Academic literature on the topic 'Quartz grain characteristics'
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Journal articles on the topic "Quartz grain characteristics"
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Wu, Chao, Peng Qian, Xiangmin Zheng, Limin Zhou, Hui Wang, and Hongyang Xu. "Quartz grain characteristics of the late Pleistocene hard clay in the Yangtze River delta and implications for sedimentary environment and provenance." Quaternary Research 97 (June 9, 2020): 199–215. http://dx.doi.org/10.1017/qua.2020.31.
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AbstractThe sedimentologic fingerprinting in detrital deposit is vital to reconstruct sedimentary environments and discriminate sources. In this study, grain size and microtextural characteristics of quartz from the late Pleistocene hard clay in the Yangtze River delta (YRD) were analyzed by using a laser particle size analyzer and a scanning electron microscope. Subaqueous quartz from the Yangtze River and Yellow River sediments and eolian quartz from the Chinese Loess Plateau loess were also analyzed by scanning electron microscopy to obtain the microtextural characteristics. Quartz grains of the hard clay were characterized by poor sorting, fine skew, bimodal grain-size distributions, and numerous eolian microtextures. The comparison of the quartz grain characteristics of the hard clay with these in eolian loess indicated that the hard clay belonged to an eolian deposition. Moreover, the fine quartz grains of the hard clay were dominated by eolian microtextural characteristics, representing long-distance transportation. The coarse quartz grains of the hard clay exhibited more subaqueous microtextural characteristics, which indicated that the coarse fraction of the hard clay was derived from the proximal source regions in the YRD. The determination of buried eolian deposition with multiple sources in the YRD implies a southward westerly jet stream, strengthened eolian dust transportation, and extensive aridification in the YRD due to the increased Northern Hemisphere ice sheets in Marine Oxygen Isotope Stage 2.
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Hu, Yue, Bo Li, and Zenobia Jacobs. "Single-Grain Quartz OSL Characteristics: Testing for Correlations within and between Sites in Asia, Europe and Africa." Methods and Protocols 3, no. 1 (December 26, 2019): 2. http://dx.doi.org/10.3390/mps3010002.
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We studied the characteristics of the optically stimulated luminescence (OSL) signal of single-grain quartz from three sites in China, Italy, and Libya, including the brightness, decay curve and dose response curve (DRC) shapes, recuperation, and reproducibility. We demonstrate the large variation in OSL behaviors for individual quartz grains of different samples from different regions, and show that recuperation, sensitivity change, and reproducibility are independent of the brightness and decay curve shape of the OSL signals. The single-grain DRCs can be divided into at least eight groups with different characteristic saturation doses (D0), and a standardized growth curve (SGC) can be established for each of the DRC groups. There is no distinctive difference in the shape of OSL decay curves among different DRC groups, but samples from different regions have a difference in the OSL sensitivities and decay shapes for different groups. Many of the quartz grains have low D0 values (30–50 Gy), and more than 99% of the grains have D0 values of <200 Gy. Our results raise caution against the dating of samples with equivalent dose values higher than 100 Gy, if there are many low-D0 and ‘saturated’ grains.
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Kalińska-Nartiša, Edyta, Kristaps Lamsters, Jānis Karušs, Māris Krievāns, Agnis Rečs, and Raimonds Meija. "Quartz grain features in modern glacial and proglacial environments: A microscopic study from the Russell Glacier, southwest Greenland." Polish Polar Research 38, no. 3 (September 1, 2017): 265–89. http://dx.doi.org/10.1515/popore-2017-0018.
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Abstract It is assumed that close to the margins of ice-sheets, glacial, fluvial and aeolian processes overlap, and combined with weathering processes, produce numerous sediments, in which quartz is a common mineral. Quartz grains, if available, may serve as a powerful tool in determining the depositional history, transportation mode and postdepositional processes. However, quartz grain studies in some modern glacial areas are still sparse. In this study, we examine for the first time quartz grains sampled from the modern glacial and proglacial environments of the Russell Glacier, southwest Greenland in binocular microscope and scanning electron microscope, to analyze their shape, character of surface and microtextures. We debate whether the investigated quartz grains reveal glacial characteristics and to what extent they carry a signal of another transportation and sedimentary processes. Although glacial fracturing and abrasion occur in grain suites, most mechanical origin features are not of a high frequency or freshness, potentially suggesting a reduced shear stress in the glacier from its limited thickness and influence of the pressurized water at the ice-bed. In contrast, the signal that originates from the fluvial environment is much stronger derived by numerous aqueous-induced features present on quartz grain surfaces. Aeolian-induced microtextures on grain surfaces increase among the samples the closest to the ice margin, which may be due to enhanced aeolian activity, but are practically absent in sediments taken from the small scale aeolian landforms. In contrast, aeolian grains have been found in the bigger-size (1.0–2.0 mm) investigated fraction. These grains gained the strongest aeolian abrasion, possibly due to changes in transportation mode.
