Hasil untuk "Mineralogy"

Flora Vernyuy Wiysanyuy, Bernard Che Ngu, Zerubbabel Akongneh et al.

Abstract The Kribi-Campo Sub-Basin offshore Cameroon represents a significant hydrocarbon province; however, exploration success has historically been hindered by persistent uncertainties regarding reservoir heterogeneity and fluid charge. In the Kribi Batanga Field, these challenges necessitate a more robust characterization framework to mitigate subsurface risk and optimize commercial development. We utilizes a high-resolution Logging While Drilling (LWD) suite to conduct a definitive petrophysical evaluation of five identified reservoir intervals (R1–R5). Lithological identification was rigorously established using Matrix Identification (MID) and neutron-density cross-plots to correct legacy interpretations and distinguish true mineralogy from gas-effect anomalies. The workflow integrated Buckles and Pickett plots to assess fluid mobility and irreducible water saturation. The analysis reveals a distinct hydraulic hierarchy among the reservoirs. Reservoirs R2 (Gas) and R4 (Oil) are identified as premium flow units, characterized by effective porosities of 18–20%, permeabilities exceeding 28 mD, and superior hydrocarbon saturations of 68.46% and 54.52%, respectively. High Net-to-Gross ratios (0.74–0.78) further confirm substantial reservoir continuity in these zones. Conversely, Reservoir R1 is classified as a secondary target with high oil saturation (65.37%) but moderate permeability (5.42 mD) requiring stimulation, while Reservoir R3 presents mobile water risks due to a complex oil-gas contact. Reservoir R5 is characterized as a tight, non-pay basal seal with negligible porosity (2.53%). By accurately identifying the formation as a calcite-dominated limestone sequence, this research provides a corrected geological framework that resolves previous lithological ambiguities. The findings confirm the field’s commercial viability and propose a prioritized development strategy that targets the high-quality oil leg in R4 while maintaining the pressure integrity of the R2 gas cap. This LWD-constrained approach serves as a scalable model for reducing uncertainty in similar carbonate-dominated sub-basins globally.

Ji-In Jung, Mathieu G. A. Lapôtre, Ralph E. Milliken et al.

Visible-to-shortwave infrared (VSWIR) reflectance spectroscopy has revolutionized our understanding of planetary surface compositions. However, space-weathering processes on airless bodies complicate quantitative compositional analyses. Here, we present a framework to isolate the signatures of space weathering in VSWIR spectra of lunar maria by leveraging radiative transfer modeling under the assumptions that (i) a space-weathered target can be expressed as a mixture of fresh and fully space-weathered components and (ii) remaining signatures can be modeled by including agglutinates as an end-member component. We first validate this approach against laboratory spectra of space-weathered Apollo mare soils of known mineral compositions using a probabilistic Markov Chain Monte Carlo implementation of the Hapke radiative transfer model. Second, we illustrate how this approach can be applied to orbital Moon Mineralogy Mapper data. The proposed space-weathering correction workflow for lunar maria could be expanded to other lunar lithologies and applied to existing and future data sets.

Andrey Karpov, Atali Agakhanov

Chabazite-Ca and chabazite-K are found in specimens from the Mariinskoe (Malyshevskoe) deposit (Ural Emerald mines). They form lenticular twins up to 1–2 mm on prehnite. Both zeolites are characterized by an atypically high Cs content: up to 1.20 wt. % Cs2O (0.10 apfu Cs) in chabazite-Ca and up to 0.75 wt. % Cs2O (0.05 apfu Cs) in chabazite-K. In contrast to chabazite-K, chabazite-Ca also contains Sr: up to 1.50 wt. % SrO = 0.15 apfu Sr. Averaged formula is (Ca1.16K0.51Mg0.21Na0.16Sr0.08Cs0.06)(Al3.71Si8.31)O24·11.9H2O for chabazite-Ca (n = 30) and (K1.21Ca0.97Na0.26Mg0.12Cs0.04)(Al3.63Si8.36)O24·12.1H2O for chabazite-K (n = 15). Infrared spectra, X-ray powder diffraction data and calculated unit cell parameters of both minerals are in good agreement with published data for chabazite. Our finding of Cs-bearing chabazite from the Ural Emerald mines is the first in the Urals and likely the second in Russia.

