班—怒成矿带西段江玛南铜银矿区石英闪长玢岩锆石U-Pb年龄、Hf同位素及地球化学特征 |
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关键词:quartz diorite porphyry LA-ICP-MS zircon U-Pb dating zircon Hf isotope whole-rock geochemistry Bangong Co–Nujiang metallogenic belt |
基金项目:中国地质科学院基本科研业务费专项(编号: JYYWF20182402);国家重点研发计划“深地资源勘查开采”重点专项(编号: 2018YFC0604106);国家自然基金项目(编号: 41873046);中国地质调查局地质调查项目(编号: DD20160026) |
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摘要: |
Zircon U-Pb Age, Hf Isotope and Geochemistry of Quartz Diorite Porphyry of the Jiangmanan Copper-silver Ore District in the Western Part of the Bangong Co–Nujiang Metallogenic Belt |
The Jiangma–Saideng ore district with a large potential of copper polymetallic resources was discovered recently in the Bangong Co–Nujiang metallogenic belt. Zircon U-Pb geochronology, whole-rock geochemistry and Zircon Hf isotope composition of the quartz diorite porphyry in Jiangmanan were studied in this paper. LA-ICP-MS zircon 206Pb/238U dating result indicates that the quartz diorite porphyry was emplaced at (118.6±2.8) Ma (N=13, MSWD = 3.6). Whole-rock major and trace element data show that the quartz diorite porphyry belongs to medium-K calc-alkaline and metaluminous I-type felsic rocks. The quartz diorite porphyry is obviously enriched in LREE and displays weak or no Eu anomalies (REE/HREE = 9.37~9.76, LaN/YbN = 12.33~12.98, δEu = 0.94~0.97). The rock is also enriched in large-ion lithophile elements (LILE such as Rb, Th, U, and K) and relatively depleted in high field strength elements (HFSE such as Ta, Nb, Ti and Zr), having geochemical features of arc-type magmas. The positive εHf(t) values of zircons are +7.9 ~ +11.2, and the second stage Hf mode ages TDMC are 456~675 Ma, which indicates its mantle source. Based on geochronology, geochemistry, zircon Hf isotope and regional study, the authors hold that the quartz diorite porphyry resulted from southward subduction of Bangong Co–Nujiang Tethys Ocean. |
GAO Teng,WANG Li-qiang,WANG Yong,ZHENG Si-lun,HU Yu.2019.Zircon U-Pb Age, Hf Isotope and Geochemistry of Quartz Diorite Porphyry of the Jiangmanan Copper-silver Ore District in the Western Part of the Bangong Co–Nujiang Metallogenic Belt[J].Acta Geoscientica Sinica,40(6):884-894. |
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