Journal articles: 'Granite generation'

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Raeva, Emilia, and Zlatka Cherneva. "Geochemistry of migmatite-granite connection: a case study from the Central Rhodope, Bulgaria." Geologica Balcanica 37, no. 1-2 (June 30, 2008): 53–59. http://dx.doi.org/10.52321/geolbalc.37.1-2.53.

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Extensive crustal melting and intrusive granite magmatism accompanied the extensional stage of the Rhodope massif Alpine evolution. Granites of different structural position and time of crystallization could reveal compositional and temporal relations between anatectic migmatization and granite magma generation. We have studied the post-kinematic Smilyan pluton and smaller syn-kinematic granite bodies hosted by the Madan unit metatexitic gneisses in the southwestern periphery of a metamorphic core complex known as Central Rhodopian Dome (CRD). The dominant geochemical features of the Madan unit granites display remarkable similarities with in situ formed anatectic melts from the CRD diatexitic core (Arda unit): felsic peraluminous compositions, low HFSE and REE, high LILE contents and LREE/HREE ratios, and negligible to positive Eu anomaly. Some deviations of the syn-kinematic granites geochemistry (metaluminous compositions, REE and HFSE enrichment, LREE/HREE ratios and Eu/Eu* variation) support an idea of separate partial melt batches extracted from different precursor compositions. Age data available (Smilyan pluton 43 Ma, and CRD core anatectic melts 37–38 Ma) preclude direct feedback relations between Madan unit intrusive granites and Arda unit migmatites. We infer that the migmatite-granite connection should be considered a common process of protracted Tertiary crustal melting that operated during CRD evolution and affected different crustal sources to produce discrete portions of granite melts. Major and trace elements geochemistry reveals potential lines of descent amongst groups of spatially related granitic rocks due to the same mechanism of melt generation.

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Williams, Ian S., and Kenton S. W. Campbell. "Bruce William Chappell 1936–2012." Historical Records of Australian Science 28, no. 2 (2017): 146. http://dx.doi.org/10.1071/hr17012.

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Bruce Chappell was one of the most distinguished geologists of his generation whose contributions to understanding the origins of granites are both insightful and profound. A pioneer in the application of X-ray fluorescence spectrography to the analysis of geological materials, his radical ideas about magma genesis, still the subject of vigorous debate, have dominated and largely determined the global directions of subsequent research on granites. His restite model, the recognition that most granite magmas move bodily away from their source regions as a mixture of melt and solid residual material, the progressive separation of which determines the magma composition, underlies his tenet that granites are images of their source. His consequent recognition, with Allan White, that there are two fundamentally different types of granite magma, I-type (derived from igneous sources) and S-type (derived from weathered sedimentary sources), each with its distinctive evolutionary path and associated mineralization, continues to underpin research into granites worldwide, and the search for granite-related mineral deposits.

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Gosselin, D. C., J. J. Papike, C. K. Shearer, Z. E. Peterman, and J. C. Laul. "Geochemistry and origin of Archean granites from the Black Hills, South Dakota." Canadian Journal of Earth Sciences 27, no. 1 (January 1, 1990): 57–71. http://dx.doi.org/10.1139/e90-005.

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The Little Elk Granite (2549 Ma) and granite at Bear Mountain (BMG) (~2.5 Ga) of the Black Hills formed as a result of a collisional event along the eastern margin of the Wyoming Province during the late Archean. Geochemical modelling and Nd isotopic data indicate that the Little Elk Granite was generated by the partial melting of a slightly enriched (εNd = −1.07 to −3.69) granodioritic source that had a crustal residence time of at least 190 Ma. The medium-grained to pegmatitic, peraluminous, leucocratic BMG was produced by melting a long-lived (>600 Ma), compositionally variable, enriched (εNd = −7.6 to −12.3) crustal source. This produced a volatile-rich, rare-earth-element-poor magma that experienced crystal–melt–volatile fractionation, which resulted in a lithologically complex granite.The production of volatile-rich granites, such as the BMG and the younger Harney Peak Granite (1715 Ma), is a function of the depositional and post-depositional tectonic environment of the sedimentary source rock. These environments control protolith composition and the occurrence of dehydration and melting reactions that are necessary for the generation of these volatile-rich leucocratic granites. These types of granites are commonly related to former continental–continental accretionary boundaries, and therefore their occurrence may be used as signatures of ancient continental suture zones.

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Kitchen, D. E. "The disequilibrium partial melting and assimilation of Caledonian granite by Tertiary basalt at Barnesmore, Co. Donegal." Geological Magazine 126, no. 4 (July 1989): 397–405. http://dx.doi.org/10.1017/s0016756800006580.

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AbstractA regional Tertiary basaltic dyke swarm intensifies within a Caledonian granite at Barnesmore, Co. Donegal. Rapid heating along the contact of one (possible feeder) dyke resulted in disequilibrium partial melting of granite wall-rock and the generation of a range in melt composition by the in situ melting of feldspar. The compositional variability of the melt is preserved in a glass containing feldspar spherulites and other quench phases which suggest rapid cooling. During partial melting the trace elements, Rb, Sr, and Ba were mobile and have been concentrated in glassy melted granite close to the contact of one dyke. The textures, mineralogy and geochemistry of dolerite in two dykes indicate localized bulk contamination and mixing with melted granite. This had a particularly marked effect on the crystallization of pyroxene and resulted in a wide range in mineral composition reflecting the degree of contamination. The intensification of a regional dyke swarm in well-jointed granite might control the siting of some major intrusive centres. Granite melted and mixed with basaltic magma may contribute to the evolution of granites in such centres.

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Sandiford, Mike, John Foden, Shaohua Zhou, and Simon Turner. "Granite genesis and the mechanics of convergent orogenic belts with application to the southern Adelaide Fold Belt." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 83, no. 1-2 (1992): 83–93. http://dx.doi.org/10.1017/s026359330000777x.

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ABSTRACTTwo models for the heating responsible for granite generation during convergent deformation may be distinguished on the basis of the length- and time-scales associated with the thermal perturbation, namely: (1) long-lived, lithospheric-scale heating as a conductive response to the deformation, and (2) transient, localised heating as a response to advective heat sources such as mantle-derived melts. The strong temperature dependence of lithospheric rheology implies that the heat advected within rising granites may affect the distribution and rates of deformation within the developing orogen in a way that reflects the thermal regime attendant on granite formation; this contention is supported by numerical models of lithospheric deformation based on the thin-sheet approximation. The model results are compared with geological and isotopic constraints on granite genesis in the southern Adelaide Fold Belt where intrusion spans a 25 Ma convergent deformation cycle, from about 516 to 490 Ma, resulting in crustal thickening to 50–55 km. High-T metamorphism in this belt is spatially restricted to an axis of magmatic activity where the intensity and complexity of deformation is significantly greater, and may have started earlier, than in adjacent low-grade areas. The implication is that granite generation and emplacement is a causative factor in localising deformation, and on the basis of the results of the mechanical models suggests that granite formation occurred in response to localised, transient crustal heating by mantle melts. This is consistent with the Nd- and Sr-isotopic composition of the granites which seems to reflect mixed sources with components derived both from the depleted contemporary mantle and the older crust.

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Stepanyuk, L. M., T. I. Dovbush, V. M. Belskyi, O. B. Vysotsky, O. V. Bilan, and I. M. Kotvitska. "GEOCHRONOLOGY OF CRYSTALLINE ROCKS OF THE SHUMYLIV SECTION OF THE SOUTH BUG RIVER VALLEY (HAISYN BLOCK)." Mineralogical Journal 43, no. 3 (2021): 62–72. http://dx.doi.org/10.15407/mineraljournal.43.03.062.

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The Haisyn complex rocks (sobites (Shcherbakov, 2005)), consisting of diorite-like rocks and amphibolites, which biotite granites develop, is outcroping near the village of Shumyliv along the South Bug river and in an abandoned open pit mine (on South of Shumyliv). The rocks are characterized by high magnetization according to magnetic survey results. A linear magnetic anomaly extends in the north-east direction (NE 69º) with a distance of more than 35 km. Entin et al. (2019) proposed that this magnetic anomaly is caused by a dyke with a felsic or intermediate composition. The internal structure of accessory zircon crystals from quartz diorite and granite were studied. In both types of rocks, zircon crystals are complex and consist of three different generations. The first generation consists of fractured nuclei of light pink color, which apparently grew in rims of zircon of the 2nd and/or 3rd generation. Zircon of the second generation is light pink in color. It forms rims around the first generation of zircon, but also occasionally occurs the interior core areas of crystals. Third generation zircon forms rims around the first two generation zircons, or growth episodes. As usually, the heads of crystals have a light brown to brown color. The age of formation of monazite in the granite and titanite in the quartz diorite was determined by the uranium-lead isotope method. The two endogenous geological processes have ages of 2049 ± 6 million years and 2005±2 million years, respectively.

