Formation Of Quartz Research Articles

Controls of normal diagenesis on poroperm parameters in red beds: examples in Miocene Muddy Creek Formation, Mesquite basin, USA and upper Devonian Old Red Sandstone, Orcadian basin, Scotland

General diagenetic patterns in Miocene Muddy Creek Formation and upper Devonian Old Red Sandstone (ORS) can be characterized as follows: i) early diagenesis characterized by the formation of early hematite, carbonate, and clay cement; ii) burial diagenesis followed by the formation of quartz and feldspar overgrowths, poikilotopic calcite and pore-filling clays; iii) late diagenesis characterized by the formation of late hematite replacing previous poikilotopic carbonate cement. Normal diagenesis has a significant impact on poroperm parameters as indicated by the destruction of pore spaces from cementation and intergranular pressure solution. Early cementation in unburied sandstones of the Muddy Creek Formation reduces sample porosities to 2÷20% of the total rock volume. Cementation destroyed the original porosity of studied sandstones through pore occlusion due to the formation of equant and meniscus calcite cement. Point-count data indicate that the intergranular cement of studied samples ranges between 22 and 44%; in contrast, the intergranular porosities range from 2÷20% of the total rock volume. These consequently indicate that the intergranular volumes that are considered to represent the original porosities of studied samples, ranged from 35÷50% of the total rock volume. Completely pore-occluding poikilotopic calcite cement in the upper Old Red Sandstone reduces poroperm values to as low as 5% porosity and 0.003 mD permeability. Late reddening is caused by replacive hematite cement in the calcite. In addition, normal diagenesis also has an impact on porosity enhancement due to dissolution in the studied red beds. This improves porosity and permeability by as much as 14% and 254 mD in the upper ORS.

Diagenetic Evolution Mechanism of the Jurassic Tuffaceous Sandstone Reservoir in Qikou Sag, Bohai Bay Basin, East China

Exploring for hydrocarbons in a pyroclastic-affected reservoir is an important research topic. Previous studies have mainly focused on laminated pyroclastic. A large number of dispersed pyroclastic is present in sedimentary rocks, and dispersed volcanic ash strongly influences the diagenetic evolution of sandstone reservoirs. However, these aspects remain understudied. We studied the mechanism of the diagenetic evolution of the Jurassic tuffaceous sandstone reservoir in Qikou Sag of the Bohai Bay Basin by performing inclusion temperature measurements, rock slice identification, and scanning electron microscopy, and using electron microprobes and microzone isotopes. We determined the mechanism of water-rock interaction. Based on microscopic observations, we determined that the main diagenesis included two-stage dolomite cementation, two-stage calcite cementation, quartz cementation, and transformation and dissolution of clay minerals. The hydrolysis and chemical transformation of pyroclastic during burial not only provided an alkaline environment in the early stage of diagenesis but also supplied ions for the formation of microcrystalline quartz and early dolomite and the transformation of clay minerals. Leaching and denudation generated early dissolution caused by a tectonic uplift. Following the epigenetic stage, microbial activity stimulated the formation of early calcite during the shallow burial stage. When the burial temperature of the stratum was 80 °C, the acidic fluid discharged from the thermal evolution of organic matter was neutralized by the soluble components in the pyroclastic, which prevented the formation of a large-scale acidic environment. When the burial temperature exceeded 100 °C, the acidic fluid generated by thermal catalytic decarboxylation of organic matter formed a large quantity of dissolution. The dissolution of plagioclase promoted the overgrowth of quartz and the growth of kaolinite.

Influence of E-Coli on workability and strength characteristics of self-consolidating geopolymer concrete based on GGBFS, flyash and alccofine

