Varve thickness record of Nautajärvi
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The sedimentary record of Nautajärvi, a lake in Finland, is 6.6 m long and covers uninterruptedly annual laminations (varves) sediments back to 9852 a BP. The isolation of Lake Nautajärvi from the Baltic Sea basin occurred at 9625 a BP, and since then the rate of sedimentation has remained relatively stable, averaging 0.6–0.7 mm yr-1. Varves consist of wo layers, a dark biogenic layer of particulate to fine-grained organic matter deposited in summer and a pale clastic layer of detrital origin linked to snowmelt and spring discharge intensity, which depend on the severity and snow storage during the winter. This dataset contains the varve (annual) thickness record and thickness of the seasonal layers published in Ojala and Alenius (2005). Data were collected in 1999-2003 and covers a time interval from present to 9852 a BP. Data are at seasonal to annual resolution. Detailed microfacies analysis, varve counting, and varve and laminae thickness measurements were performed on a scanning electron microscope back-scattered electron images (SEM BSEI), X-ray radiographs, and digital line-scan image analysis. Varves were analysed in between 200 marker horizons 5-6 times using different media, and deviations between counts were registered to represent the margin of error associated within the varve chronology.
芬兰瑙塔耶尔维湖（Nautajärvi）的沉积记录总长6.6米，连续保存了可追溯至9852 a BP的年纹层（varve）沉积物。瑙塔耶尔维湖与波罗的海盆地的分离发生于9625 a BP，自此之后沉积速率始终相对稳定，平均为0.6–0.7 mm yr⁻¹。年纹层由两层构成：夏季沉积的深色生物成因细粒有机质颗粒层，以及由融雪和春季径流强度决定的碎屑成因浅色层——其中径流强度取决于冬季降雪量与降雪严酷程度。本数据集包含刊载于Ojala与Alenius（2005）的年纹层厚度记录及季节层厚度数据。数据采集于1999年至2003年间，覆盖了自现今至9852 a BP的时间区间，分辨率为季节至年际尺度。研究通过扫描电子显微镜背散射电子图像（SEM BSEI）、X射线放射成像以及数字线扫描图像分析，开展了详细的微相分析、年纹层计数以及年纹层与纹层厚度测量工作。研究人员在200个标志层位之间采用不同介质对年纹层进行了5至6次分析，并将各次计数结果间的偏差作为年纹层年代学的误差范围。
