Articles de revues : « Emplacement Optimal »

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Álvarez, M., E. Martínez, Á. Arquero et M. Romero. « Apoyo a la selección de emplazamientos óptimos de edificios. Localización de un edificio universitario mediante el Proceso Analítico Jerárquico (AHP) ». Informes de la Construcción 62, n^o 519 (1 septembre 2010) : 35–45. http://dx.doi.org/10.3989/ic.08.052.

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Murty, Sivala Vishnu. « Emplacement Detection Using Ant Colony Optimization ». International Journal for Research in Applied Science and Engineering Technology 10, n^o 6 (30 juin 2022) : 4890–93. http://dx.doi.org/10.22214/ijraset.2022.45046.

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Abstract: The Ant Colony Optimization (ACO) is a algorithm with metaheuristic and versatile optimization approach based on the behaviour of ants. After a numerous analysis, ACO has been applied to solve different combinatorial problem statements. The ant colony metaheuristic proves itself to be efficient in solving hard problems, often generating the best solution in the shortest amount of time. However, not enough attention has been paid to ACO as a means of solving problems that have optimal solutions which can be found using other methods. The shortest path problem is undoubtedly one of the aspects of great significance to navigation and telecommunications. It is used, amongst others, for determining the shortest route between two geographical locations, for routing in packet networks, and to balance and optimize network utilization. Thus, this article introduces Shortest Path ACO, an Ant Colony Optimization based algorithm designed to find the shortest path in a graph. The algorithm consists of several sub problems that are presented successively. Each subproblem is discussed from many points of view to enable researchers to find the most suitable solutions to the problems they investigate.

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Sathyamoorthy, Malathy, Sangeetha Kuppusamy, Anand Nayyar et Rajesh Kumar Dhanaraj. « Optimal emplacement of sensors by orbit-electron theory in wireless sensor networks ». Wireless Networks 28, n^o 4 (11 mars 2022) : 1605–23. http://dx.doi.org/10.1007/s11276-022-02919-9.

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Belaabed, Faris, et Leila Arabet. « Prediction of the Discharge Coefficient of a Labyrinth Weir Type D by an Artificial Neural Network Method ». Archives of Hydro-Engineering and Environmental Mechanics 71, n^o 1 (1 janvier 2024) : 59–72. http://dx.doi.org/10.2478/heem-2024-0004.

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Abstract This study presents the use, and its advantages, of artificial intelligence methods to predict the discharge coefficient (Cw ), considering the approach conditions of the labyrinth weir type D. The study suggests modifying the training and validation rates in AI tools, which are often fixed without proper justification in previous studies. Unlike most studies that use geometric dimensions as inputs, this work focuses on the approach conditions (the emplacement of the labyrinth weir and filling the alveoli upstream and downstream) of the labyrinth weir type D. The results, based on laboratory experiments, show that these modified inputs significantly impact the e ciency and cost of constructing the weir. Moreover, the C w predictions based on these inputs are highly satisfactory compared to laboratory test results. In terms of training and validation ratios, the study confirms that the optimal ratio is 70/30 for accurate and highly satisfactory predictions.

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Hobbs, Bruce E., et Alison Ord. « The mechanics of granitoid systems and maximum entropy production rates ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 368, n^o 1910 (13 janvier 2010) : 53–93. http://dx.doi.org/10.1098/rsta.2009.0202.

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A model for the formation of granitoid systems is developed involving melt production spatially below a rising isotherm that defines melt initiation. Production of the melt volumes necessary to form granitoid complexes within 10 4 –10 7 years demands control of the isotherm velocity by melt advection. This velocity is one control on the melt flux generated spatially just above the melt isotherm, which is the control valve for the behaviour of the complete granitoid system. Melt transport occurs in conduits initiated as sheets or tubes comprising melt inclusions arising from Gurson–Tvergaard constitutive behaviour. Such conduits appear as leucosomes parallel to lineations and foliations, and ductile and brittle dykes. The melt flux generated at the melt isotherm controls the position of the melt solidus isotherm and hence the physical height of the Transport/Emplacement Zone. A conduit width-selection process, driven by changes in melt viscosity and constitutive behaviour, operates within the Transport Zone to progressively increase the width of apertures upwards. Melt can also be driven horizontally by gradients in topography; these horizontal fluxes can be similar in magnitude to vertical fluxes. Fluxes induced by deformation can compete with both buoyancy and topographic-driven flow over all length scales and results locally in transient ‘ponds’ of melt. Pluton emplacement is controlled by the transition in constitutive behaviour of the melt/magma from elastic–viscous at high temperatures to elastic–plastic–viscous approaching the melt solidus enabling finite thickness plutons to develop. The system involves coupled feedback processes that grow at the expense of heat supplied to the system and compete with melt advection. The result is that limits are placed on the size and time scale of the system. Optimal characteristics of the system coincide with a state of maximum entropy production rate.

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Piquer, José, Pablo Sanchez-Alfaro et Pamela Pérez-Flores. « A new model for the optimal structural context for giant porphyry copper deposit formation ». Geology 49, n^o 5 (26 janvier 2021) : 597–601. http://dx.doi.org/10.1130/g48287.1.

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Abstract Porphyry-type deposits are the main global source of copper and molybdenum. An improved understanding of the most favorable structural settings for the emplacement of these deposits is necessary for successful exploration, particularly considering that most future discoveries will be made under cover based on conceptual target generation. A common view is that porphyry deposits are preferentially emplaced in pull-apart basins within strike-slip fault systems that favor local extension within a regional compressive to transpressive tectonic regime. However, the role of such a structural context in magma storage and evolution in the upper crust remains unclear. In this work, we propose a new model based on the integration of structural data and the geometry of magmatic-hydrothermal systems from the main Andean porphyry Cu-Mo metallogenic belts and from the active volcanic arc of southern Chile. We suggest that the magma differentiation and volatile accumulation required for the formation of a porphyry deposit is best achieved when the fault system controlling magma ascent is strongly misoriented for reactivation with respect to the prevailing stress field. When magmas and fluids are channeled by faults favorably oriented for extension (approximately normal to σ3), they form sets of parallel, subvertical dikes and veins, which are common both during the late stages of the evolution of porphyry systems and in the epithermal environment. This new model has direct implications for conceptual mineral exploration.

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Ellis, Jean T., et Mayra A. Román-Rivera. « Assessing Natural and Mechanical Dune Performance in a Post-Hurricane Environment ». Journal of Marine Science and Engineering 7, n^o 5 (2 mai 2019) : 126. http://dx.doi.org/10.3390/jmse7050126.

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The purpose of this study is to document the geomorphic evolution of a mechanical dune over approximately one year following its installation and compare it to the recovery of a natural dune following the impact of Hurricane Matthew (2016). During the study period, the dunes’ integrity was tested by wave and wind events, including king tides, and a second hurricane (Irma, 2017), at the end of the study period. Prior to the impact of the second hurricane, the volumetric increase of the mechanical and natural dune was 32% and 75%, respectively, suggesting that scraping alone is not the optimal protection method. If scraping is employed, we advocate that the dune should be augmented by planting. Ideally, the storm-impacted dune should naturally recover. Post-storm vegetation regrowth was lower around the mechanical dune, which encouraged aeolian transport and dune deflation. Hurricane Irma, an extreme forcing event, substantially impacted the dunes. The natural dune was scarped and the mechanical dune was overtopped; the system was essentially left homogeneous following the hurricane. The results from this study question the current practice of sand scraping along the South Carolina coast, which occurs post-storm, emplacement along the former primary dune line, and does not include the planting of vegetation.

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Rueda-Velasco, Feizar Javier, Wilson Adarme-Jaimes, Angélica Garzón-Luna, Jhonatan Marroquín-Ávila et Gabriel Parada-Caro. « Evaluation of a facility location for a food assistance supply chain. The case of Bienestarina in Colombia ». Ingeniería e Investigación 39, n^o 3 (12 février 2020) : 50–61. http://dx.doi.org/10.15446/ing.investig.v39n3.77175.

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The evaluation of the strategic supply chain configuration is considered one of the strategic logistics decisions, especially in food assistance supply chains focused on generating better nutritional conditions in vulnerable populations. In Colombia, there is a social program called Bienestarina, which aims to promote food and nutritional security in a vulnerable population. Although the government supports the program for improving nutritional support, there are currently inconsistencies in freight flows, lack of coverage in some areas, and delivery delays. Therefore, this work aims to evaluate the current configuration of the supply chain and propose improvements related to the facility location. Such advances would enable the increase in the efficacy of the network and the reduction of malnutrition in the country. For this purpose, a mixed-integer mathematical programming model is presented, which considers the weighted distance criterion for different demand scenarios and supports the location-allocation decision in a social assistance supply chain. The current network configuration was compared with the optimal proposed structure. The comparisons show highly potential improvements in freight flow allocation, suggests several variations in the existing warehouses emplacement, and generates public policy implications to reduce the logistic cost in the system, prioritizing in turn the demand covering.

