Insights into Magma Storage Beneath a Frequently Erupting Arc Volcano (Villarrica, Chile) from Unsupervised Machine Learning Analysis of Mineral Compositions

A key method to investigate magma dynamics is the analysis of the crystal cargoes carried by erupted magmas. These cargoes may comprise crystals that crystallize in different parts of the magmatic system (throughout the crust) and/or different times. While an individual eruption likely provides a partial view of the sub-volcanic plumbing system, compiling data from multiple eruptions builds a picture of the whole magmatic system. In this study we use machine learning techniques to analyze a large (>2000) compilation of mineral compositions from a highly active arc volcano: Villarrica, Chile. Villarrica's post-glacial eruptive activity (14 ka–present) displays large variation in eruptive style (mafic ignimbrites to Hawaiian effusive eruptions) yet its eruptive products have a near constant basalt-basaltic andesite bulk-rock composition. What, therefore, is driving explosive eruptions at Villarrica and can differences in storage dynamics be related to eruptive style? We used hierarchical cluster analysis to detect previously undetected structure in olivine, plagioclase and clinopyroxene compositions, revealing the presence of compositionally distinct clusters. Using rhyolite-MELTS thermodynamic modeling we related these clusters to intensive magmatic variables: temperature, pressure, water content and oxygen fugacity. Our results provide evidence for the existence of multiple discrete (spatial and temporal) magma reservoirs beneath Villarrica where melts differentiate and mix with incoming more primitive magma. The compositional diversity of an erupted crystal cargo strongly correlates with eruptive intensity, and we postulate that mixing between primitive and differentiated magma drives explosive activity at Villarrica.

Study of the Dissolution of Stainless-Steel Slag Minerals in Different Acid Environments to Promote Their Use for the Treatment of Acidic Wastewaters

Several stainless-steel slags have been successfully employed in previous studies as substitutes for lime in the treatment of industrial acidic wastewaters. This study deepens the knowledge of such application, by analyzing the neutralizing capacity of different slags related to their mineral compositions. To do so, firstly the chemical and mineral compositions of all the slag samples are assessed. Then, 0.5 g, 1 g, 2 g of each slag and 0.25 g and 0.5 g of lime are used to neutralize 100 g of 0.1 M HCl or HNO3 solutions. After the has neutralization occurred, the solid residues are extracted and analyzed using XRD spectroscopy. Then, the solubility of the minerals is assessed and ranked, by comparing the XRD spectra of the residues with the obtained pH values. The results show that minerals such as dicalcium silicate and bredigite are highly soluble in the selected experimental conditions, while minerals such as merwinite and åkermanite, only partially. Moreover, Al-rich slags seem to perform poorly due to the formation of hydroxides, which generate extra protons. However, when the weight of slag is adequately adjusted, Al-rich slags can increase the pH values to higher levels compared to the other studied slags.

Development of a Calcium Aluminate Cement from steelmaking slag by altering its mineralogical compositions

Strict environmental norms and raising concern to recycle solid wastes generated during ironmaking and steelmaking processes has been the key driving force in developing various technologies. The present study describes a calcium-aluminate clinker prepared from steel ladle slag by modifying its mineral compositions. The slag paste prepared by mixing with water exhibited flash setting behaviour due to the presence of C12A7 and C3A phases. In contrast, the slag clinker, developed by sintering a mixture of pre-determined quantity of slag and Al2O3 at 1400°C for 2h and 4h, contained CA, CA2, Gehlenite and ‘Q’ phases. Hydration of slag clinker contained stable C3AH6, AH3 and stratlingite with preferential growth of calcium-aluminate hydrate prisms along c-axis that provided a well-defined raceme like morphology with interlinked structure. It improved the setting time and crushing strength of the clinkers after 6h and 24h curing at room temperature. Additionally, presence of ‘Q’ phase with lamellar prismatic crystals also helped in enhancing the strength. The developed clinker also exhibited superior crushing strength as compared to commercially available calcium aluminate cement of medium purity. The slag, used as a source of CaO could replace CaCO3 completely and thus contributed to reduction in CO2 emission during clinker making process.

