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Archives of global climate change contained in ocean sediments

Ocean sediments serve as continuous climate archives, consisting of terrigenous material, organic rainfall, and calcite/silicate shells. Deposits form from marine organisms, with sedimentation rates varying. Microscopic views reveal marine paleothermometers such as foraminifera abundance, sediment chemistry, coral chemistry, and oxygen isotopes. Heavy isotope 18O ratios in substances differ, impacting marine CaCO3 and Antarctic snow. Explore the glacial world's history through Wally's insights, incorporating data from Bemis et al. (1998) and Lea et al. (2000).

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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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