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Manor, Matthew J., Stephen J. Piercey, Corey J. Wall et Nikola Denisová. « High-Precision CA-ID-TIMS U-Pb Zircon Geochronology of Felsic Rocks in the Finlayson Lake VMS District, Yukon : Linking Paleozoic Basin-Scale Accumulation Rates to the Occurrence of Subseafloor Replacement-Style Mineralization ». Economic Geology 117, n^o 5 (1 août 2022) : 1173–201. http://dx.doi.org/10.5382/econgeo.4910.

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Abstract Felsic igneous complexes and associated volcano-sedimentary rocks in continental back-arc environments host large-tonnage and/or high-grade volcanogenic massive sulfide (VMS) deposits. The emplacement mechanisms, style, and preservation of these deposits is thought to be partially dependent on depositional rates of the host lithofacies (i.e., discrete volcanic eruptions) relative to the setting of massive sulfide genesis on the seafloor as mounds and/or via subseafloor replacement of existing strata. The localization and occurrence of subseafloor replacement-style VMS deposits is therefore strongly influenced by the characteristics of the volcano-sedimentary facies in the hosting basin and the rates of their emplacement; the latter are poorly constrained in the literature due to the difficulty of obtaining high-precision dates that make this possible in Phanerozoic and older rocks. New high-resolution U-Pb geochronology and detailed regional stratigraphic investigation indicate that Devonian-Mississippian volcanic rocks and associated VMS mineralization in the Yukon-Tanana terrane in the Finlayson Lake district, Yukon, Canada, were erupted or emplaced during distinct time periods (ca. 363.3, 362.8, and 355.2 Ma) in two discrete submarine basins: the Kudz Ze Kayah formation and the Wolverine Lake group. The VMS deposits in both settings are contained within intrabasinal rocks that accumulated at rapid rates of ~350 to 2,000 m/m.y. over 0.6 to 1.4 m.y. Locally, these rates reach peak rates up to 7,500 m/m.y. in the Wolverine Lake group, which are interpreted to reflect facies deposition by mass transport complexes or turbidity currents. These new dates indicate that rapid accumulation of volcanic rocks in the back-arc basins was critical for localizing subseafloor replacement-style mineralization and the development of the Zn-enriched GP4F, Kudz Ze Kayah, and Wolverine VMS deposits. Rapid depositional processes observed in these deposits and their host basins are interpreted to have an important role in developing highly porous and permeable, water-saturated lithofacies that provide optimal conditions for enhancing zone refining processes and subsequent preservation of massive sulfide mineralization, which are key in the development of high-grade and large-tonnage VMS deposits. It is herein suggested that quantitative basin-scale accumulation rates, as a result of new U-Pb geochronological methods and increased precision combined with detailed stratigraphic and facies analysis, may provide important perspectives on the formation of continental back-arc basins and the localization of VMS deposits in other continental margin environments globally.

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Crépon, Alexandre, Lucie Mathieu, Daniel J. Kontak, Jeffrey Marsh et Michael A. Hamilton. « An Archean Porphyry-Type Deposit : Cu-Au Mineralization Associated with the Chibougamau Tonalite–Diorite Pluton, Abitibi Greenstone Belt, Canada ». Minerals 14, n^o 12 (20 décembre 2024) : 1293. https://doi.org/10.3390/min14121293.

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The Neoarchean diorite- and tonalite-dominated Chibougamau pluton (Canada) is ideal for case studies dedicated to the petrogenesis and timing of emplacement of fertile magmatic systems and associated Cu-Au porphyry systems. Using whole-rock analyses, geochronology, and zircon chemistry, it is determined that an early magmatic phase (pre-2714 Ma) is derived from a dioritic magma with a moderate ƒO2 (ΔFMQ 0 to +1), which is optimal for transporting Au and Cu, and that diorite is a potentially fertile magma. Field descriptions indicate that the main mineralizing style consists of sulfide-filled hairline fractures and quartz–carbonate veins. This is likely the consequence of fluid circulation facilitated by a well-developed diaclase network formed following the intrusion of magma at about 4–7 km depth in a competent hosting material. The petrographic features of fluid inclusions (FIs), considered with their microthermometric data and evaporate mound chemistry, suggest the exsolution of early CO2-rich fluids followed by the unmixing of later aqueous saline fluids characterized by a magmatic signature (i.e., Na-, Ca-, Fe-, Mn-, Ba-, and Cl-F). The type of magmatism and its oxidation state, age relationships, the nature of mineralization, and fluid chemistry together support a model whereby metalliferous fluids are derived from an intermediate hydrous magma. This therefore enforces a porphyry-type metallogenic model for this Archean setting.

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Vietor, Tim, et Michael Schnellmann. « Site selection for the best clay-hosted repository in Switzerland ». Safety of Nuclear Waste Disposal 1 (10 novembre 2021) : 51–52. http://dx.doi.org/10.5194/sand-1-51-2021.

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Abstract. The site selection process for the deep geological repositories in Switzerland is in its final phase. All three remaining sites fulfil the requirements of the repositories for low level waste (LLW) as well as for high level waste (HLW) and spent fuel. Using surface-based exploration methods, including 3D seismic studies and deep bore holes, Nagra has recently collected the necessary data to select the most suitable site. The sites will be compared based on 13 technical criteria defined in 2008 and already used in the 2 previous phases of the selection process. The criteria comprise safety-related aspects including the barrier properties and their long-term stability as well as the construction suitability of the repository and its access facilities. If one site offers optimal conditions for both HLW and LLW and the space requirements can be met at that site, a co-disposal facility will be proposed. This facility will then comprise separate emplacement areas with specific safety concepts for the different waste categories. In our contribution we present the overall approach for the surface-based exploration in the different stages of the site selection process. We show how we integrated third party data, seismic surveys, surface mapping as well as deep and shallow bore holes to drive the site selection process. Example data sets from the ongoing deep drilling campaign (clay content, hydrotest data, porewater isotope profiles etc.) and recent 3D seismic surveys are used to illustrate our approach to distinguish the remaining sites according to long-term safety and to underline the large safety margin of the selected clay host rock in long-term evolution scenarios.

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Burns, Jack O. « Aperture Synthesis imaging from the Moon ». International Astronomical Union Colloquium 131 (1991) : 420–27. http://dx.doi.org/10.1017/s0252921100013762.

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AbstractFour candidate imaging aperture synthesis concepts are described for possible emplacement on the Moon beginning in the next decade. These include an optical interferometer with 10 μarcsec resolution, a submillimeter array with 6 milliarcsec resolution, a Moon- Earth VLBI experiment, and a very low frequency interferometer in lunar orbit.

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Nouiri, Issam, et Féthi Lebdi. « Algorithme Génétique (AG) pour le choix optimal des stations d’appoint de chlore sur les réseaux d’eau potable ». Revue des sciences de l'eau 19, n^o 1 (20 mars 2006) : 47–55. http://dx.doi.org/10.7202/012596ar.

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Résumé La chloration sur les réseaux de distribution d’eau potable constitue une tâche délicate. Elle assure la protection contre la reviviscence microbienne et contre la contamination du réseau. Les réactions du chlore avec la matière organique du système entraînent la formation des sous‑produits chlorés, indésirables pour la santé humaine. Ainsi, le maintien du taux de chlore libre à des valeurs admissibles, sur tout le réseau et à tout moment, constitue un objectif principal des gestionnaires des réseaux. Lors de la chloration à partir des sources d’eau, les processus de réaction-transport créent sur les réseaux, caractérisés par des temps de séjours importants, de mauvaises distributions des taux de chlore libre. Les stations d’appoints sur les réseaux constituent une alternative efficace. La détermination de leur nombre et le choix des emplacements optimums constituent les deux difficultés auxquelles sont confrontés les gestionnaires. Le présent travail utilise un algorithme génétique (AG) pour la détermination du nombre et des emplacements optimums des stations d’appoint de chlore sur les réseaux. Deux objectifs ont été fixés : (1) l’amélioration de l’homogénéité spatio-temporelle de la chloration et (2) la minimisation du nombre de stations d’appoint. L’application du modèle développé sur un réseau test a permis d’identifier les emplacements des deux stations d’appoint de chlore. La solution optimale a considérablement amélioré l’homogénéité et a assuré, pour 98 % des noeuds, des taux de chlore libre dans l’intervalle admissible (0,1-0,5) mg/L.

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Yudintsev, Sergey V., Michael I. Ojovan et Victor I. Malkovsky. « Thermal Effects and Glass Crystallization in Composite Matrices for Immobilization of the Rare-Earth Element–Minor Actinide Fraction of High-Level Radioactive Waste ». Journal of Composites Science 8, n^o 2 (10 février 2024) : 70. http://dx.doi.org/10.3390/jcs8020070.

