Abstract

Pelagic carbonate and Volcaniclastic sediments from Sites 288 and 289 on the Ontong-Java Plateau show evidence of resedimentation by turbidity and ocean bottom currents. The evidence includes sedimentary structures, the admixing of pelagic-derived carbonate sediment with Volcaniclastic sediment, and the arrangement of these two sediment types into a sequence. Sedimentary structures include current ripples preserved as wavy beds, micro-cross-laminae, clay drapes, flaser bedding, lenticular bedding, and parallel lamination.

The sequence consists of a basal scour overlain by graded, fresh volcaniclastic siltstone, resedimented limestone containing locally derived components interbedded with altered volcanic ash, and pelagic limestone consisting of nannofossils. The resedimented limestone contains parallel laminae, current ripples, clay drapes, and lenticular, flaser, and wavy bedding. The graded siltstone was deposited by turbidity currents, whereas the limestone was resedimented by ocean currents characterized by alternating phases of bedload or suspension sedimentation of either tidal or longer termed periodicity. Partial sequences consisting of combinations of any two of these three sediment types are common to the Ontong-Java Plateau and haye been described from other deep ocean settings.

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