Hasil untuk "Mineralogy"

Pierre Shale, L. Schultz, Thomas B. Nolan

S. Kirby

F. Debon, P. Fort

Emily H. Cunningham, Sarah Lambart, Pengyuan Guo et al.

Abstract The mid‐Norwegian Margin, part of the North Atlantic Igneous Province (NAIP), is a well‐studied volcanic rifted margin formed during the breakup between Greenland and Eurasia ∼56 Ma, with the largest accumulation of magmatic material hosted by the Vøring Margin section. Despite extensive study in the area, the main controls on magmatic productivity during continental breakup remain debated. To constrain the drivers of breakup magmatism, we developed an inverse Monte Carlo statistical melting model that infers source mineralogy from basalt chemistry. When applied to basalts recently recovered on the Vøring Margin, our results reveal a clear shift in source mineralogy during rifting, with peak magmatism coinciding with clinopyroxene enrichment, despite mantle potential temperatures likely being capped below 1500°C. We also establish that, while the proto‐Iceland mantle plume played a role during the emplacement of the NAIP, the main driver for the continental breakup magmatism is lithospheric thinning as a consequence of continent breakup. This study provides new insights into the magmatic and geodynamic evolution of the mid‐Norwegian Margin, emphasizing the role of lithospheric refertilization in driving breakup magmatism.

P. Tsakiridis, G. Papadimitriou, S. Tsivilis et al.

Mélissa Martinot, Kerri L. Donaldson Hanna, Benjamin T. Greenhagen et al.

Questions about the formation of the primary anorthositic crust of the Moon remain unanswered. Spectroscopic surveys of the lunar crust have evidenced the presence of pure, crystalline plagioclase exposures (PCPEs) across the surface, which are assumed to be remnants of the Moon's ancient anorthositic crust. Results from our work show that the plagioclase composition within PCPEs in all geochemical terranes is relatively uniform and consistent with highly calcic anorthite found in immature and mature Apollo highlands regolith samples. Observed variations in our spectroscopic data sets are likely related to maturity, not plagioclase composition, supporting a single crust-forming event rather than serial magmatism. To constrain the plagioclase composition within the primary anorthositic crust, we use remote sensing data from two instruments on board different lunar orbiters, Moon Mineralogy Mapper (M ^3 ) and Diviner Lunar Radiometer (Diviner). When working with data sets acquired by different instruments, coregistration is key if one wants to extract values from those instruments at the same point on the lunar surface. Due to the suboptimal selenolocation of the M ^3 observations, misalignments exist between the M ^3 data and Diviner data sets. Here we present a methodology for extracting both data sets from a single locality while mitigating offsets, and provide results about the composition of the primary anorthositic crust. M ^3 was used to identify regions of interest within previously reported PCPEs at a selection of craters, and Diviner Christiansen feature data was utilized to constrain these locations’ plagioclase composition by comparing them against laboratory measurements of Apollo 16 highland soil samples.

Saeedeh Rastgar, Wahid Zamani, Monireh Faghani et al.

This study investigates the effectiveness of Lignocellulose Nanofibers (LNCFs) as a sustainable adsorbent for the removal of nitrite, nitrate, and phosphate from aquaculture wastewater, specifically focusing on fish farms in Gamishan. We optimized several key parameters, including pH, contact time, temperature, and adsorbent dosage, to determine the optimal conditions for pollutant removal. The results indicate that the highest removal efficiencies were achieved at a pH level of 6.5, with a contact time of 67 minutes, a temperature of 30 ○C, and an adsorbent dosage of 400 mg. Specifically, the removal rates were found to be 93 % for nitrate, 95 % for nitrite, and 96 % for phosphate. These findings demonstrate that LNCFs are not only effective in reducing these pollutants but also possess significant potential as a sustainable solution for wastewater treatment in aquaculture systems. The study emphasizes the critical role of optimizing operational parameters to maximize pollutant adsorption. Furthermore, the successful application of LNCFs in aquaculture practices could enhance environmental sustainability by promoting healthier aquatic ecosystems and effectively addressing the challenges posed by nutrient loading in water bodies. This research lays the groundwork for future investigations into the broader applicability of LNCFs in various wastewater treatment contexts, suggesting that their integration into aquaculture practices could lead to substantial improvements in water quality management and ecosystem health.