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Poernomo, Herry. "SORPTION AND DISPERSION OF STRONTIUM RADIONUCLIDE IN THE BENTONITE-QUARTZ-CLAY AS BACKFILL MATERIAL CANDIDATE ON RADIOACTIVE WASTE REPOSITORY." Indonesian Journal of Chemistry 10, no. 3 (December 14, 2010): 276–84. http://dx.doi.org/10.22146/ijc.21430.
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The experiment of sorption and dispersion characteristics of strontium in the mixture of bentonite-quartz, clay-quartz, bentonite-clay-quartz as candidate of raw material for backfill material in the radioactive waste repository has been performed. The objective of this research is to know the grain size effect of bentonite, clay, and quartz on the weight percent ratio of bentonite to quartz, clay to quartz, bentonite to clay to-quartz can be gives physical characteristics of best such as bulk density (rb), effective porosity (e), permeability (K), best sorption characteristic such as distribution coefficient (Kd), and best dispersion characteristics such as dispersivity (a) and effective dispersion coefficient (De) of strontium in the backfill material candidate. The experiment was carried out in the column filled by the mixture of bentonite-quartz, clay-quartz, bentonite-clay-quartz with the weight percent ratio of bentonite to quartz, clay to quartz, bentonite to clay to quartz of 100/0, 80/20, 60/40, 40/60, 20/80, 0/100 respectively at saturated condition of water, then flowed 0.1 N Sr(NO3)2 as buffer solution with tracer of 0.05 Ci/cm3 90Sr as strontium radionuclide simulation was leached from immobilized radioactive waste in the radioactive waste repository. The concentration of 90Sr in the effluents represented as Ct were analyzed by Ortec b counter every 30 min, then by using profile concentration of Co and Ct, values of Kd, a and De of 90Sr in the backfill material was determined. The experiment data showed that the best results were -80+120 mesh grain size of bentonite, clay, quartz respectively on the weight percent ratio of bentonite to clay to quartz of 70/10/20 with physical characteristics of rb = 0.658 g/cm3, e = 0.666 cm3/cm3, and K = 1.680x10-2 cm/sec, sorption characteristic of Kd = 46.108 cm3/g, dispersion characteristics of a = 5.443 cm, and De = 1.808x10-03 cm2/sec can be proposed as candidate of raw material of backfill material in the radioactive waste repository.
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Křížová, Lenka, Marek Křížek, and Lenka Lisá. "Applicability of quartz grains surface analysis to the study of the genesis of unlithified sediments." Geografie 116, no. 1 (2011): 59–78. http://dx.doi.org/10.37040/geografie2011116010059.
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This paper deals with genetic types of unlithified sediments and their characteristics with an emphasis on quartz grain surface microrelief. There are various physical-geographic agents in different sedimentary environments which play an important role in the origin of certain marks on the surface of sedimentary grains. As a result, studying the features of quartz grain surfaces enables us to determine the possible origin of sediments and landforms. Reference samples were chosen from geomorphological landforms of known origin: a moraine in the Labský Důl Valley, a debris flow in the Důl Bílého Labe Valley, a flood accumulation and deluvium from the Důl Bílého Labe Valley in the Krkonoše Mountains and eolian sediment from Klárov in Prague. Significant differences in surface micromorphology were found among these samples.
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Shimada, Aiko, Masashi Takada, and Shin Toyoda. "Characteristics of ESR signals and TLCLs of quartz included in various source rocks and sediments in Japan: A clue to sediment provenance." Geochronometria 40, no. 4 (December 1, 2013): 334–40. http://dx.doi.org/10.2478/s13386-013-0111-z.
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AbstractThe variation of electron spin resonance (ESR) signal intensities and thermoluminescence colour images (TLCIs) of quartz was investigated in the present study for various rocks and sediments in Japan, to discuss the possibilities of identifying the sediment provenance. The ESR signal intensity of the E1’ centre in the same grain size in granitic quartz varies from sample to sample, except for that in Quaternary samples of volcanic sediment, which is very low, close to the noise level. It was found that the diagram, ESR intensities of Al versus Ti-Li centre signal intensities, distinguish volcanic from the same grain size in granitic quartz as well as distinguish individual tephra from another. The TLCIs from volcanic quartz and some granitic quartz samples is almost red and that from the rest of granitic and metamudstone quartz is blue as results of TLCIs although the emission intensities are different. Our results suggest that examining the multiple-centre signal intensities of ESR and the TLCIs are effective to identify the source of quartz and to estimate the sediment provenance.
