Earth History GEOL 2110

1. Earth History GEOL 2110 The Cenozoic Era The Modern World Emerges Tectonics

2. Major Concepts • The volcanic null that corresponded with the LaramideOrogeny starting in the late Cretaceous ended in the late Eocene epoch (~40Ma) with the resumption of arc magmatism along the western margin of NA • Starting in the Miocene (~20Ma), the collision of the East Pacific Rise created a transform boundary between the Pacific and NA plates; this brought on the Basin and Range-style extension tectonics, the uplift of the Colorado Plateau, the creation of the Rio Grande Rift, and shift in the motion of the Pacific plate • The collision of India and various microcontinentsspalled from Gondwana’s break-up closed the Tethy’s Sea and created the Alpine-Himalayan orogenic belt

3. Summary of the Cenozoic PEOMPP

4. Early Cenozoic (66-40 Ma)Paleocene - Mid-Eocene LaramideOrogeny Block uplift of the Precambrian basement

5. LaramideOrogenyMagmatic Null Zone – Shallow Slab Subduction

6. Sedimentation in LaramideIntermontane Basins BH PR WR GR U Coal Seams in the Powder River Basin, WY LacustrineShales of the Green River Basin, UT LacustrineShales Marls Bryce Canyon NP, UT

7. Middle Cenozoic (40-20 Ma)Late Eocene – Oligocene – Mid-Miocene Resumption of continental volcanic arc magmatism as subduction of the Farallon Plate steepens Tectonics during the Oligocene (~30 Ma)

8. Middle Cenozoic (40-20 Ma)San Juan Volcanic Field La Garita Caldera (28Ma) San Luis Tuff, Wheeler Geologic Monument

9. Middle Cenozoic (40-20 Ma)Burial and Exhumation of the Laramide Mountains LaramideMtns Exhumed 66Ma 35 Ma LaramideMtns Re-Buried LaramideOrogeny Post- LaramideOrogeny 57 Ma LaramideMtns Buried 15 Ma LaramideMtns Re-Exhumed 50 Ma

10. Laramide Sediments and Volcanic Ash Spreads across the Great Plains Eocene – Oligocene fluvial sediments of the White River Group, Badlands, SD

11. Late Cenozoic (20-0 Ma)Mid-Miocene – Pliocene –Pleistocene - Holocene Mid-Miocene (~15 Ma) Pliocene (~5 Ma) Collision of East Pacific Rise with NA plate creates the San Andreas Transform Fault System, Basin and Range Province, Colorado Plateau and Rio Grand Rift

12. Basin and Range ProvinceExtensional Thinning of the Crust Sevier Deformation Listric Normal Faults

13. Basin and Range ProvinceExtensional Thinning of the Crust

14. Basin and Range ProvinceExtensional Thinning of the Crust Extension due to mantle upwelling in area of Slab Gap

15. Basin and Range Province Extensional Thinning of the Crust As the SA transform boundary grows, Basin and Range Extension migrates to the North. Establishment of rift zone in the Gulf of California kills extension in the southern Basin and Range.

16. The Slicing and Dicing of California Narrow fault –bound basins rapidly fill with great thickness of sediment that are simultaneously deformed (e.g., Ventura Basin) Pliocene (~5 Ma)

17. Uplift of the Colorado PlateauRejuvenation of Mature Rivers Mantle Upwelling? Pliocene (~5 Ma)

18. Columbia River Basalts, Snake River Basalts, and the Yellowstone Hotspot Edge of Craton NA Drift Yellowstone Newberry

19. Mantle Plume-Generated Volcanism Columbia River Basalts Yellowstone Hydrothermal Field Newberry Rhyolite

20. Present-Day Tectonic Picture

21. Pacific Plate Tectonics

22. Passive Margins East and South Erosion of North America – River and Deltaic Deposits Triassic-sourced Halite Deposits Pangea Break-up – Shallow Marine Deposits

23. Passive Margins East and South Rejuvenation of the Appalachians

24. The Closing of the Tethys Sea

25. 25 Ma The Closing of the Tethys Sea 5-6 Ma Mediteranean Dries Up -Evaporites 4 Ma Straits of Gibraltar open up

26. Tectonics of East Asia

27. Next LectureThe CenozoicThe Modern World EmergesClimate and Life