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The current policy of managing high-level waste (HLW) derived in the closed nuclear fuel cycle consists in their vitrification into B-Si or Al-P vitreous forms. These compounds have rather limited capacity with respect to the HLW (5–20 wt%), and their properties change over time due to devitrification of the glasses. Cardinal improvement in the management of HLW can be achieved by their separation onto groups of elements with similar properties, followed by their immobilization in robust waste forms (matrices) and emplacement in deep disposal facilities. One of the possible fractions contains trivalent rare-earth elements (REEs) and minor actinides (MAs = Am and Cm). REEs are the fission products of actinides, which are mainly represented by stable isotopes of elements from La to Gd as well as Y. This group also contains small amounts of short-lived radionuclides with half-lives (T1/2) from 284 days (144Ce) to 90 years (151Sm), including 147Pm (T1/2 = 2.6 years), 154Eu (T1/2 = 8.8 years), and 155Eu (T1/2 = 5 years). However, the main long-term environmental hazard of the REE–MA fraction is associated with Am and Cm, with half-lives from 18 years (244Cm) to 8500 years (245Cm), and their daughter products: 237Np (T1/2 = 2.14 × 106 years), 239Pu (T1/2 = 2.41 × 104 years), 240Pu (T1/2 = 6537 years), and 242Pu (T1/2 = 3.76 × 105 years), which should be immobilized into a durable waste form that prevents their release into the environment. Due to the heat generated by decaying radionuclides, the temperature of matrices with an REE–MA fraction will be increased by hundreds of centigrade above ambient. This process can be utilized by selecting a vitreous waste form that will crystallize to form durable crystalline phases with long-lived radionuclides. We estimated the thermal effects in a potential REE–MA glass composite material based on the size of the block, the content of waste, the time of storage before immobilization and after disposal, and showed that it is possible to select the waste loading, size of blocks, and storage time so that the temperature of the matrix during the first decades will reach 500–700 °C, which corresponds to the optimal range of glass crystallization. As a result, a glass–ceramic composite will be produced that contains monazite ((REE,MA)PO4) in phosphate glasses; britholite (Cax(REE,MA)10-x(SiO4)6O2) or zirconolite ((Ca,REE,MA)(Zr,REE,MA)(Ti,Al,Fe)2O7), in silicate systems. This possibility is confirmed by experimental data on the crystallization of glasses with REEs and actinides (Pu, Am). The prospect for the disposal of glasses with the REE–MA fraction in deep boreholes is briefly considered.

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Ait El Haj, Badiâ, Aboubakr Bouayad et Mohammed Alami. « Effect of Mould Temperature and Melt Treatment on Properties of an AlSi9 Cast Alloy - Thermal and Microstructural Investigations ». International Letters of Chemistry, Physics and Astronomy 55 (juillet 2015) : 12–18. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.55.12.

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In this study we used the cast TATUR samples that promotes the formation of an AlSi alloy porosity through a variable temperature gradient from top to bottom of the specimen. The die (permanent mold) was instrumented by thermocouples in order to follow the cooling of the specimen in several emplacements. Thermal analyses via cooling curves have been correlated to the microstructural data (SDAS measurement). Samples were cut from all castings and analyzed by optical microscopy in order to get the Secondary Dendrite Arm Spacing (SDAS) variation in function of cooling rates in the casting. The present work shows the effect of various pre-heating mould temperature and melt treatment on secondary dendrite arm spacing.

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Ait El Haj, Badiâ, Aboubakr Bouayad et Mohammed Alami. « Effect of Mould Temperature and Melt Treatment on Properties of an AlSi9 Cast Alloy - Thermal and Microstructural Investigations ». International Letters of Chemistry, Physics and Astronomy 55 (3 juillet 2015) : 12–18. http://dx.doi.org/10.56431/p-xzgx6e.

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In this study we used the cast TATUR samples that promotes the formation of an AlSi alloy porosity through a variable temperature gradient from top to bottom of the specimen. The die (permanent mold) was instrumented by thermocouples in order to follow the cooling of the specimen in several emplacements. Thermal analyses via cooling curves have been correlated to the microstructural data (SDAS measurement). Samples were cut from all castings and analyzed by optical microscopy in order to get the Secondary Dendrite Arm Spacing (SDAS) variation in function of cooling rates in the casting. The present work shows the effect of various pre-heating mould temperature and melt treatment on secondary dendrite arm spacing.

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Carrara, Alexandre, Virginie Pinel, Pascale Bascou, Emmanuel Chaljub et Servando De la Cruz-Reyna. « Post-emplacement dynamics of andesitic lava flows at Volcán de Colima, Mexico, revealed by radar and optical remote sensing data ». Journal of Volcanology and Geothermal Research 381 (septembre 2019) : 1–15. http://dx.doi.org/10.1016/j.jvolgeores.2019.05.019.

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Macorps, E., M. Jo, B. Osmanoglu et R. A. Albayrak. « MAPPING AREAS IMPACTED BY VOLCANIC FLOWS DURING AN ERUPTION USING SYNTHETIC APERTURE RADAR AND OPTICAL IMAGERY ». International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVIII-M-1-2023 (21 avril 2023) : 175–82. http://dx.doi.org/10.5194/isprs-archives-xlviii-m-1-2023-175-2023.

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Abstract. During volcanic disasters, the remoteness of the terrains combined with potentially incapacitated lifelines (e.g., disturbed transportation network) prevent ground-based surveys for timely assessment of damage extents. To that effect, we worked to combine satellite optical and Synthetic Aperture Radar (SAR) data to rapidly delineate the areas impacted by fast-moving volcanic flows during an eruption (e.g., Pyroclastic Density Currents (PDCs), lahars), which can in turn be used to target and organize the response efforts. We used the 2015 eruptions of Volcán de Colima (Mexico) and Volcán Calbuco (Chile) volcanoes to calibrate detection thresholds of different types of volcanic flows, from optical and SAR imagery. Optical imagery is used to calculate temporal changes of Normalized Difference Vegetation Index (NDVI) associated with the presence of erupted materials on the surface. SAR amplitude images are used to detect changes in surface roughness (sigma0) attributed to the emplacement of new volcanic flows. Classification of the respective NDVI and SAR amplitude signal changes for different types of volcanic flows is done using very-high-resolution imagery and ground-based data obtained during field work. Linear rescaling of minimal and maximal threshold signals is used to create probability maps of volcanic flow deposits extent, and then combined into a joint probability map to maximize the accuracy of the deposit extents. We tested our ability to generate volcanic flow extent maps during the April 2021 eruption of Soufrière St Vincent, using this detection method and the calibrated threshold values for PDCs and lahars.

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Lumbreras, Mikel, Gonzalo Diarce, Koldobika Martin-Escudero, Alvaro Campos-Celador et Pello Larrinaga. « Industrial Waste Heat District-Heating Design Based on Geographic Information System : Case Study in Vitoria-Gasteiz (Spain) ». Journal of Physics : Conference Series 2042, n^o 1 (1 novembre 2021) : 012040. http://dx.doi.org/10.1088/1742-6596/2042/1/012040.

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Abstract The use of georeferenced information system and Light Detection and Ranging (LiDAR) data in combination with traditional data analytics tools is very promising in urban scale engineering and especially in energy urban planning. This paper explores the use of new DH networks for industrial waste heat exploitation and for that purpose, a case-study in Vitoria-Gasteiz (Spain) is proposed. The methodology explained in this paper explores the incorporation of data from industrial emplacements, buildings and road network in order to identify optimal areas in the city for the construction of a new district-heating network. An area of influence of a buffer of radius 1.5km from the industry location is defined and the proposed algorithm divides this area into grids of different sizes. The path for the network is calculated by optimizing the economic performance of the network. The results show that the district-heating may be built in the south-west direction from the industry and among the 40 configurations studied, payback periods from 6 to 8.5 years are obtained.

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Müller, Franz, Peter Hallas et Uwe Kroner. « The anisotropy of geomaterial granite ». Safety of Nuclear Waste Disposal 2 (6 septembre 2023) : 69–70. http://dx.doi.org/10.5194/sand-2-69-2023.

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Abstract. Granites appear to be isotropic, which qualifies them as suitable crystalline host rocks for nuclear waste repository sites. However, despite their optical appearance, granites show a primary structural anisotropy (Bouchez, 1997) that evolved during emplacement and crystallization of the melt. The major processes involved are magmatic flow and oriented crystal growth (Müller et al., 2011). Hypothetically, it is expected that different tectonic environments, i.e. different orientations of the stress tensor, cause significant differences in the primary anisotropy, which is expressed by the crystallographic preferred orientation (CPO) of the rock-forming minerals. It is likely that primary anisotropic petrophysical properties control the orientation of post-magmatic structural features like extensional fractures and thus shape potential fluid pathways. We present the first results of a systematic study of felsic plutonites, i.e. the GAME project (Gefüge, Textur- und Anisotropie-Messungen von potenziell für die Endlagerung geeigneten Graniten zur Charakterisierung möglicher Fluidwegsamkeiten). The samples of syn-Variscan felsic plutons from two sites (Erzgebirge and Fichtelgebirge) represent different tectonic settings during intrusion: extension and compression. Furthermore, they depict different stages of fractionation of the peraluminous granite suites. The CPOs were analysed using the neutron time-of-flight (ToF) texture diffractometer SKAT (Keppler et al., 2014; Ullemeyer et al., 1998) and EBSD (electron backscatter diffraction). Using scanning electron microscope (SEM) automated mineral liberation analysis (Schulz et al., 2020), modal mineral compositions are quantified. This enables us to model primary or “intrinsic” petrophysical properties for these granites based on the elastic stiffness tensor of the individual rock-forming minerals (Mainprice et al., 2011). Main- and trace-element geochemical data (ICP-AES and ICP-MS) allow for a characterization of the different magmatic settings of the samples. All granites show distinct preferred orientations of rock-forming minerals. The quartz textures, for example, exhibit similar CPOs, with point maxima of the positive rhombs in combination with small circles to crossed-girdle c-axis distributions. However, the orientation with respect to the geographic reference system strongly varies. We will discuss the CPOs in relation to the stress tensor orientation during emplacement of the felsic plutons and compare the primary anisotropy with the post-magmatic fracture patterns of the particular granites.

