sedimentation processes
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2022 ◽  
Vol 12 (2) ◽  
pp. 580
Author(s):  
Boris A. Dzeboev ◽  
Anastasia A. Odintsova ◽  
Alena I. Rybkina ◽  
Boris V. Dzeranov

The introduction of modern methods for the mathematical processing of geological data is one of the promising areas of study and development in the field of geosciences. For example, today mathematical geology makes it possible to reliably identify astronomical cycles by measuring the scalar magnetic parameters of rocks (magnetic susceptibility). The main aim of this study is to develop a mathematical tool for identifying stable oscillation cycles (periods) in the dataset of the magnetic susceptibility of rocks in a geological section. The author’s method (algorithm) is based on the concept of discrete mathematical analysis—an innovative mathematical approach to the analysis of discrete geological and geophysical data. Its reliability is also demonstrated, by comparison with the results obtained by classical methods: Fourier analysis, Lomb periodogram, and REDFIT. The proposed algorithm was applied by the authors to analyze the material of field geological studies of the Zhelezny Rog section (Taman Peninsula). As a result, stable cycles were determined for the Pontian and Lower Maeotian sedimentary strata of the Black Sea Basin (Paratethys).


2021 ◽  
Vol 937 (4) ◽  
pp. 042096
Author(s):  
N I Meshcheriakov ◽  
G V Ilyin ◽  
E G Zhuvikina ◽  
G V Tarasov

Abstract The paper reviews the study results of sedimentation and formation of geochemical characteristics of glacial Lake Bretjørna sediment – as the example of postglacial process in inner areas of Arctic archipelagos. Field research and sampling were carried out in the winter of 2018. The properties of sediments along the profile of the lake were analyzed. The income and accumulation of heavy metals in sediment were assessed. The lithofacies characteristics of the sediments and their spatial distribution were determined. In the paper the main geochemical characteristics of the lake bottom sediments (granulometric composition, organic matter content, as well as the accumulation of Pb, Zn, Cu, Ni, Fe, Mn, Hg) are considered. The correlation between the lithological composition of sediments and their micro-component content are shown. Correlation between elements and terrigenous sediments income from Northern Scandinavia and the Kola Peninsula accumulated by the glacier and snow cover of the catchment is obtained. Three associations of trace elements in the group of studied elements are distinguished.


2021 ◽  
pp. 127397
Author(s):  
Jan Sedláček ◽  
Ondřej Bábek ◽  
Tomáš Matys Grygar ◽  
Zuzana Lenďáková ◽  
Jan Pacina ◽  
...  

2021 ◽  
Vol 937 (4) ◽  
pp. 042081
Author(s):  
N I Meshcheryakov ◽  
I S Usyagina ◽  
V V Sharin ◽  
V A Dauvalter ◽  
G N Dukhno

Abstract This paper presents results of a study of sedimentation in Colesbukta (Isfjorden, Spitsbergen), a typical example of sedimentation in a shallow bay of the Svalbard Archipelago. We have examined sediment samples from several cores collected in Colesbukta in May 2018. To meet the goals of this study, geomorphological features of the Colesbukta catchment area have been identified and described. The lithological characteristics of bottom sediments from the study area have been described and their spatial and temporal changes analyzed. The chronology of sedimentation has been reconstructed by 210Pb and 137Cs. We have calculated sedimentation rates in Colesbukta and their temporal dynamics over the several latest decades. According to our estimations, the sedimentation rate has increased by 2–4 times compared to the middle of the 20th century and ranges from 0.2 to 0.46 mm/year depending on the individual conditions of sedimentation in each part of the bay. Climatic fluctuations are shown to have a direct impact on sedimentation processes in Colesbukta. We have revealed that on the periphery of the studied area the rate of sedimentation better depends on the temperature regime while in its central part it is rather a result of the amount of atmospheric precipitation.


Author(s):  
D.G. Kushnir

For the first time, on the basis of the data set of the Taimyr geophysical site, the processes that cause vertical oscillatory movements of large blocks of the continental crust and largely determine its deep structure are confidently recorded. In this regard, the conceptual apparatus of plate tectonics is being expanded due to terms that were not originally used for it, previously used within the framework of geosyncline theory. Modern geodynamics combines concepts opposed in the past, thereby forming a conceptually new geosyncline plate tectonics. Under the new paradigm, the oil and gas prospects of an area are determined not so much by its confinement to a geostructure of any age, as by the current stage of the geosyncline cycle, characterized by subsidence, active sedimentation processes and formation of a sedimentary basin or, conversely, orogenesis and dominant erosion of sediments. Thus, one or another scenario will cause a different inflow of hydrocarbons from the generation area, which means that regional tectonic movements largely predetermine the realization of the hydrocarbon potential, making them one of the most important criteria for its assessment.


