Late Quaternary Carbonate Changes in the North Atlantic and Atlantic/Pacific Comparisons

  1. E.T. Sundquist and
  2. W.S. Broecker
  1. Thomas J. Crowley

Published Online: 18 MAR 2013

DOI: 10.1029/GM032p0271

The Carbon Cycle and Atmospheric CO2: Natural Variations Archean to Present

The Carbon Cycle and Atmospheric CO2: Natural Variations Archean to Present

How to Cite

Crowley, T. J. (1985) Late Quaternary Carbonate Changes in the North Atlantic and Atlantic/Pacific Comparisons, in The Carbon Cycle and Atmospheric CO2: Natural Variations Archean to Present (eds E.T. Sundquist and W.S. Broecker), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM032p0271

Author Information

  1. Climate Dynamics Program, National Science Foundation, Washington, D.C. 20550

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

This paper discusses North Atlantic carbonate dissolution fluctuations during the last 400,000 years (oxygen 18 stages 1–11).

Dissolution is inferred based on fluctuations of percent benthonic foraminifera and planktonic foraminiferal fragments. Stratigraphic control is based on percent carbonate fluctuations correlated to oxygen 18 records. A summary of results for the last 400,000 years indicates that (1) North Atlantic dissolution is relatively low during interglacial maximum events and increases with increasing ice volume; however, the relationship between dissolution and ice volume is not linear; (2) the lysocline changed by about 200–300 m in response to the dissolution fluctuations; (3) abyssal regions of the eastern Atlantic have a different dissolution pattern than bathyal regions; (4) comparison of Atlantic and Pacific carbonate dissolution records indicates that sometimes dissolution changes in the two basins are in phase, sometimes out of phase; (5) there is a tendency for a mid-Brunhes (200–450,000 years BP) increase in dissolution intensity in both the Atlantic and the Pacific. Interpretation of the results suggests that out-of-phase dissolution events between the Atlantic and Pacific can be explained in terms of changing deep water production rates. Abyssal/bathyal variations may be due to decreased deep water production rates coupled with increased residence times of deep waters below local sill depth in the eastern basins. In-phase Atlantic/Pacific dissolution events occur during intervals of ice growth. This result implies that shelf/basin transfer of carbon during sea level lowerings is in part responsible for whole-ocean changes in the carbon budget and global carbonate dissolution events. Long-term (100,000 years) changes in dissolution correlate in part with orbital insolation variations. At present, four processes primarily operating on 1,000-year time scales have been identified that may contribute to lower-frequency (100,000 year) dissolution variations: changes in the rate of sea level lowering, global weathering rates, high-latitude carbonate productivity, and the rate of oceanic mixing. The relative importance of these mechanisms has not yet been quantitatively determined.