For the first time in podiform chromitites, a mineral of the humite group, titanium–containing hydroxylclinohumite, belonging to natural dense water-containing magnesian silicates (DHMS phases), was found. The find was made in chrome ores of the Paity plateau, located in the northern part of the Voikaro-Synyinsky ultramafic massif of the Polar Urals. Chromitites are deposited in the dunite body, which is located at the contact of apoharzburgite amphibole-olivine-antigorite and amphibole-enstatite-olivine metamorphic rocks containing relics of non-serpentinized harzburgites. According to optical data and chemical composition, the mineral belongs to titanium-containing hydroxylclinohumite, since it contains TiO2 (up to 5.64 wt.%), in the complete absence of fluoride. The presence of OH-grouping in the mineral is confirmed by the Raman spectrum, which generally corresponds to the standard of hydroxylclinohumite. The results of geothermometry show that this mineral was formed in chromitites of the Polar Urals at a temperature of 668–740º with and, probably, a pressure of 20–25 kbar. It follows from this that the formation (or recrystallization) of chromite ores occurred under high-pressure conditions, i. e. ore occurrences of chromites in the northern part of the Voikaro-Synyinsky massif were formed, apparently, in a suprasubduction environment.

A humite group mineral, Ti-bearing hydroxylclinohumite, referred to natural compact water-containing magnesian silicates (DHMS phases) was found for the first time in podiform chromitites. The finding was made in chrome ores of the Paity Plateau located in the northern part of the Voikar–Synya ultramafic massif of the Polar Urals. Chromitites deposited in the dunite body located at the contact of apoharzburgite amphibole–olivine–antigorite and amphibole–enstatite–olivine metamorphic rocks containing nonserpentinized harzburgite relics. According to the optical data and chemical composition, this mineral belongs to Ti-bearing hydroxylclinohumite, because it contains TiO2 (up to 5.64 wt

Eclogites exposed along the northeastern boundary of the Belomorian orogen in the eastern Fennoscandian Shield formed as a result of Mesoarchean-Neoarchean subduction. Highly-deformed banded TTG gneisses with eclogitized mafic pods, lenses and dykes in the Gridino association of metamorphic rocks have been modified locally to have typical migmatite structures that formed as HP rocks decompressed through HP granulite-facies metamorphic conditions (16-12 kbar, 800-850 degrees C) to amphibolite-facies conditions (10-9 kbar, 600-700 degrees C). The migmatites are located with the boundaries between felsic and mafic lithologies, which are the most suitable place for partial melting, fluid migration, and component diffusion. Symplectic intergrowths of hydrous minerals (mica, epidote) together with quartz in the leucosome are important markers of arrested reaction textures that formed by reversed hydration crystallization of residual melts or by fluids where their infiltrated through migmatite areas. There are two potassic granitic leucosomes with contrasting geochemical signatures. Garnet and phengite-bearing leucosome replaces the host TTG gneiss and percolates mafic rocks. This leucosome is distinguished by a high Ba content, striking positive Eu and Sr anomalies and corresponding low concentrations of all other trace elements. The compositions of the leucosome record initial segregation and migration of melt away from the residual source and subsequent crystal fractionation, dominated by feldspars, of the escaped melt. Migration of anatectic melts led to the formation of small bodies of leucogranite that are characterized by high contents of trace elements and negative Eu and Sr anomalies. Leucogranites formed from portions of fractionated melt that percolated the migmatites and solidified. Anatexis occurred during the Neoarchean time (similar to 2.7 Ga). U-rich zircon domains were partly or completely affected by radiation damage that yield discordant scattered dates between 2.7 and 1.9 Ga, which are interpreted as reflecting a thermal and fluid overprint during evolution of Belomorian province that produced recrystallization and Pb loss in Neoarchean zircons.

