Hasil untuk "Mineralogy"

A. Oganov, S. Ono

The Earth's lower mantle is believed to be composed mainly of (Mg,Fe)SiO3 perovskite, with lesser amounts of (Mg,Fe)O and CaSiO3 (ref. 1). But it has not been possible to explain many unusual properties of the lowermost ∼150 km of the mantle (the D″ layer) with this mineralogy. Here, using ab initio simulations and high-pressure experiments, we show that at pressures and temperatures of the D″ layer, MgSiO3 transforms from perovskite into a layered CaIrO3-type post-perovskite phase. The elastic properties of the post-perovskite phase and its stability field explain several observed puzzling properties of the D″ layer: its seismic anisotropy, the strongly undulating shear-wave discontinuity at its top and possibly the anticorrelation between shear and bulk sound velocities.

Zhifei Liu, Yulong Zhao, C. Colin et al.

Zilong Wang, Wei Tian, Wei-RZ Wang et al.

Abstract There is ongoing debate about whether lunar magnesian suite (Mg-suite) magmatism was a global, nearly synchronous event with a genetic link to potassium, rare-earth element and phosphorus components (KREEP). Arguin 002, the first whole-rock meteorite classified as a lunar norite, offers a unique opportunity to explore the genesis and timing of Mg-suite rocks. Here we investigated the petrology, mineralogy, geochemistry, and chronology of Arguin 002, revealing it to be an evolved, KREEP-free Mg-suite rock with chemical similarities to atypical Apollo-15 Fe-norites. It likely formed through plutonic magmatism originating from low-degree partial melting of a deep, KREEP-free mantle source and has a 207Pb/206Pb age of 4341.5  ± 9.3 Ma. The potential source of Arguin 002 is within the South Pole-Aitken basin, near the Chang’e-6 landing site. These findings indicate that Mg-suite magmatism was a global and nearly synchronous event, potentially driven by rapid global mantle overturn.

Lisset Martínez-Bring, Giorvys Ramón Cuza-Fernández, Luis Alberto Pérez-García et al.

Los suelos lateríticos ferrosos de Moa son de baja productividad agrícola. El presente trabajo tuvo el objetivo de evaluar la aplicación de agrominerales y mejoradores de suelos, a partir de tres experimentos realizados en dos organopónicos de la localidad.  Se aplicaron formulaciones a base de tobas zeolitizadas cargadas con residual amoniacal y calcilutitas en cultivos de pepino y habichuela, y formulaciones a base de tobas zeolitizadas cargadas con residual amoniacal y mezcladas con tobas vítreas, en cultivos de pepino. Las formulaciones lograron incrementar el rendimiento de la habichuela y del pepino variedad Puerto Padre evidenciando la viabilidad del uso de este agromineral. Los resultados contribuyen a la sostenibilidad ambiental y fomentan la adopción de prácticas más sostenibles.

Alaa El-Din Hamid Sayed, Rashad E. M. Said, Mohamed Abd El-Aal et al.

Abstract In Egypt, while many studies have focused on the radiometry and mineralogy of black sands, research on their effects on nearby aquatic organisms is rare. This study aimed to assess the combined effects of heat stress (HS) and black sand nanoparticles (BS-NPs) on renal function, antioxidant responses (TAC, SOD, CAT), neuro-stress indicators (AchE, cortisol), and to conduct histopathological investigations in the kidney and spleen tissues of African catfish Clarias gariepinus over a 15-day period to exposure to control, HS (32 °C), BS (6.4 g/kg diet) and HS + BS groups. The outcomes revealed that thermal stress alone showed no significant difference from the control. However, creatinine and uric acid levels were significantly higher in the BS-NPs and HS + BS-NPs groups (p < 0.001). Antioxidant markers (TAC, SOD, and CAT) were substantially reduced across all treated groups (0.05 ≥ p < 0.0001). AchE levels were significantly elevated in BS-NPs and HS + BS-NPs (p < 0.001), while cortisol levels were higher in these groups but not significantly different in HS. Degeneration and necrosis in the white and red pulps, scattered lymphocytes, and increased collagen fiber surrounding blood vessels and the lining of the ellipsoid structure were all evident in the spleen, along with the enlargement of the melanomacrophage centers with big granular, irregular, and brown pigments (hemosiderin). Our study, therefore, provides new insights into how heat stress, an abiotic environmental factor, influences the toxicity of black sand nanoparticles in catfish.

