Geology and 2D modelling of magnetic data to evaluate surface and subsurface setting in Bongongoayu geothermal area, Gorontalo

Abstract

Bongongoayu is one of the regions in Indonesia that has geothermal potential. Bongongoayu requires surface and subsurface data to support the preliminary data. This research aims to determine surface and subsurface data conducted by geology and magnetic method. The surface data, including geomorphology, lithology, hydrology and manifestation. The subsurface data have taken by the magnetic method. The result showed that the geothermal manifestation of Bongongoayu is a hot pool. The surface temperature is 43 to 59 °C. The geomorphology units is composed of volcanic hills unit and lake plains unit. The lithology of the research area is composed of granite and alluvial deposits. Based on petrographic analysis, the level of alteration in granite rocks is 65% and is classified as moderate alteration. The recharge area is in the north and southwest of the research area. Discharge area is in the central area. Based on 2D magnetic modeling, there are two subsurface layers. The first layer is alluvial and the second layer is granite. Rocks that are under the alluvial layer and have been altered are interpreted as a cap rock. 2D magnetic models show normal faults in the research area as a controlling factor for geothermal fluid.

Study of Geothermal Characteristics Based on the Geochemistry of Makula Hot Springs Wala Area, South Sangalla, Tana Toraja, South Sulawesi, Indonesia

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“…Kondisi tektonik yang sangatlah kompleks yang terjadi di sepanjang zona subduksi di daerah bagian utara hingga ke timur dari lengan utara Sulawesi [1], [2]. Sehingga banyaknya keterdapatan batuan-batuan intrusi [3], [4] yang menerobos batuan yang telah ada sebelumnya sehingga kemudian membentuk berbagai tipe alterasi dan cebakan mineralisasi pembawa mineral ekonomis. Mineral bijih terutama emas merupakan salah satu kebutuhan dasar manusia.…”

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