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Ma, Zhao, Lichao Nie, Zhaoyang Deng, Xiaobin Xu, Xin Yin, Junfeng Shen, Kai Wang, and Ningbo Li. "Relationship between Induced Polarization Relaxation Time and Hydraulic Characteristics of Water-Bearing Sand." Applied Sciences 12, no. 11 (June 5, 2022): 5735. http://dx.doi.org/10.3390/app12115735.
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The induced polarization method has become a popular method for evaluating formation permeability characteristics in recent years because of its sensitivity to water and water-bearing porous media. In particular, the induced polarization relaxation time can reflect the macroscopic characteristics of the porous media of rock and soil. Therefore, in order to study the relationship between relaxation time and permeability, eight quartz sand samples of different grain sizes were used to simulate water-bearing sand layers under different geological conditions, and the induced polarization experiment and the Darcy seepage experiment were carried out on the same sand sample. The experimental results show that relaxation time and permeability are closely correlated with the grain size of quartz sand samples. According to the experimental data, the power function equation is a better fit for describing the relationship between permeability and relaxation time. It is worth noting that the equations obtained are only empirical equations for quartz sand samples, and they may not be applicable to all geological conditions.
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Hathon, Lori A., Michael T. Myers, and Abhishek Arya. "Pore Volume Compressibility of Unconsolidated Sand Reservoirs: Insights Gained Using Laboratory-Created Sand Pack Analogs." Petrophysics – The SPWLA Journal of Formation Evaluation and Reservoir Description 62, no. 5 (October 1, 2021): 516–36. http://dx.doi.org/10.30632/pjv62n5-2020a6.
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Pore volume compressibility is a fundamental driver of production for unconsolidated sand reservoirs. Prediction of compressibility is desirable when direct measurements on core are not available. Many characteristics of reservoir sands change simultaneously. For this reason, the controls on compressibility are difficult to isolate and interpret. We present the results of compaction experiments using laboratory-created, unconsolidated sands. In these analog sands, we change one textural or mineralogical parameter at a time to investigate the influence of that parameter on the measured compaction properties. Initially, simple quartz grain packs of varying grain sizes were used. Subsequently, additional parameters were investigated, including grain packing, angularity, sorting, feldspar content, ductile grain content, small volumes of dispersed clay, and initial sample preconditioning at stress. Multiple samples of each type were created and tested. This allowed the testing to be halted at several intermediate stresses and the samples to be examined using 2D and 3D imaging and image analysis techniques. For monomineralic quartz sand packs, grain size is a principal control on compressibility. As mean size increases from 150 to 450 μm, peak compressibility increases from 6 to 24 microsips. The depletion stress at which peak compressibility occurs decreases from 8,000 to 2,500 psi. Increasing grain angularity also increases compressibility but with smaller effect. For 150-μm quartz sands, increasing the angularity resulted in an increase in compressibility from 6 microsips for round quartz to 10 microsips for angular quartz and decreased the depletion stress required to achieve peak compressibility from 8,000 to 7,000 psi. As sorting varies from well to moderately poorly sorted, compressibility decreases, and the curve broadens as a function of depletion stress. Adding small volumes of feldspar (or other minerals that cleave) increases the compressibility more than the change resulting from changes in grain size, illustrating the importance of framework grain composition. Adding similar volumes of ductile grains results in a similar increase in compressibility to that observed for feldspar. However, when the size of the ductile grains is larger than that of the associated quartz (e.g., locally derived rip-up clasts), the increase in compressibility is significantly larger. To validate the experimental work, we compare the results of uniaxial pore volume compressibility tests on laboratory-created sands with measurements made on subsurface samples of similar texture and mineralogy. Both the shape of the compressibility curves as well as the magnitude of the compressibility are successfully reproduced. We conclude that laboratory-created sands can provide reasonable proxies for estimating the compressibility of subsurface reservoirs when intact subsurface samples are not available for measurement (e.g., only percussion sidewall samples are acquired) as long as mineralogy and texture are known.
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Zheng, Xinxin, Ruichen Chen, Jian Chen, Song Chen, and Lulu Shi. "Breakage Characteristics of Quartz Sand Based on Ring Shear Tests: Implications for the Fragmentation Processes of Rock Avalanches." Advances in Civil Engineering 2022 (January 13, 2022): 1–12. http://dx.doi.org/10.1155/2022/7879067.
