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计算云南及周边地区48个宽频地震台记录的8600个远震P波接收函数,并根据参考地球模型将接收函数从时间域转换到深度域.在转换深度550 km处,将1°×1°面元内的接收函数叠加成一道信号,共获得了沿纬度28°,27°,26°,25°,24°和23°N的6个共转换面元叠加剖面,其叠加深度在0~800 km之间.结果表明:(1)在26°N以北的地区,410和660 km间断面的平均深度分别为407~408和663~667 km,地幔过渡带的平均厚度处于255~259 km之间,过渡带的厚度接近全球平均厚度250 km;(2)在26°N以南的地区,410和660 km间断面的平均深度分别为412~426和675~703 km,地幔过渡带的平均厚度处于262~279 km之间,明显大于全球平均厚度250 km.云南地区410和660km间断面的加深显然与印度板块在缅甸弧下方的俯冲有关,然而,从云南地区地幔过渡带的结构来分析,本文认为印度板块沿缅甸弧向东俯冲主要发生在26°N以南地区.
8600 teleseismic P wave reception functions recorded by 48 broadband seismic stations in Yunnan and its surrounding areas were calculated and the receiver function was switched from the time domain to the depth domain according to the reference earth model.When the conversion depth was 550 km, The receiver functions in the bin are superposed into a single signal, and a total of six co-converted facet superposed profiles are obtained along the latitudes of 28 °, 27 °, 26 °, 25 °, 24 ° and 23 ° N, 800 km.The results show that: (1) In the area north of 26 ° N, the average depth of sections between 410 and 660 km is respectively 407 ~ 408 and 663 ~ 667 km, and the average thickness of the mantle transition zone is between 255 and 259 km and the thickness of the transitional zone is close to the global average thickness of 250 km. (2) In the area south of 26 ° N, the average depths of the sections 410 and 660 km are 412 ~ 426 and 675 ~ 703 km, respectively. The mantle transitional zone Is between 262 and 279 km, which is obviously larger than the global average thickness of 250 km. The deepening of the intercept between 410 km and 660 km in Yunnan Province is obviously related to the subduction of the Indian plate under the Myanmar arc. However, from the structure of the mantle transitional zone in Yunnan This paper argues that the subduction of the Indian plate along the Myanmar arc to the east mainly occurs in the area south of 26 ° N.