Distinct Lithospheric Structures of the Ordos Block and Its Margins From P and S Receiver Functions and Its Implications for the Cenozoic Lithospheric Reworking

Abstract

We obtained the crustal and lithospheric structures across the Ordos block in the western North China Craton, using P and S receiver functions (RFs) based on teleseismic data of a dense N-S seismic array. Migrated images for P and S RFs show distinct lithospheric features of the Ordos block and its margins: a thick, cratonic lithosphere is present beneath the Ordos block, whereas the lithosphere is significantly thin at its surrounding rift systems. More importantly the Ordos lithosphere is severely modified by the mantle upwelling at the northern margin but has little modification by the eastward lateral asthenospheric flow at the southern margin. Finally, the dramatically thin lithosphere observed across the southern margin of the Ordos block supports the existence of a significant pathway for eastward asthenospheric flow from the northeastern Tibetan Plateau beneath the Weihe rift and Qinling orogen.