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A decade of integrate litho-, magneto-, and biostratigraphic studies in joint projects yielded new data on the Pliocene-Pleistocene stratigraphy of Transbaikalia. Upper Cenozoic deposits are mostly slope wash in Western Transbaikalia and alluvium in Eastern Transbaikalia. Paleontological constraints have been obtained for a number of formations in the two subregions. In Western Transbaikalia they are the Lower Pliocene Anosov, Middle Pliocene Tologoi, and Middle Neopleistocene Krivoi Yar Formations, and in Eastern Transbaikalia they are the Lower and Middle Pliocene, and Upper Pliocene-Eopleistocene Ikaral, Torei, and Tsasuchei Formations, respectively, the Lower and Middle Neopleistocene Kholui and Kholbon Formations, the Lower Eopleistocene Ust'-Obor solifluction slope wash, and the upper Middle Neopleistocene Borzhigantai alluvium. The Middle Pliocene-Holocene section of Western Transbaikalia includes eleven successive mammal assemblages and the Eastern Transbaikalian section includes four faunas of which three are equivalents of the Chikoi, Tologoi, and Upper Paleolithic assemblages from Western Transbaikalia. The correlation among the faunal assemblages was used to correlate the Neogene-Quaternary sections from the two subregions and made a basis for a single scale of the Cenozoic stratigraphy of Transbaikalia.

In March, 2002, two fields of globular granular ice (so-called

A new analytical solution for approximate integral functions that describe the electromagnetic field from dipole sources in layered conducting media at small wave numbers is applied to a three-coil loop in a medium with a single interface.

A new analytical algorithm for the gradient of residual functionals is applied to numerical inversion of seismic data from horizontally layered media. The algorithm works for any linear differential equation and second-order system where the coefficients are piecewise constant functions. It is advantageous due to its plain logic and easily programmable formalism.

First paleomagnetic results for a 53 m core obtained from the HÖvsgÖl lake deposits (Mongolia) in the framework of the Russian-Mongolian joint project are presented. On the basis of measured inclination of natural remanent magnetization (NRM), three distinct polarity zones corresponding to Brunhes and Matuyama Chrons and Jaramillo Subchron have been recognized. Intervals with shallow NRM inclination are interpreted as possible geomagnetic excursions. Using the boundaries of both polarity zones and excursions as time marks, sedimentation rate of lake deposits is calculated. Several layers with different magnetic properties have been distinguished within the core section. The periodic repetitions of layers with different characteristics, probably, reflect variations in magnetic material input to the lake, changes in water salinity, and fluctuations of the lake level.

We studied multiphase symmetrical dikes that cross-cut Triassic tuff lavas in the Kamen' alkali mafic province in the northern Siberian craton, especially, the structure of vitreous and crystalline dikes, their petrography, major-element compositions, and mineralogy. The dike swarm has a symmetrical structure produced by compositionally similar left-hand and right-hand half-dikes. The dikes show five phases of melt injection. Vitreous dikes are composed of olivine-clinopyroxene or occasionally picritic (in the center) porphyry. Each half-dike consists of a quench contact with spherulites of silicic glass and carbonate and an inner zone with feldspar, and feldspar with kaersutite and/or mica. Early phases in crystalline dikes are variolitic clinopyroxenites and late phases are picritic porphyry. The rock chemistry and mineralogy indicate presumably limburgite composition of the parent melt. The multiphase dikes originated by repeated melt injection into pulse-like opening fractures whereby the melt moving along the magma conduit underwent differentiation with separation of magnesian fluid. Overcooling of the limburgite melt in the dikes provided separation of carbonatite and alkali-silicic fluids and heteromorphic crystallization of variolitic clinopyroxenites.

