Carbonate postsedimentation processes studies by electron paramagnetic resonance

© SGEM2014. All Rights Reserved. The purpose of this study was to show possibilities of the electron paramagnetic resonance (EPR) method on the example of carbonate rocks Lodemskoy area Zimnebrezhnogo diamond district by separating inhomogeneities in them and identifying indicators going changes. In calcite ions Mn2+ replace Ca2+, and in dolomite occupy positions as Ca2+ as well as Mg2+ positions. Although the basic form of the iron presence in carbonates is Fe2+, but with an increase in the medium oxidation potential some part of the impurity iron as Fe3+ is included a Ca2+ position in calcite and position Mg2+ in dolomite. EPR spectrometer X-band PS 100X (ADANI, Minsk) for recording the spectra at room temperature was used with including Al2O3:Cr3+ crystal in the side hole of the cavity as internal standard lines. Postsedimentary processes carbonates may be explained by the fact that in this area developed ultrabasic rocks (kimberlitic), which is a hotbed for ions Cr, Mn, Fe, Mg which migrate as a true solution and diffuse into the structure of the carbonates, the cations occupying the position that resulted in neoplasm of calcite and dolomite

Contact zone gypsum - Carbonate sediments by electron paramagnetic resonance

© SGEM2014. All Rights Reserved. The purpose of this work is to study geochemical features in the contact zone of gypsum - carbonate deposits by the electron paramagnetic resonance (EPR) method on the example of the typical core samples Syukeevskogo field. Choosing the annealing temperature of 350, 600 and 950 °C is associated with decomposition of organic matter and carbonates. Five different kind contact zones of gypsum-carbonate strata Syukeevskogo field along the borehole were selected. Quantitative changes of the EPR parameters: Mn2+, Fe3+, Cr3+, α and radicals caused by thermochemical effects on the rock and organic matter are presented in the diagram forms. Geochemical features installed in the contact zones such as a manganese increase in the newly formed calcite, a decrease α in sample oil-saturated, a reason of calcium excess or magnesium deficiency at increase alpha are discussed

Thermal annealing derivatives of technogenic gypsum by electron paramagnetic resonance

© SGEM2016.Previously dehydration products EPR spectra of single crystals of gypsum (“Marino glass”) have been studied in the temperature range from 100 to 425 °C [Crystall. Reports, 2014, Vol. 59, No. 3, pp. 399]. In this work, the subject of study was selected technogenic gypsum and its derivatives dehydration [Procedia Earth and Planet Sci. Vol. 15, 2015, P. 579].Temperature region of formation gypsum, alpha and beta phase states of bassanite and gamma-anhydrite, insoluble anhydrite were determined from the EPR spectra of radical ions and the atomic hydrogen. Obtained results may be used for the control in the technological processes of gypsum materials production, and scientific purposes

Insoluble anhydrite as product gypsum dehydration according to electron paramagnetic resonance spectra

© SGEM2015. Electron paramagnetic resonance studies were carried out with two main aims. Firstly, to detect the appearance of an insoluble phase anhydrite formed due to the dehydration of gypsum. Secondly, to study the dynamics of development of insoluble phases in the dehydration sequeonce in natural gypsum. Annealing gypsum products ("Marino steklo") are mineral polyphase system, in which there are co-crystallization and recrystallization processes to form a system of point defects in each f the phase components of the mixture. Found that in the range 25-450 °C temperature annealing products may include gypsum, α and β bassanite, α and β soluble anhydrite, insoluble anhydrite (Crystallography. Reports, vol.59(3), pp.399, 2014). In this paper, we continue the detailed study of the formation of the crystalline structure of the insoluble anhydrite during dehydration. It was found that the lines of the EPR spectra of radical ions that are typical of structure of natural anhydrite, begin to appear with 225 °C. In the temperature range 275-350 °C dehydration formation of an insoluble anhydrite becomes the dominant process. In the temperature range from 225 to 450 °C during the dehydration of gypsum was recorded the birth and formation of the EPR lines, structurally different radical ions SO2 - , SO3 - and atomic ion-radical О-

