Magnetotellurics study of Atambua area, West Timor, Indonesia

Edy Wijanarko; Ilham Arisbaya; Prihadi Sumintadireja; Warsa; Hendra Grandis

doi:10.15625/2615-9783/17581

Author affiliations

Authors

Edy Wijanarko 1-Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung (ITB), Indonesia; 2-Research Center for Oil and Gas "LEMIGAS", Indonesia
Ilham Arisbaya 1-Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung (ITB), Indonesia; 3-National Research and Innovation Agency (BRIN), Indonesia
Prihadi Sumintadireja Faculty of Earth Science and Technology, Institut Teknologi Bandung (ITB), Indonesia
Warsa Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung (ITB), Indonesia
Hendra Grandis Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung (ITB), Indonesia

DOI:

https://doi.org/10.15625/2615-9783/17581

Keywords:

Atambua, West Timor, 2D magnetotellurics, geoelectrical strike, phase tensor

Abstract

Timor Island, located in the eastern Indonesian archipelago, has a complex tectonic evolution causing complex geological structures. Many hypothetical tectonic models are proposed mainly based on regional geological and geophysical data. Available geophysical data to support geological study at a more detailed scale are still very limited. Therefore, this study aimed to map the sub-regional subsurface geology in Atambua, West Timor, and its surroundings by using the magnetotelluric (MT) method. The estimated geo-electrical strike direction from the phase tensor analysis confirmed the regional Southwest - Northeast general structural orientation. The dimensionality analysis also showed the validity for 2D approximation in that direction. The subsurface resistivity models from 2D inversion of the MT data at representative lines perpendicular to the regional structural direction delineate the primary sequences and their boundaries from their resistivities. They are, from top to bottom, Viqueque and Bobonaro sequences, Kolbano sequence, Kekneno sequence, and the basement dominated by rocks with Australian affinity. These main rock formations represent the regional sedimentary depositional fill resulting from the major tectonic events on Timor Island.

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