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Late Paleozoic – early Mesozoic geological evolution of the Kolyvan-Tomsk Fold Zone (KTFZ) located in the northwestern part of the Central Asian Orogenic Belt is significant to understanding the tectonic transition from post-collision to intraplate settings. We present new whole-rock geochemical and Sr-Nd isotopic data, and in situ zircon U-Pb ages for granitic rocks from the KTFZ basement to constrain their petrogenesis and to characterize changing of the tectonic setting and geodynamic evolution. Zircon U-Pb ages reveal extended multi-stage emplacement of the KTFZ granitoids for about 20 Ma from ~260 to ~240 Ma, that can be divided into two stages: the Permian-Triassic (~260 to 250 Ma) and the Triassic (~250 to 240 Ma). The Permian –Triassic granitic rocks with SiO2 between 63% and 74% have high LREE, HFSE (except Nb and Ta), Sr, Mg#, Cr, Ni concentrations, Sr/Y and (La/Yb)N ratios and remarkably low Y and Yb contents and 87Sr/86Sr(T) values (0.704682 and 0.703368). They are magnesian and show metaluminous to weakly peraluminous natures, indicating their formation through high degree fractionation of mantle-derived magmas. The Triassic granitoids exhibit extremely high SiO2 (73–77%), HFSE, HREE, Rb contents, Rb/Sr ratios and elevated negative Eu and Sr anomalies, low Mg#. They are ferroan and have a peraluminous nature with the absence of aluminium-rich minerals, all of which indicate the presence of the crustal substance in the magma source. Isotopic Nd compositions show that the both the Permian –Triassic and Triassic granitoids have uniform magma's, which were derived from partial melting of juvenile Neoproterozoic sources. These two stages of granitoid magmatism are interpreted as reflecting the transition from post-collisional magmatism, related to the final closure of the Paleo-Asian Ocean due to collision between the Baltica and Siberian paleocontinents during the Late Permian – Early Triassic and hence, to the intraplate magmatism. The formation of the KTFZ granitic rocks was induced by an upwelling asthenosphere in an extensional geodynamic setting. During the post-collisional process, the large-scale lithospheric delamination plays a key role in the genesis of the Permian-Triassic granitoids and provide the magma generation for them. In the Triassic, we propose additional source of heat from mantle plume beneath the KTFZ, which promote extending of the granitoid magmatism in intraplate setting.

This study provides 87 Sr/ 86 Sr, δ 13 C and δ 18 O data from the best-preserved limestone and dolomite of the Ediacaran carbonate-dominated Khorbusuonka Group of the Olenek Uplift, NE Siberian Craton, as well as detrital zircon geochronological data from both underlying and overlying sandstones. The Maastakh Formation is characterized by 87 Sr/ 86 Sr ratios of ca. 0.70822 and δ 13 C values between + 4.8 and + 6.0‰. 87 Sr/ 86 Sr ratios in limestones of the Khatyspyt Formation are fairly uniform, ranging from 0.70783 to 0.70806. The carbon isotopic composition slowly decreases from bottom (+ 3.7‰) to top (− 0.2‰) of section. The Sr isotopic composition of the Turkut Formation varies from 0.70824 to 0.70914, value of δ 13 C is about zero: − 0.7…+0.7 ‰. The youngest population of detrital zircons from Maastakh Formation indicates that these rocks were formed not later than 630 Ma. U–Pb detrital zircons data of Kessyusa Group has a single peak at about 543 Ma, which is almost identical to the earlier dating. Based on biostratigraphy and isotopic data, the Sr isotopic compositions from the Khatyspyt Formation ( 87 Sr/ 86 Sr = 0.70783–0.70806) represent the composition of seawater at 560–550 Ma. Such low values of 87 Sr/ 86 Sr ratio in Ediacaran water were probably caused by the quick opening of Iapetus Ocean.

The West Siberian Basin (WSB) is one of the largest intracratonic Meso-Cenozoic basins in the world. Its evolution has been studied over the recent decades, however, some fundamental questions regarding the tectonic evolution of the WSB remain unresolved or unconfirmed by analytical data. A complete understanding of the evolution of the WSB during the Mesozoic and Cenozoic eras requires insights into the cooling history of the basement rocks as determined by low-temperature thermochronometry. We presented an apatite fission track (AFT) thermochronology study on the exposed parts of the WSB basement in order to distinguish tectonic activation episodes in an absolute timeframe. AFT dating of thirteen basement samples mainly yielded Cretaceous cooling ages and mean track lengths varied between 12.8 and 14.5 μm. Thermal history modeling based on the AFT data demonstrates several Mesozoic and Cenozoic intracontinental tectonic reactivation episodes affected the WSB basement. We interpreted the episodes of tectonic activity accompanied by the WSB basement exhumation as a far-field effect from tectonic processes acting on the southern and eastern boundaries of Eurasia during the Mesozoic–Cenozoic eras.

In this study, we present zircon U/Pb, plagioclase and K-feldspar 40Ar/39Ar and apatite fission track (AFT) data along the South Tannuol Fault Zone (STFZ). Integrating geochronology and multi-method thermochronology places constraints on the formation and subsequent reactivation of the STFZ. Cambrian (~510 Ma) zircon U/Pb ages obtained for felsic volcanic rocks date the final stage of STFZ basement formation. Ordovician (~460&ndash, 450 Ma) zircon U/Pb ages were obtained for felsic rocks along the structure, dating their emplacement and marking post-formational local magmatic activity along the STFZ. 40Ar/39Ar stepwise heating plateau-ages (~410&ndash, 400 Ma, ~365 and ~340 Ma) reveal Early Devonian and Late Devonian&ndash, Mississippian intrusion and/or post-magmatic cooling episodes of mafic rocks in the basement. Permian (~290 Ma) zircon U/Pb age of mafic rocks documents for the first time Permian magmatism in the study area creating prerequisites for revising the spread of Permian large igneous provinces of Central Asia. The AFT dating and Thermal history modeling based on the AFT data reveals two intracontinental tectonic reactivation episodes of the STFZ: (1) a period of Cretaceous&ndash, Eocene (~100&ndash, 40 Ma) reactivation and (2) the late Neogene (from ~10 Ma onwards) impulse after a period of tectonic stability during the Eocene&ndash, Miocene (~40&ndash, 10 Ma).