Construction sector across world utilizes cement as one of the most relevant and efficient raw material. It is being estimated that by manufacturing one ton of cement, roughly-one ton of CO 2 gas is emitted into atmosphere. With increasing awareness about global warming, development of alternative binding material that can replace cement completely has gained importance in construction sector. Many studies made on Geopolymer concrete (GPC) has proven its ability to replace cement in construction sector. This experimental investigation concentrates on completely replacing cement by alkali activated GGBFS, Fly ash and alccofine in self-consolidating concrete (SCC) mixes. The current investigation studies effect of E-Coli bacteria on workability and strength characteristics of Self-consolidating geopolymer concrete (SCGC). In this study 10 different SCGC mix samples were prepared by varying cell concentration of E-coli bacteria in order of 0 %, 1 %, 2 %, 3 %, 4 %, 5 %, 6 %, 7 %, 8 % and 9 % of total binder content. Test results indicated that all fresh SCGC mixes with bacteria exhibited better workability with values satisfying EFNARC guidelines. SCGC mix containing E-Coli in cell concentration of 8 % of total binder content gained maximum compressive strength of 36 MPa, flexural strength of 2.4 MPa and split-tensile strength of 2.8 MPa after 28 days of ambient curing. With optical density (OD) values ranging from 0.4 to 0.8, Bacterial survivability (Turbedimetric) test result showed that incorporated bacterial cells remained active within the geopolymer matrix even after 28 days. XRD analysis indicated the formation of quartz, Guanine and Anorthite minerals along with geopolymeric gels indicating a dense microstructure of geopolymer matrix resulting from enhanced geopolymerization process.

Conditions of formation and sources of fluids of the birthplace of barren residential quartz of hydrothermal-metamorphogenic-metasomatic and hydrothermal-metamorphogenic genesis (Middle and South Urals)

The paper considers the conditions of quartz formation of hydrothermal-metamorphogenic-metasomatic and hydrothermal-metamorphogenic genesis of deposits and manifestations of the Middle and Southern Urals based on the study of fluid inclusions by methods of thermobarogeochemistry, ion and gas chromatography. It is established that the studied quartz objects are formed in a wide temperature range, against the background of insignificant differences in pressure values. It is shown that the temperatures of mineral formation in deposits of hydrothermal-metamorphogenic-metasomatic genesis vary from 440-230 ° C at a pressure of 1.2-1.4 kbar. The formation of these veins occurred with the participation of K-Mg-Fe-chloride fluid with a salinity of 1.2-8.7 wt. % NaCl-eq., depleted Mg and Fe due to the deposition of magnesia-ferruginous carbonates. A typomorphic feature of hydrothermal-metamorphogenic-metasomatic quartz is the high values of boron associated with the placement of quartz veins among pegmatoids and the presence of boron-containing mineral inclusions on quartz-vein objects. Veins of hydrothermal-metamorphogenic genesis were formed when the crack system was filled with quartz with the participation of a substantially K-Na chloride fluid (0.2-15.5 wt. % NaCl-eq.), at homogenization temperatures of 435-335 ° C and a pressure of 1.3-2.3 kbar. In the composition of fluid inclusions of hydrothermal-metamorphogenic-metasomatic quartz, the sum of "harmful" components (H2O, CO2, CH4, Cl, B, Na, K, Mg and Li) is less than in hydrothermal-metamorphogenic quartz. The studied quartz deposits and veins were formed in the range of temperatures and pressures not higher than the green shale stage during several successive stages: the formation of quartz veins – in a more high-temperature hydrothermal stage, while subsequent changes in quartz veins occurred under the influence of metamorphism processes, with a decrease in temperature. Subsequent changes are associated with the appearance of fracturing, cataclysm and recrystallization of quartz bodies with a decrease in grain size.

Mineral association in pegmatites from the Djurkovo Pb-Zn deposit, Central Rhodopes: preliminary results

Deformed pegmatites of varying thickness and position are a significant constituent intruded in the metamorphic complex, hosting the Djurkovo Pb-Zn deposit in Central Rhodopes. The mineral composition of the pegmatites consists of plagioclase, K-feldspar, quartz, and minor micas. The main accessory minerals are allanite, titanite, apatite and zircon. Late hydrothermal alteration of pegmatites led to the formation of epidote, adularia, sericite, chlorite, carbonate, quartz and leucoxene. Rare earth carbonate-phosphate assemblage (REE+Y, Th, U), manifested as ˂ 20 µm anhedral grains, is observed along fractures and dissolved zones in allanite and titanite. Because of the limited mobility of REE in fluids, these elements are barely transported during the hydrothermal activity and are incorporated in new phases, precipitated in the frames of the altered accessory minerals. The studied pegmatites contain a significant amount of accessory minerals rich in incompatible elements and therefore could be considered as their potential source.

