A chronology for geomorphological developments in the greater Bandung area, West-Java, Indonesia

Abstract

The greater Bandung area (West-Java, Indonesia) is a large intramontane basin surrounded by volcanic highlands. Geomorphological and sedimentological studies reveal that the morphology of the central basin and the Sunda-Tangkuban Perahu volcanic complex developed during the Middle-Late Quaternary, in particular since 125 kyr B.P. Tectonic subsidence, paroxysmal eruptions, volcanism-induced faulting/rifting, drainage system adaptations and intramontane lacustrine sedimentation (partly geomorphology-controlled) constitute the dominant landform-determining processes. A reconstruction of the regional morphological development is based on interpretation of morphological features and morphodynamic processes in the volcanic upland, in combination with analysis of the sedimentary record in the basin. A chronological framework is based on datings obtained from surficial sediments and deep drill cores. Initially, long term patterns in volcanicity and tectonic effects determine regional sedimentation and relief development in the greater Bandung area. Fluvial sedimentation and weathering prevailed in the basin, while the southern and northern volcanic ranges gradually formed. Basin subsidence, with contemporaneous volcanism around 125 kyr B.P., resulted in the formation of an enclosed intramontane basin, and stimulated lacustrine sedimentation. From this time on, concentration of volcanicity in the northern Sunda-Tangkuban Perahu complex and the resulting morphostructural developments caused rapid (catastrophic) and localized morphological changes. Cataclysmic eruptions (around 105 kyr B.P. and 50-35 kyr B.P.) caused voluminous sediment inflow in the northwestern basin. These events mark the significance of the Sunda-Tangkuban Perahu volcanic centre during the Late Quaternary; the Sunda volcano collapsed into a caldera in which later the Tangkuban Perahu volcano developed. Moreover, these eruptions controlled regional sedimentation and determined landform development in the greater basin area. In the vicinity of the eruption centre, volcano-tectonic faulting formed the conspicuous E-W Lembang fault that controlled distribution of volcaniclastic sediments and the initiation of a new drainage system in the Lembang area. In the low-lying Bandung plain persistent (fluvio)lacustrine and volcaniclastic sedimentation, followed by basin subsidence and minor fluvial erosion characterised the younger phases of landform development.