Late Neogene sediment composition and accumulation rates of ODP Hole 120-751A

Through scanning electron microscope analysis of sediment microfabric, we have evaluated variations in high-resolution shipboard physical properties (index properties and shear strength), sediment components (smear slide determinations), and shore-based calcium carbonate and biogenic silica data from Site 751 (Kerguelen Plateau). The stratigraphic section at this site records a change in biogenic ooze composition from predominantly calcareous (nannofossil) to siliceous (diatom) ooze from ~23 Ma to the present, reflecting expansion of Antarctic water masses during the late Neogene. The profound change in physical properties and sediment character at 40.1 mbsf (~5-6 Ma) evidently records the northward movement of the Polar Front and a change in absolute accumulation rates of sediment at this site. […]本研究通过扫描电子显微镜（scanning electron microscope）对沉积物微组构开展分析，评估了凯尔盖朗高原（Kerguelen Plateau）751站位的高分辨率船上物理性质（指标性质与抗剪强度）、沉积物组分（涂片测定结果），以及岸基碳酸钙与生物硅（biogenic silica）数据的变化特征。该站位的地层剖面记录了约23百万年至今的生物软泥组分演变：从以钙质（颗石藻，nannofossil）为主的软泥，逐步转变为硅质（硅藻，diatom）软泥，这一变化反映了新近纪晚期南极水团的扩张。海底以下40.1米（meters below seafloor, mbsf，约5~6百万年）处，物理性质与沉积物特征的显著转变显然记录了极锋（Polar Front）的北移，以及该站位沉积物绝对堆积速率的变化。[...]