Receiver function analysis at Shanxi Rift

Shanxi Rift, which separates the stable Ordos Block and extensional North China Basin, is thought to have resulted from the differential extrusion of Tibean Plateau between the North and South China blocks.During August 2006 to March 2008, Peking University deployed two linear arrays (140 km apart) of 45 portable broadband seismometers across the southern part of Shanxi Rift.Slant-stacking and migration images of receiver functions reveal an uplift about 4～6 km of the Moho and an increase of the V_P/V_S ratio from about 1.75 beneath Ordos Block and Taihang uplift to 2.0 under the rift.A low velocity layer may exist in the crust beneath the rift.We conclude that Shanxi Rift has accommodated much of the difference in stress field and tectonic activity between Ordos and North China Basin.We also observe a transition in the basin formation mechanism from a pure-shear model at Linfen Basin in the south to a simple-shear model at Taiyuan Basin.