27 Geological Surveys and Resource Mapping/Evaluation Studies (Posters)

This session highlights studies from state geologic surveys and the U.S. Geological Survey regarding natural resource evaluations. We welcome submissions with relevance to critical minerals, rare earth elements, various energy sectors, and the construction industry.

Tuesday, 10 March 2026
9:00 AM - 5:00 PM
RCC, Lower Level Hall

Deep Crustal Boundaries as Fluid Conduits: A Geochemical Investigation of MVT mineralization in Kentucky and Beyond

Paper number: 27-5
Program: Technical Sessions
Time: 9:00 AM – 9:00 AM

Authors

Abstract

Critical minerals are vital to the United States economy and national security, yet their supply chains are at risk. Common minerals in Mississippi Valley-type (MVT) deposits, such as sphalerite, galena, fluorite, and barite, host critical metals such as barium, gallium, germanium, and zinc, which are essential for energy technologies. We investigated three MVT mineral districts in Kentucky to elucidate previously unrecognized systematics, genetic relationships, and sources of ore components using stable and radiogenic isotope geochemistry, particularly from galena, sphalerite, barite, and gangue minerals (e.g., carbonates). Our central hypothesis is that the location, paragenesis, and dominant kind of mineralization in each district are influenced by deep crustal boundaries that occur in the vicinity of these three mineral districts. These crustal boundaries may act as conduits for mineralizing fluids and may have a more significant influence on MVT mineralization than previously recognized.

Here we present preliminary isotope data from the Kentucky-Tennessee Mineral District (KTMD), Central Kentucky Mineral District (CKMD), and Illinois-Kentucky Fluorspar District (IKFD). Our Pb isotope data of the sulfides from the KTMD and CKMD have some overlap, but the CKMD is more radiogenic overall (average 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb: KTMD: 19.768, 15.747, and 39.332; CKMD: 19.911, 15.833, and 39.394, respectively). There is a moderate correlation between distance and 207Pb/204Pb, with more radiogenic Pb closer to the boundaries, suggesting a stronger input of Pb from Precambrian basement-derived fluids. Sulfur isotope data of sulfide and barite samples from the KTMD and CKMD also show some overlap and likely indicate similar sources of sulfur for both districts (δ34S ranges for KTMD sulfides: −11.3‰ to −0.5‰; KTMD sulfates: 29.4‰ to 35.5‰; CKMD sulfides: −8.19‰ to 0.77‰, CKMD sulfates: 21.11‰ to 38.62‰). Additional Pb, Sr, and S isotope data will be collected from the Precambrian basement rocks that the deep crustal boundaries intersect beneath these mineral districts and from various ore and gangue minerals in the IKFD. These data will be used to further elucidate sources of ore components, fluid migration, and the relationships between deep crustal boundaries and localization of these mineral districts.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411514

© Copyright 2026 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.