大湖塘矿集区一矿带燕山晚期成矿后花岗斑岩年代学、地球化学特征及对成矿结束时间的约束  

Geochronology,Geochemical Characteristics of the Post-mineralization Late Yanshanian Granite Porphyry and its Constraints for the Terminal of the Metallogeny in the No.1 Ore Belt of the Dahutang District

作　　者：陈茂松 项新葵[2] 占岗乐[3] 尹青青[4] 余振东[2] 王天晨 徐裕敏[2] 谭荣[2] CHEN Mao-song;XIANG Xin-kui;ZHAN Gang-le;YIN Qing-qing;YU Zhen-dong;WANG Tian-chen;XU Yu-min;TAN Rong(Land and Resources Trade Center,Department of Natural Resources of Jiangxi Province,Nanchang 330025,China;No.916 Geological Party,Jiangxi Bureau of Geology&Mineral Exploration,Jiujiang 332100,China;Northwestern Geological Brigade of Jiangxi Geology&Mineral Resources Development Bureau,Jiujiang 332100,China;Sinosteel Tianjin Geological Academy Ltd,Tianjin 300181,China)

机构地区：[1]江西省自然资源厅国土资源交易中心,江西南昌330025 [2]江西省地质矿产勘查开发局九一六大队,江西九江332100 [3]江西省地质矿产勘查开发局赣西北大队,江西九江332100 [4]中钢集团天津地质研究院有限公司,天津300181

出　　处：《东华理工大学学报（自然科学版）》2020年第5期401-416,共16页Journal of East China University of Technology(Natural Science)

基　　金：中国地质调查局项目“江西大湖塘钨(铜)多金属矿整装勘查区关键基础地质研究”(12120114034501);江西省地质矿产勘查开发局项目“江西石门寺一区三型钨铜钼矿床成矿模式研究”([2011]81)

摘　　要：在赣北大湖塘钨多金属矿集区内的一矿带、昆山、毛公洞等矿区详查与资源储量核实过程中,发现部分花岗斑岩切割了含矿石英大脉,同时也切割了细脉浸染型、热液隐爆角砾岩型矿体与其他燕山期花岗质岩石单元。该花岗斑岩内无黑钨矿、白钨矿、黄铜矿、辉钼矿等矿石矿物,无石英脉分布,化学分析显示也无钨多金属矿化,与石门寺等矿区查明的成矿期花岗斑岩截然不同,可判断为成矿后侵入的花岗斑岩。对大湖塘一矿带成矿后花岗斑岩开展了锆石U-Pb年代学、地球化学研究,LA-ICP-MS测得锆石U-Pb年龄为(139.0±1.2)Ma,较准确地限制了矿集区成矿活动的结束时间;地球化学方面具有高硅富碱、过铝质特征及较高的分异指数DI,轻重稀土分馏明显,呈左高右低的深V型,Eu负异常明显,存在REE四分组效应,Rb/Sr、Rb/Nb比值明显高于上地壳所对应的均值0.32和4.5,也明显大于中国东部上地壳对应的均值0.31和6.83,表明其源区来自成熟度较高的地壳物质,为高分异S型花岗岩。In the process of detailed investigation and verification of resource reserves in No.1 ore belt, Kunshan, maogongdong and other mining areas of Dahutang tungsten polymetallic district in northern Jiangxi province, it was found that part of granitic porphyry cuts the ore-bearing quartz veins, meanwhile,it also cuts the veinlet disseminated type and hydrothermal crypto-explosion breccia type ore bodies and other granitic rock units. There is no wolframite, scheelite, chalcopyrite, molybdenite and other ore minerals and no quartz vein distributed in the granite porphyry, meanwhile, chemical analysis results shows that there is no tungsten polymetallic mineralization. It is diametrically opposed to the metallogenic period of granite porphyry which are identified in the Shimensi and other mining areas. Therefore it can be judged that the granite porphyries is a intrusive granite of post-metallogenic period. Zircon U-Pb geochronology and whole-rock geochemistry were applied to the post-mineralization granitic porphyry in No.1 ore belt. The granite porphyry has zircon U-Pb ages of(139.0±1.2) Ma, which accurately limited the end of mineralization in the concentration area.Its characteristics are high-silicon,rich-alkaline and peraluminous, and have higher differentiation index DI. The fractionation between HREE and HREE is pronounced,which is characterized by negative Eu anomaly with the tetrad effect of REE. The ratios of Rb/Sr、Rb/Nb are obviously higher than the corresponding average value of upper crust-0.32 and 4.5 respectively,and it is obviously higher than the corresponding average value of upper crust in eastern China-0.31 and 6.83 respectively. Geochemical characteristics reveal that the source of the granite porphyry originates from crustal material with high maturity, and that it belongs to highly fractionated S-type granite.

关 键 词：成矿后花岗斑岩 锆石U-PB定年 地球化学 S型花岗岩 大湖塘矿集区 

分 类 号：P18.67[天文地球—天文学] P58