Вестник Пермского университета. Геология @geology-vestnik-psu
Статьи журнала - Вестник Пермского университета. Геология
Все статьи: 643
18-е научные чтения памяти П. Н. Чирвинского
Статья обзорная
В Пермском государственном национальном исследовательском университете проведены очередные ежегодные научные чтения памяти П.Н. Чирвинского с международным участием. Рассмотрены проблемы минералогии, петрологии, геохимии и других геологических наук, опубликованы материалы конференции.
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19-е научные чтения памяти П. Н. Чирвинского
Статья научная
В Пермском государственном национальном исследовательском университете проведены ежегодные научные чтения памяти П.Н. Чирвинского с международным участием. Рассмотрены проблемы минералогии, петрологии, литологии, металлогении и геохимии, опубликованы материалы конференции
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21-е научные чтения памяти П.Н. Чирвинского
Краткое сообщение
В Пермском государственном национальном исследовательском университете проведены ежегодные научные чтения памяти П.Н. Чирвинского с международным участием. Рассмотрены проблемы минералогии, петрологии, литологии, металлогении и геохимии, опубликованы материалы конференции.
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37-я Всероссийская научно-практическая конференция "Геология и полезные ископаемые Западного Урала"
Статья
23-24 мая 2017 г. на базе Пермского государственного национального исследовательского университета состоялась 37-я Всероссийская научно-практическая конференция с международным участием «Геология и полезные ископаемые Западного Урала». В статье описаны основные моменты работы конференции, освещены затрагиваемые проблемы и тематика докладов, а также подведены итоги.
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90 лет со дня рождения палеонтолога П. К. Чудинова (1922-2002)
Статья научная
Петр Константинович Чудинов - выдающийся ученый, главным вкладом которого в российскую палеонтологию было открытие, раскопки и изучение очёрской фауны ископаемых позвоночных. Он описал несколько новых родов и семейств зверообразных рептилий из этой фауны. Очёрская фауна представляет собой особый, не известный нигде в мире этап развития пермских наземных позвоночных.
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Статья научная
Four Electrical Resistivity Tomography (ERT) profiles and borehole data were acquired on the front face of the earth-filled dam and on the flanks, constituting Lake #1, in order to locate the seepage zone, the flow path, and to determine possible reasons of the seepage. The seepage, observed a year after the construction in the southwestern part of the lake, was severe and could cause further softening, slippage and erosion of soil, developing of pipe holes, increasing the water outflow and risk to the embankment integrity. The owner agreed to drain the lake in order to acquire geophysical and borehole data. Based on the analyses of the acquired ERT and borehole data, four solution-widened fracture zones trending from southwest to northeast were identified. It was concluded that the seepage pathway beneath the dam was through a solution-widened fracture zone, the top of which constituted the original stream channel.
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Статья научная
Subsalt seismic imaging is particularly difficult due to the complex overburdens, caused by the movement of salt that usually results in steeply dipping structures, which along with strong lateral velocity contrast at the sediments-salt interface distort the structural position and the stratigraphic resolution of the subsalt reservoirs. Despite it was proven that two-way wave equation migration provides the best results illuminating these reservoirs, it has huge computational cost, especially in three dimensions. One-way wave equation (OWWE) migration techniques are good alternative in this case as providing the acceptable quality of seismic sections with an appropriate computational cost. To know the advantages and limitations of the OWWE techniques in subsalt imaging, three classical OWWE algorithms were evaluated for depth migration of prestack data (PSDM): phase-shift-plus-interpolation (PSPI), split-step Fourier (SSF), and Fourier finite-difference (FFD). These algorithms were tested with three different fully elastic synthetic models which simulates the structural complexity showed in subsalt plays. It was concluded that FFD gives very accurate results when the lateral velocity variation was strong with acceptable computational cost. The PSPI provided the best quality results but required about twice the computer time needed for FFD, and SSF was the fastest but clearly the least accurate.
