Crystallinity Of Quartz Research Articles

Quartz Crystallinity Characteristics and Their Effects on Shale Gas Reservoir Performance: A Case Study of the Deep Longmaxi Formation Shale in the Sichuan Basin, China

Quartz Crystallinity Characteristics and Their Effects on Shale Gas Reservoir Performance: A Case Study of the Deep Longmaxi Formation Shale in the Sichuan Basin, China

Microfacies Analysis and Diagenetic Effects of Middle Jurassic Succession in Rania and Sargelu Sections, Northern Iraq

The studied area covers two outcrops they are located within Sulaimaniya, northeastern of Iraq (Rania and Sargelu sections). Sargelu Sections are located in Sargelu village within Unstable Shelf, High Folded Zone, including Surdash anticline, while Rania Sectionis are located in Rania city near Hanjira village within the Unstable Shelf, High Folded Zone, including Shaweri anticline. The carbonates represent the major microfacies and constitute of lime mudstone microfacies, lime wackestone microfacies, Calcisphere-Posidonia lime wackestone submicrofacies, posidonia lime wackestone submicrofacies, lime packstone microfacies, Posidonia lime packstone submicrofacies, Posidonia-Ostacoda lime packstone submicrofacies, lime Crystalline Microfacies. The observations of the studied area show that the basin of the Sargelu Formation represents a deep part of a ramp system.These microfacies are variably affected by several diagenetic processes including mechanical and chemical compaction, cementation, recrystallization and dolomitization. The chert shows a high degree of quartz crystallinity which indicates a diagenetically product from the amorphous silica of the many radiolarians, remnant of which is preserved in several units of the Sargelu Formation

Crystallinity and formation of silica in Palaeozoic shales: A new quantification calculation method based on X-Ray diffraction

Based on X-ray diffraction (XRD) data, we suggest a new parameter for describing quartz crystallinity. The parameter is determined by analysing the quartz's fifth peak's perfection degree at (68°–68.6°)/2θ in XRD data. In contrast to other computation techniques, the new one does not require the subtraction of the environment background value from the XRD patterns, preventing the huge deviation appearance introduced artificially. Furthermore, the values obtained by the new method exhibit a decreased standard deviation compared with those obtained by previous methods following data normalisation to remove the influence of magnitude order, demonstrating better precision and stability. It has been discovered that the origin of silica, which was once thought to be a significant factor affecting silica crystallinity, has no effect. The abundance of silica and a lack of growth space can all inhibit quartz crystal growth. The appearance of endogenous pyrobitumen and exogenous hydrocarbon can possibly prevent quartz crystal growth.

Silica crystallinity: Characteristics and controlling factors in marine shale of the upper Yangtze area, China

The quartz crystallinity index (QCI) was applied to quantitatively characterise the crystallinity features of silica within the marine shale of the upper Yangtze area. A total of 67 samples, including 63 shale samples, 3 quartz vein samples, and 1 artificial quartz sample as reference, were applied in QCI calculation by X-ray diffraction (XRD). Furthermore, based on the identification and classification of graptolite biozones, a series of experimental analyses, including the total organic carbon (TOC) content, bitumen reflectance, and elemental composition, were conducted to determine the silica origin and controlling factors of crystallinity. The results indicated that biogenic silica in marine shale intervals had an obviously lower crystallinity than silica of other origins. The quartz vein in shale intervals presented the highest silica crystallinity. Silica that experienced a low diagenesis intensity exhibited the lowest crystallinity. Furthermore, biogenic silica in a state of overpressure had a much lower crystallinity than that under normal pressure. The crystallinity of silica in marine shale of the upper Yangtze area is affected by origin, diagenesis intensity, and overpressure. From the perspective of QCI, the Chengkou area is probably the next favourable area for shale gas exploration and development.

