Articles de revues : « Crystalline Granite »

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Conliffe, J., et M. Feely. « Fluid inclusions in Irish granite quartz : monitors of fluids trapped in the onshore Irish Massif ». Earth and Environmental Science Transactions of the Royal Society of Edinburgh 101, n^o 1 (20 décembre 2010) : 53–66. http://dx.doi.org/10.1017/s1755691010009047.

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ABSTRACTFluid inclusion studies of granite quartz provide an opportunity to study fluid flow associated with igneous activity and post-emplacement fluid processes. This study presents new fluid inclusion data from the late Caledonian Donegal granites and Newry granodiorite, and the Tertiary Mourne Mountains granite in Ireland, which identify three distinct fluids. Aqueous-carbonic fluids (Type 1) have been recorded in late Caledonian granites with a significant mantle component (Newry granodiorite and the Ardara and Thorr granites in Donegal). These fluids represent late-magmatic fluids trapped at high temperatures (up to 575°C), and the ultimate source of these carbonic fluids is linked to sub-lithospheric processes during the Caledonian orogeny. The dominant fluid type (Type 2) in late Caledonian granites is a H2O+NaCl±KCl fluid which may be related to thermal convection cells around granite bodies and/or to regional scale influx of surface derived fluids at the end of the Caledonian orogeny. High salinity NaCl–CaCl2 fluids (Type 3) overprint quartz in the Ardara granite in Donegal, and in the Newry granodiorite, and are interpreted to represent basinal brines, sourced in overlying sedimentary basins, which circulated through the crystalline basement during a period of crustal extension (possibly during the Carboniferous or the Triassic). Fluid inclusion studies of the Tertiary Mourne Mountains granites have identified only Type 2 fluids related to thermal convection cells, consistent with stable isotope evidence, which indicates that this younger granite is unaffected by regional-scale fluid influxes.

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Lin, J. Q., F. Ding, C. H. Chen et T. Shen. « Zircon U–Pb geochronology, Hf isotope composition, and petrochemical characteristics of Paleocene granitoids in the western Gangdese Belt, Tibet ». Russian Geology and Geophysics 62, n^o 6 (1 juin 2021) : 666–84. http://dx.doi.org/10.2113/rgg20194131.

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Abstract —The research team studied the petrology, whole-rock geochemistry, zircon U–Pb age, and stable isotopic characteristics of the Rongguo Longba and Garongcuo granites of the Nuocang area to understand better the impact of Neo-Tethys ocean subduction and In-dia–Eurasia continental collision on Paleocene tectonomagmatic processes along the southern margin of the Gangdese Belt. The Rongguo Longba granite and Garongcuo granite porphyry formed at 61.86 and 62.17 Ma, respectively. The Nuocang granitoids are characterized by (1) high SiO2, NaO2, and Al2O3 contents and low FeOtot, MgO, and TiO2 contents; (2) LREE and LILE enrichment and HREE and HFSE (Nb, P, and Ti) depletion; and (3) obvious negative Eu anomalies. These features indicate that the Nuocang granites are of the high-K calc-alkaline and peraluminous granite types. Furthermore, their zircon Hf isotope characteristics suggest that the magma source region has an ancient crystalline basement. The basaltic andesitic crystal tuff is the product of garnet–peridotite partial melting and crust contamination from rising magma emplacement.

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Petrov, V. A., M. Lespinasse, V. V. Poluektov, S. A. Ustinov et V. A. Minaev. « Scale effect in a fluid-conducting fault network ». Геология рудных месторождений 61, n^o 4 (13 août 2019) : 3–14. http://dx.doi.org/10.31857/s0016-77706143-14.

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The data presented in the article consistently outlines the methodology for studying the orientation and morphogenetic characteristics of fracture systems of four scale levels including kilometers, meters, centimeters and millimeters. The Urtuisky granite massif, located in the South-Eastern Transbaikalia to the west of the Streltsovsky caldera, containing uranium deposits unique in their reserves was chosen as the object of the research. The massif is composed of Late Riphean granites and granite-gneisses, affected by dynamometamorphic and hydrothermal-metasomatic transformations in various degrees, and dissected by numerous faults with traces of fluid activity of various tectogenesis episodes. The interrelation between such geometrical parameters of fractures systems as specific density and specific length was established. It is shown that such geostructural data should be used for conceptual and numerical modeling of fluid filtration and radionuclides transport processes occurring in a three-dimensional fractured-pore space of crystalline rocks, as applied to the reconstruction and modeling of uranium ore formation and use of geological space for radioactive materials isolation.

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Blum, Joel D. « A petrologic and Rb–Sr isotopic study of intrusive rocks near Fairbanks, Alaska ». Canadian Journal of Earth Sciences 22, n^o 9 (1 septembre 1985) : 1314–21. http://dx.doi.org/10.1139/e85-135.

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Epizonal granodiorite and granite plutons intrude the northwestern portion of the Yukon Crystalline Terrane near Fairbanks, Alaska. Mineralogic, major-oxide, and trace-element studies indicate that the plutons represent a comagmatic fractionation suite. A Rb–Sr whole-rock isochron for one pluton yields an age of 90.9 ± 0.9 Ma, in agreement with previous K–Ar dating of biotite and hornblende and an initial 87Sr/86Sr ratio of 0.71238 ± 0.00014. The elevated initial 87Sr/86Sr ratio suggests that the plutons may have had a different source from that of the belt of subduction-related, mid-Cretaceous plutonic rocks found farther to the southeast in the Yukon Crystalline Terrane. In contrast, they appear to have been formed at least in part by anatectic melting of Late Proterozoic or early Paleozoic crustal rocks. Comparison of aplite dike compositions with the synthetic granite system, estimates of average uplift rate, and K–Ar cooling ages of surrounding schists all indicate that the magmas that formed the plutons near Fairbanks intruded much higher into the crust after anatectic melting and crystallized at a relatively shallow depth of 3–5 km.

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Kang, Jun Feng, Jin Shu Cheng, Jing Wang, Yan Sheng Hou et Shao Yang Qian. « Preparation and Properties of CaO-MgO-Al₂O₃-SiO₂ Glass-Ceramics from Granite Wastes ». Materials Science Forum 890 (mars 2017) : 312–16. http://dx.doi.org/10.4028/www.scientific.net/msf.890.312.

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Granite process industry generates a large amount of wastes, which pollute and damage the environment. This work aims to investigate the possibilities of using the granite sawing wastes in the production of glass-ceramics. Granite wastes with other components were used to prepare glass-ceramics. The crystallization behavior and properties of the glass-ceramics were investigated. The results showed that the activation energy for crystallization (Ec) was 463 kJ/mol and Avrami parameter (n) was 2.68, suggested a two dimension crystal growth mechanism. The main crystalline phase of all the obtained glass-ceramics was diopside. With the increase of heat treatment temperature, the diffraction peak intensity of diopside firstly increased and then decreased slightly. The minor crystalline phases spinel and Mg4Al2Ti9O25 were observed above 970°C. When heated at 970 °C for 1h, the sample exhibited the highest Vicker's hardness and bending strength values, 7.3 GPa and 151 MPa, respectively. And the glass-ceramics showed better acid resistant than alkali resistant.

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Stepanyuk, L. M., N. M. Konoval, O. B. Visotskiy, T. I. Dovbush et O. V. Bilan. « Uranium-lead age of granites Chigirin massif ». Geochemistry and ore formation 41 (2020) : 77–82. http://dx.doi.org/10.15407/gof.2020.41.077.