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To investigate the effects of internal shear fragmentation on dry granular flow, in this study a series of ring shear tests were performed on quartz sand samples under different normal stresses (100 kPa, 200 kPa, and 300 kPa), shear displacements (3 m, 5 m, 10m, 15 m, and 20 m), and shear rates (30 deg min−1, 60 deg min−1, and 90 deg min−1). Next, the grain-size distributions, fractal dimensions, and microcharacteristics of the quartz sand before and after the experiments were compared and analyzed. The study results show that grain breakage under shearing preferentially occurs at the edges of the particles and forms a bimodal distribution in frequency grain-size distribution curves, which is consistent with observations of rock avalanches. The fine particles prevent the coarse particles from breaking, in turn leading to the ultimate grain-size distribution and stable fractal dimension (2.61) of quartz sand at relatively small shear displacements compared with the travel distance of rock avalanches. The results of this study suggest that the fragmentation of rock avalanches during the shear spread stage may be far less significant than previously believed. Therefore, the fragmentation effect is not considered to be a major factor of the hypermobility in the late stage of rock avalanches.
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He, Shao-Heng, Zhi Ding, Hai-Bo Hu, and Min Gao. "Effect of Grain Size on Microscopic Pore Structure and Fractal Characteristics of Carbonate-Based Sand and Silicate-Based Sand." Fractal and Fractional 5, no. 4 (October 4, 2021): 152. http://dx.doi.org/10.3390/fractalfract5040152.
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In this study, a series of nuclear magnetic resonance (NMR) tests was conducted on calcareous sand, quartz sand, and glass bead with a wide range of grain sizes, to understand the effect of grain size on the micro-pore structure and fractal characteristics of the carbonate-based sand and silicate-based sand. The pore size distribution (PSD) of the tested materials were obtained from the NMR T2 spectra, and fractal theory was introduced to describe the fractal properties of PSD. Results demonstrate that grain size has a significant effect on the PSD of carbonate-based sand and silicate-based sand. As grain size increases, the PSD of sands evolves from a binary structure with two peaks to a ternary structure with three peaks. The increase in the grain size can cause a remarkable increase in the maximum pore size. It is also found that the more irregular the particle shape, the better the continuity between the large and medium pores. In addition, grain size has a considerable effect on the fractal dimension of the micro-pore structure. The increase of grain size can lead to a significant increase in the heterogeneity and fractal dimension in PSD for calcareous sand, quartz sand and glass bead.
Dissertations / Theses on the topic "Quartz grain characteristics"
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Weschenfelder, Simone. "Caracterização de kefir tradicional quanto à composição físico-química, sensorialidade e atividade anti-Escherichia-coli." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/16409.
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Kefir é um alimento fermentado resultante da dupla fermentação do leite pelos grãos de kefir, sendo estes grãos uma associação simbiótica de leveduras, bactérias ácido-láticas e bactérias ácido-acéticas. Do kefir pode-se obter o kefir leban e o soro de kefir, ambos resultantes da filtração do kefir em tecido de algodão esterilizado, por 24 horas, a 25ºC ± 2ºC. Este estudo tem por objetivos caracterizar e avaliar o comportamento de diferentes amostras de grãos de kefir tradicional e de derivados (kefir, kefir leban e soro de kefir) quanto às características físico-químicas, sensoriais, intenção de compra e atividade anti-Escherichia coli, quando inoculados em diferentes concentrações, padronizando-se o tipo de leite, o tempo e a temperatura de incubação, a maturação e a filtração. Foram desenvolvidas análises fisicoquímicas, a avaliação sensorial através do teste de aceitabilidade e preferência e a determinação de atividade anti-Escherichia coli. Os resultados demonstraram que a técnica de manipulação e padronização das amostras foi eficaz na obtenção de produtos com características idênticas, visto a reprodutibilidade dos resultados. Também indicam que o volume de leite utilizado na incubação influencia significativamente nas características do produto final. O kefir leban obtido do experimento apresentou consistência cremosa, semelhante ao queijo quark, aroma característico de laticínio fermentado, cor amarela esbranquiçada, sabor ácido e boa espalhabilidade. Manteve os teores de cálcio contidos no leite após o processamento, concentrou as proteínas e gorduras, além de não conter lactose. Apresentou boa aceitabilidade e 58% de intenção de compra, quando utilizado na elaboração de formulações alimentares tipo antepasto. O kefir e o soro de kefir apresentaram Intensidade de Atividade de Inibição Bacteriana/bacteriostasia e Intensidade de Atividade de Inativação Bacteriana/ bactericidia máximas frente ao inóculo bacteriano Escherichia coli (ATCC 11229), testado em concentrações <=108 UFC/mL.Kefir is a fermented food resulting from the double fermentation of milk by kefir grains, these grains are a symbiotic association of yeasts, acid-lactic and acetic-acid bacteria. From kefir can be obtained kefir leban and kefir whey, both from the filtration of kefir in sterile cotton cloth, during 24 hours at 25°C ± 2ºC. This study aims to characterize and evaluate the behavior of different samples of traditional kefir grains and products derived (kefir, kefir leban and kefir whey) on the physicochemical composition, sensorial characteristic, intent to buy and anti-Escherichia coli activity, when inoculated in different concentrations, standardized the type of milk, the time and temperature of incubation, the maturation and filtration processes. Were developed physical and chemical analysis, the sensory evaluation using the tests of acceptability and preference and determination of anti-Escherichia coli activity. The results showed that the technique of handling and standardizing of the samples was effective in providing products with similar characteristics as the reproductibility of results. It is also indicate that the volume of milk used in the incubation influence significantly the characteristics of the final product. The kefir leban obtained in the experiment showed creamy consistency, similar to quark cheese, characteristic aroma of fermented dairy, whitish yellow color, acid flavor and good spread. He maintained the calcium contained in milk after processing,he concentrated protein, and don't contain any lactose. The product showed good acceptability and 58% of purchase intention, when used in the preparation of food formulations such hors d'oeuvre. The kefir and the kefir whey showed maximal intensity of bacterial inhibition activity/bacteriostasys, and intensity of bacterial inactivation activity/bactericidie in front of inoculum of Escherichia coli (ATCC 11229), tested at concentrations <=108CFU/mL.
