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Sample records for granite gneiss complex

  1. Evaluation of magma mixing in the subvolcanic rocks of Ghansura Felsic Dome of Chotanagpur Granite Gneiss Complex, eastern India

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

    2017-10-01

    The subvolcanic rocks exposed in the Ghansura Felsic Dome (GFD) of the Bathani volcano-sedimentary sequence at the northern fringe of the Rajgir fold belt in the Proterozoic Chotanagpur Granite Gneiss Complex preserves evidence of magma mixing and mingling in mafic (dolerite), felsic (microgranite) and intermediate (hybrid) rocks. Structures like crenulated margins of mafic enclaves, felsic microgranular enclaves and ocelli with reaction surfaces in mafic rocks, hybrid zones at mafic-felsic contacts, back-veining and mafic flows in the granitic host imply magma mingling phenomena. Textural features like quartz and titanite ocelli, acicular apatite, rapakivi and anti-rapakivi feldspar intergrowths, oscillatory zoned plagioclase, plagioclase with resorbed core and intact rim, resorbed crystals, mafic clots and mineral transporting veins are interpreted as evidence of magma mixing. Three distinct hybridized rocks have formed due to varied interactions of the intruding mafic magma with the felsic host, which include porphyritic diorite, mingled rocks and intermediate rocks containing felsic ocelli. Geochemical signatures confirm that the hybrid rocks present in the study area are mixing products formed due to the interaction of mafic and felsic magmas. Physical parameters like temperature, viscosity, glass transition temperature and fragility calculated for different rock types have been used to model the relative contributions of mafic and felsic end-member magmas in forming the porphyritic diorite. From textural and geochemical investigations it appears that the GFD was a partly solidified magma chamber when mafic magma intruded it leading to the formation of a variety of hybrid rock types.

  2. Effects of Weathering on Mechanical Properties of Granite Gneiss ...

    African Journals Online (AJOL)

    This paper describes the geotechnical characteristics of granite gneiss and dolerite from Oban and Obuduregions in South-eastern Nigeria. The suitability of these rocks for civil construction purposes and the effects of weathering on their mechanical properties are examined. The results indicate that compressive strength ...

  3. Geochemical trends in the weathered profiles above granite gneiss ...

    African Journals Online (AJOL)

    Geochemical trends in the weathered profiles above granite gneiss and schist of Abeokuta area, southwestern Nigeria. Anthony T Bolarinwa, Anthony A Elueze. Abstract. No Abstract. Journal of Mining and Geology 2005, Vol. 41(1): 19-31. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT ...

  4. Geochemistry of mylonitic tourmaline-bearing granite- gneiss pluton in the northeast of June mine

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    Arezoo Moradi

    2017-07-01

    Full Text Available Introduction Studied mylonitic granite-gneiss body is located in the Northwest of the Azna region in the Lorestan province close to the June dimension stone mine. It is a part of the metamorphic- magmatic complex including granite-gneiss, amphibolite, marble and schist. The crystalline basement is attributed to late-Neoproterozoic and it indicates a Panafrican basement, which yields a laser-ablation ICP–MS U–Pb zircon ages of 608 ± 18 Ma and 588 ± 41 Ma (Shakerardakani et al., 2015. There are two granite-gneiss plutons in the complex that are Galeh– Dezh (Shabanian et al., 2009, and June plutons. The Galeh-Doz pluton are previously proposed as syn-deformation pluton with a major S-shaped bend which has been imparted during dextral shearing with a Late Cretaceous (Mohajjel and Fergusson, 2000. However, new age dating on the pluton using U–Pb in the magmatic zircon produced the late-Neoproterozoic dates (Nutman et al., 2014; Shakerardakani et al., 2015. The granite-gneiss plutons show mylonitic fabrics and microstructures (Shabanian et al., 2010. The geochemical characteristics of mylonitic granite-gneiss body near June mine in NW Azna, is in the focus of our research. Materials and methods Petrographic investigations of 30 thin sections were made. Then eight samples were selected and analyzed for whole rock major, trace and REE compositions by ICP-emission spectrometry and ICP-mass spectrometry using natural rock standards as reference samples for calibration at the ACME Analytical Laboratories in Vancouver, British Columbia, Canada. Results The studied gneiss- granitic body has lepido-granoblastic texture as its major texture. It variably shows evidence of dynamic deformation from ultramylonite to protomylonite. The gneiss- granite consists of quartz, alkali feldspar (mostly as perthite, plagioclase, biotite, white mica (muscovite and phengitic muscovite. Accessory phases in the granitoid include, tourmaline, zircon, magmatic epidote

  5. Rb-Sr age estimation of granites-gneisses of Belopotokskij type (Soviet Carpathians)

    International Nuclear Information System (INIS)

    Stepanyuk, L.M.; Kotlovskaya, F.I.; Dovbush, T.I.

    1987-01-01

    Using rubidium-strontium method the age of granito-gneisses of Belopotokskij type of 470 ± 6 mln. years, which agree with isotopic age (459 ± 6 mln. years) obtained by uranium-lead isochronous method using syngenetic zircon, is established. The latter testifies to the manifestation of magmatic activity 460-470 mln. years ago. The low initial ratio of strontium isotopes 87 Sr/ 86 Sr and results of petrographic study of fel spars are indicative of magmatic nature of initial granites and plutonic (mantle or lower crust) source of magma, crystallization of which was the beginning of the Belopotokskij type granito-gneiss formation

  6. Origin of allanite in gneiss and granite in the Dabie orogenic belt, Central East China

    Science.gov (United States)

    Guo, Haihao; Xiao, Yilin; Xu, Lijuan; Sun, He; Huang, Jian; Hou, Zhenhui

    2017-03-01

    Allanite is a common accessory mineral phase, representing an important carrier of rare earth elements, Th, U, Sr and other trace elements in most continental rocks. As Th and U can be incorporated into the allanite lattice, the mineral is a good geochronological tool for constraining geological events. Moreover, the trace element features δEu, Th/U ratio and common lead content of allanite are indicators of the forming conditions. Allanite and coexisting epidote-group minerals are abundant in ultrahigh-pressure (UHP) metamorphic rocks from the Dabie-Sulu orogen in central East China. However, if these minerals formed in the Neoproterozoic as magmatic phases, or in the Triassic as metamorphic phases is a matter of long-standing controversy. We report major and trace element analyses of whole rocks, allanite and coexisting epidote-group minerals, together with U-Th-Pb isotopic compositions of allanite in UHP gneiss from the Dabie-Sulu orogen, and allanite in the adjacent Jingshan granite. The granite is emplaced along the southeastern margin of the North China Craton and considered a product of partial melting of the subducted Dabie-Sulu gneiss. Trace elements (low Th/U and La/Sm, high δEu and high Sr) and high common lead concentrations indicate a metamorphic origin of allanite-epidote in the UHP gneiss. On the other hand, coarse-grained allanite from the Jingshan granite shows a corrosion core and a magmatic rim with common 208Pb up to 70% in the core and less than 30% in the rim. The allanite cores are of peritectic and the rims of magmatic origin with ages of ∼160 Ma, consistent with the granite crystallization age. In combination with previous studies, we conclude that the allanite of the Jingshan granite has form from the subducted and remolten Dabie-Sulu gneiss. Allanite records Triassic UHP metamorphic ages as well as Jurassic peritectic-magmatic ages as a part of the evolution of the Dabie-Sulu orogen.

  7. Influence de la structure des gneiss et des granites sur la resistance ...

    African Journals Online (AJOL)

    A partir de la structure des roches (gneiss et granites) provenant des différentes régions du Togo il a été proposée une classification basée sur le modèle exponentielle appliquée à la probabilité de présence de grains de dimensions variables. Cette classification a permis d'évaluer l'homogénéité granulaire des roches de ...

  8. Petrogenesis of Oxidized Arfvedsonite Granite Gneiss from Dimra Pahar, Hazaribagh, Eastern India: Constraints from Mineral Chemistry and Trace Element Geochemistry

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    Basak, Ankita; Goswami, Bapi

    2017-04-01

    The arfvedsonite granite gneiss of Dimra Pahar occurs along the North Purulia Shear Zone (NPSZ) which pivots the Proterozoic Chotannagpur Gneissic Complex (CGC), Eastern India. Although minerals like arfvedsonite and aegirine depict the peralkaline nature of the pluton, the geochemistry of the rock reflects its composition varying from peralkaline to mildly peraluminous. K-feldspar, quartz, arfvedsonite, albite with accessory aegirine, titaniferous iron oxides and zircon form the dominant mineralogy of this alkali feldspar granite (IUGS, 2000) gneiss. The zircon saturation temperature corresponds to 747oC-1066oC. The granitic magma contains low water content evidenced by the absence of any pegmatite associated with this pluton. Geochemically these granites are classified as ferroan and alkalic (cf. Frost et al., 2001). These highly evolved granites possess enrichment of SiO2, Na2O + K2O, FeO(t)/MgO, Ga/Al, Zr, Nb, Ga, Y, Ce and rare earth elements (REE) with low abundance of CaO, MgO, Ba and Sr which characterize their A-type nature while standard discrimination diagrams ( cf. Eby, 1992; Grebennikov, 2014) help to further discriminate them as A1 type. Tectonic discriminations diagrams (Pearce et al., 1984; Maniar and Piccoli, 1989; Batchelor and Bowden, 1985) constrain the tectonic setting of the magma to be anorogenic, within plate, rift-related one. The REE compositions show moderately fractionated patterns with (La/Yb)N 2.57-10.5 and Eu/Eu* 0.16-0.70. Multielement spider diagram and various trace element ratio together with oxidized nature (ΔNNO: +2) of these granites further suggest that these have been derived from OIB-type parental magma. The peralkaline nature of the granite and its lack of subduction- related geochemical features are consistent with an origin in a zone of regional extension. The extremely high Rb/Sr ratios combined with the extreme Sr, Ba, P, Ti and Eu depletions clearly indicate that these A-type granites were highly evolved and require

  9. 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

  10. Tungsten isotope composition of the Acasta Gneiss Complex

    Science.gov (United States)

    Willbold, M.; Mojzsis, S. J.; Chen, H.-W.; Elliott, T.