Erbin Shi, Xiaojia Zeng, Jian Chen et al.

Calcium sulfates are widely distributed in Gale crater and Endeavour crater on Mars. However, the mole ratios of Ca ^2+ and SO _3 in some Sr–Ba-rich sulfate veins are less than 1. This indicates that there may be additional solid solution phases on Mars, including Ca–Sr, Ba–Sr, and Ca–Ba sulfates, which, on Earth, are typically found in marine environments. In this study, we synthesized a series of Ca–Sr, Ba–Sr, and Ca–Ba sulfate solid solutions in the laboratory. These synthesized solid solutions were then characterized using various techniques, including X-ray powder diffraction (XRD), Raman, mid-infrared, and visible and near-infrared. Our results show that the XRD and Raman spectra of Ca–Sr and Ba–Sr sulfates varied with their cation contents. In particular, the linear relationships ( R ^2 ≥ 0.98) between the mole ratios of cation ions and peak positions of ${{\rm{SO}}}_{4}^{2{-}}$ tetrahedron ( v _1 ) in Raman spectra were obtained. The mole content of Ca ^2+ , Sr ^2+ , and Ba ^2+ can be precisely constrained in Ca–Sr, Ba–Sr, and Ca–Ba sulfate solid solution phases through linear relationships, respectively. These results are the experimental basis for analyzing in situ detection data (e.g., SHERLOC, SuperCam, and Oxia planum) and can be used to precisely constrain the mineral phases of calcium sulfate veins on Mars.

Yanisel Batista-Nuñez, Arlenys Carbonell-Pupo, Yurisley Valdés-Mariño. et al.

Geotourism is a tourism modality that has gained relevance due to its connection with sustainable tourism, offering a wide range of recreational and cognitively enriching experiences. In Cuba, although the government stimulates this type of tourism, and studies are being conducted to identify and highlight the heritage value of geosites, its visibility as a sustainable alternative remains insufficient to achieve a significant boost within the country´s tourism offering. Reversing this situation and promoting the broad and sustainable use of geosites on the island is a task that must be grounded in scientific foundations. Accordingly, a literature review was carried out to demonstrate the role geotourism plays in sustainable development, from an integrative perspective of science, technology, and society. The analysis conducted showed that geotourism can be an effective tool to preserve a region's natural and cultural resources and generate economic benefits. However, for it to be truly sustainable, it must responsibly consider the environmental, social and cultural impacts it can generate. In addition, scientific activity linked to geotourism must evaluate the current conditions and social perceptions of the environment, while promoting an ethic of preservation shared between tourism providers and consumers. It is concluded that it is essential to develop studies aimed at analyzing the role of science, technology and society in the implementation of geotourism, in order to identify the key factors that have an impact on its consolidation as a sustainable development strategy.

K. C. Lohmann

E. Galán

G. Cultrone, C. Rodriguez-Navarro, E. Sebastián et al.

Bilal Wadood, Suleman Khan, Michael Wagreich et al.