Peculiarities gypsum crystals structure based on electron paramagnetic resonance radiation defects

© SGEM2016.Electron paramagnetic resonance (EPR) at 77 K in the X-band are studied natural gypsum crystals (“Marino” glass, Russia), previously irradiated at room temperature by X-rays of different doses. Detected earlier observed spectra of paramagnetic centers SO-3(B); SO-3(A1); SO-3(A2)[Crystallog. Rep., vol. 59(3), pp.399–406. 2014]. It was found two new spectrum with magnetic multiplicity KM = 2 (Ci symmetry center) and super hyperfine splitting of the interaction of the electron spin S = 1/2 and the proton nuclear spin I = 1/2. These spectra are assigned to the centers SO-4 —1H, which differ from each other in the position of a proton H(1) gypsum structure. The mobility of water molecules in the channels of the structure activates the formation of two or more centers SO-4―1H, SO-3―1H. From the angular dependence of the spectra in the three orthogonal planes were found the parameters of the spin Hamiltonian (SH). It has been established that the differences in radiation sensitivity of the paramagnetic centers depends on charge redistribution processes in the crystal

Phase states of the gypsum thermal-annealing derivatives according to electron spin resonance spectra

The electron spin resonance (ESR) spectra of SO 3 - and SO 2 - radical ions with a linewidth ΔH ≈ 2.7 G and SO 3 - (A 1) and SO 3 - (A 2) centers with superhyperfine splitting due to the interaction with protons in platelike gypsum single crystals under X-ray irradiation have been analyzed at 25°C. Dehydrated regions with a radius >4 Å are revealed in gypsum. The ESR spectra of SO 3 - radical ions and atomic hydrogen with ΔH ≈ 0.3 G are found in the products of isothermal annealing of gypsum kept for 30 min after X-ray irradiation at 25°C. The dependences of the intensities of these spectra on the annealing temperature are studied in the range of 100-450°C. The temperature range of formation of α- and β-phase states of bassanite and γ-anhydrite are determined. The process of residual water redistribution between the channel systems of the α- and β-phase types of γ-CaSO4 in gypsum thermal derivatives is established. © 2014 Pleiades Publishing, Inc

Features of bitumen-containing sandstones of the volga-ural oil and gas province according to electron paramagnetic resonance and gamma spectrometry data

© SGEM2017. All Rights Reserved. On the territory of the Volga-Ural oil and gas province in the Permian sediments are concentrated significant resources of bitumen-containing rocks, which are of interest as a source of unconventional oil. In this connection, it is very important to clarify the conditions for the formation of bituminous strata and their productive areas. High efficiency in the study of oil-bearing rocks has radio-spectroscopic methods for determining the structure of the oil deposit and the nature of its oil and bitumen saturation, not only in carbonate rocks, but also in sandy-clayey varieties. In this paper are considered the results of analysis of reservoir rocks by electron-paramagnetic resonance (EPR) in combination with gamma spectrometry. The EPR method is used to study diamagnetic crystals where the paramagnetic centers are the impurity ions of Fe3+ and Mn2+ in calcite, dolomite, electron-hole centers in them, radiative E'-center in quartz, free radicals of organic matter of coal and oil series. These paramagnetic centers reflect the conditions and environment for the formation of minerals, the degree of degradation of the syngenetic material of rocks, reflecting different stages of post-sedimentation changes of rocks. Bitumen deposits belong to the Ufimian (Kungurian-ICS) stage (sheshminskiy horizon) of Permian period, which are represented by cross-bedded fine-to-medium-grained, polymictic sands and sandstones. According to the mineral composition, they belong to the Greywack group. In the clastic material of sandstones, there are grains of quartz, feldspar, mica, as well as particles of volcanic rocks, which was introduced from the Ural Mountains that were collapsing in the Permian time. Cement in sandstones is clayey-carbonate by composition, sometimes carbonate; by type - porous, pelitomorphic, basal. The mutual arrangement of grains of detrital minerals determines the poorly expressed banding of rocks. The intergranular space of the detrital component is largely filled with cement matter. The EPR method makes it possible to determine the paramagnetic centers reflecting the stages of diagenetic transformation of rocks and the degradation of organic matter. According to the EPR data, it was found that in the studied samples there are 2 types of organic matter, of oil and coal series. The oil substance has a migratory nature and, most likely, is associated with the oil rising from deeper horizons (Carboniferous deposits). The organic matter of the coal series has a syngenetic origin and is represented by the remains of vegetation (algae) and is deposited along with the primary sediments. One of the most important parameters is the radiation E'-center, which is observed in trigonal quartz. The E'-center creates if the trigonal quartz is irradiated by radioactive elements. The content of natural radionuclides of the 238 U ( 226 Ra) series, as well as 232 Th and 40 K was estimated in the samples under study by gamma spectrometry. The EPR spectra of the ion-radicals E' of quartz in the profiles of the studied wells are highly correlated with 238 U ( 226 Ra) and 40 K. Herewith, their content prevails in the upper and lower parts of productive horizons. This suggests that the source of irradiation is in the rock itself. Such a source can be potassium feldspar, as well as insignificant concentrations of uranium. Uranium can be supplied as part of groundwater of the red-colored Ufimian deposits, which have the properties of alkaline solutions, and precipitate on contact with bitumen-bearing rocks

