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Geological, petrological, geochemical, and isotope data from the Yenisei Ridge indicate three stages of rifting and attendant within-plate magmatism at 750, 700, and 670 Ma. The igneous rocks of the three stages are, respectively, metarhyolite-basalt, trachybasalt-trachyte, and alkali ultramafic (alkali picrite) associations. Magmatism was concurrent with terrigenous deposition of the Neoproterozoic Upper Vorogovka, Chingasan, and Chapa Groups. The volcanosedimentary complexes were deposited in narrow rift-like graben along faults. The earlier consolidated flanking uplifts of the graben experienced granitoid magmatism synchronously with rifting and within-plate volcanism. The respective plutonic events produced granitoid intrusions of the Ayakhta (760-750 Ma), Kutukas (690-700 Ma), and Middle Tatarka (~700 Ma) alkaline complexes, and the later (about 650-670 Ma) alkali ultramafic Chapa complex of carbonatites and metasomatites. Basalts and alkaline rocks are chemically similar to ocean-island and continental-rift basalts which have been reliably attributed to mantle plumes. Neoproterozoic rifting and within-plate magmatism were possibly related to the plume activity responsible for the breakup of Rodinia. These events in the Yenisei Ridge appear to be coeval with rifting and within-plate magmatic processes in other continental blocks which may have been parts of the Rodinia supercontinent.

We investigated local geology of Meso-Cenozoic basalt complexes in the Tien Shan and collected the first samples that represent nearly the entire area of within-plate basaltic magmatism in Central Asia (over 285,000 km²). According to their ⁴⁰Ar/³⁹Ar ages, the Tien Shan basalts erupted for a relatively short time span between 61 and 76 Ma, in the Late Cretaceous-Paleogene. The trace- and rare-earth-element compositions of rocks show that most of the studied basaltic series in the Tien Shan formed in within-plate magmatic systems related to mantle plume sources. Some melts bear evidence of crustal contamination. The compositions of melt inclusions and patterns of trace and rare-earth elements in them are consistent with the plume origin of the melts and with the evolution of magmatic systems toward an increase in K, Al, and Fe contents. The melt inclusion data show a direct dependence of the crystallization temperatures of parental melts of the Meso-Cenozoic Tien Shan basalts on their Mg#: 1220-1250

We report new isotope dates and metallogenic and chemical characteristics of granitoids from the Hangayn area (central Mongolia) with implications for the time and tectonic settings of their formation. Proximal U-Pb and Ar-Ar ages of 241.3 ± 1.5 Ma and 238.2 ± 2.5 Ma have been obtained for the Triassic Guchin Us and Hurmen Gol intrusions, respectively, and an Early Permian age (288.7 ± 2.3 Ma, Ar-Ar) for the Bayanulaan granite and for granite porphyry from the Saran Uul Cu-Mo-(Au) deposit. Granitoids of the Egiyn Davaa, Hangayn, and Shar Us Gol complexes in the southwestern Hangayn area are of two geochemical types. Some intrusions that were formerly attributed to these complexes have been reinterpreted as resulting from multiple plutonic pulses of different ages. According to our new data and published evidence, most of granitoids in the area may have been produced by Early-Middle Triassic (255-230 Ma) rather than Permian and Late Triassic-Early Jurassic events. The Hangayn granitoids are of low mineral potential. Gold mineralization in the area is confined within the Hangayn gold belt and appears to be independent of the intrusions.

In the 1980s, Ag-Sb deposits were discovered in a new ore cluster of the Delyun-Yustyd back-arc rift basin in southeastern Altai and northwestern Mongolia. The Delyun-Yustyd basin is filled with up to 9 km thick Devonian volcanosedimentary and terrigenous rocks lying over Vendian-Cambrian carbonate-terrigenous strata. Volcanosedimentary rocks are intruded by D₃-C₁ granites of the Yustyd complex, as well as by pre-granite mafic rocks, post-granite gabbro-diabase, diabase porphyry dikes, and younger lamprophyre dikes of the Chuya complex (245-236 Ma Ar-Ar biotite age). Ag-Sb ores in the Yustyd cluster formed at the Early Mesozoic stage at 240 ± 1.6 Ma (Early-Middle Triassic boundary) and were thus nearly coeval with the Chuya lamprophyre intrusion. The age of Cu-Ag-Sb-Hg mineralization is about 234.4 ± 1.0 Ma (Ar-Ar, sericite). Sb-Hg mineralization is the latest in the province (231.5 ± 1.0 Ma, Ar-Ar, sericite). Gradual change of Ag-Sb (siderite-tetrahedrite) ores to complex Cu-Ag-Sb-Hg (Hg-Ag-tetrahedrite) and Sb-Hg (cinnabar with Sb sulfosalts and stibnite) mineralization along the Kurai-Kobdo and Terekta-Tolbonur large faults is interpreted as development of stage metallogenic zoning along major ore-controlling faults.

