A WIGGLE-MATCHED 297-YR TREE-RING OXYGEN ISOTOPE RECORD FROM THAILAND: INVESTIGATING THE 14C OFFSET INDUCED BY AIR MASS TRANSPORT FROM THE INDIAN OCEAN
A WIGGLE-MATCHED 297-YR TREE-RING OXYGEN ISOTOPE RECORD FROM THAILAND: INVESTIGATING THE 14C OFFSET INDUCED BY AIR MASS TRANSPORT FROM THE INDIAN OCEAN
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DOI：
10.1017/rdc.2023.14
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发表时间：
2023-03
期刊：
影响因子：
8.3
通讯作者：
M. Sano;N. Pumijumnong;K. Fujita;M. Hakozaki;F. Miyake;T. Nakatsuka
中科院分区：
文献类型：
--
作者：
M. Sano;N. Pumijumnong;K. Fujita;M. Hakozaki;F. Miyake;T. Nakatsuka
摘要 北半球放射性碳 (14C) 校准曲线的区域偏移在亚洲季风中得到广泛认可，并且常常阻碍准确的 14C 测年。在本文中，我们利用泰国的树木年轮 δ18O 和 14C 数据探讨了夏季季风强度与 14C 偏移之间可能的联系。我们开发了 297 年漂浮树木年轮 δ18O 年表，其中包括来自泰国西北部 Ban Rai 岩石庇护所的七个柚木棺材样本。根据总共 10 个 14C 测量结果，我们年表的最外环估计为公元 358-383 年，概率范围为 95.4% (2σ)，这些测量结果与 IntCal20 和 SHCal20 曲线均匀加权的混合校准曲线进行摆动匹配。向后轨迹分析表明，现代树木年轮 δ18O 年表中检测到的夏季季风增强（减弱）最有可能是由热带印度洋的气团输送增加（减少）引起的，热带印度洋是一个强烈的上升流区域，其中 14C 浓度低于大气 14C 水平。然而，部分由于样本量有限和测年不确定性，树木年轮δ18O系列与从柚木木棺样本中获得的14C记录之间的直接联系无法得到统计验证。
ABSTRACT Regional offsets from Northern Hemisphere radiocarbon (14C) calibration curves are widely recognized for monsoon Asia and often hinder accurate 14C dating. In this paper, we explore the possible linkage between summer monsoon intensity and 14C offsets using tree-ring δ18O and 14C data from Thailand. We developed a 297-yr floating tree-ring δ18O chronology comprising seven teak log-coffin samples from the Ban Rai rock shelter site, northwestern Thailand. The outermost ring of our chronology was estimated to date from 358–383 CE, within a 95.4% (2σ) probability range, based on a total of 10 14C measurements that were wiggle-matched against a mixed calibration curve evenly weighted from the IntCal20 and SHCal20 curves. Backward trajectory analysis showed that an intensified (weakened) summer monsoon detected in a modern tree-ring δ18O chronology was most likely to be induced by increased (decreased) air mass transport from the tropical Indian Ocean, which is an area of intense upwelling where the 14C concentration is lower than the atmospheric 14C level. However, partly because of the limited sample size and dating uncertainty, the direct linkage between the tree-ring δ18O series and 14C records obtained from our teak log-coffin samples could not be statistically verified.