Paper Number: 1316
Zambezi continental margin:
allocyclic and antecedent controls on sediment transport in the
Mozambique Channel.
Wiles, E.A.1,
2*, Green, A.N.1, Watkeys, M.K. 1and Jokat,
W.3
1 University of KwaZulu Natal, Westville, 4000, South Africa. *eawiles@yahoo.com
2 Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.
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Sediment delivery to the abyssal regions of the oceans is an integral process in the source to sink cycle of material derived from the hinterland. How sediments are transported down-slope, and where they are deposited has implications for the mass balance of the upper lithosphere, hydrocarbon reserves, climate archives and sequence stratigraphic models [1]. The Zambezi River, the largest in southern Africa, delivers vast amounts of material to the continental shelf, submarine Sofala/Zambesia Bank, of central Mozambique. The Sofala/Zambesia Bank acts as a staging area for this riverine input prior to its redistribution toward the abyssal plains of the Mozambique Channel [2] [3]. Much of this material is said to be directed into the submarine Zambezi Valley and Channel [5] [6][7][8]. Until this study the exact sediment transport dynamics between the Sofala/Zambesia Bank and abyssal plains of the Mozambique Channel have been poorly understood and constrained. The aim of this contribution is to better constrain sediment transport pathways to the abyssal plains, taking into account the effects of bottom water circulation, antecedent basin morphology and sea level change. Results show that sediment transport and delivery to the abyssal plains is discreetly partitioned into southern, central and northern domains. This sediment partitioning is primarily controlled by changes in continental shelf, and shelf break, morphology and a dynamic anticyclonic inshore circulation system, while changes in sea level have an overarching control on sediment delivery to particular domains at various sea levels. A direct consequence of these controlling factors is limited sediment delivery to the submarine Zambezi Valley and Channel in the present-day, with increased activity envisaged during regression. Furthermore, the switching “on” and “off” of discrete domains along strike is a sequence stratigraphic concept generally not previously considered in the shelf-slope-abyssal continuum.
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