库布齐沙漠碎屑锆石U-Pb年龄组成及其物源分析

发布时间：2018-03-06 15:32

本文选题：库布齐沙漠　切入点：物源　出处：《西北大学》2017年硕士论文　论文类型：学位论文

【摘要】：库布齐沙漠的物源一直存在很大的争议,并存在周缘山脉侵蚀、就地起沙、黄河补给等诸多观点。碎屑锆石U-Pb年龄谱是物源示踪的有效手段。本研究在野外考察的基础上,通过对比沙漠不同地区地表沙与其潜在物源的碎屑锆石U-Pb年龄谱解析库布齐沙漠的物源。研究共分析了包括河套古湖滨湖相细沙、沙漠内部基岩、黄河及其本地二级支流河道沙、以及沙丘表面沙等在内的9个样品的900粒碎屑锆石。研究还采用光释光测年法确定了古湖样品的地层年代。结果显示,库布齐沙漠碎屑锆石U-Pb年龄主要谱峰为2.5Ga、1.9Ga、960Ma、450Ma和280Ma。碎屑锆石U-Pb年龄谱显示在沙漠内部物源具有明显的空间分带性,反映了自西向东黄河物源贡献的递减以及南部山脉和基底物质贡献的递增。河套湖盆可能对沙漠东部近源古老基岩物质和黄河携带的远源物质的汇集起到了重要作用。湖盆干枯后经风化剥蚀,间接为库布齐沙漠注入本地基岩物质和黄河远源物质。通过对本区潜在物源区的进一步对比发现,本区中西部物质很有可能是黄河从青藏高原东北缘搬运而来,而东部物质主要来自于古湖沙的翻新。
[Abstract]:The provenance of the Kubuqi desert has always been controversial, and there are many viewpoints such as the erosion of the surrounding mountains, the local sand collection, the recharge of the Yellow River, and so on. The U-Pb age spectrum of detrital zircon is an effective means to trace the provenance. The zircon U-Pb dating spectra of surface sediments and their potential provenances in different desert areas were compared to analyze the provenance of the Kubuqi Desert, including the fine sand of the ancient lacustrine lacustrine facies in Hetao, and the bedrock in the desert. 900 zircon fragments from 9 samples of the Yellow River and its local secondary tributaries, including sand on the sand dune surface, etc. The stratigraphic age of the ancient lake samples was also determined by means of the photoluminescence dating method. The results show that, The main spectrum peaks of zircon U-Pb in Kubuqi desert are 2.5Ga1.9Ga9Ga960MaA 450 Ma and 280Ma.The U-Pb age spectrum of detrital zircon shows obvious spatial zonation in the desert interior. It reflects the decreasing contribution of the source of the Yellow River from west to east, and the increasing contribution of the southern mountains and basement materials. The Hetao Lake basin may play an important role in the accumulation of the ancient bedrock material near the eastern desert and the distant material carried by the Yellow River. After drying up, the lake basin is weathered and denuded, Indirectly injected local bedrock material and distant Yellow River material into the Kubuqi desert. Through further comparison of the potential source areas in this area, it is found that the material in the central and western parts of the region is probably transported by the Yellow River from the northeastern margin of the Qinghai-Tibet Plateau. The material in the east comes mainly from the renovation of the ancient lake sand.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P597.3

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