陇县—宝鸡断裂带CO_(2)气体地球化学特征及成因  

Geochemical Characteristics and Genesis of Soil Gas CO_(2) in the Longxian-Baoji Fault Zone

作　　者：刘洁 李营[2] 陈志[2] 王新[1] 赵小茂[1] 冯希杰[1] 王景丽 LIU Jie;LI Ying;CHEN Zhi;WANG Xin;ZHAO Xiaomao;FENG Xijie;WANG Jingli(Shaanxi Earthquake Agency,Xi an 710068,Shaanxi,China;Institute of Earthquake Forecasting and Key Laboratory of Earthquake Prediction,China Earthquake Administration,Beijing 100036,China)

机构地区：[1]陕西省地震局,陕西西安710068 [2]中国地震局地震预测研究所中国地震局地震预测重点实验室,北京100036

出　　处：《地震研究》2022年第2期217-228,共12页Journal of Seismological Research

基　　金：中国地震局地震预测开放基金(2021EFOF03);中国地震局震情跟踪定向工作任务(2022010502、2021010309)联合资助;陕西省自然科学基金(2022JQ-254)。

摘　　要：陇县—宝鸡断裂带位于青藏块体东北缘,属于鄂尔多斯块体西南缘弧形断裂束的最南段。为对比分析该断裂带的分段活动性强弱特征,利用断裂带逸出气CO_(2)的地球化学特征进行反演。布设6条跨断层土壤气CO_(2)测线,进行2期测量,共计获取150个土壤气CO_(2)组分浓度,计算了气体的相对活动强度;收集了60件CO_(2)气体样品,测试了其碳同位素组成。结果表明:岐山—马召断裂的气体活动强度(1.56~2.70)比固关—虢镇断裂的气体活动强度(1.73~1.75)大,且岐山—马召断裂上的CO_(2)碳同位素组成比固关—虢镇断裂上的CO_(2)更靠近深部物质端元。位于南段的岐山—马召断裂的地下构造连通性较好,断裂闭锁程度较低,而位于北段的固关—虢镇断裂气体活动性较弱,闭锁程度较高,未来发生地震的危险性较高。The Longxian-Baoji Fault Zone is located in the northeast edge of the Qinghai-Tibet Block and belongs to the southernmost segment of the arc fault belt in the southwest edge of the Ordos Block.To compare the activity of the Qishan-Mazhao Fault in the south of the Longxian-Baoji Fault Zone with the activty of the Guguan-Guozhen Fault in the north,we study the geochemical features of the soil gas CO_(2)in the faults.Six survey profiles for surveying CO_(2)are deployed across the two faults and two periods of observation are carried out.We obtain 150 observed values of CO_(2)component concentrations.In addition,we collect 60 CO_(2)samples for stable carbon isotopic composition measurements.We find that the intensity(1.56-2.70)of CO_(2)activity in the Qishan-Mazhao Fault is greater than that(1.73-1.75)in the Guguan-Guozhen Fault.And the source of the CO_(2)in the Qishan-Mazhao Fault is closer to the end member of the deep materials.This suggests that the connectivity of the underground structures of the Qishan-Mazhao Fault is better and the fault’s locking degree is lower.Meanwhile,the gas activity in the Guguan-Guozhen Fault is weaker and the fault’s locking degree is higher.Thus,the earthquake risk in this fault zone is higher.

关 键 词：土壤气CO_(2)气体活动强度 碳稳定同位素 断层活动性 

分 类 号：P315.724[天文地球—地震学]