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<p>Tin-tungsten-rubidium mineralization is typically associated with magmatic–hydrothermal processes. To examine the transition and mineralization processes from the late magmatic to hydrothermal stages, a comprehensive geochemical-geochronological investigation on monazite, cassiterite, and wolframite, together with bulk-rock compositions and petrology was carried out on the Xiwukou Sn–W–Rb polymetallic deposit and its associated granites in the eastern segment of the Jiangnan Orogenic Belt (JOB), South China. Field observations revealed that altered granite–greisen-type Sn–Rb ore bodies occur in the upper part of the intrusion, while quartz vein-type Sn–W ore bodies are hosted mainly in Silurian sedimentary country rocks. LA-ICP-MS U–Pb dating of monazite from the Xiwukou pluton delineates two distinct magmatic stages: 139.9 ± 1.0&#xa0;Ma for porphyritic granite (Granite Ⅰ) and 129.0 ± 0.7&#xa0;Ma for porphyritic biotite granite (Granite Ⅱ). Monazite from altered granite and altered granite-type Sn ore yielded consistent ages of 129.3 ± 0.8 and 128.9 ± 1.3&#xa0;Ma, respectively. Furthermore, cassiterite and wolframite dating directly constrained the Sn mineralization from 128.9 ± 0.9&#xa0;Ma (altered granite-type) to 126.4 ± 1.5&#xa0;Ma (quartz vein-type), while the W mineralization in wolframite–topaz–quartz veins formed from 127.4 ± 1.4 to 125.5 ± 2.0&#xa0;Ma. The monazite geochemistry revealed systematic compositional variations during the magmatic–hydrothermal evolution, characterized by decreasing Th contents, increasing Eu anomalies, and enhanced LREE-HREE differentiation from the granite and altered granite to the Sn ores. Integrated with the whole-rock geochemistry of the granites and tectonic setting of the JOB during this period, we conclude that emplacement of porphyritic biotite granite at ca. 129&#xa0;Ma occurred in an extensional setting, which triggered the primary Sn–W metallogenetic event.</p>

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Magmatic–hydrothermal mineralization processes in the Xiwukou Sn–W–Rb deposit, Jiangnan orogenic belt: Constraints from multi-mineral U–Pb geochronology

  • 期刊论文

  • 发表日期：

    2026年3月23日

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  • Kun-Yan Wu,
  • Xiao-Ying Gao,
  • Qi Hou,
  • Xiao-Yong Yang,
  • Qiu Wan,
  • Xiang Qian,
  • Fu-Jun Zhong,
  • Gen-Tao Zhou

摘要

Tin-tungsten-rubidium mineralization is typically associated with magmatic–hydrothermal processes. To examine the transition and mineralization processes from the late magmatic to hydrothermal stages, a comprehensive geochemical-geochronological investigation on monazite, cassiterite, and wolframite, together with bulk-rock compositions and petrology was carried out on the Xiwukou Sn–W–Rb polymetallic deposit and its associated granites in the eastern segment of the Jiangnan Orogenic Belt (JOB), South China. Field observations revealed that altered granite–greisen-type Sn–Rb ore bodies occur in the upper part of the intrusion, while quartz vein-type Sn–W ore bodies are hosted mainly in Silurian sedimentary country rocks. LA-ICP-MS U–Pb dating of monazite from the Xiwukou pluton delineates two distinct magmatic stages: 139.9 ± 1.0 Ma for porphyritic granite (Granite Ⅰ) and 129.0 ± 0.7 Ma for porphyritic biotite granite (Granite Ⅱ). Monazite from altered granite and altered granite-type Sn ore yielded consistent ages of 129.3 ± 0.8 and 128.9 ± 1.3 Ma, respectively. Furthermore, cassiterite and wolframite dating directly constrained the Sn mineralization from 128.9 ± 0.9 Ma (altered granite-type) to 126.4 ± 1.5 Ma (quartz vein-type), while the W mineralization in wolframite–topaz–quartz veins formed from 127.4 ± 1.4 to 125.5 ± 2.0 Ma. The monazite geochemistry revealed systematic compositional variations during the magmatic–hydrothermal evolution, characterized by decreasing Th contents, increasing Eu anomalies, and enhanced LREE-HREE differentiation from the granite and altered granite to the Sn ores. Integrated with the whole-rock geochemistry of the granites and tectonic setting of the JOB during this period, we conclude that emplacement of porphyritic biotite granite at ca. 129 Ma occurred in an extensional setting, which triggered the primary Sn–W metallogenetic event.