Open AccessMorphology and possible origins of the Perm anomaly in the lowermost mantle of Earth
Author(s) -
He YuMei,
Wen LianXing,
Capdeville Yann
Publication year - 2021
Publication title -
earth and planetary physics
Language(s) - English
Resource type - Journals
ISSN - 2096-3955
DOI - 10.26464/epp2021009
Subject(s) - mantle (geology) , core–mantle boundary , geology , cosmic microwave background , geophysics , anomaly (physics) , mantle plume , plume , plate tectonics , seismology , tectonics , physics , lithosphere , meteorology , anisotropy , condensed matter physics , quantum mechanics
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 small‐scale chemical pile in the lowermost mantle, although the hypothesis of a developing mantle plume cannot be ruled out.