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Foster, J. "Development of a Terra Rossa soil profile on marbles of the Cambrian Normanville Group at Delamere, South Australia." Thesis, 2003. http://hdl.handle.net/2440/123594.
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This item is only available electronically.The genesis of Terra Rossa soils is still a matter of controversy. The two leading theories are: (1) that the soil is derived from the insoluble residue of the underlying limestone; or, (2) that contributions from some outside source account for large portions of the soil. Through morphological, analytical and mineralogical studies of a Terra Rossa soil profile at Delamere, South Australia, the insoluble residue of the underlying dolomite and a texture contrast profile from upslope, the major contributors to the soil’s development were determined. Also, field emission scanning electron microscopy (FESEM) of the coarse sand fraction was employed to determine the origin of coarse quartz grains in the soils. The Terra Rossa was discovered to be receiving considerable contributions from upslope via creep and/or colluvial movement, a feature that was most apparent in the upper horizons of the profile. The deeper horizons, however, appear to be largely derived from the insoluble residue of the dolomite, indicated by the mineralogy, particle size distribution, micromorphology and quartz grain morphology.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, YEAR
Book chapters on the topic "Quartz grain characteristics"
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Wang, Zizheng, Xin-Sheng Jiang, Bang-Guo Zhou, and Sheng-Lin Lu. "Sedimentary Characteristics of the Member 1 of the Middle Devonian Suotoushan Formation and Its Ore-Bearing Potential in Northeastern Yunnan." In Mineralogy. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.103826.
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Super-large quartz sandstone deposit has been discovered in Northeastern Yunnan and the major ore-bearing bed is occurred in the Member 1 of the Middle Devonian Suotoushan Formation. Systematic study on the sedimentary characteristics of the Suotoushan Formation in Yiliang region, northeastern Yunnan Province has been conducted, Profile surveying, drilling and trenching show that, microscopic identification, the thickness of the Suotoushan Formation is 62.8 m ∼ 222.7 m and principally composed of gray-white thick-bedded medium-grained quartz sandstone with well developed parallel bedding, swash bedding, oscillation cross-bedding and wave ripple, showing remarkable wave action features. Thin section observation shows that quartz sandstone in the Member 1 of the Suotoushan Formation is grain supported, siliceous cemented, concave-convex and line contact and the pressure solution and secondary overgrowth of quartz sand grains are obvious. Grain size analysis shows that the grain size is concentrated between 1.5Φ and 3.5Φ with saltation population up to 99% which is composed by tow sub populations and lacking of traction and suspension populations, showing a typical foreshore grain size distribution. Chemical analysis shows SiO2 chemical purity of the quartz sandstone is 99.05 ∼ 99.39 with weighted average 98.99 (N = 11) which has exceeded the industry standard for first-grade raw material of plate glass. Based our studies above, it can be concluded that the quartz sandstone in Member 1 of Suotoushan Formation is high energy coastal foreshore sediments with high texture and mineral maturity, and has been further purified by diagenesis, and both the grain-size characteristic and chemical purity have reached the standard of high-purity quartz sandstone, which can be expected raw material for high-purity quartz. The results in this article can provide accurate prospecting target to enlarge the resources potential of high-purity quartz deposits in northeastern Yunnan.
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Nseka, Denis, Vincent Kakembio, Frank Mugagga, Henry Semakula, Hosea Opedes, Hannington Wasswa, and Patience Ayesiga. "Implications of Soil Properties on Landslide Occurrence in Kigezi Highlands of South Western Uganda." In Landslides. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.99865.
