— The results of geochronological study (U–Pb SHRIMP-II) of zircons from granodiorites and plagiogranites of the main phase of the Tallai pluton of the Baikal–Vitim belt are presented. The obtained estimates of the age of the magmatic cores of zircons from granodiorite and plagiogranite coincide with each other within the limits of errors and are interpreted as the age of crystallization of rocks of the main phase of the Tallai pluton, 661 ± 6 Ma. The weighted average value of the age of the metamorphic rims of zircon from these rocks is 637 ± 5 Ma. The high positive values of ε Nd (660), +7.2 and +7.3, in the rocks of the main phase indicate a juvenile source of the parental melts. Based on new and earlier published geochronological data, a conclusion about the formation of Late Baikalian juvenile gabbro–granite associations of the same type within the Baikal–Vitim belt 660 million years ago (Tallai complex) and in the interval of 603–615 Ma (Padora complex) was made.

The results of a geochronological study (U–Pb SHRIMP-II) of zircon from granodiorites and plagiogranites of the main phase of the Tallain pluton of the Baikal-Vitim belt are presented. The obtained estimates of the age of the magmatic cores of zircon from granodiorite and plagiogranite coincide with each other within errors and are interpreted as the age of crystallization of rocks of the main phase of the Tallain pluton 661 ± ± 6 million years. The weighted average age of the metamorphic zircon shells of these rocks is 637 ± 5 million years. High positive values of ɛNd (660) +7.2 and +7.3 in the rocks of the main phase indicate a juvenile source of the parent melts. Based on new and previously published geochronological data, a conclusion is made about the formation of similar late Neoproterozoic juvenile gabbro-granite associations of the Baikal-Vitim belt at the turn of 660 million years (Tallain complex) and 603–615 million years (Padorinsky complex).

The paper presents data on the geological structure of the Kichera zone of the Baikal–Vitim belt (BVB) at the boundary between the marginal part of the Siberian craton and the Barguzin–Vitim superterrane of the Central Asian Orogenic Belt. Early Neoproterozoic (Early Baikalian) and Late Neoproterozoic (Late Baikalian) structures and complexes are identified and characterized in the Kichera zone of the BVB. Data are presented on the geochemistry of the rocks and on their U–Pb isotope age (zircon, SIMS and ID-TIMS) and on the Nd isotope characteristics of rocks from various parts of the Kichera zone, including representative rock association of the Nyurundukan migmatite–tonalite–metabasite complex with MORB-type tholeiites and tholeiites with intraplate geochemical features. It is shown that the sources of the Early Neoproterozoic complexes of the Kichera zone, which were metamorphosed at 0.76–0.74 Ga as a result of accretion events in the marginal part of the craton, were dominated by Early Precambrian recycled crustal material. The Late Neoproterozoic complexes typomorphic of the Kichera zone were formed in the Cryogenian–Ediacaran (720–545 Ma) from prevailing juvenile sources. Our data suggest that the metabasites of the Nyurundukan complex were formed in an environment of segmented troughs of the pull-apart paleorift system of the Kichera zone and can be compared with a reduced complex of continental-margin ophiolites transformed at 630 ± 7 to 615 ± 3 Ma. The destruction of the ancient continental crust of the craton ended with the formation and exhumation of deep rocks in the Late Ediacaran, the emplacement of adakite granites of the postcollisional geochemical type, and the formation of grabens filled with a terrigenous complex. The juvenile and riftogenic crust produced during the Late Neoproterozoic tectonic evolution of the Kichera rift zone does not show any features of mature continental-type crust.

The results of U–Pb geochronological (SIMS) study of zircons from granitoids of the Konstantinovskii Stock located 6 km from the Sukhoi Log gold deposit are reported. The 206Pb/238U weighted average age for long-prismatic crystals, rims, and cores of the early stage of crystallization of zoned zircons is 303 ± 3 Ma (MSWD = 0.87). The data obtained on the age of xenogenic cores of zoned zircons of the Konstantinovskii Stock granitoids indicate consolidated basement of the Bodaibo epicratonic sedimentary basin and its intraplate tectono-thermal transformation in the Archean, Paleoproterozoic and Paleozoic.

This article presents the results of U–Pb geochronological study of gneiss-granites of the Mamskaya zone. The age estimate of 1874 ± 9 Ma (SIMS method) obtained for the magmatic protolith of gneiss-granites for the first time proves the close formation time of gneiss-granites from the Mamskaya zone and rapakivi-like granites of the Kodar complex in the Chara–Olekma block. In the Late Devonian and Carboniferous, according to preliminary data, the Paleoproterozoic protolith of the gneiss-granites underwent deep metamorphic processing during shear deformations and formation of pegmatoid granites and pegmatites.

A forecast-exploration model of gold deposits of the Toupugol-Khanmeishor ore cluster was developed, which made it possible to recommend geological exploration within other promising areas of the Malyi Ural volcano-plutonic belt (VPB) in the Polar Urals. The studies have demonstrated that the Manyukuyu and Kokpela potential ore clusters of the Tan’yu-Lagorta complex ore district in the southern Malyi Ural VPB represent the most promising targets for the further prospecting for lode gold mineralization assigned to various structural-compositional subtypes of the gold-sulfide-quartz mineral type.

