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Detailed studies of the petrography and geochemistry of petroleum source rocks, the geochemistry of petroleum accumulations, and the paleohydrology of the Illinois basin suggest an episode of long-range migration of Devonian-sourced petroleum during a period of regional groundwater flow.
Petrographic analyses of samples of the New Albany Shale group (Devonian/Mississippian) were used to define lateral and vertical variation in composition and thermal maturity of organic matter within the basin. These data delineate likely New Albany Shale group petroleum source areas.
GC, GCMS, and carbon isotopic analyses of thermally mature New Albany Shale in southeastern Illinois and Silurian-reservoired petroleum samples from central Illinois were used in making oil-oil and oil-source rock correlations. These correlations indicate long-range lateral and downward cross-stratigraphic net migration.
Compaction-driven and elevation head-driven ground-water flows within the basin were numerically modeled using available stratigraphic, structural, and hydrologic data. Calculations based on compaction-driven flow show the possibility of down-stratigraphic migration. Compaction-driven flow, however, cannot explain the amount of lateral transport inferred. Regional ground-water flow due to the uplift of the Pascola arch could explain the long-range lateral migration.
Calculations of the effects of advective heat transport by elevation head-driven flow agree with estimates of temperatures made from fluid inclusions in basin mineralization.
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