宁芜火山岩盆地凹山铁矿床侵入岩锆石微量元素特征及其地质意义  

Zircon trace element characteristics of intrusions in the Washan iron deposit of Ningwu volcanic basin and their geological significance

作　　者：段超[1,2] 李延河[1] 毛景文[1] 侯可军[1] 袁顺达[1] 

机构地区：[1]中国地质科学院矿产资源研究所,国土资源部成矿作用和资源评价重点实验室,北京100037 [2]地质过程与矿产资源国家重点实验室,中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《中国地质》2012年第6期1874-1884,共11页Geology in China

基　　金：公益性行业科研专项项目(200911007,200811114);国家自然科学重点基金项目(40930419);国家重点基础研究发展计划项目(2007CB411405);地质过程与矿产资源国家重点实验室开放基金项目(GPMR201029)联合资助

摘　　要：凹山铁矿床是玢岩铁矿床的典型代表之一,矿床中发育有辉石闪长玢岩和花岗闪长斑岩两类侵入岩。锆石微量元素分析结果显示,两类岩浆岩中锆石的稀土元素配分模型相似,花岗闪长斑岩中的锆石较辉石闪长玢岩中锆石具有较高的U含量,较高的U/Yb比值以及相似的Yb、Hf和Y含量,结合前人的研究认为,两者的源区具有一致性,均源于富集地幔,并在其上涌就位过程中混染了壳源物质,其中花岗闪长斑岩混染了更多的壳源物质。花岗闪长斑岩中锆石的Ce(Ⅳ)/Ce(Ⅲ)比值集中于0～100,远低于斑岩铜矿成矿岩体Ce(Ⅳ)/Ce(Ⅲ)>300的特征,具有较弱的形成斑岩型铜金矿的特征,但在宁芜地区发育的这类花岗闪长斑岩是否具有形成铜金矿化的潜力仍需进一步的研究和勘查。The Washan iron deposit is a representative porphyrite iron deposit.There are two types of intrusions： One is gabbro-diorite porphyrite closely related to the iron mineralization and serves as the host rocks,and the other is granodiorite porphyry cutting across the ore body,which has been rarely studied.Detailed zircon LA-ICP-MS trace element measurement was performed on these two intrusions.The two intrusions have similar chondrite-normalized REE patterns of zircons and Yb,Hf and Y values,whereas zircons from the granodiorite porphyry have higher U values and U/Yb ratios.In combination with previous studies of isotope geochemistry,the authors infer that these intrusions have similar sources,and much crust material was involved in the formation of granodiorite porphyry during the ascending process.Zircon Ce（Ⅳ）/Ce（Ⅲ）ratios of the granodiorite porphyry are concentrated in the range of 0-100,lower than the values of zircons（300） from the granite related to the porphyry Cu-Au mineralization;nevertheless,they have similar characteristics of δEu（0.4）.Thus,it is not certain whether the granodiorite porphyry had the potential to form copper and gold deposits,and hence further researches are needed concerning the possible relationship between the granitic stocks and copper and/or gold mineralization.

关 键 词：锆石微量元素 Ce(Ⅳ) Ce(Ⅲ)比值 凹山 玢岩铁矿 宁芜 

分 类 号：P618.31[天文地球—矿床学]