The forest conditions in the Central Aimag of Mongolia, located in the southern part of the Baikal catchment area, near the southern border of the forest-steppe subzone, were examined within the framework of this study. The field materials collected in the summer 201-2018 at the Zuunmod Model polygon serve as the core of the study. An ecosystem map of the Model polygon with the scale 1:50 000 and the Key plot with the scale 1:5 000 was drawn up using World Vi.w-2 satellite imagery data (2016). The proven method of botanical indication of forest growth conditions is as follows: identification of the ecologic and coenotic groups of plant species, calculation of the moisture coefficient based on the ratio of the number of species included in the groups characterizing the extreme conditions of the moisture gradient and distribution of communities in accordance with the values of the gradient in the ecological series. Communities of stages of ecological series serve as indirect indicators of the forest conditions: Stage I: Ku <1, insufficient humifying for tree growth, Stage II: Ku 1-2, average humifying, Stage III: Ku >2, sufficient humifying for tree growth. The stages also correspond to the landscape conditions and the character of the vegetation cover.

В статье проводится анализ проблемных вопросов развития системы путей сообщения Монголии для формирования современной политики российско-монгольского сотрудничества в сфере железнодорожного транспорта. Раскрываются планы формирования международных железнодорожных коридоров в рамках Программы развития экономического коридора «Китай – Монголия – Россия». Особое внимание уделяется анализу динамики, структуры и маршрутов грузовых потоков. Делается вывод, что слаборазвитая транспортная инфраструктура Монголии является серьезным ограничением для дальнейшего увеличения объемов экспорта полезных ископаемых. Рассматриваются инициативы России и КНР по развитию сети железных дорог в Монголии. По мнению авторов, они не были реализованы в связи с опасениями монгольского правительства усиления роли соседних стран в национальной экономике. При этом руководство Монголии, используя транзитную риторику, стремится привлечь внешних партнеров к развитию транспортной сети для улучшения условий выхода монгольскому экспорту на внешние рынки. Выдвигаются предложения в части формирования стратегии сотрудничества России с Монголией в области развития железнодорожной инфраструктуры. В качестве ключевого направления рассматривается дальнейшее участие России в развитии Центрального железнодорожного коридора.

New results of U–Pb zircon and Nd–isotope analyses of the Goryachinskiy Pluton adakite granites have been obtained. The pluton is exposed along the Baikal coast in the section where a section of sheared tectonic sheets of the Baikal–Muya Belt wedges out. The determined Early Cambrian (545 ± 6 Ma) age of the granitoids is unusual in the Northern Baikal region. These new geological and isotopic data are interpreted as an indication of the formation of the granitoids studied at the final stage of the Late Baikal strike–slip tectonics, which caused the pulse of the adakite magmatism within the Baikal–Muya belt.

This paper presents the results of U–Pb isotope–geochronological study on zircons from subalkali gabbros and granodiorites of the Dogaldyn intrusive massif located in the Karalon–Mamakan zone of the Baikal–Muya belt. The ages of 254 ± 2 and 256 ± 1 Ma yielded for rocks of the two main intrusion phases do not differ significantly from each other and correspond to the Late Permian period. The Nd-isotope and geochemical data indicate the relationship between the primary melts of intraplate rocks from the Dogaldyn Massif and various sources, including plume–mantle and ancient crustal ones. The manifestations of Late Permian intraplate magmatic activity in the Baikal–Muya belt could have been induced by the Iberian superplume framed by the Siberian trap province.

The Kichera zone of the Baikal–Muya Belt consists of alternating tectonic plates with rocks of different metamorphic facies. Garnet–cordierite–sillimanite gneiss from the tectonic fragment in granite–gneiss of the Baikal massif with an age of 755 ± 15 Ma from the Goremyka plate and two-pyroxene schist of the granulite complex with an age of 617 ± 5 Ma from the Boguchan plate were studied. Thermobarometric studies of these key metamorphic rocks were carried out using the avPT (THERMOCALC) and TWEEQU (TWQ 2.01) methods. The P–T parameters estimated for the cordierite⎯sillimanite gneiss of the Goremyka plate correspond to the boundary between the amphibolite and granulite facies. Granulites of the Boguchan plate belong to the HT–LP type. Exhumation of metamorphic rocks could be caused by extension upon the evolution of the Late Baikal rifting.

It was established that amphibolites of the Kichera zone of the Baikal-Muya belt (BMB) belong, at least, to two age groups: (I) Early Neoproterozoic large metamafic xenoliths entrapped by granitic rocks of 750 Ma and (II) Late Neoproterozoic (650-620 Ma) amphibolites, which compose individual tectonic sheets and lenses. The rocks of these groups are distinct in chemical composition: the low-Ti amphibolites of the first group with increased Al2O3 contents are similar to modern IABs, whereas the highly-Ti amphibolites of the second group correspond to MORBs and OIBs. The geochemical data showed that the igneous protoliths of amphibolites of the Kichera zone were formed during different stages of the BMB evolution distinct in geodynamic settings.