BOUMA, ARNOLD H., Louisiana State University, Baton Rouge, LA, MICHAEL B. DEVRIES, Exxon Exploration Company, Houston, TX, and TIMOTHY W. COOK, Louisiana State University, Baton Rouge, LA

ABSTRACT: Correlation Efficiency as a Tool to Establish Depositional Subenvironments in Submarine Fans

Depositional units in submarine fan systems commonly are too large to be entirely or sufficiently exposed in an outcrop to properly identify. Channel fills can be massive, bedded, or any combination thereof. The layering can be horizontal or inclined. Typical bedded series can be thick or thin bedded, or a combination with or without a certain cyclicity. Occurrence of sedimentary structures is not yet a decisive interpretation characteristic.

At the present, the Lower Permian Skoorsteenberg Formation of the Southwest Karoo in South Africa may be the best example of long, nontilted, outcrops where entire subenvironments can be observed. Using that knowledge, outcrop information from several areas, and ideas from the literature, we attempted correlations in two spillways in the Jackfork Group in Arkansas. A layer-by-layer correlation failed, even after small layer packages could be established using an occasional thick shale break, a major slump, or a very thick massive sandstone layer for dividing both sides of the spillway. A "semi-logarithmic" display of measured thickness provides patterns of variations in layer thickness that normally are sufficiently typical to use as a correlation tool between both sides.

This is not a foolproof system and one should consider additional parameters, such as location within the entire fan system. However, the degree of correlatibility helps identify or suggest depositional environments.

AAPG Search and Discovery Article #90989©1993 GCAGS and Gulf Coast SEPM 43rd Annual Meeting, Shreveport, Louisiana, October 20-22, 1993.