Burial Diagenesis of Upper Mississippian Greenbrier Limestone in Central Appalachian Basin: ABSTRACT

Abstract

As carbonate sediments undergo progressive burial under conditions of increasing temperature and pressure, they go through a variety of changes. Burial diagenesis includes processes such as mechanical and chemical compaction, mineralogic change, cementation, dolomitization, and various types of neomorphic fabric change. Identifying the products of burial diagenesis may be useful in predicting porosity and reservoir quality in the subsurface. The Upper Mississippian Greenbrier Limestone and equivalents are exposed throughout the central Appalachians. Important textural and mineralogical changes have been recognized in these shallow shelf limestones, which indicate burial to different depths. Variations in trace- and minor-element concentrations occur with increasing diagenesis. Textural alterations include increased matrix (micrite) crystal size and increased twinning of echinoderm fragments. The Greenbrier Limestone can be divided into three diagenetic provinces. Zone 1, located on the extreme western side of the basin, is characterized by little evidence of compaction, mineralogic variation, or textural change. In this area, the limestones were never buried to any great depth. Zone 3, on the eastern side of the basin, is characterized by significant mechanical and chemical compaction, and mineralogic and textural change. Limestones of this diagenetic province have been subjected to relatively high paleotemperatures during deep burial. Zone 2 ismore » of intermediate burial depth and diagenesis and is present between zones 1 and 3.« less