Evolution of grantoid magmatism and stages of crustal growth and accretion-collision events in the Southwestern Siberian Craton in the Archaean

The paper presents data on the age, composition, and isotopic parameters of Archean granitoids of the Sharyzhalgai uplift (southwestern Siberian Craton). From the Paleoarchean to the Meso- and Neoarchean, there was a change in the composition of the predominant granitoids with an increase in K 2 O content, a decrease in Eu/Eu*, and a decrease in ε Nd of the rocks and ε Hf of zircons. The Paleoarchean stage of TTG magmatism reflects the growth of sialic crust due to melting of the mafic source, which is confirmed by positive values for rocks (ε Nd from 0 to +3.1) and zircons (ε Hf from 0 to +6.3). The Mesoarchean saw four stages of granitoid magmatism at ~ 3.0, 2.95, 2.88, and 2.86 Ga. The isotopic features, negative values of εNd and εHf of Mesoarchean potassium granitods and felsic volcanics are evidence that crustal growth was followed by crustal reworking. The asynchrony of the stages of Paleo- and Mesoarchean magmatism in different blocks of the Sharyzhalgai uplift indicates a distinct evolution of their lithosphere. A new impulse of juvenile crust formation at ca. 2.7 Ga is recorded in Neoarchean felsic metavolcanics with ε Nd from +1.2 to –2.4 and ε Hf from +2.9 to –0.5. The simultaneous Neoarchean (2.55–2.53 Ga) granitoid magmatism and high-grade metamorphism record collision processes and the amalgamation of crustal blocks into a Neoarchean superterrane structure. The Neoarchean granitoids’ isotopic parameters (ε Nd from –4.4 to –1.7 and ε Hf from –6.2 to –3.7) as well as Mesoarchean inherited zircon cores reflect the recycling of the Archaean crust by intracrustal melting and its cratonization.