The Middle – Late Miocene intra-arc basin in the region of Majalengka – Banyumas area has been an interesting theme since there is indication of the volcanoclastic sediments pathway show different direction compare to the time equivalent sediments in the adjacent Bogor Trough. Enhanced regional gravity map clearly imaged the E-W and NW-SE major structural grains parallel with the postulated intraarc basin. These structural lineaments could be responsible for the development of sub-basins and volcanic products through splay or duplex fault or pull apart related to oblique subduction. Spot sampling of epiclastic deposited as sediment-gravity flows and their pyroclastic within the submarine-fan complex of the Middle-Late Miocene age shows the significance variation during the development of this basin. Paleobathymetry changing is evidence with the micropaleontology data that reveal the gradual changes within the Middle – Late Miocene basin fill. The slope channel to basinal deposits developed traversing this basin axis. The development of this basin indicates complex history since this region is now inverted and built the mountain range. Therefore further tectonic reconstruction in this region is required for better understanding the geologic history merit further geological exploration prospect.
Keywords: Enhanced regional gravity map, intra-arc basin, sub-basin, volcanic activities, splay fault,
duplex fault, pull apart, oblique subduction, sediment-gravity flows, tectonic reconstruction
Author : H. Permana, P. S. Putra, A. F. Ismayanto, I. Setiawan, M. Hendrizan, M. M. Mukti