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AbstractNew geochronological (U–Pb ID-TIMS) data on zircons from pegmatites of the Mama mica belt in the Baikal Highlands are presented. The ages obtained for the plagioclase pegmatites (388 ± 2 and 389 ± 2 Ma, Mochikit deposit) and two-feldspar pegmatites (333 ± 1 and 332 ± 3 Ma, Slyudyanka deposit) demonstrate a significant age gap (50–60 Ma) between them. Based on the entire set of geological and new geochronological data available, it is proposed to divide the Mama complex, to which they were previously assigned, into two separate granitoid complexes.

The stratigraphic distribution of microfossils and macroscopic fossil biota in Vendian deposits of the South Ladoga region (northwestern East European Platform) is analyzed. In the sequence of the Shotkusa- 1 well, three taxonomically heterogeneous microfossil assemblages are distinguished: two of them refer to the Redkinian age (Starorusskaya Fm.) and one to the Kotlinian age (Vasileostrovskaya Fm.). Deposits of the Starorusskaya Fm. contain Redkinian biota of macroscopic fossils, of which the most characteristic representatives are Chuaria circularis, Doushantuophyton lineare, Morania zinkovi, Orbisiana simplex, and Redkinia spinosa. These new findings expand the paleontological characteristics of Upper Vendian deposits, also providing additional criteria for distinguishing the Redkinian horizon in the northwestern East European Platform.

The crystallization age of Zhaunkar granites (829 ± 10 Ma) was determined by U–Pb zircon dating. Taking into account the data obtained earlier on the granite age (791 ± 7 Ma) in the Aktas Complex and the syenite age (673 ± 2 Ma) in the Karsakpai Complex, the Ulutau sialic massif is assumed to be composed of three igneous complexes formed during the Tonian–Cryogenian periods of the Neoproterozoic.

U–Pb dating of the Torangalyk Complex (Northern Balkhash) yielded a Late Carboniferous age of 305 ± 2 Ma. Taking into account the previous data, a new scheme for Late Paleozoic granitic magmatism in this region has been proposed. It includes the Early Carboniferous granite–granodiorite Balkhash Complex, Late Carboniferous monzonite–granosyenite Kokdombak and Torangalyk complexes, and the Late Carboniferous–Early Permian granite–leucogranite Akchatau Complex.

U–Pb dating of tonalite of the Shaytantas Pluton located within the Ulutau sialic Massif (Central Kazakhstan) has been carried out. Their crystallization age of 521 ± 2 Ma corresponds to the Early Cambrian (boundary of Stages 2 and 3). The obtained geochronological data allow us to identify the Early Cambrian stage of the intraplate magmatic activity in the history of formation of the sialic massifs in the western part of the Central Asian fold belt.

Determination of the age of ore hosting complexes at famous large deposits is a necessary condition to improve prospecting. In Kazakhstan, sufficiently abundant porphyry copper deposits are related to magmatic complexes of various ages [2]. The Konyrat deposit is the largest porphyry copper deposit in Kaza khstan. Therefore, dating of rocks hosting the major part of ores at this deposit with advance geochronolog ical techniques is important for a forecast in adjacent areas.

The sialitic massifs with Precambrian crust formed by terrigeneouscarbonate and siliciousterrigeneous unmetamorphosed strata of the EdiacaranLower Paleozoic cover, which overlie the metamorphosed volcanogenicsedimentary and granitoid complexes of the Proterozoic basement to a variable degree, play an important role in the structure of paleozoids in the western part of Kazakhstan and Northern Tien Shan. The sialic massifs of Kazakhstan and Northern Tien Shan can be subdivided into two groups with respect to their structure, composition, and the age of volcano genicsedimentary and granitoid complexes of the basement.

The principal structure of the Central Asian fold belt is determined by the combination of many continental massifs and smaller fold belts of different ages. In its eastern segment, the most typical examples of the massifs are the Bureya (Turan) and Malyi Khingan (Jiamusi) massifs, which represent the main element of the Bureya-Jiamusi superterrane. The metamorphic complexes, which have been dated back to the Early Precambrian, are usually thought to form the basement of these terranes.

The formation of the Caledonian accretional-collisional area of the Central Asian Fold Belt (CAFB) is controlled by the processes of Early Caledonian tectonogenesis. In the range of 570-490 Ma, these processes resulted in the formation of the Caledonian superterrain comprising the fragments of continental massifs located within the Paleoasian Ocean, as well as Late Riphean and Vendian-Early Paleozoic oceanic and island arc structures.

The Kitoi sillimanite schist deposit is located on the left side of the Kitoi River within the Sayan (Sharyzhalgai) marginal uplift of the Siberian Platform basement. In this district, sillimanite was described for the first time in 1951. In 1958, a geological crew under the supervision of I. M. Shirobokov revealed a significant amount of sillimanite as a result of geological survey and after lengthy exploration, 1959-1968, it was recognized as the largest alumina deposit in Eastern Siberia. The total reserves of the deposit are a few hundred million tons with sillimanite grade more than 20%.