Geological Society of America

3 Microanalyses, Macro Implications: Using Microscale Analyses to Decipher System-to-Regional Scale Processes

Monday, 25 March 2019
8:00 AM - 12:00 PM
Kings Room

GEOCHEMISTRY AND U-PB DATING OF FLUORITE AND NACRITE FROM THE ROUND TOP RHYOLITE: CONSTRAINTS ON MAGMATISM AND TECTONISM IN TRANS-PECOS TEXAS

Paper number: 3-9
Program: Theme Sessions
Time: 10:35 AM – 10:55 AM

Authors

Gavin Piccione
University of California at Santa Cruz, Santa Cruz, CA
Randall R. Parrish
University of Portsmouth, Portsmouth
Troy Rasbury
Stony Brook University, Stony Brook, NY
Brent A. Elliott Presenting Author
Jackson School of Geosciences, University of Texas at Austin, Austin, TX
J. Richard Kyle
The University of Texas at Austin, Austin, TX
Steven J. Jaret
Stony Brook University, Stony Brook, NY
Alvin Acerbo
University of Chicago, Argonne, IL
Antonio Lanzirotti
University of Chicago, Argonne, IL
Paul Northrup
Brookhaven National Laboratories, Upton, NY
Kathleen Wooten
Stony Brook University, Stony Brook, NY

Abstract

New radiometric dating and geochemistry help to constrain magmatic and post-magmatic process within the rhyolite magmatism in the Trans-Pecos region of west Texas. Previous radiometric ages and isotope values provide insight, but only a few of the 100+ laccoliths have data, and it has been well documented that these systems were subjected to late-stage fluid alteration processes that mobilized and recrystallized zircon. The Round Top laccolith is known for yttrium and heavy rare earth element enrichment and has been dated at 36 Ma. New U-Pb data from Y+REE-bearing fluorite and nacrite from veins in the laccolith show ages younger than 7 Ma. The mineral chemistry and geochronology of these minerals show that mineralization and mobilization of Y+REEs can occur in association with high-silica magmatic systems, and post-magmatic paragenesis constrains the timing of late-stage fluid events associated with Rio Grande rifting in west Texas.

Geological Society of America Abstracts with Programs. Vol. 51, No. 2

doi: 10.1130/abs/2019SC-327145

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