Episyenites in the Zuni Mountains, Cibola County, New Mexico — New interpretations
— Virginia T. McLemore


Brick-red, K-feldspar-rich episyenites (altered rocks that were desilicated and metasomatized by alkali-rich solutions) are found in Proterozoic-age rocks in the Zuni Mountains in central New Mexico. The Zuni episyenites are high in K2O and depleted in SiO2 and Na2 O, with slightly enriched heavy REE patterns. The Zuni episyenites are similar in composition to episyenites found in the Caballo and Burro mountains, the Sevilleta National Wildlife Refuge, and at Lobo Hill, but the Zuni episyenites are lower in REE. The Zuni episyenites are younger than ~1000 Ma. Similar episyenites are found elsewhere in New Mexico and southern Colorado and are thought to be part of a Cambrian-Ordovician magmatic event that is documented throughout this region. Unlike episyenites in the Caballo and Burro mountains, which contain moderate to high concentrations of rare earth elements (REE), uranium, and thorium, the episyenites in the Zuni Mountains have little or no economic potential.

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Recommended Citation:

  1. McLemore, Virginia T., 2021, Episyenites in the Zuni Mountains, Cibola County, New Mexico — New interpretations, in: New Mexico Geological Society, 71st Annual Fall Field Conference, September 2021, Geology of Mount Taylor, Frey, Bonnie A.; Kelley, Shari A.; Zeigler, Kate E.; McLemore, Virginia T.; Goff, Fraser; Ulmer-Scholle, Dana S., New Mexico Geological Society, Guidebook, pp. 129-136. https://doi.org/10.56577/FFC-71.129

[see guidebook]