THE BENTHIC FORAMINIFERAL ASSEMBLAGE RECORD OF PALEOENVIRONMENTAL CHANGES DURING MIS 10-11 AT THE BLAKE OUTER RIDGE (WESTERN NORTH ATLANTIC, ODP SITE 1057)

Benthic foraminiferal assemblages were investigated in sediments from ODP Site 1057 (Blake Outer Ridge, 2600m water depth), spanning the MIS 10-11 time interval at a time resolution of approximately 5000 years. The ridge is a sediment drift produced by the interaction between the northward flowing surface waters of the Gulf Stream and the southerly flow of the Western Boundary Undercurrent (WBUC). Sedimentation rates in this area are high, due to the abundant supply of terrigenous material from northern sources via the WBUC, and possibly from southern areas via the Gulf Stream.

At Site 1057, interglacial MIS 11 is characterized by high relative abundances of epifaunal species indicative of oligotrophic environments, similar to modern conditions in this area. During glacial MIS 10, instead, the benthic assemblage is dominated by Bolivina (up to 58%) and other infaunal taxa indicative of organic carbon-rich sediments and/or lower oxygen conditions in pore water.