NEW INSIGHT OF STRUCTURAL EVOLUTION OF THE TIMOR ISLAND AND AUSTRALIAN CONTINENTAL MARGIN

Recent oil and gas exploration in the Eastern Indonesian region is highly concentrated in active the convergent area such as Timor and Tanimbar troughs. This area mostly characterized by development of complex fold-thrust-belt deformation involving sediments from Australian continental margin. Our research utilizing new acquired regional 2D seismic data, existing oil and gas wells and intensive fieldworks in the Timor Island. Numerous oil seeps were observed and samples during the fieldworks. However, their distribution and traps mechanism are not obvious and need to explore in more detail particularly their relationship to the structural development of the area. We are conducting integrated study of subsurface and surface geology using palinspatic reconstructions for understanding tectonic and structural evolution as implication for hydrocarbon prospect of the area.

Timor Island is type locality of arc-continent collision, which involve Australian continental margin and Banda Arc system. Deformation in the island is very complex involving Australian passive margin sequences in the south and fore-arc sediment of Banda region to the north. Two styles of faults are observed in the area, which are fold-thrust-belt and normal fault system. Although, thrust fault mostly occurred in the Timor area where normal faults system occurred within the Australian continental margin. Timor trough marked the boundary between thrust faults and normal fault system. Seismic data shows some of this normal fault is reactivated of older fault normal faults system as part of Permian rift graben. There is no clear evidence this faults system are developed under Timor Island. Over all, subsurface evidence indicate both fault style are occurred almost in the same time. The present interpretations propose that loading of thrust system affected the development of normal faults within the Australian continental margin.