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Archives of global climate change contained in ocean sediments

Archives of global climate change contained in ocean sediments. Ocean sediments as continuous climate archives. Sediments consist of terrigenous material + organic rain + rain of calcite/silicate shells

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Archives of global climate change contained in ocean sediments

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  1. Archives of global climate change contained in ocean sediments

  2. Ocean sediments as continuous climate archives • Sediments consist of terrigenous material + organic rain + rain of calcite/silicate shells • Sedimentary rain not derived from rocks is produced primarily by marine organisms (shells and excrement) • Sedimentation rates range from almost nil to 10-20 cm/kyr

  3. Microscope view ofrinsed seafloor sediment

  4. Archer D.E., 1996

  5. Marine paleothermometers • Foraminiferal abundance • Sediment chemistry (Alkenones) • Coral chemistry • δ18O, Sr/Ca • Chemistry of foraminifera • δ18O, Mg/Ca

  6. Oxygen Isotopes • For every 500 water molecules in the sea, one bears the heavy isotope 18O • In a variety of earth substances, the ratio of heavy oxygen atoms (18O) to light oxygen atoms (16O) varies from this 1/500 ratio by several percent • For example, marine CaCO3 has ~4% more heavy oxygen than seawater, while Antarctic snow has ~4% less heavy oxygen than seawater From “The Glacial World According to Wally”, 2002

  7. Bemis et al., 1998

  8. Data from Lea et al., (2000) presented in Wally

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