Cancio Jiménez-Lugos, Manuel Flores-Favela, Antonio Romero-Serrano et al.

During the roasting, leaching, and electrodeposition of zinc ores, lead–silver residues are produced. These residues contain valuable metals (Pb, Zn, and Ag) and toxic metals (Cd and As). In this study, a pyrometallurgical process is proposed for treating Pb-Ag residues, consisting of drying, roasting, and reduction steps to recover valuable metals, such as silver in a metallic Pb phase, while converting the waste into an environmentally friendly slag. First, the Pb-Ag residue is dried at 100 °C, then roasted at 700 °C, and finally reduced at a high temperature, with Na₂CO₃ as a flux and CaSi as a reducing agent, rather than carbon-based reducing agents (carbon or carbon monoxide), to minimize greenhouse gas production. The effects of the reduction temperature and the mass of the reducing agent were investigated on a laboratory scale. The metallic phase and slag obtained in the reduction step were characterized by their chemical composition and mineralogy via chemical analysis, X-ray diffraction, and SEM-EDS. The results showed that silver and lead formed a metallic phase, and that silver content decreased from 1700 ppm in the Pb-Ag residue to 32 ppm in the final slag at 1300 °C. The Pb-Ag residue and final slag were leached with an aqueous acetic acid solution to evaluate their chemical stability.

Yane Coutinho, Rennan Medeiros, Leandro Sanchez et al.

The depletion of natural resources and the increasing interest in reducing CO₂ emissions have heightened the demand for alternative materials in concrete production. A viable approach is to lower the clinker-to-cementitious materials ratio by partially replacing clinker with supplementary cementitious materials (SCMs) and/or alternative materials such as aggregate mineral fillers (AMFs). As the availability of SCMs is expected to decline, AMFs have been increasingly explored, including those derived from aggregate processing and susceptible to alkali-aggregate reaction (AAR). However, the behaviour of AAR-reactive AMFs in concrete remains poorly understood. This paper summarizes the current state of the art and identifies knowledge gaps concerning the use of AAR-reactive AMFs, focusing on the roles of mineralogy, particle size, replacement content, and the test methods used to assess AAR-induced development and associated microscopic and mechanical deterioration. A consistent terminology is also proposed to support future research. Finally, a theoretical foundation to understand the role of AAR-reactive AMFs in mortar and concrete is provided, and the key knowledge gaps are discussed.

Ch.M. Khertek, A.M. Sazonov

Native gold from seven placers of the Amyl-Sistighem ore placer region (the Republic of Tyva, Krasnoyarsk region) is classifed on the basis of its structure, morphology and chemical composition, which are studied by optical and electronic microscopy. Three chemical types of native gold are identifed: Ag-Au, Hg-Ag-Au, Cu-Ag-Au. There are rounded and angular particles with and without a high-fneness rim. Seventeen types of native gold are established on the basis of combination of various characteristics. These varieties characterize the mineralogical-geochemical types of primary ores, the distance of the transportation of clastic material, the degree of mechanogenic and crystallophysical deformations of gold particles, and the duration of their occurrence in a gold-bearing layer under relatively calm conditions. Our results can be used in planning thematic pre-project and prospecting-assessing work at this territory, whereas methodological issues can be applied in other gold placer areas.

