Middle slope contourite deposits and associated sedimentary facies off NE Argentina
In: Geo-Marine Letters. Springer: Heidelberg; Berlin. ISSN 0276-0460; e-ISSN 1432-1157, more
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| Author keywords |
Last Glacial Maximum; Sedimentary Facies; Lithic Fragment; North Atlantic Deep Water; Middle Slope |
| Authors | | Top |
- Bozzano, G.
- Violante, R.A.
- Cerredo, M.E.
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| Abstract |
The Argentine continental margin is characterised by a large contourite depositional system driven by southern-sourced water masses flowing at different water depths. Interest in contourite deposits is increasing in geoscience and related fields, though knowledge of the Argentine contourite system is still limited. In particular, studies based on core data providing detailed descriptions of sedimentary facies are lacking, as are investigations of principal sediment source areas and of key factors controlling sedimentary processes. This study combines visual core description and downcore grain-size analyses as well as petrographic thin-section and magnetic susceptibility analyses of 14 cores from intermediate water depths of 616–1,208 m to characterise contourite deposits on the north-eastern Argentinean slope. Gravel-rich, sandy–silty and muddy contourites as well as hemipelagic facies were identified. The deposition of these contourites was presumably controlled by sea level, the depth range of the Antarctic water mass, climate conditions and windborne terrigenous supply. It is proposed that, during glacial lowstands, muddy contourites were deposited at depths <900 m, whereas sandy–silty sequences dominated at deeper depths. During the late Pleistocene–Holocene transition, sandy–silty contourites covered the entire middle slope. Hemipelagic facies draped limited sectors of the middle slope when the sea level reached the present-day position and gravel-rich contourites became restricted to contouritic channels and moats. Northern Patagonia and the southern Pampa are the most plausible sources for sediments deposited via along-slope processes, whereas the Tandilia Range is the best candidate for sediments deposited via down-slope processes. |
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