Abstract

The Flippen Limestone of central Jones County, Texas, is one in a series of Virgilian-Wolfcampian limestones representative of cyclic deposition characteristic of late Pennsylvanian and early Permian sedimentation on the Eastern shelf of the Midland Basin.

Data obtained from exploratory drilling indicates that the Flippen Limestone was subaerially exposed to the effects of meteoric waters after deposition during a regressive phase of the sea. Paleostream systems developed, and the Flippen Limestone was leached and eroded as streams meandered westward from the Ouachita Uplift toward the subsiding Midland Basin.

Core analysis shows there to be at least four depositional facies and environments within the Flippen Limestone. A calcarenite facies may be subdivided into a shallow marine, medium to high energy grainstone lithotype, or a low energy, shallow marine, packstone lithotype. A pelletal-breccia facies represents a shallow marine, restricted depositional environment. The pelletal limestone was brecciated upon exposure to meteoric waters in a supratidal environment. A rounded grain facies composed of micrite mud balls and fossil fragments set in a matrix of blocky calcite spar is indicative of a shallow marine, medium to high energy environment. Nodular limestone representing a low energy, nearshore marine environment is the uppermost depositional facies recognized in the sequence.

Diagenetic processes are responsible for both creation and destruction of porosity and permeability in the Flippen Limestone. Secondary pores in the form of pinpoint vugs, solution channels, solution-enlarged breccia porosity, and moldic porosity, are the result of subaerial exposure and leaching by percolating meteoric waters in a vadose environment.

Primary porosity is mostly absent due to cementation by blocky spar and microspar. Much secondary porosity (most notably solution-enlarged breccia porosity) has been occluded by white, coarse crystalline, late diagenetic, sparry dolomite.