Abstract: Areal Distribution of Clay Minerals and Their Relation to Physical Properties, Gulf of Mexico

W. E. Hottman, W. R. Bryant

This study describes the distribution of clay minerals in the Gulf of Mexico. The samples are from 37 piston and gravity cores obtained on cruises of the R/V Alaminos between 1965 and 1970. Because the cores are from all major physiographic provinces of the Gulf of Mexico they represent most depositional environments.

Some of the cores from the southwest Gulf of Mexico were studied for variations in clay mineralogy with depth. The variations can be explained by a change of the source area or by postdepositional alterations. However, clay-mineral diagenesis appears to play only a minor role in causing vertical compositional variations of near-surface sediments in the Gulf of Mexico.

The physical properties--grain size, water content, void ratio, shear strength, carbonate content, and specific gravity--were measured shortly after core recovery. The variation of clay mineralogy was compared with physical-property data, and no single correlation was found. However, many multivariable explanations can be made. For example, a change of grain size commonly corresponds to a change in void ratio or porosity. As void ratio increases, water content shows a corresponding increase whereas shear strength tends to decrease. Variations in grain size often signify a different clay-mineral assemblage.

AAPG Search and Discovery Article #90972©1976 AAPG-SEPM Annual Convention and Exhibition, New Orleans, LA