Search

The Astaneh Fault is one of the active and seismic faults in the Shahroud sinistral fault system. Fault gouges can be seen in a completely pristine and unchanged form in the portions of this fault that have affected the carbonate rocks. Fault gouges are the direct product of lithology and are formed as a result of the fault slip from the host rocks. Studying these rocks for type, composition, mineralogical phases and structure can provide results on how the fault slip and gouge process occurs. The result of a seismic slip in faults, and especially in gouges, are different types of deformations, such as mineralogical and compositional deformations, depending on the conditions of their formation. From this deformation model, we can mention the thermal decomposition of calcite and dolomite, as well as the presence of siderite in gouges. In this article, by studying the combined [aggregated] microstructures in the Astaneh fault gouge, their relationship with seismic slip has been investigated. According to previous research, the Astaneh Fault is certainly a seismic fault. The presence of the resulting thermal decomposition of calcite and dolomite (calcium and magnesium oxide or periclase) and the welding of particles due to heat may be the key to seismic slip in this fault. [ABSTRACT FROM AUTHOR]

Copyright of Spanish Journal of Palaeontology is the property of Socieadad Espanola de Paleontologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, a mineralogical study and thermal decomposition analysis of jarosite residue sample from a zinc plant were carried out. The mineralogical analysis showed that the jarosite residue is mainly composed of four components, including jarosites, sulfates–hydroxides, sulfides and spinel. The distribution of relevant metallic elements in these components was characterized using a sequential extraction process. The X-ray diffraction results showed that AFe3(OH)6(SO4)2 and ZnFe2O4 are the main components of the jarosite residue sample. The thermal decomposition mechanisms of ammoniojarosite and sodium jarosite were studied by TG-DSC (Thermogravimetric analysis–differential scanning calorimetry). The thermal decomposition process and the corresponding mechanism of the jarosite residue were analyzed. The jarosite thermal decomposition process includes the removal of crystal water, dihydroxylation and deammoniation, desulfonation of component jarosite and desulfonation of component zinc sulfate. [ABSTRACT FROM AUTHOR]

In this work, a mineralogical study and thermal decomposition analysis of jarosite residue sample from a zinc plant were carried out. The mineralogical analysis showed that the jarosite residue is mainly composed of four components, including jarosites, sulfates–hydroxides, sulfides and spinel. The distribution of relevant metallic elements in these components was characterized using a sequential extraction process. The X-ray diffraction results showed that AFe3(OH)6(SO4)2 and ZnFe2O4 are the main components of the jarosite residue sample. The thermal decomposition mechanisms of ammoniojarosite and sodium jarosite were studied by TG-DSC (Thermogravimetric analysis–differential scanning calorimetry). The thermal decomposition process and the corresponding mechanism of the jarosite residue were analyzed. The jarosite thermal decomposition process includes the removal of crystal water, dihydroxylation and deammoniation, desulfonation of component jarosite and desulfonation of component zinc sulfate.

Mineral liberation is an important variable to be considered in the iron ore geometallurgical studies, especially since it provides information leading to the understanding of the ore's behaviour in the beneficiation process, mainly when harder ores are concerned. Nowadays, the professionals and researchers in the mineral industry have been using complementary techniques for mineralogical characterization. In this way, Mineral Liberation Analyser (MLA) and optical microscopy are amongst the most efficient and important tools in these studies. Together, these techniques can provide information leading to the development of geometallurgical models, including the degree of quartz liberation, mineral modal composition, mineralogical association and particle and mineral size distribution, as well as the spectrum of mineral liberation either by free surface or particle composition. The purpose of this study is to compare the degree of quartz liberation in four different iron ore types observed in optical microscopy and MLA. It also assesses the influence of mineral liberation in the quality of the resulting concentrate, according to the SiO2 content. All the results of the various quartz liberation degrees, determined by both MLA and optical microscopy were very close, as well as the correlation between the mineral liberation and the ore's response in the flotation process. The investigation provided evidence that the mineral liberation study is an important tool in the prediction of the ore's behaviour in the beneficiation process. [ABSTRACT FROM AUTHOR]

