Unravelling the genetic relationship between pegmatites and granites in the Jiajika Li-Be polymetallic district, Songpan-Ganze Orogenic Belt, Southwestern China: Insights from monazite U-Pb geochronology and trace element geochemistry

作者：Mingzhao Zhou, Rongqing Zhang, John M. Hanchar, Zhiqin Xu, Jianjun Lu, Huan Hu, Xudong Che, Bihai Zheng, Guangwei Li · 发表于：Ore Geology Reviews · 年份：2023 · DOI：10.1016/j.oregeorev.2023.105774 · 被引用次数：10 · 研究领域：Geological and Geochemical Analysis、earthquake and tectonic studies、Geochemistry and Geologic Mapping

The Jiajika Li-Be Polymetallic District is located in the Songpan-Ganze Orogenic Belt, Southwestern China. The Li-Be mineralization is genetically, temporally, and spatially, related to pegmatites in the Jiajika District. Hundreds of pegmatite dikes were emplaced surrounding the adjacent Majingzi granite pluton. Drill core samples from the 3,200 m deep scientific drilling project (JSD-1) were acquired to determine the vertical extent and the petrogenesis and metallogeny of the granites, and the pegmatites, respectively, and to obtain a better understanding of their genetic relationship. The vertical zonation of the pegmatites from shallow to deep is as follows: shallow albite pegmatites; albite-microcline pegmatites; microcline pegmatites; and deeper more albite pegmatites. Spodumene occurs mainly in the shallow albite pegmatites (55–105 m), and disseminated beryl, columbite-tantalite, and cassiterite, mainly occur in pegmatites at depths less than 700 m. Eight samples were selected for monazite U-Pb geochronology and trace element geochemistry from pegmatites and granites at different depths. LA-ICPMS monazite U-Pb geochronology for the pegmatites indicate two episodes of magmatic activity; one at 210–205 Ma (2σ, 523–2,568 m depth) and another at 193–192 Ma (2σ, 3,170–3,211 m depth). The crystallization age of the older pegmatites is in good agreement with the monazite U-Pb geochronology of the adjacent Majingzi granite (209–205 Ma) within analytical uncertainty, indicating ...