Lower Cretaceous foraminiferal biostratigraphy, paleoecology, and depositional environment at DSDP site 397, Leg 47A, North Atlantic.

Abstract

Sedimentologic and ecologic data from the microfossils suggest prodelta shelf depth merging into upper bathyal environments. Benthic foraminifers (such as Quinqueloculina associated with ostracodes and small gastropods and pelecypods) may indicate a nearshore environment in front of a deltaic complex. Epistominids and nodosariids indicate an outer-shelf to upper bathyal environment. However, hedbergellids and a few radiolarian specimens suggest the epipelagic setting of an open-shelf water mass, and can be compared with Recent shelf pelagic biota. Paucity of fauna indicates neither stagnant bottom conditions (pelagic sapropel) nor oceanic depths below the CCD. The barren character of the facies may indicate dilution by the sediments due to continuous terrigenous (cyclic sedimentation) input into the shelf basin. -from Author