Insight into modification of North China Craton from seismological study in the shandong province

Abstract

The study region is located in the southeast edge of the North China Craton (NCC), which is an Archean craton that underwent removal and modification of the lithospheric mantle during the Late Mesozoic-Cenozoic. Teleseismic data from the NCISP-1 experiment were used to image the velocity structures in lithosphere and to investigate the upper mantle anisotropy. Seismological results revealed that the present lithosphere consists of two parts with different structural features throughout, including crustal fabric, lithospheric velocity stratification, and anisotropic patterns. The formation of the contrasting structure is attributable to one of two possibilities: the trans-lithospheric Tanlu fault zone (TLFZ) operated as an asthenospheric upwelling channel and facilitated the NCC reactivation, or the TLFZ separates the study region into two lithospheric blocks, with the ancient lithospheric materials remaining within the rejuvenated lithospheric mantle. These two possibilities suggest that thermal/chemical erosion may have played critical roles in the NCC reactivation. Copyright 2008 by the American Geophysical Union.