R. Vigliaturo, R. Vigliaturo, G. P. Servetto et al.

<p>The current climate emergency and the related energy transition require the development of technology producing zero-carbon energy. One viable option entails the utilization of recyclable metal fuels. The primary energy stored by the reduction in metal oxides can be transported and later released by metal combustion. Mg is among the most promising metal as a regenerable energetic vector, having an energy density of 25 MJ kg<span class="inline-formula">⁻¹</span>. The exploitation of the Mg oxidation and reduction loop has recently been demonstrated, and the loop combustion products are made of metal oxides. The mineralogical characterization of the MgO crystals generated by the Mg combustion is of utter importance for the optimization of the particle trapping capacity in the combustion system during the closed oxidation and reduction loop. In this paper we characterize MgO particles generated in a swirl-stabilized Mg flame by using powder X-ray diffraction, transmission electron microscopy and selected area electron diffraction, and atomic-resolution microscopy combined with energy-dispersive X-ray spectroscopy and dual-electron energy-loss spectroscopy. The MgO combustion products were chemically homogeneous at this level of investigation. Three representative morphologies (cubic, truncated octahedron, and spherical) and two isostructural phases were identified in the MgO combustion product. These findings may contribute to the optimization of system development, particularly in terms of the collection efficiency of the combustion end product.</p>

Alexander A. Kremenetsky, Igor G. Spiridonov, Alexey G. Pilitsyn et al.

The project of organizing mineral-and-energy clusters with spatial conjugation of deposits of solid minerals (SM) and hydrocarbons (HC) localized on the continental margin and shelf of the Arctic zone of the Russian Federation is substantiated. Four clusters of the kind are characterized, i.e.: Murmansk-Barents, Yamal-Norilsk, Lena-Laptev Sea and Northeast-Chukotka, with the corresponding characteristics of the SM and HC resource bases, as well as substantiation of the bedrock gold and porphyry copper prospective areas in the Northeast-Chukotka cluster. An example of prediction and localization of the HC accumulations in the deep-water part of the Arctic Basin outside the 200-mile zone of the Russian shelf is considered. Geological and morphostructural evidence of the epicontinental nature of the bottom of the Amerasian and Eurasian basins is presented as a criterion for substantiating Russia's right to expand the outer boundary of the continental shelf.

TONG Yan-mei, ZHANG Hu-yuan, ZHOU Guang-ping et al.

During the operation of underground repository of high-level radioactive waste, the highly alkaline solution generated by groundwater corroding lining concrete will diffuse into the bentonite buffer barrier, resulting in the degradation of barrier property. The KOH solution with different pH values was used to simulate the alkaline solution, and a one-year contact diffusion test at room temperature was conducted. Then, X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometry (EDS) were performed to investigate the effect of slow diffusion on the mineralogy of bentonite. The XRF test results show that when the pH of KOH solution was greater than 12.6, the content of silicon began to decrease, that is, montmorillonite, quartz, cristobalite and other Si-containing minerals in bentonite were dissolved. At the same time, the content of K increased, indicating that the bentonite had an ion exchange reaction with the alkaline solution, a large amount of K+ ions in the solution entered the montmorillonite crystal layer. The XRD test results show that the 001 peak of montmorillonite mineral started to shift to the right at pH=12.6, the peak widths widened, and the peak intensity reduced considerably. When the pH>13, the crystal interlayer space decreased from 1.385 3 nm (13.853 Å) to 1.221 0 nm (12.210 Å), indicating that the crystal layer of montmorillonite was compressed. With the increase of the pH value, the content of minerals such as montmorillonite and quartz decreased significantly, and the contents of illite, clinoptilolite and feldspar minerals increased slightly. The SEM test results show that part of the montmorillonite crystal layer overlapped with the pH of the solution increasing, and then some cracks and holes were generated. As a result, the cracks can accelerate the dissolution of montmorillonite. In the one-year contact diffusion test, the diffusion depth of the KOH solution with pH=13.8 exceeded 7.5 mm, and the newly formed illite crystallites were observed on the contact surface between the alkaline solution and the bentonite. It is confirmed that the strong alkaline solution will cause montmorillonite dissolution and illitization.

