Planktonic foraminifera assemblages and sea surface temperature reconstruction of IODP Site 383-U1539

This dataset comprises planktonic foraminifera assemblages and sea surface temperature (SST) reconstructions generated using the Modern Analogue Technique (MAT). The record spans 0.5 to 1.3 Ma, covering intervals before, during, and after the Middle Pleistocene Transition (MPT). It includes the sample code, depth in meters CSF-A (core depth below seafloor, method A), interpolated age in million years (Ma), sea surface temperature (°C) with associated weighted standard deviation, as well as the relative abundances (%) of planktonic foraminifera species. Sediment was recovered by drilling during IODP Expedition 383 at Site U1539, located in the South Pacific sector of the Southern Ocean. Samples were washed through a 63 µm mesh size sieve and subsequently dried at approximately 50°C for 24 hours. Once dried, samples were sieved through a 250 µm mesh. Species-level identification was performed using a stereomicroscope. These assemblage data were used to reconstruct SSTs with the MAT, implemented in C2 Software (version 1.8.0), using the Squared Chord Distance dissimilarity coefficient and leave-one-out cross-validation. The resulting SST estimates were applied as a proxy to investigate the latitudinal migration of oceanic fronts-particularly the Polar Front-during the MPT, to assess the mechanisms driving these shifts and their impact on the central South Pacific. The use of foraminiferal assemblages as a proxy for palaeoceanographic changes follows Kucera (2007; https://doi.org/10.1016/S1572-5480(07)01011-1).

本数据集包含浮游有孔虫（planktonic foraminifera）群落与基于现代类比法（Modern Analogue Technique, MAT）重建的海表温度（sea surface temperature, SST）结果。该记录的时间跨度为0.5至1.3百万年（Ma），覆盖中更新世过渡期（Middle Pleistocene Transition, MPT）前后及过渡期内的地层区间。数据集包含如下信息：样品编号、以米为单位的CSF-A深度（即海底以下岩心深度，方法A）、以百万年（Ma）为单位的插值年龄、附带加权标准差的海表温度（摄氏度）数据，以及各浮游有孔虫物种的相对丰度（百分比）。

沉积物由国际大洋发现计划（International Ocean Discovery Program, IODP）383航次在南太平洋扇区的南大洋U1539站位钻探获取。样品处理流程如下：首先经63微米孔径筛网冲洗，随后在约50℃条件下烘干24小时；烘干后再通过250微米孔径筛网过筛。研究人员借助体视显微镜完成物种水平的分类鉴定。

本研究利用该群落数据，通过搭载于C2软件（版本1.8.0）的现代类比法，以平方弦距离相异系数（Squared Chord Distance dissimilarity coefficient）和留一法交叉验证（leave-one-out cross-validation）开展海表温度重建。所得海表温度估算值作为古环境代用指标，用于探究中更新世过渡期内大洋锋面（尤其是极锋（Polar Front））的纬度迁移过程，以评估驱动此类迁移的机制及其对南太平洋中部海域的影响。本数据集采用有孔虫群落作为古海洋变化的代用指标，参考了Kucera（2007）的研究成果（https://doi.org/10.1016/S1572-5480(07)01011-1）。