Michael H. Gardner1,
James M. Borer1
(1) Colorado School of Mines, Golden, CO
Abstract: Submarine channel architecture along a slope to basin profile, Brushy Canyon Formation, West Texas
The correlation of submarine channels with flanking overbank deposits is critical to determining bed connectivity, continuity, lithology, and facies distributions within these important deep-water reservoirs. Existing submarine channel-overbank models assume that overbank (levee construction) and channel deposition are contemporaneous and record the highest energy condition during the evolution of a channel-levee complex. We propose an alternative "build," "cut," "fill," and "spill" model for submarine channel development that explains not only lateral channel-overbank facies relationships but also predicts proximal-distal changes in submarine channel architecture.
Slope and basin-floor channel sandbodies in the Permian Brushy Canyon Formation compose a depositional profile along which changes in the facies architecture of a four-fold channelform hierarchy are compared. Multistory and multilateral channel complexes (30-m thick by 450-m wide) form sandbodies (30-m thick by 450-m wide) with serrate margins consisting of stacked channels (7-m thick by 150-m wide) that increase in offset basinward. Channels and channel complexes record "cut," "fill," and "spill" phases of bypass and deposition, with channel and overbank deposition offset in time.
Upper slope siltstones encase the largest channelform sandbodies confined to intraslope depressions. Sediment bypass gives way to deposition down-profile, producing multistory, multilateral, and eventually distributary channel patterns. As complexes widen, both "build" phase deposits that precede channelization, and subsequent spill-phase overbank deposits thicken down-profile, effectively equilibrating sandstone volumes inside and outside channels.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana