U–Pb zircon dating by laser ablation and sector-field mass spectrometry with inductively coupled plasma (LA–SF-ICP-MS) is an accessible local method with easy sample preparation. At the Geological Institute, Ulan-Ude, this method was applied using a Thermo Scientific Element XR single-collector SF ICP mass spectrometer and a UP-213 (New Wave Research) laser ablation system. Measurements for standard zircons showed the error of dating less than 2%. The results of U–Pb LA–SF-ICP-MS dating of zircon from Late Paleozoic granitoids of western Transbaikalia confirm the overlapping of the time intervals of formation of the Barguzin (330–290 Ma), Chivyrkui (305–285 Ma), and Zaza (305–285 Ma) intrusive complexes.

We present results of a comparative study of Late Paleozoic granitoids of Eastern Kazakhstan and Western Transbaikalia composing the large Kalba–Narym and Angara–Vitim batholiths. We have established that despite the different geologic history of these regions, granitoid magmatism there proceeded nearly synchronously at the Carboniferous/Permian boundary (330–280 Ma) and was accompanied by mantle magmatism. The regularities of its evolution are considered in terms of the plume model and different stages of interaction of mantle plumes with the lithosphere. The major principles of plume–lithosphere interaction in accretion-collision fold belts have been formulated: (1) Plume-lithosphere interaction results in large-scale melting of sublithospheric mantle, lower lithosphere, and crustal substrates warmed by the preceding orogenic processes; (2) The processes last 30 to 50 Myr and produce large volumes of igneous rocks, mostly granitoids; (3) The sequence of formation of granitoid and basic igneous complexes and the metallogenic specialization can be different and depend on the lithosphere structure and preceding geologic history of the region.

Isotopic dates newly obtained for the northwestern portion of the Angara–Vitim batholith are consistent with preexisting data on the duration of the Late Paleozoic magmatic cycle: 55–60 Ma (from 325 to 280 Ma). These data also indicate that alkaline mafic magmatism in western Transbaikalia began simultaneously with the transition from crustal granite-forming processes to the derivation of granites of a mixed mantle–crustal nature, with gradual enrichment of the juvenile component in the source of the magmas. Analysis of the currently discussed geodynamic models of Late Paleozoic magmatism shows that a key role in all models of extensive granite-forming processes in the region is assigned to mafic mantle magmas, which can be generated in various geotectonic environments: subduction, delamination, decompression, and a mantle plume. The plume model is most consistent with the intraplate character of the Angara–Vitim batholith. The derivation of the vast volume of granitic material (approximately 1 million km³) should have required a comparable volume of mafic magma that should have been pooled in the middle crust of the Baikal fold area. However, the density structure of the region does not provide evidence of significant volumes of mafic rocks. This suggests that the mechanism of plume–lithospheric interaction that should have induced extensive crustal melting and the origin of vast granite areas was more complicated than simply conductive melting of crustal protoliths in contact with mafic intrusions.

U‐PB LA‐ICP‐MS ДАТИРОВАНИЕ ЦИРКОНОВ ИЗ СУБВУЛКАНИТОВ БИМОДАЛЬНОЙ ДАЙКОВОЙ СЕРИИ ЗАПАДНОГО ЗАБАЙКАЛЬЯ: МЕТОДИКА, СВИДЕТЕЛЬСТВА ПОЗДНЕПАЛЕОЗОЙСКОГО РАСТЯЖЕНИЯ ЗЕМНОЙ КОРЫ