摘要
通过对大凉山断裂带中段普雄河断裂、甘洛-汉源断裂、洪溪-美姑断裂进行野外的氡气测量,分析讨论各断裂带的氡气特征、相对活动性强弱以及与现代地震的发震关系。研究结果表明:(1)3条断裂均表现出氡气多峰异常的特征,指示其为多条断层或隐伏断层组成的构造带。其中,普雄河断裂带由6条断层组成、甘洛-汉源断裂带由3条主要断层组成、洪溪-美姑断裂由3条断层组成;与野外及地形地貌有着较好的对应性;(2)3条断裂带内各断层氡气最大峰背比介于3.89～16.30;异常平均峰背比介于3.11～7.09;异常平均值/异常下限值介于1.82～4.15,相对活动性判别表明,虽然普雄河断裂带最宽,次级断层最为发育,但甘洛-汉源断裂的活动性却更强,表明中生代以来的控盆作用更明显;(3)与区内已有发震断层资料对比总结出,当断层氡气异常平均峰背比介于4.67～5.12、异常平均值与异常下限值比介于2.73～3.00时,断层具有发生5.0级中强震的能力。而甘洛-汉源断裂带中侯波日哈断层、瓦依拉达断层氡气异常平均峰背比介于5.52～7.09、异常平均值与异常下限值比介于3.23～4.15,因此具有发生大于5.0级中强震的可能,也为监测区内活动断层的地震活动性提供了新的资料。
On the basis of field investigation,the radon gas in Puxiong River Fault,GanluoHanyuan Fault and Hongxi-Meigu Fault in the middle segment of Dliangshan Fault Belt is measured and the chatercteristics of radon gas,relative mobility and relation with the seismogeny of the 3 faults are discussed.It shows that the three faults have multiple peak anomalies of radon gas,indicating that they are a fault system consisting of multiple faults and buried faults.The Puxiong River Fracture Belt consists of six faults,both the Ganluo-Hanyuan Fracture Belt and the Hongxi-Meigu Fracture Belt consist of three major faults.All of the faults are consistent with the field topographic and geomorphic features.The radon gas ratios of peak value to background value of the three fracture belts are in the range of 3.89~16.30,the anomalous average ratios of peak to ground values are 3.11~7.09,and the average anomaly value/lower limit anomaly values are 1.82~4.15.Comparison of relative mobility of the faults indicates that the Ganluo-Hanyuan Fracture Belt shows more mobile than the Puxiong River Fracture Belt though the latter has a wider fault zone and has more secondary faults.On the basis of summarization of seismogenic faults in the area,it is proposed that when the average peak-to-background ratios of radon gas anomalies in a fault range from 4.67 to 5.12,and the ratios of mean value and lower limit value are 2.73~3.00,a magnitude of 5.0 medium-strong earthquake is likely to happen.The field investigation reveals that the average peak-to-background ratios of radon gas anomalies in Houboriha Fault and Wayilada Fault of the Ganluo-Hanyuan Fault Belt are in the range of 5.52~7.09,and the ratios of mean value and lower limit value are 3.23~4.15.Therefore,these 2 faults have a potential for occurrence of a magnitude of 5.0 medium-strong earthquakes.The radon gas measurement provides information for monitoring the seismicity of active faults in the middle Daliangshan Fault Belt.
作者
文龙
巴金
朱兵
李小平
金灿海
WEN Long;BA Jin;ZHU Bing;LI Xiaoping;JIN Canhai(Sichuan Institute of Geological Survey , Chengdu 610081, China;Chengdu Center of Geological Survey , China Geological Survey , Chengdu 610081,China)
出处
《矿物岩石》
CAS
CSCD
北大核心
2018年第4期56-65,共10页
Mineralogy and Petrology
基金
中国地质调查局地质调查项目<乌蒙山区地质矿产综合调查>(编号:121201010000150002)
关键词
川滇块体
大凉山断裂带
氡气
发震断层
Sichuan - Yunnan Block
Daliangshan Fault Belt
radon gas
seismic fault