    2015-06-01

    High-precision tungsten (182W/184W) isotope measurements on well-characterised mafic and felsic samples of the ca. 3960 Ma Acasta Gneiss Complex (AGC; Northwest Territories, Canada) show radiogenic ε182W values between +0.06 to +0.15. Two ca. 3600 Ma felsic samples from this terrane have ε182W ∼ 0 and are the oldest samples so far documented to have a W isotopic composition indistinguishable from that of the modern mantle. The ε182W data are correlated with ε142Nd (Roth et al., 2014) and we attribute this variability to incomplete metamorphic homogenisation of the 3960 Ma protolith with more recent material in a 3370 Ma tectono-thermal event. Notably, the value of the positive ε182W anomalies seen in the 3960 Ma AGC samples that are least affected by metamorphic homogenisation is comparable to that observed in other early Archean rocks (Isua Supracrustal Belt, Greenland; Nuvvuagittuq Supracrustal Belt, Canada) and the late Archean Kostomuksha komatiites (Karelia). This demonstrates a globally constant signature. We infer that the presence of a pre-late veneer mantle represents the most straightforward interpretation of a uniform distribution of ε182W ∼ + 0.15 value in Archean rocks of different ages. We show that such a notion is compatible with independent constraints from highly siderophile element abundances in mafic and ultra-mafic Archean mantle-derived rocks. The absence of anomalous ε182W and ε142Nd so far measured in samples younger than ca. 2800 Ma suggests progressive convective homogenisation of silicate reservoirs. The downward mixing of an upper mantle rich in late-delivered meteoritic material might account for these combined observations.

  11. Petrological and geochemical features of the early Paleozoic granitic gneisses and iron ores in the Tianhu iron deposit, Eastern Tianshan, NW China: Implications for ore genesis

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    Zheng, Jiahao; Mao, Jingwen; Yang, Fuquan; Chai, Fengmei; Shen, Ping

    2017-08-01

    This paper reports whole-rock geochemical, zircon U-Pb and Hf isotopic data for ore-hosted granitic gneisses, mineral compositions of oxides, and sulfur isotopic data for sulfides in iron ores from the Tianhu deposit, central part of the Eastern Tianshan. Our results can provide crucial constraints on the genesis of granitic gneisses and early Paleozoic tectonic setting of the Eastern Tianshan. LA-ICP-MS U-Pb dating on magmatic zircons yielded weighted mean 206Pb/238U ages of 463 to 438 Ma, interpreted as the crystallization ages of the granitic protoliths and the formation ages of the Tianhu Group. Zircon U-Pb age of ore-hosted granitic gneiss (ca. 459 Ma) can provide reliable constrains on upper limit for iron mineralization age in the Tianhu deposit. Geochemical characteristics suggest that the protoliths of the Tianhu granitic gneisses are metaluminous to weakly peraluminous high-K calc-alkaline granitic rocks, exhibiting typical subduction-related features such as strong enrichment in LREE and LILE and depletion in HFSE. Zircon Hf isotopic compositions show a positive trend from 463 to 438 Ma, indicating that 460 Ma magmas came from both ancient and juvenile sources, whereas 438 Ma magmas involved more juvenile material. Some early Paleozoic granitoids were recently identified in the Eastern Tianshan with the ages between ca. 475 and ca. 425 Ma. The formation of these early Paleozoic granitoids was in response to subduction processes, suggesting that subduction of Junggar Ocean probably began in the Early Ordovician and lasted until Late Silurian. Pyrite and pyrrhotite in iron ores have δ34SCDT values from + 4.6 to + 15.7‰, which are consistent with the marine source, but inconsistent with the magmatic source or those involved evaporites in skarn iron deposit. Geological, geochemical, and isotopic data suggest that the Tianhu iron ores were formed by volcano-sedimentary processes in a subduction environment during the early Paleozoic time, and Tianhu is a

  12. 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

    OpenAIRE

    Wilson Teixeira; Ciro Alexandre Ávila; Luciana Cabral Nunes

    2008-01-01

    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 la...

  13. Evaluating the controls on Tourmaline Crystallization in the mylonitic granite-gneiss pluton in the Northeastern of Jan mine (Lorestan province

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    Arezoo Moradi

    2017-02-01

    Full Text Available Introduction The study area is a part of the Sanandaj- Sirjan zone that is located in the NW of Azna city and NE of the dimension stone mine of Jan between 49° 11' 41"and 49° 16' 07" E longitude and 33° 36'35" and 33° 38'12" N latitude., A pluton of mylonitic granite-gneiss is exposed in the area which contains abundant tourmalines as black and patchy or subgrain association. Geochemically, the studied granite-gneiss is A-type, peraluminous to slightly metaluminous and calc – alkaline to slightly alkaline (Moradi et al., 7. The electron microprobe analyses of the tourmalines display shorl-dravite in composition with more tendency to shorl (Moradi et al., 2015. In this paper we try to study the petrological sites of tourmaline formation with associated minerals, controller factors of crystallization using mineral chemistry of tourmaline, comprehensive behavior of trace elements in the tourmaline, synthetic phase diagrams and finally relationships between the associated minerals. Materials and methods The results of trace-element and major-element analyses were obtained from one polished thin section including 2 tourmaline grains. Major-element analyses of tourmaline were obtained at Oklahama City University of America using the JEOL 8200 electron microprobe with a spot size of 5 μm and trace-element analyses were performed on just a sample by Laser Ablation-Inductively Coupled Plasma-Mass Spectroscopy (LA-ICP-MS a 193nm ArF excimer laser ablation system (MicroLas GeoLas 200Q in combination with a quadrupole ICP-MS (Micromass Platform ICP at Utrecht University of Netherland. Representative EMP and LA-ICP-MS analyses of tourmaline samples are presented in Tables1 and 2. Results The results of LA-ICP-MS on tourmalines of Jan mine in the North east of mylonitic granite-gneiss body show that distribution and diffusion of trace elements during the growth of tourmaline trend is positive on the plots of binary Mn versus Fetot / (Fetot +Mg and it

  14. Preliminary radiometric analyses of zircons from the Mount Copeland syenite gneiss, Shuswap metamorphic complex, British Columbia

    International Nuclear Information System (INIS)

    Okulitch, A.V.; Laveridge, W.D.; Sullivan, R.W.

    1981-01-01

    The isotopic ratios resulting from Pb and U analyses on three zircon fractions from syenite gneiss intrusive into metasediments of the Shuswap Metamorphic Complex are collinear on a concordia plot and yield upper and lower intercepts of about 773 Ma and 70 Ma. The upper intercept is tentatively interpreted as the minimum age of emplacement. The lower intercept is suggested to be the time of uplift and cooling associated with tectonic denudation of the Shuswap Complex. The implied age of the country rocks is pre-late Proterozoic and they may be correlatives of the Purcell Supergroup. (auth)

  15. Southern complex: geology, geochemistry, mineralogy, and mineral chemistry of selected uranium- and thorium-rich granites

    International Nuclear Information System (INIS)

    Hoffman, M.A.

    1987-01-01

    Four major rock groups are defined in the Southern Complex: the Bell Creek Granite (BCG), the Clotted Granitoids (CGR), the Albite Granite (AGR), and the Migmatite Complex. Metatexites of the Migmatite Complex are the oldest rocks and include paleosome of a metasedimentary and metavolcanic protolith represented by Banded Iron Formation, Banded Amphibolite, and Banded Gneisses, and interlayered or crosscutting leucogranites. The CGR span the range from metatexite to diatexite and represent in-situ partial melting of metapelitic layers in the protolith during intrusion of the BCG. The BCG cuts the migmatites, is locally cut by the CGR, and was derived by partial melting of a dominantly metasedimentary protolith at some depth below the presently exposed migmatites during a regional tectonothermal event. The Albite Granite is a 2km diameter, muscovite-fluorite-columbite-bearing intrusive stock that cuts all other major units. The thorium history of the BCG is a function of the history of monazite. The thorium history of the CGR is also dominated by monazite but the thorium content of this unit cannot be entirely accounted for by original restite monazite. The uranium history of the BCG and CGR was dominated by magmatic differentiation and post magmatic, metamorphic and supergene redistributions and is largely independent of the thorium history. The thorium and uranium history of the AGR was dominated by magmatic/deuteric processes unlike the BCG and CGR

  16. Geochemistry of the uranium mineralized Achala granitic complex, Argentina: Comparison with Hercynian peraluminous leucogranites of western Europe

    International Nuclear Information System (INIS)

    Cuney, M.; Leroy, J.; Valdiviezo, P.A.; Daziano, C.; Gamba, M.; Zarco, A.J.; Morello, O.; Ninci, C.; Molina, P.

