PETROLOGY AND DIAGENESIS OF THE GLENRAY LIMESTONE MEMBER OF THE BLUEFIELD FORMATION, POCAHONTAS COUNTY, WEST VIRGINIA

The Glenray Limestone is the basal unit of the drillers’ Little Lime (Reynolds-Glenray limestone couplet) in West Virginia. An outcrop of the Glenray was examined on Droop Mountain in Pocahontas County, WV. The 4.5m unit consists of a fining-upwards/ shallowing-upwards unit of mixed carbonate-siliciclastic sediment. The lower part of the unit is an ooid grainstone with a typical shallow marine assemblage of crinoids, bivalves, brachiopods, gastropods, and bryozoans. The ooid grainstone grades upward to an ooid-bearing, fossiliferous packstone to wackestone. The previously recorded components are admixed with quartz silt and terrigenous mud. The upper 3m is a pelletal wackestone with both carbonate and terrigenous mud. Bioclasts are predominantly ostracodes with a sparse, low diversity fauna of similar composition to the lower section. The percentage of terrigenous material is greater higher in the section and generally finer grained. Deposition of the Glenray Limestone was in a nearshore environment where, after an initial transgression, terrigenous sediment influx increased episodically at the expense of carbonate. Diagenesis of the Glenray Limestone includes cementation of the sediment by both sparry calcite and micrite, micritization, dissolution and subsequent infilling of porosity by granular to blocky spar, recrystallization of bioclasts, minor dolomitization and silicification, formation of stylolites and solution seams, and fracturing and subsequent infilling by carbonate.