Abstract

Hydrocarbons exist in the Frontal and Central Ouachita Mountains in three distinct forms: crude oil, asphaltite, and as organic matter disseminated in potential source rocks. Each of these types has been examined geochemically, in an attempt to correlate oil to asphaltite and oil to source rock. Results show that the crude oil produced to date is chemically mature and largely undegraded. Examination of the Ouachita section for source potential indicates that several formations are high enough in organic carbon to have sourced oil, although some may be ruled out on the basis of the type of organic matter present.

Association of oil and asphaltite along the strike of the Windingstair Fault indicates that this listric reverse fault may have served as a migration conduit. Geochemical similarities between analyses of asphaltite from the upper Ordovician Bigfork Formation and that from the Mississippian Stanley Group further indicate the possibility of vertical migration. Finally, migration along a listric fault, with subsequent near-surface degradation of the oil, would explain the close association of near-surface solid asphaltite and slightly deeper liquid oil.