Bulletin of Scientific Contribution

ABSTRAK

Survei Magnetotelurik (MT) telah dilakukan di daerah panas bumi Maranda yang terletak di Kabupaten Poso, Sulawesi Tengah. Pola struktur geologi di daerah Maranda didominasi oleh arah utara-selatan yang berasosiasi dengan arah sesar naik Poso yang berada di bagian baratnya dan pola struktur berarah relatif barat-timur sebagai antitetiknya. Hasil perhitungan dengan geotermometer silika baik pada kondisi conductive cooling maupun adiabatic cooling menunjukkan nilai yang hampir sama dimana suhu reservoir berdasarkan geotermometer kelompok mata air panas Maranda berkisar antara 125-184°C. Tujuan survei ini adalah untuk mengetahui struktur tahanan jenis bawah permukaan yang berkorelasi dengan sistem panas bumi. Pengukuran MT di daerah panas bumi Maranda telah dilakukan pada 42 titik ukur yang tersebar membentuk 8 buah lintasan berarah baratdaya-timurlaut dengan jarak antar titik ukur sekitar 1000 m. Peta tahanan jenis (MT) memperlihatkan adanya pola kelurusan berarah baratlaut-tenggara dengan sebaran tahanan jenis tinggi di sebelah baratdaya dan sebaran tahanan jenis rendah di sebelah timurlaut. Batuan penudung yang dicirikan dengan nilai tahanan jenis rendah berada di sebelah timurlaut di antara mata air panas Maranda dan mata air panas Kawende dengan pola yang membuka ke arah timurlaut. Batuan penudung ini diperkirakan berada di dekat permukaan hingga kedalaman 750 meter dengan ketebalan 500-750 meter.

Kata kunci: magnetotelurik, panas bumi, Maranda, Sulawesi Tengah

ABSTRACT

Magnetotelluric (MT) surveys have been conducted in the Maranda geothermal area located in Poso District, Central Sulawesi. The geological structure pattern in the Maranda region is dominated by the north-south direction associated with the Poso thrust fault in the west and the structures pattern of relative east-west trending as their antithetes. The results of calculations with silica geotherm meter in both conductive cooling and adiabatic cooling conditions show almost the same value that the reservoir temperature based on the geothermometric of the Maranda hot springs ranges from 125-184 ° C. The purpose of this survey is to knowing the structure of the subsurface resistivity that correlates with the geothermal system. Measurements of MT in geothermal Maranda have been done on 42 scattered points forming 8 trajectory direction southwest-northeast with the distance between the measuring point about 1000 m. The type resistance maps (MTs) show an alignment pattern in northwest-southeast direction with high resistance range in the south-west and low-end resistance range to the northeast. The cap rocks that are characterized by low-end resistance values are northeast of Maranda's hot springs and Kawende's hot springs with a pattern that opens to the northeast. The cap rocks are estimated to be near the surface to a depth of 750 meters with a thickness of 500-750 meters.

Keywords: magnetotelluric, geothermal, Maranda, Central Sulawesi

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