毛乌素沙地晚第四纪地层特征与沙漠化研究综述

Review of Late Quaternary Strata Characteristics and Desertification on Mu Su Dune Field in North China

毛乌素沙地保存着晚第四纪以来的多种沉积序列,记录了过去数十万年以来的古气候变化信息。其在地层发育上过渡性明显,以神木、榆林、横山、靖边及定边一线的沙漠-黄土边界带最为典型,主要有风成沉积和河湖相沉积2种类型,其中古风成砂是这2类沉积剖面的典型地层特征。随着地层记录、精确测年技术等现代沉积学方法的进步以及与历史地理、环境考古、遥感技术相结合的综合研究,晚第四纪以来毛乌素沙地的沙漠演变研究精度不断提高,毛乌素沙地进退在不同的时空尺度下与冷暖期的多旋回变化相适应,经历了沙丘固定与活化的多次转变。毛乌素沙地沙漠化研究在指标运用上多直接沿用黄土区的环境代用指标,有必要建立适合沙漠-黄土过渡地区的环境代用指标,且将气候环境物理替代性指标与元素地球化学以及生物学指标相结合。毛乌素沙地内部沉积速率快、受人类活动干扰较小的湖泊沉积物,对于提高沉积物的分辨率、恢复短时间尺度的环境变化过程也具有显著优势。

A variety of sedimentary sequences Mu Su dune field have been developed since Late Quaternary, and recorded the paleoclimate changes in the past thousands of years. The development of sedimentary strata in Mu Su dune field has prominent features of transition between desert and loess in North China. The most typical strta are situated in the desert-loess transition zone along Shenmu, Yulin, Hengshan, Jingbian and Dingbian, mainly including two types of aeolian depositions and fluvio-lacustrine deposits, in which the palaeo-eolian sand shows typical strata characteristics. With the progerss in stratigraphic record and accurate dating technology, and the comprehensive research combined with historical geography, environmental archaeology and remote sensing, the research precision on Mu Su desert evolution continues to improve. The advance and retreat of Mu Su dune field experienced several changes of the fix and activation of sand dunes, which were appropriate to the multi-cycle changes of cold-warm periods in in different temporal and spatial scales. The previous researches on Mu Us desertification in the use of indicators often adopted directly the environmental proxies suited for the loess area, so it is necessary to establish a suitable environmental proxy indicators for the desert-loess transition zone, which should be combined with the climatic-environmental physical, element geochemistry and biological indicators. The lake sediments with fast deposition rate and less human disturbance in Mu Su dune field have significant advantages for enhancing the resolution of sediments and restoring short-time scale environmental change process.