2021 ◽  
Author(s):  
◽  
Cassandra Anh Trinh-Le

<p>The hyper-arid, cryotic, wind-dominated conditions in the high-elevation McMurdo Dry Valleys of Antarctica are among Earth’s most extreme environments and represent the closest terrestrial analog to the surface of Mars. These unique conditions result in complex surface processes that occur in the overall absence of liquid water. However, since water is typically believed to be required for these processes to occur, the mechanisms responsible for how these processes can persist in this environment are poorly understood. Previous studies that focused on individual processes of sedimentation in the Dry Valleys leave questions regarding the role of water in dry cryotic sedimentation as well as the rates at which these processes occur. This thesis addresses these questions by combining Optically Stimulated Luminescence (OSL) dating, meteoric Beryllium-10 (10Be) measurements, soil geochemistry analysis, and petrographic microscopy analysis on ice-cemented permafrost cores taken from University Valley, one of the high-elevation Dry Valleys, where the availability and effects of liquid water are minimal. These analyses were used to explore four main sedimentation processes that occur in the Dry Valleys: chemical weathering, fine particle translocation, eolian transport, and physical weathering. Analyzed together, findings from these analyses comprehensively describe the complex processes involved in dry cryotic sedimentation and determine the roles of different phases of water in this environment.   Sediments in University Valley have accumulated at a rate of approximately 2.1 mm/ka for the last 200 ka, as dated by OSL, from erosion of the valley walls and deposition of windblown dust. Sediment accumulation is influenced by topography of the valley floor, depth of the ice table, aspect of the valley walls, wind direction, and mechanical breakdown of rocks due to solar heating. While persistent winds constantly remobilize fine particles and dust in the upper few cm of the dry ground, sediment grains that are sand-sized or larger do not undergo significant remobilization, and sediments in the ice-cemented ground are unaffected by remobilization and translocation processes. Rare clay bridges seen in thin section show that small, infrequent, transient surface wetting events have occurred over the last 200 ka. High anion concentrations associated with high surface meteoric 10Be measurements and clay bridges indicate that the source of these wetting events is the melting of wind-blown snow from coastal regions. Patterns in meteoric Be measurements show that these small transient wetting events are not sufficient to translocate fine particles through the soil profile, which suggests that the role of liquid water as a transporting agent is negligible in this environment. Chemical weathering in University Valley appears to be controlled by two main components: dolerite content of the sediments, and exposure to the atmosphere at the ground surface where condensation of water vapor onto grain surfaces readily leaches ions from dolerite grains under the oxidizing conditions of the Dry Valleys. In the absence of liquid water, chemical processes that occur in this environment rely on water vapor.   Together, these results indicate that surfaces in University Valley are remarkably young and sedimentologically active. Because University Valley represents one of the closest terrestrial analogs to the surface of Mars, findings from this thesis may be applicable to understanding the timescales and the processes that control anhydrous sedimentation on the surface of Mars.</p>


