Hasil untuk "Mineralogy"

O. Quintela, S. Burchardt, T. Mattsson et al.

Abstract Magma reservoirs typically form through the incremental emplacement of smaller magma pulses over extended timescales. Pulsed reservoir growth significantly impacts a magma body's temperature evolution, chemical differentiation potential, and the probability, scale, and timing of volcanic eruptions. Moreover, the addition of thermal energy and magmatic fluids reheat and hydrothermally alter previously emplaced magma. Consequently, it may be difficult to distinguish individual magma pulses in exposed solidified intrusions (plutons), obscuring evidence of magma body construction and evolution. In this study, we employ geological mapping combined with petrofabric and Anisotropy of Magnetic Susceptibility (AMS), Anisotropy of Anhysteretic Remanent Magnetization (AARM), hysteresis, First‐Order Reversal Curves (FORCs) and susceptibility versus temperature analyses to investigate pulsed magma emplacement and its consequences in terms of fabric overprinting and hydrothermal alteration within the Slaufrudalur pluton in Southeast Iceland. The field mapping documents distinct emplacement styles, including magma ascent in marginal zones, subhorizontal sheet emplacement, and bulk intrusion below the sheets. The AMS fabrics show high Km values (∼1 × 10−2 SI), but overall weak degrees of anisotropy (Pj < 2%). The weak magnetic fabrics reflect the destructive interference between the magnetite fabric and the fabric of hematite and iron hydroxides. Later, pulses of magma are less oxidized, which indicates that the alteration was caused by volatile release from magma that intruded below already emplaced magma. Our results demonstrate that rock magnetic data provide a novel approach to detecting magma pulse interactions and associated alteration in plutons, offering insights into magma body dynamics.

Junjie Dong, Gabriel-Darius Mardaru, Paul D. Asimow et al.

We present globally inverted pressure–temperature ( P – T ) phase diagrams up to 5000 GPa for four fundamental planetary materials, Fe, MgO, SiO _2 , and MgSiO _3 , derived from logistic regression and supervised learning, together with an experimental phase equilibrium database. These new P – T phase diagrams provide a solution to long-standing disputes about their melting curves. Their implications extend to the melting and freezing of rocky materials in the interior of giant planets and super-Earth exoplanets, contributing to the refinement of their internal structure models.

Nur Khatibah Md Yunos, Hui-Juan Pan, Shouye Yang et al.

Abstract Shipwreck ceramics are rarely analysed in situ since conventional mineral tests require sampling and jeopardise conservation. This study present the first application of full-range visible–near-infrared (VIS–NIR, 350–2500 nm) reflectance spectroscopy to shipwreck ceramics, analysing 30 sherds from the 16th-century Bidong wreck off Peninsular Malaysia. CIELAB colour space reveals the a*–b* linearity improves markedly from R² ≤ 0.50 on uncleaned surfaces to 0.80 in clean-powder subsamples, providing an objective metric for de-encrustation. High chromaticity and pervasive hematite document dominantly oxidising, whereas a minority of grey fabrics signal reduction firing conditions. Varimax-rotated PCA (VPCA) resolves 18 spectral components in intact sherds but only 11 after cleaning, demonstrating how surface alteration inflates apparent mineral diversity. Diagnostic loadings for illite and Fe-rich pyroxene (hedenbergite) tie the ceramic body to Sukhothai red clays, while copper sulphides and marine carbonates fingerprint post-burial interaction with Cu fittings and seawater. A weak 600–620 nm shoulder tentatively matches lazurite, a blue pigment rarely reported in Southeast Asian wares thus requires micro-analytical confirmation. This rapid, micro-destructive VIS–NIR method provides preliminary information about the salvaged artifacts which can be further correlated with another scientific study for provenance and production techniques interpretation.

Magdalena Angelova, Rusi Rusew, Rositsa Nikolova et al.

A new polymorph modification of SrB₂O₄ was obtained from melt containing Sr₂CO₃, H₃BO₃ and CuCl₂·2H₂O with a molar ratio of 2:2:1. The growth was carried out by cooling the melt from 1180 to 860 °C. The obtained material looks like a green bulk mass at the edges, of which grew transparent single crystals of SrB₂O₄ (approximately 0.1 × 0.2 × 0.1 mm in size). The crystals were studied by scanning electron microscopy, single crystal, powder X-ray diffraction, DTA/TG and FTIR spectroscopy. The single crystal structure data of SrB₂O₄ shows orthorhombic <i>Pna</i>2₁ symmetry. The structure is built up of linked BO₄ and BO₃ units and the charge is compensated by strontium cations.

