基于接收函数方法研究川滇块体东边界的地壳厚度和泊松比  

Crustal Thickness and Poisson′s Ratio beneath the East Boundary of Sichuan-Yunnan Block from Receiver Functions

作　　者：张宝文[1] 赵翠萍[1] 周连庆[1] 

机构地区：[1]中国地震局地震预测研究所,北京100036

出　　处：《地震》2015年第1期55-64,共10页Earthquake

基　　金：南北地震带中部潜在强震危险区的监测和研究(I2011IES010104)

摘　　要：本文使用沿川滇块体东边界主要断裂带（安宁河、则木河、小江断裂带）布设的37个临时台站和四川区域台网14个固定台站记录的远震波形资料,用时间域迭代反褶积方法提取接收函数,采用接收函数H-κ反演方法得到了30个台站下方的地壳厚度和泊松比.研究结果表明,川滇块体东边界的地壳厚度表现为自西向东由60 km左右向华南块体（35 km左右）逐渐减薄的过渡带特征：以安宁河大凉山断裂带为界,以西地壳厚度平均在54 km左右,以东作为华南块体与川滇块体的交界前缘,地壳厚度在42～48 km之间.以小江断裂带与则木河断裂带交汇处为界,其南北两侧的地壳岩性和组分差异明显.小江断裂带北段泊松比值在0.20～0.27之间,表明其地壳物质组分主要为中基性岩石.而以北的安宁河、则木河及马边—盐津断裂带的泊松比值大多位于0.27～0.32之间.安宁河—则木河断裂带附近多数台站的泊松比值＞0.30,可能是部分熔融造成的.Teleseismic waveform data from 38 temporary stations along the main fault zone （Anninghe,Zemuhe,Xiaojiang fault zone） of the eastern boundary of the Sichuan-Yunnan block and 14 permanent stations in Sichuan regional seismic network were used to compute crustal thickness and velocity ratio （Vp/Vs） of 30 stations by time domain iterative deconvolution extracting receiver function and the H-inversion method.The results show that crustal thickness becomes thinner gradually from 60 km from west to east to that 35 km in South China block.In the west of Anninghe-Daliangshan fault zone,the average crust thickness is about 54 km,while in the east,as the front junction between South China block and Sichuan-Yunnan block,the average crust thickness is 42～48 km.Crust lithology and component obviously differ between Xiaojiang fault and that to its nouthern region.The poisson＇s ratio between 0.20 and 0.27 at the northern segment of Xiaojiang fault zone indicates that its crust is mainly composed of basic rock.Nevertheless,the poisson＇s ratio that is mostly lies between 0.27 and 0.32 at the Anninghe,Zemuhe and Mabian-Yanjin fault zones.Below most of the stations on Anninghe-Zemuhe fault zone,there is an ultra high Poisson＇s ratio that greater than 0.30,which is inferred as evidence of local partial melt.

关 键 词：地壳厚度 泊松比 川滇块体东边界 接收函数 

分 类 号：P315.7[天文地球—地震学]