in the
rock. Fossil
fuels
are
associated
with sedimentary
rocks. Grotzinger
et
al. (2007) The
Cretaceous
Southwest Coal
seam
in
Fruitland
Formation
(Upper
Cretaceous), 31 Navajo
Mine,
Navajo
Nation,
New
Mexico Coal
deposits
found
today
in
the
Mountain
West mark
ancient
coastal
wetlands
along
the regressing
Cretaceous
Western
Interior
Sea Maximum
western
extent
of
the Western
Interior
Sea (Older
coals
formed after
earlier
transgressions) Grotzinger
et
al.
(2007) Coal
mine
in northwest
New
Mexico This
coal
is
burned
to
generate power
for
Southwest
cities. 32 The
Cretaceous
Southwest Cretaceous
coalfields
of
the Colorado
Plateau
and
Southern
Rocky
Mountains U.S.
Geological
Survey The
Cretaceous
Southwest 33 Mining
subbituminous
coal
at BHP
Navajo
Mine,
Navajo
Nation,
San
Juan
Basin
west
of
Farmington,
NM (S.
Semken) The
Cretaceous
Southwest 34 Burning
C‐rich
fossil
fuels
such
as
coal
yields
energy C (s, in coal) + O2 (g) ➞ 2 (g) + heat CO CH4(g) + 2O2(g) ➞ CO2(g) + 2H2O(g) + heat C8H18(l) + 12.5O2(g) ➞ 8CO2(g) + 9H2O(g) + heat 85.3%
from fossil
fuels US
Energy
Mix 1850‐2000 Source:
US
Energy
Information Administration Figure
in
Press
et
al.
(2004) The
Cretaceous
Southwest 35 Coal
is
burned
by
APS
and
SRP
to
generate
electricity, which
is
transmitted
to
the
Valley
of
the
Sun. Four
Corners
and
San
Juan
Power
Plants,
northwest
New
Mexico K
coal Press
et
al.
(2004) The
Cretaceous
Southwest 36 Environmental
costs
of
coal
use Mining
(esp.
underground)
is
a
hazardous industry. Surface‐mined
lands
must
be
reclaimed for
subsequent
use. Air
and
water
pollution: Coal
contains
small
amounts
of
pyrite
(FeS2). Burning
coal
forms
gases
SO2
and
SO3,
which make
acid
rain. CO2
from
burning
coal
contributes
to
global climate
change. In
wet
regions,
chemical
weathering
of pyrite
in
coal
creates
acid
mine
drainage (not
a
big
problem
in
SW). Press
et
al.
(2004)
 The
Cretaceous
Southwest U.S.
Geological
Survey 37 Scrubbers
at
Four
Corners
Power
Plant,
New
Mexico The
Cretaceous
Southwest 38 We
depend
on
power
from
the
past (the
Cretaceous
Southwest
)

! The
Cretaceous
Southwest 39 ...
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This note was uploaded on 03/01/2011 for the course GLG 394 taught by Professor Semken during the Fall '10 term at ASU.

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