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ABSTRACT: Southern Oklahoma Aulacogen: An Integrated Basin Model

D. A. Wavrek

A basin model has been developed for the southern Oklahoma aulacogen that includes geochemical data, structural analysis, and regional mapping. This integrated approach has been used to reconstruct the basin's complex history.

Geochemical characterization of over 400 oil samples indicates the presence of four major oil types together with mixtures of these end members. Type A oils have abundant isoprenoids and relatively abundant C15+ n-alkanes that show a linear decrease with increasing carbon number. Type B oils have a moderate amount of isoprenoids and an n-alkane profile that decreases exponentially with increasing carbon number. Type C oils have a moderate odd-carbon preference in the nC11-nC19 range, moderate isoprenoids, and anomalous concentrations of alkyl-benzenes and alkyl-cyclohexanes. Type D oils have a strong odd-carbon preference in the nC11-nC19 range, minor isoprenoids, and limited n-alkanes longer than nC19. These four oil t pes appear to correlate with Middle Pennsylvanian shales, the Devonian-Mississippian rock units, the Viola Group (tentative), and an unidentified Ordovician unit, respectively.

Because the sedimentation history of a region reflects the tectonic development, burial reconstructions are combined with a thermal model to establish the timing of hydrocarbon generation. The three-dimensional extension of this procedure demonstrates that the major pulse of oil migration from the Ardmore basin was concurrent with the fold development during early Pennsylvanian deformation, whereas migration from the Marietta basin was affected by fault displacements that were more extensive during Late Pennsylvanian deformation. The distribution of various oil types helps constrain the basin model and demonstrates the application of geochemistry in a mature exploration province.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990