O. Plotinskaya, E. Kovalchuk

Co and Ni minerals are described in ores of the Mikheevskoe porphyry copper deposit (South Urals, Russia). Minerals of the cobaltite–gersdorfte series (CoAsS–NiAsS), violarite (FeNi2S4), millerite (NiS), pentlandite (Ni5.5Fe3.4)8.9S8.0 and melonite (NiTe2) are identifed. They overgrow pyrite, chalcopyrite and bornite and belong to late low-temperature assemblages. Cobalt and Ni are also incorporated in pyrite. The latter, being the most widespread mineral of the deposit, is a major carrier of these metals. The variability of Co and Ni minerals is determined by the presence of serpentinites, which replaced ultramafc rocks.

Eusebius J. Kutsienyo, Martin S. Appold, Martha E. Cather

About one million tons of CO₂ have been injected into the Farnsworth unit to date. The target reservoir for CO₂ injection is the Morrow B Sandstone, which is primarily made of quartz with lesser amounts of albite, calcite, chlorite, and clay minerals. The impact of CO₂ injection on the mineralogy, porosity, and pore water composition of the Morrow B Sandstone is a major concern. Although numerical modeling studies suggest that porosity changes will be minimal, significant alterations to mineralogy and pore water composition are expected. Given the implications for CO₂ storage effectiveness and risk assessment, it is crucial to verify the accuracy of theoretical model predictions through laboratory experiments. To this end, batch reaction experiments were conducted to model conditions near an injection well in the Morrow B Sandstone and at locations further away, where the CO₂ has been diluted by formation water. The laboratory experiments involved submerging thin sections of both coarse- and fine-grained facies of the Morrow B Sandstone in formation water samples with varying levels of CO₂. The experiments were conducted at the reservoir temperature of 75 °C. Two experimental runs were conducted, one lasting for 61 days and the other for 72 days. The initial fluid composition used in the second run was the same as in the first. The mineralogy changes in the thin sections were analyzed using SEM and the Tescan Integrated Mineral Analyzer (TIMA), while changes in the composition of the formation water were determined using ICP-AES. During each experiment, a thin layer of white fine-grained particles consisting mainly of dolomite and silica formed on the surface of the thin sections, leading to significant reductions in Ca, Mg, and Sr in the formation water. This outcome is consistent with numerical model predictions that dolomite would be the primary mineral that would react with injected CO₂ and that silica would be oversaturated in the formation water. Changes in mineral abundance in the thin sections themselves were much less systematic than in the theoretical modeling experiments, perhaps reflecting heterogeneities in the mineral grain size surface area to volume ratios and mineral distributions in the thin sections not considered in the numerical models.

Yue Fu, Huizi Wang, Jiang Zhang et al.

Hematite, a ferric mineral with diagnostic features in the visible and infrared spectral range, has recently been discovered in the polar regions of the Moon by the Chandrayaan-1 Moon Mineralogy Mapper (M³). The oxygen involving the oxidization process producing lunar hematite is supposed to originate from the Earth’s upper atmosphere, and hematite with different ages may have preserved information on the oxygen evolution of the Earth’s atmosphere in the past billions of years. The discovery of lunar hematite may provide insight into the understanding of the oxidation products on the Moon and other airless bodies. In this work, we analyze hematite abundance distribution in the lunar polar regions, showing that the content of hematite on the lunar surface increases with latitude, and is positively correlated with surface water abundance. We suggest that the latitude dependence of hematite is derived from the latitude dependence of water, which indicates that water may play an essential role in the formation of hematite. The correlation between hematite and the optical maturity parameter (OMAT) was analyzed and a significant positive correlation was observed, which suggests that the hematite in the polar regions is the result of gradual and persistent oxidation reactions. In addition, based on the analysis of oxygen particles in the Earth wind, it was found that O⁺ and O₂⁺ are much more abundant, suggesting that low-energy O⁺ or O₂⁺ ions escaping from the upper atmosphere of the Earth may play a crucial role in the formation of hematite in the lunar polar regions.

Carlos D. Simões, Vera Aldeias

N. Tribovillard, V. Bout-Roumazeilles, M. Delattre et al.

<p>The Bancs Jumeaux Formation appears as a succession of limestone beds and marly interbeds, of Late Jurassic age (Tithonian), cropping out in the cliffs of the Boulonnais (French shore of the English Channel). This formation is enriched in pyrite present in abundance in the forms of framboids, polyframboids and other concretions of a relatively large size for sedimentary pyrite (a few tens to hundreds of micrometers). Previous works have shown that (poly)framboids appeared during early authigenesis in reducing microenvironments within dysoxic sediments. The question is whether, like what is observed for bacteria causing carbonate mineralization of their outer wall, sulfate-reducing bacteria could have been trapped (locked up) in pyrite “sarcophagi”, induced by their own metabolism. In an attempt to provide answers, the large pyrites were extracted from the Bancs Jumeaux marls by physical separations and acid digests. Their analysis reveals the presence of organic matter in significant quantities. The typical morphology of certain polyframboids present in the studied samples suggests the early fossilization of bacterial colonies by pyrite. If pyrite appears to be a relatively significant trap for organic matter, then pyrite could represent an underevaluated component of the carbon cycle.</p>

Alexander V. Volkov, Ivan A. Novikov, Alexander A. Razumovsky et al.

