Research On Alteration Zone Of The Duobaoshan Porphyry Copper Deposit,Heilongjiang Province

The Duobaoshan copper deposit in Heilongjiang Province is one of the most important porphyry copper-molybdenum deposits in the eastern part of the Central Asian orogenic belt.The wall rock alteration of the Duobaoshan copper deposit is characterized by typical alteration of the porphyry deposit,but the clay belt is not developed in this deposit.In this paper,we study the element migration and mineral chemical characteristics of the alteration zone,and achieved the following results and awareness.In the formation of the alteration zone,the active elements show different characteristics of the element migration in different alteration zones:In the silicified belt,SiO₂,CaO,K₂O,Sb,Sr moved into,Fe₂O₃,MgO,TiO₂,Bi,Co,Mn,Mo,W,Zn,Rb and?REE were brought out,and the depletion is obvious.In the potassium alteration zone,the CaO,Na₂O,Mo,Bi and Sr are obviously introduced,while Fe₂O₃,MgO,TiO₂,Cu,W,Co,Zn,Mn,Rb and?REE are obviously poor.In the belt of sericite-quartz alteration,the Fe₂O₃,CaO,K₂O,Cu,Mo,Bi,W,Co,Zn,Mn,Sb are obviously brought in,and the Na₂O and?REE are taken out obviously.In the propylitic zone,Fe₂O₃,CaO,Na₂O,TiO₂,Cu,Mo,Co,Mn and Sr are obviously brought in,while W,Rb and?REE are obviously poor.The rare earth elements in the all alteration zones show obvious feature of being taken out,in overall trend,in silication and potassium belt,the rare earth elements have been taken out most obvious and exhibit similar characteristics in migration,in other alteration belts,the amount of light rare earth elements has been taken out is more than heavy rare earth.Ore-forming elements Cu were taken out in potassium belt.In sericite-quartz and propylitic belt Cu was brought into.In sericite-quartz belt,Cu was taken in most obvious,and in the favorable conditions of construction,the enrichment of Cu lead to the formation of industrial orebody,the second is propylitic belt.Mo moved out obviously in the process of granodiorite silicided,Mo was brought in by the process of potassium,sericite-quartz and spropylitic,the potassium rock brought Mo into biggest,spropylitic and sericite-quartz belt is the second.By analysising mineral chemical characteristics of biotite from granodiorite i got the rock mass emplacement and diagenetic temperature is between 550??650?.According to biotite calculated pressure we get the average diagenetic pressure of rock mass is about 2.39 x 10⁸ Pa,the corresponding average diagenetic depth is about9.04 km.And the source region of magma is a mixture of the crust and mantle.When biotite in the process of the chloritization,Si obviously moved out and entered the fluid.Migration of Al and Mg are not obvious.The Fe was obviously introduced,and part of Fe in chlorite is inherited from the biotite,the rest part from the external hydrothermal fluid.All of the K moved out into the fluid.In the process of the sericitization of plagioclase,sericite inherited most of the Si from the plagioclase,and the rest part of Si is brought out into the fluid.Ti is introduced into the sericite.Most of the Na moved out from the plagioclase to hydrothermal fluid.Mg and K are obviously brought in.Al content level increased,not very much.The Ca in plagioclase was brought out,and leaded the Ca content level in sericite to almost be zero.The Fe was obviously brought in from the external fluid.