Fluid phase separation promotes mineralization of epithermal base metal sulfides: A case study from the Central Seruyan Pb-Zn-Cu deposit in Kalimantan, Indonesia
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2025-11
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Journal Article
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yes
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Abstract
The Central Seruyan Pb-Zn-Cu deposit in Central Kalimantan is an epithermal deposit situated within the Central Borneo metallogenic belt. To develop a genetic model for this deposit and provide insights for future exploration, we conducted studies on petrography, fluid inclusions, trace element geochemistry of sulfide minerals, and Pb isotope compositions. The mineralization can be categorized into four hydrothermal stages, based on the characteristics of alteration and ore mineral assemblages. The primary base metal sulfide minerals in the main ore stage include galena, sphalerite, and chalcopyrite, with minor amounts of covellite and tetrahedrite-tennantite. The principal Pb-Zn-Cu mineralization occurred under temperatures ranging from 170 to 320 ℃ at an apparent depth of 0.1 to 0.4 km from the paleosurface.
Petrographic analysis and fluid inclusion microthermometry suggest that fluid boiling and decompression-induced quenching were the dominant processes driving base metal mineralization. The heterogeneous trace element distribution and color zonation observed in sulfide minerals further indicate an abrupt temperature change during the main mineralization stage. Arsenic and gold zonation in pyrite, along with indium and gallium zonation in sphalerite, suggest rapid temperature fluctuations likely associated with boiling. Microanalyses of fluid inclusions in sphalerite reveal that the ore-forming fluids originated from subduction-related magmas undergoing batholith-scale fractionation. For future exploration, we recommend targeting SW-NE trending faults, which may have facilitated decompression and subsequent boiling.
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published
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Volume
186
Pages / Article No.
106925
Publisher
Elsevier
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Subject
Magmatic-hydrothermal fluid; Pb-Zn-Cu epithermal deposit; Fluid inclusion; Trace element geochemistry; Pb isotope; Phase separation
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03958 - Bachmann, Olivier / Bachmann, Olivier