Low-temperature dehydration of gypsum single crystals

On the basis of the analysis of the electron spin resonance spectrum of the SO 3 - radical ion, it is established that the transformation of gypsum (CaSO4 · 2H2O) into bassanite (CaSO4 · 0.5H2O) with partial removal of water molecules occurs through the formation of an anhydrous metastable phase. This phenomenon, reflecting the processes of recrystallization of materials of this class, serves as the scientific basis for the production of binders from sulfate mineral associations. © 2008 Pleiades Publishing, Ltd

Transformation of organic matter of rocks from domanik deposits in hydrothermal and pyrolytic processes

© SGEM 2017. All Rights Reserved. The objects of the study were samples of Domanik rock from Upper Devonian siliceous-carbonate and carbonate sediments of the Romashkinо oil field, which occurs in the central part of the South Tatarian arch in Tatarstan. The composition of organic matter and mineral rock components and bitumoids extracted from them was studied by thermal analysis, X-ray diffraction analysis, SARA analysis and gas chromatography. Significant differences in the mineralogical composition and content of organic matter are found in samples after their hydrothermal treatment at a temperature of 350°C in the steam medium at the carbon dioxide. Based on the example of these rock samples, pyrolytic experiments were conducted to simulate the processes of conversion of kerogen to free micronized oil at temperatures of 350 and 600°C in a hydrogen medium in a flow system. The content of Mn 2+ , SO 3 - , SO 2 - ions in the rock, as well as ions of vanadyl (VO 2+ ) and free radicals (R*) in the pyrolysis products were evaluated using Xband electron paramagnetic resonance (EPR) spectroscopy at frequency of 9.43 GHz. The most significant changes associated with an increase in the concentration of free radicals were observed at 350°C. A new free organic radical C350 was registered In the sample of siliceous-carbonate sediments and a free organic radical C 600 – in carbonate sample, which indicate that the studied rocks did not fully realize their potential in natural hydrocarbon generation processes

Derivation of the conditions for equivalent positions in crystals: The dissymmetrization of barite by electron spin resonance spectra

The conditions for equivalent positions on the (hkl) face of growing crystal are derived using sym- metry elements of the space group. It is shown by the example of the sp. gr.D2h 16 that the conditions of equiv- alent position formation coincide with conditions of the reflection of diffracted beams by crystal. It is estab- lished that electron spin resonance (ESR) centers in barite, SO4 -(I) and SO4 -(II), with only two conjugate spectra with equal intensity out of four, and SO4 -(III), with a different intensity of conjugate spectra KaM = 2, are localized into the growth pyramid of the (001) face with a [010] step. SO2 -,SO3 -, and (IV) centers, having an identical intensity of the conjugate ESR spectra with KαM = 2, are localized into the growth pyramid of the (210) face with a growth step [001]. © Pleiades Publishing, Inc., 2012