Middle Miocene seawater isotope evolution at IODP Site 307-U1318

Mid-Miocene (16.6 – 12.8 Ma) hydrogen isotopes of alkenones and sea temperatures are obtained from the sediment record of Integrated Ocean Discovery Program (IODP) Expedition 307, Site U1318 drilled in the Porcupine Basin, north east Atlantic at a water depth of ~ 400 m. Surface seawater isotopes are calculated based on the hydrogen isotopic compositions of C37 long chain alkenones (δ2HC37) with the environment calibration of Gould et al. (2019, doi:10.1016/j.gca.2018.12.004). The bottom seawater isotopes are based on oxygen isotopes of benthic foraminifera (record from Quaijtaal et al., 2018, doi:10.1017/S0016756816001278) and subsurface temperature (subT) estimates (TEX86H). We applied the calibration of Cramer et al. (2011, doi:10.1029/2011JC007255) and calculated subT with the 0-200 m equation of Kim et al. (2012, doi:10.1029/2012GL051157).