USING OUTCROP AND PRESERVED CORES TO DETERMINE THE CRITICAL MINERAL POTENTIAL OF THE WICHITA MOUNTAINS

The Wichita Mountains of Southern Oklahoma consist of knobs and hills exposing Proterozoic to Cambrian age igneous bodies and Cambrian to Ordovician carbonate and shale, surrounded by Pennsylvanian age primarily clastic sedimentary basin units fed by proximal erosion of the range. Deeper mafic units are abundant as well, as found in local outcrops and highlighted by steep magnetic intensity gradients in USGS airborne geophysics. Many of these units are enriched in the critical minerals found in the USGS’s Earth-MRI database, though the precise mechanisms and distribution of this mineralization is uncertain. Working with the USGS Earth-MRI program, the Oklahoma Geological Survey (OGS) is conducting a geochemical and mapping survey of eight 7.5’ quadrangles across the Wichita Mountains. As part of the grant, 200 samples will be sent to USGS for bulk-rock geochemical analysis (whole-rock XRF and ICP-MS-OES). Thus far, 120 samples from outcrops have been collected in the field. These samples are predominately igneous and encompass the many granitic and gabbroic units found throughout the area.

A suite of core samples (Glen Mountain Collection) housed at the Oklahoma Petroleum Information Center (OPIC) will also be used to further our understanding of the critical mineral potential of the area. This collection consists of core from 5 separate wells, encompassing more than 800 boxes of core. The Glen Mountain Layered Complex (GMLC) is a layered mafic igneous intrusion of primarily anorthositic and gabbroic rocks and is the oldest of the intrusive rocks exposed in the Wichita Mountains. All samples (both outcrop and selected core samples) will be imaged and then analyzed using a Thermo-Scientific Niton XL5 hand-held X-ray fluorescence (XRF) device to look for bulk-rock trends in elemental enrichment (Ti, Ni, Fe, Mn, etc) prior to shipment to USGS. Additionally, we have ~200 polished thin sections in this collection, which will allow for the determination of individual mineral phases using wavelength dispersive X-ray spectroscopy (WDS) with the electron microprobe at OGS. An upcoming project will focus on sampling of the entirety of the Glen Mountain collection, rather than just a selected subset of samples studied as part of this current project.