Badanina and three co-authors reported in 2016 that the composition of melt and its evolution in space and time is traced at formation of ore-bearing Li-F granites and them sub-effusive analogs (ongonites, rhyolites, felsite-porphyries) from Orlovka, Etyka and Sherlovaja Gora in Transbaikalia (Russia) on the basis of melt inclusions study in quartz [1]. It is established that process of fractional crystallization is not the unique mechanism of concentration of LILE (Li, Rb, Cs) and HFSE (Nb, Ta, Zr, REE, W, Sn).
A role of various mechanisms of concentration (fractionation, liquid immiscibility, metasomatism) estimate by calculation of distribution coefficients and saturation degree of melt for ore minerals. Contrast behavior of various rare elements is established at different stages of melt evolution [1]. High concentration of Li, B, Ta, Zn are found out in hypersaline and fluid inclusions of Orlovka [2]. High concentration of some rare elements are found out in fluid inclusions (FI) in quartz from Sn-bearing rhyolites of Sherlovaya Gora by LAICP- MS.
So, the Sn concentration varies from 1864 to 5879 ppm that explains formation of large tin deposit with finely dispersed cassiterite at a hydrothermal stage. High concentration of Zr in a fluid (to 1,5 wt %) from ultrapotassic felsite-porphyry explains the formation here saturation zones of fine crystalline zircon in a topaz from famous a topaz-aquamarine greisen of Sherlovaya Gora and confirms probability of its crystallization at a hydrothermal stage. High
uranium concentration in melt of rhyolites (up to 42 ppm U) exceed those in rhyolites of a Streltsovsky deposit. Sharp increase of U in FI up to 116 ppm unequivocally testifies to a potential role of rhyolites in genesis of uranium deposits of Transbaikalia that closes discussion about a source of uranium
for them.
[1] Badanina et al. (2010) Petrology. 18. 139-167.
[2] Thomas et al. (2009) Min Petrol. 96. 129-140.
Managed & Built by I2M Consulting, LLC | © 2010-
