Neogene marine microfossil biofacies of the Western North Atlantic

Abstract The western North Atlantic Ocean was one of the first areas to be explored by the Deep Sea Drilling Project (DSDP; Leg 1, 1968). Subsequently, Glomar Challenger returned for 17 additional Legs (2,4,11,12,37, 39,43,44,45,49,51,76,78,82,93, 94, 95; Fig. 1). In addition to deep-sea drilling, more than 200 gravity and piston cores, collected mostly by the Lamont- Doherty Geological Observatory, have sampled Neogene sediments in the western North Atlantic (Fig. 2). In the shallower water of the continental shelf, more than 100 boreholes have sampled the Neogene sedimentary section (Ascoli, 1976; Poag 1978,1985, inScholle, 1982; and Poag inScholle and Wenkam, 1982; Hathaway and others, 1979; Barss and others, 1979; see Fig. 1). This paper summarizes microfossil biofacies data chiefly from DSDP Sites as published in the Initial Reports of that project. At the time of writing, detailed data from DSDP Legs 78, 82,93,94, and 95 had not yet been published. The Initial Reports data are supplemented by a few key published syntheses. Temporal and spatial composition and distribution of deep-sea zoo- planktonic, phytoplanktonic, nektonic, and benthic biofacies (sediment assemblages) are briefly discussed and compared with data from North American continental margin sites (Fig. 1). We point out the relationships of the composition and distribution of biofacies to paleoclimates, paleoceanography, sea-level changes, and sedimentary processes. Using a narrow definition of the term Neogene, we limit our discussion to Miocene and Pliocene microfossils. For a dicussion of Quaternary microfossils, the reader should