地震研究

壳幔过渡带是地壳与地幔物质和能量的交换场所,其结构特征与该区的深部过程和构造演化密切相关。提取腾冲火山区31个地震台站下方的接收函数H-κ叠加获得的地壳厚度随频率变化特征和接收函数的Ps/P、PpPs/P振幅比,发现盈江断裂北部的黑空山—燃灯寺和南侧沙坝台区域具有比周边区域更低的振幅比,约有2 km地壳厚度差异。将该观测结果与前人获得的这两个区域相对薄的地壳厚度与高的V_P/V_S比值相结合,表明黑空山—燃灯寺和沙坝台区域具有厚的壳幔过渡带,推测其是地幔物质涌入地壳的通道。结合前人获得的该区上、中、下地壳都存在大片低速体的特征,推测来自地幔的岩浆很可能沿着腾冲火山区黑空山—燃灯寺和沙坝台这两个区域上涌到地壳,并依次在下、中和上地壳富集和横向展布,最终沿多个通道喷出地表。

The Crust-Mantle transition zone serves as a critical interface for the exchange of material and energy between the Earth's Crust and Mantle,closely tied to deep processes and tectonic evolution in the region.This study extracts characteristics of crustal thickness variation with frequency from receiver functions H-κ stacking beneath 31 seismic stations in the Tengchong volcanic area,as well as the Ps/P and PpPs/P amplitude ratios of the receiver functions.It reveals that the Heikongshan-Randengsi area to the north of the Yingjiang fault and the Shabatai area to the south exhibit lower amplitude ratios and a crustal thickness difference of approximately 2 km compared to surrounding regions.Combining these observations with previous findings of relatively thin Crust and high V_P/V_S ratios in these two areas suggests a thick Crust-Mantle transition zone,hypothesized as conduits for Mantle material into the Crust.Building on previous findings of extensive low-velocity features in the upper,middle,and lower Crust of the region,this paper postulates that magma from the Mantle likely ascends through the Crust along the Tengchong volcanic area,specifically through the regions of Heikongshan-Randengsi and Shabatai.Subsequently,it enriches and laterally spreads within the lower,middle,and upper Crust,eventually erupting onto the surface through multiple channels.

引言
1 理论分析与数据来源
2 结果与讨论
3 结论

图1 不同类型的壳幔过渡带地壳模型(a)及对应的不同高斯系数下的理论接收函数(b,c)<br/>Fig.1 Different Crust-Mantle transition zone models(a)and corresponding theoretical receive functions with different Gaussian coefficients(b,c)

图1 不同类型的壳幔过渡带地壳模型(a)及对应的不同高斯系数下的理论接收函数(b,c)
Fig.1 Different Crust-Mantle transition zone models(a)and corresponding theoretical receive functions with different Gaussian coefficients(b,c)

表1 壳幔过渡带对接收函数H-κ叠加结果和震相振幅比的影响<br/>Tab.1 Impact of the Crust-Mantle transition zone on the receiver functions H-κ stacking results and phase amplitude ratios

表1 壳幔过渡带对接收函数H-κ叠加结果和震相振幅比的影响
Tab.1 Impact of the Crust-Mantle transition zone on the receiver functions H-κ stacking results and phase amplitude ratios

图2 腾冲火山区地震台站、火山及地震分布<br/>Fig.2 Seismic stations,volcanoes and the earthquake distribution in Tengchong volcanic area

图2 腾冲火山区地震台站、火山及地震分布
Fig.2 Seismic stations,volcanoes and the earthquake distribution in Tengchong volcanic area

图3 本文用到的远震事件的震中分布(a)和不同高斯系数下单台接收函数叠加后的波形(b)<br/>Fig.3 Epicenter distribution of teleseismic events used in this study(a)and stacked receiver functions for each station with different Gaussian coefficients(b)

图3 本文用到的远震事件的震中分布(a)和不同高斯系数下单台接收函数叠加后的波形(b)
Fig.3 Epicenter distribution of teleseismic events used in this study(a)and stacked receiver functions for each station with different Gaussian coefficients(b)

图4 腾冲火山区地壳厚度和VP/VS比值(a)、地壳厚度随频率变化(b)以及Ps/P和PpPs/P振幅比分布特征(c、d)<br/>Fig.4 Crustal thickness and VP/VS ratio(a),variations in Crustal thickness with frequency(b),distribution characteristics of Ps/P and PpPs/P amplitude ratios(c,d)

图4 腾冲火山区地壳厚度和VP/VS比值(a)、地壳厚度随频率变化(b)以及Ps/P和PpPs/P振幅比分布特征(c、d)
Fig.4 Crustal thickness and VP/VS ratio(a),variations in Crustal thickness with frequency(b),distribution characteristics of Ps/P and PpPs/P amplitude ratios(c,d)

图5 腾冲火山区岩浆上涌通道示意图<br/>Fig.5 Schematic model of magma upwelling channel in the Tengchong volcanic area

图5 腾冲火山区岩浆上涌通道示意图
Fig.5 Schematic model of magma upwelling channel in the Tengchong volcanic area

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备注

引言

1 理论分析与数据来源

2 结果与讨论

3 结论

期刊信息