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Sawyer, E. W. "Melt segregation and magma flow in migmatites: implications for the generation of granite magmas." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 87, no. 1-2 (1996): 85–94. http://dx.doi.org/10.1017/s0263593300006507.

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ABSTRACT:To form a granite pluton, the felsic melt produced by partial melting of the middle and lower continental crust must separate from its source and residuum. This can happen in three ways: (1) simple melt segregation, where only the melt fraction moves; (2) magma mobility, in which all the melt and residuum move together; and (3) magma mobility with melt segregation, in which the melt and residuum move together as a magma, but become separated during flow. The first mechanism applies to metatexite migmatites and the other two to diatexite migmatites, but the primary driving forces for each are deviatoric stresses related to regional-scale deformation. Neither of the first two mechanisms generates parental granite magmas. In the first mechanism segregation is so effective that the resulting magmas are too depleted in FeOT, MgO, Rb, Zr, Th and the REEs, and in the second no segregation occurs. Only the third mechanism produces magmas with compositions comparable with parental granites, and occurs at a large enough scale in the highest grade parts of migmatite terranes, to be considered representative of the segregation processes occurring in the source regions of granites.

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Vigneresse, Jean Louis. "A new paradigm for granite generation." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 95, no. 1-2 (March 2004): 11–22. http://dx.doi.org/10.1017/s0263593300000882.

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ABSTRACTIdeas about granite generation have evolved considerably during the past two decades. The present paper lists the ideas which were accepted and later modified concerning the processes acting during the four stages of granite generation: melting, melt segregation and ascent, and emplacement. The active role of the mantle constitutes a fifth stage.Fluid-assisted melting, deduced from metamorphic observations, was used to explain granite and granulite formation. Water seepage into meta-sedimentary rocks can produce granitic melt by decreasing melting temperature. CO2 released by the mantle helps to transform rocks into granulites. However, dehydration melting is now considered to be the origin of most granitic melts, as confirmed by experimental melting. Hydrous minerals are involved, beginning with muscovites, followed by biotite at higher temperatures. At even deeper conditions, hornblende dehydration melting leads to calc-alkaline magmas.Melt segregation was first attributed to compaction and gravity forces caused by the density contrast between melt and its matrix. This was found insufficient for magma segregation in the continental crust because magmas were transposed from mantle conditions (decompression melting) to crustal conditions (dehydration melting). Rheology of two-phase materials requires that melt segregation is discontinuous in time, occurring in successive bursts. Analogue and numerical models confirm the discontinuous melt segregation. Compaction and shear localisation interact non-linearly, so that melt segregates into tiny conduits. Melt segregation occurs at a low degree of melting.Global diapiric ascent and fractional crystallisation in large convective batholiths have also been shown to be inadequate and at least partly erroneous. Diapiric ascent cannot overcome the crustal brittle-ductile transition. Fracture-induced ascent influences the neutral buoyancy level at which ascent should stop but does not. Non-random orientation of magma feeders within the ambient stress field indicates that deformation controls magma ascent.Detailed gravity and structural analyses indicate that granite plutons are built from several magma injections, each of small size and with evolving chemical composition. Detailed mapping of the contact between successive magma batches documents either continuous feeding, leading to normal petrographic zoning, or over periods separated in time, commonly leading to reverse zoning. The local deformation field controls magma emplacement and influences the shape of plutons.A typical source for granite magmas involves three components from the mantle, lower and intermediate crusts. The role of the mantle in driving and controlling essential crustal processes appears necessary in providing stress and heat, as well as specific episodes of time for granite generation. These mechanisms constitute a new paradigm for granite generation.

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Yu, Zhi-Feng, Qi-Ming Peng, Zheng Zhao, Ping-An Wang, Ying Xia, Yu-Qi Wang, and Hao Wang. "Geochronology, Geochemistry, and Geodynamic Relationship of the Mafic Dykes and Granites in the Qianlishan Complex, South China." Minerals 10, no. 12 (November 29, 2020): 1069. http://dx.doi.org/10.3390/min10121069.

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The Qianlishan complex, located in Hunan Province of South China, is closely associated with intense W-dominated polymetallic mineralization. The Qianlishan complex is composed of three phases: the main-phase porphyritic and equigranular granites, granite porphyry, and mafic dykes. Geochronologically, the zircon U-Pb dating results show that the porphyritic and equigranular granites have ages of approximately 159 and 158 Ma, respectively, similar to those of mafic dykes (approximately 158 Ma), while the granite porphyry was formed later at approximately 145 Ma. Geochemically, the mafic dykes are characterized by calc-alkaline high-Mg andesite (HMA) with high MgO, TiO2, Mg#, and CA/TH index. They exhibit significantly depleted εNd(t) and εHf(t) with high Ba/La, La/Nb, and (La/Yb)N, indicating that they formed from mixing melts of depleted asthenospheric mantle and metasomatized subcontinental lithospheric mantle (SCLM). The main-phase granites are peraluminous and are characterized by high SiO2, low (La/Yb)N ratios, and relative depletion in Ba, Sr, Ti, and Eu. They also display negative correlations between La, Ce, Y, and Rb contents, suggesting that they are highly fractionated S-type granites. Furthermore, they show high εNd(t) and εHf(t), CaO/Na2O ratios, HREE, and Y contents, indicating that they were produced by parental melting of ancient basement mixed with mantle-derived components. In contrast, the granite porphyry shows A-type signature granites, with higher εNd(t) and εHf(t) and CaO/Na2O ratios than the main-phase granites but similar Zr/Nb and Zr/Hf ratios to the mafic dykes, suggesting that they are the products of partial melting of a hybrid source with ancient basement and the mafic dykes. We thus infer that the slab roll-back led to generation of Qianlishan back-arc basalt and HMA and further triggered the formation of the Qianlishan granite.

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PRADO, MAURÍCIO, JOSÉ TADEU MAXIMINO MIRRAS FERRON, EVANDRO FERNANDES DE LIMA, ARTUR CEZAR BASTOS NETO, VITOR PAULO PEREIRA, ORLANDO RENATO RIGON MINUZZI, and RONALDO PIEROSAN. "Caracterização Petrográfica e Geoquímica da Parte Leste do Granito Europa, Distrito Mineiro de Pitinga, AM." Pesquisas em Geociências 34, no. 1 (June 30, 2007): 77. http://dx.doi.org/10.22456/1807-9806.19464.

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The important mineral deposits of the Pitinga Mine, in the Amazonian region are related to A-type granites intruded in the Iricoumé Group. The Europa granite is one of these A-type rocks, intruded in the Iricoumé Group, which is represented by subaerial vulcanoclastic rocks (crystal-rich ignimbrites, thin massive tuffs and siltic tufaceous arenites) and minor hipabissal rhyolites. The volcanic rocks were probably generated in a caldera environment. The Europa granite is an alkali-feldspar peralkaline granite (hipersolvus) without genetic relationship with to the volcanic rocks of the Iricoumé Group, but it could have been generated during the resurgence stages. The petrographic and geochemical data attest that fractional crystallization process was the principal mechanism during the crystallization, which led to the generation of two different granitic facies. The Nb soil anomalies overprinted on the more differentiated facies are related to the astrophillite weathering.

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XU, XI-SHENG, KAZUHIRO SUZUKI, LEI LIU, and DE-ZI WANG. "Petrogenesis and tectonic implications of Late Mesozoic granites in the NE Yangtze Block, China: further insights from the Jiuhuashan–Qingyang complex." Geological Magazine 147, no. 2 (October 27, 2009): 219–32. http://dx.doi.org/10.1017/s0016756809990367.

