Shallow geological structure features in Balikpapan Bay East Kalimantan Province – Indonesia

Abstract Research to determine the shallow geological structure features was carried out in Balikpapan Bay, East Kalimantan Province, using the sub-bottom profiling (SBP) method. The aim is to contribute marine geological data for regional development. Some geological structures are observed at the bottom of Balikpapan Bay based on the analyses of SBP records. These features are interpreted as representing and as the continuation of terrestrial geological data and information surrounding Balikpapan Bay obtained from the Geological Agency. The observed geological structures in the bay are bedding planes, folds, thrusts, and strike-slip faults. The geological structures observed in Balikpapan Bay are due to compressional stress derived from the Makassar Strait spreading center. These results support Terrestrial Geological Agency data surrounding the bay that occurred in the marine environment. It is hoped that the results of this research will become supporting data when a bridge over Balikpapan Bay will be built in the future which will connect Balikpapan City to the new National Capital. The development of shallow geological structures in Balikpapan Bay is influenced by a branch of the regional Adang Fault passing through the bay. This strike-slip fault manifests itself as many shallow geological structures as observed in SBP records. Spreading center in the middle of Makassar Strait that generates compressional forces was causing the development of such structures in either Balikpapan Bay or its terrestrial areas.