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The age of granites of the Chyhyryn massif – 2040.0 ± 1.1 million years – was determined by the uranium-lead isotope method for accessory monazite. According to the results of mineral studies of zircon crystals, the conclusion that granites this mass, as well as granitoids of Novoukrainsky, is formed due to the crust, which indicates the presence of relict nuclei of substrate rocks in the middle of the crystals of this mineral. It is proposed to combine in one (for example, Kropyvnytskyi) complex All two-field spar granitoids of the Ingul megablock, leaving in the composition of the new Ukrainian just gabbroids, intrusive nature and a deep source that does not create doubts. The Chyhyryn massif has an area of over 3,500 km2, located in the northern part of the Ingul megablock. The main volume of rocks that make up the array is occupied by granites, which in their composition correspond to the granites of the Kirovograd complex. According to structural features, trachytoid and porphyritic granites differ among them, and biotite and garnet-biotite granites differ in composition. The inclusions are usually represented by a microcline (occupying 40-50% of the rock volume), having a tabular shape, 3-8 mm in size, which often contain small inclusions of quartz and plagioclase. Large plate crystals of the microcline are often crushed from the edges. In addition to the microcline, plagioclase crystalline crystals up to 5 mm in size occur in areas. Porphyry-like granites of the Chyhyryn massif, common within the Golovkivsky quarry. Monocytes from biotite granite were dated to determine the time of formation of the Chyhyryn massif. Granite was selected in the Golovkivsky quarry, located south of the village. Skelivka.

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Zhao, Chuntao, Jinggui Sun, Yang Liu, Xiaolei Chu, Zhikai Xu, Jilong Han, Wenqing Li, Liang Ren et Chenglin Bai. « Constraints of magmatism on the Ergu Fe–Zn polymetallic metallogenic system in the central Lesser Xing’an Range, NE China : evidence from geochronology, geochemistry and Sr–Nd–Pb–Hf isotopes ». Geological Magazine 158, n^o 10 (23 juillet 2021) : 1862–90. http://dx.doi.org/10.1017/s0016756821000479.

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AbstractThe medium-sized Ergu Fe–Zn polymetallic skarn deposit is located in the central Lesser Xing’an Range, NE China. The ore bodies are mainly hosted in the contact zone between granodiorite intrusions and lower Cambrian dolomitic crystalline limestones or skarns. To reveal the magmatic influence on the mineralization, resource potential and metallogenic geodynamic process of this deposit, a systematic study of the geology, petrology, zircon U–Pb dating, element geochemistry, amphibole geochemistry and Sr–Nd–Pb–Hf isotopes of the Ergu deposit intrusives was conducted. The results show the following: (1) The major rock types in the mine area are medium-grained granodiorite and porphyritic granite, and the rock related to mineralization is medium-grained granodiorite. Zircon U–Pb dating suggests that the granodiorite and porphyritic granite formed at 181.9–183.8 Ma and 182.7 Ma, respectively. Thus, an Early Jurassic magmatic event led to the formation of the Ergu deposit. (2) The granodiorite and porphyritic granite are high-K calc-alkaline I-type granites that formed by comagmatic evolution with varying degrees of fractional crystallization and were likely derived from partial melting of the lower crust. The Ergu deposit occurred in an active continental-margin tectonic setting. (3) The high water content (5.69 wt % H2O), high oxygen fugacity (ΔFMQ = +1.75 to +1.82) and intermediate-plutonic emplacement (3.13 km) of the granodioritic magma are key factors in the formation of the Ergu deposit. The porphyry granite is characterized by high water content (>4 wt % H2O), reduced oxygen fugacity (ΔFMQ = −0.47) and shallow emplacement (<3 km).

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Schofield, David I., et Richard S. D'Lemos. « Granite petrogenesis in the Gander Zone, NE Newfoundland : mixing of melts from multiple sources and the role of lithospheric delamination ». Canadian Journal of Earth Sciences 37, n^o 4 (3 avril 2000) : 535–47. http://dx.doi.org/10.1139/e99-116.

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Silurian to Devonian granites within the Gander Zone of the Appalachian Central Mobile Belt in northeastern Newfoundland formed adjacent to the former Gondwanan continental margin following terminal closure of the Iapetus Ocean. Comparison of geochemical and isotopic characteristics of the granites with their host migmatites and metasediments, amphibolite, and orthogneiss constrain their potential source. Nd and Sr isotopic compositions indicate that no single source or binary mixing product could have produced the granites. Instead, we show that they result from multicomponent mixing involving a contribution from unexposed crystalline basement, mantle or underplate, and variable contamination by supracrustal host rocks. The timing and composition of granite magmatism do not exhibit collisional orogenic, subduction-related, or continental rifting characteristics. Hence, we relate magmatism to lithospheric melting following delamination of an orogenic keel. This process provides the influx of mantle-derived magma into fertile crust and hence promotes lower crustal melting and primary magma mixing.

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Goode, A. J. J., et R. J. Merriman. « Evidence of crystalline basement west of the Land's End granite, Cornwall ». Proceedings of the Geologists' Association 98, n^o 1 (janvier 1987) : 39–43. http://dx.doi.org/10.1016/s0016-7878(87)80016-0.

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Guillot, François, Olivier Averbuch, Michel Dubois, Cyril Durand, Pierre Lanari et Arnaud Gauthier. « Zircon age of vaugnerite intrusives from the Central and Southern Vosges crystalline massif (E France) : contribution to the geodynamics of the European Variscan belt ». BSGF - Earth Sciences Bulletin 191 (2020) : 26. http://dx.doi.org/10.1051/bsgf/2020027.

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To provide a better picture of the active geodynamics along the Variscan suture zones during the late collisional stage (particularly regarding the evolution of the orogenic system towards HT conditions), we focused here on vaugnerites, which consist of mafic ultra-potassic magmatic rocks, intrusive into the granite-gneiss sequences of the Variscan Vosges crystalline massif. Those rocks, though subordinate in volume, are frequently associated with late-collisional granites. In the Central-Southern Vosges, they appear either as (1) pluton margin of the Southern Vosges Ballons granite complex or (2) composite dykes intrusive into migmatite and metamorphic sequences classically referred to as granite-gneiss unit (Central Vosges). Both types correspond to melanocratic rocks with prominent, Mg-rich, biotite and hornblende (20–40% vol., 64 < mg# < 78), two-feldspar and quartz. Those Vosges vaugnerites display geochemical signatures characteristic of ultra-potassic mafic to intermediate, metaluminous to slightly peraluminous rocks. Zircon U-Pb ages were obtained by Laser Ablation Inductively Coupled Plasma Mass Spectrometry. Zircon grains were extracted from a sillimanite-bearing gneiss from the granite-gneiss unit hosting the Central Vosges vaugnerites. They yielded an age at 451 ± 9 Ma, indicating a pre-Variscan Upper Ordovician protolith for the host sequence. Zircon from the four vaugnerite intrusives display U-Pb ages (± 2σ) of 340 ± 2.5 Ma (Ballons), 340 ± 25 Ma, 340 ± 7 Ma and 336 ± 10 Ma (Central Vosges). Synchronous within uncertainty, vaugnerite age data suggest a relatively early emplacement during the Late Variscan collisional history (i.e. Middle Visean times). These results are in line with previously published ages from the Southern Vosges volcano-sedimentary sequences (Oderen-Markstein) and the nearby ultra-potassic granite complexes from the Central and Southern Vosges (Ballons, Crêtes) thereby arguing for a magmatic event of regional significance. Recent petrological studies on vaugnerites suggest that they derive from partial melting of a metasomatized mantle contaminated to some different degrees by elements of continental crust. We propose here that the major ultra-potassic magmatic pulse at 340–335 Ma is a consequence of a significant change into the dynamics of the Rhenohercynian subduction system below the Central-Southern Vosges. In the light of recent thermo-mechanical modelling experiments on mature continental collision, magmatism could result from a syn-collisional lithospheric delamination mechanism involving (1) first, continental subduction evolving towards (2) the underthrusting of the Avalonian continental margin lower crust and (3) the initiation of lithospheric delamination within the supra-subduction retro-wedge (Saxothuringian-Moldanubian continental block). This delamination would drive the emplacement of an asthenospheric upwelling, initially localized along the Variscan suture zones, and gradually propagating towards the southern front of the belt during the Late Carboniferous, as the delamination front migrated at the base of the crust.

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Setiyawan, Khanif, Bambang Sugiantoro et Nugrah Rekto Prabowo. « Analysis of the Morphology and Mechanical Properties of Polymer Composite Materials (PCM) from Silicon Dioxide (SiO₂) and Multiwalled Carbon Nanotubes (MWNTs) Reinforced Volcanic Stone ». Materials Science Forum 1029 (mai 2021) : 65–72. http://dx.doi.org/10.4028/www.scientific.net/msf.1029.65.

