Carbonate Preservation and Rates of Climatic Change: An 800 KYR Record from the Indian Ocean

  1. E.T. Sundquist and
  2. W.S. Broecker
  1. L. C. Peterson and
  2. W. L. Prell

Published Online: 18 MAR 2013

DOI: 10.1029/GM032p0251

The Carbon Cycle and Atmospheric CO: Natural Variations Archean to Present

The Carbon Cycle and Atmospheric CO: Natural Variations Archean to Present

How to Cite

Peterson, L. C. and Prell, W. L. (1985) Carbonate Preservation and Rates of Climatic Change: An 800 KYR Record from the Indian Ocean, in The Carbon Cycle and Atmospheric CO: Natural Variations Archean to Present (eds E.T. Sundquist and W.S. Broecker), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM032p0251

Author Information

  1. Department of Geological Sciences, Brown University, Providence, Rhode Island 02912

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 1985

ISBN Information

Print ISBN: 9780875900605

Online ISBN: 9781118664322

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Keywords:

  • Carbon cycle (Biogeochemistry)—Congresses;
  • Atmospheric carbon dioxide—Congresses;
  • Geological time—Congresses;
  • Paleothermometry—Congresses;
  • Geology, Stratigraphic—Congresses

Summary

In the eastern equatorial Indian Ocean, a foraminiferal-based Composite Dissolution Index (CDI) identifies the present level of the lysocline (3800 m) and reflects the modern carbonate saturation gradient in the water column. Piston cores from water depths of 2900 to 4400 m on the Ninetyeast Ridge at 6°S provide an 800 kyr record of bathymetric and temporal variations in carbonate preservation as measured by the CDI. Dissolution of carbonate is out of phase with glacial-interglacial δ18O cycles. Cross-spectral analysis reveals high coherency (>0.85) between the CDI, the δ18O record, and its derivative over the 100 kyr and 41 kyr Milankovitch frequencies, indicating a simple linear response of overall dissolution intensity to climate change. Variations in preservation are proportional to and in phase with maximum rates of change in the δ18O record, suggesting a rapid response of the local carbonate system to climatic forcing. Both the Broecker shelf deposition model and circulation models calling for changes in the production or chemistry of deep waters provide plausible mechanisms for explaining the observed dissolution patterns. However, the lack of a well-defined precessional (23 and 19 kyr) response in the CDI and loss of coherency with δ18O over the same frequencies tends to favor a circulation explanation, as strict interpretation of a shelf model would require coherency at all of the dominant Milankovitch periods. Alternatively, shelf-basin carbon inventory models may be too simple and may produce a nonlinear response in the deep sea carbonate reservoir for small changes in sea level.