东昆仑活动断裂带西大滩段断层气(Rn,CO_2)的释放特征  

THE EXHALATION CHARACTERISTIC OF Rn AND CO_2 AT THE XIDATAN SEGMENT OF EAST KUNLUN ACTIVE FAULT ZONE

作　　者：李陈侠[1] 徐锡伟[1] F Perrier P Richon 陈桂华[1] Y Klinger J-M Nocquet C Romieu 张晓清[3] 常振广 

机构地区：[1]中国地震局地质研究所 [2]法国巴黎地球物理研究所,巴黎75005 [3]青海省地震局,西宁810001 [4]格尔木市地震局,格尔木816000

出　　处：《地震地质》2007年第4期905-909,共5页Seismology and Geology

基　　金：国家自然科学基金(40474037)资助

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。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^-1 also 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.

关 键 词：东昆仑活动断裂 西大滩段 断层气 氡气 CO2 

分 类 号：P315.2[天文地球—地震学]