Geological Characteristics Of The Gariatong Granite Type Rubidium Polymetallic Deposit In Tibet

Gariatong rubidium polymetallic deposit is located in the middle of Lhasa block,which is the first giant granite type rubidium deposit in Tibet.However,limited by geographical location and other factors,the research and exploration degree of this mine is not high at present,and the diagenetic and metallogenic age,rock geochemical characteristics,occurrence state of rubidium and the genesis of the deposit are not clear.In this paper,according to the latest exploration results of the mining area,on the basis of detailed geological survey and previous research results,the borehole geological catalogue is carried out.By means of microscopic identification,electron probe analysis,zircon U-Pb dating and element geochemical analysis,the geological characteristics,diagenetic and metallogenic ages and geochemical characteristics of the deposit are further supplemented and improved,and the genesis of the deposit is finally discussed.The main achievements of this research are as follows:The rubidium ore body in the mining area is mainly in the form of rock strains in monzogranite,and the rock mass is the ore body.Its emplacement crystallization age is 20.95 ～ 18.8 Ma,which is the product of Miocene magmatic activity.The geochemical characteristics of the rocks show that the monzogranite belongs to the peraluminous high potassium calc-alkaline potassic pluton granite,which is characterized by high silicon,rich in aluminum,poor in iron and magnesium,and high differentiation.It is obviously enriched in light rare earth elements,depleted in heavy rare earth elements,and has obvious negative Eu anomaly.Its origin is S-type granite formed after remelting from crustal origin.The characteristics of alteration and mineralization reveal that the alteration types are diverse and widely distributed in the area,and the main alteration types are greisenization,Muscovitization(sericitization),biotitization and fluorination.Among them,Muscovitization and greisenization are most closely related to mineralization.Electron probe analysis revealed that rubidium mainly exists in Muscovite and biotite.In conclusion,the Gariatong rubidium polymetallic deposit is a reduced felsic magma formed by partial melting of the middle and upper crust materials under the extensional background of the collision between the Indian plate and the Eurasian plate.After the long-term evolution and crystallization differentiation,it forms a shallow emplacement of highly differentiated granite.At the same time,the rare element(Rb)is enriched into the hydrothermal fluid by the complexation of volatiles such as fluorine during the magmatic evolution process and is enriched in the Muscovite and biotite in the form of isotropy.Finally,granite-type rubidium ore body is formed in the granite top and surrounding rock.The discovery of Gariatong rubidium polymetallic deposit reveals that the high differentiation of peraluminous crust-derived granite in the central Lhasa terrane of Tibet has a good prospecting prospect for rare metals such as Rb,and it is expected to find more high-quality rare metal deposits,which will provide important resource guarantee for the Tibetan Plateau and national key metal reserves and economic development.