geological data, petrogeochemical characteristics of magmatites of the Kurung complex (the Ket-Kap-Yuna igneous province of the Aldan Shield), and previously published isotopic data along with the results of geochronology and geochemistry research provide evidence for this complex evolving in the Late Cretaceous in a setting of riftogenesis (final phase) of continental margins. Similar to the Late Jurassic-Early Cretaceous polyformational volcano-plutonism of the Aldan Shield, the Late Cretaceous alkaline magmatism in the Ket-Kap-Yuna province is associated with the tectonomagmatic activation which manifested itself mainly as continental margin rifting associated with deep reorganization of the southwestern, southern and southeastern framing of the Siberian craton triggered by gravitational sliding of the lithospheric plates. Results of the petrogeochemical analysis of the studied magmatites revealed that the heterogeneous rock groups identified within this rock complex are not related to each other by fractional or other type of differentiation, thus suggesting their possible derivation as a result of fluid syntexis-type interaction between mantle-derived alkali-basite melt and felsic crustal melts. Alkali-basite parent melts are shown to have formed during partial melting of variably enriched mantle which is widely spread beneath the Aldan Shield and is varied in composition (from BSE enriched to nearly EM-I). Origination of such deep-seated melts (magma sources) was associated with the rifting processes (strike-slip tectonics) triggered by the setting of gravitational sliding of lithospheric plates. The formation of alkaline-salic magmas of the Kurung complex is associated with large-scale selective assimilation of crustal material by high-temperature fluidized mantle magmas during their ascent to the surface, possibly as a result of fluid syntexis of alkaline-basite mantle magmas and crustal smeltings formed under their influence.

Геологические сведения и петрогеохимические характеристики магматитов курунгского комплекса Кеткапско-Юнской магматической провинции Алданского щита в совокупности с опубликованными ранее данными изотопной геохронологии и геохимии свидетельствуют о формировании его в позднем мелу в обстановке (завершающей фазы) окраинно-континентального рифтогенеза. Как и предшествующий ему позднеюрско-раннемеловой полиформационный вулканоплутонизм Алданского щита, позднемеловой щелочной магматизм Кеткапско-Юнской провинции связан с процессами тектономагматической активизации, которые проявились главным образом в виде окраинно-континентального рифтинга, сопряженного с коренной структурной перестройкой юго-западного, южного и юго-восточного обрамления Сибирской платформы, обусловленной обстановкой скольжения литосферных плит. Как вытекает из результатов петрогеохимического изучения магматитов комплекса, разноосновные группы пород в его пределах не связаны между собой отношениями фракционной или иного типа дифференциации, а являются, вероятно, производными флюидно-синтексического взаимодействия мантийного щелочно-базитового расплава и кислых коровых выплавок. Образование щелочно-базитовых материнских расплавов происходило при парциальном плавлении обогащенной в разной степени мантии, широко распространенной под Алданским щитом и варьирующей по составу от обогащенной BSE до близкой к EM-I. Зарождение столь глубинных областей плавления было связано с присдвиговым рифтингом, обусловленным существованием обстановки скольжения литосферных плит. Образование щелочно-салических магм курунгского комплекса увязывается с масштабным избирательным усвоением корового материала высокотемпературными флюидизированными мантийными магмами в процессе их подъема к поверхности, возможно, в результате флюидного синтексиса щелочно-базитовых мантийных магм и образовавшихся под их влиянием коровых выплавок. Integrated geological data, petrogeochemical characteristics of magmatites of the Kurung complex (the Ket-Kap–Yuna igneous province of the Aldan Shield), and previously published isotopic data along with the results of geochronology and geochemistry research provide evidence for this complex evolving in the Late Cretaceous in a setting of riftogenesis (final phase) of continental margins. Similar to the Late Jurassic–Early Cretaceous polyformational volcano-plutonism of the Aldan Shield, the Late Cretaceous alkaline magmatism in the Ket-Kap–Yuna province is associated with the tectonomagmatic activation which manifested itself mainly as continental margin rifting associated with deep reorganization of the southwestern, southern and southeastern framing of the Siberian craton triggered by gravitational sliding of the lithospheric plates. Results of the petrogeochemical analysis of the studied magmatites revealed that the heterogeneous rock groups identified within this rock complex are not related to each other by fractional or other type of differentiation, thus suggesting their possible derivation as a result of fluid syntexis-type interaction between mantle-derived alkali–basite melt and felsic crustal melts. Alkali–basite parent melts are shown to have formed during partial melting of variably enriched mantle which is widely spread beneath the Aldan Shield and is varied in composition (from BSE enriched to nearly EM-I). Origination of such deep-seated melts (magma sources) was associated with the rifting processes (strike-slip tectonics) triggered by the setting of gravitational sliding of lithospheric plates. The formation of alkaline–salic magmas of the Kurung complex is associated with large-scale selective assimilation of crustal material by high-temperature fluidized mantle magmas during their ascent to the surface, possibly as a result of fluid syntexis of alkaline–basite mantle magmas and crustal smeltings formed under their influence.

