A study on accurate age determination of volcanic eruptions by high-precision 140 dating and a wiggle matching analysison charred wood from volcanic deposits

2001年从白头山火山采集了6个木材样本，经过仔细检查，发现两个烧焦的木材树干有树皮。其中较大的一个，有102个年轮，用于^&lt；14&gt；C测年。年轮被分成82个样本。由于年轮较窄，外围的20个年轮每两年划分一次。从21^&lt；st&>；到92^&lt；n&>；每个年轮都是分开的。年轮大于92°的年轮断裂，不能分离。我们分析了82个样品中的35个：大约每三个年轮一次。木炭样品经过AAA处理，并在常规方法中转化为石墨。名古屋大学的暖通电子加速器测量了14&gt；C、13&lt；C和12&gt；C。用摆动匹配法将得到的数据与INTCAL98^&lt；14&gt；C校准数据进行比较。我们得到了一个清晰的峰的概率分布，该峰对应于最外面的两个环的混合物最可能在公元935年生长的时间，误差为8年和5年。这一结果表明，白头山火山的喷发与公元926年渤海国的沦陷无关。U-Oki Tephra通常被认为是在日本沉积的，大约在9.3-9.6kaBP之间。在鱼梁岛上发现了U1、U2、U3和U4层，其层位高于AT层(2.5kaBP)。在2002年和2003年对鱼梁岛的调查中，从U2(烧焦的木材)、U3(有机土壤)和U4(烧焦的树枝和有机土壤)收集了用于^&lt；14和gt；C测年的碳样品。测得U2、U3和U4的年龄分别为5kaBP、7.5-8.0kaBP和10-12kaBP。这些结果表明，日本的U-Oki tephra对应于U4。这是一项非常新的发现，因为U-Oki Tephra被认为与U2相对应。

Six wood samples were collected from Baitoushan Volcano in 2001 and two charred wood trunks were detected to have barks by careful inspection. The larger one of the two, with 102 annual rings, was used for ^<14>C dating. The annual rings were divided into 82 samples. The outer 20 annual rings were divided every two years because of narrow annual rings. From 21^<st> to 92^<nd> each annual ring was separated. Annual rings inner than 92^<nd> ring were broken and could not be separated. We have analyzed 35 samples out of 82 : approximately every three annual rings. The charcoal samples were processed by AAA treatments and converted to graphite in a routine method. The ^<14>C, ^<13>C and ^<12>C were measured with a HVEE Tandetron at Nagoya University. The obtained dates were compared with the INTCAL98 ^<14>C calibration data by wiggle matching. We obtained a probability distribution of one clear peak that corresponded to the time when the mixture of the outermost two rings was grown most probably in 935 cal AD, with errors of +8 and -5 years. This results implies that the eruption of Baitoushan Volcano had no relation with the fall of the Bo-hai State in AD926.ext, tephras from the Ulleung Island were studies chronologically. The U-Oki tephra is commonly accepted to have deposited in Japan at around 9.3-9.6 kaBP. The tephra layers U1, U2, U3 and U4 have been recognized on the Ulleung Island and their horizons were upper than the AT tephra (2.5 kaBP). During the survey at the Ulleung Island in 2002 and 2003, carbon samples for ^<14>C dating were collected from U2 (charred wood), U3 (organic soil) and U4 (charred twigs and organic soil). ^<14>C ages obtained for these layers were 5 kaBP for U2, 7.5-8.0 kaBP for U3 and 10-12 kaBP for U4. These results imply that the U-Oki tephra in Japan corresponds to U4. This is a really new finding, because the U-Oki tephra has been believed to correspond to U2.