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AbstractThe Jiuhuashan–Qingyang complex is one of the Mesozoic granite complexes in the NE Yangzte Block, China. New petrographical and petrochemical data show that the complex comprises a dominant granodiorite–monzogranite, the Qingyang body, which was intruded by the Jiuhuashan granite body. The two are characterized by distinct mineral components and trace element patterns. Compared to the Qingyang granodiorite and monzogranite, the Jiuhuashan granite is enriched in Rb, Th, U, Nb, Ta, Hf, Yb and Lu, and depleted in Ba, Sr, Nd, Sm, Eu, Gd and Ti, which are ascribable to the separation of plagioclase and biotite, and crystallization of thorite and fergusonite during the magmatism. New LA-ICPMS zircon U–Pb dating suggests that the crystallization age of the Qingyang body is 139–133 Ma, and the Jiuhuashan granite followed at 127 Ma. Moreover, the new zircon U–Pb dates reveal that Archaean materials were involved in the formation of these magmas, and that a sodium-rich metasomatic event occurred at about 100 Ma. The CHIME monazite and zircon ages studied for the Jiuhuashan body agree well with the LA-ICPMS zircon ages. Integrating this information with previous studies for granites in the NE Yangtze Block and in the coastal area of SE China, we believe that all of these Late Mesozoic granites were produced under the tectonic regime of palaeo-Pacific plate subduction towards the SE China continent in a NW direction, but the granites in the NE Yangtze Block are basically derived by crustal melting with limited mixing of juvenile material during the magma generation.

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Wilton, Derek H. C. "Tectonic evolution of southwestern Newfoundland as indicated by granitoid petrogenesis." Canadian Journal of Earth Sciences 22, no. 7 (July 1, 1985): 1080–92. http://dx.doi.org/10.1139/e85-110.

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Four granitoid suites are recognized in the region of the Cape Ray Fault Zone of southwestern Newfoundland. The two oldest (Ordovician–Silurian (?)) suites represent partial melts of their enclosing host rocks. The Port aux Basques granite is modelled as a partial melt of the gneissic component of its host, Port aux Basques Complex. The Cape Ray granite forms a dominantly tonalitic terrane derived by partial melting of ophiolitic material. The Red Rocks granite and a megacrystic phase of the Cape Ray granite form coherent lines of geochemical descent from the parental tonalite but show evidence of some continental crust contamination.The Late Devonian Windowglass Hill granite is a subvolcanic equivalent of felsic volcanic rocks in the Windsor Point Group. Both units were derived as partial melts of continental crust.The post-tectonic, Late Devonian to Early Carboniferous Strawberry and Isle aux Morts Brook granites constitute the youngest granitoid suite in the region. These A-type granitoids were derived as partial melts of an underlying depleted granulitic (felsic) crust. The depleted nature of the source may have resulted from previous generation of the Windowglass Hill granite and Windsor Point Group. The only possible protolith for the granulitic source is Precambrian Grenvillian gneiss. The presence of this gneiss beneath the Cape Ray Fault Zone of southwestern Newfoundland implies that the complete series of lithologies is allochthonous.

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Truche, Laurent, Franck Bourdelle, Stefano Salvi, Nicolas Lefeuvre, Apolline Zug, and Emily Lloret. "Hydrogen generation during hydrothermal alteration of peralkaline granite." Geochimica et Cosmochimica Acta 308 (September 2021): 42–59. http://dx.doi.org/10.1016/j.gca.2021.05.048.

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Aspiotis, S., S. Jung, F. Hauff, and R. L. Romer. "Petrogenesis of a late-stage calc-alkaline granite in a giant S-type batholith: geochronology and Sr–Nd–Pb isotopes from the Nomatsaus granite (Donkerhoek batholith), Namibia." International Journal of Earth Sciences 110, no. 4 (April 7, 2021): 1453–76. http://dx.doi.org/10.1007/s00531-021-02024-w.

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AbstractThe late-tectonic 511.4 ± 0.6 Ma-old Nomatsaus intrusion (Donkerhoek batholith, Damara orogen, Namibia) consists of moderately peraluminous, magnesian, calc-alkalic to calcic granites similar to I-type granites worldwide. Major and trace-element variations and LREE and HREE concentrations in evolved rocks imply that the fractionated mineral assemblage includes biotite, Fe–Ti oxides, zircon, plagioclase and monazite. Increasing K2O abundance with increasing SiO2 suggests accumulation of K-feldspar; compatible with a small positive Eu anomaly in the most evolved rocks. In comparison with experimental data, the Nomatsaus granite was likely generated from meta-igneous sources of possibly dacitic composition that melted under water-undersaturated conditions (X H2O: 0.25–0.50) and at temperatures between 800 and 850 °C, compatible with the zircon and monazite saturation temperatures of 812 and 852 °C, respectively. The Nomatsaus granite has moderately radiogenic initial 87Sr/86Sr ratios (0.7067–0.7082), relatively radiogenic initial εNd values (− 2.9 to − 4.8) and moderately evolved Pb isotope ratios. Although initial Sr and Nd isotopic compositions of the granite do not vary with SiO2 or MgO contents, fSm/Nd and initial εNd values are negatively correlated indicating limited assimilation of crustal components during monazite-dominated fractional crystallization. The preferred petrogenetic model for the generation of the Nomatsaus granite involves a continent–continent collisional setting with stacking of crustal slices that in combination with high radioactive heat production rates heated the thickened crust, leading to the medium-P/high-T environment characteristic of the southern Central Zone of the Damara orogen. Such a setting promoted partial melting of metasedimentary sources during the initial stages of crustal heating, followed by the partial melting of meta-igneous rocks at mid-crustal levels at higher P–T conditions and relatively late in the orogenic evolution.

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Mohammadi, Nadia, Christopher R. M. McFarlane, and David R. Lentz. "U–Pb Geochronology of Hydrothermal Monazite from Uraniferous Greisen Veins Associated with the High Heat Production Mount Douglas Granite, New Brunswick, Canada." Geosciences 9, no. 5 (May 15, 2019): 224. http://dx.doi.org/10.3390/geosciences9050224.

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A combination of in situ laser ablation inductively coupled plasma–mass spectrometry (LA ICP–MS) analyses guided by Scanning Electron Microscope–Back-Scattered Electron imaging (SEM–BSE) was applied to hydrothermal monazite from greisen veins of the Late Devonian, highly evolved, uraniferous Mount Douglas Granite, New Brunswick, Canada. Understanding the uraniferous nature of the suite and characterizing the hydrothermal system that produced the associated mineralized greisen veins were the main goals of this study. The uraniferous nature of the Mount Douglas Granite is evident from previous airborne radiometric surveys, whole-rock geochemical data indicating high U and Th (2–22 ppm U; 19–71 ppm Th), the presence of monazite, zircon, xenotime, thorite, bastnaesite, and uraninite within the pluton and the associated hydrothermal greisen veins, as well as anomalous levels of U and Th in wolframite, hematite, and martite within greisen veins. New U–Pb geochronology of hydrothermal monazite coexisting with sulfide and oxide minerals yielded mineralization ages ranging from 344 to 368 Ma, with most of them (90%) younger than the crystallization age of the pluton (368 ± 3 Ma). The younger mineralization age indicates post-magmatic hydrothermal activities within the Mount Douglas system that was responsible for the mineralization. The production of uraniferous greisen veins by this process is probably associated with the High Heat Production (HHP) nature of this pluton, resulting from the radioactive decay of U, Th, and K. This heat prolongs post-crystallization hydrothermal fluid circulation and promotes the generation of hydrothermal ore deposits that are younger than the pluton. Assuming a density of 2.61 g/cm3, the average weighted mean radiogenic heat production of the Mount Douglas granites is 5.9 µW/m3 (14.1 HGU; Heat Generation Unit), in which it ranges from 2.2 µW/m3 in the least evolved unit, Dmd1, up to 10.1 µW/m3 in the most fractionated unit, Dmd3. They are all significantly higher than the average upper continental crust (1.65 µW/m3). The high radiogenic heat production of the Mount Douglas Granite, accompanied by a high estimated heat flow of 70 mW/m2, supports the assignment of the granite to a ‘hot crust’ (>7 HGU) HHP granite and highlights its potential for geothermal energy exploration.

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Chen, Xin, Cin-Ty A. Lee, Xiao-Lei Wang, and Ming Tang. "Influence of water on granite generation: Modeling and perspective." Journal of Asian Earth Sciences 174 (May 2019): 126–34. http://dx.doi.org/10.1016/j.jseaes.2018.12.001.