Genesis of the Longtougou gold deposit, South Qinling Orogen, China: Constraints from ore geology, trace element, and S–Pb–H–O isotopes

Orogenic gold deposits are a significant source of gold production, although the geological processes and metallogenic material sources remain somewhat controversial. The Longtougou deposit is located in the South Qinling Orogen, China, and is a newly discovered moderate tonnage gold deposit. The deposit can be split into four stages of mineralization and contains three types of pyrite (Py0, Py1, and Py2). The Py0 is fine-grained, present as subhedral–anhedral aggregates, and formed during diagenetic stage of sandstones of the Devonian Dafenggou Formation. Coarse- to medium-grained euhedral Py1 is hosted by early-ore stage quartz–pyrite veins. The last pyrite to form was fine-grained anhedral Py2, which coexists with barite within main-ore stage quartz–barite–polymetallic sulfide veins. The final stage is associated with the formation of quartz–barite–carbonate veins and stockworks. Early-ore stage samples yield δ18OH2O values from 9.8‰ to 13.9‰ and δDV-SMOW values from −75.4‰ to −65.3‰, indicative of fluids may be derived from a mixing of metamorphic and magmatic fluids. Main-ore stage samples yield δ18OH2O and δDV-SMOW values of 5.4‰ and −70.6‰, respectively, whereas late-ore stage samples yield δ18OH2O values from −9.0‰ to 3.3‰ and δDV-SMOW values from −74.5‰ to −56.7‰. These data indicate that the main-ore stage involved meteoric and organic water, whereas the late-ore stage was dominated by meteoric water. The Py0 has significantly negative δ34S values (−15.1‰ to −14.5‰), suggesting that the sulfur in this pyrite was derived from bacterial sulfate reduction. Early-ore stage sulfides have restricted ranges of δ34S values (−5.7‰ to 5.6‰) that are indicative of a magmatic–hydrothermal fluid origin. The Py2 yields lower positive δ34S values (2.4‰ to 5.3‰) and coexisting barite has higher positive δ34S values (15.3‰ to 17.5‰), indicative of a transition into an oxidizing environment. The Δ34SA–B−δ34SB diagram yields a δ34SΣS value of 8.2‰, indicative of sulfur derived from a mix of sedimentary and magmatic sources. All of the sulfides have Pb isotopic ratios that plot within the field of underlying Paleozoic strata and are close to the Indosinian and Yanshanian granites, suggesting that the metals were derived from a combination of underlying Paleozoic sedimentary and granitic sources. Most of the hydrothermal pyrites have Co/Ni and S/Se ratios that are indicative of a magmatic-hydrothermal origin, suggesting that the Au was derived predominantly from magma but with possible contributions from sedimentary and metamorphic fluid sources. In addition, hydrothermal pyrites have trace-element variations that differ from Py0, suggesting that the gold was not derived from the local host rocks. An underlying Paleozoic sedimentary sequence enriched Au that underwent greenschist facies metamorphism may be another source of the gold. The majority of invisible Au is present as structurally bound, with visible gold present as inclusions or as fracture fills within Py2. The gold was precipitated as a result of fluid mixing, a process that caused an increase in fO2 values and a change from reduced to oxidized conditions during the main-ore stage. This study suggests that the Longtougou deposit is an orogenic gold deposit that formed during the transition between compression and extension in an intracontinental orogeny.

Effect of Al2O3 content on microstructure and oxidation behavior of silicate enamel coatings on a Ni-based superalloy at 1000 °C

Enamel coating, which is of low thermal conductivity and high chemical stability, has been employed for the protection of many hot parts against oxidation. It is composed of multiple oxides, and each oxide component plays a certain role on thermophysical properties. In this paper, a type of silicate enamel coating with different contents of oxide component Al 2 O 3 was prepared on K444 superalloy. Its microstructural evolution and cyclic oxidation behavior at 1000 °C were investigated. Results indicated that the A0 enamel coating, which was free of Al 2 O 3 in composition, suffered from serious crystallization at high temperature. The formation of quartz, cristobalite and SrSiO 3 crystals resulted in significant mass loss during cyclic oxidation. However, precipitation of these crystals was almost completely prohibited in the A10 and A15 coatings with 10 and 15 wt% Al 2 O 3 , respectively. The A10 coating had no mass loss after cyclic oxidation. But much high content of Al 2 O 3 resulted in the formation of abundant long strip crystals of SrAl 2 Si 2 O 8 in the A15 coating, which led to minor spallation. Furthermore, enamel coatings with Al 2 O 3 (above 6 wt%) promoted the formation of a continuous alumina scale at the enamel/alloy interface, which improved oxidation resistance and increased bonding strength. The well grown alumina scale at interface as well as the mild crystallization ensured high spallation resistance of the enamel coating A10.

