Depositional dynamics of the Brushy Canyon Formation, Delaware Basin, Texas

Abstract

The Brushy Canyon Formation, lowermost of the DeLaware Mountain Group, represents a network of submarine channel and overbank deposits, The site of deposition, the Delaware basin, was analogous to present deep basins off the coast of southern California, such as San Pedro, Sc.nta Monica, and San Diego basins. Because recent data from present oceans indicate that submarine channels like those in the Delaware basin initiate at the mouths of submarine canyons, the existence of numerous submarine canyons along the margin of the ancient Delaware basin is inferred.

By analogy with the above recent examples, sediment was probably delivered by tidal and longshore current action into the heads of submarine canyons which extended back onto the platform. Subaqueous bottom flows initiated by earthquakes, storm generated waves, or by overloading, transported sediment down the canyons and into the deep basin via the subsea channels. The coarser material remained in the channels which extended many miles beyond the canyon mouths, whereas much of the finer material spilled over the channel margins and produced natural Levees and finely laminated overbank deposits. These overbank deposits are much Like the flood plain deposits made by subaerial streams.

Current flow data obtained from the Brushy Canyon Formation are remarkably unidirectional, which seems to be a characteristic of sediment deposited by this mechanism. The prevailing current direction is southeast (i, e,, basinward), perpendicular to the northeast-southwest trending platform margin.