Title:
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Temporal and contemporary fine-grained sedimentation across the Indus sedimentary system
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The research presented within this thesis makes up a steady of fine-grained sediments of the Indus River, Indus Shelf/slope, Indus Canyon, and the pelagic/hemipelagic and the turbidite units of the Indus Fan. The material presented herein proposes the source, dispersal patterns and mode of transportation of fine-grained sediments in the fluvial, littoral and deep-sea environments. At present, the supply of sediment from the Arabian Sea to the estuary of the Indus River is apparently more pronounced than the sediment supplied by the river to the sea. This is a consequence of the reduction of sediment load resulting from the construction of dams and barrages on the Indus River. Two dispersal patterns are proposed for the dispersion of Indus River derived fine-grained sediments on the Indus Shelf. The first dispersal pattern originates from the Indus River mouth and flows roughly parallel to the coast. The wind-induced currents move the sediments to the southeast or northwest depending upon the prevailing monsoon. A second transport pathway appears to follow the canyon axis. However, at present, little or no transportation is in progress via the canyon because the movement is alongshore in conjunction with the current pattern and deposition of the fluvial mud is largely confined to the delta area. The pelagic/hemipelagic facies covers a large area on the fan as only a small portion of the fan was subjected to terrigenous derived sedimentation because of the high sea-level stand during the Holocene. The terrigenous sediments are trapped within the Indus Delta and thus the fan became the site of predominantly pelagic/hemipelagic sedimentation; this is represented by the draping of foraminiferal-nannoplankton ooze over the entire channel-levee system. Beside indicating increased surface water productivity the pelagic interval may also indicate decreased clastic influx.
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