13. Paleoclimate - Paleoclimatology History of Climate...

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Unformatted text preview: Paleoclimatology History of Climate Change History of climate through time recorded in the sedimentary rock record Sediments frequently deposited in water - ocean Proxies- data that is inferred from other evidence rather than measured directly Qualitative vs. quantitative Proxies Qualitative Distribution of rock/sediment types: Corals/Reefs Warm (>20C), shallow (light), clear water (symbionts) Evaporites Aridity (evaporation > precipitation) Glacial Till Reef/Evap Distribution Today Reefs Evaporites Species Diversity Pangaea Super continent all lands ~300 to 175 Ma (Permian) Evaporites Through Time Gordon, 1975 Area covered by evaporites through time Pangea Climate through Time Frakes, 1979 Icehouse Icehouse Icehouse Greenhouse Greenhouse Greenhouse Proxies Distribution of Fauna/Flora Certain plants and animals live in specific conditions Reefs Alligators on Elsmere Island (north of Arctic circle) in Cretaceous Breadfruit in northern high latitudes in the Paleocene Left vs. right coiling foraminifera in the Pleistocene Geologic Record Dott and Prothero, Evolution of the Earth Some marine sediments currently on land Long-term record of marine sediments in the ocean * oldest crust ~200 My Integrated Ocean Drilling Program International consortium Operates the JOIDES Resolution Drills deep sea sediments and ocean crust Age of the Seafloor Integrated Ocean Drilling Program From ODP TAMU http://joidesresolution.org/node/218 Video of coring operation Integrated Ocean Drilling Program DSDP 1968-1975 ODP 1985-2003 IODP 2003-2013 Ocean Drilling ODP Leg 198- Paleocene Thermal Max Geochemical Proxies Qualitative studies Using the chemistry of the sediments to learn about conditions in the past Oxygen isotopes- temperature and ice volume Nd isotopes- ocean circulation Isotopes Isotope- atoms of an element that have the same number of protons (defines element), but different numbers of neutron #protons + #neutrons = mass Mass dependent fractionation Periodic Table of the Elements Oxygen Isotopes Oxygen has 3 isotopes #protons #neutrons isotope 8 8 8 8 9 10 Cooler More ice Oxygen Isotopes Oxygen has 3 isotopes #protons #neutrons isotope 8 8 8 8 9 10 16 O 17 O 18 O 16 O = 99.76% 17 O = 0.04% 18 O = 0.2% (500 atoms of 16 O for every atom of 18 O ) Differences in mass are great enough to make the atoms behave differently during physical and chemical processes Oxygen Isotopes Oxygen Isotopes Measure ratio of the two most abundant 18 O/ 16 O Notation [ 18 O/ 16 O sample- 18 O/ 16 O standard ] 18 O = 18 O/ 16 O standard * 1000 Stable isotope Mass Spectrometer Calcite shells (foraminifera) = CaCO 3 Oxygen Isotopes Seawater: H 16 OH H 18 OH H 17 OH CaC 16 O 16 O 16 O CaC 16 O 16 O 18 O Ratio in the foram CaCO 3 reflects the ratio in the seawater Differences in mass different physical behavior Two physical processes: 1. Evaporation1....
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13. Paleoclimate - Paleoclimatology History of Climate...

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