安徽铜陵狮子山铜矿田岩石的地球化学特征

Geological and Geochemical Characteristics of the Shizishan Ore-Field in Anhui Province

安徽铜陵狮子山矿田是铜陵矿集区内储量最大的铜(金)矿田。矿田内矿床类型多样,成矿作用复杂,分布有东狮子山、西狮子山、大团山、老鸦岭、冬瓜山和花树坡等铜(金)矿床。这些矿床均围绕岩体产出,多数为隐伏矿,赋存于上石炭统-中三叠统的不同层位,在空间上具有明显的分带特征,由下向上依次为层控矽卡型、矽卡岩型和热液脉型矿床,其中以前2种类型最为重要。矿田成矿经历了海西期和燕山期2个时代,燕山期为主要成矿期。中酸性侵入岩是狮子山矿田内铜矿床成矿物质的主要来源。该矿田主要岩浆岩为石英闪长岩、辉石二长闪长岩和花岗闪长岩,均为高钾钙碱性系列,属中酸性岩石,为造山带派生的碱性和偏碱性花岗岩。岩石地球化学特征表明本区岩浆岩为幔源岩浆分异的产物,属于壳幔混染型,岩浆岩后期同化围岩使硅质流失,并且在岩浆侵入过程中与Na2O、K2O含量较高的围岩发生了同化混染作用,不同岩石之间可能有某种成因上的联系。

The Shizishan ore field is the largest Cu-Au ore-field in the Tongling cluster,Anhui province.Several Cu-Au deposits,including Dongshizishan,Xishizishan,Datuanshan,Laoyaling,Dongguashan and Huashupo,are embedded in Upper Carboniferous to Middle Triassic strata and occur in the vicinity of intrusions.According to the temporal and spatial relationship between mineralization and igneous intrusions,three ore types can be distinguished： stratabound skarn type,skarn type and hydrothermal vein type.The two skarn types are economically most important.Mineralization of the Shizishan ore-field relates to Hercynian and dominant Yanshanian magmatism.The intermediate-acid intrusions are the main sources of the metals of the Cu deposits in the Shizishan ore-field.The main magma as quartz diorite,pyroxene monzodiorite and granodiorite are high calc-alkaline series rocks,which originate in orogen granite.The geochemical characteristics of the rock show the magma coming from the mantle with mixing of high Na2O and K2O country rock by assimilate-contamination during the magma intrusion into the crust.Therefore,the different magma rocks have a relationship to the rock genesis.