2021 ◽  
Author(s):  
◽  
Cassandra Anh Trinh-Le

<p>The hyper-arid, cryotic, wind-dominated conditions in the high-elevation McMurdo Dry Valleys of Antarctica are among Earth’s most extreme environments and represent the closest terrestrial analog to the surface of Mars. These unique conditions result in complex surface processes that occur in the overall absence of liquid water. However, since water is typically believed to be required for these processes to occur, the mechanisms responsible for how these processes can persist in this environment are poorly understood. Previous studies that focused on individual processes of sedimentation in the Dry Valleys leave questions regarding the role of water in dry cryotic sedimentation as well as the rates at which these processes occur. This thesis addresses these questions by combining Optically Stimulated Luminescence (OSL) dating, meteoric Beryllium-10 (10Be) measurements, soil geochemistry analysis, and petrographic microscopy analysis on ice-cemented permafrost cores taken from University Valley, one of the high-elevation Dry Valleys, where the availability and effects of liquid water are minimal. These analyses were used to explore four main sedimentation processes that occur in the Dry Valleys: chemical weathering, fine particle translocation, eolian transport, and physical weathering. Analyzed together, findings from these analyses comprehensively describe the complex processes involved in dry cryotic sedimentation and determine the roles of different phases of water in this environment.   Sediments in University Valley have accumulated at a rate of approximately 2.1 mm/ka for the last 200 ka, as dated by OSL, from erosion of the valley walls and deposition of windblown dust. Sediment accumulation is influenced by topography of the valley floor, depth of the ice table, aspect of the valley walls, wind direction, and mechanical breakdown of rocks due to solar heating. While persistent winds constantly remobilize fine particles and dust in the upper few cm of the dry ground, sediment grains that are sand-sized or larger do not undergo significant remobilization, and sediments in the ice-cemented ground are unaffected by remobilization and translocation processes. Rare clay bridges seen in thin section show that small, infrequent, transient surface wetting events have occurred over the last 200 ka. High anion concentrations associated with high surface meteoric 10Be measurements and clay bridges indicate that the source of these wetting events is the melting of wind-blown snow from coastal regions. Patterns in meteoric Be measurements show that these small transient wetting events are not sufficient to translocate fine particles through the soil profile, which suggests that the role of liquid water as a transporting agent is negligible in this environment. Chemical weathering in University Valley appears to be controlled by two main components: dolerite content of the sediments, and exposure to the atmosphere at the ground surface where condensation of water vapor onto grain surfaces readily leaches ions from dolerite grains under the oxidizing conditions of the Dry Valleys. In the absence of liquid water, chemical processes that occur in this environment rely on water vapor.   Together, these results indicate that surfaces in University Valley are remarkably young and sedimentologically active. Because University Valley represents one of the closest terrestrial analogs to the surface of Mars, findings from this thesis may be applicable to understanding the timescales and the processes that control anhydrous sedimentation on the surface of Mars.</p>


2021 ◽  
Vol 910 (1) ◽  
pp. 012075
Author(s):  
Aisha A. Juma ◽  
Amin S. Badawy ◽  
Sanad B. Mohammed

Abstract This study aim is to purify β-galactosidase from a local isolate of yogurt in Salah al-Din Governorate to overcome the phenomenon of lactose in decomposition. The bacteria were grown on MRS medium supplemented with 1%CaCo3. Twenty isolates of lactic acid bacteria were obtained and conducting culture tests and microscopic examinations were on these isolates. In order to classify them to the level of species, it was found that there were four types, namely: Lactobacilluse acidophilus,LactobacilluseCasei,Lactobacilluse delubrici subsp.bulgaricus,Streptococcus thermophilus, The cultivation and activation steps of the different isolates were carried out forobtaining the most productive and active isolate, which is Lactobacilluse acidophiluse. Beta-galactosidase activation processes were carried out for the enzyme and cell breakdown by lysozyme. Purification and sedimentation processes were carried out using ammonium sulfate and membrane sorting, followed by gel filtration using Lactobacillus G-150. The best extraction rate (L.acidophiluse 70%) was achieved by enzyme precipitation (4,375) units/mol, and the activity increased in the membrane sorting step to (5,900) units/mol, and in gel filtration we obtained activity of the enzyme (15.591) units/mol.


Author(s):  
Xin Wang ◽  
Qiyan Feng ◽  
Qingjun Meng ◽  
Fei Liu ◽  
Qihang Cao ◽  
...  

AbstractUranium is an environmentally hazardous element, and is commonly present at trace levels (2.4 μg/g for world coals) in coal deposits. However, selected coal deposits could be highly enriched in uranium. In this study, 15 coal samples were collected from Eastern Yunnan coal deposits, China, aiming to characterize the distribution and the occurrence of uranium in those coals. In studied samples, uranium content varied from 0.36 to 8.28 μg/g, with an average value of 3.76 μg/g. Generally, uranium content in coals from northern coal mines (3.02 ± 2.44 μg/g, n = 5) were lower than it in southern coal mines (4.13 ± 2.30 μg/g, n = 10). Uranium in coal samples showed no obvious correlation with total sulfur, whereas was positively correlated with ash yield. The results of sequential chemical extraction procedure confirm that organic-bound is the dominant occurrence of uranium. The slight enrichment of uranium in studied coals was probably attributed to sedimentation processes, hydrological conditions and tectonic structure of the coal deposits.


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