Petrology of the Weir sand (lower Mississippian) in the Ashland-Clark Gap gas field of southern West Virginia / by Robert W. Privette.
| Author/creator | Privette, Robert W. author. |
| Other author | Neal, Donald W., degree supervisor. |
| Other author | East Carolina University. Department of Geology. |
| Format | Theses and dissertations |
| Production | 1983. |
| Description | 78 leaves, 11 unnumbered leaves : illustrations (some color), maps ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | The Weir sand is a fine-grained lithic arenite with minor interbedded shales, which was deposited as a marine bar in a delta-front environment. The average composition is 54% quartz, 17% rock fragments, 5% feldspar, 9% carbonates, 7% porosity, 5% matrix, and 3% accessory minerals. The rock fragments include both metamorphic and sedimentary fragments, which indicates a combined metamorphic and sedimentary source area. Porosity includes both intergranular primary and intragranular secondary porosity. The porosity values range from 0 to 13.2% with an average permeability of less than 0.2 md. Diagenetic changes have affected both the porosity and permeability of the Weir. The greatest effect has been the overall reduction of porosity by compaction and the formation of authigenic minerals, primarily carbonates. Porosity was preserved by the formation of authigenic chlorite, which prevented quartz overgrowth formations during the late stage of diagenesis. Porosity was increased slightly by the creation of secondary porosity due to the dissolution of authigenic minerals and detrital grains. Diagenetic changes have altered both the porosity and petrology of the Weir. The proposed sequence can be separated in an early, middle, and late stage of diagenesis. The early stage began with the initial compaction of the sand and the formation of pyrite and pore filling calcite. This was followed by the formation of illite and siderite. The middle stage is characterized by a change in the geochemistry from reducing to oxidizing conditions, the formation of quartz overgrowths, and the creation of secondary porosity. The late stage is characterized by a shift to reducing conditions and the formation of chlorite grain coatings, and a second generation of pore fillings calcite, and the kaolinization of K-feldspar. |
| General note | "Presented to the faculty of the Department of Geology ... in partial fulfillment of the requirements for the degree Master of Science in Geology." |
| General note | Advisor: Donald W. Neal |
| Dissertation note | M.S. East Carolina University 1983 |
| Bibliography note | Includes bibliographical references (leaves 70-74). |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |