Gravity field and crustal structure of the Eastern Arm of Sulawesi and the Banggai Archipelago, Eastern Indonesia

Abstract

The occurrence of extensive ophiolite masses and the development of the Batui-Balantak foreland thrust-fold belt on the Eastern Arm of Sulawesi can be attributed to the geologic process in the Neogene period when the Sulawesi Island Arc and the Banggai-Sula collided. Following the convergence, crustal fragments were further adjusted on a regional scale. This adjustment involved the rotation of crustal fragments into strike-slip faults on Sulawesi Island and the formation of extensional faults in the Banggai Archipelago. The analyses of the gravity field in the region of the eastern Sulawesi and Banggai Archipelago have yielded models that can potentially be interpreted as a representation of the underlying crustal structure in the region. The models can also be understood in a way that has consequences for tectonics. The tectonic episodes have played a significant role in the formation and development of sedimentary basins within the region. The primary objective of this study was to investigate the crustal structures of the Eastern Arm of Sulawesi and the Banggai Archipelago by means of analyzing gravity profiles. The findings of the analysis suggest that there is a slight thickening observed in the crustal block beneath the central portion of the eastern arm region. In addition, this area exhibits significant fracturing and severe attenuation. Furthermore, the crustal block has a dipped north-eastward trend in response to the ascent of the Molucca Sea oceanic crust.