Sergey V. Yudintsev, Maximilian S. Nickolsky, Michael I. Ojovan et al.

The structural and chemical properties of zirconolite (ideally CaZrTi₂O₇) as a host phase for separated REE–actinide-rich wastes are considered. Detailed analysis of both natural and synthetic zirconolite-structured phases confirms that a selection of zirconolite polytype structures may be obtained, determined by the provenance, crystal chemistry, and/or synthesis route. The production of zirconolite ceramic and glass–ceramic composites at an industrial scale appears most feasible by cold pressing and sintering (CPS), pressure-assisted sintering techniques such as hot isostatic pressing (HIP), or a melt crystallization route. Moreover, we discuss the synthesis of zirconolite glass ceramics by the crystallization of B–Si–Ca–Zr–Ti glasses containing actinides in conditions of increased temperatures relevant to deep borehole disposal (DBD).

Behrooz Amiri, Seyed Vahid Shahrokhi

The Tangedozdan area is located in the west of Isfahan province and 25 km northeast of Fereydounshahr. Structurally, this area is located in the Sanandaj- Sirjan zone. The rock units include greenish volcanic rocks, lime-sandstone, limestone to dolomitic-limestone, conglomerate, sandy-limestones and present-age alluviums. The existing rock sequence along with zinc and lead mineralization has been affected by tectonic phenomena, in the form of thrusting and the formation of open folds, joints and fractures. The main geological structures include thrust plates that have pushed scales of Jurassic and Cretaceous rock units from the northeast to the southwest on top of each other. The folding structures are very small and dense size and are mainly related to faults that have affected the rock units, especially thin-bedded limestone. Tectonic studies show the influence of two lateral faults with the NW-SE trend and a concentrated fault zone inside the dolomitic rocks in the mineralization process. Zinc and lead mineralization shows more expansion in the tension zones. Mineralogy, geochemistry and, EPMA studies indicate the presence of calamine and a small amount of zincian dolomite. The limestone to dolomitic-limestone rocks hosts zinc and lead mineralization and consists of lenses, non-sulfide minerals veins and, veinlets such as smithsonite, hemimorphite, cerussite and, barite, sulfide minerals such as sphalerite and galena. The dolomitization phenomenon due to the effects of acidic hydrothermal fluids has caused alteration of the carbonate wall rock. The structural factor is the main reason for the formation of this dolomite type and the replacement of magnesium with zinc. Introduction High tectonic energy causes shear structures by deforming the crust (Ramsay and Huber, 1987; Lawrence, 2010; Peacock, 1992; Montest and Hirth, 2003). Different temporal and spatial distribution of mineral resources is the result of crustal orogenic actions during tectonomagmatic terms related to specific crust zones. (Aghanabati, 2006; Nabatian et al., 2015). Carbonate rocks under appropriate geodynamic conditions with specific platforms are potential hosts of lead and zinc resources (Rajabi et al., 2012a; Rajabi et al., 2012b; Amiri, 2017; Karimpour et al., 2019). Accordingly, in this we attempt to investigate the relationship between the structure and mineralization and provide a model for structural formation. The Tangedozdan zinc and lead mine 25km northeast of Fereydounshahr is located in the extreme western corner of Isfahan Province and adjacent to the Lorestan Province. For the geological location, this area is considered part of the Sanandaj-Sirjan zone. The limestone unit in the east of Tangedozdan hosts zinc carbonate mineralization. In this region, the mineralization is located between two faults inside the dolomite limestone concentrated directly on the trachyandesite volcanic rocks. Materials and methods To accurately identify the minerals, thin-polished sections were prepared from the surface, boreholes, and trenches and studied by transmitted and reflected polarization microscope (Nikon E200). Also, many samples were studied by XRD and EPMA. Result The Tangedozdan zinc-lead mine includes rock units in the convergent and active margin of the neotethys Ocean in the Mesozoic. These rocks were formed in an eugeocynclinal medium during the Jurassic and early Cretaceous periods (Aghanabati, 2006). Tectonic phenomena, in the form of thrusting and the formation of open folds, joints, and fractures, are considered mineralogy controllers. Two important and major faults related to mineralization have been identified in Tangedozdan. The first fault at a distance of about 650m to the east of Tangedozdan and along the general direction of N158 caused contact between sandy limestone deposits and calcareous sandstone, and the fault has played an important role in mineralization. The second fault, at a distance of about 450 m to the east of Tangedozdan, with the general direction of N150, along with the past fault, has played an important role in mineralization, and together with the sub-faults, they are considered to be structural controllers of mineralization. Mineralogical studies as well as the use of EDS spectra and XRD have shown presence of non-sulfide minerals such as smithsonite, cerussite, hemimorphite, barite, and sulfide minerals such as sphalerite and galena, which are paragenesis of each other. The transparent minerals are calcite and dolomite and barite and Quartz to a lesser extent, which are placed in the space between the opaque minerals. Quartz is mainly observed heterogeneously and only in some empty spaces. The formation of empty spaces between the crystals and the fractures is the result of the dolomitization phenomenon and it has made possible the concentration of ore-bearing fluids and the deposition of valuable zinc and lead ores. Hence, mineralization can be expected in parts of the deposit where developing dolomitization and creating empty spaces is possible. Calamine is very similar to carbonate minerals such as dolomite and calcite and has a variety of colors (Wilkinson, 2014; Lecumberri-Sanchez et al., 2014). Therefore, in Tangedozdan, the two-component reagent Zinc Zap was used, which qualitatively shows the presence of zinc-bearing minerals and leads to red and orange colors to identify calamine or non-sulfide minerals that cover zinc and primary sulfide minerals. Accordingly, calamine was identified in field studies in Tangedozdan. The most important existing alteration includes dolomite, silicic, and carbonate, which can be seen with non-sulfide zinc mineralization such as calamine, and zincian dolomite, which is considered an important sign of mineralization in the region. The dolomitization phenomenon due to the effect of acidic hydrothermal fluids has altered the carbonate wall rock. The structural factor is the main reason for the formation of this type of dolomite and the replacement of magnesium with zinc (Boni et al., 2011; Mondillo et al., 2017). Discussion Given field evidence, it can be said that zinc and lead have mineralized simultaneously with the faults with the current mechanism of normal dip-slip along with strike-slip component with the general direction of N150 to N158. Then, with penetration of fluids containing zinc and lead, mineralization has taken place along the existing faults and their sub-faults as mineralization structural controllers. According to the studies, the dolomitized process has led to the formation of empty spaces between the crystals as well as fractures and finally the concentration of ore fluids and deposition of valuable zinc and lead ores. The phenomenon of dolomitization has also changed the carbonate wall rock.

