Characteristics of fault rocks and paleoearthquake source along the Koktokay-Ertai fault zone, Xinjiang, China

Abstract

The Koktokay-Ertai fault zone was developed on the basis of a former ductile shear zone (mylonite zone). The mylonites were formed in the brittle-ductile transition zone at 10–15 km depth within the crust. The rocks had experienced multi period deformation processes, including ductile deformation, ductile instability and brittle seismic faulting which had gave rise to the formation of Koktokay-Ertai fault zone and the development of pseudotachylytes. The pseudotachylytes are distributed within an area about 60 km in length and 300 m in width, which may represent the scale of the paleo-earthquake source. The physical conditions of the paleo-earthquake source was similar to those for the formation of the mylonites along this zone.