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Sample records for chhotanagpur granite gneiss

  1. Experimental Researches on Long-Term Strength of Granite Gneiss

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    Lin Liu

    2015-01-01

    Full Text Available It is important to confirm the long-term strength of rock materials for the purpose of evaluating the long-term stability of rock engineering. In this study, a series of triaxial creep tests were conducted on granite gneiss under different pore pressures. Based on the test data, we proposed two new quantitative methods, tangent method and intersection method, to confirm the long-term strength of rock. Meanwhile, the isochronous stress-strain curve method was adopted to make sure of the accuracy and operability of the two new methods. It is concluded that the new methods are suitable for the study of the long-term strength of rock. The effect of pore pressure on the long-term strength of rock in triaxial creep tests is also discussed.

  2. SHRIMP Dating and Recrystallization of Metamorphic Zircons from a Granitic Gneiss in the Sulu UHP Terrane

    Institute of Scientific and Technical Information of China (English)

    LI Hongyan

    2004-01-01

    An unusual zircon SHRIMP dating result of a granitic gneiss from the Qinglongshan eclogite-gneiss roadcut section is presented in this paper. The very peculiar and complicated internal structures, as well as the very low Th/U ratios (0.01-0.08) of the zircons indicate that they were formed by metamorphic recrystallization. Strongly in contrast with previously published zircon U-Pb ages of the Dabie-Sulu UHP metamorphic rocks where protolith ages of 600-800 Ma are commonly recorded, only metamorphic age of 218+5 Ma, defined by 18 analytical spots either in rim or in core of zircons, are recorded in this granitic gneiss. This age represents the time of the complete metamorphic recrystallization overprint on primary magmatic zircons. The recrystallization was derived by the UHP metamorphism,and was strengthened by the early stage of retrograde metamorphic fluid activity.

  3. Zircon SHRIMP U-Pb Dating, Geochemical Characteristics and Tectonic Significance of Granitic Gneisses in Amdo, Tibet

    Institute of Scientific and Technical Information of China (English)

    Lu Lu; Zhenhan Wu; Zhen Zhao; Daogong Hu; Peisheng Ye

    2014-01-01

    The Amdo microcontinent is located within the middle of Bangong-Nujiang suture (BNS) zone in the shape of lens. The basic geological research restricts geologists from understand-ing the histories of tectonic evolution of BNS and regional geology more deeply. This paper system-atically studies the geochronology and geochemistry of granitic gneisses from Amdo basement. These data provide constraints on formation age, source characteristics and tectonic setting of their protolith. The SHRIMP zircon U-Pb dating is operated for granitic gneisses. Samples AGS-2 and AGS-3 (granitic gneiss) yield average zircon U-Pb ages of 485±14 and 487±6 Ma, respectively. These ages should represent the formation age of protolith and indicate that they are formed in the Early Ordovician. Granitic gneisses are characterized by high SiO2, Na2O, K2O and Al2O3, low Fe and Mg, enrichment in light rare earth elements (LREEs) and large ion lithophile elements (LILEs), deple-tion in heavy rare earth elements (HREEs) and high field strength elements (HFSEs), with negative Eu anomaly. The Rittmann index (σ) is 1.77 to 2.60, less than 3.3. The aluminum saturation index (A/CNK) values range from 0.88 to 1.26. These features suggest that protolith of granitic gneisses from Amdo basement show characteristics of calc-alkaline and S-type granite, and they could be de-rived from partial melting of metamorphic greywackes in the upper crust of low maturity. The tec-tonic setting is syn-collision. These all suggest that the formation of protolith of granitic gneisses from Amdo are caused by the Early Paleozoic orogeny, which could be related to proto-Tethyan oceanic subduction along Gondwana continental margins, and does not result from the production of Pan-African orogenesis.

  4. Factor value determination and applicability evaluation of universal soil loss equation in granite gneiss region

    Institute of Scientific and Technical Information of China (English)

    Wen-hai ZHANG; Xing-nan ZHANG; Zhi-dong GAO

    2009-01-01

    Six types of runoff plots were set up and an experimental study was carried out to examine natural rate of soil and water loss in the granite gneiss region of northern Jiangsu Province in China. Through correlation analysis ofrunoffand soil loss during 364 rainfall events, a simplified and convenient mathematical formula suitable for calculating the rainfall erosivity factor (R) for the local region was established. Other factors of the universal soil loss equation (USLE model) were also determined. Relative error analysis of the soil loss of various plots calculated by the USLE model on the basis of the observed values showed that the relative error ranged from-3.5% to 9.9% and the confidence level was more than 90%. In addition, the relative error was 5.64% for the terraced field and 12.36% for the sloping field in the practical application. Thus, the confidence level was above 87.64%. These results provide a scientific basis for forecasting and monitoring soil and water loss, for comprehensive management of small watersheds, and for soil and water conservation planning in the region.

  5. U-Pb geochronology of zircon and monazite from Mesoproterozoic granitic gneisses of the northern Blue Ridge, Virginia and Maryland, USA

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    Aleinikoff, J.N.; Burton, W.C.; Lyttle, P.T.; Nelson, A.E.; Southworth, C.S.

    2000-01-01

    Mesoproterozoic granitic gneisses comprise most of the basement of the northern Blue Ridge geologic province in Virginia and Maryland. Lithology, structure, and U-Pb geochronology have been used to subdivide the gneisses into three groups. The oldest rocks, Group 1, are layered granitic gneiss (1153 ?? 6 Ma), hornblende monzonite gneiss (1149 ?? 19 Ma), porphyroblastic granite gneiss (1144 ?? 2 Ma), coarse-grained metagranite (about 1140 Ma), and charnockite (>1145 Ma?). These gneisses contain three Proterozoic deformational fabrics. Because of complex U-Pb systematics due to extensive overgrowths on magmatic cores, zircons from hornblende monzonite gneiss were dated using the sensitive high-resolution ion microprobe (SHRIMP), whereas all other ages are based on conventional U-Pb geochronology. Group 2 rocks are leucocratic and biotic varieties of Marshall Metagranite, dated at 1112??3 Ma and 1111 ?? 2 Ma respectively. Group 3 rocks are subdivided into two age groups: (1) garnetiferous metagranite (1077 ?? 4 Ma) and quartz-plagioclase gneiss (1077 ?? 4 Ma); (2) white leucocratic metagranite (1060 ?? 2 Ma), pink leucocratic metagranite (1059 ?? 2), biotite granite gneiss (1055 ?? 4 Ma), and megacrystic metagranite (1055 ?? 2 Ma). Groups 2 and 3 gneisses contain only the two younger Proterozoic deformational fabrics. Ages of monazite, seprated from seven samples, indicate growth during both igneous and metamorphic (thermal) events. However, ages obtained from individual grains may be mixtures of different age components, as suggested by backscatter electron (BSE) imaging of complexly zoned grains. Analyses of unzoned monazite (imaged by BSE and thought to contain only one age component) from porphyroblastic granite gneiss yield ages of 1070, 1060, and 1050 Ma. The range of ages of monazite (not reset to a uniform date) indicates that the Grenville granulite event at about 1035 Ma did not exceed about 750??C. Lack of evidence for 1110 Ma growth of monazite in

  6. Paleoproterozoic granitic gneisses of the Dinggye and LhagoiKangri areas from the higher and northern Himalaya,Tibet:Geochronology and implications

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Granitic gneisses have been widely found in crystalline rocks in the Dinggye area of the Higher Himalaya (HHM) and the LhagoiKangri area of the North Himalaya (NHM), Tibet. In the HHM, the gneisses intruded in the granulite-amphibolite facies metamorphosed sedimentary rocks, known as Nyalam group. In the NHM, the gneisses intruded in the amphibolite facies metamorphosed ones, known as LhagoiKangri group. These granitic gneisses are peraluminous monzonitic granites in terms of their mineral assemblage, and are considered as being derived from metamorphosed sedimentary rocks by anatexis based on the transitional relationship of the gneisses with their migmatitized wall rocks. Zircons are similar in crystal shape and interior structure from both gneisses. Most of them are euhedral or subhedral elongated prism-shaped transparent crystals, with fine oscillatory zoning, showing the magmatic genesis. Some of them are short prism-shaped and with relict core inherited from magma source and oscillatory zoning mantle crystallized from magma. SHRIMP U-Pb dating of zicons shows that both the granitic gneisses in the HHM and NHM are Paleoproterozoic (1811.6±2.9 Ma and 1811.7±7.2 Ma, respectively). These ages are similar to those (1815 to 2120 Ma) from granitic gneiss which is widely distributed in the Lesser Himalaya (LHM). The ages of inherited zircons (>2493.9±7.0 Ma, 2095.8± 8.8 Ma, 1874±29 Ma) exhibit the possible presence of several thermal events in Paleoproterozoic. All of the ages suggest the same India basement beneath the different units in Himalaya area, and do not support the idea that the HHM and NHM are accretionary terranes in Pan-Africa orogenic event. The fact that the basement in HHM is as old as or even younger than LHM is inconsistent with the presently prevalent orogenic models such as either extrusion of low-viscosity mid-crust or orogenic channel.

  7. Notes on epilithic and epigeic lichens from granite and gneiss outcrops in mountains of Makedonia, Greece, with emphasis on northern species

    DEFF Research Database (Denmark)

    Christensen, Steen

    2014-01-01

    The epilithic and epigeic lichen flora of eight localities with granite and gneiss outcrops in the mountains of Makedonia, N Greece has been investigated. Of the 46 taxa reported, seven species are new to Greece, viz.: Brodoa oroarcti­ca, Candelariella coralliza, Cetraria ericetorum, Lecanora...

  8. The Blaník Gneiss in the southern Bohemian Massif (Czech Republic): a rare rock composition among the early palaeozoic granites of Variscan Central Europe

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    René, Miloš; Finger, Fritz

    2016-08-01

    Metamorphosed and deformed tourmaline-bearing leucogranites with a Cambro-Ordovician formation age are widespread in the Monotonous Group of the Variscan southern Bohemian Massif, Czech Republic. The rocks, known locally as Blaník gneiss, are strongly peraluminous and classify as phosphorus-rich low-T, S-type granite. The magma formed from a metapelitic source, most likely through muscovite dehydration melting. With respect to its low-T origin and the abundance of tourmaline, the Blaník gneiss is exotic within the spectrum of Early Palaeozoic granites of the Variscan fold belt of Central Europe. Coeval granitic gneisses in the neighbouring Gföhl unit of the Bohemian Massif can be classified as higher T S-type granites and were probably generated through biotite dehydration melting. The geochemical differences between the Early Palaeozoic granitic magmatism in the Gföhl unit and the Monotonous Group support models claiming that these two geological units belonged to independent peri-Gondwana terranes before the Variscan collision. It is suggested here, that the Gföhl unit and the Monotonous Group represent zones of higher and lower heat flow within the Early Palaeozoic northern Gondwana margin, respectively. The geochemical data presented in this study could be helpful for terrane correlations and palaeogeographic reconstructions.

  9. Effective crustal permeability controls fault evolution: An integrated structural, mineralogical and isotopic study in granitic gneiss, Monte Rosa, northern Italy

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    Lawther, Susan E. M.; Dempster, Tim J.; Shipton, Zoe K.; Boyce, Adrian J.

    2016-10-01

    Two dextral faults within granitic gneiss in the Monte Rosa nappe, northern Italy reveal key differences in their evolution controlled by evolving permeability and water/rock reactions. The comparison reveals that identical host rock lithologies develop radically different mineralogies within the fault zones, resulting in fundamentally different deformation histories. Oxygen and hydrogen isotope analyses coupled to microstructural characterisation show that infiltration of meteoric water occurred into both fault zones. The smaller Virgin Fault shows evidence of periodic closed system behaviour, which promoted the growth of hydrothermal K-feldspar, whilst the more open system behaviour of the adjacent Ciao Ciao Fault generated a weaker muscovite-rich fault core, which promoted a step change in fault evolution. Effective crustal permeability is a vital control on fault evolution and, coupled to the temperature (i.e. depth) at which key mineral transformations occur, is probably a more significant factor than host rock strength in controlling fault development. The study suggests that whether a fault in granitic basement grows into a large structure may be largely controlled by the initial hydrological properties of the host rocks. Small faults exposed at the surface may therefore be evolutionary "dead-ends" that typically do not represent the early stages in the development of larger faults.

  10. Early Mesozoic deep-crust reworking beneath the central Lhasa terrane (South Tibet): Evidence from intermediate gneiss xenoliths in granites

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    Zhou, Xiang; Zheng, Jian-Ping; Xiong, Qing; Yang, Jing-Sui; Wu, Yuan-Bao; Zhao, Jun-Hong; Griffin, William L.; Dai, Hong-Kun

    2017-03-01

    Understanding the rheological behavior of the Tibetan Plateau and its response to geodynamic processes requires a clear knowledge of the composition, evolution and lithological properties of the deep crust. Here we present U-Pb-Hf isotopes of zircons, bulk-rock geochemistry and mineral compositions for seven intermediate gneiss xenoliths and their host Early Mesozoic granites (205 ± 6 Ma) in the central Lhasa terrane to probe the deep crust beneath Southern Tibet. The xenoliths contain plagioclase, amphibole, titanite, allanite, quartz, biotite and muscovite, with accessory Fe-Ti oxides, apatite and zircon. Bulk-rock and mineral geochemistry suggests that these xenoliths have a magmatic origin and experienced deformation and amphibolite-facies metamorphism (equilibration at pressures of 0.46-0.83 GPa and temperatures of 650 °C), before they were captured by the host granite at 205 Ma. Zircons in these xenoliths show complex microstructures, including inherited cores, magmatic or metamorphic bands, and high U-Th hydrothermal rims. Inherited zircon cores record U-Pb ages from 2277 Ma to 517 Ma. Igneous zircons show a range of concordant U-Pb ages, suggesting a protracted magmatism from 236 Ma to 203 Ma. Metamorphic zircon zones record the timing of amphibolite-facies metamorphism from 224 to 192 Ma, while the high U-Th hydrothermal rims show a subsequent fluid activity until 150 Ma. Unradiogenic Hf isotopic compositions of both xenoliths and host granites [xenolith εHf(t) = - 11.2 to 0; host granite εHf(t) = - 17.3 to - 3.3] indicate that the Early Mesozoic deep crust in the central Lhasa terrane originated mainly from ancient (i.e., Proterozoic) crust, with little or no interaction with juvenile magmas. This study suggests a possible continental differentiation mechanism during crustal reworking; progressive melting may initiate from the lower mafic crust (at ca. 236 Ma) and gradually migrate into the sediment-rich upper crust (until ca. 203 Ma). The reworking

  11. Mineralogy and mineral chemistry of rare-metal pegmatites at Abu Rusheid granitic gneisses, South Eastern Desert, Egypt

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    Mohamed Fahmy Raslan

    2011-12-01

    Full Text Available The Abu Rushied area, situated in the South Eastern Desert of Egypt is a distinctive occurrence of economically important rare-metal mineralization where the host rocks are represented by granitic gneisses. Correspondingly, mineralogical and geochemical investigation of pegmatites pockets scattered within Abu Rusheid granitic gneisses revealed the presence of Hf-zircon, ferrocolumbite and uranyl silicate minerals (uranophane and kasolite. Electronmicroprobe analyses revealed the presence of Nb-Ta multioxide minerals (ishikawaite, uranopyrochlore, and fergusonite, uraninite, thorite and cassiterite as numerous inclusions in the recorded Hf-zircon and ferrocolumbite minerals.Abu Rusheid pegmatites are found as small and large bodies that occur as simple and complex (zoned pegmatites.Abu Rusheid rare-metal pegmatites occur as steeply dipping bodies of variable size, ranging from 1 to 5 m in width and 10 to 50 m in length. The zoned pegmatites are composed of wall zone of coarser granitic gneisses, intermediated zone of K-feldspar and pocket of mica (muscovite and biotite, and core of quartz and pocket ofmica with lenses of rare metals.The zircon is of bipyramidal to typical octahedral form and short prisms. Because the zircon of the investigated Abu Rushied pegmatite frequently contains hafnium in amounts ranging between 2.31 and 11.11%, the studied zircon was designated as Hf-rich zircon. This zircon commonly exhibits a normal zoning with rims consistentlyhigher in Hf than cores. The bright areas in the crystal either in core or rim showed a remarkable enrichment in hafnium content (8.83–11.11% with respect to the dark zones (3.19%. The investigated ferroclumbite commonly exhibits zoning; the dark zone is low in the Ta and U but the light zone is enriched in Ta (13% and U (1%. EMPAanalyses indicate the chemical composition of ishikawaite with U ranging from 0.68 to 0.79 per formula unit.Uranopyrochlore species has dominant uranium in the A

  12. Genesis of emulsion texture due to magma mixing: a case study from Chotanagpur Granite Gneiss Complex of Eastern India

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    Gogoi, Bibhuti; Saikia, Ashima; Ahmad, Mansoor

    2016-04-01

    The emulsion texture is a rare magma mixing feature in which rounded bodies of one magmatic phase remain dispersed in the other coherent phase (Freundt and Schmincke, 1992). This type of special texture in hybrid rocks can significantly contribute toward understanding the mechanisms facilitating magma mixing and magma chamber dynamics involving two disparate magmas as the exact processes by which mixing occurs still remain unclear. Recent developments in microfluidics have greatly helped us to understand the complex processes governing magma mixing occurring at micro-level. Presented work uses some of the results obtained from microfluidic experiments with a view to understand the formation mechanism of emulsions preserved in the hybrid rocks of the Ghansura Rhyolite Dome (GRD) of Proterozoic Chotanagpur Granite Gneiss Complex (CGGC), Eastern India. The GRD has preserved hybrid rocks displaying emulsion texture that formed due to the interaction of a phenocryst-rich basaltic magma and host rhyolite magma. The emulsions are more or less spherical in shape and dominantly composed of amphibole having biotite rinds set in a matrix of biotite, plagioclase, K-feldspar and quartz. Amphibole compositions were determined from the core of the emulsions to the rim with a view to check for cationic substitutions. The amphibole constituting the emulsions is actinolite in composition, and commonly shows tschermakite (Ts) and pargasite (Prg) substitutions. From petrographical and mineral-chemical analyses we infer that when mafic magma, containing phenocrysts of augite, came in contact with felsic magma, diffusion of cations like H+, Al3+and others occurred from the felsic to the mafic system. These cations reacted with the clinopyroxene phenocrysts in the mafic magma to form amphibole (actinolite) crystals. The formation of amphibole crystals in the mafic system greatly increased the viscosity of the system allowing the amphibole crystals to venture into the adjacent felsic

  13. Are cumulate granites characteristic of migmatitic gneiss domes? An example from the Fosdick Mountains of Marie Byrd Land, West Antarctica

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    Brown, Caitlin R.; Yakymchuk, Chris; Brown, Michael; Fanning, C. Mark; Korhonen, Fawna J.; Piccoli, Philip M.; Siddoway, Christine S.

    2014-05-01

    In the Fosdick migmatite-granite complex, Cretaceous granites yield U-Pb zircon crystallization ages of 117-102 Ma, corresponding to the timing of doming during a regional transition from transpression to transtension that facilitated exhumation of the complex. The results of P-T phase equilibria modeling and occurrence of leucosome-bearing normal-sense shear zones are consistent with suprasolidus conditions during the early stages of exhumation. Commonly, leucosomes in normal-sense shear zones and sub-horizontal sheeted granites within the complex have coarse blocky plagioclase or K-feldspar grains with interstitial quartz, suggesting a cumulate origin. The Cretaceous granites have whole rock Sr and Nd and zircon Hf and O isotope compositions consistent with derivation from regionally-associated source materials comprising a Devonian-Carboniferous calc-alkaline granodiorite suite (dominant component) and a Cambrian metaturbidite sequence (minor component). However, the major and trace element chemistry of these granites is highly variable and inconsistent with melt compositions expected from simple anatexis of such source materials. Furthermore, major element compositions are inconsistent with those of cotectic granites and more variable than those reported from melt inclusions. The granites typically have large positive Eu anomalies and the overall geochemistry is consistent with the early accumulation of feldspar and quartz, and drainage of fractionated melt. These granites are interpreted to record the collapse of sub-horizontal partially-crystallized layers of magma by filter pressing during vertical shortening associated with dome exhumation, leaving behind cumulate-rich residues. Consequently, the extracted melt is expected to be more evolved and variable than compositions of experimental melts and melt inclusions in peritectic minerals. A potential sink for melt complementary to the cumulate granites is represented by the Cretaceous Byrd Coast Granite suite

  14. Geochemical constraints on the evolution of mafic and felsic rocks in the Bathani volcanic and volcano-sedimentary sequence of Chotanagpur Granite Gneiss Complex

    Indian Academy of Sciences (India)

    Ashima Saikia; Bibhuti Gogoi; Mansoor Ahmad; Talat Ahmad

    2014-07-01

    The Bathani volcanic and volcano-sedimentary (BVS) sequence is a volcanic and volcano-sedimentary sequence, best exposed near Bathani village in Gaya district of Bihar. It is located in the northern fringe of the Chotanagpur Granite Gneiss Complex (CGGC). The volcano-sedimentary unit comprises of garnet-mica schist, rhyolite, tuff, banded iron formation (BIF) and chert bands with carbonate rocks as enclaves within the rhyolite and the differentiated volcanic sequence comprises of rhyolite, andesite, pillow basalt, massive basalt, tuff and mafic pyroclasts. Emplacement of diverse felsic and mafic rocks together testifies for a multi-stage and multi-source magmatism for the area. The presence of pillow basalt marks the eruption of these rocks in a subaqueous environment. Intermittent eruption of mafic and felsic magmas resulted in the formation of rhyolite, mafic pyroclasts, and tuff. Mixing and mingling of the felsic and mafic magmas resulted in the hybrid rock andesite. Granites are emplaced later, crosscutting the volcanic sequence and are probably products of fractional crystallization of basaltic magma. The present work characterizes the geochemical characteristics of the magmatic rocks comprising of basalt, andesite, rhyolite, tuff, and granite of the area. Tholeiitic trend for basalt and calc-alkaline affinities of andesite, rhyolite and granite is consistent with their generation in an island arc, subduction related setting. The rocks of the BVS sequence probably mark the collision of the northern and southern Indian blocks during Proterozoic period. The explosive submarine volcanism may be related to culmination of the collision of the aforementioned blocks during the Neoproterozoic (1.0 Ga) as the Grenvillian metamorphism is well established in various parts of CGGC.

  15. Geochemical constraints on the evolution of mafic and felsic rocks in the Bathani volcanic and volcano-sedimentary sequence of Chotanagpur Granite Gneiss Complex

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    Saikia, Ashima; Gogoi, Bibhuti; Ahmad, Mansoor; Ahmad, Talat

    2014-06-01

    The Bathani volcanic and volcano-sedimentary (BVS) sequence is a volcanic and volcano-sedimentary sequence, best exposed near Bathani village in Gaya district of Bihar. It is located in the northern fringe of the Chotanagpur Granite Gneiss Complex (CGGC). The volcano-sedimentary unit comprises of garnet-mica schist, rhyolite, tuff, banded iron formation (BIF) and chert bands with carbonate rocks as enclaves within the rhyolite and the differentiated volcanic sequence comprises of rhyolite, andesite, pillow basalt, massive basalt, tuff and mafic pyroclasts. Emplacement of diverse felsic and mafic rocks together testifies for a multi-stage and multi-source magmatism for the area. The presence of pillow basalt marks the eruption of these rocks in a subaqueous environment. Intermittent eruption of mafic and felsic magmas resulted in the formation of rhyolite, mafic pyroclasts, and tuff. Mixing and mingling of the felsic and mafic magmas resulted in the hybrid rock andesite. Granites are emplaced later, cross-cutting the volcanic sequence and are probably products of fractional crystallization of basaltic magma. The present work characterizes the geochemical characteristics of the magmatic rocks comprising of basalt, andesite, rhyolite, tuff, and granite of the area. Tholeiitic trend for basalt and calc-alkaline affinities of andesite, rhyolite and granite is consistent with their generation in an island arc, subduction related setting. The rocks of the BVS sequence probably mark the collision of the northern and southern Indian blocks during Proterozoic period. The explosive submarine volcanism may be related to culmination of the collision of the aforementioned blocks during the Neoproterozoic (1.0 Ga) as the Grenvillian metamorphism is well established in various parts of CGGC.

  16. Nd-Sr Isotopic Geochemistry and U-Pb Geochronology of the Fé Granitic Gneiss and Lajedo Granodiorite: Implications for Paleoproterozoic Evolution of the Mineiro Belt, Southern São Francisco Craton, Brazil

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    Wilson Teixeira

    2008-04-01

    Full Text Available The Fé granitic gneiss and Lajedo granodiorite belong to a voluminous felsic-mafic plutonism, tectonically linked toPaleoproterozoic magmatic evolution of the Mineiro Belt, southern portion of the São Francisco Craton, central-easternBrazil. The Fé pluton is located north of the Lenheiros shear zone and is intrusive with respect to the Rio das Mortesgreenstone belt and pyroxenite - gabbroic bodies, as indicated by xenoliths of gneiss and amphibolite, in the first case, andpyroxenite in the latter. The Lajedo granodiorite is located south of the Lenheiros shear zone and cuts the metamafic rocks ofthe Forro peridotite – pyroxenite and mafic and intermediate rocks of the Nazareno greenstone belt, as evidenced by xenolithsfrom the latter unit. The modal composition of the Fé granitic gneiss lies within the ranges of monzogranite and syenogranite.It is peraluminous and shows a large variation in K2O content, which implies a middle-K calc-alkaline to high-K calc-alkalinetendency. The Lajedo modal composition is consistent with granodioritic and tonalitic compositions. It indicates a predominantlyperaluminous composition and calc-alkaline character. The U-Pb zircon crystallization age of the Fé granitic gneiss is 2191± 9 Ma, whereas the Lajedo granodiorite yields 2208 ± 26 Ma. The Nd/Sr characteristics of the Fé and Lajedo plutons areconsistent with mixtures of enriched mantle (EMI-type, DMM and crustal components during magma genesis in a plutonicarc setting, while the low 87Sr/86Sri ratios point to contribution of mafic rock protoliths during magma genesis. This is also inaccordance with the characteristic xenoliths observed within the investigated plutons from the Nazareno and Rio das Mortesgreenstone belts. The Fé granitic gneiss and Lajedo granodiorite show tectonic characteristics which are comparable to thoseof nearby coeval plutons: Brito quartz-diorite (2221 ± 2 Ma, Brumado de Cima granodiorite (2219 ± 2 Ma, Brumado de

  17. Nd-Sr isotopic geochemistry and U-Pb geochronology of the Fe granitic gneiss and Lajedo Granodiorite: implications for paleoproterozoic evolution of the Mineiro Belt, southern Sao Francisco craton, Brazil

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    Teixeira, Wilson [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Centro de Pesquisas Geocronologicas]. E-mail: wteixeir@usp.br; Avila, Ciro Alexandre [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Museu Nacional. Dept. de Geologia e Paleontologia]. E-mail: avila@mn.ufrj.br; Nunes, Luciana Cabral [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias]. E-mail: luciana@igc.usp.br

    2008-07-01

    The Fe granitic gneiss and Lajedo granodiorite belong to a voluminous felsic-mafic plutonism, tectonically linked to Paleoproterozoic magmatic evolution of the Mineiro Belt, southern portion of the Sao Francisco Craton, central-eastern Brazil. The Fe pluton is located north of the Lenheiros shear zone and is intrusive with respect to the Rio das Mortes greenstone belt and pyroxenite - gabbroic bodies, as indicated by xenoliths of gneiss and amphibolite, in the first case, and pyroxenite in the latter. The Lajedo granodiorite is located south of the Lenheiros shear zone and cuts the metamafic rocks of the Forro peridotite - pyroxenite and mafic and intermediate rocks of the Nazareno greenstone belt, as evidenced by xenoliths from the latter unit. The modal composition of the Fe granitic gneiss lies within the ranges of monzogranite and syenogranite. It is peraluminous and shows a large variation in K{sub 2}O content, which implies a middle-K calc-alkaline to high-K calc-alkaline tendency. The Lajedo modal composition is consistent with granodioritic and tonalitic compositions. It indicates a predominantly peraluminous composition and calc-alkaline character. The U-Pb zircon crystallization age of the Fe granitic gneiss is 2191 {+-} 9 Ma, whereas the Lajedo granodiorite yields 2208 {+-} 26 Ma. The Nd/Sr characteristics of the Fe and Lajedo plutons are consistent with mixtures of enriched mantle (EMI-type), DMM and crustal components during magma genesis in a plutonic arc setting, while the low {sup 87}Sr/{sup 86}Sri ratios point to contribution of mafic rock protoliths during magma genesis. This is also in accordance with the characteristic xenoliths observed within the investigated plutons from the Nazareno and Rio das Mortes greenstone belts. The Fe granitic gneiss and Lajedo granodiorite show tectonic characteristics which are comparable to those of nearby coeval plutons: Brito quartz-diorite (2221 +- 2 Ma), Brumado de Cima granodiorite (2219 {+-} 2 Ma), Brumado

  18. The geology and petrogenesis of the southern closepet granite

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    Jayananda, M.; Mahabaleswar, B.; Oak, K. A.; Friend, C. R. L.

    1988-01-01

    The Archaean Closepet Granite is a polyphase body intruding the Peninsular Gneiss Complex and the associated supracrustal rocks. The granite out-crop runs for nearly 500 km with an approximate width of 20 to 25 km and cut across the regional metamorphic structure passing from granulite facies in the South and green schist facies in the north. In the amphibolite-granulite facies transition zone the granite is intimately mixed with migmatites and charnockite. Field observations suggests that anatexis of Peninsular gneisses led to the formation of granite melt, and there is a space relationship between migmatite formation, charnockite development and production and emplacement of granite magma. Based on texture and cross cutting relationships four major granite phases are recognized: (1) Pyroxene bearing dark grey granite; (2) Porphyritec granite; (3) Equigranular grey granite; and (4) Equigranular pink granite. The granite is medium to coarse grained and exhibit hypidiomorphic granular to porphyritic texture. The modal composition varies from granite granodiorite to quartz monzonite. Geochemical variation of the granite suite is consistent with either fractional crystallization or partial melting, but in both the cases biotite plus feldspar must be involved as fractionating or residual phases during melting to account trace element chemistry. The trace element data has been plotted on discriminant diagrams, where majority of samples plot in volcanic arc and within plate, tectonic environments. The granite show distinct REE patterns with variable total REE content. The REE patterns and overall abundances suggests that the granite suite represents a product of partial melting of crustal source in which fractional crystallization operated in a limited number of cases.

  19. Thermobarometric studies on the Levack Gneisses: Footwall rocks to the Sudbury Igneous Complex

    Science.gov (United States)

    James, R. S.; Peredery, W.; Sweeny, J. M.

    1992-01-01

    Granulite and amphibolite facies gneisses and migmatites of the Levack Gneiss Complex occupy a zone up to 8 km wide around the northern part of the Sudbury Igneous Complex (SIC). Orthopyroxene- and garnet-bearing tonalitic and semipelitic assemblages of granulite facies grade occur within 3 km of the SIC together with lenses of mafic and pyroxenitic rock compositions normally represented by an amphibole +/- cpx-rich assemblage; amphibolite facies assemblages dominate elsewhere in this terrain. These 2.711-Ga gneisses were introduced by (1) the Cartier Granite Batholith during late Archaean to early Proterozoic time and (2) the SIC, at 1.85 Ga, which produced a contact aureole 1-1.5 km wide in which pyroxene hornfelses are common within 200-300 m of the contact. A suite of 12 samples including both the opx-gt and amphibole-rich rock compositions have been studied. Garnets in the semipelitic gneisses are variably replaced by a plg-bio assemblage. Thermobarometric calculations using a variety of barometers and thermometers reported in the literature suggest that the granulite facies assemblages formed at depths in the 21-28 km range (6-8 kbar). Textures and mineral chemistry in the garnet-bearing semipelitic rocks indicate that this terrain underwent a second metamorphic event during uplift to depth in the 5-11 km range (2-3 kbar) and at temperatures as low as 500-550 C. This latter event is distinct from thermal recrystallization caused by the emplacement of the SIC; it probably represents metamorphism attributable to intrusion of the Cartier Granite Batholith. These data allow two interpretations for the crustal uplift of the Levack Gneisses: (1) The gneisses were tectonically uplifted prior to the Sudbury Event (due to intrusion of the Cartier Batholith); or (2) the gneisses were raised to epizonal levels as a result of meteorite impact at 1.85 Ga.

  20. Association of Neoproterozoic A- and I-type Granites in South China: Implications for Generation of A-type Granites in A Subduction-related Environment

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xin-fu; ZHOU Mei-fu; LI Jian-wei; WU Fu-yuan

    2008-01-01

    @@ Neoproterozoic magmatism in the Yangtze Block of South China produced voluminous S- and I-type granites, and sparse A-type granites. The Daxiangling A-type granitic pluton is spatially associated with the Shimian I-type pluton at the western margin of the Yangtze Block. Both plutons have similar SHRIMP zircon U-Pb ages of~800 Ma and are slightly younger than the tonalite-trondhjemite-granodiorite (TTG) gneisses in the area.

  1. Speleothem and biofilm formation in a granite/dolerite cave, Northern Sweden

    DEFF Research Database (Denmark)

    Sallstedt, T.; Ivarsson, M.; Lundberg, J.

    2014-01-01

    Tjuv-Antes grotta (Tjuv-Ante's Cave) located in northern Sweden is a round-abraded sea cave ('tunnel cave'), about 30 m in length, formed by rock-water abrasion in a dolerite dyke in granite gneiss. Abundant speleothems are restricted to the inner, mafic parts of the cave and absent on granite...

  2. Multi-stage evolution of gneiss from North Dabie:evidence from zircon U-Pb chronology

    Institute of Scientific and Technical Information of China (English)

    XIE Zhi; GAO Tianshan; CHEN Jiangfeng

    2004-01-01

    TTG gneiss is a common rock to outcrop in the northern part of the Dabie orogen, a few of which are closely associated with eclogites that experienced the Triassic ultrahigh pressure metamorphism. Although they were thermally metamorphosed by a large-scale magma activity in this region at the Early Cretaceous, it is unclear whether or not they are also affected by the Triassic metamorphism during continental subduction and exhumation. In order to resolve this issue, SHRIMP zircon U-Pb dating was carried out for the host gneiss of eclogites in North Dabie. The results show that cores from the gneiss have an age of 746±31 Ma, consistent with the protolith ages of granitic gneisses in the Dabie orogen. Zircon overgrowing with different U and Th concentrations give concordant ages of 212±21 and 120±11 Ma, respectively. Th/U ratios of overgrown zircons are both lower than 0.1, suggesting a metamorphic genesis. The present results suggest that the gneiss in North Dabie has the similar protolith ages of Neoproterozoic to those granitic gneisses elsewhere in the Dabie orogen, and experienced not only the Triassic metamorphism but also the thermal metamorphism due to the Early Cretaceous magmatism. This provides an important insight into the geodynamic evolution of gneissic rocks in the Dabie orogen.

  3. Spatial greenstone-gneiss relationships: Evidence from mafic-ultramafic xenolith distribution patterns

    Science.gov (United States)

    Glikson, A. Y.

    1986-01-01

    The distribution patterns of mafic-ultramafic xenoliths within Archaean orthogneiss terrain furnish an essential key for the elucidation of granite-greenstone relations. Most greenstone belts constitute mega-xenoliths rather than primary basin structures. Transition along strike and across strike between stratigraphically low greenstone sequences and xenolith chains demonstrate their contemporaneity. These terrains represent least deformed cratonic islands within an otherwise penetratively foliated deformed gneiss-greenstone crust. Whereas early greenstone sequences are invariably intruded by tonalitic/trondhjemitic/granodioritic gneisses, stratigraphically higher successions may locally overlap older gneiss terrains and their entrained xenoliths unconformably. The contiguity of xenolith patterns suggests their derivation as relics of regional mafic-ultramafic volcanic crustal units and places limits on horizontal movements between individual crustal blocks.

  4. The Wuluma granite, Arunta Block, central Australia: An example of in situ, near-isochemical granite formation in a granulite-facies terrane

    Science.gov (United States)

    Collins, W. J.; Flood, R. H.; Vernon, R. H.; Shaw, S. E.

    1989-06-01

    The Wuluma granite is a small, elongate, relatively undeformed pluton in the Proterozoic Strangways Metamorphic Complex, central Australia. The complex constitutes a supracrustal assemblage that underwent granulite-facies metamorphism 1800 Ma ago. Metamorphism was associated with at least three phases of folding that ultimately produced upright, regional, doubly plunging F 3 folds and isobaric cooling ensued. Generation of the Wuluma granite occurred at ˜ 1750 Ma, based on RbSr isotopic data, during syn-D 3 regional retrogression and rehydration of the terrane. Contacts between the granite and gneisses are invariably gradational. At the pluton margin, banded gneisses grade along strike into granite containing abundant biotite schlieren that parallel regional structures. Granite and pegmatite dykes cut these rocks. Inwards from the contact, the granite is more homogeneous, containing diffuse parallel schlieren and small aligned rectangular feldspar crystals, indicating flow of magma. Rafts of unmelted granofels form a ghost layering; they mimic macroscopic F 3 folds and show only minor retrogressive metamorphic effects. At the pluton core, the granite is homogeneous and structurally isotropic, containing some subrounded granofelsic inclusions, very diffuse schlieren and disaggregated pegmatite dykes. Thus, it appears that an isoclinally folded, vertical body of quartzofeldspathic gneiss was melted "in situ" to form the pluton, which did not break away from the source. The body resembles a tapered diapir and we term this type of pluton a regional migmatite terrane granite. Geochemical data are consistent with the granite forming by anatexis of quartzofeldspathic migmatitic gneisses with appropriate composition. The chemical similarity of both rock types implies derivation of the granite by either partial melting and retention of residual material in the magma or more complete melting, followed by solidification virtually in situ. The latter interpretation is

  5. Characteristics of pegmatoidal granite exposed near Bayalan, Ajmer district, Rajasthan

    Indian Academy of Sciences (India)

    Nilanjan Dasgupta; Taritwan Pal; Joydeep Sen; Tamoghno Ghosh

    2011-08-01

    The study involves the characterization of pegmatoidal granite, southeast of Beawar, Ajmer district, Rajasthan. Earlier researchers had described this granite as part of the BGC, basement to the Bhim Group of the Delhi Super Group rocks. However, the present study indicates that it is younger than the rocks of Bhim Group of South Delhi Fold Belt, into which it is intrusive. The intrusion is structurally controlled and the outcrop pattern is phacolithic. The granite had intruded post-D2 deformation of the Delhi orogeny along the axial planes of D2 folds. The intrusion has also resulted in the formation of a contact aureole about the calc gneisses.

  6. Geochemistry and geochronology of the Rathjen Gneiss: implications for the early tectonic evolution of the Delamerian Orogen

    Energy Technology Data Exchange (ETDEWEB)

    Foden, J.; Sandiford, M.; Dougherty-Page, J. [University of Adelaide, SA (Australia). Department of Geology; Williams, I. [Australian National University, ACT (Australia). Research School of Earth Sciences

    1999-06-01

    The Rathjen Gneiss is the oldest and structurally most complex of the granitic intrusives in the southern Adelaide Fold-Thrust Belt and therefore provides an important constraint on the timing of the Delamerian Orogen. Zircons in the Rathjen Gneiss show a complex growth history, reflecting inheritance, magmatic crystallisation and metamorphism. Both single zircon evaporation (`Kober` technique) and SHRIMP analysis yield best estimates of igneous crystallisation of 514 {+-} 5 Ma, substantially older than other known felsic intrusive ages in the southern Adelaide Fold-Thrust Belt. This age places an older limit on the start of the Delamerian metamorphism and is compatible with known stratigraphic constraints suggesting the Early Cambrian Kanmantoo Group was deposited, buried and heated in less than 20 million years. High-U overgrowths on zircons were formed during subsequent metamorphism and yield a {sup 206}Pb/{sup 238}U age of 503 {+-} 7 Ma. The Delamerian Orogeny lasted no more than 35 million years. The emplacement of the Rathjen Gneiss as a pre- or early syntectonic granite is emphasised by its geochemical characteristics, which show affiliations with within-plate or anorogenic granites. In contrast, younger syntectonic granites in the southern Adelaide Fold-Thrust Belt have geochemical characteristics more typical of granites in convergent orogens. The Early Ordovician post-tectonic granites then mark a return to anorogenic compositions. The sensitivity of granite chemistry to changes in tectonic processes is remarkable and clearly reflects changes in the contribution of crust and mantle sources. Copyright (1999) Blackwell Science Pty Ltd 35 refs., 3 tabs., 11 figs.

  7. 2005 dossier: granite; Dossier 2005: granite

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the geologic disposal of high-level and long-lived radioactive wastes in granite formations. Content: 1 - advantage of granitic formations for the geologic disposal; 2 - containers; 3 - design study of a disposal facility in granitic environment; 4 - understanding and modelling of granite; 5 - description of disposal concepts in granitic environment; 6 - long-term and safety aspects; 7 - conclusion. (J.S.)

  8. Geochemical characteristics of Mesoproterozoic metabasite dykes from the Chhotanagpur Gneissic Terrain, eastern India: Implications for their emplacement in a plate margin tectonic environment

    Indian Academy of Sciences (India)

    Rajesh K Srivastava; Anup K Sinha; Suresh Kumar

    2012-04-01

    A number of mafic intrusive bodies (mostly dykes) are exposed in the Chhotanagpur Gneissic Terrain (CGT). Most dykes trend in ENE–WSW to E–W following major structural trends of the region. These metabasite dykes show granoblastic to grano-nematoblastic textures and contain hornblende, plagioclase, chlorite, quartz and epidote which suggest their metamorphism under amphibolite grade P–T conditions. Although no radiometric age is available for the metabasite dykes, field relationships with host rock and available geochronology on granitoids suggest their emplacement during Mesoproterozoic. Geochemical characteristics of these dykes classify them as low-K tholeiite to medium-K calcalkaline type. At least two types of metabasite dykes are recognized on the basis of their HFSE contents; one group shows entirely calc-alkaline nature, whereas the other group has rocks of tholeiite-calc-alkaline series. High Mg#observed in a number of samples indicates their derivation from primary melt. Multielement spidergrams and rare-earth element patterns observed in these samples also corroborate their derivation from different magma batches. Trace element patterns observed for Nb–Ta, Hf–Zr, Sr and Y suggesting involvement of subduction related processes in the genesis of CGT metabasite dykes. Perceived geochemical characteristics suggest that metamorphism did not affect much on the chemistry of metabasites but source region, responsible for the generation of CGT metabasites, was possibly modified during subduction process. This study suggests that magma generated in a destructive plate setting fed the Mesoproterozoic mafic dykes of the CGT.

  9. Oxygen isotopes of some trondhjemites, siliceous gneisses, and associated mafic rocks

    Science.gov (United States)

    Barker, F.; Friedman, I.; Hunter, D.R.; Gleason, J.D.

    1976-01-01

    Analyses of oxygen isotopes in whole-rock samples of 58 Precambrian and Phanerozoic trondhjemites and siliceous gneisses and of 28 cogenetic mafic to intermediate rocks from North America, Fennoscandia, and southern Africa give the following results: 1. (1) 47 trondhjemites, tonalites, and mostly Archean acidic gneisses that apparently are not isotopically disturbed show an overage ?? 15O of +7.3??? and a range of 5.2-8.9???; 11 other samples are slightly to moderately disturbed and show higher values; and 2. (2) the mafic rocks show a wide range of ??-values, from about 0-9??? but the undisturbed ones give an average ?? 18O of 5.2???. The ?? 18O values of the trondhjemitic intrusives and siliceous gneisses of similar composition are lower than those of most granitic rocks and support models for derivation of these rocks from basaltic parents. This approach, however, cannot be used to determine if individual bodies formed by differentiation or by partial melting. ?? 1976.

  10. Garnet-sillimanite bearing gneisses from Darjeeling, eastern Himalaya: Textural relationship and P–T conditions

    Indian Academy of Sciences (India)

    Divya Prakash; Suparna Tewari

    2015-08-01

    The area around Darjeeling consists of medium grade metamorphic rocks and provides a classic example of inverted Himalayan metamorphism. The area under investigation shows upper amphibolite facies metamorphism (sillimanite-muscovite subfacies), rocks are intimately associated with the migmatites and granites. The presence of quartzite, calc-silicate rocks, graphitic schist and abundance of aluminous minerals like kyanite or sillimanite in these rocks indicate their metasedimentary character. Granetsillimanite bearing gneisses occupy most of the area of Darjeeling but not persistent throughout. Textural relationship suggests sequential growth of progressively higher-grade metamorphic minerals during D1 and D2 deformation. The relative XMg in the minerals varies in the order: biotite>staurolite>garnet, and the XMn decreases in the order: garnet>staurolite>biotite. The P–T evolution of these garnetsillimanite gneiss has been constrained through the use of conventional geothermobarometry, internally consistent TWEEQU programme and Perple_X software in the KFMASH model system, the combination of these three approaches demonstrates that the Darjeeling gneisses experienced peak pressure and temperature at 7.0 ± 0.3 kbar and 700 ± 30°C. The observation in this study has important bearing on the inverted metamorphism in the Himalayan metamorphic belt.

  11. Retrograde, charnockite- gneiss relations in Southern India

    Science.gov (United States)

    Srikantappa, C.; Ashamanjari, K. G.; Narasimha, K. N. Prakash; Raith, M.

    1988-01-01

    The high-pressure charnockites (P = 8 to 9 Kb., T = 700 to 800 C CO2-rich fluid regime) of the Nilgiri hills show evidence of retrogression related to shear deformation within the Moyar and Bhavani shear belts. Two types of retrogression have been noticed: (1) retrogression along shear planes, and (2) retrogression along pegmatitic veins. Initial stages of retrogression results in the formation of irregular, 2 to 3 cm to one meter wide bleached zones with the removal of greasy grey color of charnockites. Minor structures which were earlier obscured in charnockites are clearly seen in bleached areas. In intensely shear areas, formation of highly fissile grey gneiss results often with the development of flaser and mylonitic structures. Fluid inclusion studies and geochemical investigations carried out for serial samples collected from charnockite to gneiss indicate following features: (1) there is a gradual decrease in density of CO2-rich fluids from 1.073 to 0.821 g/cu cm; (2) interestingly, in many sections of the gneisses studied, there is almost complete absence of fluid inclusions suggesting that they would have decrepitated (this may be due to large pressure difference (2 to 3 Kb.) created between the interior and exterior of the fluid inclusions); and (3) presence of mixed CO2-H2O inclusions were noticed.

  12. EXPLOITATION OF GRANITE BOULDER

    Directory of Open Access Journals (Sweden)

    Ivan Cotman

    1994-12-01

    Full Text Available The processes of forming, petrography, features, properties and exploitation of granite boulders are described. The directional drilling and black powder blasting is the succesful method in exploitation of granite boulders (boulder technology (the paper is published in Croatian.

  13. Geology and U-Pb geochronology of the Banabuiú granite, Northeastern Ceará, Brazil

    OpenAIRE

    Lima, M. N.; Nogueira Neto, J. A.; Azevedo, M. R.; Valle Aguado, B.

    2010-01-01

    The Banabuiú massif crops out in the Central Ceará Domain (DCC) of the Borborema Province (NE Brasil), as an N-S elongate granite intrusion, concordant with the regional structures. It was emplaced into basement rocks of Paleoproterozoic age, extensively transformed into gneisses and migmatites during the Brasilian orogeny (~600 Ma). Using U-Pb zircon dating, the crystallization age of the Banabuiú syn-kinematic two-mica granite was estimated at 578.6 ± 6.5 Ma. The granite is strongly peralum...

  14. U-Pb dating of zircon from the bed parallel anatectic granitic intrusion in the Baoban group in Hainan Island and the tectonic implication

    Institute of Scientific and Technical Information of China (English)

    DING; Shijiang; HU; Jianmin; SONG; Biao; CHEN; Mulun; XIE

    2005-01-01

    The petrological and geochemical features of the bed parallel granitic intrusion in the Pre-Cambrian Baoban group in Hainan Island attest to the anatexis origin of the granites. U-Pb dating analyses of zircons from the anatectic granite and the biotite two-feldspar gneiss in the Baoban group, using SHRIMP II in the Beijing Ion-probe Center, acquire 206Pb/238U ages of 368±3.5 Ma (of granite, 95% confidence level, MSDW=1.23) and 362.9±6.1 Ma (of gneiss, 95% confidence level, MSDW = 2.04) respectively. The two late Devonian ages indicate consistently a tectonic- thermal event experienced in Hainan Island, and are the first discovered record of the Devonian geological process in the district. This event possibly resulted from the deep thermal-dynamic process when the Gondwana continent began to break up in the Devonian period.

  15. Evolution of high-pressure mafic granulites and pelitic gneisses from NE Madagascar: Tectonic implications

    Science.gov (United States)

    Ishwar-Kumar, C.; Sajeev, K.; Windley, B. F.; Kusky, T. M.; Feng, P.; Ratheesh-Kumar, R. T.; Huang, Y.; Zhang, Y.; Jiang, X.; Razakamanana, T.; Yagi, K.; Itaya, T.

    2015-11-01

    The occurrence of high-pressure mafic-ultramafic bodies within major shear zones is one of the indicators of paleo-subduction. In mafic granulites of the Andriamena complex (north-eastern Madagascar) we document unusual textures including garnet-clinopyroxene-quartz coronas that formed after the breakdown of orthopyroxene-plagioclase-ilmenite. Textural evidence and isochemical phase diagram calculations in the Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O-TiO2 system indicate a pressure-temperature (P-T) evolution from an isothermal (780 °C) pressure up to c. 24 kbar to decompression and cooling. Such a P-T trajectory is typically attained in a subduction zone setting where a gabbroic/ultramafic complex is subducted and later exhumed to the present crustal level during oceanic closure and final continental collision. The present results suggest that the presence of such deeply subducted rocks of the Andriamena complex is related to formation of the Betsimisaraka suture. LA-ICPMS U-Pb zircon dating of pelitic gneisses from the Betsimisaraka suture yields low Th/U ratios and protolith ages ranging from 2535 to 2625 Ma. A granitic gneiss from the Alaotra complex yields a zircon crystallization age of ca. 818 Ma and Th/U ratios vary from 1.08 to 2.09. K-Ar dating of muscovite and biotite from biotite-kyanite-sillimanite gneiss and garnet-biotite gneiss yields age of 486 ± 9 Ma and 459 ± 9 Ma respectively. We have estimated regional crustal thicknesses in NE Madagascar using a flexural inversion technique, which indicates the presence of an anomalously thick crust (c. 43 km) beneath the Antananarivo block. This result is consistent with the present concept that subduction beneath the Antananarivo block resulted in a more competent and thicker crust. The textural data, thermodynamic model, and geophysical evidence together provide a new insight to the subduction history, crustal thickening and evolution of the high-pressure Andriamena complex and its link to the terminal

  16. First field identification of the Cuonadong dome in southern Tibet: implications for EW extension of the North Himalayan gneiss dome

    Science.gov (United States)

    Fu, Jiangang; Li, Guangming; Wang, Genhou; Huang, Yong; Zhang, Linkui; Dong, Suiliang; Liang, Wei

    2016-07-01

    The Cuonadong dome exposes in east-southern margin of the North Himalayan gneiss domes (NHGD), which is reported first time in this study. The Cuonadong dome is located at the southern part of the Zhaxikang ore concentration area, which is divided into three tectono-lithostratigraphic units by two curved faults around the dome geometry from upper to lower (or from outer to inner): the upper unit, middle unit and lower unit, and the outer fault is Nading fault, while the inner fault is Jisong fault. The Cuonadong dome is a magmatic orthogneiss and leucogranite mantled by orthogneiss and metasedimentary rocks, which in turn are overlain by Jurassic metasedimentary and sedimentary rocks. The grades of metamorphism and structural deformation increase towards the core, which is correspondence with the Ridang Formation low-metamorphic schist, tourmaline granitic-biotite gneiss, garnet-mica gneiss and mylonitic quartz-mica gneiss. The Cuonadong dome preserves evidences for four major deformational events: firstly top-to-S thrust (D1), early approximately N-S extensional deformation (D2), main approximately E-W extensional deformation (D3), and late collapse structural deformation (D4) around the core of the Cuonadong dome, which are consistent to three groups lineation: approximately N-S-trending lineation including L1 and L2, E-W trending L3, and L4 with plunging towards outside of the dome, respectively. The formation of the Cuonadong dome was probably resulted from the main E-W extensional deformation which is a result of eastward flow of middle or lower crust from beneath Tibet accommodated by northward oblique underthrusting of Indian crust beneath Tibet. The establishment of the Cuonadong dome enhanced the E-W extension of the NHGD, which is further divided into two structural dome zones according to the different extensional directions: approximately N-S extensional North Himalayan gneiss domes (NS-NHGD) and E-W extensional North Himalayan gneiss domes (EW

  17. Magnetofabrics of ultrahigh-pressure gneisses from the Chinese Continental Scientific Drilling (CCSD) project: Retrogression of ferromagnetic gneisses

    Science.gov (United States)

    Grimmer, J.-C.; Qi, X. X.; Xu, Z. Q.

    2009-04-01

    In order to better understand retrograde processes during exhumation of ultrahigh pressure (UHP) rocks the anisotropy of magnetic susceptibility (AMS) was measured on UHP-gneisses from the 5138 m deep CCSD-mainhole. The Sulu UHP-gneisses are composed of variable proportions of quartz, K-feldspar, plagioclase, biotite, and white mica with variable contents of garnet, chlorite, epidote, amphibole, and accessory phases such as zircon, apatite, and Fe-Ti-oxides. 111 samples from 21 oriented core pieces from the uppermost 1800 m of the CCSD-mainhole were measured for their AMS. The mean susceptibilities (Kmean) of the gneisses vary from 0.1x10-3 to 37.2x10-3 SI. Some core pieces outline a large intra-sample variation of Kmean. The anisotropies (Ṕ) of the gneisses vary from 1.05 to 1.62. 83% of the samples display positive shape factors (T) and thus oblate AMS-ellipsoids. Magnetic foliations coincide with metamorphic foliations dipping to the ENE with variable dip angles. The orientations of the principal susceptibility axes show no systematic variation with Kmean at the intra- and inter-sample scale. The average gneiss density is 2.67±0.12 g/cm3. The main carrier of susceptibility is biotite for the paramagnetic gneisses (Kmean 5x10-3 SI). Variation diagram of Kmean versus density outlines a well-constrained positive correlation for paramagnetic gneisses since higher contents of biotite augment both density and Kmean. For the ferromagnetic gneisses the correlation is also well constrained and positive since higher contents of magnetite augment both density and Kmean. Cogenetic gneisses with a large intra-sample variation of Kmean are in particular suitable to better understand possible genetic links between the para- and ferromagnetic gneisses. These particular samples outline diffuse, but nevertheless negative correlations between Kmean and the density corroborating decomposition of magnetite and concomitant biotite formation. Since no impact on the orientation of

  18. U-Pb zircon and CHIME monazite dating of granitoids and high-grade metamorphic rocks from the Eastern and Peninsular Thailand - A new report of Early Paleozoic granite

    Science.gov (United States)

    Kawakami, T.; Nakano, N.; Higashino, F.; Hokada, T.; Osanai, Y.; Yuhara, M.; Charusiri, P.; Kamikubo, H.; Yonemura, K.; Hirata, T.

    2014-07-01

    In order to understand the age and tectonic framework of Eastern to Peninsular Thailand from the viewpoint of basement (metamorphic and plutonic) geology, the LA-ICP-MS U-Pb zircon dating and the chemical Th-U-total Pb isochron method (CHIME) monazite dating were performed in the Khao Chao, Hub-Kapong to Pran Buri, and Khanom areas in Eastern to Peninsular Thailand. The LA-ICP-MS U-Pb zircon dating of the garnet-hornblende gneiss from the Khao Chao area gave 229 ± 3 Ma representing the crystallization age of the gabbro, and that of the garnet-biotite gneisses gave 193 ± 4 Ma representing the timing of an upper amphibolite facies metamorphism. The CHIME monazite dating of pelitic gneiss from the Khao Chao gneiss gave scattered result of 68 ± 22 Ma, due to low PbO content and rejuvenation of older monazite grains during another metamorphism in the Late Cretaceous to Tertiary time. The U-Pb ages of zircon from the Hua Hin gneissic granite in the Hub-Kapong to Pran Buri area scatter from 250 Ma to 170 Ma on the concordia. Granite crystallization was at 219 ± 2 Ma, followed by the sillimanite-grade regional metamorphism at 185 ± 2 Ma. Monazite in the pelitic gneiss from this area also preserves Early to Middle Jurassic metamorphism and rejuvenation by later contact metamorphism by non-foliated granite or by another fluid infiltration event in the Late Cretaceous to Tertiary time. The Khao Dat Fa granite from the Khanom area of Peninsular Thailand gave a U-Pb zircon age of 477 ± 7 Ma. This is the second oldest granite pluton ever reported from Thailand, and is a clear evidence for the Sibumasu block having a crystalline basement that was formed during the Pan-African Orogeny. The Khao Pret granite gives U-Pb zircon concordia age of 67.5 ± 1.3 Ma, which represents the timing of zircon crystallization from the granitic melt and accompanied sillimanite-grade contact metamorphism against surrounding metapelites and gneisses. Metamorphic rocks in the Doi Inthanon area

  19. Geochemistry of the Baishitouquan Amazonite—and Topaz—bearing Granite in the Mid—Tianshan Belt,Xinjiang,China

    Institute of Scientific and Technical Information of China (English)

    顾连兴; 王金珠; 等

    1994-01-01

    The Baishitouquan amazonite and topaz-bearing granite is one of the typical high-rubidium and high-fluorine granites in the eastern part of the Mid-Tianshan belt.This intrusion is in sharp contact with Mid-Proterozoic schists,gneisses and marbles,and is composed of four zones transitional from the bottom upwards:leucogranite,amazonite granite,topaz-bearing amazonite granite and topaz quartz albitite.The Baishitouquan granite contains highly ordered K-feldspar,Li-rich mica,Mn-rich garnet,α-quartz and low-temperature zircon and is chemically high in Si,K,Na,Al,Li,Rb,Cs an F, and low in Ti,Fe,Ca,Mg,P,Co,Ni,Cr,V,Sr and Ba,with Na2O>K2O,Amazonite from the amazonite granite zone contains 1867 ppm Rb.The F contents of bulk rocks are 3040 and 4597 for the amazonite granite and topaz-bearing amazonite granite zones,respectively,These two zones have δ18O values of 8.97-9.85‰(SMOW)and show flat REE distribution patterns with strong Eu depletion.K-Ar and Rb-Sr ages of this inturusion are 226.6 Ma and 209.6 Ma respectively,with an initial 87Sr/86Sr ratio of 0.987±0.213.The Baishitouquan granite is the product of crystallization of a low-temperature,and water,rubidium and fluorine-rich magma,which may have been derived from partial melting of muscovite-rich crustal rocks.Consolidation of this granite involved two contasting and successive stages:melt crystallization and hydrothermal metasomatism and precipitation.Various geological features of this granite were formed during the transition from the magmatic to the hydrothermal stage.

  20. Geochemistry of mylonitic gneisses from the Cycladic Basement Unit (Paros and Serifos, Aegean Sea): implications for protoliths of the high-grade gneisses

    Science.gov (United States)

    McGrath, Annette; Stouraiti, Christina; Windley, Brian

    2016-10-01

    The nature of the protolith(s) of high-grade gneisses from the Aegean Cycladic Basement Unit of the islands of Paros and Serifos is investigated using whole-rock geochemistry and Sr-Nd-O isotopes, in order to better understand their origin and to compare with possible equivalents from the southern Aegean region. On Paros, the basement unit consists of heterogeneous, mylonitized upper amphibolite-grade paragneisses and associated migmatitic rocks, whereas on Serifos, it consists of a mylonitized felsic gneiss, intercalated with layers and lenses of S-type leucogranites and minor mafic metavolcanics. New Nd, Sr and O isotope data suggest a predominantly crustal-derived source in the gneiss protolith from both islands: high initial 87Sr/86Sr ratios (≥7052 to 0.711, calculated at 300 Ma), negative initial ɛNd (-2.8 to -7.7) values for bulk-rock gneiss samples, and high δ18O values of quartz separates (+10 to +12.7 ‰). Major and trace-element variations corroborate that chemical differentiation within the NW Paros gneiss subunit results from progressive migmatitization. Peraluminous gneisses from eastern Paros share clear similarities with metapelitic gneisses from the Naxos gneiss dome, in terms of their trace-element patterns, ɛNd (300) and O isotope characteristics. The mineral assemblage, the fine grain size (due to intense mylonitization), and the metaluminous affinity of the South Serifos grey quartzofeldpathic gneiss do not allow for an unambiguous interpretation for these undated rocks; however, a combination of geochemical parameters and tectonic discrimination diagrams indicates an immature siliciclastic (greywacke) protolith from a continental island arc setting. Sr-Nd isotopic systematics indicates an increasing lower crustal component in gneisses from NW Paros, which is closer to the migmatitic core of the Paros dome. The overall isotopic trend of the gneissic Cycladic Basement Unit on Paros is spatially correlated with that of the Naxos gneiss dome.

  1. Nature and time of emplacement of a pegmatoidal granite within the Delhi Fold Belt near Bayalan, Rajasthan, India

    Science.gov (United States)

    Dasgupta, N.; Sen, J.; Pal, T.; Ghosh, T.

    2009-04-01

    The study area is situated about 70 km south east of Ajmer, in Rajasthan, India around the village Bayala (26o 02' 19 N''; 74o 21' 01'') within the Ajmer district of Central Rajasthan. The area is along the eastern flank of the central portion of the Precambrian South Delhi Fold Belt (SDFB) and it stratigraphically belongs to the Bhim Group of rocks. Basement rocks of Archaean age, commonly known as the Banded gneissic Complex (BGC), is exposed to the east, where the rocks of the Bhim Group rests unconformably over BGC. To the west gneissic basement rocks of mid-Proterozoic times underlie the Bhim Group and have been referred to as the Beawar gneiss (BG). The Bhim Group of rocks comprises of metamorphosed marls and calc-silicate gneisses with minor amounts of quartzites and pelitic schists, indicative of its shallow marine origin. Within the Bhim Group, a pegmatoidal granite has intruded the calc silicate gneisses of the area. The pegmatoidal granite body is elliptical in outline with the long dimension(20 km) trending N-S and covers an area of 300 sq. km. approximately. This granite have so far been mapped as basement rocks (BG) surrounding the Beawar town (26o 06' 05'' N; 74o 19' 03'' E), 50 km south east of Ajmer. Rafts of calc-silicate gneisses, belonging to the Bhim Group, are seen to be entrapped within granite. Fragments of BG and its equivalents have also been found as caught up blocks within this pegmatoidal granite body near Andheri Devari, a small hamlet east of Beawar. The objective of the study was to map this pegmatoidal body, and decipher the mechanism and time of emplacement of this granite. A detailed structural mapping of the area in a 1:20000 scale spread over a 30 sq. km area in the vicinity of Bayala was carried out to analyse the geometry and the time of emplacement of the pegmatitic granite. The ridges of calc silicates and marbles adjoining the area were studied for the structural analyses of the Delhi fold belt rocks of the area. The calc

  2. P- T- t constraints on the development of the Doi Inthanon metamorphic core complex domain and implications for the evolution of the western gneiss belt, northern Thailand

    Science.gov (United States)

    Macdonald, A. S.; Barr, S. M.; Miller, B. V.; Reynolds, P. H.; Rhodes, B. P.; Yokart, B.

    2010-01-01

    The western gneiss belt in northern Thailand is exposed within two overlapping Cenozoic structural domains: the extensional Doi Inthanon metamorphic core complex domain located west of the Chiang Mai basin, and the Mae Ping strike-slip fault domain located west of the Tak batholith. New P- T estimates and U-Pb and 40Ar/ 39Ar age determinations from the Doi Inthanon domain show that the gneiss there records a complex multi-stage history that can be represented by a clockwise P- T- t path. U-Pb zircon and titanite dating of mylonitic calc-silicate gneiss from the Mae Wang area of the complex indicates that the paragneissic sequence experienced high-grade, medium-pressure metamorphism (M1) in the Late Triassic - Early Jurassic (ca. 210 Ma), in good agreement with previously determined zircon ages from the underlying core orthogneiss exposed on Doi Inthanon. Late Cretaceous monazite ages of 84 and 72 Ma reported previously from the core orthogneiss are attributed to a thermal overprint (M2) to upper-amphibolite facies in the sillimanite field. U-Pb zircon and monazite dating of granitic mylonite from the Doi Suthep area of the complex provides an upper age limit of 40 Ma (Late Eocene) for the early stage(s) of development of the actual core complex, by initially ductile, low-angle extensional shearing under lower amphibolite-facies conditions (M3), accompanied by near-isothermal diapiric rise and decompression melting. 40Ar/ 39Ar laserprobe dating of muscovite from both Doi Suthep and Doi Inthanon provided Miocene ages of ca. 26-15 Ma, representing cooling through the ca. 350 °C isotherm and marking late-stage development of the core complex by detachment faulting of the cover rocks and isostatic uplift of the sheared core zone and mantling gneisses in the footwall. Similarities in the thermochronology of high-grade gneisses exposed in the core complex and shear zone domains in the western gneiss belt of northern Thailand (and also in northern Vietnam, Laos, Yunnan

  3. The Montalet granite, Montagne Noire, France: An Early Permian syn-extensional pluton as evidenced by new U-Th-Pb data on zircon and monazite

    Science.gov (United States)

    Poilvet, Jean-Charles; Poujol, Marc; Pitra, Pavel; Van Den Driessche, Jean; Paquette, Jean-Louis

    2011-07-01

    Dating the magmatism in the Montagne Noire gneiss dome in the southern French Massif Central is a key point for understanding the Late Palaeozoic evolution of this part of the Variscan belt, which is characterised by compressive tectonics during the Carboniferous and extensional tectonics during Stephanian-Permian times. The Montalet granite crops out in the north-western part of the dome and was first considered as an early syntectonic intrusion related to compressive deformation. More recently, it has been dated at 327 Ma and considered as contemporaneous with the diapiric ascent of the Montagne Noire gneiss dome before the Stephanian-Permian extension. We show that in fact, this pluton was emplaced 294 ± 1 Ma ago and is therefore contemporaneous with the Stephanian-Permian extension. This age is consistent with the interpretation of the Montagne Noire Massif as an extensional gneiss dome.

  4. Artificial weathering of granite

    Directory of Open Access Journals (Sweden)

    Silva Hermo, B.

    2008-06-01

    Full Text Available This article summarizes a series of artificial weathering tests run on granite designed to: simulate the action of weathering agents on buildings and identify the underlying mechanisms, determine the salt resistance of different types of rock; evaluate consolidation and water-repellent treatment durability; and confirm hypotheses about the origin of salts such as gypsum that are often found in granite buildings. Salt crystallization tests were also conducted, using sodium chloride, sodium sulphate, calcium sulphate and seawater solutions. One of these tests was conducted in a chamber specifically designed to simulate salt spray weathering and another in an SO2 chamber to ascertain whether granite is subject to sulphation. The test results are analyzed and discussed, along with the shortcomings of each type of trial as a method for simulating the decay observed in monuments. The effect of factors such as wet-dry conditions, type of saline solution and the position of the planes of weakness on the type of decay is also addressed.En este trabajo se hace una síntesis de varios ensayos de alteración artificial realizados con rocas graníticas. Estos ensayos tenían distintos objetivos: reproducir las formas de alteración encontradas en los edificios para llegar a conocer los mecanismos que las generan, determinar la resistencia de las diferentes rocas a la acción de las sales, evaluar la durabilidad de tratamientos de consolidación e hidrofugación y constatar hipótesis acerca del origen de algunas sales, como el yeso, que aparecen frecuentemente en edificios graníticos. En los ensayos de cristalización de sales se utilizaron disoluciones de cloruro de sodio, sulfato de sodio, sulfato de calcio y agua de mar. Uno de estos ensayos se llevó a cabo en una cámara especialmente diseñada para reproducir la alteración por aerosol marino y otro se realizó en una cámara de SO2, con el objeto de comprobar si en rocas graníticas se puede producir

  5. The Acasta Gneisses revisited: Evidence for an early depleted mantle

    Science.gov (United States)

    Scherer, E. E.; Sprung, P.; Bleeker, W.; Mezger, K.

    2010-12-01

    The oldest known mineral samples crystallized on the Earth are the up to 4.4 Ga zircon grains from the Jack Hills, Australia [e.g., 1,2]. Zircon, which is datable by U-Pb, contains ca. 1 wt% Hf, and has very low Lu/Hf, is well suited to recording the initial 176Hf/177Hf of its parent magma. It has therefore been widely used to track Earth’s crust-mantle differentiation over time and to estimate the relative amounts of juvenile and recycled components that contributed to Archean and Hadean crust. [e.g., 3,4,5,6]. Zircon studies may be subject to sampling bias, however: Juvenile mafic magmas are likely to stem from depleted sources, but are less likely to crystallize zircon. Processes such as host-rock metamorphism, remelting, weathering of the host rock, and sedimentary transport of grains may have further biased the zircon population. Metamict grains or those with high aspect ratios are likely to be destroyed by these processes, potentially biasing the zircon Hf record toward enriched compositions such that the degree of mantle depletion remains poorly defined before 4 Ga. In addition, incorrect age assignments to Hf analyses result in spurious initial ɛHf values. Here, we attempt to overcome these issues by investigating the bulk rock Lu-Hf and Sm-Nd systematics of some of the oldest rocks on Earth, the Acasta Gneisses (Northwest Territories, Canada). Earlier studies showed that zircon grains in these gneisses tend to come from enriched sources [e.g, 3,7,8] and are thus of little use for directly tracking the degree of mantle depletion. Furthermore, the gneisses themselves have been multiply metamorphosed and are often affected by mixing: The banded gneisses in particular comprise several magmatic precursor rocks of different age that have been repeatedly folded into each other. This promted questions of whether zircon ages should be used in the calculation of bulk rock initial epsilon Nd, and whether linear trends on Sm-Nd isochron represented meaningful

  6. Status of LLNL granite projects

    Energy Technology Data Exchange (ETDEWEB)

    Ramspott, L.D.

    1980-12-31

    The status of LLNL Projects dealing with nuclear waste disposal in granitic rocks is reviewed. This review covers work done subsequent to the June 1979 Workshop on Thermomechanical Modeling for a Hardrock Waste Repository and is prepared for the July 1980 Workshop on Thermomechanical-Hydrochemical Modeling for a Hardrock Waste Repository. Topics reviewed include laboratory determination of thermal, mechanical, and transport properties of rocks at conditions simulating a deep geologic repository, and field testing at the Climax granitic stock at the USDOE Nevada Test Site.

  7. Granites petrology, structure, geological setting, and metallogeny

    CERN Document Server

    Nédélec, Anne; Bowden, Peter

    2015-01-01

    Granites are emblematic rocks developed from a magma that crystallized in the Earth’s crust. They ultimately outcrop at the surface worldwide. This book, translated and updated from the original French edition Pétrologie des Granites (2011) is a modern presentation of granitic rocks from magma genesis to their crystallization at a higher level into the crust. Segregation from the source, magma ascent and shapes of granitic intrusions are also discussed, as well as the eventual formation of hybrid rocks by mingling/mixing processes and the thermomechanical aspects in country rocks around granite plutons. Modern techniques for structural studies of granites are detailed extensively. Granites are considered in their geological spatial and temporal frame, in relation with plate tectonics and Earth history from the Archaean eon. A chapter on granite metallogeny explains how elements of economic interest are concentrated during magma crystallization, and examples of Sn, Cu, F and U ore deposits are presented. Mi...

  8. Experimental study on dehy- dration melting of natural biotite-plagioclase gneiss from High Himalayas and implica- tions for Himalayan crust anatexis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Here we present the results of dehydration melting, melt morphology and fluid migration based on the dehydration melting experiments on natural biotite- plagioclase gneiss performed at the pressure of 1.0-1.4 GPa, and at the temperature of 770-1028℃. Experimental results demonstrate that: (ⅰ) most of melt tends to be distributed along mineral boundaries forming "melt film" even the amount of melt is less than 5 vol%; melt connectivity is con-trolled not only by melt topology but also by melt fraction; (ⅱ) dehydration melting involves a series of subprocesses including subsolidus dehydration reaction, fluid migration, vapor-present melting and vapor-absent melting; (ⅲ) ex-periments produce peraluminous granitic melt whose com-position is similar to that of High Himalayan leucogranites (HHLG) and the residual phase assemblage is Pl+Qz+Gat+Bio+Opx±Cpx+Ilm/Rut±Kfs and can be compa-rable with granulites observed in Himalayas. The experi-ments provide the evidence that biotite-plagioclase gneiss is one of source rocks of HHLG and dehydration melting is an important way to form HHLG and the granulites. Addition-ally, experimental results provide constraints on determining the P-T conditions of Himalayan crustal anatexis.

  9. Zr, Hf, U, Th and REE-Fertile Lower Proterozoic Potassic Granite from Parts of Andhra Pradesh, South India

    Institute of Scientific and Technical Information of China (English)

    Yamuna SINGH

    2004-01-01

    The medium- to coarse-grained and porphyritic granitoid of Dharmawaram, Karimnagar district, Andhra Pradesh, south India is a biotite-hornblende granite with notable contents of rare metal (Zr, Hf, Th) and rare earth (including Y) minerals like zircon, thorite, allanite, monazite and xenotime. Chemically, it is metaluminous (average A/C+N+K = 0.95)-type, potassic (ay. 5% K2O) granite, with dominantly sub-alkaline characters. It shows up to 8 times enrichment of rare metals (Zr, Hf, U, Th) and rare earths (including Y, Sc), with reference to their abundances in normal unevolved granite, and hence, fertile for some of these elements. Field, petrological, geochemical and isotopic data of potassic granite (PG) indicate involvement of silica-rich metasedimentary-basic crustal rocks (amphibole-quartzite,amphibolite, hornblende-biotite gneiss, etc.) in its genesis, at a depth range of 30 km. Further, chondrite-normalized REE patterns demonstrate that low-degree partial melting of source rocks is the major controlling factor in the genesis of PG.Mild negative Eu-anomaiy (av. Eu/Eu* = 0.48), plots of Ba-Rb-Sr in the field of anomalous granite and K/Rb ratios (av.239) in the range that is shown by normal unevolved granite together indicate less fractionated nature of the PG. Limited fractionation of metalumination-type, involving hornblende, led to occasional weak alumina saturation. Interestingly,geochemical and petrogenetic features of the studied PG broadly match with those potassic granites which are already known to host anomalously high enrichment of rare metals and rare earths in other parts of Andhra Pradesh and adjoining Kamataka.

  10. Reconnaissance geology and geochronology of the Precambrian of the Granite Mountains, Wyoming

    Science.gov (United States)

    Peterman, Zell E.; Hildreth, Robert A.

    1978-01-01

    The Precambrian of the western part of the Granite Mountains, Wyoming, contains a metamorphic complex of gneisses, schists, and amphibolites that were derived through amphibolite-grade metamorphism from a sedimentary-volcanic sequence perhaps similar to that exposed in the southeastern Wind River Mountains. Whole-rock Rb-Sr dating places the time of metamorphism at 2,860?80 million years. A high initial 87Sr/ 86 S r ratio of 0.7048 suggests that either the protoliths or the source terrane of the sedimentary component is several hundred million years older than the time of metamorphism. Following an interval of 300:t100 million years for which the geologic record is lacking or still undeciphered, the metamorphic complex was intruded by a batholith and satellite bodies of medium- to coarse-grained, generally massive biotite granite and related pegmatite and aplite. The main body of granite is dated at 2,550?60 million years by the Rb-Sr method. Limited data suggest that diabase dikes were emplaced and nephrite veins were formed only shortly after intrusion of the granite. Emplacement of the granite at about 2,550 million years ago appears to be related to a major period of regional granitic plutonism in the Precambrian of southern and western Wyoming. Granites, in the strict sense, that are dated between 2,450 and 2,600 million years occur in the Teton Range, the Sierra Madre, the Medicine Bow Mountains and the Laramie Range. This episode of granitic plutonism occured some 50 to 100 million years later than the major tonalitic to granitic plutonism in the Superior province of northern Minnesota and adjacent Ontario-the nearest exposed Precambrian W terrane that is analogous to the Wyoming province. Initial 87Sr / 86Sr ratios of some of the Wyoming granites are higher than expected if the rocks had been derived from juvenile magmas and it is likely that older crustal rocks were involved to some degree in the generation of these granites. Slightly to highly disturbed

  11. Timing and duration of partial melting and magmatism in the Variscan Montagne Noire gneiss dome (French Massif Central)

    Science.gov (United States)

    Trap, Pierre; Roger, Françoise; Cenki-Tok, Bénédicte; Paquette, Jean-Louis

    2017-03-01

    Unravelling the detailed pressure-temperature-time-deformation (P-T-t-D) evolution of magmatic and metamorphic rocks provides essential insights into the timing and duration of partial melting and related plutonism during crustal flow and migmatitic dome formation. The Montagne Noire Axial Zone (MNAZ) is a migmatitic dome located within the Variscan orogen in the southern French Massif Central. The timing of the main thermal event that was responsible for intense partial melting is still highly debated. In this study we present new laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) age data on micaschists, migmatites and granites that clarify the P-T-t-D evolution of the MNAZ. Structurally controlled samples were collected in order to constrain the timing of metamorphism, migmatization and plutonism regarding the main structural pattern D1, D2 and D3. D1 and D2 correspond to nappe stacking and dextral transpression, respectively. D3 is related to vertical shortening and coaxial thinning with a preferential NE-SW- to E-W-directed stretching. LA-ICP-MS analyses on the syntectonic Anglès, Soulié and Martys granites yielded U-Th/Pb monazite ages of 305 ± 1.5, 306 ± 1.9 and 314 ± 2 Ma, respectively. Five migmatitic rocks sampled in the eastern and central Espinouse area yielded in situ ages ranging between 312 ± 2 and 301 ± 2 Ma. Along the dome envelope, two garnet-staurolite-bearing micaschists near Saint-Pons-de-Thomières village gave in situ U-Th-Pb ages of 312.1 ± 2.1 and 309.0 ± 3.1 Ma. A fine-grained gneiss with a D3 fabrics in the eastern dome envelope yield a 208Pb/232Th mean age at 305.7 ± 3.9 Ma. All ages obtained in this study for the micaschists, migmatites and granites range between 315 and 301 Ma. We interpret this time span as the record of the high thermal event responsible for intense crustal partial melting within the lower and middle crust. The onset of partial melting occurred at ca. 315 Ma that marked the beginning of

  12. Tonian granitic magmatism of the Borborema Province, NE Brazil: A review

    Science.gov (United States)

    Guimarães, Ignez P.; de Fatima L. de Brito, Maria; de A. Lages, Geysson; da Silva Filho, Adejardo F.; Santos, Lucilene; Brasilino, Roberta G.

    2016-07-01

    Tonian granitoids, today augen-gneisses and migmatites, showing crystallization ages ranging from 870 Ma to 1000 Ma occur in the Borborema Province, NE Brazil. The majority of them have ages within the 925-970 Ma interval. Few intrusions with ages of ∼1.0 Ga and successions and metasedimentary sequences in the Transversal and South subprovinces. Tonian granitoids are unknown in the North subprovince. The CVG comprise mainly coarse-grained augen-gneisses of granite to granodiorite composition. Fe-rich biotite (annite) is the main mafic mineral phase, constituting up to 15% of the modal composition. Garnet, muscovite and tourmaline occur as accessory phases in many plutons. The CVG augen-gneisses have high SiO2 (>71%) and alkali contents, they vary from slightly peraluminous to slightly metaluminous, and from slightly magnesian to typical ferrroan rocks. In the migmatized orthogneisses the SiO2 contents are usually 40 ppm). The chondrite normalized REE patterns are characterized by strong to moderate negative Eu anomalies (Eu/Eu* = 0.23-0.70). In general, the spidergram patterns show deep troughs at Ti, P, Ba and Sr and less pronounced Nb-Ta troughs. These patterns are similar to those reported for anorogenic granites evolved from mixtures of magmas from both crustal and mantle sources. The CVG exhibit TDM model ages ranging from 1.9 to 1.1Ga, with slightly negative to slightly positive ƐNd(t) values, suggesting the involvement of distinct proportions of mantle and crustal components in the source of their protoliths. There is no consensus in the literature about the tectonic setting of the CVG ie they have been related to either continental margin magmatic arc, with possible back-arc association, or extention-related setting, with generation of A-type granites. However, all the available geochemical data suggest that the CVG represent extension related magmatism. The geochemical signature associated to bimodal volcanism, including pyroclastic rocks, with similar

  13. The protoliths to the sillimanite gneisses from the Larsemann Hills and geological implication in their formation

    Institute of Scientific and Technical Information of China (English)

    Ren Liudong; Yang Chonghui; Wang Yanbin; Liu Ping; Zhao Yue

    2009-01-01

    The source rock from which the sillimanite gneisses derive mainly was the biotite plagioclase gneiss in the Larsemann Hills. It is the deformation-metamorphism process under special pressure and temperature condition, not the original rock compositions, that controls the presence of sillimanite. To a great degree, the sillimanite gneiss was the mixture of the detaining materials of the migrating felsic melt from the bt-plagioclase gneiss that underwent partial melting and the relics when the melt was removed. In sillimanitization the original rock had been changed substantially in chemical composition. The related metamorphism process severely deviated from the isochemical series, the process was of, therefore, an open system. In addition, the Al2O3 contents of the original rock was an important, but not critical factor for the formation of sillimanite, i.e., the sillimanite-bearing rock need not be of aluminum rich in composition, and vise contrarily, the aluminum rock may not produce sillimanite. The authors of the present paper postulate that the source rock from which the aluminum rich rock derives need not be of aluminum rich, but sillimanitization is generally the Al2O3 increasing process. The aluminum rich sediments such as clay or shale need not correspond directly to sillimanite-rich gneisses. No argillaceous rock present equals to sillimanite-rich gneiss in chemical composition. The protoliths to the sillimanite gneisses from the Larsemann Hills, east Antarctica, and their adjacent area may be pelite, shale greywacke, sub-greywacke, quartz sandstone and quartz-tourmalinite. If correct, the conclusion will be of significant implication for the determination of the sillimanite gneiss formation process and the reconstruction of the protolith setting.

