Turbidites After Ten Years of Deep-Sea Drilling–Wringing Out the Mop?
Kerry Kelts, Michael A. Arthur, 1981. "Turbidites After Ten Years of Deep-Sea Drilling–Wringing Out the Mop?", The Deep Sea Drilling Project: A Decade of Progress, John E. Warme, Robert G. Douglas, Edward L. Winterer
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Deep-sea drilling has provided data on the distribution and changes in composition of redeposited sediment in deep- sea settings through time. The collection of such data by drilling, however, has not been very systematic or purposeful, and has contributed relatively little to the direct understanding of mechanisms of sediment redeposition. A review of reported occurrences of redeposited sediment in DSDP initial reports through Leg 54 shows some temporal patterns: Pleistocene continental margin sequences are thick and dominated by redeposited, relatively coarse-grained terrigenous material, whereas Middle to Upper Eocene and Albian-Cenomanian sequences are characterized by radiolarian turbidites. Moreover, DSDP has recovered an inordinate number of redeposited volcanogenic sequences in the Upper Cretaceous (centered on the Campanian) of all ocean basins and to a lesser extent in the Eocene. These commonly drape the flanks of aseismic rises, ridges, and plateaus and imply episodic volcanism along these features.
Deep Sea Drilling Project cores have also contributed greatly to increasing recognition of the importance of redeposition of large volumes of mud both in fan and non-fan turbidite settings along active and passive margins. Pelagic environments are not devoid of redeposited material; so-called “pelagic turbidites” are common and comprise redeposited pelagic calcareous and siliceous biogenic components derived from the flanks of submarine highs. Redeposited sediments found in DSDP cores have also been extremely important in reconstruction of the tectonic history of numerous features, such as the drowning and demise of Jurassic-Lower Cretaceous carbonate platforms on young passive margins bordering the Atlantic, the destruction and upbuilding of the continental rise along Atlantic margins in the mid-Cenozoic, the history of uplift and volcanism on linear island chains in the Pacific, and the formation and destruction of slope basins along active margins.
With the advent of the Hydraulic Piston Coring system, the future holds promise for more complete documentation of deep-sea fans, a closer examination of controls on timing and frequency of turbidite events, and detailed studies of turbidite physical properties and early diagenesis.
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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.