HR: 08:00h
AN: V41H-01    [Abstracts]
TI: Phanerozoic sea level, ice volume, and carbon dioxide
AU: * Miller, K G
EM: kgm@rci.rutgers.edu
AF: Rutgers University, Department of Geological Sciences, Piscataway, NJ 08854 United States
AU: Kominz, M A
EM: michelle.kominz@wmich.edu
AF: Western Michigan University, Department of Geosciences, Kalamazoo, MI 49008 United States
AU: Browning, J V
EM: jvb@rci.rutgers.edu
AF: Rutgers University, Department of Geological Sciences, Piscataway, NJ 08854 United States
AU: Wright, J D
EM: jdwright@rci.rutgers.edu
AF: Rutgers University, Department of Geological Sciences, Piscataway, NJ 08854 United States
AU: Katz, M E
EM: mimikatz@rci.rutgers.edu
AF: Rutgers University, Department of Geological Sciences, Piscataway, NJ 08854 United States
AB: We review sea-level changes over the past 543 m.y. and present a new sea-level record for the last 100 m.y. Variations in ocean crust production caused sea-level changes of 100-300 m on the 10 to 100 m.y. scale; changes on this scale were smaller than previously inferred, with a Late Cretaceous peak of 100±50 m, implying smaller changes in seafloor spreading rates. Ice-volume variations controlled sea-level changes of ~30-80 m on the 1-5 m.y. scale over at least the past 100 m.y. and changes of 30-120+ m on the "Milankovitch" scale for the past 2.5 m.y. Sea-level changes mirror δ¹⁸O variations on various scales. Such covariance can be explained by ice-volume changes in concert with temperature changes on the m.y. and k.y. scales, but a long-term δ¹⁸O increase of ~4-5‰ since 50 Ma must be primarily attributed to deep-water cooling (15°C overall), rather than to ice storage. The link between sea level and temperature on the 10 m.y. scale cannot be due to cooling alone because this steric effect would explain only ~15 m of eustatic fall since 50 Ma. The link between δ¹⁸O and sea-level variations on the 10-100 m.y. scale must be due to tectonics though carbon dioxide, as indicated by a covariance of long-term sea level, δ¹⁸O, and CO₂ proxies. Over the past 100 m.y, sea-level changes reflect global climate evolution from a time of ephemeral Antarctic ice sheets (100-33 Ma), through a time of large and variable Antarctic ice sheets (33-2.5 Ma), to a world with large Antarctic and large, variable Northern Hemisphere ice sheets (2.5-0 Ma). Though long-term thermal evolution generally follows CO₂ and parallels sea-level changes, sharp changes to cooler climatic states occurred in the earliest Maastrichtian, across the Eocene/Oligocene boundary, in the middle Miocene, and in the mid-Pliocene.
DE: 0726 Ice sheets
DE: 1030 Geochemical cycles (0330)
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1621 Cryospheric change (0776)
DE: 4901 Abrupt/rapid climate change (1605)
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005