Karakteristik Mineralisasi dan Alterasi Transisi Porfiri-Epitermal pada Sistem Porfiri-Epitermal Prospek Onto, Dompu, Sumbawa, Indonesia Karakteristik Mineralisasi dan Alterasi Transisi Porfiri-Epitermal pada Sistem Porfiri-Epitermal Prospek Onto, Dompu, Sumbawa, Indonesia
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Abstract
Penelitian ini mengkaji prospek onto di busur Sunda bagian timur, koridor magmatis Sunda–Banda yang prospektif terhadap endapan emas–tembaga porfiri dan epitermal, dengan tujuan mengkarakterisasi alterasi hidrotermal dan mineralisasi bijih untuk memahami hubungan sistem porfiri dan epitermal sulfidasi tinggi. Metode kualitatif meliputi studi lapangan, logging inti bor VHD039, VHD055, dan VHD086, serta analisis petrografi dan mikroskopi bijih. Hasil menunjukkan intrusi porfiri Onto mengalami tumpang-tindih alterasi argilik lanjut akibat fluida epitermal sulfidasi tinggi, dengan zonasi vertikal dari bawah ke atas berupa kuarsa–piropilit ± diaspor, kuarsa–alunit–piropilit, kuarsa vuggy residual, kuarsa–alunit, kuarsa–dikit, kuarsa–kaolinit, hingga ilit–smektit, serta dominasi mineral alterasi temperatur tinggi seperti kuarsa–alunit dan kuarsa–alunit–piropilit ± diaspor. Mineralisasi tembaga–emas didominasi kovelit–pirit yang berasosiasi dengan alterasi kuarsa–alunit pada kedalaman ±300 m, berkembang sebagai diseminasi, pengisi urat kuarsa tipe A–B, dan inklusi dalam pirit, dengan tekstur vuggy terisi kovelit, pirit, dan sulfur alami; secara keseluruhan, alterasi argilik lanjut yang intens dan dominasi kovelit–pirit–sulfur mengindikasikan Prospek Onto sebagai sistem porfiri terawetkan yang tertumpang-tindih oleh sistem epitermal sulfidasi tinggi (lithocap), mencerminkan lingkungan mineralisasi transisi yang kompleks.
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References
Agangi, A., & Reddy, S. M. (2016). Open-system behaviour of magmatic fluid phase and transport of copper in arc magmas at Krakatau and Batur volcanoes, Indonesia. Journal of Volcanology and Geothermal Research, 327, 669–686. https://doi.org/10.1016/j.jvolgeores.2016.10.006
Ward, J. F., Rosenbaum, G., Ubide, T., & Sandiford, M. (2024). Slab segmentation, anomalous arc volcanism, and giant porphyry copper deposits in Indonesia. Earth and Planetary Science Letters, 626, 118532. https://doi.org/10.1016/j.epsl.2023.118532
Idrus, A. (2018). Petrography and mineral chemistry of magmatic and hydrothermal biotite in porphyry copper-gold deposits: A tool for understanding mineralizing fluid compositional changes during alteration processes. Indonesian Journal on Geoscience, 5(1), 47–64. https://doi.org/10.17014/ijog.5.1.47-64
Hammarstrom, J. M., Bookstrom, A. A., Dicken, C. L., Drenth, B. J., Ludington, S., Robinson, G. R. J., Setiabudi, B. T., Sukserm, W., Sunuhadi, D. N., Wah, A. Y. S., & Zientek, M. L. (2013). Porphyry copper assessment of Southeast Asia and Melanesia. U.S. Geological Survey Scientific Investigations Report 2010–5090–D. http://pubs.usgs.gov/sir/2010/5090/d/
Maryono, A., Harrison, R. L., Cooke, D. R., & Rompo, I. (2018). Tectonics and geology of porphyry Cu-Au deposits along the Eastern Sunda Magmatic Arc, Indonesia. Economic Geology, 113(1), 7–38. https://doi.org/10.5382/econgeo.2018.4542
van Leeuwen, T., & Rompo, I. (2023). High sulfidation Au(-Ag-Cu) deposits in Indonesia: A review. Indonesian Association of Geologists (IAGI) & Indonesian Society of Economic Geologists (MGEI).
Burrows, R. D., Rennison, M., Burt, D., & Davies, R. (2020). The Onto Cu-Au discovery, Eastern Sumbawa, Indonesia: A large, Middle Pleistocene lithocap-hosted high-sulfidation covellite-pyrite porphyry deposit. Economic Geology. https://doi.org/10.5382/econgeo.4766
Setijadji, L. D., & Maryono, A. (2012). Geology and arc magmatism of the Eastern Sunda Arc, Indonesia. In Proceeding of Banda and Eastern Sunda Arcs 2012 MGEI Annual Convention (pp. 26–27).
Hall, R. (2002). Cenozoic geological and plate tectonic evolution of SE Asia and the SW Pacific: Computer-based reconstructions, model and animations. Journal of Asian Earth Sciences, 20, 353–431. https://doi.org/10.1016/S1367-9120(01)00069-4
Rahutama, A. (2021). Evolusi Busur Magmatik Pulau Jawa Bagian Timur sejak Eosen sampai Kuarter, berdasarkan analisis provenance batupasir Formasi Sambipitu. Lembaran Publikasi Minyak dan Gas Bumi, 55(2). https://doi.org/10.29017/LPMGB.55.2.607
Maryono, A., Harrison, R. L., Cooke, D. R., Rompo, I., & Hoschke, T. G. (2018). Tectonics and geology of porphyry Cu-Au deposits along the Eastern Sunda Magmatic Arc, Indonesia. Economic Geology, 113(1), 7–38. https://doi.org/10.5382/econgeo.2018.4542.
Faesal, A., Aminuddin, M. I. K. A., & Ubaidillah, A. S. (2022). Host rock petrology, hydrothermal alteration characteristics & ore mineralogy of porphyry copper-gold deposit, Brambang, Lombok, West Nusa Tenggara Indonesia. Materials Today: Proceedings, 66, 3071–3076. https://doi.org/10.1016/j.matpr.2022.07.373
Sutarto, Idrus, A., Harijoko, A., & Setijadji, L. D. (2020). Mineralization style of the Randu Kuning porphyry Cu-Au and intermediate sulphidation epithermal Au-base metals deposits at Selogiri area, Central Java, Indonesia. AIP Conference Proceedings, 2245(1), 080006. https://doi.org/10.1063/5.0008058
Carlile, J. C., & Mitchell, A. H. G. (1994). Magmatic arcs and associated gold copper mineralization in Indonesia. Journal of Geochemical Exploration, 50, 91–142. https://doi.org/10.1016/0375-6742(94)90022-1
Sillitoe, R. H. (2010). Porphyry copper systems. Economic Geology, 105, 3–41.
Barnes, S. J., Van Kranendonk, M. J., & Sonntag, I. (2012). Geochemistry and tectonic setting of basalts from the Eastern Goldfields Superterrane. Australian Journal of Earth Sciences, 59(5), 707–735. https://doi.org/10.1080/08120099.2012.687398