  14. Contrasting Structures and Deformational History of Syntectonic Granites of Campina Grande and Serra Redonda, Borborema Province, NE Brazil

    Directory of Open Access Journals (Sweden)

    Sérgio Wilians de Oliveira Rodrigues

    2011-04-01

    Full Text Available The Campina Grande and Serra Redonda Granites are intrusive along the contact of the Paleoproterozoic basement(Alto Moxotó Domain with the Tonian gneisses (Alto Pajeú Domain of the Borborema Province (northeast Brazil. TheCampina Grande Granite (U-Pb age = 581± 2 Ma shows a concentric oval-shaped structure whereas the Serra RedondaGranite (U-Pb age = 576 ± 3 Ma has a tabular shape, elongated in the NE-SW direction. The plutons are separated bythe left-lateral Galante transcurrent shear zone. In this study, the anisotropy of magnetic susceptibility (AMS was appliedto 64 outcrops of granites to determine the internal structures of these plutons and to explore the relationship betweenmagmatism and deformation in an orogenic setting. The magnetic fabrics are concordant with the metamorphic structure ofthe host rocks. Strike-slip shear zones controlled the emplacement of the Serra Redonda Granite, as indicated by sigmoidalfoliation, defining shear bands associated with the Galante shear zone. In contrast, the magmatic/magnetic fabric of theCampina Grande granite seems to have been produced by body (ascensional forces. The pluton displays an inward dipping, concentric planar fabric parallel to the wall rock contact and lineations highly oblique to the foliation trend. The fabric of the Campina Grande pluton is consistent with a magma moving over a ramp dipping to southwest, with the lineation at high angle to the NE-trending flow direction. The contrasting structures of the plutons reflect the episodic nature of orogenic deformation, which was punctuated by the alternation of weak and strong strains, affecting the fabric development of the syntectonic intrusions.

  15. Zircon dating and mineralogy of the Mokong Pan-African magmatic epidote-bearing granite (North Cameroon)

    Science.gov (United States)

    Tchameni, R.; Sun, F.; Dawaï, D.; Danra, G.; Tékoum, L.; Nomo Negue, E.; Vanderhaeghe, O.; Nzolang, C.; Dagwaï, Nguihdama

    2016-09-01

    We present the mineralogy and age of the magmatic epidote-bearing granite composing most of the Mokong pluton, in the Central Africa orogenic belt (North Cameroon). This pluton intrudes Neoproterozoic (~830 to 700 Ma) low- to high-grade schists and gneisses (Poli-Maroua group), and is crosscut or interleaved with bodies of biotite granite of various sizes. The pluton is weakly deformed in its interior, but solid-state deformation increases toward its margins marked by narrow mylonitic bands trending NNE-SSW. The magmatic epidote granitic rocks are classified as quartz monzodiorite, granodiorite, monzogranite, and syenogranite. They are medium- to coarse-grained and composed of K-feldspar + plagioclase + biotite + amphibole + epidote + magnetite + titanite + zircon + apatite. In these granites, the pistacite component [atomic Fe+3/(Fe3+ + Al)] in epidote ranges from 16 to 29 %. High oxygen fugacity (log ƒO2 - 14 to -11) and the preservation of epidote suggest that the magma was oxidized. Al-in hornblende barometry and hornblende-plagioclase thermometry indicate hornblende crystallization between 0.53 and 0.78 GPa at a temperature ranging from 633 to 779 °C. Zircon saturation thermometry gives temperature estimates ranging from 504 to 916 °C, the latter being obtained on samples containing inherited zircons. U/Pb geochronology by LA-ICP-MS on zircon grains characterized by magmatic zoning yields a concordia age of 668 ± 11 Ma (2 σ). The Mokong granite is the only known occurrence magmatic epidote in Cameroon, and is an important milestone for the comparison of the Central Africa orogenic belt with the Brasiliano Fold Belt, where such granites are much more abundant.

  16. Status of the GRANIT facility

    CERN Document Server

    Roulier, Damien; Baessler, Stefan; Clément, Benoît; Morton, Daniel; Nesvizhevsky, Valery; Pignol, Guillaume; Rebreyend, Dominique

    2014-01-01

    The GRANIT facility is a follow-up project, which is motivated by the recent discovery of gravitational quantum states of ultracold neutrons. The goal of the project is to approach the ultimate accuracy in measuring parameters of such quantum states and also to apply this phenomenon and related experimental techniques to a broad range of applications in particle physics as well as in surface and nanoscience studies. We overview the current status of this facility, the recent test measurements and the nearest prospects.

  17. Petrogenesis of the Neoarchean granitoid gneisses in northern Hebei Province%冀北太古代花岗质片麻岩的成因

    Institute of Scientific and Technical Information of China (English)

    刘树文; 吕勇军; 王伟; 杨朋涛; 白翔; 凤永刚

    2011-01-01

    series are recognized: ( 1) low-K calc-alkaline series produced by low degrees of partial melting of tholeiitic basalts; (2) medium-K calc-alkaline series derived mainly from partial melting of basalts and greywackes, with local melting of tonalitic gneisses; (3) high-K calc-alkaline series produced by partial melting of greywackes consisting chiefly of high-K intermediate to acid volcanic rocks. Integrated with recently Early Precambrian study in the northern Hebei Province, the petrogenesis of these granitic gneisses reveals an important Archean crust growth at ca. 2. 7Ga in the northern Hebei Province. Large scale of volcanic eruptions occurred at the Early Noearchean, which constructed the protoliths of these granitic gneisses, and subsequently partial melting of these volcanic and related volcanic sedimentary rocks produced the magmas of TTGM, followed by regional metamorphism and deformation. The geodynamic processes producing these Neoarchen granitic gneisses suggest that their tectonic background are analogous to the west coast of the South America, implying a transitional geodynamic regime from convergent compression to back-arc extension in the northern Hebei Province.

  18. Augen gneisses versus Augen gneisses from the Jaguaribeana Belt, northeastern region from Brazil: stratigraphy, geochemistry and U-Pb ages; Augen gnaisses versus Augen gnaisses da faixa Jaguaribeana, NE do Brasil: estratigrafia, geoquimica e idades U-Pb

    Energy Technology Data Exchange (ETDEWEB)

    Sa, Jaziel Martins; Silva, Elvis Roberto da [Rio Grande do Norte Univ., Natal, RN (Brazil). Dept. de Geologia; Bertrand, Jean Michel [Savoie Univ., 73 - Chambery (France). Lab. de Geodynamique; Leterrier, Jacques [Centre National de la Recherche Scientifique (CNRS), 54 - Nancy (France). Centre de Recherches Petrographiques et Geochimiques

    1997-12-31

    The Jaguaribeana Belt is located at Borborema Province, Ceara State, Brazil and this study aims to present Uranium-Lead (U-Pb) data and the augen gneisses petrographic and geochemical study of the Jaguaribe Belt, and to realize comparisons between these and the augen gneisses from the Oros Belt. It describes the geological characteristics of this region, the augen gneisses petrography and geochemical data and the U-Pb method results for a discussion about the augen gneisses from the Oros and Jaguaribe Belt 10 refs., 6 figs.

  19. Regional variation in the Amitsoq gneisses related to crustal levels during late Archean granulite facies metamorphism: Southern west Greenland

    Science.gov (United States)

    Nutman, A. P.; Bridgwater, D.; Mcgregor, V. R.

    1986-01-01

    The dominant lithology at Kangimut sangmissoq is described as nebulitic tonalitic gneiss containing highly distended plagioclase phyric amphibolites. The gneiss amphibolite complex was intruded by Nuk gneiss between 3.05 and 2.90 Ga and later (2.6 to 2.7 Ga) by post granulite facies granitoid sheets. The amphibolites are though to be Ameralik dikes and the older gray gneiss are then Amitsoq by definition. The problem arises when the isotopic data are considered, none of which indicate rocks older that about 3.0 Ga.

  20. Soil-gas helium and surface-waves detection of fault zones in granitic bedrock

    Indian Academy of Sciences (India)

    G K Reddy; T Seshunarayana; Rajeev Menon; P Senthil Kumar

    2010-10-01

    Fracture and fault networks are conduits that facilitate groundwater movement in hard-rock terrains.Soil-gas helium emanometry has been utilized in Wailapally watershed,near Hyderabad in southern India,for the detection of fracture and fault zones in a granite basement terrain having a thin regolith.Based on satellite imagery and geologic mapping,three sites were selected for detailed investigation.High spatial resolution soil-gas samples were collected at every one meter at a depth of <1.5m along 100 m long profiles (3 in number).In addition,deep shear-wave images were also obtained using the multichannel analysis of surface waves.The study clearly indicates several soil-gas helium anomalies (above 200 ppb)along the pro files,where the shear-wave velocity images also show many near-surface vertical low velocity zones.We thus interpret that the soil-gas helium anomalous zones and the vertical low-velocity zones are probable traces of fault/fracture zones that could be efficient natural recharge zones and potential groundwater conduits.The result obtained from this study demonstrates the efficacy of an integrated approach of soil-gas helium and the seismic methods for mapping groundwater resource zones in granite/gneiss provinces.

  1. Structures, kinematics, thermochronology and tectonic evolution of the Ramba gneiss dome in the northern Himalaya

    Institute of Scientific and Technical Information of China (English)

    Lei Guo; Jinjiang Zhang; Bo Zhang

    2008-01-01

    The Ramba gneiss dome, one of the north Himalayan gneiss domes, is composed of three tectono-lithologic units separated by an upper and a lower detachment fault. Low-grade metamorphic Tethyan Himalayan sedimentary sequence formed the upper unit above the brittle upper detachment fault. Mylonitic gneiss and a leucogranite pluton made up the lower unit beneath the ductile lower detach-ment fault. Mylonitic middle-grade garnet-, staurolite- and andalusite-schist constituted the middle unit between the two faults, which may be that the basal part of the upper unit experienced detachment shear. The Ramba dome underwent three episodes of deformationin its tectonic evolution. The first episode was a top-down-to-north-northwest sliding possibly related to the activity of the south Tibetan detachment system (STDS). The second episode was the dominant deformation related to a east-west extension, which resulted in a unique top-down-to-east kinematics and the major tectonic features of the dome. The third episode was a collapse sliding toward the outsides of the dome. The Ramba gneiss dome is possibly a result of the east-west extension and magmatic diapir. The lower detachment fault is probably the main detachment fault separating the sedimentary sequence from the crystalline basement during the east-west extension in the dominant deformation episode. The diapir of the leucogranite pluton formed the doming shape of the Ramba gneiss dome. This pluton intruded in the core of the dome in a late stage of the dominant deformation, and its Ar-Ar cooling ages are about 6 Myr. This indicates that the dominant deformation of the dome happened at the same time of the east-west extension represented by the north-south trending riffs throughout the northern Himalaya and southern Tibet. Therefore, the formation of the Ramba gneiss dome should be related to this east-west extension.

  2. Granite Exfoliation, Cosumnes River Watershed, Somerset, California

    Science.gov (United States)

    Crockett, I. Q.; Neiss-Cortez, M.

    2015-12-01

    In the Sierra Nevada foothills of California there are many exposed granite plutons within the greater Sierra Nevada batholith. As with most exposed parts of the batholith, these granite slabs exfoliate. It is important to understand exfoliation for issues of public safety as it can cause rock slides near homes, roads, and recreation areas. Through observation, measuring, and mapping we characterize exfoliation in our Cosumnes River watershed community.

  3. Origin and evolution of Gneiss-Charnockite rocks of Dharmapuri District, Tamil Nadu, India

    Science.gov (United States)

    Rao, D. Rameshwar; Narayana, B. L.

    1988-01-01

    A low- to high-grade transition area in Dharmapuri district was investigated petrologically and geochemically. The investigation confirmed the presence of a continuous section through a former lower crust, with felsic charnockites predominating the lower part and felsic gneisses the upper part. The structure of original gneisses is preserved in charnockites and the latter show petrographic evidence for prograde metamorphism. The prograde metamorphism is of isochemical nature as revealed by the similarity of compositions of tonalitic gneisses and tonalitic charnockites. However, the depletion of LIL elements particularly Rb, caused variation in K/Rb ratios from low values (345) in the gneisses in upper part to higher values (1775) in the charnockites in the lower crust. This variation in K/Rb ratio in a north to south traverse is related to the progressive break-down of hydrous minerals under decreasing H2O and increasing CO2 fluid conditions. Metasomatism and partial melting has also taken place to a limited extent along shear planes and weak zones. During cooling the H2O circulation affected substantial auto-regression in the transition zone resulting in the formation of second generation biotite.

  4. Geology and U-Pb geochronology of the Banabuiu granite, Northeastern Ceara, Brazil; Geologia y geocronologia U-Pb del granito de Banabuiu, Noreste de Ceara, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Lima, M. N.; Nogueira Neto, J. A.; Azevedo, M. R.; Valle Aguado,

    2010-07-01

    The Banabuiu massif crops out in the Central Ceara Domain (DCC) of the Borborema Province (NE Brasil), as an N-S elongate granite intrusion, concordant with the regional structures. It was emplaced into basement rocks of Paleoproterozoic age, extensively transformed into gneisses and migmatites during the Brasilian orogeny ({approx}600 Ma). Using U-Pb zircon dating, the crystallization age of the Banabuiu syn-kinematic two-mica granite was estimated at 578.6 {+-} 6.5 Ma. The granite is strongly peraluminous (A/CNK 1,098 - 1,134) and shows a typical S-type geochemical signature. The {epsilon}Nd{sub 5}80 values are strongly negative ({epsilon}Nd{sub 5}80 = -19 a - 23) and partially overlap with those of the Paleoproterozoic gneissmigmatite complex ({epsilon}Nd{sub 5}80 = -12 to -26), suggesting that the parental magmas of the Banabuiu granite could have been produced by partial melting of similar crustal materials. (Author) 21 refs.

  5. Rb-Sr and Sm-Nd study of granite-charnockite association in the Pudukkottai region and the link between metamorphism and magmatism in the Madurai Block

    Science.gov (United States)

    Sekaran, M. Chandra; Bhutani, Rajneesh; Balakrishnan, S.

    2016-04-01

    Pudukkottai region in the northeastern part of the Madurai Block exposes the garnetiferous pink granite that intruded the biotite gneiss. Charnockite patches are associated with both the rock types. Rb-Sr biotite and Sm-Nd whole-rock isochron ages indicate a regional uplift and cooling at ˜550 Ma. The initial Nd isotope ratios (\\varepsilon _{ {Nd}}t=-20 to -22) and Nd depleted-mantle model ages (TDM = 2.25 to 2.79 Ga) indicate a common crustal source for the pink-granite and associated charnockite, while the biotite gneiss and the charnockite within it represent an older crustal source (\\varepsilon _{ {Nd}}t= -29 and TDM = > 3.2 Ga). The Rb-Sr whole-rock data and initial Sr-Nd isotope ratios also help demonstrate the partial but systematic equilibration of Sr isotope and Rb/Sr ratios during metamorphic mineral-reactions resulting in an `apparent whole-rock isochron'. The available geochronological results from the Madurai Block indicate four major periods of magmatism and metamorphism: Neoarchaean-Paleoproterozoic, Mesoproterozoic, mid-Neoproterozoic and late-Neoproterozoic. We suggest that the high-grade and ultrahigh-temperature metamorphism was preceded by magmatism which `prepared' the residual crust to sustain the high P- T conditions. There also appears to be cyclicity in the tectono-magmatic events and an evolutionary model for the Madurai Block should account for the cyclicity in the preserved records.

  6. The Pedregal granite (Portugal: petrographic and geochemical characterization of a peculiar granitoid

    Directory of Open Access Journals (Sweden)

    Ferreira, J. A.

    2014-12-01

    Full Text Available The Pedregal granite outcrops in the Central Iberian Zone, northern Portugal, in the eastern border of a synorogenic variscan granite-migmatite complex sub-concordant with the regional metamorphic structures. It is a granitoid (ca. 3 km2 with an elongated NW-SE shape intruded in staurolite-micaschist and banded gneiss-migmatite rocks, with local igneous breccias in the contact. The country rocks belong to a metapelitic and metasammitic sequence of Edicarian-Cambrian age, known as the “Complexo Xisto-Grauváquico” (CXG which shows a main regional foliation with a NW-SE to NNW-SSE direction. The Pedregal granite is peraluminous (its A/CNK parameter ranges from 1.18 to 1.62, with a magnesian and alkali to alkali-calcic signature. The peculiar features of the granite are high contents of Zr (389 to 435 ppm and a LREE flat pattern, which are uncommon characteristics for granitic rocks, as well as the corroded shape of the biotite, and the large amount of secondary muscovite. These peculiar features distinguish it from the adjacent synorogenic granites. The field, petrographical and chemical features of the Pedregal granite are in accordance with a second phase of partial melting of a residuum, depleted by melt segregation during a first melting episode with the involvement of peritectic garnet and abundant residual biotite with LREE- and Zr-bearing accessory minerals. Besides, the intrusive character of the granite, and the presence of metasedimentary xenoliths point out to a secondary diatexite.El granito de Pedregal aflora en la Zona Centro-Ibérica, en el norte de Portugal, en el borde oriental de un complejo granito-migmatítico sinorogénico varisco, subconcordante con las estructuras metamórficas regionales. Es un granitoide (ca. 3 km2 de forma elongada NW-SE, que intruye en micaesquistos estaurolíticos y en rocas gneissico- migmatíticas bandeadas, con brechas ígneas locales en el contacto. Las rocas encajantes pertenecen a una

  7. Gneisses (Serizzi and Beole) of the Verbano-Cusio-Ossola district (Piedmont, Northern Italy): possible candidates for the designation of "Global Heritage Stone province"

    Science.gov (United States)

    Antonella Dino, Giovanna; Borghi, Alessandro; Cavallo, Alessandro; Primavori, Piero

    2016-04-01

    The Verbano-Cusio-Ossola quarrying district (Piedmont, northern Italy) produces many different ornamental stones (granites, gneisses, marbles): two really important categories are represented by Serizzo and Beola gneisses. Several varieties of Serizzo and Beola crop out in the upper and middle Ossola Valley: Serizzo derives from the Antigorio, Monte Leone and Monte Rosa Penninic Units, whereas Beola from the Monte Leone, Orselina-Moncucco-Isorno and Monte Rosa Penninic Units, as well from the Fobello-Rimella schists (Austroalpine). The Serizzo, represented by a group of foliated granitoid orthogneisses (Serizzo Antigorio, Serizzo Formazza, Serizzo Sempione and Serizzo Monte Rosa varieties), is probably the most important and extensively exploited ornamental stones from the VCO province (about 70% of the VCO stone production). The quarries are mostly concentrated in the Antigorio and Formazza valleys, where the Antigorio nappe has a sub-horizontal attitude and reaches its greatest thickness (up to 1000 m). This stone was largely used to produce columns since the end of XV century (e.g. the old Ospedale Maggiore in Milano, now University of Milano) and later on it was replaced with granites. It was also used in the building structure of the Duomo di Milano, for the plinth and the piers. Nowadays, thanks to its good wear resistance and low cost, it is mainly used in polished slabs for paving: a recent application is the Frankfurt airport floor. Beola is the name of a group of heterogeneous orthogneisses with mylonitic foliation and strong mineralogical lineation (Beola Grigia, Bianca, Ghiandonata, Striata varieties), easy to split into thin slabs with hammer and chisel, occurring in the middle Ossola Valley, between Vogogna and Montecrestese. The quarries of Beola are probably the oldest of the Ossola Valley, although the precise period in which the stone started to be exported is unknown. The Beola trade probably started at the end of the XIII century, with the

  8. Rare metal granites and related rocks of the Ukrainian shield

    Directory of Open Access Journals (Sweden)

    Esipchuk, K.Ye.

    1993-12-01

    Full Text Available Two rare metal leucocratic granites, Perga and Kamennaya complexes, can be distinquished on the Ukrainian shield. The Perga complex consists of medium- and coarse grained, mainly porphyric, biotite, riebeckite and aegirine granites, granite porphyries, microclinites and albitites with rare metal mineralization (genthelvite, phenacite, tantalite, cassiterite and wolframite etc.. Granites from several stocks (up to 30 km2 in the northwestern part of the shield, situated along the fracture zone, restricted the large Korosten pluton of rapakivi granites to the northwest. The age of these granites (Pb-Pb and U-Pb methods on zircon and monazite practically coincide with the age of rapakivi granites being 1750 Ma. Within the Korosten complex of rapakivi granites we consider that zinnwaldite granites, which are characterized by fluorite and topazine mineralization, represent the final phase of pluton. These granites differ from the Perga ones by their low content of rare metals. The Kamennaya Mogila complex lies in the southeastern part of the Ukrainian shield. It consists of biotite and muscovite-biotite, medium- and coarse-grained (also porphyric, and occasionally greisining granites with rare metal mineralization (cassiterite, columbite, molybdenite, wolframite and beryl. Granites form several stocks (5-30 km2 situated 10-30 km to the west-northwest of the South-Kalchik gabbro-syenite-granite pluton. Granitoids in both of these complexes have similar isotopic ages (1800 Ma. Leucocratic subalkaline granites (the Novoyanisol type are known within the pluton itself, occupying an intermediate position between the above mentioned in terms of mineral and geochemical composition. The gabbro-syenite-granite formation of the Nearazov region has a substantial similarity to the anorthosite-rapakivi-granite formation. In this respect the relation of each of them to rare metal granites is rather remarkable. This relation is, most probably, not only spatial, but

  9. Origin of an unusual monazite-xenotime gneiss, Hudson Highlands, New York: SHRIMP U-Pb geochronology and trace element geochemistry

    Science.gov (United States)

    Aleinikoff, John N.; Grauch, Richard I.; Mazdab, Frank K.; Kwak, Loretta; Fanning, C. Mark; Kamo, Sandra L.

    2012-01-01

    A pod of monazite-xenotime gneiss (MXG) occurs within Mesoproterozoic paragneiss, Hudson Highlands, New York. This outcrop also contains granite of the Crystal Lake pluton, which migmatized the paragneiss. Previously, monazite, xenotime, and zircon from MXG, plus detrital zircon from the paragneiss, and igneous zircon from the granite, were dated using multi-grain thermal ionization mass spectrometry (TIMS). New SEM imagery of dated samples reveals that all minerals contain cores and rims. Thus TIMS analyses comprise mixtures of age components and are geologically meaningless. New spot analyses by sensitive high resolution ion microprobe (SHRIMP) of small homogeneous areas on individual grains allows deconvolution of ages within complexly zoned grains. Xenotime cores from MXG formed during two episodes (1034 ± 10 and 1014 ± 3 Ma), whereas three episodes of rim formation are recorded (999 ± 7, 961 ± 11, and 874 ± 11 Ma). Monazite cores from MXG mostly formed at 1004 ± 4 Ma; rims formed at 994 ± 4, 913 ± 7, and 890 ± 7 Ma. Zircon from MXG is composed of oscillatory-zoned detrital cores (2000-1170 Ma), plus metamorphic rims (1008 ± 7, 985 ± 5, and ∼950 Ma). In addition, MXG contains an unusual zircon population composed of irregularly-zoned elongate cores dated at 1036 ± 5 Ma, considered to be the time of formation of MXG. The time of granite emplacement is dated by oscillatory-zoned igneous cores at 1058 ± 4 Ma, which provides a minimum age constraint for the time of deposition of the paragneiss. Selected trace elements, including all REE plus U and Th, provide geochemical evidence for the origin of MXG. MREE-enriched xenotime from MXG are dissimilar from typical HREE-enriched patterns of igneous xenotime. The presence of large negative Eu anomalies and high U and Th in monazite and xenotime are uncharacteristic of typical ore-forming hydrothermal processes. We conclude that MXG is the result of unusual metasomatic processes during high grade

  10. PREVALENCE OF METABOLIC SYNDROME IN GRANITE WORKERS

    Directory of Open Access Journals (Sweden)

    Srilakshmi

    2015-10-01

    Full Text Available BACKGROUND: The prevalence of the metabolic syndrome (MS has significantly increased over the last few decades and has become a main health challenge worldwide. Prevalence of MS is quickly rising in developing countries due to changing lifestyle. It was considered worthwhile to study MS and its components in granite workers since granite factories are situated in and around Khammam area. Moreover, no studies of MS in granite workers have been reported in literature. OBJECTIVES: Aim of our study is to assess the prevalence of metabolic syndrome and its components in granite workers. MATERIALS AND METHODS: 210 male workers in the age group of 20 - 50 working in granite industries located in and around the Khammam town of Telangana State are selected for the present study. Blood pressures (BP, waist circumference (WC were measured. Fasting blood samples were collected for the estimation of glucose and lipids. RESULTS: 69 subjects out of 210 were identified as having MS based on updated National cholesterol education programme - Adult Treatment Panel III (NCEP - ATP III guidelines. CONCLUSION: MS should be identified and remedial measures may be suggested, so that the risk of hypertension, cardiovascular risk, diabetes and the resultant morbidity is minimized and can be delayed

  11. Syn-orogenic high-temperature crustal melting: Geochronological and Nd-Sr-Pb isotope constraints from basement-derived granites (Central Damara Orogen, Namibia)

    Science.gov (United States)

    Ostendorf, Jörg; Jung, Stefan; Berndt-Gerdes, Jasper; Hauff, Folkmar

    2014-04-01

    Major and trace element and Nd, Sr and Pb isotope data from c. 550 Ma-old gray granites and c. 510 Ma-old red leucogranites of the high-grade central part of the Damara orogen (Namibia) indicate a dominantly deep crustal origin. Moderately peraluminous gray granites are isotopically evolved (initial ɛNd: c. - 17) and were likely derived from meta-igneous sources with late Archean to Paleoproterozoic crustal residence ages. Based on a comparison with experimental results, the granites were derived by partial melting of a granodioritic biotite gneiss at c. 900-950 °C and less than 10 kbar. Slightly peraluminous red leucogranites are also isotopically evolved (initial ɛNd: - 15 to - 18) but have undergone extensive crystal fractionation coupled with minor contamination of mid crustal meta-pelitic material. Major and trace element data do not support closed-system fractional crystallization processes for all samples, however, some chemical features underline the importance of crystal fractionation processes especially for the leucogranites. Isotope data do not support mixing of different crust-derived melts or assimilation of crustal rocks by a mafic magma on a large scale. For the gray granites, unradiogenic Pb isotope compositions with substantial variation in 207Pb/204Pb at almost constant 206Pb/204Pb, strongly negative ɛNd values and moderately radiogenic Sr isotope compositions argue for an undepleted nature of the source. High Rb/Sr ratios of the red leucogranites permit a comparison with the gray granites but similar initial ɛNd values indicate that the source of these granites is not fundamentally different to the source of the gray granites. The most acceptable model for both granite types involves partial melting of meta-igneous basement rocks of Archean to Proterozoic age. The consistency of the chemical data with a crustal anatectic origin and the observation that the gray granites intruded before the first peak of high-grade regional metamorphism

  12. Geologic map of the Granite 7.5' quadrangle, Lake and Chaffee Counties, Colorado

    Science.gov (United States)

    Shroba, Ralph R.; Kellogg, Karl S.; Brandt, Theodore R.

    2014-01-01

    The geologic map of the Granite 7.5' quadrangle, Lake and Chaffee Counties, Colorado, portrays the geology in the upper Arkansas valley and along the lower flanks of the Sawatch Range and Mosquito Range near the town of Granite. The oldest rocks, exposed in the southern and eastern parts of the quadrangle, include gneiss and plutonic rocks of Paleoproterozoic age. These rocks are intruded by younger plutonic rocks of Mesoproterozoic age. Felsic hypabyssal dikes, plugs, and plutons, ranging in age from Late Cretaceous or Paleocene to late Oligocene, locally intruded Proterozoic rocks. A small andesite lava flow of upper Oligocene age overlies Paleoproterozoic rock, just south of the Twin Lakes Reservoir. Gravelly fluvial and fan deposits of the Miocene and lower Pliocene(?) Dry Union Formation are preserved in the post-30 Ma upper Arkansas valley graben, a northern extension of the Rio Grande rift. Mostly north-northwest-trending faults displace deposits of the Dry Union Formation and older rock units. Light detection and ranging (lidar) imagery suggests that two short faults, near the Arkansas River, may displace surficial deposits as young as middle Pleistocene. Surficial deposits of middle Pleistocene to Holocene age are widespread in the Granite quadrangle, particularly in the major valleys and on slopes underlain by the Dry Union Formation. The main deposits are glacial outwash and post-glacial alluvium; mass-movement deposits transported by creep, debris flow, landsliding, and rockfall; till deposited during the Pinedale, Bull Lake, and pre-Bull Lake glaciations; rock-glacier deposits; and placer-tailings deposits formed by hydraulic mining and other mining methods used to concentrate native gold. Hydrologic and geologic processes locally affect use of the land and locally may be of concern regarding the stability of buildings and infrastructure, chiefly in low-lying areas along and near stream channels and locally in areas of moderate to steep slopes. Low

  13. Thermometers and thermobarometers in granitic systems

    Science.gov (United States)

    Anderson, J.L.; Barth, A.P.; Wooden, J.L.; Mazdab, F.; ,

    2008-01-01

    The ability to determine the thermal and barometric history during crystallization and emplacement of granitic plutons has been enhanced by several new calibrations applicable to granitic mineral assemblages. Other existing calibrations for granitic plutons have continued to be popular and fairly robust. Recent advances include the trace element thermometers Ti-in-quartz, Ti-in-zircon, and Zr-in-sphene (titanite), which need to be further evaluated on the roles of reduced activities due to lack of a saturating phase, the effect of pressure dependence (particularly for the Ti-in-zircon thermometer), and how resistive these thermometers are to subsolidus reequilibration. As zircon and sphene are also hosts to radiogenic isotopes, these minerals potentially also provide new insights into the temperature - time history of magmas. When used in conjunction with pressure-sensitive mineral equilibria in the same rocks, a complete assessment of the P-T-t (pressure-temperature-time) path is possible given that the mineralogy of plutons can reflect crystallization over a range of pressure and temperature during ascent and emplacement and that many intrusions are now seen as forming over several millions of years during the protracted history of batholith construction. Accessory mineral saturation thermometers, such as those for zircon, apatite, and allanite, provide a different and powerful perspective, specifically that of the temperature of the onset of crystallization of these minerals, which can allow an estimate of the range of temperature between the liquidus and solidus of a given pluton. In assessment of the depth of crystallization and emplacement of granitic plutons, the Al-in-hornblende remains popular for metaluminous granites when appropriately corrected for temperature. For peraluminous granites, potential new calibrations exist for the assemblages bearing garnet, biotite, plagioclase, muscovite, and quartz. Other thermometers, based on oxygen abundance, and

  14. Gamma radiation measurements in Brazilian commercial granites

    Energy Technology Data Exchange (ETDEWEB)

    Anjos, R.M.; Veiga, R.; Mosquera, B.; Carvalho, C.; Macario, K. [Universidade Federal Fluminense, Niteroi (Brazil)

    2006-07-01

    Full text of publication follows: Gamma radiation from radionuclides which are characterized by half lives comparable to the age of the earth, such as 40 K and the radionuclides from the 238 U and 232 Th series, and their decay products, represent the main terrestrial source of irradiation to the human body. Their concentrations vary for different types of rocks, where high radiation levels are associated with igneous rocks such as granite. Thorium, uranium and potassium concentrations of granitic rocks are intimately related to their mineral compositions and general petrologic features. Then, these features associated with effects of weathering and metamorphism produce expressive alterations in the relationship between the natural radionuclides (Th, U, K, Th/U and Th/K). Consequently, the measurements of thorium, uranium, and potassium concentrations of different granite samples result on individual differentiation sequences. From the 232 Th, 238 U and 40 K activity concentrations obtained for each sample, it is possible to evaluate their respective dose rates in air, when these stones are used as tiling rocks. These results are of great interest in the environmental radiological protection study, since granites are widely used as building and ornamental materials, including as indoor covering. In this way, the Laboratory of Radioecology (L.A.R.A.) of the Physics Institute of the Universidade Federal Fluminense (I.F. -U.F.F.) has been performing analyzes on more than one hundred differ ent types of the main Brazilian commercial granites in last two years [1]. Using NaI and HP Ge gamma-ray spectrometers to determine the concentration of natural radionuclides in these samples, the annual effective dose rates and the gamma activity concentration index have been evaluated and compared to the limits proposed by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and European Commission (E.C.). In addition, the correlations between thorium

  15. Petrography, mineral chemistry and lithochemistry of the albitite and granite-gneissics rocks of anomaly 35 from Lagoa Real uranium province; Petrografia, quimica mineral e litoquimica do albitito e das rochas granito-gnaissicas da anomalia 35, provincia uranifera de Lagoa Real

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Camila Marques dos

    2016-07-01

    In the northwestern portion of the Lagoa Real Uranium Province (LRUP), located in south-central Bahia, it is located one of the most promising uranium anomalies Brazil (an35, Gameleira I deposit), the reserves and proximity to the Cachoeira mine. Other anomalies of this sector (eg. 31 AN and AN34), are also considered strategic for the content of radioactive minerals and REE. The objective was to develop a study of a representative drill core of an35, where the main rocks PULR are present. The research focused on the mineralogical and chemical changes observed in the passages of a lithology to another, from the rock to the meta granitic albitites, through gneiss and transitional rocks, and making comparisons with similar lithologies sampled on testimonies of AN31 and 34. The granites are classified as hypersolvus coarse alkali-feldspar granite and are variably deformed. The main mineral assemblage in granites are perthitic orthoclase+hedenbergite+ quartz +hastingsite + biotite, and zircon, apatite, ilmenite and titanite are accessories. The reddening of these rocks are characterized by feldspars sericitization and hematitization and the presence of 'vazios'. The gneisses are mainly gray and reach milonitic to protomilonitics terms. These rocks have characteristics of subsolidus changes as swapped rims and metasomatic perthites. The tardi-magmatic association (amphibole+biotite) indicates final crystallization or late influx by superficial fluids resulting in an increase in water and volatiles, such as F and Cl in the system, which must also have carried rare-earth elementsGranites have geochemical affinity with A-type ferroan granite, A2, reduced and are post-collisional. Their patterns of incompatible elements and rare earths are comparable to Sao Timoteo Granite, but their petrographic features indicate that it is a less common granite facies. Albitites were classified as garnet albitites, magnetite albitites and biotite albitites. Contacts between

  16. Geochemistry of the granitic rocks from the Kwandonkaya Complex, northern Nigeria

    Science.gov (United States)

    Imeokparia, E. G.

    The Kwandonkaya Complex forms one of the most prominent and typical ring structures in the Centre of Jos, Plateau State, Nigeria. Lithologically, it is composed of amphibole and biotite granites emplaced within Archean basement gneisses and migmatites. The chemical and mineralogical characteristics of this complex suggest that it was derived from crustal source materials. Trace elements are high in Rb, Li, F, Sn, Nb, W and low in Sr and Ba compared to the world average for rocks of similar composition indicating a high degree of fractionation. However, the {K}/{Rb} ratios and petrographic evidence indicate that recrystallization may have redistributed the elements after the initial solidification of the rocks particularly in the biotite granites; and that the distribution of tin may have been initially controlled by crystal-silicate melt equilibra. Tin probably preferentially entered the aqueous phase during the late stages of solidification. It was the interaction between this phase and early formed minerals that led to greisenization and tin-tungsten mineralization. Although total rock chemical composition show no marked trends the composition of the biotites and hornblende define a trend in the compositional triangle Fe 3+Fe 2+Mg. When the biotites are related to the experimentally studied ternary system KFe 33+AlSi 3O 12(H-1)KFe 32+AlSi 3O 10(OH) 2KMg 3AlSi 3O 10(OH) 2 and coupled with the estimated position of biotite solid solutions for different oxygen buffers, the trend suggests that oxygen fugacities in the magmas during biotite formation were slightly higher than those defined by the Fe 2SiO 4SiO 2Fe 3O 4 buffer. The ratio of ferric to ferrous iron in pairs of the minerals from the Kwandonkaya Complex is the same for both hornblende and biotite and suggests crystallization in a closed but buffered environment.

  17. Fractal patterns of fractures in granites

    Science.gov (United States)

    Velde, B.; Dubois, J.; Moore, D.; Touchard, G.

    1991-01-01

    Fractal measurements using the Cantor's dust method in a linear one-dimensional analysis mode were made on the fracture patterns revealed on two-dimensional, planar surfaces in four granites. This method allows one to conclude that: 1. (1)|The fracture systems seen on two-dimensional surfaces in granites are consistent with the part of fractal theory that predicts a repetition of patterns on different scales of observation, self similarity. Fractal analysis gives essentially the same values of D on the scale of kilometres, metres and centimetres (five orders of magnitude) using mapped, surface fracture patterns in a Sierra Nevada granite batholith (Mt. Abbot quadrangle, Calif.). 2. (2)|Fractures show the same fractal values at different depths in a given batholith. Mapped fractures (main stage ore veins) at three mining levels (over a 700 m depth interval) of the Boulder batholith, Butte, Mont. show the same fractal values although the fracture disposition appears to be different at different levels. 3. (3)|Different sets of fracture planes in a granite batholith, Central France, and in experimental deformation can have different fractal values. In these examples shear and tension modes have the same fractal values while compressional fractures follow a different fractal mode of failure. The composite fracture patterns are also fractal but with a different, median, fractal value compared to the individual values for the fracture plane sets. These observations indicate that the fractal method can possibly be used to distinguish fractures of different origins in a complex system. It is concluded that granites fracture in a fractal manner which can be followed at many scales. It appears that fracture planes of different origins can be characterized using linear fractal analysis. ?? 1991.

  18. Geodynamic evolution and crustal growth of the central Indian Shield: Evidence from geochemistry of gneisses and granitoids

    Indian Academy of Sciences (India)

    M Faruque Hussain; M E A Mondal; Talat Ahmad

    2004-12-01

    The rare earth element patterns of the gneisses of Bastar and Bundelkhand are marked by LREE enrichment and HREE depletion with or without Eu anomaly. The spidergram patterns for the gneisses are characterized by marked enrichment in LILE with negative anomalies for Ba, P and Ti. The geochemical characteristics exhibited by the gneisses are generally interpreted as melts generated by partial melting of a subducting slab. The style of subduction was flat subduction, which was most common in the Archean. The rare earth patterns and the multi-element diagrams with marked enrichment in LILE and negative anomalies for Ba, P and Ti of the granitoids of both the cratons indicate interaction between slab derived melts and the mantle wedge. The subduction angle was high in the Proterozoic. Considering the age of emplacement of the gneisses and granitoids that differs by ∼ 1 Ga, it can be assumed that these are linked to two independent subduction events: one during Archaean (flat subduction) that generated the precursor melts for the gneisses and the other during the Proterozoic (high angle subduction) that produced the melts for the granitoids. The high values of Mg#, Ni, Cr, Sr and low values of SiO2 in the granitoids of Bastar and Bundelkhand cratons compared to the gneisses of both the cratons indicate melt-mantle interaction in the generation of the granitoids. The low values of Mg#, Ni, Cr, Sr and high values of SiO2 in the gneisses in turn overrules such melt-mantle interaction.

  19. Hydrothermal alteration of Hercynian granites, its significance to the evolution of geothermal systems in granitic rocks

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Jose M.; Matias, Maria J.; Basto, Maria J.; Aires-Barros, Luis A. [Instituto Superior Tecnico, Centro de Petrologia e Geoquimica, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Carreira, Paula M. [Instituto Tecnologico e Nuclear, Estrada Nacional n 10, 2686 - 953 Sacavem (Portugal); Goff, Fraser E. [Earth and Planetary Sciences Department, Univ. of New Mexico, Albuquerque, NM 87131 (United States)

    2010-06-15

    We discuss geochemical and isotopic ({sup 18}O/{sup 16}O, {sup 2}H/{sup 1}H and {sup 87}Sr/{sup 86}Sr) data recording the hydrothermal alteration of northern Portuguese Hercynian granites by Na-HCO{sub 3}-CO{sub 2}-rich mineral waters. Whole-rock samples from drill cores of Vilarelho da Raia granite have {delta}{sup 18}O values in the +11.47 to +10.10 permille range. The lower values correspond to highly fractured granite samples displaying vein and pervasive alteration. In the pervasive alteration stage, which probably results from a convective hydrothermal system set up by the intrusion of the granites, the metamorphic waters are in equilibrium with hydrous minerals. In contrast, the vein alteration of these granitic rocks was caused by water of meteoric origin. The oxygen ratios between water (W) and rock (R), the so-called W/R ratios, obtained for the open system (where the heated water is lost from the system by escape to the surface) range between 0.05 and 0.11, suggesting that the recrystallization of the veins was influenced by a small flux of meteoric water. Stable isotope analyses performed on the cores show that the vein alteration stage relates to post-emplacement tectonic stresses acting on the granite, probably of late Hercynian age. Our results are consistent with the existence of two separate alteration events (pervasive and vein) caused by hydrothermal waters of different isotopic characteristics. The studies presented in this paper should be viewed as a natural analogue that uses the alteration features observed in a fossil geothermal system at Vilarelho da Raia to assess possible water-rock reactions presently occurring at depth in granitic rocks of the nearby Chaves area. (author)

  20. Petrology of dioritic, tonalitic and trondhjemitic gneisses from Encantadas Complex, Santana da Boa Vista, southernmost Brazil: paleoproterozoic continental-arc magmatism

    Directory of Open Access Journals (Sweden)

    Ruy P. Philipp

    2008-12-01

    Full Text Available The Encantadas Complex is a unit composed of dioritic, tonalitic and trondhjemitic gneisses with minor hornblendite. This complex is intruded by granites of Neoproterozoic age. Major and trace element data indicate metaluminous to slightly peraluminous composition related to the medium-K calc-alkaline series. Compositional parameters are consistent with a common evolution from less differentiated magmas, probably through fractional crystallization. The orthogneisses show LaN/YbN ratios from 10 to 50, K2O/Na2O varying from 1.1 to 3.0, Y contents from 3 to 39 ppm, Yb from 0.3 to 3.7, and Lu with contents in the range 0.06 and 0.54 ppm. Such geochemical features are similar to those of Archaean tonalitic rocks and are usually described in rocks formed by partial melting of mafic rocks under high-pressure conditions leaving an eclogitic residue. The presence of diorites and hornblendites, associated to tonalitic and trondhjemitic gneisses suggests, on the other hand, that tonalitic magmas could be formed by hornblende-controlled fractionation of hydrous basaltic magmas. Tonalitic gneisses show U-PbSHRIMP zircon age of 2, 263 ± 6 Ma for igneous crystallization and 2, 045 ± 10 Ma for the metamorphism. The geochemical parameters, tectonic and geochronological features of Encantadas Complex are consistent with magmas derived from mantle metasomatized by subduction-related fluids in a continental-arc.O Complexo Encantadas é constituído por gnaisses tonalíticos, trondhjemíticos e dioríticos com presença subordinada de hornblenditos. Os elementos maiores e traços indicam uma composição metaluminosa a fracamente peraluminosa relacionada às séries cálcico-alcalinas médio-K. Os parâmetros composicionais são consistentes com uma evolução associada provavelmente a cristalização fracionada a partir de magmas menos diferenciados. Os ortognaisses mostram razões LaN/YbN variando entre 10 até 50, K2O/ Na2O entre 1,1 e 3,0, com conteúdos de Y

  1. Summary report - development of laboratory tests and the stress- strain behaviour of Olkiluoto mica gneiss

    Energy Technology Data Exchange (ETDEWEB)

    Hakala, M.; Heikkilae, E. [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Rock Engineering

    1997-05-01

    This work summarizes the project aimed at developing and qualifying a suitable combination of laboratory tests to establish a statistically reliable stress-strain behaviour of the main rock types at Posiva Oy`s detailed investigation sites for disposal of spent nuclear fuel. The work includes literature study of stress-strain behaviour of brittle rock, development and qualification of laboratory tests, suggested test procedures and interpretation methods and finally testing of Olkiluoto mica gneiss. The Olkiluoto study includes over 130 loading tests. Besides the commonly used laboratory tests, direct tensile tests, damage controlled tests and acoustic emission measurements were also carried out. (orig.) (54 refs.).

  2. Simulation of a true-triaxial deformation test on anisotropic gneiss using FLAC3D

    Science.gov (United States)

    Ye, Shenghua; Sehizadeh, Mehdi; Nasseri, Mohammad; Young, Paul

    2016-04-01

    A series of true-triaxial experiments have been carried out at the University of Toronto's Rock Fracture Dynamics Laboratory. Isotropic pegmatite and gneiss have been used to systematically study the effect of anisotropy on the strength, behaviour and seismic response. Samples were loaded under true-triaxial stress conditions and subjected to complex loading and unloading histories associated with rock deformation around underground openings. The results show expected patterns of weakness from preferentially oriented samples and highlight the importance of unloading history under true-triaxial conditions on the deformation and seismic response of the samples. These tests have been used to validate a synthetic simulation using the Itasca FLAC3D numerical code. The paper describes the FLAC3D simulations of the complex true-triaxial loading and unloading history of the different anisotropic samples. Various parameters were created to describe the physico-mechanical properties of the synthetic rock samples. Foliation planes of preferential orientations with respect to the primary loading direction were added to the synthetic rock samples to reflect the anisotropy of the gneiss. These synthetic rock samples were subjected to the same loading and unloading paths as the real rock samples, and failed in the same mechanism as what was observed from the experiments, and thus it proved the validity of this numerical simulation with FLAC3D.

  3. Petrogenesis and tectonic implications of the Neoarchean North Liaoning tonalitic-trondhjemitic gneisses of the North China Craton, North China

    Science.gov (United States)

    Wang, Maojiang; Liu, Shuwen; Wang, Wei; Wang, Kang; Yan, Ming; Guo, Boran; Bai, Xiang; Guo, Rongrong

    2016-12-01

    Tonalitic-trondhjemitic-granodioritic (TTG) gneisses are dominant lithological assemblages in Archean high grade metamorphic terranes in the world. These TTG gneisses preserve important information in formation and evolution of Archean continental crust. Tangtu-Majuanzi microblock in North Liaoning Province (NLP) is one of the major Neoarchean metamorphic basement terranes in the northeastern margin of the North China Craton (NCC). The Tangtu-Majuanzi microblock is composed mainly of Neoarchean tonalitic-trondhjemitic (TT) gneisses, subordinate granodioritic to monzogranitic association (GMA) and minor supracrustal rocks. The tonalitic-trondhjemitic gneisses are divided into high MgO Group (HMG) and low MgO Group (LMG) based on their chemical compositions. Detailed petrogenetic investigations suggest that the magmatic precursors of the HMG samples were derived from partial melting of subducted slabs and contaminated by the overlying mantle wedge during its ascent; whereas, magmatic precursors of the LMG samples were derived from the juvenile lower crust. LA-ICPMS zircon U-Pb isotopic dating analyses reveal that the magmatic precursors of the HMG samples were formed at 2553-2531 Ma. An older HMG tonalitic gneiss sample was discovered at Sandaoguan in the southmost of the studied area, with its magmatic precursor emplaced at 2680 Ma. The magmatic precursors of the LMG samples emplaced at 2595-2583 Ma. Combined with previous credible chronological data, our newly obtained zircon U-Pb dating and Lu-Hf isotopic data indicate that three episodes of magmatism at ∼2700-2680 Ma, ∼2600-2570 Ma and ∼2550-2510 Ma occurred in the Tangtu-Majuanzi microblock, and the TT gneisses in this microblock were subjected to generally amphibolite-facies metamorphism at ∼2520-2470 Ma. Based on the above Neoarchean crust-mantle thermal-dynamic processes, we propose that the Neoarchean magmatism and metamorphism in the Tangtu-Majuanzi microblock of North Liaoning Province occurred in

  4. Preface to special issue: Granite magmatism in Brazil

    Science.gov (United States)

    Janasi, Valdecir de Assis; de Pinho Guimarães, Ignez; Nardi, Lauro Valentim Stoll

    2016-07-01

    Granites are important both to the geologic evolution and to the economy of Brazil. Deposits of precious and rare metals, such as Au, Sn and many others, are directly or indirectly associated with granites, especially in the geologically under-explored Amazon region. On the opposite eastern side of the country, expanding exploitation of natural granite as dimension stone makes Brazil currently the world's second largest exporter of granite blocks. Granites are a major constituent of the Brazilian Archean-Proterozoic cratonic domains (the Amazon and São Francisco cratons) and their surrounding Neoproterozoic fold belts. The granites are thus fundamental markers of the major events of crustal generation and recycling that shaped the South American Platform. As a result, Brazilian granites have received great attention from the national and international community, and a number of influential meetings focused on the study of granites were held in the country in the last three decades. These meetings include the two International Symposia on Granites and Associated Mineralization (Salvador, January 21-31, 1987, and August 24-29, 1997), the Symposium on Rapakivi Granites and Related Rocks (Belém, August 2-5, 1995) and the Symposium on Magmatism, Crustal Evolution, and Metallogenesis of the Amazonian Craton (Belém, August 2006). Special issues dedicated to contributions presented at these meetings in the Journal of South American Earth Sciences (Sial et al., 1998), Lithos (Stephens et al., 1999), Canadian Mineralogist (Dall'Agnol and Ramo, 2006), Precambrian Research (Ramo et al., 2002) and Anais da Academia Brasileira de Ciências (Dall'Agnol and Bettencourt, 1997; Sial et al., 1999a) are still important references on the knowledge of Brazilian granites and granite petrology in general.

  5. Rare Earths of Two Types Granites in Sawuer Region, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    Yuan Feng; Zhou Taofa; Tan Lugui; Fan Yu; Yue Shucang

    2005-01-01

    The geochemical characteristics of rare earth elements of A type and I type granites were studied in the Sawuer region, Xinjiang. The characteristics of two types granites are different obviously,because the A type and I type granites formed at different stage of the post-collisional period. The Sentasi intrusion and Wokensala intrusion are the I type granites formed at the late of post-collisional period, and there is extrusion translating to extension stress. The characteristics of rare earth elements show that the fractional crystallization of the I type granites is indistinct, and the sources of the I type granites come from the mantle. The Kuoyitasi intrusion and Qiaqihai intrusion are the A type granites formed at the end of post-collisional period, and there is extension stress. The characteristics of rare earth elements show that the fractional crystallization of the A type granites is distinct. The sources of the A type granites come from the mantle but interfused by the crust.

  6. Portuguese granites associated with Sn-W and Au mineralizations

    Directory of Open Access Journals (Sweden)

    Ana M.R. Neiva

    2002-01-01

    Full Text Available In northern and central Portugal, there are different tin-bearing granites. Most of them are of S-type, others have mixed characteristics of I-type and S-type granites and a few are of I-type. Tin-tungsten deposits are commonly associated with Hercynian tin-bearing S-type granites. Some quartz veins with wolframite are associated with an I-type granite, which has a low Sn content. In suites of tin-bearing S-type granitic rocks, Sn content increases as a function of the degree of fractional crystallization. Greisenizations of two-mica S-type granites associated with tin-tungsten mineralizations are accompanied by an increase in SiO2, H2O+, Sn, W, Nb, Ta, Rb, Zn, and Pb and decrease in MgO, Na2O, V, Sc,Zr, and Sr. The granite associated with the Jales gold deposit is of S-type and strongly differentiated like the tin-bearing S-type granites, but it has a very low Sn content. During fractional crystallization, Si, Rb, Sn, Pb, Au, As, Sb, and S increase. During increasing degree of hydrothermal alteration of this granite at the gold-quartz vein walls, there are progressive increases in K2O, H2O+, Sn, Cs, Cu, Pb, Au, Sb, As, and S.

  7. Zircon SHRIMP dating of granite from Qaidamshan,NW China

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Zircon SHRIMP dating from Qaidamshan granite shows that the granite age is 446 Ma, similar to that of eclogite in the UHP belt. We think that both granite and eclogite may be formed at different stages during tectonic evolution of this area. Together with other studies we suggested that the collision of ocean and continent plates may occur at the early Caledonian in this area, forming the eclogite, and the collision of continent and continent plates at the late Caledonian, forming the Qaidamshan granite with the zircon SHRIMP age of 446 Ma.

  8. Characterization of Climax granite ground water

    Energy Technology Data Exchange (ETDEWEB)

    Isherwood, D.; Harrar, J.; Raber, E.

    1982-08-01

    The Climax ground water fails to match the commonly held views regarding the nature of deep granitic ground waters. It is neither dilute nor in equilibrium with the granite. Ground-water samples were taken for chemical analysis from five sites in the fractured Climax granite at the Nevada Test Site. The waters are high in total dissolved solids (1200 to 2160 mg/L) and rich in sodium (56 to 250 mg/L), calcium (114 to 283 mg/L) and sulfate (325 to 1060 mg/L). Two of the samples contained relatively high amounts of uranium (1.8 and 18.5 mg/L), whereas the other three contained uranium below the level of detection (< 0.1 mg/L). The pH is in the neutral range (7.3 to 8.2). The differences in composition between samples (as seen in the wide range of values for the major constituents and total dissolved solids) suggest the samples came from different, independent fracture systems. However, the apparent trend of increasing sodium with depth at the expense of calcium and magnesium suggests a common evolutionary chemical process, if not an interconnected system. The waters appear to be less oxidizing with depth (+ 410 mV at 420 m below the surface vs + 86 mV at 565 m). However, with Eh measurements on only two samples, this correlation is questionable. Isotopic analyses show that the waters are of meteoric origin and that the source of the sulfate is probably the pyrite in the fracture-fill material. Analysis of the measured water characteristics using the chemical equilibrium computer program EQ3 indicates that the waters are not in equilibrium with the local mineral assemblage. The solutions appear to be supersaturated with respect to the mineral calcite, quartz, kaolinite, muscovite, k-feldspar, and many others.

  9. Multivariate analyses of Erzgebirge granite and rhyolite composition: implications for classification of granites and their genetic relations

    Science.gov (United States)

    Förster, Hans-Jürgen; Davis, John C.; Tischendorf, Gerhard; Seltmann, Reimar

    1999-06-01

    High-precision major, minor and trace element analyses for 44 elements have been made of 329 Late Variscan granitic and rhyolitic rocks from the Erzgebirge metallogenic province of Germany. The intrusive histories of some of these granites are not completely understood and exposures of rock are not adequate to resolve relationships between what apparently are different plutons. Therefore, it is necessary to turn to chemical analyses to decipher the evolution of the plutons and their relationships. A new classification of Erzgebirge plutons into five major groups of granites, based on petrologic interpretations of geochemical and mineralogical relationships (low-F biotite granites; low-F two-mica granites; high-F, high-P 2O 5 Li-mica granites; high-F, low-P 2O 5 Li-mica granites; high-F, low-P 2O 5 biotite granites) was tested by multivariate techniques. Canonical analyses of major elements, minor elements, trace elements and ratio variables all distinguish the groups with differing amounts of success. Univariate ANOVA's, in combination with forward-stepwise and backward-elimination canonical analyses, were used to select ten variables which were most effective in distinguishing groups. In a biplot, groups form distinct clusters roughly arranged along a quadratic path. Within groups, individual plutons tend to be arranged in patterns possibly reflecting granitic evolution. Canonical functions were used to classify samples of rhyolites of unknown association into the five groups. Another canonical analysis was based on ten elements traditionally used in petrology and which were important in the new classification of granites. Their biplot pattern is similar to that from statistically chosen variables but less effective at distinguishing the five groups of granites. This study shows that multivariate statistical techniques can provide significant insight into problems of granitic petrogenesis and may be superior to conventional procedures for petrological

  10. Multivariate analyses of Erzgebirge granite and rhyolite composition: Implications for classification of granites and their genetic relations

    Science.gov (United States)

    Forster, H.-J.; Davis, J.C.; Tischendorf, G.; Seltmann, R.

    1999-01-01

    High-precision major, minor and trace element analyses for 44 elements have been made of 329 Late Variscan granitic and rhyolitic rocks from the Erzgebirge metallogenic province of Germany. The intrusive histories of some of these granites are not completely understood and exposures of rock are not adequate to resolve relationships between what apparently are different plutons. Therefore, it is necessary to turn to chemical analyses to decipher the evolution of the plutons and their relationships. A new classification of Erzgebirge plutons into five major groups of granites, based on petrologic interpretations of geochemical and mineralogical relationships (low-F biotite granites; low-F two-mica granites; high-F, high-P2O5 Li-mica granites; high-F, low-P2O5 Li-mica granites; high-F, low-P2O5 biotite granites) was tested by multivariate techniques. Canonical analyses of major elements, minor elements, trace elements and ratio variables all distinguish the groups with differing amounts of success. Univariate ANOVA's, in combination with forward-stepwise and backward-elimination canonical analyses, were used to select ten variables which were most effective in distinguishing groups. In a biplot, groups form distinct clusters roughly arranged along a quadratic path. Within groups, individual plutons tend to be arranged in patterns possibly reflecting granitic evolution. Canonical functions were used to classify samples of rhyolites of unknown association into the five groups. Another canonical analysis was based on ten elements traditionally used in petrology and which were important in the new classification of granites. Their biplot pattern is similar to that from statistically chosen variables but less effective at distinguishing the five groups of granites. This study shows that multivariate statistical techniques can provide significant insight into problems of granitic petrogenesis and may be superior to conventional procedures for petrological interpretation.

  11. Oxygen Isotope Study of the Suzhou Granite

    Institute of Scientific and Technical Information of China (English)

    王汝成; 沈渭洲; 等

    1998-01-01

    Oxygen isotope studies of the Suzhou granite have been made based on drill-hole samples.In the inner part,the δ18 O values are less variable either in the whole-rock,quartz or in feldspar.Oxygen isotopic compositions are in equilibrium between coexisting quartz and feldspar.Data points from the inner part are plotted in a small area in the δ18 OQ-δ18Of diagram,indicating that this part has not been affected by meteoric hydrothermal fluids.But the whole-rock δ18 O values of the marginal part vary greatly.Oxygen isotopic compositions are in extreme disequilibrium between quartz and feldspar.Data points from the marginal part are displayed with a nearly vertical slope in the δ18OQ-δ18 Of diagram,implying that rocks of this part are affected by the meteoric hydrothermal fluids.Extreme water-rock interactions lead to mineralizations of rare-elements(Nb,Ta,as well as Zr,Hf,Th)in the marginal part.Source materials of the Suzhou granite are also discussed in this paper.

  12. Evidence for an Early Archean component in the Middle to Late Archean gneisses of the Wind River Range, west-central Wyoming: conventional and ion microprobe U-Pb data

    Science.gov (United States)

    Aleinikoff, J.N.; Williams, I.S.; Compston, W.; Stuckless, J.S.; Worl, R.G.

    1989-01-01

    Gneissic rocks that are basement to the Late Archean granites comprising much of the Wind River Range, west-central Wyoming, have been dated by the zircon U-Pb method using both conventional and ion microprobe techniques. A foliated hornblende granite gneiss member from the southern border of the Bridger batholith is 2670??13 Ma. Zircons from a granulite just north of the Bridger batholith are equant and faceted, a typical morphology for zircon grown under high grade metamorphic conditions. This granulite, which may be related to a second phase of migmatization in the area, is 2698??8 Ma. South of the Bridger batholith, zircons from a granulite (charnockite), which is related to an earlier phase of migmatization in the Range, yield a discordia with intercept ages of about 2.3 and 3.3 Ga. However, ion microprobe analyses of single zircon grains indicate that this rock contains several populations of zircon, ranging in age from 2.67 to about 3.8 Ga. Based on zircon morphology and regional geologic relationships, we interpret the data as indicating an age of ???3.2 Ga for the first granulite metamorphism and migmatization. Older, possibly xenocrystic zircons give ages of ???3.35, 3.65 and ???3.8 Ga. Younger zircons grew at 2.7 and 2.85 Ga in response to events, including the second granulite metamorphism at 2.7 Ga, that culminated in the intrusion of the Bridger batholith and migmatization at 2.67 Ga. These data support the field and petrographic evidence for two granulite events and provide some temporal constraints for the formation of continental crust in the Early and Middle Archean in the Wyoming Province. ?? 1989 Springer-Verlag.

  13. Effectiveness of granite cleaning procedures in cultural heritage: A review.

    Science.gov (United States)

    Pozo-Antonio, J S; Rivas, T; López, A J; Fiorucci, M P; Ramil, A

    2016-11-15

    Most of the Cultural Heritage built in NW Iberian Peninsula is made of granite which exposition to the environment leads to the formation of deposits and coatings, mainly two types: biological colonization and sulphated black crusts. Nowadays, another form of alteration derives from graffiti paints when these are applied as an act of vandalism. A deep revision needs to be addressed considering the severity of these deterioration forms on granite and the different cleaning effectiveness achieved by cleaning procedures used to remove them. The scientific literature about these topics on granite is scarcer than on sedimentary carbonate stones and marbles, but the importance of the granite in NW Iberian Peninsula Cultural Heritage claims this review centred on biological colonization, sulphated black crusts and graffiti on granite and their effectiveness of the common cleaning procedures. Furthermore, this paper carried out a review of the knowledge about those three alteration forms on granite, as well as bringing together all the major studies in the field of the granite cleaning with traditional procedures (chemical and mechanical) and with the recent developed technique based on the laser ablation. Findings concerning the effectiveness evaluation of these cleaning procedures, considering the coating extraction ability and the damage induced on the granite surface, are described. Finally, some futures research lines are pointed out.

  14. Magnesium isotope fractionation during differentiation of Harney Peak granite

    Science.gov (United States)

    Ke, S.; Teng, F.; Walker, R. J.

    2009-12-01

    Although numerous studies have sought to constrain the Mg isotopic composition of mantle rocks, few studies have focused on the Mg isotopic compositions of crustal rocks, particularly evolved igneous rocks, such as granites. Granites are a major component of the upper continental crust and can be produced by partial melting of the deep continental crust. Studies of granites, therefore, can potentially provide important constraints on Mg isotopic composition variations in the continental crust as related to sources and petrogenetic processes. In order to explore the behavior of Mg isotopes during partial melting of continental crust, as well as granite differentiation, we have begun a study of a set of well-characterized samples from S-type Harney Peak granite, its potential source rocks and associated Tin Mountain pegmatite from Black Hills, South Dakota, USA. δ26Mg values of Harney Peak granites and Tin Mountain pegmatite vary significantly (from -0.69 to +0.11), well beyond the range of their potential source rocks (from -0.40 to +0.15) — early Proterozoic schists and late Archean metagranites. The large Mg isotopic variations within the granite suite likely, in part, reflect heterogeneities in source rocks, as previously shown for oxygen and Nd isotopes. A greater cause of the variations may be fractionations that occur during partial melting and subsequent differentiation of granitic melts, as suggested by the correlations between δ26Mg with SiO2, Al2O3, Na2O and Sr.

  15. Geophysical Studies of Irish Granites Using Magnetotelluric and Gravity Data

    Science.gov (United States)

    Farrell, T. F.; Muller, M. R.; Rath, V.; Feely, M.; Hogg, C.

    2014-12-01

    We present results of on-going geophysical studies of Caledonian radiothermal granite bodies in Ireland, which are being undertaken to investigate the volumetric depth extent and structural features of these granites. During three field seasons, magnetotelluric (MT) and audio-magnetotelluric (AMT) data were acquired at 156 sites targeting three separate granite bodies. These studies will contribute to a crustal-scale investigation of the geothermal energy potential of the granites and their contribution to the thermal field of the Irish crust. Across the calc-alkaline Galway granite, located on the Irish west coast, MT and AMT data were acquired at 75 sites distributed in a grid. Preliminary 3D inversion reveals the presence of a resistor, thickest beneath the central block of the granite where it extends to depths of 11 - 12 km. The greater depth of the resistor beneath the central block is in contrast to previous thinking that proposed the central block granites to have shallower depth extent than those of the western block, based on Bouguer anomaly maps of the area in which the western block exhibited a more pronounced negative Bouguer anomaly than the central block. At the S-type Leinster granite, in eastern Ireland and to the south of Dublin, MT and AMT data were acquired along two profiles (LGN - 27 sites and LGS - 32 sites). Preliminary 1D inversions of AMT data along profile LGN show the Northern Units of the Leinster granite to extend to a depth of 4.5 km and the Lugnaquilla pluton extending to 2.5 km depth. MT and AMT data were acquired at 22 sites along a profile across the buried Kentstown granite, 35 km to the NW of Dublin. The Kentstown granite was intersected by two mineral exploration boreholes at depths of 492 m and 663 m. Preliminary 2D inversions do not yet satisfactorily resolve the top of the buried granite. Inversion of MT and AMT data is continuing, with the electrical conductivity structures revealed by these inversions being used to

  16. Mineral chemistry of tourmaline from Mashak Pahar, South Purulia Shear Zone (SPSZ), eastern Indian Shield

    Indian Academy of Sciences (India)

    Santanu Acharjee; Jyotisankar Ray; Payel Dey; Debapriya Bhattacharyya; Mousumi Banerjee; Basab Chattopadhyay; Shyamal Sengupta; A K Bhatt; D Chowdhury; A K Dwivedi; Sanjoy Mahato; Arka Ranjan Jana; P B Maithani; P V Ramesh Babu

    2016-12-01

    The area of investigation at and around Mashak Pahar, Bankura district, West Bengal, India comprises a number of rock types namely: granite gneiss, migmatized quartz tourmaline gneiss, quartz pebbleconglomerate, ferruginous quartzite, quartz tourmaline veins (as veins) and graphite schists. Interestingly, the study area lies in the region extending South Purulia Shear Zone (∼Tamar–Porapahar Shear Zone) which marks the boundary between two contrasting tectonic blocks of eastern India, namely, the Chhotanagpur Gneissic Terrane (CGC) to the north and Singhbhum Group of rocks to the south. The rocks of the study area are poly-phasedly deformed by three phases of folding, namely, F1, F2 and F3. All the tourmalines are classified to be of ‘Alkali Group’. Chemistry of tourmalines from migmatized quartz tourmaline gneiss and those from quartz tourmaline veins are in conformity with their relation to (earthquake induced) shear system evolution in this terrain. In general, the compositional evolutionof tourmaline during prograde metamorphism (∼400°–730°C) has been supported by both petrographic and chemical evidences. Assessment of mineral–chemical data of constituent tourmaline grains clearly suggests compositional variations across zonal boundaries within tourmaline that was controlled by changing metamorphic milieu in this terrane. Field and petrographic evidences clearly indicate activation of earlier and later shears in this region accompanied by infiltration of boron and formation of zoned tourmaline crystals.

  17. Tectonic imprints within a granite exposed near Srinagar, Rajasthan, India

    Indian Academy of Sciences (India)

    Trishit Ruj; Nilanjan Dasgupta

    2014-08-01

    Partial melting in the middle to lower crustal level produces melts of granitic composition during orogeny. Thrusts play a vital role in their exhumation after consolidation of these granitic melts. In this paper we focus on one such granite along the eastern margin of the Delhi Fold Belt (DFB) rocks near Srinagar, Rajasthan, India. This is the first report of granite within the area and holds a key stratigraphic position in the entire rock package. The said granite is found to be intrusive to the DFB metasediments as well as their basement popularly known as the Banded Gneissic Complex (BGC). We disentangle the deformation fabrics seen within the granite and associated DFB metasediments, suggesting that subsequent to emplacement and consolidation, the granite has co-folded along with the country rocks. Three deformational events could be identified within the DFB metasediments namely, D1D, D2D and D3D. The peak metamorphism was achieved in the D1D event. The granite magma is generated and emplaced late syn-kinematic to D1D and thereafter is deformed by D2D and D3D producing D1G and D2G structural fabrics. These compressive deformations resulted in the collapse of the basin; the combined package of DFB rocks and the granite was thrusted eastwards over the basement rocks. The tectonic transport direction during thrusting is suggested eastwards from our structural analysis. Transverse faults developed perpendicular to the length of the granite have led to partitioning of the strain thereby showing a heterogeneity in the development of fabric within it.

  18. Total exploitation of an ornamental granite quarry

    Directory of Open Access Journals (Sweden)

    Taboada, J.

    2005-09-01

    Full Text Available In this paper we propose a methodology to estimate the recovery percentage for each of the products which can be obtained from the exploitation of an ornamental granite quarry: block, semiblock, masonry-transverse stone, and the smaller materials that can be used to obtain construction aggregates. This methodology ensures that quarry exploitation is exhaustive, thereby minimising the production of spoils and the consequent negative impact on the environment. The analysis is based on a detailed and exhaustive compilation of discontinuity data from the research fronts, which are then interpreted statistically and projected over the three weakness planes that are a particular feature of ornamental granite deposits. Using this information, and bearing in mind the minimum commercially viable sizes for each kind of granite, the corresponding recovery rates are calculated for each material in each plane. The results are then integrated using spatial techniques, and the result is an evaluation of quarry contents with a view to total exploitation. This methodology was applied to a quarry in the opening phase in order to carry out an a priori assessment of the economic feasibility of the quarry.

    En este trabajo se propone una metodología para estimar el porcentaje de recuperación de cada uno de los productos que se pueden obtener en la explotación de una cantera de granito ornamental: bloque, semibloque, manpostería y per piaños, y material restante destinado a la obtención de áridos. De esta manera se logra un aprovechamiento integral de la cantera, evitándose la generación de estériles y el subsiguiente impacto ambiental producido por éstos. La metodología de análisis se basa en la recopilación detallada y exhaustiva de datos de discontinuidades en los frentes de investigación, que se interpretan estadísticamente y se proyectan sobre los tres planos de debilidad propios del granito ornamental. Con esta información, y las

  19. The "granite pump": LP/HT metamorphism and exhumation in the Montagne Nore (S-France)

    Science.gov (United States)

    Franke, W.; Doublier, M. P.; Doerr, W.; Stein, E.

    2003-04-01

    The Montagne Noire at the southern margin of the French Massif Central represents an exceptional case of a hot metamorphic core complex evolved from a thrust stack in a foreland position. The core of the structure (Zone Axiale) exposes granites and LP/HT gneisses up to anatectic grade. The hot core is encased by ENE-trending shear zones, which define a dextral pull-apart structure. Ductile extension is documented by top WSW shearing in the W, and ENE shearing in the E part of the Zone Axiale (eg, MATTE et al., 1998). Extension in ENE and reduction of the metamorphic profile are accompanied by NNW-directed contraction ("pinched pull-apart"). Palaeozoic sediments on the southern flank of the Zone Axiale exhibit only greenschist to diagenetic grades of metamorphism. Conodont alteration index (WIEDERER et al., 2002) and illite crystallinity (Doublier, this meeting) reveal a decrease of metamorphic temperature away from the hot core. Metamorphic isograds cut across the axial planes of D1 nappes. These features suggest that metamorphism was imposed by the rising hot core. Accordingly, the palaeozoic sediments show a tectonic evolution which closely resembles that of the gneissic core (extension top ENE, contraction in NNW). Structures relating to stacking (D1) have survived at the southern margin of the Montagne Noire. U-Pb studies (TIMS on single zircon and monazite) reveal peak metamorphism and magmatism already at c. 315 Ma (KLAMA et al., 2001), i.e., only <10 Ma after the end of flysch deposition in latest Visean/Early Namurian time (<= 323 Ma). The coincidence, within error, of the U-Pb ages and earlier Ar/Ar ages (MALUSKI et al., 1991) suggest rapid cooling. Synchronous granite emplacement and metamorphism is best explained by advective heating. Since granites are not generated in foreland settings, we propose derivation of the melts from areas of thickened crust adjacent to the N. Transport and emplacement of granites was essentially driven by the hydraulic

  20. IRETHERM: The geothermal energy potential of Irish radiothermal granites

    Science.gov (United States)

    Farrell, Thomas; Jones, Alan; Muller, Mark; Feely, Martin; Brock, Andrew; Long, Mike; Waters, Tim

    2014-05-01

    The IRETHERM project is developing a strategic understanding of Ireland's deep geothermal energy potential through integrated modelling of new and existing geophysical and geological data. One aspect of IRETHERM's research focuses on Ireland's radiothermal granites, where increased concentrations of radioelements provide elevated heat-production (HP), surface heat-flow (SHF) and subsurface temperatures. An understanding of the contribution of granites to the thermal field of Ireland is important to assessing the geothermal energy potential of this low-enthalpy setting. This study focuses on the Galway granite in western Ireland, and the Leinster and the buried Kentstown granites in eastern Ireland. Shallow (geothermal project. These studies yielded HP = 2-3 μWm-3 and HF = 80 mWm-2 at the Sally Gap borehole in the Northern Units of the Leinster granite, to the SW of Dublin. In the Galway granite batholith, on the west coast of Ireland, the Costelloe-Murvey granite returned HP = 7 μWm-3 and HF = 77 mWm-2, measured at the Rossaveal borehole. The buried Kentstown granite, 35 km NW of Dublin, has an associated negative Bouguer anomaly and was intersected by two mineral exploration boreholes at depths of 660 m and 490 m. Heat production is measured at 2.4 μWm-3 in core samples taken from the weathered top 30 m of the granite. The core of this study consists of a program of magnetotelluric (MT) and audio-magnetotelluric (AMT) data acquisition across the three granite bodies, over three fieldwork seasons. MT and AMT data were collected at 59 locations along two profiles over the Leinster granite. Preliminary results show that the northern units of the Leinster granite (40 km SW of Dublin) extend to depths of 2-5 km. Preliminary results from the southern profile suggest a greater thickness of granite to a depth of 6-9 km beneath the Tullow pluton, 75 km SW of Dublin. Over the Galway granite, MT and AMT data have been collected at a total of 75 sites (33 consist of only

  1. Occurrence of silicate melt, carbonate-rich melt and fluid during medium pressure anatexis of metapelitic gneisses (Oberpfalz, Bavaria) revealed by melt and fluid inclusions study

    Science.gov (United States)

    Ferrero, Silvio; O'Brien, Patrick; Hecht, Lutz; Wunder, Bernd

    2014-05-01

    of a silicate melt and a carbonate-rich melt during anatexis at relatively shallow crustal levels, but this hypothesis needs to be further tested through re-homogenization experiments by piston cylinder means. References Bartoli, O., Cesare, B., Poli, S., Bodnar, R.J., Acosta-Vigil, A., Frezzotti, M.L. & Meli, S., 2013. Recovering the composition of melt and the fluid regime at the onset of crustal anatexis and S-type granite formation. Geology, 41, 115-118. Cesare, B., Ferrero, S., Salvioli-Mariani, E., Pedron, D. & Cavallo, A., 2009. Nanogranite and glassy inclusions: the anatectic melt in migmatites and granulites. Geology, 37, 627-630. Ferrero, S., Bartoli, O., Cesare, B., Salvioli Mariani, E., Acosta-Vigil, A., Cavallo, A., Groppo, C. & Battiston, S., 2012. Microstructures of melt inclusions in anatectic metasedimentary rocks. Journal of Metamorphic Geology, 30, 303-322. Ferrero, S., Braga, R., Berkesi, M., Cesare, B. & Laridhi Ouazaa, N., 2014. Production of Metaluminous melt during fluid-present anatexis: an example from the Maghrebian basement, La Galite Archipelago, central Mediterranean. Journal of Metamorphic Geology, DOI:10.1111/jmg.12068. Tanner, D.C. & Behrmann, J.H., 1995. The Variscan tectonics of the Moldanubian gneisses, Oberpfalzer Wald: a compressional history. Neues Jahrbuch fur Geologie und Palaontologie. Abhandlungen, 197, 331-355. Touret, J.L.R., 2009. Mantle to lower-crust fluid/melt transfer through granulite metamorphism. Russian Geology and Geophysics, 50, 1052-1062.

  2. Uranium-lead isotope systematics and apparent ages of zircons and other minerals in precambrian granitic rocks, Granite Mountains, Wyoming

    Science.gov (United States)

    Ludwig, K. R.; Stuckless, J.S.

    1978-01-01

    Zircon suites from the two main types of granite in the Granite Mountains, Wyoming, yielded concordia-intercept ages of 2,640??20 m.y. for a red, foliated granite (granite of Long Creek Mountain) and 2,595??40 m.y. for the much larger mass of the granite of Lankin Dome. These ages are statistically distinct (40??20 m.y. difference) and are consistent with observed chemical and textural differences. The lower intercepts of the zircon chords of 50??40 and 100+ 75 m.y. for the granite of Long Creek Mountain and granite of Lankin Dome, respectively, are not consistent with reasonable continuous diffusion lead-loss curves but do correspond well with the known (Laramide) time of uplift of the rocks. Epidote, zircon, and apatite from silicified and epidotized zones in the granites all record at least one postcrystallization disturbance in addition to the Laramide event and do not define a unique age of silicification and epidotization. The lower limit of ???2,500 m.y. provided by the least disturbed epidote, however, suggests that these rocks were probably formed by deuteric processes shortly after emplacement of the granite of the Lankin Dome. The earlier of the two disturbances that affected the minerals of the silicified-epidotized rock can be bracketed between 1,350 and 2,240 m.y. ago and is probably the same event that lowered mineral K-Ar and ages in the region. Zircon suites from both types of granite show well-defined linear correlations among U content, common-Pb content, and degree of discordance. One of the zircon suites has an extremely high common-Pb content (up to 180 ppm) and exhibits a component of radiogenic-Pb loss that is apparently unrelated to radiation damage. ?? 1978 Springer-Verlag.

  3. Water–rock interaction on the development of granite gneissic weathered profiles in Garhwal Lesser Himalaya, India

    Indian Academy of Sciences (India)

    S Vyshnavi; R Islam

    2015-07-01

    The development and sustainability of weathered profiles are very difficult in the Himalaya due to its complex lithology, tectonic history and fast erosion. Despite this, two weathered profiles namely WPa (weathered profile a) and WPb (weathered profile b) which have sustained erosion are developed on porphyry granite gneiss and granite gneissic lithology in Alaknanda valley of the Garhwal Lesser Himalaya. Systematic sampling of these two weathered profiles was done from bottom to top and they were chemically analysed to understand the elemental mobility in each profile. Major, trace and rare earth element studies show dissimilar behaviour with the advancement of weathering. In WPa profile, the CIA value of LAR (LAR) is 50 which reveals that the rock has not suffered any alteration but in WPb profile, the CIA value of LAR is 64 which indicates significant amount of chemical alteration. A–CN–K projection also exhibits similar behaviour. Further, the relative mobility of all the major and trace elements show variable elemental distribution in both the profiles. Enrichment of Mg, Fe, Ti, Al, Co, Ni, Zr, LREE and depletion of Na, K, P, Ca, Si, LILE and HFSE are observed in WPa profile; while the depletion of Na, K, Ca, P, Si, HREE and enhancement of Fe, Mn, Ti, Sc, Co, Zr, LREE are noticed in WPb profile. The rare earth elements also show a dissimilar mobilization pattern in both the profiles due to their strong dependency on lithology, and corresponding climate and tectonic interaction. Contrasting elemental mobility in both the profiles depict the major role in disparity of lithological characters and subsequent development of fractures produced by the major thrust system (Ramgarh thrust) which made an easy passage for rain water, thus causing the development of a chemically altered profile in the Lesser Himalayan region. Further, the present study infers the climate and tectonic milieu which is responsible for the development of such weathered profiles in

  4. Water-rock interaction on the development of granite gneissic weathered profiles in Garhwal Lesser Himalaya, India

    Science.gov (United States)

    Vyshnavi, S.; Islam, R.

