166 Mineralogical Characterization of Economic Resources: From Critical Minerals to Gemstones
From ore materials to precious gemstones, minerals play an important role in almost every aspect of our lives. This session will focus on characterization of economic minerals employing spectroscopic techniques, geochemical analysis, and microanalytical techniques.
Tuesday, 21 October 2025
8:00 AM - 12:00 PM
HBGCC, 217A
Mineralogy and Critical Mineral Potential of Alkaline Intrusions in the Northern Trans-Pecos Magmatic Province of Texas
Paper number: 166-2
Program: Technical Sessions
Time: 8:20 AM – 8:35 AM
Authors
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Mert Ugurhan Presenting AuthorThe University of Texas at Austin, Bureau of Economic Geology, Austin, TX
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Brent ElliottThe University of Texas at Austin, Bureau of Economic Geology, Austin, Texas
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Shelby ShortThe University of Texas at Austin, Bureau of Economic Geology, Austin, Texas
Abstract
The Trans-Pecos magmatic province of Texas hosts numerous Paleocene to Miocene age intrusive and extrusive igneous bodies that formed during transition from subduction-related compression to subsequent regional extension. A series of alkaline intrusions occur along a northwest-southeast trending line in the northern part of the province, encompassing mafic to highly evolved felsic magmatism. Geochemical analyses and petrographic studies were conducted to characterize these intrusions. They are ferroan, peralkaline to metaluminous in composition, and display within-plate geochemical affinity, suggesting that they were emplaced during an incipient stage of regional extension that formed the Rio Grande Rift in central New Mexico.
Intrusions in the Cornudas Mountains, Sierra Tinaja Pinta, and Black Mountains range in composition from phonolite to trachyte and are enriched in incompatible elements, including Ti, Nb, Zr, U, Th, and REEs. Whole-rock analyses of 107 samples indicate REE+Y concentrations ranging from 450 ppm to 920 ppm, with energy-dispersive spectra obtained from the scanning electron microscope confirming the presence of monazite, eudialyte, bastnäsite, parisite and aeschynite in samples from Cornudas Mountains and Black Mountains. Additionally, Marble Canyon, a compositionally zoned mafic to intermediate pluton, and Cave Peak, a breccia-hosted porphyry molybdenum deposit, are located in the Sierra Diablo Mountains. Average REE+Y concentrations from the whole-rock data are 758 ppm (n=10), and 436 ppm (n=9) for Cave Peak and Marble Canyon, respectively. Cave Peak, in particular, is the highly evolved felsic endmember of this magmatic system and is enriched in F, Nb, Cu, Pb, Zn, W, Sn, and REEs, with monazite, xenotime, yttrofluorite, and yttrocerite identified within the intrusion.
Geological Society of America Abstracts with Programs. Vol. 57, No. 6
doi: 10.1130/abs/2025AM-413441
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