Alekseev, et al., report that accessory mineralization of the Late Cretaceous intrusive series in the Far East in Russia was investigated on the basis of published data and the author’s original evidence. The composition of accessory minerals from leucogranite, monzonitoid rocks, and Li–F granites has been established. The trend in the evolution of Late Cretaceous granitoids is characterized by an increase in the mineral-forming role of iron and rare elements.
Diverse accessory minerals and their typomorphic assemblages have been identified for Li–F granites and ongonites. The regional specificity of accessory mineralization in raremetal granites consists in the leading role of the minerals W, Ta, Nb, Bi, Y, REE, and As. The uniformity of mineral species and mineral assemblages and the typomorphism and evolution of accessory minerals are inherent to the Far East belt of Li–F granites.
The authors concluded that:
1) The evolution of accessory mineralization in Late Cretaceous raremetal granitic series is directed toward increase in mineral-forming role of iron and rare elements (W, Ta, Nb, Bi, Sn, F, Li, Y, HREE). The early leucogranites and monzonitoid rocks contain zircon, ilmenite, apatite, allanite(Ce), monazite, xenotime, titanite, rutile, and garnet. The late and greizenized intrusive phases are characterized by appearance of or enrichment in fluorite, topaz, tourmaline, cassiterite, pyrophanite, thorite, wolframite, pyrochlore fergusonite, and other rare-metal minerals. Monzonitoid rocks are distinguished by elevated contents of malacon, apatite, Th and Y-bearing REE phosphates and silicates. Li–F granites and ongonites as final members of intrusive series are sharply distinguished by abundant rare-metal minerals, primarily, W-bearing tantaloniobates in the absence of apatite and allanite(Ce).
2) A raremetal composition and extremely diverse accessory mineralization have been established for Li–F granites and ongonites of the Far East. The main minerals are topaz, fluorite, cyrtolite, monazite (Ce), W–Nb-ilmenite, and W–Nbrutile. The auxiliary mineral species are wolframoixiolite, ferberite, amblygonite, samarskite(Yb), ishikawaite, bismutopyrochlore, ilmenorutile strüverite, columbite(Fe), allanite(Y), etc. The rare minerals are fluocerite (Ce), tveitite(Y), gadolinite, gananite, gahnite, bismuth, etc. The tungsten, tin–tantalum–niobium, niobium–titanium, bismuth, and mixed As–Y–REE–U mineral assemblages are typomorphic. Wolframoixiolite, Nb-ferberite, allanyte(Y), and chernovite(Y) are typomorphic minerals.
3) The uniform composition of accessory mineralization contained in the Late Cretaceous granitic rocks of the Far East is strikingly expressed in identity of rare-metal mineral assemblages of Li–F granites and ongonites. The speciation, parageneses, main typomorphic features, and tendencies of accessory mineral evolution steadily repeat in raremetal granites over the entire Far East from Primorye to Chukchi Peninsula, reflecting the genetic and compositional uniformity of the Late Cretaceous raremetal magmatism. The main regional features of accessory mineralization in Li–F granites are expressed in (i) leading role of W, Na, Nb, and Bi minerals; (ii) W and Sc admixtures in accessory minerals; (iii) prevalence of Nb over Ta; and (iv) obvious contribution of Y, REE, As, Th, and U minerals. The uniform accessory mineralization in Li–F granites over vast territory of the Far East is evidence for existence of the raremetal granitic subprovince, or the Far East belt of Li–F granites.
Managed & Built by I2M Consulting, LLC | © 2010-
