Granitoids of the Altakhta Сomplex, the Eastern Part of the Bureya Continental Massif, Central Asian Fold Belt: Age, Geochemical Features, and Geodynamic Interpretations

New data are reported on the age, composition, and formation conditions of the Late Triassic granitoids of minor intrusions from the eastern part of the Bureya continental massif of the Central Asian fold belt, and their geodynamic interpretation is given. U–Pb geochronological zircon studies indicate that the rocks of the Altakhta syenite–leucogranite complex were formed in two phases within 235–224 Ma. The first phase (235.3 ± 2.9–230 Ma) was responsible for the formation of magmatic rocks that are similar to the А 1 -type intraplate granitoids in terms of geochemistry and resemble subduction- and collision- related granitoids in terms of REE composition. The second phase (226–224 Ma) produced granites similar to А 2 -type and А 2 + I and S-types. A combination of within-plate and subduction signatures and the presence of A, I, and S-type rocks of similar ages in this complex supports their formation in a transform continental margin setting.