127-12 Detailed Analysis of the Long Mountain Granite, Wichta Moutains, Oklahoma

Session: Mineralogy, Geochemistry, Petrology, and Volcanology Student Session

Presenting Author:

Authors:

Abstract:

The igneous rocks of the Wichita Mountains of Southern Oklahoma formed as the result of failed rifting (Southern Oklahoma Aulacogen) during the early Cambrian. They are host to a collection of shallowly emplaced plutons and associated intrusions known as the Wichita Granite Group (WGG). The granites in this series are of similar composition, but exhibit differences in mineralogy, geochemistry, and texture. We are characterizing the Long Mountain Granite – a medium-coarse grained granite largely exposed as inselberg located along the southern margin of the central Wichita Mountains. Characterization includes petrologic analysis through XRD, XRF and SEM-EDS to best compare and contrast it against other WGG members.

We've examined 5 whole-rock and 10 hand and section samples distributed throughout the Long Mountain. Whole-rock compositions place most among a group of WGG with relatively elevated Ba (>1000 ppm) and middling SiO₂ (avg = 74.5 wt.%) and Sr (~40 ppm) values. Hand samples contained few vugs, with color varying from a light pink to a light gray, all with similar grain size. Each contain fine granophyre marked by finely exsolved perthite. The smaller population of quartz intergrowths surround large phenocrysts of finely exsolved perthite, along with Ti-Fe oxide and trace biotite.

Based on these characteristics, the Long Mountain is differentiable from surrounding granites, such as the adjacent Lugert Granite. Locally, the Lugert is largely similar in composition to the Long Mountain, but contains hornblende and exhibits little to no granophyre.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9122

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