The Thelon Basin is temporally and spatially related to the Athabasca Basin in Saskatchewan, Canada, which hosts the highest-grade unconformity-related uranium deposits in the world. Several uranium deposits occur within the Aberdeen sub-basin of the Thelon Basin, and it has been suggested that they may also be unconformity-related deposits. However, the genesis of the deposits is still debated and the age of the uranium mineralization event remains loosely constrained. In this study, we use secondary ion mass spectrometry to measure three sulphur (S) isotopes in pyrite from the Kiggavik deposit to constrain the sources of sulphur. We use this information to determine whether these sulphides, if dated by the Re--Os method, would provide a better constraint on the timing of uranium mineralization. The Kiggavik deposit comprises three zones (Main, Centre, and East) that formed from ~200 [degrees]C fluids at ~1600 Ma. Non-hydrothermal pyrite and galena from all three zones have a wide range of [delta][.sup.34]S values, from-41.2[per thousand] to+37.4[per thousand]. The A[.sup.33]S values (>0[per thousand]) indicate recycling of mass independent fractionation sulphur, suggesting that pyrite from the Kiggavik deposit derived sulphur from the Neoarchean metagraywacke host rock. The preservation of these anomalous [DELTA][.sup.33]S values suggests that the pyrite formed from low-temperature processes rather than hydrothermal processes. Low-temperature, high-latitude fluids may have been involved in the formation of the pyrite because some of these sulphides are also associated with uranium minerals that are devoid of Pb and contain corroded calcite. Based on these data, Re--Os geochronology of these sulphides would not yield an age that would constrain the timing of hydrothermal uranium mineralization. Key words: Thelon Basin, Kiggavik, uranium mineralization, sulphur isotopes, secondary ion mass spectrometry (SIMS), isotope geochemistry. Le bassin de Thelon est associé dans le temps et l'espace au bassin d'Athabasca en Saskatchewan (Canada), qui est l'hôte des gisements d'uranium associés àune discordance les plus riches du monde. Plusieurs gisements uranifères sont présents dans le sous-bassin d'Aberdeen du bassin de Thelon, et il a été suggéré qu'il pourrait s'agir de gisements associés à des discordances. La formation de ces gisements fait toujours débat, et l'âge de l'épisode de minéralisation uranifère n'est qu'approximativement établi. Dans la présente étude, nous utilisons la spectrométrie de masse d'ions secondaires pour mesurer trois isotopes du soufre (S) dans de la pyrite du gisement de Kiggavik pour déterminer les sources du soufre. Nous utilisons cette information pour établir si la datation de ces sulfures par la méthode Re--Os permettrait de mieux délimiter le moment de la minéralisation uranifère. Le gisement de Kiggavik comprend trois zones (principale, centrale et est) qui ont été formées par des fluides à ~200 [degrees]C vers 1600 Ma. De la pyrite et de la galène non hydrothermales provenant des trois zones définissent de grandes fourchettes de valeurs de [delta][.sup.34]S allant de -41, 2[per thousand] à +37,4[per thousand]. Les valeurs de [DELTA][.sup.33]S (>0[per thousand]) témoignent du recyclage de soufre issu du fractionnement indépendant de la masse, ce qui indiquerait que la pyrite du gisement de Kiggavik comprend du soufre provenant du métagrauwacke néoarchéen encaissant. La préservation de ces valeurs anormales de [DELTA][.sup.33]S donne à penser que la pyrite s'est formée par des processus de basse température plutôt que des processus hydrothermaux. Des fluides de haute latitude et de basse température pourraient être intervenus dans la formation de la pyrite puisque certains de ces sulfures sont aussi associés à des minéraux d'uranium exempts de Pb et contiennent de la calcite corrodée. À la lumière de ces données, la géochronologie Re--Os de ces sulfures ne donnerait pas un âge qui délimiterait le moment de la minéralisation uranifère hydrothermale. [Traduit par la Rédaction] Mots-clés: bassin de Thelon, Kiggavik, minéralisation uranifère, isotopes du soufre, la spectrométrie de masse d'ions secondaires (SIMS), géochimie isotopique., Introduction Mining of Proterozoic unconformity-related uranium deposits produces ~30% of the world's uranium (OECD 2018). They are generally high-grade and medium tonnage deposits (Lambert et al. 2005) that are associated [...]