腾冲火山是中国规模较大的新生代火山群之一,壳内岩浆活动情况一直广受关注。为探讨腾冲火山区的深部构造特征,基于腾冲火山区(24°40'N～25°30'N,98°15'E～98°45'E)11个固定台站和1个喜马拉雅Ⅰ期流动台站记录的600多个远震波形三分量数据,提取时间域P波接收函数,利用接收函数Pms波分裂到时方差最小法计算腾冲火山区地壳各向异性参数。引入去除混响滤波器消除沉积层对接收函数的影响,采用适用于地壳各向异性介质的接收函数H-κ-c 方法,计算地壳厚度、波速比和泊松比。结果显示,腾冲火山区地壳各向异性慢波延时在0.1～0.5s之间,平均延时为0.27s,该区的地壳各向异性可能主要来自中上地壳,各台站快波偏振方向以NE-SW向、近N-S向为主,与主要的断层、最大压应力方向一致。地壳厚度在 35.5～39.5km 之间,波速比在1.71～1.9之间,泊松比在0.24～0.308之间,该区具有高泊松比值特征。结合前人的研究结果,认为地壳泊松比最大的两个区域,即腾冲—沙坝台一带、马站—民振台一带下方可能存在岩浆囊,地热活动强烈的热海和热水塘地区,热量可能横向来自其他区域,热海台附近的热能可能来源于其东侧,热水塘台附近的热能可能来源于其东北侧和西侧。腾冲地区不同台站地壳平均泊松比的差异主要受壳内岩浆囊和火山喷发活动的影响。

Tengchong volcano area,as one of the large Cenozoic volcanic groups in China,has drawn significant attention due to its crustal magmatic activity. To investigate the deep structural characteristics of the Tengchong volcanic region,we analyzed over 600 three-component seismic datasets from 11 permanent and one temporary station as part of ChinArray Phase I,covering the coordinates(24°40'～25°30'N,98°15'～98°45'E). The time-domain P-wave receiver function was extracted,and crustal anisotropy parameters were calculated using the Pms wave split time variance minimization method. To mitigate the impact of sedimentary layers on the receiver function,a reverberation removal filter was applied. Using the H-κ-c method,which is effective for anisotropic crustal media,we calculated crustal thickness, v_P/v_S ratios,and Poisson ratio. The results indicate that the anisotropic slow wave delay ranges from 0.1s to 0.5s seconds,with an average delay of 0.27s. The crustal anisotropy in the Tengchong volcanic region likely originates from the middle to upper crust. The polarization direction of the fast wave predominantly aligns with the NE-SW and N-S directions,corresponding to the orientation of the major faults and maximum compressive stress in the region. Crustal thickness varies between 35.5 and 39.5km, v_P/v_S ratios range from 1.71 to 1.9,and Poisson ratio lies between 0.24 and 0.308. Notably,the region exhibits high Poisson ratio values,suggesting possible magmatic chambers beneath the TNC-SBT and MZT-MIZ areas,which show the highest Poisson ratios. For regions with significant geothermal activity,such as RHT and RST,the thermal energy appears to be sourced horizontally from adjacent areas-east of RHT and northeast and west of RST. The variations in Poisson ratio across different stations in the Tengchong volcanic region are likely influenced by the presence of magma chambers in the crust and ongoing volcanic activity. These findings provide important insights into the complex magmatic processes and the deep structure of the Tengchong volcanic region.

P315

中国地震局“三结合”课题(3JH-202301034)和云南省地震科技创新团队(CXTD202412)共同资助