No basalt accumulation and segregation atop the 660-km discontinuity beneath the Sea of Okhotsk

作     者：BingXin Zhou XiaoBo He 

作者机构：Marine Science and Technology CollegeZhejiang Ocean UniversityZhoushan Zhejiang 316022China 

出 版 物：《Earth and Planetary Physics》 (地球与行星物理（英文版）)

年 卷 期：2024年第8卷第4期

页      面：621-631页

核心收录：

学科分类：070904[理学-构造地质学] 0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 

基　　金：support from the National Natural Science Foundation of China(Grant No.42276049) the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB42020103) 

主　　题：660-km discontinuity S660P basalt segregation mantle transition zone western Pacific subduction zone 

摘      要：Recent seismic evidence shows that basalt accumulation is widespread in the mantle transition zone(MTZ),yet its ubiquity or sporadic nature remains *** investigate this phenomenon further,we characterized the velocity structure across the 660-km discontinuity that separates the upper mantle from the lower mantle beneath the Sea of Okhotsk by modeling the waveform of the S660P phase,a downgoing S wave converting into a P wave at the 660-km *** waves were excited by two regional410-km-deep events and were recorded by stations in central *** findings showed no need to introduce velocity anomalies at the base of the MTZ to explain the S660P waveforms because the IASP91 model adequately reproduced the *** finding indicates that the basalt accumulation has not affected the bottom of the MTZ in the study ***,this discontinuity is primarily controlled by temperature or water content variations,or ***,we argue that the basalt accumulation at the base of the MTZ is sporadic,not ubiquitous,reflecting its heterogeneous distribution.