earth history geol 2110
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Earth History GEOL 2110. The Mesozoic Era Tectonic and Geologic History o f North America. Major Concepts. The geologic history of North America during the Mesozoic Era was dominated by two contrasting tectonic processes : - PowerPoint PPT PresentationTRANSCRIPT
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Earth History GEOL 2110
The Mesozoic EraGeology of North America
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Major Concepts• The geologic history of North America during the
Mesozoic Era was dominated by two contrasting tectonic processes :On the east, continental rift of Pangea was creating the present-
day Atlantic marginOn the west, compressional tectonics accreted exotic terranes in
the early Mesozoic (Triassic and early Jurassic periods) and then became Andean-type volcanic arc in the mid- to late Mesozoic (Jurassic and Cretaceous periods).
• Sedimentation in the Mesozoic was largely in western NA and was dominantly non-marine with sediment supplied by the erosion of the Appalachians and the emerging Cordilleran Orogen.
• A major transgression in the Cretaceous created a Great Interior Seaway where great accumulation of marine and non-marine sediment were deposited in the Great Plains
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Events of the Mesozoic Era
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Un-Making PangeaSuperplume
disassembles the Supercontinent
Now PangeaLate Triassic (215Ma)
Late Cretaceous (95Ma)
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Continental RiftingRift grabens and aulocogens bounded by normal faults
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Mesozoic Rift BasinsNon-marine-type Marine-type
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Graded Alluvial Fan Deposits along Graben Fault Scarps
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Triassic Red-bed Sedimentation in the West
2013 SEG Field TripPetrified Forest
Painted DesertUpper Triassic Chinle Formation
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Petrified WoodReplacement by Silica
Groundwater picks up silica from sediment that is rich in siliceous volcanic ash that is altered to clay (bentonite)
That the wood does not rot, indicates reducing environments with rapid deposition (floodplains, lagoons, ). The petrifaction process preserves the original cellular structure of the wood
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Early Jurassic RegressionEolian SS Mark the End of the Absaroka Sequence
Navajo Desert
2013 SEG Field TripCanyon de Chelley
Navajo SandstoneCanyon de Chelley
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Navajo Sandstone at Zion NP, Utah
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Dinos on the Dunes
Dilophosaurus
Coprolite??Dino-pie
Dilophosaurus Footprints in the Jursassic Kayenta Formation near Tuba City, AZ
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Middle Jurassic TransgressionBrings on the Zuni Sequence
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Morrison FormationUpper Jurassic Dinosaur Graveyard
Zuni SequenceUnconformity
Absaroka Sequence
Dinosaur National Monument, COnear Green River, UT
Non-marine mudstone, sandstone, siltstone and limestone that is variegated light grey, greenish gray, or red; represents floodplains deposits
TransgressiveRegressive
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Zuni Sequence Clastic Wedge Deposit in the Cretaceous Foreland Basin of the
Cordilleran Orogen.
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Next Lecture
Tectonic History of the North American Cordilleran