    2015-07-01

    The development and sustainability of weathered profiles are very difficult in the Himalaya due to its complex lithology, tectonic history and fast erosion. Despite this, two weathered profiles namely WPa (weathered profile a) and WPb (weathered profile b) which have sustained erosion are developed on porphyry granite gneiss and granite gneissic lithology in Alaknanda valley of the Garhwal Lesser Himalaya. Systematic sampling of these two weathered profiles was done from bottom to top and they were chemically analysed to understand the elemental mobility in each profile. Major, trace and rare earth element studies show dissimilar behaviour with the advancement of weathering. In WPa profile, the CIA value of LAR (LAR) is 50 which reveals that the rock has not suffered any alteration but in WPb profile, the CIA value of LAR is 64 which indicates significant amount of chemical alteration. A-CN-K projection also exhibits similar behaviour. Further, the relative mobility of all the major and trace elements show variable elemental distribution in both the profiles. Enrichment of Mg, Fe, Ti, Al, Co, Ni, Zr, LREE and depletion of Na, K, P, Ca, Si, LILE and HFSE are observed in WPa profile; while the depletion of Na, K, Ca, P, Si, HREE and enhancement of Fe, Mn, Ti, Sc, Co, Zr, LREE are noticed in WPb profile. The rare earth elements also show a dissimilar mobilization pattern in both the profiles due to their strong dependency on lithology, and corresponding climate and tectonic interaction. Contrasting elemental mobility in both the profiles depict the major role in disparity of lithological characters and subsequent development of fractures produced by the major thrust system (Ramgarh thrust) which made an easy passage for rain water, thus causing the development of a chemically altered profile in the Lesser Himalayan region. Further, the present study infers the climate and tectonic milieu which is responsible for the development of such weathered profiles in Himalayan

  5. Early Permian extensional shearing of an Ordovician granite: The Saint-Eutrope "C/S-like" orthogneiss (Montagne Noire, French Massif Central)

    Science.gov (United States)

    Pitra, Pavel; Poujol, Marc; Van Den Driessche, Jean; Poilvet, Jean-Charles; Paquette, Jean-Louis

    2012-08-01

    Dating the magmatic events in the Montagne Noire gneiss dome is a key point to arbitrate between the different interpretations of the Late Carboniferous-Early Permian tectonics in this southern part of the Variscan belt. The Saint-Eutrope orthogneiss crops out along the northern flank of the dome. We show that the protolith of this orthogneiss is an Ordovician granite dated at 455 ± 2 Ma (LA-ICP-MS U-Pb dating on zircon). This age is identical to that previously obtained on the augen orthogneiss of the southern flank, strongly suggesting that both orthogneiss occurrences have the same Ordovician protolith. The Saint-Eutrope orthogneiss experienced intense shearing along the Espinouse extensional detachment at ca. 295 Ma (LA-ICP-MS U-Pb-Th on monazite), an age close to that determined previously on mica by the 39Ar-40Ar method and contemporaneous with the emplacement age of the syntectonic Montalet granite farther to the west. This normal sense shearing reworked previous fabrics related to Variscan thrusting that can be still observed in the augen orthogneiss of the southern flank, and is responsible for the spectacular "C/S-like" pattern of the Saint-Eutrope orthogneiss. This work also shows that care is needed when dealing with C/S-type structures, since they can develop not only in syntectonic intrusions, but also in orthogneisses affected by an intense secondary deformation, at decreasing temperature.

  6. The petrochemistry characteristics and petrogenesis of peraluminous granite in Tibet

    Institute of Scientific and Technical Information of China (English)

    LIAO Zhongli; MO Xuanxue; PAN Guitang; ZHU Dicheng; WANG Liquan; ZHAO Zhidan; GENG Quanru; XIONG Xingguo; DONG Guochen

    2007-01-01

    There are 61 major peraluminous granitic bodies in Tibet (TPGs) along the south of the Bangong Co-Gêzê- Amdo-Nujiang suture, whose lithology includes tourmaline granite, muscovite granite and two-mica granite. The TPGs have SiO2 = 65.7%-79.52%, K2O + Na2O = 2.20%-12.51%, K2O/Na2O=0.49-1.04 and A/CNK= 1.04-1.38. Al2O3 gradually decreases and the other oxides disperse with the increase in SiO2. The rock series is mainly calc-alk series with high potassium. It has typical characteristics of strongly per- aluminous granite. Based on the alurninum saturation index and QAP plots, the peraluminous granite plot is mostly within the continental collision granite (CCG) field, indicat- ing that the peraluminous granites in Tibet formed in a continental collisional setting. Ab-Or-Q-H2O phase diagram indicates the pressure of 0.5×108-2×108 Pa in TPGs, from which it can be deduced that the forming temperature was under 700℃. The TPGs mainly occurred at the collision stage between two continental crust plates, and the original magma is rooted in the remelting from the upper crust. It is the S-type granite in petrogenesis. The South Gandise belt and the Lhagoi Kangri belt have similar characteristics, suggesting that the two belts have the same magma source and the same tectonic setting.

  7. Long-range laser scanning and 3D imaging for the Gneiss quarries survey

    Science.gov (United States)

    Schenker, Filippo Luca; Spataro, Alessio; Pozzoni, Maurizio; Ambrosi, Christian; Cannata, Massimiliano; Günther, Felix; Corboud, Federico

    2016-04-01

    In Canton Ticino (Southern Switzerland), the exploitation of natural stone, mostly gneisses, is an important activity of valley's economies. Nowadays, these economic activities are menaced by (i) the exploitation costs related to geological phenomena such as fractures, faults and heterogeneous rocks that hinder the processing of the stone product, (ii) continuously changing demand because of the evolving natural stone fashion and (iii) increasing administrative limits and rules acting to protect the environment. Therefore, the sustainable development of the sector for the next decades needs new and effective strategies to regulate and plan the quarries. A fundamental step in this process is the building of a 3D geological model of the quarries to constrain the volume of commercial natural stone and the volume of waste. In this context, we conducted Terrestrial Laser Scanning surveys of the quarries in the Maggia Valley to obtain a detailed 3D topography onto which the geological units were mapped. The topographic 3D model was obtained with a long-range laser scanning Riegl VZ4000 that can measure from up to 4 km of distance with a speed of 147,000 points per second. It operates with the new V-line technology, which defines the surface relief by sensing differentiated signals (echoes), even in the presence of obstacles such as vegetation. Depending on the esthetics of the gneisses, we defined seven types of natural stones that, together with faults and joints, were mapped onto the 3D models of the exploitation sites. According to the orientation of the geological limits and structures, we projected the different rock units and fractures into the excavation front. This way, we obtained a 3D geological model from which we can quantitatively estimate the volume of the seven different natural stones (with different commercial value) and waste (with low commercial value). To verify the 3D geological models and to quantify exploited rock and waste volumes the same

  8. Contact metamorphism, partial melting and fluid flow in the granitic footwall of the South Kawishiwi Intrusion, Duluth Complex, USA

    Science.gov (United States)

    Benko, Z.; Mogessie, A.; Molnar, F.; Severson, M.; Hauck, S.; Lechler, P.; Arehart, G.

    2012-04-01

    The footwall of the South Kawishiwi Intrusion (SKI) a part of the Mesoproterozoic (1.1 Ga) Duluth Complex consists of Archean granite-gneiss, diorite, granodiorite (Giant Range Batholith), thin condensed sequences of Paleoproterozoic shale (Virginia Fm.), as well as banded iron formation (Biwabik Iron Fm). Detailed (re)logging and petrographic analysis of granitic footwall rocks in the NM-57 drillhole from the Dunka Pit area has been performed to understand metamorphic processes, partial melting, deformation and geochemical characteristics of de-volatilization or influx of fluids. In the studied drillhole the footwall consists of foliated metagranite that is intersected by mafic (dioritic) dykes of older age than the SKI. In the proximal contact zones, in the mafic dykes, the orthopyroxene+clinopyroxene+plagioclase+quartz+Fe-Ti-oxide+hornblende±biotite porphyroblasts embedded in a plagioclase+K-feldspar+orthopyroxene+apatite matrix indicate pyroxene-hornfels facies conditions. Migmatitization is revealed by the euhedral crystal faces of plagioclase and pyroxene against anhedral quartz crystals in the in-situ leucosome and by the presence of abundant in-source plagioclase±biotite leucosome veinlets. Amphibole in the melanosome of mafic dykes was formed with breakdown of biotite and implies addition of H2O to the system during partial melting. Towards the deeper zones, the partially melted metatexite-granite can be characterized by K-feldspar+plagioclase+quartz+ortho/clinopyroxene+biotite+Fe-Ti-oxide+apatite mineral assemblage. The felsic veins with either pegmatitic or aplititic textures display sharp contact both to the granite and the mafic veins. They are characterized by K-feldspar+quartz±plagioclase±muscovite mineral assemblage. Sporadic occurrence of muscovite suggest local fluid saturated conditions. Emplacement of gabbroic rocks of the SKI generated intense shear in some zones of the granitic footwall resulting in formation of biotite-rich mylonites with

  9. 2005 dossier: granite. Tome: phenomenological evolution of the geologic disposal; Dossier 2005: Granite. Tome evolution phenomenologique du stockage geologique

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the phenomenological aspects of the geologic disposal of high-level and long-lived radioactive wastes (HLLL) in granite formations. Content: 1 - introduction: ANDRA's research program on disposal in granitic formation; 2 - the granitic environment: geologic history, French granites; 3 - HLLL wastes and disposal design concepts; 4 - identification, characterization and modeling of a granitic site: approach, geologic modeling, hydrologic and hydro-geochemical modeling, geomechanical and thermal modeling, long-term geologic evolution of a site; 5 - phenomenological evolution of a disposal: main aspects of the evolution of a repository with time, disposal infrastructures, B-type wastes disposal area, C-type wastes disposal area; spent fuels disposal area, radionuclides transfer and retention in the granitic environment; 6 - conclusions: available knowledge, methods and tools for the understanding and modeling of the phenomenological evolution of a granitic disposal site. (J.S.)

  10. Metamorphism of cordierite gneisses from Eastern Ghat Granulite Terrain, Andhra Pradesh, South India

    Science.gov (United States)

    Murthy, D. S. N.; Charan, S. Nirmal

    1988-01-01

    Cordierite-bearing metapelites of the Eastern Ghat granulite terrain occur in close association of Khondalites, quartzites, calc-silicate rocks and charnockites. Rocks occurring between Bobbili in the north and Guntur in the south of Andhra Pradesh are studied. The association of the mineral and textural relationships suggest the following metamorphic reactions: Garnet + sillimanite + quartz = cordierite, hypersthene + sillimanite + quartz = cordierite, sillimanite + spinel = cordierite + corundum, and biotite + quartz + sillimanite = cordierite + K=feldspar. Generally the minerals are not chemically zoned except garnet-biotite showing zoning when they come in close contact with one another. The potential thermometers are provided by the Fe-Mg distribution of coexisting biotite-garnet and cordierite-garnet. Conflicting interpretation of the P/T dependence of these reactions involving cordierite are due to H2O in the cordierite. The presence of alkali feldspar-quartz assemblage which is common in these gneisses will be constrained from melting only if H2O activity is less than 0.5. The piezometric array inferred is convex towards the temperature array, indicating a rapid and isothermal crustal uplift probably aided by thrust tectonics.

  11. Geochemistry of Archean Tonalitic—Ganodioritic Gneisses from Chicheng County,Northwestern Hebei Province

    Institute of Scientific and Technical Information of China (English)

    陈岳龙; 陈伟邦; 等

    1989-01-01

    Detailed geological,chronological,mineralogical,petrological and geochemical studies have been conducted of the Chichent gneissic complex in northwestern Hebei province.The gneissic complex is composed mainly of tonalitic-granodioritic rocks according to O'Connor's classification.The zircou U-Pb age of the gneissic complex is 2468-27+33 Ma.,consistent with that of the rocks in the North Tonalitic-granodioritic Gneiss Belt in the North China Platorm.The Archean Chicheng gneissic complex is part of the belt.No significant difference in composition between early anhedral metasomatic and late semi-euhedral plagiocalases suggests that the gneissic complex is not composed merely of mafic rocks replaced by felsic fiuids.The REE patterns in the complex,in conjunction with major and trace elements data,show that the gneissic complex is the mixture of felsic magma produced by partial melting of FI dacitic granulite and crystallate derived from the magma produced by 50%±partial melting of TH2 tholeiitic granulite and 40%±fractional crystallization of hornblende.

  12. Age and origin of post collision Baltoro granites, south Karakoram, North Pakistan: Insights from in-situ U-Pb, Hf and oxygen isotopic record of zircons

    Science.gov (United States)

    Mahar, Munazzam Ali; Mahéo, Gweltaz; Goodell, Philip C.; Pavlis, Terry L.

    2014-09-01

    Origin of post collision plutonism is critical to understand the tectonothermal evolution of the over thickened continental crust in collision zones. This has proven difficult to reconcile with the conventional whole rock geochemical and field based studies alone. We report in-situ study of zircon U-Pb, Hf and O isotopes from five samples of the Baltoro Plutonic Unit (BPU) in south Karakoram. The plutonic unit is the western part of the southern Asian margin of the India-Asia convergent zone. Baltoro granites and a biotite-rich enclave yielded similar and overlapping U-Pb ages ranging from 26 to 15 Ma. Hafnium isotopic composition (εHf (0)) is very heterogeneous ranging from - 17.1 to + 4.4 while the oxygen isotopic composition of the granites is homogeneous with mean δ18O ranging from 7.2 to 9.4‰. Based on U-Pb geochronology and Hf-O isotopic composition, the involvement of two main sources is suggested (1) Cretaceous calc-alkaline Karakoram crust and (2) Karakoram gneisses. Moreover, possible involvement of metasomatized Asian lithospheric mantle is supported by elevated oxygen composition of granites and identical Hf composition of biotite-rich enclave to the mantle derived Baltoro lamprophyre. However, direct contribution from juvenile pristine mantle is unlikely as no juvenile mantle type Hf and oxygen values were obtained. This also precludes the involvement of southward juvenile arc related component of Kohistan-Ladakh batholith. Our new U-Pb and Hf data are comparable to the Mesozoic Karakoram batholith, Miocene two-mica leucogranites in the Pangong Range and magmatism from the Lhasa terrane in south Tibet, suggesting a genetic link between the Karakoram and the rocks to the east. This magmatic event is best explained by lower crust partial melting promoted by both thermal equilibration following crustal thickening and heat advection by ultrapotassic magmas associated with the breakoff of the Indian continental margin.

  13. The 3.5 Ga Siurua trondhjemite gneiss in the Archaean Pudasjärvi Granulite Belt, northern Finland

    Directory of Open Access Journals (Sweden)

    Tapani Mutanen

    2003-01-01

    Full Text Available In the Archaean Pudasjärvi Complex the pyroxene-bearing rocks are considered to form a belt, the Pudasjärvi Granulite Belt (PGB. The major rock types of the PGB are metaigneous mafic and felsic granulites, and trondhjemite gneisses. Red alaskites, white leucogranites and trondhjemitic pegmatoids are locally abundant. Ion microprobe U-Pb analyses on zircons suggest a magmatic age of ca. 3.5 Ga for the trondhjemite gneiss in Siurua, considered the oldest rock so far identified in the Fennoscandian Shield. The old age is supported by the Sm-Nd depleted mantle model age of 3.5 Ga, and by conventional U-Pb zircon data, which have provided a minimum age of 3.32 Ga. The U-Pb sims-data on the Siurua gneiss are, however, heterogeneous and suggest several stages of zircon growth, mostly at 3.5–3.4 Ga. An inherited core in one crystal provided an age of 3.73Ga, whereas the youngest two analyses yield ages of 3.1 and 3.3 Ga. Metamorphic monazite formed in the Siurua gneiss ca. 2.66 Ga ago, roughly contemporaneously with the high-grade metamorphism recorded by zircon in a mafi c granulite. Magmatic zircons from a felsic high-grade rock provide ages of ca. 2.96 Ga, but no zircons coeval with the 2.65 Ga metamorphism were detected by ion-microprobe. As a whole the PGB seems to be a tectonic block-mosaic containing rocks with Sm-Nd crustal formation ages ranging from 3.5 to 2.8 Ga.

  14. Effect of Hydrograph Separation on Suspended Sediment Concentration Predictions in a Forested Headwater with Thick Soil and Weathered Gneiss Layers

    Directory of Open Access Journals (Sweden)

    Naoki Kabeya

    2014-06-01

    Full Text Available Two-component hydrograph separation using oxygen-18 concentrations was conducted at a sediment runoff observation weir installed in a small subcatchment of a forested gneiss catchment in Japan. The mean soil thickness of this catchment is 7.27 m, which comprises 3.29 m of brown forest soil (A and B layers and a 3.98-m layer of heavily weathered gneiss. Data were collected for a storm on 20–21 May 2003, and the percentage of event water separated by the stable isotope ratio in comparison with the total rainfall amount was about 1%. This value is within the ratio of a riparian zone in a drainage area. Temporal variation of suspended sediment concentration exhibited higher correlation with the event water component than with the total runoff or pre-event water component. This shows that the riparian zone causes rainwater to flow out quickly during a rain event, and that this is an important area of sediment production and transportation in a forested headwater with thick soil and weathered gneiss layers.

  15. Gneiss-Water Interaction and Water Evolution During the Early Stages of Dissolution Experiments at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    Zhu Yinian(朱义年); Ingrid Stober; Kurt Bucher

    2003-01-01

    Gneiss-distilled water interaction at room temperature was investigated with batch-reactors to study water-rock reaction and geochemical evolution of the aqueous phase with time.The ion concentrations in water were controlled not only by the dissolution of primary minerals,but also by the precipitation of secondary minerals. The decreasing fraction sizes of gneiss could favor dissolution and precipitation simultaneously. Ca2+ and K + were the major cations,and HCO3- was the major anion in water. All the ions except Ca2 + increased in concentration with time. The Ca2 + release from the rock to the aqueous phase was initially much faster than the release of K + ,Na + and Mg2 +. But after about 5 - 24 hours,the Ca2 + concentrations in water decreased very slowly with time and became relatively stable. During the experiment,the water varied from the Ca-( K)-HCO3-type water to the K-Ca-HCO3-type water,and then to the K( Ca,Na) -HCO3-type water. The water-gneiss interaction was dominated by the dissolution of Kfeldspar in the solution. The remaining secondary minerals were mainly kaolinite,illite and K (Mg) -mica.

  16. The Landforms of Granitic Rocks: An Annotated Bibliography

    Science.gov (United States)

    1990-05-01

    rock faces develop on granitic inselbergs; and 4) old age : pediments are dominant in the landscape, relief is low, tors develop as residu- als in...scale. The rock is a coarse-grained, biotite-hornbleade granite, forms tors and is post- tectonic and late Hercynian in age . The climate is humid...source of the salts. Brook, G. A. 1978. A new approach to the study of inselberg landscapes. Zeitschrift fir Geo- morphologie , Supplement 31, pp. 138

  17. Quality control chart for crushed granite concrete

    Directory of Open Access Journals (Sweden)

    Ewa E. DESMOND

    2016-07-01

    Full Text Available A chart for assessing in-situ grade (strength of concrete, has been developed in this study. Four grades of concrete after the Nigerian General Specification for Roads and bridges (NGSRB-C20, C25, C30 and C35, is studied at different water-cement ratios for medium and high slump range. The concrete mixes are made from crushed granite rock as coarse aggregate with river sand as fine aggregate. Compression test on specimens are conducted at curing age of 1, 3, 7, 14, 21, 28 and 56 days. Results on concrete workability from slump values, and water-cement ratios revealed that specimens with lower water-cement ratio were less workable but had higher strength, compared to mixes with higher water cement ratio. A simple algorithm using nonlinear regression analysis performed on each experimental data set produced Strength-Age (S-A curves which were used to establish a quality control chart. The accuracy of these curves were evaluated by computing average absolute error (AAS, the error of estimate (EoE and the average absolute error of estimate (Abs EoE for each concrete mix. These were done based on the actual average experimental strengths to measure how close the predicted values are to the experimental data set. The absolute average error of estimate (Abs. EoE recorded was less than ±10% tolerance zone for concrete works.

  18. Hydraulic fracturing in granite under geothermal conditions

    Science.gov (United States)

    Solberg, P.; Lockner, D.; Byerlee, J.D.

    1980-01-01

    The experimental hydraulic fracturing of granite under geothermal conditions produces tensile fracture at rapid fluid injection rates and shear fracture at slow injection rates and elevated differential stress levels. A sudden burst of acoustic emission activity accompanies tensile fracture formation whereas the acoustic emission rate increases exponentially prior to shear fracture. Temperature does not significantly affect the failure mechanism, and the experimental results have not demonstrated the occurrence of thermal fracturing. A critical result of these experiments is that fluid injection at intermediate rates and elevated differential stress levels increases permeability by more than an order of magnitude without producing macroscopic fractures, and low-level acoustic emission activity occurs simultaneously near the borehole and propagates outward into the specimen with time. Permeability measurements conducted at atmospheric pressure both before and after these experiments show that increased permeability is produced by permanent structural changes in the rock. Although results of this study have not demonstrated the occurrence of thermal fracturing, they suggest that fluid injection at certain rates in situ may markedly increase local permeability. This could prove critical to increasing the efficiency of heat exchange for geothermal energy extraction from hot dry rock. ?? 1980.

  19. High-grade deformation in quartzo-feldspathic gneisses during the early Variscan exhumation of the Cabo Ortegal nappe, NW of Iberia

    Directory of Open Access Journals (Sweden)

    F. J. Fernández

    2015-12-01

    Full Text Available High-grade highly deformed gneisses crop out continuously along the Masanteo peninsula in the Cabo Ortegal nappe (NW Spain. The rock sequence formed by quartzo-feldspathic gneisses and mafic rocks records two partial melting events: during the Early Ordovician (ca. 480–488 Ma., at the base of the Qz-Fsp gneisses, and immediately after eclogization (ca. 390.4 ± 1.2 Ma, during its early Variscan exhumation. Despite the strain accumulated during their final exhumation in which a pervasive blastomylonitic S2 foliation was developed, primary sedimentary layering in Qz-Fsp gneisses is well preserved locally at the top of the sequence. This first stage of the exhumation process occurred in ~ 10 Ma, during which bulk flattening of the high-grade rock sequence was accommodated by anastomosing shear bands that evolved to planar shear zones. Strain was progressively localized along the boundaries of the migmatitic Qz-Fsp gneisses. A SE-vergent ductile thrust constitutes the base of gneisses, incorporating eclogite blocks-in-matrix. A NW-vergent detachment placed the metasedimentary Qz-Fsp gneisses over the migmatitic Qz-Fsp gneisses. A difference in metamorphic pressure of ca. 0.5 GPa is estimated between both gneissic units. The high-grade deformation reduced substantially the thickness of the gneissic rock sequence during the process of exhumation controlled by change in the strain direction and the progressive localization of strain. The combined movement of the top detachment and basal thrust resulted in an extrusion of the migmatites within the nappe, directed to the SE in current coordinates.

  20. Insights on high-grade deformation in quartzo-feldspathic gneisses during the early Variscan exhumation of the Cabo Ortegal nappe, NW Iberia

    Science.gov (United States)

    José Fernández, Francisco; Llana-Fúnez, Sergio; Valverde-Vaquero, Pablo; Marcos, Alberto; Castiñeiras, Pedro

    2016-04-01

    High-grade, highly deformed gneisses crop out continuously along the Masanteo peninsula and constitute the upper part of the lower crustal section in the Cabo Ortegal nappe (NW Spain). The rock sequence formed by migmatitic quartzo-feldspathic (qz-fsp) gneisses and mafic rocks records the early Ordovician (ca. 480-488 Ma) injection of felsic dioritic/granodioritic dykes at the base of the qz-fsp gneisses, and Devonian eclogitization (ca. 390.4 ± 1.2 Ma), prior to its exhumation. A SE-vergent ductile thrust constitutes the base of quartzo-feldspathic gneissic unit, incorporating mafic eclogite blocks within migmatitic gneisses. A NW-vergent detachment displaced metasedimentary qz-fsp gneisses over the migmatites. A difference in metamorphic pressure of ca. 0.5 GPa is estimated between both gneissic units. The tectono-metamorphic relationships of the basal ductile thrust and the normal detachment bounding the top of the migmatites indicate that both discrete mechanical contacts were active before the recumbent folding affecting the sequence of gneisses during their final emplacement. The progressive tectonic exhumation from eclogite to greenschist facies conditions occurred over ca. 10 Ma and involved bulk thinning of the high-grade rock sequence in the high pressure and high temperature (HP-HT) Cabo Ortegal nappe. The necessary strain was accommodated by the development of a widespread main foliation, dominated by flattening, that subsequently localized to a network of anastomosing shear bands that evolved to planar shear zones. Qz-fsp gneisses and neighbouring mafic granulites were exhumed at > 3 mm yr-1, and the exhumation path involved a cooling of ˜ 20 °C/100 MPa, These figures are comparable to currently active subduction zones, although exhumation P-T trajectory and ascent rates are at the hotter and slower end in comparison with currently active similar settings, suggesting an extremely ductile deformation environment during the exhumation of qz

  1. Granitoid magmatism of Alarmaut granite-metamorphic dome, West Chukotka, NE Russia

    Science.gov (United States)

    Luchitskaya, M. V.; Sokolov, S. D.; Bondarenko, G. E.; Katkov, S. M.

    2009-04-01

    . Soc. Amer. Spec. Paper, 2002, 360. P. 209-224 7. Sokolov S.D., Bondarenko G.E., Morozov O.L., Luchitskaya M.V. Tectonics of junction zone between Verkhoyan-Chukotka and Koryak-Kamchatka fold // Byul. MOIP. Otd. Geol. 2001. V. 76. Is.6. P.24-37. (in Russian) 8. Bondarenko G.E. Tectonics and geodynamic evolution of Mesozoides of north framework of Pacific Ocean. М.: MGU, 2004. 46 p. (in Russian) 9. Til'man S.M. Comparative tectonics of Mesozoides of northern part of Pacific rim. Novosibirsk: Nauka. 1973. 325 p. (in Russian) 10. Grantz A., Moore T. E., Roeske S.M. Gulf of Alaska to Arctic Ocean: Geological Society of America Continental-Ocean Transect A-3, scale 1:500,000. Menlo Park, California, 1991, 72 р. 11. Sadovsky A.I. Geologic map of USSR, scale 1:200000. Anyui-Chauna series. Paper R-58-XXVII, XXVIII. (Ed: Gel'man M.L.) Explanatory report. Leningrad: VSEGEI, 1970, 84 p. (in Russian) 12. Gel'man M.L. Phanerozoic granite-metamorphic domes at Russian North-East. Paper 2. Magmatism, metamorphism and migmatization in Late Mesozoic domes // Pacific geology. 1996. V. 15. № 1. P. 84-93. (in Russian) 13. Bering Strait Geologic Field Party, Koolen metamorphic complex, NE Russia: implications for the tectonic evolution of the Bering Strait region // Tectonics, vol. 16, no. 5, p. 713-729 14. Bondarenko G.E., Luchitskaya M.V. Mesozoic tectonic evolution of Alarmaut rise // Byul. MOIP. Otd. Geol. V. 78. Is. 3. P. 25-38. (in Russian) 15. Katkov S.M., Strikland A., Miller E.L. Age of granite batholiths in the Anyui-Chukotka Foldbelt // Doklady. Earth Sciences. 2007. Vol. 414. № 4. P. 515-518. 16. Amato J.M., Wright J.E. Potassic mafic magtism in the Kigluaik gneiss dome, northern Alaska: a geochemical study of arc magmatism in an extensional tectonic setting // J. Geophys. Res. 1997. Vol.102. N B4. P.8065-8084 17. Tikhomirov P.L., Luchitskaya M.V., Kravchenko-Berezhnoy I.R. Comparison of Cretaceous granitoids of the Chaun tectonic zone to those of the Taigonos Peninsula

  2. The 'Granite' collegial mission of dialogue. Report; Mission collegiale de concertation Granite. Rapport

    Energy Technology Data Exchange (ETDEWEB)

    Boisson, P.; Huet, Ph.; Mingasson, J

    2000-06-01

    The aim of the 'Granite' collegial mission of dialogue is to inform the French authorities, associations and population about the project of construction of an underground laboratory for the study of the disposal of high level and long-life radioactive wastes in a granitic environment. The aim of the dialogue was not to select a site but to collect the public reactions and advices about such a project. However, such a dialogue has partially failed because of a misunderstanding of the population about the aims of the mission. However, the mission has collected many point of views and questions which are developed in this report. The first and second chapters recall the process of the mission and its progress, while a third chapter stresses on the questions asked by the public and which concern the fear of nuclear wastes and the incompatibility between the disposal of wastes and the socio-economical development of the region concerned. Thanks to the lessons drawn from this experience, the mission has formulated some recommendations (chapter 4) concerning the need for a better information of the population about any topic in relation with the radioactive wastes. Some complementary information is provided in appendixes. (J.S.)

  3. Geochemistry of Gneisses from Dabie Complex and Tongbai Complex in Qinling-Tongbai-Dabie Orogenic Belt: Implications for Location of Yangtze-Sino-Korean Suture

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The Dabie complex (DC) and the Tongbai complex (TBC) are separately distributed in the middle and eastern parts of the Qinling-Tongbai-Dabie orogenic belt. In this study, the Dabie complex can be divided into two units: one is the complex with no high pressure and ultrahigh pressure metamorphic rocks (DC1), and the other is the complex containing coesite-bearing eclogite lenses or boudins (DC2). Gneisses are predominant in the TBC, DC1 and DC2. Major and trace element data of gneisses in the TBC, DC1 and DC2 show them to be the orthogneisses. The gneisses in the DC1 have higher incompatible element contents and higher ratios of w(K2O)/w(Na2O) and w(La)n/w(Yb)n than those in the DC2. However, no obvious differences arise in other element contents and the ratios of w(La)/w( Nb), w(Nb)/w(Th), w(Nb)/w(Hf), w(Ba)/w(La), w(Sm)/w(Nd) and w(Th)/w(U) between the gneisses in the DC2 and those in the DC1. These observations suggest that the protoliths of the gneisses in the DC2 have affinities to those in the DC1. The difference between the DC1 and DC2 gneisses in incompat- ible element contents could reflect the difference in their partial melting extent. The TBC gneisses are geochemically similar to the DC1 gneisses, suggesting that the TBC and DC1 gneisses are the same lithologic unit in the Qinling-Tongbai-Dabie orogenic belt and that they have experienced similar formations and evolution histories. In the Qinling-Tongbai area, the TBC is part of the northern blocks of the Yangtze craton. Given the similarity of geochemical characteristics, the rock assemblage and the ages between the TBC and DC1 gneisses, we can infer that the Dabie complex also belongs to the northern blocks of the Yangtze craton. In terms of the distribution of eciogites and metamorphic facies, we propose that the collisionai suture in the Dabie area is distributed along the Xiaotian-Mozitan fault, at the contact with the Shang-Dan-Tongbai fault to the west.

  4. Silicified Granites (Bleeding Stone and Ochre Granite) as Global Heritage Stones Resources from Avila (Central of Spain)

    Science.gov (United States)

    Garcia-Talegon, Jacinta; Iñigo, Adolfo C.; Vicente-Tavera, Santiago; Molina-Ballesteros, Eloy

    2015-04-01

    Silicified Granites have been widely used to build the main Romanesque monuments in the 12 th century of Avila city that was designated a World Heritage Site by the UNESCO in 1985. The stone was used in the Cathedral (12 th century); churches located interior and exterior of the Walls (e.g. Saint Vincent; Saint Peter). During the Renaissance and Gothic period, 15 th century Silicified Granites have been used mainly to buid ribbed vaults in Avila city (e.g. Royal Palace of the Catholic Monarchs, and Chapel of Mosén Rubí). Silicified Granites are related to an intermediate and upper parts of a complex palaeoweathering mantle developed on the Iberian Hercynian Basement (the greatest part of the western Iberian Peninsula and its oldest geological entity). In the Mesozoic the basement underwent tropical weathering processes. The weathered mantle were truncated by the Alpine tectonic movements during the Tertiary, and Its remnants were unconformably covered by more recent sediments and are located in the west and south part of the Duero Basin and in the north edge of the Ambles Valley graben. For the weathering profiles developed on the Hercynian Basement is possible to define three levels from bottom to top: 1) Lower level (biotitic granodiorite/porphyry and aplite dykes); 2) Intermediate level (ochre granite); 3) Upper level (red/white granite). The lower level has been much used as a source of ornamental stone, Avila Grey granite. The porphyry and applite dykes are mainly used to built the Walls of the City. The intermediate level is called Ochre granite or Caleño and was formed from the previous level through a tropical weathering process that, apart from variations in the petrophysical characteristics of the stone, has been accompanied by important mineralogical changes (2:1 and 1:1 phyllosilicates) and decreases in the contents of the most mobile cations. The upper level has received several names, Bleeding stone, Red and White granite or Silcrete and was formed

  5. Smolt Monitoring at the Head of Lower Granite Reservoir and Lower Granite Dam, 2004 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Edwin W.; Putnam, Scott A. [Idaho Department of Fish and Game

    2009-02-18

    This project monitored the daily passage of Chinook salmon Oncorhynchus tshawytscha, steelhead trout O. mykiss, and sockeye salmon O. nerka smolts during the 2004 spring out-migration at migrant traps on the Snake River and Salmon River. In 2004 fish management agencies released significant numbers of hatchery Chinook salmon and steelhead trout above Lower Granite Dam that were not marked with a fin clip or coded-wire tag. Generally, these fish were distinguishable from wild fish by the occurrence of fin erosion. Total annual hatchery Chinook salmon catch at the Snake River trap was 1.1 times greater in 2004 than in 2003. The wild Chinook catch was 1.1 times greater than the previous year. Hatchery steelhead trout catch was 1.2 times greater than in 2003. Wild steelhead trout catch was 1.6 times greater than the previous year. The Snake River trap collected 978 age-0 Chinook salmon of unknown rearing. During 2004, the Snake River trap captured 23 hatchery and 18 wild/natural sockeye salmon and 60 coho salmon O. kisutch of unknown rearing. Differences in trap catch between years are due to fluctuations not only in smolt production, but also differences in trap efficiency and duration of trap operation associated with flow. Trap operations began on March 7 and were terminated on June 4. The trap was out of operation for a total of zero days due to mechanical failure or debris. Hatchery Chinook salmon catch at the Salmon River trap was 10.8% less and wild Chinook salmon catch was 19.0% less than in 2003. The hatchery steelhead trout collection in 2004 was 20.0% less and wild steelhead trout collection was 22.3% less than the previous year. Trap operations began on March 7 and were terminated on May 28 due to high flows. There were two days when the trap was taken out of service because wild Chinook catch was very low, hatchery Chinook catch was very high, and the weekly quota of PIT tagged hatchery Chinook had been met. Travel time (d) and migration rate (km

  6. Diffusive transport in compacted mixtures of clay and crushed granite

    Energy Technology Data Exchange (ETDEWEB)

    Oscarson, D.W. (AECL Research, Whiteshell Labs., Pinawa, MB (Canada)); Hume, H.B. (AECL Research, Whiteshell Labs., Pinawa, MB (Canada)); Choi, J.W. (Korea Atomic Energy Research Inst., Daejeon (Korea, Republic of))

    1994-01-01

    Diffusion coefficients are important parameters for predicting migration rates of contaminants through earthen barrier materials used in many waste containment strategies. Apparent diffusion coefficients, D, were measured for Tc and I in compacted 1:3 mixtures of Lake Agassiz clay and crushed granite. Technetium-99 and [sup 129]I are two of the most important radioisotopes present in nuclear fuel waste. Lake Agassiz clay is a glacial lake clay composed principally of smectite, illite, quartz and kaolinite. Before being mixed with clay, crushed granite was separated into the following particle size fractions: <150, 150 to 300, 300 to 850, 850 to 2000, and 2000 to 4750 [mu]m. The dry density of the mixes was about 2 Mg/m[sup 3] and they were saturated with a Na-Ca-Cl-dominated synthetic groundwater solution having an effective ionic strength of 220 mol/m[sup 3]. The mean D values (n = 4) for Tc in the mixes ranged from 20 [mu]m[sup 2]/s when the granite particle size was 2000 to 4750 [mu]m to 0.19 [mu]m[sup 2]/s when it was <150 [mu]m. In clay alone, the mean D value was 59 [mu]m[sup 2]/s. The decrease in D with decreasing granite particle size is largely attributed to an increase in the extent of reduction of Tc(VII) to Tc(IV) and its subsequent sorption on Fe(III) oxyhydroxides present in granite. The reductants are probably Fe(II)-bearing minerals, such as magnetite, in granite. The finer the granite particle size, the greater the reactive surface area. For I, clay controls the diffusion process and granite is essentially inert filler. The mean D values for I are about 3 [mu]m[sup 2]/s in all cases. The results show that, depending on the environmental conditions and the nature of the diffusant, crushed granite in compacted clay-based barriers can markedly slow mass transport. (orig.)

  7. Earth's youngest exposed granite and its tectonic implications: the 10-0.8 Ma Kurobegawa Granite.

    Science.gov (United States)

    Ito, Hisatoshi; Yamada, Ryuji; Tamura, Akihiro; Arai, Shoji; Horie, Kenji; Hokada, Tomokazu

    2013-01-01

    Although the quest for Earth's oldest rock is of great importance, identifying the youngest exposed pluton on Earth is also of interest. A pluton is a body of intrusive igneous rock that crystallized from slowly cooling magma at depths of several kilometers beneath the surface of the Earth. Therefore, the youngest exposed pluton represents the most recent tectonic uplift and highest exhumation. The youngest exposed pluton reported to date is the Takidani Granodiorite (~ 1.4 Ma) in the Hida Mountain Range of central Japan. Using LA-ICP-MS and SHRIMP U-Pb zircon dating methods, this study demonstrates that the Kurobegawa Granite, also situated in the Hida Mountain Range, is as young as ~ 0.8 Ma. In addition, data indicate multiple intrusion episodes in this pluton since 10 Ma with a ~ 2-million-year period of quiescence; hence, a future intrusion event is likely within 1 million years.

  8. P-T-X conditions of symplectite formation in the eclogites from the Western Gneiss Region (Norway).

    Science.gov (United States)

    Bigge, Nils; Martin, Céline; Harlow, George

    2016-04-01

    Symplectitic intergrowths of sodic plagioclase + diopside ± amphibole that replace omphacite are commonly found in eclogites. The role of an aqueous fluid as a catalyst of the symplectite formation process has now been demonstrated, but the origin of that fluid is still debated. In the Western Gneiss Region (Norway), basaltic eclogites are found as meter- to kilometer-size lenses embedded within the surrounding gneiss, and many of these display symplectite replacements. X-ray maps of the major elements were acquired by EMPA on six eclogites samples from four locations in the Western Gneiss Region. These maps were processed with XMapTools software to (i) calculate mass balance based on local equilibrium and (ii) estimate the P-T conditions of symplectite formation. One sample shows symplectite with only plagioclase and diopside, whereas the five other samples also contain amphibole lamellae. Kelyphite (intergrowths of amphibole and plagioclase around garnet) is also present in those five samples. Mass balance calculations derived from the standardized X-ray maps reveal that symplectite can form either in a closed (i.e., no influx of an external fluid) or open (i.e., influx of an external fluid) system, but open system behavior is dominant (five samples). The only sample showing symplectite formation in a closed system likely depended on the OH component of the phengite to catalyze the reaction. The estimated P-T paths for the four locations are similar: Symplectite formation is initiated in eclogite facies (20-15 kbar and 650-750 °C), and continues toward amphibolite facies which is indicated by kelyphite formation (15-9 kbar and 500-700 °C). The combination of these data with existing P-T estimates from the same areas, for both peak eclogite and amphibolite, shows that symplectites record the path between eclogite- and amphibolite-facies conditions, when plagioclase becomes stable.

  9. GRANITE CUTTING WASTE: TECHNOLOGICAL INNOVATION FOR THE FINAL DESTINATION

    Directory of Open Access Journals (Sweden)

    Joner Oliveira Alves

    2015-06-01

    Full Text Available The granite processing market is one of the most promising business areas of the mineral sector, with an average growth of the world production of about 6% per year. The granite extraction generates residues in the form of powder rock of 20-25 wt.% of the total benefited. The granite dust must be carefully managed since it can cause siltation of rivers and human health risks. This paper presents two routes for the final destination of this waste: the vitrification process aiming the production of fibers for thermo-acoustic insulation, and the magnetic separation in order to recover the steel grit. Results showed that the forms of treatments presented are economically and ecologically viable since they represent a cost reduction in the waste disposal, and also provide the production of new materials with commercial value.

  10. Magnetic Properties of Hydrothermalized A-type Red Granites

    Science.gov (United States)

    Trindade, R. I. F.; Nédélec, A.; Peschler, A.; Archanjo, C. J.; Poitrasson, F.; Bouchez, J. L.

    Hydrothermalized A-type granites are commonly identified by their pink to red-brick colour attributed to tiny flakes of hematite in the alkali feldspars. These inclusions can be of interest in magnetic studies, but their timing and process of formation are still unclear. Formation of chlorite after biotite is the commonest effect of hydrother- malization and may occur quite early after crystallization due to late-magmatic or externally-derived fluids. The reddish colour appears at a later stage. Five cases of A-type granites were investigated for their magnetic mineralogy and properties. The selected cases range from nearly unmodified granites (Panafrican stratoid granites of Madagascar) to strongly hydrothermalized ones (Meruoca, Brazil; Tana, Corsica); in- termediate cases are : Mount Scott (Oklahoma), Bushveld (granitic core kindly pro- vided by R.G. Cawthorn) and. Hydrothermal alteration is often associated to a de- crease of the magnetic susceptibility magnitude (K) and of the anisotropy degree (P). It also strongly affects the rockt's bulk coercivity parameters, since alteration changes the relative amounts of coarse-grained primary magnetite, fine-grained PSD to SD sec- ondary magnetite, and hematite. Correspondingly, most samples plot away from the magnetite trend in the Dayt's diagram, but the different groups identified after coer- civity parameters do not directly correlate with whole-rock colour. In addition, IRM- acquisition curves and thermal demagnetization of tri-axial IRM show that hematite occurs in almost all analysed samples despite their colour. Various hematite coercivity ranges are also evidenced. In fact, hematite can be formed either in feldspar crys- tals or after magnetite. Tiny hematite within feldspars can appear either by exsolu- tion process or, more likely, by precipitation from a fluid phase. For these reasons, hematite inclusions may carry a remanence acquired shortly after granite crystalliza- tion or, conversely, a recent

  11. Granite microcracks: Structure and connectivity at different depths

    Science.gov (United States)

    Song, Fan; Dong, Yan-Hui; Xu, Zhi-Fang; Zhou, Peng-Peng; Wang, Li-Heng; Tong, Shao-Qing; Duan, Rui-Qi

    2016-07-01

    Granite is one rock type used to host high-level radioactive waste repositories, and the structure of microcracks in the rock can influence its hydraulic characteristics. Thus, a quantitative analysis of granite microcracks is relevant for understanding the hydrogeological characteristics of the rocks surrounding geological repositories. The analysis can also contribute scientific data to a seepage model for low permeability rocks and materials with microscopic pores. In this study, seven granite core samples were drilled from different depths up to 600 m in Alxa, Inner Mongolia, China. Using a grid survey method and image processing technology, micrographs were converted into binary images of microcracks. The geometric parameters of the microcracks, including their quantity, width, cranny ratio, crack intersections and dimensional parameters of the fracture network, were analyzed in order to fully describe their spatial distribution. In addition, the morphological characteristics and elemental compositions of the microcracks were analyzed by scanning electron microscopy energy dispersive X-ray analysis (SEM-EDS), and the natural moisture content was also determined through heated. Finally, two-dimensional microcrack network seepage models of the granite samples were simulated using the Lattice Boltzmann method (LBM), which revealed the influence of the microcrack structure on their connectivity. The results show that the growth and development of microcracks in the granite samples generally decreases as sampling depth increases in this study area. Connectivity is positively correlated with a number of the geometric parameters: the quantity of microcracks, the cranny ratio, the number of crack intersections and dimensional parameters of the fracture network, which is revealed in the two-dimensional microcrack network seepage models for these granite samples.

  12. Threshold Differences on Figure and Ground: Gelb and Granit (1923)

    Science.gov (United States)

    Kinateder, Max

    2017-01-01

    In 1923, Gelb and Granit, using a method of adjustment for a small red light, reported a lower threshold for the target when presented on a ground region than on an adjacent figural region. More recent work in perceptual organization has found precisely the opposite—a processing advantage seems to go to items presented on the figure, not the ground. Although Gelb and Granit continue to be cited for their finding, it has not previously been available as an English translation. Understanding their methodology and results is important for integrating early Gestalt theory with more recent investigations. PMID:28286640

  13. The Swedish Bohus granite - a stone with a fascinating history

    Science.gov (United States)

    Schouenborg, Björn; Eliasson, Thomas

    2015-04-01

    One of the most well-known and well spread Swedish stone types used as building stones is the Bonus granite. It outcrops in an area north of Gothenburgh (SW Sweden), along the coastline, approximately 35 km wide and 85 km long. The granite continues into Norway as the Iddefjord granite. The Bohus granite is one of Sweden's youngest granites. Isotopic dating shows that the magma cooled at about 920 M years ago and thus marking the end of the Sveconorwegian orogoney. It is a composite granite massif area with several granitic intrusions but with rather homogeneous mineralogy. However, colour and texture varies quite a lot and the colour ranges from red to reddish grey although some pure grey varieties occur sparsely. The grain size ranges from medium grained to coarse grained and even with some porphyric parts. Quarrying in an industrial scale started 1842. The merchant A C Kullgren opened the first quarry and produced stones for the construction of the 86 km long Trollhättan channel connecting lake Vänern and the Atlantic ocean in the SW Sweden The stone was used for constructing harbors and wharves along the channel. Several quarries opened in the late 1800 around 1870 - 1890 and the export increased steadily with deliveries to Germany, Denmark, Holland, England and even to South America. The stone industries in Bohuslän (Bohus county), at its peak in 1929, engaged around 7 000 employees. During the depression in 1930 almost all of them became unemployed. However, as a curiosity, production and export continued to Germany for construction of Germania, the future World capital city ("Welthauptstadt Germania"), planned by Adolf Hitler and Albert Speer. About 500 stone workers were kept employed for this project during the late thirties. Today several varieties are still produced: Evja/Ävja, Tossene, Brastad, Näsinge, Broberg, Nolby, Allemarken and Skarstad. However, the number of stone workers is far from that of the early 1900. The Swedish production is mainly

  14. Hercynian Granite and Related Mineralisation in Beni Snouss, Western Algeria

    Science.gov (United States)

    Nacera, Hadj Mohamed; Abdelhak, Boutaleb

    2016-10-01

    The purpose of this research is to describe the mineralisation related to the Hercynian granite located in western Algeria by combining geologic, tectonic, mineralogical and fluid inclusion studies. Quartz veins bearing sulphides occur in close spatial association with granitoids, which, representing hydrothermal activities associated with them. Visible but rare gold occurs in a very small quantity connected with arsenopyrite. Barite veins and stock works are developed in the granites where are observed at Mallal and Bouabdous. The vein varies in thickness from a few centimetres up to 2 meters, and their length varies from 10 up to up 100 m. Most of veins are N50 - N75 and 60 to 90 dip.

  15. Small scale heterogeneity of Phanerozoic lower crust: evidence from isotopic and geochemical systematics of mid-Cretaceous granulite gneisses, San Gabriel Mountains, southern California

    Science.gov (United States)

    Barth, A.P.; Wooden, J.L.; May, D.J.

    1992-01-01

    An elongate belt of mid-Cretaceous, compositionally banded gneisses and granulites is exposed in Cucamonga terrane, in the southeastern foothills of the San Gabriel Mountains of southern California. Banded gneisses include mafic granulites of two geochemical types: type 1 rocks are similar to high Al arc basalts and andesites but have higher HFSE (high-field-strength-element) abundances and extremely variable LILE (largeion-lithophile-element) abundances, while type 2 rocks are relatively low in Al and similar to alkali rich MOR (midocean-ridge) or intraplate basalts. Intercalated with mafic granulites are paragneisses which include felsic granulites, aluminous gneisses, marble, and calc-silicate gneisses. Type 1 mafic granulites and calcic trondhjemitic pegmatites also oceur as cross-cutting, synmetamorphic dikes or small plutons. Small-scale heterogeneity of deep continental crust is indicated by the lithologic and isotopic diversity of intercalated ortho-and paragneisses exposed in Cucamonga terrane. Geochemical and isotopic data indicate that K, Rb, and U depletion and Sm/Nd fractionation were associated with biotite +/- muscovite dehydration reactions in type 1 mafic granulites and aluminous gneisses during high-grade metamorphism. Field relations and model initial isotopic ratios imply a wide range of protolith ages, ranging from Early Proterozoic to Phanerozoic. ?? 1992 Springer-Verlag.

  16. Heat focussing, granite genesis and inverted metamorphic gradients in continental collision zones

    Science.gov (United States)

    Jaupart, Claude; Provost, Ariel

    1985-05-01

    The thermal conductivity of sedimentary rocks is usually much lower than that of crystalline rocks, gneisses and granites. Continental collision zones are characterized by large-scale thrusts which superpose crystalline basement and sedimentary layers. This leads to heat refraction effects of significant magnitude. Sedimentary layers act as a barrier to the transport of heat. We show that the peculiar geometry of a gently sloping sedimentary layer thrust into more conductive rocks is very efficient in diverting the vertical flux of heat. Temperatures can vary by more than 50% along the horizontal and reach a marked maximum at the top of crystalline layers. These results are in general agreement with the main features of orogenic belts as exemplified by the Himalayas. They explain why the young leucogranites of the Main Central Thrust (MCT) are confined to a narrow belt at the top of the basement slab. They also account for the inverted metamorphic gradient observed there. In a crustal accretionary wedge, folding and thrusting modify the structure of the upper crust, by thickening the sedimentary cover and by introducing sedimentary rocks at depth. This leads to high temperatures at shallow depths in specific places. Les zones de collision continentale se caractérisent par de grands chevauchementsàfaible pendage qui empilent les unes sur les autres des couches de socle cristallin et des couches sédimentaires. Cette structure particulière engendre d'importants effets de réfraction thermique. En effet, leur conductibilitéthermiqueétant normalement bien plus faible que celle des roches cristallines, les formations sédimentaires font office de barrières pour le transfert thermique: le flux de chaleur se trouve fortement dévié. Dans un plan horizontal, la température peut varier de plus de 50%, les maximaétant situésàl'interface supérieur des dalles cristallines. En ces endroits précis, les isothermes profonds remontent très significativement. Ces r

  17. Chemical Variations in a Granitic Pluton and Its Surrounding Rocks.

    Science.gov (United States)

    Baird, A K; McIntyre, D B; Welday, E E; Madlem, K W

    1964-10-09

    New techniques of x-ray fluorescence spectrography have provided, for the first time, abundant data regarding chemical variability of granitic rocks on different scales. The results suggest that current designs of sampling plans for trend surface analysis should be modified; in particular several specimens, preferably drillcores, may be required at each locality.

  18. Etude de la diagraphie neutron du granite de Beauvoir. Effet neutron des altérations et de la matrice du granite. Calibration granite. Porosité totale à l'eau et porosité neutron Analysis of the Beauvoir Granite Neutron Log. Neutron Effect of Alterations and of the Granite Matrix. Granite Calibration. Total Water Porosity and Neutron Porosity

    Directory of Open Access Journals (Sweden)

    Galle C.

    2006-11-01

    Full Text Available Cet article rend compte des travaux effectués sur la porosité du granite de Beauvoir (Sondage GPF 1 d'Echassières, Massif Central français. L'objectif de notre étude est de pouvoir obtenir des valeurs représentatives de la saturation en eau (porosité totale à l'eau n du granite de Beauvoir à partir des mesures de porosité neutron PorositéN (diagraphie neutron BRGM sans avoir recours aux mesures sur carottes. Notre démarche est expérimentale et nous avons tenté d'approfondir certains problèmes liés à l'utilisation de la diagraphie neutron dans une roche granitique. Deux facteurs principaux conditionnent la réponse neutron : la concentration en hydrogène de la formation (eau libre et eau de constitution de certains minéraux et la présence d'éléments absorbeurs à forte section de capture comme le gadolinium, le cadmium, le bore, . . . et dans le cas du granite de Beauvoir, le lithium. A partir des mesures de porosité totale à l'eau n sur carottes, des essais de pertes au feu sur poudre qui nous permettent de déterminer la porosité neutron liée à l'eau de constitution PorositéN(OH- et des analyses chimiques avec lesquelles nous évaluons la porosité neutron thermique PorositéN(ox (Programme SNUPAR, Schlumberger liée à la capture neutronique, nous reconstituons la porosité neutron totale PorositéNR du granite de Beauvoir. Pour 7 échantillons caractéristiques du granite de Beauvoir, nous réalisons grâce à ces résultats une nouvelle calibration du taux de comptage neutron initial corrigé du gradient thermique et de l'effet de trou. Grâce à cette opération, il est possible de déterminer, pour les échantillons traités, la porosité neutron du granite avec une calibration granite (PorositéNg et non calcaire (PorositéNc. La connaissance de l'effet neutron de la matrice nous permet enfin d'évaluer la teneur en eau du granite (porosité totale à l'eau et de comparer celle-ci avec la porosité mesurée sur

  19. Fracture controls on valley persistence: the Cairngorm Granite pluton, Scotland

    Science.gov (United States)

    Hall, A. M.; Gillespie, M. R.

    2016-12-01

    Valleys are remarkably persistent features in many different tectonic settings, but the reasons for this persistence are rarely explored. Here, we examine the structural controls on valleys in the Cairngorms Mountains, Scotland, part of the passive margin of the eastern North Atlantic. We consider valleys at three scales: straths, glens and headwater valleys. The structural controls on valleys in and around the Cairngorm Granite pluton were examined on satellite and aerial photographs and by field survey. Topographic lineaments, including valleys, show no consistent orientation with joint sets or with sheets of microgranite and pegmatitic granite. In this granite landscape, jointing is not a first-order control on valley development. Instead, glens and headwater valleys align closely to quartz veins and linear alteration zones (LAZs). LAZs are zones of weakness in the granite pluton in which late-stage hydrothermal alteration and hydro-fracturing have greatly reduced rock mass strength and increased permeability. LAZs, which can be kilometres long and >700 m deep, are the dominant controls on the orientation of valleys in the Cairngorms. LAZs formed in the roof zone of the granite intrusion. Although the Cairngorm pluton was unroofed soon after emplacement, the presence of Old Red Sandstone (ORS) outliers in the terrain to the north and east indicates that the lower relief of the sub-ORS basement surface has been lowered by 1 km of vertical erosion and for 400 Myr. This valley persistence is a combined product of regionally low rates of basement exhumation and of the existence of LAZs in the Cairngorm pluton and sub-parallel Caledonide fractures in the surrounding terrain with depths that exceed 1 km.

  20. The Formation of Yanshanian Granitic Magma in Dabie Mountains:Dehydration or Aquifer Melting with Tiantangzhai and Jiuzihe Granites as Examples

    Institute of Scientific and Technical Information of China (English)

    WANG Qiang; ZHAO Zhenhua; QIU Jiaxiang; WANG Renjing; XU Jifeng

    2001-01-01

    There are large-areas of late Yanshanian granites in the Dabie Orogen, but the formation mode of the relevant granitic magma is still under discussion. Taking the typical Yanshanian granites in the North Dabie Block The TG and JG as examples, the Writers endeavor to discuss contain aspects of the formation mode of the granitic magma by studying the characteristics of the chemical compositions of biotite and amphibole of the granites and petrological features of enclaves in the intrusions, in the light of recent results of experimental petrology on dehydration melting and aquifer melting. It is suggested that: (1) Some biotites in the Tiantangzhai and the JGs and their enclaves were residual minerals; (2) Some of the amphiboles could be new-born minerals, and others, residual ones.(3) the banded bodies in granites were residuals of anatexis. (4) The TG and JG were formed by aquifer melting, and the South Dabie Block could be the important source region of water.

  1. Numerical experiments on the role of buoyancy and rheology during the formation of extension-driven gneiss domes

    Science.gov (United States)

    Korchinski, Megan; Rey, Patrice; Teyssier, Christian; Whitney, Donna; Mondy, Luke

    2016-04-01

    Domal structures that are cored with crystallized partially melted crustal rocks are ubiquitous features in active and exhumed orogens. The exposure of these gneiss/migmatite domes at the Earth's surface represents an opportunity to study the mechanisms of flow within the deep crust, and the mode of emplacement of high-pressure rocks into the shallow crust. End-member gneiss dome types include (1) extension-driven domes that core metamorphic core complexes, and (2) buoyancy-driven domes that are exhumed by diapiric flow. Numerical models are ideally suited to test the relative roles of buoyancy and extension-driven mechanisms in dome dynamics, and therefore to explore the interaction of physical parameters involved in doming. To that end, this research utilizes a 2D visco-plastic thermomechanical modeling framework to undertake a parametric numerical experiment where the density (range of 2700-3100 kg.m3) and viscosity (range of 1E19-1E21 Pa.s) of the lower crust are systematically varied. The style and timing of "intrusion" of partially molten lower crust into non-molten lower crust is similar for densities of 2700-3100 kg.m3 across two lower crustal viscosities tested here (1E19 Pa.s, 1E21 Pa.s). However, dome development and upwards flow of lower crust material for a relatively high-density, middle-viscosity lower crust (2900-3100 kg.m^3; 1E20 Pa.s) involves a significant upward translation of the Moho, relative to the low-density, middle-viscosity model results. In addition, the high-density, middle-viscosity model shows a decrease in the volume of partial melt in the lower crust, and distributed brittle faulting in the upper crust. Thus, this experiment suite illustrates that variations in density and viscosity of the lower crust influence (1) faults distribution in the upper crust, (2) flow patterns within the lower crust, (3) upward translation of the solidus into the lower crust, and (4) upward displacement of the Moho. The style of extension within the

  2. A hot spring in granite of the Western Tianshan, China

    Energy Technology Data Exchange (ETDEWEB)

    Bucher, Kurt [Institute of Mineralogy, Albertstr.23 b, D-79104 Freiburg (Germany)], E-mail: bucher@uni-freiburg.de; Zhang Lifei [School of Earth and Space Sciences, Peking University, Beijing, 100871 (China); Stober, Ingrid [Institute of Mineralogy, Albertstr.23 b, D-79104 Freiburg (Germany)

    2009-03-15

    The western Tianshan range is a major Cenozoic orogenic belt in central Asia exposing predominantly Paleozoic rocks including granite. Ongoing deformation is reflected by very rugged topography with peaks over 7000 m high. Active tectonic deformation is tied to an E-W trending fracture and fault system that sections the mountain chain into geologically diverse blocks that extend parallel to the orogen. In the Muzhaerte valley upwelling hot water follows such a fault system in the Muza granite. About 20 L min{sup -1} Na-SO{sub 4}-Cl water with a temperature of 55 deg. C having a total mineralization of about 1 g L{sup -1} discharge from the hot spring. The water is used in a local spa that is frequented by the people of the upper Ili river area. Its waters are used for balneological purposes and the spa serves as a therapeutic institution. The major element composition of the hot water is dominated by Na and by SO{sub 4} and Cl, Ca is a minor component. Dissolved silica (1.04 mmol L{sup -1}) corresponds to a quartz-saturation temperature of 116 deg. C and a corresponding depth of the source of the water of about 4600 m. This temperature is consistent with Na/K and Na/Li geothermometry. The water is saturated with respect to fluorite and contains 7.5 mg L{sup -1} F{sup -} as a consequence of the low Ca-concentration. The water is undersaturated with respect to the primary minerals of the reservoir granite at reservoir temperature causing continued irreversible dissolution of granite. The waters are oversaturated with respect to Ca-zeolite minerals (such as stilbite and mesolite), and it is expected that zeolites precipitate in the fracture pore space and in alteration zones replacing primary granite. The stable isotope composition of O and H supports a meteoric origin of the water. The Cl/Br mass ratio of 1500 suggests that the salinity results from halite dissolution. Salts leached from powders of Muza granite show the same Cl/Br signature as the hot spring water

  3. Zarzalejo granite (Spain). A nomination for 'Global Heritage Stone Resource'

    Science.gov (United States)

    Freire Lista, David Martin; Fort, Rafael; José Varas-Muriel, María

    2015-04-01

    Zarzalejo granite is quarried in the Sierra de Guadarrama (Spanish Central System) foothills, in and around Zarzalejo village, in the province of Madrid, Spain. It is an inequigranular monzogranite medium-to-coarse grained, with a slight porphyritic texture (feldspar phenocrysts) and mafic micro-grained enclaves. In this abstract the candidacy of Zarzalejo granite as a "Global Heritage Resource Stone" (GHSR) is presented. This stone ideally fits the newly proposed designation as it has been used in many heritage buildings and its good petrophysical properties and durability have allowed well preserved constructions such as a Roman road, San Pedro Church in Zarzalejo (1492), Descalzas Reales Monastery in Madrid (1559-1564) and the San Lorenzo del Escorial Royal Monastery (1563-1584), to be declared a World Heritage Site by UNESCO. This level of construction has been a landmark in the extraction and proliferation of historic quarries created due to the high demand that such colossal monuments and buildings with granite, have required for their construction. In the mid-20th century, More, Zarzalejo granite has also been used in restoration works including the Royal Palace and the Reina Sofía Museum (2001-2005), both buildings in Madrid, Spain. Extraction of granite ashlars from tors has been a very frequent activity in the Zarzalejo neighbourhood until mid-twentieth century. So there is also a need to preserve these historic quarries. This type of stone has created a landscape that has been preserved as an open-air museum today where you can see the marks left in the granite due to historic quarry operations. The granite industry has been one of the main pillars of the Zarzalejo regional economy. For centuries, the local community have been engaged in quarrying and have created a cultural landscape based on its building stone. A quarryman monument has been erected in Zarzalejo in honor of this traditional craft as well as an architecture museum at San Lorenzo del

  4. Subsolidus physical and chemical mixing of granite and gabbro during mylonitization, South Victoria Land, Antarctica

    Science.gov (United States)

    Rachel Walcott, C.; Craw, Dave

    1993-12-01

    At Dromedary Massif, Southern Victoria Land, Antarctica, a suite of coarse-grained granite dykes cross-cuts a gabbro pluton which has been partially metamorphosed at amphibolite facies. During regional deformation, strain has been inhomogeneously distributed through the gabbro pluton and has been concentrated in granite dykes. In zones of relatively high strain, the granite dykes have developed a mylonitic fabric. A high strain gradient between granitic mylonite and metagabbroic host rock has induced isochemical mylonitization of the margin of the host. This grain size reduction allowed chemical diffusion between granitic and metagabbroic mylonites, resulting in a marginal zone of biotite-rich mylonite with intermediate composition. Biotite-rich mylonite decoupled from metagabbroic mylonite and flowed with granitic mylonite. Continued folding and transposition of granitic mylonite and biotite-rich mylonite has produced compositionally banded mylonite zones through thorough and irreversible mixing of the two lithologies.

  5. Experimental analysis on physical and mechanical properties of thermal shock damage of granite

    Directory of Open Access Journals (Sweden)

    He Xiao

    2017-01-01

    Full Text Available The purpose of this study was to explore the changes of mechanical and physical properties of granite under different thermal loading effects. Uniaxial compression experiments studying the rules of the influence of temperature load on mechanical properties of granite were carried out. After high-temperature heating at above 600 °C, granite tended to have stronger ductility and plasticity as well as declined peak stress and compressive strength. Thermogravimetry - differential scanning calorimetry (TG-DSC analysis results showed that, thermal load at different temperatures induced reactions such as water loss, oxidation and crystallization in the microstructure of granite, which led to physical changes of granite. Hence it is concluded that, heating can significantly weaken the mechanical performance of granite, which provides an important support for the optimization of heating assisted processing of granite. It also reveals that, heating assisted cutting technique can effectively lower energy consumption and improve processing efficiency.

  6. Alteration of granite stone used in building construction

    Directory of Open Access Journals (Sweden)

    Esbert Alemany, R. M.ª

    2007-12-01

    Full Text Available The article contains a synthesis of the different factors involved in the alteration of granite ashlars or cladding used in building construction. Emphasis is placed on the – primarily fissure-like – anisotropies often present in granite, which are usually related to the structural conditions of the quarry where it is mined. Such anisotropies condition the development of certain types of alterations that appear over time, particularly in ashlars. Stone petrography, particularly as regards the chemical composition of the minerals comprising granite, also govern its alteration. Moreover, the commercial term granite often includes other more alkaline rocks generically known as granitoids, whose alterability is higher than in granite per se. The values of some of the physical properties of these rocks, which must be quantified to evaluate their durability, are shown to differ in keeping with their anisotropy. Finally, the forms, causes and mechanisms involved in granite decay are reviewed in the context of its use in building construction.En el artículo se sintetizan los diversos aspectos que inciden en la alteración de las rocas graníticas, cuando estas se utilizan en los edificios, ya sea en forma de sillares o de losetas de revestimiento. Se hace especial hincapié en las anisotropías, fundamentalmente de carácter fisural que suelen presentar los granitos. Estas suelen estar relacionadas con las condiciones estructurales del yacimiento del cual proceden. Dichas anisotropías condicionan el desarrollo de determinadas formas de alteración que con el paso del tiempo se aprecian, sobre todo en los sillares. También se recuerda que la petrografía, y en especial la composición química de los minerales que componen las rocas graníticas, condicionan su alteración, y que dentro del término comercial granito se suelen incluir otras rocas más alcalinas denominadas genéricamente granitoides y más alterables que el granito sensu

  7. Petrography and geochemistry of metamafic rocks intercalated in gneisses from Goiás Magmatic Arc, region of Indiara (GO

    Directory of Open Access Journals (Sweden)

    Guillermo Rafael Beltran Navarro

    2015-03-01

    Full Text Available In Indiara region (GO, dozens of metamafic rocks lenses of various dimensions (metric to kilometric occur, intercalated in gneisses of the Goiás Magmatic Arc and oriented according to the direction of the main foliation (Sn. These lenses consist of amphibolite (amphibole schists and amphibolites, have chemical compositions of sub-alkaline basalts to andesitic basalts and sub-alkaline tholeiitic affinity. The distribution of major and trace elements, as well as rare earth elements (REE, suggests that these rocks are derived from a source with similar geochemical signature. The analyzed rocks are enriched in large ion litophile elements (Cs, Rb, Ba, K, Th and U in relation to elements of high field strength (Nb, Ta, Zr, Hf and Y and in relation to REE, Sr, P and Ti, showing weak to medium negative anomalies of Nb, Ta and P and suggesting that these rocks were generated in a magmatic arc environment.

  8. Tectonic Dynamic Metallization of Silver-Gold Hydrothermal Fluids in Proterozoic Gneiss Terrene Shear Zones, Suichang, Zhejiang, China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The Suichang mine is the largest silicified vein-type silver-gold mineralization system in Southeast China, whose ore bodies are controlled by shear zones developing in Lower Proterozoic gneiss terrene with initial migmatization, which is covered by Upper Jurassic and Lower Cretaceous volcanic rock system and cut by acidic igneous veins of Jurassic and Cretaceous. The conclusions are as follows: (1) The ore-forming fluid is defined as superhigh tectonic-metamorphic fluid on the base of: ① δ(D)-δ(18O) values; ② fluid inclusions; ③ trace elements of pyrite from ores. (2) The shear zone silicified orebodies occurred in Proterozoic, Jurassic and Cretaceous, which have been transformed in part by ore-bearing comb quartz vein of volcanism.

  9. Radon exhalation rates of some granites used in Serbia

    Directory of Open Access Journals (Sweden)

    Nikolić Mladen D.

    2015-01-01

    Full Text Available In order to address concern about radon exhalation in building material, radon exhalation rate was determined for different granites available on Serbian market. Radon exhalation rate, along with mass exhalation rate and effective radium content were determined by closed chamber method and active continuous radon measurement technique. For this research, special chambers were made and tested for back diffusion and leakage, and the radon concentrations measured were included in the calculation of radon exhalation. The radon exhalation rate ranged from 0.161 Bq/m2h to 0.576 Bq/m2h, the mass exhalation rate from 0.167 Bq/kgh to 0.678 Bq/kgh, while the effective radium content was found to be from 12.37 Bq/kg to 50.23 Bq/kg. The results indicate that the granites used in Serbia have a low level of radon exhalation.

  10. Cosmic Dust in Suzhou A-Type Granite

    Institute of Scientific and Technical Information of China (English)

    王尔康; 万玉秋; 朱政; 胡中为; 林承毅; 周剑雄; 倪邦发

    1994-01-01

    A large number of microspherules have been extracted from Suzhou A-type granite bymeans of heavy placer.Both natural surfaces and part sections of 539 microspherules have been observed bySEM.457 microspherules have been determined by EDX,with some of them by EPMA,XRD and INAA.The results suggest these spherules are of ablated cosmic dust.Among them silicate glassy microspheruleshave been highly enriched in REE and other lithophile refractory trace elements,and REE abundance patternfavors a meteoritic origin as a roughly flat distribution.Ringwoodite has been first found in these glassy mi-crospherules.The composition of these iron spherules is similar to those of the ablated cosmic dust from deepsea and polar ice.Some Fe-Ni spherules and spherules composed of troilite have also been found.This isprobably the first report on various types of cosmic dust extracted from granite.

  11. THERMAL STUDY ON THE GRINDING OF GRANITE WITH SUPERABRASIVE TOOLS

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In the present paer, a thermal study was conducted for the grinding of granite with diamond tools. Three types of grinding-straight surface grinding, deep grinding(circular sawing), and vertical spindle grinding-were studied. Some surface grinding tests were also conducted using a CBN(cubic boron nitride) wheel. Temperature distributions on the workpiece surface were measured using a foil thermocouple and the energy partition to the workpiece was estimated using a temperature matching method. The temperature for CBN surface grinding was found to be much higher than for diamond grinding. Energy partitions to the granite were 30%~36% for CBN surface grinding, 25%~32% for diamond surface grinding, about 53% for vertical spindle grinding, and 5.5%~9% for diamond deep grinding. The low energy partition value in deep grinding also suggested that more of the heat generated by grinding in this case can be conducted to the grinding tool and promote tool wear.

  12. Dynamic analysis of granite rockburst based on the PIV technique

    Institute of Scientific and Technical Information of China (English)

    Wang Hongjian; Liu Da’an; Gong Weili; Li Liyun

    2015-01-01

    This paper describes the deep rockburst simulation system to reproduce the granite instantaneous rock-burst process. Based on the PIV (Particle Image Velocimetry) technique, quantitative analysis of a rock-burst, the images of tracer particle, displacement and strain fields can be obtained, and the debris trajectory described. According to the observation of on-site tests, the dynamic rockburst is actually a gas–solid high speed flow process, which is caused by the interaction of rock fragments and surrounding air. With the help of analysis on high speed video and PIV images, the granite rockburst failure process is composed of six stages of platey fragment spalling and debris ejection. Meanwhile, the elastic energy for these six stages has been calculated to study the energy variation. The results indicate that the rockburst process can be summarized as:an initiating stage, intensive developing stage and gradual decay stage. This research will be helpful for our further understanding of the rockburst mechanism.

  13. Lower Granite Dam Smolt Monitoring Program, 1999 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Verhey, Peter; Morrill, Charles; Mensik, Fred

    1999-01-01

    The 1999 fish collection season at Lower Granite was characterized by high spring flows and spill, low levels of debris, cool water temperatures, increased hatchery chinook numbers, and an overall decrease in numbers of smolts collected and transported. A total of 5,882,872 juvenile salmonids were collected at Lower Granite. Of these, 5,466,057 were transported to release sites below Bonneville Dam, 5,232,105 by barge and 233,952 by truck. An additional 339,398 fish were bypassed back to the river. A total of 117,609 salmonids were examined in daily samples. Nine research projects conducted by four agencies impacted a total of 440,810 smolts (7.5% of the total collected) of which 247,268 were PIT tagged and 572 were recorded as incidental mortalities.

  14. Rapakivi granites in the geological history of the earth. Part 1, magmatic associations with rapakivi granites: Age, geochemistry, and tectonic setting

    Science.gov (United States)

    Larin, A. M.

    2009-06-01

    Rapakivi granites characteristic practically of all old platforms are greatly variable in age and irregularly distributed over the globe. Four types of magmatic associations, which include rapakivi granites, are represented by anorthosite-mangerite-charnockite-rapakivi granite, anorthosite-mangerite-rapakivi-peralkaline granite, gabbro-rapakivi granite-foidite, and rapakivi granite-shoshonite rock series. Granitoids of these associations used to be divided into the following three groups: (1) classical rapakivi granites from magmatic associations of the first three types, which correspond to subalkaline high-K and high-Fe reduced A2-type granites exemplifying the plumasitic trend of evolution; (2) peralkaline granites of the second magmatic association representing the highly differentiated A1-type reduced granites of Na-series, which are extremely enriched in incompatible elements and show the agpaitic trend of evolution; and (3) subalkaline oxidized granites of the fourth magmatic association ranging in composition from potassic A2-type granites to S-granites. Magmatic complexes including rapakivi granites originated during the geochronological interval that spanned three supercontinental cycles 2.7-1.8, 1.8-1.0 and 1.0-0.55 Ga ago. The onset and end of each cycle constrained the assembly periods of supercontinents and the formation epochs of predominantly anorthosite-charnockite complexes of the anorthosite-mangerite-charnockite-rapakivi granite magmatic association. Peak of the respective magmatism at the time of Grenvillian Orogeny signified the transition from the tectonics of small lithospheric plates to the subsequent plate tectonics of the current type. The outburst of rapakivi granite magmatism was typical of the second cycle exclusively. The anorthosite-mangerite-charnockite-rapakivi granite magmatic series associated with this magmatism originated in back-arc settings, if we consider the latter in a broad sense as corresponding to the rear parts of

  15. MULTIDISCIPLINARY APPROACH TO STUDY MIGMATITES: ORIGIN AND TECTONIC HISTORY OF THE NASON RIDGE MIGMATITIC GNEISS, WENATCHEE BLOCK, CASCADES CRYSTALLINE CORE, WA, USA

    Directory of Open Access Journals (Sweden)

    Stowell Harold H.

    2008-12-01

    Full Text Available The Nason Ridge Migmatitic Gneiss of the Cascades Core is a migmatitic unit comprising concordant pelitic schist and gneiss, amphibolite, and tonalite gneiss, and cross cutting tonalite, quartz-rich granitoid, and pegmatite. There are several generations of 'igneous' lithologies (leucosomes = tonalite, quartz-rich granitoid, and pegmatite some of which are concordant; others clearly crosscut the strongly deformed host rocks. The host rocks are interpreted to be Chiwaukum Schist with metasedimentary (pelitic schist and some gneiss and metavolcanic(amphibolites origins. Metamorphic fabric in the Nason Ridge Migmatitic Gneiss is characterized by preferred orientation of platy minerals (continuous schistosity, compositional layering, mineral lineations (elongate grains and grain aggregates, and non-coaxial deformational features (asymmetric augen, grain offsets,rotated porphyroblasts, etc.. Compositional layering is characterized by quartz-plagioclase lenses and patches (mm to cm scale and by large variations in biotite content. This composite fabric is faulted and folded by mesoscopic structures. The most strongly foliated leucosomes (gneissic tonalites are generally concordant with the regional trend of foliation, while weakly foliated leucosomes (tonalites and pegmatite veins crosscut host rock and tonalite gneisses. Thin melanosome layers (biotiteand amphibole schist are developed locally around quartz - plagioclase lenses and patches. Metamorphism in the Nason Ridge Migmatitic Gneiss and the nearby Chiwaukum Schist likely peaked after intrusion of the Mt. Stuart Batholith ca. 91-94 Ma. Peak temperatures and pressures for the Nason Ridge Migmatitic Gneiss in the Wenatchee Ridge and Pacific Crest areas were 650 - 720 °C and 6 - 9 kbar with a pressure increase of £ 2.0 kbar during metamorphism. Thermodynamic modeling indicates that hydrous partial melting would begin at ca. 660 °C and is relatively pressure independent. Field

  16. Lower Granite Dam Smolt Monitoring Program, 1998 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Verhey, Peter; Ross, Doug; Morrill, Charles (Washington Department of Fish and Wildlife, Olympia, WA)

    1998-12-01

    The 1998 fish collection season at Lower Granite was characterized by relatively moderate spring flows and spill, moderate levels of debris, cool spring, warm summer and fall water temperatures, and increased chinook numbers, particularly wild subyearling chinook collected and transported. The Fish Passage Center's Smolt Monitoring Program is designed to provide a consistent, real-time database on fish passage and document the migrational characteristics of the many stocks of salmon and steelhead in the Columbia Basin.

  17. Lower Granite Dam Smolt Monitoring Program; 1997 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Verhey, Peter; Witalis, Shirley; Morrill, Charles (Washington Department of Fish and Wildlife, Olympia, WA)

    1998-01-01

    The 1997 fish collection season at Lower Granite was characterized by high spring flows, extensive spill, cool spring and early summer water temperatures and comparatively low numbers of fish, particularly yearling chinook. The Fish Passage Center's Smolt Monitoring Program is designed to provide a consistent, real-time database of fish passage and document the migrational characteristics of the many stocks of salmon and steelhead in the Columbia Basin.

  18. Dose assessment associated with granite use in residential property

    Energy Technology Data Exchange (ETDEWEB)

    Leal, Andre Luiz do Carmo, E-mail: andre.leal@ifrj.edu.br [Instituto Federal do Rio de Janeiro (IFRJ), Sao Goncalo, RJ (Brazil); Lauria, Dejanira da Costa, E-mail: dejanira@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    The radioactivity levels in materials used as building materials have been reported in many countries and relatively high levels of radioactivity have been identified in some materials build (Beretka and Mathew, 1985; Pavlidou et al., 2006; Tzortzis et al., 2003 ; Al-Selah and Al-Berzan, 2007; Kitto et al.,2009 ; Myatt et al., 2010 ). Although is reported in the literature some studies on the levels of radionuclides in granites and the associated doses (Salas, 2003; Ahmed et al., 2006; Bonotto et al, 2009 ; Turhan, 2012; Anjos et al., 2005, 2012), most of assessed dose are related with external exposure data (Anjos et al., 2011, Llope, 2011 ). From the radionuclide concentrations in 10 samples of granite rock, this study evaluated the dose by inhalation of radon from the use of national granites as floor covering, according to the refresh rate of air, porosity, and radon emanation rate of diffusion coefficient by sensitivity analyzes, using the RESRAD-BUILD 3.5 code. As a result, it was found that the higher dose by radon inhalation was 0.058 mSv / year and the Rn-220 isotope is the largest contributor to this route of exposure. (author)

  19. Mechanical characteristics and microcosmic mechanisms of granite under temperature loads

    Institute of Scientific and Technical Information of China (English)

    XU Xiao-li; GAO Feng; SHEN Xiao-ming; XIE He-ping

    2008-01-01

    The relationships between mechanical characteristics of rock and microcosmic mechanism at high temperatures were investigated by MTS815, as well as the stress-strain behavior of granite under the action of temperatures ranging from room tem-perature to 1200 ℃. Based on a micropore structure analyzer and SEM, the changes in rock porosity and micro'structural mor-phology of sample fractures and brittle-plastic characteristics under high temperatures were analyzed. The results are as follows: 1) Mechanical characteristics do not show obvious variations before 800 ℃; strength decreases suddenly after 800 ℃ and bearing capacity is almost lost at 1200 ℃. 2) Rock porosity increases with rising temperatures; the threshold temperature is about 800 ℃;at this temperature its effect is basically uniform with strength decreasing rapidly. 3) The failure type of granite is a brittle tensile fracture at temperatures below 800 ℃ which transforms into plasticity at temperatures higher than 800 ℃ and crystal formation takes place at this time. Chemical reactions take place at 1200 ℃. Failure of granite under high temperature is a common result of thermal stress as indicated by an increase in the thermal expansion coefficient, transformation to crystal formation of minerals and structural chemical reactions.

  20. Lower Granite Dam Smolt Monitoring Program, 2000 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Morrill, Charles; Ross, Doug; Mensik, Fred

    2000-01-01

    The 2000 fish collection season at Lower Granite was characterized by lower than average spring flows and spill, low levels of debris, cool water temperatures, increased unclipped yearling and subyearling chinook smolts, and 8,300,546 smolts collected and transported compared to 5,882,872 in 1999. With the continued release of unclipped supplementation chinook and steelhead above Lower Granite Dam, we can no longer accurately distinguish wild chinook, steelhead, and sockeye/kokanee in the sample. Although some table titles in this report still show ''wild'' column headings, the numbers in these columns for 1999 and 2000 include wild and unclipped hatchery origin smolts. The increases over previous years reflect the increased supplementation. A total of 8,300,546 juvenile salmonids were collected at Lower Granite Dam. Of these, 187,862 fish were bypassed back to the river and 7,950,648 were transported to release sites below Bonneville Dam, 7,778,853 by barge and 171,795 by truck. A total of 151,344 salmonids were examined in daily samples. Nine research projects conducted by four agencies impacted a total of 1,361,006 smolts (16.4% of the total collection).

