Date of Award

1986

Degree Type

Thesis

Degree Name

Master of Science in Oceanography

Department

Oceanography

First Advisor

Margaret Leinen

Abstract

Sedimentation rate data for the late Pleistocene and Holocene was compiled and mapped along with bulk sediment accumulation rate data estimated from the surface calcium carbonate concentration. This data was combined with surface organic carbon and opal (biogenic silica) concentration data in order to calculate the recent rate of accumulation of these biogenically derived sedimentary components. The maps of organic carbon and opal accumulation rates showed similar trends, being highest in known regions of upwelling and high productivity. Annual organic carbon burial was estimated by multiplying the accumulation rate by the areas between the contours and found to be 0.21 x 1014 gC/yr for the deep-sea (pelagic and hemipelagic) and 0.04 x 1014 gC/yr for the shelves exclusive of deltaic sediments. Burial of organic carbon in deltaic sediments is very large, however the necessary data is not available to calculate the burial of organic carbon in all the worlds major river deltas. For this reason an estimate of 1.04 x 1014 gC/yr from Berner (1982) is assumed to be correct for delta deposits, yielding a global organic carbon burial rate of 1.29 x 1014 gC/yr. Organic carbon burial in the most recent Mediterranean sapropel is 0.016 x 1014 and therefore had little or no affect on the global carbon cycle. Glacial versus interglacial organic carbon accumulation is compared at 10 sites, showing glacial rates higher in areas of present upwelling. Organic carbon accumulation rates and organic carbon accumulation rates divided by productivity are plotted versus sedimentation. While correlations were fairly good (r2 = 0.81 and r2 = 0.66, respectively), sedimentation rate data alone is insufficient for estimating organic carbon accumulation.

All available quartz and opal concentrations from deep-sea surface sediments were intercalibrated, plotted, and contoured on a calcium carbonate-free basis. The maps show highest concentrations of opal along the west coast of Africa, along equatorial divergences in all oceans, and at the Polar Front in the southern Indian Ocean. These are all areas here upwelling is strong and there is high biological productivity. Quartz in pelagic sediments deposited far from land is generally eolian in origin. Its distribution reflects dominant wind systems in the Pacific, but in much of the Atlantic and Indian oceans the distribution pattern is strongly modified by turbidite deposition and bottom current processes.

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