About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

Journal of Sedimentary Research (SEPM)

Abstract


Journal of Sedimentary Petrology
Vol. 53 (1983)No. 4. (December), Pages 1261-1270

Paleochannel Geometry and Flow Patterns Determined from Exhumed Permian Point Bars in North-central Texas

Marc B. Edwards (2), Kenneth A. Eriksson (3), Robert S. Kier (4)

ABSTRACT

Point-bar deposits in the Clear Fork Group (Lower Permian) of north-central Texas are exposed both in cross section and in plan as exhumed arcuate accretionary ridges. A thin basal lag of locally derived caliche and mudstone fragments is overlain by a 2 to 3 m thick epsilon cross-stratified unit which fines upward from very fine sandstone at the base to mudstone at the top. Sandstone beds in the epsilon units are almost entirely cross-laminated and were deposited by straight-crested ripples, most of which are oriented at 40° to 65° to the main channel direction.

The Clear Fork point bars were deposited by small, variable-discharge, perennial streams with high sinuosity. The straight-crested ripples migrating on the point bar surfaces are oblique rather than perpendicular to the near-bed flow direction. The cause of such considerable obliquity was primarily a large transverse gradient in local downstream sediment transport rate and, to a lesser degree, components of transverse near-bed fluid velocity due to helicoidal flow.


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