Granites of the Late Mesozoic Kukul'bei ore-bearing complex in the Aga structure-formational zone of eastern Transbaikalia are studied. It is shown that the concentrations of incompatible trace elements in them are correlated with the domal morphology of the roof of granite intrusive systems of the Kukul'bei complex. Massifs of biotite granites of the major intrusive phase (MIP) are localized in the centers of domes formed in enclosing sand-shaly rocks, and younger ore-bearing leucogranite (usually muscovite) differentiates occur on the flanks of the axial, most uplifted, zones of the domes. The studied granites are highly aluminous and potassic. The MIP granites are enriched in granitophile trace elements, including Sn, W, Be, Ta, and volatiles, which are of plutonic genesis. The enrichment is shown to be of local character: The most enriched granite bodies occur in the axial zones of domes, whereas granites with lower concentrations of trace elements (as low as their clarkes), in the peripheral, least uplifted, zones of the domes. Rare-metal mineralization is localized in leucogranites drastically depleted in Sr and Ba; its productivity is directly correlated with the concentrations of trace elements in the leucogranites.
The granites of intrusive systems of the Kukul'bei complex, localized in deep-fault zones, might be enriched in trace elements (including volatiles F and B) as a result of their supply with mantle fluids. This process led to the formation of crustal granite magma chambers of ore-bearing rare-metal intrusions. Their subsequent evolution during the fluid supply resulted in leucogranite differentiates enriched in trace, ore-forming, and volatile elements, which were the major source of ore-bearing fluids and hydrotherms at the postmagmatic stage.

Study is given to the petrography, geochemistry, ⁴⁰Ar/³⁹Ar age, and geodynamic settings of the formation of volcanics from boreholes drilled in the Uralian part of the West Siberian syncline (upper reaches of the Severnaya Sos'va River) in recent years. Carboniferous and Permo-Triassic basalts and scarcer basaltic andesites, trachybasalts, and basaltic tuffs have been recognized here. Heterochronous basalts differ in the degree of paleohypergene and greenstone alteration and in geochemical parameters.
The Carboniferous and Permo-Triassic basalts are rocks of calc-alkalic series with normal or, less often, moderate alkalinity. They have moderate contents of K, but some Carboniferous samples are poor and some Permo-Triassic samples are rich in it. Both types of basalts, particularly the Permo-Triassic ones, are enriched in incompatible elements relative to N-MORB.
According to geochemistry, the Carboniferous basalts are island-arc volcanics, and the Permo-Triassic ones are rift trap rocks, which are widespread in the Upper Permian and Triassic strata of the West Siberian syncline.

Not only hydrodynamic but also eolian processes have an effect on placer formation. Our experimental, mineralogical, and field studies as well as analysis of recent literature data permitted us to recognize a new morphologic type, eolian gold, and a new genetic type of gold deposits, eolian placers. Eolian gold is represented by gold flakes with ridgelike edges, toroidal grains and hollow spheroids 0.1 to 0.25 mm in size, as well as by compact disc-shaped, flat gold particles with ridgelike edges, and lump-shaped ones covered with a specific fibrous membrane measuring 0.25 mm and more. In addition to gold particles characterized by eolian features, gold-crustated quartz occurs. Analysis of distribution of eolian gold shows that the above-mentioned shapes of gold are widespread in Proterozoic-Cenozoic deposits almost in all platforms of the world. The eolian gold occurrences are well correlated with fragmentally developed surfaces of deflation paleodeserts, the halo of which can be reconstructed from findings of ventifacts. Both arid and nival climates are favorable for eolian placer formation because the epoch of glaciation is characterized by intense eolian processes that gave rise to placer formation. Eolian gold placers may be formed as the result of long-lasting activity of unidirectional winds owing to the deflation of a primary source itself, gold-bearing crusts of weathering or previously generated alluvial, beach, and other placers of varying genesis. We suggest to divide them into eolian gold placers and heterogeneous ones, i.e., eolian-proluvial, eolian-alluvial, eolian-marine, etc. Eolian gold placers have a specific structure: The producing horizon overlies the deflation surface like a blanket, with its thickness extremely small (tens of centimeters), and is complicated by jet series. This horizon is usually composed of sandstones and gravel with a low content of argillaceous matter containing ventifacts and wind-worn gold particles. The eolian gold placers are divided into autochthonous and allochthonous. Autochthonous deflation placers are generated by denudation of a primary source matrix either with deflation of the crust of weathering formed in the primary source or with deflation of the placer previously formed. Allochthonous eolian placers are basal (transit) and dune ones. Basal eolian placers are confined to the eolian denudation surface and are mainly developed in deflation basins and grooves. Allochthonous dune placers of gold occur between denudation and accumulation zones. Lying far from the primary source, they have no economical value because the metal particles that migrated together with blown sands are very small, dispersed, with low contents of gold. Not only remarkable shapes of gold particles and character of their surface, but also ventifacts, specific structure of producing bed, deflation relief structures, i.e., grooves and basins, and typical lithology of sedimentary deposits are exploration tools for revealing eolian gold placers. As far as wind-worn gold particles are not only of mineralogical interest but also form high concentrations of the metal, e.g., in the Witwatersrand gold placer, we believe that the discovery of eolian gold placers of varying age in platforms all over the world is quite promising, in particular, in the eastern European, Siberian, North American, South American, African, and Australian Platforms as well as in Tuva and Mongolia.