S. I. Shkolnik, E. F. Letnikova, L. Z. Reznitsky

There have been presented the results of the study of a thick (no less than 2–3 km), extended (for more than 200 km) volcanogenic formation (Tsetsen-Uul or Yargait) in the south of the Zavkhan terrane of the Central Asian fold belt. The formation is an assemblage of frequently intercalating effusive rocks of the subalkaline basalt-andesite-dacite-rhyolite series, their tuffs, tuffites, ignimbrites, and terrigenous rocks. Felsic rocks dominate over basites, and tuffogenic rocks dominate over effusives. There is some evidence that the formation emerged in a subaerial setting, with explosive eruptions, and the petrogeochemical features of the effusive rocks are typical for subduction environment. The felsic effusive rocks have high negative εNd from –11.5 to –12.8 and Early Precambrian model age TNd(DM)=2.4–2.5 Ga, which indicates the presence of an ancient crust at the depth and its involvement in magma. The evidence supports the formation of volcanic rocks within an active continental margin. The continental-margin formation stage ranges from ~860 Ma to ~780 Ma based on the LA-ICP-MS U-Pb dating of zircons.The Tsetsen-Uul (Yargait) formation is similar in structure and composition to the Zavkhan formation of the Zavkhan terrane and the Sarkhoi group of the Tuva-Mongolian massif, and partially overlaps them in formation time. It is concluded that all three volcanogenic formations emerged in the same geodynamic setting and in the same time interval, and are the fragments of a continental volcanic arc belonging to both Zavkhan and Tuva-Mongolian paleomicrocontinents.

Selin Bi̇lgi̇ç Gençer, Sibel Tatar Erkül, Fuat Erkül

Volcanism that has been active since the early Miocene along a N-S trending line from Eskişehir to Isparta displays calc-alkaline and alkaline character and is closely associated with slab tearing processes. However, the geodynamic setting of these volcanic units between Afyon and Emirdağ is still poorly known. In this study, petrological characteristics of the Emirdağ and İscehisar volcanic units have been investigated using petrography, whole-rock geochemistry and Sr-Nd isotopes. The Emirdağ and İscehisar volcanic units overlap the SeydileIgnimbrites. The Emirdağ volcanic unit is trachyandesite and the İscehisar volcanic unit is trachyte, basaltic trachyandesite and trachydacite in composition. The Emirdağ volcanic unit displays calc-alkaline character, while the İscehisar volcanic unit is alkaline but the rocks from both the units have shoshonite character defined by their high K2O contents. The Emirdağ volcanic unit has 87Sr/86Sr ratios of 0.706790-0.706284 and 143Nd/144Nd ratios of 0.512472-0.512463, while these ratios in the İscehisar volcanic unit are of 0.707650-0.706527 and 0.512464-0.512424, respectively. Data revealed by this study indicate that these volcanic units were affected by crustal contamination, fractional crystallization and magma mixing. Rising of asthenosphere in the region due to the extensional regime in the Early Miocene appears to have caused formation of volcanism that pass from calc-alkaline to alkaline in character. The Emirdağ and İscehisar volcanic units are the products of the volcanism that developed in the late stages of southward slab roll-back and in the extensional regime prior to the slab tearing event.

Vendula Davidová, Pavel Reiterman

Autogenous shrinkage of cement based composites is important property influencing number of their engineering application. Its ultimate value is predominantly determined by mineralogical composition of cement and its particle size distribution. Present paper introduces experimental study focused on the evaluation of various cements of grade CEM I 42.5 produced in Czech Republic in terms of shrinkage under autogenous conditions. Selected cement type is currently the most frequently used cement. Conducted study confirmed essential differences in ultimate values of shrinkage, which is partially determined by its specific surface area. Accompanying tests of mechanical properties indicate the influence of particle size distribution, which controls initial phases of cement hydration.

Šarinová Katarína, Rybár Samuel

Within the framework of reinterpretation of the depositional evolution of the Komjatice depression, presence of cummingtonite in weakly lithified sediment has been detected. The sediment is formed by volcanic lithoclasts and phenocrysts with a small admixture of non-volcanic grains. The different mineral composition and various degrees of alteration of volcanic lithoclasts, together with structural features point to epiclastic origin. Therefore, the studied samples can be described as volcanic paraconglomerate and sandstone. The cummingtonite is found in rusty coloured volcanic lithoclasts and in the heavy fraction. Cummingtonite-bearing volcanic rocks have not been described so far from the Slovak Neogene volcanic fields. Therefore its presence in the studied samples represents the first indication of such volcanic rock in Slovakia. The aim of the article is to invoke interest for finding these volcanic rocks in situ.

