Wave velocities and anisotropy of rocks:Implication for origin of low velocity zone of the Qinling Orogenic Belt,China  

作　　者：Lei Liu Ying Li Tingting Li Hanyu Wang Shasha Liu Panpan Zhao Gerile Naren Li Yi Hong Liu Fengxia Sun Jianguo Du 

机构地区：[1]United Laboratory of High-Pressure Physics and Earthquake Science,Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China [2]Shandong Provincial No.3 Exploration Institute of Geology and Mineral Resources,Yantai 264004,Shandong,China [3]School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China [4]Shanghai Supercomputer Center,Shanghai 201203,China

出　　处：《Geoscience Frontiers》2025年第1期393-405,共13页地学前缘(英文版)

基　　金：supported by the National Natural Science Foundation of China(42174115 and 42330311);the Special Fund of the Institute of Earthquake Forecasting,China Earthquake Administration(CEAIEF20230301);the State key laboratory of earthquake dynamics(LED2021B02).

摘　　要：Structure and composition of Earth are fundamental importance in exploring the dynamic evolution of the crust and mantle.The Qinling Orogenic Belt(QOB)is located between the North China plate and the South China Plate,and is one of the main orogenic belts in China.To explore the composition and origin of anisotropy and the low wave velocity zone of the QOB,ten rock samples(gneiss and schist)were collected from the five sites of the QOB and the P-and S-wave velocities of these samples were measured under 0.6 to 2.0 GPa and 100 to 550℃.The wave velocities increase with increasing pressure and decreasing temperature.The V_(P)and V_(S)of the schist and gneiss match the velocity of the middle and lower crust of the QOB,indicating that schist and gneiss are important component of the QOB.All the schist and gneiss samples exhibit obvious seismic anisotropy with 1.64%-17.42%for V_(S)and 2.93%-14.78%for V_(P)under conditions of crust and upper mantle.The CPO/LPO and layering distribution of mica in rock samples are the main reasons for this anisotropy.The V_(S)structures below the five sampled sites from seismic ambient noise tomography were built to explore the effect of schist and gneiss on the composition and structure of the QOB.The results indicate that orientation-arranged gneiss and schist driven by the tectonic stresses might be a new origin of the character of V_(P)/V_(S),seismic anisotropy,and the low velocity zone in the QOB.

关 键 词：Wave velocity of rock ANISOTROPY Origin of low velocity zone The Qinling Orogenic Belt 

分 类 号：P58[天文地球—岩石学]