* Corresponding Author
Characteristics Of Hydrothermal Alteration In Cijulang Area, West Java, Indonesia
https://doi.org/10.22146/jag.16917 Myo Min Tun(1), I Wayan Warmada(2*), Agung Harijoko(3), Reza Al-Furqan(4), Koichiro Watanabe(5)
(1) Department of Geology, Mandalay University, Mandalay, Myanmar
(2) Geological Engineering Department, Faculty of Engineering, Gadjah Mada University
(3) Geological Engineering Department, Faculty of Engineering, Gadjah Mada University
(4) PT. Eksplorasi Nusa Jaya/Freeport-McMoran Copper & Gold
(5) Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University
(*) Corresponding Author
Abstract
Characterization of hydrothermal alteration in the
Cijulang area (West Java, Indonesia) was carried
out using shortwave infrared spectroscopy. Hydrothermal alteration in the Cijulang area occurs in the calc-alkaline volcanic and volcaniclastic rocks. Shortwave infrared spectroscopic measurements of reflectance for altered rocks and minerals were carried out by ASD-FieldSpec and the laboratory spectra acquired were then analysed with “The Spectral Geologist” software program. Shortwave infrared spectroscopy is capable of detecting most finegrained alteration minerals from different hydrothermal alteration zones. Characteristic alteration minerals identified from the SWIR technique include pyrophyllite, alunite, kaolinite, dickite, illite, montmorillonite, polygorskite, gypsum, epidote, paragonite, and muscovite. Most of the spectra show mixture of
alteration minerals and only a few display pure spectra of single mineral. The crystallinity of kaolinite from the samples was also determined from the reflectance spectra and show moderately to high crystallinity. Alteration system of the Cijulang prospect
is similar to others documented high-sulfidation epithermal deposits, such as Rodalquilar (Spain), Summitville (Colorado), and Lepanto (Philippines). A characteristic alteration sequence and zonation of advanced argillic, argillic and propylitic alteration
outward from the silica core has resulted from the progressive cooling and neutralization of hot acidic magmatic fluid with the host rocks.
Keywords: Cijulang, High-sulfidation, Alteration minerals, Shortwave Infrared Spectroscopy
Cijulang area (West Java, Indonesia) was carried
out using shortwave infrared spectroscopy. Hydrothermal alteration in the Cijulang area occurs in the calc-alkaline volcanic and volcaniclastic rocks. Shortwave infrared spectroscopic measurements of reflectance for altered rocks and minerals were carried out by ASD-FieldSpec and the laboratory spectra acquired were then analysed with “The Spectral Geologist” software program. Shortwave infrared spectroscopy is capable of detecting most finegrained alteration minerals from different hydrothermal alteration zones. Characteristic alteration minerals identified from the SWIR technique include pyrophyllite, alunite, kaolinite, dickite, illite, montmorillonite, polygorskite, gypsum, epidote, paragonite, and muscovite. Most of the spectra show mixture of
alteration minerals and only a few display pure spectra of single mineral. The crystallinity of kaolinite from the samples was also determined from the reflectance spectra and show moderately to high crystallinity. Alteration system of the Cijulang prospect
is similar to others documented high-sulfidation epithermal deposits, such as Rodalquilar (Spain), Summitville (Colorado), and Lepanto (Philippines). A characteristic alteration sequence and zonation of advanced argillic, argillic and propylitic alteration
outward from the silica core has resulted from the progressive cooling and neutralization of hot acidic magmatic fluid with the host rocks.
Keywords: Cijulang, High-sulfidation, Alteration minerals, Shortwave Infrared Spectroscopy
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PDF DOI: https://doi.org/10.22146/jag.16917
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Copyright (c) 2015 Myo Min Tun, I Wayan Warmada, Agung Harijoko, Reza Al-Furqan, Koichiro Watanabe
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