怀安盆地北缘断裂东段土壤气体地球化学特征

活动断裂带的土壤气体地球化学测量在活动断裂危险性评价方面起着重要作用。 本文讨论了怀安盆地北缘断裂东段的土壤气体地球化学特征及其构造意义。 我们于2012年7月和2013年6月在怀安盆地北缘断裂东段的羊窖沟以及张家窑两地现场测量了土壤气体组分的浓度和通量。 测量结果表明: ① 断裂带土壤气H₂、 Rn、 CO₂和Hg浓度空间分布曲线呈现双峰模式, 且断裂下盘土壤气的Rn、 CO₂和Hg浓度较上盘的高; H₂、 Rn、 CO₂和Hg浓度平均值分别是4.61 ppm、 4.81 k Bqm^-3、 0.38%和9 ngm^-3; 土壤气Rn和CO₂的通量平均值分别是6718 Bqm^-2d^-1和49.83 gm^-2d^-1; ② 土壤气Rn和CO₂在两个测区脱气强烈, 羊窖沟地区土壤气CO₂、 Rn和Hg浓度平均值以及土壤气Rn和CO₂通量值较张家窑地区高。 这些结果可能是两个测区断裂活动性差异引起的。

Geochemical Characteristics of Soil Gas in the Eastern Segment of the North Margin Fault of the Huaian Basin,Hebei Province

Soil gas measurement over active fault has an important significance to assess the risk of active faults. In this paper, geochemical characteristics and tectonic significance of geochemical characteristics in the eastern segment of the north margin fault in the Huaian Basin have been discussed. Concentration of Rn, CO₂, Hg and H₂ and flux of Rn and CO₂ were measured twice in the field at two sites (Zhangjiayao and Yangjiaogou) across the eastern segment of the north margin fault in the Huaian Basin in July 2012 and June 2013, respectively.The measured results indicate that: ① The average concentration of H₂, Rn, CO₂ and Hg were 4.61 ppm ,4.81 k Bq/m³ , 0.38% and 9 ng/m³, respectively. The average flux of CO₂ and Rn are 11664 Bqm^-2d^-1 and 49.83 gm^-2d^-1, respectively. The concentration distribution curves of H₂, Rn, CO₂, and Hg in soil gas are characterized by bimodal pattern, the concentration of soil gas in the footwall is higher than that in the hanging wall. ② Soil gas Rn and CO₂ are degassed intensively in the eastern segment of the north margin fault of the Huaian Basin. Average concentration value of Rn, CO₂ and Hg and flux of Rn and CO₂ in yangjiaogou profile are higher than that in zhangjiayao profiles. The results might be caused by the fault activity difference of the two sites.