The Late Precambrian Uchur-Yudoma hypostratotype includes the Uchur-Maya plate (a depression in the southeast of the Siberian Platform), the Yudoma-Maya pericratonic trough, and the Okhotsk microcontinent. The sequence of stratigraphic units ranked groups and formations has surely been established for all these structures, but the location and nature of boundaries between them as well as their age are still debatable. The information available casts doubt upon many universally accepted concepts. It is proven that the Maya Group giving rise to the Mayanian, the lower Neoproterozoic unit, overlaps the entire region under study, being in contact with diverse older units. However, its starting Kerpyl Subgroup is not coeval with the entire Ennin Formation completing the Lower Riphean in the western Uchur-Maya plate but only with a separate member of deposits erroneously considered its part. The pre-Kerpylian tectonic rearrangement contributed much to the specific paleogeography of the region, which is also commonly associated with the pre-Vendian events alone. The Kerpylian was preceded by an accretion to the Siberian craton of its surrounding microcontinents while the supercontinent Rodinia was completing its formation. Nothing of the kind occurred prior to the formation of the Lakhanda Subgroup closely connected with the Kerpyl one. The pre-Kerpylian changes in phytolith and microfossil biotas served as a base for the paleontological substantiation of the lower boundary of the Upper Riphean. Their specific character that appeared in the Kerpylian continued to develop in the Lakhanda Subgroup. Therefore, there is no need to distinguish the Lakhandinian as a separate group to oppose it to the Kerpylian. The data reported show that the lower boundary of the Neoproterozoic is not younger than 1100 Ma.
A persistent sequence of K-Ar and Rb-Sr ages corresponding to the available paleontological data shows that the Ui Group formed in the range 750-650 Ma. This does not contradict U-Pb and Sm-Nd ages (about 1000 Ma) obtained from its cutting dikes. These figures indicate the age of the magma chamber rather than the time of their intrusion. The Ui Group dated in this way and its analogs in other regions correspond only to the upper half of the Baikalian and Cryogenian of the International Scale (850-650 Ma). This conclusion is in discrepancy with the common opinion that the Ui Group is closely connected with the Lakhandinian. In the same way, a number of formations disappear from the Ui Group leaving no trace, while on the eastern slope of the Omnya rise, the Ust'-Kirbi Subgroup completing the Ui Group rests immediately upon the Lakhandinian. These relationships are due to the regressive structure of the Ui deposits, where the event nature marking the beginning of a new group is masked by the considerable subsidence of the Yudoma-Maya trough. It is related to the extension that accompanied the breakup of the supercontinent Rodinia. In other parts of the Siberian craton where this process was accompanied by intense compression, the beginning of the Baikalian has a distinct event basis and an appropriate complex of basal deposits. Because of the complex event nature of the Baikalian in Siberia some geologists refer it partly to the Middle Riphean using U-Pb ages of dikes, whereas the others date some part of the Baikalian by the Vendian. Neither thinking is true because of the Late Riphean age of the paleontological remains. The event nature of the Vendian, the upper unit of the Neoproterozoic, is due to the repeated accretion to the Siberian craton of its surrounding microcontinents, which triggered the Caledonian tectonic activity. The principal character of the events limiting the main Neoproterozoic stratons in Siberia makes them promising as units of the General Stratigraphic Scale of Precambrian.