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The formation of Polymer Composite Materials (PCM) based on mineral stones reinforced with Silicon Dioxide (SiO2) and Carbon Nanotubes (CNTs) using the Squeze Casting Method was carried out to obtain an increase in surface hardness, while the inner side of the elongation remained high. Based on SEM-EDX testing, it is known that the crystalline form of igneous rock and SiO2 is tapered, with large and small variations, CNTs with fine crystalline structures, which can bind well to specimen formation. The results of bending and hardness tests showed that dimensional variations, the aggregate ratio with resin and the addition of CNT and SiO2 reinforcement had the highest hardness 89.55 HD (Hardness of durometer), mixing of silica sand – vulkanic sand had the highest bending strength of 18.7 MPa, the lowest is a mixture of granite-sand of Merapi at 11.63 MPa. The variation of silica sand – volcanic sand has the highest bending strength, the lowest is the mixing of granite-volcanic sand.

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Gonzalez-Triviño, I., J. Pascual-Cosp, B. Moreno et M. Benítez-Guerrero. « Manufacture of ceramics with high mechanical properties from red mud and granite waste ». Materiales de Construcción 69, n^o 333 (28 janvier 2019) : 180. http://dx.doi.org/10.3989/mc.2019.03818.

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Red mud (bauxite residue) is an alkaline suspension that is the by-product of alumina production via the Bayer process. Its elevated annual production and the global inventory of red mud determine its valorisation. Granite can be used as a source of fluxing oxides for the ceramic industry, as can the flake-shaped waste generated during the flaming of granite. In this work, a set of ceramic pieces made of red mud and granite waste are prepared and characterised via X-ray diffraction, a hardness test, electron scanning microscopy, a leaching test, and determining open porosity, water absorption, bulk density and flexural strength of the samples. The main crystalline phases in the high-temperature fired products are hematite, pseudobrookite and anorthite; the presence of magnetite reveals their ferrimagnetic character. All samples present high mechanical properties. Leaching results are below critical levels established by regulations.

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Srivastava, P. K., A. P. Krishna, Shadab Jawed et Pallavi Sarkhel. « Quantitative Minerological Analysis of Some Granite Rocks of Deoghar Jharkhand ». Earth Science Research 9, n^o 2 (10 mai 2020) : 30. http://dx.doi.org/10.5539/esr.v9n2p30.

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Crystalline minerals in granite rocks has been quantatively analysed by powder X-ray diffraction (XRD) and Scanning Electron Microscope supported with Energy Dispersed Spectroscopy (SEM-EDS). SEM microphotograph reveals that rock is dominated by brightly illuminated quartz imbedded in the matrix with mica and other minor minerals. The X-ray mineral composition data have been plotted with SEM-EDS mineral composition, data shows that the composition obtained by two technique are in consistent within the experimental limit and in good agreement. Further plot of chemical composition of constituent oxides of granite sample by XRD and SEM-EDS confirm the consistency of two technique and similarity with Jharkhand mean granite composition. Silica composition have been plotted with trace element Pb, Ba, Zr, Rb, and Alumina composition with Pb , Ba, Zr and Rb shows that these elements are randomly imbedded in the matrix with almost uniform composition. Al2O 3 composition have been plotted with Ba, Pb, and Zr shows almost constant composition in all the five samples. Based on XRD and SEM-EDS results, it was reveals that granite sample from the study areas are peraluminius rocks composed of mainly quartz, muscovite, kaolinite, chlorite and albite.

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Usenko, O. V. « Tonalite-trondjemite-granodiorite formation of the Archaean. Special features of composition and conditions of formation, Ukrainian Shield as an example ». Geofizicheskiy Zhurnal 43, n^o 1 (13 mars 2021) : 38–68. http://dx.doi.org/10.24028/gzh.0203-3100.v43i1.2021.225541.

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Tonalite-trondjemite-granodiorite formation (TTG) produces the main volume of acidic rocks of the continental crust. Similar rocks are never met later. Therefore the problems of their production are directly connected with the problem of the crust and mantle formation. The structure of the Archean TTG formation of granite-gneiss area of the Bug megablock and granite-grrenstone area of the Middle Dnieper megablock (MDMB) has been considered. Similar and different features have been found. The analysis of these data resulted in a conclusion that within the MDMB, West Periazovian and Khashchevate-Zavalie block of the Middle Bug area the events of formation of the Archean granite-greenstone area were similar, however these three blocks of the Ukrainian Shield demonstrate different levels of erosion damage reflected in PT-conditions of metamorphic transformations. The rocks of TTG formation are a part of complex structured stratum appeared as a result of impregnation (migmatization) by quartz-albite melt of the primary crust and/or of more ancient strata of predominantly basic composition. In the middle-lower crust a partial replacement of the primary crust occurred and in the upper one — the deposition of new portions of the melt on the earlier ones, piercement of granite masses and migmatization of volcanogenic stratum. During the Archean these events happened repeatedly, that resulted in partial replacement of the primary crust with plagiogranites. Modern notions have been considered on the processes of producing of TTG granite formation. It has been shown that according to thermal model distribution of temperatures in the crust does not cross the line of basalt water solidus. That is why the appearance of granite melts could not be the result of submergence to big depths (ultrametamorphism). Chronological and genetic relation with mantle melting, of which komatiites and spilites of green-stone structures were crystallized, assumed convective flows in the mantle. To explain the formation of tonalite and trondjemite melt a model of two-leveled crystallization differentiation of ultrabasic melt has been used. However appearance of primary basalt replacement in such a scale and assimilation of green-stone roots by granite melt are possible only in case of interaction of mantle fluids with the rocks of primary crust. An assumption has been made that the composition of some part of these fluids could be close to composition of granite (trondjemite). According to the author’s opinion such assumption confirms a hypothesis of V. Griffin and N. Pirson about formation of crystalline mantle on the border between the Archean and Proterozoic.

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İLBEYLİ, N. « Mineralogical–geochemical constraints on intrusives in central Anatolia, Turkey : tectono-magmatic evolution and characteristics of mantle source ». Geological Magazine 142, n^o 2 (mars 2005) : 187–207. http://dx.doi.org/10.1017/s0016756805000476.

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Collision-related rocks intrude metamorphic rocks overthrust by ophiolitic units to make up the Central Anatolian Crystalline Complex. A wide variety of rock types were produced by the latest Cretaceous magmatism in the complex. These rocks can be divided into three distinct units: (1) calc-alkaline (Ağaçören, Behrekdağ, Cefalıkdağ, Çelebi, Ekecikdağ, Halaçlı, Karamadazı, Kösefakılı, Terlemez, Üçkapılı, Yozgat); (2) sub-alkaline (Baranadağ); and (3) alkaline (Atdere, Davulalan, Eğrialan, Hamit, İdişdağı, Karaçayır). The calc-alkaline rocks are metaluminous/peraluminous I- to S-type plutons ranging from monzodiorite to granite. The sub-alkaline rocks are metaluminous I-type plutons ranging from monzonite to granite. The alkaline rocks are metaluminous to peralkaline plutons, predominantly A-type, ranging from foid-bearing monzosyenite to granite. These plutons crystallized under varying pressures (5.3–2.6 kbar) and a wide range of temperatures (858–698 °C) from highly oxidized magmas (log fO2 −17 to −12). All intrusive rocks display enrichment in LILE and LREE compare to HFSE and have high 87Sr/86Sr and low 143Nd/144Nd ratios. These characteristics indicate that these rocks are derived from a mantle source containing large subduction components, and have experienced assimilation coupled with fractional crystallization (AFC) during uprise through crust. The coexistence of calc-alkaline and alkaline magmatism in the complex may be ascribed to mantle source heterogeneity before collision. Either thermal perturbation of the metasomatized lithosphere by delamination of the thermal boundary layer or removal of a subducted plate (slab breakoff) are the likely mechanisms for the initiation of the collision-related magmatism in the complex.

