LA-ICP-MS Zircon U-Pb Dating of Granodioritic Porphyry located Zhuxi Copper-Tungsten Mine in Northeast Jiangxi and Its Geological Significance
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摘要:
赣东北朱溪超大型铜钨矿位于江南古岛弧带塔前—赋春成矿带中段, 该矿床的发现可进一步验证“南钨北扩”观点并对“南钨北铜”格局提出挑战, 但前人对与朱溪铜钨矿成矿作用有关的花岗岩缺少精确的年代学研究, 导致对其地球动力学背景理解不够深入。本研究通过详细的野外调查、岩心编录和岩矿鉴定, 并利用激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)锆石U-Pb法对朱溪铜钨矿区侵入元古代双桥山岩群中的铜矿化花岗闪长斑岩进行测年, 获得了锆石206Pb/238U加权平均年龄为847.2±9.4 Ma(MSWD=0.111), 代表了其侵位结晶的年龄, 属新元古代。分析认为:朱溪铜钨矿区铜矿化花岗闪长斑岩是新元古代早期华南古洋壳俯冲消减及扬子陆块与华夏陆块发生碰撞作用下的岩浆产物, 这次岩浆活动与区域上塔前—赋春成矿带成矿作用关系密切, 并为钦—杭成矿带提供了成矿物质基础。本次对其成岩年龄的限定, 为研究朱溪超大型铜钨矿矿床提供了新证据。
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关键词:
- 朱溪铜钨矿 /
- 花岗闪长斑岩 /
- 铜矿化 /
- 激光剥蚀电感耦合等离子体质谱法 /
- 锆石U-Pb定年
Abstract:The Zhuxi ultra-large type copper-tungsten deposit in the Northeast Jiangxi province located in Taqian -Fuchun metallogenic belt which belongs to Jiangnan ancient island-arc, the discovery of the deposit has verified Southern Tungsten North Expansion perspective and challenge the viewpoint that Tungsten located in the south but the copper located in the north of Jiangxi provience, but the previous lack of accurate chronology study related to Zhuxi copper-tungsten mineralization of granite not enough, resulting in the geodynamic background of understanding. In this study, on the basis of detailed field investigation, core logging and petrology studies on the granodioritic porphyries which had intruded into the Middle Proterozoic Shuangqiaoshan group and with copper mineralization alteration, using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U-Pb dating, we obtained the granodioritic porphyries zircon 206Pb/238U weighted mean age of 847.2±9.4Ma (MSWD=0.111), which can represent the granodiorite porphyry magma emplacement and crystallization age, belonging to the neoproterozoic. The results reveal that the granodioritic porphyries of Zhuxi copper-tungsten mine is a product of the early Neoproterozoic Southern China ancient oceanic crust subduction and Yangtze and Cathaysian continental blocks collisional magmatism, the magmatic activity provides the basis for the metallogenic Qinzhou-Hangzhou metallogenic belt, and the magma event is close related to the Taqian-Fuchun ore belt mineralization, it also provides new evidence for the study of Zhuxi ultra-large type copper-tungsten deposit.
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表 1 朱溪铜钨矿区花岗闪长斑岩(ZX-1) LA-ICP-MS锆石U-Pb同位素测试结果
Table 1. LA-ICP-MS zircon U-Pb isotopic analysis of the granodiorite porphyry (ZX-1) of Zhuxi Cu-W deposit
测试编号 元素含量(×10-6)及比值 同位素比值 表面年龄(Ma) ZX-1 232Th 238U Th/U 207Pb/206Pb 1σ 207Pb/235U 1σ 206Pb/238U 1σ 208Pb/232Th 1σ 207Pb/206Pb 1σ 207Pb/235U 1σ 206Pb/238U 1σ 208Pb/232Th 1σ 1.1 284 344 0.83 0.12935 0.00041 5.63888 0.12147 0.31622 0.00693 0.06631 0.00435 2100 6 1922 19 1771 34 1298 82 2.1 297 244 1.22 0.10176 0.00061 4.07664 0.14633 0.29073 0.01064 0.04436 0.00273 1657 11 1650 29 1645 53 8778 53 3.1 136 100 1.36 0.07044 0.00043 1.36692 0.02637 0.14087 0.00269 0.02216 0.00128 943 13 875 11 850 15 443 25 4.1 101 130 0.77 0.06705 0.00031 1.29790 0.02610 0.14022 0.00271 0.02133 0.00117 839 9 845 12 846 15 427 23 5.1 112 244 0.46 0.06769 0.00028 1.29879 0.02754 0.13913 0.00291 0.02066 0.00107 859 14 845 12 840 16 413 21 6.1 131 213 0.62 0.14158 0.00046 7.52942 0.14366 0.38546 0.00718 0.06361 0.00309 2247 6 2176 17 2102 33 1247 59 7.1 58 73.4 0.79 0.17709 0.00082 11.71112 0.18405 0.48023 0.00758 0.07386 0.00379 2626 8 2582 15 2528 33 1440 71 8.1 373 590 0.63 0.06937 0.00064 1.35965 0.06080 0.14227 0.00639 0.02278 0.00124 909 14 872 26 857 36 455 25 9.1 171 132 1.30 0.07038 0.00067 1.37762 0.03907 0.14270 0.00410 0.02208 0.00120 939 19 879 17 860 23 441 24 10.1 216 159 1.36 0.06765 0.00033 1.32418 0.02979 0.14192 0.00312 0.02085 0.00120 857 15 856 13 856 18 417 24 11.1 169 174 0.97 0.11191 0.00037 5.06352 0.09896 0.32845 0.00649 0.04832 0.00256 1831 6 1830 17 1831 32 954 49 12.1 166 192 0.87 0.07157 0.00073 1.39301 0.03321 0.14154 0.00332 0.02427 0.00126 974 20 886 14.09 853 19 485 25 13.1 354 594 0.60 0.07355 0.00031 1.67332 0.02786 0.16570 0.00297 0.02793 0.00133 1029 9 998 11 988 16 557 26 14.1 176 324 0.55 0.07028 0.00052 1.36216 0.02696 0.14090 0.00279 0.02315 0.00115 937 16 873 12 850 16 463 23 15.1 128 313 0.41 0.06764 0.00082 1.28765 0.10353 0.13852 0.01137 0.02070 0.00114 857 26 840 46 836 64 414 23 16.1 563 721 0.78 0.06947 0.00025 1.44977 0.03768 0.15125 0.00384 0.02181 0.00108 922 7 910 16 908 22 436 21 17.1 100 136 0.74 0.06779 0.00030 1.30721 0.01766 0.13985 0.00182 0.02088 0.00111 861 9 849 8 844 10 418 22 18.1 133 189 0.71 0.06734 0.00027 1.29724 0.01770 0.13984 0.00191 0.01950 0.00109 850 9 845 8 844 11 390 22 19.1 226 237 0.95 0.06755 0.00050 1.30646 0.04041 0.14037 0.00433 0.01755 0.00107 854 16 849 18 847 24 352 21 20.1 144 339 0.42 0.06838 0.00024 1.19735 0.01624 0.12704 0.00171 0.01643 0.00108 880 7 799 8 771 10 329 22 -
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