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Shardakova, G. Yu. "New data on the trace element composition and Lu-Hf isotopic system of zircons from the Early Cambrian granites of the Ufaley block (Middle Urals): a step to the correction of geodynamic concepts." LITHOSPHERE (Russia) 22, no. 1 (March 2, 2022): 55–74. http://dx.doi.org/10.24930/1681-9004-2022-22-1-55-74.

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Research subject. Composition and isotopic parameters of zircons and their host granites of the Bitim complex, localised in the eastern part of the Ufaley block (Middle Urals).Materials and methods. The determination of trace element composition and Lu-Hf isotope system in zircons was carried out by LA-ICP-MS (the “Geoanalitik” shared research facilities of the IGG UB RAS, Ekaterinburg).Results and conclusions. The images and geochemical features of the main zircon population from granites confirm their magmatic genesis and minimal alteration, which proves previously defined Vendian- Cambrian (520 ± 9 Ma) age for the granites. Younger zircons (401–459 Ma) differing in composition from the older ones, were formed during subsequent tectonic-thermal activity, possibly under the fluid action. The mixed mantle-crustal nature of substrate for the granite melting is indicated by specific isotopic parameters (87Sr/86Sr = 0.703389, εHf(t)aver = +6.3) and a number of characteristic ratios for zircons and granites. The geodynamic concepts of the granite formation settings of the Bitim complex are corrected: in the Vendian–Early Cambrian, a transform-type margin has developed in this sector, the divergent movements on which have been accompanied by a break in the continuity of the crust and the intrusion of a deep mantle diapir; the participation of the slab substance in the magma generation might also be assumed.Conclusions. The results obtained can be used for the geological mapping and correction of a general geodynamic scheme for the junction zone between the Ural Mobile Belt and the East European platform.

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Zimanovskaya, Natalya A., Tatyana A. Oitseva, Sergey V. Khromykh, Alexey V. Travin, Ainel Y. Bissatova, Irina Yu Annikova, and Saltanat S. Aitbayeva. "Geology, Mineralogy, and Age of Li-Bearing Pegmatites: Case Study of Tochka Deposit (East Kazakhstan)." Minerals 12, no. 12 (November 22, 2022): 1478. http://dx.doi.org/10.3390/min12121478.

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New geological, mineralogical, geochemical, and geochronological data have been obtained for Li-bearing pegmatites from the Tochka deposit located within the Karagoin–Saryozek zone in East Kazakhstan. Earlier, the exploration works in this zone were carried out to detect only Ta and Sn mineralization, but other ores (including Li) were not considered. The estimation of lithium resources in pegmatites from the area was methodologically imperfect. Previously, it was believed that the formation of rare-metal pegmatite veins was associated with Late Carboniferous Na-granites. The obtained geological observation confirms that the ore-bearing rare-metal pegmatites at the Tochka deposits cut the Late Carboniferous Na-granites and do not cut the Early Permian Kalba granites. The associations of the accessory minerals in host hornfels, Na-granites, and rare-metal pegmatites are different and the accessory minerals in pegmatites are similar to the accessory minerals in the Kalba granites. Geochemical data show that the behavior of rare elements (Ba, Th, HFSE, and REE) and the levels of accumulation of rare metals prove that pegmatites are similar to the product of the differentiation of the granitic magmas of the Kalba complex. The 40Ar/39Ar muscovite age of the Tochka pegmatites (~292 Ma) fits the age range of the Kalba granite complex. Based on the main principles of the generation of rare-metal pegmatites, the Tochka pegmatites formed during the fluid–magmatic fractionation of magma in large granitic reservoirs of the Kalba complex. The Karagoin–Saryozek zone—located between several large granite massifs of the Kalba complex where host rocks play a role as a roof—may be very promising for rare-metal pegmatite mineralization.

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Broman, C., K. Sundblad, M. Valkama, and A. Villar. "Deposition conditions for the indium-bearing polymetallic quartz veins at Sarvlaxviken, south-eastern Finland." Mineralogical Magazine 82, S1 (March 21, 2018): S43—S59. http://dx.doi.org/10.1180/minmag.2017.081.024.

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ABSTRACTPolymetallic quartz veins, with up to 1500 ppm indium, have been discovered recently in the Sarvlaxviken area within the 1.64 Ga anorogenic multiphase Wiborg rapakivi batholith and adjacent 1.90 Ga Svecofennian crust in SE Finland. Evidence from primary fluid inclusions in the Sarvlaxviken area provides new information on the hydrothermal transport and depositional processes of metals in anorogenic granites. Fluid inclusions with variable aqueous liquid and vapour proportions (5–90 vol.% vapour) occur in quartz, cassiterite and fluorite belonging to three generations of polymetallic quartz veins. Microthermometry indicates that the veins were deposited at temperatures that range from ~500°C down to <100°C and salinities from 0 to 16 eq. mass% NaCl. Fluid inclusion data show that the depositional conditions were similar regardless of vein generation. The interpreted depositional processes involve phase separation with a combination of condensation, cooling and boiling of an initially low-salinity (<3 eq. mass% NaCl) aqueous magmatic vapour phase enriched in CO2-F-Cl-S and metals. Fluid inclusions with low salinities dominate, but higher salinities are recorded in metal-rich parts of the veins. The turbulent fluid flow, with complex geometry and temperature-salinity patterns, may explain why sulfide and/or oxide opaque minerals occur irregularly, and are locally the dominating vein minerals, but disappear completely into barren parts of the quartz veins. All fluids are considered to have been generated by the F-rich Marviken granite (and related granite dykes), which show all geochemical criteria for an ore-fertile granite. The quartz veins investigated in the adjacent Svecofennian country rocks are considered to represent the very last stage of a fluid with similar characteristics to the fluid responsible for the ore formation in the Sarvlaxviken area, but that had cooled to <100°C.

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Nummer, Alexis R., Rômulo Machado, and Nolan M. Dehler. "Pluton emplacement in a releasing bend in a transpressive regime: the arrozal granite in the Paraíba do Sul shear belt, Rio de Janeiro." Anais da Academia Brasileira de Ciências 79, no. 2 (June 2007): 299–305. http://dx.doi.org/10.1590/s0001-37652007000200011.

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The Arrozal Granite, situated in the southwestern region of the State of Rio de Janeiro, has a granitic to granodioritic composition. It contains a strong mylonitic foliation along its border, passing gradually to a well-developed magmatic foliation towards its center. Structural analysis indicates that the Arrozal Granite was emplaced along the Além-Paraíba Shear Zone in a dextral transpressive tectonic regime. A regional shift of the trend along this shear zone from NE-SW to E-W, observed in the area, is interpreted to be casually related to the creation of space for the emplacement of the granite. Our data indicate that releasing bends may have played an important role for space generation during the emplacement of the Arrozal Granite and other plutons.

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AUGLAND, LARS EIVIND, ARILD ANDRESEN, FERNANDO CORFU, and HANS KRISTIAN DAVIKNES. "Late Ordovician to Silurian ensialic magmatism in Liverpool Land, East Greenland: new evidence extending the northeastern branch of the continental Laurentian magmatic arc." Geological Magazine 149, no. 4 (October 3, 2011): 561–77. http://dx.doi.org/10.1017/s0016756811000781.

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AbstractNew U–Pb ID-TIMS geochronological and whole-rock geochemical data from the Hurry Inlet Plutonic Terrane in Liverpool Land provide evidence of a Late Ordovician to Silurian magmatic arc in the East Greenland Caledonides. These voluminous granitoid rocks range from meladiorite to monzonite and granite, they are alkali-calcic to calc-alkaline and magnesian, and have characteristic arc granitoid trace element signatures. Zircon data give ages of 446 ± 2 and 438 ± 4 Ma for two phases of the Hurry Inlet Composite Pluton, 426 ± 1 Ma for a meladioritic xenolith in the anatectic Triaselv granite, and 424 ± 1 Ma for the Hodal-Storefjord Pluton. The Late Ordovician plutons can be correlated with similar plutons in the uppermost nappes of the Scandinavian Caledonides, likely representing the northern branch of magmatic arcs formed on the Laurentian margin. Magmatism appears to have continued sporadically until about 425 Ma when a major, short-lived, magmatic event formed the bulk of the batholith on Liverpool Land. This activity was likely mantle-driven and can be correlated with the Newer Granites in Scotland, for which a slab break-off mechanism has been proposed. The increased heat flow from this process can also explain the generation of the crustally derived, syntectonic, two-mica granites, which are the areally most important Caledonian suite in East Greenland.

