The Regional Hydrothermal Alteration Characteristics In The Eastern Section Of Gangdise

The eastern part of the Gangdise metallogenic belt covers more than 10 counties of Lhasa city,Shannan city and Linzhi city,the total area of 22,000 km~2,involving 511:50,000 maps.Based on the data of the data from regional geological survey,geological mine survey,mineral exploration,the single type alteration map is drawn by analyzing the alteration information.the formation of alteration temperature type map is drawn according to the integrated project remote sensing alteration information results and alteration temperature into the alteration temperature type.Then,according to the alteration temperature type space superposition,the alteration combination type is determined to form the alteration combination diagram.At the same time,mineral information layer is compiled after precipitation of mineral information and combing of the type of mineral combinations and genetic types.Then,the alteration information is compared with the mineral information to determine the validity of the alteration information mining,and finally conclusions are as follows:The determined alterations by regional geological survey,geological mine survey,mineral exploration consist of tremolite,albitization,K-feldspar,Muscovite,actinolitization,biotitization,silicification,sericitization,chloritization and epidotization,zoisitization,kaolin,clay,hornfel,fluoritization,barite.The identified alteration information by remote sensing consisit of aluminum hydroxyl,magnesium containing,silica,which correspond to(1)kaolin,montmorillonite,dolomite,alunite,illite,(2)chlorite,and epidotization,(3)silicification.Obove alterations are divided into high temperature,medium temperature,medium-low temperature,low temperature.Alteration types include high-medium-low temperature,low-high temperature,low-medium temperature,medium-high temperature,medium-low temperature,medium temperature,high temperature,low temperature.There are 360 mineral data expect for chromite ore from regional geological survey,geological mine survey,mineral exploration,which include 7 super-large deposits,8 medium deposits,9 small deposits,45 ore-spots,291 mineralized spots.These mineral data are divided into copper polymetallic mineral resources(201),Pb-Zn-Ag polymetallic mineral resources(51),gold polymetallic deposit(42),molybdenum polymetallic mineral(40),iron polymetallic mineral resources(26),other 5 kinds of minerals combination type.There are 3 genetic types:skarn type(22),porphyry type(40)and hydrothermal type(298).The rate of single alteration information,which covers the proportion of known endogenetic minerals,is generally low,and covers well with 55%(62%),epidote(48%),silicification(44%),and sericite(sericite).The types of alteration temperature have greatly increased the coverage ratio of known minerals,which are high temperature hydrothermal alteration(90%),moderate temperature alteration(91%),low temperature alteration(92%),low temperature alteration(95%).After the combination of different temperature types,all known endogenous minerals are included,covering all deposit are combined low temperature high medium,but different types of alteration assemblages covering known mineral resources situation is different:the copper polymetallic ore,high-medium-low temperature,including 159spots,accounting for 79%;low-medium temperature,including 26 spots,accounting for 13%;medium-high,medium-low temperature,including 4 spots respectively,accounting for 2%;high,moderate,low temperature,including 1 spots respectively,accounting for 0.5%;low temperature,including 5 spots,accounting for 2.4%.The Pb-Zn-Ag polymetallic ore show the following characteristics:high-low temperature,including 44 spots,accounting for 84.6%;low-temperature,including 6 spots,accounting for 11.5%;high,moderate,low temperature,including 1 spots respectively,accounting for 0.5%;low temperature,including 5 spots,accounting for 2.4%;medium-low temperature,low-high temperature,including 26 spots respectively,accounting for 1.9%.Gold polymetallic ores show the following characteristics:high-medium-low temperature,including 39 spots,accounting for 95.1%;high-medium temperature,moderate-low temperature,including 1 spots respectively,accounting for 2.4%.Iron polymetallic ores show the following characteristics:high-medium-low temperature,including 34 spots,accounting for 85%;medium-high temperature,low-medium,low-high,high temperature,moderate temperature,low temperature,including 1 spots respectively,accounting for 2.5%.Tungsten molybdenum polymetallic ores show the following characteristics:high-low temperature,including 21 spots,accounting for 80.6%;low temperature,high temperature,including 1 spots respectively,accounting for 3.8%.The above characteristics show that the alteration assemblage indicates ore-bearing potential well.