Significance of plant remains in redeposited Aptian sediments, Hole 462A, Nauru Basin, to Cretaceous oceanic-oxygenation models ( DSDP).

Abstract

Carbonized plant remains occur in an 80cm-thick section of upper Aptian gray claystones that apparently constitute a raft within the Cretaceous basaltic igneous complex of Hole 462A. The sediments are streaked out, suggesting local redeposition, and the plant remains are concentrated in select laminae. Organic carbon values of the total sediment are around 0.2%. These plant remains comprise the type of degraded organic matter that could readily survive and accumulate in oxygenated water, and hence the Cretaceous oxygen-minimum model for the Pacific remains viable. There is some evidence for a regional change in the type of material deposited from predominantly land-derived higher plant in the Aptian to planktonic in the Albian-Cenomanian. Such a change in the Pacific record, if real, has parallels in the Atlantic Ocean, and may perhaps be a global phenomenon: if so, it defines an important difference between the nature of the Early and Late Cretaceous oceanic anoxic events.-from Authors