湘中包金山矿区花岗闪长斑岩的锆石U-Pb年龄、Hf-O同位素组成及其地质意义

发布时间：2018-05-25 15:11

本文选题：SIMS锆石U-Pb年龄 + Hf-O同位素示踪　；参考：《中国有色金属学报》2017年07期

【摘要】：包金山金矿床是近年在湘中地区探获的以金为主的多金属矿床,其成矿与印支晚期岩浆活动关系密切。利用高精度SIMS锆石U-Pb定年方法得到矿区两条花岗闪长斑岩年龄分别为(225.1±1.5)Ma和(223.3±1.4)Ma,在误差范围内一致,属印支晚期大规模岩浆活动的产物;矿区两条花岗闪长斑岩的~(176)Hf/~(177)Hf值均集中分布在0.2825附近,对应的ε_(Hf)(t)值介于-5.9~3之间,平均为-3.98,两阶段模式年龄T_(DM2)为0.96~1.45 Ga,平均为1.35 Ga;δ~(18)O值为0.824%~0.973%;Hf-O同位素研究表明花岗闪长斑岩主要为中元古代下地壳岩石重熔形成,且有部分幔源物质参与成岩作用;与紫云山花岗岩体对比分析,表明两者为同源岩浆演化的产物,且间接指示包金山金矿成矿时间为227~223 Ma;花岗闪长斑岩形成于多板块汇聚的动力学背景,为印支地块向北挤压和太平洋板块向西俯冲共同作用的结果。
[Abstract]:Baojinshan gold deposit is a polymetallic deposit mainly found in central Hunan in recent years. Its mineralization is closely related to the late Indosinian magmatism. Using SIMS zircon U-Pb dating method, two granodiorite porphyry ages of 225.1 卤1.5)Ma and 223.3 卤1.4 Ma. are obtained, which are consistent within the error range and belong to the products of large-scale magmatic activity in the late Indosinian period. The HF values of the two granodiorite porphyries in the mining area are concentrated in the vicinity of 0.2825, and the corresponding 蔚 ~ (-1) value is between -5.9 ~ (3). The average value is -3.98, the two-stage model age is 0.96 ~ 1.45Gaand the average value is 1.35Ga.The 未 ~ (18) O value is 0.8240.973H _ (f-O) isotopic study shows that the granodiorite is mainly formed by the remelting of the lower crust rocks of the Mesoproterozoic, and some mantle source materials are involved in diagenesis. Comparative analysis with Ziyunshan granite shows that they are the product of homologous magmatic evolution and indirectly indicate that the metallogenic time of Baojinshan gold deposit is 227223 Ma.The granodiorite was formed in the dynamic background of multi-plate convergence. This is the result of the northward compression of the Indosinian block and the westward subduction of the Pacific plate.
【作者单位】：中南大学地球科学与信息物理学院有色金属成矿预测教育部重点实验室;湖南省有色地质勘查局二总队;中国科学院地球化学研究所矿床地球化学国家重点实验室;
【基金】：国家自然科学基金资助项目(41473043,41272096)~~
【分类号】：P588.1;P597.3;P618.2

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