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Callovian and Late Jurassic zonal biostratigraphy and evolution of foraminifers in West Siberia have received better constraints from the foraminiferal taxonomy in newly studied sections and from revised earlier data. The evolution stages of foraminifers, each beginning at the onset of a Boreal transgression, were inferred from species diversity within zones and from changes in their coeval assemblages in different geographic regions of West Siberia. The boundaries between stages are marked by migration of generic and specific taxa into the West Siberian sea. Taxonomic diversity was used as an additional criterion in division and correlation of sections. Generic variations within the studied time span were associated with dramatic abiotic events which were apparently controlled by eustatic transgressions and regressions. Invasion of species- and genus-ranked migrants into the West Siberian Sea marks the borderlines between the stages. The peaks and dips of taxonomic diversity curves for the studied benthos assemblages show good correlation among different regions of West Siberia and with their counterparts in the Russian Platform and northern Central Siberia.

Simulation of the global electromagnetic field as a sum of related electric and magnetic modes simplifies the solutions to both forward and inverse global EM problems. The forward problem (for EM field) is solved with only horizontal or only vertical field components measured on the Earth's surface, and the inverse problem (for conductivity inside the Earth) is solved by fitting of the correlated surface horizontal and vertical components. The component correlation approach to lateral conductivity variations inside the Earth requires neither source modeling nor computing source dependences of impedances and tippers. Processing measured global Sq variations with the new method tentatively indicates the presence of lateral variations in diurnal-period skin depth and in skin-depth average conductivity.

New data on the age of shear deformations in the Ol'khon region (western Cisbaikalia) are reported. The Ol'khon collisional system has an intricate folded structure with three successively formed parageneses: nappe, domal, and shear. Shear deformations appeared at the final stages of the formation of this region and determined its general structure. The age of the deformations has been first estimated by ⁴⁰Ar/³⁹Ar dating of minerals with indications of shearing genesis. It has been established that the shearing took place 445-434 Myr ago, i.e., much later than the peak of metamorphism of granulite facies (480-500 Myr ago). The data obtained also suggest the existence of a thermal event (no earlier than 415 Myr ago), which led to a partial re-equilibration of the isotopic system.

To estimate conditions of heat and mass transfer through plume channel, three kinds of plumes have been recognized: (a) plumes located in oceanic and continental regions far from spreading zones; (b) plumes at the axis of a mid-oceanic ridge, and (c) plumes situated near the ridge axis.
Given geologic and geophysical data, the flow rates of the effused magma have been estimated. The flow rate values permitted us to estimate the thermal power of the source of the plumes formed at the core-mantle boundary. The source powers for the Bouvet, Hawaiian, and Iceland plumes are 1.57 · 10⁷, 3.02 · 10⁸, and 3.78 · 10⁸ kW, respectively.
We have analyzed the heat and mass transfer of a thermochemical plume rising from the core-mantle boundary. The most probable values of melt viscosity in the plume channel and Lewis numbers for a chemical additive which lowers the melting point at the core-mantle boundary have been obtained for plumes with N = (3.0-3.8) · 10⁸ kW, rising for 1-5 Myr. For these Lewis numbers, typical temperature drops ΔT_II between the melting point of the massif and the temperature of plume sole have been found. For the given ΔT_II at Le = 100-1000, such parameters as additive concentration, temperature drop, power, and time and velocity of rise are calculated for the plume source diameters at the core-mantle boundary, d_s, of 70 and 100 km.

The distribution of rare-earth elements (REE) in metasomatites and ores of the Dukat epithermal gold-silver deposit in northeastern Russia has been studied for the first time. The deposit occurs in the sequence of Lower Cretaceous acid effusive rocks intruded by a granite massif. Granites, acid effusive rocks, rhyodacitic ignimbrites, and felsites form a volcanoplutonic association; in leucogranites, ΣREE = 288 ppm. Rhyodacitic ignimbrites contain more REE (191-203 ppm) than felsitic lavas and dikes (105-127 ppm). The ignimbrites and leucogranites have similar proportions of major lanthanide groups - 78_Ce 16_Y6_Sc and 77 _Ce 16 _Y 17 _Sc , respectively. High REE contents have been found in hornfels (up to 254 ppm) and greisens (up to 410 ppm) developed after acid effusive rocks at their contact with the granite intrusion. Processes of pre-ore areal sericitization and hydromicatization in acid volcanics contribute to the REE accumulation in hydrothermally altered rocks of the roof of the Dukat intrusion, particularly in hydromicatized volcanics (up to 404 ppm). Near-ore propylites developed after andesites on the deposit flanks are enriched in REE (up to 174 ppm). Altered argillizites of the central part of the deposit, which host gold-silver mineralization, are depleted in REE (61 ppm). Despite the difference in ΣREE, all wallrocks, irrespective of their composition and spatial occurrence, are enriched in light lanthanides. The Ce/Yb values vary from 37 to 46 in the altered propylites and argillizites and do not exceed 21 in the other wallrocks. The proportion of lanthanide groups in the altered propylites (88 _Ce 10 _Y 2 _Sc ) is nearly the same as in the altered argillizites (88 _Ce 11 _Y 1 _Sc ). In polychronous ores of the Dukat deposit, ΣREE varies over a broad range of values (3.9-37 ppm). High REE contents (up to 37 ppm) have been found in tin-silver-polymetallic ores of deep horizons of the deposit, and low ones, in later formed gold-silver and silver ores of the upper and middle horizons of its central part. Rejuvenated gold-silver ores show a minor variation in ΣREE (5.1-5.7 ppm). Minimum concentrations have been found in the last produced predominantly silver ores (3.9-5.1 ppm). Hydrophile lanthanides of the cerium group prevail in these ores but to a lower degree than in the altered metasomatites. The Ce/Yb values in the ores do not exceed 22.