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Trunilina, Vera. "Petrology of Granitoids of the Selennyakh Ridge (Verkhoyansk-Kolyma Orogenic Belt)." IOP Conference Series: Earth and Environmental Science 906, no. 1 (November 1, 2021): 012084. http://dx.doi.org/10.1088/1755-1315/906/1/012084.

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Abstract The Verkhoyansk-Kolyma orogenic belt is characterized by intense Late Mesozoic granitoid magmatism. Numerous granitoids plutons form longitudinal belts, elongated parallel to the boundaries of major tectonic structures (Main and Northern), and transverse belts, oriented across or at an angle to them. The Main belt is dominated by massifs of granodiorite-granite composition, accompanied by tin-tungsten, boron-tin, and gold mineralization of various scale. Therefore, understanding their petrological and genetic characteristics and crystallization conditions leading to the generation of mineralization is of not only theoretical but also practical interest. The aim of the research was a detailed study of petrography, geochemical features and crystallization conditions of granodiorite-granite massifs of the Selennyakh block of the Omulevka terrane of the Kolyma-Omolon microcontinent that forms part of the Verkhoyansk-Kolyma orogenic belt. It was found that the formation of granitoids took place in an active continental margin setting and was long-term and complex. During the evolution of magmatism, the homodrome character of development (granodiorites → granites → leucogranites and aplites) was replaced by the antidrome one (granite-porphyries and granodiorite-porphyries). The Rb-Sr isotopic age of the rocks varies from 136 to 122 Ma. The generation of the parent melts for the granitoid massifs occurred within the lower crust at the boundary between amphibolite and dacite-tonalite substrates at temperatures of 1070–990° C and a pressure of 1.1–0.9 GPa. These parameters are comparable to those of the melt that formed the granodiorite-porphyry dikes: 990° C and 0.94 GPa. Maintaining high temperatures of the melt formation from initial to final derivatives at deeper levels of the magma chamber with a simultaneous increase in their fluid saturation requires the supply of juvenile heat and fluids. The main mineral in the territory is tin. The formation of mineralization is associated with late fluid-saturated derivatives of the granitoid melt. During the crystallization of leucogranites and pegmatites, fluorine was the main Sn-extracting agent. With depth, in the course of crystallization of granite and granodiorite porphyries, boron and then sulfur became the major extractants of tin.

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D’LEMOS, R. S., M. BROWN, and R. A. STRACHAN. "Granite magma generation, ascent and emplacement within a transpressional orogen." Journal of the Geological Society 149, no. 4 (July 1992): 487–90. http://dx.doi.org/10.1144/gsjgs.149.4.0487.

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Levashova, E. V., S. G. Skublov, T. A. Oitseva, B. A. Dyachkov, X. H. Li, Q. L. Li, N. V. Shatova, and V. V. Shatov. "First Age and Geochemical Data on Zircon from Riebeckite Granites of the Verkhnee Espe Rare Earth–Rare Metal Deposit, East Kazakhstan." Geochemistry International 60, no. 1 (January 2022): 1–15. http://dx.doi.org/10.1134/s0016702922010086.

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AbstractThis paper is dedicated to the isotope-geochemical study of zircon from riebeckite granites of the Verkhnee Espe rare earth-rare metal deposit and the specification of its U–Pb age. Zircon from the Verkhnee Espe massif is peculiar in the high content of non-formula elements (up to 43000 ppm REE, up to 22000 Y, and others) and demonstrates a clearly expressed heterogeneous structure. The central and rim zones of the zircon show a “magmatic” rare-earth element (REE) distribution. The intermediate zones are characterized by a flattening of the REE patterns and an anomalous enrichment in REE, Y, Nb, and Ca. This compositional feature of the zircon may be caused by impact of fluid-saturated granite melts enriched in incompatible trace elements. The δ18О values in the zircon are 5.83–7.16‰, which generally corresponds to zircon formed from granitoid melts. The age of zircon from the Verkhnee Espe rare earth–rare metal deposit is 283 ± 3 Ma, which indicates that there is no significant age gap between granite crystallization, on the one hand, and metasomatic processes and ore generation, on the other.

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Corfu, Fernando, and Denver Stone. "Age structure and orogenic significance of the Berens River composite batholiths, western Superior Province." Canadian Journal of Earth Sciences 35, no. 10 (October 1, 1998): 1089–109. http://dx.doi.org/10.1139/e98-056.

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The Berens River area of northwestern Ontario is underlain mainly by Archean felsic plutonic rocks, which enclose minor supracrustal and gneissic enclaves and merge with the greenstone-belt-rich Uchi Subprovince to the south. U-Pb geochronology using zircon and monazite shows that the batholiths evolved mainly between 2750 and 2690 Ma by sequential and essentially continuous intrusive activity into an older substratum composed of 3000-2800 Ma volcanic and tonalitic crust. There is a broad, but not strict, compositional transition from early biotite tonalite and hornblende tonalite, progressing with time towards a greater abundance of hornblende granodiorite to granite, and finally to late biotite granite, rare peraluminous granites, and sanukitoid (dioritic, monzodioritic to granitic) plutons. The tonalite suites were predominantly synvolcanic. The late granitic intrusions postdated volcanism, but were largely synchronous with the main compressional events that caused widespread sedimentation, deformation, and metamorphism in other parts of the region. The age patterns and compositional features of the batholiths and the spatial and temporal links between their evolution and those of the supracrustal sequences in the greenstone belts of the region are consistent with mechanisms of magma generation and emplacement at converging plate margins.

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Kholodnov, V. V., E. S. Shagalov, G. A. Kallistov, G. Yu Shardakova, D. N. Salikhov, and E. V. Konovalova. "The Akhunovo–Petropavlovsk Granitoid Area as a Continental-Margin Center of the Long-Term Mantle–Crust Interaction: The Role of Subductional and Rift–Plume Sources." Russian Geology and Geophysics 62, no. 6 (June 1, 2021): 648–65. http://dx.doi.org/10.2113/rgg20194121.

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Abstract —The Akhunovo–Petropavlovsk area of the late Paleozoic granite magmatism is located in the northeast of the Magnitogorsk megazone (MMZ) in the South Urals. It is a series of successively intruded rocks (Petropavlovsk, Akhunovo, Karagai, and Uiskii Bor intrusions) differing not only in composition, the depth of formation, and ore content but also in the relationship with magmatic and fluid sources and in magma generation mechanisms. This area differs significantly in the number and composition of intrusive complexes from the igneous rocks and ore associations in the central and western parts of the MMZ. The granite magmatism pulses alternated with the collisional shearing/spreading and rifting stages. The Petropavlovsk mesoabyssal granite intrusion (347.0 ± 8.6 Ma) formed at the early stage of the area evolution. Its rocks are similar in composition to a suprasubductional series (melting products of a mantle source enriched not only in water fluid but also in Cl). Later (310–306 Ma), at the collision–compression stage, crustal intrusion of the Akhunovo–Karagai granodiorite–granite complex took place. The intruded rocks are similar to the Middle Urals continental-margin gabbro-tonalite–grano-diorite–granite plutons (320–290 Ma) bearing large gold–sulfide–quartz deposits (Berezovskoe etc.). At the final stage of the area evolution, during the transition from continental-margin regime to hard collision between the East European and Kazakhstan continents (late Carboniferous) and the intense shearing/spreading deformations, the Uiskii Bor granosyenite–granite intrusion (304.0 ± 4.8 Ma) rich in K and HFSE formed. Granite intrusions of this type have been revealed in the MMZ for the first time. Thus, the granitoid complexes of the Akhunovo–Petropavlovsk area formed under changes in geodynamic settings and are characterized by different compositions, depths of occurrence, and genesis. This permits us to consider the area a typical continental-margin center of the long-term mantle–crust interaction, where magma generation proceeded at different mantle and crust levels, with the participation of both suprasubductional and enriched plume-related rift sources.

