Carbon Isotopes in Deep-Sea Benthic Foraminifera: Precession and Changes in Low-Latitude Biomass

  1. E.T. Sundquist and
  2. W.S. Broecker
  1. Lloyd D. Keigwin1 and
  2. Edward A. Boyle2

Published Online: 18 MAR 2013

DOI: 10.1029/GM032p0319

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

Keigwin, L. D. and Boyle, E. A. (1985) Carbon Isotopes in Deep-Sea Benthic Foraminifera: Precession and Changes in Low-Latitude Biomass, 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/GM032p0319

Author Information

  1. 1

    Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543

  2. 2

    Massachusetts Institute of Technology, Cambridge Massachusetts 02139

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 have been obtained from benthic foraminifera in the North Atlantic (CHN 82 Sta 24 Core 4PC, 42°N, 32°W, 3427 m, 244 kyr) and central equatorial Pacific (KNR 73 Sta 4 Core 3PC, 0°S, 106°W, 3606 m, 410 kyr). These data demonstrate that the North Atlantic site has always been nutrient depleted relative to the Pacific site. Although down-core carbon isotope data in the Atlantic and Pacific reflect changes in deep-ocean circulation patterns, a larger fraction of δ13C variability in both oceans is due to changes in the inventory of continental reduced carbon. The magnitude of this carbon isotope biomass signal is nearly twice as large during oxygen isotope stages 4 and 6 as it is during stage 2. Carbon isotope variability in both oceans contains significant power at the 23-kyr frequency band which is coherent with insolation changes caused by precession of the earth's rotational axis. We propose that this correlation is due to orbitally driven variations in low-latitude biomass, and that the lower amplitude of the carbon isotope signal during the last 60 kyr is due to the reduction in precession parameter amplitude during this period.