Lithospheric structure beneath the Qinling Orogenic Belt and its surrounding regions: Implications for regional lithosphere deformation

Abstract

AbstractWe present a lithospheric shear‐wave velocity model for the Qinling Orogenic Belt (QOB) and its surrounding regions through joint inversion of surface wave dispersion and receiver functions. Our model reveals large‐scale extremely low‐velocity zones (Vs ≤ 3.4 km/s) beneath the Northeastern Tibetan Plateau without further eastward extension, implying the absence ductile crustal flow beneath the eastern part of QOB. Pronounced upper‐mantle low‐velocity anomalies are imaged beneath the North Qinling and Weihe basin, suggesting the existence of deep mantle upwellings that lead to the extensional tectonics in these regions. A high‐velocity zone running continuously from the Alxa block to the eastern part of Qilian orogen in the uppermost mantle is revealed. We identify the high‐velocity zone to be the Asian mantle lithosphere and infer the development of southward underthrusting towards Qilian orogen.