Crucial control on magmatic-hydrothermal Sn deposit in the Tengchong block, SW China: Evidence from magma differentiation and zircon geochemistry
Magmatic-hydrothermal Sn deposits are commonly associated with high silica magmas, but why most global high silica granites do not bear economic Sn ore grades remains unclear. Two crucial factors controlling magmatic-hydrothermal Sn mineralization, including advanced fractionation and depressurizati...
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| Format: | Article |
| Language: | English |
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Elsevier
2022-07-01
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| Series: | Geoscience Frontiers |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S1674987122000548 |
| _version_ | 1797704506788544512 |
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| author | Qiwei Zhang Qingfei Wang Gongjian Li Xiang Sun Qihai Shu Jun Deng |
| author_facet | Qiwei Zhang Qingfei Wang Gongjian Li Xiang Sun Qihai Shu Jun Deng |
| author_sort | Qiwei Zhang |
| collection | DOAJ |
| description | Magmatic-hydrothermal Sn deposits are commonly associated with high silica magmas, but why most global high silica granites do not bear economic Sn ore grades remains unclear. Two crucial factors controlling magmatic-hydrothermal Sn mineralization, including advanced fractionation and depressurization-induced rapid cooling, were revealed in the case study of the Guyong granitic pluton linked with the Xiaolonghe Sn deposit, in the Tengchong block, SW China. The Guyong granitic pluton comprises three petrological facies: less evolved biotite syenogranite, evolved alkali granite and leucogranite, and highly evolved facies (the protolith of greisenized granite). Similar crystallization ages (∼77 Ma) and gradual contact between different petrological facies indicate the Guyong granitic pluton records a continuous fractionation process. Monte Carlo-revised Rayleigh fractionation model suggests the fractionation degree of the Guyong pluton is markedly high (>87 wt.%) that can only be achieved by a high initial water (≥4 wt.%) content in the parent granitic magma revealed by rhyolite-MELTS calculation. Advanced degree fractionation causes the first Sn enrichment but it also significantly increases the viscosity of evolved magmas, suppressing the exsolution and transport of hydrothermal fluids. Hence, it must be compensated by the second critical factor: depressurization-induced rapid cooling, reflected by the occurrence of highly metamict zircons in the greisenized granite. The highly metamict feature, indicated by the large full width at half maximum (FWHM) values of zircon ν3(SiO4) peak (>19.5 cm−1), suggests these zircons do not experience thermal annealing but rapidly ascend into a shallow cooling environment. Depressurization-induced rapid cooling facilitates exsolution and transport of hydrothermal fluids, interacting with wall rocks and resulting in Sn mineralization. |
| first_indexed | 2024-03-12T05:21:25Z |
| format | Article |
| id | doaj.art-1b3195e5c5d4407a9cbe70ddb8cfe741 |
| institution | Directory Open Access Journal |
| issn | 1674-9871 |
| language | English |
| last_indexed | 2024-03-12T05:21:25Z |
| publishDate | 2022-07-01 |
| publisher | Elsevier |
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| series | Geoscience Frontiers |
| spelling | doaj.art-1b3195e5c5d4407a9cbe70ddb8cfe7412023-09-03T07:38:55ZengElsevierGeoscience Frontiers1674-98712022-07-01134101401Crucial control on magmatic-hydrothermal Sn deposit in the Tengchong block, SW China: Evidence from magma differentiation and zircon geochemistryQiwei Zhang0Qingfei Wang1Gongjian Li2Xiang Sun3Qihai Shu4Jun Deng5State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China; Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2R3, CanadaState Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China; Corresponding author.State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, ChinaState Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, ChinaState Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, ChinaState Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, ChinaMagmatic-hydrothermal Sn deposits are commonly associated with high silica magmas, but why most global high silica granites do not bear economic Sn ore grades remains unclear. Two crucial factors controlling magmatic-hydrothermal Sn mineralization, including advanced fractionation and depressurization-induced rapid cooling, were revealed in the case study of the Guyong granitic pluton linked with the Xiaolonghe Sn deposit, in the Tengchong block, SW China. The Guyong granitic pluton comprises three petrological facies: less evolved biotite syenogranite, evolved alkali granite and leucogranite, and highly evolved facies (the protolith of greisenized granite). Similar crystallization ages (∼77 Ma) and gradual contact between different petrological facies indicate the Guyong granitic pluton records a continuous fractionation process. Monte Carlo-revised Rayleigh fractionation model suggests the fractionation degree of the Guyong pluton is markedly high (>87 wt.%) that can only be achieved by a high initial water (≥4 wt.%) content in the parent granitic magma revealed by rhyolite-MELTS calculation. Advanced degree fractionation causes the first Sn enrichment but it also significantly increases the viscosity of evolved magmas, suppressing the exsolution and transport of hydrothermal fluids. Hence, it must be compensated by the second critical factor: depressurization-induced rapid cooling, reflected by the occurrence of highly metamict zircons in the greisenized granite. The highly metamict feature, indicated by the large full width at half maximum (FWHM) values of zircon ν3(SiO4) peak (>19.5 cm−1), suggests these zircons do not experience thermal annealing but rapidly ascend into a shallow cooling environment. Depressurization-induced rapid cooling facilitates exsolution and transport of hydrothermal fluids, interacting with wall rocks and resulting in Sn mineralization.http://www.sciencedirect.com/science/article/pii/S1674987122000548Magmatic-hydrothermal Sn depositsMetamict zirconsFractionationRaman spectraThermodynamic modeling |
| spellingShingle | Qiwei Zhang Qingfei Wang Gongjian Li Xiang Sun Qihai Shu Jun Deng Crucial control on magmatic-hydrothermal Sn deposit in the Tengchong block, SW China: Evidence from magma differentiation and zircon geochemistry Geoscience Frontiers Magmatic-hydrothermal Sn deposits Metamict zircons Fractionation Raman spectra Thermodynamic modeling |
| title | Crucial control on magmatic-hydrothermal Sn deposit in the Tengchong block, SW China: Evidence from magma differentiation and zircon geochemistry |
| title_full | Crucial control on magmatic-hydrothermal Sn deposit in the Tengchong block, SW China: Evidence from magma differentiation and zircon geochemistry |
| title_fullStr | Crucial control on magmatic-hydrothermal Sn deposit in the Tengchong block, SW China: Evidence from magma differentiation and zircon geochemistry |
| title_full_unstemmed | Crucial control on magmatic-hydrothermal Sn deposit in the Tengchong block, SW China: Evidence from magma differentiation and zircon geochemistry |
| title_short | Crucial control on magmatic-hydrothermal Sn deposit in the Tengchong block, SW China: Evidence from magma differentiation and zircon geochemistry |
| title_sort | crucial control on magmatic hydrothermal sn deposit in the tengchong block sw china evidence from magma differentiation and zircon geochemistry |
| topic | Magmatic-hydrothermal Sn deposits Metamict zircons Fractionation Raman spectra Thermodynamic modeling |
| url | http://www.sciencedirect.com/science/article/pii/S1674987122000548 |
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