THE STRUCTURAL FRAMEWORK OF THE THRUST NAPPE IN WESTERN FUJIAN AND ITS EVOLUTION

The early Mesozoic thrust nappe structure in western Fujian is composed of three basic tectonic units:the crystalline basement obduction zone in the central part and the cover fold thrust zone in the east.Paleotectonic stress measurements indicate that the stress values decrease from west to east.By using the principle of layer length conservation,the rate of crustal shortening resulting from thrusting has been estimated to be at least 45% with a shortening amount of nearly 120km.The thrust nappe as a whole was controlled by the tectonism of the basement of Cathaysia and constitutes a part of the southeast vergent thrust belt on the northwestern margin of Cathaysia.It combines with the northwest vergent foreland margin fold thrust belt on the southeastern margin of the Yangtze platform to form the early Mesozoic South China deflected symmetric fan shaped thrust orogenic belt.