Seismic evidence links the subducted Mongol-Okhotsk slab to deformation in D near the northeastern margin of the Perm Anomaly

Numerical simulations have indicated that the Large low-Shear Velocity Provinces (LLSVPs) dynamically interact with subducted slabs in and slabs in turn play an important role in influencing the shape and location of the LLSVPs. In this study, we find evidence for the existence of the D '' discontinuity near the northeastern margin of the Perm Anomaly - a smaller LLSVP beneath Eurasia, by analyzing the Scd (the lower mantle triplication) phases generated from two deep events occurring in the northwestern Pacific subduction zone and recorded at stations in Europe and Turkey. The D '' discontinuity in the north is characterized with a + 2% velocity increase occurring at a height of 300 km above the core-mantle boundary (CMB), whereas the discontinuity in the south is characterized with a + 3% velocity increase occurring at a height of 260 km above the CMB. The D '' discontinuity is most likely attributed to a phase transition from perovskite to post-perovskite in conjunction with the presence of relic slab materials (likely related to the subducted Mongol-Okhotsk slab). Our observations along with previous seismic anisotropic detections- provide a clue to dynamically link the subducted slab to deformation taking place near the edges of the LLSVP.