VOLCANIC ASH IN THE HOOPER FORMATION (PALEOCENE), WILCOX GROUP: A PRELIMINARY REPORT

Volcanic ashes and detrital zircons in the Texas Gulf Coast are generally well-known, especially those associated with early-middle Eocene subbituminous coals and disseminated within the Upper Wilcox Group and Claiborne Groups. No published works on the volcanic ash in the lower or middle Wilcox Group exist. The unofficial formation designation of “Hooper” was proposed in the 1950’s for a succession of siliciclastic rocks and coals, with a type locality in McKinney Roughs Nature Park on the Wilbarger Bend of the Colorado River in Central Texas. The upper portion of the exposure contains a ca. 2-m thick subbituminous C coal with two splits, a basal tonstein of varying thickness that averages 2-dm thick, and an upper siliciclastic split. The ash contains abundant intact and fragmentary leaf compression-impression fossils, and likely fell into moving water as there is some indication of minor redistribution of the ash. Petrographic and geochemical analyses of the ash were completed at Morehead State University and the Kentucky Geological Survey, respectively. The ash is a devitrified kaolinite clay with remnant glass shards, rare zircon crystals, abundant leaf compression-impression fossils, and minor charcoal. Here we present results of optical petrography and XRD/XRF geochemistry of the ash.