The Genesis Of Picrite Porphyry And The Metallogenic Significance In Sichuan Kuangshan Liangzi

Although the formation of the Pingchuan and Panzhihua Fe deposit has relationship with largescale basalt eruption and basic-ultrabasic intrusion,the two deposits have some big differences.Furthermore,the cause of picrite porphyry has not been received consideration by the researchers.So we focus on the origin of picrite porphyry and the relationship with that of the Pingchuan Fe-deposit.We select olivine as study object in Pingchuan Fe-deposit,Yanyuan area,Sichuan province,and analysis some rock forming minerals and auxiliary minerals by Electron Probe X-ray and major elements of whole rocks based on petrography observation,aiming to reveal the magmatic processes and that of physics and chemistry conditions.As a result,olivine can be divided into four types: coarse-grain olivine,fine-grain olivine,inclusions-rich olivine and spinifex texture olivine.Different genetic types of the olivine crystals belonging to different crystal groups,and these are circular crystal,residual crystal,and matrix of crystal,respectively.Therefore,this suggests that parts of olivine in Mg-rich picrite basalt are may not producted by primary magma crystallization but experenced very complex history.Different types of olivine has formed different temperature.The highest temperature of the formation of microcrystalline olivine is 1335?.The initial crystallization temperature of coarse grained olivine is low about 1295?.Inclusions-rich olivine is about 1292?,but olivine crystallization temperature does not change,shows the relatively stable characteristics.“Spinifex” olivine initial crystallization temperature is relatively low of 1272?,but with olivine crystals,the temperature decreased steadily,shows the continuous crystallization state that “spinifex” is the product of olivine picrite porphyrite magma crystallization.In addition to the original inclusions in olivine,the other three types of crystallization temperature of olivine edge is similar to the show before the final consolidation diagenesis after magma mixed formation of picrite porphyrite we see today's.Volume content of olivine phenocrysts with CSD olivine spot.Other sources of crystal cut.Namely coarse grained olivine,microcrystalline inclusions of olivine and Peridot,in addition to retain the“spinifex”olivine.Olivine can be found after removing SiO₂ content of picrite porphyrite is 48.41%,the primary magma is not picritic magma is picrite porphyrite.This suggests mother magma of the picrite porphyry was not consolidated in a closed system,but was likely to be in an open system which has experienced magma injection with a certain amount of olivine once or several times.Consequently,the ore-rich fluids of the Kuangshanliangzi Fe-deposit raise making use of picrite mass bedrock which can be regarded as a magmatic channel.After that,the fluids and magma were decoupled at the bottom of the KuangshanLiangzi stopped and finally formed ore bodies.