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引用本文:尹继元1 陈 文1 喻 顺1 龙晓平2 袁 超2 张 彦1 李 洁1 孙敬博1 刘新宇1. 西准噶尔包古图富镁闪长质岩墙的时代、地球化学特征以及铜金成矿意义[J]. 中国地质, 2013, 40(4): 1030-1043.
YIN Ji-yuan1, CHEN Wen1, YU Shun1, LONG Xiao-ping2, YUAN Chao2, ZHANG Yan1, LI jie1, SUN Jing-bo1, LIU Xin-yu1. Age, geochemical features and Cu-Au mineralization significance of the magnesian dioritic dykes in Baogutu area of west Junggar[J]. Geology in China, 2013, 40(4): 1030-1043(in Chinese with English abstract).
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西准噶尔包古图富镁闪长质岩墙的时代、地球化学特征以及铜金成矿意义
尹继元1 陈 文1 喻 顺1 龙晓平2 袁 超2 张 彦1 李 洁1 孙敬博1 刘新宇11,2
1.中国地质科学院地质研究所, 同位素热年代学实验室,大陆构造与动力学国家重点实验室,北京 100037;2.中国科学院广州地球化学研究所,同位素地球化学国家重点实验室, 广东 广州 510640
摘要:
提要:西准噶尔包古图地区广泛发育富镁闪长质岩墙。对这些岩墙进行角闪石Ar-Ar和锆石U-Pb定年分别获得(313.1±3.5)Ma和(316.3±3.8) Ma的年龄,显示其主要形成于晚石炭世。闪长质岩墙以富Si(SiO2=56.8 %~62.9 %)、Mg(MgO=2.39 %~4.04 %、Mg#=54-62)、Cr(Cr=30×10-6~80×10-6)、Ni(Ni=20×10-6~62×10-6)为特征,具有弱的Eu负异常和高Sr/Y比值(36~44),强烈亏损HREE(Yb=1.32×10-6~1.54×10-6、Y=13.1×10-6~15.5×10-6),富集LILE(K、Sr、Ba),亏损HFSE(Nb、Ta、Ti)。这些特点显示,这些闪长质岩墙可能是由俯冲的板片熔体与地幔橄榄岩反应而成,与洋脊俯冲有关。而闪长质岩墙的形成过程也有利于铜金矿床的形成,显示该区有良好的成矿远景。
关键词:  包古图  富镁闪长岩  岩墙  锆石U-Pb  角闪石Ar-Ar  铜金矿化  LA-ICP-MS
DOI:
分类号:
基金项目:国家自然科学基金(41203026,41273012),中国地质科学院地质研究所基本科研业务费项目(J1209),公益性行业专项经费(201211074-05)和中国地质调查局地质矿产调查评价专项(12120113015600)联合资助。
Age, geochemical features and Cu-Au mineralization significance of the magnesian dioritic dykes in Baogutu area of west Junggar
YIN Ji-yuan1, CHEN Wen1, YU Shun1, LONG Xiao-ping2, YUAN Chao2, ZHANG Yan1, LI jie1, SUN Jing-bo1, LIU Xin-yu11,2
1. Laboratory of Isotope Thermochronology, State Key Laboratory of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;2. State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, Guangdong, China
Abstract:
Abstract:The magnesian dioritic dykes widely distributed in west Junggar of Xinjiang recorded the Late Paleozoic tectonic evolutionary history of the area. The LA-ICP-MS zircon U-Pb and amphibole Ar-Ar dating of dioritic dykes yielded a 206Pb/238U age of 316.3±3.8 Ma and a plateau age of 313.1±3.5 Ma, respectively, suggesting that they were generated in Late Carboniferous. The magnesian dioritic dikes (56.8%-62.9%) are characterized by high MgO (2.39%-4.04%; Mg#= 54-62), Cr (30×10-6-80 ×10-6), and Ni (20×10-6-62×10-6) content. These samples show negligible to negative Eu values, high Sr/Y (36-44) ratios, strong depletion of HREE (e.g., Yb = 1.32×10-6-1.54×10-6 and Y=13.1×10-6-15.5×10-6), and enrichment of large-ion-lithophile elements (LILE) (K, Sr, Ba) with negative Nb-Ta-Ti anomalies. These features are compatible with slab-derived adakites interacted with mantle materials and related to ridge subduction. The interaction between high oxygen fugacity slab melt and mantle peridotite caused the decomposition of metal sulfides and the Cu and Au mineralization. Baogutu area of west Junggar thus has good metallogenic prospect.
Key words:  Baogutu  magnesian diorite  dyke  zircon U-Pb  amphibole Ar-Ar  copper-gold mineralization, LA-ICP-MS