Potential drilling locations at the Argentine continental margin to investigate the Cenozoic history of South Atlantic deep water circulation
Persistent geostrophic currents interacting with sea-floor topography and available sediment sources are capable of eroding, transporting and depositing fine-grained particles into mounded and elongated sediment drifts. These drifts show enhanced accumulation rates when compared to pure pelagic sequ...
| Main Authors: | , , |
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| Format: | Conference Object |
| Language: | unknown |
| Published: |
2013
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| Subjects: | |
| Online Access: | https://epic.awi.de/id/eprint/32252/ https://hdl.handle.net/10013/epic.40984 |
| Summary: | Persistent geostrophic currents interacting with sea-floor topography and available sediment sources are capable of eroding, transporting and depositing fine-grained particles into mounded and elongated sediment drifts. These drifts show enhanced accumulation rates when compared to pure pelagic sequences and are thus attractive targets for high resolution paleoceanographic studies. Several expeditions of the IODP/ODP (e.g. 162, 172, 303, 306, 339, 342) therefore have successfully targeted giant contourite drifts. An unexplored area in this context is a prominent contourite depositional system (CDS) located in the southernmost sector of the extensional Argentine margin. Here the thermohaline circulation is characterized by the interaction of northwardflowing Antarctic water masses (Antarctic Intermediate Water, AAIW; Circumpolar Deep Water, CDW; Antarctic Bottom Water, AABW) and southward-flowing North Atlantic Deep Water (NADW). The transfer of heat and energy via these water masses constitutes an important component in maintaining the global ocean conveyor belt. We investigate an extensive set of high quality seismic reflection profiles from the Argentine continental margin to detect, characterize and map sedimentary features related to bottom current activity and to reconstruct past changes in the abyssal circulation. Typical margin-parallel morphosedimentary features such as (1) a set of four terraces on the slope and rise, (2) channels separating the terraces, (3) a giant buried sediment drift, and (4) sheeted drifts on the abyssal plain indicate that along slope (contour current) transport dominates over downslope (turbiditic) processes at the southern Argentine margin. Along the central Argentine margin the relative importance of the permanent, steady bottom currents and the shorter-duration, unsteady mass wasting processes on sediment deposition was variable in time and space. Based on a detailed investigation of a continental slope terrace at the southern margin and the mapping of depocenter geometries ... |
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