瑞昌—武宁活动断裂带土壤气地球化学特征

Geochemical Characteristics of the Soil Gas in the Ruichang-Wuning Active Fault Zone

对瑞昌—武宁断裂带瑞昌段进行了跨断层气体地球化学流动测量,测定了断裂带土壤气Rn和CO_(2)浓度,分析了该断裂带的气体地球化学特征,结合赣南地区b值讨论了断裂带气体分布特征与构造活动性的可能关系。结果显示:桂林桥、伍家畈土壤气Rn和CO_(2)浓度均表现出强正相关特征,说明断裂带Rn是基于CO_(2)载气运移至地表浅层。Rn和CO_(2)浓度峰值均出现在断裂带附近,桂林桥测线中部土壤气浓度明显高于两端,而伍家畈测线中部与两端浓度平均值相对接近,这种浓度空间释放特征的差异可能主要是震后断裂带愈合程度不一所致。两条测线土壤气Rn浓度水平较高,b值扫描发现研究区应力呈增强趋势,表明断裂带活动性较强,可能意示土壤气Rn浓度与断裂带的活动性有着密切的联系。

Based on the distribution of the concentration of the soil gas Rn and CO_(2)in the Ruichang-Wuning Active Fault Zone obtained by cross-fault observation in the field,we analyze the geochemical characteristics of Rn and CO_(2)in the Fault Zone,and reveal the relationship between the geochemical characteristics of the two soil gases and the Fault Zone.The results show that the strong correlation of Rn and CO_(2)concentration indicates that in the Fault Zone Rn migrates to the shallow surface along with CO_(2).The peak concentrations of Rn and CO_(2)soil appear near the Fault Zone.The concentration of Rn and CO_(2)in the middle of the Guilinqiao survery line is obviously higher than that at both ends of the line,while the average concentrations in the middle and both ends of the Wujiafan survey line are relatively close.The concentrations differ spatially mainly because of the different degrees of fault healing after the earthquake.The concentration of Rn in both the two survey lines is high,and the b-value scanning shows that the stress in the study area is increasing,indicating that the Fault activity is strong.This suggests that the concentration of Rn is closely related to the activity of the Ruichang-Wuning Active Fault Zone.