侯鹤楠, 任云生, 杨群, 邹欣桐, 蒋国豪. 吉林延边六道崴子铁铜矿床成矿辉长闪长岩LA-ICP-MS锆石U-Pb年龄与地球化学特征[J]. 地质通报, 2014, 33(9): 1342-1352.
    引用本文: 侯鹤楠, 任云生, 杨群, 邹欣桐, 蒋国豪. 吉林延边六道崴子铁铜矿床成矿辉长闪长岩LA-ICP-MS锆石U-Pb年龄与地球化学特征[J]. 地质通报, 2014, 33(9): 1342-1352.
    HOU He-nan, REN Yun-sheng, YANG Qun, ZOU Xin-tong, JIANG Guo-hao. LA-ICP-MS zircon U-Pb dating and geochemistry of the metallogenic gabbrodiorite intrusion in the Liudaowaizi iron-copper deposit of eastern Yanbian, Northeast China[J]. Geological Bulletin of China, 2014, 33(9): 1342-1352.
    Citation: HOU He-nan, REN Yun-sheng, YANG Qun, ZOU Xin-tong, JIANG Guo-hao. LA-ICP-MS zircon U-Pb dating and geochemistry of the metallogenic gabbrodiorite intrusion in the Liudaowaizi iron-copper deposit of eastern Yanbian, Northeast China[J]. Geological Bulletin of China, 2014, 33(9): 1342-1352.

    吉林延边六道崴子铁铜矿床成矿辉长闪长岩LA-ICP-MS锆石U-Pb年龄与地球化学特征

    LA-ICP-MS zircon U-Pb dating and geochemistry of the metallogenic gabbrodiorite intrusion in the Liudaowaizi iron-copper deposit of eastern Yanbian, Northeast China

    • 摘要: 六道崴子铁铜矿位于兴蒙造山带东段的延边地区,主矿体赋存于燕山早期辉长闪长岩与二叠系大理岩接触带内,赋矿岩石主要为石榴子石矽卡岩,成因上属接触交代型矿床。为确定成岩成矿时代、物质源区和构造背景,对矿区北山成矿辉长闪长岩中的锆石进行了LA-ICP-MS U-Th-Pb同位素测定和岩石地球化学分析。结果表明,20个测点的U-Pb年龄值介于196Ma±2Ma~213Ma±1Ma之间,年龄加权平均值为204Ma±2.3Ma,指示成岩成矿作用发生于早侏罗世;岩石主量元素组成具有低硅、富碱、富钠、高铝的特征,属偏铝质富钠钙碱性系列;辉长闪长岩稀土元素总量较低,以轻稀土元素相对富集、轻重稀土分馏较明显、较弱的负Eu异常等为特征;大离子亲石元素富集,高场强元素亏损,低Sr高Yb,微量元素比值介于地壳和地幔平均值之间,表明六道崴子成矿岩体具有壳幔混源的特征。结合东北地区区域构造背景演化,初步认为六道崴子铁铜矿的成岩成矿作用发生在活动大陆边缘的岛弧环境,与古太平洋板块向吉黑东部的俯冲作用有关。

       

      Abstract: The Liudaowaizi iron-copper deposit is located in Yanbian area and belongs to the east part of the Xing'an-Mongolia Orogenic Belt. The major orebodies occur along the contact zone between the Early Yanshanian gabbrodiorite and the Permian marble. The ore-hosting rock in the ore deposit is dominated by the garnet skarn. Based on the ore-forming geological factors and mineralization characteristics, it can be concluded that the deposit belongs to the contact-metasomatic type. Using the LA-ICP-MS U-Th-Pb dating method of isotopes of zircon grains from gabbrodiorite in northern mining area and analysis of the geochemical characteristics of the intrusion, the authors obtained the U-Pb ages, which vary from 196Ma±2Ma to 213Ma±1Ma with an average value of 204Ma±2.3Ma. Both the gabbrodiorite and the associated iron-copper mineralization were formed at the beginning of the Jurassic period. Major elements in the gabbrodiorite are characterized by low SiO2 (55.56%~56.45%), high alkali (3.43%~3.66%), sodium (3.43%~3.66%) and aluminum (17.34%~18.33%), indicating that the metallogenic gabbrodiorite belongs to the metaluminous high-sodium calc-alkaline series. Meanwhile, the rocks are featured by low REE content ((77.43~88.76)×10-6), high LREE and LREE/HREE ratios, and low positive or negative Eu anomalies. Such geochemical features as relative enrichment of large ion lithophile elements, depletion of high field strength elements, low Sr, high Yb and ratios of trace elements between the crust and the mantle show that the gabbrodiorite was derived from the crust-mantle mixed source. In combination with the evolution of tectonic background of Northeast China, the authors hold that both the gabbrodiorite and the associated iron-copper mineralization in the Liudaowaizi deposit were formed in island-arc environment resulted from the subduction of the Paleo Pacific plate to the Eurasian plate at the beginning of the Jurassic period.

       

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