Barium isotope variations in highly-fractionated granites linked to tin mineralization: new insights into tin recycling and enrichment in the continental crust
Barium isotope variations in highly-fractionated granites linked to tin mineralization: new insights into tin recycling and enrichment in the continental crust
Most primary tin deposits are intimately associated with highly-fractionated granites (HFGs), but the factors controlling the formation of tin mineralization; including source enrichment, partial melting, fractional crystallization, and fluid processes, are still subject to debate. The potassium-rich Yanbei volcanic-intrusive complex is part of the world-class Nanling W–Sn metallogenic belt in South China and contains both barren and Sn-rich igneous rocks. We report here Ba isotope compositions of these rocks in an effort to elucidate the relationship between HFGs and related Sn mineralization. Overall, the results show δ
138/134Ba values ranging widely from −0.83 to +0.21‰. The δ
138/134Ba of the barren volcanic rocks (−0.11 to +0.21‰) are correlated with SiO
2, Sr, and Ba contents, and Eu/Eu* values in a manner indicating that fractional crystallization is the main control over their Ba isotope variation. The most fractionated volcanic rocks have the highest δ
138/134Ba due to crystallization of alkali-feldspar rich in light Ba isotopes. In contrast, the highly-fractionated tin granites have low Ba contents and δ
138/134Ba values of −0.83 to −0.23‰. These low values cannot be explained by either addition of mantle-sourced melts and magmatic fluids, or fractional crystallization and fluid circulation at the shallow emplacement level. Rather, these geochemical features are likely inherited from an isotopically lighter crustal source with enhanced tin contents related to the recycling of intensely chemically weathered sediments. When combined with bulk-rock chemical data, the Ba isotope data suggest that assimilation of this tin-enriched source played a key role in forming the tin granites and related tin deposits.
Barium isotope, Highly-evolved granite, South China, The Yanbei Sn deposit, Tin mineralization
Li, Qian
e8950786-8f13-45ac-9a4d-8942268fe32c
Zhao, Kui-Dong
bd5bd864-d7d0-40b4-ae43-37cdc7632a37
Zhu, Zhi-Yong
840cb2ca-fd1c-4fda-9952-2b9f6c273606
Palmer, Martin R.
d2e60e81-5d6e-4ddb-a243-602537286080
Chen, Wei
a10d22f3-d9cc-4769-8e16-d04ee6f33dd3
Jiang, Shao-Yong
dc929006-69ac-4366-bf2b-dc97527602d3
5 January 2024
Li, Qian
e8950786-8f13-45ac-9a4d-8942268fe32c
Zhao, Kui-Dong
bd5bd864-d7d0-40b4-ae43-37cdc7632a37
Zhu, Zhi-Yong
840cb2ca-fd1c-4fda-9952-2b9f6c273606
Palmer, Martin R.
d2e60e81-5d6e-4ddb-a243-602537286080
Chen, Wei
a10d22f3-d9cc-4769-8e16-d04ee6f33dd3
Jiang, Shao-Yong
dc929006-69ac-4366-bf2b-dc97527602d3
Li, Qian, Zhao, Kui-Dong, Zhu, Zhi-Yong, Palmer, Martin R., Chen, Wei and Jiang, Shao-Yong
(2024)
Barium isotope variations in highly-fractionated granites linked to tin mineralization: new insights into tin recycling and enrichment in the continental crust.
Chemical Geology, 646, [121914].
(doi:10.1016/j.chemgeo.2023.121914).
Abstract
Most primary tin deposits are intimately associated with highly-fractionated granites (HFGs), but the factors controlling the formation of tin mineralization; including source enrichment, partial melting, fractional crystallization, and fluid processes, are still subject to debate. The potassium-rich Yanbei volcanic-intrusive complex is part of the world-class Nanling W–Sn metallogenic belt in South China and contains both barren and Sn-rich igneous rocks. We report here Ba isotope compositions of these rocks in an effort to elucidate the relationship between HFGs and related Sn mineralization. Overall, the results show δ
138/134Ba values ranging widely from −0.83 to +0.21‰. The δ
138/134Ba of the barren volcanic rocks (−0.11 to +0.21‰) are correlated with SiO
2, Sr, and Ba contents, and Eu/Eu* values in a manner indicating that fractional crystallization is the main control over their Ba isotope variation. The most fractionated volcanic rocks have the highest δ
138/134Ba due to crystallization of alkali-feldspar rich in light Ba isotopes. In contrast, the highly-fractionated tin granites have low Ba contents and δ
138/134Ba values of −0.83 to −0.23‰. These low values cannot be explained by either addition of mantle-sourced melts and magmatic fluids, or fractional crystallization and fluid circulation at the shallow emplacement level. Rather, these geochemical features are likely inherited from an isotopically lighter crustal source with enhanced tin contents related to the recycling of intensely chemically weathered sediments. When combined with bulk-rock chemical data, the Ba isotope data suggest that assimilation of this tin-enriched source played a key role in forming the tin granites and related tin deposits.
Text
Li et al 2024
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Accepted/In Press date: 26 December 2023
e-pub ahead of print date: 30 December 2023
Published date: 5 January 2024
Additional Information:
Funding Information: this work is supported by the National Natural Science Foundation of China Projects (No. 42321001 , No. 91755208 , No. 42073015 , No. 42302091 ). Qian Li is also grateful for the financial support of the Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) . The authos would like to thank Dr. Marco Fiorentini, Dr. Jason Bennett and Dr. Patrick Carr for their constructive comments which significantly improve the manuscript.
Keywords:
Barium isotope, Highly-evolved granite, South China, The Yanbei Sn deposit, Tin mineralization
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Local EPrints ID: 486786
URI: http://eprints.soton.ac.uk/id/eprint/486786
ISSN: 0009-2541
PURE UUID: bceba21a-9359-438b-b664-3b12b9cd5612
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Date deposited: 06 Feb 2024 17:38
Last modified: 17 Mar 2024 06:56
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Contributors
Author:
Kui-Dong Zhao
Author:
Zhi-Yong Zhu
Author:
Wei Chen
Author:
Shao-Yong Jiang
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