In the Amur region, a series of gold-ore occurrences belonging to gold-polysulfide-quartz and gold-quartz formations (Tomskoe, Chitkan, Vyruchka, Urusha) have been recognized within the northern periphery of the Argun' terrane. These occurrences are associated with the formation of Late Paleozoic magmatic arc on the active continental margin. The latter is a chain of gabbro-diorite-granodiorite-granite intrusions of the Urusha complex with the isotopic age of 274-278 Ma (U-Pb zircon method), which extend along the structural boundary between the terrane and the Mongolo-Okhotsk fold belt. In geochemical and isotope-geochemical characteristics ((⁸⁷Sr/⁸⁶Sr)₀ = 0.70527-0.70724 at ε _Nd (t) = -1...+2.2) the granitoids of this association correspond to type I and are similar to granitoids of active continental margins. The ore occurrences under study are localized within endo- and exocontact zones of Late Paleozoic granitoids or slightly off them and are quartz-sulfide veinlets inheriting tectonic zones of weakness. Gold contents in the veinlets reach 30 ppm (atomic-absorption analysis). The orebodies are composed mainly of quartz, chlorite, sericite, zoisite, arsenopyrite, pyrite, galena, sphalerite, and chalcopyrite. Gold is present both in free (Chitkan) and in sulfide-associated (Tomskoe) forms. In the latter case, its content in sulfides reaches 300 ppm (chemical-spectral analysis). These ore occurrences evidence that the setting of active continental margin that existed along the northern periphery of the Argun' terrane in the Late Paleozoic favored the formation of various ore objects, including gold-bearing ones. The subsided tectonic blocks of this structure seem to be promising for commercial gold deposits.

The Khorinka volcanoplutonic structure lies in the central part of the Mongolo-Transbaikalian alkali-granite belt (MTB) extending for more than 2500 km through Northern Mongolia and Transbaikalia. The MTB formed in two stages: 280-270 and 230-210 Ma. The Khorinka structure is ca. 3000 km² in area. Syenites and granites prevail at the modern denudation level of its rocks. Only a minor part of volcanic comagmates (bimodal trachybasalt-rhyolite series) has been preserved in this structure. The volcanic stage was preceded by the formation of a bimodal dike belt. Granitoid massifs resulted from the subsequent intrusion of alkali-feldspathic, alkaline, and syenogranitic magmas. Rb-Sr isotope dating has shown that the Khorinka structure was produced at the early stage of the MTB formation (~280 ± 5 Ma). The Rb-Sr ages for alkali granitoids agree with the literature U-Pb zircon ages of these rocks. The (⁸⁷Sr/⁸⁶Sr)₀ value is 0.7073 in alkali and feldspathic granitoids and 0.7033 in syenogranites, which points to different sources of their parental acid magmas.

⁴⁰Ar/³⁹Ar geochronology shows that the formation of the Erdenetiyn-Ovoo porphyry Cu-Mo deposit in Northern Mongolia related to the Erdenet ore-bearing porphyry complex was preceded by multiphase gabbro-granitoid magmatism in the region which produced the 258.6 ± 3.3 and 247 ± 3.7 Ma Selenge granitoids and the 244.6 ± 1.0-239.3 ± 1.4 Ma Shivota complex. The ore-bearing porphyry complex underwent a rhythmic evolution. The main mineralization stage was associated with porphyry magmatism of the first (234.6 ± 1.7 Ma) and second (225.3 ± 1.0-220.3 ± 5.8 Ma) pulses. The ⁴⁰Ar/³⁹Ar age of sericite from metasomatic rocks of the main mineralization stage is 235.8 ± 1.9 Ma. Intrusives of different ages (dated on accessory apatite) and early high-temperature ore formation products (on anhydrite) have low ⁸⁷Sr/⁸⁶Sr ratios of 0.70393-0.70437 corresponding to the mantle values. Mantle sources are likewise indicated by δ³⁴S of sulfides which approach the chondrite norm. Repeated magmatism and mineralization in the Erdenet region provided favorable conditions for the formation of a large porphyry Cu-Mo deposit. Especially important was the rhythmic development of the ore-bearing porphyry complex in which each rhythm was accompanied by mineralization and metasomatism.

A GIS-based technique has been developed to treat georeferenced geologic and hydrogeochemical data for estimating the buried mineralization within the Uronai ore unit. A GIS project is proposed, which includes data on relief, geomorphology, geology, metallogeny, and chemical composition of natural waters. This project turned to be useful in distinguishing several hydrogeochemical anomalies and promising sites with buried ores of molybdenum and tungsten.

The petroleum potential of Mesozoic, Paleozoic and Vendian strata in Stepnoi Altai was investigated using geochemical criteria. Maturity of organic matter, distribution of organic carbon, and the contents and composition of bitumens were studied, with the main focus on the molecular composition of saturated hydrocarbons. Bitumens in Paleozoic and Vendian rocks are depleted in asphaltenes because of high maturity of organic matter (up to metamorphic grade) and display the full range of biomarker hydrocarbons typical of phytoplanktonic and bacterial lipids. According to the geochemical evidence, Paleozoic formations may store small accumulations of asphaltene-free light aliphatic syngenetic oil and condensate.