中文摘要：

沙漠与黄土的物源联系是黄土研究关注的问题之一。石英氧同位素可示踪物源，粒度被用以分析沉积环境，但在沙漠物源研究中将二者结合应用的报道尚不多。本文测定了塔克拉玛干沙漠沙丘沙和沙丘剖面中河湖相沉积物的粒度及不同粒级的石英氧同位素，结果显示：①沙丘沙以极细砂和细砂为主，粉砂和黏土含量很低；河湖相沉积物以粉砂和黏土为主，砂含量低于5％。②各粒级石英δ^18OSMOW值介于13．8％e～19．7‰，其中沙丘沙为13．8‰-19．7‰，河湖相沉积物为15．6‰～17．6‰；沙丘沙石英δ^18O值随粒级增大未呈现减小趋势，同一粒级石英的8”0值存在一定变异。③经比较，塔克拉玛干沙漠砂和粉砂粒级的石英δ^18O值均高于中国其他沙漠，且〈20μm的石英δ^18O值与黄土高原的马兰黄土、洛川黄土一古土壤序列〈20μm的石英δ^18O值并无显著性差异。

英文摘要：

Oxygen isotopic composition of quartz has been regarded as a good source tracer, and grain size analysis is widely applied to investigate sedimentary environment. However, there are few studies combining quartz δ^18O values with granulometry to explore provenance of aeolian sands in the Chinese deserts. In this paper, oxygen isotopic compositions of quartz in various size fractions and grain-size distribution were determined for fluvial-- lacustrine sediments and dune sands from the Taklimakan desert, western China. The results show that dune sands are generally composed of very fine sand and fine sand, whereas fluvial--lacustrine sediments are almost dominated by silt and clay. The 8180 values in different size fractions range from 13.8‰ to 19.7‰, in which dune sands vary from 13.8‰ to 19.7‰, fluvial--lacustrine sediments are between 15.6‰ and 17.6‰. Quartz from these samples has δ^18O values which lie within the range of values considered to be indicative of both metamorphic and sedimentary rocks. The quartzδ^18O values of dune sands have no notable decreasing trend with increase of grain size, and their values have obvious differences between the same size fractions in the Taklimakan desert, which is not consistent with former studies. In contrast to other deserts of China, the δ^18O values of silt-grained and sand- grained quartz are the greatest in the Taklimakan desert. There are no significantly different in the δ^18O values of fine-grained （ 〈 20μm） quartz between Taklimakan desert, Malan Loess, and Luochuan loess--palaeosol sequence in the Chinese Loess Plateau.