STABLE ISOTOPE BASED TEMPERATURE RECONSTRUCTION IN THE NORTHERN NORTH ATLANTIC DURING THE EARLY-MIDDLE MIOCENE
Our results show that planktonic foraminifera from Site 982 record a 1.25‰ increase in δ18O values between 15.5-12.5 Ma. Accounting for ice volume difference using Miller et al. (2020) ice volume estimates, SSTs varied between 14-17°C during the MCO and cooled to 10-12°C with the MMCT. Our benthic foraminiferal δ18O values record a 0.5‰ increase reflecting a 2-3°C deep-water cooling following the MCO. In contrast, the UK’37 and TEX86 based SSTs recorded modest cooling (<2°C) and remained >22°C through the MCO and subsequent Antarctic Ice sheet growth. Resolving disparity in SST proxies is important because they present two different and possibly incompatible scenarios. The biomarker-based estimates require an asymmetry in cooling with the subpolar North Atlantic maintaining subtropical conditions while the southern subpolar region cooled dramatically. We favor the stable isotope SST reconstruction because 1) the cooling coincides with CO2 decreases and the growth of a large ice sheet on Antarctica and 2) the resulting SST estimates following the MCO are similar to the modern seasonal SSTs over Rockall Plateau (10-13°C).