Maged El-fakharany, Ahmed Omar, Mahmoud Abdellatif

Egyptian Eastern Desert is rich in many areas that contain granites masses throughout the geological era; some of them show good characteristics of the rock hardness, durability, density and mineralogy. This current research aims to utilize three main types of granite aggregates based on their mineralogical composition and Alkali reactivity with cement during concrete production. The studied granite aggregate can be also classified into red younger granite aggregate, white older granite aggregate and grey older granite aggregate. Evaluating these granite rocks as aggregate used in concrete mixture is interesting by produced three mixes using the three studied granite aggregate symbolized (Red GA), (White GA) and (Grey GA), tested mechanically to give a more detailed for the obtained results to be not restricted for only studied granite aggregate criteria but also to follow the actual reaction of this studied granite aggregate with cement.   It was obtained that all studied granite aggregates within acceptable limits of concrete aggregate by following Egyptian code (ECP-203) although their variation on its mineralogical composition. Some reflections produced from change in mineralogical composition between the three studied granite aggregates exhibited by relative regression in the average physico-mechanical values for both (White and Grey GA) than (Red GA). On the other hand, slight reactive for (Red GA) than others at the age of 28 day. In addition, all produced (Red GA), (White GA) and (Grey GA) mixes were acceptable mechanically with limits of (ECP-203) giving benefit for using all of the studied granite aggregate after their detailed study involving its mineralogical composition and alkali aggregate reactivity (AAR).

Aleksei Chepurov, Valeri Sonin, Dmitry Shcheglov et al.

