Carbon Isotope Variations in Surface Waters of the Gulf of Mexico on Time Scales of 10,000, 30,000, 150,000 and 2 Million Years

  1. E.T. Sundquist and
  2. W.S. Broecker
  1. Douglas F. Williams

Published Online: 18 MAR 2013

DOI: 10.1029/GM032p0329

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

Williams, D. F. (1985) Carbon Isotope Variations in Surface Waters of the Gulf of Mexico on Time Scales of 10,000, 30,000, 150,000 and 2 Million Years, 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/GM032p0329

Author Information

  1. Department of Geology, University of South Carolina, Columbia, South Carolina 29208

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

Detailed carbon isotope records from surface-dwelling planktonic foraminifera appear to represent δ13C variations in the surface ocean mixed layer of the Gulf of Mexico on different time scales. Correlation of late Pleistocene planktonic δ13C records from the Gulf of Mexico, Panama Basin and southeast Indian Ocean suggests that the surface water δ13C record monitors global changes in the carbon cycle, perhaps changes in atmospheric CO2 levels, and not local effects due to variations in productivity or water temperature. Variations in δ13C of 0.5°/oo occur with a frequency of <500 years in the Holocene and may record background variations in atmospheric pCO2. The meltwater effect on the δ13C of surface waters is largest during the most rapid portion of the deglaciation from isotope stage 2 into stage 1 (from approximately 17 to 12.5 kybp). On time scales representing the last 150,000 years, the most prominent negative δ13C excursion begins in late stage 6 and culminates in the earliest part of isotope stage 5e, a time representing the warmest global temperatures and highest sea levels of the last 150 ky B.P. Major changes in the benthic δ13C record may lead those in the planktonic δ13C record by as much as 10,000 years, but more work is needed to fully explore this observation. A small but significant offset of −0.3°/oo occurs at 900 ky B.P. in the δ13C records of the Gulf of Mexico (E67-135) and Caribbean (DSDP Site 502B (Prell, 1982)), in good agreement with the positive 18O stepwise shift observed in globally distributed DSDP records.