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dc.contributor.authorRosenthal, Yair
dc.contributor.authorMorley, Audrey
dc.contributor.authorBarras, Christine
dc.contributor.authorKatz, Miriam E.
dc.contributor.authorJorissen, Frans
dc.contributor.authorReichart, Gert-Jan
dc.contributor.authorOppo, Delia W.
dc.contributor.authorLinsley, Braddock K.
dc.identifier.citationRosenthal, Yair, Morley, Audrey, Barras, Christine, Katz, Miriam E., Jorissen, Frans, Reichart, Gert-Jan, . . . Linsley, Braddock K. (2011). Temperature calibration of Mg/Ca ratios in the intermediate water benthic foraminifer Hyalinea balthica. Geochemistry, Geophysics, Geosystems, 12(4), n/a-n/a. doi: 10.1029/2010GC003333en_IE
dc.description.abstractCore top samples from Indonesian and northeast Atlantic depth transects were used to calibrate Mg/Ca and δ18O in tests of the calcitic benthic foraminifer Hyalinea balthica to bottom water temperature between 4°C and 13°C. This shallow infaunal species is primarily abundant in neritic to upper bathyal sediments (<600 m). Both linear and exponential calibrations suggest a temperature sensitivity of ∼12% per °C that is ∼4 times higher than observed in other species of deep-sea benthic foraminifera. Culture experiments support the core top calibration. We find no discernible effect of salinity and saturation on Mg/Ca. Comparison between the measured benthic foraminiferal δ18O and predicted equilibrium values suggests that on average H. balthica δ18O is 0.64‰ ± 0.13‰ lower than predicted from the equilibrium composition. To test the reliability of using paired H. balthica Mg/Ca and δ18O measurements for reconstructing seawater δ18Osw and salinity, we apply this calibration to another depth transect from Cape Ghir off NW Africa, which was not included in the calibration. Based on error analysis of the calibration data and this validation test, we show that the uncertainty of reconstructing bottom water temperature and salinity from paired Mg/Ca and δ18O measurements of H. balthica is better than ±0.7°C and ±0.69 practical salinity scale, respectively. The small uncertainties allow for the reconstruction of seawater density to better than 0.3σθ units, which is precise enough for the identification of specific water masses and reconstruction of changes in their properties. We propose that the relatively high Mg content and temperature sensitivity of H. balthica might be due to minor, biologically mediated contribution of high-Mg calcite to the primarily low Mg calcite test, which is influenced by the ambient temperature. This hypothesis, if correct, suggests that benthic species with relatively high Mg/Ca may be better suited for deepwater temperature reconstructions than species that have thus far been more commonly used.en_IE
dc.description.sponsorshipNSF Awards OCE 02‐20922 and 09‐02977 toYR, OCE 09‐28607 to MK, OCE02‐20776 to DWO, and DFGpriority program INTERDYNAMIK to AM. Indonesian Agency for Assessment and Application of Tech-nology (BPPT), the Center of Research and Development forOceanography (LIPI) for their help in organizing and fundingthis cruiseen_IE
dc.publisherAmerican Geophysical Unionen_IE
dc.relation.ispartofGeochemistry Geophysics Geosystemsen
dc.subjectBenthic foraminiferaen_IE
dc.subjectTemperature calibrationen_IE
dc.titleTemperature calibration of Mg/Ca ratios in the intermediate water benthic foraminifer Hyalinea balthicaen_IE
dc.local.contactAudrey Morley, Geography, School Of Geography, & Archaeology, Nui Galway. Email:

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