地学前缘 ›› 2016, Vol. 23 ›› Issue (3): 140-150.DOI: 10.13745/j.esf.2016.03.018

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海原断裂带土壤气与地下水地球化学特征研究

孙小龙，王广才，邵志刚，司学芸   

  1. 1. 中国地震局 地壳应力研究所 地壳动力学重点实验室, 北京 100085
    2. 中国地质大学(北京), 北京 100083
    3. 中国地震局 地震预测研究所, 北京 100036
    4. 宁夏回族自治区地震局, 宁夏 银川 750001
  • 收稿日期:2015-12-26 修回日期:2016-01-26 出版日期:2016-05-15 发布日期:2016-05-15
  • 作者简介:孙小龙（1981—），男，博士研究生，副研究员，研究方向为地震地下流体。E-mail:xlsun04@163.com
  • 基金资助:

    国家自然科学基金项目(41502239)；中央级公益性科研院所基本科研业务专项(ZDJ201408)；地震行业科研专项项目(20140801903)；中国地震局震情跟踪定向工作任务(2015020301)

Geochemical characteristics of emergent gas and groundwater in Haiyuan fault zone

SUN Xiaolong，WANG Guangcai,SHAO Zhigang，SI Xueyun   

  1. 1. Key Laboratory of Crustal Dynamics, Institute of Crustal Dynamics, China Earthquake Administration, Beijing 100085, China
    2. China University of Geosciences(Beijing), Beijing 100083, China
    3. Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China
    4. Earthquake Administration of Ningxia Hui Autonomous Region, Yinchuan 750001, China
  • Received:2015-12-26 Revised:2016-01-26 Online:2016-05-15 Published:2016-05-15

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摘要：

选取海原断裂带曹洼(CW)、菜园(CY)、万家水(WJ)、水泉(SQ)、三塘(ST)、松山(SS)和安远(AY)7个测区进行土壤气测量与地下水地球化学检测，依据海原断裂带不同构造部位的土壤气浓度、水化学组分和同位素组成等，分析了海原断裂带的构造活动性分段特征。结果显示：研究区内土壤气Rn释放量较高的区域主要集中于ST、SQ测区，且断裂带中部区域气氡浓度相对较低；氦浓度及其同位素检测结果表明ST、SQ和CY测区土壤逸出气中含有幔源气体；泉水化学组分及氢氧同位素分析结果显示SQ和ST测区地下水与围岩介质之间的水岩相互作用程度较高、水岩反应平衡状态较高、地下水循环深度较大；泉水氚活度分析结果显示水泉（SQ）测区地下水补给区较远、水循环周期较长、新老水体的交换作用缓慢。综合分析认为，相比其他区段，海原断裂中西段（SQST）接近1920年8.5级地震破裂段，其断裂带闭锁程度较弱、与地壳深部的连通性较好，更有利于地下流体的扩散与运移。

关键词: 土壤气浓度, 水化学组分, 同位素组成, 海原断裂带

Abstract:

Seven measuring areas were selected and named Caowa(CW), Caiyuan(CY), Wanjia(WJ), Shuiquan(SQ), Santang(ST), Songshan(SS) and Anyuan(AY) respectively, in which soil gas was measured and geochemical composition in groundwater was detected. Characteristics of tectonic activity in Haiyuan fault zone was analyzed according to the soil gas concentration, chemical composition and isotopic composition in different area. Analysis results show that (1) those areas with higher soil gas concentration were ST and SQ along the fault strike；along the vertical direction of the fault, the concentration of Rn in soil gas was lower in the central position of fault than both sides; helium concentration and isotopic testing results show that mantlederived gas was mixed in the soil gas in ST, SQ and CY areas; that (2) according to results of the chemical composition and hydrogen isotope in spring water, we thought that there were more interaction and higher equilibrium state between groundwater and rock, and the depth of groundwater circulation were deeper in the areas of SQ and ST, compared to other areas in Haiyuan fault zone; that (3) the result of spring tritium activity showed that the groundwater recharge area in SQ area was far away, the water cycle period is longer, and the exchange action between old and new water is slow. Above all, the central and western areas of Haiyuan fault (SQST), which is close to the rupture zone of the 8.5 earthquake in 1920, has lower fault blocking degree and deeper connectivity with deep crust. So, different from other areas, those areas in central and western of Haiyuan fault has more conducive to subsurface fluid to diffuse towards the surface.

Key words: concentration of soil gas, water chemical composition, isotopic composition, Haiyuan fault zone

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