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de Azevedo, Afonso Rangel Garcez, Markssuel Teixeira Marvila, Laimara da Silva Barroso, Euzébio Bernabé Zanelato, Jonas Alexandre, Gustavo de Castro Xavier, and Sergio Neves Monteiro. "Effect of Granite Residue Incorporation on the Behavior of Mortars." Materials 12, no. 9 (May 5, 2019): 1449. http://dx.doi.org/10.3390/ma12091449.

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Civil construction is one of the most resource-consuming sectors in the world. For this reason, the last years have witnessed the study of reusing industrial residues in building materials. The ornamental stone processing industry has a considerable environmental liability related to residue generation during the cutting stages of granite blocks. The objective of this work is to analyze the viability of incorporating granite residues, up to 100%, to substitute sand in coating mortars for building construction. Mortars without residue, as control, and incorporated with 20, 40, 60, 80, and 100% of granite residue were subjected to consistency tests, incorporated air and water retention together with the rheological characterization using the squeeze-flow and the dropping-ball methods. The results show that mortars with 40% granite residues presented greater plastic deformation, helping their applicability by also presenting improved technological properties in the fresh state.

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Leake, Bernard Elgey. "Stoping and the mechanisms of emplacement of the granites in the Western Ring Complex of the Galway granite batholith, western Ireland." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 102, no. 1 (March 2011): 1–16. http://dx.doi.org/10.1017/s175569101100911x.

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ABSTRACTThe western end of the Galway granite batholith demonstrates the importance of stoping as a granite emplacement process, which is currently controversial, and also of space generation by uplift of the centre of a ring complex. The granite rings are shown (with a coloured 1:25 000 geological map) to be consanguineous, near coeval, and older than the 407–410 Ma late molybdenite mineralisation. A newly-recognised Mace–Ards granite, around and injected by the Aplitic Murvey-type granite of the ring core (both lacking hornblende and titanite), has biotite–muscovite–cordierite orbs and sulphide–granite orbs, showing separation of immiscible hydrous and sulphide fluids from the late magma which, with vugs, indicates a low pressure, near-roof site. The outer ring of the Errisbeg Townland granite (ETG, the main batholith granite with K-feldspar phenocrysts), was emplaced by progressive outward stoping of the country rock metagabbro, as shown by mapping, and by chemical fractionation of feldspars, biotites and bulk rocks, to the marginal, dry, fine-grained aphyric, in part garnetiferous, highly fractionated, siliceous Murvey granite. Stoping ceased when, after previously invading dense metagabbro, the outer ring complex reached the low-density Roundstone granite, which is shown for the first time to be older than the Galway batholith. This arresting of the batholith intrusion shows that stoping was such a significant process that emplacement ceased when stoping became impossible. The inside edge of the ETG grades into the slightly later, intrusive, aphyric Carna granite, which shows inward fractionation to the wet magma of the Mace–Ards granite. The ring complex core was injected by highly fractionated, dry, Aplitic Murvey-type granite, intensely hydrothermally altered by late magmatic water. The radially outward dipping, inclined igneous layering in the ETG shows that the original ETG centre was pushed upwards by the intruded Carna granite and eroded away. The Galway granite and its nearby magmatism matches the low Ba and Sr, high Th and Rb, Scottish Cairngorm Suite and similarly has few appinitic rocks associated with it. Magmatism extended over >45 Myr from ∼425 Ma to 380 Ma. It originated by slab breakoff and consequent rise of the asthenosphere, causing deep crustal melting.

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Fuentes, Elsa, Rafael Carballeira, and Beatriz Prieto. "Role of Exposure on the Microbial Consortiums on Historical Rural Granite Buildings." Applied Sciences 11, no. 9 (April 22, 2021): 3786. http://dx.doi.org/10.3390/app11093786.

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Local granite has been used throughout history in Galicia (NW Spain), forming the basis of much of the region’s architecture. Like any other rock, granite provides an ecological niche for a multitude of organisms that form biofilms that can affect the physical integrity of the stone. In this study, for the first time, characterization of the microbial consortium forming biofilms that developed on historical rural granite buildings is carried out using a combination of culture-dependent and next generation sequencing (NGS) techniques. Results pointed to differences in biofilm composition on the studied rural granite buildings and that of previously analyzed urban granite buildings, especially in terms of abundance of cyanobacteria and lichenized fungi. Exposure was corroborated as an important factor, controlling both the diversity and abundance of microorganisms on walls, with environmental factors associated with a northern orientation favoring a higher diversity of fungi and green algae, and environmental factors associated with the west orientation determining the abundance of lichenized fungi. The orientation also affected the distribution of green algae, with one of the two most abundant species, Trentepohlia cf. umbrina, colonizing north-facing walls, while the other, Desmococcus olivaceus, predominated on west-facing walls.

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Parphenuk, O. "Postcollisional evolution features of the intracontinental structures formed by overthrusting." Georesursy 20, no. 4 (November 30, 2018): 377–85. http://dx.doi.org/10.18599/grs.2018.4.377-385.

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The investigation of intracontinental collision structures is conducted based on the complex model of the thermal and mechanical evolution of overthrusting process for the rheologically layered lithosphere, which includes brittle upper crust, the lower crust and lithospheric upper mantle with different effective viscosity values. Finite element models with Lagrangian approach were used for the problem simulation. It was shown that thermal evolution of continental orogens essentially results from the geometry and topography due to thrusting and postcollision stage. This work concentrates on the thermal parameters influence on the evolution of collision zones aimed to the study of possibility of granite melt formation. Calculations for mean continental initial temperature distribution lead to the conclusion of possibility of granite melt formation for the case of “wet” granite solidus. The horizon of temperatures higher than “wet” granite solidus appears at the level of 30-40 km, moving upward to the depth 15-20 km at postcollision stage. The early postcollision evolution shows some heat flow increase due to the thickening of the upper crust with maximum heat generation rate. Further history leads to the stable heat flow values because additional loading redistribution resulting from the denudation of surface uplift and corresponding sedimentation is small due to the local erosion in our model. It was shown that surface heat losses after the termination of horizontal shortening depend to a greater extent on radiogenic heat generation rather than thermal conductivity value in the upper crust.

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Melleton, Jérémie, Eric Gloaguen, Dirk Frei, Alexandre Lima, Romeu Vieira, and Tania Martins. "Polyphased rare-element magmatism during late orogenic evolution: geochronological constraints from NW Variscan Iberia." BSGF - Earth Sciences Bulletin 193 (2022): 7. http://dx.doi.org/10.1051/bsgf/2022004.

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Rare-element granites and pegmatites represent important sources of raw materials for “clean, green and high technologies”, such as lithium and tantalum, for example. However, mechanisms of rare-element granites and pegmatite’s origin are still far from being fully understood. Several rare-element pegmatite fields and a rare-element granite are known in the Variscan realms located in Iberia (Spain and Portugal), enhancing the interest of this area for studying the formation of these extremely fractionated melts. In situ U-Pb dating by LA-SF-ICP-MS of columbite-group minerals from rare-element granites and pegmatites of the Iberian Variscan belt provides new constraints on the generation of rare-element melts. Three events have been recognized: (i) Emplacement of the Argemela rare-element granite, in the Central Iberian Zone (CIZ), with an age of 326 ± 3 Ma; (ii) Emplacement of rare-element pegmatites from the Galicia-Trás-os-Montes Zone (GTOMZ), at an average age of 310 ± 5 Ma; (iii) Emplacement of rare-element pegmatites in the CIZ and in the southern GTOMZ at about 301 ± 3 Ma. These two last events are coeval with the two peaks of ages for the late orogenic magmatism at ca. 308 Ma and 299 Ma, and all dated rare-element pegmatites clearly emplaced during the late-orogenic evolution of the Variscan belt. Contemporaneous fields of rare-element pegmatites are arranged in belts following those formed by similar granitoid suites. Pegmatite fields from both the GTOMZ and the CIZ reveal a southward propagation of ages of emplacement, which matches the observed propagation of deformation, metamorphism and magmatism in the two different geotectonic zones. Existence of three successive rare-element events in the Iberian Massif argues against the involvement of lower crustal HP-HT metamorphism in the generation of rare-element melts. Possible sources of rare-element-enriched melts are more likely located in the middle to upper crust, as are the major components of granitic magmatism. Analyses of U and Pb isotopes from columbite-group minerals are very robust and reproducible, making them good candidates for dating ore deposits related to peraluminous magmatism as well as REE- and Nb-bearing deposits.

