Palaeoceanography and sedimentology of the Gulf of Cadiz (0-30ka, BP)

• Main Author: Rogerson, Michael
• Format: Thesis
• Language: English
• Published: University of Southampton 2003
• Subjects: North Atlantic Deep Water; North Atlantic
• Online Access: https://eprints.soton.ac.uk/465285/; https://eprints.soton.ac.uk/465285/1/937882.pdf

Evidence is presented for the presence of the Azores Front in the northern Gulf of Cadiz prior to 16ka BP, and its subsequent withdrawal during the last deglaciation. It is conducted that the North Atlantic warm water sphere was comparable in extent to today during the latter parts of the last glaciation. It is also proposed that the Mediterranean Outflow plume settled to greater depths during the last glaciation, on the basis that evidence for its presence is found on the Gil Eanes Drift (the lowermost part of the Gulf of Cadiz contourite) but is not found in the modern flow path of the plume. This observation is consistent with predictions made from the physical constraints on the current system, and will have significant and potentially wide-ranging impact for the circulation of the Atlantic at all depths. In addition to its direct influence, the relatively shallow settling depth of the modern Mediterranean Outflow plume may promote the formation of North Atlantic Deep Water and thus enhance the meridional overturning. Sea-level/climatic variation are proposed as the cause of contourite cycles on both large and small scales. The implications of observed anti-phasing of depositional cycles on the Gil Eanes Drift and the rest of the Gulf of Cadiz drift are discussed. Sediment deposited on the Gil Eanes Drift is found to be ultimately sourced from southwestern Iberia, initially deposited on the continental shelf and then reworked onto the slope where it is energetically sorted by the waning Mediterranean Outflow Plume and deposited on the sediment drift. High-resolution colour data scanning is proposed as a tool for palaeoceangraphy, both as a correlation tool and for delineation of sedimentary flux to a location. Supply of terrigenous material to the western Gulf of Cadiz is found to be significantly enhanced during glacial times.