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Vernon, R. H. « Oriented growth of sillimanite in andalusite, Placitas – Juan Tabo area, New Mexico, U.S.A. » Canadian Journal of Earth Sciences 24, n^o 3 (1 mars 1987) : 580–90. http://dx.doi.org/10.1139/e87-057.

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In metapelitic schists near the Sandia granite in the Placitas – Juan Tabo area, New Mexico, nucleation sites for sillimanite are very variable, but growth of sillimanite in andalusite is common, either as bundles of fibrous ("fibrolitic") sillimanite crystals or as coarser grained parallel prisms or dendritic crystals of sillimanite. Optical relationships indicate a coaxial relationship between the andalusite and the sillimanite but with a and b axes interchanged. Stacking faults formed by dissociated screw dislocations in the andalusite may have provided nucleation sites for sillimanite. Some large sillimanite grains appear to have formed by coarsening of fibrous sillimanite, but others show no evidence of such coarsening. Some fibrous sillimanite occurs in folia in zones of inferred noncoaxial strain accumulation. Some occurs in radiating or crystallographically controlled aggregates in low-strain zones between sillimanite folia. These aggregates do not necessarily indicate postdeformation growth, except on a very local scale, and many of the fibrous sillimanite aggregates have been deformed. Hence, the sillimanite is a product of syndeformational rather than post-deformational metamorphism, as previously suggested, although regional metamorphism and granite emplacement may have been broadly synchronous. The andalusite–sillimanite microstructural relationships indicate a prograde P–T–time path similar to those occurring in other low-pressure (andalusite–sillimanite) metamorphic areas.

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Gouedji, Franck, Christian Picard, Marc Antoine Audet, Thierry Augé et Jorge Spangenberg. « Ni-Cu sulfide mineralization and PGM from the Samapleu mafic-ultramafic intrusion, Yacouba complex, western Ivory Coast ». Canadian Mineralogist 59, n^o 4 (1 juillet 2021) : 631–65. http://dx.doi.org/10.3749/canmin.1900030.

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ABSTRACT The mafic-ultramafic Samapleu deposits of the Yacouba complex, which host nickel, copper sulfides, and platinum-group minerals, are located in the Biankouma-Silipou region, western Ivory Coast. These intrusions originate from the mantle and would have been established during the Proterozoic (2.09 Ga) around 22 km deep within the Archean granulites (3.6–2.7 Ga) which at least partially contaminated them. Platinum-group and sulfide minerals from the Samapleu deposits were studied using optical microscopy, scanning electron microscopy, the electronic microprobe, X-ray fluorescence, fire assay, and a Thermo Fisher Scientific Delta S isotope ratio mass spectrometer system. The sulfide mineralization (mainly pyrrhotite, pentlandite, chalcopyrite ± pyrite) is mainly disseminated with, in places, semi-massive to massive sulfide veins. It is especially abundant in pyroxenite horizons with net or breccia textures. The isotopic ratios of sulfur measured from the sulfides (an average of 0.1‰), the R factor (between 1500 and 10,000), and the Cu/Pd ratios indicate a mantle source. Thus, the sulfides would have formed from sulfide liquids produced by immiscibility from the silicate mantle magma under mafic-ultramafic intrusion emplacement conditions and with possible geochemical modification of the magmas by assimilation of the surrounding continental crust. The platinum-group minerals (michenerite, merenskyite, moncheite, Co-rich gersdorffite, irarsite, and hollingworthite) are mainly associated with the sulfide phases. The nature of the platinum-group minerals is indicative of the probable role of late-magmatic hydrothermal fluids during the mineralizing process.

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Ahmadi, Hemayatullah, Mohammad Reza Hussaini, Atal Yousufi, Alma Bekbotayeva, Akmaral Baisalova, Bakytzhan Amralinova, Indira Mataibayeva, Abdul Baqi Rahmani, Emrah Pekkan et Naqibullah Sahak. « Geospatial Insights into Ophiolitic Complexes in the Cimmerian Realm of the Afghan Central Block (Middle Afghanistan) ». Minerals 13, n^o 11 (18 novembre 2023) : 1453. http://dx.doi.org/10.3390/min13111453.

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Ophiolites are remnants of oceanic crust that have been thrust onto continental crust due to tectonic processes. They are composed of mostly mafic and ultramafic rocks, which are genetically associated with gold, silver, platinum group element (PGE), chrome, manganese, titanium, cobalt, copper, and nickel deposits. The main objective of this research was to identify the spatial distribution of Mesozoic ophiolitic complexes within the Central Afghan Block in Middle Afghanistan using optical remote sensing data and spectral analyses. Distinct algorithms, such as false color composite (FCC), proposed band ratios (PBR), principal component analysis (PCA), and spectral angle mapper (SAM), were used to map the targeted ophiolitic complexes. New band ratios were proposed in this study based on the spectral properties of mafic-ultramafic minerals and rocks, which showed high efficiency. Based on the results, four different ophiolitic complexes were delineated within this study area. These complexes are consistent with previous studies. The accuracy assessment of this study showed an overall accuracy of 72.2%. The findings of this study can significantly contribute to further studies on the emplacement mechanism and paleo-Tethys history of Middle Afghanistan. Also, the spatial distribution of the ophiolitic complexes identified in this study can be used to constrain models of the tectonic evolution of the Central Afghan Block. Additionally, the identification of new band ratios for mapping ophiolitic complexes can be used in future studies of other ophiolite-bearing regions.

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Morad, Sadoon, Ihsan S. Al-Aasm, Fadi H. Nader, Andrea Ceriani, Marta Gasparrini et Howri Mansurbeg. « Impact of diagenesis on the spatial and temporal distribution of reservoir quality in the Jurassic Arab D and C members, offshore Abu Dhabi oilfield, United Arab Emirates ». GeoArabia 17, n^o 3 (1 juillet 2012) : 17–56. http://dx.doi.org/10.2113/geoarabia170317.

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ABSTRACT This study is based on petrographic examination (optical, scanning electron microscope, cathodo-luminescence, backscattered electron imaging, and fluorescence) of 1,350 thin sections as well as isotopic compositions of carbonates (172 carbon and oxygen and 118 strontium isotopes), microprobe analyses, and fluid inclusion microthermometry of cored Jurassic Arab D and C members from 16 wells in a field from offshore Abu Dhabi, United Arab Emirates. The formation was deposited in a ramp with barrier islands and distal slope setting. Petrographic, stable isotopic and fluid-inclusion analyses have unraveled the impact of diagenesis on reservoir quality of Arab D and C within the framework of depositional facies, sequence stratigraphy, and burial history. Diagenetic processes include cementation by grain rim cement and syntaxial calcite overgrowths, formation of moldic porosity by dissolution of allochems, dolomitization and dolomite cementation, cementation by gypsum and anhydrite, and stylolitization. Partial eogenetic calcite and dolomite cementation has prevented porosity loss in grainstones during burial diagenesis. Dolomitization and sulphate cementation of peritidal mud are suggested to have occurred in an evaporative sabkha setting, whereas dolomitization of subtidal packstones and grainstones was driven by seepage reflux of lagoon brines formed during major falls in relative sea level. Recrystallization of dolomite occurred by hot saline waters (Th 85–100°C; and salinity 14–18 wt% NaCl). Anhydrite and gypsum cements (Th 95–105°C; fluid salinity 16–20 wt% NaCl), were subjected to extensive dissolution, presumably caused by thermal sulfate reduction followed by a major phase of oil emplacement. The last cement recorded was a second phase of anhydrite and gypsum (Th 95–120°C; 16–22 wt% NaCl), which fills fractures associated with faults.

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Ivanov, Aleksey. « Material Composition of the Mesozoic Alkaline Rocks of the Yukhta Massif (Southern Yakutia, Central-Aldan Ore Region) ». IOP Conference Series : Earth and Environmental Science 906, n^o 1 (1 novembre 2021) : 012114. http://dx.doi.org/10.1088/1755-1315/906/1/012114.

