贵东岩体燕山期与印支期花岗岩元素地球化学特征对比及其指示意义  

Comparison of Element Geochemical Characteristics of Yanshanian and Indosinian Granites in Guidong Composite Pluton and Its Indicative Significance

作　　者：邵上[1] 王春双[1] 刘斌 吴建勇[1] 叶松鑫 SHAO Shang;WANG Chunshuang;LIU Bin;WU Jianyong;YE Songxin(Research Institute No.290,CNNC,Shaoguan,Guangdong 512029,China)

机构地区：[1]核工业二九〇研究所,广东韶关512029

出　　处：《世界核地质科学》2022年第1期50-59,共10页World Nuclear Geoscience

摘　　要：燕山期花岗岩体和印支期花岗岩体为贵东复式岩体的重要组成部分。两种岩体形成于相似的构造环境,空间上紧密伴生,但相较于燕山期花岗岩印支期花岗岩中赋存着大量铀矿床。选取贵东复式岩体内的燕山期和印支期花岗岩体为研究对象,对比分析其元素地球化学特征,从而确定产铀花岗岩的指示性特征。结果表明,不同期次花岗岩的源区和成因类型存在差异,是导致其产铀能力不同的主要因素。贵东岩体产铀花岗岩主要为印支期花岗岩,其特征是:成岩年龄为219.6~236 Ma,成岩温度和氧逸度低,属于S型花岗岩,其经历同碰撞的构造背景,分布在华夏地块内。产铀花岗岩蚀变作用强,副矿物组合复杂,结晶分异作用强,SiO_(2)、Fe_(2)O_(3)和K_(2)O含量低,而Al_(2)O_(3)、TiO_(2)、MgO和CaO含量相对较高,Th/U值相对较低,这些信息可作为铀矿勘查的地球化学标志。Yanshanian and Indosinian granites are important component of Guidong composite pluton.These two types of granites were formed in similar tectonic environment and closely coexisted in space.However,compared with the Yanshanian granite,there are a large number of uranium deposits in Indosinian granite.In this paper,the Yanshanian and Indosinian granites in the Guidong composite pluton are selected and their element geochemical characteristics are compared and analyzed to determine the indicative characteristics of uranium-producing granites.The results showed that the origin and genetic types of granites in different periods are different,which is the main factor leading to the different uranium producing capacity.The uranium producing granites in the Guidong composite pluton are mainly Indosinian granites,which are characterized by low diagenetic temperature and oxygen fugidity with diagenetic age of 219.6 Ma to 236 Ma.They belong to S-type granites,and are distributed in the Cathaysia block under the tectonic background of syncollision.Uranium producting granites are characterized by strong alteration,complex accessory mineral assemblage,strong crystallization differentiation,low contents of SiO_(2),Fe_(2)O_(3) and K_(2)O,but relatively high contents of Al_(2)O_(3),TiO_(2),MgO and CaO,and relatively low Th/U value.These information can be used as geochemical indicators for uranium exploration.

关 键 词：元素地球化学特征 贵东岩体 铀成矿 华南 

分 类 号：P619.14[天文地球—矿床学]