Radiometric dating, geochemical proxies, and predator biological remains obtained from aquatic sediment cores on South Georgia Island.

This data set contains radiometric dating measurements from two aquatic sediment cores excavated from two separate sites (Salisbury Plain and Gold Harbor) on South Georgia Island in February 2019. It also contains biological and geochemical sediment proxy values from both sediment cores, including total carbon (%), total nitrogen (%), number of penguin feathers and eggshell fragments, number of seal hairs, and δ13C and δ15N stable isotope values. Cores were sectioned at 1cm intervals, and radiometric dating analyses were conducted on sediment fractions <850 µm by measuring for 210Pb and 226Ra (via 214Pb) by direct gamma counting using the high purity germanium planar detector in the Marine Geochemistry Laboratory at Louisiana State University (LSU). The 210Pbex profiles were used to calculate sedimentation rates using a steady state model that assumes constant rate of supply and constant sedimentation rate (Maiti et al., 2010). Geochemical analyses were performed on sediment fractions <125 µm using an Elemental Analyzer-Isotope Ratio Mass Spectrometry (EA-IRMS) in the Stable Isotope Ecology Lab at LSU. Biological counts of feathers and hairs were determined by enumeration using a dissecting microscope of sediment fractions >1000 µm. The data set also includes sediment core excavation site names and coordinates, date of excavation, sediment depth and age, and carbon to nitrogen isotopic ratios. Details of the data set and all relevant methods are provided in Kristan et al., 2021.本数据集收录了2019年2月于南乔治亚岛两处独立采样遗址——索尔兹伯里平原（Salisbury Plain）与戈德港（Gold Harbor）——钻取的两处水生沉积岩芯的放射性测年测量数据。同时包含两处沉积岩芯的生物学与地球化学沉积代用指标数据，具体包括总碳（Total Carbon，%）、总氮（Total Nitrogen，%）、企鹅羽毛及蛋壳碎片数量、海豹毛发数量，以及δ13C与δ15N稳定同位素比值数据。 岩芯以1厘米为间隔进行切片分样；针对粒径小于850 µm的沉积物组分开展放射性测年分析：采用路易斯安那州立大学（Louisiana State University, LSU）海洋地球化学实验室的高纯锗平面探测器（high purity germanium planar detector），通过直接γ计数（direct gamma counting）法测定210Pb与226Ra（通过214Pb间接测定）。基于过剩210Pb（210Pbex）剖面，采用恒定供给速率与恒定沉积速率的稳态模型（steady state model，Maiti等，2010）计算沉积速率。 地球化学分析针对粒径小于125 µm的沉积物组分开展，使用路易斯安那州立大学稳定同位素生态实验室的元素分析仪-同位素比率质谱仪（Elemental Analyzer-Isotope Ratio Mass Spectrometry, EA-IRMS）完成检测。羽毛与毛发的生物学计数通过对粒径大于1000 µm的沉积物组分使用体视显微镜（dissecting microscope）进行枚举统计得到。 本数据集还包含沉积岩芯采样遗址名称与坐标、采样日期、沉积物深度与年代，以及碳氮同位素比值数据。数据集的详细信息与所有相关实验方法可参见Kristan等，2021。