Morphology and possible origins of the Perm anomaly in the lowermost mantle of Earth

作者：YuMei He,LianXing Wen,Yann Capdeville

摘要：We have constrained a small-scale,dome-shaped low-velocity structure near the core-mantle boundary(CMB)of Earth beneath Perm(the Perm anomaly)using travel-time analysis and three-dimensional(3-D)forward waveform modeling of seismic data sampling of the mantle.The best-fitting dome-shaped model centers at 60.0°E,50.5°N,and has a height of 400 km and a radius that increases from 200 km at the top to 450 km at the CMB.Its velocity reduction varies from 0%at the top to–3.0%at 240km above the CMB to–3.5%at the CMB.A surrounding 240-km-thick high-velocity D''structure has also been detected.The Perm anomaly may represent a stable smallscale chemical pile in the lowermost mantle,although the hypothesis of a developing mantle plume cannot be ruled out.

发文机构：Key Laboratory of Earth and Planetary Physics Mohe Observatory of Geophysics Laboratory of Seismology and Physics of Earth’s Interior Department of Geosciences Laboratoire de Planétologie et Géodynamique de Nantes

关键词：seismicvelocitystructurecore-mantleboundaryPermanomalychemicalpile

分类号： P31[天文地球—固体地球物理学]