@article{RegenbergStephNuernbergetal.2009,
  author    = {Regenberg, Marcus and Steph, Silke and Nuernberg, Dirk and Tiedemann, Ralph and Garbe-Schoenberg, Dieter},
  title     = {Calibrating Mg/Ca ratios of multiple planktonic foraminiferal species with delta O-18-calcification temperatures : paleothermometry for the upper water column},
  issn      = {0012-821X},
  doi       = {10.1016/j.epsl.2008.12.019},
  year      = {2009},
  abstract  = {In order to consistently approximate the thermal vertical structure of past upper water columns, Mg/Ca ratios of eight planktonic foraminiferal species with different preferential calcification depths selected from 76 tropical Atlantic and Caribbean sediment-surface samples were calibrated with delta O-18-derived calcification temperatures with an overall range of approximate to 8-28 degrees C. Extending the broad number of species-specific calibrations, which agree well especially with our shallow-dweller calibrations, this study presents new bulk calcite Mg/Ca vs. calcification temperature relationships for shallow-dwelling Globigerinoides ruber pink, thermocline-dwelling Globorotalia menardii, and deep-dwelling Globorotalia truncatulinoides dextral and Globorotalia crassaformis not separately calibrated before. The species-specific temperature sensitivities are relatively similar (approximate to 7- 11\% increase in Mg/Ca per 1 degrees C), yet y-axis intercepts vary from 0.23-0.65 for the shallow and thermocline dwellers to 0.83-1.32 for the deep dwellers. Based on these differences, we established a 'warm water' calibration for temperatures > 19 degrees C (Mg/Ca=0.29.exp(0.101.T): r=0.90; shallow and thermocline dwellers) and a 'cold water' calibration for temperatures < 15 degrees C (Mg/Ca=0.84.exp(0.083.T); r=0.85; deep dwellers). These calibrations are offset by approximate to 8 degrees C. This maybe significant for paleotemperature reconstructions, which are afflicted with the problem that similar Mg/Ca offsets are probably characteristic of extinct species used to calculate past temperatures.},
  language  = {en}
}