Environment Properties Model Of Duobuza Cu(Au) Deposit,Tibet

Duobuza Cu(Au)deposit is located in the territory of Gêrzê County in the Ali district of Tibet,it is the first large-scale porphyry copper deposit discovered in the central Tibetan plateau,and the current copper resource amounted to 2.34 million tons.Duobuza deposit has not yet been developed,the studies of the deposit are limited to geological mineralization and prospecting,it has not been studied on the environmental properties.To fully understand the impact of Duobuza deposit on the surrounding environment before development,this article conduct a study of its environmental properties,and establish the ?Environment Properties Model of Duobuza Cu(Au)Deposit in Tibet?,and provide scientific basis for future green development of Duobuza deposit.The main conclusions of this paper are as follows.(1).The main ore-bearing rock body of Duobuza deposit is granodiorite porphyry,the main metal minerals in the ore include chalcopyrite,pyrite,limonite,bornite,magnetite,lancosite,etc.The alteration minerals found in borehole core by PIMA tests mainly include illite,kaolinite,muscovite,dickite,chlorite,etc.(2).The p H value of the Samalong River is between 7 and 9,which belongs to alkaline water.The EIA results indicate that the water quality of the river is in good condition.The evaluation results of single contaminative index show that the pollution elements in the soil sample of upper,middle and lower reaches of the Samalong River are Cu,As and Cd elements.The percentage of lightly polluted and moderately polluted Cu in the upstream soil was 68% and 23%,respectively.Soil is only slightly polluted by Cu element in the middle and lower reaches,with proportions of 36% and 9%,respectively.The contamination elements in surface soil samples of Duobuza deposit are Cu,Pb,Zn and Cd elements.The proportion of Cu elements in mild polluted,moderately contaminated,and heavily contaminated soils is 10.8%,21.6% and 67.6% respectively.The comprehensive evaluation results show that 59% of the soils in the upper reaches of the sarmalong River are poor and extremely poor;the soils of the middle reaches are all better,the soil quality is obviously better than the upstream;all the soils in the lower reaches are better,and the soil quality is equivalent to that in the middle reaches,which is obviously better than that in the upper reaches.About 95% of the surface soil samples are extremely poor,and 5% of the samples are poor.The pollution degree of surface soils is much greater than that of river soils.(3).The total amount of metallic Cu released to the environment since Duobuza-Bolong deposit was formed is approximately 652,500 tons,equivalent to the reserves of a large copper deposit;the content of metal Cu in the Quaternary sediments is about 3292.3 tons;the content of metal Cu in river sediments is about 85.5 tons.We speculate that most of the metal Cu released by Duobuza-Bolong deposit has been deposited in the Biecuo lake.(4).Through speciation analysis of heavy metals,the contents of Cu,Pb,Zn,As,Cr,and Hg in river soils mainly exist in the form of residue,iron-manganese oxidation,strong organic and humic acid,and he sum of the proportions of the more stable forms of these elements is more than 90%,they are only potentially harmful to the surrounding environment.The Cd element is mainly in the form of carbonate in the river soil,accounting for 48.64%,and that is easy to harm the environment.The results of the morphological analysis of the seven metal elements in the upper,middle and lower reaches of the Samalong River are consistent with the results of the overall analysis of the river soil.The Cu and Cd elements in the surface soil mainly exist in the form of iron manganese oxide,the elements Pb,Zn,As,Cr,and Hg exist mainly in the form of residuals,they are only potentially harmful to the surrounding environment.Through comparative analysis,the changes in the content of seven forms of metal elements in river soil and surface soil are basically the same.(5).Through factor analysis,eight variables in Samalong River soil are represented by three factors after analysis by the main factor,F1(Cr-Pb-As)is the most important factor.The eight variables in surface soil are represented by four factors after analysis by the main factor,F1(Cr-Hg)and F2(Cu-Zn-?As?)are two important factor.Through factor analysis of seven forms of heavy metal elements,the most important factor of Cu in river soils is? carbonate state-humic acid state-ferromanganese oxidation state-strong organic state-residue state?,they have a good positive correlation with each other;the most important factor of Cu in surface soils is? water soluble state-carbonate state-strong organic state-residual state?,they have a good positive correlation with each other.(6).Through the study of ore body,mineralization characteristics,rock and mineral facies,wall rock alteration,heavy metal release,heavy metal element geochemistry,and metal element morphological characteristics of Duobuza porphyry copper deposits,we have established the mineral deposit environment attribute model before the development of the deposit,thus provide scientific basis for future green development of Duobuza deposit...