Experimental data on the diffusion coefficients of Fe, Mn, Mg, and Ca in garnets are generalized. Frequency factors (cm²/s), activation energies (cal/mole), and activation volumes (cm³/mole) are optimized. Based on the compensation law, the dependences of diffusion coefficients on pressure (kbar) and temperature (K) have been derived:
D _Fe = 1.0 · 10^-3 exp [ - (61450 + 23.9 · 8 · P ) / (RT) ] ,
D _Mn = 2.3 · 10^-6 exp [ - (44600 + 23.9 · 6 · P) / (RT) ] ,
D _Mg = 4.9 · 10^-3 exp [ - (65900 + 23.9 · 9.2 · P ) / (RT) ] ,
D _Ca = 4.1 · 10^-5 exp [ - (62450 + 23.9 · 11.2 · P) / (RT)] .

Three zones of layered series - lower, middle, and upper - composed of dunites and plagiodunites, troctolites and olivine gabbros, gabbros and gabbronorites, respectively, have been recognized in the Luchina massif. The melt that produced the massif rocks was of picrite-basaltic composition (15-16% MgO), and its crystallization took place at 1300-1000

We discovered unusual very small (2 to 70 cm) mafic bodies intruded into metamorphosed Early Carboniferous sandstone and shale in the Late Paleozoic Tastau volcanoplutonic complex (Char shear zone, eastern Kazakhstan). The small intrusions possibly emplaced during shearing when sediments experienced cataclasis and ensuing viscosity decrease. The shear rate was comparable to that in historic crustal earthquakes. Rapid shear motion concurrent with magmatism caused fragmentation of the injecting low-viscosity melt and its dispersal in globular and other bodies along linear breccia zones. The origin of the intrusions is explained in a tectonic model.

The mechanisms and species of gold incorporation into crystals of simple sulfides are described. The concept of endocrypty in its modern treatment and the corresponding technique of experimental study were used. The technique is based on the principle of phase composition correlation and variation of parameters specifying the concentrations of active crystal defects. Gold species are determined with the method of statistical samples of analytical data for single crystals (SSADSC). The highest gold incorporation limits have been established for PbS and CdS under high sulfur fugacity (2.4 · 10^-2 and 7 · 10^-3 wt.%, respectively) at 500

Comprehensive studies have been applied to a core from well 126 in the Chara basin (eastern Baikal-Stanovoy upland). The 1180 m thick drilled section comprises Upper Pleistocene sediments (0-173.1 m) with two intervals of varved silt coeval with the Wurm Glacial, two Middle Pleistocene glacial intervals at 180-263.5 m and 337-424.7 m, earliest Pleistocene (424.7-550 m), Pliocene (550-1036 m), and Miocene (1036-1180 m) strata. The core records the history of Late Cenozoic climate and vegetation for the past 20 Myr (with two large gaps), which has been reconstructed using the pollen analysis. Interpolation of long- and medium-period climate oscillations tied to the time scale allows predicting a trend of possible climate change for the future 2-2.5 kyr.

We have located earthquake hypocenters in the area of central Lake Baikal using the Hypoellipse inversion of direct P traveltimes collected by a local seismological network of seven stations in 2001 through 2005. The location accuracy depends on the agreement between the reference velocity model and the real subsurface. Traveltime residuals have no bearing on the accuracy of depth estimates due to origin time errors.
Hypocenter location with reference to a DSS-derived layered velocity model predicts that the crust is seismogenic between 10 and 22 km. The hypocenters cluster densely in belts trending in NE and SE directions along and across Lake Baikal. Earthquakes become deeper from 10 to 22 km toward the Selenga basin.