Publications

ION-GXT has completed a regional 2D reconnaissance survey of the Java Sea back-arc region and Makassar Strait comprising over 9,000 line-km of data acquired with a 25 m shot interval, 12.5 m group interval and maximum offset of 9,000 m. These new data have provided pre-stack depth images to 40 km, allowing new interpretations of the basement structure and its influence on the overlying sedimentary cover. In the East Java Sea, the new seismic data have revealed thicker intervals of pre-Tertiary sedimentary rocks than have previously been thought to exist below the normally accepted acoustic basement, overlying arc-related basement terranes in the west (Sundaland) and Precambrian continental crust of presumably Australian origin in the east. They occur in structures that commonly localize Paleogene extension and subsequent inversion in the Neogene. Improved imaging of the Paleogene grabens in the North and Makassar Basins allows for more detailed interpretations of the stratigraphic character and depth of the syn-rift fill. The basement in this area is interpreted as extended continental crust based on estimated crystalline crustal thickness exceeding 25 km. Much of the eastern area, north of Nusa Tenggara and south of Sulawesi between Buton-Tukang Besi and Bone Bay, is interpreted to be underlain by fragments of continental crust presumably of Australian origin. This area was later extended during the Neogene associated with back-arc spreading in the Banda Sea. The spectacular rift geometry imaged in the Bone basin forms the western tectonic boundary of this province, which is located near the interpreted suture of this terrane to easternmost Sundaland. Oceanic crust in the Flores basin lies marginal to this terrane and the East Java Sea, where it is overthrust by a deformed post-Cretaceous volcanic complex.