西秦岭北缘断裂带深部气体地球化学特征与断层形变空间分布相关性研究

Study on Correlation between Geochemical Features of Deep Gas and Fault Deformation Distribution in Northern Margin Fault Zone of West Qinling

断裂带气体地球化学特征与形变特征之间的相关关系是建立具有物理预报思路断层气流动观测网络布设的重要课题。选择有大量温泉出露点且形变较剧烈的西秦岭北缘断裂带为研究对象,对跨断层形变测量场地进行断层土壤气剖面重合布设及现场测量,重点研究断层气分段性特征与断层形变、地震活动性特征耦合关系,探讨利用多种方法开展断裂带强震危险性分析的可能性。结果表明:断裂带土壤气地球化学特征和断层水准形变特征的分布具有良好相关关系,二者对比结果同时显示出西秦岭北缘断裂带中东段——武山段断层活动性相对活跃,渭源—漳县段次之,天水段断层相对闭锁的特征;且武山和甘谷走滑拉分区因流体活动的影响以中小地震活动为主,天水段和漳县段西部及与武山段交汇的盘古川地区,流体活动较弱,应变速率较小,存在孕育强震的可能。

In this study,we took the northern margin fault zone of West Qinling as the study area,which has many hot-spring dew points and severe deformations.We established the fault soil gas profile overlap and conducted field measurement in the cross-fault deformation area to determine the coupling relationship between fault gas segmental characteristics,fault deformation,and seismic activity.We used a variety of methods to evaluate their usefulness in fault earthquake hazard analysis.The results show that there is a good correlation between the geochemical features of soil gas and the distribution of fault deformation characteristics.The comparison results indicate that fault activity is relatively more active in the Wushan segment than in the Weiyuan—Zhangxian segment,and that the Tianshui segment is relatively locked.In addition,due to the active influence of fluid activity,most of the shocks in the Wushan and Gangu strike-slip pull-apart partitions generate medium to small earthquakes.In contrast,strong earthquakes are likely in the west of the Tianshui and Zhangxian segment,and in the Panguchuan region,as the fluid activity and strain rate are weak in these areas.These results can contribute to a theoretical basis for developing a fault gas flow observation network layout with the potential for physical prediction.