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Brown, Michael. "The generation, segregation, ascent and emplacement of granite magma: the migmatite-to-crustally-derived granite connection in thickened orogens." Earth-Science Reviews 36, no. 1-2 (April 1994): 83–130. http://dx.doi.org/10.1016/0012-8252(94)90009-4.

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Nazarov, V. E., A. B. Kolpakov, and A. V. Radostin. "Amplitude dependent internal friction and generation of harmonics in granite resonator." Acoustical Physics 55, no. 1 (January 2009): 100–107. http://dx.doi.org/10.1134/s1063771009010114.

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Wareham, Christopher D., Ian L. Millar, and Alan P. M. Vaughan. "The generation of sodic granite magmas, western Palmer Land, Antarctic Peninsula." Contributions to Mineralogy and Petrology 128, no. 1 (June 25, 1997): 81–96. http://dx.doi.org/10.1007/s004100050295.

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35

Shardakova, G. Yu, S. V. Pribavkin, A. A. Krasnobaev, N. S. Borodina, and M. V. Chervyakovskaya. "ZIRCONS FROM ROCKS OF THE MURZINKA-ADUI METAMORPHIC COMPLEX: GEOCHEMISTRY, THERMOMETRY, POLYCHRONISM, AND GENETIC CONSEQUENCES." Geodynamics & Tectonophysics 12, no. 2 (June 23, 2021): 332–49. http://dx.doi.org/10.5800/gt-2021-12-2-0527.

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Transformation of the oceanic crust into the continental one in orogenic belts is an important problem in petrological studies. In the paleocontinental sector of the Urals, a key object for tracing the stages of metamorphism and investigating the origin of anatectic granites is the Murzinka-Adui metamorphic complex. We have analyzed trace elements in zircons and established their genesis, sources, crystallization conditions, and stages of metamorphic events and granite generation in this complex. Zircons compositions were determined by the LA-ICP-MS method. Temperatures were calculated from Ti contents in the zircons. We distinguish three geochemical types of zircons, which differ in the ratios of light and heavy REE, U, Th, Ti, Y and show different values of Ce- and Eu-anomalies and Zr/Hf ratios, which are indicative of different crystallization conditions, as follows. Type I: minimal total LREE content; clear negative Eu- and Ce- anomalies; features of magmatic genesis; crystallization temperatures from 629 to 782 °C. Type II: higher contents of Ti, La, and LREE; low Ce-anomaly; assumed crystallization from highly fluidized melts or solutions. Type III: low positive Eu-anomaly; high REE content; low Th/U-ratio; zircons are assumed to originate from a specific fluidized melt with a high Eu-concentration. Ancient relict zircons (2300–330 Ma) in gneisses and granites show features of magma genesis and belong to types I and II. Such grains were possibly inherited from granitoid sources with different SiO2 contents and different degrees of metamorphism. Based on the geological and petrogeochemical features and zircon geochemistry of the Murzinka-Adui complex, there are grounds to conclude that the material composing this complex was generated from the sialic crust. The main stages of metamorphism and/or granite generation, which are traceable from the changes in types and compositions of the zircons, are dated at 1639, 380–370, 330, and 276–246 Ma. Thus, transformation of the oceanic crust into the continental one was a long-term and complicated process, and, as a result, the thickness of the sialic crust is increased in the study area.

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Dung, Joro Joshua, and Achuenu Ifeanyi. "Study of Origin, Geology and Geochemical Classification of the Granitoids of Imori Area, North Central Nigeria." International Journal of Engineering Research and Advanced Technology 08, no. 03 (2022): 16–29. http://dx.doi.org/10.31695/ijerat.2022.8.3.3.

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Two distinct generationsof granitiods in terms of space and time were identified in the Imori fields of north central Nigeria. The first generation is the Older Pan-Africa calc-alkaline granite suites(OPACG)which comprises the migmatite-gneiss and the porphyritic hornblende-biotite granite.The second group is the Younger Mesozoic alkali granite suites (YMAG).This comprises the rhyolite, biotite granite and arfvedsonite granite. The OPACGsuites are characterized by depletion in SiO2ranging from 63.30 wt % -68.38 wt % as compared to the YMAGsuites which range from 70.41 wt % -79.14 wt %. In addition, the OPACGsuites are characterized by higher concentrations of MgO, fe2O3, Al2O3, TiO2, CaO and Sr as compared to the YMAGsuites. The YMAGsuites are characterized by an excess of total alkaloids (Na2O +K2O), Cr, Nb, W, Ta, and lower concentrations of ferromagnesian minerals. These characteristic indicates that the OPACGsuites are generated from deep seated crustal levels rocks with the possibility of mantle materials. The YMAGsuites were originated from partial melting of crustal sialic materials. Both thetrace element patterns of the OPACG suites and the YMAGsuites indicate that each suiteis co-magmatic.

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Lozanova, Siya, Martin Ralchev, and Chavdar Roumenin. "Generation of Microparticles in Rock Structures." Proceedings of the Bulgarian Academy of Sciences 75, no. 12 (December 23, 2022): 1813–21. http://dx.doi.org/10.7546/crabs.2022.12.13.

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Regularity has been observed in the generation of microparticles during uniaxial deformation of rocks and building concretes with the following formula: a previously unknown phenomenon in solid non-regular structures has been experimentally established and investigated, which is expressed in emission of microparticles under the action of strong uniaxial pressures. The size and amount of the fine-dispersed microfractions depend on the substance’s physicalmechanical properties and pressure values. The paper presents the first results of the observed phenomenon in rock structures – granite and limestone originating from some regions of Bulgaria. The effect motivates the option for using the emission process as a new sensor method for assessment of the stress condition of solid-state systems.

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Hervé, Francisco, Robert J. Pankhurst, Robert Drake, Myrl E. Beck, and Constantino Mpodozis. "Granite generation and rapid unroofing related to strike-slip faulting, Aysén, Chile." Earth and Planetary Science Letters 120, no. 3-4 (December 1993): 375–86. http://dx.doi.org/10.1016/0012-821x(93)90251-4.

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Vorobiev, Oleg, Souheil Ezzedine, and Ryan Hurley. "Near-field non-radial motion generation from underground chemical explosions in jointed granite." Geophysical Journal International 212, no. 1 (September 22, 2017): 25–41. http://dx.doi.org/10.1093/gji/ggx403.

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Xu, XiSheng, WeiMin Lu, and ZhenYu He. "Age and generation of Fogang granite batholith and Wushi diorite-hornblende gabbro body." Science in China Series D: Earth Sciences 50, no. 2 (February 2007): 209–20. http://dx.doi.org/10.1007/s11430-007-2068-3.

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Contreras Inga, Carlos Efrain, Gabriel Walton, and Elizabeth Holley. "Statistical Assessment of the Effects of Grain-Structure Representation and Micro-Properties on the Behavior of Bonded Block Models for Brittle Rock Damage Prediction." Sustainability 13, no. 14 (July 14, 2021): 7889. http://dx.doi.org/10.3390/su13147889.

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The ability to predict the mechanical behavior of brittle rocks using bonded block models (BBM) depends on the accuracy of the geometrical representation of the grain-structure and the applied micro-properties. This paper evaluates the capabilities of BBMs for predictive purposes using an approach that employs published micro-properties in combination with a Voronoi BBM that properly approximates the real rock grain-structure. The Wausau granite, with Unconfined Compressive Strength (UCS) of 226 MPa and average grain diameter of 2 mm, is used to evaluate the effectiveness of the predictive approach. Four published sets of micro-properties calibrated for granites with similar mineralogy to the Wausau granite are used for the assessment. The effect of grain-structure representation in Voronoi BBMs is analyzed, considering grain shape, grain size and mineral arrangement. A unique contribution of this work is the explicit consideration of the effect of stochastic grain-structure generation on the obtained results. The study results show that the macro-properties of a rock can be closely replicated using the proposed approach. When using this approach, the micro-properties have a greater impact on the realism of the predictions than the specific grain-structure representation. The grain shape and grain size representations have a minor effect on the predictions for cases that do not deviate substantially from the real average grain geometry. However, the stochastic effect introduced by the use of randomly-generated Voronoi grain-structures can be significant, and this effect should be considered in future studies.

