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Revised Fusulinid Biostratigraphic Zonation and Depositional Sequence Correlation, Subsurface Permian Basin

A. M. Reid, S. T. Reid, S. J. Mazzullo, S. T. Robbins

Current revisions in fusulinid zonation enable us to subdivide the fossiliferous Pennsylvanian and Lower Permian section in the Permian basin into more biostratigraphic zones than the older scheme of R. V. Hollingsworth, each zone of shorter temporal duration than has previously been recognized. The identification of distinct fusulinid assemblage subzones within the absolute chronology of radiometric dating provides the basis for these stratigraphic subdivisions. The Atoka is divided into five assemblage subzones, each with an approximate duration of 1.0 m.y. In the Strawn, five subzones each of about 0.8 m.y. duration are recognized within the Cherokee; the three subzones in the Marmaton are each of 0.67 m.y. duration. Within Canyon and Cisco shelf carbonate sections are presently recognized seven and six subzones, respectively; the approximate duration of each is 0.33 and 1.03 m.y. The shelf Wolfcamp section is divisible into seven subzones, each of about 2.36 m.y. span. The entire Leonard shelf section comprises six subzones, each of about 1.83 m.y. duration; three subzones are presently recognized in the lower Leonard and three cumulatively in the middle and upper Leonard sections.

These biostratigraphic subzones correspond to single or composite sediment packages (parasequences) that can be correlated regionally from shelf into basinal strata, using wireline log and conventional and processed seismic sections. Such packages comprise parts of individual depositional sequences as recognized by seismic-stratigraphic interpretations. Carbonate (various shelf and foreshelf detrital facies) and sandstone reservoirs occur within individual subzones within these sequences and can be readily defined and mapped by subsurface facies studies.

AAPG Search and Discovery Article #91034©1988 AAPG Southwest Section, El Paso, Texas, 21-23 February 1988.