Revised age calibrations for the Eocene/Oligocene boundary of ODP Site 199-1218, supplement to: Coxall, Helen; Wilson, Paul A; Pälike, Heiko; Lear, Caroline H; Backman, Jan (2005): Rapid stepwise onset of Antarctic glaciation and deeper calcite compensation in the Pacific Ocean. Nature, 433, 53-57

The ocean depth at which the rate of calcium carbonate input from surface waters equals the rate of dissolution is termed the calcite compensation depth. At present, this depth is ~4,500 m, with some variation between and within ocean basins. The calcite compensation depth is linked to ocean acidity...

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Bibliographic Details
Main Authors: Coxall, Helen, Wilson, Paul A, Pälike, Heiko, Lear, Caroline H, Backman, Jan
Format: Dataset
Language:English
Published: PANGAEA - Data Publisher for Earth & Environmental Science 2005
Subjects:
Datum level
DEPTH, sediment/rock
Age model, optional
Age model
Age, error
Composite Core
Leg199
Joides Resolution
Ocean Drilling Program ODP
Antarctic
Kennett
Pacific
Pollard
Shackleton
Antarc*
Antarctica
Ice Sheet
Online Access:https://dx.doi.org/10.1594/pangaea.769838
https://doi.pangaea.de/10.1594/PANGAEA.769838
Description
Summary:The ocean depth at which the rate of calcium carbonate input from surface waters equals the rate of dissolution is termed the calcite compensation depth. At present, this depth is ~4,500 m, with some variation between and within ocean basins. The calcite compensation depth is linked to ocean acidity, which is in turn linked to atmospheric carbon dioxide concentrations and hence global climate (Broecker and Peng, 1987). Geological records of changes in the calcite compensation depth show a prominent deepening of more than 1 km near the Eocene/Oligocene boundary (~34 million years ago) (van Andel, 1975, doi:10.1016/0012-821X(75)90086-2) when significant permanent ice sheets first appeared on Antarctica (Kennett and Shackleton, 1976, doi:10.1038/260513a0; Miller et al., 1991, doi:10.1029/90JB02015; Zachos et al., 1996, doi:10.1029/96PA00571; Lear et al., 2000, doi:10.1126/science.287.5451.269), but the relationship between these two events is poorly understood. Here we present ocean sediment records of calcium carbonate content as well as carbon and oxygen isotopic compositions from the tropical Pacific Ocean that cover the Eocene/Oligocene boundary. We find that the deepening of the calcite compensation depth was more rapid than previously documented and occurred in two jumps of about 40,000 years each, synchronous with the stepwise onset of Antarctic ice-sheet growth. The glaciation was initiated, after climatic preconditioning (DeConto and Pollard, 2003, doi:10.1038/nature01290), by an interval when the Earth's orbit of the Sun favoured cool summers. The changes in oxygen-isotope composition across the Eocene/Oligocene boundary are too large to be explained by Antarctic ice-sheet growth alone and must therefore also indicate contemporaneous global cooling and/or Northern Hemisphere glaciation. : Sediment depth is given in rmcd. Eocene-Oligocene boundary CK95/BKSA95 age = 33,7 Ma, revised to 33,9 Ma for ODP Site 119-1218.

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