胶西北地区北截金矿闪长玢岩锆石SHRI MP年龄及其地质意义  

Zircon SHRIMP Age of Diorite-Porphyrite in Beijie Gold Deposit from the Northwest Jiaodong Area and Its Geological Implications

作　　者：耿科[1,2] 王瑞江[3] 李洪奎[2] 单伟[2] 李大鹏[2] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]山东省地质科学研究院,山东省金属矿产成矿地质过程与资源利用重点实验室,国土资源部金矿成矿地质过程与资源利用重点实验室,济南250013 [3]中国地质科学院矿产资源研究所,北京100037

出　　处：《地质学报》2015年第6期1099-1107,共9页Acta Geologica Sinica

基　　金：国土资源部大调查项目“全国重要矿产资源潜力评价成果集成”(编号:12120114051301);国土资源部公益性科研专项“胶东招平断裂带深部特征与金成矿过程研究”(编号:201511029);山东省2012年度整装勘查区项目“山东省招远-莱州地区金矿成矿条件和成矿规律研究”(编号:鲁勘字201203号)联合资助

摘　　要：山东省招远市北截金矿是胶西北地区发现较早的金矿之一，主要赋存于严格受NEE向断裂控制的黄铁绢英岩化蚀变带内，是典型的破碎带蚀变岩型金矿。本文通过对矿区内切穿矿体的闪长玢岩、郭家岭序列下属北截岩体的地质背景和SHRIMP锆石U-Pb年代学研究，得出闪长玢岩形成年龄为117±2Ma，北截岩体形成年龄为129±1Ma，限定北截金矿成矿年龄在117-129Ma之间，属早白垩世。锆石样品中测得Ar3、Z、J3等多个期次的继承锆石年龄，表明北截岩体和闪长玢岩形成过程具有多重继承演化性。根据同源岩浆的成岩成矿时间差及岩体与金矿的空间位置，判断郭家岭序列与金矿关系更为密切。讨论了胶东金矿的成矿期次和构造环境，认为其形成于俯冲造山带的弧后伸展环境，其形成与演化受中生代以来中国东部岩石圈大规模减薄、地幔上涌或陆缘裂谷的影响，最终成因可能与地幔柱有关。The Beijie gold deposit in Zhaoyuan city is one of the earliest discovered gold deposit in the northwest Jiaodong area.It is a typical altered tectonite-type gold deposit which lies in beresitization alteration zone strictly controlled by an NEE fault.This article studies geological background and zircon SHRIMP geochronology of diorite-porphyrite cutting through orebody and Beijie intrusion from Guojialing sequences.Dating result of zircons from diorite-porphyrite is 117±2Ma and Beijie intrusion is 129±1Ma,suggesting that the Beijie gold deposit was formed in early Cretaceous with an age of 117-129Ma.Multiple stages of inherited zircon age of Ar3 ,Z,J3 gained from zircons in Beij ie intrusion and diorite-porphyrite imply that the process of rock forming was very complicated and inherited.Guojialing sequence is 5-10Ma earlier than gold deposits in the Jiaodong area,and it is more closer to gold deposits in space distribution,suggesting that it is much more closer to a magma source of ore-forming fluid in the Jiaodong area.Ore-forming stage and tectonic environment of Jiaodong gold deposits are also discussed.It is conclucled that the Jiaodong gold concentration area was formed in an environment of back-arc extending.Its formation and evolution were controlled by large-scale lithospheric thinning,mantle upwelling,and continental margin rift in east China in Mesozoic.It was very probably related to a mantle plume.

关 键 词：锆石SHRIMP年龄 闪长玢岩 北截金矿 胶西北 郭家岭 

分 类 号：P597.3[天文地球—地球化学] P618.51[天文地球—地质学]