Geochemical behavior of phosphorus and its implication for lithium mineralization in the pegmatite-type lithium deposit in Altai,Xinjiang
The Altai orogenic belt is an important pegmatite-type rare metal metallogenic belt,with multiple pegmatite-type lithium deposits of various scales in Xinjiang,China.Currently,it is unclear about geochemical behavior of phosphorus during the magma-hydrothermal evolution and its indicative significance for lithium mineralization.This paper conducted a comparative study on the microstructure and chemical composition of phosphate-bearing minerals such as alkaline feldspar,apatite and lithiophilite(triphyline)in the Koktokay No.3 pegmatite,Xiaohusite No.91 pegmatite and Talati No.1 pegmatite,aiming to explore the above mentioned scientifical issues.The research results show that phosphorus gradually accumulates in the residual magma with the magma fractional crystallization.When it reaches a certain extent,immiscibility occurs between the phosphate melt and the silicate melt,and Li is preference for entering into the phosphate melt,leading to the formation of lithium-rich phosphate minerals such as lithiophilite(triphyline).The crystallization of Mn-rich apatite with skeletal texture in the zone Ⅱ of Koktokay No.3 pegmatite may be attributed to rapid crystallization caused by magma undercooling.Moreover,the already formed lithiophilite(triphyline)are easily altered by the exsolved magmatic fluids in the later stage,resulting in a series of complex secondary phosphate minerals.
Magmatic-hydrothermal evolution processLithium mineralizationPhosphate-rich mineralsAlkali feldsparPegmatite in Altai
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维普
