Geological Characteristics And Genesis Discussion Of Tongshancopper Depositin Shangrao Jiangxi Province

The Tongshan copper deposit in Shangrao city Jiangxi province locates in north wuyi copper polymetallic metallogenic belt.This article is under the foundation of detailed field and mine geological survey for Tongshan copper deposit,through studying and summarizing,and acquires some achievements and cognition in the aspects of mineral composition and structure characteristics,the magmatic source of the metallogenic rock,the deposit metallogenic periods and phases,skarn mineralogy characteristics,the controlling factors of deposit and so on.Tongshan copper mine is similar with many large ore deposits in the area,belongs to the porphyry-skarn type copper deposits.In Yanshan period,the mining area occurred magmatic activity,formed the quartz monzonitic porphyry intrusive body,in the contact zone of the rock mass and the stratum,formed skarn copper deposits.Nappe structure and the fold,slip generated by it are the important rock and ore body controlled structure,strata controls the occurrence and distribution of ore body.On the whole,rock and ore bodies distribute in the north-east orientation.The metallogenic rock quartz monzonitic porphyrybelongs to the syntexis-type granite,forms in the island arc tectonic environment,related to the ancient subduction of the Pacific plate.In rock mass,can find many dark grey basic inclusion and hornfels xenolith,which indicates multiple magma intrusion activity.The plagioclase which has band structure in tongshan rock mass belongs to neutral Plagioclase,in the Or-Ab-An diagram,all the data points fall on andesine And area.From the core to the edge of crystal,the content of An and FeO changes in the same direction,especially in the ninth point,FeO content fells sharply,that means magma composition have changed,and it was caused by acidic magma from the earth adding into the mantle basic magma.In the ?Hf(t)—t graph,most pointsof zircon ?Hf(t)fall in between chondrites and depleted mantle,few fall into chondrite area,has a larger range,which indicates that in the process of magma formation,there was magmatic mixing.The range of S isotopic composition characteristics of main metal mineral is narrow(-1.6 ‰~1.2 ‰),the average is-0.32 ‰,close to zero,histogram distributes to tower significantly,and is similar with magmatic ?34 S(0±3 ‰),shows that S may mainly came from the mantle,the ore-forming material was brought by the deep magma.In south China,there was largescale metal mineralization happened in Mesozoic yanshan period.Between 170~180 Ma,southern China was in the local extension environment,tongshan copper mine was formed under this metallogenic dynamicshe background.Around 170 Ma,quartz monzonitic porphyry intruded along the limestone decollement layer which caused by nappe structure,occurred metasomatism in contact zone,intrusion mass provided ore-forming material sources for the deposit,slip bands provided space for the ore bodies,and eventually formed the tongshan copper deposit.