Multimodal spectroscopy with chemometrics for the forensic analysis of the inorganic content of Western Australian sandy soils

This study demonstrates a multi-modal analytical sequence suited to the characterisation of sandy soils, which remain an underutilised form of forensic trace evidence. Within the Swan Coastal Plain in Perth, Western Australia, most soils are heavily leached with only small deviations in their mineral compositions. Traditional soil analyses are hence rendered inappropriate for use due to the lack of clay and organic matter. This has led to inorganic methods of analysis predominating, in addition to experimentation with modified techniques. One example is utilisation of the quartz-recovered fine fraction, which is suitable for dry, quartz-dominated sandy soils. In this study, preliminary investigations used the spectroscopic techniques microspectrophotometry, infrared spectroscopy, and x-ray diffraction, to develop a multi-faceted approach for the forensic analysis of the quartz fine fraction of soils. These data were then combined with principal component analysis to demonstrate how chemometrics can assist with objective characterisation and differentiation of sandy soil samples for forensic purposes. Chemometric analysis has not previously been attempted with data obtained from the quartz fine fraction. This methodology is transferable to other jurisdictions where dry, sandy soils predominate.

A 5-km-thick reservoir with >380,000 km3 of magma within the ancient Earth's crust

Several recent studies have argued that large, long-lived and molten magma chambers1–10 may not occur in the shallow Earth’s crust11–23. Here we present, however, field-based observations from the Bushveld Complex24 that provide evidence to the contrary. In the eastern part of the complex, the magmatic layering was found to continuously drape across a ~4-km-high sloping step in the chamber floor. Such deposition of magmatic layering implies that the resident melt column was thicker than the stepped relief of the chamber floor. Prolonged internal differentiation within such a thick magma column is further supported by evolutionary trends in crystallization sequence and mineral compositions through the sequence. The resident melt column in the Bushveld chamber during this period is estimated to be >5-km-high in thickness and >380,000 km3 in volume. This amount of magma is three orders of magnitude larger than any known super-eruptions in the Earth’s history25 and is only comparable to the extrusive volumes of some of Earth’s large igneous provinces26. This suggests that super-large, entirely molten and long-lived magma chambers, at least occasionally, occur in the geological history of our planet. Therefore, the classical view of magma chambers as ‘big magma tanks’1–10 remains a viable research concept for some of Earth’s magmatic provinces.

Rationale for using nutrient complexes with vitamin and mineral compositions in rehabilitation schemes for patients who have undergone viral infections (literature review)

The results of the previous studies have shown that the use of nutrient complexes with vitamin and mineral compositions in rehabilitation schemes for patients who have undergone viral infections, including COVID-19, is an important link in rehabilitation measures and post COVID-19. The article pathogenetically substantiates the use of biologically active food supplements containing vitamins A, D3, E, C, B1, B2, B3, B5, B6, folic acid, zinc, vanadium, catechins, proanthocyanidins, flavonoids and glycyrrhizic acid.

Effects of Ginger and Garlic on the Proximate and Mineral Compositions of Differently Processed Nile Tilapia (Oreochromis niloticus)

Freshly caught Nile Tilapia (Oreochromis niloticus) samples were obtained from Sabiyel Lake in Aliero Local Government Area of Kebbi State. Oreochromis niloticus samples were descaled, degutted, cut into chunks and rinsed with clean water at Fisheries Laboratory, Department of Forestry and Fisheries, Kebbi State University of Science and Technology, Aliero. The samples were subjected to different treatments designated as; T1 (oven drying), T2 (Frying), T3 (smoking), T4 (oven-dried + 5% ginger-garlic), T5 (Fried + 5% ginger-garlic), T6 (smoked + 5% ginger-garlic), T7 (oven-dried + 10% ginger-garlic), T8 (Fried + 10% ginger-garlic), T9 (smoked + 10% ginger-garlic), T10 (oven-dried + 15% ginger-garlic), T11 (Fried + 15% ginger-garlic), T12 (smoked + 15% ginger-garlic). The processed samples were taken to Agric. Chemical Laboratory, Faculty of Agriculture, Usmanu Danfodio University Sokoto, Nigeria, for the determination of proximate and mineral compositions. The treatments were analysed in 2 phases: at week 0 for the first phase of analysis and after 8 weeks of storage in an airtight plastic container at room temperature. The samples were then taken to the laboratory for the second phase of analysis. This study revealed that processing (oven drying, frying and smoking) of Oreochromis niloticus with ginger-garlic gave high nutritive content after 8 weeks of storage and thus might prevent the use of obnoxious substances as a means of preservation and substantially improve consumer’s satisfaction and quality fish protein intake.