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Generally, soil characteristics have a significant influence on landslide occurrence. This issue has, however, not yet been adequately analysed in Kigezi highlands of South Western Uganda. In this study, soil properties such as dispersion, grain size distribution, Atterberg limits, shear strength and clay mineralogy were analysed to establish their contribution to the spatial distribution of landslides in Kigezi highlands. The results demonstrate that deep soil profiles ranging between 2.5 and 7 meters were dominated by clay-pans at a depth between 0.75 and 3 meters. Although the uppermost surface horizons of the soil profile are loamy sand, the clay content is more than 35% especially in the sub soil. This suggests that the soil materials are Vertic in nature. In addition, the upper soil layers predominantly contain quartz, while subsurface horizons have considerable amounts of illite as the dominant clay minerals, ranging from 43–47%. The average liquid limit and plasticity index was 58.43% and 33.3% respectively. Besides, high average computed weighted plasticity index (28.4%) and expansiveness (38.6%) were obtained. These soil characteristics have great implication on the timing and nature of landslide processes in the study area. A change in soil material due to varying moisture content is thought to be a major trigger of landslides in Kigezi highlands of South Western Uganda. This understanding of soil characteristics is a key step in mitigating landslide hazards in the area.
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Amgaa, Tsolmon, Dieter Mader, Wolf Uwe Reimold, and Christian Koeberl. "Tabun Khara Obo impact crater, Mongolia: Geophysics, geology, petrography, and geochemistry." In Large Meteorite Impacts and Planetary Evolution VI. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.2550(04).
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ABSTRACT Tabun Khara Obo is the only currently known impact crater in Mongolia. The crater is centered at 44°07′50″N and 109°39′20″E in southeastern Mongolia. Tabun Khara Obo is a 1.3-km-diameter, simple bowl-shaped structure that is well visible in topography and clearly visible on remote-sensing images. The crater is located on a flat, elevated plateau composed of Carboniferous arc-related volcanic and volcanosedimentary rocks metamorphosed to upper amphibolite to greenschist facies (volcaniclastic sandstones, metagraywacke, quartz-feldspar–mica schist, and other schistose sedimentary rocks). Some geophysical data exist for the Tabun Khara Obo structure. The gravity data correlate well with topography. The −2.5–3 mGal anomaly is similar to that of other, similarly sized impact craters. A weak magnetic low over the crater area may be attributed to impact disruption of the regional trend. The Tabun Khara Obo crater is slightly oval in shape and is elongated perpendicular to the regional lithological and foliation trend in a northeasterly direction. This may be a result of crater modification, when rocks of the crater rim preferentially slumped along fracture planes parallel to the regional structural trend. Radial and tangential faults and fractures occur abundantly along the periphery of the crater. Breccias occur along the crater periphery as well, mostly in the E-NE parts of the structure. Monomict breccias form narrow (<1 m) lenses, and polymict breccias cover the outer flank of the eastern crater rim. While geophysical and morphological data are consistent with expectations for an impact crater, no diagnostic evidence for shock metamorphism, such as planar deformation features or shatter cones, was demonstrated by earlier authors. As it is commonly difficult to find convincing impact evidence at small craters, we carried out further geological and geophysical work in 2005–2007 and drilling in 2007–2008. Surface mapping and sampling did not reveal structural, mineralogical, or geochemical evidence for an impact origin. In 2008, we drilled into the center of the crater to a maximum depth of 206 m, with 135 m of core recovery. From the top, the core consists of 3 m of eolian sand, 137 m of lake deposits (mud, evaporites), 34 m of lake deposits (gypsum with carbonate and mud), 11 m of polymict breccia (with greenschist and gneiss clasts), and 19 m of monomict breccia (brecciated quartz-feldspar–mica schist). The breccias start at 174 m depth as polymict breccias with angular clasts of different lithologies and gradually change downward to breccias constituting the dominant lithology, until finally grading into monomict breccia. At the bottom of the borehole, we noted strongly brecciated quartz-feldspar schist. The breccia cement also changes over this interval from gypsum and carbonate cement to fine-grained clastic matrix. Some quartz grains from breccia samples from 192, 194.2, 196.4, 199.3, 201.6, and 204 m depth showed planar deformation features with impact-characteristic orientations. This discovery of unambiguous shock features in drill core samples confirms the impact origin of the Tabun Khara Obo crater. The age of the structure is not yet known. Currently, it is only poorly constrained to post-Cretaceous on stratigraphic grounds.
