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Sequence Stratigraphic Analysis of Coal-bearing Lower Pennsylvanian Strata, Central Appalachian Foreland Basin, southwestern Virginia: Controls on Coal Attributes

Ryan P. Grimm
Virginia Tech Department of Geosciences Blacksburg, Virginia United States of America [email protected]

     Lower Pennsylvanian sediments of the Breathitt Group occur in the deeper part of the Central Appalachian Basin, where deposits thicken significantly to the southeast from Kentucky into Virginia. Coal-bearing immature siliciclastic strata intercalated with quartzarenite belts dominate the Lower Breathitt Group. Chesnut (1994) identified several widespread marine horizons subdividing the Breathitt Group into eight third order transgressive sequences. Within each transgressive sequence, Greb et al. (2004) documented 5-6 smaller scale cyclic facies successions of siliciclastic deposition between coal seams, each attributed to high frequency orbital eccentricity driven glacio-eustatic cycles.
     This investigation will seek to clarify the depositional influences of coal seam system tract position (HST/LST) and sequence hierarchy (third/fourth order) on coal quality attributes in the central Appalachian Basin. A stratigraphic analysis of the Breathitt Group in southwestern Virginia provides the opportunity to evaluate existing approaches to the sequence stratigraphy of non-marine, coal-bearing strata, and thus define any correlation between sequence stratigraphic position and coal quality attributes, including variations in thickness, cleating and geochemical composition.
     The Virginia Coalfield is excellent for study due to the high density of recent conventional and CBM well perforation. The project dataset includes geophysical well logs, measured outcrops, and donated cores. Surveying subsurface coal deposystem facies stacking patterns and distribution of genetic facies associations will have instant benefits for both mining and CBM development. Additionally, this study will assist the Southeast Regional Carbon Sequestration Partnership efforts to characterize the geologic constraints of mature CBM reservoirs, using cores from a carbon dioxide sequestration well test site.

 

AAPG Search and Discovery Article #90070 © 2007 AAPG Foundation Grants in Aid