TY - JOUR
T1 - Igneous Geochronology and Thermochronology of the Northern Battle Mountain District, Nevada
T2 - Implications for Gold Mineralization
AU - Huff, Dante E.
AU - Holley, Elizabeth A.
AU - Guenthner, William R.
N1 - We thank reviewers Mark Barton and David John whose comments greatly improved the manuscript. NSF EAGER awards to EH (1641142) and WRG (1641138) and an NSF CAREER award to EH (1752756) supported this research. We gratefully acknowledge Nevada Gold Mines and SSR Mining Inc. for access to sampling sites, historical data, and logistical support. At Colorado School of Mines (Golden, Colorado), we thank Jae Erickson at the Thin Section Laboratory, Wendy Bohr-son for her valuable insight on magmatic processes, and Jorge Crespo and John Meyer for their helpful comments to improve this manuscript. We thank Victor Valencia at Zirchron LLC for sample separation, Jim Crowley at the Boise State Isotope Geology Laboratory (Idaho) for U-Pb geochronology and discussion of results, and Linda Angeloni at the Helium Analysis Laboratory (University of Illinois at Urbana-Champaign) for assistance with (U-Th)/He analyses.
PY - 2025/1
Y1 - 2025/1
N2 - The Battle Mountain mining district of north-central Nevada hosts a variety of gold deposit types, including Cu-Au porphyries and skarns, polymetallic veins, and sedimentary rock-hosted disseminated Au deposits. This study examines intrusions in the northern part of the district, with a focus on those spatially associated with the sedimentary rock-hosted disseminated Au deposits. We identify three periods of magmatism in the district using zircon U-Pb geochronology-Jurassic (~162 Ma), Cretaceous (~97-92 Ma), and Eocene (~40-39 Ma)-which we attribute to magma periodically exploiting a structural fabric that developed over a Late Proterozoic rift structure. New district-scale geophysical surveys support this process; aeromagnetic data reveal large positive anomalies that we interpret to represent batholiths that grew through repeated injections of magma during the Cretaceous and Eocene. Sedimentary rock-hosted Au deposits are generally located at the margins of these anomalies, suggesting that mineralizing fluids utilized the fracture networks that developed where the rheologic contrast between igneous stocks and the surrounding country rock is most pronounced. Apatite and zircon (U-Th)/He thermochronology identifies district-wide cooling during the Eocene, even at deposits that lack causative Eocene intrusions. We interpret this Eocene date population to represent heating and subsequent cooling from widespread hydrothermal fluid flow, as the (U-Th)/He dates overlap with the formation of Eocene magmatic-hydrothermal Au deposits elsewhere in the Battle Mountain district (e.g., Converse, Buffalo Valley, Elder Creek, Copper Basin, Copper Canyon) and predate rapid exhumation. Time-temperature thermal models on (U-Th)/He aliquots and an absence of alteration zonation constrain fluid temperatures to <210°C during this period. Based on the spatial association with inferred large batholiths at depth and the fluid temperature constrained by thermal modeling, we interpret that Eocene magmatism contributed fluids and heat (and possibly metals) to the sedimentary rock-hosted disseminated Au deposits in the northern Battle Mountain district.
AB - The Battle Mountain mining district of north-central Nevada hosts a variety of gold deposit types, including Cu-Au porphyries and skarns, polymetallic veins, and sedimentary rock-hosted disseminated Au deposits. This study examines intrusions in the northern part of the district, with a focus on those spatially associated with the sedimentary rock-hosted disseminated Au deposits. We identify three periods of magmatism in the district using zircon U-Pb geochronology-Jurassic (~162 Ma), Cretaceous (~97-92 Ma), and Eocene (~40-39 Ma)-which we attribute to magma periodically exploiting a structural fabric that developed over a Late Proterozoic rift structure. New district-scale geophysical surveys support this process; aeromagnetic data reveal large positive anomalies that we interpret to represent batholiths that grew through repeated injections of magma during the Cretaceous and Eocene. Sedimentary rock-hosted Au deposits are generally located at the margins of these anomalies, suggesting that mineralizing fluids utilized the fracture networks that developed where the rheologic contrast between igneous stocks and the surrounding country rock is most pronounced. Apatite and zircon (U-Th)/He thermochronology identifies district-wide cooling during the Eocene, even at deposits that lack causative Eocene intrusions. We interpret this Eocene date population to represent heating and subsequent cooling from widespread hydrothermal fluid flow, as the (U-Th)/He dates overlap with the formation of Eocene magmatic-hydrothermal Au deposits elsewhere in the Battle Mountain district (e.g., Converse, Buffalo Valley, Elder Creek, Copper Basin, Copper Canyon) and predate rapid exhumation. Time-temperature thermal models on (U-Th)/He aliquots and an absence of alteration zonation constrain fluid temperatures to <210°C during this period. Based on the spatial association with inferred large batholiths at depth and the fluid temperature constrained by thermal modeling, we interpret that Eocene magmatism contributed fluids and heat (and possibly metals) to the sedimentary rock-hosted disseminated Au deposits in the northern Battle Mountain district.
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U2 - 10.5382/econgeo.5114
DO - 10.5382/econgeo.5114
M3 - Article
AN - SCOPUS:85219750483
SN - 0361-0128
VL - 120
SP - 137
EP - 169
JO - Economic Geology
JF - Economic Geology
IS - 1
ER -