Print this pageSediment Accommodation Regions: Fragmentation of a Subsiding Shelf
WATNEY, W. LYNN, JOHN C. DAVIS, JOSEPH M. KRUGER, and JAN HARFF
Spatial analysis of isopach, structure, and lithofacies data, including shelf-wide mapping of Upper Pennsylvanian cyclothem-scale genetic stratigraphic units (GSUs) and genetic sets (GSs), provides consistent delineation of distinctive kilometer-scale sediment accommodation regions (SARs), in the form of rhombic and arcuate shaped subdivisions of the 100,000 km{2} shelf bordering the Anadarko and Arkoma basins. Basinward trends of increasing sediment accommodation space are interrupted by areas of seemingly episodic structural movements that define the SARs. The regions closely correspond to heterogeneous crustal blocks defined by potential field geophysics, basement geology and geochronology. Episodic structural activity along boundaries of SAR's may have resulted from changes in strength and orientation of far-field stresses associated with the Ouachita orogeny.
Comparison of stratal and sedimentation patterns suggest that differing elevations of SARs led to contrasting relative sea-level histories during periods of widely fluctuating, high magnitude eustacy. Variations in subsidence rates and shelf elevations led to prominent changes in stratal stacking patterns. Using input parameters inferred from this study, forward stratigraphic models produce results that are similar to observed stratigraphy.
Each SAR is characterized by more consistent stratigraphic and sedimentological patterns, making them potentially useful in identifying subtle combination structural and stratigraphic traps. Recognizing SARs may be helpful in developing reservoir analogs where diagenetic and depositional conditions are similar. Boundaries of SARs may serve as pathways for fluid migration and play a role in hydrocarbon charging of petroleum reservoirs.