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1
Chappell, B. W. "Towards a unified model for granite genesis." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 95, no. 1-2 (March 2004): 1–10. http://dx.doi.org/10.1017/s0263593300000870.
Повний текст джерелаАнотація:
ABSTRACTMost granites result from partial melting within the crust. Granite melts produced at the lowest temperatures of partial melting mainly comprise close to equal amounts of the haplogranite components Qz, Ab and Or, with H2O. Many felsic granites were formed by partial melting under such conditions and are low-temperature types, with crystals of zircon and other restite minerals present in the initial magma. Such magmas evolve in composition, at least initially, through fractionation of that restite. If one of the four haplogranite components either becomes depleted or too low in amount to contribute further to the melt, then melting may proceed to higher temperatures without a contribution from that component. Melting will advance to significantly higher temperatures if there is a critical deficiency in one or more components and a high-temperature granite magma forms, in which zircon is completely soluble. Such magmas are extracted from the source in a completely molten state and may evolve by fractional crystallisation. They are monzonitic, tonalitic or A-type, depending on whether the critical deficiency occurred in the Qz, Or or H2O component. If the Ab component is critically deficient, as in pelitic rocks, the rocks may be infertile for granite production. The control that source rock compositions exert on both the physical and chemical properties of granite magmas provides a unifying element in granite gen
2
Brown, M. "Granite: From genesis to emplacement." Geological Society of America Bulletin 125, no. 7-8 (June 7, 2013): 1079–113. http://dx.doi.org/10.1130/b30877.1.
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3
Zhang, Dachun, Isaac R. Kaplan, and Robert N. Clayton. "Nitrogen isotopes in granite genesis." Chinese Science Bulletin 43, S1 (August 1998): 155. http://dx.doi.org/10.1007/bf02891650.
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Dai, Hongzhang, Denghong Wang, Xin Li, Shanbao Liu, Chenghui Wang, and Yan Sun. "Genesis of the Wuzhutang Granite and Associated W–Sn–Be Mineralization in the Xuebaoding Mining Area, Sichuan Province, China." Minerals 12, no. 8 (August 5, 2022): 993. http://dx.doi.org/10.3390/min12080993.
Повний текст джерелаАнотація:
The Xuebaoding W–Sn–Be mining area, located in the Songpan–Garze orogenic belt in western China, is known for producing large, colorful, euhedral crystals of scheelite, cassiterite, and tabular beryl. Zircon LA-ICP-MS U–Pb dating of the Wuzhutang granite yields a concordia age of 218.96 ± 2.1 Ma, and a weighted mean 206Pb/238U age of 218.98 ± 1.12 Ma. Cassiterite LA-MC-ICPMS dating of the quartz vein bearing beryl, cassiterite, and scheelite, yields a concordant age of 213.5 ± 1.7 Ma. These observations indicate that magmatic activities and mineralization on the western side of the Zibaishan dome occurred during the late Indosinian, prior to their occurrence on the eastern side of the dome, reflecting the fact that the granite may have undergone two epochs of magmatic evolution and metallogenic processes. Geochemical analysis revealed that the Wuzhutang granite has relatively high A/CNK (average: 1.05) and differentiation index (DI; 81.16~85.88) values, and that they are enriched in W, Sn, Be, Li, and Cs. Unlike the Pukouling and Pankou granites, the Wuzhutang granite contains a certain amount of plagioclase and relatively high contents of Ba (633~1007 ppm) and Sr (334~411 ppm). Sr–Nd–Pb isotope values (87Sr/86Sr(t) = 0.70747–0.70865, εNd(t) = −6.35 to –4.34, 206Pb/204Pb = 18.186–18.3, 207Pb/204Pb = 15.556–15.592, and 208Pb/204Pb = 38.268–38.432) indicate a Mesoproterozoic basement origin for the Wuzhutang granite. We suggest the three granites belong to a peraluminous magma system and were derived by partial melting of the upper crust, the magma of the Wuzhutang granite originated from a deeper source and exhibits a lower degree of differentiation than that of the Pankou and Pukouling granites.
5
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.
Повний текст джерелаАнотація:
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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Clemens, J. D. "Preface." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 100, no. 1-2 (March 2009): v—vi. http://dx.doi.org/10.1017/s175569100901620x.
Повний текст джерелаАнотація:
The Sixth Hutton Symposium on the Origin of Granites and Related Rocks was held on July 2–6, 2007 at the University of Stellenbosch, South Africa, founded on granite, nestled at the feet of towering mountains and fringed by the rolling winelands of the Western Cape. This Special Issue opens with Master’s historical account of how the Cape granites influenced 18th and early 19th century thinking on the origins of these rocks. The fascinating fact is that the granites of the Western Cape were apparently the first intrusive granites recognised outside Britain. The balance of the volume contains a collection of research papers derived from the meeting and illustrates some of the important directions in which granite research may be evolving. One of the characteristics of the papers and talks presented at the meeting was that there seemed to be some shift in interest, away from the crust as a source of granitic magmas and towards mantle rocks that have been metasomatised by subduction-zone fluids or melts. Nevertheless, the crust still holds pride of place as the cradle of granite genesis.
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Liu, Shiyu, Yuping Liu, Lin Ye, Chen Wei, Yi Cai, and Weihong Chen. "Genesis of Dulong Sn-Zn-In Polymetallic Deposit in Yunnan Province, South China: Insights from Cassiterite U-Pb Ages and Trace Element Compositions." Minerals 11, no. 2 (February 13, 2021): 199. http://dx.doi.org/10.3390/min11020199.
Повний текст джерелаАнотація:
The Dulong Sn-Zn-In polymetallic deposit in the Yunnan province, SW China, hosts a reserve of 5.0 Mt Zn, 0.4 Mt Sn, and 7 Kt In. It is one of the most important polymetallic tin ore districts in China. Granites at Dulong mining area include mainly the Laojunshan granite (third phase), which occurs as quartz porphyry or granite porphyry dikes in the Southern edge of the Laojunshan intrusive complex. Granites of phases one and two are intersected at drill holes at depth. There are three types of cassiterite mineralization developed in the deposit: cassiterite-magnetite ± sulfide ore (Cst I), cassiterite-sulfide ore (Cst II) within the proximal skarn in contact with the concealed granite (granites of phases one to two and three), and cassiterite-quartz vein ore (Cst III) near porphyritic granite. Field geology and petrographic studies indicate that acid neutralising muscovitization and pyroxene reactions were part of mechanisms for Sn precipitation resulting from fluid-rock interaction. In situ U–Pb dating of cassiterite samples from the ore stages of cassiterite-sulfide (Cst II) and Cassiterite-quartz vein (Cst III) yielded Tera-Wasserburg U–Pb lower intercept ages of 88.5 ± 2.1 Ma and 82.1 ± 6.3 Ma, respectively. The two mineralization ages are consistent with the emplacement age of the Laojunshan granite (75.9–92.9 Ma) within error, suggesting a close temporal link between Sn-Zn(-In) mineralization and granitic magmatism. LA-ICPMS trace element study of cassiterite indicates that tetravalent elements (such as Zr, Hf, Ti, U, W) are incorporated in cassiterite by direct substitution, and the trivalent element (Fe) is replaced by coupled substitution. CL image shows that the fluorescence signal of Cst I–II is greater than that of Cst III, which is caused by differences in contents of activating luminescence elements (Al, Ti, W, etc.) and quenching luminescence element (Fe). Elevated W and Fe but lowered Zr, Hf, Nb, and Ta concentrations of the three type cassiterites from the Dulong Sn-Zn-In polymetallic deposit are distinctly different from those of cassiterites in VMS/SEDEX tin deposits, but similar to those from granite-related tin deposits. From cassiterite-magnetite ± sulfide (Cst I), cassiterite-sulfide ore (Cst II), to cassiterite-quartz vein ore-stage (Cst III), high field strength elements (HFSEs: Zr, Nb, Ta, Hf) decrease. This fact combined with cassiterite crystallization ages, indicates that Cst I–II mainly related to concealed granite (Laojunshan granites of phases one and two) while Cst III is mainly related to porphyritic granite (Laojunshan granites of phase three).
