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

摘要： 通过在东昆仑活动断裂带西大滩段进行断层气测试,首次获取了该断裂带中Rn和CO₂的释放量。在2004年开挖的2～3m深的探槽内,氡浓度可达20732Bq·m^-3,氡发射率可达433mBq·m^-2·s^-1,远高于在地表的氡浓度505～2380Bq·m^-3与氡发射率7～28.19mBq·m^-2·s^-1(地表氡发射率均值为14.7mBq·m^-2·s^-1,与世界平均值相当)。从而我们推断该断裂具有从上部第四系覆盖物到深部花岗岩之间的良好连通性。在地表CO₂的析出率平均值为18.9g.m^-2·d^-1,与通常的背景值相当,在探槽中和距离断层1km的地方没有明显的空间变化,但是在断层北侧3km处的一个近乎直立的千枚岩小山上,CO₂的析出率却很高,为421g·m^-2·d^-1,同时该处氡的发射率也高,达503mBq·m^-2·s^-1,因此,有必要在该断裂附近进行长期监测。

关键词: 东昆仑活动断裂, 西大滩段, 断层气, 氡气, CO₂