HUBUNGAN KONDISI GEOLOGI TERHADAP SEBARAN KADAR CU-AU BERDASARKAN DATA INTI PENGEBORAN PROSPEK TUMPANGPITU, DAERAH SUMBERAGUNG, BANYUWANGI, JAWA TIMUR: RELATIONSHIP BETWEEN GEOLOGICAL CONDITIONS AND Cu-Au GRADE DISTRIBUTION BASED ON DRILL CORE DATA FROM TUMPANGPITU PROSPECT, SUMBERAGUNG AREA, BANYUWANGI, EAST JAVA

Putri Rindu Bunga Kasih Riyanto; Dadan Wildan; Achmad Djumarma Wirakusumah; Tatik Handayani; Riansyah Widisaputra

doi:10.47599/bsdg.v20i3.549

Penulis

Putri Rindu Bunga Kasih Riyanto PEP Bandung Penulis
Dadan Wildan Penulis
Achmad Djumarma Wirakusumah Penulis
Tatik Handayani Penulis
Riansyah Widisaputra Penulis

DOI:

https://doi.org/10.47599/bsdg.v20i3.549

Abstrak

Daerah penelitian terletak di Pesanggaran, Banyuwangi, Jawa Timur, berada pada bagian tengah busur magmatik Sunda-Banda, berpotensi terbentuknya mineralisasi. Penelitian bertujuan mengetahui kondisi geologi, zona alterasi, mineralisasi, tipe deposit bijih dan hubungannya dengan distribusi kadar Cu-Au. Hasil penelitian dapat digunakan untuk acuan dalam eksplorasi lebih lanjut. Penelitian berdasarkan pada data hasil pengeboran inti, sebanyak enam titik lokasi, analisis ASD, X-RD, petrografi, mineragrafi dan statistik berupa boxplot. Litologi daerah penelitian terdiri dari enam satuan litologi, yaitu batupasir, dasit fase 1, diorit, diorit kuarsa, dasit fase 2, dan breksi freatomagmatik. Terdapat lima zona alterasi, yaitu zona overprint (alunit-klorit-mika-smektit±pirofilit±biotit±k-feldspar). Zona argilik lanjut (pirofilit-mika-dikit-diaspor). Zona argilik (kaolinit-mika±illit±diaspor). Zona filik (serisit/mika-smektit±klorit±kalsit). zona propilitik (klorit-mika-smektit±epidot±kalsit). Mineralisasi yang dijumpai berupa mineral pirit, kalkosit, enargit, dan kalkopirit, dalam bentuk tersebar, masif dan urat, hadir pada kedalaman <150 m dengan kadar Au 0,1 ppm s.d. >1 ppm, dan Cu <0,1% s.d. 0,5%. Kehadiran mineral pirit, kalkopirit, bornit, dan kovelit, berupa urat-urat kuarsa yang intensif saling berpotongan, hadir pada kedalaman >150 m dengan kadar Au 0,5 ppm s.d. >1 ppm, dan Cu 0,3% s.d. >1%. Zona distribusi kadar Cu-Au dikontrol oleh intrusi diorit kuarsa, berhubungan dengan alterasi tipe argilik dan tipe filik, dan mineralisasi yang berhubungan yaitu bornit-kalkopirit-pirit, enargit-kalkosit-pirit dan yang memiliki hubungan lemah yaitu mineral pirit. Tipe deposit bijih yaitu porfiri Cu-Au di-overprint oleh epitermal sulfidasi tinggi.

Referensi

Achdan, A.Bachri, S.. (1993). Peta Geologi Lembar Blambangan, Jawa Timur.

Adams, A. E., Mackenzie, W. S., & Guildford, C. (1984). Atlas of sedimentary rocks under the microscope. Longman.

Chen, P.Y., 1977, Table of Key Lines in X-Ray Diffraction Patterns of Minerals in Clay and Associated Rocks: Indiana, Geological Survey Occasional paper 21, Departmen of Natural Resources, p. 11-39.

Corbett, G. 2013. World Gold: Pacific Rim Epithermal Au-Ag. World Gold.

Corbett, G. J., & Leach, T. M. 1997. Short Course Manual: Southwest Pasific Rim Gold-Copper Systems: Structure, Alteration, and Mineralization. Chapter, 1, 12-21.

Harrison, R. L., et al. (2018): Geochronology of the Tumpangpitu porphyry Au-Cu Mo and high-sulfidation epithermal Au-Ag-Cu deposit: evidence for pre- and postmineralization diatremes in the Tujuh Bukit district, Southeast Java, Indonesia, Economic Geology.

Harrison, R.L., et al. (2017): Geochronology of the Tumpangpitu porphyry gold-coppermolybdenum and high-sulfidation epithermal gold-silver-copper deposit - Evidence for pre and post-mineralization diatremes in the Tujuh Bukit district, Southeast Java, Indonesia:Economic Geology (in press).

Hauff, P.L., 2005. Applied relectance spectroscopy. Spectral International Incorporated, technical docu ment to accompany spectral libraries and identiica tion softwares.

Hellman, P.L. 2011. “Tujuh Bukit Project Report on Mineral Resources, Technical Report for Interprid Mines Limited”.

Hellman, P. L. (2010). Tujuh Bukit Project Report on Mineral Resources, Located in East Java, Indonesia.

Koesoemadinata, R. P. (2020). An Introduction Into The Geology of Indonesia: Volume I (General Introduction and Part I Western Indonesia).

MacKenzie W. S, A. E. Adams, and K. H. Brodie. 2017. Rocks and Minerals in Thin Section.

Parcejus. B. 2015. The Ore Minerals under The Microscope. Second Edition. Elsevier, Amsterdam.

Pettijohn, F.J. 1975. Sedimentary Rocks (3rd ed.). New York: Harper & Row Publishing Co.

Sillitoe, R. H. (2010). Porphyry copper systems. Economic geology.

Streckeisen, A., 1978. IUGS Subcommission on the Systematics of Igneous Rocks. Classification and nomenclature of volcanic rocks, lamprophyres, carbonatites and melilitic rocks. Recommendations and suggestions. Neues

Streckeisen, A. 1976. To each plutonic rock its proper name. Earth-science reviews, 12(1), 1-33.

Suprapto, S. J., Murdohardono, D., Suparno, S., Abdurahman, O., & Subekti, A. T. (2018). Alterasi dan Mineralisasi di Pulau Merah, Kecamatan Pesanggaran, Kabupaten Banyuwangi, Provinsi Jawa Timur. Buletin Sumber Daya Geologi, 13(2), 70-83.

Thompson, A.J.B. dan Thompson, J.F.H., 1996, Atlas of Alteration A Field And Petrographic Guide To Hydrothermal Alteration Minerals, Mineral Deposots Division. Canada.

Uytenbogaardt, W. dan Burke, E.A.J. 1971. Table for the Microscopic Identification of Ore Minerals. Elsevier Scientific Publishing Company, New York.

Van Bemmelen, R. V. 1949. The Geology of Indonesia. Vol. IA: General Geology of Indonesia and Adjacent Archipelagoes. US Government Printing Office.

Sinclair, W.D., 2007, Porphyry deposits, in Goodfellow, W.D., ed., Mineral Deposits of Canada: A Synthesis of Major Deposit-Types, District Metallogeny, the Evolution of Geological Provinces, and Exploration Methods: Geological Association of Canada, Mineral Deposits Division, Special Publication No. 5, p. 223-243.