Raman microspectroscopy applied to flint provenance at the chalcolithic settlement of Zambujal (Torres Vedras, Portugal)

AbstractThe mineralogical fingerprint of both archaeological and geological flint, measuring by Raman microspectroscopy the α‐quartz, and the minor elements was studied. Quartz crystallinity index, by XRD, was calculated in geological samples. An estimation of the degree of crystallinity through Raman analysis could be used to infer quartz crystallinity in archaeological materials. The evaluation of moganite content allowed a better differentiation among Cenomanian flints from different places. It was possible to confirm the correlation between archaeological microfacies M1‐TV with the Torres Vedras Cenomanian flint and warn that the M2 flint preliminary associated to Lisboa region could be from another source area.

Investigating Potential Links Between Fine-Grained Components in Loess and Westerly Airflow: Evidence From East and Central Asia

Loess is a ubiquitous, silty aeolian sediment common across the semiarid to subhumid regions in the Northern Hemisphere. As such, the physical characteristics of loess sediment, such as modal grain size and quartz crystallinity index, have the potential to inform us about dust transport pathways and corresponding atmospheric circulation responsible for entrainment, transport, and deposition. In this article, we combine detailed granularity analyses and non-parametric end-member modeling with investigations of the quartz crystallinity index of three loess deposits, extending from East to Central Asia, with the aim of identifying dust transport processes and the climate subsystems responsible for them. We find marked differences in the grain size characteristics of Eastern and Central Asian loess. Given potential linkages of fine particles to the westerly jet stream, here we focused on the fine-grained end-members in the loess. The fine-grained components of the Central Asian Bishkek (BSK) and Chashmanigar (CMG) loess may be derived from individual particles carried at high altitude by major climate subsystems such as the westerlies. However, similar quartz crystallinity indexes of fine- and coarse-grained components in the Central Asian loess indicated that surface-level wind strength might influence the releases from proximal-sourced regions and abundances in the upper atmosphere for the fine particles. By contrast, the fine-grained component of the East Asian [Fanshan18 (FS18)] loess seems to yield physical similarities to the Tertiary Red Clays underlying many loess stratigraphies, and has been interpreted to relate to transport associated with the East Asian winter monsoon. It was further supported by quartz crystallinity indexes of the <16 μm fractions in the FS18 loess, basically consistent with those of the deserts in North China, highlighting the near-surface northwesterly winter monsoon as the dominant transport dynamics of fine-grained dust. In addition, comparisons of quartz crystallinity indexes of fine-grained components between the East and Central Asian loess also suggest that variations in fine particles within the loess might not be related to transport by the higher-level westerlies, which is in disagreement with the previous model. Therefore, our results indicate that variations in fine-grained end-members in loess are difficult to reliably document the variabilities of higher-level westerlies.

Quartz Crystallinity Index of Arabian Sands and Sandstones

AbstractAlthough quartz crystallinity index (QCI) was developed more than four decades ago, it remains a relatively new tool used in provenance studies. This study examines QCI values of Arabian sands (Quaternary sands from Nafud, Dahna, and AlRub'AlKhali deserts), and Arabian sandstones (Paleozoic and Mesozoic sandstones from northern and central Arabia). QCI values of sandstones range from 8.2 to 9.8. For Quaternary occurrences, QCI values of Nafud sands range from 7.4 to 9.5, Dahna sands range from 7.9 to 9.4, and AlRub'AlKhali sands range from 8.8 to 9.4. The data confirm that Arabian sands are derived mainly from early Paleozoic sandstones, with subordinate contributions from late Paleozoic and Mesozoic sandstones. They also highlight the role that sediment homogenization plays in narrowing QCI values of AlRub'AlKhali sands. Highest and lowest QCI values raise questions about the role of chert in controlling of QCI values of Arabian sands and sandstones. Arabian sandstones of Late Ordovician, Late Devonian, Late Permian, Late Triassic, and Cretaceous age possess the highest QCI values (>9.5). These time intervals coincide with lower abundances of siliceous sponges, and therefore fewer potential sources of chertification/silicification. Cambrian sandstones and Quaternary sands possess the lowest QCI values (<8.5). This coincides with the fact that both are of eolian origin, environments, which usually contain large quantities of quartz‐rich dust that are documented to be a primary source of silica for chert formation. Therefore, we propose that the presence of chert is responsible for the extreme values of QCI in Arabian sands and sandstones.

