海原断裂带东南段土壤气体地球化学特征

摘要

The concentration of soil gas He, H2, N2, O2, CH4, C2H6, Rn, Hg and flux of soil gas He,H2 , CH4 , Rn, Hg were surveyed at four sites( Xiaokou , Bazhiyao , Caixiangpu and Xiaonanchuan) in the southeastern part of Haiyuan Fault. Soil-gas concentrations of more than 200 samples were obtained. The results show that the background values of N2/O2, Hg, Rn were 4. 2,50.4ng/m3and 5. 8k Bq/m3 ,respectively. The maximum concentrations of He and CH4 were 65. 3 and 537. 7ppm,respectively , at the end of the southeastern part of Haiyuan Fault. Furthermore, soil gas He and CH4 were intensively degassed. The maximum flux of He and CH4 in soil gas was 6. 9and 390mg m-2d-1 ,respectively. These may be caused by stress concentration at the end of the southeastern part of Haiyuan Fault. H2 and Rn in soil gas were powerful components as indicators of location of the southeastern part of Haiyuan Fault. The maximum concentrations of H2 and Rn in soil gas were 369. 7ppm and 38. 3k Bq/m3 near the middle of the southeastern part of Haiyuan Fault. The maximum fluxes of H2 and Rn in soil gas were 5. 5mg m-2d-1 and 828. 6m Bqm-2s-1 , respectively. These may be related with the intensive rupture of the middle of the southeastern part of Haiyuan Fault. The anomalies of Hg in soil gas at the fault were good reference indicators. The maximum flux of Hg in soil gas was 211. 2ng m-2h-1.%在海原断裂带东南段4个地点跨断层测量了土壤气中He、H2、N2、O2、CH4、C2 H6、Rn和Hg 的浓度及He、H2、CH4、Rn和Hg的通量.测量结果表明,N2/O2、Hg和Rn的背景值分别是4.2、50.4ng/m3和5.8k Bq/m3;土壤气中He和CH4在海原断裂带东南段端部有强烈异常,并且脱气强烈,通量分别达到6.9mg m-2d-1和390mg m-2d-1;土壤气中H2和Rn是指示海原断裂东南段破裂位置非常有利的气体组分,在靠断裂中部区域通琶达到最高,分别为5.5mg m-2d-1和828.6m Bqm-2s-1;土壤气中Hg在断裂带的异常可作为指示断裂破裂位置的参考信号,其通量最高达到211.2ng m-2h-1.