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Abstract

Carbonate-hosted hydrothermal deposits typically show narrow visible mineralogical and textural alteration halos, which inhibit exploration targeting. In contrast, hydrothermal modification of the country rock’s stable isotope composition usually extends far beyond the limited visible alteration. Hence, stable isotope studies should be an effective tool to aid exploration for carbonate-hosted deposits. Here we present new insight into the development of a large stable isotope alteration halo based on 910 O and C isotope analyses of carbonate veins and hydrothermally altered limestone hosting the Cinco de Mayo Pb-Zn-Ag (Au, Cu) carbonate replacement deposit (CRD), in Chihuahua, Mexico. Our results demonstrate that stable isotope alteration is consistent with reactive, magmatic fluid flow into unaltered limestone and represents a powerful tool for the characterization of these hydrothermal ore systems. Synmineralization veins are texturally and isotopically distinct from those formed during pre- and postmineralization diagenesis and fluid flow and show distinct gradients along the direction of mineralizing fluid flow: this appears to be a promising exploration vectoring tool. Downhole variations in wall-rock isotope values reveal aquifers and aquicludes and outline the principal hydrothermal flow paths. Furthermore, wall-rock δ18OVSMOW systematically decreases toward mineralization from ~23‰ to

Item Type:	Article
Authors/Creators:	Beinlich, A and Barker, SLL and Dipple, GM and Hansen, LD and Megaw, PKM
Keywords:	mineral exploration, stable isotope, carbonate-replacement, alteration
Journal or Publication Title:	Economic Geology and The Bulletin of The Society of Economic Geologists
Publisher:	Economic Geology Publ Co
ISSN:	0361-0128
DOI / ID Number:	https://doi.org/10.5382/econgeo.2019.4635
Copyright Information:	© 2019 Society of Economic Geologists, Inc.
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