RECENT FINDINGS REGARDING THE EASTERN WICHITA GRANITE GROUP, WICHITA MOUNTAINS, SOUTHWEST OKLAHOMA

The Wichita Mountains expose the Cambrian magmatic products of the Southern Oklahoma Aulacogen (SOA). High-resolution mapping and associated geochemical and petrographic inquiry is resolving the nature of the Wichita Granite Group (WGG), a series of shallow alkali feldspar granites that intruded the base of the rhyolite cover at its unconformable contact with the underlying Glen Mountains Layered Complex (GMLC). We report recent findings in the eastern Wichita Mountains concerning the Cache Granite, the Mount Scott intrusive suite, the Quanah Granite, and adjacent granitic and pegmatitic dikes.

The eastern WGG exposures preserve numerous igneous relationships produced by rapid-tempo emplacement. The Cache pluton is intruded first as two geochemically distinct, but otherwise similar, facies. It preserves stoped Carlton Rhyolite Group. The region was then intruded by the Medicine Park and Rush Lake Granites, followed by the voluminous and homogenous Mount Scott pluton. The Cache and Mount Scott are each intruded by the Quanah Granite; the eastern third of this latter pluton is a distinct, chemically homogenous but microstructurally variable subunit that we’ve named the Craterville facies. The contacts of the Quanah pluton (with the GMLC and with other WGG), although grossly linear and aligned to the SOA trend, exhibit numerous intrusive attributes, such as irregular geometries, included blocks, and outwardly-penetrating dikes. The Quanah Granite is itself intruded by a series of geochemically diverse dikes and small bodies, the bulk of which are concentrated on the margins of the pluton. Although dating suggest these fall within a 400 kyr window, contacts largely display evidence of significant thermal contrast (e.g. quench features).