安徽蚌埠西贾庄铅锌金银矿床赋矿地层和岩浆岩年代学、Hf同位素、地球化学特征及其意义  

Chronology,Hf isotope and geochemistry of the ore-hosting and magmatic rocks in Xijiazhuang Pb-Zn-Au-Ag deposit,Bengbu,Anhui Province,and its signiciance

作　　者：陈杨 范裕[1,2] 刘一男 王彪[1,2] 刘青 CHEN Yang;FAN Yu;LIU YiNan;WANG Biao;LIU Qing(School of Resources and Environmental Engineering,Ore Deposit and Exploration Centre(ODEC),Hefei University of Technology,Hefei 230009,China;Anhui Province Engineering Research Center for Mineral Resources and Mine Environments,Hefei 230009,China;No.312 Geological Team,Bureau of Geology and Mineral Exploration of Anhui Province,Bengbu 233040,China)

机构地区：[1]合肥工业大学资源与环境工程学院,合肥工业大学矿床成因与勘查技术研究中心(ODEC),合肥230009 [2]安徽省矿产资源与矿山环境工程技术研究中心,合肥230009 [3]安徽省地质矿产勘查局三一二地质队,蚌埠233040

出　　处：《岩石学报》2019年第12期3763-3781,共19页Acta Petrologica Sinica

基　　金：国家重点研发计划项目(2016YFC0600206);安徽省国土厅公益性地质项目(2016-g-3-35);中央高校基本科研业务费专项资金(PA2019GDZC0093)联合资助

摘　　要：安徽省北部蚌埠隆起位于华北克拉通东南缘,郯庐断裂带西侧。蚌埠隆起和胶东金矿区现今位置被认为是郯庐断裂带大规模左行平移引起,推测两区有相似的成矿背景。蚌埠隆起东西向长约160km,以固镇-永平岗断裂为界分为东西两段。前人已对蚌埠隆起东段的成岩成矿作用开展了元素地球化学和成矿流体等方面的研究,而蚌埠隆起西段由于第四系覆盖,一直未发现岩浆岩和相关成矿作用,被认为是无矿区,未有相关研究。西贾庄矿床是近年来蚌埠隆起西段新发现的矽卡岩型铅锌金银矿床,为区内成岩成矿作用研究提供了良好的对象。本次工作在矿床地质特征研究基础上,系统开展了矿床赋矿地层和岩浆岩的年代学、地球化学和Hf同位素的研究,确定了成矿岩体的源区、性质和演化,丰富和完善了区内成岩成矿作用研究。西贾庄矿床的赋矿地层为黑云母斜长片麻岩,成岩时代为2466±12Ma,确定其为五河群西堌堆组地层,其原岩来自2.65~2.85Ga新生地壳的重熔;花岗闪长斑岩为成矿岩体,成岩时代为113.0±1.0Ma^114.9±1.7Ma,石英二长岩为成矿期后脉岩,成岩时代为112.1±0.8Ma,因此限定成矿时代约为112~115Ma。花岗闪长斑岩和石英二长岩的地球化学特征基本相同,均属高钾钙碱性、准铝质-弱过铝质的Ⅰ型花岗岩类。这两类侵入岩的εHf(t)=-16.6^-12.5,tDM2=1963~2264Ma,表明它们的岩浆源区为老地壳(主要为古元古代)的部分熔融,推测其形成于古太平洋板块俯冲作用下的弧后伸展环境。通过对比,西贾庄矿床侵入岩与蚌埠隆起东段早白垩世晚期侵入岩体具有相同的构造背景和源区,蚌埠隆起西段在覆盖层之下仍有一定的成矿潜力。Bengbu Uplift is located in the southeastern margin of North China Craton,the west of Tan-Lu Fault Zone. It is considered that the current position of the Bengbu Uplift and Jiaodong gold district was caused by the intense sinistral movement of the Tan-Lu Fault Zone,and the two regions have similar metallogenic backgrounds. The east-west length of the Bengbu Uplift is about 160 km,and the boundary of east and west part of Bengbu Uplift is Guzheng-Yongpinggang fault. Previous works have been studied on chronology,geochemistry,isotopes and ore-forming fluids about the magmatism and mineralization in the east of Bengbu Uplift. Due to the west of Bengbu Uplift wildly covered by the Quaternary sediments,there is no study on the magmatism and mineralization.Xijiazhuang deposit is a newly discovered and unique deposit in the west of Bengbu Uplift. It provides a good object for the study of magmatism and mineralization in this area. Based on the geological characteristics of the deposit,the ore-hosted strata and related magma rocks in Xijiazhuang deposit will have to be detailed study on chronology,geochemistry and Hf isotope in this work. This study constrains the sources,characteristic and evolution of the magma,and also further improve the understanding of the magmatism and mineralization in this area. The crystallization of the biotite plagioclase gneiss is 2466 ± 12 Ma,it belongs to the Xigudui Formation of Wuhe Group and was derived from remelting of juvenile crust materials( 2. 65 ~ 2. 85 Ga). The age of the two groups of ore-host magmatic rocks( granodiorite porphyry) are 113. 0 ± 1. 0 Ma and 114. 9 ± 1. 7 Ma. The age of quartz monzonite is 112. 1 ± 0. 8 Ma,and it was formed after the mineralization. Hence this deposit was mineralized at 112 ~ 115 Ma. The two types of intrusive rocks have the following common geochemical characteristics. The major and trace elements show that they are high-K calc-alkaline,metaluminous to weakly peraluminous,I-type granite. They display enrichment in light REEs,depletion in hea

关 键 词：蚌埠隆起 西贾庄矿床 赋矿围岩 成岩作用 

分 类 号：P588.13[天文地球—岩石学] P588.345[天文地球—地质学]