The study of granites in the basement of the Western Siberian platform is highly relevant since they are associated with hydrocarbon deposits, which are located not only above the granite massif, but also within the metasomatically altered upper layer of granites. At the same time, granites are most easily and reliably dated by zircon, which makes the geological structure of the area easier to examine, especially when the latter is overlapped by a thick sedimentary cover. The composition of granitoids from the basement of the Traigorod–Kondakovskii licensed site of the Western Siberian megabasin, located in the northwestern part of Tomsk Region, near the border with the Khanty-Mansi Autonomous Okrug, about 40 km east of the village of Aleksandrovskoye, has been studied. This license area is located within the Aleksandrovskii arch, which is bounded by the Ust-Tymsk Depression in the southeast and the Koltogorskii Trough in the northwest. The Aleksandrovskii Arch has a complex structure, which includes the large Krivolutskii granite batholith enclosed in the Carboniferous–Devonian sedimentary (mainly carbonate) rocks and Ordovician–Silurian shales. It has been established that batholith rocks are leucogranites and granites of normal alkalinity and have undergone metasomatic alterations in the form of propylitization and argillization. Granites belong to the I-type and were probably formed from the island arc substrate. Their age, according to the results of U–Pb zircon dating, is approximately 268 Ma; i.e., the generation and intrusion of granites took place during the beginning of the formation of the Koltogorsk–Urengoi Rift, the central rift of Western Siberia (which, according to Ar–Ar basalt dating, was also formed 268 million years ago).

Bazhenov Formation is regarded as the main oil-bearing stratum mothering nearly all the fields of the Western Siberia Oil-Gas-bearing Megabasin. Presently, it is one of the most studied formations of Siberia and, probably, Eurasia as a whole. While there is an enormous amount of studies devoted to the Bazhenov Formation, there are no detailed mineralogical studies at the modern hardware level. The age and sources of the terrigenous materials of the formation have not been studied as well. We have explored the detrital monazite from the upperJurassic terrigenous sediments of the Multan Area at the foundation of the Bazhenov Formation in the central part of Western Siberia, Surgut District. All the detrital rare earth phosphate is of the cerium kind being a monazite- (Се). The mineral is rather dissimilar in respect of its chemical properties, especially, the content of thorium. Some fragments have been subjected to superposed secondary changes. The detrital monazite is rounded to various degrees which is indicative of the various distances from the rare earth phosphate orebody washout. As per the chemical data, most of the monazite has been washed out from the medium and basic rocks (probably subalkaline or alkaline) as well as the sialic rocks (granitoids and associated veins). According to the chemical dating, most of the monazite fragments have been washed out of the very ancient Proterozoic formations and lower-Proterozoic rocks. Terrigenous materials derives probably from the rock assemblages of the eastern and south-eastern fringes of the Western Siberian megabasin such as the Proterozoic Yenisei Ridge or LowerProterozoic blocks of the Altay and Sayan Faulting.

Fluorcalciobritholite and fluorbritholite-(Ce)-rare-earth minerals from the apatite supergroup-have been found in the course of the study in monzogabbro from the pre-Jurassic foundation of the Novoportovskoye oil and gas exploration area (southern part of the Yamal Peninsula). They form short-prismatic small individuals around fluorapatite crystals and belong to the primary mineral (magmatic) assemblage. This first finding of these minerals in gabbroids significantly expands our understanding of their occurrence in the nature.

Dolerites of the parallel dikes formed in a back-arc spreading setting have been dated by Sm–Nd to the Silurian (426 ± 34 Ma) for Mount Azov in the Central Urals. The age coincides with that for zircons (428.5 ± 3.7 Ma) from the East Ural Megazone dolerites, which indicates the regional extent of the back-arc spreading processes. Study of the ontogeny and mineral inclusions in the Middle–Upper Devonian zircons from the dikes of Mount Azov showed that the formation of zircons occurred during regional metamorphism of the dolerite and hosting basalts. This metamorphism coincides with time of onset of the Late Devonian collision, when collision processes engulfed practically the entire region.

