Characteristic And Prospecting Significance Of Granite In The Jiajika Rare Metal Mining Area Of The West Sichuan

Sichuan Jiajika granitic pegmatite type rare metal mining area is the largest rare metal mining area of China, with complete Li-Be-Nb-Ta metallogenic series, and the area of rare metal deposits has the characteristics of rich taste, minerals, buried in shallow, good processing performance, on behalf of the geological characteristics of strong, is the ideal object of pegmatite type rare metal deposits. Due to previous studies of this area are mostly concentrated on the pegmatite deposit, of this area only with the pegmatite has a close temporal and genetic relationships of granite research degree is relatively weak. This author based on field geological survey, through systematic sampling and analysis test, of granite and rock in the mining area geology and petrology and zircon U-Pb geochronology, geochemical characteristics of granite and pegmatite for detailed study, combined with previous research results, in order to analyze the granite rock genetic types and tectonic background, has carried on the discussion to the magma source and genesis of magma, and makes a further discussion on the relationship between rock mass and rare metal pegmatite, The main achievements are as follows:1.Thelithology of Jiajika granite is containing tourmaline fine-grain two mica granite, and rare metal pegmatite veins in grantie as the center is asymmetric centrifugal zonal distribution and a large number of development.2.The LA-ICP-MS zircon U-Pb dating of the grantie indicates that the age of the Jiajika two mica granite is 223+ IMa. According to the dating results, Songpan-Ganzi orogenic belt in late orogenic extensional gellon time should be about 220Ma.3.The geochemical characteristics of Jiajika grantie is rich in silicon, high potassium, high aluminum and alumina saturation index showed strongly peraluminous rocks, and in the calculation of the CIPW normative minerals, there were quartz and corundum. The total rare earth less, the distribution curve shape presents right mode that light REE relative enrichment and heavy REE relative loss. With moderate negative Eu anomalies and no significant Ce anomaly, primitive mantle normalized spider diagram curve shape is similar, showing an overall features of tilted to the right, and has the characteristics of "multiple peaks and valleys'4.Jiajika grantie belongs to S-type granite, and Muscovite peraluminous granite (MPG), formed in the later stages of the same collision, which means the crash after the back collision extensional transition period and has the characteristics of tectonic background of continental collision granite. Jiajika grantie's source rocks are rich clay argillaceous rocks, which from partial melting of Xikang Group mudstone and sandstone, and Jiajika grantie is the product of the Songpan Garze orogenic belt in late Indosinian large-scale detachment push orogeny stage, crustal continuous thickening and partial melting.5.The geochemical characteristics of different types of pegmatite performance for silicon rich and poor potassium, high aluminum and alumina saturation index showed strongly peraluminous rocks, and differentiation index mean value is 93.14. In the calculation of the CIPW normative minerals, there were quartz and corundum.The different types of pegmatite have the same major element characteristics, and belongs to the crystallization of diversity to a very high degree of low potassium calc alkaline strongly peraluminous granite. According to the different types of pegmatite rock major element covariance plots, different types of pegmatite are not the same parent magma in sequence evolution results. Total REE content is very low, with the enrichment of light REE coordination model feature points and different types of pegmatite characteristics of rare earth elements and remelting magma points shaped pegmatite similar. The total amount of rare components increased with the evolution of the potential, and the basic elements of the formation of the corresponding evolution of the corresponding sequence.6.Different containing ore pegmatite veins is approxi mately centrifugal zonal distribution around the two mica granite, and both in geological and geochemical characteri stics are in line with Li-F granite magma liquid immiscibl e based liquid separation characteristics, which are cognat e magma liquid immiscibility for under the main liquid se paration of two conjugate magma group points.7.By researching of rocks and pegmatites of Jiajika, can establish the metallogenic geological conditions of rare metal pegmatite type deposit, which the search for similar deposits has important guiding significance in the area of the Western Sichuan (Songpan-Ganzi orogenic belt).In the Songpan-Ganzi orogenic zone, emplaced in the late Indosinian 220Ma granite rocks many, and Jiajika rock with similar petrogenesis, tectonic setting and geochemical characteristics of the granite rocks is also a lot. Based on this, divided three rare metal for prospecting area, Wanlicheng and Ermaoshan prospecting area, Yanggonghai prospecting area, Rongxuka and Changzheng prospecting area, to provide the basis for the exploration of rare metals in the area.