Carbonaceous Rocks Research Articles

Zinc(II) Adsorption by Low-Carbon Shungite: The Effect of pH

Shungite is a carbonaceous rock which is abundant in Karelia (Russian Federation). Large deposits of shungite with low levels of carbon (approx. 10% C) are also found in Kazakhstan, where it is mined under the trade name Taurit (Koksu Mining Company). Although Taurit has been reported to be used as an adsorbent for hazardous compounds in water treatment, there is very little precise data about its adsorption capacity or the compounds adsorbed. In this study, the ability of Taurit to adsorb Zn(II) was investigated and Freundlich isotherms were determined for both distilled water and tap water. Taurit was found to have a high buffer capacity leading to pH values > 7.0 in aqueous solution. Because dissolved zinc precipitates as Zn(OH)2 under alkaline conditions, the pH must be carefully controlled and kept ≤7.0. Despite the small inner surface area (BET) of Taurit (13.4 m2 g−1), Freundlich coefficients for distilled water (Kf = 2.4, n = 4.0) and tap water (Kf = 1.5, n = 2.5) were similar to other adsorbents. Our results indicate that Taurit could provide a cheap alternative to activated carbon since both substances have a similar adsorption capacity (at least for Zn(II)).

Evaluation of Remote Sensing Techniques for Lithological Mapping in the Southeastern Pamir using Landsat 8 OLI Data

In this study we test the Landsat 8 OLI data potential for lithological mapping in the Southeastern Pamir. Discrimination of lithological units in the study area has been carried out by utilizing Landsat 8 OLI Satellite data and image enhancement techniques. The approaches consist of spectral enhancement such as independent component analysis (ICA), band ratioing, and false-color composition (FCC). The spectral enhancement techniques were applied in order to extract the initial lithological information, which shows a clear discrimination of granitic rocks from terrigenous and carbonate sedimentary successions. FCC image (OLI bands 6, 7 and 5), color-ratio composite image (OLI 6/5, OLI (7x5)/7, and OLI 6/7), and color composite of independent components (IC6, IC3, IC4) in red, green and blue respectively were found as combinations with more contrast on lithologic information and were used as the input data in supervised classification. Maximum likelihood classification was used to classify resultant images. The results, verified with field observations, demonstrate that different kind of granitoids, terrigenous and carbonaceous rocks can be distinguished and delineated, leading to constriction of geological maps with a better accuracy.

The Features of the Transformation of Organic Matter of Precambrian Carboniferous Rocks of the Ukrainian Crystalline Shield

The main features of the transformation of organic matter (OM) in the greenschist, amphibolite, and granulite facies of metamorphism are considered based on the example of the Ukrainian crystal shield. The occurrence area and OM content in highly carbonaceous ancient rocks are characterized. The composition of primary sedimentary rocks and the processes of accumulation of biophile elements under the OM transformation are reconstructed.

The analysis of creep characteristics of the surrounding rock of the carbonaceous rock tunnel based on Singh-Mitchell model

Carbonaceous rock has the characteristics of easy disintegration, softening, swelling and environmental sensitivity, which belongs to soft surrounding rock, and the deformation during excavation and long-term stability of the surrounding rock of carbonaceous rock tunnel are common problems in the construction of carbonaceous rock tunnel. According to the above, the Monitor and measure the displacement, temperature and osmotic pressure of the surrounding carbonaceous rock of the tunnel of Guangxi Hebai highway. Then it based on the obtaining data to study the creep mechanism of surrounding rock using Singh-Mitchell model and predict the deformation of surrounding rock before the tunnel is operation. The results show that the Singh-Mitchell creep model can effectively analyse and predict the deformation development law of surrounding rock of tunnel without considering temperature and osmotic pressure, it can provide reference for the construction of carbonaceous rock tunnel and the measures to prevent and reinforce it..

