About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

GCAGS Transactions

Abstract


Gulf Coast Association of Geological Societies Transactions
Vol. 43 (1993), Pages 31-40

Correlation Efficiency as a Tool to Better Determine Depositional Subenvironments in Submarine Fans

Arnold H. Bouma (1), Michael B. DeVries (1,2), Timothy W. Cook (1)

ABSTRACT

Depositional facies in submarine fan systems are commonly too large to be entirely or sufficiently exposed in an outcrop in order to make conclusive identifications. The normally tectonically-Previous HitdippingNext Hit layers prevent lateral correlation over any significant distance. A channel fill usually is identified as being massive, bedded with or without any vertical sequence trend, horizontally layered or inclined, thick or thin bedded, or any combination of these parameters. The levee and overbank deposits consist of alternating sandstone and shale layers, and typically have distinct tractional sedimentary structures. The non-channelized depositional lobes are bedded, very sand-rich, may reveal upward-thickening cycles, and contain complete or incomplete turbidites. The variation in submarine fans is too large to apply the mentioned criteria without other information.

The lower Permian Skoorsteenberg Formation of the southwest Karoo in South Africa is likely the only available non-tilted outcrop series comprising middle and lower fans, thus permitting unbiased identifications. Because this provides only one model, another system was developed for the two parallel sides of the DeGray Spillway of the Jackfork Group in Arkansas. Layer by layer correlation within correlative packages failed because Previous HitbedNext Hit thickness and number of layers normally differ over the short distance of 214 feet. A different approach, plotting the succession of layers vertically and weighing them equally in spite of different thicknesses and plotting each Previous HitbedNext Hit thickness horizontally in a "semi-logarithmic" manner, made it possible to correlate on Previous HitbedTop thickness trends.

The system is not foolproof and any additional information available should be used. Too often, outcrops are interpreted based on models only and wrong results are common. The degree of correlation, using the thickness trend technique, helped to better identify depositional environments. The technique was also applied to the Dierks Spillway outcrops in Arkansas.


Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Watermarked PDF Document: $14
Open PDF Document: $24