桂东南地区干热型地热资源潜力分析  

Analysis of hot-dry geothermal resource potential in southeastern Guangxi

作　　者：孙明行 刘德民[2] 康志强 管彦武[4] 梁国科 黄锡强 叶家辉 郭尚宇 孙兴庭 唐维 冯民豪 SUN Minghang;LIU Demin;KANG Zhiqiang;GUAN Yanwu;LIANG Guoke;HUANG Xiqiang;YE Jiahui;GUO Shangyu;SUN Xingting;TANG Wei;FENG Minhao(Guangxi Institute of Geological Survey,Nanning 530023,China;School of Earth Sciences,China University of Geosciences(Wuhan),Wuhan 430074,China;China ASEAN Geosciences Cooperation Center,Nanning 530023,China;Key Laboratory of Applied Geophysics,Ministry of Natural Resources,College of Geo exploration Science and Technology,Jilin University,Changchun 130026,China;Guangxi Mineral Resources and Reserves Evaluation Centre,Nanning 530023,China)

机构地区：[1]广西壮族自治区地质调查院,广西南宁530023 [2]中国地质大学(武汉)地球科学学院,湖北武汉430074 [3]中国-东盟地学中心(南宁),广西南宁530023 [4]自然资源部应用地球物理重点实验室,吉林大学地球探测科学与技术学院,吉林长春130026 [5]广西壮族自治区矿产资源储量评审中心,广西南宁530023

出　　处：《地学前缘》2020年第1期72-80,共9页Earth Science Frontiers

基　　金：广西科技基地和人才专项广西地矿局院士工作站(桂科AD17129052);广西地质矿产局部门预算前期地质勘查经费项目“广西干热岩选区预测与分级评价”(2019016110);中国地质调查局公益性基础地质调查项目“海南昌江—广东云浮地区区域地质调查”(DD20190047)。

摘　　要：干热岩作为地热资源的重要组成部分,被视为未来的清洁能源,极具开发前景和研究价值。文章以桂东南潜在的干热岩为研究对象,通过基础地质、地球物理和地球化学资料的二次开发和实地考察,对区域构造-岩浆-沉积建造系统、岩石圈结构、现今地热场特征和地震、温泉分布规律等进行综合分析,旨在初步探讨桂东南地区干热型地热资源的潜力。结果表明:桂东南地区岩石圈较薄,分别在25km之上和6~8km处存在厚约6km和2km的双层低速层/带,指示滑脱型韧性剪切和高温地质体的存在;印支期花岗岩提供稳定的放射性生热物质基础(U含量均值5.41×10^-6,Th含量均值18.38×10^-6,K2O含量均值4.43%),新生代火山活动(OIB)在补给大量地热能的同时,为深部热物质上涌提供通道;桂东南地区现今地热存在明显异常,大地热流值介于80~100mW/m^2,北海-南宁地温梯度值高于30℃/km,钦州、合浦中-新生代断陷盆地因沉积盖层裂隙度、孔隙度和导热率低且圈闭性好而属于干热岩地热资源丰富区。对桂东南干热型地热资源潜力的研究,将为广西能源结构调整、生态环境优化和产业转型升级助力。As an important part of geothermal resource,hot dry rock(HDR)is regarded as future clean energy with great developmental prospect and research value.Here,we studied southeastern Guangxi by reexamining the basic geological,geophysical and geochemical data.We carried out field investigations of tectonic-magmatic-sedimentary formation system,lithospheric structure,characteristics of present-day geothermal field and distribution of earthquakes and hot springs to explore the potential of dry-heat geothermal resources in southeastern Guangxi.The results show that the lithosphere is relatively thin with two low-velocity layers about 6 and 2 km thick at above 25 and 6-8 km,respectively,indicating presence of slippage type ductile shears and high temperature geological bodies.In this area,Indosinian granites can provide stable supply of radiogenic heat materials(mean U concentration 5.41×10^-6;Th 18.38×10^-6;K2 O4.43%),whilst Cenozoic volcanic activities(OIB)provide a channel for the upwelling of deep thermal material while replenishing large amounts of geothermal energy.Indeed,we observed obvious geothermal anomalies in southeastern Guangxi:in Beihai-Nanning,terrestrial heat flow was at 80-100 mW/m^2 with geothermal gradient above 30℃/km;in Qinzhou and Hepu,Mesozoic-Cenozoic fault basins possess rich HDR geothermal resources that the sedimentary cap was of low cracking,porosity and thermal conductivity.Our research of dry heat geothermal potential will assist energy structural adjustment,ecological environmental optimization and industrial transformation and upgrading in Guangxi.

关 键 词：干热岩 资源潜力 低速层 断陷盆地 桂东南 

分 类 号：P314.2[天文地球—固体地球物理学]