A persistent Holocene wetting trend in arid central Asia, with wettest conditions in the late Holocene, revealed by multi-proxy analyses of loess-paleosol sequences in Xinjiang, China
A persistent Holocene wetting trend in arid central Asia, with wettest conditions in the late Holocene, revealed by multi-proxy analyses of loess-paleosol sequences in Xinjiang, China
复制标题
通过对中国新疆黄土-古土壤序列的多代理分析揭示了干旱中亚地区持续的全新世湿润趋势，在全新世晚期具有最潮湿的条件
DOI：
10.1016/j.quascirev.2016.06.002
复制
发表时间：
2016-08-15
影响因子：
4
通讯作者：
An, Chengbang
中科院分区：
文献类型：
--
作者：
Chen, Fahu;Jia, Jia;An, Chengbang
全新世期间干旱中亚（ACA）的湿度（降水）历史解读存在显著差异，一方面是从洞穴石笋氧同位素记录推断得出，另一方面是从湖泊沉积物推断得出。在此，我们展示了对来自中国新疆天山北坡和伊犁河谷（位于ACA核心区域）的四个年代确定良好的黄土 - 古土壤序列的气候敏感磁性特征和土壤颜色的测量结果。我们的研究结果表明，代表相对湿润条件的全新世特征古土壤一般在研究区域约6 ka（1 ka = 1000 cal yr BP）之后形成，并且未风化黄土的堆积在全新世早期占主导地位，这表明当时气候干燥。磁性指标进一步揭示出自末次盛冰期以来湿度总体呈上升趋势，最湿润的气候出现在全新世晚期。全新世期间这种湿度增加的趋势代表了新疆地区，可能也代表了整个ACA核心区域，并且与东亚夏季风区域观测到的全新世中期湿度最大以及自全新世早期以来印度夏季风强度普遍下降形成鲜明对比。我们的研究结果得到了气候模拟结果的支持，该模拟结果表明全新世期间ACA核心区域夏季和冬季降水呈增加趋势，这主要是由纬度日照梯度增加所影响的西风强度增加以及北极涛动（AO）或北大西洋涛动（NAO）的负趋势所导致的。（C）2016爱思唯尔有限公司。保留所有权利。
There are significant differences in the interpretation of the moisture (precipitation) history of arid central Asia (ACA) during the Holocene, as inferred on one hand from speleothem oxygen isotope records, and on the other from lake sediments. Here we present the results of measurements of climatically-sensitive magnetic properties and soil color from four well-dated loess-paleosol sequences from the northern slopes of the Tienshan Mountains and the Yili River valley, Xinjiang, China, in the core area of ACA. Our results demonstrate that the characteristic Holocene paleosol, indicating relatively moist conditions, generally formed after similar to 6 ka (1 ka = 1000 cal yr BP) in the study region, and that the accumulation of unweathered loess prevailed during the early Holocene, indicating a dry climate at that time. The magnetic proxies further reveal a trend of generally increasing moisture since the Last Glacial Maximum, with the wettest climate occurring during the late Holocene. This trend of increasing moisture during the Holocene is representative of the Xinjiang region and possibly of the whole of the core area of ACA, and is in marked contrast both to the mid-Holocene moisture maximum observed in the East Asian summer monsoon region and to the general decrease in the strength of the Indian summer monsoon since the early Holocene. Our findings are supported by the results of a climate simulation which indicate a trend of increasing summer and winter precipitation during the Holocene in the core area of ACA, caused mainly by an increase in the strength of the westerlies effected by an increasing latitudinal insolation gradient and by a negative trend of the Arctic Oscillation (AO) or North Atlantic Oscillation (NAO). (C) 2016 Elsevier Ltd. All rights reserved.