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Tuach, J., P. H. Davenport, W. L. Dickson, and D. F. Strong. "Geochemical trends in the Ackley Granite, southeast Newfoundland: their relevance to magmatic–metallogenic processes in high-silica granitoid systems." Canadian Journal of Earth Sciences 23, no. 6 (June 1, 1986): 747–65. http://dx.doi.org/10.1139/e86-077.

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The Ackley Granite, occupying an area of approximately 2700 km2, was intruded at about 355 Ma across the boundary between the Avalon and Gander tectonic terranes of southeast Newfoundland. It is dominated by K-feldspar-megacristic and equigranular biotite-bearing granite with subordinate granodiorite, but 10 separate phases have been recognized, also including hornblende- and muscovite-bearing varieties. Small aplite–pegmatite type molybdenite deposits occur in a southwest lobe, and cassiterite–wolframite-bearing quartz–topaz greisens are found as steeply dipping veins and pods within a south-central lobe of the pluton. A geochemical study of 357 rock samples, randomly distributed on a grid of 2 km spacing, shows systematic geographic variation in the concentrations of a range of elements.The concentrations of silica and some other elements show a relatively abrupt change approximately 10–15 km west of the projected boundary between the Avalon and Gander terranes, indicating that the different terranes had some influence on magma compositions, presumably as source rocks, that was preserved through subsequent ascent, cooling, and crystallization. Other elements change along smoother trends and support a model for the southeastern part of the Ackley Granite magma chamber (2100 km2) analogous to those inferred for chemically layered, high-silica ash-flow tuffs. This model entails a process of convective fractionation and (or) liquid-state diffusion that was responsible for early enrichment and depletion of certain elements in the magma and was accompanied by volatile exsolution and mineralization, especially in magma with more than 74% SiO2.Overall, the southeastern Ackley Granite has "I-type" granite affinities, evolving to "A-type" affinities in the shallower, more silicic mineralized varieties. This study indicates that neither the current concepts for generation of different types of granite nor the metallogenic concepts linking Mo and Sn–W deposits to specific types of granite are generally applicable. We suggest that high-level magmatic processes are adequate to produce such features and that any high-silica granitoid pluton that exhibits extreme enrichment of the large-ion lithophile elements and depletion of Ba and Sr is a potential host to granophile deposits.

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Trunilina, Vera A., and Andrei V. Prokopiev. "Petrology of Granites of the Tommot Rare-Earth Ore Field (Verkhoyansk–Kolyma Orogenic Belt)." Minerals 12, no. 11 (October 24, 2022): 1347. http://dx.doi.org/10.3390/min12111347.

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The article presents the results of studying the aegirine–arfvedsonite granites of the Somnitelnyi massif within the Tommot ore field located in the Verkhoyansk–Kolyma orogenic belt (NE Asia). Along with the crustal signatures, the rocks display features of mantle contamination at their origin. Their affinity for A-type granites characteristic of continental rifts and hot spots is shown. The associated Tommot REE deposit is the only one discovered in NE Russia. New data are presented for the previously studied Tommot massif within the same ore field, with a wide compositional range from alkaline-ultrabasic rocks to alkaline syenites. It is established that despite a common geochemical enrichment of both massifs’ rocks with REEs, the Somnitelnyi massif granites cannot be interpreted as the final phase of the Tommot massif emplacement. Specific REE mineralization and high crystallization temperatures (up to 1045 °C) of the Somnitelnyi granites may be explained by the existence within the study area of an undepleted mantle source (“hot spot”), whose maximum activity occurred during the granitic melt generation. The ore bodies of the Tommot deposit consist of fenitized albitites, granite gneisses, and, more rarely, the cross-cutting pegmatite veins. They are confined mostly to exocontacts of the Somnitelnyi massif, are less often in its endocontacts, and are not found in the host rocks and in the inner part of the massif away from the contacts. Principal ore minerals are chevkinite, yttrialite, gadolinite, and fergusonite. Based on the data obtained, the deposit is classified as a metasomatic complex Ce–Y–Nb–Zr deposit associated with the alkaline granites.

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Wu, Shanbai, Ruihua Zhao, Liping Liao, Yunchuan Yang, Yao Wei, and Wenzhi Wei. "Failure mode of rainfall-induced landslide of granite residual soil, southeastern Guangxi Province, China." Earth Surface Dynamics 10, no. 6 (November 4, 2022): 1079–96. http://dx.doi.org/10.5194/esurf-10-1079-2022.

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Abstract. Granite residual soil landslides are widely distributed in the southeast of Guangxi, China. They pose threats to local communities, economic development and ecological restoration. To understand the failure mode, the landslide can provide a scientific basis for early warning and prevention. In this study, we conducted artificial flume model tests to investigate the failure mode of granite residual soil landslide. The macroscopic phenomena of landslides were observed and summarized. The response and variations of soil moisture content and pore water pressure were analyzed. And the discrepancies in landslide initiation were explored. The results had three aspects: (1) the response of volume moisture content was not synchronized with that of pore water pressure. Their variations were influenced by initial dry density, slope angle and rainfall intensity. The fluctuation of pore water pressure depended on soil mechanical behavior and its diffusion. (2) The differences in the formation process of granite residual soil landslides included the initiation time and mode. The starting time of landslide was delayed with increasing initial dry density and slope angle but shortened with increasing rainfall intensity. The failure mode could be changed from a sudden type to a progressive type due to the increase in initial dry density. (3) There are five stages in the landslide mobilization as follows: rain infiltration and crack generation, soil slide at the slope toe, occurrence of surface runoff and soil erosion, formation of steep-free surface, and soil slide at the upper slope. This research can provide valuable reference for the prevention and early warning of granite residual soil landslide in southeastern Guangxi.

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Yue, Jun, Pan Huang, Jin Feng Cao, and Bao Cheng Feng. "Digital Image Processing Method Based Partial Differential Equation for Rock’s Microstructure." Applied Mechanics and Materials 90-93 (September 2011): 2597–600. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.2597.

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A digital image processing method based on partial differential equation(PDE) for rock’s heterogeneity is introduced. The actual microstructures of the rock sample was obtained by multiphase level set method. The main components of granite, quartz, feldspar and biotite, can be easily identified. The numerical results show that the method has advantage of self-adaptation and is benefit for grid generation in the following mechanical properties analyzing with Abaqus.

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Ledru, P., G. Courrioux, C. Dallain, J. M. Lardeaux, J. M. Montel, O. Vanderhaeghe, and G. Vitel. "The Velay dome (French Massif Central): melt generation and granite emplacement during orogenic evolution." Tectonophysics 342, no. 3-4 (December 2001): 207–37. http://dx.doi.org/10.1016/s0040-1951(01)00165-2.

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ZHANG, Wen, Yuhong LI, Fenghua ZHAO, Zheng ZHOU, Wei HAN, Junlin ZHOU, and Qiao ZHANG. "Granite is an Effective Helium Source Rock: Insights from the Helium Generation and Release Characteristics in Granites from the North Qinling Orogen, China." Acta Geologica Sinica - English Edition 94, no. 1 (February 2020): 114–25. http://dx.doi.org/10.1111/1755-6724.14397.

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Wang, Guo-Chang, Zheng Liu, Shu-Cheng Tan, Yu-Kun Wang, Xiao-Hu He, Mei-Li Li, and Chang-Shi Qi. "Petrogenesis of biotite granite with transitional I-A-type affinities: Implications for continental crust generation." Lithos 396-397 (September 2021): 106199. http://dx.doi.org/10.1016/j.lithos.2021.106199.

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LIU, Shixin, A. H. M. Faisal ANWAR, Takafumi SEIKI, and Yasuaki ICHIKAWA. "MICROCRACK GENERATION AND PROPAGATION IN GRANITE DURING STRESS RELAXATION UNDER WATER-SATURATED TRI-AXIAL CONDITION." Doboku Gakkai Ronbunshuu C 62, no. 3 (2006): 623–30. http://dx.doi.org/10.2208/jscejc.62.623.

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Johnson, Paul A., and Thomas J. Shankland. "Nonlinear generation of elastic waves in granite and sandstone: Continuous wave and travel time observations." Journal of Geophysical Research 94, B12 (1989): 17729. http://dx.doi.org/10.1029/jb094ib12p17729.

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Journal articles on the topic 'Granite generation'

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