Mapping the chemistry of the Earth’s mantle

Publication of the LGL-TPE in the journal PNAS on November 21, 2022. CNRS-INSU communication on December 7, 2022. In the 1980s, geochemical observations led researchers to propose a geodynamic model of the mantle's marbled structure. A team of scientists, some of whom are attached to the Laboratory of Geology of Lyon: Earth, Planets, Environment (LGL-TPE, CNRS/ENS de Lyon/Claude Bernard Lyon 1 University), has been working on this model using a seismological perspective. There is no direct access to the deep Earth mantle. Therefore, insights into the deep mantle composition rely on indirect observations from geophysics. We exploit seismic datasets of compressional and shear waves reflected at mineralogical phase transitions globally and reveal the existence of anomalous geochemical reservoirs in the mantle transition zone (MTZ).