Pelagic, hemipelagic and turbidite deposition in the Arabian Sea during the late quaternary : unravelling the signals of eolian and fluvial sediment supply as functions of tectonics, sea-level and climate change by means of end-member modelling of siliciclastic grain-size distributions

Abstract

Tectonics, sea-level changes and variations in climate are the major controlling factors on the input of terrigenous sediments in ocean basins over long periods of time. Two important mechanisms define the timing of high-frequency changes in the sedimentary record of the late Quaternary: glacio-eustatic sea-level change and climate change. Lowering of sea level enhances sediment transport by slope instability processes, by enlargement of the drainage basin through exposure of the shelf and by increasing the river's competence through baselevel lowering. Climate change from an arid into a humid climate may result in an increase in river discharge and thus in an increased fluvial sediment transport into deep-sea fan systems. On the other hand, a change into a dry climate may increase the eolian transport of finegrained terrigenous material. These mechanisms for increased sediment transport are 'end members' of a spectrum, in which sea-level lowstand and high river discharge during favourable humid-climate periods on the one hand, and enhanced eolian activity during favourable arid-climate periods on the other hand can be in phase or out of phase. The main objectives of this project are to unravel late Quaternary Arabian-Sea records of fine-grained terrigenous sediments, and to reconstruct the flux and provenance of these sediments. The reconstructed 'mass balance' (origin, timing, volume and distribution) of the terrigenous sediments deposited in the Arabian Sea during the late Quaternary will be related to glacio-eustatic sea-level changes, to the paleoclimate evolution of the surrounding continental areas and to the tectonic setting of the sedimentary systems. The outcome of the project will allow insights into the phase relationship of glacio-eustatic sea-level changes and climate changes and their effects on terrigenous sediment distribution in the Arabian Sea.