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Experimental and theoretical research into the processes of radon emanation during failure of rocks has been carried out. We propose a physical model for the mechanisms of origin of anomalies of radon volume activity. Based on the obtained experimental data, relative changes in the open porosity and specific inner surface of rock during its failure have been studied.

Earthquake nucleation and fracture propagation in deformed rocks generate elastic waves, within acoustic frequencies. Strain-induced acoustic waves appear both in field tectonic structures and in laboratory samples, thus making laboratory acoustic emission (AE) data from load tests suitable to interpret natural seismic processes. However, laboratory tests are commonly run at room temperature, while the natural rocks at the earthquake origin depths are as hot as hundreds of degrees centigrade. We report AE data for thermally and mechanically loaded granites subjected to impact fracture at different temperatures. The energy distribution in the time series of acoustic signals emitted from fine-grained granite fits a power law of the type of the Gutenberg-Richter relationship at temperatures from 20 to 500 ºC. Medium- and coarse-grained samples behave in this way only within 300 ºC but show a Poissonian (random) AE energy distribution above 300 ºC.

Phase change of dielectric magnesiowьstite in the lower mantle may leave signatures in geomagnetic records of the globally distributed array of observatories. The related features appear in EM induction responses of lower mantle, which are studied theoretically. The surface EM field corresponding to a response of the earth with conductivity anisotropy in a mantle spherical layer is presented as the sum of the magnetic and electric modes. Equations for the fields of both modes and their relationship in a weakly anisotropic earth are obtained by the perturbation method. The two field modes are analyzed jointly and separately to characterize the conductivity tensor of the anisotropic lower mantle. The tensor elements corresponding to the tangential components of the field can be estimated from the magnetic mode alone recorded currently by the global network of geomagnetic observatories. For the tensor data to be complete, observatory data on lateral variations of the electric field are required in addition to three-component geomagnetic records.

The mantle structure in Central Asia was investigated by surface-wave tomography from dispersion of the fundamental mode of the Rayleigh wave group velocities along more than 3200 earthquake-station paths within 40º N to 60º N and 80º E to 132º E. The velocities were processed by the frequency-time analysis at periods from 10 to 250 s to obtain their dispersion curves. Then group velocity maps were computed separately for each period, at different sampling intervals: at every 5 s for the short periods from 10 to 30 s, at 10 s for periods between 30 and 100 s, and at 25 s for the longest periods of 100 to 250 s. Resolution was estimated according to the effective averaging radius (R) and presented likewise in the form of maps. To estimate the depths of the revealed inhomogeneties, locally averaged dispersion curves were calculated using the group velocity maps, with reference to the radius R , and were then inverted to S-wave velocity-depth profiles. The resulting three-dimensional S-wave velocity structure to depths of about 700 km revealed large lateral inhomogeneties through the entire depth range. This pattern may be due to the history of the major tectonic structures, as well as to ongoing processes in the mantle.

We present data on the composition of metasedimentary rocks from the greenstone belt of the Onot terrane (Sharyzhalgay uplift) and results of U-Pb dating (SHRIMP II) and Lu-Hf isotope study of detrital zircon from garnet-staurolite schists. The metasedimentary rocks of the Onot greenstone belt are dominated by garnet- and staurolite-bearing schists alternating with amphibolites (metabasalts) in the upper part of the section. Compositionally the protoliths of garnet-staurolite schists correspond to sedimentary rocks, ranging from siltstone to pelitic mudstone. The trace-element characteristics of the garnet-staurolite schists indicate that the terrigenous material was derived from three different rock types, such as tonalite-trondhjemite plagiogneisses (elevated Gd/Yb ratios), mafic rocks (elevated Cr/Th ratios and reduced Th/Sc ratios), and felsic igneous rocks formed by crustal melting (the presence of a Eu minimum), which agrees with the set of potential source rocks from the Onot terrane. The age of predominant detrital zircon reflects the erosion of mainly Neoarchean igneous rocks; this fact, combined with the poor rounding of zircon and tectonically active sedimentation conditions accompanied by mafic volcanism, suggests that the probably depositional age is ca. 2.7 Ga. Older source rocks (2.80–3.35 Ga) contributed to the sediment deposition along with the Neoarchean ones. According to the Hf isotope composition of detrital zircon from the garnet-staurolite schists, the source provenances had different crustal prehistories. The source provenances include Paleoarchean and juvenile Neoarchean crust and rocks formed by the mixing of melts from ancient and juvenile crustal sources.