The study of diamond surfaces is traditionally undertaken in geology and materials science. As a sample material, two natural diamond crystals of type Ia were selected, and their luminescence and nitrogen state was characterized. In order to etch the surface catalytic hydrogenation was performed using Fe particles as an etchant. Micromorphology of the surface was investigated by scanning electron and laser confocal microscopy. It was demonstrated that etching occurred perpendicular to the crystal surface, with no signs of tangential etching. The average depth of caverns did not exceed 20–25 μm with a maximal depth of 40 μm. It is concluded that catalytic hydrogenation of natural type Ia diamonds is effective to produce a porous surface that can be used in composites or as a substrate material. Additionally, the comparison of results with porous microsculptures observed on natural impact diamond crystals from the Popigai astrobleme revealed a strong resemblance.

N. Nagatsuka, K. Goto-Azuma, K. Goto-Azuma et al.

<p>Our study is the first to demonstrate a high-temporal-resolution record of mineral composition in a Greenland ice core over the past 100 years. To reconstruct past variations in the sources and transportation processes of mineral dust in northwestern Greenland, we analysed the morphology and mineralogical composition of dust in the SIGMA-D ice core from 1915 to 2013 using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results revealed that the ice core dust consisted mainly of silicate minerals and that the composition varied substantially on multi-decadal and inter-decadal scales, suggesting that the ice core minerals originated from different geological sources in different periods during the past 100 years. The multi-decadal variation trend differed among mineral types. Kaolinite, which generally formed in warm and humid climatic zones, was abundant in colder periods (1950–2004), whereas mica, chlorite, feldspars, mafic minerals, and quartz, which formed in arid, high-latitude, and local areas, were abundant in warmer periods (1915–1949 and 2005–2013). Comparison to Greenland surface temperature records indicates that multi-decadal variation in the relative abundance of these minerals was likely affected by local temperature changes in Greenland. Trajectory analysis shows that the minerals were transported mainly from the western coast of Greenland in the two warming periods, which was likely due to an increase in dust sourced from local ice-free areas as a result of shorter snow/ice cover duration in the Greenland coastal region during the melt season caused by recent warming. Meanwhile, ancient deposits in northern Canada, which were formed in past warmer climates, seem to be the best candidate during the colder period (1950–2004). Our results suggest that SEM–EDS analysis can detect variations in ice core dust sources during recent periods of low dust concentration.</p>

V.A. Popov, M.A. Rassomakhin, S.V. Kolisnichenko

A large crystal of the rarest mineral polyakovite was discovered in 2019 in the carbonatitespegmatites of pit № 97 of the Ilmeny Mountains. Bodies of carbonatites, glimmerites, glimmeritespegmatites and carbonatite-pegmatites are located within a small complex body of alkaline ultramafites and carry a unique range of mineral assemblages (rocks), as well as rare-metal and REE minerals, which is unique for this famous mineral province.

Flerov G.B., Churikova T.G., Gordeychik B.N. et al.

The Ziminy Sopki Volcanic Massif is remarkable for its co-formation from magmas of different potassium alkalinity manifested by three rocks associations (series) with individual evolutional trends: I — andesite-basalts — andesites — dacites; II — andesite-basalts — the intermediate composition andesites; III — high potassium andesite-basalts. Variations of rocks from the revealed series manifest themselves in the above mentioned mineral associations, and the discreteness of rocks regression lines evidence on quite autonomous parental magmas. Orthogonal trends of minerals composition alterations in andesite-basalts with the vector correlating with the potassium alkalinity increase in rocks of associations evidence on existence of the process leading to the enrichment of these magmas with potassium. Thus, we can conclude that, within the single penetrated magmatic system, there are deep intermediate chambers with different conditions for formation of the initial andesite-basalt magmas, which during volcanic activity directly associated with the deeper parental basaltic magma.

Bedartha Goswami, Niklas Boers, Aljoscha Rheinwalt et al.

Most time series techniques tend to ignore data uncertainties, which results in inaccurate conclusions. Here, Goswami et al. represent time series as a sequence of probability density functions, and reliably detect abrupt transitions by identifying communities in probabilistic recurrence networks.