PETROGRAPHIC FEATURES AND MODELLING OF SOME WATERFALL ROCKS IN KENYIR LAKE, TERENGGANU: A MICROSCOPIC PERSPECTIVE APPROACH IN SUSTAINABLE GEOTOURISM

Waterfalls around Kenyir Lake, Terengganu naturally serve as an iconic symbol of amazing rock bounded formation amidst the wilderness, which stores a hidden story for millions of years. The waterfalls feeding the Kenyir Lake have become tourists’ main attractions since they are located separately on a different island. There are three naturally picturesque waterfalls worth seeing in the study area, namely Sungai Buweh Waterfall, Lasir Waterfall, and Saok Waterfall, which are made up of granitic rock body that emerged in the Eastern Belt during the Late Triassic (~251.2 Ma). To date, the waterfall landscape in any area concerned with geotourism focusses more on outcrop architecture and geomorphological features, but has only limited accessibility to rock records. This study was carried out to evaluate the geo heritage features, of the waterfall landscape as well as its rock-forming minerals. Three rock samples were carefully collected from the waterfalls and subsequently prepared for optical thin section petrography analysis using a polarised light microscope. The optical thin section petrography further revealed precise mineral compositions, fabrics, and microstructures. A photomicrograph of the thin sections was also taken at low and high magnification levels in plane polarised light (PPL) and cross polarised light (XPL). Additionally, petrographic modelling was constructed using optical microscopic data to help identify a microscopic mineral (a hidden material in rock) in detail so that the mineral becomes clear to both geologists and the public at large. Generally, this modelling will enlighten the public on the material embedded in the rocks and illustrate the importance of learning about rock-forming minerals as well as to embed the idea of making the waterfall a Sustainable Development Goal (SDG). Besides making geology an interesting field to embark on, this mineral find affirms the beauty of the waterfalls for tourism purposes, thereby connecting geotourism and nature. The minerals from various constituents are also useful for scientific heritage purposes and may benefit the economy by serving as sustainable tourism while being part of a geopark.

Sulfuric Acid Baking—Water Leaching for Gold Enrichment and Arsenic Removal from Gold Concentrate

During the roasting of gold concentrate to improve gold recovery, arsenic is released into the air and valuable elements such as Fe, Cu, Zn, and Pb are converted into oxide minerals. In this research, we evaluated the release of As and the loss of valuable metals during the acid baking and hot water leaching processes used for gold concentrate. The acid bake tests were conducted for gold concentrate using an electric furnace by applying various concentrations of H2SO4 solution under different baking times. The water leaching process was enacted using 70 °C water for the baked samples. Chemical and mineral compositions of the raw and treated samples were analyzed using AAS and XRD, respectively. The results show that soluble metal sulfates, such as rhomboclase and mikasite, were formed in the baked samples, and that the leaching of valuable metals (Fe, Cu, Zn, and Pb) was accelerated during the hot water leaching procedure. During acid baking, arsenic was partially removed by volatilization, and the rest of the arsenic-containing minerals were converted to soluble minerals. The soluble arsenic-containing mineral resulted in a dissolution that was 60 times higher than in the roasted sample. The maximum gold grade of solid residues increased up to 33% through the acid baking–water leaching process. It was confirmed that acid baking with H2SO4 prevented As release into the air, as well as the recovery of valuable metals through hot water leaching, such as Fe, Cu, Zn, and Pb, which were formerly discarded in the tailings.

Classification and Disintegration Characteristics of the Carboniferous Rocks in Guangxi, China

To investigate the disintegration characteristics of the carbonaceous rocks in Guangxi Province, the typical carbonaceous rocks in the section exposed by the Hechi-Baise Expressway were investigated in this study. First, based on their mineral compositions and contents, the carbonaceous rocks were divided into four types: carbonate chert, carbonaceous argillaceous limestone, carbonaceous illite clay mudstone, and carbonaceous illite clay shale. Then, through indoor wet-dry cyclic disintegration test, the disintegration characteristics of the four types of rocks were studied. The test results showed the following: (1) the disintegration residues of the carbonate chert and the carbonaceous argillaceous limestone decrease linearly as the number of wetting-drying cycles increases. (2) The disintegration index of the carbonaceous illite clay mudstone and the carbonaceous illite clay shale decreases exponentially as the number of wetting-drying cycles increases. (3) As the number of wetting-drying cycles increases, the disintegration index curves of the carbonaceous illite clay mudstone and the carbonaceous illite clay shale samples gradually become stable until the disintegration of the samples is completed. (4) The disintegration of carbonaceous rocks is mainly affected by the clay content, followed by the structural form, but it cannot be ignored.