Mean grain-size and sorting of sediments from the Piedra Buena contourite terrace

The dataset contains results of grain-size analyses of sediments after removing the biogenic calcium carbonate, the biogenic opal and organics.
Grain-size analyses were performed using a SALD-2300 laser diffraction particle size analyzer (Shimadzu, Japan), which yields a size spectrum from 17 nm to 2.5 mm. Grain-size analysis was performed both on the bulk sediment samples and calcium carbonate-free samples. Hydrochloric acid (10%) was used to remove biogenic calcium carbonate. For core AI-3442, where the radiolarian content is relatively high compared to the rest of the cores, the biogenic opal was removed using 1M sodium hydroxide solution (NaOH). H2O2 was used to remove organics. Sodium hexametaphosphate solution (Na6P6O18, 0.7%) and ultrasonication (1 min) were applied to all the studied samples for particle disaggregation. Mean grain size and sorting coefficient were calculated according to Folk and Ward (1957) using the GRADISTAT software (Blott and Pye, 2001).

本数据集包含经去除生物成因碳酸钙（biogenic calcium carbonate）、生物成因蛋白石（biogenic opal）及有机质（organics）后的沉积物粒度分析（grain-size analyses）结果。粒度分析采用日本岛津（Shimadzu）SALD-2300激光衍射粒度分析仪（laser diffraction particle size analyzer）完成，该仪器可检测的粒径范围为17 nm至2.5 mm。本次分析分别针对全沉积物样品（bulk sediment samples）与去碳酸钙沉积物样品（calcium carbonate-free samples）开展。使用10%盐酸（hydrochloric acid）去除生物成因碳酸钙。针对放射虫含量相对其余岩芯更高的AI-3442岩芯，采用1M氢氧化钠溶液（sodium hydroxide，NaOH）去除生物成因蛋白石。使用过氧化氢（hydrogen peroxide，H₂O₂）去除有机质。向所有研究样品中加入0.7%六偏磷酸钠溶液（sodium hexametaphosphate solution，Na₆P₆O₁₈）并进行1分钟超声处理（ultrasonication），以实现颗粒分散（particle disaggregation）。依据Folk与Ward（1957）提出的方法，借助GRADISTAT软件（GRADISTAT software）计算平均粒径（mean grain size）与分选系数（sorting coefficient）。