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Sun, Zhenjun, Guanghu Liu, Yunsheng Ren, Xi Chen, Xinhao Sun, Chengyang Wang, and Zuowu Li. "Age, Genesis and Tectonic Setting of the Sayashk Tin Deposit in the East Junggar Region: Constraints from Lu–Hf Isotopes, Zircon U–Pb and Molybdenite Re–Os Dating." Minerals 12, no. 9 (August 23, 2022): 1063. http://dx.doi.org/10.3390/min12091063.
Повний текст джерелаАнотація:
The Sayashk tin (Sn) deposit is located within the southern part of the Eastern Junggar orogenic belt in Xinjiang Province and forms part of the Kalamaili alkaline granite belt. There are many Sn polymetallic deposits in the area. To constrain the age, genesis, and tectonic setting of the Sayashk tin deposit in the East Junggar region, we conducted a bulk-rock geochemical analysis of the granite porphyry (SR1) and medium- to fine-grained granite (SR2) hosts of the deposit, LA-ICP-MS zircon U–Pb dating and Lu–Hf isotopic analysis, as well as molybdenite Re–OS dating and combined our results with the metallogenic conditions and other geological characteristics of the deposit. The results show that the Sayashk Sn deposit is indeed spatially, temporally, and genetically closely related to the granite porphyry and medium-fine-grained granite. Both zircon U–Pb ages are 308.2 ± 1.5 Ma and 310.9 ± 1.5 Ma, respectively. The isochron age of molybdenite is 301.4 ± 6.7 Ma, which represents the crystallization age of the granite porphyry and medium-fine-grained granite. Therefore, all of them formed in the late Carboniferous epoch. The medium-fine-grained granites and granite porphyry are characteristically rich in Si and alkali, poor in Ca and Mg, rich in high field-strength elements (HFSE, e.g., Zr, Hf) and Ce, and deficient in Ba, Sr, Eu, P, and Ti. They are typical A-type granites, showing the characteristics of a mixed crustal mantle source. The εHf(t) values of the zircon from the granite porphyry (SR1) range from 10.27 to 16.17 (average 13.71), εHf(t) values of the zircon from the medium-fine-grained granites (SR2) are between 5.72 and 9.21 (average 7.08), and the single model ages (TDM1) and two-stage model ages (TDM2) of the granite porphyry (SR1) fall within the ranges of 319~535 Ma and 339~644 Ma. The single model ages (TDM1) and two-stage model ages (TDM2) of the medium-fine-grained granites (SR2) fall within the ranges of 346~479 Ma and 309~557 Ma. There is little difference between their two-stage model ages and zircon U–Pb ages, indicating that the Sayashk granite may be the product of partial melting of juvenile crustal. Combined with previous research results, the Sayashk Sn deposit formed in a post-collision extensional tectonic setting after the late Carboniferous in the Kalamaili area.
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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.
Повний текст джерелаАнотація:
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.
10
Williamson, B. J., H. Downes, and M. F. Thirlwall. "The relationship between crustal magmatic underplating and granite genesis: an example from the Velay granite complex, Massif Central, France." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 83, no. 1-2 (1992): 235–45. http://dx.doi.org/10.1017/s0263593300007926.
Повний текст джерелаАнотація:
ABSTRACTThe Velay granite pluton (Massif Central, France) is the youngest (304 ± 5 Ma) and largest (∼6,900 km2) of the major Massif Central monzogranites/granodiorites and was formed nearly 50 Ma after the cessation of Hercynian continental collision (Pin & Duthou 1990). It is a highly heterogeneous pluton consisting of I-type, high-Sr granites (Sr = 500-900 ppm) with low (+35 to +41) and high (-3 to -5), at its centre, grading into S-type and mixed I-S-type heterogeneous granites of more normal Sr content (100–420 ppm) and higher (+40 to +210) and lower (-3·8 to -7.3) at its margins.The metasedimentary lower crust of the Massif Central was underplated/intruded by mafic mantle-derived magmas between 360 Ma and 300 Ma. From 300-280 Ma (Downes et al. 1991) underplating led to partial melting and granulite facies metamorphism of the underplated material (represented by felsic and mafic meta-igneous lower crustal xenoliths, = –11 to +112, = +2·2 to 8·2, Downes et al 1990). The partial melts assimilated mainly schist but also felsic gneiss and older granite country rock material ( = +100 to +300, = - 5 to -9) to produce the heterogeneous granites. Plagioclase and biotite were accumulated at the base of the intrusion which was intruded to high levels to form the high-Sr granites.
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Artemenko, G. V., L. V. Shumlyanskyy, I. A. Shvaika, and V. K. Butyrin. "AGE OF THE HANNIVKA GRANITE (MIDDLE-DNIEPER MEGABLOCK OF THE UKRAINIAN SHIELD)." Mineralogical Journal 44, no. 4 (2022): 73–83. http://dx.doi.org/10.15407/mineraljournal.44.04.073.
Повний текст джерелаАнотація:
The Middle-Dnieper megablock, which is a fragment of the craton, differs from other cratons found on Earth. This is because of the large variety of granitoids (Tokiv, Mokro-Moskowka, and Demuryne complexes) in the former that were formed after the Mesoarchean TTG. Thus, the Middle-Dnieper megablock is important for studying the genesis and geodynamic formation conditions of Late Archaean granitoids. The granitoids in the Middle-Dnieper megablock are not well understood. They include the Hannivka granites of the East Hannivka monocline of the Kryvyi Rih-Kremenchuk structure, whose age and stratigraphic position has been a matter of a long-standing debate. The purpose of the work is to study the geochemistry, genesis and U-Pb age of the Hannivka granites. Based on our results, the Hannivka granites possibly formed in the crust resulting from the melting of older rocks. They differ from other Late Archean granitoids of the Middle-Dnieper megablock by their high U (56.4 ppm) content and the presence of Mo (4.3 ppm). The Hannivka granites underwent tectonic reworking during a collisional event about 2.0 billion years ago, which is probably associated with the kalishpatization of these rocks. The U-Pb age of the cores of zircons sampled from the Hannivka granites, determined by LA-ICP-MS method, are about 2827±16 million years in age. Younger rims probably formed during kalishpatization. The Hannivka granites are the same age as the granitoids of the Mokro-Moskowka and Tokiv complexes. Late Archean granitoids were formed between 2.99-2.7 Ga in the Middle-Dnieper granite-greenstone block and in the geologically similar granite-greenstone block KMA are 2.6 Ga in age. In the Pilbara craton, which is a Paleoarchean granite-greenstone complex, the age of biotite and feldspar granites is similar to the age of the rocks on the Middle-Dnieper megablock (2.94-2.93 Ga). The difference in magmatism ages may be due to the drift of the different cratons above mantle plumes of different ages.
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Yuguchi, Takashi, Yuya Izumino, and Eiji Sasao. "Genesis and development processes of fractures in granite: Petrographic indicators of hydrothermal alteration." PLOS ONE 16, no. 5 (May 4, 2021): e0251198. http://dx.doi.org/10.1371/journal.pone.0251198.
Повний текст джерелаАнотація:
Biotites occur with varying degrees of alteration within a granite. This study analyzes the relationships among alteration indicators, areal microvoid fractions in chloritized biotite, and macroscopic fracture frequencies in the Toki granite, central Japan, to establish the genesis and development processes of fractures in granite. Appropriate characterizations for the frequency distribution of macroscopic fractures in granite can assist in understanding potential hydrogeological applications, which contributes to safety evaluations for geological disposal and storage. Borehole 06MI03, drilled to a depth of 191 m, was used to obtain samples for the analysis. In total, 24 samples that depicted variations in the macroscopic fracture frequency were selected. Petrographic alteration indicators using biotite chloritization as innovative methods are proposed to evaluate the extent of hydrothermal alteration and fracture frequency within granites. The alteration indicators are defined as the ratio between the alteration product area and the original mineral area. Furthermore, the volume of microscopic fractures and micropores in the mineral was quantitatively characterized by the areal fraction of microvoids in minerals through image analysis. Samples with high macroscopic fracture frequencies correspond to a high number of areal microvoid fractions and large alteration indicators. Microvoids, which are the source of macroscopic fractures, occurred at temperatures between 350 and 780°C and can be evaluated by intrinsic factors, such as alteration indicators. Subsequent faulting and unloading (extrinsic factors) developed microvoids into macroscopic fractures. Intrinsic factors are used to evaluate the source of macroscopic fractures, and therefore contribute to the characterization of present and future distributions of macroscopic fracture frequencies.
