Measurements of the surface layer turbulence in the urban area

The turbulence characteristics measured in the surface layer over a real underlying surface are presented. The measurements are carried out at the 3- and 16-m levels using acoustic anemometers; at the lower level, the measurements are doubled. The diurnal cycle is obtained of the temperature flux and friction velocity. To obtain the temperature flux, so-called “acoustic” temperature is used as calculated from the sound speed data with corrections for air humidity and pressure. The normalized characteristics of turbulence are presented as dependent on dimensionless height z/L. The values of temperature flux and friction velocity increase with height: their day-integral values at 16-m level exceed those at 3-m level for about 20 and 35%, respectively.     

Newania carbonatites, Western India: example of mantle derived magnesium carbonatites

The key mineralogical features of the Newania carbonatites, that illustrate their derivation from primary mantle melts (Gruau et al. Terra Nova, Abstract Suppl 1:336, 1995; Viladkar Petrology 6(3):272–283, 1998; Basu and Murty Abstracts of Goldschmidt Conference A40, 2006), are the presence of magnesite, graphite and Cr-rich magnetite. Magnesite is an early crystallizing phase. Cr-rich magnetite and graphite coexist with carbonatite minerals and precipitated from carbonate magma. Graphite, as well as gaseous CO₂ and carbonate minerals such as dolomite and magnesite, can be stable in peridotite mantle. Coexistence of these minerals is controlled by fO ₂ and PT-conditions. Mineral geothermometers for the Newania carbonatite give temperatures from 463 to 950°C. The parental source for Newania carbonatites was characterized by a relatively high log (fHF/fH₂O) level which increased during the crystallization history of Newania. The estimated oxygen fugacity (for ilmenite–magnetite pairs) varies from ?1.5 to +3.5 (log-bar unit deviation from FMQ buffer), which is supported by the presence of Fe-columbite, and the composition of phlogopite, amphibole and pyroxene that have an elevated concentration of Fe³⁺. However, the oxygen fugacity range represented by co-existing early-crystallized graphite and magnesite is below that of the FMQ buffer and lies on the CCO buffer.     

Substantiation of the use of gaseous sorbed hydrocarbons as indicators of technogenic load impact on natural environments

This article describes the patterns of distribution of sorbed gaseous hydrocarbons in dispersed rocks of oil and gas areas to determine the possibility of using them as indicators of water pollution. Sorbed gaseous hydrocarbons have a number of geochemical properties that contribute to their influence on technological conditions and long-term preservations of the changes that occur in their composition in man-made conditions.     

Nd-Sr systematics of metamagmatic rocks of the Anginskaya and Talanchanskaya Formations,middle part of Lake Baikal

The paper presents data on the Nd-Sr systematics of magmatic rocks of the Khaidaiskii Series of the Anginskaya Formation in the Ol’khon region, western Baikal area, and rocks of the Talanchanskaya Formation on the eastern shore of Lake Baikal. Geochemical characteristics of these rocks are identical and testify to their arc provenance. At the same time, the ɛ_Nd^tof rocks of the Khaidaiskii Series in the Ol’khon area has positive values, and the data points of these rocks plot near the mantle succession line in the ɛ_Nd^t-⁸⁷Sr/⁸⁶Sr diagram, whereas the ɛ_Nd^t values of rocks of the Talanchanskaya Formation are negative, and the data points of these rocks fall into the fourth quadrant in the ɛ_Nd^t-⁸⁷Sr/⁸⁶Sr diagram. This testifies to a mantle genesis of the parental magmas of the Khaidaiskii Series and to the significant involvement of older crustal material in the generation of the melts that produced the orthorocks on the eastern shore of the lake. These conclusions are corroborated by model ages of magmatic rocks in the Ol’khon area (close to 1 Ga) and of rocks of the Talanchanskaya Formation (approximately 2 Ga). The comparison of our data with those obtained by other researchers on the Nd-Sr isotopic age of granulites of the Ol’khon Group and metavolcanics in various structural zones in the northern Baikal area suggests, with regard for the geochemistry of these rocks, the accretion of tectonic nappes that had different isotopic histories: some of them were derived from the mantle wedge and localized in the island arc itself (magmatic rocks of the Anginskaya Formation) or backarc spreading zone (mafic metamagmatic rocks of the Ol’khon Group), while others were partial melts derived, with the participation of crustal material, from sources of various age (metagraywackes in the backarc basin in the Ol’khon Group and the ensialic basement of the island arc in the Talanchanskaya Formation).     

Chemical composition and geochemical characteristics of the Koksharovka alkaline ultrabasic massif with carbonatites,primorye

New geochemical data are discussed on the magmatic complexes of the Koksharovka alkaline ultrabasic massif of Late Jurassic age obtained by the ICP-MS method. Based on the first results on rare earth geochemistry of carbonatites and associating pyroxenites and geological observations, the magmatic origin of the Koksharovka carbonatites was substantiated, and the problems of formation of accompanying igneous rocks were considered.     

