关键词: 东昆仑活动断裂, 西大滩段, 断层气, 氡气, CO₂

Abstract: It's the first time to observe the exhalation flux of soil Rn and CO₂ in Xidatan segment of East Kunlun active fault in September,2006 and first-hand data of the Rn and CO₂ in this fault were obtained.A significant Rn flux,reaching up to 433 mBq·m^-2·s^-1 and the concentration of Rn ranging from 505 up to 2380 Bq·m^-3 was observed in the excavated trench with 2～3 meters deep across the fault.On the surface,the Rn flux ranges from 7 to 28.19mBq·m^-2·s^-1,with the mean value of 14.7 mBq·m^-2·s^-1,similar to the world average.The CO₂ flux on the surface with an average value of 18.9g·m^-2·s^-1also remains similar to regular background values.It shows no systematic spatial variation up to a distance of 1.2 km from the fault and no clear change in the trench.But a high CO₂ flux of 421g·m^-2·s^-1 is observed at phyllite outcrops on a hill 3km north of the fault.A large Rn flux,503 mBq·m^-2·s^-1,is observed at the point where the maximal CO₂ flux is observed.These results indicate the advective pore gas transport from the subsurface to the atmosphere in the vicinity of the East Kunlun active fault zone.

Key words: East Kunlun active fault zone, Xidatan segment, fault gas, Rn, CO₂