Effect of two thermal activation methods on shale residue based geopolymer

In this study, microwave heating (MH) was applied for thermal activation of shale residue (SR) to prepare geopolymers and the results were compared with those obtained by conventional heating (CH). The compressive strength of the geopolymers by MH was mostly higher than those by CH, and the optimal activation conditions for MH and CH was 600 °C and 700 °C with 15 min, corresponding to the strength of 19.78 and 16.19 MPa, respectively. This may be caused by the reason that MH activated SR effectively and led to a higher proportion of fine particles, low crystallinity of quartz, which also can be proved by the leaching concentration of Si and Al in alkaline solution. Thus, the better activated SR can produce the geopolymers with higher compressive strength. These results demonstrate that MH can be used as a more efficient method for the thermal activation of solid waste to prepare geopolymers.

Quartz crystallinity index: New quantitative evidence for biogenic silica of the Late Ordovician to Early Silurian organic-rich shale in the Sichuan Basin and adjacent areas, China

Quartz crystallinity index (QCI) was used to reflect the crystallisation of silica in the Late Ordovician Wufeng (WF) and Early Silurian Longmaxi (LM) Formation shale, as well as the airborne volcanic ash-derived silica in the Lucaogou Formation tuffaceous shale, to distinguish the two types of silica. The silica in different graptolite biozones exhibited different crystallisation. The WF2–3, LM1–4 graptolite biozones showed obviously lower QCI values than the LM5–9 graptolite biozones and the Lucaogou Formation samples. The graptolite organisms played the role of adsorption, fixation, and precipitation in silicon accumulation and enrichment in stratum. The biogenic origin caused the poorest quartz crystallisation in WF2–3 and LM1–4 graptolite biozones samples. The airborne volcanic ash-derived silica in the Lucaogou Formation tuffaceous shale exhibited relatively poor quartz crystallisation because of weaker diagenesis intensity. Generally, although the WF2–3 and LM1–4 graptolite biozones underwent strong diagenesis and contained a small amount of detrital quartz, the silica still exhibited lower QCI values than the airborne volcanic ash-derived silica in the Lucaogou Formation tuffaceous shale. The biogenic silica crystallisation was much poorer than that of the airborne volcanic ash-derived silica. QCI is an effective quantitative index to demonstrate the biogenic silica in the organic-rich and silica-rich shale.

Microstructural Analysis of Changes in the Morphology of Quartz Raw Materials of Different Genesis at Dry Milling

The influence of the genesis of quartz-containing rocks on the strength of particles and changes in morphology during destruction from the standpoint of the mineralogical approach in the development of the scientific direction "geonics" ("geomimetics") has been investigated. The kinetics of dry grinding of raw materials in a laboratory ball roller mill was carried out. The features of the formation and development of cracks, particle size distribution, changes in the morphology and microstructure of fragments have been studied. It was found that in natural quartz cracks develop along the surface, where the highest concentration of impurities creates a defect structure with destruction into small particles. The purest structure of hydrothermal quartz is susceptible to brittle fracture into fragments similar in morphology to the base particle. Reducing the defectiveness of the structure increases the strength of the crystals. The internal energy potential of techno genic raw materials is determined by its defective structure, which undergoes the greatest deformations during grinding, allowing obtaining the maximum values of the specific surface area and reduce the grinding time. A difference in the degree of crystallinity of quartz, which composes the polymineral techno genic raw materials, makes it possible to obtain the optimal granulometry of fine particles. The conducted research is aimed at identifying the mechanisms of destruction of quartz rocks and can be used in solving engineering problems not only in construction materials science, but also in geotechnics.