Methane sorption and storage characteristics of organic-rich carbonaceous rocks, Lurestan province, southwest Iran

High-pressure-high-temperature methane sorption isotherms have been measured on nineteen samples from the Jurassic Sargelu and the Cretaceous Garau formations in Lurestan province, southwest Iran. Measurements were performed on dry and moisture-equilibrated samples. The study aimed at investigating the effects of pressure, temperature, organic matter and water content on sorption and gas storage characteristics.On the dry samples sorption isotherms were measured between 45 and 130°C at pressures up to 25MPa. Isotherms for the moisture-equilibrated samples were measured at 45°C. An excess sorption function based on the Langmuir model was used to fit the experimental data.The total organic carbon (TOC) contents of the Garau samples range between 0.18 and 5.41wt% and those of the Sargelu samples vary between 0.23 and 15.91wt%. Carbonate is the dominant mineral in both sample sets, followed by quartz and clay minerals. No clear correlation was found between TOC content and porosity of the samples, indicating multiple factors controlling the abundance and volumes of both organic and inorganic pores.A linear correlation between sorption capacity and TOC value was found for both sample sets. Due to the larger variance in TOC values this relationship was more obvious for the Sargelu samples. Clay minerals constitute only a minor component of these carbonate-rich rocks. Therefore, as expected, no correlation was observed between sorption capacity and clay content. Organic matter content thus is the pivotal factor controlling methane sorption capacity.With increasing temperature the excess sorption capacity decreases while the Langmuir pressure increases, as evidenced by decrease in the initial slope of the isotherms.A negative correlation was observed between water content and sorption capacities and a positive correlation between water content and the Langmuir pressure (PL).The total gas storage capacity of the two sample sets was estimated as a function of depth based on all measured data and representative temperature and pressure gradients. Sorption generally tends to dominate the total storage capacity of shale gas systems in the low-depth/low-pressure range (as high as 90% depending on TOC content and specific pore volume), whereas in the great-depth/high-pressure range the volumetric storage capacity prevails.

Liberation of hydrogen-containing gases during closed system pyrolysis of immature organic matter-rich shales

The liberation of hydrogen sulfide (H2S), molecular hydrogen (H2) and hydrocarbon gases as well as CO2 from three immature carbonaceous rocks has been studied by Micro-Scale Sealed Vessel (MSSV) pyrolysis in the temperature range from 350 to 600°C at a heating rate of 1°C/min. The samples analyzed were the lacustrine Miocene Condor Shale from Australia (CON-1) and two marine marlstones (HBY-1 and HBY-2) from Southern Lebanon, with different contents of total sulfur (TS; 0.38–1.6%), total organic carbon (TOC; 3.7–11.6%) and total inorganic carbon (TIC; 2.8–9.3%). The Condor Shale has a high siderite (FeCO3) content (20.3%) and 0.2% pyrite (FeS2). The total iron (Fe) content is 10.5% and the kerogen is sulfur-lean. The iron (Fe) contents of the HBY samples are below 1% (0.9% and 0.3%, respectively) and insignificant amounts of pyrite are present, indicating a predominance of organic sulfur (sulfur-rich kerogen) with Sorg values of >1%. The low Rock-Eval Tmax values support the presence of sulfur-rich, labile kerogen.CO2 was the major pyrolysis gas released from the CON-1 over the entire pyrolysis temperature range while no H2S was detected at any temperature level. The molar H2 yields tend to exceed the CH4 yields up to 475°C while at higher pyrolysis temperatures CH4 is the predominant hydrogen-containing product gas. For the HBY-1 and HBY-2 samples H2S and CO2 are the major product gases up to 450°C. Up to this temperature H2S is also the predominant hydrogen-bearing gas component. Subsequently methane and ethane yields exceed the molar H2S yields. At higher temperatures an increasing proportion of hydrogen is released as H2. Ultimately the molar H2 yields approach or even exceed the H2S yields from the sulfur-rich HBY samples.At pyrolysis temperatures<450°C the sulfur-rich kerogens liberate more hydrogen as H2S than as CH4 and H2. At high temperatures hydrogen release as H2 and H2S is less significant. These results indicate that, besides the amounts of molecular hydrogen released, the liberation of H2S should be taken into account for a comprehensive H mass balance of organic sulfur-rich source rocks. Approximately 50% of the hydrogen in sulfur-rich kerogen is released as CH4 during cracking at high temperatures (600°C).

