Composition and Seismic Properties of the Oceanic Lithosphere: A Synthesis of Ophiolites and Core Samples of the IODP

作     者：ZHAO Jiabin WANG Qin 

作者机构：State Key Laboratory for Mineral Deposits ResearchSchool of Earth Sciences and EngineeringNanjing UniversityNanjingJiangsu 210023 

出 版 物：《Acta Geologica Sinica(English Edition)》 (地质学报（英文版）)

年 卷 期：2020年第94卷第S01期

页      面：89-90页

核心收录：

学科分类：0709[理学-地质学] 0819[工学-矿业工程] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 0818[工学-地质资源与地质工程] 0708[理学-地球物理学] 0816[工学-测绘科学与技术] 

主　　题：ophiolite seismic velocity oceanic crust serpentinization Moho 

摘      要：Our knowledge of the oceanic lithosphere largely comes from analogy with ophiolite complexes and the direct scientific drilling of the present-day oceanic crust(e.g.,Christensen and Salisbury,1975,1989;Smith and Vine,1989;Dilek and Furnes,2011,2014).In this study,we summarized previous experimental results on seismic properties of oceanic lower crust and upper mantle according to different tectonic *** results are used to highlight the compositional heterogeneity and the nature of the oceanic *** in different ophiolites reveal an ideal oceanic lithosphere profile with ideal petrologic units and seismic units(Dilek and Furnes,2011,2014).The lithospheric mantle beneath ocean basins is composed of tectonized peridotites,which include layered lherzolites and harzburgites and lenses of dunites with chromitites and nearly correspond to the seismic Layer *** overlying layered gabbros and mafic sheeted dike complex equal to the seismic Layer 3,as a result of crystallization from a magma *** transitional unit between the former two petrologic units consists of layered ultramafic and mafic rocks,corresponds to the petrological *** seismic Layer 2 and 1 are well defined by pillow lavas and massive flows,and the overlying abyssal sediments,*** these results with the refraction seismic profiles,the oceanic crust and upper mantle show different composition and *** Pwave velocities of the Layer 3 gabbros varies from 6.7 to 7.0 km s-1 and have low velocity gradients of0.1 km *** the gradual increase of P-and S-wave velocities with depth can be attributed to the increasing proportion of mafic minerals from the top to the bottom,prehnite-pumpellyite facies alteration of basalts,greenschist-faces metamorphism to epidote-amphibolite facies metamorphism of gabbros will decrease the velocities of the Layer 2 and Layer 3(Christensen and Salisbury,1975,1989),because the P-wave velocities of chlorite and hornblende a