Potential Errors in Estimates of Carbonate Rock Accumulating Through Geologic Time

  1. E.T. Sundquist and
  2. W.S. Broecker
  1. William W. Hay

Published Online: 18 MAR 2013

DOI: 10.1029/GM032p0573

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

Hay, W. W. (1985) Potential Errors in Estimates of Carbonate Rock Accumulating Through Geologic Time, 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/GM032p0573

Author Information

  1. Museum, University of Colorado, Boulder, Colorado 80309

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

One of the arguments for changes in atmospheric CO2 on geologic time scales rests on consideration of the rates of accumulation of carbonate rock through time. Estimates of the volumes of different rock types, including carbonate, deposited over geologic time have generally assumed that sedimentary rocks can be divided into three major assemblages, one characteristic of platform areas, another characteristic of geosynclines, and a third characteristic of pelagic sediment. The latter assemblage is frequently omitted from the estimate computations. While it may be reasonable to assume that shelf sediments beneath the sea are probably similar to the platform sediments exposed on land, it may be unreasonable to expect that the same proportions of sediment types can be extrapolated to the deposits of the slope and rise. Cratonic sediments form about 14% of the sedimentary mass, passive margin shelf sediments 8%, and passive margin slope and rise sediments 24%. Because the mass of slope and rise sediments is larger than that of cratonic and shelf sediments, there may be significant errors in estimates of total mass of carbonate rock formed at a given time. Passive margin slope and rise areas may be carbonate sinks early in their development and may exclude carbonate later in their development. The apparent ratio of clastics to carbonates accumulating at any time might also vary significantly according to the overall composition of the slope and rise deposits. The apparent decline in rate of accumulation of carbonate since the Mesozoic is in part a function of the shift in site of deposition of carbonate from solely shallow water environments to both shallow and deep water environments as a result of the development of the oceanic calcareous plankton.