Relationship of oil seep in Kudat Peninsula with surrounding rocks based on geochemical analysis

This study aims to investigate the relation of oil seepage at Sikuati area with the structural and petroleum system of Kudat Peninsula. The abundance of highly carbonaceous rocks with presence of lamination in the Sikuati Member outcrop at Kudat Peninsula may give an idea on the presence of oil seepage in this area. A detailed geochemical analysis of source rock sample and oil seepage from Sikuati area was carried out for their characterization and correlation. Hydrocarbon propectivity of Sikuati Member source rock is poor to good with Total Organic Carbon (TOC) value of 0.11% to 1.48%. and also categorized as immature to early mature oil window with Vitrinite Reflectance (VRo) value of 0.43% to 0.50 %Ro. Based on biomarker distribution, from Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS) analysis, source rock sample shows Pr/Ph, CPI and WI of 2.22 to 2.68, 2.17 to 2.19 and 2.46 to 2.74 respectively indicates the source rock is immature and coming from terrestrial environment. The source rock might be rich in carbonaceous material organic matter resulting from planktonic/bacterial activity which occurs at fluvial to fluvio-deltaic environment. Overall, the source rock from outcrop level of Kudat Peninsula is moderately prolific in term of prospectivity and maturity. However, as go far deeper beneath the surface, we can expect more activity of mature source rock that generate and expulse hydrocarbon from the subsurface then migrating through deep-seated fault beneath the Sikuati area.

Mineralogical and Geochemical Compositions of the Lopingian Coals and Carbonaceous Rocks in the Shugentian Coalfield, Yunnan, China: with Emphasis on Fe-Bearing Minerals in a Continental-Marine Transitional Environment

This paper presents the mineralogical and geochemical compositions of coal benches and non-coal (carbonaceous rock benches, parting, roof and floor) samples from the No. 1 Coal in the Longtan Formation of the Permian-Lopingian epoch from the Shugentian Coalfield, eastern Yunnan Province, southwestern China. The coal is rich in Nb, Ta, Zr, and Hf, which were derived from the Kangdian Upland with the dominant compositions of the Emeishan basalt. The minerals identified in the samples include mixed-layer illite-smectite, kaolinite, quartz, siderite, and minor calcite, pyrite, anatase and ankerite. Albite and chamosite occur in the roof and floor samples. The parting sample (SGT1-2p) is characterized by abundant siderite (64.9%) and calcite (20.1%), and one carbonaceous rock sample SGT1-11 contained a large amount of pyrite (26.1%). Four factors were responsible for the geochemical and mineralogical compositions in the samples; namely, the terrigenous detrital materials transported from the Kangdian Upland, direct volcanic ash inputs, multi-stage inputs of hydrothermal fluids, and marine influences. The co-existence of siderite and pyrite was attributed to a continental-marine transitional environment.