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Marignac, Christian, Michel Cuney, Michel Cathelineau, Andreï Lecomte, Eleonora Carocci, and Filipe Pinto. "The Panasqueira Rare Metal Granite Suites and Their Involvement in the Genesis of the World-Class Panasqueira W–Sn–Cu Vein Deposit: A Petrographic, Mineralogical, and Geochemical Study." Minerals 10, no. 6 (June 23, 2020): 562. http://dx.doi.org/10.3390/min10060562.
Повний текст джерелаАнотація:
Elucidation of time-space relationships between a given wolframite deposit and the associated granites, the nature of the latter, and their alterations, is a prerequisite to establishing a genetic model. In the case of the world-class Panasqueira deposit, the problem is complicated because the associated granites are concealed and until now poorly known. The study of samples from a recent drill hole and a new gallery allowed a new approach of the Panasqueira granite system. Detailed petrographic, mineralogical, and geochemical studies were conducted, involving bulk major and trace analyses, BSE and CL imaging, EPMA, and SEM-EDS analyses of minerals. The apical part of the Pansqueira pluton consisted of a layered sequence of separate granite pulses, strongly affected by polyphase alteration. The use of pertinent geochemical diagrams (major and trace elements) facilitated the discrimination of magmatic and alteration trends. The studied samples were representative of a magmatic suite of the high-phosphorus peraluminous rare-metal granite type. The less fractionated members were porphyritic protolithionite granites (G1), the more evolved member was an albite-Li-muscovite rare metal granite (G4). Granites showed three types of alteration processes. Early muscovitisation (Ms0) affected the protolithionite in G1. Intense silicification affected the upper G4 cupola. Late muscovitisation (Fe–Li–Ms1) was pervasive in all facies, more intense in the G4 cupola, where quartz replacement yielded quartz-muscovite (pseudo-greisen) and muscovite only (episyenite) rocks. These alterations were prone to yield rare metals to the coeval quartz-wolframite veins.
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Mughal, Muhammad Saleem, Chengjun Zhang, Amjad Hussain, Hafiz Ur Rehman, Dingding Du, Mirza Shahid Baig, Muhammad Basharat, Jingya Zhang, Qi Zheng, and Syed Asim Hussain. "Petrogenesis and Geochronology of Tianshui Granites from Western Qinling Orogen, Central China: Implications for Caledonian and Indosinian Orogenies on the Asian Plate." Minerals 10, no. 6 (June 2, 2020): 515. http://dx.doi.org/10.3390/min10060515.
Повний текст джерелаАнотація:
The precise timing, petrogenesis, and geodynamic significance of three granitoid bodies (Beidao granite, Caochuanpu granite, Yuanlongzhen granite, and the Roche type rock) of the Tianshui area in the Western Qinling Orogen, central China, are poorly constrained. We performed an integrated study of petrology, geochemistry, and zircon U-Pb dating to constrain their genesis and tectonic implication. Petrographic investigation of the granites shows that the rocks are mainly monzogranites. The Al saturation index (A/CNK versus SiO2) of the granitoid samples indicates meta-aluminous to peraluminous I-type granites. Their magmas were likely generated by the partial melting of igneous protoliths during the syn-collisional tectonic regime. Rare-earth-elements data further support their origin from a magma that was formed by the partial melting of lower continental crust. The Beidao, Caochuanpu, and Yuanlongzhen granites yielded U-Pb zircon weighted mean ages of 417 ± 5 Ma, 216 ± 3 Ma, and 219 ± 3 Ma, respectively. This study shows that the Beidao granite possibly formed in syn- to post-collision tectonic settings due to the subduction of the Proto-Tethys under the North China Block, and can be linked to the generally reported Caledonian orogeny (440–400 Ma) in the western segment of the North Qinling belt, whereas Yuanlongzhen and Caochuanpu granites can be linked to the widely known Indosinian orogeny (255–210 Ma). These granitoids formed due to the subduction of the oceanic lithospheres of the Proto-Tethyan Qinling and Paleo-Tethyan Qinling. The Roche type rock, tourmaline-rich, was possibly formed from the hydrothermal fluids as indicated by the higher concentrations of boron leftover during the late-stages of magmatic crystallization of the granites.
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Liu, Huimin, Zhaojun Song, Hongbo Yan, Wenyu Wang, Xinru Wang, Yifang Sun, and Haonan Li. "New View on the Genesis of the Bashuihe Pluton, Laoshan Granites, China: Indications from Fluid Inclusions and H–O Isotopes." Geofluids 2021 (February 6, 2021): 1–12. http://dx.doi.org/10.1155/2021/6655431.
Повний текст джерелаАнотація:
Oval caves have recently been discovered in the Bashuihe granite pluton of Laoshan Mountain, China. Oval caves typically occur in alkaline granites. This study conducted microthermometry and stable isotope analysis of quartz inclusions from oval caves and host rocks from the Bashuihe pluton to reconstruct the diagenetic evolutionary history of the Laoshan area. The temperature measurement results indicated a homogenisation temperature range from 162.5 to 261.6°C (mean 203.9°C), a salinity range of 2.1–8.3 wt% (mean 5.07 wt%), and a density range of 0.8–0.98 g/cm3 (mean 0.90 g/cm3), indicating a low-temperature, low-salinity, and low-density fluid. The emplacement depth ranged from 2.73 km to 4.43 km, indicating medium-shallow granite. A hydrogen and oxygen isotope analysis ( δ D = − 83.58 – − 67.17 , δ 18 O H 2 O = 0.83 – 0.39 ) revealed that the diagenetic fluids of the Bashuihe pluton represented a mixed hydrothermal solution composed of meteoric water and magmatic water. The results of a whole rock, H–O isotopes, rare earth element, and high field strength element analysis on the Laoshan alkali granites suggest significant hydrothermal activity in the late stage of magmatism. Primary oval caves in the Bashuihe pluton most likely evolved in the following sequence: fluid was enriched in the late diagenetic stage, diagenetic minerals crystallised under low temperature and pressure conditions, the crystallisation rate accelerated, and the magma condensed rapidly. Moreover, the increase in magma fluid enabled the movement and convergence of fluid. The accumulated fluid and volatiles occupied more space, and rapid magma condensation trapped the accumulated fluid and volatiles in the pluton, forming the oval granite cave. This research provides a crucial theoretical reference for the development and utilisation of underground space and engineering buildings in granite regions.
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Leonov, M. G., E. S. Przhiyalgovskii, E. V. Lavrushina, and A. V. Nikitin. "GRANITE ISLAND MOUNTAINS: MORPHOLOGY, TECTONIC STRUCTURE AND GENESIS." Geomorphology RAS, no. 3 (January 1, 2017): 3–15. http://dx.doi.org/10.15356/0435-4281-2017-3-3-15.
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Wang, Dezi, Yaming Pen, and Pu Yuan. "Petrology, geochemistry and genesis of Kuiqi granite batholith." Chinese Journal of Geochemistry 5, no. 2 (April 1986): 97–107. http://dx.doi.org/10.1007/bf02885383.
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Gonçalves, Ana, Helena Sant’Ovaia, and Fernando Noronha. "Geochemical Signature and Magnetic Fabric of Capinha Massif (Fundão, Central Portugal): Genesis, Emplacement and Relation with W–Sn Mineralizations." Minerals 10, no. 6 (June 20, 2020): 557. http://dx.doi.org/10.3390/min10060557.