On the northeastern slope of the Kuznetsk Alatau, small differentiated alkaline basic intrusive massifs form an isometric area ~100 km across. They are composed of subalkalic and alkali gabbroids, basic and ultrabasic foidolites, nepheline and alkali syenites, and carbonatites. Results of complex (U-Pb, Sm-Nd, and Rb-Sr) isotope dating suggest that alkaline basic magmatism developed at two stages in the Middle Cambrian-Early Ordovician (~510-480 Ma) and in the Early-Middle Devonian (~410-385 Ma). Finding of accessory zircons (age 1.3-2.0 Ga) in alkaline rocks suggests that the ascent of mantle plume was accompanied by the melting of fragments of Proterozoic mature continental crust composing the basement of the Caledonian orogen of the Kuznetsk Alatau. Probably, parental Cambrian-Ordovician alkaline mafic melts initiated metasomatism and lithosphere erosion. During the next melting of lithosphere substrate in ~100 Myr, this caused the generation of magmas of similar composition with inherited isotope parameters (ε_Nd(T) ≈ +4.8 to +5.7, T_Nd(DM) ≈ 0.8-0.9 Ga) pointing to the similar nature of their matter sources in the moderately depleted mantle.

We present results of isotope-geochemical studies of Late Paleoproterozoic basites from intrusions located in different parts of a dike swarm traceable for more than 200 km within the Baikal marginal salient of the Siberian craton basement (northern Baikal area). The basites of the southern (Khibelen site) and northern (Chaya site) parts of the dike swarm show both similarity and difference in their sources and formation conditions. For example, the Khibelen basites correspond in chemical composition to basalts and trachybasalts, and the Chaya basites, to basalts and andesite-basalts. Based on petrographic and petrochemical data, the basites of both sites can be referred to as medium-alkali (subalkalic) series. All analyzed basites show distinct negative Nb-Ta and Ti anomalies on element spidergrams, negative ε_Nd(T) values, and indicative geochemical ratios Th/Nb_pm, La/Nb_pm, and La/Sm_n > 1. All this points to the formation of basites of both sites from mantle sources contaminated with continental crust. Contamination might have occurred in intermediate magma chambers localized in crust. Differentiated basic varieties of both sites resulted from fractionation of clinopyroxene. For the Khibelen basites, the mantle source (probably, with geochemical parameters close to those of IAB) might have been initially contaminated with middle-crust rocks and then, with lower/upper crust material. The source of the Chaya basites was, probably, produced during the interaction of mantle components similar in composition to IAB and N-MORB with a crustal component. The performed studies testify to the heterogeneous composition of the upper mantle beneath different sites of the Siberian craton basement.

The abundance of various chemical elements (including trace, rare-earth, and radioactive) in the carbon dioxide mineral waters of the Choigan complex has been investigated. Three groups of waters are recognized according to the geochemical conditions and chemical composition: groundwaters of regional-jointing zone with oxidizing conditions; CO₂-enriched groundwaters of regional-jointing zone with oxidizing conditions; and groundwaters of fault zones with reducing conditions. It is shown that water-rock interaction intensified by high temperature and carbon dioxide action is the main process determining the chemical composition of groundwaters.

We present new original data on the geochemistry of scandium in the coals of Asian Russia, Mongolia, and Kazakhstan. In general, the studied coals are enriched in Sc as compared with the average coals worldwide. Coal deposits with abnormally high, up to commercial, Sc contents were detected in different parts of the study area. The factors for the accumulation of Sc in coals have been identified. The Sc contents of the coals depend on the petrologic composition of coal basins (composition of rocks in their framing) and the facies conditions of coal accumulation. We have established the redistribution and partial removal of Sc from a coal seam during coal metamorphism. The distribution of Sc in deposits and coal seams indicates the predominantly hydrogenic mechanism of its anomalous concentration in coals and peats. The accumulation of Sc in the coals and peats is attributed to its leaching out of the coal-bearing rocks and redeposition in a coal (peat) layer with groundwater and undergroundwater enriched in organic acids. The enrichment of coals with Sc requires conditions for the formation of Sc-enriched coal-bearing rocks and conditions for its leaching and transport to the coal seam. Such conditions can be found in the present-day peatland systems of West Siberia and, probably, in ancient basins of peat (coal) accumulation.

A natural oil seep has been revealed in the floodplain of the middle stream of the Amga River, in zone of the exposure of Middle Cambrian sediments. A distinctive feature of saturated hydrocarbons of this oil is the absence of biomarkers of the series 12- and 13-methylalkanes, biomarkers that are present in oils of the Vendian-Cambrian deposits of the Nepa-Botuobiyan petroliferous province. In this feature the studied seep oil is similar to the Middle Cambrian oil from hydrogeologic wells (1-P and 1-T) drilled earlier downstream of the Amga River.