The role of downslope versus alongslope sediment transport over the last glacial cycle on the Scotian Rise

Abstract

Little work has been done on the Scotian Rise to identify the mode of sediment transportation. Specifically, identifying to what extent the Western Boundary Undercurrent (WBUC) influences the Scotian Rise and how previous ice advances and retreats may have played a role in this sediment transport. The physical properties of two piston cores located on the Central Scotian Rise south of Western Bank were analysed to identify the sources of six recognized sediment units. The overall framework for age was established by C-14 dating and the recognition of Heinrich events (H-events). The age model corresponding to the units could then be linked to stadial and interstadial times via marine isotopic stages (MIS). The sources of sediments were mostly from glacial supply from the Appalachians and erosion of the Scotian Shelf, as indicated by numerous physical properties, such as clay mineralogy, Nd isotopes, pXRF and spectrophotometry data. The sources and the corresponding ages of the units developed in this study indicate the Scotian Rise typically experienced downslope transport during stadial periods (units II, III, V, VI), and alongslope transport during interstadials in unit I (MIS I) and IV (early MIS 3). The data confirm that a major glacial advance (Caledonia phase) took place in Nova Scotia in MIS 4, reaching the edge of the shelf.