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引用本文:梁玉伟1 余存林2 沈国珍3 孙庆茹1 李进文4 杨郧城4 佘宏全4 张 斌4 谭 刚4. 内蒙古东乌旗索纳嘠铅锌银矿区花岗岩地球化学特征及其构造与成矿意义[J]. 中国地质, 2013, 40(3): 767-779.
LIANG Yu-wei1, YU Cun-lin2, SHEN Guo-zhen3, SUN Qing-ru1, LI Jin-wen4, YANG Yun-Cheng4, SHE Hong-quan4, ZHANG Bin4, TAN Gang4. Geochemical characteristics of granites in the Suonaga Pb-Zn-Ag deposit of Dong Ujimqin Banner, Inner Mongolia, and their tectonic and ore-forming implications[J]. Geology in China, 2013, 40(3): 767-779(in Chinese with English abstract).
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内蒙古东乌旗索纳嘠铅锌银矿区花岗岩地球化学特征及其构造与成矿意义
梁玉伟1 余存林2 沈国珍3 孙庆茹1 李进文4 杨郧城4 佘宏全4 张 斌4 谭 刚41,2,3,4
1. 内蒙古第一地质矿产勘查开发院,内蒙古 呼和浩特 010020;2. 内蒙古地质矿产勘查开发局,内蒙古 呼和浩特 010020;3. 内蒙古第九地质矿产勘查开发院,内蒙古 锡林浩特 026000;4. 中国地质科学院矿产资源研究所,北京 100037
摘要:
提要:内蒙古东乌旗索纳嘠铅锌银矿区赋矿侵入岩为一由中粗粒花岗岩、细粒黑云母花岗岩和似斑状钾长花岗岩组成的杂岩体。三种岩石的锆石U-Pb同位素年龄依次为(319.6±4.1)Ma、(172.5±1.4)Ma和(165.5±1.8)Ma。三者均以高钾、富碱、贫镁为特征,均属钙碱性、准铝质—弱过铝质岩石,分异程度较高。岩石稀土总量较高,轻稀土相对富集,均具负铕异常;均富集U、Th,Rb/Sr值大于壳源Rb/Sr值,应属S型花岗岩。根据花岗岩地球化学和区域地质特征分析认为,中粗粒花岗岩形成于晚石炭世后碰撞伸展构造环境;中侏罗世细粒黑云母花岗岩和似斑状钾长花岗岩产于板内伸展构造环境,为同源岩浆演化不同阶段的产物。似斑状钾长花岗岩富含成矿元素Pb和Zn,而且其成岩年龄与辉钼矿(163.4±2.4)Ma~(166.6±2.4)Ma的Re-Os同位素年龄基本一致,可能为成矿母岩。
关键词:  花岗岩  岩石年龄  地球化学  构造背景  金属成矿  内蒙古东乌旗
DOI:
分类号:
基金项目:中国地质调查局地质调查项目(1212011085260)、科技支撑计划(2006BAB01A10)和内蒙古地质矿产勘查开发局综合研究项目(ND2007004)联合资助。
Geochemical characteristics of granites in the Suonaga Pb-Zn-Ag deposit of Dong Ujimqin Banner, Inner Mongolia, and their tectonic and ore-forming implications
LIANG Yu-wei1, YU Cun-lin2, SHEN Guo-zhen3, SUN Qing-ru1, LI Jin-wen4, YANG Yun-Cheng4, SHE Hong-quan4, ZHANG Bin4, TAN Gang41,2,3,4
1. No. 1 Institute of Geology and Mineral Resources Development, Hohhot 010020, Inner Mongolia, China;2. Bureau of Geology and Mineral Resources Development of Inner Mongolia, Hohhot 010020, Inner Mongolia, China;3. No. 9 Institute of Geology and Mineral Resources Development, Xilin Hot 026000, Inner Mongolia, China;4. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
Abstract:
Abstract:The ore-bearing pluton in the Suonaga Pb-Zn-Ag deposit is composed of medium-coarse-grained granite, fine-grained biotite granite and pseudoporphyritic K-feldspar granite. The zircon U-Pb dating results show that the medium-coarse-grained granite was formed at 319.6±4.1 Ma, the fine-grained biotite granite was formed at 172.5±1.4 Ma, and the pseudoporphyritic K-feldspar granite was formed at 165.5±1.8 Ma. The petrogeochemistry of the three rock bodies is characterized by high K, rich alkali and poor magnesium, so they all belong to calcium-basic, quasi-aluminous to weakly peraluminous and highly-differentiated rocks. All of the granites have high REE and negative Eu anomalies, exhibiting relative enrichment of LREE. These rock bodies belong to S-type granites, because they are enriched in U and Th and their Rb/Sr ratios are higher than those of the crustal source. Regional geology and granite geochemistry indicate that the medium-coarse-grained granite was formed in a post-collisional extensional environment in Late Carboniferous; the Middle Jurassic fine-grained biotite granite and pseudoporphyritic K-feldspar granite were formed in an intraplate extensional environment, and they were products of different evolutionary stages of a comagmatic region. The pseudoporphyritic K-feldspar granite was probably the ore-forming parent rock, because its diagenetic age is consistent with the molybdenite Re-Os ages (163.4±2.4Ma to 166.6±2.4Ma) and the rocks are enriched in metallogenic elements Pb and Zn.
Key words:  granite  age of the rock  geochemistry  tectonic setting  mineralization  Dong Ujimqin Banner in Inner Mongolia