Tectono-Eustatic Controls on Carbonate Platform Development, Permian Basin Outcrop-Subsurface
J. F. (Rick) Sarg, Karen Romine, Peter R. Vail
Integration of seismic stratigraphic concepts, detailed field studies, and geohistory analysis provides powerful interpretation leverage for deciphering the geologic history of the Permian carbonate platform complexes. The structural history of the Permian basin during the Permian shows two subsidence cycles of 10 to 20 m.y. duration. These subsidence cycles played a major role in the long-term (millions to tens of millions of years) development of the Permian carbonate platforms. During periods of relatively rapid subsidence, aggradation was dominant; during times of slow subsidence, major basinward platform progradation occurred.
Superimposed on the long-term tectonic cycles are a series of third-order eustatic cycles (0.5-3 m.y.) which controlled development of 23 depositional sequences. Each sequence is composed of three depositional systems tracts: (1) a lower basin-restricted wedge interpreted to have been deposited during a relative fall and lowstand of sea level; (2) a transgressive systems tract of variable thickness; and (3) an upper aggradational to progradational carbonate platform system interpreted to have been deposited during a relative highstand in sea level. The lowstand systems tracts are composed dominantly of quartz sandstone, commonly intercalated with carbonate debris beds at the toe-of-slope. Two highstand depositional styles are differentiated here: (1) a keep-up system which maintains p ce with periodic rises in relative sea level and displays a mounded-oblique stratal geometry at the platform margin and (2) a catch-up system which represents a relatively slow rate of accumulation and displays a sigmoid profile at the platform margin. Sequence boundaries display erosional truncation (subaerial on shelf or at shelf edge; subaqueous on slope) and/or subaerial exposure.
AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.