ABSTRACT: Sequence Stratigraphy of the Concho Platform, North Central Texas

HARRISON, EARL, Ph.D.

Strata, which are genetically related by having been deposited by the same depositional processes without being interrupted by a major disconformity, constitutes a stratigraphic sequence.

The dominant factors which influence the depositional processes were: climate, tectonics of the depositional basin, sediment economics relating to the type and amount of sediments being supplied to the basin and glacial eustatic changes of sea level.

The Concho Platform encompassed that portion of North Central Texas lying between the Ouachita structural belt and related Fort Worth Basin to the east, north of the Llano Uplift, and westward into the Midland Basin of West Texas.

The platform plunged gently to the north from the Llano| Uplift and was tilted westward into the Midland Basin by the Ouachita orogeny.

During high stands of sea level, bedded carbonate deposition was dominant across the Concho Platform, Biostromal carbonate banks, with localized biohermal reefing, were prominent across portions of the platform.

Clastic deposition was dominant across portions of the platform during low stands of sea level. Shale deposits, with intercalated sandstones, were dominant. Most of the sandstone deposits were of fluvial-deltaic origin. Some of the exposed marine shales were weathered to lateritic paleosoils.

Alternate rise and fall of the sea level, in reponse to continental glaciation of Gondwanaland of the Southern Hemisphere, transgressed and regressed the shoreline back and forth across portions of the slowly subsiding Concho Platform. A slight change in water depth produced widespread advance or withdrawal of the shoreline. These processes gave rise to intercalated carbonate and clastic deposits in a vertical stratigraphic column.

AAPG Search and Discovery Article #90947©1997 AAPG Southwest Section Meeting, San Angelo, Texas