晚更新世以来塔克拉玛干沙漠中部地区的环境演变  

Palaeoenvironmental changes in the central part of the Taklamakan Desert, northwestern China since the late Pleistocene

作　　者：杨小平 杜金花 梁鹏[1] 张德国 陈波[1] Patrick Rioual 张峰[4] 李鸿威 王旭龙[5] Xiaoping Yang;Jinhua Du;Peng Liang;Deguo Zhang;Bo Chen;Patrick Rioual;Feng Zhang;Hongwei Li;Xulong Wang(Key Laboratory of Geoscience Big Data and Deep Resource of Zhejiang Province,School of Earth Sciences,Zhejiang University,Hangzhou 310027,China;School of Earth Science and Resources,Chang an University,Xi'an 710064,China;Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;College of Resource and Environment Science,Xinjiang University,Urumqi 830046,China;State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,Chinese Academy of Sciences,Xi'an 710061,China)

机构地区：[1]浙江大学地球科学学院,浙江省地学大数据与地球深部资源重点实验室,杭州310027 [2]长安大学地球科学与资源学院,西安710064 [3]中国科学院地质与地球物理研究所,中国科学院新生代地质与环境重点实验室,北京100029 [4]新疆大学资源与环境科学学院,乌鲁木齐830046 [5]中国科学院地球环境研究所,黄土与第四纪地质国家重点实验室,西安710061

出　　处：《科学通报》2021年第24期3205-3218,共14页Chinese Science Bulletin

基　　金：科技部科技基础资源调查专项(2017FY101001);国家自然科学基金(41672182,41430532)资助。

摘　　要：选取塔克拉玛干沙漠中西部南-北大断面为考察路线,综合运用第四纪地质学、地貌学等学科的研究方法,对9个河流-湖泊(及静水)-风沙沉积地层的古环境特征进行了解析和探讨.目前这些剖面都处于风沙环境,但保存的古河流沉积和湖泊(静水)沉积暗示这些区域都曾是河流所到之处或较长时间被水体淹没.通过光释光测年方法对河流和湖泊的起始时间进行了界定;选取颜色、粒度和磁化率等代用指标明确古环境意义.古环境代用指标值与野外沉积相的判断结果基本一致,河流和风沙沉积的粒度较湖相沉积为粗,磁化率总体较低,湖相沉积的碳酸钙含量较高.研究区河流和湖相沉积的持续时间说明,塔克拉玛干沙漠自晚更新世以来至少经历过3个相对比较湿润的时段,即约70~50 ka、末次冰期冰消期(约17~11 ka)和全新世晚期(约5~2 ka).对比分析表明,塔克拉玛干沙漠的古环境演变过程和机制与中国北方地区其他沙漠、沙地存在显著区别.The Taklamakan Desert, with an area of 337600 km2 and located in the Tarim Basin of southern Xinjiang, is the largest sand sea in the mid-latitudes on Earth. Previous understanding about palaeoclimate of this vast arid landscape was mostly deciphered from loess sequences found in the surrounding mountains, while only a few in situ investigations in the sand sea were carried out. In light of the advances in the optically stimulated luminescence(OSL) dating techniques during the last decades, reconstructing palaeoenvironmental changes via studying aeolian sands in the interior of sand seas can now be achieved by careful observations in the field and by application of improved protocols of OSL dating methods. We used the new multiple-aliquot regenerative-dose(MAR) protocol with carefully selected preheat conditions of 230°C for 10 s to date all samples which are distinctly younger than the upper age limit of this dating procedure, confirming that our chronology is scientifically robust.This paper reveals facies changes and the OSL chronologies of nine sedimentary sections showing interactions between fluvial, lacustrine(including slack-water) and aeolian processes in the central part of the Taklamakan. At present all sites of these sections are undergoing aeolian processes. The occurrences of fluvial and lacustrine(including slack-water)sediments in these sections indicate that many parts of the sand sea were shaped by rivers and inundated by water for long durations in the past. The initiations of occurrence of rivers and lakes(including slack-water) show some cyclicity according to the OSL ages.Our palaeoenvironmental interpretations of the different sedimentary facies in the field are supported by the data of palaeoclimatic proxies including color, grain sizes and magnetic susceptibility. The nine sections collectively suggest that three moist periods occurred in the Taklamakan Sand Sea since the late Pleistocene, i.e., ~70–50 ka(1 ka = 1000 years before 2010 CE), the late glacial of the last glaciation(~17-11

关 键 词：沙漠 地貌学 第四纪 环境演变 光释光测年 

分 类 号：P931.3[天文地球—自然地理学]