This study deals with unraveling the diagenesis-induced porosity evolution in a mixed clastic-carbonate sequence of the Middle Permian Indus Basin, Pakistan. Multiple data sets including outcrop, petrography, cathodoluminescence, scanning electron microscopy (SEM), mineralogy, and geochemical isotopic compositions were integrated to establish a link between porosity evolution and diagenesis. The spatial thickness and facies variations of the strata at outcrop scale are inherently controlled by the underlying bathymetry of the basin with deepening westward trend. The low values of δ18O of the target strata, relative to average values of the Permian carbonate, hints to diagenetic alteration in the strata. The data sets used in this study reveal modification of the strata in four environments, that is, i) early marine diagenesis indicated by micritization, pervasive dolomitization and isopachous fibrous cements, followed by ii) meteoric dissolution, and iii) shallow burial diagenetic processes including the precipitation of blocky cement, compaction of skeletal and non-skeletal allochems, and stylolites, and iv) a deep burial environment, characterized by pressure solution, and micro-fractures. The clastic intervals host subangular to subrounded quartz grains, floating textures, and almost complete absence of deleterious clay minerals, consequently resulting in the preservation of primary porosity. The primary porosity of carbonate intervals is preserved in the form of intercrystalline and intracrystalline porosity. The secondary porosity evolved through various diagenetic phases in the form of fractures and dissolution. The diagenetic solution mediated by organic matter in carbonates may have experienced both bacterial decomposition and thermochemical sulfate reduction, precipitating sulfides within the pores. The plug porosity/permeability analyses generally suggest high porosity in the siliciclastic unit, and carbonates with wackestone fabric while lower values were observed for the inner shelf pure carbonate facies. However, both intervals show very low permeability values probably due to isolated moldic pores and intense micritization. Therefore, clastic intervals may provide an opportunity to serve as a moderate reservoir; however, the carbonate intervals possess very low permeability values and could generally be considered as low-moderate reservoir potential.

Igor S. Peretyazhko, Elena A. Savina, Irina A. Pulyaeva

New data obtained from core samples of two boreholes and dredged samples from the Alba Guyot in the Magellan Seamount Trail (MST), Western Pacific, including the ⁴⁰Ar/³⁹Ar age determinations of basanite, and the mineralogy of basanite, tuff, tuffite, mantle-derived inclusions in basanite and tuff (lherzolite xenolith and Ol, Cpx, and Opx xenocrysts), and calcareous nannofossil biostratigraphy, have implications for the guyot′s development and history. Volcanic units in the upper part of the Alba Guyot main edifice and its Oma Vlinder satellite, at sea depths between 3600 and 2200 m, were deposited during the Cretaceous 112 to 86 Ma interval. In the following ~60 myr, the Alba Guyot became partly submerged and denuded with the formation of a flat summit platform while the respective fragment of the Pacific Plate was moving to the Northern Hemisphere. Volcanic activity in the northeastern part of the guyot summit platform was rejuvenated in the Miocene (24–15 Ma) and produced onshore basanitic volcanoes and layers of tuff in subaerial and tuffite in shallow-water near-shore conditions. In the Middle-Late Miocene (10–6 Ma), after the guyot had submerged, carbonates containing calcareous nannofossils were deposited on the porous surfaces of tuff and tuffite. Precipitation of the Fe-Mn crust (<i>Unit III</i>) recommenced during the Pliocene–Pleistocene (<1.8 Ma) when the guyot summit reached favorable sea depths. The location of the MST guyots in the northwestern segment of the Pacific Plate near the Mariana Trench, along with the Miocene age and alkali-basaltic signatures of basanite, provide first evidence for petit-spot volcanism on the Alba Guyot. This inference agrees with the geochemistry of Cenozoic petit-spot basaltic rocks from the Pacific and Miocene basanite on the Alba Guyot. Petit-spot volcanics presumably originated from alkali-basaltic melts produced by decompression partial melting of carbonatized peridotite in the metasomatized oceanic lithosphere at the Lithosphere–Asthenosphere Boundary level. The numerous volcanic cones with elevations of up to 750 m high and 5.1 km in basal diameter, discovered on the Alba summit platform, provide the first evidence of voluminous Miocene petit-spot basanitic volcanism upon the Cretaceous guyots and seamounts of the Pacific.

