Dating the "Undateable" - Quantitative Environmental Reconstruction and Precision Chronology Using Tree-ring Stable Isotopes

在以科学为基础的考古学中，树木年轮测年是最精确的测年方法。它允许单个树木年轮的生长被指定为一个日历年，并且木材样本保留树皮边缘，可以确定树木死亡或被砍伐的季节和年份。这种方法可以提供绝对的日历日期，并彻底改变了整个欧洲的木结构和人工制品的年代。在树木在强烈的环境压力下生长的地方，通常是在高海拔或纬度，也可以提取过去气候的信息。然而，树木年代学和树木气候学受到测定年轮序列的长度和变异性以及树种、年龄和种源的限制。这意味着很大一部分样本，特别是那些来自诸如欧洲西北部等气候很少限制生长的地区的样本，无法确定年代或用于历史气候重建。QUERCUS项目将使用稳定同位素而不是环宽来进行年代测定和古环境重建，从而开发出欧洲西北部从距今4500年至青铜器时代的第一个年度同位素年表。QUERCUS将推进最需要年代学和古气候数据的物种和地区的技术，允许对自科学树木年代学发展以来一直无法确定年代的档案和人工制品进行短序列，属间和多方法的年代测定。稳定同位素年表携带着强烈的气候信号，即使树木在环境压力下没有生长，也可以用来重建过去的气候。这些记录采用多学科方法，使用世界上最长的仪器系列进行校准，将为文化丰富、人口稠密的地区提供无与伦比的夏季气候量化重建，这些地区的气候变化已经对社会产生了数千年的影响。

Dendrochronology, or tree-ring dating, is the most precise dating method in science-based archaeology. It allows the growth of an individual tree ring to be assigned to a single calendar year and, where wood samples retain the bark-edge, it is possible to determine the season and the year in which the tree died, or was felled. The method can provide absolute calendar dates and has revolutionised the dating of wooden structures and artefacts across Europe. Where the trees grew under strong environmental stress, typically at high altitude or latitude, it is also possible to extract information on the climate of the past.However, dendrochronology and dendroclimatology are constrained by the length and variability of the tree-ring sequence being dated, as well as by the tree species, age and provenance. This means that a large proportion of samples, particularly those from regions such as NW Europe where climate rarely limits growth, cannot be dated or used for historical climate reconstruction.Using stable isotopes rather than ring widths, for both dating and palaeoenvironmental reconstruction, the QUERCUS project will develop the first annually-resolved isotopic chronologies for NW Europe extending c. 4,500 years to the Bronze Age. QUERCUS will advance the technique for species and regions where chronology and palaeoclimate data are most needed, to permit short sequence, inter-genus and multi-method dating of archives and artefacts that have remained undateable since the development of scientific dendrochronology.The stable isotope chronologies carry strong climate signals, and can be used to reconstruct the climate of the past even when the trees were not growing under environmental stress. Using a multi-disciplinary approach, these records, calibrated using some of the longest instrumental series in the world, will deliver unrivalled quantified reconstructions of summer climate for culturally-rich, populous regions where climatic change has impacted upon society over millennia.