Controls on terrigenous sediment supply to the Arabian Sea during the late Quaternary: the Makran continental slope M.A. Prins a, * , G. Postma a , G.J. Weltje b,c a Institute for Paleoenvironments and Paleoclimate Utrecht (IPPU), Faculty of Earth Sciences, Utrecht University, Utrecht, The Netherlands b Department of Geo-Energy, Netherlands Institute of Applied Geoscience TNO, Utrecht, The Netherlands c Subfaculty of Applied Earth Sciences, Delft University of Technology, Delft, The Netherlands Received 6 August 1999; accepted 26 June 2000 Abstract The input of terrigenous sediment along the tectonically active Makran continental margin off south-western Pakistan (Gulf of Oman, northern Arabian Sea) is studied on the basis of sediment cores distributed along a transect from the upper slope to the abyssal plain. Spatial and temporal variations in sediment composition, sedimentation rate and turbidite frequency in late Pleistocene–Holocene time (last 20 14 C ka) will be discussed and related to changes in sea level and climate, and tectonic activity. End-member modelling of the grain-size distributions of the hemipelagic and turbiditic sediments indicate that the sediments are adequately described as mixtures of three end-members, which represent turbidite sand, turbidite silt or eolian dust, and fluvial mud. The geochemical and mineralogical compositions of the hemipelagic sediments indicate that the eolian dust was dominantly supplied from the northern Arabian Peninsula and the Persian Gulf region, and that the fluvial input is from the Makran margin. The ratio of contributions of eolian and fluvial sediment in the hemipelagic intervals is used as an indicator of continental aridity, i.e. summer monsoon intensity. Highest Holocene turbidite frequencies and sedimentation rates are recorded at the deepest coring sites. They are related to the proximity of the deformation front of the accretionary prism. Turbidite sedimentation on the upper continental slope was most frequent during the last glacial period of sea-level lowstand, and continued during the entire deglaciation and sea-level rise. Infrequent turbidite sedimentation occurred during the Holocene highstand of sea level. Turbidite sedimentation during the period of late sea-level rise and the Holocene sea-level highstand is inferred to be due to the strong impact of episodic events (i.e. flash floods and earthquakes) and because of the narrow shelf of the active Makran continental margin.  2000 Elsevier Science B.V. All rights reserved. Keywords: Turbidite; Eolian dust; Grain-size analysis; Arabian Sea; Sea level; Monsoon climate 1. Introduction Changes in sea level and climate of river-delta–fan systems can result in distinctly different fan deposits depending on whether the river system discharges onto a passive or an active continental margin. The largest Quaternary deep-sea fan systems have devel- oped along passive continental margins and are fed by large, lowland river systems. Turbidite sedimentation on such deep-sea fan systems is primarily controlled by glacio-eustatic sea-level fluctuations. During the Marine Geology 169 (2000) 351–371 0025-3227/00/$ - see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0025-3227(00)00087-6 www.elsevier.nl/locate/margeo * Corresponding author. Present address: Faculty of Earth Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands. E-mail address: prim@geo.vu.nl (M.A. Prins).