The Sound Velocity Measurements Of Fe-O-S At High Pressure And The Candidate Compositions Research Of Earth's Outer Core

The seismic velocity data is the most important ways for human understanding of Earth's internal structure and composition,and the limits of the Earth's Mineralogical Composition,excepting for complying with the established model of the Earth based on the seismic velocity data,it should also consistent with the universe chemical model,and it should be accepted by the high temperature and high pressure experiments.So it compares the measurement results of various candidate mineral with the profile of the density and sound velocity in the Earth model. Therefore,this paper carries out limited study of Earth's outer core compositions,by means of theories of condensed matter and recently developed high pressure and high temperature techniques.So this work is a research topic belonging to cross disciplines. This article includes the following results:(1) Based on the full research of the Earth's outer core at home and abroad, ternary alloys of Fe-O-S with 92.5/2.2/5.3 by wt.%is chosen as the sample material, based on Huang's suggestions and the PREM model constrained by both density and sound velocity vs pressure relations.(2) Under high pressure and high temperature,the sound velocity study of the candidate material of the Earth's outer core has very important significance.Through its inversion of seismic velocity data can be more positive or amendment of the Earth's interior information.The significance,measuring principle and the test methods of high-pressure sound velocity measurement are introduced in detail in this paper.And then,this paper described in detail with the principle and measurement techniques of VISAR.Compared with the commonly Optical analysis techniques,the VISAR sound velocity measurements just use one sample,and the experimental setups are Simple.We can not only get P-wave velocity,but also get body-wave velocity,and it can also effectively improve the measurement accuracy.(3) Through the VISAR sound measurement techniques,we measure two Sound velocity measurements of Fe-O-S material during 106-232GPa and get the sound-pressure curve.Combination of the pre-test data of Huang,we have received that O and S are the main light elements of the Earth's outer core,and they can effectively reduce the density of iron and improve the sound speed under the temperature and pressure conditions of Earth's outer core.O can enhance the sound speed of Fe more than S.(4) At ICB(330GPa),the melting temperatures of Fe-O-S material is 5400K.O and S effectively reduce the melting temperature of iron.This article identifies the temperature profile of the Earth's outer core,and it also calculates the Fe-O-S mixture's density and body wave velocity under the temperature and pressure conditions of Earth's outer core.The results show that the ternary alloy candidate Earth's outer core compositions of Fe-O-S system can be basically constrained with PREM model.Combination of Huang's conclusion,we can get that the content of O and S are non-uniform in the Earth's outer core,and the distribution may be into a gradient.There is more S element beside the inner core,and there is more O element beside the Mantle.