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Abstract The paper considers the petrographic composition of the Mesozoic alkaline igneous rocks of the Yukhta massif. It is part of the Central Aldan ore region and is spatially located in the central part of the Nymnyr block. The massif is a large multiphase structure, of the most productive stage of the territory’s development – the Mesozoic tectonic-magmatic activation of the Aldan-Stanovoy shield. Determination of the qualitative quantitative-mineralogical characteristics of the 2 and 3 phases of intrusion (emplacement) most promising for gold-radioactive mineralization with the help of crystal-optical methods was the main goal of this work. As a result of petrographic studies of Mesozoic alkaline igneous rocks, it is defined that, the Yukhta massif is a multiphase magmatic structure, with decrease of the content of dark-colored minerals in rocks from the early to later phases of intrusion. In general, the rocks of the massif bear significant traces of secondary changes, which are related to the gradual formation of the massif. According to the features of the composition of the massif rocks, it was found that the latter could be formed from residual differentiates during the fractional crystallization of rock-forming minerals with the involvement of plagioclases. The Yukhta massif is associated with the large Samolazovskoye gold deposit, which formation is related to an intense contact-metasomatic impact on carbonate rocks. Hydrothermal-metasomatic transformations of the latter are the products of multi-stage silica-alkaline metasomatosis associated with the second and especially with the third phases of the massif intrusion, and with further weathering processes, involving karst formation, disintegration of gold-ore metasomatites and the formation of a thick oxidation zone. From whence it is concluded that uranium being a chemically active element does not accumulate in a hypergenic form within the Yukhta massif. Where the weathering crust is intensively developed, a gold-ore type of mineralization is observed. On the other hand, the rocks of the massif itself, in particular syenites of the 2 and 3 phases of intrusion, may be promising for the uranium-thorium-rare earth (U-Tn-REE) type of mineralization. In general, these studies in this direction will provide insight into a number of issues related to the study of the evolution and metallogeny of the Mesozoic tectonic-magmatic activation of the Aldan-Stanovoy Shield

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Sabeti, Mohammad, James J. Noel et Arthur Situm. « Evaluating Corrosion Behaviour of Copper Under Deliquescent Drying/Wetting Cycles in Humid Air Condition ». ECS Meeting Abstracts MA2022-01, n^o 17 (7 juillet 2022) : 2419. http://dx.doi.org/10.1149/ma2022-01172419mtgabs.

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Most nuclear safety agencies around the world agree that deep geological repositories (DGRs) constructed hundreds of meters below ground in stable host rock formations are viable solutions to safely isolate used nuclear fuel. In Canada, the DGR design involves storing used nuclear fuel in sealed copper coated used fuel containers (UFC) surrounded by highly compacted bentonite blocks (HCB) ~500 m underground. Shortly after emplacement, heat generated by radioactive decay of the used fuel will warm the UFC and its surroundings, desiccating the HCB and decreasing moisture on the container surface. As water vapour is driven from the UFC surface, the presence of minor amounts of dissolved salts may cause droplet formation prior to complete evaporation, during which deposits of salts may be left behind on the UFC. Later, as conditions evolve and the relative humidity increases and the temperature decreases, condensation of liquid water on the UFC surfaces will produce droplets again, due to the deliquescence of minor salt deposits. In either the wetting or the drying scenario, secondary spreading and spatial separation of anodic and cathodic reactions and consequent non-uniform corrosion could be possible, due to the droplet geometry. To investigate this scenario, the quartz crystal microbalance (QCM) technique is being used. The QCM initially consists of a quartz plate, covered by gold electrodes on both sides where a layer of copper is deposited on the crystal by using magnetron sputtering. In this technique, the change in the resonance frequency of a vibrating quartz crystal is correlated to its mass change due to the corrosion process. To investigate the effect of salts and their deliquescence behaviours, different salts (NaCl, CaCl2, and MgCl2) and CR10-E simulated groundwater were loaded on the copper surface using an inkjet printer, and then corrosion tests were performed at different temperatures and relative humidity (RH) values. In parallel, a set of long-term vapour-phase corrosion tests was performed on wrought and cold-sprayed copper coupons at 75 °C and different RH values. As part of the post-experiment analysis, the corrosion products were analyzed using a suite of surface analysis techniques, including optical microscopy, Raman spectroscopy, and scanning electron microscopy (SEM). The results from QCM experiments at RH values below salts deliquescence point showed a low mass change that could correlate with less corrosion in comparison to the experiments at RH values above salts deliquescence point. It’s worth noting that even at RH values below the deliquescence point of the salts, a trace of corrosion was observed which could be indicative of the presence of monolayers of water on the surface. The results obtained from NaCl and CR10-E exposure conditions showed higher mass change and therefore higher corrosion in comparison to CaCl2 and MgCl2 salts. As for the long-term vapour-phase corrosion tests, Raman spectroscopy confirmed the presence of CuO and Cu2O on the surface as corrosion products. Further surface characterizations and mass loss measurements are underway to determine the extent of corrosion on the copper coupons.

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König, Tobias, Ron Dagan, Kathy Dardenne, Michel Herm, Volker Metz, Tim Pruessmann, Jörg Rothe, Dieter Schild, Arndt Walschburger et Horst Geckeis. « Spectroscopic and chemical investigations on volatile fission and activation products within the fuel-cladding interface of irradiated pressurised water reactor fuel rod segments ». Safety of Nuclear Waste Disposal 1 (10 novembre 2021) : 5–6. http://dx.doi.org/10.5194/sand-1-5-2021.

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Abstract. In Germany, the present waste management concept foresees the direct disposal of spent nuclear fuel (SNF) in deep geological repositories for high-level waste available by 2050, at best. Until then, SNF is encapsulated in dual-purpose casks and stored in dry interim storage facilities. Licenses for both casks and facilities will expire after 40 years following loading of the cask and emplacement of the first cask in the storage location. Yet, due to considerable delays in the site selection process and the estimated duration for construction and commissioning of a final repository of at least 2 decades, a prolonged dry interim storage of SNF is inevitable (ESK, 2015). Concerning these considerable timespans, integrity of the cladding is of utmost importance regarding the ultimately conditioning of the fuel assemblies for final disposal. Various processes strain the structural integrity of Zircaloy cladding during reactor operation and beyond such as delayed hydride cracking, fuel-cladding chemical interactions or irradiation damage induced by α-emitters present in the fuel pellet's rim zone (Ewing, 2015). Especially with higher burn-up, the gap between fuel and cladding closes and results in the formation of an interaction layer, in which precipitates of fission and activation products are present, displaying an interface for degradation processes. For chemical analysis and speciation of these agglomerates, Zircaloy-4 and SNF specimens were sampled from fuel rod segments irradiated in commercial pressurised water reactors during the 1980s. Zircaloy-4 specimens were taken from an UOX (50.4 GWdtHM-1) and mixed oxide fuel (MOX) (38.0 GWdtHM-1). In addition, SNF fragments were sampled from the closed gap of both fuel types to examine volatile activation and fission products, which had been segregated from the centre to the pellet periphery during irradiation and thus contribute to the possible chemically assisted cladding degradation effect of the precipitates within the fuel-cladding interface. Spectroscopic analysis of precipitates within the interface layer between fuel and cladding were performed by optical microscopy, X-ray absorption and X-ray photoelectron spectroscopy, as well as by energy-dispersive scanning electron microscopy. Moreover, the radionuclide inventory of the respective Zircaloy-4, fuel and interaction layers was determined using liquid scintillation counting, γ-spectroscopy, gas mass spectrometry, ion chromatography and inductive-coupled plasma mass spectrometry and compared to results received by MCNP/CINDER and webKORIGEN calculations. In this study, we provide results regarding the speciation and chemical composition of previously identified Cs-U-O-Zr-Cl-I bearing compounds found in the interaction layer of irradiated nuclear fuel and inventory analyses of radionuclides present therein, with particular emphasis on Cl-36 and I-129. Furthermore, the agglomerates within the fuel-cladding interface were characterised for the first time utilising synchrotron radiation-based Cl K-edge and I K-edge measurements, resulting in compounds with structural similarities to CsCl and CsI. The outcomes obtained from this study provide further insights into the complex chemistry within the fuel-cladding interface with respect to the aging management and integrity of SNF under the conditions of interim storage. In future studies we will examine whether the different compounds at the fuel-cladding interface have the potential to affect the mechanical properties of Zircaloy cladding.

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Muñoz, Andrés Gabriel, et Dieter Schild. « Graphite Cast Iron GGG40 for Disposal Containers : The Corrosion Mechanism in Opalinus Clay Water ». ECS Meeting Abstracts MA2023-02, n^o 12 (22 décembre 2023) : 1093. http://dx.doi.org/10.1149/ma2023-02121093mtgabs.

