The Recognition And Applications Of Altered Mineral Assemblage Which Based On Infrared Spectrum

Porphyrydeposits and epithermal deposits which are considered to have transitional and symbiotic relationshipspatiallyare always been thefocus of the geologist.The Tiegelongnan copper(gold)deposit which characterized by the late high-sulfidation epithermal mineralization over the early porphyry mineralization is the first super-large copper(gold)deposit discovered in the Tibet Plateau.Based on the exploration from 2013 to 2015,the amountofthe controlledresource of Cu is over 11 million tons associated with more than 120 tons of Au and the prospecting resource of Cu is also more than 15 million tons.Therefore,TheTiegelongnan depositis called the largest single copper(gold)deposit in our country.As a kind of prospecting method,the infrared spectrum can help the geologists in identification of altered minerals and efficient prospecting,because of the relationship between the mineralization and altered minerals.By means of shortwave infrared technology and thermalinfrared technology,we work on the samples from the drill holes(ZK0804,ZK1604,ZK2404 and ZK3204)and ground in the Tiegelongnan deposit and consequently,build up an infrared spectroscopy prospecting model which can provide some advice for exploration in depth and external of the Tiegelongnan deposit.Finally,some conclusionsare listed as follows:1.The alteration minerals such as kaolinite,alunite,dickite,pyrophyllite,muscovite,gypsum,diaspore and montmorillonite were identified in the drilling core samples by short wave infrared spectroscopy.These alteration minerals which are the result of the acidic-strongacidicleachingare distributed in the mid-top core of the drill holes,represented the high-sulfidationepithermal mineralization.2.Bymeans of the Fourier thermal infrared analysis,alteration minerals which include biotiteamphibole,FeMg-chlorite,Fe-chlorite,rutile,andbytownitearefounding the bottom of the drilling core.Moreover,the biotite and amphibole increasedgradually along with the depth.This kind of biotitization and silication indicate a good prospecting of porphyry mineralization in depth.3.The shortwave infrared spectroscopy characteristics of the surficial rock samples shows that the alteration mineralsof the surface are mainly composed of anhydrite,diaspore,kaolinite,phengite,montmorillonite,alunite,halloysite and illite.In addition,these alteration minerals together form an alteration zoon which centres on the anhydrite and diasporeand is surrounded by the alunite,kaolinite,phengite,montmorillonite,muscovite and illite.The boundary of the alteration zoon constrain on the size of the orebody.4.According to the achievement we have made,this article attemped to modeling the infrared spectrum exploration.In vertical direction,aggregates of carbonate+clay m inerals represented by alunite+kaolinite developed in shallow part may indicate the ex ist of epithermal deposits.With depth going down in the drill hole,alteration mineral as semblage would changed into hornblende+ biotite,and it shows a trend of keep changi ng.This promised the presence of pyromagma and hydrothermalgenesis in depth.All t he evidences can confirm and support the dual structure of ore bodys in Tiegelongnan mining area.5.Combine the sueface and drilling core,the alteration of mineral identification and research showed a huge potentiality of prospecting in deep(edge)mining area.