Traction structures in deep-marine, bottom-current-reworked sands in the Pliocene and Pleistocene, Gulf of Mexico

;
• Spalding, T. D.
;
• Rofheart, D. H.

Abstract

The Pliocene-Pleistocene sequence cored in the Ewing Bank and Garden Banks areas in the Gulf of Mexico provides an example of deep-marine sand reworked by bottom currents. A distinctive attribute of these sands is their traction structures, which include cross-stratification, current ripples, and horizontal lamination. These sands also exhibit sharp upper contacts, inverse size grading, mud offshoots, and flaser bedding. An important aspect of these structures is their occurrence in discrete units, but not as part of a vertical sequence of structures, such as the Bouma sequence. Presumably, the Loop Current, a strong, wind-driven surface current in the Gulf of Mexico, impinged on the sea bottom, as it does today, and resulted in bottom-current-reworked sands. A depositional model is proposed in which the bottom-current-reworked sands tend to develop a facies in interchannel slope areas that is distinctly different from channel-levee turbidite facies.