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Gawęda, Aleksandra, Krzysztof Szopa, Jan Golonka, David Chew et Anna Waśkowska. « Central European Variscan Basement in the Outer Carpathians : A Case Study from the Magura Nappe, Outer Western Carpathians, Poland ». Minerals 11, n^o 3 (28 février 2021) : 256. http://dx.doi.org/10.3390/min11030256.

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Exotic crystalline blocks within the Outer Carpathian flysch have the potential to establish the nature of their eroded basement source(s) and thus to reconstruct the paleogeography of the Outer Carpathians. Petrological investigations (including mineral analyses) coupled with zircon and apatite U-Pb dating were performed on an exotic crystalline block within Eocene siliciclastic rocks in the Rača Zone of the Magura Nappe in the Outer Western Carpathians, Poland. This exotic block is a large (c. 1 m diameter) pink porphyritic granitoid block found in the Osielczyk Stream, southeast of Osielec village in the Makowski Beskid mountains. The timing of magmatic crystallization is constrained by a U-Pb zircon age of 315.9 ± 2.6 Ma (MSWD = 0.69), while inherited zircon cores yield Archean (c. 2780 Ma), Cadomian (541.8 ± 6.7 Ma; MSWD = 0.53), Devonian (417 ± 11 Ma; MSWD = 0.57) and Early Variscan (c. 374 Ma) ages. Apatites from the same sample yield a Tera Wasserburg lower intercept U-Pb age of 311.3 ± 7.5 (MSWD = 0.87). The granitoid exhibits geochemical characteristics typical of I-type granites and εNd(316 Ma) = 2.15 (with a TDM model age of 1.18 Ga) and 87Sr/86Sr(316 Ma) = 0.704710. These data suggest a likely source region in the Saxo-Danubian Granite Belt, which possibly formed the basement of the Fore-Magura Ridge.

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Hendronursito, Yusup, Muhammad Amin, Slamet Sumardi, Roniyus Marjunus, Frista Clarasati, David Candra Birawidha, Muhammad Al Muttaqqi et Kusno Isnugroho. « Processing of granite quarry solid waste into industrial high silica materials using leaching process with HCl concentration variation ». Jurnal Riset Teknologi Pencegahan Pencemaran Industri 11, n^o 2 (19 novembre 2020) : 43–50. http://dx.doi.org/10.21771/jrtppi.2020.v11.no2.p43-50.

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This study was aimed to increase granite's silica content using the leaching process with HCl concentration variation. The granite used in this study came from Lematang, South Lampung. This study aims to determine the effect of variations in HCl concentration, particle size, and rotational speed on the crystalline phase and chemical elements formed in the silica product produced from granite. The HCl concentration variations were 6.0 M, 7.2 M, 8.4 M, and 9.6 M, the variation in particle size used was 270 and 400 mesh. Variations in rotational speed during leaching were 500 and 750 rpm. Granite powder was calcined at 1000 ºC for 2 hours. Characterization was performed using X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP- OES). The results showed that the silica content increased with increasing HCl concentration, the finer the particle size, and the higher the rotational speed. XRF analysis showed that the silica with the highest purity was leached with 9.6 HCl with a particle size of 400 mesh and a rotational speed of of 750 rpm, which was 73.49%. Based on the results above, by leaching using HCl, the Si content can increase from before. The XRD diffractogram showed that the granite powder formed the Quartz phase.

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Heo, Jin, Jae Chul Lee, Jung Bum Seo, Seung Hun Park, Jung Chan Park et Sangki Kwon. « Variation of Thermal and Mechanical Properties of Crystalline Granite under Saturated-Loading Condition ». Journal of Korean Society For Rock Mechanics 24, n^o 3 (30 juin 2014) : 224–33. http://dx.doi.org/10.7474/tus.2014.24.3.224.

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Exley, C. S. « Evidence of crystalline basement west of the Land's End granite Cornwall : A discussion ». Proceedings of the Geologists' Association 98, n^o 3 (janvier 1987) : 271. http://dx.doi.org/10.1016/s0016-7878(87)80046-9.

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Goode, A. J. J., R. J. Merriman et D. P. F. Darbyshire. « Evidence of crystalline basement west of the Land's End granite Cornwall : A reply ». Proceedings of the Geologists' Association 98, n^o 3 (janvier 1987) : 272. http://dx.doi.org/10.1016/s0016-7878(87)80047-0.

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Johansson, H., M. Siitari-Kauppi, M. Skålberg et E. L. Tullborg. « Diffusion pathways in crystalline rock—examples from Äspö-diorite and fine-grained granite ». Journal of Contaminant Hydrology 35, n^o 1-3 (décembre 1998) : 41–53. http://dx.doi.org/10.1016/s0169-7722(98)00114-4.

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Llera, F. J., M. Sato, K. Nakatsuka et H. Yokoyama. « Temperature dependence of the electrical resistivity of water‐saturated rocks ». GEOPHYSICS 55, n^o 5 (mai 1990) : 576–85. http://dx.doi.org/10.1190/1.1442869.

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The electrical resistivities of several dacitic tuffs, sandstone, andesite, granite, and crystalline limestone samples, saturated with a 0.001 M aqueous solution of KC𝓁;, were measured in the range from room temperature to 250°C. The experiments were made using a cell technique with platinum electrodes. Of particular interest are the data collected at temperatures above 200°C under high pressure, a region scarcely documented in the literature. Basically the samples used in the present study show a quasi‐exponential decrease of resistivity with temperature up to 200°C. The same temperature dependence is found for the resistivity of the saturating solution, thus confirming that conduction in water‐saturated rocks is essentially electrolytic. At temperatures above 200°C, some specimens of highly porous dacitic tuff still closely follow the saturating solution in the pattern of resistivity variation with temperature, exhibiting a minimum around 220°C; however, the behavior of low‐porosity crystalline rocks (notably granite) where a relatively abrupt decrease of resistivity is observed above 50°C, departs from that of the saturating solution. Hysteresis phenomena are more or less observed in most rock samples; i.e., the resistivity after one complete thermal cycle is systematically lower than its initial value. This experimental evidence points out that mechanisms different from water characteristics, such as growth of microcracks or chemical reactions, contribute to electrical conduction at high temperature. We point out the electrical signature of the thermally induced growth of microcracks (thermal cracking) in welded tuff and granite and suggest the possibility of using electrical measurements to monitor an extension of reservoir fractures in hot dry rock.

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Qin, Jin-hua, Cui Liu et Jin-fu Deng. « Geochronology and geochemistry of igneous rocks in the southeastern Lesser Xing’an Range, northeastern China : petrogenesis and implications for the early Mesozoic tectonic evolution ». Canadian Journal of Earth Sciences 57, n^o 4 (avril 2020) : 506–23. http://dx.doi.org/10.1139/cjes-2018-0198.

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We present systematic U–Pb age data collected by laser ablation multi-collector inductively coupled plasma mass spectrometry, precise geochemical data, and Nd isotope data for igneous rocks from the southeastern Lesser Xing’an Range (SE LXR). The results indicate that the formation ages as follows: Maojiatun alkaline granite, 207.2 ± 0.84 Ma and 204.6 ± 0.93 Ma; Diorite porphyrite, 164.5 ± 0.97 Ma; and Tieli syenogranite, 186.7 ± 1.50 Ma. The alkaline granite has high silicon, potassium, alkali, and FeOT contents; it is enriched in high field strength elements, Zr, Hf, Th, Rb, and U; is depleted in Ba, Sr, Nb, Ta, P, Ti, etc.; and has high ratios of 10000Ga/Al. It shows an A2-type granite affinity. The Tieli alkali-feldspar granite has high total alkali contents and is enriched in high field strength elements and rare earth elements and depleted in Sr, Ba, Ti, and P, and shows varying degrees of alkalinity. Rocks from SE LXR display similar εNd (t) values with corresponding to Nd model ages of 1095 to 813 Ma. The igneous rocks from the SE LXR are proposed to be derived from melting of the Neoproterozoic lower crust and potential magma mixing with ancient crystalline basement. The formation of the Maojiatun alkaline granite occurred in response to a postorogenic event following the closure of the Paleo-Asian Ocean. However, the SE LXR exhibited an extensional back-arc tectonic setting in the Early Jurassic. The Middle Jurassic diorite porphyrite could be related to the temporary stagnation of the westward subduction of the Paleo-Pacific plate.

