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listelement.badge.dso-typeЭлемент, NORTH ATLANTIC CONTOURITE SAND CHANNELS(2007) Akhmetzhanov A.; Kenyon N.H.; Habgood E.; Van der Mollen A.S.; Nielsen T.; Ivanov M.; Shashkin P.Two sand-rich channelized depositional systems, formed by strong contour currents, were studied west of the Faeroe Bank Channel and in the Gulf of Cadiz. Both are areas beyond the exit of constrictions where water overflows from the Norwegian Sea and the Mediterranean Sea, respectively. West of the Faeroe Bank, newly mapped channels are developed mainly under the influence of a geostrophic current and are characterized by significant lateral migration, which determines the marked cross-sectional asymmetry and the architecture of the deposits. The pathways of the Mediterranean Undercurrent in the Gulf of Cadiz are complex, with the greater proportion flowing under geostrophic conditions along a terrace but with some of the denser water becoming ageostrophic and descending downslope owing to gravity. A series of 'peel-off' channels is formed, with the largest one, Gil Eanes, being about 40 km long. Most of the channel fills consist of medium-coarse sand. Levees are mainly silts with a higher sand content in the vicinity of the channel. Both depositional systems have a variety of contourite sand channels, which in most respects are remarkably similar. In both cases there are stretches where the flow is ageostrophic, with water descending downslope for as much as 400 m before resuming geostrophic flow at deeper levels. In each case the main pathway of the densest water is the shallowest and several branches turn off to the left of this main pathway before bending to the right under the influence of Coriolis forces. In both cases there are channel fills of medium-coarse sand, probably cross-bedded, and up to 200 ms thick. Sheets of sand with a thickness of a few metres to a few tens of metres are common. Similarities to turbidite channels are the aggradational nature of some channel floors and the flanking muddy or silty sediment waves. Contourite channel depositional complexes are distinguished from turbiditic ones by their coarsening-up rather than fining-up sand units, the asymmetry in channel architecture, the presence of regional unconformities, and the distribution pattern with well-marked boundaries of current-derived deposits.listelement.badge.dso-typeЭлемент, ESTIMATION OF LOADING DENSITY OF UNDERGROUND WELL REPOSITORIES FOR SOLID HIGH-LEVEL RADIOACTIVE WASTES(2007) Malkovsky V.I.; Pek A.A.The convective transfer of radionuclides by subsurface water from a geological repository of solidified high-level radioactive wastes (HLW) is considered. The repository is a cluster of wells of large diameter with HLW disposed of in the lower portions of the wells. The safe distance between wells as a function of rock properties and parameters of well loading with wastes has been estimated from mathematical modeling. A maximum permissible concentration of radionuclides in subsurface water near the ground surface above the repository is regarded as a necessary condition of safety. The estimates obtained show that well repositories allow for a higher density of solid HLW disposal than shaft storage facilities. Advantages and disadvantages of both types of storage facilities are considered in order to estimate the prospects for their use for underground disposal of solid HLW.listelement.badge.dso-typeЭлемент, RECONSTRUCTION OF PALEOHYDRODYNAMIC CONDITIONS DURING THE FORMATION OF UPPER JURASSIC CONGLOMERATES OF THE CRIMEAN PENINSULA(2007) Lalomov A.V.Conglomerates and sandstones related to Upper Jurassic division of Mesozoic rocks make up the Main Range of the Crimean Mountains. Grain size and structural features testify to active hydrodynamic regime of depositional environments. Conglomerates contain a small quantity of exotic granite-granodiorite pebbles and boulders probably transported from the Ukrainian Crystalline Shield situated 400 km north of the Crimean Peninsula. Paleohydrodynamic parameters and transportation mechanisms of debris were modeled with the help of different methods used in geoengineering computations. The results obtained demonstrated satisfactory convergence of the data. The calculations showed that the rocks under investigation were formed during a short (from geological standpoint) but very intense episode of sedimentation related to active tectonic processes that were responsible for the activation of hydrodynamic and sedimentation processes in the paleobasin.listelement.badge.dso-typeЭлемент, DIAMOND, SUBCALCIC GARNET, AND MANTLE METASOMATISM: KIMBERLITE SAMPLING PATTERNS DEFINE THE LINK(2007) Malkovets V.G.; Griffin W.L.; O'Reilly S.Y.; Wood B.J.A genetic relationship between diamond and subcalcic Cr-pyrope garnet, both being produced by a metasomatic process, can be inferred from the sampling patterns of kimberlites in the Daldyn-Alakit province, Yakutia, Russia. Pressure-temperature estimates for xenoliths and xenocrysts show a strong concentration of highly depleted rocks in a well-defined zone 140 190 km deep; diamond inclusions and diamond-bearing xenoliths show that most diamonds come from harzburgites within this layer. Xenocryst distribution curves indicate that diamondiferous kimberlites have sampled both garnet and chromite from the harzburgitic layer, but low-grade pipes have sampled only chromite. Diamond formation probably is due to the oxidation of methane-rich, silica-bearing fluids: Fe2O3 (in chromite) + CH4 → C + H2O + FeO (in chromite), accompanied by another reaction: chromite ± olivine ± orthopyroxene + Si, Ca (in fluid) → low-Ca, high-Cr garnet. The presence or absence of diamond in kimberlites thus reflects the distribution of metasomatized fluid conduits in a lithospheric mantle that originally consisted of highly refractory harzburgites containing neither garnet nor diamond.listelement.badge.dso-typeЭлемент, THE BIBLE AND GEOLOGY: DESTRUCTION OF SODOM AND GOMORRAH(2007) Trifonov V.G.The biblical story of the destruction of Sodom and Gomorrah is interpeted as a reflection of a real natural disaster. According to the Bible, Sodom and Gomorrah were situated near the southern part of the Dead Sea basin or in the Jordan River valley. The description of their destruction in the Bible can be interpreted only as volcanic eruption. Evidence of middle Holocene volcanism is absent both in the Dead Sea and Jordan River regions, but has been found in the Neogene - Quaternary lava highland in the southern Syria. At two settlements, Khirbet El-Umbashi and Hebariye, dated around the second part of the third millennium BC, many animal bones were covered by the basaltic lava. It is possible that, the Bible's story of the destruction of Sodom and Gomorrah combined collective memories about two events. Located in the Dead Sea region, Sodom and Gomorrah were most probably destroyed by a strong earthquake or flood, but the fresh memory about two settlements perishing from a volcanic eruption caused the population to merge these two events.