  1. Zircon SHRIMP U-Pb ages, Hf isotopic features and their geological significance of the Greater Himalayan Crystalline Complex augen gneiss in Gyirong Area, south Tibet%藏南吉隆地区早古生代大喜马拉雅片麻岩锆石SHRIMP U-Pb年龄、Hf同位素特征及其地质意义

    Institute of Scientific and Technical Information of China (English)

    王晓先; 张进江; 杨雄英; 张波

    2011-01-01

    藏南吉隆地区眼球状片麻岩是大喜马拉雅结晶岩系的一部分,其矿物组成为石英、斜长石、钾长石、黑云母和少量的白云母.片麻岩中的锆石具有核一边结构,由继承碎屑锆石核和具有同心环带结构的岩浆锆石边组成.SHRIMP U-Pb测年显示,边部岩浆锆石加权平均年龄为(498.9±4.4)Ma,表明片麻岩的原岩为早古生代的花岗岩,εHf加权平均值为-8.3±0.95,暗示片麻岩原岩为壳源,可能是印度大陆北部地壳部分熔融的产物.文中和现有的地质年代学数据表明,喜马拉雅造山带是一个复合造山带,经历了早古生代的造山作用,早古生代的喜马拉雅造山带是原特提斯洋向冈瓦纳大陆北缘俯冲的结果,是冈瓦纳大陆拼合之后在其边缘形成的安第斯型造山带,而不属于冈瓦纳超大陆聚合过程中陆一陆碰撞形成的泛非造山带的一部分.%The augen gneiss in the Gyirong Area of south Tibet belongs to the Greater Himalayan Crystalline Complex. It consists of quartz, plagioclase, K-feldspar, biotite and minor muscovite. Zircons of the augen gneiss have core-rim structures with inherited cores and magmatic rims indicated by concentric oscillatory zoning. The zircon rims gave a weighted mean age of 498. 9-t-4.4 Ma, hinting that the protoliths of the gneiss was early Paleozoic granite. The εHf ranges between - 13. 6 and - 4. 6 with a weighted mean value of - 8. 3 ± 0. 95. It implies that the source of granite came from crust, possibly resulted from partial melting of the crust in the northernmost margin of the India Crator. The zircon SHRIMP U-Pb ages, combined with the published geochronological data, demonstrate that the Himalaya is a composite orogenic belt, which underwent an early Paleozoic orogenesis. The early Paleozoic Himalaya was an Andean-type orogen after the Gondwana assemblying, which resulted from the subduction of the proto-Tethys ocean beneath the India Plate, rather than a Pan

  2. 富力矿立井花岗岩片麻岩涌水的治理和利用%Control and Utilization of Water Gushing in Granitic Gneiss Region of Shaft in Fuli Colliery

    Institute of Scientific and Technical Information of China (English)

    张鹏

    2014-01-01

    The paper introduces the design and implementation of utilization project of bedrock water gushing in shaft of Fuli Colliery ,which realizes the reutilization of high -quality mine water by modification on existing fa-cilities and creates great economic benefits for enterprise .%富力矿设计并实施的立井基岩涌水的再利用工程,充分地利用已有设施、进行改造,实现优质矿井水的再利用,为企业创造了较大的经济效益。

  3. Modeling and numerical analysis of granite rock specimen under mechanical loading and fire

    Institute of Scientific and Technical Information of China (English)

    Luc Leroy Ngueyep. Mambou; Joseph Ndop; Jean-Marie Bienvenu Ndjaka

    2015-01-01

    The effect of ISO 834 fire on the mechanical properties of granite rock specimen submitted to uniaxial loading is numerically investigated. Based on Newton’s second law, the rate-equation model of granite rock specimen under mechanical load and fire is established. The effect of heat treatment on the me-chanical performance of granite is analyzed at the center and the ends of specimen. At the free end of granite rock specimen, it is shown that from 20 ?C to 500 ?C, the internal stress and internal strain are weak; whereas above 500 ?C, they start to increase rapidly, announcing the imminent collapse. At the center of specimen, the analysis of the internal stress and internal strain reveals that the fire reduces the mechanical performance of granite significantly. Moreover, it is found that after 3 min of exposure to fire, the mechanical energy necessary to fragment the granite can be reduced up to 80%.

  4. Mineral inclusions in zircons of S-type granite: implications for high pressure metamorphism history of meta-sedimentary rocks in the Huai'an terrain, North China Craton

    Science.gov (United States)

    Wang, Haozheng; Zhang, Huafeng; Zhai, Mingguo; Cui, Xiahong

    2016-04-01

    The Paleoproterozoic evolution of North China Craton (NCC) arises many argument as geologists have different viewpoints on the distribution and metamorphic history of mafic granulites and granulite facies meta-sedimentary rocks. To provide more evidence of constraining the metamorphic history of granulite facies meta-sedimentary rocks, we select granulite facies meta-sedimentary rocks and co-existing S-type granite in the Huai'an terrain to make a deep research. Magmatic zircons derived from the S-type granite reveal the magmatic age of ˜1.95 Ga and metamorphic age of ˜1.85 Ga with ɛHf(t) value of -4.5 - -0.5. The ɛHf(t) value of S-type granite and relict of garnet-sillimanite gneiss suggest that the S-type granite is generated by melting of meta-sedimentary rocks. Zircons with ages of ˜1.95 Ga and ˜1.85 Ga have the mineral inclusions of Ky + Qz + Ru + Pl and these mineral inclusions are determined by method of Laser-Raman. The ˜1.95 Ga magmatic zircons with inclusions of Ky + Qz + Ru + Pl suggest that meta-sedimentary rocks have mineral assemblages Ky + Qz + Ru + Pl. However, previous studies in the Huai'an terrain showed that almost granulite facies metamorphic condition of meta-sedimentary rocks were regarded as medium pressure by considering the Sill + Grt + Bt + Pl + Qz + Ru + Kf. Presence of kyanite instructs that meta-sedimentary rocks may experience high pressure granulite facies metamorphism. According to pseudosection calculation by using effective bulk composition of garnet-sillimanite gneiss, mineral assemblage of Grt + Ky + Pl + Bt + Qz + Ru + Kf is regarded as the peak stage of high pressure metamorphism. This mineral assemblage is occurred at field of 1033 - 1123 K and 9 - 15 Kbar and the peak pressure is around 11 - 13 Kbar, determined by the XMg and XCa isopleths of garnet. This P-T result is consistent with peak condition of high pressure mafic granulite. Considering the ˜1.95 Ga magmatic age of S-type granite generated by decompression

  5. Igneous Hydrothermal Alteration and Ore-Forming Processes in the Land's End Granite, Nanjizal

    OpenAIRE

    Eik, Marte

    2015-01-01

    This study addresses the hydrothermal alteration and mineralization related to a system of tourmaline-quartz veins intersecting biotite-granite in Nanjizal, in the Land s End granites of the cornubian batholith. Nanjizal is an important site as it is one of the few locations in the southern segment of the Land s End Granite where magmatic-hydrothermal tin mineralizations have been mined. The aim is to identify the alteration-patterns and their correlation with hydrothermal ore-forming events ...

  6. Oxygen isotope studies of early Precambrian granitic rocks from the Giants Range batholith, northeastern Minnesota, U.S.A.

    Science.gov (United States)

    Viswanathan, S.

    1974-01-01

    Oxygen isotope studies of granitic rocks from the 2.7 b.y.-old composite Giants Range batholith show that: (1) ??(O18)quartz values of 9 to 10 permil characterize relatively uncontaminated Lower Precambrian, magmatic granodiorites and granites; (2) granitic rocks thought to have formed by static granitization have ??(O18)quartz values that are 1 to 2 permil higher than magmatic granitic rocks; (3) satellite leucogranite bodies have values nearly identical to those of the main intrusive phases even where they transect O18-rich metasedimentary wall rocks; (4) oxygen isotopic interaction between the granitic melts and their O18-rich wall rocks was minimal; and (5) O18/O18 ratios of quartz grains in a metasomatic granite are largely inherited from the precursor rock, but during the progression - sedimentary parent ??? partially granitized parent ??? metasomatic granite ??? there is gradual decrease in ??(O18)quartz by 1 to 2 permil. ?? 1974.

  7. The Role of Accessory Phases in the Sm-Nd Isotope Systematics of the Acasta Gneiss Complex

    Science.gov (United States)

    Bauer, A.; Fisher, C. M.; Vervoort, J. D.; Bowring, S. A.

    2015-12-01

    The Acasta Gneiss Complex (AGC) of the Slave Craton in the Northwest Territories, Canada, contains some of Earth's oldest continental crust. It is characterized by a range of compositionally diverse gneisses with crystallization ages of 3.3 to > 4.0 Ga1-5. The AGC has undergone a multistage history of metamorphism and deformation. Given these post-crystallization processes, the extent of Nd isotope heterogeneity suggested by published4-7 whole rock Sm-Nd analyses of these rocks has been called into question. Criticisms include the likelihood of mixed lithologies at the hand-sample scale and the potential for open-system behavior of the Sm-Nd isotopic system in these rocks. We obtained whole rock compositional, Sm-Nd and Lu-Hf isotope data paired with Hf in zircon and Nd in titanite and apatite data to further evaluate the isotope record, and use U-Pb and Lu-Hf of zircon as a basis for identifying mixed or complex samples. Preferential preservation of Lu-Hf over Sm-Nd isotope systematics in multiply deformed, complex rocks may be controlled by the minerals that dominate the Hf and Nd budgets, with the majority of the Hf effectively sheltered in zircon and the Nd largely hosted in accessory phases such as apatite and titanite. This composite dataset enables us to evaluate the possibility that Hf and Nd isotopic systematics have been decoupled in these samples that have such critical bearing on our understanding of early crust-forming processes. [1]Bowring and Williams (1999). CoMP, 134(1), 3-16. [2]Iizuka, T. et al. (2006) Geology, 34(4), 245-248. [3]Iizuka et al (2007). Precambrian Res, 153(3), 179-208. [4]Bowring et al. 1989. Nature, 340: 222-225. [5]Mojzsis et al. (2014). GCA, 133, 68-96. [6]Bowring and Housh (1995) Science 269, 1535-1540. [7]Moorbath et al (1997) Chem. Geol. 135, 213-231.

  8. The rapakivi granite plutons of Bodom and Obbnäs, southern Finland: petrography and geochemistry

    Directory of Open Access Journals (Sweden)

    Kosunen, P.

    1999-12-01

    Full Text Available The Obbnäs and Bodom granite plutons of southernmost Finland show the typical petrographic and geochemical features of the Proterozoic rapakivi granites in Finland and elsewhere: they cut sharply across the 1900 Ma Svecofennian metamorphic bedrock and have the geochemical characteristics of subalkaline A-type granites. The Bodom pluton is composed of porphyritic granites (hornblende-, hornblende-biotite-, and biotite-bearing varieties and an even-grained granite that probably represent two separate intrusive phases. This lithologic variation does not occur in the Obbnäs pluton, which is almost entirely composed of porphyritic hornblende-biotite granite that gradually becomes more mafic to the southwest. Three types of hybrid granitoids resulting from magma mingling and mixing occur on the southwestern tip of the Obbnäs peninsula. The Bodom granites are syenogranites, whereas the composition of the Obbnäs granite varies from syeno- to monzogranite. The main silicates of both the Bodom and Obbnäs granites are quartz, microcline, plagioclase (An1541, biotite (siderophyllite, and generally also amphibole (ferropargasite or hastingsite. Plagioclase-mantled alkali feldspar megacrysts are absent or rare. The accessory minerals are fluorite, allanite, zircon, apatite, and iron-titanium oxides; the Obbnäs granite also contains titanite. The Bodom and Obbnäs granites are metaluminous to weakly peraluminous, with average A/CNK of 1.00 and 1.05, respectively, have high Fe/Mg (average FeOtot/[FeOtot+MgO] is 0.94 for the Bodom and 0.87 for the Obbnäs granites, and high Ga/Al (3.78 to 5.22 in Bodom and 2.46 to 4.18 in Obbnäs. The REE contents are high with LREE-enriched chondrite-normalized patterns and moderate (Obbnäs to relatively strong (Bodom negative Eu-anomalies. The Obbnäs granite is enriched in CaO, TiO2, MgO, and FeO, and depleted in SiO2 and K2O compared to the Bodom granites. Also, there are differences in the Ba, Rb, and Sr contents of

  9. High Resolution Geophysical Characterization of Fractures within a Granitic Pluton

    Science.gov (United States)

    Pérez-Estaún, A.; Carbonell, R.

    2007-12-01

    The FEBEX underground gallery was excavated in the Aar Granite (Switzerland), a heterogeneous granite containing from very leucocratic facies to granodiorites. The geology of the gallery shows the existence of various sets of fractures with different attributes: geometry, kinematics, fracture infilling, etc. The study of the structural data, new observations on the FEBEX gallery itself and borehole televiewer data acquired in the newly drilled boreholes, have allowed to identify four sets of fractures. The first group of fractures has a typical distribution and characteristics of en echelon tension fractures and were formed in late magmatic stages, according with the paragenesis of the minerals that filled the craks. The main strike is around 300 (280-300). These fractures are deformed and displaced by the other group of faults. The second group corresponds to the lamprophyre dikes, of mantelic origin, with an orientation oblique to the tunnel, and slightly oblique to the first group of fractures (strike, 310-330). They were formed during an extension event well evidenced by their irregular margins and flame structures into the granite. The margins of these dikes show several reactivations as strike slip faults. Geophysical data has been acquired to characterized the fracture network of the surrounding volume within the FEBEX gallery. The geophysic data include new borehole logging such as Natural Gamma and Borehole Ground Penetrating radar. The processing and integration of these different data sets indicates that the GPR record can provide images of a third set of fractures, which are probably fluid filled. This set of fractures a subparallel to the tunnel axis and appear to intersect older boreholes which are nearly perpendicular to the axis of the FEBEX gallery.

  10. Brand umbrella and made in the international competitiveness of granite

    Directory of Open Access Journals (Sweden)

    Mª José García Rodríguez

    2010-12-01

    Full Text Available Spain, like Italy, the traditional leader of granite sector, has seen how China, India or Brazil have risen several positions on global production and export rankings. In a globalized context, it's necessary a good differentiation from international competitors, much more when this is a generic product that offers suitable prices and quality. One way to identify and differentiate it, is providing value by creating a brand. In this paper we study the utility of a strategy based on made in for Galicia, major production location for the industry in Spain; an alternative that seems attractive to enterprises, but whose implementation requires strong collaboration between firms and public and private institutions.

  11. Petrogenesis of shoshonitic granitoids, eastern India:Implications for the late Grenvillian post-collisional magmatism

    Institute of Scientific and Technical Information of China (English)

    B. Goswami; C. Bhattacharyya

    2014-01-01

    Many elongated, lenticular plutons of porphyritic granitoids are distributed mainly near the southern and northern margin of the Chhotanagpur Gneissic Complex (CGC) which belongs to the EW to ENEeWSW tending 1500 km long Proterozoic orogenic belt amalgamating the North and South Indian cratonic blocks. The late Grenvillian (1071 ? 64 Ma) Raghunathpur porphyritic granitoid gneiss (PGG) batholith comprising alkali feldspar granite, granite, granodiorite, tonalite, quartz syenite and quartz monzonite intruded into the granitoid gneisses of southeastern part of CGC in the Purulia district, West Bengal and is aligned with ENEeWSW trending North Purulia shear zone. Mineral chemistry, geochemistry, physical condition of crystallization and petrogenetic model of Raghunathpur PGG have been discussed for the first time. The petrographic and geochemical features (including major and trace-elements, mineral chemistry and 87Sr/86Sr ratio) suggest these granitoids to be classified as the shosh-onitic type. Raghunathpur batholith was emplaced at around 800 ?C and at 6 kbar pressure tectonic discrimination diagrams reveal a post-collision tectonic setting while structural studies reveal its emplacement in the extensional fissure of North Purulia shear zone. The Raghunathpur granitoid is compared with some similar granitoids of Europe and China to draw its petrogenetic model. Hybridi-zation of mantle-generated enriched mafic magma and crustal magma at lower crust and later fractional crystallization is proposed for the petrogenesis of this PGG. Mafic magma generated in a post-collisional extension possibly because of delamination of subducting slab. Raghunathpur batholith had emplaced in the CGC during the final amalgamation (w1.0 Ga) of the North and South Indian cratonic blocks. Granitoid magma, after its generation at depth, was transported to its present level along megadyke channel, ways within shear zones.

  12. Petrogenesis of shoshonitic granitoids, eastern India: Implications for the late Grenvillian post-collisional magmatism

    Directory of Open Access Journals (Sweden)

    B. Goswami

    2014-11-01

    Full Text Available Many elongated, lenticular plutons of porphyritic granitoids are distributed mainly near the southern and northern margin of the Chhotanagpur Gneissic Complex (CGC which belongs to the EW to ENE–WSW tending 1500 km long Proterozoic orogenic belt amalgamating the North and South Indian cratonic blocks. The late Grenvillian (1071 ± 64 Ma Raghunathpur porphyritic granitoid gneiss (PGG batholith comprising alkali feldspar granite, granite, granodiorite, tonalite, quartz syenite and quartz monzonite intruded into the granitoid gneisses of southeastern part of CGC in the Purulia district, West Bengal and is aligned with ENE–WSW trending North Purulia shear zone. Mineral chemistry, geochemistry, physical condition of crystallization and petrogenetic model of Raghunathpur PGG have been discussed for the first time. The petrographic and geochemical features (including major and trace-elements, mineral chemistry and 87Sr/86Sr ratio suggest these granitoids to be classified as the shoshonitic type. Raghunathpur batholith was emplaced at around 800 °C and at 6 kbar pressure tectonic discrimination diagrams reveal a post-collision tectonic setting while structural studies reveal its emplacement in the extensional fissure of North Purulia shear zone. The Raghunathpur granitoid is compared with some similar granitoids of Europe and China to draw its petrogenetic model. Hybridization of mantle-generated enriched mafic magma and crustal magma at lower crust and later fractional crystallization is proposed for the petrogenesis of this PGG. Mafic magma generated in a post-collisional extension possibly because of delamination of subducting slab. Raghunathpur batholith had emplaced in the CGC during the final amalgamation (∼1.0 Ga of the North and South Indian cratonic blocks. Granitoid magma, after its generation at depth, was transported to its present level along megadyke channel, ways within shear zones.

  13. Monazite trace-element and isotopic signatures of high-pressure metamorphism: examples from the Western Gneiss region, Norway

    Science.gov (United States)

    Holder, R. M.; Hacker, B. R.; Kylander-Clark, A. R.; Cottle, J. M.

    2014-12-01

    Monazite U-Pb and trace-element data were gathered using LASS (laser-ablation split-stream ICP-MS) from the Western Gneiss region, Norway, to investigate how trace-element composition can be used to differentiate (ultra)high-pressure monazite from low-pressure monazite. Monazite from six samples contains up to 3 % common Pb, despite high U and Th concentrations. These high common-Pb monazites are characterized by high Sr, weak Eu anomalies, and low Y+HREE. The high common-Pb and Sr abundances and the weak Eu/Eu* are interpreted to reflect the absence of feldspar at (U)HP, and the low Y+HREE content is attributed to fractionation of those elements into garnet. Sr and common Pb in monazite provide a tool for constraining the timing and duration of (U)HP metamorphism. More generally, Sr in monazite is a potential indicator of feldspar instability and may be applicable in other geologic settings, such as igneous systems in which the abundance of feldspar changes due to melting and crystallization. Sr is expected to be more reliable than Eu and Eu/Eu* as a tracer of feldspar stability, because Sr partitioning is less strongly influenced by oxidation state.

  14. Assessment of Blasting Performance Using Electronic Vis-à-Vis Shock Tube Detonators in Strong Garnet Biotite Sillimanite Gneiss Formations

    Science.gov (United States)

    Sharma, Suresh Kumar; Rai, Piyush

    2016-04-01

    This paper presents a comparative investigation of the shock tube and electronic detonating systems practised in bench blasting. The blast trials were conducted on overburden rocks of Garnet Biotite Sillimanite Gneiss formations in one of the largest metalliferous mine of India. The study revealed that the choice of detonating system was crucial in deciding the fragment size and its distribution within the blasted muck-piles. The fragment size and its distribution affected the digging rate of excavators. Also, the shape of the blasted muck-pile was found to be related to the degree of fragmentation. From the present work, it may be inferred that in electronic detonation system, timely release of explosive energy resulted in better overall blasting performance. Hence, the precision in delay time must be considered in designing blast rounds in such overburden rock formations. State-of-art image analysis, GPS based muck-pile profile plotting techniques were rigorously used in the investigation. The study revealed that a mean fragment size (K50) value for shock tube detonated blasts (0.55-0.59 m) was higher than that of electronically detonated blasts (0.43-0.45 m). The digging rate of designated shovels (34 m3) with electronically detonated blasts was consistently more than 5000 t/h, which was almost 13 % higher in comparison to shock tube detonated blasts. Furthermore, favourable muck-pile shapes were witnessed in electronically detonated blasts from the observations made on the dozer performance.

  15. Geotechnical Properties of Lateritic Overburden Materials on the Charnockite and Gneiss Complexes in Ipele-Owo Area, Southwestern Nigeria

    Directory of Open Access Journals (Sweden)

    G.P. Ojo

    2016-09-01

    Full Text Available The lateritic soils that overburden Charnockite and Gneiss Complexes in Ipele-Owo area of Ondo State, Nigeria are in great use for local construction. However, little is known of their engineering properties and suitability as sub-grade and sub-base materials for large-scale building and road construction. This work utilized standard geotechnical analytical techniques to examine and characterize these laterites. The results show that the soil is characteristically of a moderate strength based on the average California Bearing Ratio (CBR test result of 52.5%. The average particle size distribution indicates 11% fine grained sand, 2% medium grains, 12.4% coarse grains, 2% fine gravel and 74.6% clay-sized particles. The respective values of the linear shrinkage, liquid and plastic limits are 10.5%, 52.7% and 23.45%. The maximum dry density of the laterites is 1778.5 kg/m3 while the moisture content is 17.65%. It is therefore suggested that the Ipele-Owo laterites are suitable for use as sub-grade and sub-base construction materials since the geotechnical properties are fairly within the regulatory standards in Nigeria

  16. Tectonic uplift mechanism of the Goodenough and Fergusson Island gneiss domes, eastern Papua New Guinea: Constraints from seismic reflection and well data

    Science.gov (United States)

    Fitz, Guy; Mann, Paul

    2013-10-01

    The D'Entrecasteaux Island (DEI) gneiss domes are fault-bounded domes with ˜2.5 km of relief exposing ultrahigh-pressure (UHP) and high-pressure (HP) metamorphic gneisses and migmatites exhumed in an Oligocene-Miocene arc-continent collision and subduction zone subject to Late Miocene to Recent continental extension. To study the style of continental extension accompanying exhumation of the DEI gneiss domes, a grid of 1518 km of 2-D multichannel seismic (MCS) reflection data and well data is interpreted from the offshore areas surrounding the DEI, including the Trobriand basin and the Goodenough basin. The offshore study is combined with onshore geologic information to constrain the Oligocene to Recent tectonic evolution of the basins. MCS and well data are consistent with the Trobriand basin forming as a forearc basin caused by southward Miocene subduction at the Trobriand trench. At ˜8 Ma, the margin transitioned to an extensional tectonic environment. Since then, the Trobriand basin has subsided 1-2.5 km with few normal faults deforming the basin fill. South of the DEI, the Goodenough rift basin developed after extension began (˜8 Ma) with the hanging wall of the north-dipping Owen-Stanley normal fault bounding the southern margin of the basin. The lack of evidence of upper crustal extension accompanying subsidence in the Trobriand and Goodenough basins suggests depth-dependent lithospheric extension from 8 to 0 Ma has accompanied uplift of the DEI gneiss domes and supports schematic model of uplift of the DEI domes involving vertical exhumation of buoyant, postorogenic lower crust, far-field extension from slab rollback, and an inverted two-layer crustal density structure.

  17. New models for Paleoproterozoic orogenesis in the Cheyenne belt region: Evidence from the geology and U-Pb geochronology of the Big Creek Gneiss, southeastern Wyoming

    Science.gov (United States)

    Jones, D.S.; Snoke, A.W.; Premo, W.R.; Chamberlain, K.R.

    2010-01-01

    The disputed age of the deep crust of the Colorado Province is central to hypotheses for Paleoproterozoic crustal growth in the region. We studied the high-grade Big Creek Gneiss, southeastern Wyoming, as a potential exposure of pre-1780 Ma basement rocks. New geologic mapping and U-Pb geochronological data indicate that the Big Creek Gneiss exposes a deeper, but coeval, level of the Green Mountain arc relative to the predominantly supracrustal section to the west. The Big Creek Gneiss is composed of: supracrustal rocks; a ca. 1780 Ma Green Mountain arc-correlative, bimodal intrusive suite; a ca. 1763 Ma extensional(?) bimodal intrusive suite; and widespread ca. 1630 Ma pegmatitic leucogranite. The mafic member of the younger bimodal suite is documented here for the first time. U-Pb zircon ages from migmatite leucosomes indicate penetrative deformation of the Big Creek Gneiss at ca. 1750 Ma. We find that the postarc intrusive suite is mantle-involved, implying a second period of crustal growth. Shortening postdates arc magmatism by ~20 m.y., implying that termination of arc magmatism and accretion were separate events. Finally, criteria previously used to constrain the polarity of subduction for the Green Mountain arc are not reliable. We propose two competing models: (1) southward-dipping Green Mountain arc subduction (present coordinates), with slab breakoff-related magmatism following arc accretion; or (2) northward-dipping subduction, with extensional postarc magmatism. In both models, high-temperature deformation coincides with accretion along the Cheyenne belt, and extensional magmatism is an important component of crustal growth. We prefer the northward-dipping subduction model because it can be better integrated with regional tectonic events and published isotopic compositions of the igneous rocks. ?? 2010 Geological Society of America.

  18. Microstructural records of multiple retrograde local H2O supplement in the pelitic gneiss, Lützow-Holm Complex at Akarui Point, East Antarctica

    OpenAIRE

    Nakamura, Aya; Kitamura, Masao; Kawakami, Tetsuo

    2014-01-01

    The alkali-feldspar and biotite in the sillimanite-biotite-garnet gneiss from East Antarctica preserves characteristic microstructural evidence of multi-stage H2O supplement during the retrograde metamorphism. The first microstructural evidence is the "zoned feldspar, " in which the mesoperthitic zone, the anti-perthitic zone, and lamella-free plagioclase zone coexist within a single crystal. They are occasionally found next to biotite, and are always depleted in orthoclase (Or) component tow...

  19. Origin and tectonic implications of the ∼200 Ma, collision-related Jerai pluton of the Western Granite Belt, Peninsular Malaysia

    Science.gov (United States)

    Jamil, Azmiah; Ghani, Azman A.; Zaw, Khin; Osman, Syamir; Quek, Long Xiang

    2016-09-01

    Triassic granitoids (∼200-225 Ma) are widespread in the Western Belt of Peninsular Malaysia. The Main Range granite is the biggest batholith in the Western Belt composed of peraluminous to metaluminous granite and granodiorite and displays typical ilmenite-series characteristics. Jerai granitic pluton occurs at the northwestern part of the Main Range granite batholith. The Jerai granite can be divided into three facies: (i) biotite-muscovite granite; (ii) tourmaline granite; and (iii) pegmatite and aplopegmatite. Biotite-muscovite granite accounts for 90% of the Jerai pluton, and the rest is tourmaline granite. Geochemical data reveal that pegmatite and tourmaline granite are more differentiated than biotite-muscovite granite. Both pegmatite and tourmaline granite have a higher SiO2 content (70.95-83.94% versus 69.45-73.35%) and a more pronounced peraluminous character. The U-Pb zircon geochronology of the Jerai granite gave an age ranging from 204 ± 4.3 Ma, 205 ± 4 Ma and 205 ± 2 Ma for pegmatite biotite-muscovite granite and tourmaline granite, respectively. The biotite-muscovite Jerai granites are similar to S-type Main Range granite, but the tourmaline granite has a signature of late-stage hydrothermal fluid interaction such as tourmaline quartz pods, the accumulation of large pegmatitic K-feldspar, pronounced peraluminous character, higher SiO2 content. Age evidence of these two granitic facies suggest that they are from the same magma.

  20. Micro-area Chemical Composition and Preserved P-T Evolution Trace of Phengite in Albite Gneiss from the Donghai Ultrahigh-Pressure Metamorphic Area, East China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Study of micro-area chemical compositions indicates that phengite in albite gneiss from hole ZK2304 of the Donghai region has evident compositional zoning. SiO2 and tetrahedrally coordinated Si contents decrease, and Al2O3, AlIV and AlVI contents increase gradually from core to rim. However, K2O, MgO and FeO contents basically remain unchanged from core to rim. According to P-T estimates obtained from geothermometers and barometers, combined with previous experimental data, the core belt (micro-area I) of phengite was formed at T=637- 672° C and P=1.55- 1.73 GPa, and the transitional belt (micro-area II) of the phengite were formed at T=594- 654° C and P=1.35- 1.45 GPa. Towards the rim belt (micro-area III), the temperature decreased slightly, but the pressure decreased rapidly with T=542- 630° C and P=1.12- 1.19 GPa. The P-T evolution path recorded by the compositional zoning of phengite is characterized by significant near-isothermal decompression, revealing that the gneiss has undergone high-pressure-ultrahigh-pressure metamorphism. The compositional zoning of the phengite in the albite gneiss may have formed in the geodynamic process of rapid exhumation in the Sulu ultrahigh-pressure metamorphic belt.

  1. The Character and Emplacement Mechanism of Gneiss in Wugong Mountain%武功山片麻岩特征及侵位机制

    Institute of Scientific and Technical Information of China (English)

    张芳荣

    2000-01-01

    江西武功山片麻岩,前人存在两种观点:混合成因和岩浆成因。近年来,作者等人*通过1:5万区调,对武功山片麻岩取得了-些新的认识,认为武功山片麻岩是岩浆成因,属岩浆多次脉动形成的气球膨胀式强力侵位机制。%According to Wugong mountain' s gneiss in Jiangxi, the predecessors have two opinions: mix cause of forma-tion and magma cause of formation. Recently, the author and others have obtained some new knowledge of Wugongmountain' s gneiss by regional investigation ( 1: 5). They think Wugong mountain' s gneiss is magma cause of formation,which belongs to balloon's expansional mechanism of heavy emplacement formed by several pulses of magma.

  2. Elastic anisotropy of Tambo gneiss from Promontogno, Switzerland: a comparison of crystal orientation and microstructure-based modeling and experimental measurements

    Science.gov (United States)

    Vasin, R. N.; Kern, H.; Lokajíček, T.; Svitek, T.; Lehmann, E.; Mannes, D. C.; Chaouche, M.; Wenk, H.-R.

    2017-01-01

    SUMMARYFelsic and mafic gneisses constitute large proportions of the upper and lower continental crust. Gneisses often demonstrate high anisotropy of elastic properties associated with preferred orientations of sheet silicates. Here we study the elastic anisotropy of a sample of Tambo gneiss from Promontogno in the Central Alps. We apply optical microscopy, time-of-flight neutron diffraction, neutron and X-ray tomography to quantify mineral composition and microstructures and use them to construct self-consistent models of elastic properties. They are compared to results of ultrasonic measurements on a cube sample in a multi anvil apparatus and on a spherical sample in an apparatus that can measure velocities in multiple directions. Both methods provide similar results. It is shown that models of microstructure-derived elastic properties provide a good match with ultrasonic experiment results at pressures above 100 MPa. At a pressure of 0.1 MPa the correspondence between the model and the experiment is worse. This may be caused by an oversimplification of the model with respect to microfractures or uncertainties in the experimental determination of S-wave velocities and elastic tensor inversion. The study provides a basis to determine anisotropic elastic properties of rocks either by ultrasonic experiments or quantitative models based on microstructures. This information can then be used for interpretation of seismic data of the crust.

  3. Experimental Studies on Partial Melting of Massive Samples of Granite

    Institute of Scientific and Technical Information of China (English)

    林强; 吴福元

    1994-01-01

    As a basis of modern petrology,the equilibrium relations describing the melting of granite were established mainly on melting experiments of Powder samples.Such experiments,however,have serious limitations in providing information about the variations in compositional and fabric features of the minerals and in the composition and distribution of the melt.Our experiments using massive samples indicate that melt occure mainly at the quartz-plagioclase and quartz-potash feldspar boundaries and the composition of the melt is dependent on local characteristics in the melting system,showing no correlation with the bulk composition of the rock samples.At lower temperatures(740-760℃,0.2GPa),the melt plots at or near the eutectic point in Q-Ab-Or-An-H2O diagram,indicating equilibrium melting.At higher temperatures(790-800℃,0.2GPa)the melt becomes lower in SiO2 and higher in Na2O,deviating makedly from the eutectic line but without disappearance of any mineral phase,suggesting a non-equilibrium process.It is obvious that the phase-equilibrium relations in natural massive granites may be greatly different from those deduced from powder experiments.

  4. Comparative study of dark patinas on granitic outcrops and buildings

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, B. [Dpto. Edafologia y Quimica agricola, Fac. Farmacia, Univ. Santiago de Compostela, 15782-Santiago de Compostela (Spain)]. E-mail: edprieto@usc.es; Aira, N. [Dpto. Edafologia y Quimica agricola, Fac. Farmacia, Univ. Santiago de Compostela, 15782-Santiago de Compostela (Spain); Silva, B. [Dpto. Edafologia y Quimica agricola, Fac. Farmacia, Univ. Santiago de Compostela, 15782-Santiago de Compostela (Spain)

    2007-08-01

    Formation of dark patinas on rocky surfaces is mainly related to the deposition of gases and particles and to sulphation mechanisms. In the present study, samples of dark patinas taken from granitic outcrops and from granitic buildings were examined in an attempt to understand the mechanisms of their formation. The outcrops are located in non-polluted areas and are characterized by the absence of any extraneous material that provides calcium, such as e.g. mortar. The buildings are located in areas with low levels of pollution. The climate in the study area favours proliferation of microorganisms. Important differences between the patinas sampled from outcrops and from buildings were observed, as the former are of biological origin and the latter of anthropogenic origin. Although the levels of pollution are low in the sampling area, sulphur was present in all of the samples from urban buildings. Sulphur was not present in patinas from outcrops or in patinas from monuments that are assumed to behave as outcrops (dolmens), although the latter are also of anthropogenic origin. Finally, the patinas were found to be formed by elements accumulated on the surface and not from elements contained within the rock itself.

  5. Bashikaogong-Shimierbulake granitic complex,north Altun,NW China: Geochemistry and zircon SHRIMP ages

    Institute of Scientific and Technical Information of China (English)

    WU; Cailai; YAO; Sunzhi; ZENG; Lingsen; YANG; Jingsui; Joseph; L.Wooden; CHEN; Songyong; Frank; K.Mazdab

    2006-01-01

    The Bashikaogong-Shimierbulake granitoid complex is about 30 km long and 2-6 km wide,with an area of 140 km2,located at the north margin of the Bashikaogong Basin in the north Altun terrain.It intruded into schist,metapelite and metatuff of Precambrian ages.This granitoid complex consists of darkish quartz diorite,grey granite,pink granite and pegmatite.Geochemically,the quartz diorite has I-type granite affinity and belongs to Calc-alkaline sereies,and the other granites have S-type affinity and to high-K calc-alkaline series.Zircon SHRIMP U-Pb dating shows that the quartz diorite has a bigger age than those of other granites,which is 481.6±5.6 Ma for quartz diorite,437.0±3.0 Ma-433.1±3.4 Ma for grey granite and 443±11 Ma-434.6±1.6 Ma for pink granite,respectively.Combined with regional geology,we think that the quartz diorite formed in tectonic environment related to oceanic crust subduction and the granites in post-collision.

  6. 2005 dossier: granite. Tome: architecture and management of the geologic disposal; Dossier 2005: granite. Tome architecture et gestion du stockage geologique

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the geologic disposal of high-level and long-lived radioactive wastes in granite formations. Content: 1 - Approach of the study: main steps since the December 30, 1991 law, ANDRA's research program on disposal in granitic formations; 2 - high-level and long-lived (HLLL) wastes: production scenarios, waste categories, inventory model; 3 - disposal facility design in granitic environment: definition of the geologic disposal functions, the granitic material, general facility design options; 4 - general architecture of a disposal facility in granitic environment: surface facilities, underground facilities, disposal process, operational safety; 5 - B-type wastes disposal area: primary containers of B-type wastes, safety options, concrete containers, disposal alveoles, architecture of the B-type wastes disposal area, disposal process and feasibility aspects, functions of disposal components with time; 6 - C-type wastes disposal area: C-type wastes primary containers, safety options, super-containers, disposal alveoles, architecture of the C-type wastes disposal area, disposal process in a reversibility logics, functions of disposal components with time; 7 - spent fuels disposal area: spent fuel assemblies, safety options, spent fuel containers, disposal alveoles, architecture of the spent fuel disposal area, disposal process in a reversibility logics, functions of disposal components with time; 8 - conclusions: suitability of the architecture with various types of French granites, strong design, reversibility taken into consideration. (J.S.)

  7. 2005 dossier: granite. Tome: safety analysis of the geologic disposal; Dossier 2005: granite. Tome analyse de surete du stockage geologique

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the safety aspects of the geologic disposal of high-level and long-lived (HLLL) radioactive wastes in granite formations. Content: 1 - safety approach: context and general goal, references, design approach by safety functions, safety approach during the construction-exploitation-observation-closure phase, safety analysis during the post-closure phase; 2 - general description: HLLL wastes, granitic environment, general structure of the architecture of a disposal facility; 3 - safety functions and disposal design: general context, safety functions of the long-term disposal, design dispositions retained to answer the functions; 4 - operational safety: people's protection, radiological risks during exploitation, risk analysis in accident situation; 5 - qualitative safety analysis: methodology, main results of the analysis of the features, events and processes (FEP) database; 6 - disposal efficiency evaluation during post-closure phase: calculation models, calculation tools used for the modeling of radionuclides transport, calculation results and main lessons. (J.S.)

  8. Neo-tectonic fracturing after emplacement of quaternary granitic pluton in the Kakkonda geothermal field, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Doi, N.; Kato, O. [JMC Goethermal Eng. Co., Ltd., Iwate-ken (Japan); Kanisawa, S.; Ishikawa, K. [Tohoku Univ., Sendai (Japan)

    1995-12-31

    The fracture which occurs in the Kakkonda geothermal system was formed by neo-tectonic stress after the emplacement of the neo-granite (Quaternary Kakkonda Granite) at middle Pleistocene to recent. The characteristic contrast in permeability at ca.1.5 km is strongly controlled by the contact metamorphic zone, especially cordierite and higher grade metamorphic zones, in which the high temperature (320{degrees}C<) and low permeable deep reservoir was created. The five geothermal wells 2.5-3.0 km deep have clarified that a microearthquake zone below -1.0 km shows high permeability especially at the margin of the Kakkonda Granite, and low permeability outside of a microearthquake zone. The Kakkonda Granite is a composite pluton which has very few fractures inside of it. Thus, neo-tectonic fracturing has developed in the non-metamorphosed Tertiary formations and the margin of the Kakkonda Granite.

  9. Geochronology and sources of late Neoproterozoic to Cambrian granites of the Saldania Belt

    Science.gov (United States)

    Chemale, F.; Scheepers, R.; Gresse, P. G.; van Schmus, W. R.

    2011-04-01

    The Saldania Belt (SB), located in the southernmost part of South Africa, contains S-, I-, and A-type granites. Whole-rock Sm-Nd data for the Saldania granites indicate the presence of a juvenile as well as inherited crustal signature. The earlier S-type granites have ɛNd( t) values from -4.2 to -3.28 (for t = 550 Ma). In contrast, the intermediate I-type and youngest A-type and highly fractionated I-type granites display ɛNd values ranging from -1.44 to -3.68 (for t = 540 Ma) and from +3.66 to +5.1(for t = 530 Ma), respectively. The U-Pb single zircon data of A-type granites exposed in the Western Branch of the SB yielded dates from 524 ± 8 to 510 ± 4 Ma, whereas an S-type granite, situated in the Southern Branch of the SB and represented by the syn- to late-tectonic Rooiklip Granite, yielded an age of 527 ± 8 Ma. The volcano-sedimentary rocks intruded by these granites display Nd model ages from Ga to 1.67 Ga and ɛNd( t) values from -6.58 to +3.34 (for t = 560 Ma) with isotope signature similar to those of the granites. The S- and I-type granitic magmatism is mostly a product of melting of an earlier crust (Mesoproterozoic to Paleoproterozoic) with different degree of juvenile contribution. The obtained isotope data and field relationship support the hypothesis that the lithological units of the SB were affected by the late Neoproterozoic to Early Cambrian tectonism, related to compressive deformational processes at the southern margin of the Kalahari Plate and probably correlated with the Sierra La Ventana Belt basement.

  10. Permian ultrafelsic A-type granite from Besar Islands group, Johor, peninsular Malaysia

    Indian Academy of Sciences (India)

    Azman A Ghani; Fatin Izzani Hazad; Azmiah Jamil; Quek Long Xiang; Wan Nur Atiqah Wan Ismail; Sun-Lin Chung; Yu-Ming Lai; Muhammad Hatta Roselee; Nur Islami; Kyaw Kyaw Nyein; Meor Hakif Amir Hassan; Mohd Farid Abu Bakar; Mohd Rozi Umor

    2014-12-01

    The granitic rocks of the peninsula have traditionally been divided into two provinces, i.e., Western and Eastern provinces, corresponding to S- and I-type granite respectively. The Western Province granite is characterised by megacrystic and coarse-grained biotite, tin-mineralised, continental collision granite, whereas, the Eastern Province granite is bimodal I-type dominated by granodiorite and associated gabbroic of arc type granite. This paper reports the occurrence of an A-type granite from peninsular Malaysia. The rocks occur in the Besar, Tengah, and Hujung islands located in the southeastern part of the peninsula. The granite is highly felsic with SiO2 ranging from 75.70% to 77.90% (differentiation index = 94.2–97.04). It is weakly peraluminous (average ACNK=1.02), has normative hypersthene (0.09–2.19%) and high alkali content (8.32–8.60%). The granites have many A-type characteristics, among them are shallow level of emplacement, high Ga, FeT/MgO and low P, Sr, Ti, CaO and Nb. Calculated zircon saturation temperatures for the Besar magma ranging from 793° to 806°C is consistent with high temperature partial melting of a felsic infracrustal source which is taken as one of the mechanisms to produce A-type magma. The occurrence of the A-type granite can be related to the extensional back arc basin in the Indo-China terrane during the earliest Permian.

  11. Gypsum-induced decay in granite monuments in Northwestern Spain

    Directory of Open Access Journals (Sweden)

    Silva Hermo, B.

    2010-03-01

    Full Text Available One of the most common forms of decay in granite monuments is the detachment of the superficial layer of the stone (plaques, plaquettes and scales. Previous studies of granite monuments in the northwest Iberian Peninsula revealed a direct relation between this type of weathering and the presence of calcium sulphate, and a mechanism whereby the salt causes this type of decay was suggested. In the present study, various hypotheses as regards the origin of the gypsum found in granite monuments are proposed. The study involved analysis of the contents of ions soluble in water, the results of X-ray diffraction analyses and the ratios of CaO/SO3 in samples of stone, mortar and deposits collected from different monuments. It was concluded that in most cases the gypsum originated from old paintworks or/and from the joint mortars, although inputs from other sources cannot be discounted, as discussed

    Una de las formas de deterioro más frecuente en los monumentos graníticos es la separación de la capa superficial de la piedra (placas, plaquetas y escamas. En trabajos anteriores centrados en monumentos del noroeste de la Península Ibérica, se constató la relación directa entre esta forma de alteración y la presencia de sulfato de calcio y se propuso el mecanismo a través del cual esta sal provoca este tipo de deterioro. En este trabajo se plantean varias hipótesis acerca del origen del yeso encontrado en monumentos graníticos. Para ello se comparan los contenidos de iones solubilizados en agua, los resultados de difracción de rayos X y las relaciones OCa/SO3 de muestras de piedra, morteros y depósitos recogidas en diferentes monumentos. Se llega a la conclusión de que en la mayor parte de los casos el yeso procede de antiguas pinturas o de revestimientos superficiales y de los morteros de juntas entre sillares, pero no se puede descartar la contribución de otros aportes, los cuales se discuten también en este artículo.

  12. Provenance of granites used to build the Santa Maria de Valdeiglesias Monastery, Pelayos de la Presa (Madrid, Spain), and conservation state of the monumental complex

    Science.gov (United States)

    Fort, R.; Alvarez de Buergo, M.; Vazquez-Calvo, C.; Perez-Monserrat, E. M.; Varas-Muriel, M. J.; Lopez-Arce, P.

    2012-04-01

    The construction of the Cistercian Monastery began at 1180, in an initial Late Romanesque style in which the Church was erected; later on, in 1258, the church underwent a severe fire, only the apse stood standing. The church was reconstructed at the end of the 13th century in Mudejar style. Gothic style was used later on, in the 16th century, for the reconstruction of the funerary chapel, and Renaissance style for the Plateresque door in between the church and the sacristy. At the end of the 16th century, the main door to access the church was built in Baroque style. In 1836, the Ecclesiastical Confiscations resulted on transfer the Monastery into particular owners. This fact favoured its abandon and ruin state until 1979, when architect Mariano Garcia Benito purchased the property and started the conservation and consolidation of the complex, beginning with the Bell Tower. Natural stone materials used in the Monastery are igneous (granite) and metamorphic rocks (gneiss and schist), and artificial stone materials are bricks and mortars, both joint and rendering ones. Granite is the most abundant material used in the complex, with a structural/reinforcing role in elements such as lintels, jambs, buttresses, or bottom areas of the walls with greater sizes and better dimensioned. Some pillars are granite built, from the large ashlars of the sacristy, to the rubble-work of the Mozarab chapel. Two types of monzogranite can be differentiated in relation to distinct constructive stages: the coarse texture monzogranite is used in the first building stages, while the fine texture monzogranite was employed mainly from 17th century on. Petrophysical characteristics of these granites are different but show a good quality to be used in construction. Nevertheless, the abandon and partial ruin of the complex, the devastating fire events (the second one in 1743) leaded to the decay acceleration of the monumental complex, being nowadays the church in ruin, with no roofs and walls

  13. 75 FR 16827 - Notice of Availability of the Draft Granite Mountain Wind, LLC Wind Energy Generation Project...

    Science.gov (United States)

    2010-04-02

    ... Bureau of Land Management Notice of Availability of the Draft Granite Mountain Wind, LLC Wind Energy... Report (EIR) for the proposed Granite Mountain Wind Energy Generation Project and by this notice is... related to the proposed Granite Mountain Wind Energy Generation Project by any of the following...

  14. IRETHERM: Magnetotelluric studies of Irish radiothermal granites and their geothermal energy potential

    Science.gov (United States)

    Farrell, T. F.; Jones, A. G.; Muller, M. R.; Feely, M.

    2013-12-01

    The IRETHERM project seeks to develop a strategic understanding of Ireland's deep geothermal energy potential through integrated modeling of new and existing geophysical and geological data. One aspect of IRETHERM's research focuses on Ireland's radiothermal granites, where increased concentrations of radioelements provide elevated heat-production (HP), heat-flow (HF) and subsurface temperatures. An understanding of the contribution of granites to the thermal field of Ireland is of key importance in assessing the geothermal energy potential of this low-enthalpy setting. This study focuses on the Leinster granite, the Galway granite and the buried Kentstown granite. Shallow (geothermal project. These studies yielded HP = 2-3 μWm-3 and HF = 80 mWm-2 at the Sally Gap borehole in the Northern Units of the Leinster granite. In the Galway granite batholith, the Costelloe-Murvey granite returned HP = 7 μWm-3 and HF = 77 mWm-2, measured at the Ros a Mhil borehole. The lower heat-flow encountered at the Ros a Mhil borehole suggests that the associated high heat production does not extend to great depth. The buried Kentstown granite has associated with it a significant negative Bouguer anomaly and was intersected by two mineral exploration boreholes at depths of 660 m and 485 m. Heat production has been measured at 2.4 μWm-3 in core samples taken from the weathered top 30m of the granite. The core of this study consists of an ambitious program of magnetotelluric (MT) and audio-magnetotelluric (AMT) data acquisition across the three granite bodies, extending over three fieldwork seasons. MT and AMT data were collected at 59 locations along two profiles over the Leinster granite. Preliminary results show that the northern units of the Leinster granite extend to depths of 2-5 km. Over the Galway granite, MT and AMT data have been collected at a total of 29 sites, with a further 46 sites to be collected in August 2013 (of these 75 sites, 33 will consist of AMT-only data

  15. Petrology, geochemistry of hornblende gabbro and associated dolerite dyke of Paharpur, Puruliya, West Bengal: Implication for petrogenetic process and tectonic setting

    Indian Academy of Sciences (India)

    Aditi Mandal; Arijit Ray; Mayukhee Debnath; Sankar Prasad Paul

    2012-06-01

    Paharpur gabbroic intrusive is an arcuate body running east–west paralleling the foliation of Chhotanagpur Granite Gneiss which acts as country rock. The main gabbroic body is intruded by a number of dolerite dykes running north–south. It is composed of clinopyroxene (Wo48En40Fs12–Wo51En40Fs09, mg no. 72–82), plagioclase (An52–An90), hornblende (magnesian hornblende to ferro-tschermackite), orthopyroxene (En76–En79) and ilmenite. Hornblende occurs as large poikilitic grain and constitutes around 60% of the rock. Both gabbro and associated dolerite dykes, show relatively primitive character (mg no. 65–73). Primitive mantle-normalized and MORB-normalized spider diagrams indicate enrichment in Rb, Ba, Th, La, Sr and depletion in Nb, Zr, Y, Ti and Nd. The LILE enrichment and Nb, Ti, Zr, Y depletion suggest arc like geochemical signature for the gabbroic and doleritic rocks of Paharpur. Flat to slightly LREE fractionated pattern and variable degree of REE enrichment is observed. An early stage fractionation of clinopyroxene, plagioclase, orthopyroxene, ilmenite and late stage reaction of cumulate pile and evolved melt/hydrous fluid is suggested for magmatic evolution of gabbro. Associated dolerite dykes, which are geochemically similar to the gabbro, have tholeiitic with boninitic character. The mineralogical and chemical compositions of intrusive rocks also have some similarity with mafic rocks of ophiolite complex of subduction zone.

  16. Radon release from granites in south-west England

    CERN Document Server

    Poole, J

    2001-01-01

    accessory minerals. The enhancement of surface area was attributed to the alteration of feldspar to sericite. This has implications for the release of radon. It is thought that the large surface area provides a sink for the adsorption of radon, retaining it in the rock structure. This radon retention explains the paradoxical decline in radon release at small particle size/large specific surface area. Various mechanisms for radon emanation are discussed with reference to the Cornubian granites. It is shown that, based on the measured specific surface areas, inter-crystalline diffusion is a slow process and not a significant contributor to overall radon release (0.01%). Approximately 1% of the total radon produced can be attributed to direct recoil processes, based on the calculated recoil ranges (36 nm). The remainder was attributed to diffusion processes through crystal imperfections and dislocations. The microscopic scale model developed here is extended to the macroscopic scale through examination of the la...

  17. Geoscience parameter data base handbook: granites and basalts

    Energy Technology Data Exchange (ETDEWEB)

    1979-12-01

    The Department of Energy has the responsibility for selecting and constructing Federal repositories for radioactive waste. The Nuclear Regulatory Commission must license such repositories prior to construction. The basic requirement in the geologic disposal of radioactive waste is stated as: placement in a geologic host whereby the radioactive waste is not in mechanical, thermal or chemical equilibrium with the object of preventing physical or chemical migration of radionuclides into the biosphere or hydrosphere in hazardous concentration (USGS, 1977). The object of this report is to document the known geologic parameters of large granite and basalt occurrences in the coterminous United States, for future evaluation in the selection and licensing of radioactive waste repositories. The description of the characteristics of certain potential igneous hosts has been limited to existing data pertaining to the general geologic character, geomechanics, and hydrology of identified occurrences. A description of the geochemistry is the subject of a separate report.

  18. Mineralogical Characteristics of Yellow—Red Soils Derived from Granite

    Institute of Scientific and Technical Information of China (English)

    LUOJIA-XIAN; YANGDE-YONG; 等

    1993-01-01

    Mineral constituents and their weathering in yellow-red soils derived from granite in middle and lower reaches of the yangtze River were studied.Light minerals in fractions greater than silt contained over 80% quartz and feldspar,and heavy ones contained more than 60% various iron minerals and about 30% mica and bornblende.Kaolinite was the main clay mineral,the content of which was about 300-400g/kg.Quartz was weathered very weakly,Ca-feldspar was weathered over 65%,and about 25% of Na-feldspar was weathered.The vermiculitisation of mica was relativly obvious,>50% of mica being eathered to vermiculite.Weatherable minerals were also obviously eathered,the weathering being about 60%.Soil vermiculite was evolved through the process of mica→hydromica→vermiculite-chlorite→vermiculite,which was closely related to leaching situation and oxidic condition.

  19. Mechanical property and cutting rate of microwave treated granite rock

    Directory of Open Access Journals (Sweden)

    Lek Sikong

    2009-10-01

    Full Text Available The purpose of this study is to investigate the effect of microwave treatment, especially at low power level on compressive strength and cutting rate of granite rock by using multimodal cavity. The power level and cooling rate of treated samples were found to have an effect on the compressive strength, and the cutting rate. This effect is due to the induction of the plastic zones and micro cracks in the rock matrix, especially at the grain boundaries induced by the thermal stresses of rock forming minerals which have the difference in dielectric properties after microwave heating for a certain exposure time together with the thermal-shock treatment after the heating. It was found that the strength of treated granite is less than 60% of the original after 30 minutes of exposure.The dry heated samples with a water quenching seem to be the most affected samples. They exhibit a significant decrease in compressive strength up to 70% and cutting rate up to 38% after 30-minute treatment at the power of 850W, and after 10-minute treatment at the power of 600W respectively. Prolonged treatment causes the relaxation of induced thermal stresses in the rock mass, leading to a slight increase in compressive strength, and a slight decrease in cutting rate. For dry samples, the cutting rate can be enhanced because of a decrease in hardness of rock mass dropped from 61.5 to 55.4 HRC afterthe 10-minute heating at 600W with thermal shock treatment.The absorbed water in the pores of rock mass also has an effect on a decrease in compressive strength. Because micro cracks developed by the water vapor generated by heat which escapes through open pores. However, it seems to have less effect on the cutting rate because it causes a slight decrease in the hardness.

  20. Durability of two water repelents applied to granite

    Directory of Open Access Journals (Sweden)

    Rivas, T.

    1998-06-01

    Full Text Available The durability of two water-repellents for granitic stonework was determined. Weathered and sound samples of granites widely used in building construction and restoration in Galicia (NW Spain were treated with water repellents of known efficacy, and then subjected to two artificial weathering tests: prolonged exposure to UV light, and sodium sulphate crystallization cycles. In both tests, but especially in the salt crystallization cycles, both treatments rapidly lost their water-repellency. Furthermore, the hydrophobic layer of water repellent impeded salt mobility, favouring fissuration parallel to the treated surface, which was eventually shed in the form of a plaque.

    Se presentan los resultados de la durabilidad de dos tratamientos de hidrofugación aplicados a rocas graníticas ampliamente utilizados en la construcción de edificios en Galicia (Noroeste de España. Tras la evaluación de la eficacia de dichos tratamientos, cuyos resultados se presentaron en un trabajo anterior, se someten las muestras tratadas a dos ensayos diferentes de envejecimiento acelerado: ciclos de exposición a la luz ultravioleta y ciclos de cristalización de sulfato de sodio. Los productos hidrofugantes muestran una escasa resistencia a ambos ensayos, sobre todo a los ciclos de cristalización de sulfato de sodio; esta débil durabilidad se manifiesta en una rápida pérdida de sus propiedades hidrofugantes. Así mismo, se observa que la presencia de la capa hidrófoba en la piedra funciona como una barrera frente a la movilidad de sales, lo que ocasiona el total desprendimiento de aquella y un fuerte deterioro del material rocoso.

  1. The effect of elevated temperature on the physical properties of Mauthausen Granite (Austria) and Mórágy Granite (Hungary); a comparative study

    Science.gov (United States)

    Török, Anita; Török, Ákos

    2014-05-01

    Elevated temperature cause changes in the physical properties of rocks. The current study provides information on the behaviour of two granitic rocks that were subjected to high temperatures. The two studied lithologies were: i) grey Mauthausen Granite from Upper Austria and a ii) pinkish granite from Mórágy Granite Formation, southern Hungary. The latter one is the host rock of the Hungarian National Radioactive Waste Repository, which is located at Bátaapáti. To assess the changes in physical properties test were made in four conditions: air-dry room temperature (23°C); water saturated room temperature (23°C); after heat shock of 300°C and 600°C, respectively. For the heat tests a furnace was used, in which the temperature was hold on 300°C and 600°C for six hours. The physical parameters were measured according to EN standards or to ISRM guidelines. These included density, determination of ultrasound speed propagation (EN 14579:2005), uniaxial compressive strength (EN 1926:2007), indirect tensile strength (ISRM) and water absorption (EN 13755:2001). The results indicate that there were only minor changes in the densities of both granite types when the samples were heated up to 600°C. To the contrary, the strength parameters showed a clear trend. From room temperature until ~300°C, the uniaxial compressive strength, the modulus of elasticity and the indirect tensile strength showed a slight increase compared to the initial values. This elevated strength decreased significantly when the samples were heated to 600°C. This trend is in good agreement with the previous tests that were made on Indian granites (Dwivedi et al. 2008). Reference: Dwivedi, R. D., R. K. Goel, V.V.R. Prasad, A. Sinha 2008. Thermo-mechanical properties of Indian and other granites. Int. J. Rock Mech. Min. Sci., 45, 3, 303-315.

  2. Dirty or Tidy ? Contrasting peraluminous granites in a collapsing Orogen: Examples from the French Massif Central

    Science.gov (United States)

    Villaros, Arnaud; Pichavant, Michel; Moyen, Jean-François; Cuney, Michel; Deveaud, Sarah; Gloaguen, Eric; Melleton, Jérémie

    2013-04-01

    Post collisional collapse commonly enhances crustal melting. Such melting typically produces peraluminous granitic magmas. In the French Massif Central, a mid-crustal segment of the western Variscan belt, two large granitic bodies were produced during the collapse of the Variscan Belt. The St Sylvestre Leucogranitic Complex (SSyL) in the western part of the Massif Central and the Velay Migmatitic Complex (VMC) in the Eastern part. Although these two complexes are formed in similar geodynamic context they present meaningful petrological and geochemical differences. The VMC (~305 Ma) is clearly intrusive in migmatitic terranes. The migmatitic host recorded two successive melting events M3 (720 °C and 5kb) dated between 335 and 315 Ma and M4 (850°C and 4 kb) dated at 305 Ma. The compositions of the VMC are strictly H2O-undersaturated and ranges from leucogranitic to granodioritic. Three main successive granite types have been distinguished (1) A heterogeneous banded biotite granite, (2) A main biotite-cordierite granite, where cordierite can be prismatic, as cockade or pseudomorphic (3) a late magmatic with large K-feldspar phenocryst and prismatic cordierite. The compositions of the VMC granites are quite similar to typical Australian S-type granites in the sense that they also show a positive correlation between ferromagnesian abundance and aluminosity. The SSyL (~320 Ma) is intrusive in upper greenschist facies to upper amphibolite migmatitic metasediment and orthogneiss (~3kb). The compositional variety observed in the SSyL suggests a continuous trend from a moderately mafic, peraluminous magma (cd- and sill- granite) to a H2O saturated granite ("two-mica" granite) facies and finally to an extremely felsic, H2O-saturated magma. Three granitic units have been recognized in the SSyL: (1) the western "Brame Unit" composed of the less evolved cd- and sill- granite facies (2) the central "St Sylvestre Unit", composed mainly by U-rich two-mica granite, intruded by two

  3. Major magmatic events in Mt Meredith, Prince Charles Mountains: First evidence for early Palaeozoic syntectonic granites

    Science.gov (United States)

    Gongurov, N.A.; Laiba, A.A.; Beliatsky, B.V.

    2007-01-01

    Precambrian rocks at Mt Meredith underwent granulite-facies metamorphism M1. Zircon isotope dating for two orthogneisses revealed the following age signatures: 1294±3 and 957±4Ma; 1105±5 and 887±2Ma. The oldest ages could reflect the time of orthogneiss protolith crystallization and the latest age determinations date Grenvillian metamorphism. The metamorphic rocks were intruded by two-mica and garnet-biotite granites. The granites and host rocks underwent amphibolite-facies metamorphism M2. Zircon isotope analysis of the two-mica granites showed age estimation within 550-510Ma and zircon dating of the garnet-biotite granites revealed the ages of 1107±5, 953±8, and 551±4Ma. As Pan-African age signatures were obtained from only the granite samples, it is possible to suggest that the granites were formed at the time of 510-550Ma and the zircons with greater age values were captured by granites from the host rocks.

  4. Microprobe monazite dating and the ages of some granitic and metamorphic rocks from southeastern Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Vlach, Silvio Roberto Farias; Gualda, Guilherme Augusto Rosa [Sao Paulo Univ., SP (Brazil). Inst. de Geociencias]. E-mail: srfvlach@usp.br

    2000-03-01

    Electron microprobe monazite crystallization ages are presented for selected granite and metamorphic rock samples from the Socorro and Guaxupe Nappes and the Alto Rio grande and Ribeira Belts, southeastern Brazil. Results are consistent with ages close to 625 Myr of the main metamorphic episode in the nappe structures. Anatetic granite magmatic events in these terranes and in the Alto Rio Grande Belt were roughly coeval, most samples sharing ages between 610-625 ({+-} 15) Myr. A crust-derived granite and a granite contact aureole from the Ribeira Belt have ages of 600-608 ({+-} 15) Myr., suggesting that the main granite magmatism in this belt was somewhat younger, probably contemporaneous with the late orogenic phase in the nappe domains. Some regional and granite samples from all these terranes point to possible inheritance or incompletely monazite grains and intra-grain domains giving older ages, up to 690 Myr. The microprobe age results agree very well with independent isotopic data, reinforcing the applicability of the method to highlight an overall picture of main geochronological trends within the continental crust. The high spatial resolution of the probe should play an important role in understanding geochronological patterns of metasedimentary rocks and related migmatites and granites, as these rocks and their minerals often present chemical and isotopic domains related to contrasting geological events, not always recognized by conventional dating schemes. (author)

  5. Magmatic constraints on localization of natural stone deposits in the Vehmaa rapakivi granite batholith, southwestern Finland

    Directory of Open Access Journals (Sweden)

    Olavi Selonen

    2011-08-01

    Full Text Available The 1580–1570 Ma old Vehmaa rapakivi granite batholith was studied with the aim to define the geological constraints for localization of natural stone deposits in the batholith. The batholith comprises four roughly concentric granite intrusions from the margin inwards: pyterlite, coarse-grained porphyritic rapakivi granite and two types of medium-grained porphyritic rapakivi granite. Also porphyry aplite and even-grained rapakivi granite occur. The batholith has intruded as a succession of pulses of subhorizontal sheet-like intrusions conceivably through repeated cauldron subsidence. Natural stone quarries are confined only to certain intrusions within the batholith. We show that the medium-grained porphyritic granite body in the centre of the batholith comprises two almost identical but different intrusions, with only slightly different appearances: the inner (IG and the outer (OG granite. The quarries are confined to the outer intrusion which has an appearance more attractive to the market than that of the inner intrusion. The localization of the natural stone deposits in the Vehmaa batholith is a result of the magmatic history of the batholith, producing intrusions of different appearances with different commercial potential.

  6. Geochemistry and petrogenesis of Proterozoic granitic rocks from northern margin of the Chotanagpur Gneissic Complex (CGC)

    Indian Academy of Sciences (India)

    Bhupendra S Yadav; Nishchal Wanjari; Talat Ahmad; Rajesh Chaturvedi

    2016-07-01

    This study presents the geochemical characteristics of granitic rocks located on the northern margin of Chotanagpur Gneissic Complex (CGC), exposed in parts of Gaya district, Bihar and discusses thepossible petrogenetic process and source characteristics. These granites are associated with BarabarAnorthosite Complex and Neo-proterozoic Munger–Rajgir group of rocks. The granitic litho-units identifiedin the field are grey, pink and porphyritic granites. On the basis of geochemical and petrographiccharacteristics, the grey and pink granites were grouped together as GPG while the porphyritic graniteswere named as PG. Both GPG and PG are enriched in SiO_2, K_2O, Na_2O, REE (except Eu), Rb,Ba, HFSE (Nb, Y, Zr), depleted in MgO, CaO, Sr and are characterised by high Fe^* values, Ga/Alratios and high Zr saturation temperatures (GPG_{avg} ∼ 861^◦C and PG_{avg} ∼ 835^◦C). The REE patternsfor GPG are moderately fractionated with an average (La/Yb)_N ∼ 4.55 and Eu/Eu^* ∼0.58, than PGwhich are strongly fractionated with an average (La/Yb)_N ∼ 31.86 and Eu/Eu^* ∼0.75. These featuresindicate that the granites have an A-type character. On the basis of geochemical data, we conclude that the granites are probably derived from a predominant crustal source with variable mantle involvementin a post-collisional setting.

  7. Earth's youngest exposed granite and its tectonic implications: the 10–0.8 Ma Kurobegawa Granite

    Science.gov (United States)

    Ito, Hisatoshi; Yamada, Ryuji; Tamura, Akihiro; Arai, Shoji; Horie, Kenji; Hokada, Tomokazu

    2013-01-01

    Although the quest for Earth's oldest rock is of great importance, identifying the youngest exposed pluton on Earth is also of interest. A pluton is a body of intrusive igneous rock that crystallized from slowly cooling magma at depths of several kilometers beneath the surface of the Earth. Therefore, the youngest exposed pluton represents the most recent tectonic uplift and highest exhumation. The youngest exposed pluton reported to date is the Takidani Granodiorite (~ 1.4 Ma) in the Hida Mountain Range of central Japan. Using LA-ICP-MS and SHRIMP U-Pb zircon dating methods, this study demonstrates that the Kurobegawa Granite, also situated in the Hida Mountain Range, is as young as ~ 0.8 Ma. In addition, data indicate multiple intrusion episodes in this pluton since 10 Ma with a ~ 2-million-year period of quiescence; hence, a future intrusion event is likely within 1 million years. PMID:23419636

  8. Protoliths of enigmatic Archaean gneisses established from zircon inclusion studies: Case study of the Caozhuang quartzite, E. Hebei, China

    Directory of Open Access Journals (Sweden)

    Allen P. Nutman

    2014-07-01

    Full Text Available A diverse suite of Archaean gneisses at Huangbaiyu village in the North China Craton, includes rare fuchsite-bearing (Cr-muscovite siliceous rocks – known as the Caozhuang quartzite. The Caozhuang quartzite is strongly deformed and locally mylonitic, with silica penetration and pegmatite veining common. It contains abundant 3880–3600 Ma and some Palaeoarchaean zircons. Because of its siliceous nature, the presence of fuchsite and its complex zircon age distribution, it has until now been accepted as a (mature quartzite. However, the Caozhuang quartzite sample studied here is feldspathic. The shape and cathodoluminescence petrography of the Caozhuang quartzite zircons show they resemble those found in immature detrital sedimentary rocks of local provenance or in Eoarchaean polyphase orthogneisses, and not those in mature quartzites. The Caozhuang quartzite intra-zircon mineral inclusions are dominated by quartz, with lesser biotite, apatite (7% and alkali-feldspar, and most inclusions are morphologically simple. A Neoarchaean orthogneiss from near Huangbaiyu displays morphologically simple inclusions with much more apatite (73%, as is typical for fresh calc-alkaline granitoids elsewhere. Zircons were also examined from a mature conglomerate quartzite clast and an immature feldspathic sandstone of the overlying weakly metamorphosed Mesoproterozoic Changcheng System. These zircons have oscillatory zoning, showing they were sourced from igneous rocks. The quartzite clast zircons contain only rare apatite inclusions (<1%, with domains with apatite habit now occupied by intergrowths of muscovite + quartz ± Fe-oxides ± baddeleyite. We interpret that these were once voids after apatite inclusions that had dissolved during Mesoproterozoic weathering, which were then filled with clays ± silica and then weakly metamorphosed. Zircons in the immature feldspathic sandstone show a greater amount of preserved apatite (11%, but with petrographic

  9. Protoliths of enigmatic Archaean gneisses established from zircon inclusion studies:Case study of the Caozhuang quartzite, E. Hebei, China

    Institute of Scientific and Technical Information of China (English)

    Allen P. Nutman; Ronni Maciejowski; Yusheng Wan

    2014-01-01

    A diverse suite of Archaean gneisses at Huangbaiyu village in the North China Craton, includes rare fuchsite-bearing (Cr-muscovite) siliceous rocks e known as the Caozhuang quartzite. The Caozhuang quartzite is strongly deformed and locally mylonitic, with silica penetration and pegmatite veining common. It contains abundant 3880e3600 Ma and some Palaeoarchaean zircons. Because of its siliceous nature, the presence of fuchsite and its complex zircon age distribution, it has until now been accepted as a (mature) quartzite. However, the Caozhuang quartzite sample studied here is feldspathic. The shape and cathodoluminescence petrography of the Caozhuang quartzite zircons show they resemble those found in immature detrital sedimentary rocks of local provenance or in Eoarchaean polyphase orthog-neisses, and not those in mature quartzites. The Caozhuang quartzite intra-zircon mineral inclusions are dominated by quartz, with lesser biotite, apatite (7%) and alkali-feldspar, and most inclusions are morphologically simple. A Neoarchaean orthogneiss from near Huangbaiyu displays morphologically simple inclusions with much more apatite (73%), as is typical for fresh calc-alkaline granitoids elsewhere. Zircons were also examined from a mature conglomerate quartzite clast and an immature feldspathic sandstone of the overlying weakly metamorphosed Mesoproterozoic Changcheng System. These zircons have oscillatory zoning, showing they were sourced from igneous rocks. The quartzite clast zircons contain only rare apatite inclusions (<1%), with domains with apatite habit now occupied by in-tergrowths of muscovite+quartz±Fe-oxides±baddeleyite. We interpret that these were once voids after apatite inclusions that had dissolved during Mesoproterozoic weathering, which were then filled with clays±±silica and then weakly metamorphosed. Zircons in the immature feldspathic sandstone show a greater amount of preserved apatite (11%), but with petrographic evidence of replacement of

  10. Coupled zircon Lu-Hf and U-Pb isotopic analyses of the oldest terrestrial crust, the >4.03 Ga Acasta Gneiss Complex

    Science.gov (United States)

    Bauer, Ann M.; Fisher, Christopher M.; Vervoort, Jeffrey D.; Bowring, Samuel A.

    2017-01-01

    The Acasta Gneiss Complex of the Northwest Territories, Canada, contains some of the earliest terrestrial continental crust and thus provides a critical sample set for characterization of crust-forming processes on the early Earth. Here we report the results of a combined Lu-Hf and U-Pb isotopic study of zircons from predominantly felsic orthogneisses from the Acasta Gneiss Complex that crystallized between ∼4.0 and 2.9 Ga, many of which contain complex zoning and therefore require an analytical treatment suited to distinguish amongst compositionally distinct age and Hf isotopic domains. To ensure the reliability of the analyses and of subsequent geologic interpretations, we employed the laser ablation split-stream (LASS) technique to concurrently measure the Lu-Hf and U-Pb isotopic systems in zircon. Our results confirm prior findings of precursor Hadean crust (>4.0 Ga) in the source of these rocks and the continued involvement of this reservoir until ∼3.6 Ga. We present evidence for the input of relatively more juvenile material at ∼3.6 Ga, which we suggest corresponds to a fundamental change in the source of the magmas. This study extends the lower bound of the published Acasta Hf isotopic record from 3.6 Ga to 2.9 Ga and demonstrates that the ∼3.6 Ga-2.9 Ga interval is largely represented by reworking of relatively juvenile ∼3.6 Ga crust and the diminution of the >4.0 Ga crustal signal. Significantly, there is no evidence that rocks within the Acasta Gneiss Complex were derived from a strongly depleted mantle.

  11. Geology, geochemistry, and geochronology (U-Pb) of the Rio Fortuna Gneiss - Serra do Bau intrusive Suite - Paragua Terrane SW Amazonian Craton

    Energy Technology Data Exchange (ETDEWEB)

    Faria, Debora Almeida; Ruiz, Amarildo Salina; Matos, Joao Batista; Sousa, Maria Zelia Aguiar de; Lima, Gabrielle Aparecida de [Research Group on Crustal and Tectonic Evolution, Guapore, RS (Brazil); Universidade Federal de Mato Grosso (ICET/UFMT), Cuiaba, MT (Brazil). Instituto de Ciencias Exatas e da Terra; Inst. Nacional de Ciencia e Tecnologia de Geociencias da Amazonia (GEOCIAM), Belem, PA (Brazil); Moacir Jose Buenano Macambira, E-mail: defaal.debora@gmail.com, E-mail: gabilimagel@gmail.com, E-mail: asruiz@gmail.com, E-mail: jmatos@ufmt.br, E-mail: prof.mzaguiar@gmail.com, E-mail: moamac@ufpa.br [Research Group on Crustal and Tectonic Evolution, Guapore, RS (Brazil); Universidade Federal do Para (UFPA), Belem, PA (Brazil)

    2014-07-01

    The Rio Fortuna Gneiss crops out in the Serra Santa Barbara, near the Fortuna military headquarters, on the Brazil-Bolivia border. These orthogneisses are located in a portion of the Paragua terrain affected by the Sunsas Orogeny (1.0-0.9 Ga.). They are classified as monzo to granodiorite orthogneisses and underwent at least three episodes of deformation. The U-Pb zircon age of 1,711 ± 13 Ma obtained by laser ablation MC-ICP-MS is interpreted as the crystallization age of this orthogneiss. Geochemically, these rocks form a sequence comprising acidic subalkaline magmatism, calc-alkalic-type high-K, and metaluminous to peraluminous. (author)

  12. Mantle hydrous-fluid interaction with Archaean granite.

    Science.gov (United States)

    Słaby, E.; Martin, H.; Hamada, M.; Śmigielski, M.; Domonik, A.; Götze, J.; Hoefs, J.; Hałas, S.; Simon, K.; Devidal, J.-L.; Moyen, J.-F.; Jayananda, M.

    2012-04-01

    Water content/species in alkali feldspars from late Archaean Closepet igneous bodies as well as growth and re-growth textures, trace element and oxygen isotope composition have been studied (Słaby et al., 2011). Both processes growth and re-growth are deterministic, however they differ showing increasing persistency in element behaviour during interaction with fluids. The re-growth process fertilized domains and didn't change their oxygen-isotope signature. Water speciation showed persistent behaviour during heating at least up to 600oC. Carbonate crystals with mantle isotope signature are associated with the recrystallized feldspar domains. Fluid-affected domains in apatite provide evidence of halide exchange. The data testify that the observed recrystallization was a high-temperature reaction with fertilized, halide-rich H2O-CO2 mantle-derived fluids of high water activity. A wet mantle being able to generate hydrous plumes, which appear to be hotter during the Archean in comparison to the present time is supposed by Shimizu et al. (2001). Usually hot fluids, which can be strongly carbonic, precede asthenospheric mantle upwelling. They are supposed to be parental to most recognized compositions, which can be derived by their immiscible separation into saline aqueous-silicic and carbonatitic members (Klein-BenDavid et al., 2007). The aqueous fractions are halogen-rich with a significant proportion of CO2. Both admixed fractions are supposed to be fertile. The Closepet granite emplaced in a major shear zone that delimitates two different terrains. Generally such shear zones, at many places, are supposed to be rooted deep into the mantle. The drain, that favoured and controlled magma ascent and emplacement, seemed to remain efficient after granite crystallization. In the southern part of the Closepet batholiths an evidence of intensive interaction of a lower crust fluid (of high CO2 activity) is provided by the extensive charnockitization of amphibolite facies (St

  13. Petrography and Physicomechanical Properties of Rocks from the Ambela Granitic Complex, NW Pakistan

    Directory of Open Access Journals (Sweden)

    Mohammad Arif

    2013-01-01

    Full Text Available Petrography and physicomechanical properties of alkali granites, alkali quartz syenite, and nepheline syenite from Ambela, NW Pakistan, have been investigated. Whereas the alkali quartz syenite and most of the alkali granites are megaporphyritic, the nepheline syenite and some of the alkali granites are microporphyritic. Their phenocryst shape and size and abundance of groundmass are also different. The values of unconfined compressive strength (UCS are the lowest and highest for megaporphyritic alkali granite and alkali quartz syenite, respectively. However, all the four rock types are moderately strong. Correspondingly, their specific gravity and water absorption values are within the permissible range for use as construction material. The UCS for the alkali quartz syenite is the highest, most probably because (i it has roughly equal amounts of phenocryst and groundmass, (ii it displays maximum size contrast between phenocryst and groundmass, (iii its phenocrysts are highly irregular, and (iv it contains substantial amounts of quartz.

  14. LGR adult trap data - Operation of the adult trap at Lower Granite Dam

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This Bonneville Power Administration (BPA) - funded project pays for NOAA staff to operate the adult salmon trap located in the fish ladder at Lower Granite Dam. The...

  15. Some geochemical characteristics of alkaline rocks of the Mada Younger Granite complex, Nigeria

    Science.gov (United States)

    Abaa, S. I.

    Some geochemical aspects of the Mada Younger Granite complex are considered. The granites are petrologically classified as A-type, of long time duration, with chemical differences arising from the variation in the A/CNK ratio. The CPW norms show a decrease in anorthite and an increase in corundum in the granites associated with disseminated and vein type cassiterite mineralization. The KRb diagram shows that rocks of the Mada massif crystallized within a pegmatitic-hydrothermal trend. Some chondrite-normalized transition elements indicate that the rocks unaffected by fluid reaction were derived by fractional crystallization. The enhancement of some LIL elements, heavy rare-earths and a decrease in the magnitude of Eu depletion, particularly in the albitized variants of the granites, point to postmagmatic rock-fluid metasomatism and accompanying mineralization.

  16. Relations between A-type granites and copper mineralization as exemplified by the Machangqing Cu deposit

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper deals with the relations between the Machangqing rockbody which corresponds to the A-type granites and porphyry copper mineralization in terms of petrochemistry,trace element geochemistry,fluid inclusion geochemistry and isotope geochemistry.The results show that the Machangqing porphyry copper deposit was formed from the fluid predominated by magmatic fluid.This kind of ore-forming fluid was just differentiated from the magma responsible for the A-type granites.Therefore,as viewed from whether they contain water or not,the A-type granites can,at least,be divided into two types:water-bearing and water-free.The water-bearing A-type granites can serve as the host of porphyry copper deposits under certain geological conditions.

  17. Relations between A-type granites and copper mineralization as exemplified by the Machangqing Cu deposit

    Institute of Scientific and Technical Information of China (English)

    毕献武; 胡瑞忠; 叶造军; 邵树勋

    2000-01-01

    This paper deals with the relations between the Machangqing rockbody which corresponds to the A-type granites and porphyry copper mineralization in terms of petrochemistry, trace element geochemistry, fluid inclusion geochemistry and isotope geochemistry. The results show that the Machangqing porphyry copper deposit was formed from the fluid predominated by mag-matic fluid. This kind of ore-forming fluid was just differentiated from the magma responsible for the A-type granites. Therefore, as viewed from whether they contain water or not, the A-type granites can, at least, be divided into two types: water-bearing and water-free. The water-bearing A-type granites can serve as the host of porphyry copper deposits under certain geological conditions.

  18. Experimental melts from crustal rocks: A lithochemical constraint on granite petrogenesis

    Science.gov (United States)

    Gao, Peng; Zheng, Yong-Fei; Zhao, Zi-Fu

    2016-12-01

    Many studies of experimental petrology have devoted to partial melting of crustal rocks. In order to provide lithochemical constraints on granite petrogenesis, this paper presents a compilation and synthesis of available experimental data for the major element compositions of felsic melts derived from partial melting of natural or synthetic materials in the compositional range of crustal rocks. The experimental melts are categorized into four types according to the species of hydrous minerals in starting materials: (I) amphibole-bearing; (II) amphibole- and biotite-bearing; (III) biotite-bearing; and (IV) biotite- and muscovite-bearing. If dehydration melting takes place at normal crustal conditions (P = 5-10 kbar, T ≤ 1000 °C), experimental melts are rich in SiO2 but poor in MgO + FeOT except those from amphibole-bearing sources. A comprehensive comparison of compositions between experimental melts and starting materials indicates that geochemical fractionation is variable for different major elements and their ratios. Source composition and melting temperature exert stronger controls on the compositional variations of experimental melts than pressure and fluid. By comparing the experimental melts with natural granites, the following insights into granite petrogenesis can be got: (1) while peritectic assemblage entrainment may be the dominant mechanism for the compositional variations of garnet/cordierite-rich S-type granites, fractional crystallization of diverse melts from heterogeneous metasedimentary precursors probably governs the compositional variations of garnet/cordierite-poor S-type granites; (2) relatively K2O-rich mafic to intermediate rocks are appropriate sources for calc-alkaline I-type granites. The compositional variations of calc-alkaline granites are jointly controlled by peritectic assemblage entrainment and subsequent fractional crystallization; (3) while dehydration melting at T > 950 °C is appropriate for the production of ferroan and

  19. Quantitative Analysis of the Loads Acting on the Abrasive Grits in the Diamond Sawing of Granites

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An experimental study was carried out to quantitati ve ly evaluate the loads acting on the diamond grits during circular sawing of two kinds of typical granite with diamond segmented saw blade. Measurements were mad e of the horizontal and vertical force components and the consumed power in order to obtain the tangential and the normal force components. The temperatures at the diamond-granite contact zone were measured using a foil thermocouple. T he measurement, together with the net sawing power, was...

