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Title:: Geochemical Characteristics of Soil Gas(Rn,CO₂)in the Ruichang Basin,Jiangxi Province

作者:: 赵影¹; 2; 陈志³; 吕坚¹; 2; 肖孟仁¹; 2; 胡婷霞¹; 2; 刘兆飞³; 何鸿毅³; 罗齐彬⁴; 王成楠⁵; 胡旭东⁴; (1.江西九江扬子块体东部地球动力学野外科学观测研究站,江西九江 332006; 2.江西省地震局,江西南昌 330096; 3.中国地震局地震预测重点实验室,中国地震局地震预测研究所,北京 100036; 4.江西省防震减灾与工程地质灾害探测工程研究中心,江西南昌 330013; 5.江西省地质环境调查研究院,江西南昌 330096)

Author(s):: ZHAO Ying¹; 2; CHEN Zhi³; LYU Jian¹; 2; XIAO Mengren¹; 2; HU Tingxia¹; 2; LIU Zhaofei³; HE Hongyi³; LUO Qibin⁴; WANG Chengnan⁵; HU Xudong⁴; (1.Observatory for Geodynamic of the East Yangtze Block in Jiujiang,Jiangxi Province,Jiujiang 332006,Jiangxi,China)(2.Jiangxi Earthquake Agency,Nanchang 330096,Jiangxi,China)(3.CEA Key Laboratory of Earthquake Forecasting,Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China)(4.Engineering Research Center for Seismic Disaster Prevention and Engineering Geological Disaster Detection of Jiangxi Province,Nanchang 330013,Jiangxi,China)(5.Geological Survey of Jiangxi Province,Nanchang 330096,Jiangxi,China)

Keywords:: the Jiujiang-Ruichang earthquake; soil gas; geochemistry; Rn; CO₂

摘要:: 通过野外流动观测,获取了2005年江西九江—瑞昌M_S5.7地震震中所处的瑞昌盆地139个测点的土壤气体Rn和CO₂浓度数据。地质统计分析显示,瑞昌盆地Rn、CO₂背景浓度分别为7.33 kBq/m³和0.50%,异常界浓度分别为27.50 kBq/m³和6.00%。Rn和CO₂浓度空间分布结果表明:Rn浓度异常呈NE向优势分布特征,可能反应了当前赣北区域的构造应力场状态; Rn和CO₂浓度的同步异常带与刘家—范家铺—城门山断裂带、瑞昌盆地东南缘断裂重合较好; Rn、CO₂浓度异常分布对比分析显示瑞昌盆地东南方向的断裂活动性较西北方向的断裂活动性强,推测瑞昌盆地内相关地震活动与盆地东南方向断裂构造关联性较大。

Abstract:: The concentration of the soil gases Rn and CO₂ at 139 sites within 140 km² in the Ruichang Basin,in which the epicenter of the Jiujiang-Ruichang M_S5.7 earthquake on November 26,2005 is located,is measured.The geostatistical analysis shows that the background values of the concentration of Rn and CO₂ are 7 330 Bq/m³,0.50%,and the abnormal boundary values of the concentration are 27 500 Bq/m³,6.00%,respectively.The anomalous values of Rn are distributed in NE direction,which is consistent with the current state of tectonic stress field in northern Jiangxi.The zone which has synchronous high-value anomaly of Rn and CO₂ is in line with the Ruichang-basin southeast marginal fault and the Liujia-Fanjiapu-Chengmenshan marginal fault.The distribution of abnormal concentration of Rn and CO₂ shows that the fault activity in the southeast direction of the Ruichang Basin is stronger than that in the northwest direction.The earthquake activity in the Ruichang Basin may be closely related to the fault structure in the southeast direction of the Basin.