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Review

Review . Paleogene Period Paleocene, Eocene, Oligocene epochs Paleogene life Evolution of whales, giant sharks Origin of grasses Diversification of mammals Earliest primates Extinction of mammals in late Eocene/early Oligocene. Today’s outline. Paleogene paleogeography and climate

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Review

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  1. Review • Paleogene Period • Paleocene, Eocene, Oligocene epochs • Paleogene life • Evolution of whales, giant sharks • Origin of grasses • Diversification of mammals • Earliest primates • Extinction of mammals in late Eocene/early Oligocene Earth History, Ch. 18

  2. Today’s outline • Paleogene paleogeography and climate • Regional geology • Laramide orogeny (western US) • Initial uplift of “modern” Rocky Mountains • Yellowstone “hot spot” • Gulf Coast sedimentation Earth History, Ch. 18

  3. Paleogene paleogeography and climate • Final break-up of Gondwanaland occurred in Paleogene time • Separation of Antarctica from Australia and South America • Final rifting of Greenland from Scandinavia • Opening of North Atlantic / Norwegian seas • Bering Land Bridge connecting Alaska and eastern Siberia Earth History, Ch. 18

  4. Earth History, Ch. 18

  5. Paleogene paleogeography and climate • Paleocene and early Eocene climate was very warm and moist worldwide • Southern England was tropical forest • Floras on Ellesmere Island resembled those of southern California today • High percentage of floras with smooth-margin leaves • Relatively light oxygen isotope ratios (suggesting absence of continental glaciers) Earth History, Ch. 18

  6. Paleogene paleogeography and climate • Beginning in late Eocene, climate rapidly became cooler and drier • Reduction in % of smooth-leafed floras • Relatively heavy oxygen isotope ratios (consistent with growth of continental glaciers) • Establishment of circum-polar currents around Antarctica • Climate change probably was responsible for extinctions of mammals, planktonic foraminifers, replacement of forest ecosystems by prairie ecosystems Earth History, Ch. 18

  7. Evidence for climate change Earth History, Ch. 18

  8. Evidence for climate change Earth History, Ch. 18

  9. Antarcticcircumpolarcurrent Earth History, Ch. 18

  10. Laramide orogeny • Western margin of North America remained a convergent margin with subduction zone • Laramide orogeny was a Paleocene/Eocene event • Igneous activity and fold-thrust belt in Idaho/Montana and Canadian Rockies (northern zone) • Igneous activity and fold-thrust belt in Arizona/New Mexico and northern Mexico (southern zone) • Central zone of basement uplifts and basins (Colorado, Utah, Wyoming) Earth History, Ch. 18

  11. Laramideorogeny Earth History, Ch. 18

  12. Laramide orogeny • Central zone of basement uplifts and basins created Uinta Mountains (Utah), Wind River Mountains (Wyoming), Black Hills (South Dakota), and Front Range (Colorado) • Intermontane basins became enormous lakes • Uinta Basin / Green River Basin known for oil shale and spectacular preservation of leaves, vertebrates • Uplifts were eroded almost as fast as they rose, leading to thick sediment deposits (including Badlands of South Dakota) Earth History, Ch. 18

  13. CentralLaramide Earth History, Ch. 18

  14. Late Eoceneerosion surface(Colorado) Laramide uplifts were 2nd phase of Rocky Mtns. Last phase occurred in Neogene time Earth History, Ch. 18

  15. Yellowstone “hot spot” • Absaroka Range of Wyoming/Montana was a site of igneous activity in Paleogene time (and continuing to today) • Volcanic rocks, geysers • Volcanic ash deposits and lavas preserved 27 separate lush Eocene forests Earth History, Ch. 18

  16. Yellowstonepetrifiedforests Earth History, Ch. 18

  17. Yellowstonepetrifiedforests(27 successiveforests preservedin volcanicash beds) Earth History, Ch. 18

  18. Yellowstone“hot spot” Earth History, Ch. 18

  19. Gulf coast sedimentation • Recall that Gulf of Mexico and Arctic Ocean merged during sea level highstand of Cretaceous • Western interior seaway • Gulf of Mexico retreated in Paleogene time, but Gulf Coastal Plain sediments extend up the Mississippi Embayment and reach a thickness of 5 km • Prolific hydrocarbon reservoirs Earth History, Ch. 18

  20. Cretaceous paleogeography Earth History, Ch. 18

  21. PaleogeneGulf Coast sedimentation Earth History, Ch. 18

  22. GulfCoastalPlain prograding siliciclastic coastline Earth History, Ch. 18

  23. Gulf Coastal plain Earth History, Ch. 18

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