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Leonov, M. G. « Crystalline protrusions as the typical stryctural-tectonic model of intragranite hydrocarbon accumulation ». Геотектоника, n^o 3 (26 juin 2019) : 24–41. http://dx.doi.org/10.31857/s0016-853x2019324-41.

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The paper deals with issues related to the study questions on magmatic tectonics and intragranitic hydrocarbon accumulating formation: (i) post-magmatic structure of granitic massifs containing hydrocarbons; (ii) mechanisms of structure-material processing, exhumation and forming porosity in granitic bodies on post-magmatic evolutional stage; (iii) availability and distribution of hydrocarbon deposits in granitic massifs located in different geodynamic settings and different regions; (iv) description of crystal piercing bodies – granite protrusions. The role of structural tectonic factor in intra-granitic hydrocarbon accumulating was estimated. An evolutionary structural-tectonic model of their formation within granitic massifs and, above all, granitic protrusions is proposed.

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Rutter, Michael J., et Peter J. Wyllie. « Experimental study of interaction between hydrous granite melt and amphibolite ». Geological Magazine 126, n^o 6 (novembre 1989) : 633–46. http://dx.doi.org/10.1017/s0016756800006932.

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AbstractWe have investigated the reaction between crystalline amphibolite and hydrous granite melt in static experiments at 810 °C and 1.5 kbar. Boundary layer concentration gradients in quenched silicate glass for the major element oxides and the volatile components, water and carbon dioxide, were measured using electron probe analysis and Fourier Transform Infrared Spectroscopy, respectively. We found a measurable change in the concentration of all components adjacent to the amphibolite in experiments of 66 and 330 hours duration. After I hour there was no detectable change in the concentration of major element oxides in the granitic glass, but steep concentration profiles were determined for carbon dioxide and water. A bubble-free zone developed adjacent to the amphibolite in the 66 hour experiment, and this zone increased in width after 330 hours. Reaction is controlled by dissolution of amphibolite and by transport of dissolved material through the granite melt. The rate-controlling process is chemical diffusion in the melt phase. Results confirm that in the absence of convective heat transfer and/or mechanical disaggregation of mafic inclusions, assimilation of mafic rocks by granite melt is very slow, corresponding to on the order of 10 mm for SiO2 in 1000 years.

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Luitel, Prakash, et Suman Panthee. « Geological study in Tal - Talekhu section of Manang District along the Besisahar – Chame Road ». Bulletin of the Department of Geology 22 (15 décembre 2020) : 25–28. http://dx.doi.org/10.3126/bdg.v22i0.33411.

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The section between Tal to Talekhu of Manang District lacks the detailed geological study. The geological mapping in the scale of 1:50,000 followed by the preparation of geological cross-section and lithostratigraphic column has been done in the present study. The studied area lies partially in the Higher Himalayan Crystalline and the Tibetan Tethys Sequence. The units of the Higher Himalayan Group from Tal to Talekhu consists mainly of vigorous to faintly calcareous gneiss, migmatitic gneiss, quartzite, granite, etc. They are named as the Calc. Silicate Gneiss and Paragneiss and the Orthogneiss and Granite units. The lowermost part of the Tibetan Tethys consisted of metamorphosed calcareous rocks containing silicates and feldspar, so this unit is termed as the Marble and Calc. Gneiss. The section is about 9 km in thickness and is highly deformed with presence of igneous rocks at many places.

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Luitel, Prakash, et Suman Panthee. « Geological study in Tal - Talekhu section of Manang District along the Besisahar – Chame Road ». Bulletin of the Department of Geology 22 (15 décembre 2020) : 25–28. http://dx.doi.org/10.3126/bdg.v22i0.33411.

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The section between Tal to Talekhu of Manang District lacks the detailed geological study. The geological mapping in the scale of 1:50,000 followed by the preparation of geological cross-section and lithostratigraphic column has been done in the present study. The studied area lies partially in the Higher Himalayan Crystalline and the Tibetan Tethys Sequence. The units of the Higher Himalayan Group from Tal to Talekhu consists mainly of vigorous to faintly calcareous gneiss, migmatitic gneiss, quartzite, granite, etc. They are named as the Calc. Silicate Gneiss and Paragneiss and the Orthogneiss and Granite units. The lowermost part of the Tibetan Tethys consisted of metamorphosed calcareous rocks containing silicates and feldspar, so this unit is termed as the Marble and Calc. Gneiss. The section is about 9 km in thickness and is highly deformed with presence of igneous rocks at many places.

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Sirianni, Greg, Howard Dean Hosgood, Martin D. Slade et Jonathan Borak. « Particle Size Distribution and Particle Size-Related Crystalline Silica Content in Granite Quarry Dust ». Journal of Occupational and Environmental Hygiene 5, n^o 5 (9 avril 2008) : 279–85. http://dx.doi.org/10.1080/15459620801947259.

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Abildaeva, M. A., S. V. Zinoviev et M. M. Buslov. « Late Paleozoic rock deformation of the Kurai block : structural‐kinematic analysis (upper Kuraika river, Gorny Altai, Russia) ». Geodynamics & ; Tectonophysics 10, n^o 4 (11 décembre 2019) : 937–43. http://dx.doi.org/10.5800/gt-2019-10-4-0450.

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In the Kurai ridge located in the southeastern Gorny Altai (Altai Mountains, Russia) metamorphic rocks of the Kurai complex are widely developed: granite‐gneisses, crystalline schists and amphibolites, including widespread Early Carboniferous mylonites and blastomylonites. Oriented samples of blastomylonites were taken from the upper reaches of the Kuraika river for the microstructural study aimed to determine the kinematics of movements. The analyses of thin cut samples show structural‐kinematic indicators that suggest two deformation events (left‐lateral shearing, then right‐lateral shearing).

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Carrieri, Mariella, Carly Guzzardo, Daniel Farcas et Lorenzo G. Cena. « Characterization of Silica Exposure during Manufacturing of Artificial Stone Countertops ». International Journal of Environmental Research and Public Health 17, n^o 12 (22 juin 2020) : 4489. http://dx.doi.org/10.3390/ijerph17124489.

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Artificial stone is increasing in popularity in construction applications, including commercial and residential countertops. Eco-friendliness, durability, and resistance to staining, make artificial stone attractive to consumers. Health concerns have arisen during manufacturing of artificial stone due to increased incidence of silicosis after relatively short exposure. Three artificial stone samples (A, B, and C) and one natural granite sample were subjected to cutting and grinding in a controlled environment. Gravimetric analysis, X-Ray diffraction, and scanning electron microscopy with energy dispersive spectroscopy were employed to determine crystalline silica concentrations and particle morphology of bulk and respirable particles. Silica content of bulk dust from artificial samples A and B was 91%, sample C was <10%, while granite was 31%. Silica percent in the respirable fraction for samples A and B was 53% and 54%, respectively, while sample C was <5% and granite was 8%. Number concentrations for samples A and B were mainly in the nano-fraction, indicating potential for translocation of silica particles to other organs outside of the lungs. Respirable dust concentrations inside the chamber were well above Occupational Safety and Health Administration standards for all materials, indicating that confined-space exposures require ventilation to lower risks of acute silicosis regardless of the nature of the stone.

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Glaas, Carole, Patricia Patrier, Jeanne Vidal, Daniel Beaufort et Albert Genter. « Clay Mineralogy : A Signature of Granitic Geothermal Reservoirs of the Central Upper Rhine Graben ». Minerals 11, n^o 5 (30 avril 2021) : 479. http://dx.doi.org/10.3390/min11050479.

