OMBILIN BASIN EVOLUTION BASED ON STRUCTURAL GEOLOGY AND BURIAL HISTORY

• Main Author: Febriansyah Putra, Aldo
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/46430
• Institution: Institut Teknologi Bandung

Ombilin Basin is a Paleogene half-graben which is currently being part of Barisan Mountains in western Central Sumatra. This study discussed the evolution of Ombilin Basin based on fault development. The basin evolution was studied by integrating remote sensing and subsurface interpretations. Remote sensing interpretation utilized Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM). Remote sensing interpretation produced surface fault lineaments. Subsurface interpretation utilized 47 2D seismic sections and three wells. Well data included wireline logs, vertical seismic profiling data, biostratigraphic reports, and vitrinite reflectance reports. Subsurface interpretation generated chronostratigraphic units, structural sections, time structure maps, isochrone maps, and burial history. Burial history was aimed to illustrate basin subsidence. Ombilin Basin has NW-SE, N-S, and NE-SW fault trends. NW-SE Takung Fault located in the north of Ombilin Basin acted as major fault and tilted the basin to NE. N-S and NE-SW trends are transverse faults in the basin. Folds are trending in NW-SE in this basin. Based on section reconstructions, Ombilin Basin went through three tectonic phases, which are extensional phase (Middle Eocene – Oligocene), compressional phase (Late Oligocene and Late Pliocene – Recent), and thermal subsidence (Early Miocene – Late Pliocene). Extension operated obliquely to enable normal faulting in all trends. Uplift and erosion in Late Oligocene were followed by sedimentation in Early Miocene – Late Pliocene. Compressional phase is characterized by inversion of NW-SE trending faults and right-lateral reactivation of N-S and NE-SW trending faults.