    1989-01-01

    The Achala granitic complex belongs to the Sierras Pampeanas Hercynian belt, located west of the city of Cordoba, Argentina. This complex is very large (about 100 km N-S and 40 km E-W) and is composed of biotite, biotite with muscovite and muscovite with tourmaline granites intruded in amphibolite grade metamorphic rocks, along a main N 20 deg. E structural direction. Numerous uranium mineralizations are located within the granitic massif and tungsten mineralizations are present both in the enclosing metamorphic rocks and in the granite. The geochemistry of the granite has been studied in four test areas (Southern, Copina, Median and Don Vincente). Two test areas (Median and Don Vicente) present clear evidence of hydrothermal alteration: albitization and dequartzification similar to the French 'episyenites', silicification and argillic alteration. Potassic alteration is rare and weakly developed. The two test areas with hydrothermal alteration present a high uranium geochemical background (5-30 ppm). High thorium contents (up to 65 ppm) are essentially observed in the less differentiated granites of the Copina and Median areas. Thorium/uranium ratios are highly variable (1-10). Uranium minerals are related to different environments - (1) apatite-biotite enclave mineralized with uraninite and uranothorite, (2) gneiss from the contact metamorphism rim, (3) granite with incipient dequartzification, (4) granite associated with albitic episyenites and (5) silicified granite - but are all located in the two test areas presenting clear evidence of hydrothermal alteration. The three petrogenetic events are clearly related to very different mechanisms, separated from each other by several tens of millions of years in the west European Hercynian chain. In the same period the same succession of events leading to uranium deposits is observed in Argentina. 34 refs, 10 figs, 1 tab

  17. A practical assessment of aquifer discharge for regional groundwater demand by characterizing leaky confined aquifer overlain on a Mesozoic granitic gneiss basement

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    Shih, David Ching-Fang

    2018-04-01

    Due to increasing population worldwide, there is an urgent need to manage these important but diminishing groundwater resources efficiently to ensure their continued availability. The major innovative design of this study is to provide a practical assessment process for groundwater discharge under a regional demand by characterizing the nature of leaky confined aquifers overlain on a Mesozoic granitic gneiss basement which involves the important groundwater system in the Kinmen region (Taiwan, ROC) and the assessment of adoptable groundwater discharge in aquifer is needed. The storage coefficient presents an order of one in a thousand and hydraulic conductivity is approximately at the order of 1-8 m/d and 0.4-0.9 m/d for aquifer and aquitard respectively. Groundwater discharge and admissible number of pumping well is suggested considering scheduled maximum groundwater volume and head decline change for eastern and western studied area respectively. The safety subjected to the conservative issue is then addressed by the use of scheduled maximum groundwater volume. It reveals that the safety can be ensured using the indicator as scheduled maximum groundwater volume with predefined scenarios. The result can be utilized practically for developing management strategy of groundwater resources due to the applicability and novel of method.

  18. Evolutionary trend of the Jarawa younger granites ring complex, Jos ...

    African Journals Online (AJOL)

    The Jarawa Younger Granites Ring Complex which occupies the eastern flank of the popular Jos-Bukuru Ring Complex in Central Nigeria was geologically and geochemically investigated in order to identify the different lithologic units that make up the formation, as well as understand its geochemistry. These were used to ...

  19. Temperature time evolution of the Assynt Terrane of the Lewisian Gneiss Complex of Northwest Scotland from zircon U-Pb dating and Ti thermometry

    OpenAIRE

    CROWLEY, QUENTIN

    2015-01-01

    The Lewisian Gneiss Complex of Northwest Scotland is a classic Precambrian basement gneiss complex. The Lewisian is divided into a number of terranes on the basis of structural, metamorphic and geochronological evidence. The most well-studied of these is the Assynt Terrane, which forms the central part of the Lewisian outcrop on the Scottish mainland. Field evidence shows that it has a complex tectonothermal history, the early stages of which remain poorly constrained. This paper sets out to ...

  20. The instrumental neutron-activation analysis of granites from the Bushveld Complex

    International Nuclear Information System (INIS)

    Watterson, J.I.W.

    1978-01-01

    Three methods of instrumental neutron-activation analysis, 14MeV, reactor thermal, and reactor epithermal, are compared for the analysis of granites form the Bushveld Complex. A total of 34 elements can be determined in the granites by these methods. Samples from the Zaaiplaats area were analysed by thermal neutron activation, and 22 elements were determined in all of them. These elements were used to distinguish between the mineralized Bobbejaankop and Lease granites and the Main granite by the use of multivariate statistics. The Bobbejaankop granite appears as a more-differentaited rock carrying greater amounts of the incompatible elements than does the Main granite [af

  1. Geology and geochronology of the granitic batholithic complex, Sinaloa, Mexico

    International Nuclear Information System (INIS)

    Henry, C.D.

    1975-01-01

    Geologic mapping shows that a large portion of the state of Sinaloa, Mexico is underlain by a granitic batholithic complex. It is predominantly granodiorite, though ranging in composition from gabbro to quartz monzonite. Pre-batholithic rocks include metamorphosed eugeosynclinal sedimentary rocks (Early Cretaceous or older), a mafic igneous complex of gabbro, pyroxenite, and anorthosite, and a quartz diorite orthogneiss. Relative age relationships among these rock types are uncertain. The pre-batholithic rocks are restricted to a belt along the Pacific coast. Comparisons of biotite and hornblende K--Ar ages and zircon U--Pb ages from identical samples reveal that concordant biotite-hornblende K--Ar ages (ages that agree within analytical precision) measure a time during cooling of a granitic rock that closely followed emplacement and crystallization. Cooling of a small (3 km diameter) pluton emplaced in a relatively cold environment was rapid, and K--Ar and U--Pb ages agree within approximately 1 million years. Two larger plutons (30 to 40 km in diameter) that were studied in detail were emplaced into hot environments. They cooled more slowly, such that the K--Ar ages of biotite and hornblende are 3 to 4 million years lower than the U--Pb ages of zircon

  2. Fracture systems in the younger granite rocks around fobur, northern ...

    African Journals Online (AJOL)

    Outcrop-scale fractures and associated veins found in the Younger Granite rocks around Fobur, Northern Nigeria were studied in relation to similar structures in their host rocks (Migmatites-gneisses -quartzite complex). Fractures and veins attitude (strike and dip) data were collected across the study area and subjected to ...

  3. The behaviour of monazite from greenschist facies phyllites to anatectic gneisses: An example from the Chugach Metamorphic Complex, southern Alaska

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    Gasser, Deta; Bruand, Emilie; Rubatto, Daniela; Stüwe, Kurt

    2012-03-01

    Monazite is a common accessory mineral in various metamorphic and magmatic rocks, and is widely used for U-Pb geochronology. However, linking monazite U-Pb ages with the PT evolution of the rock is not always straightforward. We investigated the behaviour of monazite in a metasedimentary sequence ranging from greenschist facies phyllites into upper amphibolites facies anatectic gneisses, which is exposed in the Eocene Chugach Metamorphic Complex of southern Alaska. We investigated textures, chemical compositions and U-Pb dates of monazite grains in samples of differing bulk rock composition and metamorphic grade, with particular focus on the relationship between monazite and other REE-bearing minerals such as allanite and xenotime. In the greenschist facies phyllites, detrital and metamorphic allanite is present, whereas monazite is absent. In lower amphibolites facies schists (~ 550-650 °C and ≥ 3.4 kbar), small, medium-Y monazite is wide-spread (Mnz1), indicating monazite growth prior and/or simultaneous with growth of garnet and andalusite. In anatectic gneisses, new low-Y, high-Th monazite (Mnz2) crystallised from partial melts, and a third, high-Y, low-Th monazite generation (Mnz3) formed during initial cooling and garnet resorption. U-Pb SHRIMP analysis of the second and third monazite generations yields ages of ~ 55-50 Ma. Monazite became unstable and was overgrown by allanite and/or allanite/epidote/apatite coronas within retrograde muscovite- and/or chlorite-bearing shear zones. This study documents polyphase, complex monazite growth and dissolution during a single, relatively short-lived metamorphic cycle.

  4. Primordial crustal growth in northern Nigeria: preliminary Rb-Sr and Sm-Nd constraints from Kaduna migmatite-gneiss complex

    International Nuclear Information System (INIS)

    Dada, S. S.; Briqueu, L.; Birck, J. L.

    1998-01-01

    The Kaduna Migmatite-Gneiss Complex in the central area of the Northern shield includes variably migmatised granitotrondhjemitic gneisses and amphibolite of hitherto unknown age. The amphibolite enclaves and dykes are metatholeiites with comparatively unfractionated rare-earth patterns. The two main rock units (TTG and amphibolite) exhibit complementary geochemical signatures in the normalised abundance patterns of relatively incompatible elements and suggest possible derivation of the gneisses from subduction related mafic material. Sm-Nd and Rb-Sr isotopic data document early Archaean crustal formation of new crust and its subsequent late Archaean differentiation. These preliminary results form an evidence for a more extended crustal history in the heart of the Pan-African domain (ca. 600 Ma.). They suggest the differentiation of juvenile crustal protolith from a chondritic reservoir about 3.5 Ga. for the gneiss-amphibolite bimodal suite. A tectonothermal event about 3.1-3.0 Ga led to the emplacement of an early gneiss as indicated from Rb-Sr and U-Ph zircon analyses. Subsequent differentiation and/or reworking around 2.8-2.7 Ga is coherent with the Liberian orogeny within the West African- Latino American subregion

  5. Anasagar gneiss: A folded granitoid pluton in the Phanerozoic South ...

    Indian Academy of Sciences (India)

    The Anasagar gneiss was emplaced as a concordant sheet like body along the contact of quartzite and pelitic/semipelitic schist horizons in the northern part of the South Delhi Fold Belt. It is typically a granite gneiss containing megacrysts of K-feldspar set in a recrystallised foliated matrix. The megacrysts are in general ...

