粤北贵东复式岩体的形成与重熔界面的形态演化  

Formation mechanism of the Guidong CGB in North Guangdong and the evolution of melting interfaces

作　　者：李宏卫[1,2] 娄峰[1,2] 陈光明 邱列 唐煜坤[1] 杨燕娜[1] 许冠军[1] 

机构地区：[1]中山大学地球科学系,广东广州510275 [2]广核-中大花岗岩与铀矿资源研究所,广东广州510800

出　　处：《地学前缘》2011年第1期39-48,共10页Earth Science Frontiers

基　　金：高等学校博士学科点基金项目(20070558033);广东省核工业地质局项目(321107102277)

摘　　要：根据花岗岩的"原地重熔-壳内对流"理论,对粤北贵东复式岩体的各种地质地球化学资料进行重新编码,证实该复式岩体的形成是该区陆壳中生代多次熔融(重熔)的结果,并在此基础上重建该区不同期次重熔界面形态。研究表明,早侏罗世重熔界面总体自南向北倾斜,因而在同一剥蚀面下,岩体自南向北依次出露中心相、过渡相、边缘相的岩性;晚侏罗世的熔融(重熔)事件基本局限于早期岩体内部,故该期岩体普遍比早期岩体偏酸性,本期岩浆界面自北向南倾斜。早白垩世的熔融(重熔)事件形成了石英正长岩和次英安斑岩两类不同的岩石,两者岩性的较大差异与卷入的源岩有关,本期的重熔界面同样自北向南倾斜,据此进行的隐伏矿床预测已经获得验证。Re-encoding of the geological and geochemical data concerning the Guidong Composite Granite Body（CGB） with the hypothesis of in-situ melting and crustal convection suggests that the Guidong CGB was formed by repeated crustal melting of this area in the Mesozoic.On that basis,this paper rebuilds the melting interface（MI） formed in different Yanshanian periods： the MI formed in the Early Jurassic totally tilts from south to north,which resulted in the early Yanshanian granite cropping out from inner facies to transitional facies and to margin facies from south to north on the present-day denudation plane;the MI formed in the melting event of the Late Jurassic totally tilts from north to south,and the distribution of granite bodies formed in this period was basically limited within the old member of the Guidong CGB thus usually more acid than the old one;the melting event of the Early Cretaceous produced a southward tilting MI and formed two kinds of rocks,quartz syenite and subdacite-porphyry.Difference of the rocks is likely concerning with the source rocks involved into the melting event.Metallogenic prediction on the above model in the Xiazhuang ore-field,eastern Guidong CGB,has been approved by drillings to a certain extent.

关 键 词：贵东复式岩体 下庄矿田 原地重熔 重熔界面形态 

分 类 号：P588.121[天文地球—岩石学]