Depositional Supersequences Among Cenozoic Strata of U.S. Atlantic Continental Margin: ABSTRACT

Abstract

Integration of outcrop, borehole, and seismic reflection stratigraphy reveals the broad-scale depositional framework of Cenozoic strata of the U.S. Atlantic margin. The principal feature of the framework is a series of depositional supersequences bounded by interregional erosional unconformities that can be traced from coastal plain outcrops to the continental rise. The Atlantic continental margin is divided into five depositional areas: the Salisbury, Albemarle, and Charleston embayments; a composite of the entire Atlantic coastal plain; and a composite of the Atlantic shelf and slope. The major depositional episodes are early and middle Eocene in all depositional areas, late Eocene in all areas except the Albemarle embayment, early Oligocene on the composite shelf and s ope, late Oligocene in all depositional areas but minor in the Salisbury embayment, and early, middle, late Miocene and Pliocene in all areas. Paleoenvironmental and paleo-oceanographic analyses of the sediments and associated fossil assemblages indicate that alternation of major depositional and erosional episodes is controlled chiefly by the relative position of sea level. Thus, the supersequences correlate with the supercycles of the Vail sea level model. The bounding unconformities, in turn, correlate with the major global unconformities of the Vail model. Local variations among such things as terrigenous sediment supply, subsidence rates, and the position of major geostrophic currents, however, may accentuate or diminish the sea level effects. End_of_Article - Last_Page 1445------------