esas0302temp_assemblebasement-stu

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Unformatted text preview: Assembling
the
Southwest EARTH
SCIENCE
in ARIZONA
and
the SOUTHWEST Topography
reflects
rock
types
as
well
as
the
results
of
landscape
processes (U.S.
Geological
Survey:
A
Tapestry
of
Time
and
Terrain,
http://tapestry.usgs.gov) Assembling
the Southwest 2 Recounting
the
geologic
history
of
Arizona
and
the
Southwest on
the
basis
of
geological
evidence… Chinle Kingman Kingman Flagstaff Flagstaff Phoenix Yuma Yuma Tucson (S. Reynolds) Assembling
the Southwest 3 The
geologic
time
scale Eons Eras Periods Epochs Ma
=
“million
years
ago”









Ga
=
“billion
years
ago” (U.S.
Geological
Survey,
2007) Assembling
the Southwest (U.S.
Geological
Survey) 4 Assembling
the
Southwest Inner Gorge, Grand Canyon, Arizona (U.S. Geological Survey, 2007) Assembling
the Southwest 5 Proterozoic
basement
rocks
and
younger
cover Cover:
Sedimentary
and
volcanic
rocks
deposited
on
top
of
basement Schematic
west‐east
cross‐section
of
Colorado
Plateau
at
Grand
Canyon (Reynolds,
Johnson,
Kelly,
Morin,
&
Carter,
2010) Basement:
Oldest
crust;
crystalline
metamorphic
and
igneous
rocks Assembling
the Southwest 6 Interesting
age
patterns
in
the
Southwest
basement:
Terranes Some
basement
rocks
in
other parts
of
North
America are
more
than
3
billion
years
old Younger
rocks Basement (Press,
Siever,
Grotzinger,
&
Jordan,
2004) But
the
oldest
basement in
the
Southwest
is 1.84
billion
years
old Assembling
the Southwest (Karlstrom
et
al.,
2002) 7 Plate
tectonics assembled
the
basement (Reynolds, Johnson, Kelly, Morin, & Carter, 2008) Assembling
the Southwest (R. Blakey) 8 Island
arc Craton By
the
process
of
accretion, new
continental
crust
is
assembled (Karlstrom
et
al.) Cheyenne Suturing Tens
of
millions
of
years
later, another
island
arc
arrives O 


cr lder aton Location
of present‐day Pennsylvania Accreting
continent Location
of present‐day Arizona Continental
accretion from
this
general
direction Assembling
the Southwest (Condie
&
Sloan,
1998) 9 By
the
process
of
accretion, new
continental
crust
is
assembled (Karlstrom
et
al.) Ol 

cra der
 ton Location
of present‐day Pennsylvania Location
of present‐day Arizona Assembling
the Southwest Continental
accretion from
this
general
direction 10 By
about
1.1
billion
years
ago,
accretion
ended, plate
motions
changed,
and
the
crust
was
pulled
apart (R.
Blakey) Assembling
the Southwest (Reynolds,
Johnson, Kelly,
Morin,
&
Carter,
2008) 11 Apache
Group
ca.
1350‐1050
Ma (Mesoproterozoic
to
Neoproterozoic) Assembling
the Southwest Salt
River
Canyon


(Reynolds) 12 Grand
Canyon
Supergroup
ca.
1250‐730
Ma (Mesoproterozoic
to
Neoproterozoic) (Karlstrom
and
Crossey,
2005) Assembling
the Southwest 13 The
“Great
Unconformity”
of
the
Southwest Paleozoic Grand
Canyon inner
gorge USGS Meso‐ proterozoic Paleo‐ proterozoic basement Assembling
the Southwest 14 ...
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