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Geology topics

R.E. Hall

Publications and source records attributed to R.E. Hall.

3 recordsLinked to original sources

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

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. ?? 1990.

U.S. Mid-Atlantic Outer Continental Shelf↗

Formation of the Shelf-edge Cretaceous-Tertiary contact off the southeastern U.S. Coast

Submarine erosion, associated with changes in position of the proto-Gulf Stream, was the dominant mechanism controlling the formation of the Cretaceous-Tertiary unconformity in AMCOR borehole 6004. Paleontologic evidence indicates that this unconformity, which is marked by a gravelly-sand enriched in glauconitic and phosphoritic concretions, represents a hiatus of about 7 m.y. Both Cretaceous and Paleocene sediments contain middle-outer neritic foraminiferal assemblages that become more diverse with distance from the contact. Of the elemental abundances measured, Al, Ba, Co, Fe, Ga, K, Mg/Ca, Mo, Ni, P, Sr/Ca, V, Y, and Zn show a strong positive correlation with proximity to the contact, probably as a result of the concentration of authigenic and heavy minerals present as lag sediments on the erosion surface.

Florida, Georgia, South Carolina↗