Deep-water temperatures from the Southern Ocean during HS4

Foraminiferal magnesium to calcium ratios (Mg/Ca) are reported for two benthic species, drawn from down-core marine sediment samples obtained from the deep Southern Ocean. Samples of 4-10 individual benthic foraminifera, of the species Globobulimina affinis and/or Uvigerina sp., were oxidatively cleaned according to a standard protocol, involving clay/detrital material removal, methanol rinses, buffered oxidation of organic matter, weak acid leaching, and deionised water rinses, followed by visual inspection of the remaining calcite fragments. After dissolution, samples were analysed by inductively coupled plasma mass spectrometry (ICP-MS). The analytical internal reproducibility is better than 2%. The efficiency of cleaning to remove external contaminant phases was screened on the basis of Fe/Ca ratios, which here remain below 0.05 mmol/mol.