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The Cenozoic Era. Ma. 1.8. 5.0. 23.7. 33.5. 54.5. 66.4. Major themes of the Cenozoic. Earth overall climatic cooling (“greenhouse to icehouse”) changes in ocean circulation Pangea breakup continues but slows changes in position of land and sea changes in oceanic nutrient levels Life
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The Cenozoic Era Ma 1.8 5.0 23.7 33.5 54.5 66.4
Major themes of the Cenozoic • Earth • overall climatic cooling (“greenhouse to icehouse”) • changes in ocean circulation • Pangea breakup continues but slows • changes in position of land and sea • changes in oceanic nutrient levels • Life • diversification and dominance of mammals • dominance of angiosperms • continuation of the Mesozoic Marine Revolution
The Earth in the Cenozoic • Changes in position of land and sea • destruction of Tethys • effects on climate • effects on ocean circulation • land bridges • Changes in ocean circulation • cooling more vigorous circulation • continental position new current patterns • Overall climatic cooling • continental position S. Hemisph. glaciation
The Deep Sea Drilling / Ocean Drilling Project (DSDP/ODP) JOIDES Resolution Glomar Challenger
Oxygen isotope paleothermometry • O isotope fractionation is temperature-dependent (warmer temps more 16O, less 18O) • expressed as ppt relative to PDB (Pee Dee Belemnite) • need to correct for ice volume (more glacial ice SW enriched in 18O)
Oxygen isotope paleothermometry 18O negative = warmer 18O positive = cooler
Major climate events of the Cenozoic • Late Paleocene Thermal Maximum (LPTM) • Eocene-Oligocene cooling / Antarctic glaciation • Miocene cooling • Pleistocene glaciation
Possible cause(s) for the LPTM more hydrothermal activity more CO2 warming release of methane clathrates more CO2 warming
Major climate events of the Cenozoic • Late Paleocene Thermal Maximum (LPTM) • Eocene-Oligocene cooling / Antarctic glaciation • Miocene cooling • Pleistocene glaciation
The breakup of Gondwanaland:the death of Tethys and the formation of the Circumantarctic Current • India collides with southern Asia (ca. 55 Ma) • Australia separates from Antarctica (ca. 58 Ma) • South America separates from Antarctica -- the Drake Passage (33.5-23.5 Ma)
Major climate events of the Cenozoic • Late Paleocene Thermal Maximum (LPTM) • Eocene-Oligocene cooling / Antarctic glaciation • Miocene cooling • Pleistocene glaciation
Miocene Eocene
An artist's rendering of Rodhocetus. This mammal lived near the shores of the Tethys Sea, between Asia and the South Asian subcontinent, about 47 million years ago.