To test the “rare earth” hypothesis of geophagy, geological and hydrogeochemical studies unparalleled anywhere in the world were carried out at kudurs (salt licks) in two districts in the Primorsky Krai, Russia. The mineral and chemical compositions of geophagic earth consumed by animals, the chemical composition of surface waters and vegetation, and the chemical composition of biological tissues of red deer (Cervus elaphus) were studied in this research. It was found that ultra-fresh surface and fontinal waters in the studied areas contain anomalously high concentrations of rare earth elements (REE), the sums of which exceeded the average values in the Primorsky Krai and worldwide by tenfold, and more. The presence of landscape REE anomalies is confirmed by elevated concentrations of these elements in vegetation. Using electron microscopy, it was determined that the sources of REE in landscape components are rocks containing secondary, readily soluble, REE minerals (hydrophosphates and fluorocarbonates). The study of the chemical composition of animal tissues showed the presence of significant concentrations of heavy REE (HREE) in the blood and brain, which indirectly indicates a high probability of animals developing stress reactions against the background REE-elementosis. Eaten earthy substances in both areas are represented by mixtures of smectite clays and zeolites with high ion-exchange properties. In the digestive tract of animals, such sorbents actively interact with the biological electrolyte, saturating it with sodium ions and absorbing HREE. The main meaning of geophagy is regulation of the concentration and proportion of REE in the body. Sometimes it manifests itself in intake of significant amounts of Na.

One of the theories explaining the reasons for geophagy, which was proposed earlier by the authors of the article, consists in the assumption that animals need rare-earth elements (REE). In order to test this hypothesis, we studied the chemical composition of spring waters in the territory of the Caucasus Nature Reserve at three kudurs along the Achipsta River, as well as at the Mamaevsky kudur (southwestern slope of the Pshekish mountain). At the Mamaevsky kudur, we also studied the chemical composition of earth consumed by animals, and the species, age and gender composition, seasonal and daily activity of ungulate animals–visitors of the kudur. It was determined that the most active visitors of the Mamaevsky kudur were European bison (Bison bonasus) with one activity peak during the rut, in July. The frequency of visits to the kudur by red deer (Cervus elaphus) was 4 times lower with the highest peak activity in April and a lower peak in August. Only in one of four water sources at the Mamaevsky kudur there was an elevated concentration of Na (by 7 times). In the other three the concentration was comparable to the local river water. The waters of two “sodium-free” springs had increased concentrations of REE (by 5–8 times). Geophagic earths near the Mamaevsky springs are decomposition products of siltstone and sandstone shale rocks of the Jurassic age consisting of clay minerals (illite mixed with smectite, and chlorites)—from 42 to 45%, and quartz and feldspar (in total up to 50%) mixed with Fe and Ca carbonates. The chemical composition of acid extracts (0.1 N HCl, pH = 1.0) from consumed earth showed the highest extractability of Ca and Fe. In trace elements, Sr, Ba, Zn, Cu, Ni, Co, V, light lanthanides, and Y are most actively extracted. Na is extracted at 0.03–0.1 g/kg. The sodium bicarbonate spring water consumed by animals at kudurs on the Achipsta River had Na contents 70–300 times, and REE contents 25–40 times higher than that in the river water. The revealed facts do not contradict the hypothesis that the desire for geophagy in animals in the Caucasus (in addition to the long-known “urge” for Na) can be also related to the properties of lanthanides group elements exchange in the body.

This study described is about problem of determining trace and low concentrations of rhenium with using of ICP-MS spectrometry in rock samples with high contain of carbonaceous and organic components. Paper describes different ways of analysis and sample decomposition that are used in a common practice. Special attention is paid for sample preparation for ICP-MS investigations as far as it requires decomposition and disposing organic and silicate components.

In order to reveal the genesis of barites, the authors identified content and distribution regularities of rareearth elements in barites from the Deryugin Depression, the Sea of Okhotsk. The obtained data show that a hydrothermal component does not affect the formation of the barites. Sea water is the source of the rareearth elements, and their composition apparently corresponds to the composition of cold seeps.

The first comprehensive isotope-geochemical study of volcanogenic rocks of different ages from Matua Island made it possible to distinguish the general stages in the magmatic evolution of the subduction system. The petrological similarity of the rocks from the central and northern chains of the Kuril island arc testifies that they were formed above "hot" geochemically enriched but isotopically depleted lithospheric mantle. The compositional change of the volcanic rocks of Matua Island in the Pleistocene-Holocene suggests a geodynamic transition at that time. Taking into account the similar tendency previously established in the southern Kuril Range (Kunashir Island) and for the Mutnovsky and Gorelyi volcanoes of southern Kamchatka, a global Pleistocene-Holocene tectonic event may be proposed in the evolution of the Kuril-Kamchatka island arc. The finding of the "adakite-like" tephra on Matua Island indicates the presence of felsic adakite-like melts among the eruption products of Sarychev Peak Volcano.