粤北塘湾地区燕山晚期小岩体地球化学特征与铀成矿探讨  

DISCUSSION ON THE GEOCHEMICAL CHARACTERISTICS AND URANIUM MINERALIZATION OF FINE-GRAINED TWO-MICA GRANITE IN TANGWAN,NORTH GUANGDONG

作　　者：阮昆[1] 吴星根 龙自强[1] 吴建勇[1] 孙中瑞[1] 刘国安[1] 吴烈勤[1] RUAN Kun WU Xinggen LONG Ziqiang WU Jianyong SUN Zhongrui LIU Guoan WU Lieqin(No. 290 Research Institute ,CNNC,Shaoguan 512026,China Radiation Environmental Monitoring Center of Guangdong Bureau of Nuclear Industry and Geology（Guangdong Nuclear Engineering Exploration Bureau） 9Guangzhou 510800,China)

机构地区：[1]核工业二九〇研究所,广东韶关512026 [2]广东省核工业地质局辐射环境监测中心广东省核力工程勘查院,广东广州510800

出　　处：《矿物岩石》2017年第3期38-45,共8页Mineralogy and Petrology

基　　金：国家自然科学基金项目(41772066);中国地质调查局地质调查项目(12120115018101);区域评价普查项目(201639)

摘　　要：燕山晚期花岗岩小岩体的岩性为细粒二云母花岗岩,出露于诸广岩体中南部塘湾矿床北部约4km的范围内。针对细粒二云母花岗岩进行了6块样品的主量元素、微量元素和稀土元素的分析。结果表明:该岩体表现为高钾钙碱性,SiO2质量分数高(75.27%~76.55%,平均值为75.86%);富碱(Na_2O+K_2O=7.48%~7.66%,平均值为7.55%),且钾大于钠;铝过饱和(A/CNK值介于1.11~1.22之间,平均1.16)的特点。微量元素中,富集Rb,Th,U,明显亏损Ba,Zr和Hf。稀土总含量不高,配分模式呈海鸥型,轻稀土分馏较明显,重稀土分馏较弱,以及强烈的铕负异常(δEu=0.15~0.20)等特征。推测其形成于岩石圈伸展减薄的环境下,源区主要由泥质岩组成。细粒二云母花岗岩与塘湾岩体的内外接触带与近SN向、NNE向构造复合部位为成矿的有利部位。Fine-grained two-mica granite occurs in south of Zhuguangshan rock body,about 4 km north of Tangwan ore deposit. Study of main elements, trace elements and rare earth elements of the rock mass show that the rock performance for high-k calc alkaline and SiOe content is 75.27%-76.55% ,with the average value of 75.86%. The rock is rich in alkali （NazO-I-K2O=7.48%- 7. 66% ,average 7. 55%）,with the potassium higher than sodium. A/CNK values range from 1.11 to 1.22,with an average of 1.16. The fine-grained two-mica granite is enriched in Rb, Th, U, and poor in Ba,Zr and Hf. Total content of rare earth is not high with sea-gull-shape type distribution pattern. Fractionation of light rare earth elements is obvious,while the fractionation of heavy rare earth is weak,with strong EU negative anomaly （δEu=0. 15-0.20）. It is considered that the sources of the rock mass mainly come from shale rock, and is resulted from the lithosphere exten- sion and thinning. The favorable position for mineralization is the inner and outer contact zone of the fine-grained two-mica granite with Tangwan pluton,also at the composite position with SN and NNE trending structures.

关 键 词：花岗岩小岩体 地球化学特征 铀成矿探讨 塘湾 

分 类 号：P581[天文地球—岩石学]