  6. 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

    rocks and formed siliceous melting-precipitating cells (SMPCs) (see, e.g., Huppert and Sparks, 1988). This mass of siliceous magma blocked ascent of denser mafic magmas to higher levels in the crust; hence the RLS is confined to a series of circumferential lobes around the periphery of the Bushveld Complex. Diapirs rose from the SMPCs to form sheets of Nebo Granite, which ascended in the center of the Bushveld Complex and spread laterally along the upper contacts of the RLS lenses.

  7. Petrogenesis of peralkaline granite dykes of the Straumsvola complex, western Dronning Maud Land, Antarctica

    Science.gov (United States)

    Harris, Chris; Dreyer, Tanya; le Roux, Petrus

    2018-01-01

    assimilation are unfeasible, unless an unexposed high-δ18O contaminant is invoked. Instead, it is proposed that the peralkaline syenite and granite dykes formed by partial melting of alkali-metasomatised gneiss that surrounds the nepheline syenite, followed by fractional crystallization.

  8. U-Pb age in zircon of intrusive granite at Acopiara complex, Crystal region, domain Central Ceara, Brazil

    International Nuclear Information System (INIS)

    Neri, T.F.O.; Hamelak, G.M.S.; Azevedo, L.R.; Mattos, I.C.; Verissimo, C.U.V.; Nogueira Neto, J.A.; Lima, M.N.

    2015-01-01

    Granitic body mineralogically composed by two micas, located at Crystal region, Ceara Central domain and intruded into lithotypes from Acopiara complex, provided an age of ∼526 Ma, indicating important period of magma generation of granitic composition associated with crustal anatexia, during Paleozoic

  9. Hybridization in the subvolcanic Jaala-Iitti complex and its petrogenetic relation to rapakivi granites and associated mafic rocks of southeastern Finland

    OpenAIRE

    Salonsaari, P.T.

    1995-01-01

    The 1630 Ma Jaala-Iitti complex is an example of bimodal rapakivi granite magmatism in which the interaction of granite and diabase magmas have led locally to hybridization. The dyke-like complex is situated at the northwestern margin of the Wiborg rapakivi batholith in southeastern Finland, cutting both the Proterozoic Svecofennian metamorphic crust and the Wiborg batholith. The complex consists mainly of non-hybridized compositionally homogeneous granites, i.e., hornblende granite and hornb...

  10. 1.99 Ga mafic dykes of the Lewisian Gneiss Complex of Scotland: An upper age limit for the Palaeoproterozoic Loch Maree Group

    Science.gov (United States)

    Baker, Thomas; Prave, Tony; Spencer, Christopher

    2015-04-01

    Mafic dyke swarms are often used as geochronological markers, as they are widespread and emplaced over short timespans. The ca. 2.4 Ga Scourie dyke swarm is one such example that has played a key role in understanding the complex tectonic and metamorphic history of the Lewisian Gneiss Complex of Scotland (LGC), part of the North Atlantic Craton (NAC). The LGC consists of Archean and Palaeoproterozoic terranes that experienced polyphase deformation prior to their assembly at ca. 1.8 Ga. Zircons separated from a doleritic dyke from the Gairloch terrane have yielded a concordant U-Th-Pb age (1,989 +4.3 / -0.99 Ma) using the ID-TIMS method. The doleritic dyke is emplaced in Lewisian gneiss that experienced both granulite and amphibolite-facies metamorphism. Partial recrystallisation and amphibolitisation of the dyke demonstrate that it pre-dates the most recent (Laxfordian) amphibolite-facies metamorphic event. The age obtained from the dyke overlaps the U-Pb age of a previously dated olivine gabbro dyke from the Assynt terrane (1,992 Ma). These combined ages provide strong corroborating evidence for a ca. 2.0 Ga mafic dyke swarm event, distinct from the older ca. 2.4 Ga Scourie dyke event known from elsewhere in the LGC. The existence of a ca. 2.0 Ga mafic dyke swarm provides an upper age limit for the Loch Maree Group (LMG), a Palaeoproterozoic succession of metasediment and metavolcanic rocks that overlie the LGC and which are not cross-cut by the Scourie dykes. This study proposes that a period of crustal extension took place in the region at ca. 2.0 Ga. Later, subduction may have resulted in the accretion of the LMG and the adjacent Ard Gneiss, which has previously been regarded as a magmatic arc. The ca. 1.9 Ga age of the earliest stage of the Laxfordian metamorphic event, which affected the LMG, could therefore mark the onset of collision. This sequence of events can be correlated with other coeval areas of the NAC, including the Nagssugtoqidian mobile belt of

  11. The transition from granite to banded aplite-pegmatite sheet complexes: An example from Megiliggar Rocks, Tregonning topaz granite, Cornwall

    Czech Academy of Sciences Publication Activity Database

    Breiter, Karel; Ďurišová, Jana; Hrstka, Tomáš; Korbelová, Zuzana; Vašinová Galiová, M.; Müller, A.; Simons, B.; Shail, R. K.; Williamson, B. J.; Davies, J. A.

    302/303, March 2018 (2018), s. 370-388 ISSN 0024-4937 R&D Projects: GA ČR GA14-13600S Institutional support: RVO:67985831 Keywords : granite * aplite * pegmatite * magmatic layering * Megiliggar Rocks * Cornwall Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 3.677, year: 2016

  12. 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

  13. 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

  14. The granitic complex of Brame/Saint-Sylvestre/Saint-Goussaud (French Massif Central), geochemical mapping applied to uranium prospecting

    International Nuclear Information System (INIS)

    Valois, J.P.

    1991-01-01

    Obtained geochemic data from the granitic complex of Brame/Saint-Sylvestre/Saint-Goussaud (French Massif Central), which is known as uranium ore bearing. Friedrich's data were reinterpreted using a different statistical method (principal component analysis with oblic rotation of the factors). The resulting trace element associations are interpreted according to the several mineral paragenesis previously described in this complex. These associations can be related to the successive stages of granitic cristallisation, and their mapping is in agreement with previous mapping obtained from quite different data (structural petrology for example). New results concern an U, Zn, Y, R.E association which is attributed to the uraninite paragenesis, previously described on this granitic complex. Mapping this last association contributes to emphasize the central part of the complex as a favourable zone for prospecting [fr

  15. Geochemistry of the Bayonplutonic Complex – Western Cameroon ...

    African Journals Online (AJOL)

    The BayonNeoproterozoic plutonic complex located in Western Cameroon intrudes gneisses of Paleo to Neo Proterozoic age. The complex is composed of gabbro, monzogabbro and monzonites frequently crosscut by trachytic and granitic veins. The primary mineral assemblages of the gabbro and monzogabbro is ...

  16. P-T-t conditions, Nd and Pb isotopic compositions and detrital zircon geochronology of the Massabesic Gneiss Complex, New Hampshire: isotopic and metamorphic evidence for the identification of Gander basement, central New England

    Science.gov (United States)

    Dorais, Michael J.; Wintsch, Robert P.; Kunk, Michael J.; Aleinikoff, John; Burton, William; Underdown, Christine; Kerwin, Charles M.

    2012-01-01

    We present new evidence for the assignment of the Neoproterozoic Massabesic Gneiss Complex of New Hampshire to the Gander terrane rather than the Avalon terrane. The majority of Avalonian (sensu stricto) igneous and meta-igneous rocks as defined in Maritime Canada have positive whole-rock ɛNd compared to more negative values for Gander rocks, although there is a region of overlap in ɛNd between the two terranes. Our samples from areas in Connecticut previously thought to be Avalonian and samples from the Willimantic dome have the same isotopic signatures as Maritime Canada Avalon. In contrast, samples from the Clinton dome of southern Connecticut plots exclusively in the Gander field. The majority of the orthogneiss samples from Lyme dome (coastal Connecticut), Pelham dome (central Massachusetts) and Massabesic Gneiss Complex also plot in the Gander field, with a few samples plotting in the overlap zone between Gander and Avalon. U-Pb age distributions of detrital zircon populations from quartzites from the Massabesic Gneiss Complex more closely approximate the data from the Lyme Dome rather than Avalon. Additionally, the similarity of the P-T-t path for the rocks of the Massabesic Gneiss Complex (established by thermobarometry and 40Ar/39Ar dating of amphibole, muscovite, biotite and K-feldspar) with that established in the Ganderian Lyme dome of southern Connecticut strengthens the assignment of these rocks to a single Gander block that docked to Laurentia during the Salinic Orogeny. The identification of Ganderian isotopic signatures for these rocks all of which show evidence for Alleghanian metamorphism, supports the hypothesis that Neoproterozoic Gander lower crustal rocks underlie southern New Hampshire, Massachusetts, and Connecticut, and that all rocks of the overlying Central Maine trough that largely escaped high-grade Alleghanian metamorphism are allochthonous. We suggest that during the Alleghanian, the docking of Gondwana caused Avalon to wedge into

  17. 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

  18. Geochronology of granulite, charnockite and gneiss in the poly-metamorphosed Gaozhou Complex (Yunkai massif), South China: Emphasis on the in-situ EMP monazite dating

    Science.gov (United States)

