瓦窑沟剖面记录的早中全新世毛乌素沙地东南缘气候变化

毛乌素沙地位于中国东亚季风边缘区，对气候变化响应敏感。区域内分布着大量河湖相沉积地层，忠实记录了全新世以来气候变化状况。选取毛乌素沙地东南缘河湖相沉积地层为主的瓦窑沟剖面（WYG），在光释光（OSL）和¹⁴C（AMS ¹⁴C）测年基础上，对粒度、色度和有机质环境代用指标进行分析，反演得出毛乌素沙地早中全新世气候经历了3个阶段：约9.8 ka BP前气候干冷，广泛沉积沙层；9.8—9.6 ka BP气候逐渐回暖，为气候干冷转为暖湿的过渡期；9.6—5.2 ka BP气候相对暖湿，发育砂质泥炭层。推测计算得出，剖面地层沉积速率沙层>过渡层>砂质泥炭层，且各地层均存在次一级旋回，曲线旋回周期砂质泥炭层（480 a）>沙层（150 a）>过渡层（130 a），指示砂质泥炭层沉积速率最慢、形成时期气候相对稳定。研究结果与东亚季风区域古气候记录具有很好的可比性，是对东亚冬夏季风强度变化的全球性响应。

Early and Middle Holocene climate change inferred by Wayaogou Section in the Southeastern Mu Us Desert

Mu Us Desert is located in the edge of East Asian monsoon in China， which is sensitive to climate changes. There are a large number of fluvial and lacustrine sedimentary strata in the area， which faithfully records the climate change since the Holocene. We analyzed the section of fluvio-lacustrine sediments （WYG） in the southeastern edge of Mu Us Desert， based on OSL and AMS ¹⁴C dating， in combination with environmental proxy indicators including grain size， chromaticity and organic matter. The results showed that the climate of Mu Us Desert experienced three stages in the early and middle Holocene： Before 9.8 ka BP， the climate was cold-dry， with extensive deposition of sand； 9.8-9.6 ka BP， the climate warmed up gradually， which was the transition period from cold-dry to warm-wet； 9.6-5.2 ka BP， the climate was warm-wet relatively， and peat developed. It is calculated that the order of sedimentary rate of the section is sandy > transition layer > sandy peat layer. And there are secondary cycles in each layer， The cycle length of each layer is sandy peat layer （480 a/time）> sand layer （150 a/time） and > transition layer （130 a/time） from large to small， indicating that the sedimentary rate of sandy peat layer is the slowest and the climate is relatively stable during the formation period. The results of this study are in good contrast with the paleoclimatic records of other deserts in the East Asian monsoon region， which is a global response to the changes in the intensity of the East Asian winter and summer monsoon.