Tracking abrupt climatic events for the last 40 kyr in SW Iberia (Gulf of Cadiz) - Preliminary results

The last 40 kyr encloses the Late Pleistocene-Holocene transition, mainly characterized by an evolution from a glacial to an interglacial period. Moreover, this temporal window presents important abrupt climatic oscillations, like the Heinrich events (H1 to H4), Green Sahara, Greenland stadials and Younger Dryas event. The effects of this complex climatic evolution in the southern offshore Portugal still poorly understood. Moreover, the origin of the sedimentary layers related to abrupt climatic changes still a matter of debate, being pointed three main hypotheses: i) melting of icebergs around core location, i.e., the polar front reached lower than presently thought; ii) dust that comes from NW Africa and; iii) deposition of contourites from the Mediterranian in Algarve offshore oceanic basin during cold periods. In order to track these abrupt events a piston core with 350 cm length, retrieved at 3520 m water depth south of Portimão Bank, underwent detailed environmental magnetism, sedimentological (grain-size, carbonates, organic matter) and X-ray fluorescence (XRF) geochemical analyses, complemented by AMS 14C dating. Preliminary results of this multidisciplinary approach well identify all the main abrupt climatic events known for the last 40 kyr, being the source of the main ferromagnetic phases discussed