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Province-scale tin and zinc stable isotope fractionation trends in the Bolivian tin belt.

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Title: Province-scale tin and zinc stable isotope fractionation trends in the Bolivian tin belt.
Authors: Hirsh, Evan C.1 (AUTHOR), Simon, Adam C.1 (AUTHOR) simonac@umich.edu, Mathur, Ryan2 (AUTHOR), Powell, Wayne3 (AUTHOR), Megaw, Peter4 (AUTHOR), Asael, Dan5 (AUTHOR)
Source: Geochimica et Cosmochimica Acta. Mar2026, Vol. 417, p256-268. 13p.
Subjects: Isotopic fractionation, Tin isotopes, Fluid inclusions, Sphalerite, Hydrothermal deposits, Cassiterite
Abstract: The Sn and Zn stable isotope compositions of cassiterite and sphalerite have been widely used to understand the formation of magmatic-hydrothermal Sn and Zn mineral deposits. Here, we report Sn isotopic compositions of cassiterite and Zn isotopic compositions of paragenetically later, lower-temperature sphalerite from ten Sn and Zn-bearing polymetallic deposits in the Bolivian tin belt. These deposits represent distinct mineralization styles and metal transport pathways. The δ124Sn values for cassiterite vary from −0.56 to 1.64‰ (n = 33) and δ66Zn values for sphalerite vary from −0.22 to 0.92‰ (n = 20), encompassing much of the global variance observed for each isotopic system. The Llallagua and Huanuni deposits show significantly heavier Sn isotope compositions (average = 1.24 ± 0.24‰ δ124Sn; n = 10) compared to all other deposits (average = 0.56 ± 0.55‰; n = 23) and contain several distinguishing geological attributes including: genetic association with porphyry phase stocks and/or dikes, vapor-rich and moderately to highly saline fluid inclusions, vertically restricted and/or discontinuous high-grade veins, and extensive tourmaline-rich magmatic-hydrothermal breccias. Together, these features are consistent with Rayleigh fractionation and suggest that orthomagmatic fluid separation, fluid boiling, and oxidation contributed to cassiterite precipitation and caused Sn isotope fractionation. The residual fluids after cassiterite precipitation were depleted in heavy Sn isotopes and propagated along district-scale fluid pathways. The Sn isotopic ranges for cassiterite from the Sayaquira (−0.13–1.45‰), Colquiri (0.18–1.44‰), Colcha (0.07–1.47‰), and Monserrat (−0.56–0.93‰) deposits may be a consequence of cassiterite precipitation over longer mineralization length scales with increased meteoric water influx, where distal cassiterite precipitated from hydrothermal ore fluid that was depleted in heavy 124Sn. The wide and heavy range of Zn isotopic compositions of sphalerite suggests that early orthomagmatic fluid separation and boiling may have caused significant isotopic fractionation during early fluid transport prior to sphalerite precipitation. Subsequent processes including dilution by Sn- and Zn-poor meteoric water and the concomitant change in fluid pH and increase in oxygen fugacity plausibly contributed to the precipitation of isotopically lighter sphalerite at the Monserrat, El Salvador, and Huari Huari deposits. [ABSTRACT FROM AUTHOR]
Copyright of Geochimica et Cosmochimica Acta is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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DbLabel: Engineering Source
An: 192228683
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  Data: Province-scale tin and zinc stable isotope fractionation trends in the Bolivian tin belt.
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  Data: <searchLink fieldCode="AR" term="%22Hirsh%2C+Evan+C%2E%22">Hirsh, Evan C.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Simon%2C+Adam+C%2E%22">Simon, Adam C.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> simonac@umich.edu</i><br /><searchLink fieldCode="AR" term="%22Mathur%2C+Ryan%22">Mathur, Ryan</searchLink><relatesTo>2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Powell%2C+Wayne%22">Powell, Wayne</searchLink><relatesTo>3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Megaw%2C+Peter%22">Megaw, Peter</searchLink><relatesTo>4</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Asael%2C+Dan%22">Asael, Dan</searchLink><relatesTo>5</relatesTo> (AUTHOR)
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  Data: <searchLink fieldCode="JN" term="%22Geochimica+et+Cosmochimica+Acta%22">Geochimica et Cosmochimica Acta</searchLink>. Mar2026, Vol. 417, p256-268. 13p.
