T1 Linking Mineral Resources and Their Geologic Framework I: The USGS Earth Mapping Resources Initiative (Earth MRI) and Related Critical Minerals Research

Sunday, 22 September 2024
8:00 AM - 12:00 PM
212A

CARBONATES AS A WINDOW INTO FLUID PROCESSES IN THE PARADOX BASIN, UT AND CO

Paper number: T1-12
Program: Technical Sessions
Time: 10:40 AM – 10:55 AM

Authors

Abstract

Distinctive aspects of the geologic framework, paragenesis, and chemistry of carbonate minerals provide insight into the diverse conditions (from EMPA and SEM compositions) and timing (from carbonate U-Pb) of fluid events in the Paradox Basin. Included in the basin’s fluid history are the events that generated sandstone-hosted U(-V) and Cu(-Ag) deposits. Focusing primarily on the La Sal district, new mapping, core logging and petrography show that there are several different stages of carbonate formation: early U(-V) related cements are overgrown by multiple younger generations, and later-still are fault-related Cu(-Ag) carbonates. Carbonate concretions in Morrison Formation sandstones comprise ferroan dolomites, whereas tabular U(-V) deposits hosted in the same units contain paragenetically older calcites with a slight manganoan affinity. In contrast, carbonates in vein and stratabound Cu(-Ag) deposits can range from calcite to dolomite in composition, both in vein and in disseminated form. The range in compositions is consistent with differences in redox state and perhaps salinities of the causative fluids. U-Pb geochronology of ore-stage carbonates yields Early Cretaceous ages for U(-V) mineralization that are broadly congruent with earlier results obtained by different approaches (whole rock U-Pb, Rb-Sr) and the notion of near-surface mixing of hydrologic systems. Vein carbonates intergrown with hypogene Cu(-Ag) mineralization consistently yield middle Miocene to Pliocene carbonate U-Pb dates. This age range contrasts with previous geological inferences and two Re-Os dates on sulfides. Miocene and younger mineralization implies a change in the basin’s hydrology, possibly as a result of far-field tectonics (extension in the Basin and Range) or initial stages of exhumation.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-404242

© Copyright 2024 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.