Paleoenvironmental Implications of Oceanic Carbonate Sedimentation Rates
Thomas A. Davies, Thomas R. Worsley, 1981. "Paleoenvironmental Implications of Oceanic Carbonate Sedimentation Rates", The Deep Sea Drilling Project: A Decade of Progress, John E. Warme, Robert G. Douglas, Edward L. Winterer
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Global land-sea carbonate flux for the past 60 m.y. averages 10.3-12.5 × 1014 g/y, surprisingly close to 12.2 × 1014 g/y calculated using data from today's rivers. However, oceanic carbonate accumulation rates vary between 7.8 × 1014 g/y and 28.6 × 1014 g/y, a factor of four. Furthermore carbonate accumulation oscillates between periods of high (0-6, 22-30, 45-53 m.y.) and low deposition. Prior to 30 m.y.BP all oceans behaved in concert, but since then significant partitioning between the Pacific and Atlantic-Indian oceans has complicated the picture. Prior to 15 m.y.BP the Pacific consumed two-thirds of the total pelagic carbonate, but since that time has never consumed more than 50 percent of the total, and for the past 3 m.y. only 38 percent. This trend is related to hypsometry and changes in carbonate dissolution rates as well as to changes in relative size of the oceans resulting from seafloor spreading.
Global carbonate flux through time appears to be simply related to changing land-sea ratios as calculated from sea level curves. In this system, maximum exposed continental area correlates with high pelagic carbonate flux. Deviations from this simple relationship are attributable to changes in carbonate production-dissolution ratios, latitudinal hypsometric differences, global climatic changes, and biases introduced by the simple averaging techniques used in the calculations.
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At the present the Glomar Challenger has drilled over 500 holes over the world ocean, involving hundreds of scientists from dozens of countries. This volume is intended as a review of some of theimportant results from the most comprehensive, ambitious and successful earth-bound geologic project ever undertaken. The symposium upon which this volume originated was held April 4, 1979 at the SEPM/AAPG Annual Meeting in Houston. No comprehensive synthesis of all aspects of the DSDP has appeared, and the topic coverage in this volume is biased towards the sediments and fossils, and their significance for certain aspects of earth history – paleogeography, bathymetry, climatology, oceanography, ecology, environments – all in keeping with the audience of sedimentary geologists.