Analisis Sebaran Zona Mineralisasi Mangan Menggunakan Data VLF-EM di Desa Kasihan, Kecamatan Tegalombo, Pacitan, Jawa Timur

CATUR AYU DHAMAYANTI, Drs. Imam Suyanto, M.Si.; Dr.rer.nat. Sintia Windhi Niasari, M.Eng.

2022 | Skripsi | S1 GEOFISIKA

Desa Kasihan merupakan salah satu daerah prospek sumber daya mineral di Indonesia karena ditemukan singkapan bijih sulfida dan urat kuarsa serta skarn Fe-Mn hasil alterasi. Mineral logam mangan sangat banyak kebermanfaatannya terutama dalam industri pembuatan baja. Penelitian menggunakan metode Very Low Frequency (VLF) mode tilt-angle dilakukan karena dapat menerima respon dari benda anomali konduktif yang ada di bawah permukaan untuk mengetahui sebaran zona mineralisasi mangan. Area survei terdiri atas Blok Barat dan Blok Timur yang masing-masing terdapat enam lintasan dengan azimuth 78�º. Akuisisi data menggunakan instrumen T-VLF BRGM untuk menangkap sinyal dari pemancar Australia (19.800 Hz) dan Jepang (22.200 Hz). Pengolahan data menghasilkan nilai Rapat Arus Ekuivalen (RAE) dan dibuat korelasi penampang 2D serta model 3D. Interpretasi didasarkan pada nilai RAE tinggi yang menunjukkan zona mineralisasi mangan, didukung adanya singkapan di permukaan. Blok Barat memiliki kemenerusan zona mineralisasi mangan di awal lintasan berarah Utara-Selatan yang bercabang dua serta di akhir lintasan berarah Utara-Selatan, dengan total volume 860.850 m3. Blok Timur memiliki kemenerusan di awal lintasan berarah Timur Laut-Barat Daya, dengan total volume yaitu 621.900 m3.

Kasihan Village is one of the prospect areas for mineral resources in Indonesia because outcrops of sulfide ore and quartz veins and altered Fe-Mn skarn have been found. Manganese metallic minerals are very useful, especially in the steelmaking industry. This research uses the Very Low Frequency (VLF) tilt-angle method because it can receive a response from conductive anomaly objects below the surface to determine the distribution of manganese mineralization zones. The survey area consists of the West Block and East Block, each of which has six lines with an azimuth of 78�º. Data acquisition used the T-VLF BRGM instrument to capture signals from Australian (19,800 Hz) and Japanese (22,200 Hz) transmitters. Data processing resulted in the value of the Equivalent Current Density (ECD) and made a 2D cross-section correlation and a 3D model. Interpretation is based on high ECD values indicating zones of manganese mineralization, supported by outcrops on the surface. The West Block has a continuous zone of manganese mineralization at the beginning of the area in a North-South direction and at the end of the area in a North-South direction, with a total volume of 860,850 m3. The East Block has a continuity at the beginning of the area in a Northeast-Southwest direction, with a total volume of 621,900 m3.

Kata Kunci : Very Low Frequency (VLF), anomali konduktif, Rapat Arus Ekuivalen (RAE), zona mineralisasi mangan