| 吉兰泰断陷盆地周缘断裂带气体释放及其对断层活动性的指示意义 |
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| 引用本文： | 刘兆飞,李营,陈志,崔月菊,路畅,杨江,赵元鑫.吉兰泰断陷盆地周缘断裂带气体释放及其对断层活动性的指示意义[J].地震学报,2019,41(5):613-632. |
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| 作者姓名： | 刘兆飞 李营 陈志 崔月菊 路畅 杨江 赵元鑫 |
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| 作者单位： | 中国北京 100036 中国地震局地震预测研究所;中国北京 100036 中国地震局地震预测重点实验室 |
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| 基金项目： | 中国地震局地震预测研究所基本科研业务费专项（2016IES0101，2016IES0102）和国家重点研发项目（2018YFC1503602）共同资助 |
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| 摘 要： | 为了研究吉兰泰断陷盆地周缘断裂带气体排放及其对断层活动性的指示意义，在盆地周缘4条活动断裂上布设了5条土壤气测量剖面和1条电磁测量剖面，观测了土壤气中Rn，Hg和CO2的浓度、释放通量和地电阻率，对各测量剖面进行了土壤化学组分分析，计算得到了断层活动性相对指数KQ。研究结果显示:土壤气体CO2和Rn受渗透性较低的粉砂土阻挡，主要沿结构破碎的断层上盘逃逸，并形成浓度高峰；吉兰泰盆地南缘土壤气Rn，Hg和CO2的浓度和释放通量最高，可能与盆地西南缘花岗岩中U和Ra的运移以及盆地南缘碳酸盐岩的分解有一定的关系。各测量剖面的断层活动性相对指数KQ值的变化特征表明，正断层和逆断层的KQ值大于走滑断层，且巴彦乌拉山山前断裂上的KQ值最高，揭示其活动性最强，有可能是地震发生的潜在危险区。
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| 关 键 词： | 吉兰泰断陷盆地 断裂带 土壤气 地球化学 释放通量 断层活动性 |
| 收稿时间： | 2019-02-15 |
Gas emission from active fault zones around the Jilantai faulted depression basin and its implications for fault activities |
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| Institution: | 1.Institute of Earthquake Forecasting，China Earthquake Administration，Beijing 100036，China2.Key Laboratory of Earthquake Prediction，China Earthquake Administration，Beijing 100036，China |
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| Abstract: | Soil gases from fault zones are good indicators of tectonic and seismic activities, to which many seismologists and geochemists have been paid much attention. Five measuring sections for soil gas and one for earth resistivity were designed on the four active faults around the Jilantai basin, northwestern China. The data of earth resistivity, concentration and flux of soil gases Rn, Hg and CO2 were attained, and the chemical compositions of soil were analyzed in all sections and the relative index KQ of fault activity was calculated. All the results showed that soil gases CO2 and Rn were blocked by sandy soil layers with low permeability and escaped along the hanging wall of the faults with broken structures, easily forming concentration peaks. High concentrations and fluxes of Rn, Hg and CO2 were distributed in the southern margin of the Jilantai basin, which might be related to the migration of U and Ra in granites in southwestern margin of the basin and the decomposition of local carbonate rocks in south margin of the basin. The variation characteristics of relative index KQ of fault activity in each section indicated normal and reverse faults with higher KQ values than strike-slip faults. The maximum KQ value was observed in the piedmont fault of Bayanwula mountains, probably indicating that this fault is of the strongest activity and is also a potential area of high seismic hazards. |
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