STRUCTURE ANALYSIS, PALINSPASTIC RECONSTRUCTION, AND SANDBOX ANALOGUE MODELING OF THE BARIBIS FAULT, JONGGOL SEGMENT, WEST JAVA.

• Main Author: Tirto Nugroho, Rayhan
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/76069
• Institution: Institut Teknologi Bandung

Indonesia has active tectonic activity as a result of three tectonic plate encounters: the Indo-Australian Plate, the Eurasian Plate, and the Pacific Plate. The meeting of these plates produces a diverse and complex geological structure of Indonesia. One of the evidences of Indonesia's tectonic activity is the fault. In particular, West Java has at least three major faults, namely the Cimandiri Fault, the Lembang Fault and the Baribis Fault. The Baribis Fault is currently being discussed because it poses a threat of an earthquake, coupled with its position in a densely populated area, including the capital city of Jakarta. Therefore, the Baribis Fault is an interesting object to study. This study aims to determine the condition of the subsurface geological structure and the development of structural patterns on the Baribis Fault. In addition, sandbox analog modeling is carried out so that it can simulate the formation process of the Baribis Fault. The data used in this study are two-dimensional seismic sections, checkshot data, well log data, gravity anomaly maps, and geological maps. The method used in this research consists of structural analysis on seismic sections, analysis of subsurface structure maps, structural pattern analysis, palinspastic reconstruction and sandbox analogue modeling. The results of structural analysis and palinspastic reconstruction show that the study area is influenced by several deformation phases, namely the extensional phase (Eocene–Early Oligocene), stable tectonic phase (Early Oligocene–Late Miocene) and the contractional phase (Pliocene–Pleistocene). The extensional phase produces normal faults that form a half-graben basin with a northwest-southeast orientation. In relation to regional tectonics, this deformation phase began since the India-Eurasia collision at the age of 50 million years ago. The stable tectonic phase shows differential compaction due to the non-uniform height of the basement and sedimentary layers resulting in different responses to loading. The contractional phase produces an thrust fault with a northwest-southeast direction and a strike slip fault (wrench fault) with a flower structure geometry in a northeastsouthwest trend. Also found out-of-sequence thrust which basement involved deformation. Thus, this wrench fault and out-of-sequence thrust can provide an earthquake potential. The sandbox analog modeling succeeded in modeling the foldthrust belt development process in the research area in accordance with the critical wedge theory. The fault formation starts from the part closest to the moving wall and then forms again in front of it and so on to form an imbrication fault system. The number of faults increases in direct proportion to the increase in shortening.