Research subject. The isotopic composition (Pb-Pb, Sm-Nd, Rb-Sr, Os/Os, Hf/Hf, 3 He/4 He, etc.) of magmatic complexes and ore-magmatic systems (OMS) of two ore clusters (Kupolsky and Ilirneysky) located in the subpolar Western Chukotka was studied. These ore clusters differ from each other both in their structural position and the age of their magmatic complexes, within which the largest deposits of Au-Ag type are known. Materials and methods. The Pb-Pb, Rb-Sr, SmNd, Re-Os, Lu-Hf, 3 He/4 He, 40Ar/36Ar and sulphur isotopic systems were studied at the VSEGEI centre for isotopic studies (St. Petersburg), as well as at the Institute of Geology, Geochemistry and Ore Deposits (IGEM, Moscow) and the Laboratory of Stable Isotopes of the Far Eastern Geological Institute (FEGI, Vladivostok). Re and Os were measured using an ELEMENT-2 inductively coupled plasma single-collector mass spectrometer. Sulphur isotopic ratios were measured using a Finnigan MAT 253 isotope mass spectrometer. Results and conclusions. On the basis of the isotope-geochemical data obtained, an assumption was made that various deep sources participated in the magma generation, and the differentiated composition of late melts may reflect the melting processes of the crust upper horizons. When comparing the data on the magmatism of the Ilirneysky and Kupolsky ore clusters, a different degree of crustal rock influence on melt generation was revealed. The Kupolsky ore cluster is characterised by a large influence of mantle sources in intraplate magmatism associated with ore formation processes. This is likely to have determined a greater amount of mineralisation in the Kupolsky cluster compared to the Ilirneysky ore cluster.

Research subject. This study was devoted to magmatic complexes in Northwestern Chukotka associated with the largest gold and silver deposits across Kupol’skii (Kupol field) and Ilirnei (Dvoinoe and September fields) ore junctions. Materials and methods. The petrogenic elements of ore-containing igneous rocks were determined using a spectrometer ICAP 6500Duo (USA). An elemental analysis of igneous and ore samples was performed by inductively coupled plasma spectrometry (ICP-MS). The age was determined by zircons (SHRIMP-II, VSEGEI isotope research center, St. Petersburg) using a laser ablation system NWR-213 (USA). Results. New information concerning the dating of magmatic complexes and gold-bearing magmatic systems in the ore junctions under study was obtained. It was established that the manifestations of magmatism in the Kupol and Ilirnei ore junctions differ in terms of the main phase formation age. The age of the Ilirnei ore junction, which is represented by large-volume intrusions of granitoids, leucogranites and volcanites of medium-basic composition, was determined to be 124–114 Ma. The age of mineralization, which is associated with later magmatism phases – small intrusions and a dike complex of predominantly granodiorite composition –, was estimated to be (93– 92) ± 2.0 Ma. In the Kupol ore junction, the magmatism associated with mineralization was dated 91.0 ± 1.4 Ma, while the age of rhyolite dikes containing mineralization was estimated to be 88.9–89.0 Ma.Conclusion. The results of the RMS analysis of the Kupol and Ilirney ore junctions suggest that ore formation in this region was connected with a single stage of activation of deep processes and mantle-crust interaction with participation of deep (mantle) fluids.

We investigated the deep structure of the lithosphere and the geodynamic conditions of granitoid magmatism in the Eastern Russia within the borders of the Far Eastern Federal District. The relevance of the work is determined by the need to establish the geotectonic and geodynamic conditions of the granitoids petrogenesis and ore genesis in the Russian sector of the Pacific Ore Belt. The purpose of the article is to study the deep structure of the lithosphere and determine the geodynamic conditions of granitoid magmatism in the East of Russia. The author's data on the magmatism of ore regions, regional granitoids correlations, archive and published State Geological Map data, survey mapping, deep seismic sounding of the earth's crust, gravimetric survey, geothermal exploration, and other geophysical data obtained along geotraverses. The magma-controlling concentric geostructures of the region are distinguished and their deep structure is studied. The connection of plume magmatism with deep structures is traced. The chain of concentric geostructures of Eastern Russia controls the trans-regional zone of leucocratization of the earth's crust with a width of more than 1000 km, which includes the Far Eastern zone of Li-F granites. Magma-controlling concentric geostructures are concentrated in three granitoid provinces: Novosibirsk-Chukotka, Yano-Kolyma, and Sikhote-Alin. The driving force of geodynamic processes and granitoid magmatism was mantle heat fluxes in the reduced zones of the lithospheric slab. The distribution of slab windows along the Pacific mobile belt's strike determines the location of concentric geostructures and the magnitude of granitoid magmatism in the regional provinces. Mantle diapirs are the cores of granitoid ore-magmatic systems. The location of the most important ore regions of the Eastern Russia in concentric geostructures surrounded by annuli of negative gravity anomalies is the most important regional metallogenic pattern reflecting the correlation between ore content and deep structure of the earth's crust.

