Triassic - rifting of North America from Pangaea
1.  Rift Basins in eastern US - Connecticut Basin, Palisades of Hudson River - New England to Georgia and around the Gulf of Mexico
draw: 
 
 
 

2.   Western States (Utah, Arizona, Wyoming, +) include extensive alluvial redbeds and eolian strata.  Probably in a foreland basin of Sonoma Orogeny (Sonomia = suspect terrane in SE Oregon, N California and Nevada).
- DRAW W-dipping subduction with Sonomia terrane coming in from west, North America to east going down tubes. (see 15.17)
 
 
 
 
 

 Jurassic - passive margin to the east, Andean-style margin to the west
1.  Thick sedimentation including evaporites and carbonates and clastics all around east coast and Gulf of Mexico following Triassic breakup.... Passive Margins.
2.  Andean style subduction on the West, with the Franciscan Melange holding up the western end of the Golden Gate Bridge in San Francisco (includes Blueschist grade metamx), the Sierra Nevada Batholith belt representing the extensive granitic plutonic belt, and the Great Valley Ophiolite wedged in between.
 
 
 
 
 
 
 
 
 
 
 
 

3.  FTB & Foreland basin developing in the back-arc region.  (Not a Back-Arc Basin)  caused by thrust faulting, loading.  Coarse detritals toward the foreland, fine detritals in the middle,  and carbonates toward the craton. (15.26)
 
 

 Cretaceous - high sea levels - Tethyan Seaway - Cretaceous Seaway
1.  East Coast - carbonates and clastics of the passive margin
2.  West Coast - continuing subduction and collision with lots of little suspect terranes.  Probably a shallowing of the subduction angle (continental arc migrated cratonward, then stopped).
3.  Cretaceous Seaway - North America divided into two largish Islands by a seaway with depths up to 200 m (probably). Part of the foreland basin.  Sediments marine and nonmarine clastics and some carbonates.  Lots of beaches, coals, deltas.
 
 
 
 

Cretaceous High Eustatic Sea Levels - WHY?
- Possibly Rapid Sea Floor Spreading...
- Alternative: simply an artifact of supercontinent breakup.
 
 
 

2) reign of the non-flowering seed bearing plants - Age of Cycads (a kind of palm)
- Ginko trees developed about 200 Ma - oldest genus of tree still extant

3)  rise of the angiosperms - flowering plants
- By the end of the Cretaceous, angiosperms were the dominant land plants.  Birch, Maples, Willows all had exceeded the conifers (Christmas trees)

 Animals -  Age of Reptiles
1) Dinosauria - take Frank’s class
- Maiasaura (good mother dinosaur) - built nests, nurtured young, migrated in herds
Warm-blooded?  probably, at least to some extent.
A) Several aspects of behavior - how they walked, how fast they moved, migration, etc.
B) Bone structure - paleohistology says open porous bones only in warm blooded creatures (like birds).
C) Oxygen isotopes of bones.

2) First  Mammals
- Late Triassic => stayed small and unobtrusive
- diverse forms present by end Mesozoic.

3)  Terminal Cretaceous Extinctions
- end of the Dinosaurs and about 75% of other species
- impact of a large meteorite in Chicxulub, Mexico
- shocked quartz is one key, microtectites are another
- fires, acid rain (NO2 forming in atmosphere, H2SO4 from evaporites), dust => first global refrigeration (nuclear winter) then global warming (greenhouse from extra water vapor in atmosphere),
- Alternative: perpetual darkness - died of depression.
- Alternative: Rise of angiosperms and pollen --??
 
