Sedimentary System and Depositional Environment of Copper-Bearing Rock Series of Neogene in Baicheng County, Xinjiang

Key words: 
• Baicheng county /
• copper-bearing rock series /
• sedimentary environment /
• Neogene

Abstract: A set of Neogene thick continental clastic sedimentary rocks develops in Baicheng County, Xinjiang province, in which a large-scale sedimentary copper ore occurs in the upper part of Kangcun Formation. Obviously, it is of important significance in the formation of copper deposits to the sedimentary environment and its evolution of the Kangcun Formation. Based on detailed sedimentological studies in field and laboratory, two major types of sedimentary system, alluvial fan-fan delta type and lacustrine type, are identified for Jidike Formation, Kangcun Formation and Kuqa Formation of Neogene in the study area. The sedimentary systems are further divided into subfacies of fan delta plain, fan delta front, front fan delta, shore shallow lacustrine, gypsum-salt lacustrine and some microfacies. The sedimentary framework of the Kangcun stage approximately inherited that of the Jidike stage. The types of sedimentary facies were mainly fan delta facies in the study area during the Kangcun stage, while sediments of lacustrine facies occurred in warm humid climate could fill the whole study area. Main ore-bearing beds are in the transitional strata of red rocks to gray rocks in the upper part of Kangcun Formation. And the sedimentary characteristics of ore-bearing beds indicate that the depositional environment have experienced a process from fan delta front facies to shore shallow lacustrine facies.