Investigating interspecies correction factors and extending the applicability of benthic foraminiferal oxygen isotopes studies

• Applicant: Dr. Ann Holbourn
• Subject Area: Palaeontology
• Term: from 2014 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 269869248

The oxygen isotopic composition of benthic foraminiferal shells is one of the fundamental tracers to decipher global variations in ice volume and past changes in the temperature and salinity of oceanic water masses. Despite its use as a paleoceanographic proxy for several decades, there is still considerable debate concerning the temperature dependence of benthic foraminiferal oxygen isotopes and the constancy of offsets between coexisting species. The main objectives of this project are: (1) to evaluate interspecies oxygen isotopic offsets in ten benthic foraminifers that commonly occur in intermediate- to deep-water masses, (2) to test the hypothesis of a significant influence of pH/carbonate ion concentration on the isotopic composition of infaunal foraminiferal tests and (3) to provide constraints for interspecific oxygen isotope calibrations in order to extend the applicability of composite benthic records over the Holocene to Neogene periods. Our core top calibrations will target the tropical Indo-Pacific region, which has so far been sparsely investigated and offers the opportunity to test carbonate ion effects over a wide range of bottom and pore water concentrations, using a consistent methodology. We will contrast these records with new calibration data from the eastern North Atlantic Margin, characterized by well-ventilated bottom water masses and pore waters with reduced carbonate ion concentrations. Finally, we will integrate our findings with published data from other oceanic settings to further explore the range of regional variability in interspecies oxygen isotopic offsets.

• DFG Programme: Research Grants