Low-Sulfidation Epithermal Carbonate-Base metal-Gold Mineralization Hosted by Tertiary Sedimentary Rocks in Bastem Prospect, Luwu District, Sulawesi Island, Indonesia: A Preliminary Study

https://doi.org/10.22146/jag.55472

Arifudin Idrus(1*), Irzal Nur(2), Sufriadin Sufriadin(3), Fadlin Fadlin(4), Indra Sanjaya(5), Rohaya Langkoke(6)

(1) Department of Geological Engineering, Universitas Gadjah Mada
(2) Department of Mining Engineering, Universitas Hasanuddin, Makassar
(3) Department of Mining Engineering, Universitas Hasanuddin, Makasar
(4) Sudy Program of Geological Engineering, Universitas Jenderal Soedirman
(5) Geological Survey of Indonesia, Bandung
(6) Department of Geological Engineering, Universitas Hasanuddin, Makassar
(*) Corresponding Author

Abstract


In Indonesia, gold is typically mined out from epithermal, porphyry and skarn deposit types occurred within volcanic belts along magmatic arc or active continental margin setting. Numerous gold prospects, however, are recently discovered in association with metamorphic and sedimentary rocks. This paper is aimed to discuss a preliminary study on the occurrences and characteristics of the sedimentary rock-hosted low-sulfidation (LS) epithermal gold mineralization in Bastem (Bessengan Tempe) prospect, Luwu district, Sulawesi Island, Indonesia. Detailed geological and hydrothermal alteration mapping was performed to understand the distribution and characteristics of ore mineralization. Representative ore samples taken were analysed for ore chemistry by means of Fire Assay – Atomic Absorption Spectrometry (FA-AAS) and Acid Geochemical Digest - Atomic Absorption Spectrometry (GA-AAS). The results from this work that the Bastem prospect is stratigrapically occupied by Tertiary sedimentary rocks of Toraja formation, which is adjacent to volcanic rocks of Lamasi formation. Gold-bearing quartz±carbonate veins are hosted by mudstone and siltstone of Toraja formation. The quartz-carbonate veins show a typical LS epithermal open space filling texture containing erratic gold grade of up to 7.16 g/t with relatively high besemetals (Pb and Zn) grades of up to >0.4 and >1%, respectively. Based on those various features, the LS epithermal deposit is categorized as “carbonate-basemetal-gold mineralization type”, which might be originated in back arc rift/basin setting. This ‘unconventional’ sedimentary rock hosted-gold mineralization type would be the new target of gold exploration in Indonesia.


Keywords


Sedimentary rocks, LS epithermal gold, Bastem, Sulawesi Island, Indonesia

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References

Basuki, A., Sumanagara, D.A., and Sinambela, D. (1994) The Gunung Pongkor gold-silver deposit, West Java, Indonesia, J. Geochem Expl 50: 371391.

Bergman, S.C., Coffield, D.Q., Talbot, J.P., Garrard, R.A. (1996) Tertiary tectonic and magmatic evolution of western Sulawesi and the Makassar Strait, Indonesia: evidence for a Miocene continentcontinent collision. In: Tectonic evolution of Southeast Asia (eds Hall, R. & Blundell, D. J.), Geology Society of London Special Publication 106: 391-429.

Calvert, S.J., Hall, R. (2007) Cenozoic evolution of the Lariang and Karama regions, North Makassar Basin, western Sulawesi, Indonesia. Petroleum Geoscience 13: 353-368. Carlile, J.C., Digdowirogo, S., Darius, K. (1990) Geological setting, characteristics and regional exploration for gold in the volcanic arcs of North Sulawesi, Indonesia. Journal of Geochemical Exploration 35: 105-140.

Corbett, G.J. (2004) Epithermal and porphyry gold – geological models. Proceedings PACRIM Congress 2004, Adelaide. pp. 15-23.

Djuri, Sudjatmiko, S., Bachri, Sukido (1998) Geological Map of Majene and Western Part of Palopo Sheets, Sulawesi, Scale 1: 250,000. Geological Research and Development Centre, Indonesia.

Ernowo, Meyer, F.M., Idrus, A. (2019) Hydrothermal alteration and gold mineralisation of the Awak Mas metasedimentary rockhosted gold deposit, Sulawesi, Indonesia. Ore Geology Reviews, Vol. 113, Pages 103083, https://doi.org/10.1016/j.oregeorev.2019.103083.

Gemmell, J.B. (2007) Hydrothermal alteration associated with the Gosowong epithermal Au-Ag deposit, Halmahera, Indonesia: Mineralogy, geochemistry and exploration implications, Economic Geology, v. 102, 893-922.

Hamilton, W. B. (1979) Tectonics of the Indonesian region. USGS Prof. Paper 1078, 345 pp.; reprinted with corrections 1981 and 1985.

Hermiyanto, M.H., Mangga, A.M., Koesnama (2010) Lingkungan Pengendapan Batubara, Formasi Kalumpang di Daerah Mamuju. Jurnal Geologi Sumberdaya Mineral 20: 179-184.

Idrus, A., and Kolb, J., Meyer, F.M. (2007) Chemical composition of rock-forming minerals in coppergold-bearing tonalite porphyry intrusions at the Batu Hijau deposit, Sumbawa Island, Indonesia: Implications for crystallisation conditions and fluorine-chlorine fugacity, Special Issue, Resource Geology, V. 57, No. 2 p. 102-113.

