Structure of the upper mantle of Northern Eurasia from 2D density modeling on seismic profiles with peaceful nuclear explosions

Abstract

Abstract Seismic data, obtained on the territory of Russia along the super-long seismic profiles, acquired with the Peaceful Nuclear Explosions (PNE), provide new possibilities for setting up joint geophysical models for the continental upper mantle structure. The PNE profiles show that the upper mantle is heterogeneous and its structure correlates with tectonics and the heat flow data. Since the upper mantle composition affects the density to a greater extent than seismic velocities, we initiated a 2D gravity modeling along the PNE profiles Quartz, Craton and Kimberlite in order to get new constraints on the composition of the Northern Eurasia upper mantle. The profiles cross the East European Platform, the Urals, the West-Siberian Plate and the Siberian Craton. The initial density models were constructed from the seismic data using the density/velocity relation of the Earth reference models. The initial gravity data are taken from the satellite GOCE global models. The modeling shows that the upper mantle of Archean-Early Proterozoic Siberian Craton, distinguished by higher velocities in the upper 150–200 km layer, should have the decreased densities responsible for a strong gravity low (− 100 mGal). It could be indicative of variation in the composition due to depletion of the cratonic upper mantle. The composition of the upper mantle of the East European Platform, regarding its high velocities and high densities, resembles the composition of the primitive mantle fertile matter. The Paleozoic suture zone of the Urals is characterized by anomalous structure of the crust and of the uppermost mantle with the high-density and velocity bodies indicative of the eclogite presence.