Lower Oligocene ice-rafted debris on the Kerguelen Plateau: evidence for East Antarctic continental glaciation

Abstract

Appreciable lower Oligocene clastic detritus interpreted to be ice-rafted debris (IRD) was recovered at Ocean Drilling Program (ODP) Site 748. The physiologic and tectonic setting of the site and the coarse size of the material rule out transport of the clastics by turbidity currents, nepheloid layers, or wind. The co-occurrence of the IRD, biosiliceous-rich nannofossil ooze, fish skeletal debris, and glauconite probably denotes changes in patterns and/or intensity of oceanic circulation associated with a profound climatic cooling. These changes apparently enhanced upwelling and surface-water productivity and the development of a trophic structure that supported abundant vertebrate marine life, perhaps an important step in the evolution of vertebrate marine faunas. -from Authors