Publications

The Tarakan sub-basin, which is located in the Northeast Kalimantan, Indonesia, is one of the prolific basins in circum Borneo. Many of the previous publications on Tarakan were mainly focused on the onshore and the shallow water regions of the basin. This is not surprising as most of the discoveries have been on the deltaic play. Recently, the exploration activity has been moved to the deep water region and the newly acquired seismic data provide a clearer picture of the structural setting and geometry of the basin and provides better clues on the most likely regional stress regime that might have affected the structures.One Major Regional Normal Fault (MRNF) appears to exist in the Tarakan sub-basin. This master fault is a down to basin (to the East) system and subdivides the sub-basin into the so-called stable area (Footwall) and depocentre (Hangingwall). The fault separates areas with different tectonic regimes and probably marks the transition between two different crust types. The depocentre area is dominated by a thin skinned deformation, comprising of a series of NNE-SSW growth fault and gravity-driven thrusting (toe-thrust). In contrast, the structural domain in the stable area seems to involve basement.In the stable area, NW-SE synthetic sinistral strike slip faults and NNE-SSW en echelon anticlines are considered to fit the strain ellipsoid associated to sinistral strike slip movements.The Tarakan sub-basin has undergone a series of tectonic deformation after the rifting phase that took place in Eocene time. In general, the tectonic events in Tarakan are the results of plate motions which have lead to the subduction of the Paleo South China Sea in the Northwest Borneo (Mid Oligocene), the counter clock wise rotation of the Borneo Island (Lower Miocene) and Australia collision with Sunda Plate Eastern Indonesia that resulted in the Sorong strike slip system.The left lateral strike slip faults that are present in the Tarakan sub-basin are believed to be a continuation of the Palu Koro fault system from Sulawesi. This fault system is part of fault splay at the Western end of the Sorong Fault system. The left lateral strike slip movement on Tarakan has been active primarily since the beginning of Pliocene time (about 5ma).Finally, the structural development in the sub-basin seems to control the sediment distribution on the area.