Experimental diagenesis using present-day submarine turbidite sands

Hydrothermal-reactor experiments were conducted to investigate the potential formation of chlorite and microquartz grain coatings on detrital quartz and feldspar grains, and to understand their role in inhibiting the formation of quartz and feldspar (albite) overgrowths. Modern-day proximal and distal unconsolidated sediment from the Bute Inlet (British Columbia, Canada) with known amounts of precursor clay content, were used as starting material. The samples were heated to 250°C at water vapour pressure in a hydrothermal reactor for 72 h. The experiments were performed with and without a silica supersaturated Na2CO3 (0.1 M) solution. Detailed microscopy and EDS mapping analysis identified that the main chlorite precursor, crucial for the formation of the synthesized grain coatings, was a Mg-rich chlorite. The experimental results showed that where the volume of precursor chlorite was low (i.e., 0.1%), notably in the proximal channel Bute samples, chlorite coatings were poorly developed, with a clay volume and maximum chlorite-coating coverage of 0.5% and 47%, respectively. In contrast, with an initial precursor chlorite volume of 14.5%, the distal lobe Bute sample has generated chlorite volume ranging from 42.9% to 56.3% post-experiment, with a maximum chlorite-coating coverage of 77%. The chlorite and microquartz coatings formed in the study are morphologically similar to those seen in natural sandstone reservoirs, and they have restricted the development of quartz and albite cementation in the reactor experiments. The findings provide quantitative data that can be utilised to describe diagenetic changes in mesodiagenetic environments.

High-temperature phase transformations of hydroxylapatite and the formation of silicocarnotite in the hydroxylapatite–quartz–lime system studied in situ and in operando by Raman spectroscopy

Silica-/calcium phosphate ceramics are of high interest in various aspects. On the one hand, they play an important role in medical applications due to their excellent biocompatibility. Therefore, detailed knowledge of the formation and stability properties of the high-temperature products ensures production under controlled conditions. On the other hand, they were identified as sinter deposits in industrial kilns, where it can indicate problems caused by too high combustion temperatures during the thermal combustion processes. Here, we report the results of two Raman heating studies to ~ 1300 °C in 10 °C-steps with nano-crystalline hydroxylapatite (HAp) and tricalcium phosphate (TCP), and a Raman heating study of natural silicocarnotite (to ~ 1200 °C, 50 °C-steps). The Raman experiments were complemented with thermal analyses. The Raman spectra of nano-crystalline HAp recorded at high temperatures revealed the stepwise loss of adsorbed water and surface-bound OH groups until ~ 570 °C. Significant loss of structural OH started at ~ 770 °C and was completed at ~ 850 °C, when HAp transformed to β-TCP. Between ~ 1220 and ~ 1270 °C, β-TCP was found to transform to α-TCP. The room temperature Raman spectrum of silicocarnotite is characterized by an intense v1(PO4) band at 951 ± 1 cm−1 that shifts to ~ 930 cm−1 at ~ 1200 °C. Using hyperspectral Raman imaging with a micrometer-scale spatial resolution, we were able to monitor in operando and in situ the solid-state reactions in the model system Ca10(PO4)6(OH)2-SiO2-CaO, in particular, the formation of silicocarnotite. In these multi-phase experiments, silicocarnotite was identified at ~ 1150 °C. The results demonstrate that silicocarnotite can form by a reaction between β-TCP and α′L-Ca2SiO4, but also between β-TCP and CaSiO3 with additional formation of quartz.

Fluid inclusions in vein quartz as a reflection of the deformation stages of the junction area of Baikal-Muisk and Barguzin-Vitim structural-formation zones (Western Transbaikalia)

Research subject. Fluid inclusions in quartz of three vein systems associated with tectonic cracks occurred during the development of thrust and shear deformations of the Western Transbaikalia. Vein systems localized in volcanic, terrigenous and granite rocks. Methods. The composition of fluid inclusions was studied by microthermometry, Raman spectroscopy and gas chromatography-mass spectrometry. Results. The quartz under study was formed by high-density medium-temperature NaCl-KCl and a low- and medium-salinity water-carbon dioxide fluid (2-5 wt % NaCl eq.). A distinctive feature of quartz of different vein systems was found to be the gas phase composition of inclusions associated with the composition of host rocks. The minimum temperatures of vein quartz formation were determined to range from 180 to 450°C under the minimum fluid pressure values of 0.7-2.9 kbar. Conclusions. Complex vein systems of the junction zone of the Baikal-Muiskaya and Barguzino-Vitimskay SFZ, confined to different host rocks and having different structural positions, are characterized by a similar fluid composition and a common thermodynamic history reflecting the change of deformation aggregates. The metamorphogenic-hydrothermal nature of the fluid involved in the formation of quartz vein systems was established. The development of the hydrothermal system was accompanied by its influence on the host rocks, which was manifested in the variations of fluid composition. The evolution of a single hydrothermal system is associated with tectonic deformation processes, which can be described by three dynamic stages corresponding to three quartz generations.