Assimilation of sulfate and carbonaceous rocks: Experimental study, thermodynamic modeling and application to the Noril’sk-Talnakh region (Russia)

Most of the intrusions in the Noril’sk-Talnakh region (Siberia) are hosted in thick sedimentary sequences including abundant evaporitic and terrigenous sedimentary rocks. Three mafic-ultramafic intrusions in this region contain unusually thick massive sulfide deposits, which represent one of the world’s largest economic concentrations of Ni, Cu and PGE. The interaction of Siberian magmas with sulfate and organic matter-rich sedimentary rocks has been proposed as a possible mechanism for the origin of these exceptional sulfide deposits but the interaction process and the reaction paths have never been fully investigated. Here we clarify, by both experimental petrology and thermodynamic modeling, how sulfate and organic matter assimilation occur in mafic-ultramafic magmas, affecting magma composition, crystallization and sulfide saturation.Interaction experiments were conducted at conditions relevant to the emplacement of Noril’sk type intrusions (1200°C, ∼80MPa) to simulate the assimilation of sulfate and/or organic compounds by ultramafic magmas. We used a picrite from Noril’sk1 intrusion, and coal and anhydrite from the area as starting materials. The experimental results show that the incorporation of anhydrite into the magma occurs by chemical dissolution in the melt, which increases the magma’s sulfur content, but suppresses sulfide saturation and reduces olivine crystallization. Extreme assimilation leads to sulfate saturation in the magma and high dissolved sulfur contents of 0.9±0.1wt% S. Conversely, coal assimilation promotes sulfide segregation and magma crystallization, while decreasing the dissolved H2O content of the melt and increasing the amount of coexisting fluid phase.We also employed gas-melt thermodynamic calculations to quantify the effect of these assimilations on the redox conditions and the S content of the magma, and investigate the role of temperature, pressure, and initial gas content of the magma in the assimilation process. We quantify how sulfate assimilation strongly oxidizes the magma and increases its S content; both effects are intensified by increasing pressure (from 50 to 100MPa in this study), decreasing temperature (from 1350 to 1200°C in this study), and decreasing amounts of fluid phase initially coexisting with the magma (from 2 to 0wt%). The interaction with organic matter (CH in this study) induces a strong reduction of the magma, even for extremely low degrees of assimilation (few tenths of wt%), and the dehydration of the melt.We therefore suggest that in the Noril’sk-Talnakh district (1) additional S was supplied to mantle derived magmas by the assimilation of evaporitic rocks, and was transported during magma ascent in the form of dissolved, oxidized S; (2) a substantial reduction of the magma inducing sulfide segregation and important crystallization then occurred due to the interaction with carbonaceous sediments. This mechanism can potentially produce massive sulfide deposits by important sulfate assimilation (locally higher than 3wt% CaSO4) and minor organic matter assimilation (few tenths of wt% CH); however, if one of the two steps does not occur, or the assimilation in (1) is not large enough, disseminated sub economic or no sulfide deposits are produced. We conclude that exceptional conditions favoring substantial assimilation of sediments are needed to generate exceptional ore deposits like those of the Noril’sk-Talnakh district.

Development of the principles of an integrated process for extraction of high-purity graphite, gold, and rare earths from carbonaceous rocks

Graphite-bearing rocks of the Ruzhinskaya area (Primorskii Krai, Russia) were found to contain high concentrations of noble and rare earth metals. Industrial exploration of these reserves is restrained by the lack of concentration technique. The application of hydrometallurgy for the production of useful components was studied for the first time. A prospective plan of integrated extraction of high-purity graphite, gold and rare earths using hydrogen fluoride treatment of flotation concentrates was designed.

Organic geochemistry of rocks of the Mesoproterozoic Malgin Formation and their depositional environments (southeastern Siberian Platform)

Organic matter (OM) and rocks of the upper member of the Mesoproterozoic Malgin Formation in the southeastern Siberian Platform have been studied by modern research methods. Analysis has revealed homologous series of alkanes, tricyclanes, and hopanes in the bitumens. Leiosphaeridia crassa, L. minutissima, cf. Leiosphaeridia tenuissima, cf. Glomovertella, and Oscillatoriopsis sp. have been identified among the rare microfossils preserved in mudstones. Geochemical, lithological, and paleontological studies have shown that bacterial microcommunities and, to a lesser extent, eukaryotic microorganisms were the main source of OM. Based on results of sedimentological analysis and study of biomarkers, the depositional environment has been reconstructed. A model for the accumulation of black shales and carbonate rocks of the Malgin Formation is considered. The hypothesis that the highly carbonaceous rocks formed in uncompensated depressions of shallow epicontinental marine suboxidation environments is substantiated. The petroleum potential and degree of OM catagenesis of the Malgin Formation rocks are evaluated. Pyrolysis, bitumen analysis, and hydrocarbon composition study have revealed autochthonous and parautochthonous bitumens in the oil shales, mudstones, and carbonate rocks. The obtained data show that the Malgin Formation rocks might have participated in petroleum generation in the Uchur-Maya region.

