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Ingo Klaucke1,
Neil H. Kenyon1,
Amir Ayub1,
Philip P.E. Weaver1
(1) Southampton Geological Centre, Southampton, United Kingdom
Abstract: Spatial and temporal evolution of channel sinuosity on the Indus Fan
The Indus Fan is composed of several channel-levee complexes showing intricately meandering channels. Sinuosity of these channels is as high as 3.0, but decreases down fan in a non-consistent manner. A strong link between channel sinuosity and fan gradient has been proposed to explain this evolution.
Detailed bathymetry of a 50 km reach of the most recent fan channel allows determination of the evolution with time of channel sinuosity. The channel is here up to 20 km wide while the thalweg only reaches about 1 km width. Depth of the channel reaches 300 m, but up to 5 terraces are present between the thalweg and the levee crest. Three of these terraces can be followed over much of the surveyed stretch and indicate a much wider, intricately meandering channel compared to today’s thalweg. Sinuosity of the fan valley (levee crest to levee crest) is much lower than sinuosity of the terraces. Dating of sediment cores from the terraces and the channel floor show that the Indus Fan channel was active during the Holocene. However, the presence of terraces indicates a strong reduction in the volume of turbidity currents. Since major variations in channel gradient are absent, it is thought that variations in flow discharge rather than gradient determine channel sinuosity.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana