Morphology of Channel-Levee Systems on the Indus Deep-Sea Fan, Arabian Sea

Abstract

 The channel-levee systems of the most recently active part of the Indus deep-sea fan are mapped with GLORIA slde-sean sonar, continuous seismic reflection profiling, high resolution (3.5 & 10 kHz) prOfiling, and other geophysical techniques. The resultant processed sonograph mosaic covers an area of approximately one eighth of the 1,570,000 kn/ of the fan and there are about 12,000 km of new seismic lines. The study is supplemented by 35 new cores recovered from various fan environments. The channel-levee systems have some striking similarities with architectural elements of mature terrestrial fluvial systems. The GLORIA sonographs reveal that the channel-levee systems on the fan are sinuous to highly meandering (sinuosity up to 3). Distributary complexes of large and small channel-levee systems exist on the fan. Distributary complexes of large channel-levee systems develop at the mouth of individual canyons on the upper fan while distributary complexes of small channel-levee systems develop from large channels on the middle fan. Both large and small channel-levee systems show remarkable similarities to each other in their cross-sectional form parameters, dimension of levee (overbank) deposits and degree of meandering etc. Only one channel was active at a time. The process of avulsion is one of the main controls on the development of the large and small channel-levee systems on the fan.