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

底栖有孔虫壳的氧同位素组成是解释全球冰量变化和海洋水体温度和盐度变化的基本示踪剂之一。尽管它作为古海洋学的代用物已经使用了几十年，但关于底栖有孔虫氧同位素的温度依赖性和共存物种之间补偿的稳定性仍然存在相当大的争论。该项目的主要目标是：(1)评估中深水块中常见的10种底栖有孔虫的种间氧同位素偏移；(2)验证pH/碳酸盐离子浓度对动物有孔虫测试的同位素组成有显著影响的假设；(3)为种间氧同位素校准提供约束条件，以便将全新世复合底栖生物记录的适用性扩展到新近纪。我们的核心顶级校准将针对热带印度洋-太平洋地区，该地区迄今为止研究较少，并提供了使用一致的方法在大范围的底部和孔隙水浓度下测试碳酸盐离子效应的机会。我们将这些记录与北大西洋东部边缘的新校准数据进行对比，这些数据的特征是通风良好的底部水团和碳酸盐离子浓度降低的孔隙水。最后，我们将把我们的发现与其他海洋环境的已发表数据结合起来，进一步探索物种间氧同位素抵消的区域变异范围。

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.