SEISMOLOGY AND GEOLOGY ›› 2003, Vol. 25 ›› Issue (3): 421-429.

• Brief Report • Previous Articles     Next Articles

GEOCHEMISTRY OF GEOTHERMAL WATER AND NOBLE GASES IN YANHUAI BASIN, CHINA

WANG Guang-cai1, ZHANG Zuo-chen2, WANG Min3, WANG Ji-hua1, LIU Wu-zhou1, YI Li-xin1, SUN Ming-liang4   

  1. 1. Institute of Geology, China Seismological Bureau, Beijing 100029, China;
    2. Chinese Institute of Geological Environmental Monitoring, Beijing 100081, China;
    3. China Geological Survey, Beijing 100035, China;
    4. Lanzhou Institute of Geology, Chinese Academy of Sciences, Lanzhou 730000, China
  • Received:2002-02-26 Revised:2002-09-10 Online:2003-09-03 Published:2009-10-26

延怀盆地地下热水与稀有气体的地球化学特征

王广才1, 张作辰2, 汪民3, 王基华1, 刘五洲1, 易立新1, 孙明良4   

  1. 1. 中国地震局地质研究所, 北京, 100029;
    2. 中国地质环境监测院, 北京, 100081;
    3. 中国地质调查局, 北京, 100035;
    4. 中国科学院兰州地质研究所, 兰州, 730000
  • 作者简介:王广才,男,1962年出生,1996年毕业于中国地质大学(北京)水文地质专业,获得博士学位,研究员,主要从事水文地质、地震地下流体、水化学和地热方面的研究工作,电话:010-62009346,E-mail:wanggc@pku.edu.cn.
  • 基金资助:
    地震科学联合基金(198062)和科技部项日(951102)共同资助.

Abstract: In the past several years, a series of geologic, seismologic, geochemical and geophysical investigations have been conducted to understand the crustal structure, activity of active faults and seismic risk in the Yanhuai Basin. During the investigations, a large number of data about the pre-seismic, co-seismic and post-seismic behaviors of subsurface fluids have been obtained by the Seismic Precursory Monitoring Stations in the area. This paper deals with the geochemistry of groundwater and noble gases in this region. It is aimed at the understanding of the background of groundwater, which is sensitive indicator for both earthquake and active faults in the region. The study shows that geothermal water in this region originates mainly from meteoric rainfall, the circulation depth is 1 600~3 800m, the temperature of water at the depths is 57~112℃, and the residence time is 50~30 320yr. Groundwater in this region can be divided chemically into HCO3-Na, HCO3-Cl-Na, HCO3-SO4-Na-Mg and SO4-Na types, the TDS and pH of which range from 527.6~938.0 ppm and 7.50~8.73, respectively, belonging to low TDS and neutral-alkaline thermal water. The results of water-rock equilibrium calculations by NETPATH 2.0 show that groundwater in this area is over-saturated with regard to quartz and in equilibrium with chalcedony. The noble gases of geothermal water originate from meteoric, crust and mantle sources, respectively. The anomalies of geothermal water and gases regime before the occurrence of Datong, Baotou and Zhangbei earthquakes were closely related to the faults and their activity, i.e., those anomalies occurred in the places where the circulation depth of the groundwater is great, or even the circulation depth is shallow but having an evidence of mantle gases releasing. The residence time of geothermal water and the discovery of mantle gases in this region are firstly reported in this paper. These results are of significance to further study of active faults, earthquake risk and groundwater utilization in this region.

Key words: geochemistry, geothermal water, noble gases, mantle, Yanhuai basin

摘要: 对在延怀盆地采集的14组(次)地下热、冷水和气体样品的分析结果表明,地下热水主要是大气降水成因的,其循环深度为1600~3800m,深部最高温度为57~112℃,滞留时间为50~30320a;热水中的稀有气体为大气、壳源和幔源成因;热水与气体在地震前的异常变化与热水所处的断裂构造及其活动性密切相关。关于该区地下热水的年龄和幔源气体的发现为首次报道,它对该区的断裂活动性、地震危险性研究和热水合理利用具有重要的意义。

关键词: 地球化学, 热水, 同位素, 幔源气体, 延怀盆地

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