Bathymetry and Sediments of Bay of Campeche, Gulf of Mexico: ABSTRACT

Abstract

During February and March, 1957, the Department of Oceanography and Meteorology, Agricultural and Mechanical College of Texas, conducted a cruise to the Bay of Campeche. Twenty-nine cores and one grab sample were collected at 30 stations. Approximately 1,5000 nautical miles of sounding tract was accomplished. The sediment and bathymetric data indicate that the area can be subdivided into three broadly defined sedimentary and geomorphic provinces: (1) Western Bay, separated from the Southern Bay by a deep-water re-entrant of the Gulf of Mexico centered along 95° W. Longitude; (2) Southern Bay, separated from the Eastern Bay by Campeche Canyon; and (3) Eastern Bay. The concave upper part and step-like lower part of the continental slope in the Western Bay suggest that the slope is structurally controlled and little modified by sedimentation. The convex upper part and highly irregular lower part of the continental slope in the Southern Bay suggest that the topography of the slope is the result of the behavior of unstable sediment under stress, as Gealy (1955) suggested for the topography of the Northwest Gulf of Mexico. It was not possible to shed new light on the origin of the continental slope off Campeche Bank in the Eastern Bay. The sediments from the Western and Southern Bay were found to be composed mainly of clastic material which grades sharply seaward from sands near shore to silts and clays on the continental slope. The CaCO3 content of the surface sediments increases seaward because of a relative increase in the quantity of Foraminifera and decrease in the quantity of clastic material. The clay mineral type changes seaward from dominantly kaolinite-illite on the continental shelf to dominantly montmorillonite on the continental slope. Calcareous sediments dominate the Eastern Bay Campeche Bank. Conclusive evidence of sediment displacement was found in cores from Campeche Canyon, and evidence suggesting sediment displacement was found in cores from the deep-water re-entrant between the Wester and Southern Bay. End_of_Article - Last_Page 1781------------