 

Laramide Orogeny - several different orogenic events, from Late Cretaceous to Eocene
(Figs 17.15-17.19)
- result is a series of basement uplifts around the western interior (Colorado, Wyoming, Montana)
- basins such as the Wind River, Green River, Picance
- magmatic arc moved from Cal-Nev to Ariz-NewMex-Colorado
- what could have caused this? (hint: magma generation from subducted lithosphere occurs at about 100 km depth)
 
 
 
 
 

Cenozoic fluvial and lake deposits - in all the Laramide basins formed by basement uplifts
- Eocene Green River Oil Shales (Wyoming, Utah, Colorado) - Fossil Fish, oil resource
- current site of erosion (South Dakota Badlands, Utah's Bryce Canyon, Fig 17.34)
 
 

Oligocene-Miocene Ridge Subduction (Fig 17.32)
- Pacific ocean region divided into the Pacific (west) and Farallon (east) oceanic plates
- North America moves westward across the East Pacific Rise (mid-ocean ridge)
*** ~30 Ma began subduction of East Pacific Rise
- changed from a convergent margin to a transform margin - San Andreas Fault.
 
 
 
 

 Cenozoic extension
1) uplift of the Sierra Nevada
- old Mesozoic batholiths eroded down, suddenly rejuvenated from new stress regime
- uplifted along eastern flank normal faults (up 4000m)
2)  Basin and Range - extension, possibly related to subduction of East Pacific Rise
3) Rio Grande Rift - extension and basaltic volcanics on east side of the Colorado Plateau
4) Colorado Plateau - unrifted, but uplifted due to high heat flow in region
 
 

More Cenozoic volcanism
1) Columbia River Basalts and Yellowstone
 - passage of a hot spot beneath the continent
 - flood basalts as much as 2-3 km thick
 - continuing basaltic and rhyolitic magmatism
2) Cascades - continuing volcanism - subduction of the Juan de Fuca plate (Farallon remnant)
 
 
 
 

Cenozoic clastics - Gulf of Mexico passive margin
1) Paleocene-Eocene clastics: thickest offshore Texas
- Wilcox Group - lots of Oil & Gas
- Composition: lots of volcaniclastics - lithic sandstones - immature sandstones
2) Miocene-Holocene - mostly offshore Louisiana
- Rise of the Mississippi drainage basin
- Composition: quartzose sandstones- mature sediments
 
 
 

Discuss the change in composition, location of detrital sedimentary rocks in the Cenozoic Gulf of Mexico in terms of changing provenance.
 
 
 

Other places of the World - overheads
1.  India: collision with Asia around 40 Ma => Himalayas, Tibetan Plateau, Indus & Bengal Fans
- also we find world-wide changes in oceanic plate directions - like the Hawaii-Emperor Seamount chain at about 42 Ma.
2.  Red Sea - Arabia: rifting intiated ~ 10 Ma, sea floor spreading ~ 2-3 Ma.  Zagros Mtns in Iran...
3.  Sea of Japan: back-arc spreading, rifting from Asia, current Andesitic volcanism
 
 

1.  Antarctica - mid-Cenozoic
- first dropstones in Middle Oligocene
- fully glaciated by Miocene
- Why? polar ocean (Southern Ocean) just opened
 
 
 

2.  Northern Hemisphere - Plio-Pleistocene
- glaciers cover N. America and Europe
 - latest Pliocene closing of the Isthmus of Panama = no more equatorial circulation.
- very little glacial cover in Siberia....(why?)
 
 
 

3. Control of Glacial Interglacial Cycles
 Pleistocene glacial cycles = ~100,000 year cycle with other wiggles (draw)
- Climate change and Milankovitch Cycles
Changing amount of sunlight causes climate variation
- ovalness (100,000 years), tilt (41,000 years), direction of tilt (22,000 years) (our July = less sunlight than our January does, will change in 11ka)
- Milankovitch cycles control temporal patterns of glaciation, not why they are here.
 
 
 

 4.  Overall control on Glaciation on Earth:
*** Plate tectonics governs climate patterns.
***  create colder conditions
- Continents near the poles
- High latitude oceanic circulation.
 
 

2.  Plants were much like present - angiosperms.  Tell us lots about climate.  Very warm and seasonal worldwide in Paleocene-Eocene, big temperature drop in the E. Oligocene.
 
 

3.  Age of Mammals.  Proliferation of styles, sizes.
- Whales evolved
- Marsupials - developed in Australia and S.America.  Died off in S. America during the Pliocene after establishment of the Central America land bridge.