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The overpack of the Pollux® 10 container, taken as a reference for the storage of fuel elements in different types of host rocks, is manufactured from spheroidal graphite carbon steel (GGG 40 / 0.7040) [1]. The near field environment after emplacement is constituted by bentonite, which turns moisty, warm, and anaerobic after some decades because of the decay of the heat generation and the consumption of oxygen by reaction with the container wall, microbes, and minerals [2]. Thus, the corrosion mechanism of metal containers in these conditions is an essential issue for the design of repository concepts of radioactive waste. For a better understanding of the corrosion processes taking place at the interface of steel and saturated bentonite, electrochemical and surface chemical analysis, including SEM-EDX and local XPS were performed on steel in Opalinus Clay water under different temperatures, pH´s and pressures. Electrochemical measurements were carried out in a dedicated reactor cell for working at high temperature and high pressures (up to 150 bars). A Solartron electrochemical interface 1287 connected to a frequency analyzer 1260 was used. Polarization curves performed in deaerated solutions are characterized by a low cathodic constant current separating the onset of water reduction and the active dissolution. The presence of oxygen increases the current of the cathodic plateau shifting the corrosion potential towards more positive values. The metallographic structure of the steel give rise to local predominantly anodic and cathodic elements, i.e., ferritic, and pearlitic phases, on the one side and cementite and graphite on the other side, respectively. The dissolution of the active phases is controlled by the formation of an oxide film mainly constituted by magnetite and silicates containing Fe, Al, Mg and Cr formed by oxidation of the silicon contained in the alloy. SEM pictures obtained after 48 h of corrosion under anaerobic conditions and 5 bar of pressure show the deposition of silicates with different morphologies: as clusters of spheres and as hexagonal platellets (see fig.1). Under 100 bar of pressure, however, an rather etched aspect can be observed, revealing clearly the different metallographic phases. The impedance diagrams obtained at the corrosion potential shows an inductive loop at low frequency. Based on the shape of potentiostatic anodic current transients, the inductive loops can be ascribed to the dynamic of formation-dissolution of the interfacial oxide-silicate film. The effect of hydrostatic pressure is particularly interesting. The shiny optical aspect of the surface after corrosion under pressure can a priori be explained by the reducing atmosphere created by water reduction under these conditions. The significance of the formation of silicates is evident in the surface analysis of samples after long-term experiments in contact with Wyoming bentonite saturated with pore Opalinus Clay water. TEM pictures of a cross sectional lamella including part of graphite sphere shows the formation of a silicate film covering the corroding surface with an irregular adherence. The accumulation of silicates at the surface creates an additional barrier for the metal dissolution, which reduces the corrosion rate by a factor of thousand. References 1. T. Hassel, A. Köhler, Ö.S. Kurt, Das ENCON-Behälterkonzept – Generische Behältermodelle zur Einlagerung radioaktiver Reststoffe für den interdisziplinären Optionsvergleich, ENTRIA-Arbeitsbericht-16, Institut für Werkstoffe, Leibniz-Universität Hannover (2019), Hannover, Germany. 2. F. King, C. Padovani, Corros. Eng. Sci. Technol. 46 (2011), 82-90. Figure 1: SEM pictures of the surface of GGG40 after corrosion during 48 h in anoxic Opalinus Clay water at 30°C and p: 5 bar Figure 1

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ADEOYE, Nathaniel Olugbade, et Collins Chidiebele OKELEKE. « Geospatial Analysis of Lagos State Landfill Site Suitability and Multi-Criteria Spatial Decision Support System ». Journal of Geospatial Science and Technology 3, n^o 1 (9 juin 2022) : 36–56. http://dx.doi.org/10.54222/afrigist/jgst/v3i1.4.

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Landfill siting is an extremely complex task, mainly because of the process and strict regulations engrossed. This study determined the suitability of Lagos State landfill sites by combining geographic information system (GIS) and multi-criteria decision-making method (MCDM) known as the analytic hierarchy process (AHP). A global Positioning System (GPS) receiver was used to acquire the x and y coordinates of the existing landfills. These were interpolated on the administrative map of the study area to show their spatial pattern. Environmental Protection Agency (EPA) landfill site selection criteria were afterwards used to identify set standards and requirements for the optimum landfill site. Landsat 7 ETM+2012 was utilized to analyze various land uses around the existing landfills in the study area while ASTER DEM was used to assess the elevation of the study site. The imageries were enhanced and geo-referenced for correct locational identity. Landsat imagery was, however, classified into different land uses using a supervised classification algorithm. The extracted spatial data were prepared in ArcMap 10.5, processed with AHP weighting/ranking operation and finally produced a suitability map, which was labelled as highly suitable, moderately suitable, less suitable and unsuitable. The results revealed that landfills in Lagos State were no longer suitable in their existing locations. Besides, only 0.001% of the total land area of the study area was identified as highly suitable, 0.119% as moderately suitable and 99.4% unsuitable for the landfill sites. In conclusion, the study generated a synthesis of knowledge valuable for the planners and stakeholders in the management of urban waste. RésuméL’emplacement des décharges est une tâche extrêmement complexe, principalement en raison du processus et des réglementations strictes absorbées. Cette étude a déterminé la pertinence des sites d’enfouissement de l’État de Lagos en combinant un système d’information géographique (SIG) et une méthode de prise de décision multicritère (MCDM) connue sous le nom de processus de hiérarchie analytique (AHP). Le récepteur du système de positionnement global (GPS) a été utilisé pour acquérir les coordonnées x, y des sites d’enfouissement existants. Ceux-ci ont été interpolés sur la carte administrative de la zone d’étude pour montrer leur modèle spatial. Les critères de sélection des sites d’enfouissement de l’Agence de protection de l’environnement (EPA) ont ensuite été utilisés pour déterminer les normes et les exigences relatives à un site d’enfouissement optimal. Landsat 7 ETM+2012 a été utilisé pour analyser diverses utilisations des terres autour des sites d’enfouissement existants dans la zone d’étude, tandis qu’ASTER DEM a été utilisé pour évaluer l’élévation du site d’étude. Les images ont été améliorées et géoréférencées pour une identité de localisation correcte. L’imagerie Landsat a toutefois été classée en différentes utilisations des terres à l’aide d’un algorithme de classification supervisé. Les données spatiales extraites ont été préparées dans ArcMap 10.5, traitées avec une opération de pondération/classement AHP et ont finalement produit une carte d’adéquation, qui a été étiquetée comme très appropriée, modérément appropriée, moins appropriée et inappropriée. Les résultats ont révélé que les décharges de l’État de Lagos ne convenaient plus à leurs emplacements existants. En outre, seulement 0,001 % de la superficie totale de la zone d’étude a été identifiée comme hautement appropriée, 0,119 % comme modérément appropriée et 99,4 % impropre au site d’enfouissement. En conclusion, l’étude a généré une synthèse des connaissances précieuses pour les planificateurs et les parties prenantes de la gestion des déchets urbains.

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Ibragimov, Iskander, et Evangelos Moulas. « The role of continental-margin architecture on models of ophiolite emplacement ». Journal of the Geological Society, 16 novembre 2023. http://dx.doi.org/10.1144/jgs2023-063.

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Ophiolite obduction, the process by which part of the oceanic crust overlaps the continental margin, is challenging when it comes to the geodynamic reconstruction of lithospheric processes. This buoyancy difference between dense oceanic crust and the relatively buoyant continental crust makes the obduction of the oceanic crust difficult, if not impossible, when only buoyancy forces are considered. To overcome the difficulties posed by the negative buoyancy, the initial configuration of the oceanic basins must have specific thermal and geometric constraints. Here we present a systematic investigation of the geometrical and the geodynamical parameters which control the ophiolite emplacement process. Our study reveals which parameters are the most important during ophiolite emplacement and which are the most optimal geometries that favour ophiolite emplacement. We focus on “Tethyan” ophiolites which are characterized by relatively small inferred basin size and are commonly found in Mediterranean region. Based on a combination of various parameters, we identified the most susceptible configurations for ophiolite obduction. Our models demonstrate, in agreement to geological data, that the obducted lithosphere must be young and the length of the Ocean-Continent-Transition zone must be relatively sharp in order to achieve ophiolite obduction. Thematic collection: This article is part of the Ophiolites, melanges and blueschists collection available at: https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists Supplementary material: https://doi.org/10.6084/m9.figshare.c.6922526

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Berg, H. P., D. Ehrlich et B. Thomauske. « Safety Analysis and Comparison of Toxicities for the Disposal of Radioactive Waste of Negligible Heat Generation Including Transuranic Elements ». MRS Proceedings 127 (1988). http://dx.doi.org/10.1557/proc-127-545.

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ABSTRACTRequirements on radioactive waste of negligible heat generation with respect to transuranic elements, derived from the safety analysis of the operational phase of the Konrad repository, are described and resulting activity limitations are discussed. For assessing the long term safety, the calculation of individual doses in connection with the very slow water movements and, additionally, toxicity comparisons to other waste and to the natural toxicity at the site are discussed. Some information is given on the procedure of taking into account the activity limitations in an optimal way when planning emplacement campaigns.

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Zagorscak, Renato, Richard Metcalfe, Thomas G. Robson et Jennifer A. Wilson. « A Methodology for Deciding on Well Seal Options for Abandonment ». Energy Geoscience Conference Series 1, n^o 1 (16 septembre 2024). http://dx.doi.org/10.1144/egc1-2024-14.

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The energy transition to achieve net zero anthropogenic CO 2 emissions will require permanently sealing and abandoning wells or boreholes drilled for many different purposes, including: underground CO 2 storage; hydrogen storage; geothermal energy extraction; site characterisation for radioactive waste repositories; and hydrocarbon extraction. It is necessary to objectively decide what sealing materials, combination of materials and methods of emplacement are optimal for a given well sealing project, taking into account the properties of lithologies penetrated, the physical and geochemical conditions around the well, the geometry of the well, and characteristics of well engineering. A workflow that would allow for a structured approach to designing well seals during well decommissioning and a set of complementary tools that will enable an informed, structured, transparent and traceable process for designing a well decommissioning sealing solution for a particular well in a given geological environment is presented in this paper. The tools include: 1) a database of Features Events and Processes; 2) a decision tree for evaluating different well sealing options and for documenting the rationale for decisions; 3) an approach for comparing options using multiple decision trees; 4) and a suite of simplified numerical models to inform judgements.

