College of Earth Sciences, Jilin University, Changchun 130061, China

On the basis of detailed field geological survey, the authors undertook petrographic and geochemical analysis of the amphibolites in Lieryu Formation of lower South Liaohe Group. Petrographic studies show that the amphibolites in Lieryu Formation are orthometamorphite. Geochemical data indicates that the amphibolites belong to high Fe tholeiitic series (Nb/Y=0.16~0.40), with the content of SiO₂ of 47.27%~50.68%, and low TiO₂ content of 0.92%~1.61%. They are depleted in high field strength elements such as Nb, Ta, Zr and Hf, indicating that their original rocks were formed in an island arc or active continental margin, rather than the continental rift defined by previous studies. Integrating petrographic and geochemical characteristics, it is preliminarily concluded that the petrogenesis is related to the active continental margin.