Distribution of benthic foraminifera with related sedimentological hydrographic parameter in the eastern Weddell Sea, Antarctica

Below this, on the upper slope down to 2000 m water depth, the predominantly calcareousBulimina aculeata assemblage coincides with the core of warm (>0°C) Weddell Deep Water and with fine and more organic-rich sediments. These calcareous live assemblages completely change composition during early diagenesis because of calcite dissolution within the uppermost sediment, which depends largely on the grain size distribution of the sediment and the fluxes of organic matter.

Therefore, a still calcareousT. angulosa-dominated fossil assemblage indicates the sandy substrates on the shelf break and the upper slope, whereas the deeper slope with hemipelagic calm sedimentation and with high fluxes of organic matter is indicated byMartinottiella nodulosa, the characteristic arenaceous fossil remnant of the former predominantly calcareous liveB. aculeata fauna. On a continental terrace between 2500 and 3500 m water depthCribrostomoides subglobosus dominates the live fauna, but because of rapid disintegration of the empty tests of this agglutinated species a predominantly calcareous fauna characterized byOridorsalis umbonatus andEpistominella exigua comprises the dead assemblage and the potential fossil assemblage, respectively.

On the lower continental slope, between the carbonate lysocline (3500 m) and the carbonate compensation depth (4000 m), tests ofNuttallides umbonifer are the characteristic dead and potential fossil remnants of a former predominantly arenaceous live fauna, which is associated with the lower part of the Antarctic Bottom Water (AABW). This corroborates earlier investigations suggesting a relationship between the carbonate-corrosiveness of water masses and the distribution of N. umbonifer.

This is important for inferring paleo-routes and estimates of paleo-production rates of AABW during the Neogene.