Tree ring oxygen isotope dating of wood recovered from a canal in the ancient capital of Japan
Tree ring oxygen isotope dating of wood recovered from a canal in the ancient capital of Japan
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DOI：
10.1016/j.jasrep.2022.103626
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发表时间：
2022-10
期刊：
影响因子：
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通讯作者：
M. Sano;Zhen Li;Yumiko Murakami;M. Jinno;Yoko Ura;A. Kaneda;T. Nakatsuka
中科院分区：
文献类型：
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作者：
M. Sano;Zhen Li;Yumiko Murakami;M. Jinno;Yoko Ura;A. Kaneda;T. Nakatsuka
生长在日本低地的树木不受气候影响，因此，不同树木之间的年轮宽度模式相关性很弱。因此，在日本的年轮宽度的基础上，树木年代学研究在很大程度上依赖于气候压力的针叶树生长在山区和/或高纬度地区。相比之下，氧同位素比值（δ 18 O）在树木之间匹配良好，无论气候压力如何，这表明在日本挖掘的大量木材可能会被测年。在这里，我们使用出土的树桩测试了氧同位素测年（Abiessp.，栎属，和Zelkova serrata），历史文献和考古学证据表明其日期为708至715 CE。一个新的2470年的主年表的基础上，日本柏树样本（主要Chamaanoparis obtusa）的开发，我们的定年方法进行了评估，使用现代样品收集的几个物种（铁杉，云杉，红豆杉，松，栎）在日本和韩国。然后，我们的年表被用来确定从运河岸边发现的树桩的年代，这条运河是在奈良成为日本新首都时建造的。尽管这些样本只有30-60个年轮，并且包括阔叶树在内的多个物种，但它们的树木年轮δ 18 O模式成功地进行了交叉匹配。由此产生的网站年表是强大的日期对主年表，表明树桩的砍伐日期范围从冬季697/8到709/10 CE。总的来说，这些日期与以前的发现是一致的，但我们的研究提供了与新首都建设有关的确切日历日期，并表明氧同位素树木年代学在日本很有效。
Trees growing in the lowlands of Japan are not climatically stressed; consequently, ring-width patterns are weakly correlated between different trees. Therefore, dendrochronological studies in Japan based on ring widths rely largely on climatically stressed conifers growing in mountainous regions and/or at higher latitudes. In contrast, oxygen isotope ratios (δ18O) are well-matched between trees, irrespective of climatic stress, indicating that the huge amounts of wood excavated in Japan could potentially be dated. Here, we tested oxygen isotope dating using unearthed stumps (Abiessp.,Quercussp., andZelkova serrata) from Japan, which historical documents and archaeological evidence suggest date from 708 to 715 CE. A new 2470-year master chronology based on Japanese cypress samples (mainlyChamaecyparis obtusa) was developed, and our dating method was evaluated using modern samples collected from several species (Tsuga,Picea,Taxus,Pinus, andQuercus) across Japan and Korea. Our chronology was then used to date stumps recovered from the bank of a canal, which was constructed when Nara became the new capital city of Japan (Heijō-kyō in Japanese). Even though the samples had only 30–60 rings and comprised multiple species, including broad-leaf trees, their tree ring δ18O patterns were successfully cross-matched. The resulting site chronology was robustly dated against the master chronology, indicating that the felling dates of the stumps ranged from winter 697/8 to 709/10 CE. Overall, the dates are consistent with previous findings, but our study provides exact calendar dating related to the construction of the new capital, and demonstrates that oxygen isotope dendrochronology works well in Japan.