Study on the process of oil recovery from oil sludge and tailing oil sands by blending extraction

The raw materials of this study were oilfield sludge and the tailings extracted from the oil sands of Yumen. The mineral composition and particle size distribution were characterized by X-ray diffraction and gradient screening. In this study, we put forward a new process of oil sludge and oil sand tailings blending extraction. Tailings mainly contained high crystallinity of quartz and calcium carbonate. Tailings with particle size greater than 75 μm accounted for more than 95%. Oil sludge mainly contained clay minerals. Through the co-extraction experiment of different proportions of oil sludge and tailings, we can get the best condition of blending extraction. The results showed that m (tailing oil sands): m (oil sludge) = 0.5, v (solvents): m (sample) = 2, temperature 60 °C and contact time 20 minutes were the optimum technological conditions. Under the optimum conditions, the yield of the first stage co-extraction was up to 81.8%. The total yield of secondary co-extraction oil was up to 89.4%. This study overcame the problem of low yield of oil extracted from oil sludge.

Investigation on the Activity Activation and Cementitious Property of Coal Gangue with High Iron and Silica Contents

The activity of coal gangue by thermal activation and composite activation technologies was investigated. The crystal composition, framework structure and morphology change were analyzed by XRD, FT-IR and SEM, respectively. The cementitious property of coal gangue was measured by strength test. The results showed that thermal activation decomposed kaolinite in coal gangue, and formed the metastable structure with a porous state, multiple internal broken bonds and large specific surface areas. Based on thermal activation, the added lime provided the alkaline environment, then this reduced the bond energy of reactant particles and the degree of crystallinity of quartz in coal gangue. The two activation methods could effectively improve the cementitious property of coal gangue based unburned bricks, and that the composite activation technology was superior performance.

Synergetic Surface and Chemical Durability Study of the Aesthetically Enhanced Natural Quartz by Heat Treatment

The change in surface behavior of natural quartz stone before and after heat treatment with metal oxides such as: cobalt oxide (Co3O4) and copper oxide (Cu2O) under vacuum and open atmosphere has been investigated. The surface feature, bulk density and hardness value of quartz changed after heat treatment, converting to a high value product. Difference in crystallinity of quartz, pre- and post-heat treatment was obtained through X-ray diffraction (XRD) study. The electron probe microanalysis results clearly explicated the diffusion of metal ion in quartz matrix exposed under vacuum atmosphere but as coating on the surface under open atmosphere. The structural transformation of quartz after heat treatment has been observed from the XRD data and well corroborated with the nanoindentation results. Durability of such quartz to chemical hazardous environment was observed. Thus, this communication demonstrates the change in physical and chemical characteristics of natural quartz stone after heat treatment under different atmosphere.

Geochemical and tight reservoir characteristics of sedimentary organic-matter-bearing tuff from the Permian Tiaohu Formation in the Santanghu Basin, Northwest China

Tuff reservoirs have been found in petroliferous basins but have not been sufficiently studied. The discovery of the Permian Tiaohu Formation reservoir in the Santanghu Basin in Northwest China has offered an excellent opportunity to further enhance our knowledge of the tuff's geochemical and reservoir characteristics. The tuff reservoir has the peculiar property of being a sedimentary organic-matter-bearing tuff. In this study, an integrated analysis of the organic geochemistry, elemental and mineral compositions, quartz crystallinity, pore types, and tight reservoir characteristics was conducted based on samples from the 20–30 m-thick tuffs. The extracted tuff samples have total organic carbon (TOC) values of 0.5–1.0 wt.%, total hydrocarbon yield values of 2–6 mg/g, and hydrogen index values of 20–336 mg HC/g TOC. The organic matter consists predominantly of Type III and II2 kerogens, and the temperature of the maximum yield of pyrolysate varies from 420 to 450 °C, which reflects the oil-generating capacity of the rock. The physical properties of the tuff are characterised by high porosity (varying from 10% to 25%) and low permeability. The air permeability mainly ranges from 0.01 to 0.50 mD. The devitrification of vitreous textures within the tuff primarily dictates the reservoir's characteristics, i.e., the greater the degree of devitrification, the higher the porosity of the reservoir. Vitric tuffs have reservoirs with higher porosity than crystal-vitric tuffs, and the degree of devitrification is generally controlled by the burial depth (temperature) and organic matter (organic acid) content. Vitric tuffs with high porosity and permeability are usually located far from the crater and within the central–lower part of the reservoir. This research may influence geologists to pay more attention to the exploration value of this special type of reservoir in other regions.