  20. Age and generation of Fogang granite batholith and Wushi diorite-hornblende gabbro body

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Fogang granitic batholith, the largest Late Mesozoic batholith in the Nanling region, has an exposure area of ca. 6000 km2. Wushi diorite-hornblende gabbro body is situated at the northeast part of the ba- tholith. Both the granitic batholith main body and the diorite-hornblende gabbro body belong to high-K calc alkaline series. Compared with the granitic main body, the Wushi body has lower Si (49%―55%), higher Fe, Mg, Ca, lower REE, less depletion of Eu, Ba, P, Ti, and obvious depletion of Zr, Hf. Zircon LA-ICP-MS dating and the mineral-whole rock isochron dating reveal that Fogang granitic main body and Wushi body were generated simultaneously at ca. 160 Ma. The Fogang granitic main body has high (87Sr/86Sr)i ratios (0.70871―0.71570) and low εNd(t) values (?5.11―?8.93), suggesting the origins of the granitic rocks from crustal materials. Their Nd two-stage model ages range from 1.37―1.68 Ga. The Sr and Nd isotopic compositions and the Nd model ages of the granitic rocks may suggest that the giant Fogang granitic main body was generated from a heterogeneous source, with participation of mantle component. Wushi diorite-hornblende gabbro is an unusual intermediate-basic magmatic rock series, with high (87Sr/86Sr)i ratios (0.71256―0.71318) and low εNd(t) values (?7.32―?7.92), which was possibly formed through mixing between the mantle-derived juvenile basaltic magma and the magma produced by the dehydration melting of lower crustal basaltic rocks.

  1. Age and generation of Fogang granite batholith and Wushi diorite-hornblende gabbro body

    Institute of Scientific and Technical Information of China (English)

    XU XiSheng; LU WeiMin; HE ZhenYu

    2007-01-01

    Fogang granitic batholith, the largest Late Mesozoic batholith in the Nanling region, has an exposure area of ca. 6000 km2. Wushi diorite-hornblende gabbro body is situated at the northeast part of the batholith. Both the granitic batholith main body and the diorite-hornblende gabbro body belong to high-K calc alkaline series. Compared with the granitic main body, the Wushi body has lower Si (49%―55%), higher Fe, Mg, Ca, lower REE, less depletion of Eu, Ba, P, Ti, and obvious depletion of Zr, Hf. Zircon LA-ICP-MS dating and the mineral-whole rock isochron dating reveal that Fogang granitic main body and Wushi body were generated simultaneously at ca. 160 Ma. The Fogang granitic main body has high (87Sr/86Sr)I ratios (0.70871―0.71570) and low eNd(t) values (-5.11―-8.93), suggesting the origins of the granitic rocks from crustal materials. Their Nd two-stage model ages range from 1.37―1.68 Ga. The Sr and Nd isotopic compositions and the Nd model ages of the granitic rocks may suggest that the giant Fogang granitic main body was generated from a heterogeneous source, with participation of mantle component. Wushi diorite-hornblende gabbro is an unusual intermediate-basic magmatic rock series, with high (87Sr/86Sr)I ratios (0.71256―0.71318) and low eNd(t) values (-7.32―-7.92), which was possibly formed through mixing between the mantle-derived juvenile basaltic magma and the magma produced by the dehydration melting of lower crustal basaltic rocks.

  2. Assessment of occupational exposure in a granite quarry and processing factory.

    Science.gov (United States)

    Tejado, J J; Guillén, J; Baeza, A

    2016-09-01

    Workers in the granite industry face an occupational hazard: silicosis due to the crystalline silica present in inhalable dust. As granite can also present a variable, and occasionally significant, content of naturally occurring radionuclides, they may also face a radiological hazard. In order to assess the risk, a granite industry with a quarry and processing factory was selected to assess the occupational exposure. Three main potential pathways were observed: external irradiation, inhalation of granite dust, and radon exposure. The external dose rate was similar to that in a nearby farming area. A slight increment (0.016-0.076 mSv yr(-1)) was observed in the quarry and stockpile, due to quarry faces and granite blocks. The effective dose due to granite dust inhalation was 0.182  ±  0.009 mSv yr(-1) in the worst case scenario (3 mg m(-3) dust load in air and no use of filter masks). Thus, the mean value of the effective dose from these two pathways was 0.26 mSv yr(-1), lower than the reference level of 1 mSv yr(-1) for the general population. The annual mean value of radon concentration in the indoor air was 33 Bq m(-3). However, during granite processing works the radon concentration can increase up to 216 Bq m(-3), due to mechanical operations (sawing, polishing, sanding, etc). This radon concentration was below the 600 Bq m(-3) reference level for action in working places. Therefore, workers in this granite factory face no significant additional radiological exposure, and no-one needs to be designated as occupationally exposed and subject to individual dosimetry.

  3. Origin of Li-F-rich granite:Evidence from high P-T experiments

    Institute of Scientific and Technical Information of China (English)

    LI Fuchun; ZHU Jinchu; RAO Bing; JIN Zhangdong; ZHANG Linsong

    2004-01-01

    Though magmatic origin of Li-F-rich granite has been supported effectively by the existence of volcanic and subvolcanic rocks and melt inclusions trapped in them with similar chemical compositions, evidence from high T-P experiments is poor up to now. To simulate the evolution process of Li-F-rich granite and to interpret its forming mechanism, a series of meltingcrystallization experiments were carried out. Under the conditions of 1x108 Pa and 570-700℃,a magmatic mineral association of quartz + alkali feldspar + lithium muscovite/ferromuscovite ±fluorite ± cassiterite is found in leucogranite-HF-H2O system. This indicates the following points:(i) Fluorite, light-colored muscovite and cassiterite can crystallize directly from the Li-F-rich granitic melt. (ii) The coexistence of dark-colored micas (e.g. biotite) and light-colored micas (e.g.lithium muscovite and ferromuscovite) suggests that the muscovite granite and two-mica granite can be formed under magmatic condition. The zonal texture of micas is not the sole feature for the micas of hydrothermal origin. (iii) As crystallization proceeds, the SiO2 concentration of the residual melt decreases, while the Al2O3 and F concentrations and A/CNK, NKA/Si ratios of the melt incerese, favoring the formation of Li-F-rich granites. Our experiment results are well consistent with the vertical zonation widely observed in rare metal bearing granites, and therefore provide strong experimental evidence for magmatic origin of Li-F-rich granite.

  4. Origin of Li-F-rich granite: Evidence from high P-T experiments

    Institute of Scientific and Technical Information of China (English)

    LI; Fuchun; ZHU; Jinchu; RAO; Bing; JIN; Zhangdong; ZHANG

    2004-01-01

    Though magmatic origin of Li-F-rich granite has been supported effectively by the existence of volcanic and subvolcanic rocks and melt inclusions trapped in them with similar chemical compositions, evidence from high T-P experiments is poor up to now. To simulate the evolution process of Li-F-rich granite and to interpret its forming mechanism, a series of meltingcrystallization experiments were carried out. Under the conditions of 1x108 Pa and 570-700℃,a magmatic mineral association of quartz + alkali feldspar + lithium muscovite/ferromuscovite ±fluorite ± cassiterite is found in leucogranite-HF-H2O system. This indicates the following points:(i) Fluorite, light-colored muscovite and cassiterite can crystallize directly from the Li-F-rich granitic melt. (ii) The coexistence of dark-colored micas (e.g. biotite) and light-colored micas (e.g.lithium muscovite and ferromuscovite) suggests that the muscovite granite and two-mica granite can be formed under magmatic condition. The zonal texture of micas is not the sole feature for the micas of hydrothermal origin. (iii) As crystallization proceeds, the SiO2 concentration of the residual melt decreases, while the Al2O3 and F concentrations and A/CNK, NKA/Si ratios of the melt incerese, favoring the formation of Li-F-rich granites. Our experiment results are well consistent with the vertical zonation widely observed in rare metal bearing granites, and therefore provide strong experimental evidence for magmatic origin of Li-F-rich granite.

  5. Gamma-spectrometric surveys in differentiated granites. II: the Joaquim Murtinho Granite in the Cunhaporanga Granitic Complex, Parana, SE Brazil; Levantamentos gamaespectrometricos em granitos diferenciados. II: O exemplo do Granito Joaquim Murtinho, Complexo Granitico Cunhaporanga, Parana

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Francisco Jose Fonseca [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Geologia. Lab. de Pesquisas em Geofisica Aplicada; Fruchting, Allan [Votorantim Metais, Sao Paulo, SP (Brazil)], e-mail: allan.fruchting@vmetais.com.br; Guimaraes, Gilson Burigo [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil). Dept. de Geociencias], e-mail: gburigo@ig.com.br; Alves, Luizemara Soares [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)], e-mail: luizemara@petrobras.com.br; Martin, Victor Miguel Oliveira; Ulbrich, Horstpeter Herberto Gustavo Jose [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Dept. de Mineralogia e Geotectonica], e-mail: vicmartin6@ig.com.br, e-mail: hulbrich@usp.br

    2009-07-01

    Detailed mapping at the NW corner of the large Neo proterozoic Cunhaporanga Granitic Complex (CGC), Parana state, SE Brazil, redefined the Joaquim Murtinho Granite (JMG), a late intrusion in CGC with an exposed area of about 10 km{sup 2}, made up mainly by evolved 'alaskites' (alkali-feldspar leuco granites). This unit is in tectonic contact with the Neoproterozoic-Eocambrian volcano-sedimentary Castro Group, to the W, and is intrusive into other less evolved granitic units of the CGC to the E. Petrographically, JMG shows mainly mesoperthite and quartz, with subordinate amounts of altered micas and some accessory phases, mainly zircon. The equi to inequigranular granites are usually deformed with cataclastic textures, are often brecciated, and may have miarolitic structures. Formation of late albite, sericite, carbonate and hematite was caused by deuteric and hydrothermal alteration. A gamma-ray spectrometric survey at 231 stations which measured total counts (TC), Ueq K%, eU ppm and eTh ppm was used to construct several direct and derived maps. Compared to neighboring units the JMG has significant anomalies, especially in the TC, %K, eTh and eU maps, although the differences are less obvious in some derived maps. These evolved granites are enriched in these three elements. Geochemical behavior of K, Th and U is used to analyse the results observed in maps. Enhanced weathering under a subtropical climate with moderate to high average temperatures and heavy rainfall affects mainly feldspars and biotite, and may also destabilize most U and Th-bearing accessory phases. Th is most likely retained in restite minerals in soils, being relatively immobile, while part of U may migrate as uranyl ion in oxidizing media. K is especially affected by feldspar alteration to K-free clays (mainly kaolinite), and may be completely leached. Gamma-ray spectrometric methods are valid tools to study facies in granitic rocks, especially in those that are enriched in K, Th and U

  6. Operation of the Lower Granite Dam Adult Trap, 2008.

    Energy Technology Data Exchange (ETDEWEB)

    Harmon, Jerrel R.

    2009-01-01

    During 2008 we operated the adult salmonid trap at Lower Granite Dam from 7 March through 25 November, except during a short summer period when water temperatures were too high to safely handle fish. We collected and handled a total of 20,463 steelhead Oncorhynchus mykiss and radio-tagged 34 of the hatchery steelhead. We took scale samples from 3,724 spring/summer Chinook salmon O. tshawytscha for age and genetic analysis. We collected and handled a total of 8,254 fall Chinook salmon. Of those fish, 2,520 adults and 942 jacks were transported to Lyons Ferry Hatchery on the Snake River in Washington. In addition, 961 adults and 107 jacks were transported to the Nez Perce Tribal Hatchery on the Clearwater River in Idaho. The remaining 3,724 fall Chinook salmon were passed upstream. Scales samples were taken from 780 fall Chinook salmon tagged with passive integrated transponder (PIT) tags and collected by the sort-by-code system.

  7. METALLOGENY OF EOCENE SYNCOLLISIONAL GRANITES OF MOTAJICA AND PROSARA MOUNTAINS

    Directory of Open Access Journals (Sweden)

    Ivan Jurković

    2004-12-01

    Full Text Available The geological setting is dominated by Eocene (48.7 Ma syncollisional granitoids in the form of a small pluton in the Motajica Mt. and in the form of numerous sills and dykes in the Prosara Mt. Microelement paragenesis of these magmatites, pegmatites, greisens and quartz veins are distinguished by U, Th, Ce, Y, P, Nb, Ta, B, Li, F, Be, Sn, Mo, W, Fe, Cu, Pb. These elements and 87Sr/86Sr and 18O isotopic values indicate the mantle origin of magma contaminated by relatively sterile lithospheric rocks. The most probable hypothesis of such a hybrid magma formation is the "slab break-off model". Deep erosion of Motajica granitoid pluton opened its acrobatholitic and epibatholitic level with numerous, but small pegmatite deposits (beryllites, tourmalinites, emeraldites and sylexites with piezoelectric quartz. Greisenization marked by strong silicification and muscovitization affected less than 1% of pluton. It is characterized by minor and accessory molybdenite, wolframite, huebnerite, scheelite, fluorite. Hydrothermal occurrences, galena and Fe minerals have only a mineralogical significance. Economically significant are numerous autochthonous kaolin deposits formed in Pliocene-Pleistocene time. Prosara apomagmatic granitoids, exclusively granite dykes are metallogenetically sterile.

  8. Geology and Genesis of Peraluminous Granites in East Tianshan Upper Paleozoic Island Arc Belt

    Institute of Scientific and Technical Information of China (English)

    顾连兴; 严正富; 等

    1996-01-01

    A peraluminous granite belt occurs along the connecting zone between the Turpan Hami Precambrian block and the Upper Paleozoic island arc belt.Muscovite granite and twomica granite are the essential lithological components of that belt.All the potassium feldspars in these granites are microcline.Heavy minerals are dominated by magnetite,SiO2 contents of these granites are greater than 73% with most of the A/NKC values greater than 1,1,norma tive corundum values greater than 1 Plots of CIPW norms in the (Al-K-Na) Ca(Fe2++Mg) diagran are mostly situated in the plagioclase cordierite-muscovite region.The rocks are characterized by very low contents of minor elements and ∑REE with strong Eu depletion δ18 O values between 6.6‰and 7.0‰,Rb-Sr isochron age of 260.2±6.2Ma and an initial 87Sr/86 Sr ration of 0.7052,These granites might have been produced by partial melting of moderately acidic volcanites and low-maturity sediments in the basement sequences and could be genetically connected with the southware A-type subduction of the Turpan-Hami block following the closure of the Middle Carboniferous back-arc basin.

  9. SHRIMP zircon U-Pb geochronology of Indosinian granites in Hunan Province and its petrogenetic implications

    Institute of Scientific and Technical Information of China (English)

    WANG Yuejun; FAN Weiming; LIANG Xinquan; PENG Touping; SHI Yuruo

    2005-01-01

    The SHRIMP zircon U-Pb geochronology of three typically Indosinian granitic plutons with peraluminous and potassium-rich affinities (Tangshi ultraunit for Weishan and Baimashan, and Longtan ultraunit for Guandimiao) is presented in Hunan Province, South China. The analyses of zircons from biotite monozonite granites for Weishan, Baimashan and Guandimiao plutons show the single and tight clusters on the concordia, and yield the weighted mean 206Pb/238U ages of 244±4, 243±3 and 239±3 Ma, respectively, representing the crystallized ages of these Indosinian granites. These data suggest that the Indosinian granitic plutons as previously thought formed at a narrow age span. In combination with other data, it is inferred that the Indosinian granites within the South China Block probably distributed in Hunan, Jiangxi, Guangxi and Guangdong provinces as planar shape, and were the derivation of the crustal materials in the intracontinental thickening setting. These precisely geochronological data provide important constraints for better understanding the spatiotemporal pattern of the Indosinian peraluminous granites and early Mesozoic tectonic evolution of the South China Block.

  10. SHRIMP zircon U-Pb dating in Jingshan "migmatitic granite", Bengbu and its geological significance

    Institute of Scientific and Technical Information of China (English)

    XU Wenliang; WANG Qinghai; YANG Debin; LIU Xiaochun; GUO Jinghui

    2005-01-01

    The petrographic characteristics of Jingshan "migmatitic granite" and the occurrence of the magmatic zircons indicate that the granite was formed by normal crystallization of felsic melts. All zircons in the granite have inherited cores and fine-scale oscillatory zoning rims of magmatic origin. It is realized that the granite was formed at 160.2±1.3 Ma through dating magmatic zircons. The generation of the granitic magma could be related to the lithospheric mantle and/or lower crust delamination after the ultrahigh pressure metamorphism (UHPM) in Triassic. Most inherited zircons yield the ages of 217.1±6.6 Ma, which is consistent with the peak UHPM in the Dabie-Sulu orogenic belt. Some of the inherited zircons (433-722 Ma) constitute a discordia line with the upper intercept age of 850+85/-68 Ma and a lower intercept age of 261+100/-140 Ma. These ages imply that the granite could be derived from the partial melting of the crustal materials of the South China Block that was intensively superimposed by the UHPM. The UHPM could be the reason for the major Pb loss at ±220 Ma.

  11. Modeling and numerical analysis of granite rock specimen under mechanical loading and fire

    Directory of Open Access Journals (Sweden)

    Luc Leroy Ngueyep. Mambou

    2015-02-01

    Full Text Available The effect of ISO 834 fire on the mechanical properties of granite rock specimen submitted to uniaxial loading is numerically investigated. Based on Newton's second law, the rate-equation model of granite rock specimen under mechanical load and fire is established. The effect of heat treatment on the mechanical performance of granite is analyzed at the center and the ends of specimen. At the free end of granite rock specimen, it is shown that from 20 °C to 500 °C, the internal stress and internal strain are weak; whereas above 500 °C, they start to increase rapidly, announcing the imminent collapse. At the center of specimen, the analysis of the internal stress and internal strain reveals that the fire reduces the mechanical performance of granite significantly. Moreover, it is found that after 3 min of exposure to fire, the mechanical energy necessary to fragment the granite can be reduced up to 80%.

  12. Weathering-associated bacteria from the Damma glacier forefield: physiological capabilities and impact on granite dissolution.

    Science.gov (United States)

    Frey, Beat; Rieder, Stefan R; Brunner, Ivano; Plötze, Michael; Koetzsch, Stefan; Lapanje, Ales; Brandl, Helmut; Furrer, Gerhard

    2010-07-01

    Several bacterial strains isolated from granitic rock material in front of the Damma glacier (Central Swiss Alps) were shown (i) to grow in the presence of granite powder and a glucose-NH(4)Cl minimal medium without additional macro- or micronutrients and (ii) to produce weathering-associated agents. In particular, four bacterial isolates (one isolate each of Arthrobacter sp., Janthinobacterium sp., Leifsonia sp., and Polaromonas sp.) were weathering associated. In comparison to what was observed in abiotic experiments, the presence of these strains caused a significant increase of granite dissolution (as measured by the release of Fe, Ca, K, Mg, and Mn). These most promising weathering-associated bacterial species exhibited four main features rendering them more efficient in mineral dissolution than the other investigated isolates: (i) a major part of their bacterial cells was attached to the granite surfaces and not suspended in solution, (ii) they secreted the largest amounts of oxalic acid, (iii) they lowered the pH of the solution, and (iv) they formed significant amounts of HCN. As far as we know, this is the first report showing that the combined action of oxalic acid and HCN appears to be associated with enhanced elemental release from granite, in particular of Fe. This suggests that extensive microbial colonization of the granite surfaces could play a crucial role in the initial soil formation in previously glaciated mountain areas.

  13. Regional and local controls on mineralization and pluton emplacement in the Bondy gneiss complex, Grenville Province, Canada interpreted from aeromagnetic and gravity data

    Science.gov (United States)

    Dufréchou, G.; Harris, L. B.; Corriveau, L.; Antonoff, V.

    2015-05-01

    The Bondy gneiss complex in the Grenville Province of Southwest Quebec hosts a mineralized iron oxide- and copper-rich hydrothermal system. The northern part of the complex overlies the lithospheric-scale Mont-Laurier lineament and is cut by the regional Mont-Laurier South shear zone interpreted from Bouguer gravity. A sinistral 6 km wide strike-slip corridor defined by several second-order shears (the Mont-Laurier South shear zone) in the complex was identified from geophysical data, including a new high-resolution airborne magnetic survey, and field observations. The spatial association of a metamorphosed alteration system, several pre- to post-metamorphic mineralized zones and mafic intrusions within the Mont-Laurier South shear zone suggests that (i) underlying basement structures controlled hydrothermal fluid migration during the formation of epithermal-IOCG mineralization and associated alteration system before ca. 1.2 Ga high-grade metamorphism and penetrative ductile deformation in the complex; (ii) post-metamorphic reactivation allowed magma ascent and pluton emplacement in the complex and adjacent supracrustal rocks within dilatational sites; and (iii) brittle-ductile shears that postdate high-grade metamorphism provided channel ways for fluid migration associated with magnetite-related mineralization. Although the complex does not host an economic mineral deposit, the role between structures at different levels and the combination of gravity and aeromagnetics at different scales provides an example of an approach for mineral exploration in similar high grade gneiss terrains.

  14. A multiscale analysis of a fracture pattern in granite: A case study of the Tamariu granite, Catalunya, Spain

    Science.gov (United States)

    Bertrand, Lionel; Géraud, Yves; Le Garzic, Edouard; Place, Joachim; Diraison, Marc; Walter, Bastien; Haffen, Sébastien

    2015-09-01

    The in-depth investigation of fractured reservoirs is mainly limited to geophysical data that is in 3D and mostly on the scale of hundred meters to several kilometers or boreholes data that is in 1D and at meter to lower scale. The study of outcropping analogues of buried reservoirs is therefore a key tool for the characterization of the fault and fracture network at the reservoir scale. Tamariu granite has been the subject of this study with the aim to analyse faults and fractures from seismic to borehole scale. With the combination of satellite picture at different resolution and field study, we perform a statistical analysis focused of the length and orientation from infra centimeter crack to hundred kilometer length fault. On the whole range of scale studied, i.e. on 7 orders of magnitude, we have defined a length distribution following a power-law with an exponent a = -2. On the contrary to the length that can be modelled with a unique law, the orientation data shows a variation depending on the scale of observation: as the fault and fracture sets are suitable from the regional faults to the centimeter crack, the proportion of the sets varies at each scale of observation.

  15. Geochemical characteristics and origin of the Lebowa Granite Suite, Bushveld Complex

    Science.gov (United States)

    Hill, M.; Barker, F.; Hunter, D.; Knight, R.

    1996-01-01

    The ??? 2052-Ma Lebowa Granite Suite (LGS) represents the culminating phase of an Early Proterozoic magmatic cycle in the Central Transvaal area of the Kaapvaal Province. Following extrusion of at least 200,000 km3 of intermediate to acid volcanics (Rooiberg Felsite), mafic and ultramafic magmas intruded at 2065 Ma to form the Rustenburg Layered Suite (RLS). The LGS includes the Nebo, Makhutso, Bobbejaankop, Lease, and Klipkloof granites. The Nebo Granite intruded the Rooiberg Felsite as sheets up to 4 km thick above the RLS. Smaller stocks of the other granites crosscut the Nebo. We determined major- and trace-element compositions and oxygen, Rb-Sr, and Sm-Nd isotope ratios for samples of: Nebo Granite; Rooiberg Felsite; granophyre and granophyric granite; Makhutso, Bobbejaankop, and Lease granites; and feldspar porphyry from areas throughout the exposed area of the LGS (Dennilton, Verena Balmoral, Enkeldoorn, Sekhukhune Plateau, Zaaiplaats-Potgeitersrus, and Western Transvaal). Coherent floor-to-roof geochemical trends exist in some areas, although it is not possible to model them convincingly. Regional variations in geochemistry exist and likely are related to source variations in the estimated 200,000 km3 of the Nebo Granite sheets. ??18O for the LGS range from +5.9??? to +9.5???; if these are approximate primary magmatic values, pelitic sediments cannot have been an important source for the LGS. The Rb-Sr isotope system has been altered, a finding consistent with previous studies. A mineral isochron for Nebo Granite near Dennilton yields a York regression age of 1995 ?? 99 Ma, with initial 143Nd/144Nd = 0.50978??8 and ???CHUR=-5.12. Samples from the Sekhukhune Plateau have higher 143Nd/144Nd ratios than do Dennilton-area samples, suggesting that the former originated from older or less LREE-enriched sources. We suggest that intrusion of mafic to ultramafic magmas at depth in the continental crust triggered melting of Archean quartzofeldspathic crystalline

  16. Differential weathering of basaltic and granitic catchments from concentration-discharge relationships

    Science.gov (United States)

    Ibarra, Daniel E.; Caves, Jeremy K.; Moon, Seulgi; Thomas, Dana L.; Hartmann, Jens; Chamberlain, C. Page; Maher, Kate

    2016-10-01

    A negative feedback between silicate weathering rates and climate is hypothesized to play a central role in moderating atmospheric CO2 concentrations on geologic timescales. However, uncertainty regarding the processes that regulate the operation of the negative feedback limits our ability to interpret past variations in the ocean-atmosphere carbon cycle. In particular, the mechanisms that determine the flux of weathered material for a given climatic state are still poorly understood. Here, we quantify the processes that determine catchment-scale solute fluxes for two lithologic end-members-basalt and granite-by applying a recently developed solute production model that links weathering fluxes to both discharge and the reactivity of the weathering material. We evaluate the model against long-term monitoring of concentration-discharge relationships from basaltic and granitic catchments to determine the parameters associated with solute production in each catchment. Higher weathering rates in basaltic catchments relative to granitic catchments are driven by differing responses to increases in runoff, with basaltic catchments showing less dilution with increasing runoff. In addition, results from the solute production model suggest that thermodynamic constraints on weathering reactions could explain higher concentrations in basaltic catchments at lower runoff compared to granitic catchments. To understand how the response to changing discharge controls weathering fluxes under different climatic states, we define basalt/granite weatherability as the ratio of the basalt catchment flux to the granite catchment flux. This weatherability is runoff-dependent and increases with increasing runoff. For HCO3- and SiO2(aq) fluxes, for modern global runoff, the derived mean basalt/granite weatherability is 2.2 (1.3-3.7, 2σ) and 1.7 (1.6-2.1, 2σ), respectively. Although we cannot determine the array of individual processes resulting in differences among catchments, the relative

  17. Crystallization and uplift path of late Variscan granites evidenced by quartz chemistry and fluid inclusions: Example from the Land's End granite, SW England

    Science.gov (United States)

    Drivenes, Kristian; Larsen, Rune Berg; Müller, Axel; Sørensen, Bjørn Eske

    2016-05-01

    The megacrystic, coarse-grained granite of the Land's End granitic complex, SW England, has been investigated by analyzing fluid inclusions, trace elements, and cathodoluminescence textures of quartz. By applying the TitaniQ geothermobarometer together with the cathodoluminescence textures, a two-stage emplacement process is proposed. K-feldspar and quartz phenocrysts crystallized in a deep magma chamber at ca. 18-20 km depth. The phenocrysts were transported together with the melt to a shallow emplacement depth at ca. 5-9 km in multiple intrusive events, causing the composite appearance of the granitic complex. This model of emplacement concurs with similar granites from the Erzgebirge. At the emplacement level, the magma exsolved an aqueous fluid with average salinity of 17.3% m/m NaCl and 9.7% m/m CaCl2. Fluids with higher salinities were exsolved deeper in the system, as the magma experienced stages of water saturation and water undersaturation during ascent from the deep magma chamber. The complex fluid inclusion textures are the results of multiple stages of entrapment of aqueous fluids in the host phases as multiple recharge events from the deeper magma chamber supplied fresh melts and aqueous volatiles. Titanium contents in quartz are closely related to the panchromatic cathodoluminescence intensity, and the Al/Ti ratio is reflected by the 3.26 eV/2.70 eV ratio of hyperspectral cathodoluminescence.

  18. The composition of zircon in Variscan granites from Northern Portugal

    Directory of Open Access Journals (Sweden)

    Martins, H. C.B.

    2014-12-01

    Full Text Available A group of slightly peraluminous Variscan plutons in Northern Portugal were selected from the study of zircon composition. The selected plutons are: the Vila Pouca de Aguiar and the Lavadores-Madalena plutons with I-type affinities and the Vieira do Minho pluton, an l-S transitional type. Zircon occurs as euhedral to subhedral crystals and exhibit finely concentric oscillatory magmatic zoning mainly related to variations of Hf, Y, U and Th concentrations. Most zircon crystals show the dominant “xenotime” substitution. The zircon crystals have Zr/Hf ratio in the range of 21 to 52, with no significant differences between the different granites. These values are in the same range of other peraluminous granites and are in accordance with a crustal signature of zircon. Moreover, the range of Zr/Hf values in zircon crystals overlaps with that of crustal sources and consequently to the potential protoliths proposed in the genesis of the Vieira do Minho and the Vila Pouca de Aguiar plutons, namely meta-igneous crustal sources at different levels. Although zircon from the Lavadores-Madalena pluton has a compositional range similar to the other plutons, an origin by hibridisation has been proposed. However, similar zircon chemistry between this pluton and Vila Pouca de Aguiar and Vieira do Minho plutons could also suggest a similar crustal source.Se han seleccionado tres plutones graniticos variscos en el norte de Portugal para el estudio de la composición del circón. Los plutones son: Vila Pouca de Aguiar y Lavadores-Madalena con afinidad de tipo-I y el plutón de Vieira do Minho de tipo transicional I-S. Los circones se presentan en cristales euhédricos a subhédricos y tienen zonados magmáticos, concéntricos oscilatorios finos ligados principalmente a variaciones de las concentraciones del Hf, Y, U y Th. La mayoría de los cristales de circón muestran la sustitución dominante “xenotima”. Los zircones tienen relaciones Zr/Hf que var

  19. Highly evolved juvenile granites with tetrad REE patterns: the Woduhe and Baerzhe granites from the Great Xing'an Mountains in NE China

    Science.gov (United States)

    Jahn, Bor-ming; Wu, Fuyuan; Capdevila, R.; Martineau, F.; Zhao, Zhenhua; Wang, Yixian

    2001-12-01

    In NE China, voluminous granitoids were emplaced in late Paleozoic and Mesozoic times. We report here Sr-Nd-O isotopic and elemental abundance data for two highly evolved granitic plutons, Woduhe and Baerzhe, from the Great Xing'an Mountains. They show a rather "juvenile" Sr-Nd isotopic signature and a spectacular tetrad effect in their REE distribution patterns as well as non-CHARAC (charge-and-radius-controlled) trace element behavior. The emplacement ages are constrained at 130±4 Ma for the Woduhe and 122±5 Ma for the Baerzhe granites by Rb-Sr and Sm-Nd isotope analyses. Both granites are also characterized by low but imprecise initial 87Sr/ 86Sr ratios of about 0.703. The Nd-Sr isotope data argue for their generation by melting of dominantly juvenile mantle component with subordinate recycled ancient crust. This is largely compatible with the general scenario for much of the Phanerozoic granitoids emplaced in the Central Asian Orogenic Belt. The parental magmas for both the Woduhe and Baerzhe granites have undergone extensive magmatic differentiation, during which intense interaction of the residual melts with aqueous hydrothermal fluids (probably rich in F and Cl) resulted in the non-CHARAC trace element behavior and the tetrad effect of REE distribution. Both the Woduhe and Baerzhe granites show the characteristic trace element patterns of rare-metal granites, but their absolute abundances differ by as much as two orders of magnitude. The oxygen isotope compositions of the two granites have been severely disturbed. Significant 18O depletion in feldspar, but not so much in quartz, suggests that the hydrothermal alteration took place in a temperature condition of 300-500 °C. This subsolidus hydrothermal alteration is decoupled from the late-stage magma-fluid interaction at higher temperatures. Despite the two distinct and intense events of "water-rock" interaction, the Rb-Sr and Sm-Nd geochronological systems seem to have maintained closed, hence, suggesting

  20. Textures and melt-crystal-gas interactions in granites

    Institute of Scientific and Technical Information of China (English)

    Jean-Louis Vigneresse

    2015-01-01

    the multiple granitic intrusions of Dolbel, Niger illustrate such events.

  1. Groundwater chemistry of a nuclear waste reposoitory in granite bedrock

    Energy Technology Data Exchange (ETDEWEB)

    Rydberg, J.

    1981-09-01

    This report concerns the prediction of the maximum dissolution rate for nuclear waste stored in the ground. That information is essential in judging the safety of a nuclear waste repository. With a limited groundwater flow, the maximum dissolution rate coincides with the maximum solubility. After considering the formation and composition of deep granite bedrock groundwater, the report discusses the maximum solubility in such groundwater of canister materials, matrix materials and waste elements. The parameters considered are pH, Eh and complex formation. The use of potential-pH (Pourbaix) diagrams is stressed; several appendixes are included to help in analyzing such diagrams. It is repeatedly found that desirable basic information on solution chemistry is lacking, and an international cooperative research effort is recommended. The report particularly stresses the lack of reliable data about complex formation and hydrolysis of the actinides. The Swedish Nuclear Fuel Safety (KBS) study has been used as a reference model. Notwithstanding the lack of reliable chemical data, particularly for the actinides and some fission products, a number of essential conclusions can be drawn about the waste handling model chosen by KBS. (1) Copper seems to be highly resistant to groundwater corrosion. (2) Lead and titanium are also resistant to groundwater, but inferior to copper. (3) Iron is not a suitable canister material. (4) Alumina (Al/sub 2/O/sub 3/) is not a suitable canister material if groundwater pH goes up to or above 10. Alumina is superior to copper at pH < 9, if there is a risk of the groundwater becoming oxidizing. (5) The addition of vivianite (ferrous phosphate) to the clay backfill around the waste canisters improves the corrosion resistance of the metal canisters, and reduces the solubility of many important waste elements. This report does not treat the migration of dissolved species through the rock.

  2. Mechanical amorphization during experimental shearing of synthetic granite gouge

    Science.gov (United States)

    White, J. C.; Hadizadeh, J.; Tullis, T. E.; Goldsby, D. L.

    2009-04-01

    Frictional sliding experiments performed in a rotary shear machine at 25 MPa normal stress on 2-mm thick layers of simulated Westerly granite gouge (initial particle size 1-85 µm) have produced heterogeneous microstructures comprising comminuted material with internal layering. In SEM/BSE individual layers comprise grains of rounded and sub-rounded quartz and feldspar particles that vary in size from 20nm on one side to about 300nm on the other. Characterization of the gouge ultrastructure has been undertaken by analytical scanning transmission electron microscopy (STEM). Areas were selected from high-magnification SEM images and thinned in a focused ion beam instrument (FIB). This sampling procedure produces material of even electron transparency with perfect spatial registration to the optical and SEM microstructures. The sub-micrometre-scale laminar variation of grain size and porosity is confirmed by STEM. Shards of both feldspar and quartz are progressively comminuted to form the texture in which larger grains are surrounded by finer-comminuted matrix material. Grains of both of the latter primary mineral constituents are routinely less than 100 nm in size. Most significantly, the finest grained, least porous zones comprise small grain fragments embedded within an amorphous silicate matrix. By extension, one can infer that observation of these zones throughout the gouge is consistent with extensive amorphization during the shearing. The internal layering of the brecciated fragments, with asymmetric particle size and porosity grading, indicates that Y-slip surfaces localize displacement until particles that line the slip surface are reduced to a critical size that enables mechanically induced amorphization. Fluctuations in friction recorded during formation of this microstructure can be reasonably related to cyclic softening-hardening related to porosity loss and amorphization, with subsequent brecciation of the gouge during slip on multiple Y-slip surfaces.

  3. Alkali control of high-grade metamorphism and granitization

    Directory of Open Access Journals (Sweden)

    Oleg G. Safonov

    2014-09-01

    Full Text Available We review petrologic observations of reaction textures from high-grade rocks that suggest the passage of fluids with variable alkali activities. Development of these reaction textures is accompanied by regular compositional variations in plagioclase, pyroxenes, biotite, amphibole and garnet. The textures are interpreted in terms of exchange and net-transfer reactions controlled by the K and Na activities in the fluids. On the regional scale, these reactions operate in granitized, charnockitized, syenitized etc. shear zones within high-grade complexes. Thermodynamic calculations in simple chemical systems show that changes in mineral assemblages, including the transition from the hydrous to the anhydrous ones, may occur at constant pressure and temperature due only to variations in the H2O and the alkali activities. A simple procedure for estimating the activity of the two major alkali oxides, K2O and Na2O, is implemented in the TWQ software. Examples of calculations are presented for well-documented dehydration zones from South Africa, southern India, and Sri Lanka. The calculations have revealed two end-member regimes of alkalis during specific metamorphic processes: rock buffered, which is characteristic for the precursor rocks containing two feldspars, and fluid-buffered for the precursor rocks without K-feldspar. The observed reaction textures and the results of thermodynamic modeling are compared with the results of available experimental studies on the interaction of the alkali chloride and carbonate-bearing fluids with metamorphic rocks at mid-crustal conditions. The experiments show the complex effect of alkali activities in the fluid phase on the mineral assemblages. Both thermodynamic calculations and experiments closely reproduce paragenetic relations theoretically predicted by D.S. Korzhinskii in the 1940s.

  4. Textures and melt-crystal-gas interactions in granites

    Directory of Open Access Journals (Sweden)

    Jean-Louis Vigneresse

    2015-09-01

    Republic and by the multiple granitic intrusions of Dolbel, Niger illustrate such events.

  5. Fault growth and acoustic emissions in confined granite

    Science.gov (United States)

    Lockner, David A.; Byerlee, James D.

    1992-01-01

    The failure process in a brittle granite was studied by using acoustic emission techniques to obtain three dimensional locations of the microfracturing events. During a creep experiment the nucleation of faulting coincided with the onset of tertiary creep, but the development of the fault could not be followed because the failure occurred catastrophically. A technique has been developed that enables the failure process to be stabilized by controlling the axial stress to maintain a constant acoustic emission rate. As a result the post-failure stress-strain curve has been followed quasi-statically, extending to hours the fault growth process that normally would occur violently in a fraction of a second. The results from the rate-controlled experiments show that the fault plane nucleated at a point on the sample surface after the stress-strain curve reached its peak. Before nucleation, the microcrack growth was distributed throughout the sample. The fault plane then grew outward from the nucleation site and was accompanied by a gradual drop in stress. Acoustic emission locations showed that the fault propagated as a fracture front (process zone) with dimensions of 1 to 3 cm. As the fracture front passed by a given fixed point on the fault plane, the subsequent acoustic emission would drop. When growth was allowed to progress until the fault bisected the sample, the stress dropped to the frictional strength. These observations are in accord with the behavior predicted by Rudnicki and Rice's bifurcation analysis but conflict with experiments used to infer that shear localization would occur in brittle rock while the material is still hardening.

  6. Discovery of A-type Granite Zone and Its Geodynamic Significance in the Western Kunlun Mts., China

    Institute of Scientific and Technical Information of China (English)

    JIANG Yaohui; YANG Wanzhi

    2001-01-01

    There is a distinct zone of A-type granite in western Kunlun Mts. with the scope corresponding to the Kudi mantle steps. The A-type granites generated in late Indosinian, intergrowthing with late Hercynian I-type granites. The characteristics of A-type granitic rocks are enrichment in alkali, LREE,Y, Nb, Zr, lean in Al, Mg, Ca, Ba and Sr transition elements, and extended SiO2 contents, which are quite similar to those of A-type granite in Chaelundi, Australia. The research results indicate that the studied granites belong to A2-type which formed in late orogenic extension environment and intruded in the process of the lithospheric delamination.

  7. Oxygen isotope, fluid inclusion, microprobe and petrographic studies of the preCambrian granites from the southern Wind River range and the Granite Mountains, central Wyoming, U.S.A.: Constraints on origin, hydrothermal alteration and uranium genesis

    Science.gov (United States)

    Cheang, K. K.

    The Granite Mountain is comprised of the granite of Long Creek Mountain and the volumetrically dominant granite of Lankin Dome. Average delta 018 O values in per mil deg/00 of the granite of Long Creek Mountain is 8.2 + or - 0.3 deg/00 (N = 4) and average delta 018 8.5 + or - -0.5 deg/00 (N = 37), values of the two phases from the granite of Lankin Dome are: biotite granites = delta 018 8.5 + or 0.5 deg/00 (N = 37), leucocratic graphite = 8.4 + or - 0.3 deg/00 (N = 12). The average delta 018 values for Louis Lake Batholith are: hornblende-biotite granodiorite = 7.3 + or - 0.3 deg/00 (N = 13) and leucocratic biotite granite = 7.7 + or - 0.1 deg/00 (N = 6). It is concluded from the whole rock oxygen isotopic, mineralogical, chemical and strontium isotopic data that the unaltered granites in the Granite Mountains were probably derived from a uranium enriched source with some peraluminous metasedimentary component which favoured the preconcentration of uranium and thorium, whereas the Louis Lake Batholith was formed by partial melting of igneous source materials that are not strongly enriched in uranium.

  8. Granite disposal of U.S. high-level radioactive waste.

    Energy Technology Data Exchange (ETDEWEB)

    Freeze, Geoffrey A.; Mariner, Paul E.; Lee, Joon H.; Hardin, Ernest L.; Goldstein, Barry; Hansen, Francis D.; Price, Ronald H.; Lord, Anna Snider

    2011-08-01

    This report evaluates the feasibility of disposing U.S. high-level radioactive waste in granite several hundred meters below the surface of the earth. The U.S. has many granite formations with positive attributes for permanent disposal. Similar crystalline formations have been extensively studied by international programs, two of which, in Sweden and Finland, are the host rocks of submitted or imminent repository license applications. This report is enabled by the advanced work of the international community to establish functional and operational requirements for disposal of a range of waste forms in granite media. In this report we develop scoping performance analyses, based on the applicable features, events, and processes (FEPs) identified by international investigators, to support generic conclusions regarding post-closure safety. Unlike the safety analyses for disposal in salt, shale/clay, or deep boreholes, the safety analysis for a mined granite repository depends largely on waste package preservation. In crystalline rock, waste packages are preserved by the high mechanical stability of the excavations, the diffusive barrier of the buffer, and favorable chemical conditions. The buffer is preserved by low groundwater fluxes, favorable chemical conditions, backfill, and the rigid confines of the host rock. An added advantage of a mined granite repository is that waste packages would be fairly easy to retrieve, should retrievability be an important objective. The results of the safety analyses performed in this study are consistent with the results of comprehensive safety assessments performed for sites in Sweden, Finland, and Canada. They indicate that a granite repository would satisfy established safety criteria and suggest that a small number of FEPs would largely control the release and transport of radionuclides. In the event the U.S. decides to pursue a potential repository in granite, a detailed evaluation of these FEPs would be needed to inform site

  9. Determination of the amount of Peroxy in granite rock using the Seebeck Effect

    Science.gov (United States)

    Tregloan-Reed, J. J.; Tarnas, J.; Plante, Z.; Freund, F. T.

    2015-12-01

    We present a series of laboratory experiments which provide evidence for peroxy defects in granite, coupled with a determination of the peroxy defect concentration. When peroxy defects are activated they become defect electrons (positive holes) in the oxygen anion sub-lattice. This in essence converts the granite sample to a p-type semiconductor. Our preliminary results of the thermoelectric (Seebeck) effect for granite show that positive charge carriers are being generated (positive gradient: see Figure) in the granite sample and that the concentration of peroxy defects in the granite sample is 1137 ± 20 ppm. The Seebeck coefficient (α) is the gradient between the voltage (V) and the temperature (T), such that α = V /T . One end of the granite sample was placed in a furnace and heated. At 300ºC the peroxy defect spins decouple, while at 430ºC the peroxy defects dissociate, producing positive holes. When the positive holes are activated their mobility increases and they move towards the cool end of the granite sample through diffusion. This induces a potential difference linked to a thermal gradient between the two ends of the sample. We then fitted the coefficients of two first order polynomials and a point of inflection using a Markov Chain Monte Carlo algorithm. This was done to statistically estimate the uncertainties in the coefficients from a Bayesian statistical analysis. The best fit and corresponding standarderror of the reflection point was found to be 426 ± 5ºC. This is in excellent agreement to values, around 430ºC, found in the literature. We then find α = 18.50 ± 0.18 μV K-1 above 426 ± 5ºC, which equates to a carrier concentration of 1.16 × 1020 cm-3 compared to the carrier concentrations of heavily doped semiconductors, which are on the order of 1021 cm-3. This then gives a peroxy defect concentration of 1137 ± 20 ppm.

  10. Sorption and desorption of cesium on rapakivi granite and its minerals

    Energy Technology Data Exchange (ETDEWEB)

    Huitti, T.; Hakanen, M. [Helsinki Univ. (Finland); Lindberg, A. [Geological Survey of Finland, Espoo (Finland)

    2000-04-01

    Batch sorption experiments of cesium were performed for rapakivi granite and its main minerals, and also for some fracture minerals. The main minerals quartz, potassium feldspar, plagioclase, biotite and hornblende were magnetically separated from crushed rapakivi granite. The fracture minerals were chlorite, dolomite and kaolinite. Sorption was studied in fresh and saline reference waters containing cesium in the range of 10{sup -8} to 10{sup -3} mol/l. The distribution ratios for rapakivi granite generally decreased with an increasing Cs concentration and an increasing ionic strength. For fresh rapakivi granite, the sorption behaviour was rather complex in both fresh and saline reference waters, being complex for the other alteration stages only in saline water. Sorption increased unexpectedly when the initial cesium concentration was raised to 10{sup -5} - 10{sup -4} mol/l. The sorption on rapakivi granite was non-linear, especially in saline water. Sorption was reversible for rapakivi granite. The sorption on the minerals proved to be very non-linear, especially on biotite. Sorption was also reversible for biotite and kaolinite. For the other minerals, sorption was irreversible to some degree. As to the sorption of cesium investigated by studying thin sections of rapakivi granite and their autoradiograms, the most dominating mineral was biotite. The water analyses made during the sorption experiment revealed the exchange of potassium and cesium. The corresponding changes were difficult to detect in saline water. Calculation of the R{sub d} values for the rock, based on the R{sub d} values of minerals and the portions of minerals in the rock, yielded smaller distribution ratios than the values determined for the rock. (orig.)

  11. Advective heat transfer and fabric development in a shallow crustal intrusive granite – the case of Proterozoic Vellaturu granite, south India

    Indian Academy of Sciences (India)

    Dilip Saha; Sukanya Chakraborti

    2007-10-01

    Syntectonic plutons emplaced in shallow crust often contain intermediate-to low-temperature deformation microstructures but lack a high-temperature, subsolidus deformation fabric,although the relict magmatic fabric is preserved. The Proterozoic Vellaturu granite emplaced at the eastern margin of the northern Nallamalai fold belt,south India during the late phase of regional deformation has a common occurrence of intermediate-to low-temperature deformation fabric, superimposed over magmatic fabric with an internally complex pattern. But high-T subsolidus deformation microstructure and fabric are absent in this pluton.The main crystal plastic deformation and fluid enhanced reaction softening was concentrated along the margin of the granite body. Resulting granite mylonites show Y-maximum c axis fabric in completely recrystallized quartz ribbons,dynamic recrystallization of perthites,and myrmekite indicative of fabric development under intermediate temperature (∼500-400° C). The weakly-deformed interior shows myrmekite,feldspar microfracturing and limited bulging recrystallization of quartz.The abundance of prism subgrain boundaries is indicative of continuing deformation through low-temperature(∼300° C).The relative rates of cooling in fluenced by advective heat transfer and deformation of the pluton seem to control the overall subsolidus fabric development.The rapid advective heat transfer from the interior in the early stages of subsolidus cooling was followed by slow cooling through intermediate temperature window as a well-developed phyllosilicate rich mylonitic skin around the granite body slowed down conductive heat loss.Low-T crystal plastic deformation of quartz was effected at a late stage of cooling and deformation of the shallow crustal granite body emplaced within the greenschist facies Nallamalai rocks.

  12. Contamination in mafic mineral-rich calc-alkaline granites: a geochemical and Sr-Nd isotope study of the Neoproterozoic Piedade Granite, SE Brazil

    Directory of Open Access Journals (Sweden)

    Leite Renato J.

    2006-01-01

    Full Text Available The Piedade Granite (~600 Ma was emplaced shortly after the main phase of granite magmatism in the Agudos Grandes batholith, Apiaí-Guaxupé Terrane, SE Brazil. Its main units are: mafic mineral-rich porphyritic granites forming the border (peraluminous muscovite-biotite granodiorite-monzogranite MBmg unit and core (metaluminous titanite-bearing biotite monzogranite BmgT unit and felsic pink inequigranular granite (Bmg unit between them. Bmg has high LaN/YbN (up to 100, Th/U (>10 and low Rb, Nb and Ta, and can be a crustal melt derived from deep-seated sources with residual garnet and biotite. The core BmgT unit derived from oxidized magmas with high Mg# (~45, Ba and Sr, fractionated REE patterns (LaN/YbN= 45, 87Sr/86Sr(t~ 0.710, epsilonNd(t ~ -12 to -14, interpreted as being high-K calc-alkaline magmas contaminated with metasedimentary rocks that had upper-crust signature (high U, Cs, Ta. The mafic-rich peraluminous granites show a more evolved isotope signature (87Sr/86Sr(t = 0.713-0.714; epsilonNd(t= -14 to -16, similar to Bmg, and Mg# and incompatible trace-element concentrations intermediate between Bmg and BmgT. A model is presented in whichMBmgis envisaged as the product of contamination between a mafic mineral-rich magma consanguineous with BmgT and pure crustal melts akin to Bmg.

  13. Regional tectonic context, timing, and intrusion mechanism of gneiss domes, eastern Papua New Guinea, from offshore seismic reflection and well data

    Science.gov (United States)

    Fitz, G. G.; Mann, P.; Lavier, L. L.

    2011-12-01

    The D'Entrecasteaux Island (DEI) gneiss domes are fault-bounded topographic domes with ~2.5 km of relief exposing ultrahigh-pressure (UHP) and high-pressure (HP) metamorphic gneisses and migmatites that began to exhume ~8 Ma in a zone of continental extension 120 km west of the tip of the westward propagating Woodlark seafloor spreading. Two previous models for the origin and emplacement of the gneiss domes include: 1) the domes are metamorphic core complexes formed as footwall blocks on north-dipping, low-angle (Trobriand basin and the Goodenough basin. MCS and well data show the Trobriand basin initially formed as an asymmetrical Miocene forearc basin overlying the south-dipping Trobriand subduction zone that underwent a late Miocene (~11-9 Ma) inversion event that deformed and uplifted the basin's southern and northern margins. Since extension began 8 Ma, the Trobriand basin has evolved as a symmetrical sag basin with 1-3 km of subsidence and few normal faults deforming the upper crust. The Goodenough basin to the south of the Trobriand basin formed as an asymmetrical and southward-tilted half-graben whose master normal fault is the Owen-Stanley fault zone (OSFZ) along the southern edge of the basin. Reconstruction on this structure based on the geometry of faults in the hanging wall indicates a minimum slip on the order of 10 km along a listric fault plane shallowly dipping to the north. The western extension of the OSFZ dips 18 deg. to 24 deg. north along the northern edge of the Dayman dome; the eastern extension of the fault along the northern edge of the Moresby seamount dips 30 deg. north. We have also identified the Trobriand fault, a 60-km-long subaerial and submarine transfer fault connecting the OSFZ and the active Woodlark spreading center in the offshore seismic data. To understand continental extension at depth surrounding the DEI, upper crust extension determined through structural reconstructions is compared to lower crust extension predicted from

  14. Paleoproterozoic migmatitic gneisses from the Tandilia belt (Argentina), Río de la Plata craton, record cooling at deep crustal levels

    Science.gov (United States)

    Martínez, Juan Cruz; Massonne, Hans-Joachim; Dristas, Jorge Anastasio; Theye, Thomas; Graff, Ailín Ayelén

    2016-04-01

    We studied high-grade metamorphic rocks of the El Cristo hill area of the Tandilia belt. Mineral analyses and thermodynamic calculations were carried out for two adjacent rock samples: an amphibole-biotite gneiss and a garnet-biotite-bearing migmatite. Peritectic garnets in the migmatite show core compositions of pyr4.5(gro + andr)10spes6alm79.5 changing to pyr3.5(gro + andr)17spes6alm73.5 at their thin rims. Garnet compositions in the gneiss are pyr6.5(gro + andr)26spes12alm55.5 and pyr4.5(gro + andr)34spes12alm49.5 for core and rim, respectively. A P-T path was constructed by calculating pseudosections in the 11-component system Si-Ti-Al-Fe-Mn-Mg-Ca-Na-K-O-H and contouring them by isopleths for garnet components using the PERPLE_X software package. Supra-solidus crystallization of garnet cores in the migmatite began at 5.8 kbar and 660 °C. Garnet rims equilibrated at 7.0 kbar and 640 °C compatible with garnet cores in the amphibole-biotite gneiss (7.6 kbar and 660 °C). The further chemical development of garnet in this rock points to P-T conditions of 11.6 kbar and 620 °C and 12.2 kbar and 595 °C (outermost garnet rim). At this high-pressure stage Ca-amphibole was not stable. Most biotite formed during exhumation whereas the high-pressure accessory minerals, titanite and epidote, persisted. According to the obtained anti-clockwise P-T path the originally partly melted material was tectonically transported from ∼22 km (middle crust) to ∼40 km (lower crust) depths reaching a geothermal gradient as low as 15 °C km-1. This transport probably occurred along a major suture zone, which was active during the Paleoproterozoic (2.25-2.10 Ga), before a terminating collision of terranes near the SW boundary of the Rio de la Plata craton.

  15. Geological and Petrological Studies on the Hiroshima Granite in the Togouchi-Yuu-Takehara District Southwest Japan

    OpenAIRE

    Hayashi, Takehiro

    1995-01-01

    The main purpose of this paper is throwing light on the mechanism of emplacement of the Hiroshima granite and on the space problem of volcano-plutonism in the Inner Zone of Southwest Japan during the late Cretaceous. In order to discuss these problems which are classical and have so far been unsolved, the author has selected the Togouchi-Yuu-Takehara district as a granite field of the San-yo zone. In the southern end of the district, the granite is in contact with Ryoke granitic and metamorph...

  16. Characteristics of the Two Types of Granits at Sikongshan in the Eastern Part of the Dabieshan Mountains

    Institute of Scientific and Technical Information of China (English)

    陈跃志; 桑宝梁; 等

    1992-01-01

    It has been shown from petrologic,geochemical,trace element and REE evidence that the gran-ite intrusions at Sikongshan,Anhui Province,can be assigned to two distinct types which are radically different in age and origin.The Precambrian gneissic granited resulted from remelting of old continental crust while the Mesozoic granites were derived ,also through remelting,from low-Rb/Sr rocks at greater depths.Granite masses at Tiantangzhai and Zhoujiawan in the Dabieshan Mountains are also dicussed.

  17. Chemical element transfer of weathering granite regolith in the Three Gorges Dam region of Yangtze River

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Clearing up sediment and regolith on the foundation of the dam in the Three Gorges of the Yangtze River in 1999, riverbed were exposed. On the basis of weathering granite regolith sampled from different portions of the valley landforms, by analysing total chemical contents with X rays fluorescent slice and calculating proper value of chemical element transferring ratio and intensity, the transferring law of chemical elements in different portions of the landforms were concluded: 1) In various landforms of the river valley, the process of desilication is not distinct; 2) in weathering granite regolith of riverbed, easy soluble CaO and MgO are relatively enriched whereas A1203 tends to decrease. The enriching rate of Fe203 is the greatest in various landforms of the river valley; 3) in weathering granite regolith of flood-plain, K20 and MgO contents are relatively enriched; 4) the weathering granite regolith of valley slope is a typical north subtropical weathering regolith, and its chemical weathering degree is in the transition phase from early to middle period; and 5) there is an opposite layer where K20 is relatively leaching and Na20 relatively enriching in 6.5 m depth of all weathering granite regolith.

  18. Sr isotope evolution during chemical weathering of granites -- impact of relative weathering rates of minerals

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The Sr isotopic systematics in the weathering profiles of biotite granite and granite porphyry in southern Jiangxi Province were investigated. The results showed that during the chemical weathering of granites, remarked fractionation occurred between Rb and Sr. During the early stages of chemical weathering of granites, the released Sr/Si and Sr/Ca ratios are larger than those of the parent rocks, and the leaching rate of Sr is higher than those of Si, Ca, K, Rb, etc. Dynamic variations in relative weathering rates of the main Sr-contributing minerals led to fluctuation with time in 87Sr/86Sr ratios of inherent and released Sr in the weathering crust of granite. Successive weathering of biotite, plagioclase and K-feldspar made 87Sr/86Sr ratios in the weathering residues show such a fluctuation trend as to decrease first, increase, and then decrease again till they maintain stable. This work further indicates that when Sr isotopes are used to trace biogeochemical processes on both the catchment and global scales, one must seriously take account of the prefer-ential release of Sr from dissolving solid phase and the fluctuation of 87Sr/86Sr ratios caused by the variations of relative weathering rates of Sr-contributing minerals.

  19. REE Comparison Between Muncung Granite Samples and their Weathering Products, Lingga Regency, Riau Islands

    Directory of Open Access Journals (Sweden)

    Ronaldo Irzon

    2016-12-01

    Full Text Available The increasing demand for Rare Earth Elements (REE is related to the continous development of technology, and these elements are used in modern equipments. REE can occur in igneous and sedimentary rocks in significant amounts as primary deposits, whereas the secondary REE deposit can be produced by intensive lateritic weathering of bedrocks under the tropical or subtropical climate. Lateritic process can increase REE concentration from sub-economic levels in host rocks to be more valuable. Muncung Granite is located in a tropical area of Lingga Regency, Riau Islands Province. REE occurs in the Muncung Granite and in weathered layers (saprolite, laterite, and soil. ICP-MS was applied to measure the REE content in all samples of this study. The average REE content of the Muncung Granite is 265 ppm with Eu anomaly in REE’s spider diagrams. Lateritization process has increased REE content by more than four times compared to that in the Muncung Granite. Ce and Eu anomalies in weathered layers can be associated with weathering process and initial REE contents in the host rock. Ce anomaly in a laterite layer is found to have a negative correlation to REE total enrichment. The REE level in the Muncung Granite is higher than the content in the soil and saprolite layers, but lower than that in the laterite.

  20. Time-Dependent Behaviors of Granite: Loading-Rate Dependence, Creep, and Relaxation

    Science.gov (United States)

    Hashiba, K.; Fukui, K.

    2016-07-01

    To assess the long-term stability of underground structures, it is important to understand the time-dependent behaviors of rocks, such as their loading-rate dependence, creep, and relaxation. However, there have been fewer studies on crystalline rocks than on tuff, mudstone, and rock salt, because the high strength of crystalline rocks makes the detection of their time-dependent behaviors much more difficult. Moreover, studies on the relaxation, temporal change of stress and strain (TCSS) conditions, and relations between various time-dependent behaviors are scarce for not only granites, but also other rocks. In this study, previous reports on the time-dependent behaviors of granites were reviewed and various laboratory tests were conducted using Toki granite. These tests included an alternating-loading-rate test, creep test, relaxation test, and TCSS test. The results showed that the degree of time dependence of Toki granite is similar to other granites, and that the TCSS resembles the stress-relaxation curve and creep-strain curve. A viscoelastic constitutive model, proposed in a previous study, was modified to investigate the relations between the time-dependent behaviors in the pre- and post-peak regions. The modified model reproduced the stress-strain curve, creep, relaxation, and the results of the TCSS test. Based on a comparison of the results of the laboratory tests and numerical simulations, close relations between the time-dependent behaviors were revealed quantitatively.

  1. Damage and Plastic Deformation Modeling of Beishan Granite Under Compressive Stress Conditions

    Science.gov (United States)

    Chen, L.; Wang, C. P.; Liu, J. F.; Liu, J.; Wang, J.; Jia, Y.; Shao, J. F.

    2015-07-01

    Based on experimental investigations, we propose a coupled elastoplastic damage model to simulate the mechanical behavior of granite under compressive stress conditions. The granite is taken from the Beishan area, a preferable region for China's high-level radioactive waste repository. Using a 3D acoustic emission monitoring system in mechanical tests, we focus on the cracking process and its influence on the macroscopic mechanical behavior of the granite samples. It is verified that the crack propagation coupled with fractional sliding along the cracks is the principal mechanism controlling the failure process and nonlinear mechanical behavior of granite under compressive stress conditions. Based on this understanding, the coupled elastoplastic damage model is formulated in the framework of the thermodynamics theory. In the model, the coupling between damage and plastic deformation is simulated by introducing the independent damage variable in the plastic yield surface. As a preliminary validation of the model, a series of numerical simulations are performed for compressive tests conducted under different confining pressures. Comparisons between the numerical and simulated results show that the proposed model can reproduce the main features of the mechanical behavior of Beishan granite, particularly the damage evolution under compressive stress conditions.

  2. Evaluation of the effectiveness of laser crust removal on granites by means of hyperspectral imaging techniques

    Energy Technology Data Exchange (ETDEWEB)

    Pozo-Antonio, J.S., E-mail: santiago.pozo@udc.es [Laboratorio de Aplicacións Industriais do Láser, Centro de Investigacións Tecnolóxicas (CIT), Departamento de Enxeñaría Industrial II, Escola Politécnica Superior, Universidade de Coruña (UDC), Campus Ferrol, 15403 Ferrol (Spain); Fiorucci, M.P.; Ramil, A.; López, A.J. [Laboratorio de Aplicacións Industriais do Láser, Centro de Investigacións Tecnolóxicas (CIT), Departamento de Enxeñaría Industrial II, Escola Politécnica Superior, Universidade de Coruña (UDC), Campus Ferrol, 15403 Ferrol (Spain); Rivas, T. [Departamento de Enxeñaría dos Recursos Naturais e Medioambiente, Escola Superior de Minas, Universidade de Vigo, 36310 Vigo (Spain)

    2015-08-30

    Highlights: • Hyperspectral imaging techniques for determining the degree of crust removal on granites used in Cultural Heritage. • Hyperspectral imaging techniques allow to in situ evaluate of the effectiveness of the laser cleaning. • Hyperspectral imaging data are consistent with the information obtained by conventional techniques about the cleaning effectiveness. - Abstract: In this paper, we present a study of the application of the hyperspectral imaging technique in order to non-destructively evaluate the laser cleaning of the biogenic patina and the sulphated black crust developed on a fine-grained granite used in the construction of Cultural Heritage in NW Spain. The grained polymineral texture of the granite hinders the adjustment of laser irradiation parameters during the cleaning, and therefore the in situ process control. The cleaning was performed with a nanosecond pulsed Nd:YVO{sub 4} laser at 355 nm. A hyperspectral camera was used to in situ assess the effectiveness of cleaning by recording images of the rock surfaces before and during the laser treatment. Different analytical techniques were used to test the ability of the hyperspectral imaging technique to evaluate the cleaning process of the granite samples: optical microscopy, scanning electron microscopy with energy dispersive X-ray spectrometry (SEM - EDX), Fourier transform infrared spectroscopy (FTIR) and spectrophotometer colour measurements. The results indicated that hyperspectral imaging technique is a reliable and more affordable technique to in situ evaluate the process of laser cleaning of the biogenic patina and the sulphated black crust in fine-grained granites.

  3. Three Paleoproterozoic A-type granite intrusions and associated dykes from Kainuu, East Finland

    Directory of Open Access Journals (Sweden)

    Hannu Huhma

    2010-12-01

    Full Text Available Mafic and felsic intrusive rocks aged 2.5–2.4 Ga have been observed over a large area in eastern and northern Finland, as well as in adjacent northwestern Russia. We describe three granite intrusions and associated dykes from Kainuu, Finland, that belong to this bimodal magmatic event. All these three granites show clear A2-type chemical affinities with high Y/Nb, HREE, Fe/Mg, Ga and Nb. Two of the intrusions, Rasinkylä and Pussisvaara, were dated at 2425±3 and 2427±3 Ma, respectively, using thermal ionisation mass spectrometry utilizing the chemical abrasion method (CA-TIMS. CA-TIMS ages are supported by single-grain age determinations obtained by using Laser Ablation Multicollector Inductively Coupled Plasma Mass Spectrometer (LA-MC-ICPMS. New data on the previously described Rasimäki granite from southern Kainuu is presented, including an age of 2389±5 Ma obtained with LA-MC-ICPMS. The variable magnetite content of the granites is proposed to reflect the differences in the oxidation state of the source, which in our interpretation is the local Archean lower crust. Partial melting and the emplacement of the granites occurred in an extensional environment. Heat for the partial melting was provided by mafic magmas under and intraplating the extended crust.

  4. New dating of Dajishan granite and related tungsten mineralization, South Jiangxi Province, China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wenlan; HUA Renmin; WANG Rucheng; CHEN Peirong; LI Huimin

    2007-01-01

    The Dajishan deposit is a well-known tungsten and niobium-tantalum deposit in China. Due to the technolo- gical restrictions, little work has been done on the ages of ore-forming and related granite in Dajishan for a long time. By means of the single-zircon U-Pb isotopic method, the intrusion age is reported in this paper, which is (151.7±1.6) Ma for a patched granite body (the source granite for Nb-Ta). By quick neutron mobilization method, an 40Ar-39Ar age of mica from the major ore vein is determined, yielding ore-forming ages of 144 Ma and 147 Ma. Combining these age data with the occurrences of the main granite body, the patched body, the major ore veins and Na-Ta mineralization, the paper dis- cusses their formation orders and relationships. These data also show that the Dajishan granite and its related mineraliza- tions are the product of magmatism in the middle Yanshanian stage and a part of the secondary large-scale mineralization in the Mesozoic.

  5. Emplacement age and tectonic implications of the Xilinhot A-type granite in Inner Mongolia, China

    Institute of Scientific and Technical Information of China (English)

    SHI Guanghai; MIAO Laicheng; ZHANG Fuqing; JIAN Ping; FAN Weiming; LIU Dunyi

    2004-01-01

    A new rock type of granite, approximate 45 km2 in area and located about 10 km south of Xilinhot, Inner Mongolia, was found in the Sunitezuoqi (or called Suzuoqi)-Xilinhot tectonic belt and identified as an A-type mia- rolitic intrusion. The pluton has miarolitic structure and is composed chiefly of perthite, quartz, euhedral albite and potassium feldspar. Various types of textures occur in the pluton, such as perthitie, graphic and myrmekite textures. Only quartz is found in miarolitic cavity. This A-type granite with seagull-shaped REE patterns and obvious negative Eu anomaly (δEu = 0.24-0.28) is high in SiO2 (76%-77%), K and Na (Na2O + K2O = 7.75%-8.15%) and low in Ca (CaO = 0.20%-0.22%), Fe and Mg. Both petrographical observations and chemical compositions indicate that it is an A-type granite. Zircon SHRIMP U-Pb analyses indicate that this A-type granite was emplaced at 276 ( 2 Ma and coeval with the same type of granites in the adjacent areas. Therefore, it suggests that this pluton was likely formed in a post-orogenic extensional setting and probably related to break-off of subducted slabs in Central Asian Orogenic Belt (CAOB), which indicate that the Sunitezuoqi-Xilinhot belt was tectonically evolved into post-orogenic stage since early Permian.

  6. Instrumented borehole drilling for interface identification in intricate weathered granite ground engineering

    Institute of Scientific and Technical Information of China (English)

    Zhuoying Tan; Meifeng Cai; Z.Q. Yue; L.G.Tham; C.F.Lee

    2007-01-01

    The successful application in drilling for HK simple weathered granite foundation has revealed its further use in instrumented drilling system as a ground investigation tool in the detection of other lithology formations, geohazards, underground water, and boundary of orebody. To expand the further use and test the accuracy in identification of formation, an R-20 rotary-hydraulic drill rig was instrumented with a digital drilling process monitoring system (DPM) for drilling in an intricate decomposed granite site.In this test ground, the boreholes revealed that the weathered granite alternately changes between moderate and strong. The qualitative and quantitative analysis of the penetrating parameters, indicates the effective thrust force, rotary speed, flushing pressure, penetrating rate, and displacement of the bit fluctuate at ground interfaces. It shows that the parameters get a good response with the change of rock strength at the interfaces, which can reveal the change of the intricate granite formation. Besides, a variable-slope method has been established, for identification of dominative and subsidiary interfaces in the granite site. The result from a t-test shows that the confidence of the instrumented drilling system in identification of the geotechnical interfaces is up to 99%.

  7. Determination of Tensile Strength and Fracture Toughness of Granite Using Notched Three-Point-Bend Samples

    Science.gov (United States)

    Wang, Yusuo; Hu, Xiaozhi

    2017-01-01

    Direct tensile strength and fracture toughness of rock and concrete, important properties for many applications, are cumbersome to measure directly. In this study, granite is chosen as an example to show how the tensile strength and fracture toughness can be measured from small three-point-bend samples of a single size but with different notches. An existing fracture mechanics model has been extended to include the stable fictitious crack growth before peak loads, which is then linked to the granite grain size. Both tensile strength and fracture toughness of granite can be estimated by the maximum load measurements from those notched three-point-bend samples. In total, 72 three-point-bend granite samples with different notches have been tested, and the estimated tensile strength and fracture toughness are compared with those available in the literature. The modified fracture mechanics model is then used to predict the fracture behaviour of smaller samples of the same granite. The theoretical prediction is confirmed by the experimental results of those smaller samples. Finally, the fracture model and its relation with the American Society for Testing and Materials (ASTM) standard on fracture toughness are discussed.

  8. Formation Age of the Marble in the Khondalite Series in Jining, Inner Mongolia: Evidence of the LA-ICP-MS Zircon U-Pb Dating of Felsic Gneiss%内蒙集宁地区孔兹岩系中大理岩的形成时代——长英质片麻岩中LA-ICP-MS锆石U-Pb测年的证据

    Institute of Scientific and Technical Information of China (English)

    徐仲元; 范志伟; 刘正宏; 李世超; 王挽琼; 张超; 马越; 王英男

    2013-01-01

    Our research area is located in Jining,the eastern section of the Khondalite belt in the western block of the North China craton,where the khondalite series is composed of garnet-biotite gneiss in the lower part and marble in the upper part.Several layers of felsic gneiss interbedded with thin marble layers are found,and the parental rock of the felsic gneiss is defined as feldsparthic sandstone by petrographical study,zircon characteristics and restoring the protolithic types.After LA-ICP-MS zircon U-Pb dating of the felsic gneiss,72 zircon data are obtained from 70 zircon grains,among which the youngest detrital zircon data is (2 091±20) Ma that can represent the lower limit of felsic gneiss formation age; And the weighted average 207Pb/206 Pb apparent age of the 19 metamorphic zircon concentrated between 1.8-1.9 Ga is (1 852±15) Ma(MSWD=0.7),can represent the upper limit of deposition age of the original rock of the felsic gneiss.Based on the previous research results,we could conclude that in Jining area,marbles in the khondalite series were formed in the Paleoproterozoic Era between (1 852±15) Ma and (2 091±20) Ma,and underwent the regional metamorphism in (1 852±15) Ma.This suggests that marbles are the import.ant component of the khondalite series; In the Khondalite belt across the western block of the North China craton,a large scale of granitic intrusion had existed in the source region of protolith of the khondalite series.However,there are different material Source regions in every part of the belt; the protoliths of the khondalite series is not the in-situ deposition of fragmentary materials provided by the nearby Archean rocks,but alien tectonic rock sheet mingled with the nearby Archean rocks by Late Paleoproterozoic tectonic processes.%研究区位于华北克拉通西部孔兹岩带东段的集宁一带,区内的孔兹岩系由下部的榴云片麻岩组合和上部的大理岩组合组成.在大理岩组合的底部发现了数层与薄层大

  9. Kyanite-garnet gneisses of the Kåfjord Nappe - North Norwegian Caledonides: P-T conditions and monazite Th-U-Pb dating

    Science.gov (United States)

    Ziemniak, Grzegorz; Kośmińska, Karolina; Majka, Jarosław; Janák, Marian; Manecki, Maciej

    2016-04-01

    The Kåfjord Nappe is the part of the Skibotn Nappe Complex traditionally ascribed to the Upper Allochthon of the North Norwegian Caledonides. Pressure-temperature (P-T) conditions and metamorphic age of the Kåfjord Nappe are not well constrained, geochronological data are limited to a single Rb-Sr age of c. 440 Ma (Dangla et al. 1978). Metamorphic evolution of kyanite-garnet gneisses of the Kåfjord Nappe is presented here. The kyanite-garnet gneisses are associated with a few meters thick amphibolite lenses. The gneisses mainly consist of quartz, plagioclase, biotite, muscovite, garnet, kyanite, and rutile. Retrograde minerals are represented by sillimanite and chlorite. Garnet occurs as two textural types. Garnet-I forms euhedral porphyroblasts with multiple small inclusions. Profiles through garnet-I show chemical zonation in all components. The composition varies from Alm64-68Prp11-16Grs13-18Sps2-8 in the core to Alm68-70Prp17-18Grs10-13Sps1-3 in the rim. Garnet-II is subhedral to anhedral, its core is inclusion-rich, whereas rim contains only single inclusions. Chemical composition of garnet-II is similar to that of the garnet-I rim. P-T conditions have been estimated using the garnet-biotite-muscovite-plagioclase (GBPM) geothermobarometer (Holdaway, 2001; Wu, 2014). Calculated peak P-T metamorphic conditions are 610-625 °C and 7.6-8.2 kbar corresponding to the amphibolite facies conditions. Phase equilibrium modelling in the NCKFMMnASH system yields peak metamorphic conditions of c. 620 °C at 8 kbar. Growth conditions of garnet-I core modelled in the NCKFMMnASH system are c. 570 °C at 9.7 kbar. Chemical Th-U-total Pb monazite dating has been performed. Preliminary dating results from the kyanite-garnet gneiss of the Kåfjord Nappe yield an array of dates from 468 Ma to 404 Ma. There is a correlation between an increase of yttrium content and decrease of monazite single dates. Compositional maps confirm an increase of yttrium towards the rim of the

  10. The UHP metamorphic Seve Nappe Complex of the Swedish Caledonides - a new occurrence of the microdiamond-bearing gneisses and their exhumation

    Science.gov (United States)

    Klonowska, Iwona; Janák, Marian; Majka, Jarosław; ‎ Froitzheim, Nikolaus; Gee, David G.

    2015-04-01

    The ultra-high pressure metamorphism (UHPM) in the Seve Nappe Complex of the Swedish Caledonides has been recently recognized within several lithologies including gneisses, eclogites and garnet pyroxenites (e.g. Janák et al. 2013, Klonowska et al. 2014a, Majka et al. 2014). Thermodynamic modelling and thermobarometric calculations indicate peak pressure conditions of >3GPa at c. 800-900°C (reaching the diamond stability field) for eclogites and garnet pyroxenites from northern Jämtland (e.g. Klonowska et al. 2014b). In addition to this, the first microdiamonds were found in paragneisses from the Snasahögarna Mt. in central Jämtland (Majka et al. 2014). Here we report a new discovery of microdiamond together with moissanite (SiC) from one of the world's most famous localities for thrusting, Mount Åreskutan, where long transport distances were recognized already in the 19th century (Törnebohm 1888). Garnet porphyroblasts in gneisses from the Åreskutan Mt. contain abundant mineral inclusions, mainly graphite, carbonates and quartz, together with fluid inclusions of CO2 concentrated in swarms. Among these inclusions three microdiamonds were found in two gneiss samples. In one of the samples moissanite was also discovered. Both minerals were identified by micro-Raman spectroscopy. In addition to these 'swarm' inclusions, biotite, kyanite, rutile, feldspars, zircon, monazite, ±phengite, ±muscovite, ±spinel, ±ilmenite, ±apatite occur in garnets. Phase equilibrium modelling for the phengite-bearing gneiss confirms its UHP history at temperatures of c. 800°C. Recent discoveries of UHP metamorphism within the Seve Nappe Complex derived from the Baltican outer margin (part of the Middle Allochthon) challenged us to present a new tectonic model incorporating exhumation of the deeply subducted continental rocks together with mantle lithosphere peridotites. Majka et al. (2014) introduced a new "under-pressure"-driven exhumation mechanism of rocks buried in

  11. Strontium and neodymium isotopic variations in early Archean gneisses affected by middle to late Archean high-grade metamorphic processes: West Greenland and Labrador

    Science.gov (United States)

    Collerson, K. D.; Mcculloch, M. T.; Bridgwater, D.; Mcgregor, V. R.; Nutman, A. P.

    1986-01-01

    Relicts of continental crust formed more than 3400 Ma ago are preserved fortuitously in most cratons. The cratons provide the most direct information about crust and mantle evolutionary processes during the first billion years of Earth history. In view of their polymetamorphic character, these terrains are commonly affected by subsequent tectonothermal events. Hence, their isotope systematics may be severely disturbed as a result of bulk chemical change or local isotopic homogenization. This leads to equivocal age and source information for different components within these terrains. The Sr and Nd isotopic data are presented for early Archean gneisses from the North Atlantic Craton in west Greenland and northern Labrador which were affected by younger metamorphic events.

  12. Durability of fired clay bricks containing granite powder

    Directory of Open Access Journals (Sweden)

    Xavier, G. C.

    2012-06-01

    Full Text Available Over the past few decades, hundreds of papers have been published on the benefits of including rock powder as a raw material in fired clay brick manufacture. Very little has been written, however, about the durability and long-term behaviour of the final product. As a rule, the ceramic bricks used in construction in developing countries are fired at low temperatures, which detracts from their mechanical performance. This is particularly visible in harsh environmental conditions, where weathering causes severe deterioration. The present paper describes the impact of weathering on clay bricks containing from 0 to 10% granite powder, an industrial by-product. The specimens were fired at 500, 700 or 900 ºC and subsequently exposed to natural environmental conditions or accelerated laboratory weathering. Their physical and mechanical properties were evaluated to determine the effect of the composition of raw materials on fired clay product durability.

    En las últimas décadas se han publicado cientos de artículos sobre las ventajas de incluir polvo de roca como materia prima en la fabricación de los ladrillos cerámicos. Sin embargo, la durabilidad y el comportamiento a largo plazo del producto final han sido objeto de pocas investigaciones. Por lo general, los ladrillos cerámicos empleados en la construcción en los países en vías de desarrollo se cuecen a temperaturas bajas, lo que impide el desarrollo de sus propiedades mecánicas. Esto queda especialmente patente cuando las condiciones ambientales son severas, en cuyo caso la meteorización puede provocar un deterioro importante. En este artículo se describe el efecto de la meteorización en ladrillos cerámicos que incorporaban entre un 0 y un 10% de polvo de granito, que es un derivado industrial. Las probetas se cocieron a 500, 700 o 900 °C y luego se sometieron a condiciones ambientales naturales o a un proceso de laboratorio de meteorización acelerada. Se evaluaron sus

  13. Post-Orogenic Granites in Pingwu Region, Northwest Sichuan: Evidence for North China Block and Yangtze Block Collision during Triassic

    Institute of Scientific and Technical Information of China (English)

    Pei Xianzhi; Li Zuochen; Ding Saping; Feng Jianyun; Li Ruibao; Sun Yu; Zhang Yafeng; Liu Zhanqing

    2009-01-01

    The Nanyili (南一里), Laohegou (老河沟), and Shaiziyan (筛子岩) granitic intrusions are located in the southern margin of the Bikou (碧口) block in Pingwu (平武) area, Northwest Sichuan (四川). The petrography and geochemical characteristics of the granitic intrusions as well as their source and tectonic settings are reported and discussed in this article. The Laohegou and Shaiziyan granites are with high SiO2 (69.89 wt.%-73.05 wt.%) and Al2O3 contents, and A/CNK=1.04-1.12. They are typi-cal strongly peraluminous granites, with supersaturation in Al and Si. The abundance of ∑REE varies in the range of (33.13-89.12)×106. The rocks show an LREE enrichment pattern and obvious Eu nega-tive anomaly. The trace element geochemistry is characterized evidently by a negative anomaly of Ta, Nb, Ti, etc. and a positive anomaly of Rb, Ba, Sr, etc.. Zircons of the Nanyili granite have higher Th/U ratios, and their CL images have internal oscillatory zoning, suggesting that the zircons of the samples are igneous in origin. The LA ICP-MS zircon U-Pb isotopic concordia diagram yields an age of 223.1±2.6 Ma (MSWD=1.4), which indicates that the granodiorite intrusions formed in the early Late Triassic. The Nanyili, Laohegou, and Shaiziyan granites have the characteristics of post-eollisional granites and are regarded as post-orogenic granites. Thus, the granite intrusions are interpreted as syn-collisional granites that resulted from the crustal thickening caused by the collisions between the North China plate and the Yangtze plate during the Indosinian. The granitic intrusions formed in a transitional environment from syn- (compres-slonal environment) to post-collision (extensionalenvironment).

