Neogene stratigraphy of the submerged U.S. Atlantic margin

Abstract

Thirty boreholes and several hundred sea-floor samples provide a detailed but incomplete record of Neogene strata and depositional environments along the submerged part of the United States Atlantic margin. Three major sedimentary basins, the Blake Plateau Basin, the Baltimore Canyon Trough, and the Georges Bank Basin, contain Neogene sedimentary prisms as thick as 1200 m, comprising bathyal marine to nonmarine strata. Middle Miocene rocks compose the most widely represented and thickest unit (> 600 m in the Baltimore Canyon Trough). Calcareous microfossils provide excellent biostratigraphic and paleoenvironmental indicators except in some sparsely fossilferous shallow-water intervals and where shallow-water diatomaceous assemblages predominate. However, in outer sublittoral assemblages of the Blake Plateau Basin and Baltimore Canyon Trough, the co-occurrence of abundant diatoms, radiolarians, and planktic foraminifera provide an excellent opportunity for intercalibration of biozones. Preliminary correlations between chronostratigraphic and paleoenvironmental interpretations indicate a close association of depositional sequences with sea-level fluctuations, but some local exception persist.