Повний текст джерелаАнотація:
The Fundão–Serra da Estrela–Capinha (FSEC) region is characterized by peraluminous to metaluminous Variscan granites intrusive in a complex and thick metasedimentary sequence. This work seeks to characterize the Capinha granite (CG), understand its spatial and genetic relationship with the host Peroviseu–Seia (PS), Belmonte–Covilhã (BC) and Fáguas granites, and evaluate its metallogenic potential. To achieve these goals, a multidisciplinary approach was undertaken, including field work and identification of the petrography and microstructures, whole rock geochemistry and anisotropy of magnetic susceptibility. Four distinct and independent differentiation trends were identified in the granites, namely, PS, BC, Fráguas and CG. The PS and BC played a role as host rocks for the W and Sn mineralizations. The Fráguas granite is anomalous in Sn and spatially related to the Sn–Li mineralizations, while the CG is anomalous in W and spatially related to W–Sn mineralizations. The post-tectonic CG is a peraluminous ilmenite-type whose ascent and emplacement were tectonically controlled. The Capinha magma used the intersection between the 25° N and 155° N strike–slip crustal scale faults for passive ascent and emplacement during the late-Variscan extensional phases. The magnetic fabric was drawn using an asymmetric tongue-shaped laccolith for CG. CG experienced two brittle deformation stages that marked the maximum compressive rotation from NE–SW to NNW–SSE.
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Chen, Binghan, Jun Deng, and Xingzhong Ji. "Time Limit of Gold Mineralization in Muping–Rushan Belt, Eastern Jiaodong Peninsula, China: Evidence from Muscovite Ar–Ar Dating." Minerals 12, no. 3 (February 23, 2022): 278. http://dx.doi.org/10.3390/min12030278.
Повний текст джерелаАнотація:
Controversy surrounds the genetic relationship between gold mineralization and magmatism, especially in deposits in granite. Jiaodong Peninsula is the leading gold province in China, and most deposits are in Mesozoic granites; moreover, debate on the genesis persists. In eastern Jiaodong, the Muping–Rushan gold belt produces mainly quartz–sulfide vein-type gold, and the Upper Jurassic Kunyushan granite and Late Lower Cretaceous Sanfoshan granite are the wall rock. Precise mineralization ages should be identified to determine whether gold is related to the intrusion. In this study, three gold deposits (Sanjia, Yinggezhuang, and Xipo) from two ore-controlling faults were considered. Muscovites from quartz–sulfide veins and beresite were selected for Argon–Argon dating. The results obtained were 116.51 ± 0.47 Ma, 120.02 ± 0.38 Ma, and 121.65 ± 0.48 Ma for the three deposits, respectively. The mineralization lasted about 5 Ma in the Muping–Rushan gold belt. The test results showed that the mineralization was 16 Ma later than the intrusion time of Kunyushan granite and was earlier than that of Sanfoshan granite. Only the cooling age overlapped with the mineralization age. Previous studies have demonstrated that the ore fluid is of medium–low salinity and medium–low temperature. No typical high–low temperature mineral assemblage exists in the Muping–Rushan gold belt. Hence, gold deposits in Muping–Rushan gold belt could not be categorized as intrusion-related gold type.
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Liu, Zekun. "Metallogenic characteristics and genesis of granite type uranium ore bodies in South China." E3S Web of Conferences 261 (2021): 02068. http://dx.doi.org/10.1051/e3sconf/202126102068.
Повний текст джерелаАнотація:
South China is the key producing area of granite-type uranium deposits in China. After decades of exploration, many important progress has been made in the study of metallogenic regularity of granite type uranium deposits in this area. On the basis of previous studies, this paper attempts to sort out the geological conditions and characteristics of diagenesis and mineralization of granite type uranium deposits in South China, and discuss their metallogenic models, so as to better summarize the metallogenic regularity and serve the prospecting and prediction.
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Elbaev, A. L., I. V. Gordienko, V. B. Khubanov, and O. V. Zarubina. "Petrogeochemical characteristics and U-Pb age of morion-granite rocks in Central Transbaikalia: Classification and genesis problems." LITHOSPHERE (Russia) 20, no. 5 (October 30, 2020): 690–705. http://dx.doi.org/10.24930/1681-9004-2020-20-5-690-705.
Повний текст джерелаАнотація:
Research subject. This article presents data on the age, material composition, petrogenetical and geochemical properties of morion-containing granites in the Etytei and Khamnigadai massifs of Central Transbaikalia.Materials and methods. The composition of rock samples was investigated using the methods of chemical analysis, XRD and ICP-MS; the age was determined by the zircon U–Pb method using SHRIMP and LA-ICP-MS; the mineral composition was studied using an LEO-1430 electron microscope.Results. The massifs composed of morion-containing granites belong to Early Jurassic (190–185 Ma) and form the peripheral area of the Early Mesozoic Khentei-Dauria magmatic region.Conclusion. According to their petrochemical and mineralogical characteristics, the morion-containing granites under study differ from typical intra-plate granitoids and correspond to the “oxidized” A-type granites. The black smoky colour of quartz contained in granite samples is associated with a relatively high radioactivity of rocks caused by the presence of accessory thorium and uranium-containing minerals.
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Mbaihoudou, Diontar, Kwékam Maurice, Fozing Eric Martial, Kagou Dongmo Armand, and Tcheumenak Kouémo Jules. "Petrology and Geochemical Characteristic of Granitoids From Guéra Massif in the Central Part of Chad: An Example of Mixing Magmas." Earth Science Research 9, no. 2 (July 6, 2020): 66. http://dx.doi.org/10.5539/esr.v9n2p66.
Повний текст джерелаАнотація:
The granitoids of Guéra Massif are composed of biotite-granite, amphibole-biotite granite and gabbro-diorite and commonly contain micro granular mafic enclaves which vary from monzogabbro to syenite composition. They are metaluminous, high-K calc-alkaline to shoshonitic series. Gabbro-diorite rocks are magnesian while amphibole-biotite granites are magnesian to ferroan, and biotite granites are ferroan. They are enriched in LREEs relative to HREE and display negative anomalies in Nb, Ta and Ti. Fields relationships, petrology and geochemistry indicate that mixing and mingling processes could be more relevant for the genesis of granitoids associated to fractional crystallization. Thus, the presence of mafic enclaves of gabbro-diorite composition in the granites, the resumption of alkaline feldspar xenocrystals in the gabbro-diorites, as well as the linear correlation between the granites and the gabbro-diorites and the intermediate position of the mafic enclaves between the two formations, enable us to propose magmatic mixing as the major process that presided over the evolution of the Guéra granitoids. The delamination of the continental lithosphere during the post-collisional phase of the Pan-African orogeny would have caused the partial melting of the subduction-modofied mantle and lower continental crust and thus produced the magmas of the Guéra granitoids.
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Sardi, Fernando G., Pablo Grosse, Mamoru Murata, and Rafael Pablo Lozano Fernández. "Internal framework and geochemistry of the Carboniferous Huaco granite pluton, Sierra de Velasco, NW Argentina." Andean Geology 45, no. 2 (March 5, 2018): 229. http://dx.doi.org/10.5027/andgeov45n2-3015.
Повний текст джерелаАнотація:
The A-type Huaco granite pluton of the Velasco range (Sierras Pampeanas of northwest Argentina) is formed by three coeval granitic facies and contains subordinate coeval-to-late facies, as well as enclaves, dikes and stocks that show different temporal relations, textures and compositions. The dominant facies (Regional Porphyritic Granite; RPG) is a porphyritic two-mica monzo- to syenogranite, with abundant microcline megacrysts up to 12 cm in size. It was emplaced in a dominant extensional setting and has a mainly crustal source but with participation of a mantle-derived component. The RPG transitions towards two coeval and co-genetic granite facies, at its margins (Border Granite; BG) and around Be-pegmatites (Adjacent Porphyritic Granite; APG). These two facies have a finer-grained texture and smaller and less abundant megacrysts. They are also monzo- to syenogranites, but a slight decrease in the biotite/muscovite ratio is observed from the BG to the RPG to the APG. Trace element modeling suggests that the RPG, BG and APG differentiated from the same magma source by fractional crystallization. Temporally older mafic (ME) and felsic (FE) enclaves are common in the pluton. The ME can be considered partially assimilated remnants of a mafic component in the genesis of the RPG, whereas the FE seem to be remnants of premature aplites. Other subordinate rocks intrude the RPG and are, hence, temporally younger: felsic dikes (FD), dioritic dikes (DD) and equiganular granites (EqG) are clearly posterior, whereas coeval-to-late Be-pegmatites (BeP) and orbicular granites (OG) formed during the final stages of crystallization of the pluton. The BeP, OG and FD indicate the presence of abundant water and volatiles. The EqG form small stocks that intrude the RPG and were possibly originated from purely crustal sources. The DD probably correspond to a younger unrelated episode of mafic magmatism.
