Volcanological and geochemical studies of Cambrian rift-related igneous rocks in the western Arbuckle Mountains, southern Oklahoma

Abstract

The Carlton Rhyolite Group formed within a major Cambrian rift in southern Oklahoma. The rhyolites are exposed in the Wichita Mountains of southwestern Oklahoma and in the East and West Timbered Hills in the Arbuckle Mountains. My project is the first modern study of the Arbuckle rhyolites. Two thick rhyolite flows are present in the East Timbered Hills and are separated by a lacustrine volcaniclastic sequence. The nearest basement well shows a similar series of rhyolite lavas, but correlation between units in the two areas is not possible. Studies of an igneous breccia in the West Timbered Hills show it to represent a basaltic phreatomagmatic vent complex. The Arbuckle rhyolites have similar A-type geochemical compositions to those in the Wichitas and are divided into four distinct trace element groups. Late diabases in the Arbuckles show geochemical affinities to within-plate tholeiitic to alkaline basalts, similar to those documented in the Wichitas.