The structure of the lithosphere in area of junction between the Okhotsk sea and the continental tectonic structures

The area of junction of the Ul'in volcano-tectonic structure of the Okhotsk-Chukotka volcanic belt and tectonic structures of Okhotsk Sea has both fundamental interest - for understanding tectonics and geodynamics on the outskirts of the continent, and practical - for assessing the metallogenic potential of the territory, primarily for gold. The main subject of the present studies was the deep unhomogeneities and disjunctive tectonics, clarification of the block structure of the lithosphere. The creation of a deep base was carried out by means of a complex interpretation of geophysical data (maps of gravity and magnetic fields), data of the Deep Seismic Sounding profile of the north-eastern section of the 3-DV profile (Skovorodino-Tommot-Khandyga-Myakit), geophysical and geological information. The main tool for geopotential fields data processing was the computer technology “KOSKAD 3D” intended for processing of three-dimensional digital geoinformation by the methods of probability-statistical analysis. Three types of 3D gravity field models up to a depth of 90 km are calculated: 3D distribution of low-frequency characteristics; 3D distribution of high-frequency characteristics; density 3D models. An analysis of petrophysical information was carried out on a formalized basis with subsequent compilation of specialized petrodensity and petromagnetic maps. The obtained 3D models allowed to construct sections and slices of the gravity field components, density of the lithosphere at different depth levels. Cartographic, geophysical and petrophysical materials formed the basis for a map of faulty tectonics in the region.The main disruptive disorders are ranked in the direction (northeastern, northwestern, sublatitudinal, submeridional), by the depth of deposition (mantle, lower crust, medium-crustal, upper crustal, near-surface), by their specialization - (blocking, magma-leading). According to the density model, the mantle part of the lithosphere is dense enough both for the continent and for the Okhotsk Sea. In the earth's crust, the Dzhugdzhur-Okhotsk and Mongol-Okhotsk fault systems divide the continental part of the territory into three regions: high-density - western and eastern (coastal), and central - decompressed ones. The Dzhugdzhur-Okhotsk northeastern system of disturbances is a regional boundary between a dense and reduced density lithosphere on the continent. Geologically, it can be regarded as the boundary of the ancient (Jurassic-Cretaceous) paleosubduction, during which a belt of a granitized decompressed lithosphere formed. The boundary of the junction of marine and continental structures does not coincide with the coast line: marine structures rise under continent, indicating a collision between the Okhotsk Sea and the Eurasian plate. Probably, the Jurassic-Cretaceous subduction regime on the outskirts of the Eurasian plate was replaced by a collision one in the Cenozoic, as a result of which the Ul'in volcano-tectonic structure was divided by northwestern faults into transverse blocks. The subsequent intraplate marginal rifting caused the Coastal (Mongol-Okhotsk) fault to “creep” of continental deposits onto “marine” tectonic structures. The results of the performed studies made it possible to better understand the nature of the interaction of the tectonic structures of the southwestern margin of the Okhotsk Sea. The deep-seated schemes of fault tectonics and the transformant of the gravitational field can be used for palinspastic reconstructions. The constructed petrophysical maps have prospects for further multi-functional application. The received structural basis can become the basis of studying laws of formation of mineral deposits

Electron correlation effects in electron-hole recombination in organic light-emitting diodes

We develop a general theory of electron--hole recombination in organic light emitting diodes that leads to formation of emissive singlet excitons and nonemissive triplet excitons. We briefly review other existing theories and show how our approach is substantively different from these theories. Using an exact time-dependent approach to the interchain/intermolecular charge-transfer within a long-range interacting model we find that, (i) the relative yield of the singlet exciton in polymers is considerably larger than the 25% predicted from statistical considerations, (ii) the singlet exciton yield increases with chain length in oligomers, and, (iii) in small molecules containing nitrogen heteroatoms, the relative yield of the singlet exciton is considerably smaller and may be even close to 25%. The above results are independent of whether or not the bond-charge repulsion, X_perp, is included in the interchain part of the Hamiltonian for the two-chain system. The larger (smaller) yield of the singlet (triplet) exciton in carbon-based long-chain polymers is a consequence of both its ionic (covalent) nature and smaller (larger) binding energy. In nitrogen containing monomers, wavefunctions are closer to the noninteracting limit, and this decreases (increases) the relative yield of the singlet (triplet) exciton. Our results are in qualitative agreement with electroluminescence experiments involving both molecular and polymeric light emitters. The time-dependent approach developed here for describing intermolecular charge-transfer processes is completely general and may be applied to many other such processes.Comment: 19 pages, 11 figure

