Tectonic characteristics of the central segment of the Tancheng–Lujiang fault zone, Shandong Peninsula, eastern China

Abstract

The Tancheng–Lujiang fault zone (TLFZ), in the central segment in the Shandong Peninsula, eastern China, is composed of four major faults, called F1–F4 from east to west, forming a 50-km-wide zone. Detailed field study demonstrates that Neogene volcanic and sedimentary strata, Quaternary deposits, and topographic surfaces cover the fractured zones of faults F3 and F4 and are not deformed or displaced. The same rocks and surfaces on faults F1 and F2, however, are clearly displaced. The geological and seismological data show that the F1 and F2 are presently active as a major seismic zone in eastern China, whereas the F3 and F4 have been inactive since the Neogene. Fabrics of foliated cataclastic rocks generated in the fracture zones show left-lateral strike-slip on the F3 and F4 between Cretaceous and Neogene time, and high-angle reverse or normal faulting, with a dextral component, on faults F1 and F2 in late Quaternary time. Field evidence and analysis of the fabrics of fault-related rocks reveal the changes of shear sense and activity of faults F1–F4 of the central segment of the TLFZ from Cretaceous to Quaternary time in the Shandong Peninsula.