Geology, Geochemistry and Hydrothermal Fluid Characteristics of Low Sulfidation Epithermal Deposit in the Sangon Area, Kokap, Special Region of Yogyakarta

https://doi.org/10.22146/jag.42442

Pranayoga Pramumijoyo(1*), Arifudin Idrus(2), I Wayan Warmada(3), Kotaro Yonezu(4)

(1) Department of Geological Engineering, Faculty of Engineering, Gadjah Mada University
(2) Department of Geological Engineering, Faculty of Engineering, Gadjah Mada University
(3) Department of Geological Engineering, Faculty of Engineering, Gadjah Mada University
(4) Department of Earth Resources Engineering, Kyushu University
(*) Corresponding Author

Abstract


On the basis of the previous studies and reconnaissance survey in the study
area covering Sangon, Kalirejo, Kokap Sub-district, Kulon Progo Regency, Special Region of Yogyakarta, it reveals some facts of the occurrence of quartz veins with massive, crustiform, comb, drusy cavity, saccharoidal, granular, and reniform/mammillated textures, the appearance of lattice bladed barite and hydrothermal breccia veins. Referring to those characteristics, the deposit type in the study area is interpreted to be low sulfidation epithermal type. This study is aimed to understand and characterize the geological condition, rock and ore geochemistry and the mineralizing fluids. The alteration and ore mineralization are almost observed in entire rock units particularly the intrusive andesite 1. Their formation is controlled by the tension fractures (NW–SE and NE–SW) which associate with sinistral strike slip faults (NE–SW), dilational jog (NNW–SSE), oblique normal fault (WNW–ESE), and predictable normal fault at the NE of study area (NW–SE). The alteration zones are developed to be silica-clay (quartz-illite-kaolinite-kaolinite/smectite), argillic (smectite-illite/smectite), and propylitic (chlorite-calcite±epidote). The precipitation
of ore minerals is controlled by boiling, mixing, and wall-rock alteration, and can
be found in the quartz veins (quartz-adularia-sericite) and disseminated in the alteration zones, which their high variability is only can be found in the quartz veins, including pyrite, sphalerite, chalcopyrite, galena, marcasite, and arsenopyrite. Based on the ICPAES measurement of 5 quartz vein samples, the Cu, Zn, Pb, and As grade reach about 5,171 ppm, 8,995 ppm, 6,398 ppm, 34.1 ppm, and 1,010.5 ppm, respectively. Gold is not detected. Fluid inclusion microthermometric analysis shows Th of 242.1–257.6 °C and salinity of 1.57–3.87 wt.% NaCl equiv., which indicate a depth below the paleosurface of 384–516 m, and pressure of 101.7–136.6 bar. The ore deposit in the study area is interpreted to be a deep basemetal low sulfidation epithermal type. Gold might be depleted in this epithermal type.

Keywords


Low sulfidation epithermal - Andesite - Alteration - Ore mineralization - Hydrothermal fluid - Sangon

Full Text:

PDF


References

Carlile, J.C., Mitchell, A.H.G. (1994) Magmatic Arcs and Associated Gold and Copper Mineralization

in Indonesia, Journal of Geochemical Exploration 50: 91–142.

Cooke, D.R., Simmons, S.F. (2000) Characteristics and Genesis of Epithermal Gold Deposits, In: SEG Reviews 13: 221–224.

Harjanto, A. (2011) Volkanostratigrafi di Daerah Kulon Progo dan Sekitarnya, Daerah Istimewa Yogyakarta, Jurnal Ilmiah MTG 4: 30–46.

Hedenquist, J.W., Arribas, A., Jr., Gonzalez-Urien, E. (2000) Exploration for Epithermal Gold Deposits,

In: SEG Reviews, Economic Geology 13: 245–277.

Idrus, A., Kolb, J., Meyer, F.M. (2009) Mineralogy, Lithogeochemistry, and Elemental Mass Balance of Hydrothermal Alteration Associated with The Gold-rich Batu Hijau Porphyry Copper Deposit,

Sumbawa Island, Indonesia, Resource Geology 59: 215–230.

Morrison, G., Dong, G., Jaireth, S. (1990) Textural Zoning in Epithermal Quartz Veins, Klondike Exploration Services, Townsville, 35p.

Petrelli, M., Poli, G., Perugini, D., Peccerillo, A.(2005) Petrograph: A New Software to Visualize,

Model, and Present Geochemical Data in Igneous Petrology, Geochemistry, Geophysics, Geosystems, vol. 6(7), 15p.

Rahardjo, W., Sukandarrumidi, Rosidi, H.M.D. (1995) Peta Geologi Lembar Yogyakarta, Jawa, Edisi 2, Pusat Penelitian dan Pengembangan, Bandung.

Shepherd, T.J., Rankin, A.H., Alderton, D.H.M. (1985) A Practical Guide to Fluid Inclusion Studies, Blackie & Son Limited, Glasgow, 239p.

Sillitoe, R.H., Hedenquist, J.W. (2003) Linkages Between Volcanotectonic Settings, Ore-Fluid Compositions, and Epithermal Precious Metal Deposits, Society of Economic Geologists, Special Publication 10, pp. 315 – 343.

Simmons, S.F., White, N.C., John, D.A. (2005) Geological Chacteristics of Epithermal Precious and

Base Metal Deposits, Society of Economic Geologists, Economic Geology, 100th Anniversary Volume, pp. 485–522.

Soeria-Atmadja, R., Maury, R.C., Bellon, H., Pringgoprawiro, H., Polves, M., Priadi, B. (1994) Tertiary

Magmatic Belts in Java, Journal of Southeast Asian Earth Science 9: 13–27.

Suroso, Rodhi, A., Sutanto (1986) Usulan Penyesuaian Tata Nama Litostratigrafi Kulon Progo,

Daerah Istimewa Yogyakarta, Proceeding of The 15th Annual Convention of The Indonesian Associationof Geologists, vol. 1, 10p.

Van Bemmelen, R.W. (1949) The Geology of Indonesia, vol. IA, General Geology of Indonesia and

Adjacent Archipelagoes, 2nd Second Edition, The Hague, Netherlands, 732p.

Wilkinson, J.J. (2001) Fluid Inclusion in Hydrothermal Ore Deposits, Lithos 55: 229 – 272.58 Journal of Applied Geology.



DOI: https://doi.org/10.22146/jag.42442

Article Metrics

Abstract views : 456 | views : 323

Refbacks

  • There are currently no refbacks.


Copyright (c) 2020 Journal of Applied Geology

Journal of Applied Geology Indexed by:

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License