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<p>The Late Triassic to Early Jurassic (ca. 220 to 190&#xa0;Ma) Dahongliutan pegmatite belt, located in the Western Kunlun orogenic belt, NW China, is a newly discovered, large Li-Be ore district comprising &gt; 320 individual rare-metal pegmatites. The pegmatite belt was emplaced in a post-orogenic setting in relation with a ductile shear zone related to the Dahongliutan detachment fault, which is spatially and temporally related to post-orogenic exhumation. Deformed spodumene pegmatites, mostly striking NW with dip angle of 50 ~ 80°, occur within or adjacent to the NW-striking detachment fault. We present new field observations, mineralogical, geochemical and geochronological results from the Dahongliutan pegmatite belt, which lead to the following conclusions: 1) High-medium temperature/middle-to-low pressure metamorphic rocks and granitoids were intruded by ductile-deformed spodumene-bearing pegmatites during development of the gneissic domes; 2) Spodumene pegmatites from the Aktas, Kalaka, Bailongshan and Longmenshan deposits record two age groups, a first one during the Upper Triassic at ca. 212–205&#xa0;Ma, and a second one during the Lower Jurassic at ca. 195–193&#xa0;Ma, as revealed by in-situ Rb–Sr dating of micas and U–Pb dating of columbite-group minerals; 3) Textural observations&#xa0;and geochemical analyses of coexisting quartz and spodumene further indicate that ductile deformation provided favorable conditions for enrichment of Li and Be in pegmatites. The Western Kunlun-Songpan Ganzi rare-metal pegmatite belt shows a close spatial and genetic relationship with ductile shear zones induced by detachment faulting, making it a potential proxy for exploration targeting of Li-Be-mineralized occurrences at the regional scale as well as in other metallogenic provinces worldwide.</p>

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Syn-tectonic emplacement of Li-bearing pegmatites related to detachment faulting in the Dahongliutan pegmatite belt, Western Kunlun, NW China

  • 期刊论文

  • 发表日期：

    2025年3月3日

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  • Tao Hong,
  • Matthieu Harlaux,
  • Ming-Guo Zhai,
  • Yue-Jun Wang,
  • Xing-Wang Xu,
  • Xiao-Ping Xia,
  • Jun Gao,
  • Jun-Lin Tang,
  • Ming-Xi Hu,
  • Huan-Xiang Gao

摘要

The Late Triassic to Early Jurassic (ca. 220 to 190 Ma) Dahongliutan pegmatite belt, located in the Western Kunlun orogenic belt, NW China, is a newly discovered, large Li-Be ore district comprising > 320 individual rare-metal pegmatites. The pegmatite belt was emplaced in a post-orogenic setting in relation with a ductile shear zone related to the Dahongliutan detachment fault, which is spatially and temporally related to post-orogenic exhumation. Deformed spodumene pegmatites, mostly striking NW with dip angle of 50 ~ 80°, occur within or adjacent to the NW-striking detachment fault. We present new field observations, mineralogical, geochemical and geochronological results from the Dahongliutan pegmatite belt, which lead to the following conclusions: 1) High-medium temperature/middle-to-low pressure metamorphic rocks and granitoids were intruded by ductile-deformed spodumene-bearing pegmatites during development of the gneissic domes; 2) Spodumene pegmatites from the Aktas, Kalaka, Bailongshan and Longmenshan deposits record two age groups, a first one during the Upper Triassic at ca. 212–205 Ma, and a second one during the Lower Jurassic at ca. 195–193 Ma, as revealed by in-situ Rb–Sr dating of micas and U–Pb dating of columbite-group minerals; 3) Textural observations and geochemical analyses of coexisting quartz and spodumene further indicate that ductile deformation provided favorable conditions for enrichment of Li and Be in pegmatites. The Western Kunlun-Songpan Ganzi rare-metal pegmatite belt shows a close spatial and genetic relationship with ductile shear zones induced by detachment faulting, making it a potential proxy for exploration targeting of Li-Be-mineralized occurrences at the regional scale as well as in other metallogenic provinces worldwide.