Natural gas dehydration by molecular sieve in offshore plants: Impact of increasing carbon dioxide content

Dehydration is a critical operation in natural gas conditioning as it reduces the potential for corrosion, hydrate formation and freezing in process equipment and transportation pipelines. Water dew point adjustment is particularly challenging in the remote ultra-deepwater natural gas reserves of the Brazilian Pre-Salt fields due to their very high carbon dioxide contents – from 30% up to 90% in raw natural gas – which is a consequence from the carbonaceous rock of the reservoir structure and long term elevation of carbon dioxide content due to its injection for early enhanced oil recovery. Under this scenario, the study evaluates the impact of the carbon dioxide content of the natural gas on the performance of water dew point via water adsorption on 4Å Zeolite molecular sieve beds. Process simulation with adsorption simulator Adsim (Aspen Technology, Inc), at varying operation pressures and carbon dioxide contents in raw natural gas, indicated that, although adsorption meets water removal specification in a condensation free operation, the high fugacity of carbon dioxide penalizes the dehydration performance due to probably two facts: (i) higher carbon dioxide fugacity in the humid natural gas imply higher saturation water content in the gas phase, which increases the service of dehydration units; and (ii) higher carbon dioxide fugacity in the humid natural gas establishes a discreet adsorption competition with water resulting in 6.5% increase of adsorbent bed volume for operating pressures of 35bar or higher.

O carvão da Jazida de Morungava (RS, Brasil): Caracterização petrográfica, química e tecnológica das camadas de carvão do poço de exploração CBM 001-MO-RS

Tendo em vista a necessidade ampliação da matriz energética nacional, torna-se premente desenvolver estudos em jazidas carboníferas não exploradas (e.g. Jazida de Morungava), onde pesquisas ulteriores datam da década de 1980. A fonte mineral situa-se no nordeste do Rio Grande do Sul, ocupando uma área de 250 km2 . Para avaliar o potencial da jazida carbonífera (CBM- 001-MO-RS) e sua economicidade, foi realizada a caracterização petrográfica, química e tecnológica das camadas obtidas (num total de seis), com 387,70 m de profundidade, espessura cumulativa de carvão de 9,22 m. Obteve-se um total de 27 amostras, utilizadas à determinação dos seguintes parâmetros: descrição de litotipos do carvão, refletância da vitrinita, contagem de macerais, análises imediatas, poder calorífico superior, enxofre total, difração de raios-X e teste de beneficiamento. O litotipo carvão fosco predomina nas amostras, com um rank variando de carvão betuminoso alto volátil A a antracito. As distintas camadas apresentam progressiva intrusão vulcânica sotoposta. O grupo maceral vitrinita predomina nos carvões na porção inferior, enquanto inertinita predomina na superior. Matéria mineral tende a apresentar acréscimos da base ao topo. Os carvões apresentaram elevados teores de cinza (&gt;50% m.b.s.), matéria volátil (6,04-30,69% m.b.s), enxofre (0,20-2,88% m.b.s.) e poder calorífico superior (777-4.732 Kcal/Kg). Há predomínio mineralógico de quartzo, caulinita, e illita. Muitas das camadas são classificadas como rocha carbonosa (&gt;50% cinza/b.s.). Os ensaios de beneficiamento indicaram baixo rendimento (&lt;7% vol.) na obtenção de produtos nobres.

