Determination of crustal thickness and velocities by using receiver functions and PmP travel times
Determination of crustal thickness and velocities by using receiver functions and PmP travel times
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使用接收器函数和 PmP 传播时间确定地壳厚度和速度
DOI：
10.1093/gji/ggy500
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发表时间：
2019
影响因子：
2.8
通讯作者：
Hua Yuanyuan
中科院分区：
文献类型：
--
作者：
Luo Song;Zhu Lupei;Huang Rong;Luo Yinhe;Jiang Xiaohuan;Hua Yuanyuan
地壳厚度（H）和Vp/Vs比（κ）是表征地壳结构的两个重要参数。当接收函数只有MohoP-S转换相位且其地壳多次波较弱或缺失时，由于两个参数之间的严重权衡，它们根据接收函数数据的估计通常具有较大的不确定性，这在构造活动区是常见的。本文推广了H-κ叠加法，将接收函数和PmP走时结合起来，同时确定H、κ和Vp。我们发展了一种反褶积技术，利用地震S波中的后临界Moho P波反射SsPmp来测量PmP走时。综合试验表明，只要接收函数中莫霍面清晰，新方法就能可靠地提取PmP走时，确定地壳厚度和速度。我们将这些方法应用于中国鄂西地区的63个宽带地震台站。研究结果证实了以前的研究所揭示的地壳厚度从研究区东部的低海拔平原到西部的山脉迅速增加的现象。地壳泊松比从低-中等值到中-高值的相应增加表明，东部地壳更长英质，最可能是由于晚中生代扬子地台的一部分镁铁质下地壳的拆沉。
Crustal thickness (H) andVp/Vsratio (κ) are two important parameters in characterizing a crustal structure. Their estimates from receiver function data often have large uncertainties due to the severe trade-off between the two parameters when the receiver functions only have the MohoP-to-Sconverted phase and its crustal multiples are weak or missing, which are common in tectonically active regions. Here, we extended theH–κ stacking method by combining receiver functions andPmPtraveltimes to determineH, κ andVpsimultaneously. We developed a deconvolution technique to measurePmPtraveltimes using the post-critical MohoP-wave reflectionSsPmpin the teleseismicSwave. Synthetic tests show that the new methods can reliably extract thePmPtraveltimes and determine crustal thickness and velocities as long as the MohoPsis clear in receiver functions. We applied the methods to 63 broad-band seismic stations in the western Hubei Province of China. The results confirm the rapid increase of crustal thickness revealed in a previous study from the low-elevation plains in the eastern part of the study area to the mountains in the west. The corresponding increase of crustal Poisson’s ratio from low-to-intermediate values to intermediate-to-high values suggests that the crust in the eastern part is more felsic, most likely due to delamination of a portion of the mafic lower crust of the Yangtze platform in the Late Mesozoic.