庐江地热温泉1号井水氡远场强震震后效应及机理分析

The post seismic effect of far-field strong earthquakes of water radon and its mechanism analysis for L01 well of Lujiang geothermal hot spring

  • 摘要: 庐江地热温泉1号井位于郯庐断裂带上,水氡测项出现远场强震震后效应现象。通过收集郯庐断裂带安徽段沿线9个主要地震观测井、地热温泉井和地表水样品,检测水样的阴阳离子和同位素,对比分析庐江地热温泉井地下水的来源深度,研究其震后效应及机理。结果表明:地热温泉井水化学类型复杂,温泉井L01,L03,L07和SC井的Cl浓度较高、\rmHCO_3^ - /Cl\rmSO_4^2 - /Cl浓度比值较低,体现出地下热水径流交替作用强烈,L11井有较大比例的冷水混入,L03井有较浅的热源埋深。庐江地热温泉井和舒城井的水样具有明显的壳源特征,L01井和SC井地表出露温度最高、L01井循环深度最深,由Na-K-Mg三角图估算L01井循环深度达12 km,反映出较多的深部构造活动信息。分析认为庐江地热温泉1号井以垂向补给方式为主,具有较深的热源埋深,远场强震的地震波引起较弱的区域构造活动,改变了深部热源的补给量,从而引起水氡上升的同震响应现象。

     

    Abstract: The Lujiang geothermal hot spring well No.1 is located on the Tanlu fault zone, where hydro-radon response to teleseism were observed. Nine geochemistry samples from the observation wells, geothermal hot spring wells and surface water along Anhui section of Tanlu fault zone were collected. The potential triggering mechanism was studied by analyzing the anion and isotope contents, as well as the source depth of the retrieved samples. The results show that the hydrochemical type is complex. The concentrations of Cl within L01, L03, L07 and SC wells are high, whereas the concentration ratios of \rmHCO_3^ -/ Cl and \rmSO_4^2 - /Cl are low, implying a strong interaction between the surface water and underground hot water, The L11 well has a large proportion of mixed cold water, and the depth of a heat source is low for L03. Water samples from Lujiang and Shucheng hot spring wells might come from crust, having moreinformation of deep tectonic activities, since the L01 and SC have the highest surface temperature and circulation depth of L01 is the deepest. The estimated depth is 12 km by calculating the Na-K-Mg concentrations. In addition, the results indicate that Lujiang geothermal hot spring well No.1 is dominated by vertical recharge and has a deeper heat source. Seismic waves could have caused weak regional tectonic activities, which change the supply of deep heat source, and cause the high hydro-radon concentrations observed.

     

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