Abstract: Olivine is widely viewed as the most abundant mineral in the Earth’s upper mantle, with contents ranging from 30% to 65% for different mantle petrological models. The olivine-wadsleyite transition at ~13-14GPa is most likely the cause of the 410 km discontinuity and for a long time, the magnitude and topography of this discontinuity have been used to calculate the averaged olivine content and temperature variations near the 410 km depth. Although the olivine-wadsleyite phase transformation has been studied intensely over the past several decades, many aspects are hidden, beyond the Clapeyron slope, the compositional/thermal effect, and the isotropic velocity jumps. In this talk, I am going to focus on two hidden aspects: the first one is utilizing olivine-wadsleyite transition and 410 discontinuity as a geochemical/petrological marker; the second one is investigating the possibility of using the anisotropy change across the olivine-wadsleyite transition as a deformation/flow field indicator. These studies are very important for linking and understanding the geochemical data, geodynamic simulations and geophysical observations at upper mantle transition zone depth range in the Earth’s interior.