Assessment of quartz materials crystallinity by x-ray diffraction

The estimated degree of crystallinity of natural and synthetic grown quartz and quartzite by calculating the x-ray diffraction patterns. It is shown that the index of crystallinity of natural quartzite varies widely, reflecting the different degree of their transformation. The highest values of the index of crystallinity are characterized natural and synthetic single crystals of quartz.

Caracterización de las arenas y arcillas minerales de los depósitos de canal y planicie de inundación del río Portuguesa, Venezuela

Portuguesa river floodplain is one of the largest systems in the region of central western Venezuelan llanos. This sub-Orinoco River basin covers an area of 59 500km2 which means about 6.5% of the country. The basin includes two tectonic provinces, and the river and its tributaries flow through a geological mosaic composed of rocks different ages and mineralogical composition. The interest of this paper is to examine the mineralogical composition of sands and clays in the former and present sediments of the lower basin of the river and document the relationship between the mineralogy of river sediment source area and climate variations in this region during the Late Quaternary. Most of the tributaries of the Portuguese river transport sediments from the southern and southeastern ranges of the Andes and the Interior cordillera from the Caribbean range; other small rivers originate and transport sediments from the floodplain and from the oldest foothill terraces. The methodology consisted of collecting ancient sediments deposited in the floodplain and the current channel. For this study, 40 samples of sands associated with different pools of load current bed Portuguesa River and 23 samples of clay from the oldest sediments were collected; by core drilling on bar meanders and paleomeanders in the flood plain of the river. The sand fraction was separated by dry sieving and clays by the Bouyoucos (1962) method with some modifications. Mineralogical analyzes of both fractions was determined by X-ray diffraction for the case of sand the analysis was performed only on whole sample and clays were subjected to three treatments (total, ethylene glycol and heated sample at 550°) to detecting the presence of swelling clays. The results indicate that the sands are mainly composed of quartz, forming mature sand or quartz-arenites with lesser amounts of minerals such as chlorite, muscovite, calcite and albite, among others. Which identified peaks in the diffractograms quartz infer high crystallinity of quartz (3.3°) and a peak of lower intensity (4.2°). Meanwhile, in the clay fraction 13 crystalline mineral phases were determined mainly predominating well crystallized quartz (3.3°) and the well-crystallized kaolin (7.1°), illite (10 A°) and muscovite (5.0 A°). The origin of the sands is mainly related with the physical-mechanical disintegration of the rocks of the Venezuelan South Andean Cordillera orogen and the Caribbean range during arid climatic conditions that prevailed at the end of the Late Pleistocene and factors such as transport distance, residence time, pedogenesis, chemical weathering intensity and the source area. One detrital origin for quartz, illite and muscovite reported in the clay fraction, the origin of minerals kaolinite can be inherited from older or soil deposits associated with these fluvial sediments is postulated. However, as kaolinite and montmorillonite, vermiculite, neoformation may have originated from the chemical change experienced by the mica and feldspar, associated with wetter weather conditions, environment and intensely washed acidity conditions that characterize this tropical region. The influence of climate highlighted in the mineralogical evolution of sedimentary deposits reported in this study and suggests that the sediments were deposited from the Early to Late Holocene, under conditions similar to today's most humid tropical climate. It is concluded that the origin and composition of the sands and clays analyzed mainly show a close relationship with the source area of the sediments and factors such as the distance of sediment transport, the residence time in the channel and floodplain, the intensity of chemical weathering and climatic conditions that prevailed during the Late Pleistocene-Holocene.