Early carboniferous brachiopod faunas from the Baoshan block, west Yunnan, southwest China

38 brachiopod species in 27 genera and subgenera are described from the Yudong Formation in the Shidian-Baoshan area, west Yunnan, southwest China. New taxa include two new subgenera: Unispirifer (Septimispirifer) and Brachythyrina (Longathyrina), and seven new species: Eomarginifera yunnanensis, Marginatia cylindrica, Unispirifer (Unispirifer) xiangshanensis, Unispirifer (Septimispirifer) wafangjieensis, Brachythyrina (Brachythyrina) transversa, Brachythyrina (Longathyrina) baoshanensis, and Girtyella wafangjieensis. Based on the described material and constraints from associated coral and conodont faunas, the age of the brachiopod fauna from the Yudon Formation is considered late Tournaisian (Early Carboniferous), with a possibility extending into earlyViseacutean.<br /

Application of Landsat-7 satellite data and a DEM for the quantification of thermokarst-affected terrain types in the periglacial Lena-Anabar coastal lowland

Extensive parts of Arctic permafrost-dominated lowlands were affected by large-scale permafrost degradation, mainly through Holocene thermokarst activity. The effect of thermokarst is nowadays observed in most periglacial lowlands of the Arctic. Since permafrost degradation is a consequence as well as a signifi cant factor of global climate change, it is necessary to develop effi cient methods for the quantifi cation of its past and current magnitude. We developed a procedure for the quantifi cation of periglacial lowland terrain types with a focus on degradation features and applied it to the Cape Mamontov Klyk area in the western Laptev Sea region. Our terrain classifi cation approach was based on a combination of geospatial datasets, including a supervised maximum likelihood classifi cation applied to Landsat-7 ETM+ data and digital elevation data. Thirteen fi nal terrain surface classes were extracted and subsequently characterized in terms of relevance to thermokarst and degradation of ice-rich deposits. 78 % of the investigated area was estimated to be affected by permafrost degradation. The overall classifi cation accuracy was 79 %. Thermokarst did not develop evenly on the coastal plain, as indicated by the increasingly dense coverage of thermokarst-related areas from south to north. This regionally focused procedure can be extended to other areas to provide the highly detailed periglacial terrain mapping capabilities currently lacking in global-scale permafrost datasets

Grain-size properties and organic-carbon stock of Yedoma Ice Complex permafrost from the Kolyma lowland, northeastern Siberia

The organic carbon stock in permafrost is of increasing interest in environmental research, because during the late Quaternary a large pool of organic carbon accumulated in the sedimentary deposits of arctic permafrost. Because of its potential to degrade and release organic carbon, the organic-matter inventory of Yedoma Ice Complex deposits is relevant to current concerns about the effects of global warming. In this context, it is essential to improve the understanding of preserved carbon quantities and characteristics. The paper aims to clarify the Yedoma Ice Complex origin, and to develop an approach for volumetric organic-matter quantification. Therefore, we analyzed the grain size and the organic-matter characteristics of the deposits exposed at the stratigraphic key site Duvanny Yar (lower Kolyma River, northeast Siberia). A distinct bimodal grain-size distribution confirms a polygenetic origin of the frozen sediments from a flood-plain environment. The total organic-carbon content averages 1.5 ± 1.4 wt% while the volumetric organic-carbon content averages 14 ± 8 kg/m³. However, large-scale extrapolations for Yedoma Ice Complex deposits in general are not reasonable yet because of their rather unclear spatial distribution. We conclude that Yedoma Ice Complex formation at Duvanny Yar was dominated by water-related (alluvial/fluvial/lacustrine) as well as aeolian processes. The total organic-carbon content of the studied deposits is low if compared to other profiles, but it is still a significant pool