Fast Seismic Anomalies Under Continents Explained by the Delaminated Lower Continental CrustImplications From High PressureTemperature Elasticity of Jadeite Academic Article uri icon

abstract

  • AbstractSeismic tomography has shown that the shear wave velocities (Vs) under continents, especially under cratons, are extremely fast at 100200km depth, which is difficult to explain by low temperatures or high Mg#. Alternatively, delaminated eclogitic lower continental crust has been proposed to account for these fast seismic anomalies. However, the thermoelastic properties of jadeite which constitutes up to 6080mol% of clinopyroxene in the potentially delaminated lower continental crust are not well constrained. In this study, we measured the singlecrystal elasticity of jadeite by Brillouin spectroscopy under simultaneous high pressure and temperature conditions for the first time. We found that the temperature dependence of Vs of jadeite is extremely small if not negligible. The seismic velocities of the potentially delaminated lower continental crusts were subsequently modeled and found to match the widely observed fast seismic anomalies under cratons between 100 and 200km depth.

published proceedings

  • Geophysical Research Letters

author list (cited authors)

  • Hao, M., Zhou, W., Dera, P., Schmandt, B., Zhang, D., & Zhang, J. S.

complete list of authors

  • Hao, Ming||Zhou, Wen‐Yi||Dera, Przemyslaw||Schmandt, Brandon||Zhang, Dongzhou||Zhang, Jin S

publication date

  • May 2024