Sedimentary strata in the Gangdese magmatic arc document a long but poorly constrained series of events leading to basin formation and evolution. In order to address one of these events, we sampled Mesozoic sedimentary rocks from the Linbuzong Formation within the Gangdese magmatic arc for detrital zircon U-Pb-Hf isotopic analysis, with the aim of delineating evolution of the back-arc basin and the uplift history and paleo-topographical growth of the Gangdese region in southern Tibet. This data provides new information on the sedimentary history and paleo-geographic reconstruction of the Gangdese region. The analyzed results reveal that the detrital zircons from the Linbuzong Formation contain four major age populations, 140-300 Ma, 480-700 Ma, 1000-1250 Ma and 1400-1700 Ma. The youngest detrital zircon cluster yields mean age at ca. 149 Ma which, in conjunction with previously published data,indicates that the youngest depositional age of the Linbuzong Formation is ca. 149 Ma and probably ceased at ca. 121 Ma. The youngest detrital zircon cluster is characterized by low 176Hf/177Hf isotopic ratios and negative εHf（t） values. This is similar to those of igneous zircons from the central Lhasa subterrane, suggesting that the central Lhasa sub-terrane is the predominant sediment source. However, few zircons from the youngest age cluster have high 176Hf/177Hf isotopic ratios. Their significantly positive εHf（t） values suggest them to be sourced from the southern Lhasa sub-terrane（Gangdese magmatic arc）. Combined with two conspicuous age populations（480-700 Ma and 1000-1250 Ma） and the Hf isotopic features, we propose that the Carboniferous-Permian metasedimentary rocks from the central Lhasa sub-terrane serve as the predominant sediment source. Taken together, we suggest that the central Lhasa subterrane was exhumed to the surface and had a high relief, whereas the Gangdese magmatic arc had a relatively low relief near sea-level during the Late Jurassic to early the Early Cretaceous. In addition, combined with published data, we present new geodynamic models to depict the evolution of the back-arc basin and southernmost Lhasa terrane（see below Fig. 1）.
类型: 国际会议
作者: MENG Yuanku,XU Zhiqin,Mooney WALTER,MA Yuan
来源: 第九届世界华人地质科学研讨会 2019-06-01
年度: 2019
分类: 基础科学
专业: 地质学,地质学,地质学
单位: College of Earth Science and Engineering, Shandong University of Science and TechnologySchool of Earth Sciences and Engineering, Nanjing UniversityU.S.Geological SurveyChina University of Geosciences(Beijing)
分类号: P597.3;P542
DOI: 10.26914/c.cnkihy.2019.028400
页码: 215-216
总页数: 2
文件大小: 225k
下载量: 1
本文来源: https://www.lunwen66.cn/article/43c8d4961695dcb5a29b9fa1.html