Abstract: Based on teleseimic data for the period of 2007 to 2010 acquired from the Three Gorges reservoir(Chongqing section)seismic network and Chongqing regional seismic network,we obtained the crustal thickness and Possion's ratio of the area through receiver function method.The results show that the crustal thickness ranges from 38.9km to 50.9km.Station CHK in northeastern Chongqing has the largest thickness which is about 50.9km;the thinnest crust is 38.9km under the station ROC in the west of Chongqing,and Poisson's ratio is about 0.27.The results show that the maximum Posson's ratio is beneath station JIZ in the east of the Chongqing section of Three Gorges Reservoir area,and the minimum Possion's ratio is beneath the station WUL,which is 0.228.In comparison with the Poisson medium(0.25),its maximum deviates up to 20.8%,and the minimum deviates by-8.80%.The Bouguer gravity anomaly often reflects subsurface density and crustal thickness variation.In this paper,the two agree with each other.The largest negative Bouguer anomaly is between CHK(50.9km)and WUX(49.7km),where the crust is the thickest.The smallest negative Bouguer anomaly is between ROC(38.9km)and YUM(41km),where the crust is the thinnest.

Key words: receiver function, Three Gorges Reservoir area, crustal structure, teleseismic data

摘要： 针对三峡库区重庆段地震监测台网和重庆区域台网2007年到2010年记录到的远震数据,利用接收函数方法,得到该区域的地壳厚度值及泊松比。结果显示27个地震台下方的地壳平均厚度为44.6km。最厚处为城口(CHK),达50.9km;最薄处为荣昌(ROC),仅38.9km,两者相差12km。研究区的地壳泊松比σ值约为0.27,三峡重庆库区东部奉节荆竹(JIZ)地壳泊松比高达0.302,武隆(WUL)地区的地壳泊松比较低,最低为0.228,两者相差0.074;研究区内泊松比的最大值偏离标准泊松体比值(0.25)20.8%以上,其最小值偏离标准泊松体比值-8.80%。布格重力异常反映了地下的密度与地壳厚度变化。文中得出的三峡库区重庆段地壳厚度变化与该区布格重力异常分析结果一致,重庆境内最小的负布格重力异常在地壳厚度最厚的城口—巫溪地区(厚49.7～50.9km),地壳最薄的荣昌—合川地区(厚38.9～41km)对应着渝西最大的负布格重力异常。

关键词: 接收函数, 三峡库区, 地壳结构, 远震数据