Variations in sediment transport at the central Argentine continental margin during the Cenozoic

Gabriele.Uenzelmann-Neben [ at ]


The construction of the sedimentary cover at most passive continental margins includes gravitational downslope transport and along-slope contourite deposition, which are controlled by tectonics, climate and oceanography. At the eastern continental margin of Argentina the history of deposition and erosion is intimately linked to the evolution of the South Atlantic and its water masses. Here we present a detailed seismic investigation of the mixed depositional system located between 41°S and 45°S. The study provides a northward complement to prior investigations from the southern Argentine margin and together with these may be used as background information for future ocean drilling in the region. Prominent features in our seismic cross sections are submarine canyons, mass wasting deposits, contourite channels, and sediment drifts. Four major seismic units above regional reflector PLe (∼65 Ma) are separated by distinct unconformities of regional extent. Using a dense grid of reflection seismic profiles, we mapped the depocenter geometries of the seismic units and derived a chronology of the depositional processes during the Cenozoic. While the Paleocene/Eocene (∼65–34 Ma) is characterized by hemipelagic sedimentation under relatively sluggish bottom water conditions, strong Antarctic bottom water (AABW) circulation led to widespread erosion on the slope and growth of a detached sediment drift during the Oligocene and early Miocene (∼34–17 Ma). After deposition of an aggradational seismic unit interpreted to represent the Mid-Miocene climatic optimum (∼17–14 Ma), gravitational downslope sediment transport increased during the middle to late Miocene (∼14–6 Ma) possibly related to tectonic uplift in South America. The Pliocene to Holocene unit (<∼6 Ma) is very heterogeneous and formed by interactions of downslope and along-slope sediment transport processes as indicated by the evolution of canyons, slope plastered drifts and channels.

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DOI 10.1029/2012gc004266

Cite as
Gruetzner, J. , Uenzelmann-Neben, G. and Franke, D. (2012): Variations in sediment transport at the central Argentine continental margin during the Cenozoic , Geochemistry Geophysics Geosystems, 13 , Q10003 . doi: 10.1029/2012gc004266

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