Eleonora Agustine

Abstrak Kajian penggunaan pestisida pada lahan pertanian perlu dilakukan karena penggunaannya yang terus menerus dalam jangka waktu yang lama akan berakibat pada masalah kesehatan masyarakat dan lingkungan. Pada paper ini kajian dilakukan di tanah vulkanik di PTPN VIII Bukit Tunggul Jawa Barat.  Untuk mengamati perubahan yang terjadi pada tanah vulkanik akibat pengaruh pestisida pada penelitian ini akan dilakukan kajian mineralogi dan  morfologi bulir magnetic menggunakan Scanning Electron Microscope (SEM). Conto diambil pada outcrop sebanyak  60 contoh dari dua lapisan yang berbeda sifat fisiknya. Conto dibagi menjadi 3 grup berbeda untuk diamati perubahannya setiap 3 bulan. Grup pertama conto standar (tanpa penambahan pestisida), grup ke dua diberi pestisida dengan variasi 5 ml pestisida ditambah aquabidest 45 ml, 10 ml pestisida dan 40 ml aquabidest sampai 50 ml murni pestiseda. Masing-masing contoh diberi 5 tetes. Grup kedua disimpan selama 3 bulan dan diamati hasilnya, demikian pula grup ke tiga disimpan 6 bulan. Dari hasil pengamatan bulan terlihat bahwa pengaruh pestisda merusak bulir magnetik yang ada, dan membuat bulir menjadi lebih halus. Dan proses penghalusan bulir magnetik ini diduga akibat disolusi atau oksidasi. Kata-kata kunci: Pestisida, tanah volkanik, morfologi bulir Abstract Study of the use of pesticides on agricultural land necessary for continuous use in the long term will result in environmental and public health problems. In this paper, a study carried out in volcanic soil in PTPN VIII West Java Bukit stumps. To observe the changes that occur in volcanic soils due to the effect of pesticides on the study will examine the mineralogy and morphology of magnetic grains using a Scanning Electron Microscope (SEM). Outcrop samples were taken on as many as 60 instances of two layers of different physical properties. Conto is divided into 3 different groups to observe the changes every three months. The first group of samples, standard (without the addition of pesticides), the second group was given pesticide with a variety of pesticides plus 5 ml aquabidest 45 ml, 10 ml and 40 ml pesticide aquabidest to 50 ml of pure pestiseda. Each sample was given five drops. The second group is stored for 3 months and observed the results, as well as a group to three stored 6 months. From the observation moon is seen that the influence of the magnetic grains pestisda existing damage, and make the grain becomes finer. And the process of refining grains of magnetic allegedly due to dissolution or oxidation. Keywords: Pesticides, volcanic soil, grain morphology

Alireza ALMASİ, Alireza JAFARİRAD, Peyman AFZAL et al.