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Wang, Jian She, Yong Feng Yan, Dong Wang, and Peng Yu Feng. "Geological Characteristics and Prospecting Criteria of Sanbao Silver Polymetallic Ore Deposit in Malipo Cuntry of Yunnan Province." Advanced Materials Research 868 (December 2013): 88–91. http://dx.doi.org/10.4028/www.scientific.net/amr.868.88.
Повний текст джерелаАнотація:
Sanbao silver polymetallic deposit is overally located in the front of "North convex" in Laojun Mountain granite body, belonging to polymetallic deposit of stratabounded medium-low temperature hydrothermal reformation genesis. It has been found that six mineralized belt, having developed the wall-rock alteration. The prospecting criterion is determined by ore genesis and ore-controlling factor.
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Liu, Xue Long, Na Zhang, Peng Wang, and Fu Cheng Yang. "Geochemical Characteristics and Genesis Discussion with Rock Metallogenic Belt of Geza Island Arc, Yunnan." Advanced Materials Research 1073-1076 (December 2014): 2015–18. http://dx.doi.org/10.4028/www.scientific.net/amr.1073-1076.2015.
Повний текст джерелаАнотація:
Geza island arc located in the southwest Sanjiang tectonic igneous rock belts which was a products of Ganzi-Litang oceanic crust diving to Zhongdian Landmasses in late Triassic. Lithogeochemical characteristics shown that the porphyry(porphyrite) and island-arc granite rocks have the same rock series (high-K calc-alkaline) and the same genetic type (I-type granite); these rocks trace elements similar to the granite of island arc,which enriched in Ba, La, Hf, Au,chalcophile elements Cu,Pb, siderophile elements Mo, Ni, and depleted in Rb, Nb, P, Ti. In this region, the similarities of porphyry and local acidic volcanic rocks in the main elements, REE and other trace elements and the composition suggest that they both have the same or similar magmatic source rocks. It is shown that the characteristics of the rock with the island arc granite partial melting of source rock, that may come from the arc type volcano rock or island arc volcano rock cognate magma evolution.
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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.
Повний текст джерелаАнотація:
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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Stone, M., J. Klomínský, and G. S. Rajpoot. "Composition of trioctahedral micas in the Karlovy Vary pluton, Czech Republic and a comparison with those in the Coruubian batholith, SW England." Mineralogical Magazine 61, no. 409 (December 1997): 791–807. http://dx.doi.org/10.1180/minmag.1997.061.409.04.
Повний текст джерелаАнотація:
AbstractTrioctahedral micas in the Karlovy Vary pluton range in composition from Fe-biotites in the granites of the Older Intrusive Complex (OIC) through siderophyllite and lithian siderophyllite to zinnwaldite in the granites of the Younger Intrusive Complex (YIC). Li + AlVI + Si would appear to substitute for Fe2+ + AlIV in biotite with a formula similar to that given in Henderson et al. (1989), but Li + Si appears to substitute for Fe2+ + AlIV in the Li-micas. In mica vs. host rock plots, Rb and F show positive linear covariation except for the Li-mica granites, but femic constituents and tFeO/(tFeO + MgO) have separate trends for OIC and YIC granites and micas. Further differences between OIC and YIC granite micas are seen in their Ti and Mg contents and in plots like V vs. SiO2, AlIVvs. Fe/(Fe+Mg) and Li vs. total iron as Fe2+ and in the results of discriminant analysis. These reveal a geochemical hiatus between OIC and YIC granite micas that coincides with a major temporal hiatus.Biotite compositions in the YIC granites are similar to those in the granites of the Cornubian batholith and reveal a similar magmatic evolution and genesis in which later biotites evolve to lithian siderophyllites with some enrichment in trace alkalis and F. It is suggested that the biotite granites in the YIC were derived from the products of partial fusion of the OIC granites. A less well-marked geochemical hiatus exists between YIC biotites and zinnwaldites. In some plots (e.g. Si vs. Li, Li vs. tFe) apparent continuity between biotite and the Li-micas suggests continuous evolution, but in others (e.g. Rb vs. TiO2, Rb(biotite) vs. Rb(rock)), Li-mica data points stand apart from the biotites suggesting, like the whole rock data, a separate evolution. Comparison with the more abundant data for Li-micas of the Cornubian batholith suggests derivation of the Li-mica granites by partial fusion of the OIC/YIC granite residues.
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Khomichev, V. L. "GENESIS OF GRANITOID (GABBRO-GRANITE) PLUTONS AND ASSOCIATED MINERALIZATION." Geology and mineral resources of Siberia, no. 2 (June 2022): 78–87. http://dx.doi.org/10.20403/2078-0575-2022-2-78-87.
Повний текст джерелаАнотація:
Deep geological and geophysical modeling by a large number of granitoid plutons for the first time showed a completely different nature than was commonly believed. As a result, ideas about the connection of mineralization with them have changed dramatically. Many petrological contradictions and puzzles were solved logically and scientifically grounded. The complete and comprehensive review of the problem from the beginning (source of the initial magma) to the end (formation of the granite ore-magmatic system) is given. Three stages of the volatiles and ore matter concentration in the history of the plutons formation were established: the first (planetary) - during the intrachamber differentiation of the initial basalt magma with an isolation of granitoid melting; the second (regional) - during the formation of a residual leukogranite chamber the third, main (local) - during the intrusion of ore-generating apophyses from the chamber.
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Meighan, I. G., A. E. Fallick, and A. G. McCormick. "Anorogenic granite magma genesis: new isotopic data for the southern sector of the British Tertiary Igneous Province." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 83, no. 1-2 (1992): 227–33. http://dx.doi.org/10.1017/s0263593300007914.
Повний текст джерелаАнотація:
ABSTRACTIt is now generally accepted that British Tertiary granites contain crustal and mantle components. Genesis principally by differentiation of crustally contaminated basaltic magmas is widely held and silicic melts with some remarkable trace element similarities were generated within different upper crust along the St Kilda/Skye - Carlingford zone.New whole-rock (and mineral) O isotope data for the southern sector of the province (N Arran, Ailsa Craig, Mourne Mountains, Slieve Gullion, etc) reveal that δ18O lies in the range +5·1 to +9·7‰ for most of the analysed granites, meteoric water-rock interaction having been in general less intensive than at Skye and Mull. Nevertheless, highly 18O-depleted country rocks (with δ18O<0) exist adjacent to the N Arran and Mourne Mountains granite plutons. There is as yet no evidence for the existence of low -18O granitic melts in this southern sector where magmatic δ18O compositions (up to c. + 9·5‰) can be inferred for some of the intrusions.New Nd (and Sr) isotope data indicate that although there is some similarity in initial 87Sr/86Sr ratios between the northern and southern sector granites, in northeastern Ireland initial εNd values for the analysed Tertiary acid major intrusions range from −3·9 to −4·5. This is in marked contrast to the Skye granites, some of which have values below −20, reflecting the involvement of different lithosphere.
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Li, Ying Shu, Yan Cai, Nan Chen, Jiao Jiao Chen, Lun Wang, Yi Ke Zhang, and Da Qing He. "Source of Tinny Granite in Gejiu Tin Ore Deposit in Yunnan Province, China." Advanced Materials Research 634-638 (January 2013): 3493–97. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.3493.
Повний текст джерелаАнотація:
It had been believed that the genesis of tinny granite in Gejiu tin ore deposits were hydrothermal mineralization in granite of Yanshanian epoch by most researchers for a long time. However, according to the form, attitude and sulphur isotope in the ore of the oreboby, the authors believe the genesis of the tin ore deposit is relict body of granitic superimposed ore-forming of the Yanshanian epoch after the basic volcano ore-forming of the Indo-Chinese epoch. It’s proved that the form and attitude of the oreboby is basically consistent with the form and attitude of the basalt of the Indo-Chinese epoch. Because sulphur isotope in pyrite of the ore is from 0.21 per thousand to 4.4 per thousand, feature of source of the mantle sulphur isotope is reflected.