Idrus, A., Hakim, F., Warmada, I.W., Aziz, M., Kolb, J., Meyer, F.M. (2015) Geology and Ore Mineralisation of Neogene Sedimentary Rock hosted LS Epithermal Gold Deposit at Paningkaban, Banyumas Regency, Central Java, Indonesia. J. SE Asian Appl. Geol. 7: 75–81.

Idrus, A., Mansur, S., Ahmad, Rahmayuddin, Mahdi, A. (2016) Occurrences and Characteristics of Gold Mineralisation in Rampi Block Prospect, North Luwu Regency, South Sulawesi Province, Indonesia. Journal of Applied Geology 1: 63-70.

Idrus, A., Prihatmoko, S., Harjanto, E., Meyer, F.M., Nur, I., Widodo, W., Agung, L.N. (2017) Metamorphic rock-hosted orogenic gold deposit style at Bombana (Southeast Sulawesi) and Buru Island (Maluku): Their key features and significances for gold exploration in Eastern Indonesia, Journal of Geosciences, Engineering, Environment and Technology, vol.2, No.2, 2017, p. 124-132.

Idrus, A., Nur, I., Sufriadin, Fadlin, Sanjaya, I. (2011) Laporan Eksplorasi Emas di Bastem, Kabupaten Luwu, PT. Emitraco Resources, Unpublished internal report, 50 hal.

Kadarusman, A., Miyashita, S., Maruyama, S., Parkinson, C.D., Ishikawa, A. (2004) Petrology, geochemistry and plaeogeographic reconstruction of the East Sulawesi Ophiolite, Indonesia. Tectonophysic 392: 55-83.

Meldrum, S.J., Aquino, R.S., Gonzales, R.I., Burke, R.J., Suyadi, A., Irianto, B., and Clarke, D.S. (1994) The Batu Hijau porphyry copper gold deposit, Sumbawa Island, Indonesia: Journal of Geochemical Exploration, v. 50, p. 203-220.

Mertig H.J., Rubin, J.N., and Kyle, J.R. (1994) Skarn Cu-Au orebodies of the Gunung Bijih (Erstberg) district, Irian Jaya, Indonesia, Journal of Geochemical Exploration, 50, 179-202.

Prihatmoko, S., Idrus, A. (2020) Low-Sulfidation Epithermal Gold Deposits in Java, Indonesia: Characteristics and Linkage to the Volcano-tectonic Setting. Ore Geology Reviews 212: 103490, https://doi.org/10.1016/j.oregeorev.2020.103490.

Querubin, C.D., Walters, S. (2011) Geology and Mineralisation of Awak Mas: A Sedimentary Hosted Gold Deposit, South Sulawesi, Indonesia, Proceedings of The Sulawesi Mineral Seminar, Manado 28-29 November 2011, p. 211-229.

Rivai, T.A., Yonezu, K., Syafrizal, Sanematsu, K., Kusumanto, D., Imai, A., Watanabe, K. (2019) A Low-Sulfidation Epithermal Mineralisation in the River Reef Zone, the Poboya Prospect, Central Sulawesi, Indonesia: Vein Textures, Ore Mineralogy, and Fluid Inclusions. Resource Geology 69: 385401.

Sillitoe, R.H., Hedenquist, J.W. (2003) Linkages between volcanotectonic settings, ore-fluid compositions, and epithermal precious metal deposits. In: Simmons, S.F., Graham, I.J. (Eds), Volcanic, Geothermal and Ore-forming Fluids: Rulers and Witnesses of Processes within the Earth, Soc. Econ. Geol., Special Publication 10, 315-343, https://doi.org/10.5382/SP.10.16

Sukamto, R. (1975) Perkembangan tektonik di Sulawesi dan daerah sekitarnya, suatu sintesis perkembangan berdasarkan tektonik lempeng. Geologi Indonesia 2: 1-13.

van Bemmelen, R.W. (1949) The Geology of Indonesia. Martinus Nijhoff, The Hague, 102p.

van Leeuwen, T.M., Allen, C.M., Elburg, M., Massone, H.J., Palin, J.M., and Hennig, J. (2016) The Palu Metamorphic Complex, NW Sulawesi, Indonesia: Origin and evolution of a young metamorphic terrane with links to Gondwana and Sundaland. Journal of Asian Earth Sciences, 115, p.133-152.

van Leeuwen, T.M. and Muhardjo (2005) Stratigraphic and tectonic setting of the Cretaceous and Paleogene volcanic-sedimentary successions in Northwest Sulawesi, Indonesia: implications for the Cenozoic evolution of Western and Northern Sulawesi. Journal of Asian Earth Sciences, 25, p.481-511.

Warmada, IW (2003) Ore mineralogy and geochemistry of the Pongkor epithermal gold-silver deposit, Indonesia, Dissertation. Papierflieger, Clausthal-Zellerfeld, 107 p.

Wajdi, M.F., Santoso, S.T.J., Kusumanto, D., Digdowirogo, S. (2011) Metamorphic Hosted Low Sulphidation Epithermal Gold System at Poboya, Central Sulawesi: A General Descriptive Review, Proceedings of The Sulawesi Mineral Seminar, Manado 28-29 November 2011, p. 201-210.



DOI: https://doi.org/10.22146/jag.55472

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