Crustal and lithospheric structure of Northeast China from S-wave receiver functions

Abstract

Lithospheric thickness is closely associated with lithospheric response to tectonic forces or thermal processes. Analysis of S-wave receiver functions (SRFs) from a dense seismic array has revealed lithospheric thickness variations along a 1200 km long profile that spans all major geological terranes of Northeast China. The SRF images identify the shallowest Moho and lithosphere–asthenosphere boundary (LAB) depths beneath the rifted Songliao Basin, thus spatially correlating well with the thick sediment accumulation. These features can be explained by a pure shear regime operating in the lower crust and upper mantle, suggesting the predominance of roughly symmetric lithosphere stretching from continental rifting. In contrast, thicker lithosphere in western and eastern terranes of NE China indicates the lithosphere in these regions was not strongly affected by the extensional processes during the Late Mesozoic. Flat LAB structure beneath the Erguna and Xing'an terranes along with the overlying relatively deeper Moho beneath the Great Xing'an Range, suggests the North–South Gravity Lineament may not be a trans-lithospheric structure.