  14. Metasomatism of ferroan granites in the northern Aravalli orogen, NW India: geochemical and isotopic constraints, and its metallogenic significance

    Science.gov (United States)

    Kaur, Parampreet; Chaudhri, Naveen; Hofmann, Albrecht W.; Raczek, Ingrid; Okrusch, Martin; Skora, Susanne; Koepke, Jürgen

    2014-06-01

    The late Palaeoproterozoic (1.72-1.70 Ga) ferroan granites of the Khetri complex, northern Aravalli orogen, NW India, were extensively metasomatised ~900 Ma after their emplacement, at around 850-830 Ma by low-temperature (ca. 400 °C) meteoric fluids that attained metamorphic character after exchanging oxygen with the surrounding metamorphic rocks. Albitisation is the dominant metasomatic process that was accompanied by Mg and Ca metasomatism. A two-stage metasomatic model is applicable to all the altered ferroan intrusives. The stage I is represented by a metasomatic reaction interface that developed as a result of transformation of the original microcline-oligoclase (An12-14) granite to microcline-albite (An1-3) granite, and this stage is rarely preserved. In contrast, the stage II metasomatic reaction front, where the microcline-bearing albite granite has been transformed to microcline-free albite granite, is readily recognisable in the field and present in most of the intrusives. Some of them lack an obvious reaction interface due to the presence of stage II albite granites only. When studied in isolation, these intrusives were incorrectly classified and their tectonic setting was misinterpreted. Furthermore, our results show that the mafic mineralogy of metasomatised granites has a significant impact on the characterisation of such rocks in the magmatic classification and discrimination diagrams. Nevertheless, the stage I metasomatised granites can be appropriately characterised in these diagrams, whereas the characterisation of the stage II granites will lead to erroneous interpretations. The close spatial association of these high heat producing ferroan granites with iron oxide-copper-gold (IOCG), U and REE mineralisation in the region indicates a genetic link between the metasomatism and the mineralisation. World-class IOCG, U and REE deposits are associated with metasomatised ferroan granites, suggesting that such a relationship may act as a critical

  15. Extra-terrestrial igneous granites and related rocks: A review of their occurrence and petrogenesis

    Science.gov (United States)

    Bonin, Bernard

    2012-11-01

    The telluric planets and the asteroid belt display the same internal structure with a metallic inner core and a silicate outer shell. Experimental data and petrological evidence in silicate systems show that granite can be produced by extreme igneous differentiation through various types of igneous processes. On Moon, 4.4-3.9 Ga granite clasts display dry mineral assemblages. They correspond to at least 8 discrete intrusive events. Large K/Ca enrichment and low REE abundances in granite relative to KREEP are consistent with silicate liquid immiscibility, a process observed in melt inclusions within olivine of lunar basalts and in lunar meteorites. Steep-sided domes identified by remote sensing can represent intrusive or extrusive felsic formations. On Mars, black-and-white rhythmic layers observed on the Tharsis rise along the flanks of the peripheral scarps of the Tharsis Montes giant volcanoes suggest the possible eruption of felsic pyroclastites. Though no true granites were found so far in the Martian SNC meteorites, felsic glasses and mesostases were identified and a component close to terrestrial continental (granitic) crust is inferred from trace element and isotope systematics. Venus has suffered extensive volcanic resurfacing, whereas folded and faulted areas resemble terrestrial continents. Near large shield volcanoes, with dominant basaltic compositions, steep-sided domes have been interpreted as non-degassed silicic extrusions. The hypothesis of a granitic component is "tantalising". Extra-terrestrial granite is frequently found as clasts and mesostases in asteroidal meteorites. Porphyritic textures, with alkali feldspar crystals up to several centimetres in size, were observed in silicate enclaves within iron meteorites. In the chondrite clan, polymict breccias can contain granitic clasts, whose provenance is debated. One clast from the Adzhi-Bogdo meteorite yields a 4.53 ± 0.03 Ga Pb-Pb age, making it the oldest known granite in the solar system. The

  16. Scaling Properties of Feldspar and Quartz in Micro-images of Ideal Granites

    Institute of Scientific and Technical Information of China (English)

    Xu Deyi; Ke Xianzhong; Xie Shuyun; Cheng Qiuming

    2008-01-01

    The properties of feldspar and quartze are studied in this article from a fractal point of view using gray-scale micro-images of granite samples collected at the Fangshan (房山) granite body in Hebei (河北) Province, China, which can be regarded as an ideal granite in the sense of Vistelius. We found that there exist power-law relationships between the eigenvalues of the gray-scale matrices and their ranks for the feldspar and quartz. The fractal model used here is a λ-R model similar to the N-λ model proposed by Qiuming Cheng in 2005. Meanwhile, we found that average variances for the gray-scale matrices of feldspar are larger than those of quartz on the same sections, and this may be useful for auto-identification of feldspar and quartz as well as other minerals.

  17. Comparative study of ornamental granite cleaning using femtosecond and nanosecond pulsed lasers

    Energy Technology Data Exchange (ETDEWEB)

    Rivas, T., E-mail: trivas@uvigo.es [Dpto. Ingeniería de los Recursos Naturales y Medioambiente. E.T.S. Ingeniería de Minas, Universidad de Vigo, 36200 Vigo Spain (Spain); Lopez, A.J.; Ramil, A. [Centro de Investigaciones Tecnológicas. Campus de Esteiro. Universidad de A Coruña 15403 Ferrol Spain (Spain); Pozo, S. [Dpto. Ingeniería de los Recursos Naturales y Medioambiente. E.T.S. Ingeniería de Minas, Universidad de Vigo, 36200 Vigo Spain (Spain); Fiorucci, M.P. [Centro de Investigaciones Tecnológicas. Campus de Esteiro. Universidad de A Coruña 15403 Ferrol Spain (Spain); Silanes, M.E. López de [Dpto. Ingeniería de los Recursos Naturales y Medioambiente. E.I. Forestales. Universidad de Vigo, Campus Pontevedra. 36005 Pontevedra Spain (Spain); García, A.; Aldana, J. R. Vazquez de; Romero, C.; Moreno, P. [Grupo de Investigación en Microprocesado de Materiales con Laser. Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca Spain (Spain)

    2013-08-01

    Granite has been widely used as a structural and ornamental element in public works and buildings. In damp climates it is almost permanently humid and its exterior surfaces are consequently biologically colonized and blackened We describe a comparative analysis of the performance of two different laser sources in removing biological crusts from granite surfaces: nanosecond Nd:YVO{sub 4} laser (355 nm) and femtosecond Ti:Sapphire laser at its fundamental wavelength (790 nm) and second harmonic (395 nm). The granite surface was analyzed using scanning electron microscopy, attenuated total reflection – Fourier transform infrared spectroscopy and profilometry, in order to assess the degree of cleaning and to characterize possible morphological and chemical changes caused by the laser sources.

  18. Petrogenesis and Dating of Two Types of Granite from North Qilian, China

    Institute of Scientific and Technical Information of China (English)

    WU Cailai; SHI Rendeng; YANG Jingsui; YANG Hongyi; Joseph L. WOODEN; ZHENG Qiuguang; CHENG Shengyong

    2005-01-01

    Two types of granitic intrusives occur in the lower Paleozoic strata in north Qilian. One is the hornblendebearing granitic body in Jingzichuan, characterized by the REE total of 90× 10-6-106× 10-6, LREE/HREE ratio of less than 8 (ranging from 6.9 to 7.8) and zircon SHRIMP age of 464 Ma. These intrusives have island-arc affinity. The other is biotite-bearing granitic body in Huangyanghe with the REE total of 214× 10-6-250× 10-6, LREE/HREE ratio of more than 8 (ranging from 8.2 to 9.7) and zircon LA-ICP-MS age of 383 Ma. They were tectonically intruded in a post-collisional or within-plate environment.

  19. Seismogenic faulting in the Meruoca granite, NE Brazil, consistent with a local weak fracture zone

    Directory of Open Access Journals (Sweden)

    ANA CATARINA A. MOURA

    2014-12-01

    Full Text Available A sequence of earthquakes occurred in 2008 in the Meruoca granitic pluton, located in the northwestern part of the Borborema Province, NE Brazil. A seismological study defined the seismic activity occurring along the seismically-defined Riacho Fundo fault, a 081° striking, 8 km deep structure. The objective of this study was to analyze the correlation between this seismic activity and geological structures in the Meruoca granite. We carried out geological mapping in the epicentral area, analyzed the mineralogy of fault rocks, and compared the seismically-defined Riacho Fundo fault with geological data. We concluded that the seismically-defined fault coincides with ∼E–W-striking faults observed at outcrop scale and a swarm of Mesozoic basalt dikes. We propose that seismicity reactivated brittle structures in the Meruoca granite. Our study highlights the importance of geological mapping and mineralogical analysis in order to establish the relationships between geological structures and seismicity at a given area.

  20. Seismogenic faulting in the Meruoca granite, NE Brazil, consistent with a local weak fracture zone.

    Science.gov (United States)

    Moura, Ana Catarina A; De Oliveira, Paulo H S; Ferreira, Joaquim M; Bezerra, Francisco H R; Fuck, Reinhardt A; Do Nascimento, Aderson F

    2014-12-01

    A sequence of earthquakes occurred in 2008 in the Meruoca granitic pluton, located in the northwestern part of the Borborema Province, NE Brazil. A seismological study defined the seismic activity occurring along the seismically-defined Riacho Fundo fault, a 081° striking, 8 km deep structure. The objective of this study was to analyze the correlation between this seismic activity and geological structures in the Meruoca granite. We carried out geological mapping in the epicentral area, analyzed the mineralogy of fault rocks, and compared the seismically-defined Riacho Fundo fault with geological data. We concluded that the seismically-defined fault coincides with ∼E-W-striking faults observed at outcrop scale and a swarm of Mesozoic basalt dikes. We propose that seismicity reactivated brittle structures in the Meruoca granite. Our study highlights the importance of geological mapping and mineralogical analysis in order to establish the relationships between geological structures and seismicity at a given area.

  1. Uranium mineralization in the muscovite-rich granites of the Shalatin region, Southeastern Desert, Egypt

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The younger granitoids of the Shalatin district in the Southeastern Desert of Egypt, are of biotite and two-mica granite compositions. The geochemistry of rare-earth elements ( REE), yttrium, thorium and uranium forms the basis for many important methods to reconstruct igneous petrogenesis. Since the recognition that REE, Y, Th, U-rich accessories may play an important role in controlling the geochemistry of crustal melts, a considerable amount of work has been done in an attempt to understand their effects. However, this effort has been almost exclusively focused on three minerals: zircon, monazite and apatite. Nevertheless, the variety of REE-Th-U-rich accessories in granite rocks are neither limited to these three minerals nor are they always the main REE, Y, Th carriers. The geochemistry of REE, Y, Th and U reflects the behavior of accessories and some key major minerals such as garnet and feldspars, and may therefore give valuable information about the conditions of partial melting, melt segregation and crystallization of granite magmas in different crustal regimes. The geochemistry of U and Th during magmatic differentiation has been studied in many granites from different areas and it has been known that the U and Th contents of granitic rocks generally increase during differentiation, although in some cases they decrease. The Th/U ratio can either increase or decrease, depending on redox conditions, the volatile content or alteration by endogene or supergene solutions. The accessory assemblage of muscovite-rich granites and high-grade rocks is composed of monazite, xenotime, apatite, Th-orthosilicate, secondary U-mineralization and betafite-pyrochlore. REE, Y, Th and U are not suitable for geochemical modeling of granitoids by means of equilibrium-based trace element fractionation equations, but are still useful petrogenetic tools.

  2. Conventional U-Pb dating versus SHRIMP of the Santa Barbara Granite Massif, Rondonia, Brazil

    Science.gov (United States)

    Sparrenberger, I.; Bettencourt, Jorge S.; Tosdal, R.M.; Wooden, J.L.

    2002-01-01

    The Santa Ba??rbara Granite Massif is part of the Younger Granites of Rondo??nia (998 - 974 Ma) and is included in the Rondo??nia Tin Province (SW Amazonian Craton). It comprises three highly fractionated metaluminous to peraluminous within-plate A-type granite units emplaced in older medium-grade metamorphic rocks. Sn-mineralization is closely associated with the late-stage unit. U-Pb monazite conventional dating of the early-stage Serra do Cicero facies and late-stage Serra Azul facies yielded ages of 993 ?? 5 Ma and 989 ?? 13 Ma, respectively. Conventional multigrain U-Pb isotope analyses of zircon demonstrate isotopic disturbance (discordance) and the preservation of inherited older zircons of several different ages and thus yield little about the ages of Sn-granite magmatism. SHRIMP U-Pb ages for the Santa Ba??rbara facies association yielded a 207Pb/206Pb weighted-mean age of 978 ?? 13 Ma. The textural complexity of the zircon crystals of the Santa Ba??rbara facies association, the variable concentrations of U, Th and Pb, as well as the mixed inheritance of zircon populations are major obstacles to using conventional multigrain U-Pb isotopic analyses. Sm-Nd model ages and ??Nd (T) values reveal anomalous isotopic data, attesting to the complex isotopic behaviour within these highly fractionated granites. Thus, SHRIMP U-Pb zircon and conventional U-Pb monazite dating methods are the most appropriate to constrain the crystallization age of the Sn-bearing granite systems in the Rondo??nia Tin Province.

  3. "Gris Quintana": a Spanish granite from the Past into the Future.

    Science.gov (United States)

    José Tejado, Juan; Mota, M. Isabel; Pereira, Dolores

    2014-05-01

    "Gris Quintana" is a medium-grained, biotite and amphibole granodiorite extracted in the Pluton of Quintana de la Serena (Extremadura, Spain). It is a constant light grey granite from the Hercynian geologic with excellent physicomechanical and physicochemical properties. The granodiorite is composed of plagioclase, biotite, quartz and alkali feldspar, with accessory allanite, titanite, apatite, zircon and ilmenite, mostly as inclusions within the biotite crystals. This commercial variety is extracted from many quarries in the late Hercynian plutons located in the Iberian Massif in Spain period (transition between Central Iberian and Ossa-Moren Zones), having large reserves of granite. Many of the quarries have their own transformation factory (high production zone), with which the sector is offered an endless variety of finishes and constructive rock typologies. A wide range of solutions to architects and designers are offered. Gris Quintana granite is one of the materials with highest technological benefits that are used in arquitecture. "Gris Quintana" granite has been used since ancient times, not only at a regional, but also at national and international level: paving, building (structural, exterior façadas, interior uses), urban decoration and funeral art. It can be found in monuments and more recently, in buildings of different styles and uses, that stand out in beauty and splendor, lasting in time. Some singular works in "Gris Quintana" granite all over the world: extension to the "Congreso de Diputados" (Parliament) in Madrid, "Puerta de San Vicente" in Madrid, Andalucia Parliament columns in Sevilla, New Senate Buiding in Madird, "Gran Vía" pavement in Madrid, "Teatro Real façade" in Madrid… "Gris Quintana" granite accomplishes all the requirements for its nomination as Global Heritage Stone Resource, for both its use in construction and for artistic purposes.

  4. El Stock álcali-feldespático El Pilón (Sierra Brava, La Rioja: un ejemplo de magmatismo granítico turmalinífero The El Pilón alkali-feldespar stock (Sierra Brava, La Rioja: an example of tourmaline granite magmatism

    Directory of Open Access Journals (Sweden)

    Juan A. Dahlquist

    2010-11-01

    Full Text Available La turmalina es un mineral accesorio abundante en el stock El Pilón, emplazado discordantemente en el basamento metamórfico de Sierra Brava, formado por esquistos, gneises y migmatitas. También es un accesorio frecuente en las rocas metamórficas, concentrado en los planos de foliación. El stock El Pilón es un granito álcali-feldespático cuya asociación mineral es Mc - Pl (An Tourmaline is an abundant accessory mineral in the El Pilón stock, a body discordantly emplaced in schist, gneiss, and migmatites of the Sierra Brava basement. It is also a common accessory mineral in the metamorphic rocks, lying in foliation planes. The El Pilón stock is alkali-feldspar granite and the magmatic assemblage is Mc - Pl (An < 1 % molar - Qtz with Bt - Ms - Tur + Opq + Zrn + Ap as primary accessory minerals, and secondary muscovite after biotite and plagioclase. Petrography and mineral chemistry indicate that the tourmaline (schorl and some muscovite crystallized from the parental magma of the stock. The chemical composition is typical of peraluminous granitic rocks (ASI = 1.23-1.29 with magmatic tourmaline, showing some chemical characteristic similar to A-type granite (high Ga/Al, low CaO/Al2O3, etc.. Low concentrations of LIL elements (average in ppm such as Ba (89, Sr (32 and the high concentrations of Rb (464 and Cs (106 suggest separation from orthoclase-rich feldspar in the source during partial melting of muscovite-rich metapelites, where the referred feldspar are generated by break-down of muscovite, with the production of a small amount of melt. Ba, Sr and Eu (Eu/Eu* = 0.33-0.42 were retained in the source, while Cs and Rb were transferred to the melt. The studied granitic rocks could also represent a highly differentiated facies of a parental peraluminous magma.

  5. 华北克拉通~2.5Ga地壳再造事件:来自中条山TTG质片麻岩的证据%Crustal reworking in the North China Craton at ~ 2.5Ga: Evidence from zircon UPb ages, Hf isotopes and whole-rock geochemistry of the TTG gneisses in the Zhongtiao Mountain

    Institute of Scientific and Technical Information of China (English)

    张瑞英; 张成立; 孙勇

    2013-01-01

    ).LA-ICP-MS zircon U-Pb age data indicate that the rocks formed within the range of 2553 ~2561Ma,so their formation age is restricted at Late Archaean.In-situ zircon Lu-Hf isotopic analyses show that they have positive εHf(t) values and the corresponding two-stage model age are mainly between 2.7Ga and 2.8Ga.According to geochemical characteristics of TTG gneisses in Sushui Complex,we can conjecture that their magmatic origin was mainly related to the partial melting of 2.7 ~ 2.8Ga basaltic lower crust at the end of Neoarchaean,and contaminated by a few mantle sourced materials.With the fact of the widely distributed granitic rocks in the NCC,we hold that there was no proof of large-scale subduction process in the central NCC and the North China Craton should have been formed in Late Archaean.Based on the zircon Lu-Hf isotopic analyses in this article and previous research results,we consider that the magmatic event in ~ 2.5Ga in the Zhongtiao Mountain represents a major event of crustal reworking.

  6. P-T path fluid evolution in the Gross Spitzkoppe granite stock, Namibia

    Directory of Open Access Journals (Sweden)

    Stephen Frindt

    2002-01-01

    Full Text Available The Gross Spitzkoppe granite stock (GSS is a zoned 30 km^2 epizonal intrusion that consists of three main granites: 1 medium-grained biotite granite (marginal, 2 a coarse-grained biotite granite, and 3 a central, porphyritic granite. The stock contains pegmatites as banded marginal stockscheiders and isolated pockets composed of large alkali feldspar and quartz, dark mica, interstitial fluorite, and euhedral topaz and beryl crystals. In the porphyritic granite there are local wolframite-bearing greisens and hydrothermal fluorite and topaz-rich veins.Fluid inclusion studies were conducted on: 1 topaz and quartz crystals from the marginal stockscheider; 2 quartz, topaz, fluorite and beryl crystals from isolated pegmatites; 3 topaz from a miarolitic pegmatite; 4 beryl and quartz veins from greisenized porphyritic granite; and 5 fluorite from a late fluorite vein inthe coarse-grained biotite granite. Preliminary data indicate the presence of three compositionally distinct primary and pseudosecondary inclusion types that are of late magmatic-hydrothermal origin.Type 1. Low salinity (0–10 eq. wt% NaCl H2O (± CO2 inclusions that homogenize to the liquid phase in the temperature range of 300 to 550˚C. These inclusions are from quartz, topaz and beryl. Inclusions in fluorite from the fluorite vein homogenize at ~170˚C and have a salinity of ca. 1–2 eq. wt% NaCl.Type 2. Saline (25–30 eq. wt% NaCl halite-bearing H2O (± CO2 inclusions that homogenize to the liquid phase in the temperature range of 300 to 400˚C. These inclusions are from quartz.Type 3. Low salinity (0–3 eq. wt% NaCl H2O-CO2 inclusions that homogenize to vapor phase in the temperature range of 330 to 550˚C. These inclusions are from quartz and topaz.Hydrothermal fluids from greisen minerals are represented by type 1 and type 2 H2O inclusions. They are predominantly of low salinity (~8 eq. wt% NaCl and homogenize to the liquid phase in the temperature range of 300 to 500

  7. Diffusivity of Sr, I and Pu in Granite With Through-Diffusion Experiment

    DEFF Research Database (Denmark)

    Dang, Hai-Jun; Hou, Xiaolin; Liu, Wen-yuan;

    2014-01-01

    The diffusion behavior of Sr, I and Pu in granite was investigated by through-diffusion experiment. the effective diffusion coefficients of Sr, I and Pu in granite at 26 °C were determined to be (1.24±0.03)×10-13 m2/s, (2.88±0.02)×10-13 m2/s and (1.33±0.52)×10-13 m2/s, respectively. It is also ob...

  8. Estimating Influence of Crystallizing Latent Heat on Cooling-Crystallizing Process of a Granitic Melt and Its Geological Implications

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bangtong; WU Junqi; LING Hongfei; CHEN Peirong

    2008-01-01

    Based on the theory of thermal conductivity, in this paper we derived a formula to estimate the prolongation period (AtL) of cooling-crystallization process of a granitic melt caused by latent heat of crystallization as follows: △t=QL×△tcol/TM-TC×CP where TM is initial temperature of the granite melt, Tc crystallization temperature of the granite melt,CP specific heat, △tcol cooling period of a granite melt from its initial temperature (TM) to its crystallization temperature (TC), QL latent heat of the granite melt. The cooling period of the melt for the Fanshan granodiorite from its initial temperature (900℃) to crystallization temperature (600℃) could be estimated ~210,000 years if latent heat was not considered. Calculation for the Fanshan melt using the above formula yields a AtL value of~190,000 years, which implies that the actual cooling period within the temperature range of 900℃-600℃ should be 400,000 years. This demonstrates that the latent heat produced from crystallization of the granitic melt is a key factor influencing the cooling-crystallization process of a granitic melt, prolongating the period of crystallization and resulting in the large emplacement-crystallization time difference (ECTD) in granite batholith.

  9. Sorption and diffusion of selenium oxyanions in granitic rock

    Science.gov (United States)

    Ikonen, Jussi; Voutilainen, Mikko; Söderlund, Mervi; Jokelainen, Lalli; Siitari-Kauppi, Marja; Martin, Andrew

    2016-09-01

    The processes controlling diffusion and sorption of radionuclides have been studied extensively in the laboratory, whereas, only a few in-situ experiments have been carried out in order to study in-situ diffusion over the long-term (several years). This is largely due to the fact that in-situ experiments are typically time consuming and cost intensive, and it is commonly accepted that laboratory scale tests are well-established approaches to characterizing the properties of geological media. In order to assess the relevance of laboratory experiments, the Swiss National Cooperative for Disposal of Radioactive Waste (Nagra) have been conducting extensive experiments in the Underground Rock Laboratory (URL) at the Grimsel Test Site (GTS) in order to study radionuclide transport and retention in-situ. One of the elements used in these experiments is non-radioactive selenium, as an analog for the radiotoxic isotope Se-79, which is present in radioactive waste. In this work, two laboratory through-diffusion experiments using selenium as a tracer were carried out in block (decimeter) scale rock specimens to support one of the ongoing radionuclide transport and retention in-situ experiment at the GTS mentioned above. The though-diffusion tests of selenium were performed under atmospheric conditions in both Kuru grey granite (KGG) and Grimsel granodiorite (GG). The decrease of selenium concentration in an inlet hole drilled into each of the rock samples and the breakthrough of selenium into sampling holes drilled around the inlet were analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The effective diffusion (De) and distribution coefficients (Kd) of selenium were then determined from the changes of selenium concentration in the inlet and sampling holes using a Time-Domain Diffusion (TDD) simulations. In addition, Kd of selenium was measured by batch sorption experiments as a function of pH and Se concentration in atmospheric conditions and nitrogen

  10. Biofouling of granite-rapakivi in St. Petersburg monuments and in the quarry in Russia and Finland

    Science.gov (United States)

    Vlasov, Dmitry; Panova, Elena; Alampieva, Elena; Olhovaya, Elena; Popova, Tatyana; Vlasov, Alexey; Zelenskaya, Marina

    2013-04-01

    Granite-rapakivi was widely used in the architecture of St. Petersburg: the facades of buildings, embankments of rivers and canals, bridges, sculptural monuments, pedestals, facing the metro stations. This stone is rapidly destroyed due to the peculiarities of its structure. Biofouling of granite is insufficiently studied. Cause the destruction of granite can be bacteria, microscopic algae, fungi, mosses, lichens, higher plants, invertebrates and vertebrates. They often form specific lithobiotic communities that contribute to the destruction of granite-rapakivi. The objects of research were monuments of St. Petersburg (granite sculpture, facades, facing embankments) as well as granite-rapakivi quarries in Russia and Finland, where the stone was quarried for use in St. Petersburg. Sampling was carried out from the most typical biofouling sites. Different methods were applied for the study of damaged granite: petrographic analysis, light and scanning electron microscopy, methods for detection and identification of microorganisms, X-ray microprobe analysis. As result the main forms of granite destruction were described: fractures, ovoid weathering, granular disintegration, surface films, crusts and layers, pitting and fouling. Lichens, mosses, herbaceous and micromycetes were dominated on the granite-rapakivi in quarries. For example, in a Monferran quarry (Virolahti region) the complicated lithobiotic community was revealed. It included 30 species of micromycetes, 31 species of lichens, 10 species of moss. Bacteriological analysis showed the dominance of bacteria Bacillus, and actinomycetes in microbial biofilms. More than 100 species of plants were found on the granite embankments in St. Petersburg. They were confined to the cracks, seams of granite blocks. Plants and mosses were common to the granite embankments of rivers and canals in the central (historical) part of the city. Dimensions of mosses depend on the area of the deepening which they occupy. The most

  11. U-Pb zircon age of the foliated garnet-bearing granites in western Dabie Mountains,Central China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    U-Pb zircon dating on two foliated gar net-bearing granite samples in the western Dabie ultra high-pressure (UHP) metamorphic unit yields concordant ages of (234±4) Ma and (227±5) Ma, respectively. These ages, following the UHP peak metamorphism, represent the magma emplacement ages for the foliated garnet-bearing granites. This, for the first time, shows that there are the Triassic granites in the Dabie Mountains. The foliated gar net-bearing granites resemble A-type granite in geochemical characteristics, indicating that they were formed in exten sional geodynamic setting. The magma formation reflects a reheating event in the Dabie orogenic belt and it enhances the transfer of tectonic regime from collision into extension and promotes the rapid exhumation into lower crust for the UHP metamorphic rocks.

  12. Founder of Niobium-Tantalum Granite Deposit——Li Renke

    Institute of Scientific and Technical Information of China (English)

    1993-01-01

    Li Renke, Vice director of Nonferrous Metals Geological Research Institute of Guangxi, Senior Engineer, discovered a new type of niobium-tantalum granite deposit as his major contribution and made significant progress in ore exploration of this type of ore deposit.

  13. Dependency of hydromechanical properties of monzonitic granite on confining pressure and fluid pressure under compression

    Science.gov (United States)

    Wang, Huanling; Xu, Weiya; Lui, Zaobao; Chao, Zhiming; Meng, Qingxiang

    2016-05-01

    Monzonitic granite is a low-permeability rock. Monzonitic granite formations are ideal for underground storage of oil due to their low permeability and high mechanical strength. In this study, a series of coupled hydromechanical triaxial tests are carried out using monzonitic granite specimens. The influence of confining and fluid pressures on stress, strain, and permeability is investigated. Failure characteristics under different confining and fluid pressures are discussed based on the analysis of macro fracture planes and micro scanning electron microscopy (SEM). The test results show that the change of permeability with stress and strain reflects the deformation stages of compaction, compression, crack propagation, coalesce, and failure of cracks. Due to the low porosity, the change of permeability is small in the initial phases of compaction and compression, whereas there is a significant increase in permeability when new cracks start to develop and coalesce. Confining pressures have a significant impact on the strength and permeability, particularly the crack damage stress of the rock. Compared with confining pressure, the effect of fluid pressure on rock strength and crack damage stress is small. For the monzonitic granite specimens tested, changing the confining pressure results in different failure modes, whereas the fluid pressure has a relatively small effect on the failure modes.

  14. Preliminary Assessment/Site Inspection Work Plan for Granite Mountain Radio Relay System

    Science.gov (United States)

    1994-09-01

    Installation Restoration Program IRPIMS Installation Restoration Program Information Management System Jacobs Jacobs Engineering Group Inc. mg ...station; * water supply building; * two 30-foot high disk antennas; * four 60-foot high tropospheric antennas; * two fuel oil storage tanks; and...a predominant surface feature around the peak of Granite Mountain. This pluton is surrounded by an andesitic volcanic unit of early Cretaceous age

  15. Geomechanical Studies on Granite Intrusions in Alxa Area for High-Level Radioactive Waste Disposal

    Directory of Open Access Journals (Sweden)

    Cheng Cheng

    2016-12-01

    Full Text Available Geological storage is an important concept for high-level radioactive waste (HLW disposal, and detailed studies are required to protect the environment from contamination by radionuclides. This paper presents a series of geomechanical studies on the site selection for HLW disposal in the Alxa area of China. Surface investigation in the field and RQD analyses on the drill cores are carried out to evaluate the rock mass quality. Laboratory uniaxial and triaxial compressive tests on the samples prepared from the drill cores are conducted to estimate the strength properties of the host rock. It is found that the NRG sub-area has massive granite intrusions, and NRG01 cored granite samples show the best rock quality and higher peak strength under various confinements (0–30 MPa. NRG01 granite samples are applied for more detailed laboratory studies considering the effects of strain rate and temperature. It is observed that the increasing strain rate from 1.0 × 10−5–0.6 × 10−2·s−1 can lead to a limited increase on peak strength, but a much more violent failure under uniaxial compressive tests on the NRG01 granite samples, and the temperature increasing from 20 °C–200 °C may result in a slight increase of UCS, as well as more ductile post-peak behavior in the triaxial compressive tests.

  16. Rb-Sr age of Gaik granite, Ladakh Batholith, northwest Himalaya

    Energy Technology Data Exchange (ETDEWEB)

    Trivedi, J.R.; Gopalan, K. (Physical Research Lab., Ahmedabad (India)); Sharma, K.K.; Gupta, K.R.; Choubey, V.M. (Wadia Inst. of Himalayan Geology, Dehra Dun (India))

    1982-03-01

    The Gaik Granite is a part of Ladakh batholith outcropping between Gaik and Kiari in NW Himalaya. This is a pink porphyritic granite rich in biotite and poor in hornblende. Rb-Sr analyses have been made on six whole-rock samples of the Gaik Granite. Though the samples are poorly enriched in radiogenic Sr, they define a reliable isochron corresponding to an age of 235+-13(2sigma) m.y. and initial /sup 87/Sr//sup 86/Sr ratio of 0.7081+-0.0004 (2sigma), Biotite, plagioclase and potash feldspar fractions separated from two of the samples have yielded a much younger mineral isochron at 30+-1.5 m.y. indicating a nearly complete redistribution of Sr isotopes between mineral phases at a time much later than the primary emplacement of the granite. The present results show that at least some components of the Ladakh batholith are of Permo-Triassic aqe. These rocks were isotopically re-equilibrated on a mineral scale during Upper Oligocene in response to the Himalayan orogeny.

  17. The timing of tectonic transition from compression to extension in Dabieshan:Evidence from Mesozoic granites

    Institute of Scientific and Technical Information of China (English)

    MA Changqian; YANG Kunguang; MING Houli; LIN Guangchun

    2004-01-01

    With the methods of single grain zircon U-Pb and hornblende-biotite Ar-Ar dating, a U-Pb zircon age (135.4(2.7) Ma of Liujiawa high Sr/Y granite and 40Ar-39Ar plateau ages (139.0(1.0) Ma and (125.3(0.2) Ma of hornblende and biotite respectively of Fenliupu high Sr/Y granite in the Dabieshan high- and ultrahigh-pressure metamorphic belt are yielded. Following the emplacement of the high Sr/Y granites, extension-related mafic intrusions and late granitoids with negative Sr and Eu anomalies and isotopic ages of 105-130 Ma were emplaced. Geochemical comparison between the two types of granitoids shows that, from early to late, the alkalinities, the K2O contents and the Sr/Y ratios as well as FeO/(FeO+MgO) ratios of the rocks increase, while the abundance of Sr reduces, suggesting that as time goes on the depth of crustal melting decreases. Rheological stratification of the crust due to early Cretaceous partial melting of crustal rocks resulted in crustal extension and deep-buried rock exhumation. Therefore, the high Sr/Y granite that appeared at ~135 Ma is the product of the tectonic transition from early shortening to late overall extension.

  18. The thermal history of the miarolitic granite at Xincun,Fujian Province, China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The thermal history of the late Mesozoic miarolitic granite has been studied based on zircon U-Pb dating, whole rock Rb-Sr dating and K-Ar dating of muscovite, biotite and K-feldspar from the same rock sample. From the beginning of zircon crystallization to the closure of K-Ar system of biotite, the granite body had a slow cooling rate (11.0℃/Ma) and an ascending rate (0.07 mm/a). From the end of this stage to the closure of K-Ar system of K-feldspar, the granite body increased its cooling rate (45℃/Ma) and ascending rate (0.36 mm/a). The thermal history of the Xincun granite with a slow cooling rate at the early stage and a fast cooling rate at the late stage may have been related to the fact that the Fujian coastal area had very high geothermal gradient in the late Mesozoic and evident decrease in geothermal gradient in the early Cenozoic.

  19. Magnetic fabric transposition in folded granite sills in Variscan orogenic wedge

    Science.gov (United States)

    Závada, Prokop; Calassou, Thibaud; Schulmann, Karel; Hrouda, František; Štípská, Pavla; Hasalová, Pavlína; Míková, Jitka; Magna, Tomáš; Mixa, Petr

    2017-01-01

    New approach involving evaluation of anisotropy of magnetic susceptibility (AMS) data in stereoplots and Jelínek's Pj-T space, Vollmer's eigenvalue and microstructural analyses is proposed to discriminate between homogeneous and superposed deformation in granites. This method is used to decipher the internal AMS fabric and microstructural evolution of a folded array of granitic sills. The studied major sill shows a fabric and microstructural zonality marked by submagmatic and high-temperature Type I planar-linear fabric developed at sill margins, and the transpositional Type II subsolidus fabrics that formed at high to medium temperature deformation in the sill core. While Type I fabric is associated with dip slip magnetic lineations, Type II subsolidus fabrics are marked by subhorizontal magnetic lineations striking parallel to the long axis of the sill. The structural reconstruction of the fabrics in the granite and the host rocks as well as new U-Pb zircon ages suggest coeval emplacement of horizontal and vertical sills accounting for significant weakening of the host rock-magma multilayer. The model of folding of such multilayer and extrusion of residual magma parallel to axial planes is discussed with respect to structural record in other syn-contractional granite sill arrays forming sheeted plutons worldwide.

  20. Geochemical study of volcanic and associated granitic rocks from Endau Rompin, Johor, Peninsular Malaysia

    Indian Academy of Sciences (India)

    Azman A Ghani; Ismail Yusoff; Meor Hakif Amir Hassan; Rosli Ramli

    2013-02-01

    Geochemical studies and modelling show that both volcanic and granitic magmas from the western part of the Johor National Park, Endau Rompin are different and probably have different sources. The geochemical plot suggests that both dacite/rhyolite and andesite probably have a common origin as in many of the geochemical plots, these two groups form a similar trend. Volcanic rocks have a transitional geochemical character between tholeiite and calc alkaline on a Y versus Zr plot. (La/Yb)N versus La and TiO2 versus Zr modelling show that the crystallization of both granitic and volcanic magmas are controlled by a different set of minerals. The rare earth elements (REE) patterns of some of the granite and volcanic samples have pronounced negative Eu anomaly indicating plagioclase fractionation. The difference between both profiles is that the granite samples show a concave shape profile which is consistent with liquids produced by partial melting of quartz feldspathic rocks containing amphibole among the residual phase. Both magmas were generated at a different time during the subduction of Sibumasu beneath the Indochina blocks.

  1. Sea Dredged Gravel versus Crushed Granite as Coarse Aggregate for Self Compacting Concrete in Aggressive Environment

    DEFF Research Database (Denmark)

    Sørensen, Eigil V.; Kristensen, Lasse Frølich

    2007-01-01

    modulus of elasticity. Tensile and compressive strength were found to depend both on aggregate type and on the properties of the interfacial zone close to the aggregate surface. Freeze-thaw scaling resistance was good with crushed granite, whereas sea gravel led to more severe scaling caused by porphyry...

  2. Isotopic geochronology of granitic rocks from the Central Iberian Zone: comparison of methodologies

    Directory of Open Access Journals (Sweden)

    Antunes, I. M.H.R.

    2010-06-01

    Full Text Available Five granitic rocks, concentrically disposed from core to rim, were distinguished in the Castelo Branco pluton. U-Pb-Th electron microprobe monazite ages from granitic rocks are similar and ranging between 297-303 Ma. The granitic rocks from Castelo Branco pluton are 310 ± 1 Ma old, obtained by U-Pb (ID-TIMS in separated zircon and monazite crystals, indicating a similar emplacement age for all granitic rocks of the pluton. Initial 87Sr/86Sr isotopic ratios and epsilon-Nd310 and delta-18O values suggest three distinct pulses of granitic magma and that they are derived from partial melting of heterogeneous metasedimentary materials. The other granitic rocks are related by magmatic differentiation and show small variations in (87Sr/86Sr310, epsilon-Nd310 and delta-18O. The granitic pluton of Castelo Branco shows a rare reverse zoning.

    En el plutón de Castelo Branco, se distinguen cinco granitoides, dispuestos concéntricamente de núcleo a borde del plutón. Las edades U-Pb-Th obtenidas en cristales de monacita por microsonda electrónica en estos granitoides son similares entre sí y varían entre 297 y 303 Ma. Los resultados de datación por U-Pb (ID-TIMS en cristales de circón y de monacita de los tres granitos seleccionados, indican una edad de implantación de 310 ± 1 Ma y que son rocas emplazadas simultáneamente. Las relaciones isotópicas iniciales de 87Sr/86Sr y los valores de epsilon-Nd310 y delta-18O de los tres pulsos magmáticos son característicos de granitos resultantes de anatexia cortical a partir de rocas metasedimentarias heterogéneas. En la secuencia de diferenciación magmática, las rocas graníticas presentan pequeñas variaciones en (87Sr/86Sr310, epsilon-Nd310 y delta-18O. El plutón de Castelo Branco presenta un

  3. Geochronology, geochemistry and tectonic implications of Late Triassic granites in the Mongolian Altai Mountains

    Science.gov (United States)

    Dash, Batulzii; Boldbaatar, Enkhjargal; Zorigtkhuu, Oyun-Erdene; Yin, An

    2016-03-01

    Although the closure of the Paleo-Asian Ocean in western China and western Mongolia occurred in the Late Carboniferous and Early Permian, widespread intra-continental magmatism continued to occur across this region from the Late Permian to the end of the Triassic. In this study we document field relationships and geochemical characterization of a Late Triassic felsic intrusive complex in the western Mongolian Altai. The plutonic complex occurs as sills, dikes, and small stocks and its composition varies from biotite granite, two-mica granite, to leucogranite. Structurally, the plutonic complex occurs in the hanging wall of a segment of the regionally extensively (>1500 km long) Irtysh-Ertix-Bulgan thrust zone. As the plutonic bodies both cut and are deformed by the shear fabrics in this regional thrust shear zone, the duration of felsic magmatism and regional thrusting was temporally overlapping. This suggests that magmatism was coeval with crustal thickening. Major- and trace-element data and isotopic analysis of granitoid samples from our study area indicate that the felsic intrusions were derived from partial melting of meta-sediments, with the biotite and two-mica granite generated through vapor-absent melting and the leucogranite from flux melting. Although the Mongolian Altai intrusions were clearly originated from anatexis, coeval granite in the Chinese Altai directly west of our study area in the hanging wall of the Irtysh-Ertix-Bulgan thrust was derived in part from mantle melting. To reconcile these observations, we propose a Himalayan-style intracontinental-subduction model that predicts two geologic settings for the occurrence of felsic magmatism: (1) along the intracontinental thrust zone where granite was entirely generated by anatexis and (2) in the hanging wall of the intracontinental thrust where convective removal and/or continental subduction induced mantle melting.

  4. Pb–Pb zircon ages of Archaean metasediments and gneisses from the Dharwar craton, southern India: Implications for the antiquity of the eastern Dharwar craton

    Indian Academy of Sciences (India)

    B Maibam; J N Goswami; R Srinivasan

    2011-08-01

    207Pb–206Pb ages of zircons in samples of metasediments as well as ortho- and para-gneisses from both the western and the eastern parts of the Dharwar craton have been determined using an ion microprobe. Detrital zircons in metasedimentary rocks from both yielded ages ranging from 3.2 to 3.5 Ga. Zircons from orthogneisses from the two parts also yielded similar ages. Imprints of younger events have been discerned in the ages of overgrowths on older zircon cores in samples collected throughout the craton. Our data show that the evolution of the southwestern part of eastern Dharwar craton involved a significant amount of older crust (< 3.0 Ga). This would suggest that crust formation in both the western and eastern parts of the Dharwar craton took place over similar time interval starting in the Mesoarchaean at ca. 3.5 Ga and continuing until 2.5 Ga. Our data coupled with geological features and geodynamic setting of the Dharwar craton tend to suggest that the eastern Dharwar craton and the western Dharwar craton formed part of a single terrane.

  5. Heavy minerals and garnet geochemistry of stream sediments and bedrocks from the Almklovdalen area, Western Gneiss Region, SW Norway: Implications for provenance analysis

    Science.gov (United States)

    Krippner, Anne; Meinhold, Guido; Morton, Andrew C.; Schönig, Jan; von Eynatten, Hilmar

    2016-05-01

    Detrital heavy minerals commonly document the geological setting in the source area, hence they are widely used in sedimentary provenance analysis. In heavy mineral studies, the 63-125 and 63-250 μm grain size fractions are most commonly used. Heavy mineral data and garnet geochemistry of stream sediments and bedrocks from the catchment area draining the Almklovdalen peridotite massif in SW Norway reveal that a wider grain size spectrum needs to be considered to avoid misleading interpretations. The Almklovdalen peridotite massif consists mainly of dunite and harzburgite, as testified by the heavy mineral suite. At the outlet of the main river, the heavy mineral spectrum is very monotonous due to dilution by a strong influx of olivine. Heavy minerals like apatite and epidote characterising the host gneisses have almost disappeared. MgO-rich almandine garnets are more frequent in the coarser grain size fractions, whereas MnO-rich almandine garnets are more frequent in the finer grain size fractions. Garnets with pyrope content exceeding 50% are only found in the 500-1000 μm grain size fraction. Therefore, the sample location and the selected grain size fraction are of paramount importance when dealing with heavy minerals and mineral geochemical data; otherwise, provenance-sensitive information may be missed.

  6. Geochemistry of amphibolites and related graphitic gneisses from the Suchý and Malá Magura Mountains (central Western Carpathians) – evidence for relics of the Variscan ophiolite complex

    OpenAIRE

    Ivan Peter; Méres Štefan

    2015-01-01

    Three small bodies of amphibolites and associated graphitic gneisses from the Suchý and Malá Magura Mountains (Tatric Megaunit, central Western Carpathians) have been studied by petrographic and geochemical methods. Isolated, fault-bounded bodies first hundreds of meters in size are located in the complex of the Early Paleozoic paragneisses and migmatites intruded by the Lower Carboniferous granitoid rocks. Amphibolites (locally actinolite schists) were formed from effusive basalts, dolerites...

  7. On the role of contamination and hybridism in formation of the composite Raumid pluton granites (Pamir Mnts.): Results of Sm-Nd Isotope Study

    Science.gov (United States)

    Volkov, V. N.; Shatagin, K. N.; Kramchaninov, A. Yu.

    2016-09-01

    This work presents isotope Sm-Nd data obtained for bulk samples of granites of all 8 emplacement phases of the Raumid granite massif, which occurred 35 Ma ago at a hypabyssal depth during the orogenic stage of development of Southern Pamir fold system. The 147Sm/144Nd ratio in studied collection of granite samples ranges between 0.091 and 0.323; the ɛNd( T) value is-4.0. The Sm-Nd isotope study results suggest that all granite varieties distinguished in the Raumid massif are comagmatic formations and contamination and hybridization processes did not play any role in REE distribution in granites. At this, the source of parental magma did not change during granite generation. We assume that the only process, resulted in the trace element evolution in granites, was differentiation of three batches of magma sequentially uplifted from the source.

  8. Measurement of radioactivity and radon exhalation rate in different kinds of marbles and granites.

    Science.gov (United States)

    El-Dine, N W; El-Shershaby, A; Ahmed, F; Abdel-Haleem, A S

    2001-12-01

    Geological materials usually contaminated with naturally occurring radioactive materials (NORM) have become a focus of great attention. These NORM under certain conditions can reach hazardous contamination levels. Some contamination levels may be sufficiently severe that precautions must be taken. The present study deals with 60 geological samples (marble and granite) from both Egyptian and foreign locations. The studied samples were analyzed and the concentrations in Bq/kg dry weight of radioisotopes were determined by gamma-ray spectrometry using hyper-pure germanium (HPGe) detector in Bq/kg dry weight. The absorbed dose rate due to the natural radioactivity in the samples under investigation ranged from 2.45 +/- 0.07 to 64.44 +/- 1.93 nGy/h for marble and from 41.55 +/- 1.25 to 111.94 +/- 3.36 nGy/h for granite. The radium equivalent activity varied from 5.46 +/- 0.16 to 150.52 +/- 4.52 Bq/kg for marble samples and from 229.52 +/- 6.89 to 92.16 +/- 2.76 Bq/kg for granite. The representative external hazard index values for the corresponding samples are also estimated and given. The radon exhalation rates for marble and granite samples were also calculated by using solid state nuclear track detector (CR-39). The value of radium exhalation rate varied from 8.0 +/- 2.39 to 30.20 +/- 5.06 Bq/m2/d for marble and 6.89 +/- 1.72 to 25.79 +/- 4.38 Bq/m2/d for granite and the effective radium content was found to vary from 1.700 +/- 0.51 to 6.42 +/- 1.08 Bq/kg for marble and 1.29 +/- 0.32 to 5.63 +/- 0.96 Bq/kg for granite. The values of the radon exhalation rate and effective radium content are found to correspond with the values of uranium concentration measured by the HPGe detector in the corresponding sample.

  9. Igneous phenocrystic origin of K-feldspar megacrysts in granitic rocks from the Sierra Nevada batholith

    Science.gov (United States)

    Moore, J.G.; Sisson, T.W.

    2008-01-01

    Study of four K-feldspar megacrystic granitic plutons and related dikes in the Sierra Nevada composite batholith indicates that the megacrysts are phenocrysts that grew in contact with granitic melt. Growth to megacrystic sizes was due to repeated replenishment of the magma bodies by fresh granitic melt that maintained temperatures above the solidus for extended time periods and that provided components necessary for K-feldspar growth. These intrusions cooled 89-83 Ma, are the youngest in the range, and represent the culminating magmatic phase of the Sierra Nevada batholith. They are the granodiorite of Topaz Lake, the Cathedral Peak Granodiorite, the Mono Creek Granite, the Whitney Granodiorite, the Johnson Granite Porphyry, and the Golden Bear Dike. Megacrysts in these igneous bodies attain 4-10 cm in length. All have sawtooth oscillatory zoning marked by varying concentration of BaO ranging generally from 3.5 to 0.5 wt%. Some of the more pronounced zones begin with resorption and channeling of the underlying zone. Layers of mineral inclusions, principally plagioclase, but also biotite, quartz, hornblende, titanite, and accessory minerals, are parallel to the BaO-delineated zones, are sorted by size along the boundaries, and have their long axes preferentially aligned parallel to the boundaries. These features indicate that the K-feldspar megacrysts grew while surrounded by melt, allowing the inclusion minerals to periodically attach themselves to the faces of the growing crystals. The temperature of growth of titanite included within the K-feldspar megacrysts is estimated by use of a Zr-in-titanite geothermometer. Megacryst-hosted titanite grains all yield temperatures typical of felsic magmas, mainly 735-760 ??C. Titanite grains in the granodiorite hosts marginal to the megacrysts range to lower growth temperatures, in some instances into the subsolidus. The limited range and igneous values of growth temperatures for megacryst-hosted titanite grains support the

  10. Origin of Mesozoic and Tertiary granite in the western United States and implications for Pre-Mesozoic crustal structure: 2. Nd and Sr isotopic studies of unmineralized and Cu- and Mo-mineralized granite in the Precambrian Craton

    Science.gov (United States)

    Farmer, G. Lang; Depaolo, Donald J.

    1984-11-01

    In the Cordilleran region of the western United States, Mesozoic and Tertiary peraluminous granitic rocks display regional variations in initial 143Nd/144Nd (ɛNd); ɛNd = -10 to -12 in southern Arizona, - 17 to -19 in the northern Great Basin (NGB), and -30 in the northern Rocky Mountains. Initial 87Sr/86Sr values are between 0.710 and 0.721 and show no regional pattern. Metaluminous granitic rocks have a wider range of ɛNd values extending from values similar to those of the peraluminous granites to much higher values. The 87Sr/86Sr values are mostly fairly low, between 0.705 and 0.710 except in the NGB where values as high as 0.7157 are observed. No systematic differences between the ɛNd or 87Sr/86Sr values of Cu- or Mo-mineralized and Unmineralized granite were discerned, except for Cu-mineralized granite in eastern Nevada and Mo-mineralized granite in Colorado, which have ɛNd values higher (˜0) and lower ( ˜-10.0), respectively, than Unmineralized granite in the same region. Comparison to ɛNd values of exposed Precambrian rock suggests that the peraluminous granite, and the Mo granite in Colorado, were derived exclusively from felsic Precambrian basement rocks and that the regional variations in the ɛNd values reflect the regional variation in the average crustal age. The Nd data confirm that the Precambrian basement underlying the NGB and eastern California is isotopically distinct from Precambrian crust in the remainder of the western United States. The similarity between the ɛNd values of peraluminous granite and Precambrian crust also suggests that the high 147Sm/144Nd (>0.13) and the low total light rare earth element (LREE) abundances characteristic of peraluminous granite in southern Arizona were imposed during the chemical evolution of the magmas. Metaluminous granite are interpreted to have formed via mixing of mantle-derived magma and large proportions of low 87Sr/86Sr (granulite facies) lower crust, except in the eastern NGB where the mantle

  11. Early to late Yanshanian I-type granites in Fujian Province, SE China: Implications for the tectonic setting and Mo mineralization

    Science.gov (United States)

    Yang, Yu-Long; Ni, Pei; Yan, Jun; Wu, Chang-Zhi; Dai, Bao-Zhang; Xu, Ying-Feng

    2017-04-01

    The Cathaysia Block is the southeastern part of the South China Block in Southeast (SE) China, and it hosts voluminous late Mesozoic I-, S-, and A-type granitoids, as well as minor highly fractionated granites. We present here zircon U-Pb age data and Nd-Hf isotopic data for the Dayang and Juzhou granites, together with new petrological and geochemical analyses. The Dayang pluton consists of fine-grained two-mica monzonitic granites in which the plagioclases exhibit zoning and poikilitic textures. In contrast, the Juzhou pluton consists of medium- to coarse-grained biotite K-feldspar granites that lack zoning and poikilitic textures. The emplacement ages are 143 ± 2.3 Ma for the Dayang pluton and 133 ± 2.1 Ma for the Juzhou pluton according to zircon U-Pb isotope analyses. The Dayang and Juzhou granites are both metaluminous and belong to the shoshonitic series. The Dayang granite exhibits very flat REE patterns, showing the tetrad effect, and the spidergrams show striking negative Ba, Sr, Nb, and Ti anomalies and a positive Ta anomaly. In contrast, the Juzhou granite has sloping REE patterns, but like the Dayang granite it also has striking negative Ba, Sr, Nb, Ta, and Ti anomalies. Petrographic and geochemical evidence indicates that the Dayang granite is a highly fractionated I-type granite and that the Juzhou granite is a typical I-type granite. The tetrad effect in the Dayang granite can be interpreted in terms of melt-rock interactions at a late stage of magma evolution, whereas the main mechanism during the evolution of the Juzhou magma was fractionation of plagioclase, biotite, hornblende, apatite, zircon, and allanite. Nd-Hf isotope data suggest that the Dayang and Juzhou granites were both formed partial melting of Paleoproterozoic basement rock and juvenile material (underplating basalts or Mayuan Group amphibolites), with the Juzhou granite having a greater contribution from juvenile material than the Dayang granite. Our new data, together with

  12. The Shahewan rapakivi-textured granite – quartz monzonite pluton, Qinling orogen, central China: mineral composition and petrogenetic significance

    Directory of Open Access Journals (Sweden)

    Xiaoxia Wang

    2002-01-01

    Full Text Available The Mesozoic Shahewan pluton consists of four texturally different types of biotite-hornblende quartz monzonite. In the porphyritic types alkali feldspar occurs as euhedral or ovoidal megacrysts that are often mantled by one or more plagioclase shells, and as smaller grains in the groundmass. Quartz, plagioclase (An20–28, biotite, and hornblende occur as inclusions in the alkali feldspar megacrystsand, more abundantly, in the groundmass. Euhedral quartz crystals in the groundmass are not as common and well developed as in typical rapakivi granite. Compared to typical rapakivi granites, the mafic minerals (biotite and hornblende are rich in Mg and poor in Fe, and the whole rock is low in Si, K, F, Ga, Zr, LREE, Fe/Mg, and K/Na. The rocks of the Shahewan pluton are thus regarded as rapakivi-textured quartz monzonites and granites but not true rapakivi granites.

  13. Evaluation of Slope Assessment System in Predicting Landslides along Roads Underlain by Granitic Formation

    Directory of Open Access Journals (Sweden)

    Bujang B.K. Huat

    2005-01-01

    Full Text Available A slope assessment is to estimate the probability of occurrence and likely severity of landslides in a given area. This study evaluates two existing Slope Assessment Systems (SAS for predicting landslide at the micro level of assessment developed by the Public Works Department of Malaysia, namely the Slope Information Management System (SIMS and the Slope Management and Risk Tracking System (SMART. From the results of this study, it appears that none of the existing SAS is satisfactory for predicting landslide in granitic formation, for various reasons such as the use of hazard score developed from another country and use of data-base derived from different rock formation. A new SAS was developed using nine-parameters equation that was based on the stepwise discriminant analysis. The new SAS appears to show a good capability in predicting landslides in granitic formations.

  14. Geochemical Characteristics of Rare Earth Elements of Guidong Granitic Complex and Relationship with Uranium Mineralization

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhanshi; Hua Renmin; Liu Xiaodong; Deng Ping; Wu Lieqin

    2007-01-01

    Guidong granitic complex is constituted by Luxi intrusion, Xiazhuang intrusion, Maofeng intrusion, Sundong intrusion, Aizi intrusion and Siqian intrusion, which emplaced in Indosinian and early Yanshanian Periods. These intrusions varied from each other not only in major element content, aluminium saturation index, but also in values of ΣREE, δEu, and LREE/HREE, (La/Yb)N, (La/Sm)N and (Gd/Yb)N. The Maofeng intrusion, which has the closest relationship with uranium mineralization, belongs to strong peraluminous granites. Having undergone much intense fluid-rock interaction, it is characterized by typical M-type tetrad effects and lowest values of ΣREE, δEu, LREE/HREE, (La/Yb)N, (La/Sm)N and (Gd/Yb)N ratios than other studied intrusions.

  15. Zircon U-Pb ages for Wulian granites in northwest Sulu and their tectonic implications

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The Wulian complex occurring in the north-western part of the Sulu orogen consists of metaigneous and metasedimentary rocks at greenschist-facies. Zircon U-Pb dating for three granite intrusions within it yields concordant ages of (672±4), (742±9) and (747±14) Ma, respectively. These ages indicate that the granites are the Neoproterozoic intrusions in the northern margin of the Yangtze plate, and correspond to the magmatic complex at Luzhenguan in the eastern part of the Beihuaiyang belt in the Dabie orogen. They were tectonic slices scraped off from the Yangtze plate during Triassic subduction and thus belong to a part of the accretionary wedge of the Yangtze plate subduction. The discovery of extensive Neoproterozoic magmatic rocks in the Wulian area suggests that the suture location between the North China and the Yangtze plates lies north of the Wulian complex.

  16. Characterisation of Australian Verdelho wines from the Queensland Granite Belt region.

    Science.gov (United States)

    Sonni, Francesca; Moore, Evan G; Chinnici, Fabio; Riponi, Claudio; Smyth, Heather E

    2016-04-01

    Verdelho is a white-grape-vine, growing well in the Granite Belt region of Queensland. Despite its traditional use in Madeira wine production, there is scant literature on the flavour characteristics of this variety as a dry wine. In this work, for the first time, volatile compounds of Verdelho wines from the Granite Belt have been isolated by solid phase extraction (SPE), and analysed using gas chromatography-mass spectrometry (GC-MS). A corresponding sensory characterisation of this distinctive wine style has also been investigated, using sensory descriptive analysis. Chemical compounds that mostly contribute to the flavour of these wines were related to fruity sweet notes (ethyl esters and acetates), grassy notes (3-hexenol), floral aromas (2-phenylethanol and β-linalool) and cheesy aromas (fatty acids). Sensory analysis confirmed that the Verdelho wines were characterised by fruity aroma attributes, especially "tree-fruit" and "rockmelon", together with "herbaceous", while significant differences in the other attributes were found.

  17. Source regions of granites and their links to tectonic environment: examples from the western United States

    Science.gov (United States)

    Anthony, Elizabeth Y.

    2005-03-01

    This review, in honor of Ilmari Haapala's retirement, reflects on lessons learned from studies of three granitic systems in western North America: (1) Mesoproterozoic samples from west Texas and east New Mexico; (2) Laramide granitic systems associated with porphyry-copper deposits in Arizona; and (3) granites of the Colorado Mineral Belt. The studies elucidate relationships amongst tectonic setting, source material, and magma chemistry. Mesoproterozoic basement samples are from two different felsic suites with distinct elemental and isotopic compositions. The first suite, the "plutonic province", is dominantly magnesian, calc-alkalic to alkali-calcic, and metaluminous. It has low K 2O/Na 2O and Rb/Sr, and Nd model ages of 1.56 to 1.40 Ga. The second suite, the "Panhandle igneous complex", is magnesian, metaluminous, alkalic, and is part of the Mesoproterozoic belt of magmatism that extends from Finland to southwestern United States. Samples from the Panhandle igneous complex demonstrate three episodes of magmatism: the first pulse was intrusion of quartz monzonite at 1380 to 1370 Ma; the second was comagmatic epizonal granite and rhyolite at 1360 to 1350 Ma. Both of these rock types are high-K to slightly ultra-high-K. The third pulse at 1338 to 1330 Ma was intrusion of ultra-high-K quartz syenite. Nd model ages (1.94 to 1.52 Ga) are distinct from those of the "plutonic province" and systematically older than crystallization ages, implying a substantial crustal input to the magmas. At the Sierrita porphyry-copper deposit in the Mazatzal Province of southeastern Arizona, trace element, Sr, and Nd isotopic compositions were determined for a suite of andesitic and rhyolitic rocks (67 Ma) intruded by granodiorite and granite. Isotopic composition and chemical evolution are well correlated throughout the suite. Andesite has the least negative initial ɛNd (-4.3) and lowest 87Sr/ 86Sr i (0.7069). It is also the oldest and chemically most primitive, having low

  18. Decay of granite monuments due to salt crystallization in a non-polluted urban environment

    Directory of Open Access Journals (Sweden)

    García-Talegón, J.

    1999-03-01

    Full Text Available The effect of salt crystallization on granite (s.l rocks used as building material in an urban environment with low atmospheric pollution was studied. The manners of salt crystallization and the subsequent deterioration caused were analyzed in unweathered granite and other fades which had undergone strong transformations in quarries before being used as stone materials, "alterites".

    Se estudia el efecto de la cristalización de sales solubles en rocas graníticas s.l empleadas como materiales de construcción, en ambiente urbano con baja contaminación atmosférica. Las formas en que cristalizan las sales y el deterioro asociado a su presencia son analizados en granitos sanos y en otras facies que han sufrido fuertes transformaciones en cantera previas a su empleo como materiales de construcción ("alteritas".

  19. Application and reliability analysis of DPM system in site investigation of HK weathered granite

    Institute of Scientific and Technical Information of China (English)

    Zhuoying Tan; Meifeng Cai; Zhongqi Yue; L.G.Tham; C.F.Lee

    2005-01-01

    A drilling process monitor (DPM) for ground characterization of weathered granite is presented. The monitor is portable and can be mounted on a hydraulic rotary drilling rig to record various drilling parameters in real time during normal subsurface investigation. The identification method for dominative and subsidiary interfaces has been established. The study reveals that the monitored drilling parameters are dependent on geotechnical materials and can be further applied to characterize ground interfaces.The t-test between manual logging and DPM logging has been carried out. The results show that the DPM has high accuracy in interfaces detection and well agreement with the manual logging. The findings show that the device and data analysis method are of potential application in subsurface drilling exploration in weathered granites. It also seems to have prospective uses in the determination of orebody boundary as well as in the detection of geohazards.

  20. Zircon U-Pb geochronological framework of Qitianling granite batholith, middle part of Nanling Range, South China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The Qitianling granite batholith (QGB) is located in the southern Hunan Province, middle part of the Nanling Range, South China. Its total exposure area is about 520 km2. Based on our 25 single grain zircon U-Pb age data and 7 published data as well as the geological, petrological, and space distribution characteristics, we conclude that QGB is an Early Yanshanian (Jurassic) multi-staged composite pluton. Its formation process can be subdivided into three major stages. The first stage, emplaced at 163―160 Ma with a peak at about 161 Ma, is mainly composed of hornblende-biotite monzonitic granites and locally biotite granites, and distributed in the eastern, northern, and western peripheral parts of the pluton. The second stage, emplaced at 157―153 Ma with a peak at 157―156 Ma, is mainly composed of biotite granites and locally containing hornblende, and distributed in the middle and southeastern parts of the pluton. The third stage, emplaced at 150―146 Ma with a peak at about 149 Ma, is mainly composed of fine-grained (locally porphyritic) biotite granites, and distributed in the middle-southern part of the pluton. Each stage can be further disintegrated into several granite bodies. The first two intrusive stages comprise the major phase of QGB, and the third intrusive stage comprises the additional phase. Many second stage fine-grained granite bosses and dykes intruded into the first stage host granites with clear chilling margin-baking phenomena at their intrusive contacts. They were emplaced in the open fracture space of the earlier stage consolidated rocks. Their isotopic ages are mostly 2―6 Ma younger than their hosts. Conceivably, the time interval from magma emplacement, through cooling, crystallization, solidification, up to fracturing of the earlier stage granites cannot exceed 2―6 Ma. During the Middle-Late Jurassic in the Qitianling area and neighboring Nanling Range, the coeval granitic and basic-intermediate magmatic activities were widely

  1. Geochemical characteristics and spectrometric prospecting in the muscovite-bearing pegmatites and granites, southeastern Aswan, Egypt

    Institute of Scientific and Technical Information of China (English)

    Gehad M. Saleh; Mohamed M. El Galy; Mohamed A. Obeid

    2008-01-01

    Rare metal mineralization of Sn, Nb-Ta and W is encountered in the Gebel Dihmit area (GDA), southeastern Aswan, Egypt. The mineralization is related to muscovite granites and their pegmatite derivatives. The pegmatites are divided into three types according to their main mineral assemblages: K-feldspar-muscovite-tourmaline, K-feldspar-albite-muscovite and albite-K-feldspar-lepidolite veins. Petrogenetic studies indicate that Sn and Nb-Ta mineralization extends from the late-magmatic stage to the pegmatite and hydrothermal stages of the (GDA) suite. The albite-K-feldspar-lepidolite granite is composed dominantly of albite, lepidolote, and quartz, with topaz, K-feldspar and amblygonite. The accessory minerals are zircon, monazite, pollucite, columbite-tantalite, microlite and Ta-rich cassiterite. Phenocrysts of quartz, topaz and K-feldspar contain abundant inclusions of albite laths and occasional lepidolite crystals along growth zones (snowball texture), indicating simultaneous crystallization from a subsolvus, residual magma. The origin of the pegmatites is attributed to extreme differentiation by fractional crystallization of a granitic magma. The economic potential for rare metals was evaluated in the geochemical discrimination diagrams. Accordingly, some of the pegmatites are not only highly differentiated in terms of alkalis, but also the promising targets for small-scale Ta and, to a less extent, Sn. The pegmatites also provide the first example of Fe-Mn and Nb-Ta fractionation in successive generations of granites to cassiterite-bearing pegmatites, which perfectly exhibit similar fractionation trends established for primary columbite-tantalite in the corresponding categories of pegmatites. Uranium and Th of magmatic origin are indicated by the presence of thorite and allanite, whereas evidence of hydrothermal mineralization is the alteration of rock- foring minerals such as feldspar and the formation of secondary minerals such as uranophane..

  2. Coral reef fish assemblages of coralline and granitic habitats of Curieuse Marine National Park

    OpenAIRE

    Pittman, S.J.

    1997-01-01

    Curieuse Marine National Park encompasses a diverse range of shallow water marine and brackish habitats including coralline fringing reefs, granitic boulder reefs, deep patch reefs, algal flats, seagrass meadows, intertidal rocky shore, sandy beach and mangrove habitat. Many of these shallow water habitats support an abundance of varied marine life, which in turn supports a burgeoning interest from tourist divers and snorkellers. Curieuse Marine National Park includes Curieuse Island and t...

  3. Radiometric evaluation of granite tables in environment public in the city of Recife-PE, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, Edilson A.; Amaral, Romilton dos S.; Santos Junior, Jose A. dos; Bezerra, Jairo D., E-mail: accioly.edilson@ufpe.b, E-mail: romilton@ufpe.b, E-mail: jaraujo@ufpe.b, E-mail: jairo.dias@ufpe.b [Universidade Federal de Pernambuco (RAE/DEN/UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Grupo de Radioecologia

    2011-07-01

    Granite in Pernambuco has been used as raw-material in several utensils, amongst which, furniture and decoration objects. This granite, besides being traded internally, is also exported to Asia and Europe. Differentiated content of some radionuclides of the ({sup 238}U and {sup 232}Th) and {sup 40}K natural series above average content of other rocks is also commonly found, due to its origin and geological formation. The gamma radiation stems from the decay of the given series, followed by the {sup 40}K, and it should not exceed the 1 mSv.y{sup -1} limit per person of the public, according to the current radiological protection rules (ICRP, 60). This work aimed to radiometrically assess the granite tables used by the public of a well visited restaurant in the city of Recife. It is expected to contribute to the environmental monitoring and to assess the possible health risks for humans. The tables were monitored for a period of about one year. Dosimetric tablets of CaSO{sub 4}:Dy were used. The findings showed doses ranges from the background to 4.7 mSv.y{sup -1}, with general average of dose rate equal to 3.0 mSv.y{sup -1}. Therefore, it was concluded that despite the average dose rates in the different granite objects studied being higher than the recommended rate, the exposure does not offer risks to their users, due to the contact time (meal time) and the levels of radioactive emission found. (author)

  4. Aeroradiometric and photogeologic characterizations Of the younger granites in the north eastern desert, Egypt and implications for mineral deposits

    OpenAIRE

    Abdel Maksoud, M. A. [محمد علي عبدالمقصود; Meguid, Ahmed A. Abdel; Abuzied, Hassan T.; Rakaiby, Magid L.; Bishta, Adel Z.

    1995-01-01

    Photogeologic studies of the younger granites in the North Eastern Desert of Egypt using both aerial photographs and satellite images revealed the separation of three successive phases of younger granites with different photogeological radiometrical and gcologiical characteristics. The first phase plutons (YG1) are charactlerizcd by brown colour, dark tone, fine surface texture, low relief with gentle slopes, elongated ridges, large size (3 km3), and high density -dendritic to parallcd-dra...

  5. Indoor radon risk associated to post-tectonic biotite granites from Vila Pouca de Aguiar pluton, northern Portugal.

    Science.gov (United States)

    Martins, L M O; Gomes, M E P; Teixeira, R J S; Pereira, A J S C; Neves, L J P F

    2016-11-01

    At Vila Pouca de Aguiar area, northern Portugal, crops out a post-tectonic Variscan granite pluton, related with the Régua-Vila Real-Verín fault zone, comprising three types of biotite granites. Among these granites, PSG granite yield the highest average contents of U, probably due to its enrichment in accessory U-bearing minerals such as zircon. In the proximity of faults and joints, these granites are often affected by different degrees of hydrothermal alteration, forming reddish altered rocks, commonly known as "episyenites". These altered rocks are probably associated to the occurrence of hydrothermal processes, which led to uranium enrichment in the most advanced stages of episyenitization. In these granites, both average gamma absorbed dose rates in outdoor and indoor air are higher than those of the world average. Furthermore, even in the worst usage scenario, all these granites can be used as a building material, since their annual effective doses are similar to the limit defined by the European Commission. The geometric mean of radon activity of 91 dwellings located at the Vila Pouca de Aguiar pluton is 568Bqm(-3), exceeding that of other northern Portuguese granites. Measurements carried out during a winter season, indicate that 62.6% of the analysed dwellings yield higher indoor radon average values than the Portuguese legislation limit (400Bqm(-3)), and annual effective doses due higher than the world's average value (1.2mSvy(-1)). The interaction of geogenic, architectural and anthropogenic features is crucial to explain the variance in the geometric mean of radon activity of dwellings from Vila Pouca de Aguiar pluton, but the role of geologic faults is probably the most important decisive factor to increase the indoor radon concentration in dwellings. Hence, the development of awareness campaigns in order to inform population about the incurred radiological risks to radon exposure are highly recommended for this specific area.

  6. An investigation on surface roughness of granite machined by abrasive waterjet

    Indian Academy of Sciences (India)

    Gokhan Aydin; Izzet Karakurt; Kerim Aydiner

    2011-07-01

    Abrasive waterjet (AWJ) cutting is an emerging technology which enables the shaping of practically all engineering materials. However, AWJ cutting may cause roughness and waviness on the cut surface. This significantly affects the dimensional accuracy of the machined part and the quality of surface finish. In this study, the surface roughness of three granites is experimentally investigated for varying process parameters in abrasive waterjet. The philosophy of the Taguchi design is followed in the experimental study. Effects of the control (process) factors on the surface roughness are presented in terms of the mean of means responses. Additionally, the data obtained are evaluated statistically using the analysis of variance (ANOVA) to determine significant process parameters affecting the surface roughness. Furthermore, effects of the material properties on the surface roughness are assessed. It was statistically found that the water pressure and the abrasive flow rate are the most significant factors influencing the surface roughness of granites. Additionally, a consistent relationship between the material grain size and surface roughness of the granites was observed.

  7. Natural radioactivity in granite stones used as building materials in Iran.

    Science.gov (United States)

    Asgharizadeh, F; Abbasi, A; Hochaghani, O; Gooya, E S

    2012-04-01

    Due to increasing concern about environmental radiological protection, specific radioactivity concentrations of (226)Ra, (232)Th and (40)K in different types of commonly used granite stone samples collected from the Tehran city of Iran have been determined by means of a high-resolution HPGe gamma-spectroscopy system. The activity concentrations of (232)Th, (226)Ra and (40)K in the selected granite samples ranged from 18 to 178, 6 to 160 and 556 to 1539 Bq kg(-1), respectively. The radium equivalent activities (Ra(eq)) are lower than the limit of 370 Bq kg(-1) set by NEA-OECD [Nuclear Energy Agency. Exposure to radiation from natural radioactivity in building materials. Report by NEA Group of Experts. OECD (1979)], except in two samples. The internal hazard indexes have been found well below the acceptable limit in most of the samples. Five samples of investigated commercial granite stones do not satisfy the safety criterion illustrated by UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation. Exposure from natural sources of radiation. Report to the General Assembly (1993). Applying dose criteria recently recommended by the EC [European Commission Report on Radiological Protection Principles Concerning the Natural Radioactivity of Building Materials. Radiation Protection 112 (1999)] for superficial materials, all investigated samples meet the exemption dose limit of 0.3 mSv y(-1).

  8. Age of Yingfeng rapakivi granite pluton on the north flank of Qaidam and its geological significance

    Institute of Scientific and Technical Information of China (English)

    XIAO Qinghui; LU Xinxiang; WANG Fei; SUN Yangui; WEI Xiangdong; XlNG Zuoyun

    2004-01-01

    The Yingfeng rapakivi granite on the north flank of Qaidam is a newly discovered Proterozoic rapakivi pluton in China, which was found after the discovery of Shachang rapakivi in Miyun County, Beijing and Kuandian rapakivi in Jilin Province. Yingfeng rapakivi pluton is exposed on the north side of the suture belt between Qinling-Kunlun orogenic belt and North China plate. U-Pb zircon isotopic dating and Ar-Ar isotopic dating of both hornblende and K-feldspar from the Yingfeng rapakivi granite have been conducted. The results show that the age of (1776±33)Ma at the upper intercept in Concorde diagram represents the age of formation of the pluton,whereas the age of (526 ± 281) Ma at the lower intercept and Ar-Ar mineral dating of hornblende and K-feldspar correspond to the age of a later event affecting the pluton, suggesting that Yingfeng pluton has ever been affected by strong regional Caledonian-Hercynian tectonic movement after its formation. The discovery of middle Proterozoic Yingfeng rapakivi granite provides a petrologic evidence for the timing of cratonization of both the continental crust basement in western China and the basement of the North China plate and for a rifting event taking place in the mid-Proterozoic, suggesting that an amalgamation of ancient China continents had ever happened during the "L(u) liang Movement" between the early Proterozoic and the mid-Proterozoic.

  9. The structure and petrography of alkaline rocks of the Mada Younger Granite complex, Nigeria

    Science.gov (United States)

    Abaa, S. I.

    The structural aspects of the Mada Younger Granite complex differ from those described from other ring complexes in the province. Ring-dykes and cauldron subsidence structures are not observed and the extrusive rhyolites do not appear to be related to a volcanic cauldron. The minor remnants of the extrusive rocks were domes over small vents since there are no clear indications of any unified volcanic structure. Volcanic eruptions may have taken place from dispersed vents probably including pipes and fissures. Linear intrusive structures have been observed and there is no concentric arrangement of rock units. The biotite granites appear more as sheet structures dipping gently to the south. Petrographically, the extrusive rocks are rhyolites, the comenditic ignimbrite being distinctly peralkaline with aegirine and arfvedsonite. The granite cupolas may be classified as 'A'-type and have been affected by pervasive potash metasomatism which caused recrystallization with microline and finely twinned clear euhedral albite, together with mica compositions between annite towards lithian siderophyllite. This process also introduced minerals like fluorite, cassiterite, columbite and thorite which make the Mada complex a possible source for economic minerals.

  10. Crack growth time dependence analysis of granite under compressive-shear stresses state

    Institute of Scientific and Technical Information of China (English)

    LI Jiang-teng; CAO Ping; Gu De-sheng; Wu Chao

    2008-01-01

    The curves of crack relative length //b and crack growth time t of granite were gained under compressive stresses state according to subcritical crack growth parameters and crack stability growth equation by double-torsion constant displacement load relaxa-tion method. The relations between crack relative length and the crack growth time were discussed under different stresses and different crack lengths. The results show that there is a turning point on curve of crack relative length //b and crack growth time of granite. The slope of curve is small when crack relative length is less than the vertical coordinate of the point, and crack grows stably in this case. Cracks grow, encounter and integrate catastro-phically when crack relative length is more than the vertical coordinate of the point, and there is not a gradual stage from crack stability growth to crack instability growth, i.e. rock mass instability is sudden. The curves of crack relative length //b and crack growth time t of granite move to right with decrease of stress σ1 or crack length a, which implies that limit time increases consequently. The results correspond to practicality.

  11. Origin of Meter-Size Granite Basins in the Southern Sierra Nevada, California

    Science.gov (United States)

    Moore, James G.; Gorden, Mary A.; Robinson, Joel E.; Moring, Barry C.

    2008-01-01

    Meter-size granite basins are found in a 180-km belt extending south from the South Fork of the Kings River to Lake Isabella on the west slope of the southern Sierra Nevada, California. Their origin has long been debated. A total of 1,033 basins have been inventoried at 221 sites. The basins occur on bedrock granitic outcrops at a median elevation of 1,950 m. Median basin diameter among 30 of the basin sites varies from 89 to 170 cm, median depth is 12 to 63 cm. Eighty percent of the basin sites also contain smaller bedrock mortars (~1-2 liters in capacity) of the type used by Native Americans (American Indians) to grind acorns. Features that suggest a manmade origin for the basins are: restricted size, shape, and elevation range; common association with Indian middens and grinding mortars; a south- and west-facing aspect; presence of differing shapes in distinct localities; and location in a food-rich belt with pleasant summer weather. Volcanic ash (erupted A.D. 1240+-60) in the bottom of several of the basins indicates that they were used shortly before ~760 years ago but not thereafter. Experiments suggest that campfires built on the granite will weaken the bedrock and expedite excavation of the basins. The primary use of the basins was apparently in preparing food, including acorns and pine nuts. The basins are among the largest and most permanent artifacts remaining from the California Indian civilization.

  12. Hydric properties of some iberian ornamental granites with different superficial finishes: a petrophysical interpretation

    Directory of Open Access Journals (Sweden)

    Rojo, A.

    2003-03-01

    Full Text Available Some physical properties of three ornamental granites with different superficial finishes (polished, sawn and flamed were quantified by standard tests. These granites are commercially known as Rosa Porrino, Rosavel and Blanco Alcazar. The determined properties were: density, open porosity, water absorption, capillarity, evaporation, vapour absorption and water vapour permeability. The values of the hydric properties in the studied granites fundamentally depended on their textural characteristics, mainly grain size, micro cracking network and open porosity, and, to a lesser extent, on their superficial finish.

    El estudio analiza las diferencias en el comportamiento hídrico de tres granitos con diferentes acabados superficiales: pulido, corte de sierra y chorro de fuego. Estos granitos se comercializan con los nombres de Rosa Porrino, Rosavel y Blanco Alcázar. Las propiedades determinadas han sido: densidad, porosidad abierta, absorción libre de agua, absorción de vapor de agua, absorción de agua por capilaridad, evaporación y permeabilidad al vapor de agua. Los valores de las propiedades hídricas determinadas dependen fundamentalmente de las características texturales: tamaño de grano, microfisuras y porosidad abierta y, en menor medida, de los acabados superficiales.