Trace Element Concentrations and Mineralogy of Quartz Vein Deposits from Southeastern Hubei Province, China

Hydrothermal quartz samples collected from the Fujiashan and Yipanqiu quartz deposits in southeastern Hubei Province, China have been investigated by analytical combination of optical microscopy, scanning electron microscopy, and inductively coupled plasma optical emission spectroscopy, in conjunction with conventional beneficiation processing to evaluate their potential as sources of high purity quartz (HPQ) from a commercial perspective. Microscopy efforts reveal that major mineral impurities associated with quartz are K-feldspar, muscovite, iron oxides, rutile with accessory kaolinite. Bulk trace element concentrations of the processed quartz products demonstrate that the Fujiashan-II quartz vein with cumulative impurities of less than 50 μg g−1 with <30 μg g−1 Al and <10 μg g−1 Ti fits with the lattice-bound criteria for HPQ, meeting the requirement by a HPQ deposit. However, the Yipanqiu quartz deposits are not promising for HPQ production due to high fluid inclusion contents, intimate intergrowth texture with highly variable crystal size, and probably high lattice-bound element contents. The early Neoproterozoic Fujiashan quartz deposits have likely been experienced long-term retrograde metamorphism-related recrystallisation which might contribute to high-purity quartz formation. Due to a much younger crystallization age compared to the Fujiashan deposits, quartz grains in the middle Cretaceous Yipanqiu quartz vein retain high trace elements, leading to exclusion of being a HPQ deposit.

Partial substitution of feldspar by alkaline-rich materials in the electrical porcelain insulator for reduction of processing temperature

Porcelain is the most widely used overhead power-line insulator. The demands for porcelain insulators have increased dramatically owing to a sharp increase in the electric power demand and supply. Usually, porcelain production demands high sintering temperatures. Herein, an electrical porcelain insulator was produced from Bombowha clay and Arero quartz and partially replaced feldspar with sodium carbonate at a reduced processing temperature. The porcelain samples were prepared by fixing the clay and quartz amount 45 and 10 wt%, respectively, and the portion of feldspar was replaced by 5, 7.5, and 10 wt% of alkaline-rich sodium carbonate. The desired composition was milled, shaped, and finally sintered at 1000, 1100, and 1200 °C. The XRD and SEM results show the early formation of quartz and mullite phases at 1000 °C, which determine the mechanical and dielectric strengths of the porcelains. The dielectric strength of the samples increases with increasing the alkaline-rich sodium carbonate content owing to the vitrification and needle-shaped mullite formation. The porcelain sample with 10 wt% of Na2CO3 content and a sintering temperature of 1200 °C has an optimum dielectric strength of 7.60 kV mm−1.

Алюминий в кварце месторождения золота Дарасун (Восточное Забайкалье, Россия)

Quartz samples taken from the ore veins of the Darasun gold deposit (Eastern Transbaikalia, Russia) were studied using electron paramagnetic resonance (EPR) and laser ablation (LA) methods. The purpose of the research was to clarify the behavior of the Al impurity during quartz crystallization and its subsequent recrystallization. The results of the research were used to determine the genetic informativeness of the Al impurities concentration in ore quartz. A separate study of the regularities of the distribution of Al impurity in the regions of crystalline structure and in the zones of crystal lattice distortions was carried out. In the regions of crystalline structure, the Al impurity concentration NAL was determined by the concentration of paramagnetic Al–O–-centers associated with the presence of substitutional Al3+ ions. The content of the Al impurity in the zones of crystal lattice distortions was judged by the difference between the gross concentrations of aluminum CAl and the values of NAL. It was taken into account that the intensity and direction of the studied processes can be influenced by the temperature of quartz formation and the degree of its recrystallization. The temperature of quartz formation was estimated by the values of Ti impurity concentration, and the degree of recrystallization was estimated by the content of Li impurity CLi in the mineral. It was found that the amount of Al impurity localized in the zones of crystal lattice distortions is an order of magnitude higher than that present in the zones of crystalline structure. It is shown that this phenomenon is explained by the high ability of the zones of crystal lattice distortions to capture of Al impurity during quartz crystallization. The amount of Al impurity trapped by quartz increases sharply with an increase in the temperature of the mineral formation. In areas of regions of crystalline structure, a different picture is observed − impurity capture during crystallization proceeds with low intensity and is not so critically dependent on temperature. It was found that the Al impurity in the considered zones behaves differently during quartz recrystallization. If Al impurity capture continues in the regions of crystalline structure, then Al impurity removal from quartz can occur in the zones of crystal lattice distortions at high CAl values. Based on the data obtained, the areas of use of aluminum impurity contents as a typomorphic feature of ore quartz were determined. The Al impurity concentrations proved to be suitable for use in cases of low ore formation temperatures, and its gross CAl contents have the prospect of wider use. It is noted that a characteristic feature for quartz from high productivity zones is a negative angle of slope of the CAl(CLi) dependence plot.

