桂北豆乍山岩体放射性地球化学特征及其干热岩资源潜力研究  

Radioactive geochemical characteristics of rocks from Douzhashan pluton in northern Guangxi and its implications for hot dry rock resources

作　　者：谭双 陈琪[1] 王安东[2] 万建军[2] 黄剑[1] 高翔[1] TAN Shuang;CHEN Qi;WANG An-dong;WAN Jian-jun;HUANG Jian;GAO Xiang(Changsha Uranium Geology Kesearch Institute,CNNC,Changsha 410007,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanrhang 330013,China)

机构地区：[1]核工业二三〇研究所,湖南长沙410007 [2]东华理工大学核资源与环境国家重点实验室,江西南昌330013

出　　处：《岩石矿物学杂志》2021年第3期501-512,共12页Acta Petrologica et Mineralogica

基　　金：中国核工业地质局地勘费项目(201917,202035-6);国家重点研发计划项目(2018YFA0404104);核资源与环境国家重点实验室自主基金(Z1912)

摘　　要：对桂北豆乍山岩体钻孔样品进行了放射性生热元素含量、岩石密度和岩石热导率测试。结果显示该岩体花岗岩U平均含量为17.49×10^(-6),Th平均含量为27.54×10^(-6),K_(2)O平均含量为4.64%,放射性生热率平均值6.46μW/m^(3),高于地壳平均值及大部分华南其他岩体的放射性生热率值;岩石密度平均在2.57 g/cm^(3)左右,与世界范围内花岗岩密度的平均值大致相同;岩石热贡献率主要来自Th和U的放射性衰变热,而U的贡献率相对更高。研究区岩石热导率平均为3.389 W/mK,与目前已知的花岗岩热导率平均值相近。通过本文及周边其他岩体的研究结果,结合前人资料,推断豆乍山岩体所在的苗儿山地区,乃至桂北地区的地幔热流值低于地壳热流值贡献,属于"热壳冷幔"型岩石圈热结构。根据豆乍山岩体放射性生热元素和生热率的优势,认为其干热岩开发潜力较大,可对其进行进一步干热岩评价工作。Radioelement content,rock density and rock thermal conductivity of drill hole samples within Douzhashan pluton of northern Guangxi were analyzed.The results suggest that the average U,Th and K2O values of the investigated granites are 17.49×10^(-6),27.54×10^(-6) and 4.64%,respectively.The average value of rock density is 2.57 g/cm^(3),which is in good agreement with the average density of granites in the world.The average radiogenic heat production of the investigated granites is 6.46μW/m^(3),which is obviously higher than that of crustal rock and most plutons in South China.The main heat production contribution is sourced from the decay of U and Th,and the U plays the most important role.The average rock thermal conductivity is 3.389 W/mK,close to that of the middle-upper crustal rocks.Combined with the previous data around the study area from previous researchers,this paper indicates that the crust contributes more heat flow to the surface than the mantle,thus the area of Miao'ershan and northern Guangxi is a typical region with cold crust and hot mantle type lithospheric thermal regime.Based on the advantages of radioelement content and radiogenic heat production,the authors hold that the Douzhashan pluton has a great exploration potential as hot dry rock resource,and hence more further work is needed in the future.

关 键 词：豆乍山岩体 放射性生热率 热导率 热壳冷幔 干热岩 

分 类 号：P598[天文地球—地球化学]