Structure of the 410 discontinuity in Northeast China and its dynamic enlightenment
The mantle transition zone is an important water storage reservoir on the Earth.The sharpness of the mantle discontinuities and the seismic wave velocity jump across the discontinuities can provide essential constraints on the water con-tent and mineral composition near the transition zone.In this study,we extract the amplitude of multi-band Pds conversion wave from the open seismic data recorded by four temporary arrays in Northeast China.We simultaneously obtain the shear wave velocity jump across the 410-km discontinuity and its sharpness using the Markov Chain Monte Carlo method(MCMC).The results show that the sharpness of 410 discontinuity in this area has reached～25 km,and the shear wave velocity has in-creased～6.9%in this depth interval.We believe that the continuous dehydration of the Pacific plate at the bottom of the tran-sition zone increased the water content at the top of the transition zone(>0.5 wt.%),which made the minerals at or above the state of fluid saturation,resulting in partial melting of the minerals,forming low-velocity and low-resistivity anomalies,and at the same time,significantly thickening of the 410 discontinuity compared with that without water(～7 km).
Northeast Chinareceiver functionMarkov chain Monte Carlo method410 km discontinuitywater con-tent
国家科技期刊平台
NSTL
万方数据
