Age and Isotope-Geochemical Characteristics of Ta, Nb, W, Sn Mineralization Associated with Rare-Metal Granites (Khangilay Ore District, Eastern Transbaikalia)

Abstract

The age relations between the formation of the parent massif and the crystallization time of the associated ore mineralization were established based on isotope-geochronological study of the massif-deposits of the Khangilay ore cluster with various metallogenic specialization in Eastern Transbaikalia. In the Orlovka Li–F granite massif, the crystallization time of columbite–tantalite (145 ± 1 Ma) and cassiterite (144.2 ± 0.3 Ma) (U-Pb, ID-TIMS) is almost identical to the crystallization time of zircon (140.6 ± 2.9 Ма (U-Pb, SHRIMP) and 145 ± 1 Ma (U-Pb, CA-ID-TIMS)), which is an age marker of the formation of massifs. This fact testifies to the magmatogenic nature of rare-metal mineralization. In the Spokojnoye massif – the “standard type” of rare-metal peraluminous granites—a 0.6–3.8 Ma time gap was revealed between the time of massif formation (141.3 ± 1.8 Ма, U-Pb, SHRIMP, 146.9 ± 0.7 Ма, Rb-Sr isotopic system) and crystallization of wolframite (141.8 ± 0.6, Rb-Sr isotopic system and 140.1 ± 1.4 Ма, Sm-Nd isotopic system). This interval likely corresponds to the life time of the hydrothermal system, which produced tungsten mineralization.