Conference papers on the topic "Quartz grain characteristics"
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Abu-Mahfouz, Israa S., Maria Ardila, and Volker Vahrenkamp. "Geochemical and Petrographic Characteristics of Lithofacies from Upper Cretaceous Organic-Rich Source Rocks, Jordan." In International Petroleum Technology Conference. IPTC, 2022. http://dx.doi.org/10.2523/iptc-21914-ms.
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Abstract The Upper Cretaceous source rocks of Jordan are organic-rich carbonate mudrocks that represent excellent source rocks but are essentially still immature to just entering the oil window. Therefore, they offer a unique opportunity to study lithology, source rock composition, and geochemistry prior to the onset of maturation and expulsion of hydrocarbons. Our study aims to examine the lithological and geochemical characteristics of these high-quality source rocks. The study utilizes an integrated petrographic and geochemical approach to define the different microfacies in the studied source rock sequence and understand their intrinsic variability. Representative subsurface samples were collected from 13 vertical cores drilled in the Upper Cretaceous interval across Jordan for bulk elemental geochemistry and microfacies analysis. To define the different microfacies and examine the mineralogical and geochemical changes, the samples were investigated for their composition, texture and lithofacies (using both optical microscopy and scanning electron microscopy (SEM/EDS)), mineralogy (XRD/XRF), and geochemistry (total organic carbon, (TOC) and total Sulphur content using a LECO elemental analyzer, and maturity using Rock-Eval). Five laminated and non-laminated carbonate and siliceous lithofacies associations were identified, all containing significant organic content (TOC varies from 7 to 29 wt.%) and Sulphur contents (2-7.5 wt.%). The rocks are of type II-S kerogen with high HI (Hydrogen Index) values of >600 mg HC/g TOC. XRD results show that the rocks are mainly composed of calcite (15-94%, 75% on average) and quartz (0-53%, 10.47% on average). Minor amounts of apatite (average 5.9%, range 0 to 27%), clay (< 7%), pyrite (up to 6%), gypsum (up to 4%) and dolomite (up to 2.7%) are also exist. Our results indicate a predominance of the organic-rich calcareous microfacies association, evidenced by the abundant foraminifera grains and the high preservation of organic matter as disseminated throughout the matrix and/or filling interparticle micropores and microfractures. This reflects the deposition in a restricted basin under anoxic conditions. The integration of the data obtained through the different techniques used in this study together with the unique characteristics of these source rocks allowed the characterization of the geological and geochemical properties of the defined lithofacies associations in these immature, organic-rich Upper Cretaceous source rocks. This, in turn, helped to achieve a better evaluation of the occurrence and distribution of the different litho- and organic facies and estimation of hydrocarbon source potential.
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Ning, Chaozhong, Xili Deng, Xuan Liao, Youjing Wang, Guangya Zhu, Haiying Han, Jing Yang, et al. "Development Mechanism of Ultra-Low Permeability Limestone Reservoirs: A Case Study of the Cretaceous S-Reservoir in H Oilfield, Iraq." In ADIPEC. SPE, 2022. http://dx.doi.org/10.2118/211591-ms.
Full textAbstract:
Abstract Ultra-low permeability limestone reservoirs in the Middle East have huge untapped reserves. In Iraq, Field H has nearly one quarter of reserves in the S-Reservoir with permeabilities of (0.02-0.4 mD). It is difficult to identify optimal drilling locations, or sweet spots, that maximize recovery factors due to poor understanding of reservoir characteristics. Using the S-limestone reservoir, this study aims to clarify the environment of deposition, diagenetic evolution, reveal the development mechanism of ultra-low permeability, and predict the distribution of more favorable areas. Whole core, thin sections, scanning electron microscope (SEM), mercury injection (MICP), well logs, and seismic data were utilized for the analysis. Through core and thin section observation, lithology, biostratigraphic sequences, pore type, and sedimentary structures were determined. Through these observations the environment of deposition of the S-Formation is interpreted as mid to outer carbonate ramp. The lithology is mainly wackestone to packstone deposited in a low energy environment below fair weather wave base. Primary fossils are planktonic foraminifera tests as grains and coccolith microfossils in the matrix. Thin sections and MICP analysis helped delineate the porosity classes and diagenetic history. The pore throat size, determined by MICP data, was 0.03 - 0.1 μm. Primary porosity is around 10-25% and is driven by intragranular voids in foraminifera tests, followed by intergranular, and intercrystalline microporosity of the matrix. Foraminifera tests are generally intact and float in the mud matrix. As a result, large intragranular pores are well developed but not connected, causing overall medium-high porosity but ultra-low permeability. Early marine calcite cement is the primary diagenetic process which destroyed porosity and permeability. Little to no evidence of secondary dissolution was observed.
