Crustal Structure Beneath the Namche Barwa Massif, Eastern Himalayan Syntaxis: Evidence of Magma Underplating?

Abstract The Namche Barwa massif (NBM) in the Eastern Himalayan Syntaxis (EHS) hosts some of the most active Cenozoic crustal deformation, magmatism, metamorphism, and extreme topographic relief on earth. The crust‐mantle dynamics responsible for the tectono‐magmatism in the NBM remains debated. We image the detailed crustal structures under the NBM using the recordings of a dense seismic array of 400 3‐component node geophones and 4,290 P‐wave receiver functions (PRFs). Our results show a wide range of negative seismic phases in the middle and lower crust and weak Moho signal in the northern part of the NBM, under the Yarlung‐Zangbo River (YZR). The upper crustal discontinuities show “hut” shape structures, and these features were validated with the forward simulation and PRFs from three broadband seismic stations in the region. These crustal structures indicate the presence of magma underplating in the upper mantle under the NBM.