Effect of desiccation on ashcrete (HSDA)-treated soft soil used as flexible pavement foundation: zero carbon stabilizer approach

Abstract The potential of using ashcrete to improve the microstructural, microspectral and shrinkage properties of expansive soils has been investigated under laboratory conditions. In addition to microstructural, three chemical modulus (TCM) and microspectral examinations, responses to linear shrinkage, volumetric shrinkage and crack width were also investigated using 30-day drying periods for expansive soil treated with ash cement. Moisture-related infrastructures such as the sub-floor of resilient pavements are prone to moisture by the rise and fall of the water table during seasonal changes. Therefore, the effect of soil improvement on soil morphology, chemical content and microspectral patterns was investigated. The soil was classified and characterized as (A-7-6) high plasticity soil and poor classification conditions. The hybrid sawdust ash (SDA) known as ashcrete, which has zero carbon footprint was obtained by activating SDA by mixing it with a reformulated activator material (a mixture of 8 M NaOH and a solution of NaSiO2 in a 1:1 ratio). The zero carbon cement was further used in percent-by-weight proportions of 3, 6, 9 and 12 for the soil improvement. X-ray fluorescence (XRF) and scanning electron microscopy (SEM) experiments were carried out to evaluate the pozzolanic resistance via the chemical composition of the oxide, TCM and the profile of the surface contour of the additives and the soil. XRF exposures revealed that the additives had lower pozzolanic resistance, which increased with the improved mixtures thus forming an improved soil mass. In addition, it showed that TCM silica moduli dominated soil stabilization with ashcrete. Scanning electron microscopy examination showed an increase in soil-ettringite and gel formation with the addition of ashcrete. Also, the microspectral studies of chemical oxide EDXRF and XRD have shown excellent results at 12 mass percent cement and soil cement, which has optimized aluminosilicate formation more than 70% and formation of calcite and quartz that has shown the potential of a zero carbon stabilization geomaterial ash cement as a good complementary binder.

New data on the formation conditions of the Drazhnoye deposit gold mineralization (Republic Sakha, Yakutia)

New results of thermal, baric, and geochemical studies indicate that quartz veins within the deposit were formed in mesozonal conditions at depths 3–9 km from heterogeneous CO2–H2O fluids containing water and carbon dioxide with low concentrations of salts and high concentrations of CO2, which is typical for ore-forming fluids of orogenic vein gold deposits. According to the phase composition, there are three types of fluid inclusions: 1) carbon dioxide- water; 2) gas-filled with dense carbon dioxide; 3) biphasic gas-liquid water-salt solutions. There are Na, Mg, and Fe chlorides predominated in the ore-forming fluids. It is assumed that the fluids migrated along the regional Adycha-Taryn shear zone, uplifting to the Earth’s surface at supra-lithostatic pressures, followed by the deposition of ore elements and the vein quartz formation during tectonic movements along shear zones.

