鲁西贺家沟二长闪长玢岩成矿岩体:锆石年代学和微量元素证据  

The ore-forming monzodiorite in the Hejiagou area of the western Shandong:Evidences from chronology and trace elements of zircons

作　　者：武斌 董美川 李明波 张海瑞 刘继勇 WU Bin;DONG Mei-chuan;LI Ming-bo;ZHANG Hai-rui;LIU Ji-yong(No.4 Exploration Institute of Geology and Mineral Resources,Weifang 261021,China;Shandong Coastal Zone Geology Research Center,Weifang 261021,China;Faculty of Earth Sciences,China University of Geosciences(Wuhan),Wuhan 430074,China)

机构地区：[1]山东省第四地质矿产勘查院,山东潍坊261021 [2]山东省地矿局海岸带地质环境保护重点实验室,山东潍坊261021 [3]中国地质大学(武汉),湖北武汉430074

出　　处：《矿物学报》2022年第6期745-758,共14页Acta Mineralogica Sinica

基　　金：山东省地勘基金项目(编号:鲁勘字[2016]43号,鲁勘字[2018]36号,鲁勘字[2020]16号);山东省地质矿产勘查开发局科技创新项目(编号:鲁地字[2021]6号)联合资助。

摘　　要：贺家沟地区位于山东省西部沂南县南约20 km,地处郯庐断裂带西侧的沂山凸起东南缘,区域上已经发现了沂南金场和铜井两处金及多金属矿床。贺家沟地区处于沂南金场、铜井矿区外围地区,成矿条件非常相似,近几年在该地区的地球物理、地球化学勘查找矿工作也指示其具有较好成矿潜力,并在该地区发现多处金多金属矿点。本次研究尝试运用贺家沟地区二长闪长玢岩锆石微区成分来解释成矿岩体的构造环境、岩浆演化特征以及区内成矿作用。LA-ICP-MS锆石U-Pb年代学显示贺家沟二长闪长玢岩加权平均年龄为(128±0.43)Ma,为早白垩世。锆石结晶温度为662~734℃,锆石中Th/U比值为0.71~1.40,表示锆石均为岩浆型锆石;锆石Sc/Yb为0.40~0.92,U/Yb为0.48~1.48,Th/Yb为0.43~1.75,指示其岩浆具有大陆弧型和大陆花岗质岩浆特征。锆石w(Pb)为3.62×10^(-6)~20.06×10^(-6),w(Th)为116.6×10^(-6)~1023.0×10^(-6),显示Ⅰ型花岗岩特征,即为壳幔混合成因;锆石Eu/Eu^(*)为0.434~0.681,Ce/Ce^(*)为16.450~408.509,表明其具有很好的斑岩型铜金矿成矿潜力。The Hejiagou area is located in approximately 20 kilometers south of the Yinan County town in the western Shandong.Tectonically,it is located in the southeast margin of the Yishan Salient on the west side of the Tanlu Fracture Zone.Two gold and polymetallic deposits including the Jinchang and Tongjing deposits,have been discovered in the region.The Hejiagou area is located in the peripheral areas of the Jinchang and Tongjing deposits with very similar metallogenic conditions.Geophysical and geochemical surveys carried out in the area in recent years have also indicated that there is good mineral prospecting potential,as several gold and polymetallic occurrences have been found in the area.In this study,we have attempted to interpret the tectonic setting,magmatic evolution characteristics,and mineralization of the mineralized intrusive body of monzodiorite porphyrite by using its zircon microzonal compositions.The LA-ICP-MS zircon U-Pb dating data show that the monzodiorite porphyrite in the Hejiagou area has a weighted average age of 128±0.43 Ma,indicating that it was formed in the early Cretaceous.The zircons have crystallization temperatures of 662-734℃ and Th/U ratios of 0.71-1.40,indicating that they are all magmatic zircons.The zircons have Sc/Yb ratios ranging from 0.40 to 0.92,U/Yb ratios ranging from 0.48 to 1.48,and Th/Yb ratios ranging from 0.43 to 1.75,indicating that the magma has characteristics of continental arc type magma and continental granitic magma.The zircons have Pb contents ranging from 3.6 to 20.1 ppm and Th contents ranging from 116.6 to 1023.0 ppm,indicating that the magma has characteristics of the Ⅰ type granite and has the crust-mantle mixed origin.The zircons have Eu/Eu^(*)values ranging from 0.434 to 0.681 and Ce/Ce^(*)values ranging from 16.450 to 408.509,indicating that there is a very good potential for prospecting porphyry copper-gold deposits in the area.

关 键 词：二长闪长玢岩 锆石 U-Pb地质年代学 微量元素 鲁西贺家沟地区 

分 类 号：P579[天文地球—矿物学] P595[天文地球—地质学] P597P611.1