Cryptic Magma Chamber in the Deccan Traps Imaged Using Receiver Functions and Surface Wave Dispersion

Abstract

An anomalous crust and lithospheric mantle in the Deccan Volcanic Province are imaged below a 160 km long W-E profile through the joint inversion of receiver functions and surface wave dispersion. The upper crust has an unusually low S-wave velocity (Vs ∼ 3.3–3.5 km/s) at 8–17 km depth, underlying a 4 km thick high-velocity layer (Vs > 3.8 km/s). The low velocity possibly represents the frozen magma reservoir, the source for the magma eruption at ∼65 Ma due to the interaction of the Reunion plume with India. The shallow, high-velocity layer could be basaltic mafic intrusions responsible for the production of massive CO2 degassing. The Moho deepens beneath the west coast to ∼45 km due to 10–15 km of magma underplating. The mantle plume scar is seen as thinned lithosphere (80–100 km), with the presence of long-lived low-velocity layers in the shallow mantle attributed to the presence of sulfide melts.