Co-genetic formation of scheelite- and wolframite-bearing quartz veins in the Chuankou W deposit, South China: Evidence from individual fluid inclusion and wall-rock alteration analysis

The large-scale Chuankou W deposit is located in the north part of the Nanling metallogenic belt, South China. It comprises independent quartz vein-type scheelite and wolframite mineralization, both associated with the underlying granitic intrusion spatially. The scheelite-bearing quartz veins occur invariably in sandstone and slate to the west, whereas the wolframite-bearing quartz veins are mainly hosted by the granite to the east. To reveal the fluid characteristics of the two mineralizing vein systems, detailed petrography, microthermometry, and Raman spectroscopic analyses were carried out on fluid inclusions in scheelite, wolframite and their coexisting quartz. Major and trace element concentrations of fluids were obtained from individual fluid inclusions in quartz via LA-ICP-MS analysis. Wall-rock alteration of both vein systems were evaluated by TESCAN Integrated Mineral Analyser (TIMA) analysis, and based on which the bulk geochemical data of wall-rock as a function of distance from the vein were obtained for scheelite-bearing quartz vein. These data aid elucidation on the nature of fluids in the two types of W mineralization. Fluid inclusions in quartz and its coexisting tungsten minerals share similar homogenization temperature and salinity, suggesting near concurrent formation of quartz and ore minerals. LA-ICP-MS analyses on pseudosecondary fluid inclusions in quartz associated with ore minerals show considerable concentrations of W in both mineralizing fluids, whereas Fe, Mn and Ca are generally absent irrespective of their higher detection limits. This may imply that Ca, Fe, and Mn were not initially derived from the granitic magma. The fluid compositions of both types of W mineralization display similar Rb/Na, K/Na, and Rb/Cs ratios, indicating a similar initial fluid source. The TIMA image shows that the host rock (sandstone) of scheelite-bearing quartz vein contains abundant Ca-rich minerals, such as apatite and calcium feldspar, indicating wall-rock as potential source providing Ca for the precipitation of scheelite. This assumption is strongly supported by bulk geochemical data of wall rock as a function of distance from hydrothermal quartz vein. In contrast, the tourmaline-rich granite hosting wolframite quartz veins may be a potential source of Fe for the precipitation of wolframite. Study on fluid composition combined with wall rock alteration suggest that the magmatic-sourced fluids and fluid–wall-rock interactions exerted primary control on the large-scale variations in mineralization types in the deposit, with scheelite- and wolframite-bearing quartz veins being both genetically and spatially related. Results of this study provide new guidelines for mineral exploration, suggesting a homologous scheelite-dominated deposit being likely to exist in association with a wolframite-dominated deposit, where the lithology of Ca-bearing formations may indicate potential prospecting areas.

Analysis of Fine Glass Waste Addition as a Filler Material for Sand Substitution on the Properties of Mortar Products

Inorganic glass waste can replace sand in mortar production due to its SiO 2 content being greater than 70%. This study aims to analyze the increase in mortal product agility due to the substitution of sand and reducing environmental pollution. The fine glass waste used is restrained on 80 and 120 mesh sieves. The fine glass waste substitution variations are 0, 10, 20, 30, 40, and 50% of the sand weight. The results show that fine glass waste could be used as a material for sand substitution because of the content of SiO2 of 73.8%. The results from XRD indicate that the phase of fine waste glass is amorphous. The mortar was printed with a 5x5x5 cm cube mold, and it was soaked for 7, 14, and 21 days. Based on the results, the compressive strength with a high value of 13.58 MPa at 20% fine glass waste substitution and 120 mesh. The density of 2.8±0.8 g/cm 3 , porosity 4.40±0.001%, and absorption 2.83±0,0009%. The compressive strengths, density, porosity, absorption, XRF and XRD characterization were evaluated. The results showed that the SiO 2 compound in waste glass with the right composition of 20% could significantly increase the compressive strength. Phase formation of Calcite (CaCO 3 ), Quartz (SiO 2 ), and Portlandite (Ca(OH) 2 ) was formed from the results of XRF characterization

Mineral paragenesis and stratigraphic setting of the Neoproterozoic volcano-sedimentary succession of Samran Group, Jabal Farasan Area, West central Arabian Shield, Saudi Arabia

Jabal Farasan is located in the west central part of the Arabian Shield. The present study aims to reveal the stratigraphic setting and mineral paragenesis of the exposed volcano-sedimentary succession of the Samran Group in Jabal Farasan area. The succession of Samran Group is composed of three successive facies: the lower interbedded andesitic tuffs and tuffaceous andesites and trachyte’s (F1), the middle-altered quartz diorite/andesite (F2) and, an upper interbedded andesitic tuff, tuffaceous andesites and trachytes (F3). The vertical variations in the petrographic lithotypes depend mainly on the position of the depositional sites relative to the volcanic centers (proximal and distal). Both the volcanic rocks and the associated units are subjected to syn-and post-depositional diagenetic/metamorphic processes. These processes include the formation of the Fe2+-silicates: (i.e., chlorite instead of the volcanic ashes and the formation of plagioclase minerals). Post diagenetic recrystallization of the tuffaceous mudstones and the formation of microcrystalline quartz. The diagenetic oxidation of the Fe2+-silicates led to the formation of volcaniclastic red beds in certain stratigraphic horizons.