  13. Oxygen isotope exchange kinetics between coexistent minerals and water in the Ertaibei granite pluton, northern Xinjiang

    Institute of Scientific and Technical Information of China (English)

    刘伟; 李志安; 赵志忠

    1996-01-01

    Coexistent minerals quartz, feldspar and biotite vary widely in δ18O value and display remarkable 18O/16O disequilibrium relations in the Ertaibei granite pluton, northern Xinjiang. The 18O/16O exchange reaction definitely occurred between granite and water. Initial δ18O values of the granite and exotic water are evaluated by the mass balance consideration. The results show that the 18O/16O exchange reaction is not necessarily accompanied by what geologists describe as petrological and mineralogiesl alteration effects, indicating that the exchange reaction occurs at a comparatively high temperature during subsolidus cooling of magmas. Exchange mechanism is mainly controlled by diffusion. It is demonstrated through quantitative modelling that the hydrothermal system associated with the Ertaibei pluton lived for 0.8-3 Ma, with a fluid flow rate of 3 × 10-14 mol · s-1 and water/rock (W/R) ratio of 0.79 - 3.08. Flow path and initial heterogeneity of the exotic metamorphic fluid are modelled with the δ1

  14. Sources of granite magmatism in the Embu Terrane (Ribeira Belt, Brazil): Neoproterozoic crust recycling constrained by elemental and isotope (Sr-Nd-Pb) geochemistry

    Science.gov (United States)

    Alves, Adriana; Janasi, Valdecir de Assis; Campos Neto, Mario da Costa

    2016-07-01

    Whole rock elemental and Sr-Nd isotope geochemistry and in situ K-feldspar Pb isotope geochemistry were used to identify the sources involved in the genesis of Neoproterozoic granites from the Embu Terrane, Ribeira Belt, SE Brazil. Granite magmatism spanned over 200 Ma (810-580 Ma), and is dominated by crust-derived relatively low-T (850-750 °C, zircon saturation) biotite granites to biotite-muscovite granites. Two Cryogenian plutons show the least negative εNdt (-8 to -10) and highest mg# (30-40) of the whole set. Their compositions are strongly contrasted, implying distinct sources for the peraluminous (ASI ∼ 1.2) ∼660 Ma Serra do Quebra-Cangalha batholith (metasedimentary rocks from relatively young upper crust with high Rb/Sr and low Th/U) and the metaluminous (ASI = 0.96-1.00) ∼ 630 Ma Santa Catarina Granite. Although not typical, the geochemical signature of these granites may reflect a continental margin arc environment, and they could be products of a prolonged period of oceanic plate consumption started at ∼810 Ma. The predominant Ediacaran (595-580 Ma) plutons have a spread of compositions from biotite granites with SiO2 as low as ∼65% (e.g., Itapeti, Mauá, Sabaúna and Lagoinha granites) to fractionated muscovite granites (Mogi das Cruzes, Santa Branca and Guacuri granites; up to ∼75% SiO2). εNdT are characteristically negative (-12 to -18), with corresponding Nd TDM indicating sources with Paleoproterozoic mean crustal ages (2.0-2.5 Ga). The Guacuri and Santa Branca muscovite granites have the more negative εNdt, highest 87Sr/86Srt (0.714-0.717) and lowest 208Pb/206Pb and 207Pb/206Pb, consistent with an old metasedimentary source with low time-integrated Rb/Sr. However, a positive Nd-Sr isotope correlation is suggested by data from the other granites, and would be consistent with mixing between an older source predominant in the Mauá granite and a younger, high Rb/Sr source that is more abundant in the Lagoinha granite sample. The

  15. Estimate of influence of U-Th-K radiogenic heat on cooling process of granitic melt and its geological implications

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The U-Th-40K concentrations of granite are on 1―2 orders of magnitude greater than those of basal- tic-ultrabasic rocks. Radiogenic heat of a granitic melt has significant influence on the cool- ing-crystallization period of the melt. In this paper we derived a formula to calculate prolongation period (tA) of cooling-crystallization of a granitic melt caused by radiogenic heat. Calculation using this for- mula and radioactive element concentrations (U=5.31×10-6; Th=23.1×10-6; K=4.55%) for the biotite adamellite of the Jinjiling batholith shows that the tA of the adamellite is 1.4 times of the cooling period of the granitic melt without considering radiogenic heat from the initial temperature (Tm=960℃) to crystallization temperature (Tc=600℃) of the melt. It has been demonstrated that the radiogenic heat produced in a granitic melt is a key factor influencing the cooling-crystallization process of the granitic melt, and is likely one of the reasons for inconsistence between emplacement ages and crystallization ages of many Meso-Cenozoic granitoids.

  16. The Yenshanian—type Twin Granite Belts in Intracontinental Compression—subduction Environments in the Northern Part of East Qinlin Area

    Institute of Scientific and Technical Information of China (English)

    胡志宏; 胡受奚; 等

    1990-01-01

    Calc-alkaline granites (excluding A-and M-type) could be divided into two petrogenic series,I,e,the syntexis series and the transformation series according to their genetic mechanisms.In the light of this classification we found that granites of these two series often aligne in paired zones parallel to contemporaneous B-type or intracontinental compression-subduction zones within ascended slabs,re-sulting in a regular zonal pattern together with subduction zones.Thus,they are defined as twin granite belts.According to the spatial relations between the granite belts and the subduction zones,the twin granite belts could be classified as A, AB and B-type .The zonation of granites of the two series in the northern part of the East Qinlin area could be cited as a typical example of A-type twin granite belts related to the Yenshanian intracontinenta compression-subduction movement in the area.In this paper the tectonic settings and petrogenic features of the twin granites belts in East Qinlin are systematically described,and a tectonic model for granitic magma genesis in intracontinental compression-subduction environments has been proposed.In this model the forma-tion of A-type twin granite belts is closely connected with tectonic movements in terms of the prince-ple,rule and dynamics of material differentiation in the lithosphere.

  17. Origin of the fluorine-rich highly differentiated granites from the Qianlishan composite plutons (South China) and implications for polymetallic mineralization

    Science.gov (United States)

    Chen, Bin; Ma, Xinghua; Wang, Zhiqiang

    2014-10-01

    Many composite granite plutons occur in South China, accompanied by large-scale polymetallic mineralization. Each composite pluton is composed of main-phase granite and late-stage highly differentiated granite. Traditionally, the highly differentiated granite is thought to be residual melt of the former via fractionation, and ore-forming materials and fluids are from granite magma itself. We propose a different model for the origin of the granites and related mineralization, based on petrological and geochemical studies on the Qianlishan composite plutons that host the supergiant Shizhuyuan W-Sn-Bi-Mo deposit. The main-phase granite shows features of normal granites, while the highly differentiated granite is characterized by F-rich, water-deficient, low fO2, alkalinity, REE tetrad effect, and modified behavior of some trace elements, e.g., very high K/Ba and low K/Rb and Zr/Hf ratios. We suggest that the parent magma of the highly differentiated granite was derived from melting of dominantly lower crustal rocks, triggered by underplating of a new pulse of basaltic magmas; small amounts of basaltic magmas and volatiles such as fluorine were involved in the source of the granite. Addition of fluorine lowered the solidus temperature and viscosity of granite magma, and thus prolonged the process of magma evolution. This resulted in extreme fractional crystallization, and intense interaction between melt and circulating waters from country rocks, forming the unusual geochemical features of the granite. The high temperature circulating waters, along with metamorphic fluids released from deep crustal rocks, subsequently, extract ore-forming metals from country rocks through forming F-bearing complexation, forming the polymetallic deposits.

  18. Fractured reservoir analogs: case study of paelocirculation markers on Tamariu's Granite.

    Science.gov (United States)

    Bertrand, Lionel; Legarzic, Edouard; Geraud, Yves; Diraison, Marc

    2013-04-01

    In fractured crystalline reservoirs, the grain matrix has in general a very low permeability and the fluid flow is localized in the fracture pattern. The flow in such fracture network is generally complicated to characterize, in on hand because many parameters (length, connectivity, aperture, tortuosity,…) are acting on the fluid flow, in other hand because the fractures at a reservoir scale using seismic data are not easy to characterize. In fact, the only information we have on fracture in buried reservoir are at a local scale with boreholes and at a kilometric scale with seismic. The study of field analogs is one way to establish a better comprehension of the fracture pattern between those two scales. Regional and outcrop studies on Tamariu's granite, which outcrops on the Catalonian Coastal Ranges, has permit the characterization of the faults and fractures at different scales. The faults network defines different sizes of structural blocks bordered by faults. In an unfaulted structural block, the granite exhibits a fracture network filled with hydrothermal carbonates, markers of important paleofluid circulation. These carbonates were analysed at different scales using fracture mapping, calcimetry and microscopy on thin- sections in order to define the location and the volume of the carbonates precipitation and to have an estimation of the paleo-porosity used by the fluids in the fracture network. With precise fracture maps, we analysed the principal flow direction and the nature of the hydrothermal deposits. The same maps, combined with calcimetry measurements, allow us to quantify the 2D volume of porosity used by the paleofluids. We have quantified the carbonates in different areas of percolation: the main veins, breccias cimented by carbonates, fractured granite and poorly fractured granite. The percentage of paleofluids markers reaches to 3% of the granitic rock, and the main part of them are localized in some fractured corridor composed of mains veins

  19. Silica enrichment, graphic granite and aquamarine growth: a new exploration guide

    Directory of Open Access Journals (Sweden)

    A. BHASKARA RAO

    2002-09-01

    Full Text Available Granitic pegmatites are traditionally known to contain graphic, perthitic and myrmekitic intergrowths related to quartz and K- and Na- feldspars. They are further considered to characterise the pegmatite types distinguishing them from the granites and other related plutonic rock types. Graphic granite is accepted also as a synonym to granitic pegmatite. Systematic studies, by the author and colleagues, on the granitic pegmatite gem deposits have permitted the definition of two aquamarine gem provinces in ENE Brazil, one in the NeoProterozoic and the other in the Archaean sequences. Potash feldspars in the pegmatites in the former show perthitic intergrowths, whereas in the latter graphic intergrowth dominates with anomalously coarse centimetric quartz along the cleavages of K-feldspar. Several granitic pegmatites hosted in Archaean complex, in Lages Pintadas Aquamarine Province, Santa Cruz, RN State, present this texture-structure. Graphic intergrowth is attributed to the eutectic crystallization, succeeded by hydrothermal fluids with silica enrichment permitting the growth through diffusion and nucleation of quartz and along cleavages of potash feldspar. In the Archaean terrain, the abundance of recycled chert forming metapsammitic migmatites traversed by numerous quartz veins and coarse graphic granites, has contributed to the growth of beryl and also the aquamarines.Pegmatitos graníticos são tradicionalmente conhecidos por terem intercrescimentos gráficos, pertíticos e mirmequíticos, relacionados a quartzo e feldspatos potássicos e sódicos. Também são considerados para caracterizar os tipos de pegmatitos, distinguindo-os dos granitos e outros tipos de rochas plutônicas relacionadas. Granito gráfico é aceito como sinônimo do pegmatito granítico. Estudos sistemáticos, do autor e seus colegas, sobre depósitos de pegmatitos graníticos de gemas permitiram a definição de duas províncias de gemas águas marinhas no ENE do Brasil

  20. Geochemistry and SHRIMP Zircon U-Pb Age of Post-Collisional Granites in the Southwest Tianshan Orogenic Belt of China: Examples from the Heiyingshan and Laohutai Plutons

    Institute of Scientific and Technical Information of China (English)

    LONG Lingli; GAO Jun; WANG Jingbin; QIAN Qing; XIONG Xianming; WANG Yuwang; WANG Lijuan; GAO Liming

    2008-01-01

    The Heiyingshan granite and the Laohutai granite plutons exposed in the Southwest Tianshan resemble A-type granites geochemically. Analysis shows that the both are ferron calc-alkalic peraluminous or ferron aikali-calcic peraluminous with a relatively high concentration of SiO2 (>70%), high alkali contents (Na2O + K2O = 7.14%-8.56%; K2O>N2O; A/CNK = 0.99-1.20), and pronounced negative anomales in Eu, Ba, Sr, P and Ti. A SHRIMP zircon U-Pb age of 285±4 Ma was obtained for the Heiyingshan hornblende biotite granite intrusion. The geochemical and age dating data reported in this paper indicate that these granites were formed during the post-collisional crustal extension of the Southwest Tianshan orogenic belt, in agreement with the published data for the granites in the South Tianshan.

  1. Mecanismos de deformación en la transición milonitas/striped gneiss y milonitas/ ultramilonitas en las sierras de Azul, cratón del Río de la Plata, Buenos Aires Deformation mechanisms in the mylonite/striped gneiss and mylonite/ultramylonite transition in Sierras de Azul, Río de la Plata craton, Buenos Aires

    Directory of Open Access Journals (Sweden)

    María C. Frisicale

    2010-08-01

    Full Text Available En el extremo occidental de la megacizalla de Azul se identificaron una serie de rocas miloníticas que presentan un grado de deformación variable e incluyen protomilonitas, milonitas, ribbon mylonites, striped gneisses y ultramilonitas. Se examinaron en forma detallada los mecanismos de deformación actuantes sobre los minerales principales de estas rocas, como feldespatos, cuarzo, anfíboles y piroxenos. El análisis de los mecanismos de deformación permitió realizar una estimación del grado metamórfico alcanzado en este sector de la zona de cizalla. Así se reconocen claramente dos áreas con diferente grado metamórfico, una en la que la deformación se habría producido en facies de anfibolita a granulita (temperaturas superiores a 600° y que se reconoce en los afloramientos del sector norte, cerro Negro y manantiales de Pereda; y una segunda área, que incluye los afloramientos de las estancias La Manuela y La Chiquita, donde la deformación, de menor intensidad, se desarrolló bajo condiciones de facies de esquistos verdes. Asimismo se analizaron los indicadores cinemáticos macro y microscópicos tales como estructuras S-C, granos rígidos fragmentados, porfiroclastos rotados y estructuras del tipo mineral-fish, con la finalidad de determinar el sentido de movimiento de las masas rocosas en esta área particular, y compararlo con los resultados existentes para el resto de la megacizalla de Azul.At the western sector of the Azul Megashear, mylonitic rocks with variable deformation that includes protomylonites, mylonites, ribbon mylonites, striped gneiss and ultramylonites were identified. A detailed examination of deformation mechanisms acting on main minerals like feldspar, quartz, amphibole and pyroxene was done. The analysis of deformation mechanisms allowed to establish the metamorphic degree reached in this sector of the shear zone. Thus, two areas with different metamorphic conditions were recognized. One of them, that involve

  2. Health assessment of natural radioactivity and radon exhalation rate in granites used as building materials in Lebanon.

    Science.gov (United States)

    Kobeissi, M A; El-Samad, O; Rachidi, I

    2013-03-01

    Measurements of specific activities (Bq kg(-1)) of gamma-emissions from radioactive nuclides, (238)U, (226)Ra, (214)Bi, (232)Th, (212)Pb and (40)K, contained in 28 granite types, used as building materials in indoors in Lebanon, were performed on the powdered granites. The concentration of the nuclides, (226)Ra, (232)Th and (40)K, in the granites varied from below detection level (BDL) to 494 Bq kg(-1), BDL to 157.2 Bq kg(-1) and BDL to 1776 Bq kg(-1), respectively. (226)Ra concentration equivalents, C(Raeq), were obtained and ranged between 37 and 591 Bq kg(-1), with certain values above the allowed limit of 370 Bq kg(-1). Calculated annual gamma-absorbed dose in air, D(aR), varied from 17.7 to 274.5 (nGy h(-1)). Annual effective dose, E (mSv y(-1)), of gamma radiations related to the studied granites and absorbed by the inhabitants was evaluated. E (mSv y(-1)) ranged from 0.09 to 1.35 mSv y(-1). Some granite types produced E above the allowed limit of 1 mSv y(-1) set by ICRP. Values of (222)Rn mass exhalation rate, E(M) (mBq kg(-1)h(-1))(,) in granite powder were obtained using the CR-39 detector technique. Diffusion factors, f, in 23 granite types were calculated with f ranging between (0.1 ± 0.02)×10(-2) and (6.6 ± 1.01)×10(-2).

  3. Th-rich zircon from peralka line A-type granite: Minera-logical features and petrological implications

    Institute of Scientific and Technical Information of China (English)

    XIE Lei; WANG Rucheng; CHEN Xiaoming; QIU Jiansheng; WANG Dezi

    2005-01-01

    The Taohuadao, Qingtian and Laoshan granites are three typical late Yanshannian peralkaline granitic plutons in the coastal area, eastern China. In this paper, internal structures and chemical compositions of zircon from these A-type granites were investigated by electron microprobe. It is shown that zircon grains are mainly composed of two distinctly separated parts. One is rich in Th (ThO2 >1 wt%, and ThO2/UO2 >2), and attains ThO2 up to 10.1 wt%; such value exceeds the dissolution limit of Th in the zircon structure (ThO2=5.5(2.5 wt%) determined in previous experiment. On the other hand, the other part is poor in Th (ThO2<1 wt%), but contains many thorite micro-inclusions with sieved texture. By comparison, it is also implied that zircon in aluminous A-type granites is characterized by low content of ThO2 (<1 wt%), ThO2/UO2 <2 and absence of thorite inclusion. Based on mineralogical features, one is tempted to assume that the Th-rich zircon is formed during the early crystallization of deep-sourced, high-temperature and Th-enriched A-type granitic magma. Such zircon is then subjected to late dissolution owing to accumulation of fluids at the end of magmatic evolution of A-type granite. Recrystallization finally leads to formation of sieved low-Th zircon with thorite micro-inclusions, which may coexist with remnants of Th-rich zircons. The Th-rich zircon may be considered to be one of characteristic accessory minerals of peralkaline A-type granites.

  4. Structures of Syn-deformational Granites in the Longquanguan Shear Zone and Their Monazite Electronic Microprobe Dating

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jinjiang; ZHAO Lan; LIU Shuwen

    2006-01-01

    The Longquanguan shear zone is an important structural belt in the North China Craton,separating the underlying Fuping complex from the overlying Wutai complex. This shear zone has experienced three episodes of deformation: the first and main episode is a ductile top-to-ESE shear along the gently northwest-west dipping foliations, while the other two episodes are later collapse sliding. Prolonged granites parallel to the shear foliations make one of the main compositions of the Longquanguan shear zone. These granites experienced deformation to form mylonitic rocks when they emplaced during the first episode of deformation. Structural characters of the granites and their contacts to the country rocks indicate that these granites possibly resulted from in-situ partial remelting by shearing, i.e., they are syn-deformational granites. Monazites in these mylonitic granites are magmatic minerals and their crystallization ages may represent ages of the magmatic events, and also the ages for the main deformation of the Longquanguan shear zone. Monazite electronic microprobe dating were carried on two samples of granite, which gives multiple peak ages, among which 1,846 Ma and 1,877 Ma are the main peak ages for the two samples. These ages represent the main deformation of the Longquanguan shear zone, which is consistent with the main regional geological event at about 1,850 Ma caused by the collision between the Eastern and Western Blocks in North China. The good match between the monazite ages and the corresponding regional tectono-thermal events shows the feasibility and reliability of monazite electronic microprobe dating.

  5. The Hydrothermal Na-Ca Alteration at the Marginal Part 0f the Florina Granite and the Associated Magnetite-Hematite Bands With Thorium and Uranium Mineralization

    Institute of Scientific and Technical Information of China (English)

    VEKIOS,P.; KELEPERTZIS,A.; BOURITHI,I.; MPARLAS,K.

    2002-01-01

    The Oxia mineralized granite is the product of differentiation in the external parts of the Florina magmatic mass. Acidic hydrothermal solutions either of magmatic or of meteoric origin reacted with the upper tectonically fractured parts of the Florina granite and became enriched in iron, thorium, uranium, zircon and rare-earth elements. The most abundant alteration minerals are sericite and quartz, while the minerals of the mineralization bands include magnetite, hematite, thorite, monazite and zircon. The outer parts of the Oxia granite made it easy the percolation of hydrothermal solutions from the deeper heater to the upper cooler parts of the granite which acted as a hot spot.

  6. Timing and origin of migmatitic gneisses in south Karakoram: Insights from U-Pb, Hf and O isotopic record of zircons

    Science.gov (United States)

    Mahar, Munazzam Ali; Mahéo, Gweltaz; Goodell, Philip C.; Pavlis, Terry L.

    2016-04-01

    The timing and origin of partial melting in collision belts is crucial to understand the thermotectonic evolution and the relationship between HT metamorphism and magmatism in over-thickened crust. In the present study, we used the in-situ isotopic (Hf, O and U-Pb) record of zircons to investigate the timing and origin of migmatitic gneisses exposed in the core of the Dassu dome in south Karakoram. The new U-Pb zircon dating identified the Proterozoic inherited cores (1.8-1.9 Ga and 2.3-2.5 Ga) surrounded by a Neogene overgrowth with ages ranging from ∼6 to ∼20 Ma. These ages imply that the partial melting in the Karakoram Metamorphic Complex lasted from >20 Ma to ∼6 Ma and can be correlated with the Miocene magmatism in the adjacent Baltoro region. Oxygen isotopic data from Proterozoic inherited cores (1.8-1.9 Ga) and Neogene overgrowths are indistinguishable and generally vary from 8‰ to 9.5‰. These values are slightly higher than the most igneous zircons (6.5-8‰, Valley et al., 2005) indicating an igneous precursor with heavy initial O composition that later might have equilibrated with low temperature environment or some involvement of supracrustal material is likely. However, a few low U/Th, relatively old inherited cores (2.3-2.5 Ga) showed mantle-like (δ18O = 5.3 ± 0.6‰, Valley et al., 2005) values of δ18O = 5.5 ± 2.7‰. The present-day weighted mean εHf (0) of the Proterozoic inherited cores ranges from -50 ± 1.0 to -44.3 ± 1.2. In contrast, the Neogene rims are 15-20 ε-units higher than the inherited core with present-day εHf (0) = -30.6 ± 0.9. This implies that the Hf composition of the Neogene overgrowth is not controlled exclusively by the dissolution of the inherited cores and that contamination by external melts is likely. We suggest a contribution from the Neogene, less-evolved magmatism in the Baltoro region (εHf (0) = ∼-4 to -10). The elevated oxygen composition is not consistent with the contribution from pristine

  7. The Paleoproterozoic Singo granite in south-central Uganda revealed as a nested igneous ring complex using geophysical data

    Science.gov (United States)

    Abdelsalam, Mohamed G.; Katumwehe, Andrew B.; Atekwana, Estella A.; Le Pera, Alan K.; Achang, Mercy

    2016-04-01

    We used high-resolution airborne magnetic and radiometric data and satellite gravity data to investigate the form of occurrence of the Paleoproterozoic Singo granite in west-central Uganda. This granitic body covers an area of ∼700 km2, intrudes Paleoproterozoic crystalline rocks and overlain by Paleoproterozoic-Mesoproterozoic sedimentary rocks, both of which belong to the Rwenzori terrane, and it is host to hydrothermally-formed economic minerals such as gold and tungsten. Our analysis provided unprecedented geometrical details of the granitic body and revealed the following: (1) the margins of the Singo granite are characterized by a higher magnetic signature compared to the interior of the granitic body as well as the surroundings. These anomalies are apparent in both the total magnetic field and horizontal derivative images and define eight overlapping ring features. (2) the depth continuation of these magnetic anomalies define outward but steeply-dipping features as indicated by the tilt images extracted from the airborne magnetic data. This is further supported by forward modeling of the magnetic and gravity data. (3) the Singo granite is characterized by relatively high and evenly-distributed equivalent concentration of Uranium (eU) and Thorium (eTh) compared to the surroundings and this is apparent in the Potassium (K)-eTh-eU radiometric ternary image. (4) the granitic body is defined by a gravity low anomaly that persisted to a depth of three km as shown by the Bouguer anomaly image and its five km upward continuation. We used these observations to identify this granitic body as a nested igneous ring complex and we refer to it as the Singo Igneous Ring Complex (SIRC). We further interpreted the eight ring structures as individual igneous ring complexes aligned in an E-W and NE-SW direction and these were developed due to repeated calderas collapse. Additionally, we interpreted the ring-shaped magnetic anomalies as due to hydrothermally-altered margins

  8. Mineralogy and Geochemistry of Granitic rocks within Lichen Hills, Outback Nunatak, Northern Victoria Land, Antarctica

    Science.gov (United States)

    KIM, T.; KIM, Y.; Lee, I.; Lee, J.; Woo, J.

    2015-12-01

    The study areas, Lichen Hills and Outback Nunatak are located in the Northern Victoria Land which is close to Pacific Ocean side of Transantarctic Mountain (TAM), Antarctica. According to the study of Zeller and Dreschoff (1990), the radioactivity values of Lichen hills and Frontier Mt. area in the Victoria Land were very high. To identify the geochemical characteristics of granitic rocks in these areas, 13 samples of Lichen Hills rocks and 4 samples of Outback Nunatak rocks are analyzed. For mineralogical study, samples were observed in macroscale as well as microscale including microscope electron probe analysis. Rock samples of Lichen Hills, Outback Nunatak are mainly leucogranite and granitic pegmatite. These rock samples are composed of quartz, k-feldspar, plagioclase, muscovite, garnet, tourmaline like granite. In SEM-EDS analysis, the observed light colored minerals show relatively high Th, U, Dy, Ce, Nb concentration. This suggests that rock samples may contain minerals such as fergusonite, monazite, thorite, allanite, karnasurtite which are considered to be REE-bearing minerals. Samples of related rocks have been analyzed in terms of major, trace and rare earth element (REE) concentrations using X-ray fluorescence (XRF) spectrometer and Inductively Coupled Plasma Mass Spectrometer (ICP-MS). As concentration of SiO2 increase, Al2O3, TiO2, Fe2O3, MgO, P2O5 concentration decrease and Na2O, K2O, MnO concentration increase. Analyzed trace elements and REE are normalized using CI Chondrite, Primitive mantle. The normalized data show that LREE are enriched compared to HREE. The distinct negative anomalies of Eu, Sr are observed, indicating that rock-forming melts are fairly processed state of fractional crystallization. It means that Th, U, Nb, Ta are much enriched in the melts.

  9. Environmental isotopes as indicators for ground water recharge to fractured granite.

    Science.gov (United States)

    Ofterdinger, U S; Balderer, W; Loew, S; Renard, P

    2004-01-01

    To assess the contribution of accumulated winter precipitation and glacial meltwater to the recharge of deep ground water flow systems in fracture crystalline rocks, measurements of environmental isotope ratios, hydrochemical composition, and in situ parameters of ground water were performed in a deep tunnel. The measurements demonstrate the significance of these ground water recharge components for deep ground water flow systems in fractured granites of a high alpine catchment in the Central Alps, Switzerland. Hydrochemical and in situ parameters, as well as delta(18)O in ground water samples collected in the tunnel, show only small temporal variations. The precipitation record of delta(18)O shows seasonal variations of approximately 14% and a decrease of 0.23% +/- 0.03% per 100 m elevation gain. delta(2)H and delta(18)O in precipitation are well correlated and plot close to the meteoric water line, as well as delta(2)H and delta(18)O in ground water samples, reflecting the meteoric origin of the latter. The depletion of 18O in ground water compared to 18O content in precipitation during the ground water recharge period indicates significant contributions from accumulated depleted winter precipitation to ground water recharge. The hydrochemical composition of the encountered ground water, Na-Ca-HCO3-SO4(-F), reflects an evolution of the ground water along the flowpath through the granite body. Observed tritium concentrations in ground water range from 2.6 to 16.6 TU, with the lowest values associated with a local negative temperature anomaly and anomalous depleted 18O in ground water. This demonstrates the effect of local ground water recharge from meltwater of submodern glacial ice. Such localized recharge from glaciated areas occurs along preferential flowpaths within the granite body that are mainly controlled by observed hydraulic active shear fractures and cataclastic faults.

  10. Petrogenesis of synorogenic diorite-granodiorite-granite complexes in the Damara Belt, Namibia: Constraints from U-Pb zircon ages and Sr-Nd-Pb isotopes

    Science.gov (United States)

    Jung, S.; Kröner, A.; Hauff, F.; Masberg, P.

    2015-01-01

    The synorogenic Palmental complex (central Damara Belt, Nambia) consists of ca. 545 Ma old quartz diorites and rare granodiorites and ca. 520 Ma-old leucogranites, representing one of the earliest and most primitive phase of crustal plutonism predating the main high-T regional metamorphism. Most quartz diorites and one granodiorite evolved through multistage, polybaric evolutionary processes involving fractionation from a lithospheric mantle-derived melt, followed by fractional crystallization of mainly hornblende, plagioclase and apatite which is shown by decreasing MgO, FeO, CaO, TiO2 and P2O5 with increasing SiO2. Assimilation of felsic basement gneisses was also important during formation of these granitoids. Although their chemical characteristics (high LILE, low HFSE) resemble those of quartz diorites and granodiorites with calc-alkaline affinity, they differ in their enriched Sr (initial 87Sr/86Sr: 0.7061-0.7098) and Nd (initial εNd: -2.7 to -9.9) isotopic composition. Neodymium depleted mantle mean crustal residence ages range from 1.3 to 1.9 Ga for the quartz diorites including the granodiorite. These model ages correlate with major and trace element abundances, further substantiating that AFC processes modified the initial isotopic systematics. Lead (206Pb/204Pb: 17.43-17.68, 207Pb/204Pb: 15.61-15.66, 208Pb/204Pb: 38.19-38.49) isotopic composition are unradiogenic relative to other Damaran intrusive rocks but plot above the Stacey and Kramers (1975) reference line, indicating that the source underwent an ancient (pre Pan-African) increase in U/Pb and Th/U, followed by more recent U-depletion. Some variation in 206Pb/204Pb at high 207Pb/204Pb further indicates involvement of ancient crustal material, most likely through AFC processes. A cross-cutting leucogranite dyke has also evolved isotopic compositions (initial 87Sr/86Sr: 0.7326; initial εNd: -15.6; 206Pb/204Pb: 17.42, 207Pb/204Pb: 15.62, 208Pb/204Pb: 38.16) but in view of the apparent younger age of

  11. Comparative evaluation of UV-vis-IR Nd:YAG laser cleaning of beeswax layers on granite substrates

    Science.gov (United States)

    Pan, A.; Chiussi, S.; González, P.; Serra, J.; León, B.

    2011-04-01

    The beeswax treatment applied in the sixties to prevent rain water from penetrating the outer stone surface of valuable granitic Galician monuments is contributing to the acceleration of the superficial degradation process of these monuments. At present, the northern sector of the renaissance frieze in the Cloister of the Cathedral of Santiago de Compostela is one of the most representative examples. Conventional wax removal methods (water, chemical and mechanical cleaning) can possibly destruct important details of the relief. Therefore laser removal is considered as a good alternative. In this work, we report systematic investigations of the effect of laser cleaning at different Nd:YAG laser wavelengths (266, 355, 532 and 1064 nm) on representative samples of the real historical surfaces. Laser removal of beeswax on granite at neither of the four wavelengths of the Nd:YAG laser is not a layer by layer removal process. For each irradiance and wavelength there is a maximum thickness that can be completely removed by a single pulse. Above this thickness the waxy material is not removed, although it undergoes thermal modifications; since the fraction of radiation that reaches the granite substrate is not enough to trigger the ejection of material. Our results show that the wax-granite interface plays a fundamental role in granite cleaning, and when the wax is weakened by absorption of radiation at 266 nm, the removal process becomes more efficient.

  12. Experimental and theoretical study of the Nd:YAG laser removal of beeswax on Galician granite at 355 nm

    Science.gov (United States)

    Pan, Aldara; Rebollar, Esther; Conde, J. Carlos; Lusquiños, Fernando; Chiussi, Stefano; León, Betty

    2010-09-01

    Beeswax coatings applied to seal off the granitic surfaces of many monuments have resulted in detrimental effects with time passing. Conservation procedures must be carried out in a selective way, removing the beeswax without any degradation of the stone. In this study we present an experimental analysis of the removal of beeswax using a Nd:YAG laser at a wavelength of 355 nm which is absorbed weakly by the beeswax. For this reason, an important percentage of the laser radiation reaches the granite substrate and the influence of the layer thickness must be studied. At each laser fluence, for single-pulse irradiation we find a maximum thickness for complete removal of the film. For thicker layers, the beeswax is not removed and additional effects such as color changes and thickness increase are observed. The experimental results suggest that a photomechanical mechanism is dominant and that granite absorption plays a fundamental role. Multiple-pulse irradiation is also performed to determine the optimal parameters for laser cleaning. Finally, infrared thermography measurements allow for the determination of the granite surface temperature after laser irradiation and theoretical calculations allow one to estimate the absorption behavior of granite at 355 and to explain the results obtained.

  13. Comparative evaluation of UV-vis-IR Nd:YAG laser cleaning of beeswax layers on granite substrates

    Energy Technology Data Exchange (ETDEWEB)

    Pan, A., E-mail: aldarapan@uvigo.es [Departamento de Fisica Aplicada, E.T.S.I Industriales, Universidad de Vigo, Rua Maxwell s/n. Campus Universitario Lagoas-Marcosende, E-36310 Vigo (Spain); Chiussi, S.; Gonzalez, P.; Serra, J.; Leon, B. [Departamento de Fisica Aplicada, E.T.S.I Industriales, Universidad de Vigo, Rua Maxwell s/n. Campus Universitario Lagoas-Marcosende, E-36310 Vigo (Spain)

    2011-04-15

    The beeswax treatment applied in the sixties to prevent rain water from penetrating the outer stone surface of valuable granitic Galician monuments is contributing to the acceleration of the superficial degradation process of these monuments. At present, the northern sector of the renaissance frieze in the Cloister of the Cathedral of Santiago de Compostela is one of the most representative examples. Conventional wax removal methods (water, chemical and mechanical cleaning) can possibly destruct important details of the relief. Therefore laser removal is considered as a good alternative. In this work, we report systematic investigations of the effect of laser cleaning at different Nd:YAG laser wavelengths (266, 355, 532 and 1064 nm) on representative samples of the real historical surfaces. Laser removal of beeswax on granite at neither of the four wavelengths of the Nd:YAG laser is not a layer by layer removal process. For each irradiance and wavelength there is a maximum thickness that can be completely removed by a single pulse. Above this thickness the waxy material is not removed, although it undergoes thermal modifications; since the fraction of radiation that reaches the granite substrate is not enough to trigger the ejection of material. Our results show that the wax-granite interface plays a fundamental role in granite cleaning, and when the wax is weakened by absorption of radiation at 266 nm, the removal process becomes more efficient.

  14. Ages and tectonic significance of the collision-related granite porphyries in the Lhunzhub Basin,Tibet,China

    Institute of Scientific and Technical Information of China (English)

    WANG LiQuan; ZHU DiCheng; GENG QuanRu; LIAO ZhongLi; PAN GuiTang

    2007-01-01

    The Paleocene collision-related granite porphyries are identified for the first time along the western margin of the Lhunzhub Basin,Tibet.SHRIMP U-Pb zircon analysis indicates that the granite porphyries were emplaced at 58.7±1.1 Ma(MSWD=0.79)during the Indo-Asian continental collision.The granite porphyries are peraluminous and high in K,belonging to the calc-alkaline to high-K calc-alkaline series.They are relatively enriched in LILE,Th and LREE and depletion in Ba,Nb,P and Ti,characterized by LREE-enriched patterns with slightly to moderately negative Eu anomalies.These Paleocene granite porphyries are interpreted as the products generated by partial melting of the pre-existing arc crustal rocks caused by the increase of pressures and temperatures during the crustal shortening at the early stages of the Indo-Asian continental collision since 65 Ma.Despite inherited geochemical features and tectonic settings of the arc protoliths,they are significantly different from the volcanic rocks of the Dianzhong Formation within the Linzizong Group and the Miocene granite porphyries in the Gangdise belt.

  15. Geochronology and tectonic significance of Middle Proterozoic granitic orthogneiss, North Qaidam HP/UHP terrane, Western China

    Science.gov (United States)

    Mattinson, C.G.; Wooden, J.L.; Liou, J.G.; Bird, D.K.; Wu, C.L.

    2006-01-01

    Amphibolite-facies para- and orthogneisses near Dulan, in the southeast part of the North Qaidam terrane, enclose minor ultra-high pressure (UHP) eclogite and peridotite. Field relations and coesite inclusions in zircons from paragneiss suggest that felsic, mafic, and ultramafic rocks all experienced UHP metamorphism and a common amphibolite-facies retrogression. Ion microprobe U-Pb and REE analyses of zircons from two granitic orthogneisses indicate magmatic crystallization at 927 ?? Ma and 921 ?? 7 Ma. Zircon rims in one of these samples yield younger ages (397-618 Ma) compatible with partial zircon recrystallization during in-situ Ordovician-Silurian eclogite-facies metamorphism previously determined from eclogite and paragneiss in this area. The similarity between a 2496 ?? 18 Ma xenocrystic core and 2.4-2.5 Ga zircon cores in the surrounding paragneiss suggests that the granites intruded the sediments or that the granite is a melt of the older basement which supplied detritus to the sediments. The magmatic ages of the granitic orthogneisses are similar to 920-930 Ma ages of (meta)granitoids described further northwest in the North Qaidam terrane and its correlative west of the Altyn Tagh fault, suggesting that these areas formed a coherent block prior to widespread Mid Proterozoic granitic magmatism. ?? Springer-Verlag 2006.

  16. Appraisal and evolution of hydrochemical processes from proximity basalt and granite areas of Deccan Volcanic Province (DVP) in India

    Science.gov (United States)

    Sonkamble, Sahebrao; Sahya, Ashalata; Mondal, N. C.; Harikumar, P.

    2012-05-01

    SummaryThis paper deals with a systematic hydrochemical study carried out at proximity basalt and granite areas of Deccan Volcanic Province (DVP) in India to assess groundwater quality and evaluate the hydrochemical processes. A total of 40 groundwater samples were collected equally from these areas and analyzed. Results showed that the groundwaters rich in alkaline earth in the basalt and alkali rich element in the granite. The dominancy of cations was observed as Ca2+ > Mg2+ > Na+ > K+ in the basalt and Na+ > Mg2+ > K+ > Ca2+ in the granite, whereas anions as HCO3->Cl>SO42- and Cl>HCO3->SO42-, respectively. Hydrochemical processes were identified with the helps of ion exchange, carbonate weathering and dissolution, multiple ionic ratios, and silicate weathering, which shown the predominance of carbonate, dolomite, calcite and silicate (anorthite) weathering in basalt, but in granite, silicate (alkali feldspar) weathering was dominated. Factor analysis also showed that there were multiple processes acting on groundwaters, were separated from the main cluster. Salinity, Sodium Absorption Ratio (SAR), Soluble Sodium Percentage (SSP), Residual Sodium Carbonate (RSC), Kelley's Ratio (KR) and Permeability Index (PI) in well samples showed that groundwater in basalt was more suitable for irrigation purposes. Further, a digital elevation model (DEM) was generated using Global mapper (8.0 version) software, which aided to decipher the thickness of basalt trap, and vertical transition zone of basaltic (trap) and granitic (basement) aquifer at this DVP comprising with the well depths and groundwater chemistry.

  17. Uranium in granites from the Southwestern United States: actinide parent-daughter systems, sites and mobilization. First year report

    Energy Technology Data Exchange (ETDEWEB)

    Silver, L T; Williams, I S; Woodhead, J A

    1980-10-01

    Some of the principal findings of the study on the Lawler Peak Granite are: the granite is dated precisely by this work at 1411 +- 3 m.y., confirming its synchroneity with a great regional terrane of granites. Uranium is presently 8-10 times crustal abundance and thorium 2-3 times in this granite. Uranium is found to be enriched in at least eight, possibly ten, primary igneous mineral species over the whole-rock values. Individual mineral species show distinct levels in, and characteristics ranges of, uranium concentration. It appears that in a uraniferous granite such as this, conventional accuracy mineral suites probably cannot account for most of the uranium in the rock, and more rare, high U-concentration phases also are present and are significant uranium hosts. It appears that at least two different geological episodes have contributed to the disturbance of the U-Th-Pb isotope systems. Studies of various sites for transient dispersal of uranium, thorium, and radiogenic lead isotopes indicate a non-uniform dispersal of these components. It appears that the bulk rock has lost at least 24 percent of its original uranium endowment, accepting limited or no radiogenic lead or thorium migration from the sample.

  18. Occupational exposure due to naturally occurring radionuclide material in granite quarry industry.

    Science.gov (United States)

    Ademola, J A

    2012-02-01

    The potential occupational exposure in granite quarry industry due to the presence of naturally occurring radioactive material (NORM) has been investigated. The activity concentrations of (40)K, (226)Ra and (232)Th were determined using gamma-ray spectroscopy method. The annual effective dose of workers through different exposure pathways was determined by model calculations. The total annual effective dose varied from 21.48 to 33.69 μSv y(-1). Inhalation dose contributes the highest to the total effective dose. The results obtained were much lower than the intervention exemption levels (1.0 mSv y(-1)) given in the International Commission on Radiological Protection Publication 82.

  19. Delineation of Fractured Aquifer Using Numerical Analysis (Factor of Resistivity Data in a Granite Terrain

    Directory of Open Access Journals (Sweden)

    Rolland Andrade

    2014-01-01

    Full Text Available In hard rock terrain, fractured aquifers comprise the major source of groundwater availability where the phreatic aquifer is desaturated. Identification of fracture zones in hard rock terrain and potential groundwater source delineation had been a perennial problem in hydrology. The purpose of this paper is to highlight the study over a small watershed area, in a granite terrain, wherein an attempt was made to delineate and map the fractured aquifer using numerical (factor analysis of the conventional vertical electrical sounding data, which was obscure in curve matching technique. This numerical approach in concatenation with resistivity imaging or other techniques would prove to be an effective tool in groundwater exploration.

  20. Gamma-ray spectrometry of granitic suites of the Paranaguá Terrane, Southern Brazil

    Science.gov (United States)

    Weihermann, Jessica Derkacz; Ferreira, Francisco José Fonseca; Cury, Leonardo Fadel; da Silveira, Claudinei Taborda

    2016-09-01

    The Paranaguá Terrane, located in the coastal portion of the states of Santa Catarina, Paraná and São Paulo in Southern Brazil is a crustal segment constituted mainly by an igneous complex, with a variety of granitic rocks inserted into the Serra do Mar ridge. The average altitude is approximately 1200 m above sea level, with peaks of up to 1800 m. Due to the difficulty of accessing the area, a shortage of outcrops and the thick weathering mantle, this terrane is understudied. This research aims to evaluate the gamma-ray spectrometry data of the granitic suites of the Paranaguá Terrane, in correspondence with the geological, petrographical, lithogeochemical, relief and mass movement information available in the literature. Aerogeophysical data were acquired along north-south lines spaced at 500 m, with a mean terrain clearance of 100 m. These data cover potassium (K, %), equivalent in thorium (eTh, ppm) and equivalent in uranium (eU, ppm). After performing a critical analysis of the data, basic (K, eU, eTh) and ternary (R-K/G-eTh/B-eU) maps were generated and then superimposed on the digital elevation model (DEM). The investigation of the radionuclide mobility across the relief and weathering mantle consisted of an analysis of the schematic profiles of elevation related with each radionuclide; a comparison of the K, eU and eTh maps with their 3D correspondents; and the study of mass movements registered in the region. A statistical comparison of lithogeochemical (K, U, Th) and geophysical (K, eU, eTh) data showed consistency in all the granitic suites studied (Morro Inglês, Rio do Poço and Canavieiras-Estrela). Through gamma-ray spectrometry, it was possible to establish relationships between scars (from mass movements) and the gamma-ray responses as well as the radionuclide mobility and the relief and to map the granitic bodies.

  1. Chronological and geochemical studies of granite and enclave in Baimashan pluton, Hunan, South China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Zircon LA-ICP-MS U-Pb dating reveals that the Baimashan Pluton is composed mainly of late Indosinian (204.5±2.8 Ma-209.2±3.8 Ma) biotite granodiorites/monzonitic granites (LIGs) and early Yanshanian (176.7±1.7 Ma) two-micas monzonitic granites (EYGs),and the coeval (203.2±4.5 Ma-205.1±3.9 Ma) mafic microgranular enclaves (MMEs) are generally found in the former.In addition,the ages of cores within zircons from LIGs and MMEs ranging from 221.4±4.0 Ma to 226.5±4.1Ma provide evidence of multistage magma intrusion during Indosinian in the study area.Measured 3010±20.6 Ma of inherited zircon age suggests that there may be recycling Archaean curstal material in existence in this area.LIGs and EYGs share some similar geochemical features: subalkaline and peraluminous granites,enrichment of Th,U,K,Ta,Zr,Hf and LREE but depletion of Ba,Nb,P,Ti and Eu,low εNd(t) values but high (87Sr/86Sr)i ratios,and old T2DM (ca.1.9-2.0 Ga).The behaviors of incompatible elements and REE are mainly dominated by fractional crystallization of plagioclase,K-feldspar,ilmenite and apatite,but that of Sr isotope mainly controlled by EC-AFC.They are crust-sourced and derived from partial melting of paleo-Proterozoic metagreywackes and related to biotite dehydration melting.LIGs are formed in post-collisional tectonic setting as crustal local extension and thinning during late Indosinian.But EYGs may be evolved products of congeneric granitic magma with LIGs formed in late Indoinian,which were emplaced again when crust underwent extensive thinning and extension in post-orogenic tectonic setting during Yanshanian in SC after undergoing EC-AFC.MMEs should be cognate enclaves and derived from liquid immiscibility of host magma.

  2. Exploration methods for granitic natural stones – geological and topographical aspects from case studies in Finland

    Directory of Open Access Journals (Sweden)

    Olavi Selonen

    2014-06-01

    Full Text Available Regional and local geological constraints for location of natural stone deposits in glaciated terrains of southern and central Finland have been studied and applied to practical exploration for natural stone. A list of geological and topographical aspects to be considered in exploration, is presented. Important aspects refer to: 1. Regional geology of the target area. 2. Magmatism (type and structure of intrusion, relative time of pluton emplacement. 3. Metamorphism (grade, mineral composition, parent material. 4. Deformation (lineaments, shear zones, folding, fault zones, fracture zones, shape preferred mineral orientations, and 5. Topography (relative elevation, micro topography. The proposed aspects can be used as geological guidelines in exploration for granitic natural stones.

  3. Dynamic Brazilian Tests of Granite Under Coupled Static and Dynamic Loads

    OpenAIRE

    Zhou, Zilong; Li, Xibing; Zou, Yang; Jiang, Yihui; Li, Guonan

    2014-01-01

    Rocks in underground projects at great depth, which are under high static stresses, may be subjected to dynamic disturbance at the same time. In our previous work (Li et al. Int J Rock Mech Min Sci 45(5):739–748, 2008), the dynamic compressive behaviour of pre-stressed rocks was investigated using coupled-load equipment. The current work is devoted to the investigation of the dynamic tensile behaviour of granite rocks under coupled loads using the Brazilian disc (BD) method with the aid of a ...

  4. Generation of Late Mesozoic Qianlishan A2-type granite in Nanling Range, South China: Implications for Shizhuyuan W-Sn mineralization and tectonic evolution

    Science.gov (United States)

    Chen, Yuxiao; Li, He; Sun, Weidong; Ireland, Trevor; Tian, Xufeng; Hu, Yongbin; Yang, Wubin; Chen, Chen; Xu, Deru

    2016-12-01

    The Late Mesozoic Qianlishan granitic complex in the western Nanling Range, South China is associated with the Shizhuyuan giant W-Sn-Mo-Bi polymetallic deposit. It mainly consists of three phases of intrusions, P-1 porphyritic biotite granite, P-2 equigranular biotite granite and P-3 granite porphyry. All three phases of granite contain quartz, plagioclase, K-feldspar and Fe-rich biotite. They have geochemical affinities of A-type granites, e.g., high FeOT/(FeOT + MgO) ratios (0.84-0.99), total alkali (Na2O + K2O, 7.50-9.04 wt.%), high Ga/Al ratios (10,000*Ga/Al > 2.6) and high Zr + Nb + Y + Ce concentrations (> 350 ppm). High Y/Nb ratios (> 1.2) suggest that the Qianlishan complex belongs to A2-type granite. Zircon U-Pb ages indicate a short age interval decreasing from 158-157 Ma, to 158-155 Ma and to 154 Ma for the P-1, P-2 and P-3 granites, respectively. These ages are similar to the mineralization age of the Shizhuyuan tungsten polymetallic deposit, within error. The Qianlishan granites were generated at low oxygen fugacity conditions based on the low values of zircon Ce4 +/Ce3 + ratios (1.53-198) and significantly negative Eu anomalies (EuN/EuN*, 0.03-0.13) in apatite. New zircon εHf(t) values for the P-3 granite range from - 13.0 to - 4.4, similar to those previously obtained for the P-1 and P-2 granites. Both the granite and apatite grains therein are characterized by high F but low Cl concentrations, suggesting the influx of a high F/Cl component. The P-2 granites especially contain higher F contents (1840-8690 ppm) and W (7-158 ppm) and Sn (6-51 ppm) concentrations and with stronger evolution features. Positive trends between F and W and Sn of Qianlishan complex indicate that high F source is crucial for mineralization of W and Sn. We consider that the lithospheric mantle source may have been metasomatized by subduction fluids in the far end of subduction zones to produce the A2 feature of the Qianlishan granite and the fluorine was introduced through

  5. Timing and sources of granite magmatism in the Ribeira Belt, SE Brazil: Insights from zircon in situ U-Pb dating and Hf isotope geochemistry in granites from the São Roque Domain

    Science.gov (United States)

    Janasi, Valdecir de Assis; Andrade, Sandra; Vasconcellos, Antonio Carlos B. C.; Henrique-Pinto, Renato; Ulbrich, Horstpeter H. G. J.

    2016-07-01

    Eight new in situ U-Pb zircon age determinations by SHRIMP and LA-MC-ICPMS reveal that the main granitic magmatism in the São Roque Domain, which is largely dominated by metaluminous high-K calc-alkaline monzogranites with subordinate peraluminous leucogranites, occurred between 604 ± 3 and 590 ± 4 Ma. This small temporal range is ca. 20-30 Ma younger than previously admitted based on U-Pb TIMS dates from literature, some of which obtained in the same occurrences now dated. The observed discrepancy seems related to the presence of small Paleoproterozoic inherited cores in part of the zircon populations used for TIMS multigrain dating, which could also respond for the unusually high (up to 10 Ma) uncertainty associated with most of these dates. The younger age range now identified for the São Roque granite magmatism has important implications for the evolution of the Ribeira Fold Belt. Whilst previously admitted ages ca. 620-630 Ma substantiated correlations with the widespread and intensely foliated high-K calc-alkaline granitoid rocks of the neighbor Socorro-Guaxupé Nappe (potentially associated with an accretionary continental margin), the ˜600-590 Ma interval seems more consistent with a late deformation tectonic setting. Strongly negative ɛHf(t) characterize the magmatic zircons from the São Roque Domain granites. An eastward increase from -22 in the São Roque Granite to -11 in the Cantareira Granite and neighboring stocks suggests an across-domain shift in granite sources. Such eastward younging of sources, also indicated by Sm-Nd isotope data from granites and supracrustal sequences in neighboring domains, is suggestive that some of the first-order limits and discontinuities in this belt are not defined by the strike-slip fault systems traditionally taken to separate distinct domains. Although the negative ɛHf(t) and ɛNd(t) indicate sources with long crustal residence for all studied granite plutons, the observed range is more radiogenic than the

  6. Geochemical constraints on the source nature and melting conditions of Triassic granites from South Qinling in central China

    Science.gov (United States)

    Lu, Ying-Hui; Zhao, Zi-Fu; Zheng, Yong-Fei

    2016-11-01

    The Qinling orogen marks the continental collision between the North China Block and the South China Block in the Triassic, but the Triassic collisional orogeny is only prominent in the South Qinling zone with the occurrence of voluminous granites. In order to understand the petrogenesis of these granites, a combined study of petrology, geochronology and geochemistry was carried out for them from outcrops at Guangtoushan (GTS) and Huayang (HY) in South Qinling. The results indicate that the studied granites were derived from partial melting of metasedimentary rocks rather than metaigneous rocks as suggested by previous studies. LA-ICPMS zircon U-Pb dating yields concordant ages of 207 ± 3 Ma to 212 ± 4 Ma for their magma emplacement. The GTS granites are weakly to strongly peraluminous with A/CNK ratios of 1.05 to 1.15 and K2O/Na2O ratios of 0.5 to 1.32 and show high whole-rock δ18O values of 9.52 to 11.20‰. The HY granites are peraluminous with high A/CNK values of 1.04 to 1.14 and K2O/Na2O ratios of 1.01 to 2.82, and have high zircon δ18O values of 10.71 to 11.43‰ and whole-rock δ18O values of 12.42-13.77‰. On the other hand, the GTS granites exhibit low Rb/Sr ratios but high Sr/Ba ratios, variable Eu anomalies (Eu/Eu* = 0.29-1.05), in association with low zircon saturation temperatures. In contrast, the HY granites have high Rb/Sr ratios but low Rb/Ba ratios, conspicuous negative Eu anomalies (Eu/Eu* = 0.52-0.77) and relatively high zircon saturation temperatures. An integrated interpretation of all these results is that the GTS granites were produced by fluid-present partial melting of a mixture source of metapelite and metagreywacke at low temperatures, whereas the HY granites were generated by fluid-absent partial melting of a metagreywacke at relatively higher temperatures. Furthermore, the two granite plutons show variably high whole-rock (87Sr/86Sr)i ratios of 0.7047 to 0.7115, negative whole-rock εNd (t) values of - 9.8 to - 6.8 and zircon ε

  7. The Borodinskii Massif of potassium porphyric granite: Results of U-Pb dating and its tectonic position (Fennoscandian Shield)

    Science.gov (United States)

    Baltybaev, Sh. K.; Rizvanova, N. G.; Glebovitsky, V. A.

    2016-09-01

    It has been demonstrated for the first time that the Svecofennian crustal porphyric granites in the southeastern part of the Fennoscandian Shield are clearly subdivided into two age groups of 1.87 and 1.80 Ga. The representative of the first group is the Kuznechenskii Massif of porphyric granites with a U-Pb age of 1874 ± 4 Ma belongs to the group of plutons formed during the orogenic stage of Svecofennide evolution. The Borodinskii Massif with an age of 1797 ± 2 Ma is a member of the second group: these plutons were formed under tectonically stable (epiplatform) conditions. Therefore, the formation of porphyric granites occurred as the result of repeated generation of crustal magmas during multistage accretional growth of the Svecofennian crust.

  8. Methanobacterium subterraneum sp. nov., a new alkaliphilic, eurythermic and halotolerant methanogen isolated from deep granitic groundwater.

    Science.gov (United States)

    Kotelnikova, S; Macario, A J; Pedersen, K

    1998-04-01

    Deep subterranean granitic aquifers have not been explored regarding methanogens until now. Three autotrophic methane-producing Archaea were isolated from deep granitic groundwater at depths of 68, 409 and 420 m. These organisms were non-motile, small, thin rods, 0.1-0.15 micron in diameter, and they could use hydrogen and carbon dioxide or formate as substrates for growth and methanogenesis. One of the isolates, denoted A8p, was studied in detail. It grew with a doubling time of 2.5 h under optimal conditions (20-40 degrees C, pH 7.8-8.8 and 0.2-1.2 M NaCl). Strain A8p is eurythermic as it grew between 3.6 and 45 degrees C. It was resistant to up to 20 mg bacitracin l-1. The G + C content was 54.5 mol%, as determined by thermal denaturation. Phylogenetic studies based upon 16S rRNA gene sequence comparisons placed the isolate A8p in the genus Methanobacterium. Phenotypic and phylogenetic characters indicate that the alkaliphilic, halotolerant strain A8p represents a new species. We propose the name Methanobacterium subterraneum for this species, and strain A8p (= DSM 11074T) is the type strain.

  9. Experimental and numerical study of drill bit drop tests on Kuru granite

    Science.gov (United States)

    Fourmeau, Marion; Kane, Alexandre; Hokka, Mikko

    2017-01-01

    This paper presents an experimental and numerical study of Kuru grey granite impacted with a seven-buttons drill bit mounted on an instrumented drop test machine. The force versus displacement curves during the impact, so-called bit-rock interaction (BRI) curves, were obtained using strain gauge measurements for two levels of impact energy. Moreover, the volume of removed rock after each drop test was evaluated by stereo-lithography (three-dimensional surface reconstruction). A modified version of the Holmquist-Johnson-Cook (MHJC) material model was calibrated using Kuru granite test results available from the literature. Numerical simulations of the single drop tests were carried out using the MHJC model available in the LS-DYNA explicit finite-element solver. The influence of the impact energy and additional confining pressure on the BRI curves and the volume of the removed rock is discussed. In addition, the influence of the rock surface shape before impact was evaluated using two different mesh geometries: a flat surface and a hyperbolic surface. The experimental and numerical results are compared and discussed in terms of drilling efficiency through the mechanical specific energy. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  10. Lower Granite Dam Smolt Monitoring Program, 2003-2004 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Mensik, Fred; Rapp, Shawn; Ross, Doug

    2004-08-01

    The 2003 fish collection season at Lower Granite Dam Juvenile Fish Facility (LGR) was characterized by water temperatures, total flows and spill that were below the five year average, low levels of debris, and increased smolt collection numbers compared to 2002 with the exception of unclipped sockeye/kokanee. There were 6,183,825 juvenile salmonids collected. Of these, 6,054,167 were transported to release sites below Bonneville Dam, 5,957,885 by barge and 96,282 by truck. An additional 102,340 fish were bypassed back to the river, primarily due to research projects with another 62,122 bypassed through the PIT-tag bypass system. According to the PTAGIS database, 152,268 PIT-tagged fish were detected at Lower Granite Dam. Of these, Smolt Monitoring Staff recorded 345 PIT-tagged raceway and sample mortalities. Of the 6,183,825 total fish collected, 113,290 were PIT-tagged or radio tagged and 380 were sacrificed by researchers. The collection included 836,885 fish that had hatchery marks other than clipped fins (elastomer, freeze brands or Coded Wire Tags). An estimated 54,857 incidental fish were collected with an additional 8,730 adult salmonids removed from the separator.

  11. The influence of aspect on the biological weathering of granites: observations from the Kunlun Mountains, China

    Science.gov (United States)

    Hall, Kevin; Arocena, Joselito M.; Boelhouwers, Jan; Liping, Zhu

    2005-04-01

    Bedrock and boulder weathering in the higher elevation, permafrost areas of the Qinghai-Tibetan Plateau have usually been ascribed to frost action. For short periods during two summers, an attempt was made to better elucidate weathering processes in this region. A combination of visual observation coupled with rudimentary data regarding removable weathered material from the four cardinal aspects of granite boulders at elevations of 4600-5000 m in the Kunlun Mountains (Qinghai-Tibetan Plateau) showed that there was a distinct aspect influence (south>west>north>east) on weathering. It was also observed that there were aspect-constrained variations in chasmoendolithic communities and for lichen distribution. To further aid understanding, temperature data for the four aspects were collected for several weeks during the summers of 2 years, with data recording at 1-min intervals using ultraresponsive (0.05 s), high precision (0.1 °C), ultrasmall (0.15 mm diameter) thermocouples; humidity data were also collected at the rock face. Based on these data, an attempt is made to evaluate the nature of granite weathering in this region. To better understand what the impact of the lichens/endolithic communities was and how this varies, use is made of XRD and SEM analyses on samples from each aspect. In addition, iron-rich patinas were found on a number of the boulders, and these too were analyzed in an attempt to see their relationship (if any) to the biological action.

  12. The bowing potential of granitic rocks: rock fabrics, thermal properties and residual strain

    Science.gov (United States)

    Siegesmund, S.; Mosch, S.; Scheffzük, Ch.; Nikolayev, D. I.

    2008-10-01

    The bowing of natural stone panels is especially known for marble slabs. The bowing of granite is mainly known from tombstones in subtropical humid climate. Field inspections in combination with laboratory investigations with respect to the thermal expansion and the bowing potential was performed on two different granitoids (Cezlak granodiorite and Flossenbürg granite) which differ in the composition and rock fabrics. In addition, to describe and explain the effect of bowing of granitoid facade panels, neutron time-of-flight diffraction was applied to determine residual macro- and microstrain. The measurements were combined with investigations of the crystallographic preferred orientation of quartz and biotite. Both samples show a significant bowing as a function of panel thickness and destination temperature. In comparison to marbles the effect of bowing is more pronounced in granitoids at temperatures of 120°C. The bowing as well as the thermal expansion of the Cezlak sample is also anisotropic with respect to the rock fabrics. A quantitative estimate was performed based on the observed textures. The effect of the locked-in stresses may also have a control on the bowing together with the thermal stresses related to the different volume expansion of the rock-forming minerals.

  13. Chemical weathering and chemical runoffs in the seashore granite hills in South China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Surface runoffs and the contents of major ions and dissolved silicon were surveyed and analyzed based on weekly sampling for one year in a granite watershed of Zhuhai City, Guangdong Province. The results demonstrated that the slope runoff played an essential role in feeding the rivulet during precipitation, whereas the groundwater was more important for the rivulet in the non-raining stages. Dissolved silicon, Na+, HCO3-, and Clions constituted the major chemical components of the rivulet water. Atmospheric CO2 and H2SO4 sourced from the oxidation of pyrite were the main erosive mediums in the natural chemical weathering. Natural chemical weathering, the wet and dry deposition of sea-salt, and acids precipitation contributed approximately equal shares of anions to the rivulet water. The ratio of NO3- to SO42- was more than 1.0 in the runoff of the studied seashore watershed, whereas it is less than 1.0 in the Xijiang River that is adjacent to the study area. This implied that the chemical composition of runoff is controlled mainly by the differences in atmospheric acid precipitation caused by human activities and lithology within the catchments under the same bio-climate zone. The CO2 flux consumed by the rock chemical weathering processes within the seashore granite watershed in South China was (0.35-1.37)×105 mol km-2 a-1.

  14. Characterization of compression strength of granite-epoxy composites using design of experiments

    Directory of Open Access Journals (Sweden)

    Antonio Piratelli-Filho

    2008-12-01

    Full Text Available This paper presents a processing study of the polymer matrix composite (PMC developed with an epoxy polymeric matrix reinforced with particulate ceramic granite. This PMC composite has been reported to be used as structural parts of machine tools and Coordinate Measuring Machines due to its superior vibration damping characteristics and reduced processing cycle over cast iron. The investigated processing variables were epoxy content and particle size and the mechanical characterization was carried out by compressive tests. Rejects of granite with particle size smaller than 500 µm were prepared by crushing, milling and classification operations. The powder was mixed with different compositions of epoxy resin, between 15 and 20% in weight. An experiment was planned and executed according to the Factorial design technique using two variables at two levels. The obtained cylindrical samples were submitted to compressive strength tests and the results showed a maximum resistance of 114.23 MPa at 20 wt. (% epoxy, value close to that of the literature.

  15. Immobilization technologies for the management of hazardous industrial waste using granite waste (case study)

    Energy Technology Data Exchange (ETDEWEB)

    Lasheen, Mohamed R.; Ashmawy, Azza M.; Ibrahim, Hanan S.; Moniem, Shimaa M. Abdel [National Research Centre, Giza (Egypt)

    2016-03-15

    Full characterization of granite waste sludge (GWS) was accomplished by X-ray diffraction (XRD) and Xray fluorescence (XRF) for identification of its phase and chemical composition. Different leaching tests were conducted to determine the efficiency of the GWS for metal stabilization in hazardous sludge. The leaching of the metals from stabilized contaminated sludge was decreased as the GWS amount increased. Only 15% of GWS was sufficient for stabilization of all metal ions under investigation. The main reason for metal immobilization was attributed to the aluminosilicates or silicates matrix within the GWS, which can transform the metals in the form of their insoluble hydroxides or absorbed in the stabilized matrix. Also, solidification/stabilization technique was used for remediation of contaminated sludge. Compressive strength test after curing for 28 days was used for measuring the effectiveness of remediation technique; it was found to be 1.88MPa. This indicated that the remediated sludge was well solidified and safe to be used as a raw substance for roadway blocks. Therefore, this huge amount of by-product sludge derived from the granite cutting industry, which has a negative environmental impact due to its disposal, can be utilized as a binder material for solidification/stabilization of hazardous sludge.

  16. Natural radioactivity measurements in the granite rock of quarry sites, Johor, Malaysia

    Science.gov (United States)

    Alnour, I. A.; Wagiran, H.; Ibrahim, N.; Laili, Z.; Omar, M.; Hamzah, S.; Idi, Bello. Y.

    2012-12-01

    This study was conducted to determine the concentration of natural radionuclides in the granite rocks of selected quarry sites in Johor state, Malaysia and their possible radiological effects. The activity concentrations of 238U, 232Th and 40K in the areas of study indicated varying values of 238U, 232Th and 40K. The highest values of 238U and 232Th concentrations (67±1 and 85±2 Bq kg-1, respectively) were observed at Kamad Quarry (IJM), whereas the highest value of 40K concentration (722±18 Bq kg-1) was detected in Kim Seng Quarry, while the values of activity concentration are lower in Hanson Quarry Products (Kulai) (25±0.5 for 238U, 24±0.5 for 232Th and 429±11 for 40K). Overall, 40K has the highest concentration in the granite rocks of the quarry sites, followed by 232Th and the least for 238U. The radium equivalent activity concentration was found in the range between 94 and 239 Bq kg-1, the absorbed dose rate was found to be in the range between 47 and 112 nGy h-1, and effective dose ranged from 58 to 137 μSv h-1. Moreover, the internal and external hazard index values were given in results lower than unity.

  17. Smolt Condition and Timing of Arrival at Lower Granite Reservoir, 1988 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Edwin W.; Nelson, William R.

    1989-10-01

    This project monitored the daily passage of smelts during the 1988 spring outmigration at two migrant traps; one each on the Snake and Clear-water rivers. Due to the low runoff year, chinook salmon catch at the Snake River trap was very low. Steelhead trout catch was higher than normal, probably due to trap modifications and because the trap was moved to the east side of the river. Chinook salmon and steelhead trout catch at the Clearwater River trap was similar to 1987. Total cumulative recovery of PIT tagged fish at the three dams, with PIT tag detection systems was: 55% for chinook salmon, 73% for hatchery steelhead trout, and 75% for wild steelhead trout. Travel time through Lower Granite Reservoir for PIT tagged chinook salmon and steelhead trout, marked at the head of the reservoir, was affected by discharge. Statistical analysis showed that as discharge increased from 40 kcfs to 80 kcfs, chinook salmon travel time decreased three fold, and steelhead trout travel time decreased two fold. There was a statistical difference between estimates of travel time through Lower Granite Reservoir for PIT tagged and freeze branded steelhead trout, but not for chinook salmon. These differences may be related to the estimation techniques used for PIT tagged and freeze branded groups, rather than real differences in travel time.

  18. Smolt Condition and Timing of Arrival at Lower Granite Reservoir, 1987 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Edwin W.; Nelson, V. Lance

    1990-01-01

    This project monitored the daily passage of smolts during the 1988 spring outmigration at two migrant traps; one each on the Snake and Clearwater rivers. Due to the low runoff year, chinook salmon catch at the Snake River trap was very low. Steelhead trout catch was higher than normal, probably due to trap modifications and because the trap was moved to the east side of the river. Chinook salmon and steelhead trout catch at the Clearwater River trap was similar to 1987. Total cumulative recovery of PIT tagged fish at the three dams, with PIT tag detection systems was: 55% for chinook salmon, 73% for hatchery steelhead trout, and 75% for wild steelhead trout. Travel time through Lower Granite Reservoir for PIT tagged chinook salmon and steelhead trout, marked at the head of the reservoir, was affected by discharge. Statistical analysis showed that as discharge increased from 40 kcfs to 80 kcfs, chinook salmon travel time decreased three fold, and steelhead trout travel time decreased two fold. There was a statistical difference between estimates of travel time through Lower Granite Reservoir for PIT tagged and freeze branded steelhead trout, but not for chinook salmon. These differences may be related to the estimation techniques used for PIT tagged and freeze branded groups, rather than real differences in travel time. 10 figs, 15 tabs.

  19. Plutonium partitioning in three-phase systems with water, granite grains, and different colloids.

    Science.gov (United States)

    Xie, Jinchuan; Lin, Jianfeng; Zhou, Xiaohua; Li, Mei; Zhou, Guoqing

    2014-01-01

    Low-solubility contaminants with high affinity for colloid surfaces may form colloid-associated species. The mobile characteristics of this species are, however, ignored by the traditional sorption/distribution experiments in which colloidal species contributed to the immobile fraction of the contaminants retained on the solids as a result of centrifugation or ultrafiltration procedures. The mobility of the contaminants in subsurface environments might be underestimated accordingly. Our results show that colloidal species of (239)Pu in three-phase systems remained the highest percentages in comparison to both the dissolved species and the immobile species retained on the granite grains (solid phase), although the relative fraction of these three species depended on the colloid types. The real solid/liquid distribution coefficients (K s/d) experimentally determined were generally smaller than the traditional K s/d (i.e., the K s+c/d in this study) by ~1,000 mL/g for the three-phase systems with the mineral colloids (granite particle, soil colloid, or kaolinite colloid). For the humic acid system, the traditional K s/d was 140 mL/g, whereas the real K s/d was approximately zero. The deviations from the real solid/liquid K s/d were caused by the artificially increased immobile fraction of Pu. One has to be cautious in using K s/d-based transport models to predict the fate and transport of Pu in the environment.

  20. Microgranitoid Enclaves in Some I—and S—type Granites from Southern China

    Institute of Scientific and Technical Information of China (English)

    周金城; 陶仙聪; 等

    1994-01-01

    The three I-type plutons of Guantian(GT),Guidong(GD),Shangbao(SB)and the two S-type plutons of Xucun(XC)and Xiuning(XN) as well as their microgranitoid enclaves in southern China have been studied,Restite in the Motianling(MT) metasomatic granite in this area is described in this paper as well,Microgranitoid enclaves in the I-type granitoids may be divied into autoliths and schlierens which have marked differences both in petrography and geochemistry.In the S-type granitoids,schlierens are the major microgranitoid enclaves,but autoliths are rare.The metasomatic granite contains only restite without other enclaves.The microgranitoid enclaves and their host rocks have close ∈Nd(T)values and the same minerals within them are similar in composition.The microgranitoid enclaves,in general,don't represent the products of mixing of the syn-plutonic foreign mafic magma and the host acidic magma.They are the records of the evolution of intermediate-acidic magma itself.The formation of autoliths is related to the interdiffusion of different constituents in magma.Schlierens are the products of immiscible fractionation of the magma.

  1. Natural radioactivity levels in granitic plutons and groundwaters in Southeast part of Eskisehir, Turkey.

    Science.gov (United States)

    Orgün, Y; Altinsoy, N; Gültekin, A H; Karahan, G; Celebi, N

    2005-08-01

    The present work investigated the radioactivity level of the granitoid plutons and its effect on the groundwaters in the southeast part of Eskisehir. Fourteen granitic samples from the Kaymaz and Sivrihisar plutons and 11 groundwater samples from the near vicinity of the pluton were analyzed. The activity concentrations measured for (238)U and (232)Th ranged from 43.59+/-2 to 651.80+/-24 Bq/kg, and 51.16+/-3 to 351.94+/-13 Bq/kg, respectively. The activity concentrations obtained for (40)K varied from 418.50+/-17 to 1618.03+/-66 Bq/kg. The absorbed dose rates in air outdoors ranged from 87.14 to 531.81 nGy/h. All the results obtained from the Kaymaz pluton are higher than those from the Sivrihisar. The U (ave. 16.6 ppm) and Th (ave. 49.9 ppm) values of the Kaymaz pluton are higher than the average concentrations of the magmatic rocks of granitic composition. These results are consistent with high dose rates of the pluton. The gross-alpha activities in the groundwater samples ranged from 0.009 to 1.64 Bq/l and the gross-beta activities from 0.006 to 0.89 Bq/l. The highest gross-alpha value was found in the sample taken from near the Kaymaz pluton. The concentrations of (222)Rn varied from 0.060 to 0.557 Bq/l.

  2. Dynamic Brazilian Tests of Granite Under Coupled Static and Dynamic Loads

    Science.gov (United States)

    Zhou, Zilong; Li, Xibing; Zou, Yang; Jiang, Yihui; Li, Guonan

    2014-03-01

    Rocks in underground projects at great depth, which are under high static stresses, may be subjected to dynamic disturbance at the same time. In our previous work (Li et al. Int J Rock Mech Min Sci 45(5):739-748, 2008), the dynamic compressive behaviour of pre-stressed rocks was investigated using coupled-load equipment. The current work is devoted to the investigation of the dynamic tensile behaviour of granite rocks under coupled loads using the Brazilian disc (BD) method with the aid of a high-speed camera. Through wave analyses, stress measurements and crack photography, the fundamental problems of BD tests, such as stress equilibrium and crack initiation, were investigated by the consideration of different loading stresses with abruptly or slowly rising stress waves. The specially shaped striker method was used for the coupled-load test; this generates a slowly rising stress wave, which allows gradual stress accumulation in the specimen, whilst maintaining the load at both ends of the specimen in an equilibrium state. The test results showed that the tensile strength of the granite under coupled loads decreases with increases in the static pre-stresses, which might lead to modifications of the blasting design or support design in deep underground projects. Furthermore, the failure patterns of specimens under coupled loads have been investigated.

  3. Geochemistry, geochronology, and cathodoluminescence imagery of the Salihli and Turgutlu granites (central Menderes Massif, Western Turkey): Implications for Aegean tectonics

    Science.gov (United States)

    Catlos, E. J.; Baker, C.; Sorensen, S. S.; Çemen, I.; Hançer, M.

    2009-04-01

    The Menderes Massif (western Turkey) is an important metamorphic core complex located in the Aegean region; geochemical and geochronological data from this extensional domain facilitates our understanding of large-scale extension of the Earth's lithosphere. S-type, peraluminous granites (Salihli and Turgutlu) that intrude the Alasehir detachment which bounds the northern edge of the central Menderes Massif may have been generated due to subduction of the Eastern Mediterranean floor along the Hellenic trench. In situ Th-Pb ion microprobe monazite ages from the granites range from 21.7±4.5 Ma to 9.6±1.6 Ma (±1s). The range is consistent with cathodoluminescence (CL) imagery that document complex textures within the samples. Salihli and Turgutlu granites share many similar characteristics, including multiple generations of plagioclase (some with shocked cores consistent with magma mixing), plagioclase replacing K-feldspar and the development of myrmekite, clear evidence for fluid infiltration, and multiple generations of microcracks and microfaults. The granites may have evolved from compositionally distinct magma sources, as Salihli samples in general contain allanite as the major accessory mineral, whereas Turgutlu granites contain monazite. However, the CL imagery document similar alteration textures. Ages reported here are similar to dates constraining extension reported elsewhere in the Aegean, but indicate a level of complexity when linking movement within the Menderes Massif to the large-scale geodynamic processes that created other metamorphic core complexes in the region. Difficulties exist in linking the ages obtained from the granites to specific tectonic events due to the presence of secondary alteration textures, generations of mineral growth, and multiple episodes of deformation.

  4. Geology and rare-earth element geochemistry of highly evolved, molybdenite-bearing granitic plutons, Southeastern Desert, Egypt

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The field relations, mineralogy, and major and trace elements (including REE analyses of whole-rock samples and minerals) of granites and their associated molybdenite + uranium mineralized aplites in Southeastern Desert, Egypt, have been studied. The granites are leucocratic and mostly peraluminous in nature with muscovite increasing at the expense of biotite. The chemical and mineralogical characteristics of the granitic rocks indicate that their melts originated from the LILE-enriched mantle wedge by partial melting and are contaminated by crustal melts, followed by thermogravitational processes. Leucogranites with higher Na2O/K2O ratios from Um Dargag and Um Maiat crystallized under H2O-saturated equilibrium conditions in which the exsolved vapor continuously migrated away. The REE patterns of the granites studied are characterized by LREE enrichments and negative Eu anomalies. In comparison, the potassic aplites and the more sodic leucogranites are depleted in LREE, enriched in HREE and show more remarkable negative Eu anomalies. Allanite and monazite are the most important REE carriers in the granites. These minerals are strongly enriched in LREE, whereas fluorite and xenotime, which are more abundant in the aplites, are enriched in HREE. The average Lu/Ce ratio represents the fractionation trend with respect to HREE. It is 0.71 for radioactive fluorite, and it increases to 1.22 for non-radioactive fluorite. The high REE contents of molybdenite represent re-deposition of the mobilized Mo and REE. Due to the strong control of accessory minerals, the REEs are of limited use in petrogenetic modelling of highly evolved granitic systems.

  5. Updating of the hierarchical rock mass rating (HRMR) system and a new subsystem developed for weathered granite formations

    Institute of Scientific and Technical Information of China (English)

    Miranda Tiago; e Sousa L. Ribeiro; Tinoco Joaquim

    2014-01-01

    The RMR system is still very much applied in rock mechanics engineering context. It is based on the eval-uation of six weights to obtain a final rating. To obtain the final rating a considerable amount of informa-tion is needed concerning the rock mass which can be difficult to obtain in some projects or project stages at least with accuracy. In 2007 an alternative classification scheme based on the RMR, the Hierarchical Rock Mass Rating (HRMR) was presented. The main feature of this system was the adaptation to the level of knowledge existent about the rock mass to obtain the classification of the rock mass since it followed a decision tree approach. However, the HRMR was only valid for hard rock granites with low fracturing degrees. In this work, the database was enlarged with approximately 40%more cases considering other types of granite rock masses including weathered granites and based on this increased database the sys-tem was updated. Granite formations existent in the north of Portugal including Porto city are predom-inantly granites. Some years ago a light rail infrastructure was built in the city of Porto and surrounding municipalities which involved considerable challenges due to the high heterogeneity levels of the granite formations and the difficulties involved in their geomechanical characterization. In this work it is intended to provide also a contribution to improve the characterization of these formations with special emphasis to the weathered horizons. A specific subsystem applicable to the weathered formations was developed. The results of the validation of these systems are presented and show acceptable perfor-mances in identifying the correct class using less information than with the RMR system.

  6. Newly discovered uranium mineralization at 2.0 Ma in the Menggongjie granite-hosted uranium deposit, South China

    Science.gov (United States)

    Luo, Jin-Cheng; Hu, Rui-Zhong; Fayek, Mostafa; Bi, Xian-Wu; Shi, Shao-Hua; Chen, You-Wei

    2017-04-01

    The southeastern part of the Nanling metallogenic province, South China contains numerous economically important granite-hosted, hydrothermal vein-type uranium deposits. The Miao'ershan (MES) uranium ore field is one of the most important uranium sources in China, hosts the largest Chanziping carbonaceous-siliceous-pelitic rock-type uranium deposit and several representative granite-hosted uranium deposits. The geology and geochemistry of these deposits have been extensively studied. However, accurate and precise ages for the uranium mineralization are scarce because uranium minerals in these deposits are usually fine-grained, and may have formed in several stages, thus hindering the understanding of the uranium metallogenesis of this province. The Menggongjie (MGJ) uranium deposit is one of the largest granite-hosted uranium deposits in the MES ore field. Uranium mineralization in this deposit occurs at the central part of the MES granitic complex, accompanied with silicification, fluorination, K-metasomatism and hematitization. The ore minerals are dominated by uraninite, occurring in quartz or fluorite veinlets along fractures in altered granite. In-situ SIMS U-Pb dating on the uraninite yields the U-Pb isotopic age of 1.9 ± 0.7 Ma, which is comparable to the chemical U-Th-Pbtol uraninite age of 2.3 ± 0.1 Ma. Such ages agree well with the eruption ages of the extension-related Quaternary volcanics (2.1-1.2 Ma) in South China, suggesting that the uranium mineralization have formed at an extensional setting, possibly related to the Quaternary volcanic activities. Therefore, our robust, new dating results of the MGJ uranium deposit make it the youngest granite-hosted uranium deposit reported so far in South China and the mineralization event represents a newly identified mineralization epoch.

  7. Development of modal layering in granites: a case study from the Carna Pluton, Connemara, Ireland

    Science.gov (United States)

    McKenzie, Kirsty; McCarthy, William; Hunt, Emma

    2016-04-01

    Modal layering in igneous rocks uniquely record dynamic processes operating in magma chambers and also host a large proportion of Earth's strategic mineral deposits. This research investigates the origin of biotite modal layering and primary pseudo-sedimentary structures in felsic magmas, by using a combination of Crystal Size Distribution (CSD) analysis and Electron Probe Microanalysis (EPMA) to determine the mechanisms responsible for the development of these structures in the Carna Pluton, Connemara, Ireland. The Carna Pluton is a composite granodiorite intrusion and is one of five plutons comprising the Galway Granite Complex (425 - 380 Ma). Prominent 30 cm thick modal layers are defined by sharp basal contacts to a biotite-rich (20%) granite, which grades upward over 10 cm into biotite-poor, alkali-feldspar megacrystic granite. The layering strikes parallel to, and dips 30-60° N toward the external pluton contact. Pseudo-sedimentary structures (cross-bedding, flame structures, slumping and crystal graded bedding) are observed within these layers. Petrographic observations indicate the layers contain euhedral biotite and fresh undeformed quartz and feldspar. Throughout the pluton, alkali-feldspar phenocrysts define a foliation that is sub-parallel to the strike of biotite modal layers. Together these observations indicate that the intrusion's concentric foliation, biotite layers and associated structures formed in the magmatic state and due to a complex interaction between magma flow and crystallisation processes. Biotite CSDs (>250 crystals per sample) were determined for nine samples across three biotite-rich layers in a single unit. Preliminary CSD results suggest biotite within basal contacts accumulated via fractional crystallisation within an upward-growing crystal pile, likely reflecting the yield strength of the magma as a limiting factor to gravitational settling of biotite. This is supported by the abrupt decrease in mean biotite crystal size across

  8. Li isotope geochemical study on weathering of granite in Longnan, Jiangxi Province, South China

    Science.gov (United States)

    Liu, W.; Xu, Z.; Zhao, T.; Yu, C.; Zhou, L.

