GEOLOGI DAN KARAKTERISTIK MINERALISASI EPITERMAL SULFIDASI RENDAH PROSPEK “RN” DI PT ANTAM PONGKOR

Silvia, Renata (2024) GEOLOGI DAN KARAKTERISTIK MINERALISASI EPITERMAL SULFIDASI RENDAH PROSPEK “RN” DI PT ANTAM PONGKOR. S1 thesis, UNIVERSITAS JAMBI.

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Abstract

Logam mulia seperti, emas, perak dan platina merupakan jenis logam yang awalnya hanya dipergunakan sebagai perhiasan saja. Namun, seiring dengan adanya perkembangan teknologi penggunaan logam mulia ini menjadi bervariasi. Emas merupakan logam mulia yang dapat digunakan dalam perkembangan industri teknologi, seperti perangkat elektronik, semikonduktor dan peralatan medis. Seiring dengan adanya perkembangan tersebut, permintaan emas dalam bidang teknologi akan terus meningkat. Lokasi penelitian berada pada Tambang emas Pongkor yang dikelola oleh PT Antam Tbk berlokasi di Kecamatan Nanggung, Kabupaten Bogor, Provinsi Jawa Barat. Vein kuarsa yang ada di Pongkor memiliki karakteristik tekstur yang beragam. Karakteristik vein dapat mengindikasikan potensi logam Au. Hal inilah yang menjadi latar belakang penulis untuk mengangkat penelitian ini. Penelitian ini bertujuan untuk menganalisis karakteristik vein secara vertikal dari tiap elevasi, dimulai dari elevasi terendah hingga elevasi tertinggi di Prospek RN. Lalu akan menghubungkan kaitannya terhadap kadar Au. Penelitian dilakukan pada vein utama di daerah Pongkor, menggunakan empat metode analisis. Pertama, metode pengamatan megaskopis atau petrologi dari karakteristik tekstur fisik dan komposisi mineral. Kedua, metode petrografi untuk mengetahui komposisi mineral dan zona alterasi. Ketiga, metode mineragrafi untuk mengidentifikasi logam berat. Keempat, uji fire assay untuk mendapatkan range kadar Au. Mineralisasi vein di Prospek RN mengisi zona bukaan akibat kontrol struktur yang berarah Utara-Selatan dan Baratlaut-Tenggara. Tipe endapan emas Pongkor tepatnya di prospek RN masuk ke dalam tipe endapan epitermal sulfidasi rendah atau dikenal sebagai lokasi vein system yang memiliki keberagaman tekstur fisik, dimulai dari yang paling sering dijumpai, yaitu tekstur massive, wall rock clast bearing, vuggy, banded (crustiform dan colloform), drussy, clay bearing, suggary, cockade, comb dan dog tooth, serta dijumpai tekstur bladed dan botryoidal pada sampel batuan mapping. Dijumpai mineral alterasi berupa smektit, illit dan klorit. Dijumpai mineral bijih dan pengikut berupa pirit (dominan) dan setempat terdapat mangan oksida, kalkopirit, kalkosit, sfalerit dan elektrum. Keterdapatan karakteristik vein dan kehadiran mineral pengikut pengisi vein berhubungan dengan kadar emas yang terkandung pada prospek vein RN. Pada umumnya emas ini terbentuk di area vein yang karakter pembentukannya berulang, sehingga terjadi pengendapan emas dan pencampuran fluida hidrotermal. Hal ini terbukti pada lokasi penelitian prospek RN dijumpai adanya tekstur banded yang dihadiri oleh grey sulfide dengan kadar berkisar 18 - 22 ppm Au. Pada tipe Pongkor sendiri grey sulfide dikenal sebagai fasies pembawa Au dengan grade yang tinggi. Selain itu, dijumpai juga fasies mangan oksida beserta kuarsa clay-debris yang kaya akan Au. Precious metals such as gold, silver, and platinum were initially only used as jewelry. However, with technological advancements, the use of these precious metals has become more varied. Gold is a precious metal that can be used in technological industry developments such as electronic devices, semiconductors, and medical equipment. Along with these developments, the demand for gold in technology will continue to increase. The research location is at the Pongkor gold mine managed by PT Antam Tbk located in Nanggung District, Bogor Regency, West Java Province. The quartz veins in Pongkor have diverse texture characteristics. The characteristics of the veins can indicate the potential of Au metal. This is the background for the author to raise this research. This study aims to analyze the vertical characteristics of veins at each elevation, starting from the lowest elevation to the highest elevation in the RN Prospect. Then, it will relate these characteristics to Au content. The research was conducted on the main vein in the Pongkor area using four analysis methods. First, the megascopic or petrological observation method of physical texture characteristics and mineral composition. Second, petrographic methods to determine mineral composition and alteration zones. Third, mineragraphy method to identify heavy metals. Fourth, fire assay test to get the range of Au content. Vein mineralization at the RN Prospect fills the opening zone due to structural control that is oriented North-South and Northwest-Southeast. The type of Pongkor gold deposit, precisely at the RN prospect, is a type of low sulfidation epithermal deposit or known as a vein system location that has a variety of physical textures, starting from the most commonly found, namely massive, wall rock clast bearing, vuggy, banded (crustiform and colloform), drussy, clay bearing, suggary, cockade, comb and dog tooth textures, as well as bladed and botryoidal textures found in mapping rock samples. Alteration minerals such as smectite, illite and chlorite are found. Ore and follower minerals are found in the form of pyrite (dominant) and locally manganese oxide, chalcopyrite, chalcocite, sphalerite and electrum. The presence of vein characteristics and the presence of vein filler associated with the gold content of the RN vein prospect. In general, this gold is formed in vein areas with repetitive formation characteristics, resulting in gold deposition and mixing of hydrothermal fluids. This is evidenced at the RN prospect research location, where there is a banded texture attended by gray sulfide with levels ranging from 18 - 22 ppm Au. In the Pongkor type, grey sulfide is known as a high grade Au-bearing facies. In addition, manganese oxide facies along with Au-rich quartz clay-debris are also found.

Type:	Thesis (S1)
Uncontrolled Keywords:	Emas, tambang emas Pongkor, vein, endapan epitermal, mineral bijih, grey sulfide
Subjects:	G Geography. Anthropology. Recreation > GB Physical geography
Divisions:	Fakultas Sains dan Teknologi > Teknik Geologi
Depositing User:	SILVIA
Date Deposited:	07 Oct 2024 02:41
Last Modified:	07 Oct 2024 02:41
URI:	https://repository.unja.ac.id/id/eprint/71124

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