[S-IT17] TRANSPORT PROPERTIES AND PROCESSES IN THE EARTH

[SIT17-P03] Elasticity of dolomite at mantle conditions: Implication for the origin of mid-lithosphere discontinuity

*Yajie Zhao¹, Xin Deng¹, Ling Chen², Zhongqing Wu¹ (1.University of Science and Technology of China, 2.Chinese Academy of Sciences)

Keywords:dolomite, elasticity, mid-lithosphere discontinuity, craton

The mid-lithosphere discontinuity (MLD) with a significant velocity reduction is detected widely in the cratonic lithosphere. During the formation and evolution of cratonic continents, carbon-bearing melts can be introduced by the paleo-subduction process or mantle plumes. As the lithospheric mantle cooled down, the carbonatitic melts trapped at ~80-100 km depth would react with pyroxene and olivine in the surrounding mantle to produce dolomite. Therefore, MLDs in some cratons may be the chemical layer enriched in dolomite. Here, we investigated the elasticity of dolomite at mantle conditions using ab initio calculations. We found the velocities of dolomite are significantly lower than those of the main minerals in the lithospheric mantle. Different from hydrous minerals such as amphibole and phlogopite, dolomite has an electrical conductivity similar to olivine. The enrichment of dolomite does not produce high electrical conductivity and more likely explains the MLD in cratonic regions where no high-conductivity anomaly has been detected.