Research On The Genesis And Prospecting Direction Of Liwu Cu-Zn Deposit

The Liwu Cu-Zn deposit is a typical medium-sized polymetallic deposit in the west of Sichuan province,which located in the west of Kangdian Earth's axis,the south edge of Songpan-Granze orogen and the northwest of Muli-Jinping arc thrust tectonic zone,and the deposit is the part of paleoproterozoic Cu-Zn polymetallic metallogenic belt of Jiulong-Muli metamorphic-thrust complex zone.Study on the geological characteristics of Liwu deposit and link with the former research fruit in the area,the paper indicated that Liwu group in the central portion of Jianglang dome tectonic is the ore-bearing layers of the deposit,which is a formation of marine volcanic-turbidite clastic rocks.The footwall of metamorphosed basic volcanic rocks-subvolcanic rocks indicates that the mineralization have relation with the space and the genesis of the intrusions.The paper indicates that the Liwu Cu-Zn deposit has polygenetic based on the research of isotope and fluid inclusions,the originality ore-bearing layers formed from Meso-Neoproterozoic clastic rocks which sedimented in the rear-arc basin environment,and have been effected by many Magmatic-tectonic movement later.The most ore matter are characterized with deep focus,the sulfur element derives from upper mantle and mixed with seawater sulfur latterly,the ore-forming fluid is composed mainly with magmatic water and metamorphic water,which mixed with seawater and atmospheric water little,the Liwu Cu-Zn deposit is featured with sea facies volcanic clastic-metamorphic genesis.The Liwu Cu-Zn deposit is in the outside of Jianglang ore filed,the ore body are ranged bedding and imbricate which controlled by tectonic obviously.The mineralization which controlled by the tectonic gyration are featured with polyphase, and the mineralization are divided into three phases based on the isotope dating and the microphase research.The tectonic movement resulted in transgression in ordovician period(471～473Ma),and in this time there had a series volcano-clastic rocks sediment in the area.The late Indosinina-early Yanshan stage(184～191Ma) is the tectonic deformation era of the Jianglang metamorphic core complex,and in which time Jianglang metamorphic core complex uplifted by the Songpan-Granze orogen.Because of the east-west ductile deformation,there formed the surge belt and the drape belt which were the good tectonic space for ore fluid moving and depositing in the metamorphic core complex.The middle-late Yanshan stage(133～143Ma) is the most important phases of mineralization in which there had a lot of tectonic movement in the area.The extentional movement of the terrane relived the former ductile structure,and all the faulting were good for the movement and the deposit of the ore fluid,the ore fluid formed the industrial sulfide deposit when it coupling coexistence with structure and other factors.According to the ore prospecting sign,such as regional geologic,geophysical exploration,chemical exploration,and Remote-sensing anomalies,and apply the comparability-analogy rules,it is thought that the areas,which are the deep and outskirts of Liwu Cu-Zc deposit,and Changqiang metamorphic core complex etc are the perspective area of mineral prospecting.