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Clay minerals are the signature of hydrothermal alterations related to fluid circulation in volcanic and crystalline rocks. In the French part of the Upper Rhine Graben, in the deep-seated granites, illitic minerals (illite and I/S mixed layers (ml)) are typical products of the structurally-controlled argillic alteration in the Paleozoic granitic basement. In the new Illkirch geothermal well, GIL-1, drill-cuttings were studied with various petrographic methods to determine the characteristics of illite in paleo- and present-permeable zones, and to compare the alteration mineralogy with that of geothermal Soultz-sous-Forêts and Rittershoffen sites. Alteration petrography, crystal structure as well as the chemical composition of the illitic minerals and the altered bulk rocks were performed all along the well. This complete characterization, combined with geophysical logs and structural results, highlighted that the illitic minerals at Illkirch, Soultz-sous-Forêts, and Rittershoffen are composed of illite and illite-rich illite-smectite mixed layers (I/S ml) (<10% smectite). Two mineralogical assemblages were distinguished: chlorite + illite resulting from the propylitic alteration after the emplacement of the granitic basement under temperatures higher than 350 °C, and illite + I/S ml + carbonates + quartz resulting from the argillic alteration due to fluid circulation in the fractures at temperatures between 130 and 160 °C. Fracture zones are characterized by the occurrence of illitic minerals (illite and I/S ml), and specifically, by higher quantities of I/S ml in present-day permeable zones than in paleo-permeable zones. A conceptual model of the fracture zones at the interface between the overlying sedimentary rocks and the granitic basement is proposed. The present-day permeability distribution is controlled by the fault and fracture network, which consists of sealed zones and unsealed zones. Fluid convection in the URG implies paleo and present fluids circulating in both fractured sedimentary and crystalline reservoirs. Such circulations develop illitic minerals that could be considered as exploration guides for future geothermal sites in the URG. At Illkirch, the repartition of the present-permeable fracture zones (KFZs) in the GIL-1 well indicates that the moderately argillically altered granite distally situated from the Eschau fault is more permeable than the intensely argillically altered granite close to the Eschau fault.

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OLICHWER, Tomasz, Katarzyna PIOTROWSKA et Estera TEREŚKIEWICZ. « PERMEABILITY OF COVER DEPOSITS OF CRYSTALLINE ROCKS IN THE SUDETY MOUNTAINS (SW POLAND) BASED ON A FIELD STUDY ». Carpathian Journal of Earth and Environmental Sciences 16, n^o 1 (2021) : 5–15. http://dx.doi.org/10.26471/cjees/2021/016/151.

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Article presents a study on the permeability of weathering covers formed on crystalline rocks, which was conducted in south-western Poland (Sudety Mountains). Evaluation of the infiltration capacity was performed based on field measurements of the vertical hydraulic conductivity carried out by using the Porschet method and the ETC Pask Constant Head Permeameter. During the field investigations conducted in sixteen sites, 28 determinations of the hydraulic conductivity k were made, 16 by the Porschet method and 12 using the ETC Pask Permeameter. Ten sites represent weathering covers of metamorphic rocks (amphibolites, eclogites, mica-schists, crystalline limestones, gneisses) and the next six sites represent covers of igneous rocks (granites). The values of the vertical hydraulic conductivity k determined by the Porschet method ranged between 0.053 and 2.19 m/d, while those obtained using the ETC Pask Permeamet erranged between 0.012 and 0.76 m/d. In the first place, it should be noticed that the results determined during the field investigations conducted according to the Porschet method are generally 3-4 times higher than those obtained using the ETC Pask Permeameter. The results for the vertical hydraulic conductivity allow us to classify weathering sediments of metamorphic and igneous rocks, as semi-permeable to medium permeable rocks. Weathered gneisses were distinctly characterized by the worst capacity to conduct water (semi-permeable) among all types of weathering covers of crystalline rocks. Higher values (0,08-0,8 m/d) of the vertical hydraulic conductivity were found for the weathering covers of the other metamorphic rocks (low permeable). The best conditions to conduct water were found in the weathering covers of granite rocks, which in most cases are classified as medium permeable rocks (more than 0.8 m/d) and exhibit distinctly better permeability coefficients.

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Pevehouse, Katie J., Dustin E. Sweet, Branimir Šegvić, Charles C. Monson, Giovanni Zanoni, Stephen Marshak et Melanie A. Barnes. « Paleotopography controls weathering of Cambrian-age profiles beneath the Great Unconformity, St. Francois Mountains, SE Missouri, U.S.A. » Journal of Sedimentary Research 90, n^o 6 (5 juin 2020) : 629–50. http://dx.doi.org/10.2110/jsr.2020.33.

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ABSTRACT Precambrian (1.4 to 1.5 Ga) granite and rhyolite in the St. Francois Mountains at the northeast corner of the Ozark Plateau in Missouri has been altered down to a depth up to 8 meters below the Great Unconformity (the contact between Paleozoic sedimentary rock and underlying Precambrian). Petrographic, geochemical, and mineralogic data indicate that at least two events generated this alteration: 1) surficial weathering due to subaerial exposure of the granite before Cambrian burial—this material is preserved as a paleosol; and 2) alteration due to reaction with basinal fluids channeled along the unconformity from nearby sedimentary basins long after burial by Paleozoic strata. To assess the variation between surficial weathering and basinal fluid alteration, we measured and sampled for petrologic, geochemical, and mineralogic data in the rock at and just below the Great Unconformity at three paleoelevations. Whole-rock geochemical oxide and X-ray diffraction data indicate that K-metasomatism and highly crystalline illite occurred in each profile. The K increase reflects crystallization of authigenic feldspar and illite from basinal fluids that were channeled along the Great Unconformity during younger Paleozoic fluid-flow events. Each profile also exhibits an upward increase in altered feldspar crystals and highly crystalline kaolinite, and an upward decrease in Ca and Na. Such changes reflect soil formation due to reaction with meteoric water before Cambrian burial, indicating that the altered granite was a paleosol before Paleozoic basinal fluid-flow events. Notably, the paleosol at the highest paleoelevation displays the least amount of paleoweathering and the paleosol at the lowest displays the greatest amount of paleoweathering. These results demonstrate that not only can characteristics of the paleosol just below the Great Unconformity be recognized in the St. Francois Mountains, despite subsequent alteration, but also it is possible to detect variations in soil thickness that were controlled by slope steepness and, therefore, water availability and/or soil creep or failure. This spatial relationship is compatible with studies of modern soils which indicate that soil character varies with position on a slope.

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MILLER, C., M. THÖNI, W. FRANK, B. GRASEMANN, U. KLÖTZLI, P. GUNTLI et E. DRAGANITS. « The early Palaeozoic magmatic event in the Northwest Himalaya, India : source, tectonic setting and age of emplacement ». Geological Magazine 138, n^o 3 (mai 2001) : 237–51. http://dx.doi.org/10.1017/s0016756801005283.

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In the High Himalayan Crystalline Series of Northwest India, numerous peraluminous granites intruded the metasediments of the late Proterozoic to early late Cambrian Haimanta Group. Nd and Sr isotope systematics confirm that they were derived from heterogeneous crustal sources. New geochronological data from two plutons range in age from late Precambrian to early Ordovician: single zircon U–Pb dating yielded an age of 553 ± 2 (2σ) Ma for the Kaplas granite, whereas mineral Sm–Nd isotope systematics define a crystallization age of 496 ± 14 (2σ) Ma for the tholeiitic mafic rocks in the Mandi pluton, where evidence of magma mingling documents a close association between mafic and granitic melts. The end of this period of magmatic activity coincides with the depositional gap below the Ordovician transgression, caused by surface uplift and erosion, that is an important feature in the stratigraphy of the Northwest Himalaya. In Spiti, the transgression of the Ordovician basal conglomerates on a normal fault indicates pre-Ordovician extensional faulting. Therefore, the early Palaeozoic magmatic activities in the Northwest Himalaya could be correlated with a late extensional stage of the long-lasting Pan-African orogenic cycle which ended with the formation of the Gondwana supercontinent.

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Takahashi, H. A., T. Nakamura, H. Tsukamoto, K. Kazahaya, H. Handa et A. Hirota. « Radiocarbon Dating of Groundwater in Granite Fractures in Abukuma Province, Northeast Japan ». Radiocarbon 55, n^o 2 (2013) : 894–904. http://dx.doi.org/10.1017/s0033822200058057.