Reports on the topic "Quartz grain characteristics"
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Boily-Auclair, É., P. Mercier-Langevin, P. S. Ross, and D. Pitre. Alteration and ore assemblages of the LaRonde Zone 5 (LZ5) deposit and Ellison mineralized zones, Doyon-Bousquet-LaRonde mining camp, Abitibi, Quebec. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329637.
Full textAbstract:
The LaRonde Zone 5 (LZ5) mine is part of the Doyon-Bousquet-LaRonde mining camp and is located in the southern part of the Abitibi greenstone belt in northwestern Quebec. The LZ5 deposit consists of three stacked mineralized corridors: Zone 4, Zone 4.1, and Zone 5. Zones 4 and 4.1 are discontinuous satellite mineralized corridors, whereas Zone 5 represents the main mineralized body. The mineralized zones of the LZ5 deposit and adjacent Ellison property (Ellison A and B zones) are hosted in the strongly-deformed, 2699-2695 Ma transitional to calcalkaline, intermediate to felsic, volcanic and volcaniclastic rocks of the Bousquet Formation upper member, which is part of the Blake River Group (2704-2695 Ma). Zones 4, 4.1, and 5 at the LZ5 mine are hosted in intermediate volcanic and volcaniclastic rocks of the Westwood andesitic to rhyodacitic unit (unit 5.1a), which forms the base of the upper member of the Bousquet Formation. The Ellison Zone A is hosted higher up in the stratigraphic sequence within a newly described intermediate volcanic unit. The Ellison Zone B is hosted in felsic volcanic and volcaniclastic rocks of the Westwood feldsparphyric rhyolite dome (subunit 5.3a-(b)). Mineralization in all three zones of the LZ5 deposit consists of discordant networks of millimeter- to centimeter-thick pyrite ±chalcopyrite ±sphalerite ±pyrrhotite veins and veinlets (10-20 % of the volume of the rock) and, to a lesser extent, very finely disseminated pyrite and boudinaged veins (less than or equal to 5 vol. % each) in strongly altered host rocks. Gold commonly occurs as microscopic inclusions in granoblastic pyrite and at the triple junction between recrystallized grains. The veins, stockworks, and disseminations were intensely folded and transposed in the steeply south-dipping, east-west trending S2 foliation. The vein network is at least partly discordant to the stratigraphy. A distal alteration halo envelops the LZ5 mineralized corridors and consists of a sericite-carbonate-chlorite- feldspar ±biotite assemblage. A proximal sericite-carbonate-chlorite-pyrite-quartz- feldspar-biotite ±epidote alteration assemblage is present within the LZ5 mineralized zones. A local proximal alteration assemblage of sericite-quartz-pyrite is also locally developed within Zone 4 and Zone 5 of the LZ5 deposit. Mass gains in Fe2O3 (t) and K2O, and mass losses in CaO, MgO, Na2O, and locally SiO2, are characteristic of the LZ5 alteration zones. The Ellison zone A and B are similar to LZ5 in terms of style of mineralization, but thin (10-20 cm) veins or bands of semi-massive to massive, finely recrystallized disseminated pyrite (0.1-1 mm) are distinctive. Chalcopyrite and sphalerite are also slightly more abundant in the mineralized corridors of the Ellison property and are usually associated with elevated gold grades. The zones are also slightly richer than at LZ5 in terms of gold and silver content, but narrower and less continuous in general. The Ellison Zone A is characterized by gains in Fe2O3 (t) and K2O and losses in CaO, MgO, Na2O, and SiO2. Gains in Fe2O3 (t) and local gains in K2O, MgO, and MnO, and losses in CO2, Na2O, P2O5, and SiO2, characterize the felsic host rocks of the Zone B corridor. The style of mineralization at LZ5 (pyrite ±chalcopyrite veins and veinlets, ±disseminated pyrite with low base metal content), its setting (i.e. in rocks of intermediate composition at the base of the upper member of the Bousquet Formation), and the geometry of its ore zones (stacked lenses of sulfide veins and veinlets, without massive sulfide lenses) differ from the other major deposits of the Doyon-Bousquet-LaRonde mining camp. Despite these differences, this study indicates that the LZ5 and Ellison mineralized corridors are of synvolcanic hydrothermal origin and have most likely been formed by convective circulation of seawater below the seafloor. An influx of magmatic fluids from the Mooshla synvolcanic intrusive complex or its parent magma chamber could explain the Au enrichment at LZ5, as has been suggested for other deposits of the camp. Evidence for a pre-deformation synvolcanic mineralization at LZ5 includes ductile deformation and recrystallization of the sulfides, the stacked nature of its ore zones, subconcordant alteration halos that envelop the mineralized corridors, evidence that the mineralized system was already active when the LZ5 lenses were deposited and control on mineralization by primary volcanic features such as the permeability and porosity of the volcanic rocks.