MAPPING GRANITE INTRUSIONS IN THE EASTERN WICHITA MOUNTAINS, OKLAHOMA

The Wichita Mountains of southwestern Oklahoma are dominated by exposed Cambrian products of rift magmatism, including a voluminous series of felsic intrusives, the Wichita Granite Group (WGG). These serve as a natural laboratory for resolving the emplacement and crystallization of shallow granite bodies in extensional settings. These plutons and their overburden were buried under a thick package of early Paleozoic carbonates. Late-Paleozoic uplift during Pangean assembly exhumed and exposed the Cambrian rocks. Shallow burial and re-exhumation gave rise to the current landforms. Recent work incorporates finer scale mapping into a GIS product at 1:24 000 scale, revealing intrusive relationships.

The eastern Wichita Mountains provide great exposure of the magmatic rocks, and are suitable for decameter-scale mapping. Granite lithodemes include the Cache, Rush Lake, Medicine Park, Mount Scott, and Quanah, each thought to form as a separate intrusive event over a short (~500 kyr) period. The Quanah Granite exhibits a number of spatially associated smaller bodies, some of which are geochemically distinct, and therefore separate intrusions. All of these exhibit complex relationships with the surrounding host lithologies (largely rhyolite and gabbro, but also hornfels). Project areas are documented through 1:12 000 surface mapping and individual GPS geolocations of boundaries and features, with reference to multi-source imagery. The map resolves individual lithodemic- and formation-level units through geochemical and petrographic evaluation of broadly distributed samples. The map further resolves sub-lithodemic features of the WGG, key to understanding their emplacement relationships.