The first finds of B–Tm volcanic ash of the catastrophic eruption of Baitoushan Volcano in the 10th century (946/947 AD) in the terrestrial deposits of Primorye are reported. The ash layer is found in 17 cross sections of lacustrine–boggy sediments at nine observation sites, both on the coast and in the internal areas of Sikhote-Alin. Identification of the volcanic source is carried out based on the study of macroelement composition of volcanic glass. Radiocarbon dating is used for age determination. The tephra distribution and the changes in the grain size depending on the distance from the source are analyzed. A comparative analysis of the volcanic glass composition and the data on pyroclastics of the proximal zone and the results of distal tephra study has been performed. It proved that the ash layer in Primorye was formed in the final phase of the eruption, but an exception was the coast of Kit Bay and the Shkotovskoe Plateau, where glass of rhyolitic composition corresponding to the maximum phase at the beginning of the eruption is found. For the reconstruction of the environmental development, the ash is used as an age marker of the Medieval Warm Period in the Holocene, which makes it possible to compare reliably the data on the cross sections located on the coast and in the mountains, to refine the chronology of paleogeographical events of historical time, and to perform interregional correlations.

Обсуждаются вопросы масштабной контаминации базальтов Шуфанского вулканического плато (Приморье) селективными выплавками из ксенолитов. Селективно экстрагированные из ксенолитов кремне-щелочные жидкости лишь ограниченно смешиваются с базальтовым расплавом и образуют полосы гранофира, придающие лавам такситовую текстуру. Охарактеризованы уникальные составы бухитов - химически модифицированных при диффузионном взаимодействии с базальтовой магмой и селективно-расплавленных пелитовых ксенолитов. Их минеральные ассоциации представлены высокожелезитым кордиеритом (секанинаитом), ультражелезистым герцинитом, (Al, Zr) Fe-армолколитом, Zr-ильменитом, муллитом, силлиманитом, высоколантановым монацитом, бариево-фосфатной алюмосиликатной фазой. Особенности химического и минерального состава бухитов отражают накопление в реститовом веществе ксенолитов рефракторных элементов: Al, Fe, Ti, Zr, Ni, Cr с созданием ультраглинозёмистой, ультражелезистой, изначально несмесимой металло-силикатной композиции. Низкие свинцовые изотопные отношения в Шуфанских базальтах свидетельствуют о селективной контаминации веществом древнего кратонного основания. Наблюдается последовательный рост этих значений для базальтов, контаминированных верхнекоровым веществом, что отражает и изотопный состав бухитов.

The origin and expansion of millennial-scale climate changes in the Earth's climate system, widely presented in different paleo records, remain important issues in the scientific community. In this study, we present a highly resolved record of the East Asian monsoon (EAM) over 123 to 30 ka, obtained from a new archive of millennial/centennial climate variability in the mid-latitudes of the Northern Hemisphere. We used sediments from the semi-enclosed Sea of Japan, which is a region with unique land, ocean, and atmospherice interactions. We obtained color lightness (CL) records of a sediment core recovered from the northwestern part of the Sea of Japan with a high temporal resolution comparable to that of the Chinese EAM records using the original photocolorimeter. The chronology of the studied core was established by correlating the Heinrich events with the measured CL, magnetic susceptibility, and chlorin content with color L* and magnetic susceptibility records of the well-dated Sea of Japan core MD01–2407 and subsequently by correlating the abrupt drops in CL with well-dated Greenland and Chinese interstadials within the established Heinrich events. To infer a new record of EAM evolution, we used the CL record of the studied core over 30–123 ka, when the sea level dropped below the present sea level <90 m, the deep-water ventilation did not change profoundly relative to the present and sediment geochemistry was mainly controlled by millennial-timescale climate changes, such as the Dansgaard–Oeschger (DO) cycles. By comparing the DO cycles inferred from different natural archives, such as δ18O records of Greenland ice core and Chinese caves and CL record of the Sea of Japan sediments, we discussed similarities and some peculiarities of the DO cycles evolution and its millennial scale variabilities recorded in the high, middle, and low latitudes of the Northern Hemisphere over 30–123 ka.

