Liaoning Institute of Geological Exploration��Dalian 116100��Liaoning��China

The author systematically discussed petrology and geochemistry of the ophiolite in the studied area�� It mainly contains metamorphic gabbro��basaltic lava with pillow structure and siliceous slate in bronzing pelagic sedimentary cover from bottom to top�� All the lithologic units are in fault contact�� The geochemistry of the lava ap- pears low K and high Al��and the highly incompatible elements (��b��Ba��Th��K��Pb��Hf) are strong enriched�� with significant losses of high field strength elements (Ta��P)�� The geochemical characteristics of the ophiolite in Xilin��Gaxian��Jifeng��is characterized by E- MO��B��whch is very similar to that of the part igneous rock�� They are the products in the same period and tectonic background��reflecting the source region of the ophiolite derived from asthenospheric mantle and mixed with a small amount of enriched mantle�� Through the construction of environment judgment��it is considered that the ophiolite is in typical transitional SSZ type�� By comparison with the Early Paleo- zoic tectonic evolution in North Greater Khingan ��ange��the Wilson cycle of the orogenic process was recovered�� It is believed that Ergun and Xingan micro plates were pieced together along the Tayuan ��Toudaoqiao��and closing time for the Cambrian series Jiang Shanjie lotus��