O. A. Gavryushkina, A. V. Travin, N. N. Kruk

In large igneous provinces (LIP) of fold areas, granitoid rocks are dominant, while mantle-derivated rocks play a subordinate role in rock formation. If magma emissions are impulsive, it may take 25–30 million years for a LIP to form and take shape. In this paper, we present the results of 40Ar/39Ar isotopic studies of Permian-Triassic grani­toids in the Altai region, Russia, and clarify the evolution of this region located at the periphery of the Siberian LIP. These granitoids are very diverse and differ not only in their rock set, but also in the composition features. In the study region, the granodiorite-granite and granite-leucogranite association with the characteristics of I- and S-types as well rare metal ore-bearing leucogranites are observed along with gabbro- and syenite-granite series, including mafic and intermediate rocks with the A2-type geochemical features. The 40Ar/39Ar data obtained in our study suggest that most of the studied granitoids intruded within a short period of time, 254–247 Ma. This timeline is closely related to the formation of granitoids in theKuznetsk basin and dolerite dikes in the Terekta complex (251–248 and 255±5 Ma, respectively), as well as intrusions of lamproite and lamprophyre dikes of the Chuya complex (245–242 and 237–235 Ma). Thus, we conclude that the Altai Permian-Triassic granitoids are varied mainly due to the evolution of mafic magmatism.

T. B. Kristensen, T. Müller, K. Kandler et al.

Cloud optical properties in the trade winds over the eastern Caribbean Sea have been shown to be sensitive to cloud condensation nuclei (CCN) concentrations. The objective of the current study was to investigate the CCN properties in the marine boundary layer (MBL) in the tropical western North Atlantic, in order to assess the respective roles of inorganic sulfate, organic species, long-range transported mineral dust and sea-salt particles.<br><br> Measurements were carried out in June–July 2013, on the east coast of Barbados, and included CCN number concentrations, particle number size distributions and offline analysis of sampled particulate matter (PM) and sampled accumulation mode particles for an investigation of composition and mixing state with transmission electron microscopy (TEM) in combination with energy-dispersive X-ray spectroscopy (EDX).<br><br> During most of the campaign, significant mass concentrations of long-range transported mineral dust was present in the PM, and influence from local island sources can be ruled out. The CCN and particle number concentrations were similar to what can be expected in pristine marine environments. The hygroscopicity parameter <i>κ</i> was inferred, and values in the range 0.2–0.5 were found during most of the campaign, with similar values for the Aitken and the accumulation mode. The accumulation mode particles studied with TEM were dominated by non-refractory material, and concentrations of mineral dust, sea salt and soot were too small to influence the CCN properties. It is highly likely that the CCN were dominated by a mixture of sulfate species and organic compounds.

C. Dennison, A. El Ghazouani, H. M. Talbot et al.

Controls on in situ methanotroph activity are not well understood. One potentially important parameter is copper (Cu) because it is the metal-centre of particulate methane monooxygenase (pMMO), the most active enzyme for oxidizing methane to methanol. Further, Cu-to-cell ratios influence the relative expression of pMMO versus the alternate soluble MMO (sMMO) in some species. However, most methanotroph studies only have assessed readily soluble forms of Cu (e.g. CuCl₂) and there is a dearth of Cu-related activity data for Cu sources more common in the environment. Here we quantified sMMO activity (as a practical indicator of Cu availability) and growth kinetics in <i>Methylosinus trichosporium</i> OB3b, an organism that expresses both pMMO and sMMO, when grown on Cu-minerals with differing dissolution equilibria to assess how mineral type and methanobactin (mb) might influence in situ methanotroph activity. Mb is a molecule produced by <i>M. trichosporium</i> OB3b that has a high affinity for Cu, reduces Cu toxicity, and may influence Cu availability in terrestrial systems. CuCO₃.Cu(OH)₂ and CuO were chosen for study based on modelling data, reflecting more and less soluble minerals, respectively, and were found to affect <i>M. trichosporium</i> OB3b activity differently. Cells grew without growth lag and with active pMMO on CuCO₃.Cu(OH)₂, regardless of the amount of mineral supplied (<500 μmoles Cu-total l^&minus;1). The organism also grew well on CuO; however, significant sMMO activity was retained up to 50 μmoles Cu-total l^&minus;1, although sMMO activity was suppressed by supplemental mb and-or direct cell-mineral contact. Mb addition increased growth rates (<i>p</i> < 0.05) with both minerals. Results show mb broadly stimulates growth, but Cu mineralogy and mb dictate whether sMMO or pMMO is active in the cells. This explains why sMMO activity has been seen in soils with high Cu and also has implications for predicting dominant MMO activity in terrestrial bioremediation applications.

C. Marshall

B. Mason, L. G. Berry

J. Horne

K. Norrish