Publications

Interpretation of high-resolution (> 150 Hz) 2D seismic data over a 6300 km2 area of the modern, drowned Java Shelf, Offshore Northwest Java, Indonesia, led to the identification and delineation of a recent (Holocene) incised-valley complex. The youngest in a series of erosional features in this area, this complex likely formed by incision during the latest eustatic sea-level fall and filled during the subsequent transgression.Seismic mapping within the first 150 msec of seismic data shows that the incised-valley complex is comprised of two types of channels: several shallow (10-30 m), relatively straFght, short (less than 30 km) channels, and a single deep (40-50 m), straight to meandering, long (greater than 150 km) channel. Channel-fill is characterized on seismic by horizontal, low to moderate strength reflections that onlap the channel walls. No lithological information is available from within the channels, however, based on seismic character, the sediment is assumed to be mud-prone.The incised-valley complex is located within a large, present-day bathymetric trough. The trough is 20-30 km wide, greater than 300 km long, and it has over 100 meters of relief. The trough is the present-day expression of a large-scale erosional valley likely formed during repetitive sea-level lowstands during the Pleistocene. It focused drainage from fluvial systems in northwest Java, southeastern Sumatra, and possibly southern Borneo into the area of the present day Java Sea. From there, the fluvial systems drained into the Indian Ocean through the Sunda Straits. During subsequent rises in sea level, the trough was filled with sediment except in localized areas where strong 'currents kept the channel relatively free of sediment. This bathymetric trough, therefore, had a first-order effect on the location of the incised-valley complex. Comparing the incised valley pattern with subsurface maps shows that structural features, such as regional fault trends and structural highs, also played a significant role in channel location.