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  Data: <searchLink fieldCode="DE" term="%22Isotopic+fractionation%22">Isotopic fractionation</searchLink><br /><searchLink fieldCode="DE" term="%22Tin+isotopes%22">Tin isotopes</searchLink><br /><searchLink fieldCode="DE" term="%22Fluid+inclusions%22">Fluid inclusions</searchLink><br /><searchLink fieldCode="DE" term="%22Sphalerite%22">Sphalerite</searchLink><br /><searchLink fieldCode="DE" term="%22Hydrothermal+deposits%22">Hydrothermal deposits</searchLink><br /><searchLink fieldCode="DE" term="%22Cassiterite%22">Cassiterite</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: The Sn and Zn stable isotope compositions of cassiterite and sphalerite have been widely used to understand the formation of magmatic-hydrothermal Sn and Zn mineral deposits. Here, we report Sn isotopic compositions of cassiterite and Zn isotopic compositions of paragenetically later, lower-temperature sphalerite from ten Sn and Zn-bearing polymetallic deposits in the Bolivian tin belt. These deposits represent distinct mineralization styles and metal transport pathways. The δ124Sn values for cassiterite vary from −0.56 to 1.64‰ (n = 33) and δ66Zn values for sphalerite vary from −0.22 to 0.92‰ (n = 20), encompassing much of the global variance observed for each isotopic system. The Llallagua and Huanuni deposits show significantly heavier Sn isotope compositions (average = 1.24 ± 0.24‰ δ124Sn; n = 10) compared to all other deposits (average = 0.56 ± 0.55‰; n = 23) and contain several distinguishing geological attributes including: genetic association with porphyry phase stocks and/or dikes, vapor-rich and moderately to highly saline fluid inclusions, vertically restricted and/or discontinuous high-grade veins, and extensive tourmaline-rich magmatic-hydrothermal breccias. Together, these features are consistent with Rayleigh fractionation and suggest that orthomagmatic fluid separation, fluid boiling, and oxidation contributed to cassiterite precipitation and caused Sn isotope fractionation. The residual fluids after cassiterite precipitation were depleted in heavy Sn isotopes and propagated along district-scale fluid pathways. The Sn isotopic ranges for cassiterite from the Sayaquira (−0.13–1.45‰), Colquiri (0.18–1.44‰), Colcha (0.07–1.47‰), and Monserrat (−0.56–0.93‰) deposits may be a consequence of cassiterite precipitation over longer mineralization length scales with increased meteoric water influx, where distal cassiterite precipitated from hydrothermal ore fluid that was depleted in heavy 124Sn. The wide and heavy range of Zn isotopic compositions of sphalerite suggests that early orthomagmatic fluid separation and boiling may have caused significant isotopic fractionation during early fluid transport prior to sphalerite precipitation. Subsequent processes including dilution by Sn- and Zn-poor meteoric water and the concomitant change in fluid pH and increase in oxygen fugacity plausibly contributed to the precipitation of isotopically lighter sphalerite at the Monserrat, El Salvador, and Huari Huari deposits. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Geochimica et Cosmochimica Acta is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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RecordInfo BibRecord:
  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.1016/j.gca.2026.01.048
    Languages:
      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 13
        StartPage: 256
    Subjects:
      – SubjectFull: Isotopic fractionation
        Type: general
      – SubjectFull: Tin isotopes
        Type: general
      – SubjectFull: Fluid inclusions
        Type: general
      – SubjectFull: Sphalerite
        Type: general
      – SubjectFull: Hydrothermal deposits
        Type: general
      – SubjectFull: Cassiterite
        Type: general
    Titles:
      – TitleFull: Province-scale tin and zinc stable isotope fractionation trends in the Bolivian tin belt.
        Type: main
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          Name:
            NameFull: Hirsh, Evan C.
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            NameFull: Simon, Adam C.
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            NameFull: Mathur, Ryan
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            NameFull: Powell, Wayne
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            NameFull: Megaw, Peter
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            NameFull: Asael, Dan
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            – D: 15
              M: 03
              Text: Mar2026
              Type: published
              Y: 2026
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              Value: 00167037
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              Value: 417
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            – TitleFull: Geochimica et Cosmochimica Acta
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