ALTERASI DAN MINERALISASI DAERAH KOMBONGAN DAN SEKITARNYA, KECAMATAN PAKENJENG, KABUPATEN GARUT, PROVINSI JAWA BARAT

Fahreza Putra

Sari


 

Abstract

The research location administratively covers two sub-districts, named Pakenjeng District which consists of Wangunjaya, Jayamekar, Jatiwangi, Depok, Panyindangan Village, and Pamulihan District, namely Garumukti Village. Geographically it is located at the coordinates of the UTM WGS-84 zone 48S: X = 792500 mE-797000 mE; Y = 9175000 mN — 9178500 mN with an area of 4.5 x 3.5 . The geomorphology are the form by Structural Hills (S1), Intrusion Hills (V1), Eroded Hills (D1), and River Bodies (F1). The lithology found is a product of a volcanic process consisting of: Jampang volcanic breccia unit (Early Miocene-Late Miocene), Jampang andesitic lava unit (Early Miocene-Late Miocene), Wayang Andesite Intrusion (Late Miocene), and Alluvial Deposit Unit (Holocene). The geological structure is in the form of layers dipping are relative to the north, fractures with the relative main stress of NNW-ESE, and faults which are grouped into Middle Miocene faults (Kombongan and Bojongboled Fault), Late Miocene faults (Cikandang, Depok, and Wayang Fault), and Pliocene faults (Cimipir and Ciawitali Fault). Hydrothermal alteration occurs intensely in the studied area, resulting in silicic (Quartz ± Pyrite), argillic (Kaolinite ± Illite ± Pyrite ± Muscovite ± Quartz), and propylitic alteration (Chlorite ± Albit ± Zeolite ± Cystobalite). Hydrothermal alteration is controlled by faults of Middle Miocene age. The mineralization found in the form of pyrite (FeS2), sphalerite (ZnS), galena (PbS), and chalcopyrite (CuFeS2) minerals which occupy the silicic alteration zone in the veins in the right slip fault zone of Kombongan and Bojongboled. The mineralized zone occupies the base metal horizon and is a type of low sulfidation (LS) deposit.

 

Keywords: Kombongan; Bojongboled; alteration; mineralization; low sulfidation

 

Abstrak

Lokasi penelitian secara administratif mencakup dua kecamatan yaitu Kecamatan Pakenjeng yang terdiri dari Desa Wangunjaya, Desa Jayamekar, Desa Jatiwangi, Desa Depok, Desa Panyindangan, dan Kecamatan Pamulihan yaitu Desa Garumukti. Secara geografis terletak pada koordinat UTM WGS-84 zona 48S: X= 792500 mE—797000 mE; Y= 9175000 mN—9178500 mN dengan luasan 4,5 x 3,5 . Geomorfologi berupa Perbukitan Struktural (S1), Bukit Intrusi (V1), Perbukitan Terkikis (D1), dan Tubuh Sungai (F1). Litologi yang dijumpai merupakan produk hasil proses vulkanik yang terdiri atas: Satuan breksi vulkanik Jampang (Miosen Awal-Miosen Akhir), Satuan lava andesit Jampang (Miosen Awal-Miosen Akhir), Intrusi Andesit wayang (Miosen Akhir), dan Satuan Endapan Aluvial (Holosen). Struktur geologi berupa kedudukan lapisan yang relatif ke arah utara, kekar dengan tegasan utama relatif NNW-ESE, dan sesar yang dikelompokan menjadi sesar berumur Miosen Tengah (Sesar Kombongan, Bojongboled), sesar berumur Miosen Akhir (Sesar Cikandang, Depok, dan Wayang) dan sesar berumur Pliosen (Sesar Cimipir dan Ciawitali). Alterasi hidrotermal terjadi secara intens di daerah telitian, menghasilkan altersi silisik (Kuarsa ± Pirit), argilik (Kaolinit ± Illit ± Pirit ± Muskovit ± Kuarsa), dan propilitik (Klorit ± Albit ± Zeolit ± Pirit ± Kristobalit). Alterasi hidrotermal dikontrol oleh sesar-sesar berumur Miosen Tengah. Mineralisasi yang dijumpai berupa mineral pirit (FeS2), sfalerit (ZnS), galena (PbS), dan kalkopirit (CuFeS2) yang menempati zona alterasi silisik pada urat di zona sesar mendatar kanan Kombongan dan Bojongboled. Zona mineralisasi daerah telitian menempati base metal horizon dan merupakan tipe endapan sulfidasi rendah (LS).

 

Kata kunci: Kombongan;Bojongboled; alterasi; mineralisasi; sulfidasi rendah


Kata Kunci


Kombongan; Bojongboled; alteration; mineralization; low sulfidation

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Referensi


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DOI: https://doi.org/10.31315/jmtg.v13i2.9459

DOI (PDF): https://doi.org/10.31315/jmtg.v13i2.9459.g5283

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