Econ. Environ. Geol. 2003; 36(5): 321-328

Published online October 31, 2003

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Geologic, Fluid Inclusion, and Sulfur Isotopic Studies of Hydrothermal Deposit in the Tanggueng District, West Java, Indonesia

Jae-Ho Lee* and In-Joon Kim

Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Korea

Correspondence to :

Jae-Ho Lee

jhlee@kigam.re.kr

Received: June 27, 2003; Accepted: August 17, 2003

Abstract

The epithermal gold and base metal deposit of the Tanggeung district of West Java consists of four major veins(Celak, Cigodobras, Cilangkap and Pasirbedil) with NS to N10o~20oE and N75oW strikes. The veins occur within fractures cutting the crystal and lithic tuff of Jampang Formation(Oligo-Miocene) in and around the Mt. Subang of the western Java, Indonesia. The ore mineralization is characterized by the occurrence of pyrite, sphalerite, galena, chalcopyrite, and small amounts of bornite and Fe-oxides. Hydrothermal alteration, associated with the mineralization, was dominantly silicified and enveloped by the phyllitic(sericitic), argillic and propylitic alteration containing the disseminated pyrite. Gangue minerals consist of interstratified smectite-illite, chlorite, sericite, and minor kaolinite. The presence of vapor-rich fluid inclusions in quartz veins suggests that boiling occurred locally throughout ore deposition. Fluid inclusion studies suggest that the ore fluid evolved from initial high temperatures(?340oC) to later lower temperatures(?190oC). Salinities range from 0.0 to 8.3 wt percent NaCl equiv. The relatively high increase in salinity(up to 8.3 wt percent NaCl equiv) might be explained by a local boiling and by a participation of magmatic fluids, supported by the sulfur isotope results. Evidence of fluid boiling suggests that the pressure decreased from 200 bars to 120bars. This corresponds to the depths of approximately 750 to 1,2 00m in a hydrothermal system that changed from lithostatic to hydrostatic conditions. Using homogenization temperatures and paragenetic
constraints, the calculated δ34S values of H2S in ore fluid are -0.2 to 1.8permil close to the 0permil isotopic value of magmatic sulfur.

Keywords Epithermal deposit, alteration, mineralization, fluid inclusion, sulfur isotope

Article

Econ. Environ. Geol. 2003; 36(5): 321-328

Published online October 31, 2003

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Geologic, Fluid Inclusion, and Sulfur Isotopic Studies of Hydrothermal Deposit in the Tanggueng District, West Java, Indonesia

Jae-Ho Lee* and In-Joon Kim

Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Korea

Correspondence to:

Jae-Ho Lee

jhlee@kigam.re.kr

Received: June 27, 2003; Accepted: August 17, 2003

Abstract

The epithermal gold and base metal deposit of the Tanggeung district of West Java consists of four major veins(Celak, Cigodobras, Cilangkap and Pasirbedil) with NS to N10o~20oE and N75oW strikes. The veins occur within fractures cutting the crystal and lithic tuff of Jampang Formation(Oligo-Miocene) in and around the Mt. Subang of the western Java, Indonesia. The ore mineralization is characterized by the occurrence of pyrite, sphalerite, galena, chalcopyrite, and small amounts of bornite and Fe-oxides. Hydrothermal alteration, associated with the mineralization, was dominantly silicified and enveloped by the phyllitic(sericitic), argillic and propylitic alteration containing the disseminated pyrite. Gangue minerals consist of interstratified smectite-illite, chlorite, sericite, and minor kaolinite. The presence of vapor-rich fluid inclusions in quartz veins suggests that boiling occurred locally throughout ore deposition. Fluid inclusion studies suggest that the ore fluid evolved from initial high temperatures(?340oC) to later lower temperatures(?190oC). Salinities range from 0.0 to 8.3 wt percent NaCl equiv. The relatively high increase in salinity(up to 8.3 wt percent NaCl equiv) might be explained by a local boiling and by a participation of magmatic fluids, supported by the sulfur isotope results. Evidence of fluid boiling suggests that the pressure decreased from 200 bars to 120bars. This corresponds to the depths of approximately 750 to 1,2 00m in a hydrothermal system that changed from lithostatic to hydrostatic conditions. Using homogenization temperatures and paragenetic
constraints, the calculated δ34S values of H2S in ore fluid are -0.2 to 1.8permil close to the 0permil isotopic value of magmatic sulfur.

Keywords Epithermal deposit, alteration, mineralization, fluid inclusion, sulfur isotope

    KSEEG
    Jun 30, 2024 Vol.57 No.3, pp. 281~352

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