The problems of large-scale contamination of the Shufan volcanic plateau (Primorye) basalts with selective melts from xenoliths are discussed. Silico-alkaline liquids that are selectively extracted from xenoliths mix only to a limited extent with the basalt melt, and form granophyre bands that give lavas a taxitic texture. The unique compositions of buchites (pelitic xenoliths chemically modified with a diffusion interaction with basaltic magma and selectively molten politic xenoliths) are characterized. The mineral associations of buchites are represented by highly ferriferous cordierite (sekaninaite), ultra-ferriferous hercynite, (Al, Zr) Fe-armalcolite, Zr-ilmenite, mullite, sillimanite, high-lanthanum monazite, and a barium–phosphate–aluminosilicate phase. The features of the chemical and mineral composition of buchites reflect the accumulation of refractory elements (Al, Fe, Ti, Zr, Ni, and Cr) in the restitic material of xenoliths, followed by the formation of ultra-aluminous, ultra-ferriferous, and initially immiscible metal-silicate composition. Low Pb isotopic ratios in the Shufan basalts indicate selective contamination with material of the ancient cratonic basement. A steady increase in these values is observed for basalts contaminated with the upper crustal material, which also reflects the isotopic composition of buchites.

New data are presented on the geology and composition of volcanic and intrusive rocks of the Orochenka caldera, which is located in the western part of the East Sikhote Alin volcanic belt. The SHRIMP and ICP MS age of zircons of volcanic and intrusive rocks, respectively, and the composition of the volcanic rocks allow comparison of these complexes with volcanic rocks of the eastern part of the volcanic structure. New data indicate the period of transition between subduction to transform regimes.

It is shown that presence of the Early Precambrian sial crust in the Indo–Atlantic segment of the Earth and its absence in the Pacific has been caused by geochemical differences in the mantle underlying these segments. These differences were examined on the basis of Nd–Hf and U–Pb isotopes in modern basalts. The U–Pb isotope system is of particular interest, since uranium is a member of a group of heat-generating radioactive elements providing heat for plumes. It is shown that in the Indo–Atlantic segment, a distribution of areas of the modern HIMU type mantle is typical, while it is almost completely absent in the Pacific segment. In the Archean, in the upper HIMU type paleo-mantle areas, plume generation and formation of the primordial basic crust occurred; this was followed by its remelting resulting in the appearance of an early sial crust forming cratons of the Indo–Atlantic segment.

The problem of the development of the ancient continental crust in the Primorye Region is discussed. It is substantiated by geological and isotope-geochemical criteria: a granite–metamorphic mineral composition of different-aged terrigenous deposits and pelagic cherts, occurrence of arkoses, as well as Proterozoic model age datings of sedimentary complexes and the occurrence of early Proterozoic zircons and monazites. The manifestation of potassium, high-Ba, LREE- and Nb-rich basite–ultrabasite magmatism, typical of Sino-Korean and Okhotsk Ba-bearing nuclears, of lengthy age intervals (Jurassic–Paleogene) in Primorye and the Amur Region is an important criterion.

The first results of SHRIMP dating of magmatic complexes and associated gold–silver deposits and ore occurrences (Kupol, Dvoinoe, Moroshka, and others) in the Chukotka sector of the Russian Arctic coast are discussed. The petrological and isotopic–geochronological data are used for reconstructing their formation conditions.

This work presents the first isotope-geochronological data obtained for granitoid series of the Arminskii block of Central Sikhote Alin: Tatibi gabbromonzodiorite and Olgino leucocratic granite. Every series is characterized by a certain structural position and timing of the formation of ore mineralization. The Tatibi series is characterized by the presence of gold-ore occurrences including the potential Glukhoe goldore occurrence. Granitoids of the Olgino series comprise known tin–sulfide ore occurrences. The conditions for the generation of each series of rocks were revealed on the basis of geochronological-isotope data.

This paper reports the results of isotope-geochemical studies and distribution patterns for trace elements and rare earth elements in a collection of specimens of Cenozoic alkaline olivine basalts and spinel lherzolite xenoliths sampled at Zhokhov Island, De Long Archipelago (New Siberian Islands), East Arctic. In spite of various contributions of xenogenic minerals of mantle lherzolite xenoliths (olivine, pyroxene and spinel), the bulk-rock isotope composition of the studied specimens deviates within insignificant limits. This evidences the isotopic and geochemical homogeneity of the mantle source and the absence of a significant effect of processes of contamination by crustal host rocks, which frequently occur within the basalts as xenoliths. On the other hand this reflects the short lifetime of existence and evolution of the mantle melt source. The studied basalts by their isotope and geochemical characteristics resemble volcanics of oceanic islands, intraplate continental volcanics, and those of ocean rises, relate to the activity of mantle plumes. The lack of elevated U/Pb in the studied specimens permits us to correlate the occurrence of the Cenozoic volcanism at De Long Islands of East Arctic with intraplate continental plume volcanism of the rifting stage (analogous to plume magmatism of the East African Rift, Mesozoic alkaline ultramafic volcanism of Eastern India, and others).