广西花山与姑婆山主体花岗岩地球化学特征对比

Comparison of geochemical characteristics of the main granites in Huashan and Guposhah,Guangxi

花山花岗岩及姑婆山花岗岩是桂东北地区典型的岩基。通过对其进行岩石地球化学及烃类组分对比研究,结果发现:姑婆山花岗岩SiO2含量高于花山花岗岩,而MgO含量则要低的多,都具有准铝质—弱过铝质碱性的特征;W、Sn、Pb、Bi均在两个花岗岩体中高度富集,微量元素组合特征基本相似;姑婆山花岗岩稀土元素总量比花山花岗岩低,且Eu的负异常要更加明显;两大岩体的烃类组分曲线结构具有相似性,但姑婆山花岗岩总烃含量较高;两岩体均为S型花岗岩,主要形成于后造山构造环境。姑婆山花岗岩体的成岩物质来源于相对较浅的地壳上部,岩体分异性好,与钨锡矿的形成密切,且可形成较大规模的矿床。而花山花岗岩体成岩物质来源相对较深,为上地壳与中地壳混合的产物,其周围地区除了可以形成钨锡矿,还可形成铌钽、铀矿等,但岩体分异性较差,由其引起的矿化规模较小。

Huashan and Guposhan granite bodies are the typical magmatic beds in the northeast Guangxi.On the basis of comparative study of petrogeochemistry and hydrocarbon composition,it is found that the SiO2 content of Guposhan granite is higher than that of Huashan granite,as the MgO content of Guposhan granite is much lower than that of Huashan granite.Both of them have the characteristics of metaluminous rock-weak peraluminous alkalinity rock.W,Sn,Pb and Bi elments are greatly enriched in two granite bodies,and the trace element assemblage feature is basically similar to each other.The total amount of rare earth elements in Guposhan granite is lower than that of Huashan granite,and the negative anomaly of Eu is more obvious.The curve pattern of hydrocarbon composition in two granite masses is similar to each other,but the total hydrocarbon content of Guposhan granite is significantly higher than that of Huashan granite.Huashan granite and Guposhan granite are S-type granite mainly formed in the post-orogenic tectonic setting.The diagenetic material of Guposhan granite comes from the shallow part of upper crust.The granite bed has a good differentiation,and it is closely related to the formation of tungsten-tin deposits and there could be hosted for several large-scale deposits.The source of diagenetic material of Huashan granite body is from the deep part,which is the mixture product of upper crust and middle crust.In addition to tungsten-tin deposits,niobium-tantalum and uranium deposits could also be formed in the surrounding area,but the granite mass has a poor differentiation and the mineralization scale caused by them is relatively small.