Middle Miocene seawater isotope evolution at IODP Site 307-U1318@en

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).中新世中期（16.6–12.8 Ma）的烯酮氢同位素与海水温度数据，采自综合大洋钻探计划（Integrated Ocean Discovery Program, IODP）307航次在东北大西洋豪猪盆地（Porcupine Basin）钻探获取的U1318站位沉积物岩芯，该站位水深约400米。表层海水同位素值基于C37长链烯酮的氢同位素组成（δ²H_C37），并采用Gould等人（2019，doi:10.1016/j.gca.2018.12.004）的环境校准方法计算得到。底层海水同位素值则基于底栖有孔虫的氧同位素数据（数据源自Quaijtaal等人，2018，doi:10.1017/S0016756816001278）以及次表层温度（subsurface temperature, subT）估算结果（TEX86H指标）。本研究采用Cramer等人（2011，doi:10.1029/2011JC007255）的校准方法，并结合Kim等人（2012，doi:10.1029/2012GL051157）提出的0-200米水深层位计算公式，完成了次表层温度的计算。