花岗岩演化与铀钍元素富集的关系:以粤北贵东岩体为例  

The relationship between granite evolution and uranium-thorium enrichment:An example from the Guidong granite body,North Guangdong Province

作　　者：娄峰[1,2] 李宏卫[1,2] 陈光明 敖文波 赖中信 卢映新 杨燕娜[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110-117,共8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：对粤北贵东岩体铀钍丰度变化特征的研究表明,原地重熔过程导致铀钍元素向花岗岩体的上方汇聚富集,并造成铀、钍元素在空间上的分离,即在花岗岩体中,铀的丰度带位处钍丰度带之上。陆壳多次原地熔融(重熔)不但导致复式花岗岩体形成,同时造成铀元素在晚期岩体中的富集。贵东岩体内燕山早期岩体铀钍含量的东西差异被认为与卷入熔融的铀源层(寒武—震旦系)的初始埋深有关,而复式岩体铀含量的南北差异,则被解释为与晚期重熔界面倾斜方向所导致的晚期岩体的剥蚀深度有关。高铀含量和高铀钍比值并存往往是晚期岩体埋深较浅的表现,对于深部隐伏矿床的寻找有重要指示作用。The study of variations of uranium and thorium abundances in the Guidong granite body suggested that the in-situ melting resulted in enrichment of uranium and thorium elements at the top of the crustal granite layer,and caused spatial separation of the two elements which is shown by the fact that the maximal abundance zone of uranium in a granite body is generally located over that of thorium.Multiple in-situ melting led not only to the formation of a composite granite body（CGB）,but also to the enrichment of uranium in the younger members of the CGB.Characteristics of relatively higher uranium and lower thorium contents in the eastern part of the Early Yanshanian granite of Guidong CGB are considered to be related to the original buried depth of the source-layer of uranium（the Sinian-Precambrian strata） while the difference of uranium abundance from south to north of the CGB is related to the attitude and erosion of the MI of the latest stage.It is concluded that the coexistence of high uranium content and high U/Th ratio usually indicates the possibility of a concealed granite body,which is of practical significance for exploration of concealed uranium deposits.

关 键 词：铀钍丰度 原地重熔 复式岩体 粤北 

分 类 号：P588.121[天文地球—岩石学]