Palaeo-ice stream dynamics in the North-western Barents Sea depicted from clay mineral analyses

The Arctic Ocean is one of the most climatically vulnerable areas on the planet, being a crossway of oceanic circulation. The study of high latitude continental margin sediments is useful for understanding past ice sheet dynamics history and its influence on climate changes. This PhD project focuses on the sedimentation history along the North-western Barents Sea continental margin from the Marine Isotope Stage (MIS) 3 to the Holocene. During the Last Glacial Maximum (LGM), around 21.000 years ago, this area was covered by the Svalbard-Barents Sea Ice sheet (SBSIS). The sedimentary record contained in the Kveithola and Storfjorden Trough Mouth Fans (TMFs) and in the contouritic drift facing the Bellsund glacial trough provides compositional information which can be useful for reconstructing the ice-streams dynamics during glacial periods, the onset of deglaciation and the climatic variability during interglacials. The geological dataset analysed for this PhD thesis, was collected during four international oceanographic cruises undertaken within international projects: SVAIS project onboard R/V BIO Hespérides; EGLACOM project, onboard R/V OGS Explora; the PNRA Project CORIBAR, onboard R/V Maria S. Marien; and the Eurofleets-2 PREPARED project, onboard RV-G.O. Sars. In this study a total of 6 sediment cores have been considered along a 200 km-long transect, SW–NE oriented along the continental margin. Four short cores have been previously analysed for different purposes, whereas the two long cores located at the opposite ends of the transect, and containing very expanded depositional sequences, have been investigated for sedimentological (water content, grain size) and compositional characteristics (XRD-clay minerals and XRF analyses). In particular, we focused this investigation on the use of clay mineral analyses as a tool for reconstructing sedimentary processes correlated with glacial dynamics, which use is often under-estimated in polar areas, especially for palaeoclimatic reconstructions. Core correlation between cores was referred to an existing age model based on palaeomagnetic analyses and 35 radiocarbon dates mainly made on planktonic foraminiferal tests. The clay mineral analysis pinpointed the high palaeoceanographic variability of the West Spitsbergen Current during the Holocene outlining the existence of additional minor (centennial-scale) climatic variations recorded at regional scale. This study proved new compositional proxies, based on the clay mineral content, that outlined a high glacial dynamism during MIS-3, with warm intervals timed with the well-known Heinrich-events and, therefore, pointing out the complexity of the climatic feedback mechanisms in polar areas.