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Knowledge of the groundwater age is indispensable for understanding groundwater flow in crystalline rocks. The present study is the first to discuss the radiocarbon ages of groundwater in Abukuma granite, Fukushima Prefecture, northeast Japan. The vertical profiles of 14C dates and δ13C are obtained from 3 boreholes (depths of 140, 230, and 306 m). Chemical and carbon isotopic compositions suggest that dead-carbon contamination of groundwater occurred during groundwater storage in the fractures. 14C concentration was corrected by using isotopic mass balance in which dead-carbon contamination of the groundwater was considered. The 14C dates ranged from modern to ≃16 ka. The relationship between tritium and 14C data in 1 borehole suggests the simultaneous inflow of shallow groundwater to deeper levels occur for the depths between 60 and 100 m. The vertical profiles of 14C dates indicate a relatively constant age of 10–16 ka for groundwater deeper than 100 m, which may have been influenced by rapid sea-level changes after the glacial period.

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Isakov, Leonid V., et Maria L. Isakova. « Location pattern and genetic classification of granite pegmatites of the Ukrainian Shield ». Journal of Geology, Geography and Geoecology 28, n^o 4 (22 décembre 2019) : 673–91. http://dx.doi.org/10.15421/111964.

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The pegmatites of the Ukrainian Shield, their formation and occurrence are con- sidered. It is shown that the Ukrainian Shield is a pegmatite province encompassing seven regions: Middle Prydniprovia, Western Pryazovia, Eastern Pryazovia, Ingulski, Rosynsko- Tikytski, Dnistersko-Buzki and Volyn, respectively encompassing megastructures of the same names and including pegmatite fields of different mineralogical composition and geochemical specialization. The Volynski, Ingulski, Middle Prydniprovia, Western Pryazovia regions have rare-earth and rare-metal specialization presented by pegmatites of different origin and petrological and mineral composition and occurring in different structural and tectonic conditions, having different formation age, which allows a full classification scheme of the pegmatites of Ukrainian Shield to be given. These structures can be considered as having formed as a result of abyssal magmatic plumes. The geological-structural position of these megastructures with obvious signs of influence of certain abyssal processes on their formation supports this assumption. We present the main geological structural and genetic factors of formation of pegmatite-bearing megastructures of the Ukrainian crystalline core-area, these factors forming the basis of a classification scheme of pegmatites of Pre-Cambrian shields. We have systematized the pegmatites of the Ukrai- nian Shield , and designed their classification scheme . We have distinguished the following groups of pegmatites by the development of pegmatite-generating zones: - three genetic groups of pegmatites: ultrametamorphogenic, magmatogenic and metamorphogenic-meta- somatic; - six genetic subgroups of pegmatites: migmatic; autochthonous granite massifs; metamorphogenic and metasomatic displaced and formed pegmatites; multiphase intrusive granite massifs; multiphase intrusive alkaline massifs; multiphase granite batholiths. By the nature of pegmatite-bearing structures, the following structural groups have been singled out: granite-gneiss regional structures and domes; dome- synclinore and dome-trough plume-structures (subgroups: interdome synclinore and trough structures, in particular greenstone structures; intrusive domes and batholiths); specific tectonic zones of stress tensions.

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Sakamoto, Akihiko, Yusuke Himei et Yoshio Hashibe. « β-Spodumene Glass-Ceramic with Anomalous Low Thermal Expansion ». Advanced Materials Research 39-40 (avril 2008) : 381–86. http://dx.doi.org/10.4028/www.scientific.net/amr.39-40.381.

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To survey new method for controlling thermal expansion of glass-ceramic material, we studied the coefficient of thermal expansion (CTE) and the microstructure of β-spodumene glass-ceramics. We found that the CTE of the β-spodumene glass-ceramics is remarkably reduced by introducing interstices at the boundary between the crystalline and glass phases. Despite its relatively low crystallinity (45vol%), a newly developed glass-ceramic showed an anomalous low thermal expansion of 7x10-7 /oC, which compares to that of silica glass. The mechanical strength of this glass-ceramic was at the same level as that of natural stones: marble and granite.

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Imeokparia, E. G. « Geochemical evolution of the Jarawa Younger Granite complex and its related mineralization, northern Nigeria ». Geological Magazine 122, n^o 2 (mars 1985) : 163–73. http://dx.doi.org/10.1017/s0016756800031071.

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AbstractThe Jarawa Younger Granite complex is composed of high silica alkali granites that were emplaced 161 Ma ago. The granites are characterized by high contents of Rb, Li, F, Sn, Nb, W above normal low-Ca granitic rocks and have typical S-type characteristics that are indicative of a substantial component of crustal melt.Mineralization in the complex is associated with the biotite granite which was emplaced as a sheet-like body at relatively shallow depth and occurs as disseminations and as greisen lodes and veins.Chemical studies of the granites have shown that the biotite granite represents a highly fractionated rock that crystallized from a residual magma from which the hornblende-biotite granite had previously crystallized. However the biotite granite is characterized by steep gradients in some minor and trace elements that apparently indicate that liquid-state differentiation and/or volatile complexing processes made significant contributions to their differentiation. Enrichment of Th, Li, Rb, Sn, W and Nb may be more closely linked to roofward migration of F.

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Nguyen, Thanh Son. « Progressive Damage of a Canadian Granite in Laboratory Compression Tests and Underground Excavations ». Minerals 11, n^o 1 (24 décembre 2020) : 10. http://dx.doi.org/10.3390/min11010010.

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The crystalline rock formations of the Canadian Shield are currently one candidate rock type for the geological disposal of radioactive waste in Canada. This article starts with a critical review of past research results on the geomechanical behaviour of Lac du Bonnet granite, a rock type found at an Underground Research Laboratory (URL) in Pinawa, Manitoba, Canada. Based on the published data, a constitutive model was developed, based on Mohr-Coulomb plasticity, which includes the concept of asynchronous degradation of cohesion and mobilization of friction with progressive damage, as well as time-dependent degradation of strength. The constitutive model was used to simulate laboratory compression tests. It was then implemented in a coupled hydro-mechanical model to simulate the response of the rock mass induced by excavation of a test tunnel at 420 m depth at the URL.

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Graham, William G. B., Pamela M. Vacek, W. Keith C. Morgan, David C. F. Muir et Beth Sisco-Cheng. « Radiographic Abnormalities in Long-Tenure Vermont Granite Workers and the Permissible Exposure Limit for Crystalline Silica ». Journal of Occupational and Environmental Medicine 43, n^o 4 (avril 2001) : 412–17. http://dx.doi.org/10.1097/00043764-200104000-00021.

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Amran, Suhaily, Mohd Talib Latif, Md Firoz Khan, Eric Goh, Abdul Mutalib Leman et Shoffian Amin Jaafar. « Underestimation of respirable crystalline silica (RCS) compliance status among the granite crusher operators in Malaysian quarries ». Air Quality, Atmosphere & ; Health 10, n^o 3 (1 octobre 2016) : 371–79. http://dx.doi.org/10.1007/s11869-016-0439-7.

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Vasconcelos, Rita G. W., Andres Idiart, Neil C. Hyatt, John L. Provis et Claire L. Corkhill. « Leaching of Nirex Reference Vault Backfill cement by clay, granite and saline groundwaters ». MRS Advances 3, n^o 21 (2018) : 1175–80. http://dx.doi.org/10.1557/adv.2018.248.

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For the UK geological disposal facility (GDF) concept in a high strength crystalline rock, Nirex Reference Vault Backfill (NRVB) has been considered to use as a cementitious backfill material. The lifetime performance of this high pH material is required to be extremely long, and as a consequence of the interaction with the geological environment (e.g. groundwater), the backfill material will evolve and age with time. In this paper, we present the results of a leaching experiment, where NRVB is placed in contact with three different groundwater compositions representative of granitic, clay and saline groundwater for 35 days. Some differences were observed related with the mineralogy. X-ray Diffraction results showed the formation of more ettringite, mainly in the NRVB samples leached in clay and saline groundwater. An increase of the pH was also observed in the NRVB samples leached with the three different ground waters, being these results in accordance with the reactive transport modelling performed.

