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Joint 53rd South-Central/53rd North-Central/71st Rocky Mtn Section Meeting - 2019

Paper No. 3-9
Presentation Time: 10:35 AM

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


PICCIONE, Gavin G.1, RASBURY, Troy2, ELLIOTT, Brent A.3, KYLE, J. Richard4, JARET, Steven J.5, ACERBO, Alvin6, LANZIROTTI, Antonio6, NORTHRUP, Paul7, WOOTEN, Kathleen2 and PARRISH, Randall R.8, (1)Department of Earth and Planetary Science, University of California Santa Cruz, 1156 High Street EMS A232, Santa Cruz, CA 95064, (2)Department of Geosciences, Stony Brook University, Stony Brook, NY 11794, (3)Bureau of Economic Geology, Jackson School of Geosciences, University of Texas at Austin, University Station, Box X, Austin, TX 78713-8924, (4)Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX 78712, (5)Alan Alda Center for Communicating Science, Stony Brook University, Stony Brook, NY 11794, (6)GSECARS, University of Chicago, Argonne National Laboratory, Argonne, IL 60439, (7)National Synchrotron Light Source, Brookhaven National Laboratories, Upton, NY 11973, (8)School of Earth and Environmental Sciences, University of Portsmouth, Burnaby Building Burnaby Road, British Geological Survey, Portsmouth, PO1 3QL, United Kingdom

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.

Session No. 3

T11. 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 (Hilton Garden Inn Manhattan )
Geological Society of America Abstracts with Programs. Vol. 51, No. 2
doi: 10.1130/abs/2019SC-327145
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