ABSTRACT

The Avant Limestone Member of the Iola Formation (Missourian) is a phylloid-algal mound in portions of southern Osage County and adjoining counties. It is also an "upper" or "regressive" limestone member representing a phase of cyclic deposition within a cyclothem.

The locally-thickened nature, variety of types of porosity and permeability, and presence of an overlying shale suggests that the Avant might serve as a petroleum reservoir locally in the subsurface within the study area.

The mound facies of the Avant trends southwestward (from R.12E. to R.3E. along T.23N. through T.20N.). Local thickening of the Avant-Hogshooter interval along eastern and southern portions of the study area generally corresponds with thickening of the overlying Avant mound facies. This suggests that submarine paleotopography may have influenced development of the mound facies along this trend.

The Avant can be correlated southward and westward in the subsurface as well.

The name Avant in the subsurface of Noble County is often misapplied to the Wildhorse Dolomite Lentil. Stratigraphic position of the Perry Gas Sand is between the Wildhorse Dolomite above and the Avant Member below.