Linear Sand Body Trends in Mississippian Aux Vases Formation Outcrop Belt: Model for Subsurface Exploration: ABSTRACT

Abstract

A regional analysis of depositional environments and facies relationships in the Mississippian Aux Vases Formation has identified two distinct linear sand-body trends. Field investigations from the type section in southeastern Missouri across southern Illinois to outcrops in Indiana and Kentucky show a major northeast-southwest trend and a secondary north-northwest-south-southeast trend. The major trend is interpreted to be a series of tidal-channel complexes, while the secondary trend is interpreted as multilateral and multistored offshore or tidal bar complexes separated by thin sheet sands or shallow marine shales. All sand bodies are composed of fine to medium-grained, subangular to rounded, sand-size quartz grains. Subsurface investigations by many previous workers have also identified linear sand bodies variously interpreted as channels or bars. A depositional model based on outcrop studies suggests that the tidal channel facies is volumetrically larger than the offshore bar facies and should therefore be potentially larger hydrocarbon reservoirs. Empirical models, based on detailed outcrop analyses, may greatly enhance hydrocarbon exploration.