Publications

Luwuk at the eastern end of Sulawesi’s East Arm has been recognized to be formed under obductional tectonic where the East Sulawesi Ophiolite Complex thrusted southward over the Banggai-Sula microcontinent during Late Neogene event. At the southern section, a gas field of Tomori has been developed with reservoirs distributed in the pre-collisional Miocene carbonates. To date, explorational work over the area has been incorporating collisional structures such as thrusts and wrench faults into the petroleum systems, e.g. hydrocarbon maturation and trap formation. Most of the structural concept based on the existing model of southeastward vergeance thick-skinned (ophiolitic basement involved) thrust-fold belt. A geologic field work has been conducted transecting north-south section and east-west section of Luwuk. Satellite imagery interpretation and field observation suggest the existance of three structural compartments, i.e.: (i) the northern extensional, block-faulting, tectonic regime on the ophiolite complex, (ii) the central compressional, northwestward vergeance thrust-fold belt, tectonic regime on the Tertiary carbonates, and (iii) the southern, locally gravitational sliding, tectonic regime on the Pliocene molasse. Each compartment exhibits distinct structural style and diverse tectonic control. The northern extensional compartment were controlled by rifting of Siuna Bay along the Late-Miocene right-lateral movement of Balantak Fault. The central compressional compartment were developed by the Late Pliocene northwestward shortening due to activation of Sorong Fault. The southern gravitational Molasse sliding were induced by the Late Pliocene uplift along the existing weak zone of north-south transtensional strike-slip fault. Implication of this research to petroleum exploration is a revision of Luwuk thrust-fold belt model, which is proposed to be thin-skinned (basement uninvolved) northwestward vergeance.