Abstract: Long-Distance Turbidite Correlations in Horseshoe Abyssal Plain
William H. Hoyt, Paul J. Fox
Few studies on modern abyssal-plain turbidites have attempted to assess the lateral extent of individual units and few therefore have been able to provide any information on the evolution of turbidity deposits across long abyssal-plain distances. In the 4,755 m-deep Horseshoe Abyssal Plain, 10 distinct lithologic units (six of these Iberian Peninsula-derived turbidites) were delineated in nine piston cores on the basis of stratigraphic position, thickness (range of 20 to over 500 cm), color, sediment type, sedimentary structures, X-ray mineralogy, and the ubiquitous presence of units in all abyssal-plain and supplying-canyon piston cores. To make this correlation more rigorous, detailed grain-size analyses, light and heavy mineralogy of sands, hydrochloric acid treatment, and volatile-solids determinations were performed on three of the six turbidite units, which have volumes of 5.7, 8.0, and 12.1 cu km. These analyses further confirm correlation over the entire 15,000 sq-km area of the Horseshoe Abyssal Plain and certainly provide long-distance correlations for six individual turbidites of over 300 km for each flow.
The results of previous studies on modern abyssal-plain turbidites, ancient flysch deposits, and experimental lab studies compared with results from the Horseshoe Abyssal Plain deposits indicate that minor physiographic disturbances on the abyssal-plain floor result in marked sedimentologic variation. Previous simple predictions concerning regular turbidite grain-size decrease and turbidite-thickness decrease with increasing distance from the supplying canyon were not supported by the present study.
AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC