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

树轮年代学是以科学为基础的考古学中最精确的年代测定方法。它允许将单个年轮的生长分配给单个日历年，并且在木材样本保留树皮边缘的情况下，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木结构和文物的年代。在树木生长在强烈的环境胁迫下，通常是在高海拔或高纬度，也可以提取关于过去气候的信息。但是，树的年代学和树的气候学受到正在测定的树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，很大一部分样品，特别是那些来自气候很少限制生长的欧洲西北部地区的样品，无法确定年代或用于重建历史气候。为了测定年代和重建古环境，Quercus项目将使用稳定的同位素而不是环宽度，将建立第一个欧洲西北部的每年可分辨的同位素年表，时间从大约4500年一直延伸到青铜时代。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，允许对自科学树状年代学发展以来一直无法确定日期的档案和文物进行短序列、属间和多种方法的测年。稳定的同位素年代学携带强烈的气候信号，即使树木在环境胁迫下不生长，也可以用来重建过去的气候。使用多学科方法，这些记录使用世界上一些最长的仪器系列进行校准，将为气候变化数千年来影响社会的文化丰富、人口稠密的地区提供无与伦比的夏季气候量化重建。

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.