A. Tuğrul, I. Zarif

R. Esposito, D. Redi, L. V. Danyushevsky et al.

<p>Mount Somma–Vesuvius is a stratovolcano that represents a geological hazard to the population of the city of Naples and surrounding towns in southern Italy. Historically, volcanic eruptions at Mt. Somma–Vesuvius (SV) include high-magnitude Plinian eruptions, such as the infamous 79 CE eruption that occurred after 295 years of quiescence and killed thousands of people in Pompeii and surrounding towns and villages. The last eruption at SV was in 1944 and showed a Volcanic Explosivity Index (VEI) of 3 (0.01 km<span class="inline-formula">³</span> of volcanic material erupted). Following the 1944 eruption, SV has been dormant for the past nearly 79 years, with only minor fumarolic and seismic activity. During its long history, centuries of dormancy at SV have ended with Plinian eruptions (VEI 6) that signal the beginning of a new cycle of eruptive activity. Thus, the current dormancy stage demands a need to better understand the mechanism involved in high-magnitude eruptions in order to better predict future eruption magnitude and style. Despite centuries of research on the SV volcanic system, many questions remain, including the evolution of magmatic volatiles from deep primitive magmas to shallower more evolved magmas. Developing a better understanding of the physical and chemical processes associated with volatile evolution at SV can provide insights into magma dynamics and the mechanisms that trigger highly explosive eruptions at SV.</p> <p>In this study, we present new data for the pre-eruptive volatile contents of magmas associated with four Plinian and two inter-Plinian eruptions at SV based on analyses of reheated melt inclusions (MIs) hosted in olivine. We correct the volatile contents of bubble-bearing MIs by taking into account the volatile contents of bubbles in the MIs. We recognize two groups of MIs: one group hosted in high-Fo olivine (Fo<span class="inline-formula">_85–90</span>) and relatively rich in volatiles and the other group hosted in low-Fo olivine (Fo<span class="inline-formula">_70–69</span>) and relatively depleted in volatiles. The correlation between volatile contents and compositions of host olivines suggests that magma fractionation took place under volatile-saturated conditions and that more differentiated magmas reside at shallower levels relative to less evolved/quasi-primitive magmas. Using the CO<span class="inline-formula">₂</span> contents of corrected MIs hosted in Fo<span class="inline-formula">₉₀</span> olivine from SV, we estimate that 347 to 686 t d<span class="inline-formula">⁻¹</span> of magmatic CO<span class="inline-formula">₂</span> exsolved from SV magmas during the last 3 centuries (38–75 Mt in total) of volcanic activity. Although this study is limited to only few SV magmas, we suggest that<span id="page922"/> further study applying similar methods could shed light on the apparent lack of correlation between the volatile contents of MIs and the style and age of eruptions. Further, such studies could provide additional constraints on the origin of CO<span class="inline-formula">₂</span> and the interaction between the carbonate platform and ascending magmas below SV.</p>

Viczián István, Kristály Ferenc

The present study is a review of publications regarding special aspects of the mineralogy of the Kaba meteorite, clay minerals, hydrous phases, and organic matter. In Section 1, the history of fall and finding of the meteorite and the first classical mineralogical description in the Year 1961 are mentioned. The most frequent alteration product of primary silicates and the glassy matrix is Fe-bearing saponite. By modelling of hydrothermal alteration of Allende-type meteorites, artificial saponite could be produced. The thermodynamic study proved the possibility of hydrous neoformation of silicates and magnetite at low temperatures, mostly below 100°C. The formation of Fe-rich external rims in forsterite grains by hydrothermal action was demonstrated by electron probe microanalysis and scanning electron microscopy-cathodo-luminescence methods. Foliation in CV3 carbonaceous chondrites indicates that the Kaba meteorite is derived from the external, shallow zone of the parent body. A combination of X-ray power diffraction (XRD) and Mössbauer spectroscopy made the exact modal analysis of CV3 chondrites possible, including Kaba. The study of alteration by in situ determination of stable oxygen isotope contents may provide constraints regarding the oxygen isotopic composition of the aqueous fluid on the CV parent asteroid. The degree of thermal metamorphism of the organic matter was determined by using Raman spectroscopy. The presence of aromatic and aliphatic, saturated and unsaturated hydrocarbons, and various amino acids was demonstrated. The non-biogenic origin is more probable; however, there are textural and mineralogical observations that may indicate also the biogenic origin of organic matter. In addition to the review of the literature above, as an appendix, shortly new XRD investigations of the authors are reported that indicated smectite-like phases in a thin section made of the meteorite.

Shangbin Chen, Yanming Zhu, Hongyan Wang et al.

C. Boyd

T. Lowenstein, M. Timofeeff, S. Brennan et al.