Continental shelves mark the zone between the terrestrial environment and deep marine realm and so are important for understanding sediment transport to the deep ocean. This study investigates the storage and potential record of the terrestrial environment on the Indus Shelf in the North Arabian Sea. The Indus Shelf records the development of clinoform sequences responding to sea level rise since at least the Mid Quaternary. Mapping of sedimentary and structural features established a clear link between sediment transport, deformation and sediment facies. Dome structures in the nearshore zone provide accommodation space on the slope for clinoform development through relative subsidence of neighbouring strata. All clinoforms contain partially eroded topsets formed during sea level fall. Multi-proxy analyses of two cores from the western shelf failed to establish a clear link between the continental record of provenance and weathering from the subaerial Indus Delta and the Indus Shelf system during the Holocene. The dominant source of sediment to the Indus Shelf appears to be erosion of Indus Delta sediments deposited during previous lowstands. During the Early Holocene some sediment is supplied to the north-west shelf from the Makran region due to the strengthening of the Asian Monsoon initiating the northwest to southeast longshore current and mixes with the Indus sediment. Estimates of mineral composition through a six end member algorithm further suggest very little relationship between provenance, weathering and published climatic records before sea level reached present levels. This thesis suggests that the Indus shelf, a high energy, a high sediment supply shelf, stores significant quantities of sediment derived from terrigenous sources. However, erosion and reworking processes mean that the record is not a good indicator of conditions in the terrestrial environment at the time of deposition.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:569631 |
| Date | January 2012 |
| Creators | Limmer, David |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=192321 |
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