摘要
根据腾冲火山地热区实施的人工地震测深剖面资料 ,用有限差分反演和正向走时拟合方法确定了地壳二维 P波速度结构 .地壳模型显示 ,在腾冲的热海热田附近上地壳存在低速异常体 ,它与火山地热活动可能有关 .测线的二维地壳结构上显示出两条地壳断裂 :龙陵—瑞丽断裂和腾冲断裂 ,其中腾冲断裂可能切穿莫霍界面 .同时 ,根据远震波形资料反演腾冲热海热田地区的 S波速度结构 ,也显示出该地区上地壳存在 S波的低速异常 .本文从深部结构方面探讨腾冲火山的成因 .腾冲火山地热区地壳具有低 P波和 S波速度、低电阻率、高热流值和低 Q值 ,以及上地幔也具有低 P波速度的特点 .由此推测地壳内岩浆来源于上地幔 ,腾冲附近地区存在的上地壳低速度异常可与岩浆的分异作用相联系 .与地球上大多数的活动火山一样 ,腾冲火山位于移动板块之间的边界附近 ,属于“板块边界”
Based upon the deep seismic sounding profile conducted in the Tengchong volcano-geothermal area, a two-dimensional crustal P velocity structure is obtained by use of the finite-difference inversion and the forward travel-time fitting method. The crustal model shows that there is a low velocity abnormal body in upper crust in the Tengchong area, which may be related with volcano-geothermal activities, and two intracrustal faults (the Longling-Ruili fault and Tengchong fault) exist on the profile, where the Tengchong fault may cut through the Moho discontinuity. Meanwhile, in view of teleseismic data recorded by the mobile network, S-wave velocity structures beneath the Rehai-Retian region of the Tengchong area show the low S-wave velocity anomaly in upper crust. The authors discuss the genesis of Tengchong volcano based on the deep crustal structure. The crust of Tengchong volcano-geothermal area is characterized by low P-wave and S-wave velocity, low resistivity, high heat-flow value and low Q value. There is also a feature of low P-wave velocity in the upper mantle. For this information, it can be induced that the magma in the crust is derived from the upper mantle, and the low velocity abnormal in upper crust in the Tengchong area may be related to the differentiation of magma. Like many other active volcanoes on the earth, the Tengchong volcano is close to an active plate boundary and belongs to ″plate boundary″ volcano.
出处
《地震学报》
CSCD
北大核心
2002年第3期231-242,共12页
Acta Seismologica Sinica
基金
国家科技部攀登计划预选项目 ( 95 -专 -0 5 )"东亚大陆地球动力学研究"
中国地震局"九五"重点项目 ( 95 -1 1 -0 2 )
国家自然科学基金委 ( D0 4 0 7)
地震科学联合基金 ( 1 991 1 9)资助
关键词
腾冲火山区
地壳结构
人工地震测深
走时拟合
远震波形
Tengchong volcanic area
crustal structure
deep seismic sounding
travel-time fitting
teleseismic waveform