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Imayanti, Indah, Sutanto Soehodho et Nahry Yusuf. « ANALYSIS OF COST AND TIME EFFICIENCY IN CONTAINER DISTRIBUTION BETWEEN CONTAINER TRUCK AND FREIGHT TRAIN FROM INDUSTRIAL AREA TO PORT ». Smart City 4, n^o 2 (25 juin 2024). http://dx.doi.org/10.56940/sc.v4.i2.8.

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Jakarta International Container Terminal (JICT) in Tanjung Priok Port , which serves export and import containers, can serve up to 5500 TEUs daily. However, no more than 1% of the total containers are transported by freight trains, meaning that 99% of container distribution from industrial areas is carried by trailer trucks. This condition causes a long queue at the container terminal entrance, resulting in delays in the services as well. Currently, Tanjung Priok Port is connected to rail transportation from Cikarang dry port with the frequency of twice a day with 30 flatcars (FC) for each trip. The capacity of one series of freight trains from Cikarang dry port to Tanjung Priok Port can reach 30 Feus or 60 Teus. However, the container distribution using freight trains is still less optimal because of the double handling at the JICT emplacement which is located outside JICT and the use of trailer trucks to move the containers from the area to JICT. The cost of transporting export and import containers always increases year by year because of the slow transportation due to inefficiency of the container depot location in Tanjung Priok area. In this research, the method used to determine the efficiency of container transportation is divided into three scenarios. The first scenario is when the container is fully transported by truck from the industrial area. The second scenario is when the container is transported by train and handled twice while entering JICT. Finally, the third scenario is when the JICT emplacement is located inside the JICT area, changing the business process of containers coming in and out, needing no stacking in the JICT container yard, relocating the container depot placement, consolidating containers, and automating equipment at JICT to reduce the cost and time of containers for export and import. After analyzing the costs and time of the three scenarios, it was found that the third scenario could reduce travel costs and shorten container time when exporting and importing. The 3rd scenario can reduce the cost by almost 50% from the 1st and 2nd scenarios due to container consolidation.

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Leong, Timothy S. J., John A. Mavrogenes et Richard J. Arculus. « Water-sulfur-rich, oxidised adakite magmas are likely porphyry copper progenitors ». Scientific Reports 13, n^o 1 (28 mars 2023). http://dx.doi.org/10.1038/s41598-023-31736-z.

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AbstractThe world’s largest current Cu resource is volcanic arc-hosted, porphyry copper deposits. Whether unusual parental magmas or fortuitous combinations of processes accompanying emplacement of common parental arc magmas (e.g., basalt) is required for ore deposit formation, remains unclear. Spatial and tectonic associations of adakite (andesite with high La/Yb, Sr/Y) with porphyries exist, but genetic links are debated. Delayed saturation with Cu-bearing sulfides consequent to elevated redox state seems essential for late-stage exsolution of Cu-bearing hydrothermal fluids. Partial melting of igneous layers of subducted, hydrothermally altered oceanic crust in the eclogite stability field are invoked to account for andesitic compositions, residual garnet signatures, and the putative oxidised character of adakites. Alternative petrogeneses include partial melting of lower crustal, garnet-bearing sources and extensive intra-crustal amphibole fractionation. Here we demonstrate mineral-hosted, adakite glass (formerly melt) inclusions in lavas erupted subaqueously in the New Hebrides arc are oxidised relative to island arc (and mid-ocean ridge) basalts, are H2O-S-Cl-rich, and moderately enriched in Cu. Polynomial fitting of chondrite-normalised, rare earth element abundance patterns shows the precursors of these erupted adakites were unequivocally derived from partial melting of subducted slab, and represent optimal porphyry copper progenitors.

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Collins, Rebecca. « The intimate socialities of going carbon neutral ». Transactions of the Institute of British Geographers, 17 novembre 2023. http://dx.doi.org/10.1111/tran.12658.

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AbstractThis paper argues that the generation of social intimacy is critical to enabling acts of environmental care. By interrogating the intimate socialities of a group of young people who grew up in a village community committed to carbon reduction, I untangle the influence of everyday intimacies on everyday (un)sustainabilities, particularly in relation to the popular but uncritical positioning of young people as ‘sustainability saviours’. I problematise assumptions that young people's social intimacies are a straightforward enabler of lifestyle change aligned with sustainability by highlighting the fluidity of intimacies and associated senses of trust throughout young adulthood. I argue further that capitalising on this fluidity might in fact amplify bottom‐up environmental care if young people can move readily between networked spaces of trust and support. Drawing from scholarship on friendship, family and community intimacies and the substantial literature on households as crucibles for more sustainable living, I suggest there is considerable reconciliation work demanded at a personal level in order to live comfortably within the everyday intimacies of social life at the same time as committing to individual environmental action. These arguments advance debates around the optimal social drivers of more sustainable lifestyles, at the same time as sounding a cautionary note in relation to the too easy emplacement of responsibility for driving change at the feet of young people.

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Kovalick, Alex, Andy W. Heard, Aleisha C. Johnson, Clara S. Chan, Luke Ootes, Sune G. Nielsen, Nicolas Dauphas, Bodo Weber et Andrey Bekker. « Living in Their Heyday : Iron‐Oxidizing Bacteria Bloomed in Shallow‐Marine, Subtidal Environments at ca. 1.88 Ga ». Geobiology 22, n^o 6 (novembre 2024). https://doi.org/10.1111/gbi.70003.

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ABSTRACTThe majority of large iron formations (IFs) were deposited leading up to Earth's great oxidation episode (GOE). Following the GOE, IF deposition decreased for almost 500 Myr. Subsequently, around 1.88 Ga, there was widespread deposition of shallow‐water granular iron formations (GIF) within a geologically short time interval, which has been linked to enhanced iron (Fe) supply to seawater from submarine hydrothermal venting associated with the emplacement of large igneous provinces. Previous studies of Fe‐rich, microfossil‐bearing stromatolites from the ca. 1.88 Ga Gunflint Formation on the Superior craton suggested direct microbial oxidation of seawater Fe2+(aq) by microaerophilic, Fe‐oxidizing bacteria (FeOB), as a driver of GIF deposition. Although Fe‐rich, microfossil‐bearing stromatolites are common in 1.88 Ga GIF deposits on several cratons, combined paleontological and geochemical studies have been applied only to the Gunflint Formation. Here, we present new paleontological and geochemical observations for the ca. 1.89 Ga Gibraltar Formation GIFs from the East Arm of the Great Slave Lake, Northwest Territories, Canada. Fossil morphology, Rare Earth element (REE) concentrations, and Fe isotopic compositions support Fe oxidation by FeOB at a redoxcline poised above the fair‐weather wave base. Small positive Eu anomalies and positive εNd (1.89 Ga) values suggest upwelling of deep, Fe‐rich, hydrothermally influenced seawater. While high [Fe2+(aq)] combined with low atmospheric pO2 in the late Paleoproterozoic would have provided optimal conditions in shallow oceans for FeOB to precipitate Fe oxyhydroxide, these redox conditions were likely toxic to cyanobacteria. As long as local O2 production by cyanobacteria was strongly diminished, FeOB would have had to rely on an atmospheric O2 supply by diffusion to shallow seawater to oxidize Fe2+(aq). Using a 1‐D reaction dispersion model, we calculate [O2(aq)] sufficient to deplete an upwelling Fe2+(aq) source. Our results for GIF deposition are consistent with late Paleoproterozoic pO2 estimates of ~1%–10% PAL and constraints for metabolic [O2(aq)] requirements for modern FeOB. Widespread GIF deposition at ca. 1.88 Ga appears to mark a temporally restricted episode of optimal biogeochemical conditions in Earth's history when increased hydrothermal Fe2+(aq) sourced from the deep oceans, in combination with low mid‐Paleoproterozoic atmospheric pO2, globally satisfied FeOB metabolic Fe2+(aq) and O2(aq) requirements in shallow‐marine subtidal environments above the fair‐weather wave base.

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Beccaro, Lisa, Matteo Albano, Cristiano Tolomei, Claudia Spinetti, Giuseppe Pezzo, Mimmo Palano et Claudio Chiarabba. « Insights into post-emplacement lava flow dynamics at Mt. Etna volcano from 2016 to 2021 by synthetic aperture radar and multispectral satellite data ». Frontiers in Earth Science 11 (15 septembre 2023). http://dx.doi.org/10.3389/feart.2023.1211450.

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Post-emplacement dynamics of lava flows is governed by several factors such as poroelastic deformation of the substrate; gravity-induced repacking and rearrangement of the vesicle-bearing fluid lava and other void spaces by superposed flows; lava densification processes; viscoelastic strain relaxation of the ground caused by the lava load; thermal cooling and contraction of the solid lava; and discrete motion of surface blocks. Here we investigate post-emplacement lava flow dynamics at the Mt. Etna volcano, and we infer on the possible causes by exploiting optical and radar satellite data. Synthetic aperture radar data from Sentinel-1 satellite mission provided high-resolution horizontal and vertical displacement rates and displacement time series of the lava flows emplaced on the Mt. Etna volcano summit from January 2016 to July 2021. Sentinel-2 multispectral data allowed to identify the lava flows boundaries emplaced during the December 2018 and May 2019 paroxysms. Finally, high resolution COSMO-SkyMed radar data allowed to account for the topographic changes generated by the lava emplacement by means of stereo radargrammetry technique. Such an unprecedented dataset provided a full picture of the lava flow dynamics, whose kinematics is governed lava cooling, which in turn produce thermal contraction of the lava body and viscous compaction of the underlying substrate. Both phenomena act at different periods, being the thermal contraction predominant for recent lava flows. Downslope sliding is also invoked, especially for recent lava flows emplaced on high slope areas.