Microstructure, 3-chemical moduli (3CM) and micro-spectral analyses of HSDA-treated black cotton soil for sustainable subgrade construction

Microstructural, 3-chemical moduli (3CM) and micro-spectral analyses has been carried out in this research work on HSDA-treated black cotton soil for sustainable subgrade construction. Black cotton soil (BCS) is considered problematic and incapable of withstanding axial load due to its erratically swell-shrink behavior on exposure to moisture. Sadly, hydraulically bound structures like the subgrade of highway pavement foundations are seasonally exposed to moisture through suction or capillary rise as the water table rises. So, the effect of treatment on the surface configuration, oxide composition and micro-graphical arrangement of the BCS has been studied. The BCS was characterized and classified as A-7 group soil with high plasticity and poorly graded condition. Sawdust ash was obtained by combusting sawdust and sieving through 2.35 mm aperture sieve. It was further activated by blending it with pre-formulated activator material (a blend of 8 M NaOH solution and NaSiO2 in 1:1 ratio) to generate HSDA. The HSDA was further used in wt % of 3, 6, 9, and 12 to treat the BCS. The treated samples were studied to their structure changes, 3-chemical moduli, and micrograph changes. XRF and SEM tests were conducted to determine the pozzolanic strength via the chemical oxide composition, 3-chemical moduli (3-CM) and the microstructural arrangement of the experimental materials and the treated BCS. The XRF tests showed that the experimental materials had less pozzolanic strength, which improved with the treated blends thereby forming stabilized mass of BCS. Also, it showed the silica moduli of the 3-CM dominated the stabilization of the soil with HSDA. SEM tests showed increased formation of ettringite and gels with the addition of the HSDA. Also, the ED-XRF chemical oxide and XRD micro-spectral studies showed great outcome at 12 wt% of HSDA and BCS blend with high formation of aluminosilicates above 70% and the formation of quartz and calcite, which showed HSDA potential as good supplementary cement.

Chemically Oscillating Reactions during the Diagenetic Formation of Ediacaran Siliceous and Carbonate Botryoids

Chemically oscillating reactions are abiotic reactions that produce characteristic, periodic patterns during the oxidation of carboxylic acids. They have been proposed to occur during the early diagenesis of sediments that contain organic matter and to partly explain the patterns of some enigmatic spheroids in malachite, phosphorite, jasper chert, and stromatolitic chert from the rock record. In this work, circularly concentric self-similar patterns are shown to form in new chemically oscillating reaction experiments with variable mixtures of carboxylic acids and colloidal silica. This is carried out to best simulate in vitro the diagenetic formation of botryoidal quartz and carbonate in two Ediacaran-age geological formations deposited after the Marinoan–Nantuo snowball Earth event in South China. Experiments performed with alkaline colloidal silica (pH of 12) show that this compound directly participates in pattern formation, whereas those with humic acid particles did not. These experiments are particularly noteworthy since they show that pattern formation is not inhibited by strong pH gradients, since the classical Belousov–Zhabotinsky reaction occurs in solution with a pH around 2. Our documentation of hundreds of classical Belousov–Zhabotinsky experiments yields a number of self-similar patterns akin to those in concretionary structures after the Marinoan–Nantuo snowball Earth event. Morphological, compositional, and size dimensional comparisons are thus established between patterns from these experiments and in botryoidal quartz and carbonate from the Doushantuo and Denying formations. Selected specimens exhibit circularly concentric layers and disseminations of organic matter in quartz and carbonate, which also occurs in association with sub-micron-size pyrite and sub-millimetre iron oxides within these patterns. X-ray absorption near edge structure (XANES) analyses of organic matter extracted from dolomite concretions in slightly younger, early Cambrian Niutitang Formation reveal the presence of carboxylic and N-bearing molecular functional groups. Such mineral assemblages, patterns, and compositions collectively suggest that diagenetic redox reactions take place during the abiotic decay of biomass, and that they involve Fe, sulphate, and organic matter, similarly to the pattern-forming experiments. It is concluded that chemically oscillating reactions are at least partly responsible for the formation of diagenetic siliceous spheroids and concretionary carbonate, which can relate to various other persistent problems in Earth and planetary sciences.