Gradual Late Pliocene onset of glaciation: a deep-sea record from the Northeast Atlantic
Abstract A detailed analysis of planktonic foraminifera assemblages and benthic oxygen isotope values from the Late Pliocence of DSDP Site 548 in the Northeast Atlantic shows that the initiation of Northern Hemisphere glaciation developed gradually, through a series of cycles. These results contrast with those of other DSDP Sites which indicate constant paleoclimatic conditions preceding the sudden, step-wise, development of glaciations at 2.4–2.5 m.y. The difference between these sites and Site 548 might be explained by broad sampling interval and breaks in the sedimentary sequence which obscure the onset of Late Pliocence glaciation at those locations where it appears to occur in a step-wise fashion. The results from Site 548 indicate that the development of Northern Hemisphere glaciation could be regarded as part of a progressive climatic deterioration rather than a geologically sudden paleoclimatic event.