Fluid inclusions and C-H-O-S isotope systematics of early Permian porphyry Mo mineralization of the West Junggar region, NW China: the Suyunhe example

ABSTRACTThe Suyunhe porphyry Mo deposit, located in the West Junggar terrane, is the largest molybdenum deposit found in Xinjiang to date, with a proven reserve of 0.57 Mt. The Suyunhe deposit is associated with Early Permian granitic rocks, which emplaced into the volcano-sedimentary sequences of the Middle Devonian Barluk Formation. Four metallogenic stages are identified in this study. Stage I is marked by the quartz-magnetite-K-feldspar±biotite±pyrite±molybdenite veins, which mainly occurred in the intensively potassic alternation zone and were formed at high temperature (>481°C), high salinity (58.6−65.18 wt.%), and relatively high oxygen fugacity conditions with a fluid system of NaCl-H2O-CO2. Stage II is the main metallogenic stage and develops numerous quartz-molybdenite±pyrite veins associated with muscovite–chlorite alteration, which were formed by immiscible fluids at medium-high temperature (210−427°C), medium-high salinity (43.36−49.90 wt.%), and relatively low oxygen fugacity conditions with the fluid system of NaCl-H2O-CO2-CH4-C2H6. After the main Mo-mineralization, quartz-polymetallic sulphides veins associated with quartz–sericite alteration were formed by fluids at medium-low temperature, low-salinity conditions with the fluid system of NaCl-H2O-CO2 in stage III. The following quartz-polymetallic sulphide veins are quartz-calcite±pyrite veins associated with calcite alteration, which were formed by fluids at low temperature and low-salinity conditions with a fluid system of NaCl-H2O in stage IV.The δ18O‰ values indicate that the ore fluids of stages I and II are dominated by magmatic water, whereas stages III and IV are dominated by meteoric water. A wide range of δ34S‰ values (−7.1 to 3.4‰) of sulphides between stages I and II indicates that increasing the reducibility plays an important role in molybdenum mineralization. The δ13CCH4 values suggest that CH4 of the ore fluids mainly results from the assimilation–contamination of carbonaceous country rocks, and partly derives from magma. However, the δ13CCO2 values suggest that CO2 of the ore fluids mainly originates from magma, and minor derives from wall-rocks as well as meteoric water.

Holocene climate change influences on trace metal and organic matter geochemistry in the sediments of an Arctic lake over 7,000 years

This study employed a 6.48 m long dated sediment core to characterize the amount of variation in background trace metal concentrations, and develop an understanding of the role of climatic influences on sediment inorganic and organic geochemistry in a High Arctic lake over ∼7000 years of the Holocene. Element geochemistry reflected varying detrital contributions from two geological sources within the catchment: carbonates (dolomites and limestones) which provided the dominant major element by weight (i.e., Ca), and carbonaceous mudrocks (primarily shales) which may have contributed most of the other trace and minor elements. The presence of eroded shale-hosted organic matter (OM) in sediments was confirmed by reflectance measurements on reworked vitrinitic macerals which had similar values to Palaeozoic carbonaceous rocks in the watershed. Bimodal distribution of the reflectance data suggested that two sources of vitrinitic macerals were present, from different formations. Variable dilution of shale-sourced elements by carbonates, related to climate (temperature)-influenced rates of dissolution and erosion, was the dominant process controlling inorganic geochemical composition. RockEval pyrolysis of bulk sediment OM revealed the unusual finding of two distinct sources of sediment kerogen which alternated in importance during the Holocene: a “baseline” state of eroded shale-hosted OM which was probably always present but which dominated sediment OM when autochthonous (algal) production was minimal, and an “enhanced algal state” which dominated when limnological conditions favored higher autochthonous productivity. Periods with more frequent examples of the enhanced algal state occurred during the mid- and late-Holocene, coincident with periods of relatively high summer air temperatures in the region. This study provides evidence that climate, particularly air temperature, influenced sediment inorganic and organic geochemical compositions in this lake through its effect on catchment geology erosion rates and aquatic primary productivity. It shows the value of studying very long periods of sediment accumulation as a background context for recent sediment metal concentrations.

