敦煌雅丹沉积物中重矿物特征及其物源指示意义

Heavy mineral characteristics and its implication for provenance of Yardang sediments in Dunhuang

重矿物是判断物源的重要标志。文中对甘肃敦煌雅丹砂质沉积物中重矿物的种类、形态和组合特征进行了分析,进而对沉积物的物源进行了探讨。通过研究,共鉴定出21种重矿物,可分为2类组合:一是磁铁矿-角闪石-锆石-磷灰石组合、二是石榴子石-绿帘石-绿泥石-矽线石组合;根据重矿物类型和组合特征推测研究区沉积物的母岩应以岩浆岩及变质岩为主;重矿物指示研究区砂质沉积物属近源快速堆积的产物,物源应来自北山构造隆起区。

Heavy minerals are the important indicators of provenance. In this paper, the provenances of sandy sediments in Yardang area, Dunhuang city, Gansu province were discussed by analyzing the species, morphology and composition characteristics of heavy minerals. The results show that the 21 identified heavy minerals can be classified into 2 combinations as following: magnetite-hornblende-zircon-apatite, and garnet-epidote-chlorite-sillimanite. According to the types and assemblage characteristics of the heavy minerals, it is estimated that the dominant parent rock of the sediments in the study area should be magmatic rocks and metamorphic rocks. The heavy minerals indicate that the sediments in the study area are the products of near-source rapid accumulation, and the provenance should be from the Beishan tectonic uplift.