New data were obtained on the age of metamorphism of the rocks of the Itkul formation of the Sysert Metamorphic Complex (Middle Urals). Amphibole-chlorite rocks from the Glubochinskoye deposit of the garnet were studied, which was partially worked by several mines. The investigated rocks are composed of chlorite (clinochlore), amphibole (sodic-ferrozhedrite, sodic-zhedrit), garnet (Alm(78-65)), staurolite, plagioclase (An(4-18)), ilmenite, fluorapatite and monazite-(Ce). We performed a microprobe study of the chemical composition of monazite and determined the age of the mineral using the Th-U-Pb dating method. The age of the monazite is from 273 to 314 Ma, a weighted average of 297 +/- 12 Ma and isochrone of 293 +/- 26 Ma (MSWD = 0.23). The age of accessory monazite shows that the formation of amphibole-chlorite rocks occurred in the early Permian times. Probably, the transformation of metamorphic rocks in the northern part of the Sysert metamorphic complex occurred at the Permian and Carboniferous boundary under the influence of a powerful thermal event. At present, this is the subject of discussions. Some researchers believe that metamorphic rocks were formed as a result of a thermal event associated with suprasubduction tonalite-granodi-orite magmatism, while others posit that the Sysert complex was formed as a suprasubduction accretion prism.

The data on the Silurian Sm–Nd age (426 ± 34 Ma) behind the arc-spreading dolerites of the sheeted dikes of Mount Azov in the Middle Urals was obtained. This age coincides with the age of zircons (428,5 ± 3,7 Ma) from the dolerites of the East-Ural megazone, which indicates the regional nature of the back-arc spreading processes. A study of the crystal ontogeny and composition of inclusions of metamorphogenic minerals in Mid-Upper Devonian zircons from the dikes of the city of Azov showed that the formation of zircons took place in the course of regional metamorphism of dolerites and enclosing basalts. This metamorphism coincides with the time of the onset of the collision in the late Devonian, and conflict processes manifested themselves over practically the entire width of the region.

Grothite – rare F-Al-rich type of titanite – has been found in accessory zircon from the granitoids of the pre-Jurassic basement of the Verkhnerechensky oil-gas area (in the southern part of the Yamal Peninsula) as a result of the study. Titanite forms rare inclusions (so-called minerals-prisoners) in the central parts of zircon crystals; in our sample of 35 individuals only two grains of titanite have been discovered. The measurement of the chemical composition of the mineral has been carried out on an electron-probe microanalyzer CAMECA SX 100, equipped with five wave spectrometers (IGG UrB RAS, Ekaterinburg). According to the microprobe analysis, the mineral has an unusual chemical composition, it shows the presence of significant concentrations of alumina (Al2O3 to 8.5 wt.%), rare earths elements (REE to 4.3 wt.%), and fluorine (F to 2 wt.%). This grothite is dramatically different in chemical composition from the accessory titanite of the matrix granitoid (monzoleicogranite), which is characterized by values close to the reference sphene. Overall, grothite is an intermediate connection between the two extreme members CaTiSiO4O (titanite) – CaAlSiO4F (synthesized Al-F-titanite), and the Verkhnerechensky mineral content of a hypothetical Al-F-titanite achieves a high level of 24–26 %. Unfortunately, grothite is crystallized in a wide range of temperatures and pressures which does not allow its use in thermodynamic reconstructions. The existence of grothite (or Al-F-titanite) is apparently determined not so much on the PT-conditions of rocks' formation, but most likely on the chemistry of the environment. So it is obvious that the Verkhnerechensky titanite was formed in the melt with an increased concentration of fluorine. It is the first record of grothite in the form of inclusions in accessory zircon.

Detrital monazite from Upper Jurassic sediments in the central part of the Frolov megadepression, West Siberian megabasin, is studied. Chemical composition of the mineral is studied and data on its age (chemical dating) are presented. Most monazite clasts are characterized by low roundness and their age corresponds to the Lower Paleozoic. Upper Jurassic sediments were likely derived not only from the local Early Paleozoic rock complexes (altaides), which make up the pre-Jurassic basement of the Frolov megadepression, but also from rocks located east and south of this megadepression.