    Chen, Cheng-Hong; Liu, Yung-Hsin; Lee, Chi-Yu; Xiang, Hua; Zhou, Han-Wen

    2012-07-01

    The in-situ EMP (electron microprobe) monazite age dating performed directly in the polished sections, in addition to the conventional U-Pb zircon and EMP monazite age dating on grains from heavy mineral concentrates, has been applied to the granulite, charnockite and gneiss in the Gaozhou Complex of the Yunkai massif in South China. While the conventional dating systems all give Caledonian ages, the in-situ EMP monazite ages provide more information to reveal not only detailed age groups pertaining to the Caledonian orogeny but also traces of later thermal events overprinting these rocks. For granulites, although some monazites present zoning (concentric, patchy and complex) in the BSE images, no discernable age differences are observed. Resetting of the Th-U-Pb monazite dating system under the high temperature condition could be the reason. Ages of homogeneous monazite in garnet porphyroblast (ca. 440 Ma) of the garnet-cordierite granulite that match nicely with the U-Pb zircon ages are systematically older than those in the matrix (ca. 430 Ma). The same case of two age groups is also present in the orthopyroxene-biotite granulite as revealed by monazite inclusions in plagioclase and orthopyroxene and those in quartz, respectively. For charnockites, despite similar ages of ca. 430 Ma are given by monazite in biotite and zircon in the rock, significant younger ages are obtained from monazites with particular features. Relict monazites with a breakdown texture to form successive layers of apatite and allanite in the rim as well as those which are close to the biotite-chlorite microvein always show a similar age of ca. 230 Ma. Moreover, tiny monazites in close association with the garnetiferous corona mainly surrounding orthopyroxene give rise to another age group around 370 Ma. For gneissic rocks, monazites enclosed by quartz give 434 Ma and those setting in the chlorite-epidote microvein of a paragneiss yield 237 Ma, consistent with the U-Pb zircon core-rim age

  19. Zircon U-Pb dating of Archaean granite activity associated with the Jack Hills metasedimentary belt, Yilgarn Craton, Western Australia

    International Nuclear Information System (INIS)

    Pidgeon, R.T.; Wilde, S.A.; Compston, W.

    1990-01-01

    The present study investigates the timing of granitic activity associated with the Jack Hills belt and compares this with the timing of granite activity elsewhere in the Narryer Gneiss Complex in order to constrain models of craton formation. An additional aim was to investigate the granitoids as possible source rocks for detrital zircons found in metasediments within the belt, in particular the 4.2 Ga zircons which form about 12% of the detrital zircon suite from a sample of metaconglomerate. 4 refs., 2 figs

  20. SHRIMP U-Pb zircon dating of Archean core complex formatio and pancratonic strike-slip deformation in the East Pilbara Granite-Greenstone Terrain

    NARCIS (Netherlands)

    Zegers, T.E.; Nelson, D.R.; Wijbrans, J.R.; White, S.H.

    2001-01-01

    Sensitive high-resolution ion microprobe (SHRIMP) U-Pb dating of zircons from granitic rocks in the East Pilbara Granite-Greenstone Terrain has provided time constraints for main tectonic events in the Shaw Granitoid Complex and has shown that deformation was intricately related to granitoid

  1. 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

  2. Mechanical properties of granitic rocks from Gideaa, Sweden

    International Nuclear Information System (INIS)

    Ljunggren, C.; Stephansson, O.; Alm, O.; Hakami, H.; Mattila, U.

    1985-10-01

    The elastic and mechanical properties were determined for two rock types from the Gideaa study area. Gideaa is located approximately 30 km north-east of Oernskoeldsvik, Northern Sweden. The rock types that were tested were migmatitic gneiss and migmatitic granite. The following tests were conducted: - sound velocity measurements; - uniaxial compression tests with acoustic emission recording; - brazilian disc tests; - triaxial tests; - three point bending tests. All together, 12 rock samples were tested with each test method. Six samples of these were migmatic gneiss and six samples were migmatitic granite. The result shows that the migmatitic gneiss has varying strength properties with low compressive strength in comparison with its high tensile strength. The migmatitic granite, on the other hand, is found to have parameter values similar to other granitic rocks. With 15 refs. (Author)

  3. Micas in experimentally shocked gneiss

    Science.gov (United States)

    Lambert, P.; Mackinnon, I. D. R.

    1984-01-01

    Powder-propellant guns are used to shock biotites and muscovites from a gneiss at pressures between 18 and 70 GPa. It is shown that shock in biotite and muscovite can produce homogeneous and devolatilized glasses within microseconds. Shock-deformed micas are found to exhibit fracturing, kinking, and complex extinction patterns over the entire pressure range investigated. Localized melting of micas commences at 33 GPa and reaches completion at 70 GPa. Even though melted biotite and muscovite are opaque optically, they exhibit extensive microvesiculation and flow when observed with the SEM. It is confirmed through electron diffraction that biotite and muscovite have transformed to a glass. The distribution of vesicles in shock-vitrified mica reveals escape of volatiles within the short duration of the shock experiment. It is noted that experimentally shocked biotite and muscovite undergo congruent melting. It is noted that the compositions of the glasses are similar to the unshocked micas except for volatiles (H2O loss and and K loss). These unusual glasses produced from mica can be quenched by rapid cooling conditions during the shock experiment. On the basis of the results, it is pointed out that the extremely low H2O content of tektites can be reconciled with a terrestrial origin by impact.

  4. Forms of iron in soils on basement complex rocks of Kaduna state in ...

    African Journals Online (AJOL)

    The forms of iron extracted by different methods were studied in soils developed on four basement complex rocks within Northern Guinea Savanna of Nigeria namely: migmatite gneisses, older granite, quartzites and mica schists. The study shows that forms of iron generally decreased in the order of total elemental iron ...

  5. The Sao Jose do Rio Pardo mangeritic-granitic suite, south eastern Brazil

    International Nuclear Information System (INIS)

    Campos Neto, M.C.; Figueiredo, M.C.H.; Janasi, V.A.; Basei, M.A.S.; Fryer, B.J.

    1988-01-01

    In the Sao Jose do Rio Pardo region, Sao Paulo and Minas Gerais States, occur some intrusive, folded tabular bodies of mangerites associated with hornblende granitoids. The country rocks correspond to a complex association of gneisses and migmatites, locally with granulite facies assemblages. Both the magnerites and hornblende granitoids present a tectonic foliation with mineral flattening and stretching. Petrographically the mangeritic rocks are mainly dark green quartz mangerites with mesoperthite, plagioclase, quartz, hypersthene, clinopyroxene and variable amounts of hornblende, with zircon as conspicuous acessory. The pink hornblende granitoids are mainly granite s.s. exhibiting higher quartz and amphibole contents and lacking pyroxenes. Hololeucocratic alkali feldspar granites are locally associated to the hornblende granites. The textures of the mangerites and granites almost always show an important metamorphic overprinting, with relictic mesoperthite and pyroxene crystal into a granoblastic matrix. The magneritic-granitic suite is characterized by relatively high Fe/(Fe + Mg), K and HFS elements and low Ca contents, being comparable to typical anorogenic magneritic-granitic suites from Svcandinavia and North America. The Rb/Sr data indicate a Late Proterozoic metamorphic isotopic rehomogenization (930 Ma, Ro = 0.706). Geological evidence suggest that the intrusive age could be Middle Proterozoic, wich is reinforced by another Rb-Sr value of about 1300 Ma. (author) [pt

  6. lateritic weathering of granite-gneiss in obudu plateau, south ...

    African Journals Online (AJOL)

    DJFLEX

    baobab and shea-butter. The Obudu-Cattle Ranch road is the only major road that traverses the study area, running roughly East-. West. Secondary roads include Sankwala-Bayasung road, running N-S in the western part of the Obudu area. .... in hematite matrix. These concretions show a thin veneer of goethite coating. L.

  7. Lateritic weathering of granite-gneiss in Obudu Plateau, south ...

    African Journals Online (AJOL)

    ... feldspar, Hornblende, Biotite, Quartz. Most of the chemical constituents of the basement rocks in these changes. Al2O3 and Fe2O3 are enriched in the upper horizons in preference to SiO2. Kaolinite is also abundant compared to other clays whereas Ba takes the opposite trend as it increases with severity of weathering.

  8. Groundwater chemistry at depth in granites and gneisses

    International Nuclear Information System (INIS)

    Jacks, G.

    1978-04-01

    The place considered for a radioactive waste storage is beneath a local water divide along the eastcoast of southern and central Sweden. pH is fixed by the carbonate system and the ground waters can be expected to be saturated with respect to calcite. pH may vary from about 7,2 to about 8,5 with the most probable value around 8. The content of Cl - is difficult to asses as it is associated with the presence of relict sea water. Relict sea waters are linked to the postglacial clays and low sections of the terrain. Near local water divides the content of Cl - is low approaching the atmospheric contribution or below 10 mg/l. The content of F - is restricted by the solubility of fluorspar and may be about 7 mg/l as a maximum, but normally 3,5 mg/l or lower. SO 4 - seems to be of the same order as the atmospheric contribution or about 15 mg/l. In the deep boreholes sampled so far the contents have been lower. The partial pressure of oxygen in the ground water should be very low. An increasing ironcontent towards depth is likely. Organic substance in the order of a few tenths of mg/l may be present. The local heating of the water close to the storage may bring about precipitation of calcite while the subsequent cooling when the water leaves the storage may result in precipitation of aluminiumsilicates. This may have a sealing effect of the rock

  9. Dome-shaped Form for the Granite Pluton of the Lavras do Sul Intrusive Complex (South Brazil) Revealed by Magnetic Fabrics

    Science.gov (United States)

    Raposo, M. B.; Gastal, M. P.

