INTERPRETATION OF SUBSURFACE GEOLOGY BASED ON MAGNETOTELLURIC DATA IN SOUTHERN CENTRAL TIMOR REGION PROVINCE OF EAST NUSA TENGGARA

• Main Author: M Lucki Junursyah, G
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/78484
• Institution: Institut Teknologi Bandung

The Geology of Timor is closely related to the formation of Banda Arc as a horseshowshaped multiple islands arc, resulting from the convergence of Indo-Australian, Pacific, and Eurasia plates. The complex tectonic activity presents some approximate tectonic evolution models, namely Overthrust, Imbricate, and Autochtone models. The models are still a subject of debate till now. The existence of varied geological resources makes Timor Island increasingly attractive to investigate, one of which is the existence of gas permeation in Kolbano area on which exploratory drilling has been conducted. The activity produced an unsatisfied result, due to the limitation of deeper subsurface geological data. Deeper subsurface geological data can be studied by geophysical methods, one of which is Magnetotelluric (MT) method. The MT method utilizes the relation between magnet field and coplanar electric field components. The relation can be measured on surface by using earth natural source, in order to map subsurface geological conditions based on the properties of resistivity of rock type. This research used MT data for 16 points that were taken in Kolbano area and vicinity, Southern Central Timor District, Province of East Nusa Tenggara. The points of MT measurement formed a straight section of approximately 25 km long and in a relative direction of southeast-northwest. The results of the subsurface interpretation based on the properties of resistivity of rock type showed that the basement in the area investigation has a deepness around 2 - 5 km, being increasingly narrower toward the southeast of MT section. The basement were covered by vertically predominant Kekneno and Kolbano sequences, and laterally predominant Viqueque sequence. The tectonic evolution model that was suitable with the formation of rise faults that cut and raised the sequences was Autochtone model.