晚新生代塔里木盆地西部沙漠形成与演化的粒度记录  

Late Cenozoic desert formation and evolution in the western Tarim Basin inferred from grain size records

作　　者：马志伟[1] 孙东怀[1] 易治宇[2] 朱彦虎[3] 王鑫[1] 李再军[1] 梁百庆[1] 李宝锋[1] 王飞[1] 

机构地区：[1]兰州大学资源环境学院,兰州730000 [2]中国地质科学院地质研究所,北京100037 [3]中国地质大学(武汉)信息工程学院,武汉430074

出　　处：《兰州大学学报（自然科学版）》2017年第2期152-162,共11页Journal of Lanzhou University(Natural Sciences)

基　　金：国家自然科学基金面上项目(41272045);国家创新群体计划项目(40121091);国家重点基础研究发展计划(973计划)项目(2010CB833401;2012CB956102);高等学校博士学科点专项科研基金项目(20120211110015)

摘　　要：塔里木盆地腹地的麻扎塔格剖面出露了连续的晚新生代地层,深入研究其沉积环境对认识塔里木盆地西部沙漠的形成演化有重要意义.对剖面全部样品进行粒度测试,应用粒度分布函数拟合方法进行粒度组分分离,依据组分的粒径/含量-频率变化,结合岩性判断,系统分析了沉积序列粒度组分的成因.粒度组分分析结果显示:风成沉积中超细粒、细粒粉尘、粗粒粉尘、风成砂组分粒径范围分别为<1.9、1.9~8.6、8.6~33.3、33.3~270.0μm.湖相沉积常呈双峰分布,湖相悬移粒径为2.4~8.6μm,含量>60%,叠加超细粒组分;河流沉积中河流砂粒径>270.0μm.剖面620 m处大套风成砂沉积出现,对应3.4 Ma风成组分含量显著增大,指示了塔克拉玛干沙漠的出现,420 m后风成砂沉积占据主导,对应2.8 Ma之后风成砂组分含量及粒径显著增大,指示沙漠环境进一步扩张.3.6 Ma以来河流组分含量阶段性增大,指示了多期河流发育,可能与青藏高原隆升有关.Continued late Cenozoic sedimentary strata were exposed at the Mazatagh section in central Tarim Basin. An in-depth study of its sediment environment would be of great significance for under- standing the desert formation and evolution in the western Tarim Basin. For this purpose grain size mea- surement was carried out for all samples, grain-size component analysis was conducted of the component partition, and the origin of each component was systematically analyzed on the basis of the size/propor- tion-frequency data, combined with field lithology. The results of component analysis suggested that, for the aeolian sediments, the modal-size of ultralfine component, fine suspension dust, coarse suspension dust and aeolian sand component had a range of〈1.9, 1.9-8.6, 8.6-33.3, 33.3-270.0 μm, respectively. La- custrine sediments generally had a bimodal distribution, lacustrine suspension a modal size range of 2.4- 8.6 μm, and the proportion was 〉60%, being overlapped by an ultralfine component. The modal size of fluvial sand component in the fluvial sediment was over 270.0 μm. Large-scale aeolian sand appeared at 620 m in the section, corresponding to a significantly increased aeolian component proportion at 3.4 Ma, indicating the onset of the Taklimakan Desert; aeolian sand dominanted the sediment after 420 m, corre- sponding to a significantly increasing proportion and grain-size of aeolian sand component at 2.8 Ma and indicating further expansion of the desert environment. The proportion of fluvial component periodically increased after 3.6 Ma, indicating the occurrence of several periods of fluvial development, probably re- lated to the uplift of the Tibetan Plateau.

关 键 词：粒度 古环境 晚新生代 塔克拉玛干沙漠 

分 类 号：P512.2[天文地球—地质学]