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Mikhailenko, Anna V., Dmitry A. Ruban, Natalia N. Yashalova et Maksim B. Rebezov. « The Unique Granite Gorge in Mountainous Adygeya, Russia : Evidence of Big and Complex Geosite Disproportions ». Geosciences 9, n^o 9 (27 août 2019) : 372. http://dx.doi.org/10.3390/geosciences9090372.

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Geological heritage sites (geosites) are subject to conservation and exploitation for science, education, and tourism. Some geosites are big and comprise diverse phenomena. Concentration of the latter in some parts of these geosites makes them disproportionate. A typical example is the Granite Gorge in SW Russia that is of recognizable tourism importance. It stretches for ~5 km and represents a deep valley of the Belaya River and Late Paleozoic granitoids of the Dakh Crystalline Massif. However, the full spectrum of unique features is much wider. Their inventory permits the establishment of geomorphological, igneous, metamorphic, sedimentary, mineralogical, paleogeographical, tectonic, economic, engineering, and hydrological and hydrogeological types of geological heritage. Spatial distribution of these types and the relevant features indicates their significant concentration near the northern entrance to the gorge and a less important concentration near the southern entrance. This is evidence of geosite disproportion. Apparently, the latter implies the need to focus geoconservation and geotourism activities on the noted loci of concentration. However, this would ’disrupt’ the geosite integrity, and, thus, management of the Granite Gorge geosite requires attention to all its parts, including those with lower heritage value.

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Liu, Zhuangzhuang, Xiaonan Huang, Aimin Sha, Hao Wang, Jiaqi Chen et Cheng Li. « Improvement of Asphalt-Aggregate Adhesion Using Plant Ash Byproduct ». Materials 12, n^o 4 (18 février 2019) : 605. http://dx.doi.org/10.3390/ma12040605.

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The adhesion bonding between asphalt and aggregate significantly influences field performance and durability of asphalt pavement. Adhesion promoters are typically used to improve asphalt-aggregate bonding and minimize moisture-related pavement damage, such as cracking and raveling. This study evaluated the effectiveness of plant ash byproduct as adhesion promoter to improve asphalt-aggregate adhesion performance. Three commonly used aggregate types (granite, basic rock, and limestone) and two asphalt binder types were used in laboratory testing. A modified stripping test method was developed to evaluate test results with image analysis and measurement of asphalt film thickness. The contact angle test and scanning electron microscopy (SEM) with energy disperse spectroscopy (EDS) were conducted. Test results showed that plant ash lixivium significantly improved asphalt-aggregate adhesion. Among three aggregate types, granite yielded the worst asphalt-aggregate adhesion for both control and treated specimens. The effectiveness of adhesion promotion varied depending on the type of asphalt or aggregate and temperature. The SEM/EDS observations showed that the mesh-like crystalline was formed at the interface between asphalt binder and aggregate in the treated specimen, which was believed to enhance the interfacial bonding and prevent asphalt film peeling off from aggregate.

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Gaspar, O., J. F. W. Bowles et T. J. Shepherd. « Silver mineralization at the Vale das Gatas tungsten mine, Portugal ». Mineralogical Magazine 51, n^o 360 (juin 1987) : 305–10. http://dx.doi.org/10.1180/minmag.1987.051.360.13.

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AbstractThe Vale das Gatas tungsten mine is situated at the contact between Hercynian granite and Cambrian-Precambrian crystalline schists a few kilometers north of the village of Sabrosa, near Vila Real, in northern Portugal. Wolframite has been the principal product of the mine although several other metals of economic interest are known to occur there. The silver content of the ores was attributed by earlier workers to the presence of tetrahedrite and schapbachite, whilst this work shows matildite, pavonite, acanthite, and argyrodite to be present, together with Ag-bearing galena. The textures and compositions of these phases are described with preliminary results of fluid inclusion studies.

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Kerimov, V. Yu, M. G. Leonov, A. V. Osipov, R. N. Mustaev et Vu Nam Khai. « Hydrocarbons in the basement of the South China Sea (Vietnam) shelf and structural-tectonic model of their formation ». Геотектоника, n^o 1 (1 avril 2019) : 44–61. http://dx.doi.org/10.31857/s0016-853x2019144-61.

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Research of genesis of hydrocarbon accumulations located within pre-Cenozoic basement of the South China Sea shelf (Vietnam) presented. Formation of hydrocarbon deposits is confined to the protrusive massifs of granites that have undergone structural and tectonic processing at the stage of prototectonics and postmagmatic tectonics. The totality of post-structure-forming processes led to a change in the viscosity properties of rocks, to their tectonic and material heterogeneity and stratification and, as a consequence, to vertical and lateral redistribution in space with the formation of granite protrusions. The mechanisms of formation of voids and oil and gas traps within the protrusions are considered. Based on the similarity of the geochemical characteristics and biomarker parameters of the oils and organic matter in the Oligocene-Miocene sediments and in the basement rocks, a conclusion has been made about the organic nature of the oils in the basement of the shelf of the South China Sea (Vietnam). Possible mechanisms of migration and accumulation of hydrocarbons in basement rocks are considered. It is confirmed that the formation of hydrocarbon deposits occurred due to lateral and downward migration of hydrocarbons through the contact area from the Oligocene-Miocene source rocks into crystalline massifs — into voids and increased fracture zone in the protrusions.

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Chelnokov, George, Ivan Bragin et Natalia Kharitonova. « Hydrochemistry of thermal waters in crystalline rocks of the Sikhote-Alin ridge, Far East of Russia ». E3S Web of Conferences 98 (2019) : 07006. http://dx.doi.org/10.1051/e3sconf/20199807006.

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Low-enthalpy thermal waters (30-50°C) of HCO3-Na and HCO3-SO4-Na types with nitrogen as a dominant associated gas discharge on the southern continental margin of the Russian Far East and traditionally are of great importance for recreation and balneology facilities. All studied thermal waters have meteoric origin and relate to Palaeocene granite intrusions. Based on the chemical characteristics and isotopic composition, thermal waters are divided onto “immature” thermal waters with a short residence time (3H=1.3±0.2TU), and “mature” thermal waters (3H=0.3±0.2TU) originated as a result of a longer evolution history (more than 60 years). The chemical composition of waters is largely determined by water-rock interactions, residence time and the local geothermal gradient.

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Zeh, A., et H. Brätz. « Timing of Late Carboniferous/Permian Granite and Granite Porphyry Intrusions in the Ruhla Crystalline Complex (Central Germany), New Constraints from SHRIMP and 207Pb/206Pb Single Zircon Dating ». Geochemistry 62, n^o 4 (2002) : 303–16. http://dx.doi.org/10.1078/0009-2819-00018.

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Wickman, Arthur R., et Paul J. Middendorf. « An Evaluation of Compliance with Occupational Exposure Limits for Crystalline Silica (Quartz) in Ten Georgia Granite Sheds ». Applied Occupational and Environmental Hygiene 17, n^o 6 (juin 2002) : 424–29. http://dx.doi.org/10.1080/10473220290035444.

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Trávníček, J., V. Kroupová et M. Šoch. « Iodine content in bulk feeds in western and southern bohemia ». Czech Journal of Animal Science 49, No. 11 (13 décembre 2011) : 483–88. http://dx.doi.org/10.17221/4335-cjas.

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In 1997–2001 a total of 304 samples of bulk feeds were analysed. Iodine was determined spectrophotometrically by Sandell and Kolthoff’s method (Bednář et al., 1964). The highest content of iodine was determined in grass silage (213.3 ± 169.3 µg/kg DM). The lowest concentration was measured in maize silage (110.0 ± 97.2) and hay (112.1 ± 93.9). Pasture herbage contained on average 148.9 ± 105.1. Feeds originating from foothill areas of western Bohemia (geological bedrock built of crystalline schists and igneous intrusions of earlier granite) contained a higher amount of iodine than feeds from foothill areas of southern Bohemia (geological bedrock in which crystalline schists prevail). The largest difference in iodine content in relation to feed origin was found out in hay: western Bohemia 168.0, southern Bohemia 78.0 (P < 0.01). From May to July pasture herbage contained 101.3 ± 73.6 and from August to October 214.5 ± 107.3 µg/kg DM (P < 0.01).    

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