    2015-12-01

    Li isotopes have been demonstrated to be a powerful tool in silicate weathering research from the continental scale to that of catchments and weathering profiles. In this study, we focus on Li isotopic behavior during granite weathering and pedogenic processes. Study profiles are developed on a granite intrusion in Longnan, South China, under a subtropical monsoon climate. Two soil profiles (JLN-S4 on the ridgetop and JLN-S3 on the midslope; both 120cm deep) and one weathering profiles (JLN-S1 on the toe slope; 1100cm deep) along a hill slope were selected to represent the granite weathering process in near surface condition. Bulk samples of these profiles were analyzed for major element and Li content, and δ7Li value. CIA (chemical index of alteration) values were determined. The uppermost soil profile (JLN-S4) samples have CIA values between 97.6 and 98.3, with δ7Li values from -2.50 to -3.90‰; JLN-S3 profile samples have lower CIA values varing from 94.4 to 96.1 and δ7Li values from -0.73‰ to -1.55‰. The weathering profile JLN-S1 at the toe slope has a generally increasing CIA values (in the range of 57.8~92.4) upward in the profile. The δ7Li values variation with CIA in JLN-S1, shows a two staged relationship: δ7Li increasing from -14.92‰ to 0.66‰ when CIA increases from 57.8 to 74.6 as the first stage (from the bottom to 370cm depth), and no obvious relationship between CIA andδ7Li(-4.74~3.62‰) was observed in the second stage (CIA higher than 74.6, 370cm depth above). Li contents in JLN-S4 vary between 3.84 and 15.03 μg/g, in JLN-S3 between 1.43~8.03 μg/g, and in JLN-S1 between 6.95~22.27μg/g. In the first stage defined by δ7Li and CIA relationship, Li contents decrease with increasing CIA. However, in the second stage, Li abundance decreases upward at the beginning and turns into an increacing tendency (at 175cm depth) to the surface. Two granite bedrock samples have δ7Li value of -0.23 and 0.39‰, and Li contents of 38.58 and 34

  9. Age and weathering status of granite tors in Arctic Finland (~ 68° N)

    Science.gov (United States)

    Darmody, R. G.; Thorn, C. E.; Seppälä, M.; Campbell, S. W.; Li, Y. K.; Harbor, J.

    2008-02-01

    Cold-based ice along the Fennoscandian glacial ice divide in northern Finland allowed preservation of old landscape features. Because there was little or no movement at the ice-land surface contact, erosion was at a minimum, and relict landscape features such as tors can be found. We investigated two such granitic tors located at Pyhä-Nattanen (68°07.335' N, 27°22.207' E, 508 m asl) and Riestovaara (68°02.613' N, 27°09.003' E, 390 m asl) in subarctic Finland. At Pyhä-Nattanen, the sampling sequence included bedrock material and grus taken from within horizontal cracks, which are so prevalent at the site as to make the tor resemble a stack of pancakes. At Riestovaara, where the outcrop is more subdued, in addition to bedrock and grus samples, soil samples were also extracted from a pit dug in an embryonic soil forming on the bedrock surface. Based on cosmogenic nuclide dating, both tors greatly predate recent glaciation. The tor at Pyhä-Nattanen, which is a more prominent landscape feature, had longer minimum 10Be and 26Al apparent exposure ages, 89.1 ± 6.7 kyr and 69.6 ± 6.4 kyr, respectively, than did the tor at Riestovaara, 55.8 ± 4.5 kyr and 46.5 ± 4.0 kyr, respectively. Both of them are significantly older than the regional last deglaciation age, indicating that both sites have survived multiple episodes of glaciation. Analyses of the 10Be and 26Al measurements in accordance with marine oxygen isotope records (DSDP 607) indicate that the tors have undergone a minimum estimated total exposure-burial durations of 997 kyr (Pyhä-Nattanen) and 858 kyr (Riestovaara) and survived at least 14-16 episodes of glaciation. Weathering, as measured by porosity determined with a microprobe, was somewhat more advanced in the Pyhä-Nattanen granite samples than in the Riestovaara granite. However, with both granites, rock porosity did not change to a depth of 4 cm below the rock surface or vary by lichen cover/noncovered surfaces, indicating that weathering had

  10. The effect of surface finishes on outdoor granite and limestone pavers

    Directory of Open Access Journals (Sweden)

    Martínez-Martínez, J.

    2008-06-01

    Full Text Available Two types of ornamental stones, namely granite (Blanco Rafaela or Zarzalejo Granite and microcrystalline limestone (marble known commercially as Gris Pulpis, treated for different surface finishes, were tested for suitability as paving slabs. The finishes tested in both stones were polishing, hammering, honing and flaming, while acid treatment and abrasion were applied to limestone only and sawn finishes were only studied in granite.The stones were tested for the three physical properties that determine suitability for use as paving slabs; flexural strength under a concentrated load, and abrasion and slip resistance. Laboratory freeze-thaw cycle ageing tests were also conducted and flexural strength subsequently evaluated. Stone water sorption proved to be substantially unaltered by the type of finish employed. Finish barely affected flexural strength, except in the case of limestone flaming, where it was lower. Hammering was found to provide good slip resistance in both stones. The best slip performance for granite, however, was found for flamed specimens. Finish was shown to have no effect on abrasion resistance in either of the stone materials. Polished limestone suffered the least damage in freeze-thaw cycles, whereas freeze-thaw resistance was similar in all the granite specimens, regardless of the finish used.Se han estudiado, para su utilización como baldosas de pavimentos, granito (Blanco Rafaela o Granito de Zarzalejo y caliza microcristalina (mármol comercial Gris Pulpis con diferentes acabados. Estos acabados son: pulido, apomazado, abujardado y flameado en ambas rocas y además acabado al ácido y amolado en la caliza. Se han determinado mediante ensayos estandarizados las tres propiedades físicas de mayor interés para el uso de la piedra natural como baldosa en pavimentos de exteriores: resistencia a la flexión bajo carga concentrada, a la abrasión y al deslizamiento. Se han realizado ensayos de durabilidad por ciclos de hielo

  11. Emplacement mechanisms and structural influences of a younger granite intrusion into older wall rocks - a principal study with application to the Goetemar and Uthammar granites. Site-descriptive modelling SDM-Site Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Cruden, Alexander R. (Dept. of Geology, Univ. of Toronto (Canada))

    2008-12-15

    The c. 1.80 Ga old bedrock in the Laxemar-Simpevarp area, which is the focus of the site investigation at Oskarshamn, is dominated by intrusive rocks belonging to the c. 1.86-1.65 Ga Transscandinavian Igneous Belt (TIB). However, the site investigation area is situated in between two c. 1.45 Ga old anorogenic granites, the Goetemar granite in the north and the Uthammar granite in the south. This study evaluates the emplacement mechanism of these intrusions and their structural influence on the older bedrock. Field observations and structural measurements indicate that both the Goetemar and the Uthammar granites are discordant and have not imposed any significant ductile deformation on their wall-rocks. The apparent conformity of geological contacts and fabrics in the wall rocks and the southern margin of the Goetemar granite is coincidental and inherited from the pattern of Svecokarelian deformation of the TIB. However, interpretation of regional aeromagnetic data suggests that the granites occur within a broad, NNE-SSW trending linear belt, pointing to deep seated tectonic control on their generation, ascent and emplacement. Thermochronology indicates that the granites were emplaced at depths between 4 and 8 km into brittle wall rocks. The 3-D shape of the Goetemar and Uthammar plutons has been investigated by 2.75D forward modelling of the residual gravity anomalies due to both granites. Both granites are associated with strong residual gravity anomalies of up to -10 mgal. Constraints on the geometry of the plutons at the surface are provided from surface geology maps and several deep boreholes located on or close to the model profiles. A further variable in the gravity modelling is introduced by either allowing the upper contact of the plutons to assume the most suitable orientation to produce the best fit between the modelled and observed gravity ('unconstrained models') or by forcing the near surface orientation of the contacts to be vertical (&apos

  12. Lithological effects in soil formation and soil slips on weathering-limited slopes underlain by granitic bedrocks in Japan

    OpenAIRE

    Wakatsuki, Tsuyoshi; Matsukura, Yukinori

    2008-01-01

    Soil slips occur every few years due to heavy rains on biotite granite (Gb) and hornblende biotite granite (Ghb) slopes in the Taga Mountains, Ibaraki Prefecture, Japan. The occurrence density of soil slips per unit area is 2.7 times greater in the Gb slopes than that in Ghb slopes. We examined the chemical, mineral, physical, and mechanical properties of two soil profiles on soil-slip scars in these slopes to study the effect of bedrock mineral composition on the density of soil slips. For a...

  13. Simulating experiments for the deformation and microstructures of granite in the central part of the Jiangnan Belt, South China

    Institute of Scientific and Technical Information of China (English)

    舒良树; 孙岩

    1996-01-01

    The simulating experiments of deformation for fresh granite samples from central part of the Jiangnan Belt under a Three Axes Stress Experimental Machine are reported, by which plenty of deformed microstructures from brittle to ductile corresponding to different temperatures and pressures have been obtained. Experiments suggest that additives of fluid (NaCl saturated solution) and setting shear plane for a sample before experiment can lower the temperature and wall pressure and shorten the experimental time from undeformation to mylonitizition. The experimental results provide some important evidence for origin mechanism and formation conditions of natural mylonitic granite.

  14. Correlation between magnetic fabrics, strain and biotite microstructure with increasing mylonitisation in the pretectonic Wyangala Granite, Australia

    Science.gov (United States)

    Lennox, P. G.; de Wall, H.; Durney, D. W.

    2016-04-01

    The Wyangala Granite is a foliated, porphyritic Silurian granite from the Palaeozoic Circum-Pacific type Eastern Lachlan Orogen (ELO) of Australia. It is a paramagnetic ilmenite-bearing, S/marginal I type two-mica- to mainly biotite-granite with different biotite contents and local chlorite alteration. Very highly strained quartz-epidote bands are present. In this contribution, anisotropy of magnetic susceptibility (AMS) is compared with independently measured intensity and 3D style of strain, biotite microstructure and degree of mylonitisation for low-strain granites with weak S-foliations, through medium-strain protomylonitic granites with moderate S- and C-foliations to a high-strain altered granite with a strong single foliation. The samples are further analysed for possible contributions from sample heterogeneity, magmatic flow and 'sub-magmatic' deformation. A good correlation, P‧AMS ~ 1.02 + 0.04 ln P‧(e)Qtz, is obtained between site-average degree of AMS (P‧AMS) in the granite and degree of finite-strain anisotropy (P‧(e)Qtz) from aspect ratios of quartz aggregates in S-foliations in hand specimen and outcrop (P‧AMS 1.03-1.14, P‧(e)Qtz 1.4-19). The magnetic fabric ellipsoids agree with a kinematic regime between neutral and pure oblate predicted by the March model. The observed quartz strains, however, exceed the AMS March strains and are near neutral, plano-linear character. The geological factors that may have contributed to these differences include intra- and inter-crystalline deformation of biotite and bimodality in S and C. Magmatic fabric is not clearly evident in either the AMS or the biotite data. New data for synkinematic oligoclase, low-titanium biotite and low-sodium K-feldspar show that conditions during deformation were approximately transitional greenschist-amphibolite facies: i.e., well below solidus. This agrees with published age data that put the granite emplacement in an extensional, back-arc setting in already deformed

  15. Temporal evolution of granitic magmas in the Luanchuan metallogenic belt, east Qinling Orogen, central China: Implications for Mo metallogenesis

    Science.gov (United States)

    Li, Dong; Han, Jiangwei; Zhang, Shouting; Yan, Changhai; Cao, Huawen; Song, Yaowu

    2015-11-01

    The Luanchuan metallogenic belt, located within the eastern part of the Qinling Orogen, central China, hosts a number of world-class Mo deposits that are closely related to small late Mesozoic granitic plutons. Zircon U-Pb dating of distinct plutons in the Luanchuan metallogenic belt has yielded ages of 153 ± 1, 154 ± 2, 152 ± 2, and 148 ± 1 Ma. Molybdenite Re-Os isotopic compositions of Yuku ore district in the southern part of Luanchuan metallogenic belt has yielded an isochron age of 146 ± 1 Ma, which is consistent with the large-scale mineralization ages in the northern part of the Luanchuan metallogenic belt. A combination of previous studies and new geochronological and isotopic data show a concordant temporal and genetic link between granitic magmatism and Mo mineralization in the Luanchuan metallogenic belt, suggesting that this mineralization episode formed the most extensive Mo mineralization belt in the east Qinling Orogen. Zircon grains from Mo-related granitic plutons show similar trace element distributions. High-precision Multi Collector-Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS) Pb isotope analysis of K-feldspar megacrysts from mineralization-related granites suggest that they were derived from the lower crust. Similarly, the Pb isotopic compositions of pyrite coprecipitated with molybdenite also suggest that the metals were derived form the lower crust, with probably minor mantle contribution. A continuum mineralization model that describes the sourcing of Mo from an evolving granitic magma over successive differentiation events, possibly in separate but connected magma chambers, could explain the remarkable Mo enrichment in the Luanchuan metallogenic belt. The volatile- and Mo-bearing granitic magmas ascended as diapirs from the deep crust, and were emplaced as dikes in the upper crust. Lithological differences between these Mo-bearing granites may relate to different stages in the evolution of individual magmas. Finally, ore

  16. The Early Jurassic Bokan Mountain peralkaline granitic complex (southeastern Alaska): geochemistry, petrogenesis and rare-metal mineralization

    Science.gov (United States)

    Dostal, Jaroslav; Kontak, Daniel J.; Karl, Susan M.

    2014-01-01

    The Early Jurassic (ca. 177 Ma) Bokan Mountain granitic complex, located on southern Prince of Wales Island, southernmost Alaska, cross-cuts Paleozoic igneous and metasedimentary rocks of the Alexander terrane of the North American Cordillera and was emplaced during a rifting event. The complex is a circular body (~3 km in diameter) of peralkaline granitic composition that has a core of arfvedsonite granite surrounded by aegirine granite. All the rock-forming minerals typically record a two-stage growth history and aegirine and arfvedsonite were the last major phases to crystalize from the magma. The Bokan granites and related dikes have SiO2 from 72 to 78 wt. %, high iron (FeO (tot) ~3-4.5 wt. %) and alkali (8-10 wt.%) concentrations with high FeO(tot)/(FeO(tot)+MgO) ratios (typically >0.95) and the molar Al2O3/(Na2O+K2O) ratio Nd values which are indicative of a mantle signature. The parent magma is inferred to be derived from an earlier metasomatized lithospheric mantle by low degrees of partial melting and generated the Bokan granitic melt through extensive fractional crystallization. The Bokan complex hosts significant rare-metal (REE, Y, U, Th, Nb) mineralization that is related to the late-stage crystallization history of the complex which involved the overlap of emplacement of felsic dikes, including pegmatite bodies, and generation of orthomagmatic fluids. The abundances of REE, HFSE, U and Th as well as Pb and Nd isotopic values of the pluton and dikes were modified by orthomagmatic hydrothermal fluids highly enriched in the strongly incompatible trace elements, which also escaped along zones of structural weakness to generate rare-metal mineralization. The latter was deposited in two stages: the first relates to the latest stage of magma emplacement and is associated with felsic dikes that intruded along the faults and shear deformations, whereas the second stage involved ingress of hydrothermal fluids that both remobilized and enriched the initial

  17. Mafic rocks from Erinpura gneiss terrane in the Sirohi region: Possible ocean-floor remnants in the foreland of the Delhi Fold Belt, NW India

    Indian Academy of Sciences (India)

    M K Pandit; H De Wall; H Daxberger; J Just; M Bestmann; K K Sharma

    2011-08-01

    A small isolated mafic body occurs to the south of Sirohi near village Daba within the Neoproterozoic Erinpura Granite in the southern sector of the Proterozoic Delhi Fold Belt in NW India. This mafic body occurs close to a 100 m wide NE–SW trending shear zone (Daba Shear Zone) which overprints the felsic rock fabrics. Further south, a small mafic body near village Kui was also sampled which forms the southern limit of the Phulad Ophiolite Suite which is a 300 km long major NE–SW trending lineament, described as Western Margin Fault. Some of the lithological components of the Daba mafic body show locally preserved magmatic fabric but completely transformed mineralogies under lower amphibolites facies metamorphic conditions where two-stage deformation has been inferred. Magnetic fabric analysis underlines a general correspondence of structural elements in both felsic and mafic lithologies. Binary correlations of Zr with other high field strength elements underline fractionation as the main process in the evolution of Daba and Kui rocks. Geochemical characteristics indicate subalkaline tholeiitic basalt affinity for these mafic rocks. The trace element characteristics, such as enriched LIL elements, high Th, absence of negative Nb anomalies and depletion in compatible elements in Daba samples suggest an enriched mantle source and lower degree of melting. The trace and rare earth element characteristics for Kui (Th anomaly, Nb–Ta trough and less spiked patterns, flat REE trends) indicate derivation from a refractory mantle source affected by fluids derived from subduction. Distinct differences in trace and REE characteristics between Daba and Kui can be interpreted in terms of different stages of ophiolite development.

  18. The Wisconsin magmatic terrane: An Early Proterozoic greenstone-granite terrane formed by plate tectonic processes

    Science.gov (United States)

    Schulz, K. J.; Laberge, G. L.

    1986-01-01

    The Wisconsin magmatic terrane (WMT) is an east trending belt of dominantly volcanic-plutonic complexes of Early Proterozoic age (approx. 1850 m.y.) that lies to the south of the Archean rocks and Early Proterozoic epicratonic sequence (Marquette Range Supergroup) in Michigan. It is separated from the epicratonic Marquette Range Supergroup by the high-angle Niagara fault, is bounded on the south, in central Wisconsin, by Archean gneisses, is truncated on the west by rocks of the Midcontinent rift system, and is intruded on the east by the post-orogenic Wolf river batholith. The overall lithologic, geochemical, metallogenic, metamorphic, and deformational characteristics of the WMT are similar to those observed in recent volcanic arc terranes formed at sites of plate convergence. It is concluded that the WMT represents an evolved oceanic island-arc terrane accreated to the Superior craton in the Early Proterozoic. This conclusion is strengthened by the apparent absence of Archean basement from most of the WMT, and the recent recognition of the passive margin character of the epicratonic Marquette Range Supergroup.

  19. LA-ICPMS Zircon U-Pb Dating for Three Indosinian Granitic Plutons from Central Hunan and Western Guangdong Provinces and Its Petrogenetic Implications

    Institute of Scientific and Technical Information of China (English)

    PENG Bingxia; WANG Yuejun; FAN Weiming; PENG Touping; LIANG Xinquan

    2006-01-01

    The LA-ICPMS zircon U-Pb geochronology of three typically Indosinian granitic plutons yielded weighted mean 206Pb/238U ages of 214.1±5.9 Ma and 210.3±4.7 Ma for the biotite monzonitic granites from the Xiema and Xiangzikou plutons in Hunan Province, and 205.3±1.6 Ma for biotite granite from the Napeng pluton, western Guandong Province, respectively, showing a similar late Indosinian age of crystallization. In combination with other geochronological data from Indosinian granites within the South China Block (SCB), it is proposed that those late Indosinian granites with an age of ~210 Ma and the early Indosinian granites (230-245 Ma) have the similar petrogenesis in identical tectonic setting. The Indosinian granites within the SCB might be the products of anatexis of the thickening crust in a compressive regime. These data provide a further understanding for the temporal and spatial distribution of the Indosinian granites and the dynamic evolution of the SCB.

  20. New perspectives on the origin and emplacement of the Late Jurassic Fanos granite, associated with an intra-oceanic subduction within the Neotethyan Axios-Vardar Ocean

    Science.gov (United States)

    Michail, Maria; Pipera, Kyriaki; Koroneos, Antonios; Kilias, Adamantios; Ntaflos, Theodoros

    2016-10-01

    The Fanos granite occurs in the Peonias subzone of the eastern Axios-Vardar zone in northern Greece. The Fanos granite is Late Jurassic (158 ± 1 Ma) and trends N-S, intruding the Mesozoic back-arc Guevgueli ophiolitic complex. The intrusive character of the eastern contact of the Fanos granite with the host ophiolitic complex is well preserved. In turn the western contact is overprinted by a few meters thick, west- to southwest-directed semi-ductile thrust zone, of Late Jurassic-Early Cretaceous age. The Fanos granite is dominated by the typical, isotropic granitoid fabric, although in some places the initial magmatic flow fabric is preserved. The main deformation recognized in the Fanos granite occurred in brittle regime and expressed by Tertiary thrust faults and Neogene-Quaternary normal to oblique normal faults. The origin as well as the possible tectonic setting of the Fanos granite is the main topics that we address in our study. Rock samples of the Fanos granite along with the adjusted Kotza Dere quartz diorite were analyzed for major and trace elements and for Sr and Nd isotopes (only the quartz diorite). The geochemical data show that the granite has peraluminous characteristics, high-K calc-alkaline affinities, and I-type features. The Sr initial isotopic values of the Fanos granite are rather low (0.7053-0.7056) while for the quartz diorite range from 0.7066 to 0.7068. The Nd initial isotopic values range from 0.51235 to 0.51240 for the granite and from 0.51222 to 0.51233 for the quartz diorite. The source of the granitic melt is interpreted to be meta-basaltic amphibolites. These amphibolites are the metamorphic products of enriched mantle melts that underplated the oceanic lithosphere. Taking into account our and published structural and geochemical data for the Fanos granite along with the tectonic data of the broader Axios-Vardar zone, we suggest that the studied granitic rocks were formed during an intra-oceanic subduction within the Neotethyan

  1. Pluton emplacement in a releasing bend in a transpressive regime: the arrozal granite in the Paraíba do Sul shear belt, Rio de Janeiro.

    Science.gov (United States)

    Nummer, Alexis R; Machado, Rômulo; Dehler, Nolan M

    2007-06-01

    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.

  2. 阿尔泰造山带晚古生代斜长-二长花岗质片麻岩特征及成因研究%STUDY ON THE CHARACTERISTICS AND GENESIS OF PLAGIO-MONZONITIC GRANITIC GNEISS IN ALTAI OROGEN

    Institute of Scientific and Technical Information of China (English)

    郑常青; 徐学纯; 何政伟

    2003-01-01

    阿尔泰造山带存在晚古生代斜长-二长花岗质片麻岩,与中级变质岩系相伴生,发育十分复杂的深层次褶皱或韧性剪切变形.斜长-二长花岗质片麻岩的主体矿物组成为:角闪石、黑云母、长石和石英,含有自形的绿帘石、锆石、磷灰石、环带状构造的褐帘石等副矿物.是一套相当于大陆边缘同构造环境的铝中等饱和的英云闪长质-花岗闪长质-二长花岗质系列的正变质岩系.钕模式年龄在1 400 Ma~1 800 Ma,εNd(t)为正值,反映斜长-二长花岗质片麻岩源于年青地壳,并不是前寒武纪结晶基底,结晶成岩作用和变质变形作用几乎是同时发生的,年龄为355 Ma±5 Ma.

  3. Timing of granitic magmatism in the northern Borborema Province, Brazil: a U Pb study of granitoids from the Alto Pajeú Terrain

    Science.gov (United States)

    Bastos Leite, P. R.; Bertrand, J.-M.; de Lima, E. S.; Leterrier, J.

    2000-11-01

    The Alto Pajeú Terrain (APT) is a SW-NE trending fold belt in the Neoproterozoic Borborema Province (NE Brazil), formed by metasedimentary sequences interlayered with metavolcanosedimentary units, both intruded by granitic rocks of different compositions and ages. The tectonic evolution of the APT involves Mesoproterozoic and Neoproterozoic transtensional and contractional tectonic events. In this study, we present U-Pb zircon ages of five granitoids selected according to a generally accepted relative chronology: (a) the Tuparetama granite and Tuparetama migmatitic granite with low angle gneissic foliation represent syn-tangential rocks presumably related to a Transamazonian event; (b) the Amparo granite with high angle gneissic foliation related to the Brazilian/Pan-African event; and (c) the Tabira and Jabitacá post-strike-slip granites. The results obtained do not confirm the generally accepted chronology of events. Granites previously classified in different groups (Tuparetama, Amparo, and Jabitacá) belong to the same orogenic cycle (Brazilian). Large batholiths, previously suspected to have been emplaced after the strike-slip deformation, represent older crustal remnants within them. In each case they consist of particular rock types — an alkaline high-temperature granite (Tabira) and a 'granulite' (Tuparetama migmatitic granite). These older ages imply that pre-Brazilian crust-forming events such as the Transamazonian Orogeny (Tuparetama migmatitic granite estimated at ca. 2050 Ma) and Cariris Velhos event (Tabira granite at ca. 972 Ma) occurred in the APT, and their records survived the intense recycling which characterizes the Brazilian/Pan-African orogeny.

  4. A radiological study of some ornamental stones: the bluish granites from Extremadura (Spain)

    Science.gov (United States)

    Pereira, D.; Neves, L.; Pereira, A.; Peinado, M.; Blanco, J. A.; Tejado, J. J.

    2012-02-01

    In the area of Trujillo (Extremadura, Spain) we have found a variety of striking bluish and secondary yellow granites outcropping within the Plasenzuela pluton. They are all quarried under different names and are characterized by leucocratic minerals in which a bluish phosphate is dispersed throughout the rock. Their physical and mechanical properties make these granites a perfect option for most applications as ornamental rocks. Within the pluton the radiological background is fairly homogeneous, with no significant differences between the gamma ray fluxes of the different facies. U (6.4 ± 0.51 ppm), Th (2.9 ± 0.47 ppm) and K2O (4.32 ± 0.26%) contents determined in the laboratory by gamma-ray spectrometry from representative samples are in good accordance with fast in situ measurements carried out with the same technique and also with conventional chemical analysis. Estimated activities for K-40, Ra-226 and Th-232 were, on average, 1022 ± 36 Bq kg-1, 84 ± 9 Bq kg-1 and 6.8 ± 1.6 Bq kg-1. On the basis of these results, the I index of EU technical document 112 was determined, with an average result of 0.66 ± 0.03. This suggests that the rock can be used with no restrictions for all types of construction purposes. Striking differences were observed between the blue facies and the yellow facies in radon exhalation tests from crushed material (0.03 Bq kg-1 vs. 0.20 Bq kg-1). Since both granites have similar uranium contents (6.3 ppm and 6.5 ppm, respectively), these results can probably be explained in terms of important differences in the mineralogical distribution of this chemical element, radon emanation being enhanced in the yellow facies. However, due to the ordinary use as ornamental stone, the yellow facies does not present a radiological risk in terms of excess effective dose due to internal exposure to radon.

  5. External gamma-ray dose rate and radon concentration in indoor environments covered with Brazilian granites

    Energy Technology Data Exchange (ETDEWEB)

    Anjos, R.M., E-mail: meigikos@if.uff.br [LARA - Laboratorio de Radioecologia, Instituto de Fisica, Universidade Federal Fluminense, Av. Gal Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (Brazil); Juri Ayub, J. [LARA - Laboratorio de Radioecologia, Instituto de Fisica, Universidade Federal Fluminense, Av. Gal Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (Brazil); GEA-Instituto de Matematica Aplicada San Luis (IMASL), Universidad Nacional de San Luis, Consejo Nacional de Investigaciones Cientificas y Tecnicas, CCT-San Luis, Ej. de los Andes 950, D5700HHW San Luis (Argentina); Cid, A.S.; Cardoso, R.; Lacerda, T. [LARA - Laboratorio de Radioecologia, Instituto de Fisica, Universidade Federal Fluminense, Av. Gal Milton Tavares de Souza, s/no, Gragoata, 24210-340 Niteroi, RJ (Brazil)

    2011-11-15

    Health hazard from natural radioactivity in Brazilian granites, covering the walls and floor in a typical dwelling room, was assessed by indirect methods to predict external gamma-ray dose rates and radon concentrations. The gamma-ray dose rate was estimated by a Monte Carlo simulation method and validated by in-situ measurements with a NaI spectrometer. Activity concentrations of {sup 232}Th, {sup 226}Ra, and {sup 40}K in an extensive selection of Brazilian commercial granite samples measured by using gamma-ray spectrometry were found to be 4.5-450 Bq kg{sup -1}, 4.9-160 Bq kg{sup -1} and 190-2029 Bq kg{sup -1}, respectively. The maximum external gamma-ray dose rate from floor and walls covered with the Brazilian granites in the typical dwelling room (5.0 m x 4.0 m area, 2.8 m height) was found to be 120 nGy h{sup -1}, which is comparable with the average worldwide exposure to external terrestrial radiation of 80 nGy h{sup -1} due to natural sources, proposed by United Nations Scientific Committee on the Effects of Atomic Radiation. Radon concentrations in the room were also estimated by a simple mass balance equation and exhalation rates calculated from the measured values of {sup 226}Ra concentrations and the material properties. The results showed that the radon concentration in the room ventilated adequately (0.5 h{sup -1}) will be lower than 100 Bq m{sup -3}, value recommended as a reference level by the World Health Organization. - Highlights: > We used indirect methods to predict external gamma dose rate and radon concentration. > The gamma-ray dose rate was estimated by a Monte Carlo simulation method. > The results were validated by in-situ measurements with a NaI spectrometer. > Radon concentrations in the room were estimated by a simple mass balance equation. > Radon concentration in the room ventilated adequately will be lower than 100 Bq m{sup -3}.

  6. A radiological study of some ornamental stones: the bluish granites from Extremadura (Spain

    Directory of Open Access Journals (Sweden)

    D. Pereira

    2012-02-01

    Full Text Available In the area of Trujillo (Extremadura, Spain we have found a variety of striking bluish and secondary yellow granites outcropping within the Plasenzuela pluton. They are all quarried under different names and are characterized by leucocratic minerals in which a bluish phosphate is dispersed throughout the rock. Their physical and mechanical properties make these granites a perfect option for most applications as ornamental rocks. Within the pluton the radiological background is fairly homogeneous, with no significant differences between the gamma ray fluxes of the different facies. U (6.4 ± 0.51 ppm, Th (2.9 ± 0.47 ppm and K2O (4.32 ± 0.26% contents determined in the laboratory by gamma-ray spectrometry from representative samples are in good accordance with fast in situ measurements carried out with the same technique and also with conventional chemical analysis. Estimated activities for K-40, Ra-226 and Th-232 were, on average, 1022 ± 36 Bq kg−1, 84 ± 9 Bq kg−1 and 6.8 ± 1.6 Bq kg−1. On the basis of these results, the I index of EU technical document 112 was determined, with an average result of 0.66 ± 0.03. This suggests that the rock can be used with no restrictions for all types of construction purposes. Striking differences were observed between the blue facies and the yellow facies in radon exhalation tests from crushed material (0.03 Bq kg−1 vs. 0.20 Bq kg−1. Since both granites have similar uranium contents (6.3 ppm and 6.5 ppm, respectively, these results can probably be explained in terms of important differences in the mineralogical distribution of this chemical element, radon emanation being enhanced in the yellow facies. However, due to the ordinary use as ornamental stone, the yellow facies does not present a radiological risk in terms of excess effective dose due to internal exposure to radon.

  7. Microfracturing and fluid mixing in granites: W (Sn) ore deposition at Vaulry (NW French Massif Central)

    Science.gov (United States)

    Vallance, Jean; Cathelineau, Michel; Marignac, Christian; Boiron, Marie-Christine; Fourcade, Serge; Martineau, François; Fabre, Cécile

    2001-07-01

    The Vaulry W-(Sn) mineralisation, located at the eastern boundary of the Blond rare metal leucogranite, is contained in a set of subvertical quartz veins, locally with muscovite and minor quartz selvages. The sequence of deposition was: (1) milky quartz, predominantly as fracture filling, generally affected by subsequent ductile deformation; (2) hyaline quartz-wolframite-cassiterite; (3) minor sulphides. Other sets of quartz veinlets, although generally barren are observed in the Blond massif. Fluid migration at the microscopic scale within the granite and in the vicinity of quartz fractures was constrained by studying the geometry of fluid-inclusion planes and fluid-inclusion chemistry in and outside the mineralised area. Three major sets of subvertical fluid-inclusion planes are recognised: a N050°-060°E set, mostly developed in the veins and in the immediate vicinity, a N110°-130°E set, regionally developed in the granite and a N140-160°E set of local extent. As a whole, the density of FIP decreases from the mineralised zones toward the barren part of the pluton, except for the N140°-160°E set. These are locally abundant around quartz veinlets with similar orientations that form a broad "N-S" band near the Blond locality. Mineralising fluids observed as primary inclusions in cassiterite and in undeformed hyaline quartz are mostly aqueous, with moderate salinity and a minor volatile component, at variance with many other W-(Sn) deposits in the Variscan belt. Ore deposition occurred around 315°C, at an estimated depth of 5.5 km, under hydrostatic to slightly suprahydrostatic pressures. It resulted from fluid mixing, in the central part of a large hydrothermal system, between two end-members: (i) a hot (425-430°C) moderately saline fluid, that contained a diluted volatile component and, although Na-dominated, minor amounts of Li and Ca. The estimated δ18O indicates that this fluid was completely equilibrated with the tectono-magmatic pile (pseudo

  8. Deterioration of the granitic stones of main front of the Vila Real Cathedral (N of Portugal

    Directory of Open Access Journals (Sweden)

    Gomes, M. E. P.

    2009-12-01

    Full Text Available The cathedral of Vila Real (North of Portugal is located in the city centre and at least four regional two-mica granites were used in its construction. A petrographic study of these granites concluded that the stones had different degrees of alterations. The identification of some physical properties of the granites –open porosity, real and apparent density, free water absorption, porometry and capillary transmission– confirms their susceptibility to degrees of weathering. A recent cleaning intervention was made and several types of deterioration were visible in the monument‚s stones, namely: granular disintegration, some thin black layers, plates, flakes and black crusts, especially in the main front exposed to SW. Granular disintegration is the most important deterioration process and is responsible for the loss of material in the most-affected stones; it is also related to the presence of small amounts of highly soluble salts such as halite and nitrates and to solar exposure.La Catedral de Vila Real (Norte de Portugal se encuentra en el centro de la ciudad y se han utilizado, al menos, cuatro granitos de dos micas para su construcción extraídos de sus alrededores. El estudio petrográfico de estos granitos pone de manifiesto que poseen un diferente grado de alteración. La determinación de algunas propiedades físicas de los granitos –porosidad abierta, densidad aparente y real, absorción libre de agua, porometría y capilaridad– confirman los distintos grados de alteración. La catedral ha sufrido una reciente limpieza y sobre las piedras de la Catedral se observan distintas formas de alteración, sobre todo desagregación granular (arenización, escasas pátinas finas negras, desplacaciones, escamas y costras negras, especialmente en la fachada principal, expuesta al SW. El fenómeno de la desagregación granular es el más importante y es el responsable de de la pérdida de material en las piedras más afectadas. Su g

  9. The main features of the interaction of mantle magmas with granulite complexes of the lower crust and their relationship with granitic melts (exemplified by the Early Caledonides of the West Baikal Region, Russia)

    Science.gov (United States)

    Vladimirov, Alexandr; Khromykh, Sergei; Mekhonoshin, Alexei; Volkova, Nina; Travin, Alexei; Mikheev, Evgeny; Vladimirova, Anna

    2016-04-01

    Granulite complexes occurring in the Early Caledonian southern folded framing of the Siberian Craton are deeply eroded fragments of the Vendian-Early Paleozoic accretionary prism, which is an indicator of the early stages of the Paleo-Asian Ocean (Gladkochub et al., 2010). The main feature of the granulite complexes is a wide development of gabbro-pyroxenites composing tectonic plates, synmetamorphic intrusive bodies, and numerous disintegrated fragments (boudins and enclaves), immersed in a metamorphic matrix. The volume of basites reaches 5-10 %, which allows us to consider mantle magmatism as a heat source for the granulite metamorphism. The most studied polygon is Chernorud granulite zone, which is a part of the Olkhon metamorphic terrane, West Baikal Region. Just this polygon was used for considering the problems of interaction of mantle magmas with lower crust granulite complexes and their relationship with granitic melts. The Chernorud Zone is a typical example of the accretionary prism with a predominance of metabasalts (70-80 %), subordinate amounts of marbles, quartzites and metapelites that have been subjected to granulite facies metamorphism and viscoelastic flow of rock masses. Study of two-pyroxene granulites (metabasalts) and garnet-sillimanite gneisses (metapelites) allows us to estimate P-T metamorphic conditions (P = 7.7-8.6 kbar, T = 770-820°C) and their U-Pb metamorphic age (530-500 Ma). Metabasalts correspond in their geochemistry to the island-arc tholeiitic series (Volkova et al., 2010; Gladkochub et al., 2010). Sin-metamorphic gabbro-pyroxenites formed in two stages: 1) Chernorud complex - tectonic slices and body's exhumed from deep earth crust levels (10-12 kb) and composed of arc tholeiitic series rocks (age T ≥ 500 Ma); 2) Ulan-Khargana complex - supply magmatic canals and fragmented tabular intrusions. This rocks composition corresponds to subalkaline petrochemical series (OIB) and U/Pb age is equal to 485±10 Ma (Travin et al., 2009

  10. Decrepitometry of fluid inclusions in quartz from the guadalcazar granite of Mexico; principles and application to mineral exploration

    Science.gov (United States)

    Chryssoulis, S. L.; Rankin, A. H.

    1988-01-01

    A simple acoustic decrepitometric method, with which samples of granite quartz are heated to about 600°C while the number of decrepitations are counted, has been developed to study rock samples derived from the mineralized guadalcazar granite in Mexico. Decrepitation temperatures for individual inclusions have also been determined by observing the point at which they rupture upon heating using a microscope heating stage. Decrepitation temperatures of individual fluid inclusions in granite quartz are influenced by a variety of factors notably size, shape, composition, homogenization temperature and proximity to the surface. There is a positive correlation between total decrepitation activity and fluid inclusion abundances (determined optically using point counting methods). Decrepitographs show a period of low intensity decrepitation activity below 390°C followed by a period of intensive decrepitation up to 570°C. The onset of massive decrepitation at around 390°C is constant for all samples, but variations in decrepitation activity often occur between mineralized and barren samples. These variations reflect complex differences in the fluid inclusion populations, but illustrate the potential for applying simple audio-decrepitometry as an aid to mineral exploration in granite terrains.

  11. The Behaviour of Rare—Earth Elements(REE) During Weathering of Granites in Southern Guangxi,China

    Institute of Scientific and Technical Information of China (English)

    郑作平; 林传仙

    1996-01-01

    The behaviour of the rare-earth elements(REE)during the weathering of granites was studied in southern Guangxi,China.Based on the study of the weathering profiles,the soil,weathered and sub-weatereb zones are identified with different REE geochemical behaviours throug the weathering profiles of granite.The Ce anomalies of the weathering profiles cover a large range of values with most falling between 1.02 and 1.43in the soil zone and 0.16and 0.40in the weathered and sub-weathered zones.Light rare-earth elements(LREE) and heavy rare-earth elements(HREE)are enriched to varying degree in the weathering profiles as compared to host granites.In the soil zone,more HREEs are leached than LREEs,and HREEs are more enriched than LREE in the weathered and sub-weathered zones.It is considered that infiltration and adsorption on clays are two processes controlling the enrichment and formation of REE deposits in the weathering profiles of granite.

  12. Technical support for GEIS: radioactive waste isolation in geologic formations. Volume 10. Repository preconceptual design studies: granite

    Energy Technology Data Exchange (ETDEWEB)

    1978-04-01

    This volume, Volume 10 ''Repository Preconceptual Design Studies: Granite,'' is one of a 23-volume series, ''Technical Support for GEIS: Radioactive Waste Isolation in Geologic Formations,'' Y/OWI/TM-36, which supplements the ''Contribution to Draft Generic Environmental Impact Statement on Commercial Waste Management: Radioactive Waste Isolation in Geologic Formations,'' Y/OWI/TM-44. The series provides a more complete technical basis for the preconceptual designs, resource requirements, and environmental source terms associated with isolating commercial LWR wastes in underground repositories in salt, granite, shale and basalt. Wastes are considered from three fuel cycles: uranium and plutonium recycling, no recycling of spent fuel and uranium-only recycling. This document describes a preconceptual design for a nuclear waste storage facility in granite. The facility design consists of several chambers excavated deep within a geologic formation together with access shafts and supportive surface structures. The facility design provides for: receiving and unloading waste containers; lowering them down shafts to the mine level; transporting them to the proper storage area, and emplacing them in mined storage rooms. Drawings of the facility design are contained in TM-36/11, ''Drawings for Repository Preconceptual Design Studies: Granite.''

  13. Effectiveness and harmful effects of removal sulphated black crust from granite using Nd:YAG nanosecond pulsed laser

    Energy Technology Data Exchange (ETDEWEB)

    Pozo, S. [Dpto. Ingeniería de los Recursos Naturales y Medio Ambiente, ETSI Minas, University of Vigo, 36310 (Spain); Barreiro, P. [Dpto. Física Aplicada, E.T.S.I. Industriales, University of Vigo, 36310 (Spain); Rivas, T. [Dpto. Ingeniería de los Recursos Naturales y Medio Ambiente, ETSI Minas, University of Vigo, 36310 (Spain); González, P. [Dpto. Física Aplicada, E.T.S.I. Industriales, University of Vigo, 36310 (Spain); Fiorucci, M.P. [Centro de Investigacións Tecnolóxicas (CIT), University of A Coruña, 15403, Ferrol (Spain)

    2014-05-01

    Sulphated black crust is a common form of deterioration affecting stone used in monuments, usually occurs in contaminated atmospheres or urban environments. Its origin and cleaning have been studied extensively, for decades, in the case of carbonate rocks. Recent studies show that this form of alteration also affects granites. Scientific research on laser removal effectiveness of gypsum-rich black crust on granites needs to be scientifically addressed considering the inexistent references. This paper assesses the removal by laser of sulphate-rich black crusts on granite using the different harmonics of a Nd:YAG nanosecond pulsed laser (266 nm, 355 nm, 532 nm and 1064 nm). Effectiveness was evaluated using Scanning Electron Microscopy with Energy Dispersive X-ray Spectrometry (SEM–EDS), X-Ray Diffraction (XRD) and Attenuated Total Reflection-Fourier Infrared Transform Spectroscopy (ATR-FTIR). We also evaluated the effect of the radiation on granite-forming minerals and on the colour of the stone using Scanning Electron Microscopy and spectrophotometry colour measurements respectively. SEM–EDS, XRD and ATR-FTIR analyses show that the higher the wavelength, the more efficient the cleaning, so samples cleaned using 1064 nm pulsed laser recovered its original colour. Nevertheless, the Nd:YAG laser did not completely eliminate the crust, and gypsum crystals remaining on the rock surface are observed, even at the most effective wavelength.

  14. Experiments of Brittle-Plastic Transition and Instability Modes of Juyongguan Granite at Different Temperatures and Pressures

    Institute of Scientific and Technical Information of China (English)

    Zhou Yongsheng; Jiang Haikun; He Changrong

    2003-01-01

    Three groups of experiments on brittle-plastic transition and instability modes of granite wereperformed in a triaxial vessel with solid pressure medium at high temperature and highpressure. The results of experiments show that brittle faulting is the major failure mode attemperature < 300℃, but crystal-plastic deformation is dominate at temperature > 800℃, andthere is a transition with increasing temperature from semi-brittle faulting to cataclnstic flowand semi-brittle flow at temperatures of 300 ~ 800℃. So, temperature is the most influentialfactor in brittle-plastic transition of granite and confining pressure is the second factor. Theresults also show that progressive failure of granite occurs at lower pressure or hightemperature where there is crystal plasticity, and sudden instability occurs at room temperatureand high pressure ( > 300MPa) or high temperature and great pressure(550℃600MPa ~ 650℃700MPa), and a broad regime of quasi-sudden instability exists between the T-P condition ofprogressive failure and sudden instability. So, instability modes of granite dependsimnitaneonsly on the pressure and temperature.

  15. The Early Jurassic Bokan Mountain peralkaline granitic complex (southeastern Alaska): Geochemistry, petrogenesis and rare-metal mineralization

    Science.gov (United States)

    Dostal, Jaroslav; Kontak, Daniel J.; Karl, Susan M.

    2014-08-01

    The Early Jurassic (ca. 177 Ma) Bokan Mountain granitic complex, located on southern Prince of Wales Island, southernmost Alaska, cross-cuts Paleozoic igneous and metasedimentary rocks of the Alexander terrane of the North American Cordillera and was emplaced during a rifting event. The complex is a circular body (~ 3 km in diameter) of peralkaline granitic composition that has a core of arfvedsonite granite surrounded by aegirine granite. All the rock-forming minerals typically record a two-stage growth history and aegirine and arfvedsonite were the last major phases to crystallize from the magma. The Bokan granites and related dikes have SiO2 from 72 to 78 wt.%, high iron (FeO (tot) ~ 3-4.5 wt.%) and alkali (8-10 wt.%) concentrations with high FeO(tot)/(FeO(tot) + MgO) ratios (typically > 0.95) and the molar Al2O3/(Na2O + K2O) ratio metal (REE, Y, U, Th, Nb) mineralization that is related to the late-stage crystallization history of the complex which involved the overlap of emplacement of felsic dikes, including pegmatite bodies, and generation of orthomagmatic fluids. The abundances of REE, HFSE, U and Th as well as Pb and Nd isotopic values of the pluton and dikes were modified by orthomagmatic hydrothermal fluids highly enriched in the strongly incompatible trace elements, which also escaped along zones of structural weakness to generate rare-metal mineralization. The latter was deposited in two stages: the first relates to the latest stage of magma emplacement and is associated with felsic dikes that intruded along the faults and shear deformations, whereas the second stage involved ingress of hydrothermal fluids that both remobilized and enriched the initial magmatic mineralization. Mineralization is mostly composed of “new” minerals. Fluorine complexing played a role during the transportation of REE and HFSE in hydrothermal fluids and oxygen isotopes in the granites and quartz veins negate the significant incursion of an external fluid and support a

  16. The transition between shortening and extensional regimes in central Mexico recorded in the tourmaline veins of the Comanja Granite

    Science.gov (United States)

    Angeles-Moreno, Edgar; Nieto-Samaniego, Angel Francisco; Ruiz-González, Francisco Jesús; Levresse, Gilles; Alaniz-Alvarez, Susana Alicia; Olmos Moya, María de Jesús Paulina; Xu, Shunshan; Miranda-Avilés, Raúl

    2017-01-01

    In central Mexico, there is a major angular unconformity separating two lithologic groups. Below the unconformity, the rocks display shortening deformation structures produced by the Laramide orogeny, overprinting those shortening structures there are normal faults related to the Cenozoic Basin and Range tectonics. Above the unconformity, the rocks are affected only by the Basin and Range tectonics, displaying mainly normal faults and in minor amount, lateral-oblique faults. We analyzed the Comanja Granite in the Sierra de Guanajuato, it is a large pluton that contains tourmaline veins. The Granite lacks of the shortening structures that pervasively affected the Mesozoic host-rocks; for this reason, we infer that the granite was formed after the main shortening event. We determined that the emplacement of the Comanja Granite took place between 51.0 ± 0.3 Ma and 49.5 ± 0.8 Ma, and that the tourmaline veins of the granite were formed at ∼51.0 Ma. At the microscopic scale, the tourmaline veins contain three kinds of tourmaline, called T1, T2, and T3, according to the order of their formation. The T1 tourmalines are brown colored and appear affected by brittle-ductile (D1) and brittle (D2) deformations. The cataclasites formed during D2 overprinted the brittle-ductile structures of D1, indicating the transition from deeper to shallower levels. In contrast, T2 and T3 tourmalines were not involved in those deformations. At the outcrop scale, we identified two slickensides in the tourmaline veins. The older, related to D1, is strike-slip with a small thrust component and the younger, related to D2, is normal with oblique components. The T1 tourmalines (which are deformed) were formed before the lateral-thrust faulting, whereas the T2 and T3 tourmalines, which are not deformed, were deposited after the faulting occurred in the veins. Our interpretation is that T1 tourmalines were deposited in the later phases of the Comanja Granite emplacement, with the minimum

  17. Strong climate and tectonic control on plagioclase weathering in granitic terrain

    Science.gov (United States)

    Rasmussen, C.; Brantley, S.; Richter, D.D.B.; Blum, A.; Dixon, J.; White, A.F.

    2011-01-01

    Investigations to understand linkages among climate, erosion and weathering are central to quantifying landscape evolution. We approach these linkages through synthesis of regolith data for granitic terrain compiled with respect to climate, geochemistry, and denudation rates for low sloping upland profiles. Focusing on Na as a proxy for plagioclase weathering, we quantified regolith Na depletion, Na mass loss, and the relative partitioning of denudation to physical and chemical contributions. The depth and magnitude of regolith Na depletion increased continuously with increasing water availability, except for locations with mean annual temperature reaction enthalpy for albite. Water availability is suggested as the dominant factor limiting rate kinetics in the water-limited systems. Together, these data demonstrate marked transitions and nonlinearity in how climate and tectonics correlate to plagioclase chemical weathering and Na mass loss. ?? 2010 Elsevier B.V.

  18. A pedogeomorphic comparison of two granitic areas in the Kruger National Park

    Directory of Open Access Journals (Sweden)

    M.C. Munnik

    1990-09-01

    Full Text Available Two climatically different areas on granitic materials near Phalaborwa and Pretoriuskop in the Kruger National Park were pedogeomorphologically compared and the influence of climatic factors on soil and hillslope development in the two areas was assessed. The examination of 18 hillslopes and their soils showed that while the two areas have many broad similarities, there are specific soil and hillslope differences between them with the result that each area has its own distinctive pedogeomorphic character. While comparable parent material, situation and age appear to be responsible for similarities between the areas, the differences could in most cases be accounted for by the disparity in rainfall between the two areas. It was, however, also necessary to note the role of past (and possibly current cycles of erosion and deposition in the creation of the two types of simple hillslopes occurring in the areas.

  19. Particle size distribution and particle size-related crystalline silica content in granite quarry dust.

    Science.gov (United States)

    Sirianni, Greg; Hosgood, Howard Dean; Slade, Martin D; Borak, Jonathan

    2008-05-01

    Previous studies indicate that the relationship between empirically derived particle counts, particle mass determinations, and particle size-related silica content are not constant within mines or across mine work tasks. To better understand the variability of particle size distributions and variations in silica content by particle size in a granite quarry, exposure surveys were conducted with side-by-side arrays of four closed face cassettes, four cyclones, four personal environmental monitors, and a real-time particle counter. In general, the proportion of silica increased as collected particulate size increased, but samples varied in an inconstant way. Significant differences in particle size distributions were seen depending on the extent of ventilation and the nature and activity of work performed. Such variability raises concerns about the adequacy of silica exposure assessments based on only limited numbers of samples or short-term samples.

  20. Radon emissions related to the granitic Precambrian shield in southern Brazil.

    Science.gov (United States)

    Fianco, Ana C B; Roisenberg, Ari; Bonotto, Daniel M

    2013-01-01

    The equivalent uranium (eU) activity concentration was analysed in selected granite samples at several sites in Porto Alegre, Southern Brazil, to obtain information on the radon ((222)Rn) generation by the aquifer rock matrices. Radon analyses of ground water and soil samples were also performed. Several samples exhibited a dissolved (222)Rn activity concentration exceeding the World Health Organization maximum limit of 100 Bq l(-1). The dissolved radon content in ground waters from the Fractured Precambrian Aquifer System exhibited a direct significant correlation with the eU in the rock matrices, which is a typical result of water-rock interactions. Variation in the soil's porosity was confirmed as an important factor for (222)Rn release, as expected, due to its gaseous nature. Thus, although the calcic-alkaline to alkaline Precambrian granitoid rocks of the study area are important reservoirs for underground resources, they can release high amounts of radon gas into the liquid phase.

  1. Influence of granitic aggregates from Northeast Brazil on the alkali-aggregate reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gomes Neto, David de Paiva; Santana, Rodrigo Soares de; Barreto, Ledjane Silva, E-mail: pvgomes@uol.com.br [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Ciencias dos Materiais e Engenharia; Conceicao, Herbert; Lisboa, Vinicios Anselmo Carvalho [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Geologia

    2014-08-15

    The alkali-aggregate reaction (AAR) in concrete structures is a problem that has concerned engineers and researchers for decades. This reaction occurs when silicates in the aggregates react with the alkalis, forming an expanded gel that can cause cracks in the concrete and reduce its lifespan. The aim of this study was to characterize three coarse granitic aggregates employed in concrete production in northeastern Brazil, correlating petrographic analysis with the kinetics of silica dissolution and the evolution of expansions in mortar bars, assisted by SEM/EDS, XRD, and EDX. The presence of grains showing recrystallization into individual microcrystalline quartz subgrains was associated with faster dissolution of silica and greater expansion in mortar bars. Aggregates showing substantial deformation, such as stretched grains of quartz with strong undulatory extinction, experienced slower dissolution, with reaction and expansion occurring over longer periods that could not be detected using accelerated tests with mortar bars. (author)

  2. Sorption of cesium, radium, protactinium, uranium, neptunium and plutonium on rapakivi granite

    Energy Technology Data Exchange (ETDEWEB)

    Huitti, T.; Hakanen, M. [Helsinki Univ. (Finland). Lab. of Radiochemistry; Lindberg, A. [Geological Survey of Finland, Espoo (Finland)

    1996-12-01

    The aim of the study is to determine the sorption of cesium, radium, protactinium, uranium, neptunium and plutonium on rapakivi granite in the brackish groundwater of Haestholmen (site of the Loviisa-1, Loviisa-2 reactors). The studies were carried out under aerobic (Cs, Ra, Pa, U, Np, Pu) and anaerobic (Np, Pa, Pu, Tc) laboratory conditions. The cation exchange capasity was determined for the rock and the diffusion of tritiated water in the rocks of different degree of alteration. The sorption and diffusion properties of the rocks are briefly compared with those of host rocks at other sites under investigation by the Finnish company Posiva Oy for the final disposal of spent fuel. (29 refs.).

  3. Influence of the properties of granite and sandstone in the desalination process by electrokinetic technique

    DEFF Research Database (Denmark)

    Feijoo, J.; Ottosen, Lisbeth M.; Pozo-Antonio, J.S.

    2015-01-01

    such as sand disaggregation and superficial detachments. These problems can be solved by conservation technologies, which are aimed to decrease the salt concentration in rocks (desalination).The present study aimed to investigate the efficiency of electrokinetic techniques for desalination of two different......) achieved in both stones.From the results obtained, it was possible to find those inherent factors to each stone which could have an influence on the efficacy of the treatment. With this technique it was possible to reduce the salt concentration in the granite almost to 100%. However, in the sandstone...... samples the decreases were not equally high, mainly at the intermediate levels where slight enrichments were observed. The results indicate that although the used technique is efficient for salt removal regardless of the porosimetric distribution of the rock, the better interconnection between the pores...

  4. Measuring the initial earth pressure of granite using hydraulic fracturing test; Goseong and Yuseong areas

    Energy Technology Data Exchange (ETDEWEB)

    Park, Byoung Yoon; Bae, Dae Seok; Kim, Chun Soo; Kim, Kyung Su; Koh, Young Kwon; Won, Kyung Sik [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2002-02-01

    This report provides the initial earth pressure of granitic rocks obtained from Deep Core Drilling Program which is carried out as part of the assessment of deep geological environmental condition. These data are obtained by hydraulic fracturing test in three boreholes drilled up to 350{approx}500 m depth at the Yuseong and Goseong sites. These sites were selected based on the result of preliminary site evaluation study. The boreholes are NX-size (76 mm) and vertical. The procedure of hydraulic fracturing test is as follows: - Selecting the testing positions by preliminary investigation using BHTV logging. - Performing the hydraulic fracturing test at each selected position with depth.- Estimating the shut-in pressure by the bilinear pressure-decay-rate method. - Estimating the fracture reopening pressure from the pressure-time curves.- Estimating the horizontal principal stresses and the direction of principal stresses. 65 refs., 39 figs., 12 tabs. (Author)

  5. Characterization of granite and limestone powders for use as fillers in bituminous mastics dosage

    Directory of Open Access Journals (Sweden)

    BRENO BARRA

    2014-06-01

    Full Text Available This paper discusses the importance of studies on materials known as fillers from different mineral origins, used in asphalt mixes, specifically in the formulation of mastics. The research was carried out on samples of limestone and granite rock filler and asphalt binder (50/70. The samples were evaluated through semiquantitative chemical analyses by X-ray fluorescence, granulometry by low angle laser emission, scanning electron microscopy, softening point tests, penetration tests, and aggregate-asphalt binder and aggregate-mastic adhesion tests. The results highlighted convergent trends, indicating that the active behavior of the fillers in the mastic formulation is not related to the size of the particles, but rather to their form, surface texture, specific surface area and mineralogical nature, allowing the filler activity concept to be divided into two components: physical (hardening and chemical (adhesion.

  6. Large zenith angle observations with the high-resolution GRANITE III camera

    CERN Document Server

    Petry, D

    2001-01-01

    The GRANITE III camera of the Whipple Cherenkov Telescope at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona (2300 m a.s.l.) has the highest angular resolution of all cameras used on this telescope so far. The central region of the camera has 379 pixels with an individual angular diameter of 0.12 degrees. This makes the instrument especially suitable for observations of gamma-induced air-showers at large zenith angles since the increase in average distance to the shower maximum leads to smaller shower images in the focal plane of the telescope. We examine the performance of the telescope for observations of gamma-induced air-showers at zenith angles up to 63 degrees based on observations of Mkn 421 and using Monte Carlo Simulations. An improvement to the standard data analysis is suggested.

  7. K-Ca and Rb-Sr Dating of Lunar Granite 14321 Revisited

    Science.gov (United States)

    Simon, Justin I.; Shih, C.-Y.; Nyquist, L. E.

    2011-01-01

    K-Ca and Rb-Sr age determinations were made for a bulk feldspar-rich portion of an Apollo rock fragment of the pristine lunar granite clast (14321,1062), an acid-leached split of the sample, and the leachate. K-Ca and Rb-Sr data were also obtained for a whole rock sample of Apollo ferroan anorthosite (FAN, 15415). The recent detection [1] of widespread intermediate composition plagioclase indicates that the generation of a diversity of evolved lunar magmas maybe more common and therefore more important to our understanding of crust formation than previously believed. Our new data strengthen the K-Ca and Rb-Sr internal isochrons of the well-studied Apollo sample 14321 [2], which along with a renewed effort to study evolved lunar magmas will provide an improved understanding of the petrogenetic history of evolved rocks on the Moon.

  8. A-type and I-type granitoids and mylonitic granites of Hassan Salaran area of SE Saqqez, Kurdistan, Iran

    Science.gov (United States)

    Abdullah, Fakhraddin Mohammad; Saeed Ahmad, Sheler

    2014-05-01

    The Hassan Salarn area is located 20km to southeast of Saqqez city in Kurdistan Province, western Iran. In this area there are two distinct granitic rock suites consisting A-type and I-type granites and also mylonitic granites. These A-type and I-type granites have various petrological and geochemical characteristics. They also have different origins and petrogenesis. A-type granitoids comprise alkali feldspar granite, syenogranite and quartz alkali feldspar syenite, whereas I-type granitoids are composed of monzogranite, granodiorite and tonalite. Geochemically, A-type granitoids are peralkaline and acmite-normative but I-type granitoids are subalkaline (calc-alkaline), metaluminous and diopside-normative. A-type granitoids are also ferroan alkali and ferroan alkali-calcic whereas I-type granitoids are magnesian and calcic. A-type granitoids resemble to within plate granites and post-orogenic granites whereas I-type granitoids resemble to volcanic arc granites. A-type granitoids contain higher concentrations of alkalies, Zr, Rb, Nb, Y, Th, Ce, high FeO/MgO ratios and lower concentrations of Mg, Ca and Sr, resembling post-orogenic A-type granites. It is possible that heat from a mantle-derived magma which intruded into the lower crust, and/or rapid crustal extension have been essential generation of approriate melts producing A-type granitoids. Thus we can conclude that A-type granitoids were generated from a mixed mantle-crust source. Negative Nb anomalies and low contents of Ti and P probably indicate a subduction-related origin for protolith of I-type granitoids. Negative Nb anomalies and enrichment in Ce relative to its adjacent elements can be related to involvement of continental crust in magmatic processes. I-type granitoids are also enriched in Rb, Ba, K, Th, Ce and depleted in Nb, Zr and Y, indicating that they have had interacted with crust. I-type granitoids may result from contamination of mantle-derived magmas by continental crust during a subduction

  9. Uranium and thorium in weathering and pedogenetic profiles developed on granitic rocks from NW Spain

    Energy Technology Data Exchange (ETDEWEB)

    Taboada, Teresa [Departamento de Edafoloxia e Quimica Agricola, Facultade de Bioloxia, University of Santiago de Compostela, E-15782, Santiago de Compostela (Spain)]. E-mail: edteresa@usc.es; Martinez Cortizas, Antonio [Departamento de Edafoloxia e Quimica Agricola, Facultade de Bioloxia, University of Santiago de Compostela, E-15782, Santiago de Compostela (Spain); Garcia, Carlota [Departamento de Edafoloxia e Quimica Agricola, Facultade de Bioloxia, University of Santiago de Compostela, E-15782, Santiago de Compostela (Spain); Garcia-Rodeja, Eduardo [Departamento de Edafoloxia e Quimica Agricola, Facultade de Bioloxia, University of Santiago de Compostela, E-15782, Santiago de Compostela (Spain)

    2006-03-01

    Uranium and thorium were analyzed in seven weathering and pedogenetic soil profiles developed on granitic rocks from NW Spain. Concentrations were measured by X-ray fluorescence spectrometry (XRF) and the U- and Th-bearing minerals were studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). Both elements were determined in rock, bulk soil and in different grain-size fractions (sand: 2000-50 {mu}m, silt: 50-2 {mu}m, and clay: < 2 {mu}m). U concentrations in the rock varied between 5.3 and 27.7 mg kg{sup -1} and Th concentrations from 5.5 to 50.7 mg kg{sup -1}. The most alkalic rocks can be considered as U-rich granites. Bulk soil U and Th concentrations are similar to those of the rocks (4.8-29.2 and 7.4-56.7 mg kg{sup -1}, respectively), but in the grain-size fractions both elements show the lowest concentrations in the sand and the highest in the clay. In the latter, concentrations are always higher than those of the rocks, particularly in the C horizons with enrichments up to 4 times for U and 5 times for Th. The concentration profiles and the ratios to the parent rock suggest that U and Th are leached from the surface soil and accumulate in the deeper horizons. Mass balance calculations, using Ti as a reference immobile element, also support U and Th leaching in the solum and supergene enrichment in bottom horizons. Leaching seems to be more intense on horizons with gravel content higher than 20%. The leaching of U and Th in the topmost horizons and the accumulation in the bottom soil horizons can be considered as a natural attenuation of the impact of these radiogenic elements in the environment. But their enrichment in the potentially airborne fraction poses some risk of redistribution in the ecosystems.

  10. Consolidating and water repellent treatments applied to wet and salt contaminated granite

    Directory of Open Access Journals (Sweden)

    Silva, B.

    2000-03-01

    Full Text Available A comparison was made of the efficacy of two consolidants and two water repellents applied to samples of granite under optimum conditions, with the efficacy of the same products applied to the granite in the presence of soluble salts or water. The amount of product absorbed and the amount of dry polymer remaining after treatment were compared. The results show that the presence of water and soluble salts in the stone significantly modifies the consumption of the products (in particular the water repellents and also the level of dry polymer retained. The water repellents were found to be much less effective when the substrate contained salts, whereas the presence of water did not appear to influence their efficacy. The lack of correlation between uptake, active dry polymer, and efficacy led to the conclusion that the presence of salts or water markedly changes the kinetics of the polymerization of the products.

    Se analiza la eficacia de dos consolidantes y dos hidrofugantes aplicados a rocas graníticas en condiciones óptimas comparativamente a la eficacia de los mismos productos aplicados sobre los mismos sustratos conteniendo cierta cantidad de sales solubles o de agua. Se compara la cantidad de producto absorbido y la cantidad de materia seca presente tras el curado. Los resultados indican que la presencia de agua y de sales solubles en la piedra modifica significativamente el consumo de los productos, sobre todo el de los hidrofugantes, así como la cantidad de materia seca. Se observa, asimismo, un fuerte detrimento en la eficacia de los hidrofugantes cuando el sustrato contiene sales mientras que, al contrario, la presencia de agua no parece infiuir en dicha eficacia. La falta de correlación entre el consumo, materia seca activa y eficacia lleva a concluir que la presencia de sales o agua modifica sensiblemente la cinética de la polimeración de los productos.

  11. Chemical transfers along slowly eroding catenas developed on granitic cratons in southern Africa

    Science.gov (United States)

    Khomo, Lesego; Bern, Carleton R.; Hartshorn, Anthony S.; Rogers, Kevin H.; Chadwick, Oliver A.

    2013-01-01

    A catena is a series of distinct but co-evolving soils arrayed along a slope. On low-slope, slowly eroding catenas the redistribution of mass occurs predominantly as plasma, the dissolved and suspended constituents in soil water. We applied mass balance methods to track how redistribution via plasma contributed to physical and geochemical differentiation of nine slowly eroding (~ 5 mm ky− 1) granitic catenas. The catenas were arrayed in a 3 × 3 climate by relief matrix and located in Kruger National Park, South Africa. Most of the catenas contained at least one illuviated soil profile that had undergone more volumetric expansion and less mass loss, and these soils were located in the lower halves of the slopes. By comparison, the majority of slope positions were eluviated. Soils from the wetter climates (550 and 730 mm precipitation yr− 1) generally had undergone greater collapse and lost more mass, while soils in the drier climate (470 mm yr− 1) had undergone expansion and lost less mass. Effects of differences in catena relief were less clear. Within each climate zone, soil horizon mass loss and strain were correlated, as were losses of most major elements, illustrating the predominant influence of primary mineral weathering. Nevertheless, mass loss and volumetric collapse did not become extreme because of the skeleton of resistant primary mineral grains inherited from the granite. Colloidal clay redistribution, as traced by the ratio of Ti to Zr in soil, suggested clay losses via suspension from catena eluvial zones. Thus illuviation of colloidal clays into downslope soils may be crucial to catena development by restricting subsurface flow there. Our analysis provides quantitative support for the conceptual understanding of catenas in cratonic landscapes and provides an endmember reference point in understanding the development of slowly eroding soil landscapes.

  12. Study on Microbes and Their Effects on Rare Earth Extraction in Weathering Crust of Granite

    Institute of Scientific and Technical Information of China (English)

    陈炳辉; 毋福海; 刘琥琥

    2001-01-01

    Microbes were cultured from the samples at various depths in a weathering profile of RE-bearing granite in Gonghe RE mine, Guangdong Province. The cultured microbes, existing at a depth of 0.2~12 m and being more plentiful within 3 m in the profile,include bacteria (Bacillus,Enterobacter, Escherichia, Alkaligenes, Neisseria, Staphylococcus and anaerobic bacteria such as Clostridium), fungi (Aspergillus niger, Aspergillus flavus, Penicillium, Mucor and Saccharomycete) and actinomyces. Experiments were made under room temperature by using solutions of the cultured microbes and their metabolites, compared with distilled water and the culture solution without microbes, to leach RE from the sample of the weathering crust. The results are shown by the experiments: (1) The mixed microbes cultured from the profile and their metabolites increase the quantity of RE leached from the sample and reduce the pH of the solutions. (2) The ability to leach RE from the sample varies with various microbes, decreasing in a sequence of fungi (Mucor, saccharomycete, Aspegillus and Penicillium), zymotic bacilli (Enterobacter, Escherichia etc.), Staphylococcus, zymotic Bacillus, actinomyces and Alkaligenes. (3) The RE leached with bacteria is mainly related to the pH value of the solutions influenced by the metabolites of the bacteria; whereas that leached with fungi is mainly related to the adsorption and imbibition of RE by the fungi and the complexing of RE with their metabolites. (4) Compared with that leached with ammonium sulfate, the fractionation of the RE leached with microbes is characterized by higher δCe, lower δEu and lower ratios of NLa/Sm and NGd/Yb. The result of the fractionation of RE accords with the distribution of RE in the various layers of a profile of weathering crust of granite in South China. The experimental results indicate that microbes and their metabolites should play a positive role in the mobilization, migration and fractionation of RE in the

  13. The failure of a slope cut into the weathering profile developed over a porphyritic biotite granite

    Science.gov (United States)

    Raj, J. K.

    1998-08-01

    At about 1.00 a.m. on 24 September, 1981, at km 24.5 of the Kuala Lumpur-Karak highway, there occurred a failure of a 26 m high slope cut into the weathering profile developed over a porphyritic biotite granite. The failure, which is best classified a slump-flow, occurred some 5.7 years after the end of excavation and involved the downslope movement of about 2000 m 3 of weathered bedrock material (mainly gravelly silty sands) and a few coreboulders. Continued movement of failed material through minor slumping and gulleying led to eventual exposure of the failure surface which was mainly located along a relict fault plane striking parallel to, and dipping 48° towards, the highway. Failure occurred as a result of several converging factors; the triggering factor being ground vibrations set up at the time of passing of three large trucks. Conditions of instability, however, were already present in the slope materials through infiltration of rainwater that led to saturation and the loss of apparent or effective cohesion. Infiltration had been encouraged by clearing of vegetation at the top of the cut and the creation of a track along its western edge some 6 months prior to failure. Infiltration was also encouraged by rainfall patterns with the failure occurring after some 29 days with almost continuous daily rainfall; this wet period being preceded by an unusual 27 days of no rain. It is concluded that stability assessments of slope cuts in weathering profiles over granitic bedrock need to take into consideration not only shear strength parameters, but also local climatic and other environmental factors, including likely triggering factors.

  14. Goethite colloid enhanced Pu transport through a single saturated fracture in granite.

    Science.gov (United States)

    Lin, Jianfeng; Dang, Haijun; Xie, Jinchuan; Li, Mei; Zhou, Guoqing; Zhang, Jihong; Zhang, Haitao; Yi, Xiaowei

    2014-08-01

    α-FeOOH, a stable iron oxide in nature, can strongly absorb the low-solubility plutonium (Pu) in aquifers. However, whether Pu transports though a single saturated fracture can be enhanced in the presence of α-FeOOH colloids remains unknown. Experimental studies were carried out to evaluate Pu mobilization at different water flow velocity, as affected by goethite colloids with various concentrations. Goethite nanorods were used to prepare (α-FeOOH)-associated Pu suspensions with α-FeOOH concentration of (0-150) mgL(-1). The work experimentally evidenced that α-FeOOH colloid does enhance transport of Pu through fractured granites. The fraction of mobile (239)Pu (RPu, m=41.5%) associated with the α-FeOOH of an extremely low colloid concentration (0.2mgL(-1)) is much larger than that in absence of α-FeOOH (RPu, m=6.98%). However, plutonium mobility began to decrease when α-FeOOH concentration was increased to 1.0mgL(-1). On the other hand, the fraction of mobile Pu increased gradually with the water flow velocity. Based on the experimental data, the mechanisms underlying the (α-FeOOH)-associated plutonium transport are comprehensively discussed in view of its dynamic deposition onto the granite surfaces, which is decided mainly by the relative interaction between the colloid particle and the immobile surface. This interaction is a balance of electrostatic force (may be repulsive or attractive), the van der Walls force, and the shear stress of flow.

  15. Monazite and zircon as major carriers of Th, U, and Y in peraluminous granites: examples from the Bohemian Massif

    Science.gov (United States)

    Breiter, Karel

    2016-12-01

    The chemical compositions of zircon and monazite and the relationships between the contents of Th, U, Y, and REE in both minerals and in the bulk samples of their parental rocks were studied in three Variscan composite peraluminous granite plutons in the Bohemian Massif. It was established that granites of similar bulk composition contain zircon and monazite of significantly different chemistry. Monazite typically contains 5-13 wt% (rarely up to 28 wt%) ThO2, 0.4-2 wt% (up to 8.2 wt%) UO2, and 0.5-2 wt% (up to 5 wt%) Y2O3, whereas zircon typically contains less than 0.1 wt% (rarely up to 1.7 wt%) ThO2, less than 1 wt% UO2 (in the Plechý/Plockenstein granite, commonly, 1-2 wt% and scarcely up to 4.8 wt% UO2), and less than 1 wt% Y2O3 (in the Nejdek pluton often 2-5, maximally 7 wt% Y2O3). Monazite is an essential carrier of thorium, hosting more than 80 % of Th in all studied granites. Monazite also appears to be an important carrier of Y (typically 14-16 %, and in the Melechov pluton, up to 81 % of the total rock content) and U (typically 18-35 % and occasionally 6-60 % of the total rock budget). The importance of zircon for the rock budget of all the investigated elements in granites is lower: 4-26 % U, 5-17 % Y, and less than 5 % Th.

  16. SilMush: A procedure for modeling of the geochemical evolution of silicic magmas and granitic rocks

    Science.gov (United States)

    Hertogen, Jan; Mareels, Joyce

    2016-07-01

    A boundary layer crystallization modeling program is presented that specifically addresses the chemical fractionation in silicic magma systems and the solidification of plutonic bodies. The model is a Langmuir (1989) type approach and does not invoke crystal settling in high-viscosity silicic melts. The primary aim is to model a granitic rock as a congealed crystal-liquid mush, and to integrate major element and trace element modeling. The procedure allows for some exploratory investigation of the exsolution of H2O-fluids and of the fluid/melt partitioning of trace elements. The procedure is implemented as a collection of subroutines for the MS Excel spreadsheet environment and is coded in the Visual Basic for Applications (VBA) language. To increase the flexibility of the modeling, the procedure is based on discrete numeric process simulation rather than on solution of continuous differential equations. The program is applied to a study of the geochemical variation within and among three granitic units (Senones, Natzwiller, Kagenfels) from the Variscan Northern Vosges Massif, France. The three units cover the compositional range from monzogranite, over syenogranite to alkali-feldspar granite. An extensive set of new major element and trace element data is presented. Special attention is paid to the essential role of accessory minerals in the fractionation of the Rare Earth Elements. The crystallization model is able to reproduce the essential major and trace element variation trends in the data sets of the three separate granitic plutons. The Kagenfels alkali-feldspar leucogranite couples very limited variation in major element composition to a considerable and complex variation of trace elements. The modeling results can serve as a guide for the reconstruction of the emplacement sequence of petrographically distinct units. Although the modeling procedure essentially deals with geochemical fractionation within a single pluton, the modeling results bring up a

  17. Nature of the Yucatan Block Basement as Derived From Study of Granitic Clasts in the Impact Breccias of Chicxulub Crater

    Science.gov (United States)

    Vera-Sanchez, P.; Rebolledo-Vieyra, M.; Perez-Cruz, L.; Urrutia-Fucugauchi, J.

    2008-05-01

    The tectonic and petrologic nature of the basement of the Yucatan Block is studied from analyses of basement clasts present in the impact suevitic breccias of Chicxulub crater. The impact breccias have been sampled as part of the drilling projects conducted in the Yucatan peninsula by Petroleos Mexicanos, the National University of Mexico and the Chicxulub Scientific Drilling Project. Samples analyzed come mainly from the Yaxcopoil-1, Tekax, and Santa Elena boreholes, and partly from Pemex boreholes. In this study we concentrate on clasts of the granites, granodiorites and quartzmonzonites in the impact breccias. We report major and trace element geochemical and petrological data, which are compared with data from the granitic and volcanic rocks from the Maya Mountains in Belize and from the Swannee terrane in Florida. Basement granitic clasts analyzed present intermediate to acidic sub-alkaline compositions. Plots of major oxides (e.g., Al2O3, Fe2O3, TiO2 and CaO) and trace elements (e.g., Th, Y, Hf, Nb and Zr) versus silica allow separation of samples into two major groups, which can be compared to units in the Maya Mountains and in Florida basement. The impact suevitic breccia samples have been affected by alteration likely related to the hydrothermal processes associated with the crater melt sheet. Cloritization, seritization and fenitization alterations are recognized, due to the long term hydrothermalism. Krogh et al. (1993) reported U-Pb dates on zircons from the suevitic breccias, which gave dates of 545 +/- 5 Ma and 418 +/- 6 Ma, which were interpreted in terms of the deep granitic metamorphic Yucatan basement. The younger date correlates with the age for the Osceola Granite and the St. Lucie metamorphic complex of the Swannee terrane in the Florida peninsula. The intrusive rocks in the Yucatan basement may be related to approx. 418 Ma ago collisional event in the Late Silurian.

  18. Nd:YVO{sub 4} laser removal of graffiti from granite. Influence of paint and rock properties on cleaning efficacy

    Energy Technology Data Exchange (ETDEWEB)

    Rivas, T., E-mail: trivas@uvigo.es [Dpto. Ingenieria de los Recursos Naturales y Medio Ambiente. Universidad de Vigo, Lagoas-Marcosende s/n, 36310 Vigo (Spain); Pozo, S. [Dpto. Ingenieria de los Recursos Naturales y Medio Ambiente. Universidad de Vigo, Lagoas-Marcosende s/n, 36310 Vigo (Spain); Fiorucci, M.P.; Lopez, A.J.; Ramil, A. [Centro de Investigacions Tecnoloxicas (CIT), Universidade da Coruna, 15403 Ferrol (Spain)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Cleaning using NdYVO{sub 4} laser at 355 nm of four different graffiti colours applied on granites. Black-Right-Pointing-Pointer Analysis of the influence of paint composition and properties of rocks on the process. Black-Right-Pointing-Pointer Composition of the paints and, in turn reflectance, determine the removal effectiveness. Black-Right-Pointing-Pointer The laser removal is not conditioned by properties of the stones. - Abstract: This paper presents the cleaning efficiency results for four differently coloured graffiti paints applied to two types of granitic stone by Nd:YVO{sub 4} laser at 355 nm. The paints were characterized in terms of mineralogy and chemistry using x-ray fluorescence, X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM); paint absorbance in the ultraviolet-visible-infrared range (200-2000 nm) was also assessed. The studied granites had different mineralogy, texture and porosity properties. Cleaning efficiency was evaluated by polarized microscopy, SEM, FTIR spectroscopy and spectrophotometer colour measurements. The results indicate differences in the effectiveness of surface cleaning for the blue, red and black paints as opposed to the silver paint, mainly attributed to chemical composition. No evidence was found that the granite properties had a bearing on laser effectiveness, although the degree, type and spatial distribution of transgranular fissures in the stone affected the overall assessment of cleaning effectiveness. Polarized light microscopy observations and colour measurements showed that the intensity and distribution of fissures affect the depth of paint penetration, ultimately affecting the cleaning efficiency for both granites.

  19. Characterization of weathering profile in granites and volcanosedimentary rocks in West Africa under humid tropical climate conditions. Case of the Dimbokro Catchment (Ivory Coast)

    Science.gov (United States)

    Koita, M.; Jourde, H.; Koffi, K. J. P.; da Silveira, K. S.; Biaou, A.

    2013-06-01

    In granitic rocks, various models of weathering profile have been proposed, but never for the hard rocks of West Africa. Besides, in the literature there is no description of the weathering profile in volcanosedimentrary rocks. Therefore, we propose three models describing the weathering profiles in granites, metasediments, and volcanic rocks for hard rock formations located in West Africa. For each of these models proposed for granitic and volcanosedimentary rocks of the Dimbokro catchment, vertical layered weathering profiles are described, according to the various weathering and erosion cycles (specific to West Africa) that the geological formations of the Dimbokro catchment experienced from the Eocene to the recent Quaternary period. The characterization of weathering profiles is based on: i) bedrocks and weathering profile observations at outcrop, and ii) interpretation and synthesis of geophysical data and lithologs from different boreholes. For each of the geological formations (granites, metasediments, and volcanic rocks), their related weathering profile model depicted from top to bottom comprises four separate layers: alloterite, isalterite, fissured layer, and fractured fresh basement. These weathering profiles are systematically covered by a soil layer. Though granites, metasediments and volcanic rocks of the Dimbokro catchment experience the same weathering and erosion cycles during the palaeoclimatic fluctuations from Eocene to recent Quaternary period, they exhibit differences in thickness. In granites, the weathering profile is relatively thin due to the absence of iron crust which protects weathering products against dismantling. In metasediments and volcanic rocks iron crusts develop better than in granites; in these rocks the alterite are more resistant to dismantling.

  20. Characterization of weathering profile in granites and volcanosedimentary rocks in West Africa under humid tropical climate conditions. Case of the Dimbokro Catchment (Ivory Coast)

    Indian Academy of Sciences (India)

    M Koita; H Jourde; K J P Koffi; K S Da Silveira; A Biaou

    2013-06-01

    In granitic rocks, various models of weathering profile have been proposed, but never for the hard rocks of West Africa. Besides, in the literature there is no description of the weathering profile in volcanosedimentrary rocks. Therefore, we propose three models describing the weathering profiles in granites, metasediments, and volcanic rocks for hard rock formations located in West Africa. For each of these models proposed for granitic and volcano sedimentary rocks of the Dimbokro catchment, vertical layered weathering profiles are described, according to the various weathering and erosion cycles (specific to West Africa) that the geological formations of the Dimbokro catchment experienced from the Eocene to the recent Quaternary period. The characterization of weathering profiles is based on: i) bedrocks and weathering profile observations at outcrop, and ii) interpretation and synthesis of geophysical data and lithologs from different boreholes. For each of the geological formations (granites, metasediments, and volcanic rocks), their related weathering profile model depicted from top to bottom comprises four separate layers: alloterite, isalterite, fissured layer, and fractured fresh basement. These weathering profiles are systematically covered by a soil layer. Though granites, metasediments and volcanic rocks of the Dimbokro catchment experience the same weathering and erosion cycles during the palaeoclimatic fluctuations from Eocene to recent Quaternary period, they exhibit differences in thickness. In granites, the weathering profile is relatively thin due to the absence of iron crust which protects weathering products against dismantling. In metasediments and volcanic rocks iron crusts develop better than in granites; in these rocks the alterite are more resistant to dismantling.