Bu çalışmanın amacı, KB İran, Saqez Bölgesi’ndeki, orojenik altın prospeksiyon sahasının haritalanmasıdır. Bu işlemi başarmak için, jeolojik, jeokimyasal ve havadan jeofizik veriler analiz edilmiş ve indeks overlay ve bulanık mantık (fuzzy logic) yöntemleri entegre edilmiş- tir. Saqez bölgesinin jeoloji haritası (1:100.000 ölçekli), litolojik ağırlık değerlerinin belirlenmesi amacıyla kullanılmış olup, burada, birimlerin özellikle orojenik Au cevherleşmesi içermesi yönünden yatkınlığı göz önünde bulundurulmuştur. Ayrıca, jeoloji haritasındaki yapısal unsurlar temel alınarak bir fay yoğunluk haritası da üretilmiştir. Jeokimyasal kanıt haritalarını hazırlamak için 535 adet dere kumu örneğinden elde edilen veriler sayı-boyut çoklu-fraktal (Number-Size multi-fractal, N-S) yöntem kullanılarak Au, As, Bi ve Hg elementleri için değerlendirilmiştir. Tespit edilen eşik değerler, dere kumu örneklerinin su toplama havzasını belirlemek için kullanılmaktadır. Aeromanyetik veriler, gelişmiş kenar saptama yöntemi temel alınarak, manyetik anomalilerin kenarlarını tespit etmek için kullanılmıştır. Ayıklanan çizgisellikler, daha sonra yoğunluk haritasına dönüştürülmüştür. Havadan radyometrik veriler de iki kanıt harita oluşturmak için kullanılmıştır. Potasyum ayrı olarak grid sayılmış ve K/Th oran haritası hidrotermal aktivitenin olduğu lokasyonları belirlemek için oluşturulmuştur. Sonuç olarak, kanıt haritaların bütünleştirilmesiyle, bulanık mantık prospeksitivite haritasıyla önceden tespit edilmiş olan Au bulguları da (Qolqoleh, Kervian ve Ghabaghloujeh) dikkate alınarak, yüksek Au cevherleşmesi içeren yeni lokasyonlar belirlenmiştir.

Majkić-Dursun Brankica, Vulić Predrag, Dimkić Milan

The formation of incrustations on public water supply well screens reduces their performance considerably. The incrustations increase hydraulic losses, reduce the capacity of the well and screen, affect the quality of the pumped water and increase maintenance costs. In alluvial environments, the most common deposits are iron and manganese hydroxides. However, the rates of formation, compositions and levels of crystallization vary, depending on the geochemical characteristics of the alluvial environment, the microbiological characteristics of the groundwater and the abstraction method. Samples of 15 incrustations were collected from wells that tap shallow alluvial aquifers and were found to be dominated by iron. XRD analyses detected low-crystalline ferrihydrite and manganese hydroxide in the samples collected from the water supply source at Trnovče (Velika Morava alluvial). The incrustations from the Belgrade Groundwater Source revealed the presence of ferrihydrite and a substantial amount of goethite α-FeOOH. Apart from goethite, greigite (Fe3S4) was detected in three samples, while one sample additionally contained bernalite Fe(OH)3 and monoclinic sulfur S8. Among carbonates, only siderite was detected. Iron oxidizing bacteria generally catalyze deposition processes in wells, while sulfate reducing bacteria (SRB) play a role in the biogenic formation of greigite. Determining the nature of the deposited material allows better selection of rehabilitation chemicals and procedure. [Projekat Ministarstva nauke Republike Srbije, br. TR37014]

A. D. Edgar, H. E. Charbonneau

S. Takeno, G. H. Moh

P. Bonazzi, L. Bindi, F. Olmi

H. Tahsin AKTİMUR, Şerafettin ATEŞ, M. Emin YURDAKUL et al.

Niksar, Erbaa ve Destek dolayını kapsayan ve Kuzey Anadolu Fay zonu tarafından katedilen çalışma alanının temelini Permo-Triyas yaşlı Turhal grubu metamorfitleri oluşturur. Temel üzerine Liyas-Üst Eosen zaman aralığında çökelmiş olan istif gelmektedir. Bu çökel paket Avrasya kıtası önündeki çukurlukta çökelmiştir. Çalışma alanı Avrasya plakası ile Anadolu plakasının kenet kuşağında yer aldığından kuzey-güney yönlü sıkışmanın etkisinde kalmıştır. Bundan dolayı bölgede doğu-batı gidişli bindirmeler oluşmuştur. Neotektonik dönemde Kuzey Anadolu Fayının oluşması ve gelişmesine bağlı olarak meydana gelen çukurluklarda Pliyosen yaşlı karasal kırıntılılar çökelmiştir. Kuzey Anadolu Fayının sonraki hareketleri ile Niksar, Erbaa-Taşova ovaları çek-ayır (pull-apart) havzalar olarak gelişmiştir. Bu havzaların gelişmeleri günümüzde de devam etmektedir.