Biostratigraphy, lithofacies and paleoenvironments of the Gulf 718-1 well, U.S. Mid-Atlantic Outer Continental Shelf

Abstract

The Gulf 718-1 well, located on the southwestern flank of the Schlee Dome, was drilled to a total depth of 3905 m. The oldest sedimentary rocks sampled were not fossiliferous, but are probably of Late Jurassic age. Sandstones and siltstones are the dominant lithologies except in the intervals between 1213 to 1450 m and 1993 to 2259 m where carbonates make up a major part of the section. Calcite is the primary cement throughout the section; chert, siderite, diagenetic clay and dolomite are locally important. The well contains coaly, gas-prone potential source rocks of Neocomian age, but these strata are only marginally mature for oil. The paleoenvironments recorded in the strata represent a general upward progression from nonmarine to marginal marine to neritic depositional conditions. These paleoenvironments are more marine than the stratigraphically equivalent sedimentary regimes of the New Jersey coastal plain to the west, but are generally more terrestrial than the paleoenvironments recorded in wells drilled seaward to the east.