ANALISIS STRUKTUR DAN SINTESIS GEOLOGI PADA AREA SUB-CEKUNGAN TARAKAN (ONSHORE), KALIMANTAN UTARA, MENGGUNAKAN METODE RESTORASI PALINSPASTIK

Abstract

This study aim to carry out the application of palinspastic reconstruction on the onshore side of the Tarakan sub-basin and compile the geological synthesis that occurs in the basin. The tarakan sub-basin is located in North Kalimantan and bounded by the Tidung sub-basin in the north, Muara and Berau sub-basins in the south, Sekak High in the west, and Makassar Strait in the east. Based on regional geological conditions, the research area was part of the back-arc basin system at Eocene and experienced an extension that reaches its peak at Early Miocene. There was a change in deformation from tensional to compression processes due to shear faults that are active around the study area started at Pliocene. The developed structures in this area are dominated by normal faults that have been inverted in several areas. The research began with seismic data analysis to produce a Time Structure Map and Thickness Map. In this section, it can be seen that there are two dominant lineages, namely the one with the northeast - southwest strike and northwest - southeast strike. Palinspastic reconstruction is carried out to reconstruct and model the depositional conditions of rock formations during the deformation event at each age. Based on the results of the analysis, it is known that during Eocene to Late Miocene the strain value always shows a positive value which indicates an elongation of the horizon in each layer. These results are consistent with the tensional regime that worked in the research area. At the Pliocene age, the strain value shows a negative value in the west - east section on the northside reserach area. This can occur due to a regime change to a compressional regime and causes some faults to experience inversion.