    2008-12-01

    Magnetic fabric and rock magnetism studies were performed on "isotropic" granites from the main intrusion of the Lavras do Sul intrusive Complex pluton (LSIC, Rio Grande do Sul). This intrusion is a roughly N-S elongated ellipsoidal pluton (12x18km) composed of alkali-calcic and alkaline granitoids, with the alkaline granites at the margin of the pluton. Magnetic fabrics were determined by applying both anisotropy of low- field magnetic susceptibility (AMS) and anisotropy of anhysteretic remanent magnetization (AARM). The AARM fabrics are coaxial with AMS fabrics. The parallelism between the AMS and AARM tensors excludes the presence of a single domain (SD) effect on the AMS fabric of the granites. Several rock-magnetism experiments performed in one specimen from each sampled site show that for all sites magnetic susceptibility is dominantly carried by ferromagnetic minerals, and mainly coarse-grained magnetite carries the magnetic fabrics. Fabric patterns (lineation and foliation) in the granites were successful determined by applying the magnetic methods. Magnetic lineations (Kmax) are gently plunging and roughly parallel to pluton elongation whereas the magnetic foliations (normal to Kmin) tend to follow the contacts between the granites. They are outerwardly gently dipping inside the pluton and become either steeply southwesterly dipping or vertical towards its margin. The lack of solid-state deformation at outcrops and at thin sections scales precludes deformation after full crystallization of the granites from the LSIC pluton. This evidence allows us to interpret magnetic fabric in the analyzed granites as primarily the result of internal magma chamber dynamics reflecting magma flow. The foliation pattern displays a dome-shaped form for the granites. However, the alkaline granites (syenogranite and perthite granite), which outcrop in the south of the studied area have an inward-dipping foliation whereas for the other granites it dips outwards. It suggests

  10. Rb-Sr systematics of granitoids of the central gneissic complex, Arunachal Himalaya: implications on tectonism, stratigraphy and source

    International Nuclear Information System (INIS)

    Dikshitulu, G.R.; Dhana Raju, R.; Pandey, B.K.; Krishna, Veena

    1995-01-01

    Precambrian central gneissic complex (CGC) in the Kameng district of Arunachal Pradesh comprises the oldest Sela group thrusting over the Bomdila group, with the Salari group being the youngest. Augen gneiss of the Bomdila group, granite of the Salari group and hornblende granite gneiss of the Sela group define Rb-Sr isochron ages of 1914±23, 1536±60 and 481± 23 Ma, respectively. The 481 Ma age on the hornblende gneiss from the oldest Sela group is attributed to the resetting of Rb-Sr clock due to tectonic imprint of the main central thrust (MCT). The 1914 Ma age of the augen gneiss, the oldest reported so far from the Arunachal Himalaya, is either the emplacement age or latest metamorphic event. The 1536 Ma old emplacement age of the granite intruding the black shale of the Salari group disproves the hitherto considered Gondwana age for the black shale, and, thus, necessitates revision in its chronostratigraphy ( 87 Sr/ 86 Sr), of the hornblende granite gneiss and Salari granite is high (0.719 and 0.709) indicating a crustal source for these, whereas it is low for the augen gneiss (0.703) suggesting an inherited signature of the upper mantle source together with some crustal contamination. Rb-Sr whole-rock isochron ages from the Arunachal Himalaya are correlatable with those reported from other parts of the Indian Himalaya. These cumulatively point to at least three major periods of activity in the Himalaya at ca. 2060±250, 1530±90 and 530± 75 Ma. (author). 22 refs., 2 figs., 3 tabs

  11. Uranium deposits in granitic rocks

    International Nuclear Information System (INIS)

    Nishimori, R.K.; Ragland, P.C.; Rogers, J.J.W.; Greenberg, J.K.

    1977-01-01

    This report is a review of published data bearing on the geology and origin of uranium deposits in granitic, pegmatitic and migmatitic rocks with the aim of assisting in the development of predictive criteria for the search for similar deposits in the U.S. Efforts were concentrated on the so-called ''porphyry'' uranium deposits. Two types of uranium deposits are primarily considered: deposits in pegmatites and alaskites in gneiss terrains, and disseminations of uranium in high-level granites. In Chapter 1 of this report, the general data on the distribution of uranium in igneous and metamorphic rocks are reviewed. Chapter 2 contains some comments on the classification of uranium deposits associated with igneous rocks and a summary of the main features of the geology of uranium deposits in granites. General concepts of the behavior of uranium in granites during crustal evolution are reviewed in Chapter 3. Also included is a discussion of the relationship of uranium mineralization in granites to the general evolution of mobile belts, plus the influence of magmatic and post-magmatic processes on the distribution of uranium in igneous rocks and related ore deposits. Chapter 4 relates the results of experimental studies on the crystallization of granites to some of the geologic features of uranium deposits in pegmatites and alaskites in high-grade metamorphic terrains. Potential or favorable areas for igneous uranium deposits in the U.S.A. are delineated in Chapter 5. Data on the geology of specific uranium deposits in granitic rocks are contained in Appendix 1. A compilation of igneous rock formations containing greater than 10 ppM uranium is included in Appendix 2. Appendix 3 is a report on the results of a visit to the Roessing area. Appendix 4 is a report on a field excursion to eastern Canada

  12. Genesis of a zoned granite stock, Seward Peninsula, Alaska

    Science.gov (United States)

    Hudson, Travis

    1977-01-01

    A composite epizonal stock of biotite granite has intruded a diverse assemblage of metamorphic rocks in the Serpentine Hot Springs area of north-central Seward Peninsula, Alaska. The metamorphic rocks include amphibolite-facies orthogneiss and paragneiss, greenschist-facies fine-grained siliceous and graphitic metasediments, and a variety of carbonate rocks. Lithologic units within the metamorphic terrane trend generally north-northeast and dip moderately toward the southeast. Thrust faults locally juxtapose lithologic units in the metamorphic assemblage, and normal faults displace both the metamorphic rocks and some parts of the granite stock. The gneisses and graphitic metasediments are believed to be late Precambrian in age, but the carbonate rocks are in part Paleozoic. Dating by the potassium-argon method indicates that the granite stock is Late Cretaceous. The stock has sharp discordant contacts, beyond which is a well-developed thermal aureole with rocks of hornblende hornfels facies. The average mode of the granite is 29 percent plagioclase, 31 percent quartz, 36 percent K-feldspar, and 4 percent biotite. Accessory minerals include apatite, magnetite, sphene, allanite, and zircon. Late-stage or deuteric minerals include muscovite, fluorite, tourmaline, quartz, and albite. The stock is a zoned complex containing rocks with several textural facies that are present in four partly concentric zones. Zone 1 is a discontinuous border unit, containing fine- to coarse-grained biotite granite, that grades inward into zone 2. Zone 2 consists of porphyritic biotite granite with oriented phenocrysts of pinkish-gray microcline in a coarse-grained equigranular groundmass of plagioclase, quartz, and biotite. It is in sharp, concordant to discordant contact with rocks of zone 3. Zone 3 consists of seriate-textured biotite granite that has been intruded by bodies of porphyritic biotite granite containing phenocrysts of plagioclase, K-feldspar, quartz, and biotite in an

  13. Low-temperature thermochronologic constraints on cooling and exhumation trends along conjugate margins, within core complexes and eclogite-bearing gneiss domes of the Woodlark rift system of eastern Papua New Guinea

    Science.gov (United States)

    Fitzgerald, P. G.; Baldwin, S.; Bermudez, M. A.; Miller, S. R.; Webb, L. E.; Little, T.

    2012-12-01

    In eastern Papua New Guinea, active sea-floor spreading within the Woodlark Basin has been propagating westward since at least 6 Ma into heterogeneous crust of the Woodlark Rift. The seafloor spreading system divides the northern conjugate margin (Woodlark Rise) from the southern margin (Pocklington Rise). West of the seafloor spreading rift-tip are high-standing extensional gneiss domes and core complexes of the D'Entrecasteaux Islands (DEI). Domes comprise amphibolite and eclogite-facies gneisses, and Pleistocene granitoid intrusions. Flanked by mylonitic shear zone carapaces and normal faults, the domes are juxtaposed against an upper plate that includes ultramafic rocks and gabbro, correlated with the Papuan ultramafic belt. Petrologic and structural evidence from the DEI has been interpreted as evidence for diapiric ascent of the largely felsic domes, with thermo-mechanical modeling proposing (U)HP exhumation in terms of diapiric flow aided by propagating extension, with feedback between the two. Core complexes lacking evidence for diapiric-aided exhumation include the Prevost Range (eastern Normanby Island), Dayman Dome (Papuan Peninsula), and Misima Island (southern conjugate margin). Thermochronology is being applied to understand the thermal and exhumation history, and hence help constrain mechanisms of (U)HP exhumation. AFT and AHe ages from samples near sea-level along conjugate margins and DEI range from ca. 12 Ma to <1 Ma, generally decreasing from east to west, although with some localized variation. Confined track length distributions (CTLD), obtained using 252Cf implantation, generally indicate rapid cooling (means ≥~14 μm), except on Goodenough Island, the western-most and highest-standing dome. On Goodenough Island, samples from the core zone have AFT ages from ~3 - <1 Ma with age decreasing with decreasing elevation. Core zone samples have mean track lengths (7-13 μm) and are positively skewed, whereas samples from shear zones are younger (<1

  14. Strain and displacement in the harts range detachment zone: a structural study of the Bruna Gneiss from the western margin of the Entia Dome, central Australia

    Science.gov (United States)

    James, P. R.; Macdonald, P.; Parker, M.

