Photos, XRF elements, total N and C, and isotopic data (d18O, d13C) from Deep Sea Drilling Project Site 225 cores, central Red Sea

Photographs, 18O/16O isotopic ratios, XRF-derived elemental and N, C concentration data are provided for sediment cores from Deep Sea Drilling Project Site 225, central Red Sea. This site was originally drilled in April 1972 by rotatary drilling to recover cores through parts of the Plio-Pleistocene sediments for studies of past Red Sea water properties and regional climate. The rotary drilling disturbed the sediments by varied amounts, though left some 1.5-m sections of core almost intact. The X-ray fluorescence (XRF) data comprise elemental proportions for the core archive sections selected where they showed the least drilling disturbance. These and the core photographs were obtained at Kochi University, Japan, using an ITRAX core scanner during 2023 and 2024. Given the age of the cores, the archive sections are not perfectly flat, hence the ITRAX-derived elemental data may be distorted by varied distance between the sensor and the core, as well as by cracks within the core. The user needs to judge these data against the core photographs. As the lighter 16O isotope is evaporated preferentially over 18O and tends to get locked up in ice sheets during glacial periods, measurements of the ratio 18O/16O in carbonate sediments are often useful for recording evidence of global climatic cycles. In the Red Sea, the ratio is further affected by local evaporation, as the basin has been variably isolated from the Indian Ocean, partly as a result of sea-level variations affecting the exchange of water between the basins. Samples of ~20 cm3 were selected with two sets of intervals. Coarse-interval sampling was chosen spanning the Plio-Pleistocene for reconnaissance, while denser sampling was carried out across particular intervals of scientific interest. Within these intervals, the shells of foraminifera were separated into different species. Shells of Cibicidoides mundulus were primarily selected for measurements of 18O/16O. Analyses were carried out in 2024 at the University of Southampton (UK) using a Kiel carbonate device coupled to a Mat253 IRMS. XRF core scanning and sampling were carried out by technical staff of the Marine Core Research Institute, Kochi University under supervision of the IODP Core Curator Yusuke Kubo. Diederik Liebrand disaggregated the samples, separated the foraminifera shells and carried out the oxygen isotopic measurements. Selected samples were also analysed for nitrogen and carbon contents (weight percent of bulk sample in columns B and C) at the University of Liverpool by Steve Crowley.

本数据集提供了来自深海钻探项目225号站位中央红海沉积岩心的照片、18O/16O同位素比值，以及由X射线荧光(XRF)技术获得的元素和氮、碳浓度数据。该站位于1972年4月通过旋转钻探技术原钻，旨在从晚更新世沉积层中提取岩心，以研究过去红海的水文特性和区域气候。旋转钻探对沉积层造成了不同程度的扰动，但仍保留了部分1.5米长的岩心基本完整。XRF数据涵盖了核心档案部分的元素比例，这些部分在XRF分析中显示出最小的钻探扰动。这些数据和核心照片均于2023年至2024年在日本高知大学使用ITRAX岩心扫描仪获取。鉴于岩心的年代，档案部分并非完全平坦，因此ITRAX获得的元素数据可能因传感器与岩心之间的距离变化以及岩心中的裂缝而扭曲。用户需将这些数据与核心照片进行对比。由于较轻的16O同位素在冰期期间相对于18O同位素更易蒸发，并倾向于在冰层中锁定，因此碳酸盐沉积物中18O/16O比值的测量通常有助于记录全球气候周期的证据。在红海，这一比值还受到局部蒸发的影响，因为该盆地与印度洋的隔离程度不一，部分原因是海平面变化影响了两个盆地之间的水交换。选用了约20立方厘米的样品，并分为两套间隔。粗间隔采样被选中，以对晚更新世进行初步调查，而在特定的科学兴趣区间内则进行了更密集的采样。在这些区间内，有孔虫的壳被分为不同的物种。Cibicidoides mundulus的壳主要被选中用于18O/16O的测量。分析于2024年在英国南安普顿大学进行，使用了与Mat253红外多光谱质谱仪相连的基尔碳酸盐设备。XRF核心扫描和采样由高知大学海洋岩心研究所的技术人员在IODP核心馆长菊保祐的监督下完成。Diederik Liebrand对样品进行了分解，分离了有孔虫壳，并进行了氧同位素测量。选定的样品还由利物浦大学的Steve Crowley分析了氮和碳含量（总样品重量百分比，列B和C）。