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Статья научная
This study introduces a novel supervised workflow for predicting lithofacies in complex, heterogeneous tight sandstone reservoirs with intercalated facies. Using a two-information criteria clustering method, six distinct facies are identified, providing an unbiased, data-driven alternative to manual approaches. Among classification models, Gaussian Process Classification (GPC) outperforms others, including Support Vector Machine (SVM) and Artificial Neural Network (ANN), with Random Forest (RF) performing less effectively. GPC accurately predicts lithofacies in testing data and is assessed for similarity accuracy. Predicted lithofacies are integrated into acoustic impedance versus velocity ratio cross plots, resulting in 2D probability density functions. These, combined with depth data, feed a neural network to forecast synthetic gamma-ray log responses. Results show strong agreement between measured and predicted gamma-ray logs (R2 = 0.978) and nearly identical log trends. Additionally, the predicted lithofacies are classified using inverted impedance and velocity ratio volumes, yielding a facies prediction volume that aligns well with well site lithofacies classification, even without core data.
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Achievements in nanomineralogy
Статья научная
The results of investigations in the field of nanomineralogy obtained by the Nanomineralogy Sector staff during 5 years (2012-2016) are presented. These include results of researches with the application of high-resolution electron microscopy with mi-croprobe analysis and experimental data. The study objects were unusual grains of placer gold of the Urals, Siberia (Russia), Kazakhstan, and the Yukon Territory (Canada). It is concluded that there are nanogold aggregation processes which lead to the formation of globular and "new" gold. These processes may be used in modern technologies of gold extraction.
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Статья научная
The article considers a chemical variation of accessory and ore-forming chrome spinels from the Kraka ultramafic massif at the different scales, from the deposit to the thin section. A correlation analysis of compositional and structural features of ultramafic rocks and ores was performed. The ultramafic rocks and chromitites in the studied massif show the distinct deformation structures and tectonite olivine fabric. A typical chemical gap (i.e. Cr#=Cr/(Cr+Al)) was observed between peridotite, on the one hand, and dunite and chromitite, on the other hand, on the scale of deposits and ore-bearing zones. The location and size of this gap depend on the type of deposit. The gap becomes wider from the disseminated tabular bodies to the typical podiform ones. It has been found that in the thin initial dunite veinlets in peridotite the chrome spinels chemistry changes gradually and there is no Cr# gap between peridotite and dunite. The dunite venlets show a strong olivine fabric, which is an evidence of their high-temperature plastic flow origin. It has been revealed that new chrome spinel grains previously formed as rods or needles and then coarsened. We explained this observation as the result of impurity segregation, coalescence and spheroidization induced by the plastic deformation of olivine. It is inferred that a solid crystal flow is the main requirement for the dunite and chromitite body formation in the Kraka ophiolite massif. In the solid stream, the mineral phase separation takes place. For example, olivine and orthopyroxene grains of parental peridotite separate from one another, and weaker (more mobile) olivine grains form dunite bodies in which chromitite appears as a result of impurity segregation.
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Статья научная
The development of mineral deposits has strong transformative effect on the geological environment. At the same time, all the components of geotechnical conditions (relief, structure of rock massifs, hydrogeological and geocryological conditions etc.), formed over a long geological time, are actively changing. Geological processes are activated and new mining-geological processes are formed. New strata are formed on the Earth's surface along with the technogenic formations and technogenic deposits. Today, the scale of technogenesis in mining is comparable to the results of geological activities that have been going on for many millions of years. The reaction of the geological environment is immediate and is expressed in the development of large-scale engineering and geological processes, which often do not allow the further development of mineral resources and threaten the human life. Therefore, even at the early stages of prospecting and/or exploration, it is necessary to understand the dynamics of changes in surrounding medium in order to develop methods for proper managing of the ore extraction. By the example of a number of objects, all the stages of study of engineering-geological conditions are considered, the dynamics of their change, which led to the formation of engineering-geological processes affecting the further development of mineral resource, is estimated.
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Engineering and geological zoning of the residual soil of the Malmyzhsky deposit (Svoboda site)
Статья научная
Interest to the study of residual soil arose at a time when geological engineers faced the problem of developing the open pits in the eluvial soils. A significant number of Russian and foreign scientists considered the formation of weathering crusts from different points of view. They established the geochemical zoning, and engineering-geological zoning of the weathering crusts. However, no comprehensive and detailed engineering-geological zo-nation of the crusts of weathering, especially when studying mineral deposits, was given due to the insufficient attention paid to it until today. Therefore, it is important to correctly determine the type and profile of the residual soil in order to establish the possibility to control the engineering and geological conditions when exposing the rock mass during excavation work for further forecasting the slope stability of the projected open pit mining structures.