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Stone, Maurice. "The Significance of Almandine Garnets in the Lundy and Dartmoor Granites." Mineralogical Magazine 52, no. 368 (December 1988): 651–58. http://dx.doi.org/10.1180/minmag.1988.052.368.09.
Повний текст джерелаАнотація:
AbstractAlmandine garnets in the cordierite-bearing granite of Sweltor Quarry, Dartmoor, contain < 10 mol. % of the spessartine end-member, whilst those in the Lundy granite have c. 10 mol. % spessartine. Experimental work indicates that such compositions can grow in equilibrium with siliceous melts at depths of 18–25 km. This evidence, reaction rims, lack of marked zoning and comparison with garnets in other siliceous calc-alkaline siliceous rocks point to a genesis involving partial melting of the ‘local’ lower crust. A restite origin rather than direct crystallization from magma is favoured but the evidence is equivocal. The Dartmoor granite (Hercynian) is a typical peraluminous late- to post-tectonic S-type granite. The S-type character of the Lundy (Tertiary) granite is revealed by the occurrence of garnet and topaz together with biotite enriched in Rb, Cs and F, despite its close association with Tertiary basic magmatism in an anorogenic setting.
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Pupin, Jean-Pierre. "Granite genesis related to geodynamics from Hf—Y in zircon." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 91, no. 1-2 (2000): 245–56. http://dx.doi.org/10.1017/s0263593300007410.
Повний текст джерелаАнотація:
Zircon is a very interesting accessory mineral, a kind of ‘crustal diamond’, easily recycled and recording through large morphological variability the main rock-forming events. Since 1985, a systematic study of chemical variability of zircon in magmatic rocks has led to the definition of three main generations in zircon populations: inherited phase 1, magmatic phase 2 and late magmatic phase 3. Hafnium and yttrium appear to be the most useful for source characterisation, especially if using phase 2 data. As a consequence, a new diagram of HfO2versus Y2O3is proposed, divided into domains la to 6b to describe the distribution of the genetic groups and the specific domains for anorogenic and orogenic rocks. Zircon in anorogenic granitoids: tholeiitic plagiogranites (high Y, low Hf), hypersolvus (medium to low Y, low Hf) and subsolvus (medium to high Y and Hf) alkaline granites/rhyolites, has separate mean distributions. Genetic relations existing between rocks with obvious textural differences (granites, microgranites, rhyolites) are also recognised. Zircon in orogenic granitoids is Y-poor and shows a very limited distribution, but the minimal average values in magmatic zircon vary from 11 000 wt ppm HfO2in the calc-alkaline suite, to 12 000 ppm in the peraluminous porphyritic granites and to 13 500 ppm in entirely crustal anatectic granites and migmatites. Mixing-mingling processes are proposed to explain the intermediate characteristics of zircons and rocks in the peraluminous porphyritic and K-subalkaline granites. This is consistent with the time emplacement and space distribution of these two orogenic members, but leads to a new proposal of emplacement of some alkaline subsolvus magmas during orogenic cycles.
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Evans, C. V., and W. A. Bothner. "Genesis of altered conway granite (grus) in New Hampshire, USA." Geoderma 58, no. 3-4 (October 1993): 201–18. http://dx.doi.org/10.1016/0016-7061(93)90042-j.
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Hettmann, Kai, Wolfgang Siebel, Cornelia Spiegel, and John Reinecker. "Granite genesis and migmatization in the western Aar Massif, Switzerland." Neues Jahrbuch für Mineralogie - Abhandlungen 186, no. 3 (October 1, 2009): 309–20. http://dx.doi.org/10.1127/0077-7757/2009/0150.
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France-Lanord, Christian, and Patrick Le Fort. "Crustal melting and granite genesis during the Himalayan collision orogenesis." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 79, no. 2-3 (1988): 183–95. http://dx.doi.org/10.1017/s0263593300014206.
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ABSTRACTThis paper reviews the petrogenesis of Himalayan leucogranites (HHγ) on the basis of field, petrological and geochemical data collected over the last fifteen years. HHγ are intruded at the top of the 2 to 8km-thick High Himalayan Crystallines (HHC). These are metamorphosed (Ky to Sill) and present much evidence of partial melting. During the MCT thrusting, the already metamorphosed HHC were thrust on top of the weakly metamorphosed Midland Formations, inducing the main phase of Himalayan metamorphism. The genesis of HHγ and North Himalaya leucogranites (NHγ) associates thrusting along the MCT, propagation of inverted metamorphism, liberation of large quantities of fluid in the Midlands, and partial melting of the HHC.The restricted compositions of the granites are close to minimum melt compositions; variations in the alkali ratio probably relate to the variable amount of B, F and H2O. The HHγ were issued from the migmatitic zone around 700°C and 800 MPa., and still emplaced some 10 to 15 km below the surface. This syn- to late-tectonic emplacement of the leucogranites lasted for more than 10 Ma according to isotopic ages (25 to 14 Ma).O, Rb–Sr, Nd–Sm and Pb isotope studies corroborate the unambiguous filiation between the HHC and the leucogranites in central Nepal. They also imply that the plutons are generated as numerous poorly mixed batches of magma produced preferentially in specific zones of the source rock. δD values may be explained by infiltration of water from the Midlands in the melting zone, and/or by water degassing during crystallisation. The positive covariations between Sr-, Nd- and O-isotope ratios relate to the variations in the original sediment composition of the source gneisses. Whereas trace element characteristics often date back to the anatectic process, limited magmatic differentiation is recorded by the biotite. These granites are typical crustal products, keeping track of some of the pre-Himalayan evolution together with that of their own origin.
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Lu, Lei, Yan Liu, Huichuan Liu, Zhi Zhao, Chenghui Wang, and Xiaochun Xu. "Geochemical and Geochronological Constraints on the Genesis of Ion-Adsorption-Type REE Mineralization in the Lincang Pluton, SW China." Minerals 10, no. 12 (December 12, 2020): 1116. http://dx.doi.org/10.3390/min10121116.
Повний текст джерелаАнотація:
Granites are assumed to be the main source of heavy rare-earth elements (HREEs), which have important applications in modern society. However, the geochemical and petrographic characteristics of such granites need to be further constrained, especially as most granitic HREE deposits have undergone heavy weathering. The LC batholith comprises both fresh granite and ion-adsorption-type HREE deposits, and contains four main iRee (ion-adsorption-type REE) deposits: the Quannei (QN), Shangyun (SY), Mengwang (MW), and Menghai (MH) deposits, which provide an opportunity to elucidate these characteristics The four deposits exhibit light REE (LREE) enrichment, and the QN deposit is also enriched in HREEs. The QN and MH deposits were chosen for study of their petrology, mineralogy, geochemistry, and geochronology to improve our understanding of the formation of iRee deposits. The host rock of the QN and MH deposits is granite that includes REE accessory minerals, with monazite, xenotime, and allanite occurring as euhedral inclusions in feldspar and biotite, and thorite, fluorite(–Y), and REE fluorcarbonate occurring as anhedral filling in cavities in quartz and feldspar. Zircon U–Pb dating analysis of the QN (217.8 ± 1.7 Ma, MSWD = 1.06; and 220.3 ± 1.2 Ma, MSWD = 0.71) and MH (232.2 ± 1.7 Ma, MSWD = 0.58) granites indicates they formed in Late Triassic, with this being the upper limit of the REE-mineral formation age. The host rock of the QN and MH iRee deposits is similar to most LC granites, with high A/CNK ratios (>1.1) and strongly peraluminous characteristics similar to S-type granites. The LC granites (including the QN and MH granites) have strongly fractionated REE patterns (LREE/HREE = 1.89–11.97), negative Eu anomalies (Eu/Eu* = 0.06–0.25), and are depleted in Nb, Zr, Hf, P, Ba, and Sr. They have high 87Sr/86Sr ratios (0.710194–0.751763) and low 143Nd/144Nd ratios (0.511709–0.511975), with initial Sr and Nd isotopic compositions of (87Sr/86Sr)i = 0.72057–0.72129 and εNd(220 Ma) = −9.57 to −9.75. Their initial Pb isotopic ratios are: 206Pb/204Pb = 18.988–19.711; 208Pb/204Pb = 39.713–40.216; and 207Pb/204Pb = 15.799–15.863. The Sr–Nd–Pb isotopic data and TDM2 ages suggest that the LC granitic magma had a predominantly crustal source. The REE minerals are important features of these deposits, with feldspars and micas altering to clay minerals containing Ree3+ (exchangeable REE), whose concentration is influenced by the intensity of weathering; the stronger the chemical weathering, the more REE minerals are dissolved. Secondary mineralization is also a decisive factor for Ree3+ enrichment. Stable geology within a narrow altitudinal range of 300–600 m enhances Ree3+ retention.