Geochemical features of the drusite massifs,the central part of the Belomorian mobile belt: I. Distribution of major and trace elements in the rocks

The comparative-geochemical study was first conducted for the ultrabasic-basic massifs of the central part of the Belomorian mobile belt, which were previously ascribed to the drusite complex on the basis of the presence of coronal textures. The studied magmatic bodies are geochemically heterogeneous and can be subdivided into three groups: (1) high-Mg rocks (MgO > 20 wt %) with elevated Cr content, enriched trace element patterns, and deep negative Ta-Nb anomaly (Sorkajoki Massif). Intrusions of this group are geochemically close to the layered plutons of Northern and Eastern Karelia (Kivakka, Burakovsky) and to the intrusions of the Kola Peninsula (Monchepluton and others); (2) low-Mg intrusions (MgO < 10 wt %) with elevated contents of Fe, Ti, and P (403-m Height Massif). The rocks composing these intrusions are characterized by subhorizontal trace element patterns and weak Ta-Nb anomaly; (3) intrusions with intermediate MgO contents (10–20 wt %), flat, occasionally depleted REE patterns, and lack of Ta-Nb anomaly (Mt. Grob Tundra). The identified geochemical differences do not depend on the degree of metamorphic transformations, but were presumably caused by differences in phase and chemical composition of parental magmas, as well as by conditions of their crystallization. It was substantiated that ultrabasic-basic massifs presently united into the drusite complex are genetically diverse and acquired similar textural appearance due to regional metamorphism. Thus, the presence of coronal textures is insufficient to ascribe the intrusions to the drusite complex, their mineralogical and geochemical composition should be taken into account.     

Nature of the structural and crystal-chemical heterogeneity of the Mg-rich glauconite (Riphean,Anabar Uplift)

The detailed mineralogical and structural-crystal-chemical characteristics are reported for the first time for glauconite grains extracted from the fine-platy silty-sandy dolomites at the roof of the lower subformation of the Yusmastakh Formation (Riphean, Anabar Uplift, North Siberia). Based on the complex study (X-ray diffraction, classical chemical analysis, microprobe analysis, IR-spectroscopy, thermogravimetric analysis, scanning electron microscopy with microprobe analysis, and Mössbauer spectroscopy), it was demonstrated that the studied glauconite sample is characterized by unique chemical and structural heterogeneity.The mineral structure consists of micaceous (90%), smectite (6%), and di-trioctahedral chlorite (4%) layers. Mica is classed with Al-glauconite (Al > Fe³⁺) with elevated Mg content. The elevated Mg mole fraction of the mineral is caused by the presence of Mg-bearing brucite-type interlayers of di-trioctahedral chlorite and the high Mg content in the octahedral sheets of 2: 1 layers. It was first discovered that glauconites are characterized by the heterogeneous distribution of cations over the available trans- and cis-octahedra due to the coexistence of trans- and cis-vacant octahedra and small trioctahedral clusters in octahedral sheets. The distribution of isomorphic cations over the accessible octahedral sites is also heterogeneous due to the tendency of Fe, Mg and Al, Mg cations to segregation and formation of corresponding domains.It was found that structure of the studied glauconite has a specific stacking defect: in addition to the predominant subsequent layers of similar azimuthal orientation according to 1M type (～77%), some layer fragments are rotated at 180° (～15%) and ±120° (8%). The structural-crystal-chemical heterogeneity of the mineral is explained by the fact that its microcrystals grew in the dolomitic sediment under nonequilibrium conditions of the reduction zone of a shallow-water basin with a sufficiently high content of Mg cations, which significantly contributed to the glauconite formation.     

Phosphorites of the Chiatura manganese deposit and specific features of their formation

The paper presents results of the detailed study of phosphorites from manganiferous beds of the Chiatura deposit. The relatively high-grade (P₂O₅ 20–28%) phosphorites are represented by various rocks ranging from the variety dominated by massive phosphates with a rare aleuritic admixture of quartz and feldspar grains to rocks mainly composed of terrigenous material with phosphates in the matrix. Phosphates make up the matrix of various organic remains: differently preserved diatom algae and microbial species. Some relatively large organic remains (in particular, sponge spicules) are typically composed of iron minerals (with manganese admixture) rather than phosphates. Manganese ores comprise phosphorite fragments composed of phosphatized cyanobacterial mat. Phosphorites of the Chiatura deposit were likely formed in a shallow-water zone away from the continental land.     

Rb-Sr geochronology of Vendian shales,the Staraya Rechka Formation,Anabar Massif,northern Siberia

Fine-grained clayey subfractions (SF) with particle sizes of 1–2, 0.6–1.0, 0.3–0.6, 0.2–0.3, 0.1–0.2, and <0.1 μm were extracted from shales of the Vendian Staraya Rechka Formation in the Anabar Massif and studied by XRD and Rb-Sr methods. All the clayey subfractions are represented by illite with high crystallinity indices, which are characteristic of the low-temperature diagenesis/catagenesis zone and grow with the decrease of the particle size. The Rb-Sr systematics in clayey subfractions combined with mineralogical data provide grounds for the conclusion that illite from clayey rocks of the Staraya Rechka Formation was forming during two periods: approximately 560 and 391–413 Ma ago. The first illite generation was likely formed in the course of lithostatic subsidence of the Staraya Rechka sediments and the second one, during the Devonian lithogenesis stage. It is assumed that age of the first generation (∼560 Ma) is close to that of the Staraya Rechka Formation. This inference is consistent with biostratigraphic, chemostratigraphic, and geochronological data obtained for both rocks of the Anabar Massif and Vendian sediments from other regions of Siberia.