    1989-02-01

    A detailed structural and strain study has been carried out on the Bruna granitic gneiss and its bounding thrusts from the western margin of the Entia Dome in the eastern Harts Ranges. The zone containing the Bruna Gneiss has been described recently as comprising the Harts Range Detachment Zone (HRDZ), a major low-angle lithospheric detachment along which both major extensional and contractional movements have occurred. The Bruna Gneiss contains a ductile fabric which varies from an augen streaky foliation through a ribbon gneiss to protomylonite and mylonite, in what is predominantly a granitic gneiss. Conformably overlying the Bruna Gneiss is a distinctive dark-coloured megacrystic gneiss layer which intruded independently from the bulk of the Bruna Gneiss and followed a different subsequent strain history. Principal stretch lineations are consistently north plunging or horizontal N-S except where folded. The Bruna Gneiss fabrics are complexly folded about axes in an asymmetric manner which suggests interruption of ductile slip and crumpling of the fabrics followed by continuing slip on other discrete surfaces and shear zones. Strain measurements of elongated feldspars and aggregates indicate moderate to high strains with predominantly plane-strain symmetries. Strain is partitioned into planar parallel zones and suggests dominant heterogeneous simple shear as the main non-coaxial flow mechanism. Flattening strains occur near the bases of two major zones and constrictional strains occur within some zones. A strain integration profile across the detachment zone produces total displacements of only a few kilometres, suggesting that much of the overall indicated displacement is partitioned into the discrete bounding thrusts. Asymmetric augen, pressure shadows and shear bands provide kinematic indicators in the Bruna Gneiss. Most show reverse sense displacement of the overlying Harts Range Cover in a southerly direction over the Entia Gneiss basement. Opposite

  15. Rapid extensional unroofing of a granite-migmatite dome with relics of high-pressure rocks, the Podolsko complex, Bohemian Massif

    Czech Academy of Sciences Publication Activity Database

    Žák, J.; Sláma, Jiří; Burjak, M.

    2017-01-01

    Roč. 154, č. 2 (2017), s. 354-380 ISSN 0016-7568 Institutional support: RVO:67985831 Keywords : anisotropy of magnetic susceptibility (AMS) * granite-migmatite dome * exhumation * metamorphic core complex * U-Pb zircon geochronology Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 1.965, year: 2016

  16. Geology, petrography and geochemistry of the A-type granites from the Morro Redondo Complex (PR-SC, southern Brazil, Graciosa Province

    Directory of Open Access Journals (Sweden)

    FREDERICO C.J. VILALVA

    2014-03-01

    Full Text Available The Morro Redondo Complex is one of the most important occurrences of the Graciosa A-type Province, southern Brazil. It consists of the Papanduva and Quiriri granitic plutons and a contemporaneous bimodal volcanic association. The Papanduva Pluton includes massive and deformed peralkaline alkali-feldspar granites with Na-Ca and Na-amphiboles and clinopyroxenes. The deformed types are the most evolved rocks in the province and carry rare ‘agpaitic’ minerals, some being described for the first time in granites from Brazil. The larger Quiriri Pluton comprises massive, slightly peraluminous, biotite syeno- and monzogranites with rare Ca-amphibole. Biotite compositions are relatively homogeneous, whereas sodic amphiboles and clinopyroxenes show increasing Na and Fe3+ evolving paths. The Morro Redondo granites are ferroan, with high SiO2, alkalis and HFSE contents; the peralkaline types registering the highest fe#. LILE and HFSE abundances increase with the agpaitic index and the most evolved are HHP granites, with radiogenic heat production up to 5.7 µWm–3. Geothermobarometric estimates indicate emplacement under low pressures (∼100 MPa, at temperatures up to 850-800 °C, and relatively reduced (QFM and oxidized (+1 REPLACE_LT ΔQFM REPLACE_LT +3 environments for the Papanduva and Quiriri Plutons, respectively. In both cases, melts evolved to relatively high oxidation states upon crystallization progress.

  17. Bokan Mountain peralkaline granitic complex, Alexander terrane (southeastern Alaska): evidence for Early Jurassic rifting prior to accretion with North America

    Science.gov (United States)

    Dostal, Jaroslav; Karl, Susan M.; Keppie, J. Duncan; Kontak, Daniel J.; Shellnutt, J. Gregory

    2013-01-01

    The circular Bokan Mountain complex (BMC) on southern Prince of Wales Island, southernmost Alaska, is a Jurassic peralkaline granitic intrusion about 3 km in diameter that crosscuts igneous and metasedimentary rocks of the Alexander terrane. The BMC hosts significant rare metal (rare earth elements, Y, U, Th, Zr, and Nb) mineralization related to the last stage of BMC emplacement. U–Pb (zircon) and 40Ar/39Ar (amphibole and whole-rock) geochronology indicates the following sequence of intrusive activity: (i) a Paleozoic basement composed mainly of 469 ± 4 Ma granitic rocks; (ii) intrusion of the BMC at 177 ± 1 Ma followed by rapid cooling through ca. 550 °C at 176 ± 1 Ma that was synchronous with mineralization associated with vertical, WNW-trending pegmatites, felsic dikes, and aegirine–fluorite veins and late-stage, sinistral shear deformation; and (iii) intrusion of crosscutting lamprophyre dikes at >150 Ma and again at ca. 105 Ma. The peralkaline nature of the BMC and the WNW trend of associated dikes suggest intrusion during NE–SW rifting that was followed by NE–SW shortening during the waning stages of BMC emplacement. The 177 Ma BMC was synchronous with other magmatic centres in the Alexander terrane, such as (1) the Dora Bay peralkaline stock and (2) the bimodal Moffatt volcanic suite located ∼30 km north and ∼100 km SE of the BMC, respectively. This regional magmatism is interpreted to represent a regional extensional event that precedes deposition of the Late Jurassic – Cretaceous Gravina sequence that oversteps the Wrangellia and Alexander exotic accreted terranes and the Taku and Yukon–Tanana pericratonic terranes of the Canadian–Alaskan Cordillera.

  18. U-Pb age in zircon of intrusive granite at Acopiara complex, Crystal region, domain Central Ceara, Brazil; Idade U-PB em zircao de granito intrusivo no Complexo Acopiara, Regiao de Cristais, Dominio Ceara Central

    Energy Technology Data Exchange (ETDEWEB)

    Neri, T.F.O.; Hamelak, G.M.S.; Azevedo, L.R.; Mattos, I.C.; Verissimo, C.U.V.; Nogueira Neto, J.A., E-mail: neri@ufc.br [Universidade Federal do Ceara (UFC), Fortaleza (Brazil). Departamento de Geologia; Lima, M.N. [Universidade Federal de Goias (UFGO), Goiania, GO (Brazil). Curso de Geologia

    2015-07-01

    Granitic body mineralogically composed by two micas, located at Crystal region, Ceara Central domain and intruded into lithotypes from Acopiara complex, provided an age of ∼526 Ma, indicating important period of magma generation of granitic composition associated with crustal anatexia, during Paleozoic.

  19. Effect of chemical composition on the electrical conductivity of gneiss at high temperatures and pressures

    Science.gov (United States)

    Dai, Lidong; Sun, Wenqing; Li, Heping; Hu, Haiying; Wu, Lei; Jiang, Jianjun

    2018-03-01

    The electrical conductivity of gneiss samples with different chemical compositions (WA = Na2O + K2O + CaO = 7.12, 7.27 and 7.64 % weight percent) was measured using a complex impedance spectroscopic technique at 623-1073 K and 1.5 GPa and a frequency range of 10-1 to 106 Hz. Simultaneously, a pressure effect on the electrical conductivity was also determined for the WA = 7.12 % gneiss. The results indicated that the gneiss conductivities markedly increase with total alkali and calcium ion content. The sample conductivity and temperature conform to an Arrhenius relationship within a certain temperature range. The influence of pressure on gneiss conductivity is weaker than temperature, although conductivity still increases with pressure. According to various ranges of activation enthalpy (0.35-0.52 and 0.76-0.87 eV) at 1.5 GPa, two main conduction mechanisms are suggested that dominate the electrical conductivity of gneiss: impurity conduction in the lower-temperature region and ionic conduction (charge carriers are K+, Na+ and Ca2+) in the higher-temperature region. The electrical conductivity of gneiss with various chemical compositions cannot be used to interpret the high conductivity anomalies in the Dabie-Sulu ultrahigh-pressure metamorphic belt. However, the conductivity-depth profiles for gneiss may provide an important constraint on the interpretation of field magnetotelluric conductivity results in the regional metamorphic belt.

  20. Petrography and geochronology (U/Pb-Sm/Nd) the Passagem Granite, Pensamiento Granitoid Complex, Paragua Terrane, SW Amazon Craton, Mato Grosso, Brazil

    International Nuclear Information System (INIS)

    Jesus, Gisely Carmo de; Sousa, Maria Zelia Aguiar de; Ruiz, Amarildo Salina; Matos, Joao Batista de

    2010-01-01

    The Passagem granite includes stocks, plugs and dikes located in the Ricardo Franco hill - Vila Bela da Santissima Trindade region - state of Mato Grosso, central Brazil. The Passagem Granite is included in the Paragua terrane - SW Amazonian Craton. It consists of isotropic monzogranite, sienogranite and more rarely granodiorites with leucocratic dark gray to white color. These rocks range from hypidomorphic inequigranular to xenomorphic texture, fine to medium grained. Biotite is the only primary mafic present as essential phase and characterize an expanded slightly acid sequence formed by a sub-alkaline magmatism of high-potassium calc-alkaline, slightly peraluminous composition from arc magmatic tectonic environment during a post-collisional period. Mechanism of fractional crystallization of plagioclase, biotite, titanite, apatite and zircon associated with simultaneous crustal assimilation are suggested for the evolution of these rocks. The results support the hypothesis of a post-collisional magmatism in the Paragua terrane at 1284 +- 20 Ma corresponding to the crystallization age of the Passagem granite. This paper propose that Passagem Granite represents as an extension in Brazilian terrane of the Pensamiento Granitoid Complex. (author)

  1. High-K granites of the Rum Jungle Complex, N-Australia: Insights into the Late Archean crustal evolution of the North Australian Craton

    Science.gov (United States)

    Drüppel, K.; McCready, A. J.; Stumpfl, E. F.