Key directions in processing carbonaceous rocks

Key directions in processing carbonaceous rocks

Geochemistry and geochronology of mylonitic metasedimentary rocks associated with the Proterozoic Miaowan Ophiolite Complex, Yangtze craton, China: Implications for geodynamic events

Constraining the timing of tectonothermal events in the Proterozoic Miaowan Ophiolite Complex (MOC) and associated rocks in the southern Huangling dome, Yangtze craton, is critical for understanding late Mesoproterozoic and Neoproterozoic tectonic evolution (ca. 1.2–0.9Ga) of South China and its relationship with the formation of the Rodinian supercontinent. The MOC consists of metamorphosed dunite and harzburgite, isotropic and layered gabbros, diabasic sheeted dike, basalt, plagiogranite, and calc-silicate-bearing siliceous and carbonaceous mylonitic rocks. In this study, we present new field, petrographic, geochemical, geochronological and isotopic data for these metasedimentary rocks and mylonitic metasandstone between the ophiolite and underlying flysch sequence, to unravel their origin and tectonic significance for the Yangtze craton. The MOC and associated sedimentary rocks underwent amphibolite facies metamorphism. Geochemical data and field relationships indicate that the mylonitic metasandstone was derived from both the autochthonous rocks of the underlying Yangtze craton and the allochthonous MOC during the accretion of the ophiolite to the craton. The calc-silicate-bearing siliceous and carbonaceous rocks are interpreted as tectonic slices of metasomatized and mylonitized chert and limestone, respectively, deposited on the basaltic crust in a Neoproterozoic ocean. Cores of igneous detrital zircons in the calc-silicate-bearing siliceous and carbonaceous mylonitic rocks have yielded two distinct age groups including a 967–1105Ma (Mean=1009Ma) group and a 1011–1095Ma (Mean=1054Ma) group. The majority of initial εHf(t) values (+9.2 to +14.1) in the zircon cores are similar to those of zircons from the gabbro, diabase and plagiogranite in the MOC, indicating that zircons in the mylonitic rocks were mainly derived from the MOC. Metamorphic overgrowth ages in zircon rims suggest that the latest tectonothermal event in the Precambrian basement rocks of the Yangtze craton took place between 942 and 935Ma. These metamorphic ages are comparable to those of the Grenvillian-aged collisional events recorded in orogenic belts worldwide. Accordingly, we suggest that this youngest tectonothermal event represents the latest amalgamation time of the heterogeneous tectonic blocks of the Yangtze craton, which were associated with the assembly of the Rodinian supercontinent.

Geochemical peculiarities of ores from the largest Natalka gold deposit in Northeastern Russia

This study of the behavior of trace and rare earth elements in ores from the Natalka gold deposit allows us to draw several conclusions. It is suggested that ore formation is related to the regional metamorphism of the host terrigenous carbonaceous rocks, which could be the major source for trace and rare earth elements. Minor enrichment of the Natalka ores in W is evidence of the contribution of magmatic fluid, which could be superimposed on early quartz veins, in ore formation. Our results support the metamorphic–magmatic model of formation of economic gold–quartz deposits of the Yana–Kolyma Belt. The similarity of metasomatites of the Natalka deposit with disseminated gold–sulfide refractory ores from the Nezhdaninskoe and Bakyrchik deposits points to the possible presence of such ores in the Natalka deposit. Our data are important for forecasting regional metallogenic reconstructions, search, and evaluation of gold deposits.

