Progress of the low velocity zone atop the mantle transition zone

Abstract

Since the discovery of the low velocity zone(LVZ)atop the mantle transition zone(MTZ),it has been playing a significant role in the development of solid geophysics in recent 20 years. The LVZ has an enormous implication for understanding subduction behavior,patterns and intensity of mantle convection,coupled and decoupled status between adjacent layers,distribution and transportation of materials,evolution of primitive Earth and other physical and chemical processes.As a consequence,it opens a window for us to resolve scientific problems of the Earth's interior.The LVZs detected in various regions around the world,with different tectonic backgrounds,mainly including subduction zone and continental craton,always show obvious lateral variation in depth and thickness.This paper also tries to make sense of the discovery process and summary typical characteristics of the global LVZs.With respect to the origin of the LVZ,although the partial melting model has been accepted widely,the inducing factors,location of initial partial melting and physical properties of melt like density and viscosity have not yet been sufficiently determined.Relevant geodynamic implications are also discussed eventually according to analysis of several key points based on partial melting genesis model.