Object. The article describes a new geological and geochemical data for Permian host rocks and copper sandstones (CS) in Orenburg’s Pre-Urals. Methods . X-ray fluorescence, atomic absorption for Au and Ag, and ICP-MS analysis were used during investigations. Results. The cupriferous sandstones are enriched in a quite broad range of microelements: Cu, Ag, Au, Cd, Сr, Ni, Mn, Co, V, U, Sc, and Pb, compared to the average values of the upper crust. The Co/Ni ratio in the CS is very low, which is typical of low-thermal fluids of meteoric origin. The CS are characterized by a REE spectrum without Eu-minima and maxima, which is close to the chondrite spectrum. Like in the host rocks, the “cerium” group of REE dominates in the CS over the “yttrium” and “scandium” groups. The spectra of REE of the CS and the host rocks have definitely similar morphology. The δCe and δEu combination indicates that CS was formed under oxidizing conditions. On geological and genetic characteristics and geochemical indicators installed the similarity of the CS in the southern Pre-Urals deposits and the Manto-type Cu-Ag deposits of Chile and Iran, and also with the CS of Iran and Cu-shales of Kupferschiefer. Conclusion. Proposed geological-genetic model of CS, points to possible high rise development of the Cu-Ag mineralization at depth as in the fields of the Manto-type copper deposits in Chile and Iran. Geochemical data show that accommodating the Permian strata could serve as a source of REE and other trace elements for ore-forming fluids. Perm CS of Pre Urals can be considered as a very promising new (“old”) source of raw materials for the development of the copper industry of the region. The obtained results can be used to predict new ore fields in the Eastern Russia region.

Gama José, Nyberg Maria

Length-weight relationships (LWRs) and length-length relationships (LLRs) were determined for six fish species: Alburnus alburnus, Blicca bjoerkna, Gymnocephalus cernua, Perca fluviatilis, Rutilus rutilus and Sander lucioperca caught using a Nordic multi-mesh gill net in Lake Kirkkojärvi in Southwestern Finland in August 2015. The measurements were done using a photographic method and the dataset is available on the Comprehensive R Archive Network (CRAN). The dataset was done with a scientific catch, which showed lower limits on specimen size than the ones from fisheries. The LWRs were calculated for the total length (TL) and found to be consistent with models from Finland. The length measurements were taken to the nearest 0.01 cm, which also allowed for juveniles to be represented in the model. The goodness of fit of the models is high, with the coefficients of determination above 95%. This study is the first one to estimate LWRs of fish species for this hypereutrophic lake, and is useful for fishery managers and biologists.

Baghdad Science Journal

Gypsiferous soil deposits (Gypcrete) are weakly consolidate earthy mixture of secondary gypsum, sand and clay. It is formed in arid and semi- arid area with annual precipitation rainfall less than 400mm. These sediments occur in surface and subsurface in region of little rainfall and rapid evaporation. This research deals with the study of gypcrete in Alexandria to improve the mineralogical and geochemical properties of the gypcrete. The gypcrete soil is used as raw material to produce the plaster for building purposes. Three samples of gypcrete were chemically and geochemically analyzed. The common mineral is howed in 0-0.5m Gypsum followed by Calcite in 0-1m and Quartz in 1-1.5m due to leaching and infiltration by rainfall as well as it full the clay Matrix and the voids between soil constituent, therefore soil properties changes with depth and the clay materials increases such as (Al, Na and K oxides) and Gypsum compound decreases (Ca, S and Sr oxides), yet the change in element concentration, takes the same path. This indicate that annual season rainfall is the only factor affecting mineralogy in this arid area and this means that the Gypsum concentration cannot be affected by ground water either increasing or decreasing. This research concerns about mineralogy and element occurrence variation in this material with accordance to their concentration from surface to depth of 1.5 meter.