The determination of some crystallographic parameters of quartz, in the sand dunes of Ouargla, Algeria

In this work, the crystallographic phase, degree of crystallinity, crystal system, space group and unit cell parameters of quartz in the Ouargla region (Algeria) sand dunes have been determined using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The mid-infrared absorption spectrum showed the characteristic doublet for α-quartz at 796 and 779cm−1. The observed principle diffractions at the d-spacings of 3.7937, 3.3539 and 1.8204Å confirm the presence of α-quartz in Ouargla sand. The calculated absorption ratio (degree of crystallinity) of A796/A779≅1.756 indicated that our quartz exhibits a highly crystalline nature. The crystallographic parameters of quartz in Ouargla sand have been determined through analysis of X-ray diffraction data, carried out using the simulation code DICVOL06. These parameters were found as: hexagonal crystal system, space group P3221 (154), unit cell parameters: a=b=4.9294Å, c=5.4093Å and V=113.832Å3.

A multidisciplinary approach to trace Asian dust storms from source to sink

Tracing the source of dust storm (DS) in mega-cities of northern China currently suffers ambiguities from different approaches including source-sink proxy comparison, air mass back trajectory modeling, and satellite image monitoring. By integrating advantages of all three methods, we present a multidisciplinary approach to trace the provenance of dust fall in Xi'an during the spring season (March to May) of 2012. We collected daily dust fall to calculate dust flux variation, and detected eight DS events with remarkable high flux values based on meteorological comparison and extreme detection algorithm. By combining MODIS images and accompanying real-time air mass back trajectories, we attribute four of them as natural DS events and the other four as anthropogenic DS events, suggesting the importance of natural and anthropogenic processes in supplying long-range transported dust. The primary sources of these DS events were constrained to three possible areas, including the northern Chinese deserts, Taklimakan desert, and Gurbantunggut desert. Proxy comparisons based upon the quartz crystallinity index and oxygen isotope further confirmed the source-to-sink linkage between the natural DS events in Xi'an and the dust emissions from the northern Chinese deserts. The integration of geochemical and meteorological tracing approaches favors the dominant contribution of short-distance transportation of modern dust fall on the Chinese Loess Plateau. Our study shows that the multidisciplinary approach could permit a better source identification of modern dust and should be applied properly for tracing the provenance fluctuations of geological dust deposits.

ESR Signal Intensity and Crystallinity of Quartz from Three Major Asian Dust Sources: Implication for Tracing the Provenances of Eolian Dust

ESR Signal Intensity and Crystallinity of Quartz from Three Major Asian Dust Sources: Implication for Tracing the Provenances of Eolian Dust

ESR signal intensity and crystallinity of quartz from Gobi and sandy deserts in East Asia and implication for tracing Asian dust provenance

Electron spin resonance (ESR) signal intensity and crystallinity index (CI) of fine‐ (<16 µm) and coarse‐grained (>16 µm) quartz were measured in surface samples from the Taklimakan desert in western China, the Badain Juran, Tengger and Mu Us deserts in northern China, and the Gobi desert in southern Mongolia to evaluate whether these geophysical parameters can serve as reliable provenance tracers of Asian dust. The results indicate that spatial variability of both ESR signal intensity and CI is evident within the Taklimakan deserts and the Mongolian Gobi, but less significant in the three deserts of northern China. Coarse‐grained quartz from the Mongolian Gobi and northern China deserts can be differentiated from the Taklimakan desert using the ESR signal intensity. Fine‐grained quartz originating from three major Asian dust sources, i.e., the Gobi‐sandy deserts in western China, northern China and southern Mongolia, can be distinguished effectively using the combination of ESR and CI signals. Our results suggest that ESR signal intensity and CI can discriminate the sources of fine‐grained quartz better than coarse‐grained quartz, providing an effective approach to trace the provenance of fine‐grained dust deposition on the land and in the ocean.