桂中地区昆仑关与十万大山花岗岩地球化学特征对比

Comparison of geochemical characteristics of granite in Kunlunguan and Shiwandashan areas in Central Guangxi

昆仑关花岗岩体和十万大山花岗岩体是桂中地区典型岩基。岩石地球化学及烃类组分对比研究表明:十万大山花岗岩的SiO 2含量明显高于昆仑关,而昆仑关花岗岩的MgO含量明显高于十万大山,两大岩体都为高钾钙碱性花岗岩;Pb、W、Sn、Ag、Bi元素在昆仑关花岗岩体中富集,Sn、Pb元素在十万大山花岗岩体中富集;两大岩体稀土元素配分曲线变化趋势相似,呈Eu负异常;两者烃类组分曲线结构具有相似性,但昆仑山花岗岩烃类总量较高;昆仑关花岗岩和十万大山花岗岩分别为A型、S型花岗岩,分别形成于陆—陆碰撞造山的构造环境和后造山构造环境。昆仑关花岗岩体物源较深,分异性较好,其与周围区域可形成较大规模的铜、银等矿床;十万大山花岗岩体物质来源相对较浅,分异相对较差,形成矿床的规模相对较小。

Kunlunguan granite body and Shiwandashan granite body are typical batholithes in Central Guangxi.The comparative study result of rock geochemistry and hydrocarbon composition shows that SiO 2 content of Shiwandashan granite is significantly higher than that of Kunlunguan granite.MgO content of Kunlunguan granite is significantly higher than that of Shiwandashan granite.The two large intrusions are both high-potassium calc-alkaline granites.Pb,W,Sn,Ag and Bi elements are enriched in Kunlunguan granite,while Sn and Pb are enriched in Shiwandashan granite.The rare earth element distribution curves of the two major rock bodies have similar trends with a negative Eu anomaly.The hydrocarbon composition curves of the two granite bodies are similar,but Kunlunshan granite has a higher total hydrocarbon content.Kunlunguan granite is A-type granite,which is formed in the continental-continent collision tectonic environment.Shiwandashan granite is S-type granite,which is formed in the post-orogenic tectonic environment.Kunlunguan granite body has a deep provenance and good differentiation,and large-scale Cu and Ag deposits can be formed in the surrounding area.Shiwandashan granite body has relatively shallow material sources and relatively poor differentiation.The small scale of the deposit can be formed in the surrounding area.