Carbon isotopic fractionation of alkenones and Gephyrocapsa coccoliths over the Late Quaternary (Marine Isotope Stages 12 to 9) glacial-interglacial cycles at the western tropical Atlantic

Here we present εp measured on natural fossil samples across the glacial-interglacial (G-I) MIS 12 to MIS 9 (454-334 ka) interval at the western tropical Atlantic Ocean Drilling Program Site 925 together with a set of organic and inorganic geochemical, micropaleontological and morphometrical data from Gephyrocapsa coccolith on the same samples. Primary productivity and export production, potentially triggered by shifting growth rates and light level conditions, and the changes in Gephyrocapsa cellular dimensions are controlled by either proxies or direct measurements, allowing to parse out the load of non-CO2 effects on εp. We also determined oxygen and carbon stable isotope vital effects in the near monogeneric separated Gephyrocapsa coccoliths (respectively δ18O Gephyrocapsa-T. sacculifer and εcoccolith)本研究报道了西热带大西洋大洋钻探计划（Ocean Drilling Program, ODP）925站位、覆盖冰期-间冰期（G-I）MIS 12至MIS 9（454~334 ka）时段的天然化石样品所测得的εp值，以及同一样品中桥石藻（Gephyrocapsa）颗石的一系列有机地球化学、无机地球化学、微古生物学及形态计量学数据。初级生产力与输出生产力（其变化可能由生长速率及光照条件改变所驱动）、桥石藻细胞尺寸的变化，均可通过代用指标或直接测量进行约束，从而得以解析非CO₂效应对εp的贡献量。本研究还对近乎单属分离的桥石藻颗石中的氧、碳稳定同位素生命效应进行了测定（分别对应桥石藻-T. sacculifer δ¹⁸O值及εcoccolith）。