地学前缘 ›› 2020, Vol. 27 ›› Issue (1): 63-71.DOI: 10.13745/j.esf.2020.1.8

• 地热资源评价与选区 • 上一篇    下一篇

广东省惠州市博罗—大亚湾NW-SE向断陷系统地热资源分析

张根袁,刘德民,张婧琪,温琛,康志强,关俊鹏   

  1. 1. 中国地质大学(武汉) 地球科学学院, 湖北 武汉 430074
    2. 中国地质大学(武汉) 地质调查研究院, 湖北 武汉 430074
    3. 广西壮族自治区地质矿产勘查开发局, 广西 南宁 530023
    4. 江苏省地质调查研究院, 江苏 南京 210018
  • 收稿日期:2019-06-02 修回日期:2019-10-30 出版日期:2020-01-20 发布日期:2020-01-20
  • 作者简介:张根袁(1994—),男,硕士研究生,构造地质学专业。E-mail:2929570014@qq.com
  • 基金资助:

    广州能源研究所“东南沿海干热岩控热构造调查与研究项目”(2018296001);江苏地质调查研究院“苏北盆地干热岩控热构造背景专题研究项目”(2018016417)

Analysis of structural controls of geothermal resources in the NW-SE trending BoluoDayawan fault depression in Huizhou City, Guangdong Province

ZHANG Genyuan,LIU Demin,ZHANG Jingqi,WEN Chen,KANG Zhiqiang,GUAN Junpeng   

  1. 1. School of Earth Sciences, China University of Geosciences(Wuhan), Wuhan 430074, China
    2. Geological Survey Institute, China University of Geosciences(Wuhan), Wuhan 430074, China
    3. Guangxi Bureau of Geology and Mineral Prospecting and Exploitation, Nanning 530023, China
    4. Geological Survey Institute of Jiangsu Province, Nanjing 210018, China
  • Received:2019-06-02 Revised:2019-10-30 Online:2020-01-20 Published:2020-01-20

摘要:

博罗—大亚湾断陷区位于广东省惠州市西南部,处在我国东南沿海构造活动带,自新生代以来,受太平洋板块和欧亚大陆板块俯冲作用的影响,洋陆系统相互作用导致构造活动活跃,岩浆侵入、火山喷发频繁,地震活动强烈,地表热流值较全国而言比较高,沿着北西走向的博罗—大亚湾线性断陷系统内发育厚层的陆相碎屑沉积,众多的高温热泉出露在裂陷边界,显示出良好的地热资源潜力。通过研究分析深部重磁电震等地球物理资料,发现区域内不仅拥有丰富的浅层次水热型地热热源,深部层位可能存在优质的干热岩储层,初步推断其热源来自新生代南海地幔底辟作用,其导致壳幔物质非均匀流动,在陆壳地区底部发生熔融,向浅部不断传导形成线性热隆伸展构造,控制着整个断陷内的地热系统。

关键词: 博罗—大亚湾断陷, 地热系统, 新生代, 地球物理

Abstract:

The BoluoDayawan fault depression (BDFD) is located in the Pearl River Mouth Basin in southwestern Guangdong Province, bordering in the north by Yangtze block and the west by Youjiang block of the Eurasian plate. At the beginning of the Cenozoic, intense tectonic activities, such as frequent magmatic intrusions, volcanic eruptions, strong earthquakes, and other neotectonics, occurred continuously in the studying area, owing to the presentday configuration of interactions between oceaniccontinental systems and westwards directed oblique subduction of the Pacific plate beneath the Eurasia plate. The BDFD is in the active tectonic coast belt of southeastern China, one of the Pacific Fire Ring’s (PFR) most spectacular and productive areas of large scale of magmatic, young volcanic and geothermal manifestation. In particular, the depression hosts an exceptionally vigorous active geothermal province which coupled with its high surface heat flow and temperature gradient, is as big as all southern China continent. Structures of the geothermal anomalies have been characterized by the NWtrending normal faults surrounded by the BDFD due to extension; inside the structures developed thick continental clastic deposits, large area of outcropped granite intrusions with rich thermogenic elements, and numerous high temperature hot springs exposed along the NWtrending linear BDFD, inductive to a huge geothermal system. Abundant hotwaterdominated geothermal resources stored in shallow sedimentary layers have been exploited and utilized by previous hydrogeological and geothermal survey. However, deeper HDR geothermal energy exploration is limited by current technology and economic conditions. From the experience of geothermal energy exploration around the world, the relationship between geological condition and temperature distribution is crucial in HDR exploration. Here, we studied the depths of a variety of Moho’s surface and Curie point isotherm and the distribution of the Bouguer gravity anomalies patterns under the BDFD, by a comprehensive multidisciplinary (gravity, magnetic, electric, seismic characteristics, etc) analysis of geophysical data. Aa a result, we derived preliminarily the crustal geological structure and temperature conditions. Considering both HDR geothermal energy generation principles and basic regional tectonic background, we infer that the heat source for HDR is derived from mantle diapirism which caused the crustmantle material nonuniform flow after producing partial melting. The melting position occurs at the bottom of continental crust region with huge upward heat transfer to the shallow layers. The ascending hot material and huge vertical stress leads to the Cenozoic new deep faults and subsidence of shallow terrain. Eventually, massive heat transfers to upper crustal rock mass through high thermal conductivity stratigraphy units and accumulates to form HDR thermal reservoir. The fracturing neotectonics superimpose on the previous Yanshanian tectonic system and reactivate the whole fault structures, facilitating heat exchange for the migrating shallow cold water. The tectonic mechanism and role of linear thermal uplift extension as shown in the conceptual model are in agreement with knowledge from other HDR geothermal studies.

Key words: BoluoDayawan fault depression (BDFD), geothermal system, Cenozoic, geophysics

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