Annotated record of the detailed examination of Mn deposits observed by the CESAR Canadian Station in the Alpha Ridge, Arctic Ocean

An evaluation is made of the sediment transport pathways which lead to the accumulation of the bottom material in the vicinity of the Alpha Ridge. An estimate is also given of the sources of the material, the factors controlling deposition and, where appropriate, on the accumulation rates. Biogenic material, ice-rafted debris and weathered bedrock by- products make up the majority of the seabed sediment. The relative abundance of each component varies from the Alpha Ridge crest to the trough. Minor amounts of eolian-derived debris were detected in the pack ice and yet lower amounts of inorganic debris were measured in the water column. Ice-rafted pebbles and cobbles were generally rounded and calcerous. Which suggests a source from a coastal region on the adjacent Canadian landmass. The recovery of bedrock in the dredging program verifies the occurrence of outcrops on the south flank of the northern Alpha Ridge crest. The samples recovered are (1) well weathered basalts which have an elemental composition similar to floes sampled in the ice pack and water column, and (2) from fine grained sediment samples recovered from adjacent basins. A local bedrock source of bottom sediments had not hitherto been considered significant.