Publications

Understanding the tectonic history of Central Java has long been recognized as critical to successful petroleum exploration over the area. Most of the geologic setting and its product in Central Java are intimately linked with subduction tectonics. This paper attempts to analyze the deformation process of Bukit Bajangan, Kebumen, Central Java. The lithology of Halang Formation of Miocene Age, evidenced in outcrop by alternating layers of competent tuffaceous sandstones and siltstones. The association of normal fault and high-angle reverse faulting is of critical interest in this paper. Association of normal and reverse faults can occur when the normal fault has highly-dipping strata that tectonically lock the movement of the other block. Reverse faulting occurs when extension progresses while tectonic locking occurs. Relative sense of movement is determined from slickensides and striation and drag folds. The main fault has an identifiable zone of brecciation. Methods used in this study are structural measurement, paleo stress analysis, and clay modeling. Structural measurement was employed to determine the orientation of structural planes and the dynamics of the structures. The results of study show that paleo stress direction of main fault came from N – S direction. This result follows the regional tectonic forces originating from subduction. Clay modeling was used to demonstrate the structures formed based on interpreted basement movement of Bukit Bajangan.