Identification of subsurface structure using the pseudo-gravity method of magnetic data at the geothermal area of Sonai Village and its surroundings, Puriala, Konawe Regency

Misbayanti Dian Ratu, Abdul Manan, Bahdad Bahdad, Rani Chahyani

Abstract


It has been conducted a geomagnetic research in the geothermal area of Sonai Village and its surroundings, Puriala, Konawe Regency, which aims to identify the structure of the subsurface using the pseudo-gravity method. After performing diurnal and IGRF corrections on the measurement data, the residual magnetic field anomaly is obtained around -150 to 90 nT. Furthermore, transformation process using the pseudo-gravity method is carried out, and the anomaly contour density is obtained around -0.07 to 0.06 mGal. The results of 2D modeling of 2 slices on the residual magnetic anomaly map that have undergone pseudo-gravity transformation show that the subsurface layers of the research area are composed of 3 formations. Layers with density values of 1.5 and 2.5 g/cm3 are thought to be Alluvium Deposits in the form of sand and clay, layers with density values of 2.6 and 2.78 g/cm3 are sandstone and conglomerate in the Alangga Formation, and a layer with a density value of 2.84 g/cm3 is peridotite in the Ultramafic Complex (bedrock layer). In addition, several minor faults were also found, and among them 2 minor faults adjacent to geothermal manifestation are located at coordinates of approximately 4o1’16.149” South Latitude dan 122o7’9.609” East Longitude with a distance of ±15 meters, and at coordinates of approximately 4o1’23.388” South Latitude dan 122o7’24.326” East Longitude which is ±28 meters from the manifestation. These minor faults cut through the peridotite layer and the conglomerate layer, and are thought to be the migration path of hot fluids towards the surface.

Keywords


Geothermal area; magnetic anomaly; pseudo-gravity method; subsurface structure

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References


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DOI: http://dx.doi.org/10.31258/jkfi.22.2.73-84

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