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Cenozoic

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Cenozoic

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Presentation Transcript

  1. Cenozoic Tectonics Climate

  2. The Himalayas

  3. The Closing of the Tethys

  4. As the World Warms:65 Million Years of Hot and Cold

  5. As the World Warms……. • The Geologic Evidence • The Heartbeat of Climate • The Present and Future

  6. The Geologic Evidence • Paleontological and Paleobotanical Remains

  7. The Arctic Environment

  8. The Arctic Environment

  9. The Geologic RecordEllesmere Island

  10. Ellesmere Island 50 MaMary Dawson of the Carnegie Museum with ~50 million year old fossil of an alligator http://www.post-gazette.com/magazine/20000319dawson1.asp

  11. Is this Possible?

  12. Eocene Forests in the Arctic Metasequoia stumps atAxel Heiberg Is. http://www.sas.upenn.edu/earth/arctic/data.html

  13. Metasequoia stumpsAxel Heiberg Is.

  14. Eocene Fossils from WyomingCrocodile SycamoreBorealosuchusPlatanus wyomingensis

  15. The Arctic Then Now

  16. The Geologic Evidence • Paleontological and Paleobotanical Remains • Marine Records • Large Geographic Coverage - 70% of Earth • Net Repository of Sediments • Continuous recorder climate change • Heat Transport and Carbon Storage

  17. The Oxygen Isotope Recorder • Stable Isotopes of Oxygen • 16O = 99.76% • 17O = 0.04% • 18O = 0.20%

  18. Stable Oxygen Isotopes 18O/16Osam - 18O/16Ostd 18O ‰ = ____________________________ * 1000 18O/16Ostd

  19. Stable Oxygen Isotopes • Paleo-temperature Equation T°C = 16.9-4.2*(18OCaCO3- 18Owater )+0.1*(18OCaCO3- 18Owater )2

  20. Stable Oxygen Isotopes Changes in 18Ocalcite 18Ocalcite = -0.23 * T°C 18Ocalcite = 18Owater

  21. Temperature EffectGalapagos SSTs and Coral 18O

  22. The 18Owater Effect Ice Volume ~ 1‰ for 100 m of sea level equivalent

  23. The Hot House to Ice House Transition • Greenhouse gases • Thermohaline circulation • Continental Configurations

  24. Greenhouse gases

  25. What caused the pCO2 to change? • High pCO2 during early Eocene could have resulted from: • Seafloor spreading changes • Large-scale volcanism

  26. High pCO2 during early Eocene • Large-scale volcanism • Giant’s Causeway in N. Ireland • Early Tertiary age

  27. Decreasing pCO2 after ~50 Ma

  28. Decreasing pCO2 after ~50 Ma • Collision began ~50 Ma • Increased weathering = Atm. CO2 decrease • CaSiO3 + CO2 = CaCO3 + SiO2

  29. Himalayan Mountains • Broad Tibetan plateau • 3 miles above sea level

  30. Himalayan Mountains • Indian craton collided with Eurasia

  31. Himalayan Mountains • Miocene clastic sediments overlying Eocene limestone • Most uplift during last 15 million years

  32. Himalayan Mountains • Indian plate subducted • Continental collision • Fold and thrust belt • Modern motion along main boundary fault

  33. Neogene Life • Isolation of Antarctica led to glaciation • Global cooling

  34. Drake Passage Opening33 Ma - Thermal Isolation of AntarcticaAntarctic Glaciation

  35. The Ice Age • Glacial Maximum • Extent of continental glaciation • Six lines of evidence • Erratic boulders

  36. The Ice Age • 2. Glacial till and basins associated with glaciation • 3. Depression of the land • Hudson Bay

  37. The Ice Age • Glacial scouring • Lower parts of mountains of northeast U.S. are smooth • Tops were not scraped by ice sheets

  38. The Ice Age • Lowering of sea level • Exposed continental shelves

  39. The Ice Age • Migration of species • Mammals crossed Bering Strait on land corridors • Vegetation changed in response to global changes

  40. The Ice Age • Pollen • Reconstruct vegetation changes • European changes

  41. The Ice Age • Chronology of glaciation • Oxygen isotope ratios of foraminiferan skeletons in sediments • Oceans are enriched in 18O during glaciations • Northern Hemisphere glaciation began ~3M years ago • Full Ice Age 2.5 M years ago

  42. Regional Events–Caribbean • Caribbean plate isolated

  43. The Ice Age • Ocean circulation changed during glaciation • Glacier in NJ • Tundra in Washington, D.C.

  44. The Ice Age • Why did the glaciation start? • Isthmus of Panama • Emplaced 3.5–3 M years ago • Started modern circulation • Gulf stream carries salty Atlantic north • Cools, sinks • Oceanic conveyor belt • High latitudes cool