Soil and geobotanical, typological characteristics of bottomland forest with short-term flooding Poltava-city green belt

Carrying out its assignment Poltava-city green belt bottomland forests with short-term flooding, has significant anthropogenic impact, needs constant research of forest biogeocoenosis present day condition. There have been done the complex research of bottomland forests with short-term flooding which are located in the range of Poltava-city green belt. Forest types according to O. L. Belgard have been noted. Soil and geobotanical characteristics, soil sections macromorphological peculiarities have been given, results of soil water extracts analysis in the investigated forestry have been noted. Throuout the complex researches of all components of forest biogeocoenosis the learning of forest and environment coorelation that is due to anthropogenic effect is topical. Especially it concerns the big cities green belt of industrial regions that suffer from the human direct influence or indirect consequences of his living. Thereby the National special-purpose program «Forests of Ukraine» for 2010–2015 was approved the aim of which is a complex study of this category of forest-steppe zone forest biogeocoenosis. For this reason was made an accent to investigate all-round the Poltava-city green belt forests related to Poltava Region throuout the regional special-purpose program of forestry integrated development «Poltava region forests by 2015». To identify the soil and geobotanical characteristics of biogeocenosis and physical and chemical piculiarities of bottomland forests with short-term flooding adaphotop we will consider the most typical sample plots of different plantations according to its forest stand that grows in relatively identical conditions. Forest areas of Poltava-city green belt belongs to the eastern soil and climatic forest-steppe zone of Poltava Region and is situated in forest-stepp belt of Left bank of Dnipro inside the Dnipro and Donetsk dimple. The most common soils are deep, low humic chernozem and middle clay-loam soil. There are mulch and sandy, agrilloarenaceous soils in river valleys. The picture of exploration area ground structure looks in such a way. The most common ground species of the area is a loess-like clay loam. There are sands observed near the river bed of Vorskla and clay on steep slopes. Soddy-meadow and chernozem-meadow, sandy loam and clay loam soils are involved in the bottomland forests formation. Typical chernozem occupies significant territories, which is formed by herbaceous grouping of mesoxerophytes, euxerophytes and xeromesophytes. Floodplain soils are divided into three parts: riverine, central and terrace near flood plain. In the riverine part is formed the most light mechanical components of interbedding soils formed on new derived silt from slightly humic layers. There are a low percent of humus (not more than 1 %) and nutritional chemicals. Thereby their fertility is low. In the central part of floodplain had been formed the sandy loam and clay loam soils with stronger profile on the massive, often calcareous or carbonaceous parent rock material. In cases of flood the water is widely overflowed and stay for a long time rich in sludge particles. It is the richest soils of the floodplain. The done research gave us the opportunity to clear up that the bottomland forests with short-term flooding of Poltava-city green belt are consist mainly of oak, aspen and alder forests. The formation and distribution of the main associations of floodplain forests depend on the regime of floodplain, trophotop and relief inhomogenuity. It was noticed that it can be found three more typical natural forest vegetations related to bottomland forests with short-term flooding inside the Poltava-city green belt: Dc' 3 (moist linden oak forest with hairlike sedge), Dn / 4 (alder forest with muddy tall herbaceous vegetation), Dc / 2 (live aspen forest with). It was noticed, that in all investigated plant formations the forest site type is sandy loam with different variations: live (SP / 2), moist (SP / 3), muddy (SP / 4). Different variations of soil has been investigated. There is no carbonate in soils of the investigated biogeocenosis. Water extract analysis tell about the lack of salinity properties, dry particles ranges (0,05–0,2 %), pH is alkaline. Detailed soil and geobotanical characteristics and establishing peculiarities of bottomland forests with short-term flooding adaphotop will give opportunity to reconstruct the existing Poltava-city green belt plantations and organize the stationary investigations with the aim of their more rational employment and saving.

Precious and Rare Metals in Overburden Carbonaceous Rocks: Methods of Extraction

Precious and Rare Metals in Overburden Carbonaceous Rocks: Methods of Extraction