Geochemical Characteristics and Genesis for Volcanic Rocks of Yixian Formation in Western Liaoning Province

Abstract

Volcanic rocks of Yixian Formation were widely distributed in western Liaoning. The Yixian volcanic cycle of early Cretaceous in the Chaoyang basin can be divided into two subcycles. The first subcycle is composed of basalt, basalt andesite and andesite. The second subcycle is composed of trachyandensite and trachyte. The volcanic rocks are characterized by high SiO2, Al2O3, K2O and Na2O, and comparatively low TiO2 components. The volcanic rocks are obviously enriched in incompatible elements, and depleted in compatible elements. The ∑REE of volcanic rocks is high and rich in LREE. The spider patterns are the right-incline, there is a slight low Eu negative abnormality and low Ce negative abnormality. The characteristics show that volcanic rocks of Yixian Formation belong to the high-K calc-alkaline magmatic serious. Comprehensive study shows that the volcanic rocks of Yixian Formation were generated in response to lithosphere extension in the continent intraplate orogenic belt.