Controls on terrigenous sediment supply to the Arabian Sea during the lateQuaternary: the Indus Fan

A previous study on the basis of long-range side-scan sonar data (Kenyon et al., 1995. Geometry of the younger sediment bodies of the Indus Fan. In: P ickering, K.T., Hiscott, R.N., Kenyon, N.H., Ricci Lucchi, F., Smith, R.D.A . (Eds.), Atlas of deep water environments: architectural style in turbidit e systems. Chapman and Hall, London, pp. 89-93.) revealed a distributary co mplex of large channel-levee systems radiating from the mouth of the Indus Canyon and lower-order distributary complexes, each consisting of several s maller channel-levee systems, on the middle Indus Fan. Sediment cores from the Indus Canyon and the middle Indus Fan are analysed in this study in ord er to reconstruct the timing of turbidite sedimentation on the fan. Sedimen t cores from the middle fan show that turbidite sedimentation of the last b ut one switched to the last and youngest channel-levee system at the transi tion from oxygen-isotope stage 3 to 2 (similar to 24.8 C-14 ka BP) and ceas ed during the last deglaciation (similar to 11.5 C-14 ka BP). The Indus Fan is subsequently draped by a calcareous ooze of approximately Holocene age. Turbidite sedimentation continued up to (sub)recent times within the main feeder channel and Indus Canyon. The geochemical, mineralogical and grain-s ize analyses suggest that the sediments deposited on the middle fan during the last glacial period were mainly supplied by the indus River (fluvial se diments) while during the Holocene they were derived predominantly from the Arabian Peninsula (eolian dust). Although major erosional and depositional cycles on the Indus Fan are strongly controlled by changes in sea level, c limate-induced differences in sediment supply and autocyclic mechanisms als o influenced fan sedimentation. (C) 2000 Elsevier Science B.V. All rights r eserved.