Natural Resources and Sequence Stratigraphy of Aux Vases Sandstone

LEETARU, HANNES E., Illinois State Geological Survey, Champaign, IL

The Aux Vases Sandstone (Valmeyeran Series, Mississippian System) was deposited in a tidally influenced, mixed carbonate-siliciclastic environment in the Illinois Basin. It is a significant aquifer in southwestern Illinois, a major oil producer in the south-central and southeastern portions of Illinois, an important quarrying stone in the southeast part of the state, and strata directly underlying the Aux Vases Sandstone siliciclastic beds in southeast Illinois and western Kentucky once were responsible for most of the fluorspar in the United States.
Sequence stratigraphy is used to reinterpret depositional systems of the Ste. Genevieve Limestone (Valmeyeran Series) through Renault Limestone (Chesterian Series, Mississippian System). Previously, the Spar Mountain Sandstone Member of the Ste. Genevieve Limestone was thought to be a lower tongue of Aux Vases Sandstone. This study shows that the Spar Mountain Sandstone was deposited in an older incised valley system unrelated to the Aux Vases Sandstone, which formed in a complex system with incised valleys to the west and possible barrier islands and shallow marine shelf systems to the east. Carbonate and siliciclastic sediments in the Aux Vases Sandstone are interbedded and, in some cases, interlaminated indicating contemporaneous deposition of both lithologies.
Sequence stratigraphy is a useful tool for reducing costs of exploiting Aux Vases Sandstone resources. It can be used in delineating areas best for locating hydrocarbons, recovering water resources, highlighting potential problems in quarrying operations, and outlining regions where calcareous lithologies of the Aux Vases Sandstone will interfere with Ste. Genevieve Limestone seismic reflection. In general, sequence stratigraphy will help develop a better understanding of depositional systems within a cratonic basin.

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