Geochemical characteristics and formation environments of metamorphic rocks in the Kanas Group of Altay tectonic belt

The geochemical study of metamorphic rocks of the Kanas Group in Altay tectonic belt shows that the metamorphic rocks are mainly argillaceous sedimentary rocks, with small amounts of sandy sedimentary rocks, Source material is mainly of acidic continental arc volcanic rocks mixed with a small amount of other debris. Although there are differences in lithology between 16 samples, the chemical etching of the variable indexes (CIA) is almost all less than 75, indexes of compositional variation (ICV) are close to or higher than 1, indicating that the source region must have experienced a warm, humid conditions of moderate chemical weathering and the maturity was poor, being the first deposition product of active continental margin. The La, Ce, ∑REE, LREE/HREE, sigma delta Eu values of the metamorphic rocks indicate that the protolith formed in a continental arc setting. These geochemical characteristics suggest that the Kanas Group metamorphic rocks probably deposited on an active continental margin of continental island arc environment. It is inferred that Kanas Group sedimentation and metamorphism occurred between 550±18ma to 430Ma and, according to the corresponding time, the metamorphism of the Kanas Group took place in Caledonian.