Geological Characteristics and Genesis of Porphyry Copper Deposits in East Junggar Region

The East Junggar metallogenic belt is one of the main ore districts with favorable geological conditions for the formation of porphyry ore deposits.In recent years,Tuwu and Oyu Tolgoi large-size porphyry copper deposits were found in adjacent areas,which promoted the exploration and research work of porphyry copper deposits in East Junggar region.Porphyry copper deposits such as Halasu,Menxi,Yulekenhalasu Qiongheba,Heaisai,Tonghualing and Wulunbulake were discovered in succession.This paper deals with the geological setting of porphyry copper deposits formed in East Junggar.According to lithologic and ore-forming characteristics of the porphyry copper deposits,the authors have divided ore deposits in East Junggar into two types,i.e.,the Early Paleozoic porphyry copper deposits and the late Paleozoic porphyry copper deposits.On the basis of a detailed analysis of the basic geological features of various types of metallic deposits(ore spots),three mineralization concentrated areas were recognized,namely Kalaxianger,Wulunbulake and Quheba porphyry ore belts.The relationship between the regional crustal evolution in East Junggar and the metal mineralization was also studied.The results indicate that,although the mineralization of metallic deposits(ore spots) in the study region occurred in Early Paleozoic and Late Paleozoic,it was the early Paleozoic orogeny and the late Paleozoic orogeny that formed the Sawuer late Paleozoic island arc and Zhifang— Qiongheba Early Paleozoic continental island arc.The porphyry mineralization occurred in favorable orogenic areas.The period of the plate tectonic activity was coincident with the peak period of large-scale mineralization,which constituted a specific evolutionary stage of crustal tectonic magmatism.