Variations of monsoonal rain and vegetation during the past millennium in Tiangui Mountain, North China reflected by stalagmite δ 18 O and δ 13 C records from Zhenzhu Cave
Variations of monsoonal rain and vegetation during the past millennium in Tiangui Mountain, North China reflected by stalagmite δ 18 O and δ 13 C records from Zhenzhu Cave
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DOI：
10.1016/j.quaint.2017.06.039
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发表时间：
2017-08
影响因子：
2.2
通讯作者：
Jianguo Yin;Hong-chun Li;Z. Rao;Chuan‐Chou Shen;H. Mii;Radha Krishna Pillutla;Hsun-Ming Hu;Y. Li;Xiahong Feng
中科院分区：
文献类型：
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作者：
Jianguo Yin;Hong-chun Li;Z. Rao;Chuan‐Chou Shen;H. Mii;Radha Krishna Pillutla;Hsun-Ming Hu;Y. Li;Xiahong Feng
用~(230)Th/U、~(14)C和~(210)Pb测年方法对采自北中国平原西北部天桂山珍珠洞的11厘米长石笋(ZZ12)进行了测定。只有AMS14C测年获得了成功，而230Th/U则没有，这是由于铀含量低和石笋年龄较小所致。石笋顶层含有“核弹碳”信号，底部木炭和碳酸盐样品的AMS14C测年结果相似。根据石笋中含有最小死碳影响(DCI)的一系列AMS14C测年数据，建立了石笋的年龄模型，表明该石笋的年龄为1970年。对石笋上部51 mm(自1180年以来)的470个样本进行了δ18O和δ13C的分析。石笋ZZ12的δ18O记录反映了北半球夏季风降水的变化，与当地和中北部的中国干湿指数相当。14-15世纪小冰期(LIA)和20世纪70年代以来出现了最干旱的时期，可能是由于东亚夏季风减弱所致。ZZ12的δ13C主要记录了天桂山的植被变化，揭示了两个主要的森林砍伐时期：1500-1600年和1830年-1940年，这两个时期是由当地人类活动引起的。对δ18O记录的谱分析表明，太平洋年代际涛动和大西洋年代际涛动在北半球多年代际季风降水的变化中可能都起着重要作用，负的太平洋年代际涛动、类拉尼诺和正的大西洋年代际涛动的降水较多。
An 11-cm long stalagmite (ZZ12) collected from Zhenzhu cave, Tiangui Mountain, northwest of the North China Plain (NCP) has been measured by230Th/U, AMS14C and210Pb dating methods. Only AMS14C dating yielded the chronology successfully, while230Th/U did not due to low uranium content and the young age of the stalagmite. The top layers in the stalagmite contain “nuclear bomb carbon” signal, and the AMS14C dates of charcoal and carbonate samples at the bottom are similar. Based on a series of AMS14C dates which contain minimal dead carbon influence (DCI) in the stalagmite, the age model of the stalagmite has been constructed, indicating that the stalagmite was 1970 years old. A total of 470 subsamples from the upper 51 mm (since 1180 CE) of the stalagmite have been analyzed for δ18O and δ13C. The δ18O record of stalagmite ZZ12 reflects changes in the summer monsoonal rainfall in the NCP, being comparable with the local and north-central China dry-wet index. The driest periods were found in 14th-15th centuries in the Little Ice Age (LIA) and since 1970s, perhaps due to weakening of East Asian summer monsoon. The δ13C of ZZ12 mainly recorded vegetation changes in Tiangui Mountain and revealed deforestation in two major periods: 1500–1600 CE and 1830–1940 CE caused by local human activities. Spectral analysis of the δ18O record suggests that the Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) may both play important roles in changes of multi-decadal monsoonal rainfall in the NCP, with more rainfall responding to the negative PDO, La Niño-like, and positive AMO phases.