ABSTRACT

The completeness of the deep-sea stratigraphic record depends upon the balance between sediment supply from biogenic surface production and delivery of detrital sediment across continental margins, and sediment removal by mechanical erosion and/or chemical dissolution. These parameters, in turn, are controlled by a combination of interrelated changes in global sea level, climate, and oceanography. Studies of the rates and patterns of accumulation of both biogenic and detrital sediment in the deep sea, based largely on data from DSDP drill holes, demonstrate that no single factor determines trends in deep-sea sedimentation.

It is tempting to link the global patterns of rise and fall of sea level through time to trends in sedimentation in the oceans. For example, sea level lowstands are expected to result in increased supply of both detrital and chemical (biogenic) sediment to the deep sea. Thus, shelf unconformities, resulting from exposure and erosion of shelf sediments, should correlate with relatively high rates of sedimentation and low incidence of hiatuses in the deep sea. Global sea level highstands would have the opposite effect. The co-occurrence of widespread shelf and deep-sea unconformities, as found in the Oligocene and lower Paleocene contradicts such simple models. These and other examples show that terrigenous and biogenic sediment flux to deep-sea basins is not totally dependent on relative sea level, and that there are commonly significant time lags in the response of deep-sea sedimentation to changes in sea level and shelf sedimentation. Rates of rise and fall of sea level, however, are a major determining factor. Additionally, global and regional climate and overall patterns of oceanic circulation, fertility, and chemistry are equally important in controlling sediment supply to the deep sea and in the development of sedimentary lacunae in deep marine basins.

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