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Broska, Igor, and Igor Petrík. "Genesis and stability of accessory phosphates in silicic magmatic rocks: a Western Carpathian case study." Mineralogia 39, no. 1-2 (January 1, 2008): 53–66. http://dx.doi.org/10.2478/v10002-008-0004-6.
Повний текст джерелаАнотація:
Genesis and stability of accessory phosphates in silicic magmatic rocks: a Western Carpathian case studyThe formation of accessory phosphates in granites reflects many chemical and physical factors, including magma composition, oxidation state, concentrations of volatiles and degree of differentiation. The geotectonic setting of granites can be judged from the distribution and character of their phosphates. Robust apatite crystallization is typical of the early magmatic crystallization of I-type granitoids, and of late magmatic stages when increased Ca activity may occur due to the release of anorthite from plagioclase. Although S-type granites also accumulate apatite in the early stages, increasing phosphorus in late differentiates is common due to their high ASI. The apatite from the S-types is enriched in Mn compared to that in I-type granites. A-type granites characteristically contain minor amounts of apatite due to low P concentrations in their magmas. Monazite is typical of S-type granites but it can also become stable in late I-type differentiates. Huttonite contents in monazite correlate roughly positively with temperature. The cheralite molecule seems to be highest in monazite from the most evolved granites enriched in B and F. Magmatic xenotime is common mainly in the S-type granites, but crystallization of secondary xenotime is not uncommon. The formation of the berlinite molecule in feldspars in peraluminous melts may suppress phosphate precipitation and lead to distributional inhomogeneities. Phosphate mobility commonly leads to the formation of phosphate veinlets in and outside granite bodies. The stability of phosphates in the superimposed, metamorphic processes is restricted. Both monazite-(Ce) and xenotime-(Y) are unstable during fluid-activated overprinting. REE accessories, especially monazite and allanite, show complex replacement patterns culminating in late allanite and epidote formation.
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Snachev, A. V., V. N. Puchkov, V. I. Snachev, and М. А. Romanovskaya. "Geodynamic and physico-chemical conditions of formation of the Stepninsky monzogabbro-granosyenite-granite complex (Southern Urals)." Moscow University Bulletin. Series 4. Geology, no. 6 (December 28, 2018): 82–92. http://dx.doi.org/10.33623/0579-9406-2018-6-82-92.
Повний текст джерелаАнотація:
Geological structure and physic-chemical characteristics of the Stepninsky, Vandyshevsky, Biryukovsky and Uisky massives related to the Stepninsky monzogabbro-granosyenite-granite complex are described. A conclusion was made that the depth of crystallization of the granitoid massives changes in this row from hypabbyssal to hypabyssal-subsurface facies. It is shown that the intrusions of the complex belong to the intraplate type. At the early stage, the basicintermediate rocks of a deep-mantle genesis were formed, which can be regarded as a derivative of an individual plume; at the later stage they were changed by granites and leucogranites of the calc-alkaline type, formed as a result of anatexis of the lower crust. The rocks of the later stage have a rare-metal geochemical specialization.
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Tian, Li, Deyou Sun, Jun Gou, Shan Jiang, Zhao Feng, Duo Zhang, and Yujie Hao. "Petrogenesis of the Newly Discovered Early Cretaceous Peralkaline Granitic Dikes in Baerzhe Area of Jarud Banner, Inner Mongolia: Implications for Deciphering Magma Evolution." Minerals 12, no. 12 (November 29, 2022): 1532. http://dx.doi.org/10.3390/min12121532.
Повний текст джерелаАнотація:
The super-large Baerzhe Be–Nb–Zr–REE deposit in NE China is hosted in the Early Cretaceous peralkaline granites. In this work, the newly discovered granitic dikes developed around the Baerzhe deposit were studied for the first time, focusing on their genesis and genetic relationships with the Baerzhe peralkaline granites. Zircon U-Pb dating of these granitic rocks (including the granite porphyry, rhyolite and miarolitic granite) yielded Early Cretaceous ages of 125–121 Ma. Their mineral assemblages and geochemical features suggest that they share similar features with the peralkaline A-type granites. Their geochemical data and zircon Hf isotopic compositions (εHf(t) = +3.4 to +10.5) indicate that the peralkaline granitic rocks were formed by the partial melting of dehydrated charnockite with extensive plagioclase crystal fractionation, which resulted in a peralkaline affinity. There are two types of distinct zircons in the studied samples: the type I zircon with a bright rim and dark core, which may represent a cumulate mineral phase captured together with aggregates during eruption, and the type II zircon with a higher evolution degree crystallized in the residual melts. Combined with the simulation results using whole-rock trace elements, we proposed that the peralkaline granitic dikes represent more evolved interstitial melts than the Baerzhe granitic magma. In the Early Cretaceous extensional tectonic settings, mantle-derived magma upwelled, which induced the melting of the lower crust and prolonged the evolutionary process of the magma crystal mush.
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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.
Повний текст джерелаАнотація:
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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ZENG, QING-DONG, JIN-HUI YANG, JIAN-MING LIU, SHAO-XIONG CHU, XIAO-XIA DUAN, ZUO-LUN ZHANG, WEI-QING ZHANG, and SONG ZHANG. "Genesis of the Chehugou Mo-bearing granitic complex on the northern margin of the North China Craton: geochemistry, zircon U–Pb age and Sr–Nd–Pb isotopes." Geological Magazine 149, no. 5 (November 24, 2011): 753–67. http://dx.doi.org/10.1017/s0016756811000987.
Повний текст джерелаАнотація:
AbstractThe Chehugou granite-hosted molybdenum deposit is typical of the Xilamulun metallogenic belt, which is an important Mo–Ag–Pb–Zn producer in China. A combination of major and trace element, Sr and Nd isotope, and zircon U–Pb isotopic data are reported for the Chehugou batholith to constrain its petrogenesis and Mo mineralization. The zircon SIMS U–Pb dating yields mean ages of 384.7 ± 4.0 Ma and 373.1 ± 5.9 Ma for monzogranite and syenogranite and 265.6 ± 3.5 Ma and 245.1 ± 4.4 Ma for syenogranite porphyry and granite porphyry, respectively. The Devonian granites are calc-alkaline with K2O/Na2O ratios of 0.44–0.52, the Permian granites are alkali-calcic with K2O/Na2O ratios of 1.13–1.25, and the Triassic granites are calc-alkaline and alkali-calcic rocks with K2O/Na2O ratios of 0.78–1.63. They are all enriched in large-ion lithophile elements (LILEs) and depleted in high-field-strength elements (HFSEs) with negative Nb and Ta anomalies in primitive mantle-normalized trace element diagrams. They have relatively high Sr (189–1256 ppm) and low Y (3.87–5.43 ppm) concentrations. The Devonian granites have relatively high initial Sr isotope ratios of 0.7100–0.7126, negative ɛNd(t) values of −12.3 to −12.4 and 206Pb/204Pb ratios of 16.46–17.50. In contrast, the Permian and Triassic granitoids have relatively low initial 87Sr/86Sr ratios (0.7048–0.7074), negative ɛNd(t) values of −10.1 to −13.1 and 206Pb/204Pb ratios of 17.23–17.51. These geochemical features suggest that the Devonian, Permian and Triassic Chehugou granitoids were derived from ancient, garnet-bearing crustal rocks related to subduction of the Palaeo-Asian Ocean and subsequent continent–continent collision between the North China and Siberian plates.
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Zhang, Zhihui, Bojie Hu, Da Zhang, Xiaolong He, Jianlin Zou, Xufeng Tian, and Yuanshun Yi. "Genesis and Significance of Late Cretaceous Granitic Magmatism in Xianghualing Tin–Polymetallic Orefield, Nanling Region, South China." Applied Sciences 12, no. 18 (September 7, 2022): 8984. http://dx.doi.org/10.3390/app12188984.
