司晓博, 冯艳芳, 苏尚国, 张波. 华东南地区花岗岩型铌-钽矿床区域成矿地质背景[J]. 地质通报, 2020, 39(7): 1085-1103.
    引用本文: 司晓博, 冯艳芳, 苏尚国, 张波. 华东南地区花岗岩型铌-钽矿床区域成矿地质背景[J]. 地质通报, 2020, 39(7): 1085-1103.
    SI Xiaobo, FENG Yanfang, SU Shangguo, ZHANG Bo. Regional metallogenic geological background of granite-type Nb-Ta deposits in Southeast China[J]. Geological Bulletin of China, 2020, 39(7): 1085-1103.
    Citation: SI Xiaobo, FENG Yanfang, SU Shangguo, ZHANG Bo. Regional metallogenic geological background of granite-type Nb-Ta deposits in Southeast China[J]. Geological Bulletin of China, 2020, 39(7): 1085-1103.

    华东南地区花岗岩型铌-钽矿床区域成矿地质背景

    Regional metallogenic geological background of granite-type Nb-Ta deposits in Southeast China

    • 摘要: 为探究华东南地区花岗岩型铌-钽矿床区域成矿地质背景,给华东南地区花岗岩型铌-钽矿区域成矿规律总结和资源潜力评价提供地质构造依据,收集整理15个典型花岗岩型铌-钽矿床的资料,结合其矿床特征、成矿时代、成矿岩体及岩石地球化学研究,认为矿床形成时代集中于124~185 Ma,属燕山期。地球化学特征显示,P2O5含量在不同成矿花岗岩中富集程度不同,既有高P,也有低P,A/CNK=0.97~1.99(绝大部分大于1.1),具有过铝质特征;微量元素富集Rb和Nb、Ta、Th、Zr、Hf等,亏损Sr、Ti、Ba,稀土元素含量总体呈现出较低的趋势,具有明显的负Eu异常;Zr/Hf=3.13~23.31,Nb/Ta=0.28~7.67,结合其矿物特征,认为含矿岩体均为高分异花岗岩。成矿岩体底部到顶部,除部分隐伏岩体显示出顶上带的特征外,其余成矿岩体都显示出明显的相带特征,且特征矿物云母的变化较明显,向浅色云母及富锂方向演化;成矿岩体为黑云母花岗岩、二云母花岗岩和白云母花岗岩的共生或过渡组合,成矿花岗岩既有S型高分异的花岗岩,也有黄玉A型花岗岩,黄玉A型花岗岩与S型花岗岩共生且由S型花岗岩熔融作用形成。结合区域研究资料,认为矿床形成于洋-陆汇聚背景下的俯冲增生造山过程,即古太平洋板块向西俯冲,诱导扬子陆块东南缘发生陆内俯冲,导致东南沿海侵入(岩)弧的西北缘推覆至扬子陆块东南缘上方,形成众多碰撞型花岗岩型铌-钽矿床。

       

      Abstract: In order to explore the regional metallogenic geological background of granite-type Nb-Ta deposits in southeast China and to provide geological tectonic basis for the regional mineralization regularity and resource potential evaluation of granite-type Nb-Ta deposits in southeast China, the authors collected and collated data from 15 typical granite type Nb-Ta deposits and, in combination with the deposit characteristics, metallogenic age, metallogenic rock mass and rock geochemical research analysis, concluded that the formation ages of the deposits are concentrated at 124 ~ 185 Ma, suggesting Yanshanian period.Geochemical characteristics show that the concentration of P2O5 is different in different ore-forming granites, with both high P and low P, A/CNK equal to 0.97~1.99, mostly greater than 1.1, and peraluminous characteristics; trace elements show enrichment of Rb and Nb, Ta, Th, Zr, Hf and other elements but loss of Sr, Ti, Ba; the content of rare earth elements generally shows a low trend, and Eu has a significantly negative anomaly; Zr/Hf=3.13~23.31, and Nb/Ta=0.28~7.67.In combination with the mineral characteristics, it is believed that the ore-bearing rock masses are all highly differentiated granites.From the bottom to the top of the ore-forming rock mass, except for some hidden rock masses that show the characteristics of the top zone, the ore-forming rock masses all show obvious facies belt characteristics, and the characteristic mineral mica changes more obviously, towards light-colored mica and evolution in lithium-richer direction; the ore-forming rocks are the associated or transitional combination of biotite granite, two-mica granite and muscovite granite.The mineralizing granite includes both S-type highly differentiated granite and topaz A-type granite, and topaz A-type granite.Granite and S-type granite are symbiotic and were formed by melting of the S-type granite.Combined with regional research data, the authors hold that the deposits were formed in the subduction accretive orogenic process under the background of ocean-continent convergence:westward subduction of the Paleo-Pacific plate led to the occurrence of intracontinental subduction on the southeast margin of the Yangtze Block, which resulted in the northwest margin of the intrusive (rock) arc of the southeast coast pushing over the southeast margin of the Yangtze Block, forming many "collision type" granite Nb-Ta deposits.

       

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