New data on the material composition of the Severny Kolchim meteorite, found in the Perm region territory in 1965, is presented. It is established that the cosmic substance is composed of forsterite, enstatite, diopside, plagioclase (oligoclase, bitovnite), glass, chromite, magnetite, ilmenite, rutile, iron and nickel metals (kamasite, taenite and tetrataenite), sulphides (troilite, pentlandite), chlorapatite and merrillite. Some minerals, namely the diopside, tetrataenite, chlorapatite and merrillite, were determined in the Severny Kolchim meteorite first time. The data on the chemical composition of minerals and the trace element composition are given. It was verified that this meteorite is a nonequilibrium stone chondrite and belongs to the petrological type H3.

The relevance of the work is conditioned by the need for a more complete study of the mineralogy of rare-metal granite pegmatites of the Lipovskoye vein field. The purpose of the study is to describe the findings of native metals (gold, silver, copper, lead, bismuth and tungsten) in granite pegmatites of the Lipovskoye vein field. Research methodology. Detailed study of chemical composition, morphology and relationships of native metals with associated minerals. For this study we have chosen samples from the three types of granitic pegmatites – classical quartz-feldspar (mostly intragranitic), desilicated (apogranite plagioclasite) and contaminated lithium-bearing. Results. The paper describes native metals (gold, silver, copper, lead, bismuth and tungsten), which we have found in rare-metal pegmatites of the Lipovskoye vein field. The discovery of the native metals is the first on this facility. The microprobe analysis of such native metals as gold and silver showed the variability of their chemical composition from the type of pegmatite in which they are present. The formation of native lead should be logically linked to the destruction and recrystallization of high uranium thin rims of zircons. The formation of bismuth and tungsten may have occurred during recrystallization of accessory tantalumniobates. Summary. The finding of the native metals in granitic pegmatites is quite explainable. This is because these core rocks are formed in the post-magmatic stage of the silicate crystallization intrusions and they can contain typomorphic rocks for these metals. The absence of mineral concentrators (sulfides) in pegmatites clearly explains the small size and high dispersion of metals.

New data on the mineral composition of the Severny Kolchim meteorite, found in Perm Region in 1965, are presented. It has been found that that the meteorite matter is composed of olivine (chrysolite), orthopyroxene (bronzite), clinopyroxene (diopside), plagioclase (oligoclase, bytownite), glass, chromite, magnetite, ilmenite, rutile, metals Fe and Ni (kamasite, taenite, tetrataenite), copper, sulfides (troilite, pentlandite, covellite), chlorapatite, and merrillite. Diopside, tetrataenite, chlorapatite, and merrillite were identified in the Severny Kolchim meteorite for the first time. The chemical compositions are given for all these minerals. The meteorite itself is a nonequilibrium ordinary chondrite stone belonging to petrological type H3.

This work presents the results of studying srilankite, a rare zirconium titanate (ZrTi2O6), associated with ilmenite, rutile, zircon, uraninite, and other minerals discovered in high-pressure garnetites of the lherzolite Mindyak massif (Southern Urals). Srilankite occurs as inclusions in ilmenite and rutile of up to several tens of microns in size. It was established for the first time that srilankite contains a significant UO2 admixture (up to 20%). The negative correlation between Zr and U is evidence of isomorphism in the srilankite–brannerite system. The association of srilankite with high-Zr rutile indicates that formation of these minerals occurred at T > 850°С.

The zircons in granitoids from the basement of the Verkhnerechenskii oil exploration area (Yamal Peninsula, West Siberia) were studied. The U–Pb age of zircons was evaluated as 254.0 ± 3.0 Ma. It was found that the inclusions in zircons are represented by various minerals: fluorapatite, titanite, monazite-(Ce), albite, quartz, chamosite, and calcite. Most likely, the latter two minerals were formed separately from zircon but belonged to later secondary minerals (the rock propylitization products). In general, the accessory zircons and inclusions belonged to the “granite” association and crystallized synchronously in the Upper Permian.