Повний текст джерелаАнотація:
Typical stratiform-like cassiterite–sulfide orebodies formed at 160–150 Ma cut by a steep hydrothermal vein-type orebody were discovered in the Xianghualing tin–polymetallic orefield, which implied a new phase of magmatism and mineralization later than the Late Jurassic stage. Hence, a systematic study of the characteristics and genesis of the concealed Laohuya granite, including U–Pb age, trace elements, Lu–Hf isotopes of zircons, and whole-rock major- and trace-elements, is examined in this paper. The zircon U–Pb dating yielded a Concordia age of 87.75 ± 1 Ma, confirming the existence of Late Cretaceous magmatism in the Xianghualing tin–polymetallic orefield. The Laohuya granite is classified as syenogranite and belongs to the peraluminous, high K calc-alkaline series. It is a highly evolved A2-type granite with εHf(t) values ranging from −14.97 to −7.59 and two-stage model ages (TDM2) ranging from 2939 to 2280 Ma. Combining chronology, petrochemistry, isotopic geochemistry, and previous tectonic studies, we believe that the Laohuya granite originated from the partial melting of a reworked ancient crust composed of TTGs, and its weathered sediments formed in subduction or collision zones at 2.5 Ga, controlled by the reactivation of the Chenzhou–Linwu deep fault in the extensional setting of South China during the Late Cretaceous.
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Daneshvar, Narges, Hossein Azizi, Yoshihiro Asahara, Motohiro Tsuboi, Masayo Minami, and Yousif O. Mohammad. "Geochemistry and Genesis of Beryl Crystals in the LCT Pegmatite Type, Ebrahim-Attar Mountain, Western Iran." Minerals 11, no. 7 (July 2, 2021): 717. http://dx.doi.org/10.3390/min11070717.
Повний текст джерелаАнотація:
Ebrahim-Attar granitic pegmatite, which is distributed in southwest Ghorveh, western Iran, is strongly peraluminous and contains minor beryl crystals. Pale-green to white beryl grains are crystallized in the rim and central parts of the granite body. The beryl grains are characterized by low contents of alkali oxides (Na2O = 0.24–0.41 wt.%, K2O = 0.05–0.17 wt.%, Li2O = 0.03–0.04 wt.%, and Cs2O = 0.01–0.03 wt.%) and high contents of Be2O oxide (10.0 to 11.9 wt.%). The low contents of alkali elements (oxides), low Na/Li (apfu) ratios (2.94 to 5.75), and variations in iron oxide (FeO= 0.28–1.18 wt.%) reveal a poorly evolved magmatic source of the beryl grains. Low abundances of rare earth elements (ΣREE = 0.8–4.9 ppm) with high 87Sr/86Sr(i) ratios of 0.739 ±0.036 for the beryl grains and 0.7081 for the host granites infer that the primary magma was directly produced by partial melting of the upper continental crust (UCC). The crystallization temperature of the Ebrahim-Attar granitic pegmatite changes from 586 to 755 °C (average = 629 °C), as calculated based on the zircon saturation index. Furthermore, the quartz geobarometer calculation shows that crystallization occurred at pressures of approximately 233–246 MPa. This pressure range is a promising condition for saturation of Be in magma. During granitic magma crystallization, the melt was gradually saturated with Be, and then beryl crystallized in the assemblage of the main minerals such as quartz and feldspar. Likewise, the host granite is characterized by high ratios of Nb/Ta (4.79–16.3) and Zr/Hf (12.2–19.1), and peraluminous signatures are compatible with Be-bearing LCT (Li-Ce and Ta) pegmatites.
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Appleby, S. K., C. M. Graham, M. R. Gillespie, R. W. Hinton, and G. J. H. Oliver. "New insights into granite genesis from isotopic and REE micro-analyses of zircons: The Scottish Caledonian Granites." Geochimica et Cosmochimica Acta 70, no. 18 (August 2006): A19. http://dx.doi.org/10.1016/j.gca.2006.06.051.
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OSANAI, Y., M. KOMATSU, and M. OWADA. "Metamorphism and granite genesis in the Hidaka Metamorphic Belt, Hokkaido, Japan." Journal of Metamorphic Geology 9, no. 2 (March 1991): 111–24. http://dx.doi.org/10.1111/j.1525-1314.1991.tb00508.x.
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Chiquet, Arnaud, Fabrice Colin, Bruno Hamelin, Annie Michard, and Daniel Nahon. "Chemical mass balance of calcrete genesis on the Toledo granite (Spain)." Chemical Geology 170, no. 1-4 (October 2000): 19–35. http://dx.doi.org/10.1016/s0009-2541(99)00240-5.
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Koteas, G. C., M. L. Williams, S. J. Seaman, and G. Dumond. "Granite genesis and mafic-felsic magma interaction in the lower crust." Geology 38, no. 12 (December 2010): 1067–70. http://dx.doi.org/10.1130/g31017.1.
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Isaac, Daama, Mbowou Gbambie Isaac Bertrand, Yamgouot Ngounouno Fadimatou, Ntoumbe Mama, and Ngounouno Ismaïla. "Geochemistry of Garga-Sarali intrusive granitoids (central domain of the central African fold belt in Cameroon): petrological implication." International Journal of Advanced Geosciences 8, no. 1 (June 4, 2020): 33. http://dx.doi.org/10.14419/ijag.v8i1.30559.
Повний текст джерелаАнотація:
The Garga-Sarali granitoids outcrop in form of large slabs and undistorted large blocks, into a schisto-gneissic basement. These rocks contain mainly muscovite and microcline, followed by K-feldspar, quartz, biotite, pyroxene, zircon and oxides, with coarse-grained to fine-grained textures. Geochemical analysis show that it belongs to differentiated rocks group (granodiorite-granite) with high SiO2 (up to 72 wt%) contents. Their genesis was made from a process of partial melting and fractional crystallization. These rocks are classified as belonging to I- and S-Type, meta-peraluminous, shoshonitic granites; belonging to the domain of volcanic arcs. The rare earth elements patterns suggest a source enriched of incompatible elements. The Nb-Ta and Ti negative anomalies from the multi-element patterns are characteristics of the subduction domains.
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Jiang, Yao-Hui, Zheng Liu, Ru-Ya Jia, Shi-Yong Liao, Qing Zhou, and Peng Zhao. "Miocene potassic granite–syenite association in western Tibetan Plateau: Implications for shoshonitic and high Ba–Sr granite genesis." Lithos 134-135 (March 2012): 146–62. http://dx.doi.org/10.1016/j.lithos.2011.12.012.
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O'Connor, P. J., P. S. Kennan, and M. Aftalion. "New Rb–Sr and U–Pb ages for the Carnsore Granite and their bearing on the antiquity of the Rosslare Complex, southeastern Ireland." Geological Magazine 125, no. 1 (January 1988): 25–29. http://dx.doi.org/10.1017/s0016756800009341.
Повний текст джерелаАнотація:
AbstractA 12-point whole-rock Rb–Sr isochron for the Carnsore Granite of southeastern Ireland yields an age of 428±11 Ma and initial 87Sr/86Sr ratio of 0.7068±0.0003 (index of goodness of fit, MSWD = 0.65). A similar mean 207Pb/206Pb age of 432±3 Ma from three slightly discordant zircon size fractions from the granite is also indicated, and shows that the pluton was emplaced contemporaneously with the neighbouring Saltee Granite.Thus, Tuskar Group rocks, which are intruded by the Carnsore Granite, could be as young as Ordovician. While the early history of the Rosslare Complex is undoubtedly Precambrian, the new age for the Carnsore pluton means that the later intrusive and tectonothermal events in the history of this complex are no longer constrained to be Precambrian and may have occurred over a 150 + Ma interval in Cambro-Ordovician time.The zircons from the Carnsore Granite are slightly discordant, and show no apparent inherited radiogenic lead component. The initial 87Sr/86Sr ratio suggests that the magma may have been derived as a melt in the lower crust. The higher strontium isotope ratios of the Rosslare gneisses would seem to preclude their involvement in the genesis of the Carnsore magma.