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<p>Southeast China hosts extensive Late Mesozoic metallogenic systems, including metallic and non-metallic deposits genetically linked to tectonic-thermal events. Central Zhejiang Province, a major fluorite-producing region in China, exhibits spatiotemporal relationships with the Cretaceous magmatic-hydrothermal activity. In this study, zircon U–Pb and fluorite Sm–Nd geochronology, whole-rock/mineral geochemistry, Sr–Nd–H–O–Ca isotopes, and fluid inclusion microthermometry were used to constrain the genesis of the Shanwang fluorite deposit in the Mazhai caldera, central Zhejiang. Fluorite orebodies are structurally controlled by intracaldera faults and contain fluorite–quartz–barite–pyrite–pyrophyllite assemblages. Geochronological data revealed that fluorite mineralization (77&#xa0;Ma, Sm–Nd isochron age) postdated the Early Cretaceous caldera-forming volcanism (128–125&#xa0;Ma, zircon U–Pb age). Fluid inclusion data indicated low-temperature (128–184&#xa0;°C) and low-salinity (0.2–8.8 wt.% NaCl eqv.) hydrothermal conditions. Stable isotopes (δD<sub>VSMOW</sub> = -101.8‰ to -64.9‰, δ<sup>18</sup>O<sub>VSMOW</sub> = -10.4‰ to -6.9‰) confirm meteoric water-dominated fluids. Integrated Sr–Nd–Ca isotopes (fluorite δ<sup>44/40</sup>Ca values = 1.29–1.35‰) and trace element characteristics demonstrate that ore-forming materials were primarily leached from volcanic rocks via meteoric water–rock interaction in a paleo-geothermal system, with subsequent migration along fault zones leading to fluorite precipitation. Mineralization is correlated with Late Cretaceous lithospheric extension driven by the Paleo-Pacific slab rollback beneath Southeast China.</p>

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Geochronology, geochemistry and genesis of the Shanwang fluorite deposit in central Zhejiang, SE China: implications for hydrothermal evolution within a pre-existing caldera

  • 期刊论文

  • 发表日期：

    2025年11月26日

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  • Xi-Yao Li,
  • Chong Jin,
  • Weijun Xu,
  • Sanzhong Li,
  • Xianzhi Cao,
  • Fengjian Ge,
  • Pengcheng Wang,
  • Liyong Gong

摘要

Southeast China hosts extensive Late Mesozoic metallogenic systems, including metallic and non-metallic deposits genetically linked to tectonic-thermal events. Central Zhejiang Province, a major fluorite-producing region in China, exhibits spatiotemporal relationships with the Cretaceous magmatic-hydrothermal activity. In this study, zircon U–Pb and fluorite Sm–Nd geochronology, whole-rock/mineral geochemistry, Sr–Nd–H–O–Ca isotopes, and fluid inclusion microthermometry were used to constrain the genesis of the Shanwang fluorite deposit in the Mazhai caldera, central Zhejiang. Fluorite orebodies are structurally controlled by intracaldera faults and contain fluorite–quartz–barite–pyrite–pyrophyllite assemblages. Geochronological data revealed that fluorite mineralization (77 Ma, Sm–Nd isochron age) postdated the Early Cretaceous caldera-forming volcanism (128–125 Ma, zircon U–Pb age). Fluid inclusion data indicated low-temperature (128–184 °C) and low-salinity (0.2–8.8 wt.% NaCl eqv.) hydrothermal conditions. Stable isotopes (δDVSMOW = -101.8‰ to -64.9‰, δ18OVSMOW = -10.4‰ to -6.9‰) confirm meteoric water-dominated fluids. Integrated Sr–Nd–Ca isotopes (fluorite δ44/40Ca values = 1.29–1.35‰) and trace element characteristics demonstrate that ore-forming materials were primarily leached from volcanic rocks via meteoric water–rock interaction in a paleo-geothermal system, with subsequent migration along fault zones leading to fluorite precipitation. Mineralization is correlated with Late Cretaceous lithospheric extension driven by the Paleo-Pacific slab rollback beneath Southeast China.