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Engineering geology of Kansas city underground spaces
Статья научная
The Bethany Falls and Argentine limestone members provide a high grade limestone aggregates for construction but also excellent areas for underground manufacturing and storage space. Under proper mining this formation will yield large areas that will constant air temperature of 52 degrees F (18 o C) and low humidity levels. Overlying shale or claystone beds provides a nearly impermeable groundwater barrier to mined out areas below. Roof support via rock bolting is almost never needed if sufficient support pillars are created during the mining operation. With minimal finishing of the mine such as a concrete floor and painting the mine space can then be rented with rental receipts soon exceeding the cost of excavation and sale of the rock.
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Статья обзорная
24-26 ноября на базе Пермского государственного национального исследовательского университета состоялась I Международная научная конференция «Новые направления нефтегазовой геологии и геохимии. Развитие геологоразведочных работ». Описана работа конференции, освещены затрагиваемые проблемы и тематика докладов, а также подведены итоги.
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Статья научная
The most memorable moments of internship trip to South-East Siberia are presented in these short memories of students from Department of Earth Sciences of the University of Oxford. The students from Perm, Oxford, and La Salle universities enrolled in field geology class spent 2 weeks in Khakassia and Tyva Republics studying geology of visited deposits and gathering gold and different rock samples.
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Nurali ophiolite massif (the Southern Urals): geological, structural, and mineralogical features
Статья научная
An overview of a geological structure of Nurali massif is presented. Compositional data of ultramafic rocks from mantle section and transitional mantle-crust assemblages, and chemistry of accessory and ore-forming Cr spinels are examined. We showed that ultramafic rocks from mantle section (spinel a spinel-plagioclase peridotites, harzburgites, dunites) are the tectonites. They have a strong predominantly optical orientation of rock-forming olivine due to a plastic flow of rocks. We presented different points of view on the mantle-crust assemblage origin, which composed by wehrlites, clinopyroxenites, vebsterites, dunites and melanocratic gneiss-like gabbro, and described two PGE-occurrences in the chromitites of this ophiolite section unit. This paper is based on a guidebook of an International field trip to Nurali massif as a part of conference “Magmatism of the Earth and related deposits of strategic metals” held in 2017 August.
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Статья научная
This article presents the results of a study of gold samples obtained by students during a practical field trip in the summer of 2014. Placer gold samples retrieved from four rivers in southeast Siberia (Khakassia and Tyva territories) by panning and sluicing were described and analyzed compositionally by Scanning Electron Microscopy. There is evidence from grain flattening and morphology for significant variations in gold transport distance, both within and between sample locations. The composition and texture of gold is compared to similar studies in the Yukon, and it is inferred that most of the placer gold in the region originated from orogenic lode sources. This orogenic gold is of Devonian to Carboniferous age. There is also evidence for a contribution from igneous intrusion-related bedrock gold, which is supported by the presence of granite, granodiorite and sienite intrusions of Devonian age. There is scope for further study, since relatively few grains were analyzed here. In addition, if compositional data of the prospective primary gold deposits can be obtained, there would be potential for more precise determination of provenance.
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Статья научная
This paper presents the results of the seismic refraction modeling using finite differences method (FDM), implemented in the program from the open source package Seismic Unix (SUFDMOD2), and its comparison with the modeling by time-term method (TTM) from the SEISIMAGER© software. The applied velocity model corresponds to the typical measurements situation in a seismic refraction survey. The depth of refraction interfaces varies approximately from 2 to 6 meters, thus allowing examining the propagation of head waves with the variable dip angles. The synthetic seis-mograms allow us identifying the first arrivals of head waves, which are subsequently the travel-time curves. The analysis of results obtained with FDM and TTM algorithms shows a high correlation with the refraction arrival times, but a low correlation with the arrival times of the direct wave. Finally, the obtained results allow concluding that the seismic modeling of the propagation of head waves using the method of finite differences makes it possible to accurately determine the first arrival time within the complex geological conditions and the velocity dispersion between the layers. The goal of this work is to show how these findings can be applied to seismic modeling by the method of finite differences for calculation of the first arrival time and clarify the results of measurements conducted in real conditions.
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