Ida Inés Pedroso-Herrera

La susceptibilidad magnética de los suelos de la cuenca del río Almendares se tomó como indicador preliminar de la contaminación potencial por metales pesados. Para obtener el esquema de zonación de la contaminación se realizaron mediciones de la susceptibilidad magnética en polígonos y perfiles de áreas potencialmente contaminadas. Se realizó un levantamiento kappamétrico a escala 1: 200 000, usando una red de 2x2 km, y se elaboraron estadísticamente datos de susceptibilidad magnética en suelos contaminados y en los no contaminados por metales pesados. Con base en la nueva versión de la Clasificación Genética de los Suelos de Cuba, los resultados de la elaboración estadística de los datos de susceptibilidad magnética y las concentraciones de metales pesados en muestras de suelo, se establecieron los rangos de susceptibilidad magnética que caracterizan los suelos contaminados en los grupos genéticos presentes en la cuenca. Como resultado se obtuvo el mapa de zonación de la contaminación por metales pesados de la cuenca del río Almendares

Ibrahim A. EL-HEMALY, Mohamed A. ABD ALLA, Igor TÚNYI et al.

The limestone samples of the Eocene to Pliocene age from the pyramids and quarries have been studied by the magnetic methods. It has been revealed that the arsenic containing scorodite mineral is a dominant carrier of magnetic properties in the studied materials. This mineral is of a diamagnetic state in its original form. During its heating the transformation takes place accompanied by the change of magnetic susceptibility. Over the 300 ◦C the transformation of scorodite into maghemite and hematite took place and so the increase of magnetic susceptibility and the intensity of partial thermoremanent magnetization were detected.

Maria Elice Brzezinski Prestes, Frederico Felipe de Almeida Faria

Analisa opiniões do naturalista italiano Lazzaro Spallanzani sobre a origem e a constituição dos fósseis por ocasião de três de suas viagens naturalísticas, entremeadas a três cursos de mineralogia da disciplina de história natural que lecionou na Universidade de Pavia. Essas viagens, para Portovenere, ilha Cerigo e Duas Sicílias, permitiram que abordasse temas importantes, como a descoberta de conchas fósseis no interior de rochas vulcânicas, a de fósseis humanos, e a existência de fósseis de espécies que 'se perderam', incorporando conhecimentos que se desenvolviam na época, com base na química mineralógica. Sua preocupação com os fósseis testemunha o modo como, ao estilo do século XVIII, Spallanzani integrava os estudos dos três reinos da natureza.<br>This article analyzes opinions expressed by Italian naturalist Lazzaro Spallanzani on the origin and constitution of fossils on three of his travels, which punctuated three courses in mineralogy he gave in the natural history discipline at the University of Pavia. These trips to Portovenere, the island of Cerigo and the Two Sicilies enabled him to address important topics, such as the discovery of fossilized shells inside volcanic rocks, the discovery of human fossils, and the existence of fossils of species that had 'been lost', incorporating knowledge being developed at the time that drew on mineral chemistry. His concern with fossils is demonstrative of how Spallanzani, in true eighteenth century fashion, integrated studies from the three kingdoms of nature.

T. Chernet

A. Hall

T. H. C. Nutte, T. Oberth�r, R. Saager et al.

Aral İ. OKAY

Honaz dağı bölgesi üst üste duran tektonik birimlerden oluşmuştur. Batıda, bu tektonik istifin en altında monoton yeşil metaşeylden oluşan yaşı belirsiz Honaz şeyli yer alır. Honaz şeylinin üzerinde tektonik bir dokanakla masif beyaz kireçtaşı ve ince tabakalı çörtlü kireçtaşı ve şeylden oluşan, hafif bir metamorfizma geçirmiş, Menderes masifinin Mesozoyik örtü birimi yer alır. Menderes masifi üzerinde tektonik dokanakla Likya naplarına ait Sandak birimi bulunur. Mesozoyik yaşta dolomit ve kireçtaşından oluşan Sandak biriminin üzerinde ise ofiyolit yer almaktadır. Bütün bu birimler Honaz antiklinali diye adlandırılan, doğuya devrik büyük bir antiklinal oluşturur; Honaz antiklinalinin devrik kanadı altında, tektonik bir dokanakla, Göbecik tepe birimi adı verilen Geç Kretase - Orta/Geç Eosen yaşta pelajik bir sedimanter istif yer almaktadır. Göbecik tepe birimi Honaz dağı bölgesinde nispî otokton birimi teşkil etmektedir. Honaz dağı bölgesindeki birimlerde Geç Kretase, Orta Eosen ve Geç Eosen/Oligosen tektoniğinin izi görülür. Ofiyolitin, Sandak birimi üzerine yerleşmesi muhtemelen Geç Kretasede olmuş, Sandak biriminin Menderes masifi üzerine bindirmesi muhtemelen Orta Eosende, tüm bu birimlerin Göbecik tepe birimi üzerine yerleşmesi ve Honaz antiklinalinin oluşması Geç Eosen/Oligosende meydana gelmiştir.

Karl NEBERT

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