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Dellefant, Fabian, Lina Seybold, Claudia A. Trepmann, Stuart A. Gilder, Iuliia V. Sleptsova, Stefan Hölzl et Melanie Kaliwoda. « Emplacement of shocked basement clasts during crater excavation in the Ries impact structure ». International Journal of Earth Sciences, 19 avril 2024. http://dx.doi.org/10.1007/s00531-024-02403-z.

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AbstractIn the Aumühle quarry of the Ries impact structure, moderately shocked clasts from the Variscan basement occur sandwiched between overlying suevite and components derived from the Mesozoic sedimentary cover of the underlying Bunte Breccia without distinct shock effects. We analyzed the clasts by optical microscopy, scanning electron microscopy (SEM/EDS/EBSD), and Raman spectroscopy to unravel their emplacement relation to the overlying suevite and the sediment-rock clasts of the Bunte Breccia. Clasts sizes range up to few decimeters and are embedded in a fine-grained lithic matrix; no impact-melt fragments are observed. Amphibolite clasts contain maskelynite with few lamellar remnants of feldspar, indicating shock pressures of 28–34 GPa. Amphiboles have cleavage fractures and ($$\overline{1}$$ 1 ¯ 01) mechanical twins suggesting differential stresses > 400 MPa. Felsic gneiss components have optically isotropic SiO2 indicative of shock pressures ≈35 GPa. Metagranite cataclasite clasts contain shocked calcite aggregates and quartz with a high density of fine rhombohedral planar deformation features indicating shock pressures ≈20 GPa. The moderately shocked basement clasts originate from deeper levels of the transient cavity and lower radial distance to the center of the structure compared to the sediment-rock clasts. Both were ballistically ejected during crater excavation. In accordance with palaeo- and rock magnetic data, they were mixed during turbulent deposition at the top of the Bunte Breccia before the emplacement of suevite. The high amount of basement clasts below suevite and on top of the underlying Bunte Breccia is consistent with the commonly reported inverse stratigraphy in the Ries impact structure. Graphical Abstract

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Bakker, Ronald J., Evgenii Pushkarev et Anna P. Biryuzova. « High Temperature Reduced Granulite-Facies Nature of Garnetites in the Khabarny Mafic–Ultramafic Massif, Southern Urals : Evidence from Fluid and Mineral Analyses ». Journal of Petrology 61, n^o 6 (juin 2020). http://dx.doi.org/10.1093/petrology/egaa066.

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Abstract High-grade metamorphic rocks underlying the intrusive layered dunite–pyroxenite–gabbronorite East-Khabarny Complex (EKC) are integrated in the complex Khabarny mafic–ultramafic Massif in the Sakmara Allochthon zone in the Southern Urals. These rocks are associated with high-temperature shear zones. Garnetites from the upper part of the metamorphic unit close to the contact with EKC gabbronorite are chemically and texturally analysed to estimate their formation conditions and fluid regime. Fluids provide crucial information of formation conditions and evolution of these garnetites during high-grade metamorphism, and are preserved in channel positions within Si6O1812- rings of cordierite, and in fluid inclusions in quartz and garnet. Minerals and fluid inclusions of the garnetites are studied with X-ray fluorescence spectrometry, electron microprobe analyses, Raman spectroscopy, and microthermometry. The garnetites mainly consist of garnet (up to 80 vol. %), cordierite and quartz. Accessory minerals are rutile, ilmenite, graphite, magnetite and cristobalite. Granulite-facies metamorphic conditions of the garnetites are estimated with the garnet–cordierite–sillimanite–quartz geothermobarometer: temperatures of 740 to 830 ˚C and pressures of 770–845 MPa. The average garnet composition in end-member concentrations is 48·5 mole % almandine (±3·9), 34·7 mole % pyrope (±3·3), 10·3 mole % spessartine (±1·1), 1·8 mole % grossular (±1·5), and 1·5 mole % andradite (±1·5). The cordierite electron microprobe analyses reveal an average Mg2+ fraction of 0·79 ± 0·01 in the octahedral site. Relicts of a strong positive temperature anomaly (up to 1000 ˚C) are evidenced by the preservation of cristobalite crystals in garnet and the high titanium content of quartz (0·031 ± 0·008 mass % TiO2) and garnet (0·31 ± 0·16 mole % end-member Schorlomite-Al). The fluid components H2O, CO2, N2 and H2S are detected in cordierite, which correspond to a relatively oxidized fluid environment that is common in granulites. In contrast, a highly reduced fluid environment is preserved in fluid inclusions in quartz nodules, which are mono-fluid phase at room temperature and composed of CH4 (>96 mole %) with locally minor amounts of C2H6, N2, H2S and graphite. The fluid inclusions occur in homogeneous assemblages with a density of 0·349 to 0·367 g·cm-3. The CH4-rich fluid may represent peak-temperature metamorphic conditions, and is consistent with temperature estimation (∼1000 ˚C) from Ti-in-garnet and Ti-in-quartz geothermometry. Tiny CH4-rich fluid inclusions (diameter 0·5 to 2 µm) are also detected by careful optical analyses in garnet and at the surface of quartz crystals that are included in garnet grains. Graphite in fluid inclusions precipitated at retrograde metamorphic conditions around 300–310 ± 27 ˚C. Aragonite was trapped simultaneously with CH4-rich fluids and is assumed to have crystallized at metastable conditions. The initial granulite facies conditions that led to the formation of a cordierite and garnet mineral assemblage must have occurred in a relative oxidized environment (QFM-buffered) with H2O–CO2-rich fluids. Abundant intrusions or tectonic emplacement of mafic to ultramafic melts from the upper mantle that were internally buffered at a WI-buffered (wüstite–iron) level must have released abundant hot CH4-rich fluids that flooded and subsequently dominated the system. The origin of the granulite-facies conditions is similar to peak-metamorphic conditions in the Salda complex (Central Urals) and the Ivrea–Verbano zone (Italian Alps) as a result of magmatic underplating that provided an appearance of a positive thermal anomaly, and further joint emplacement (magmatic and metamorphic rocks together) into upper crustal level as a high temperature plastic body (diapir).

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Xu, Duonian, Yongqiang Qu, Linjun Huang, Chao Dai, Ruipu Hu et Xun Kang. « Authigenic calcite as a record of geologic fluids in siliciclastic rocks : Evidences from the Upper Permian Wuerhe Formation, Junggar basin, NW China ». Frontiers in Earth Science 10 (11 janvier 2023). http://dx.doi.org/10.3389/feart.2022.1007902.

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The identification of geologic fluids and related fluid–rock interactions during diagenesis is the subject of much research in sedimentary petrology. Authigenic calcite potentially provides a record of geologic fluids and it occurs heterogeneously in the Upper Permian Wuerhe Formation (P3w) in the Shawan Sag, Junggar Basin, which has a complex history of geologic fluid activity. This provides an ideal opportunity to study the effectiveness of authigenic calcite in tracing fluids. We conducted optical, cathodoluminescence (CL), and scanning electron microscopic observations, as well as the major and trace element and stable carbon and oxygen isotopes of authigenic calcite. The results show that three generations of calcite were precipitated in the P3w Formation, and the diagenetic fluid was affected to varying degrees by paleo-meteoric water and hydrocarbon-bearing fluids. During early diagenesis, diagenetic fluid with low Mn contents precipitated the amorphous early-stage calcite (dark red in CL images, MnO <1.5%, δ13C = −8.6‰ to 2.1‰, VPDB). Its carbon source was mainly meteoric CO2. During mesodiagenesis, the limited hydrocarbon emplacement during the Middle Jurassic enriched the pore fluids in Mn and 13C-depleted organic derived CO2, subsequently precipitating the late-stage sparry calcite I (orange in CL images with MnO of 2.5%–4% and δ13C of −14.5‰ to −8.1‰). The carbon in this calcite came from the dissolution of early-stage calcite and CO2 generated by decarboxylation of organic acids. During the Early Cretaceous, large-scale hydrocarbon charging occurred and the pore fluids were further enriched in Mn and organic derived CO2, eventually precipitating the late-stage sparry calcite II (bright yellow in CL images with MnO of >4% and δ13C of −25.7‰ to −14.9‰). Its carbon source was mainly CO2 produced by the decarboxylation of organic acids. The precipitation of abundant late-stage sC-depleted calcite suggests that the hydrocarbons were oxidized to organic acids in the reservoir. The two periods of hydrocarbon charging caused the dissolution of laumontite and the early-stage calcite, forming secondary minerals and dissolution pores, which increased the porosity and permeability of the rock. Therefore, authigenic calcite is a useful tracer of fluid properties, fluid–rock interactions, and alteration processes in petroliferous basins.

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