    2009-08-01

    The Late Archean (c. 2.54-2.52 Ga) high-K granitoids of the Rum Jungle Complex, Northern Australia, display the igneous mineral assemblage of K-feldspar, quartz, plagioclase, biotite, and magnetite, and accessories such as zircon, monazite, titanite, allanite, apatite, and ilmenite. The granites underwent a variably severe greenschist facies alteration and associated deformation during the Barramundi Orogeny (1.88-1.85 Ga). The K-rich granitoids have variable compositions, mainly comprising syenogranite and quartz-monzonite. They can be subdivided into two major groups, (1) felsic granites and (2) intermediate to felsic granites, quartz-monzonites, and diorite. The felsic group (69-76 wt.% SiO 2) shares many features with typical Late Archean potassic granites. They are K- and LILE-rich and show marked depletion in Sr and Eu and the high field strength elements (HFSE), particularly Nb and Ti, relative to LILE and LREE. Compared to the average upper crust they have anomalously high Th (up to 123 ppm) and U (up to 40 ppm). The intermediate to felsic group (56-69 wt.% SiO 2) differs from the felsic group in having weakly lower Th and U but higher Mg#, Ti, Ba, Sr, Ni, Cr and REE, with a less pronounced negative Eu anomaly. This group displays well-defined trends in Harker diagrams, involving a negative correlation of Si with Sr, Ca, Na, and P whereas K, Rb, and Ba increase in the same direction, suggesting fractional crystallization of feldspar was more prominent than in the felsic suite. The mineralogical and geochemical characteristics of the felsic group are consistent with granite formation by intracrustal melting of plagioclase-rich igneous protoliths, probably of tonaltic to granodioritic composition, at moderate crustal levels. The intermediate to felsic granites, on the other hand, appear to be the products of mantle-crust interaction, possibly by melting of or mixing with more mafic igneous rocks. As evidenced by the presence of older inherited zircons crustal

  2. The Lagoa Real subalkaline granitic complex (south Bahia, Brazil): a source for uranium mineralizations associated with Na-Ca metasomatism

    International Nuclear Information System (INIS)

    Maruejol, P.; Cuney, M.; Poty, B.; Neto, A.M.

    1987-01-01

    In the central zone of the Sao Francisco Craton (South Bahia), the lower Proterozoic Lagoa Real granites and orthogneisses overthrust to the West the younger Urandi and Espinhaco metamorphic series, probably a late Brazilian event. This thrust is related to the regional metamorphism (amphibolite facies) of the Lagoa Real granites and induces a reverse HP metamorphism in the over thrusted series. Undeformed granites (sao Timoeto type) present two feldspars, perthitic orthoclase largely predominant over plagioclase (oligoclase ≥ albite), blue quartz, Fe-rich amphibole and biotite ± clinopyroxene assemblages, ilmenite ≥ magnetite, zircon, apatite, allanite and Nb ± Ti-REE oxides and silicates. The crystallization of the granites begins at high temperature and under low fO 2 and P H2O conditions. Fractional crystallization of pyroxene and plagioclase leads to silica enrichment during magmatic differentiation. Increasing fO 2 and P H2O are observed during this evolution. Orthogneisses show strongly recrystallized paragenesis: equal abundance of non-perthitic microcline and plagioclase (oligoclase ≤ albite), quartz, more Al-rich amphibole and biotite, magnetite, sphene, zircon, allanite, Nb ± Ti-REE oxides and silicates, and ± apatite. HT Na and Ca metasomatism occurs 330 Ma later than granite emplacement and is synchronous with important uranium mineralizations. Major elements and trace-elements geochemistry of the granites and orthogneisses indicate subalkaline to alkaline typology. Incompatible behaviour of Th, REE, Y, Zr, Nb, and F points out a convergence with alkaline magmatism. CI, F, Th, Y, REE, NB enrichments and Ba, Sr depletions are also related to a late magmatic stage. U-Th-rich and metamict accessory minerals of the granites represent a favorabl source for the Lagoa Real uranium ore-deposits [pt

  3. 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

  4. Component geochronology in the polyphase ca. 3920 Ma Acasta Gneiss

    Science.gov (United States)

    Mojzsis, Stephen J.; Cates, Nicole L.; Caro, Guillaume; Trail, Dustin; Abramov, Oleg; Guitreau, Martin; Blichert-Toft, Janne; Hopkins, Michelle D.; Bleeker, Wouter

    2014-01-01

    The oldest compiled U–Pb zircon ages for the Acasta Gneiss Complex in the Northwest Territories of Canada span about 4050–3850 Ma; yet older ca. 4200 Ma xenocrystic U–Pb zircon ages have also been reported for this terrane. The AGC expresses at least 25 km2 of outcrop exposure, but only a small subset of this has been documented in the detail required to investigate a complex history and resolve disputes over emplacement ages. To better understand this history, we combined new ion microprobe235,238U–207,206Pb zircon geochronology with whole-rock and zircon rare earth element compositions ([REE]zirc), Ti-in-zircon thermometry (Tixln) and 147Sm–143Nd geochronology for an individual subdivided ∼60 cm2 slab of Acasta banded gneiss comprising five separate lithologic components. Results were compared to other variably deformed granitoid-gneisses and plagioclase-hornblende rocks from elsewhere in the AGC. We show that different gneissic components carry distinct [Th/U]zirc vs. Tixln and [REE]zirc signatures correlative with different zircon U–Pb age populations and WR compositions, but not with 147Sm–143Nd isotope systematics. Modeled  [REE] from lattice-strain theory reconciles only the ca. 3920 Ma zircons with the oldest component that also preserves strong positive Eu∗ anomalies. Magmas which gave rise to the somewhat older (inherited) ca. 4020 Ma AGC zircon age population formed at ∼IW (iron–wüstite) to gneisses.

  5. Hybridization in the subvolcanic Jaala-Iitti complex and its petrogenetic relation to rapakivi granites and associated mafic rocks of southeastern Finland

    Directory of Open Access Journals (Sweden)

    Salonsaari, P.T.

    1995-10-01

    Full Text Available The 1630 Ma Jaala-Iitti complex is an example of bimodal rapakivi granite magmatism in which the interaction of granite and diabase magmas have led locally to hybridization. The dyke-like complex is situated at the northwestern margin of the Wiborg rapakivi batholith in southeastern Finland, cutting both the Proterozoic Svecofennian metamorphic crust and the Wiborg batholith. The complex consists mainly of non-hybridized compositionally homogeneous granites, i.e., hornblende granite and hornblende-quartz-feldspar porphyry which represent the felsic end-member (ca. 68 wt% SiO2 of the complex. The mafic end-member (ca. 51 wt% SiO2 is present as globules of disaggregated Fe-rich tholeiitic magma forming magmatic mafic enclaves (MMEs and composite MMEs. Commonly MMEs and large (up to 2 metres in diameter pillow-like MMEs show magma mixing and mingling characteristics. Hybrid rocks in the complex are monzogranitic and are characterized by (a quartz grains and quartz aggregates (partially melted xenoliths mantled by amphibole rims (ocellar texture with occasional augite, (b alkali feldspar megacrysts mantled by a micrographic plagioclase-quartz intergrowth, and (c alkali feldspar megacrysts mantled by a plagioclase shell with occasional amphibole inclusions. These textures are also found in hybrid MMEs and especially in pillow-like MMEs. Alkali feldspar and quartz megacrysts in hybrid rocks are derived from partially crystallized felsic magma and from disaggregated rapakivi granite and granitoid xenoliths whereas in the MMEs the xenocrysts are solely derived from partially crystallized felsic magma. Disaggregation of the mafic magma to form MMEs and equilibration with the host have produced micro-enclaves and recrystallized borders of MMEs. Disaggregation of the mafic magma has also produced needle-like apatite crystals incorporated from the mafic magma into the hybrid magma; acicular apatite is typical in MMEs and pillow-like MMEs and is indicative

  6. Evolution of the Archean continental crust in the nucleus of the Yangtze block: Evidence from geochemistry of 3.0 Ga TTG gneisses in the Kongling high-grade metamorphic terrane, South China

    Science.gov (United States)

    Qiu, Xiao-Fei; Ling, Wen-Li; Liu, Xiao-Ming; Lu, Shan-Song; Jiang, Tuo; Wei, Yun-Xu; Peng, Lian-Hong; Tan, Juan-Juan

    2018-04-01

    Archean Tonalite-Trondhjemite-Granodiorite (TTG) rocks are scattered within the Kongling high-grade metamorphic terrane (KHMT) in the northern South China block. A comprehensive geochronological and geochemical study is carried out on the Taoyuan granitic gneisses, a newly recognized TTG suite in the northwestern KHMT. This suite has long been regarded as a Mesoproterozoic magmatic pluton, but U-Pb zircon ages of 2994 ± 22 Ma and 2970 ± 15 Ma are obtained by LA-ICP-MS method in this study. The Taoyuan gneiss suite is trondhjemitic in composition, and has high SiO2 (67.80-74.93 wt.%), Na2O (5.11-5.81 wt.%) contents with Na2O/K2O ratios greater than unity, and low Ni (2.56-7.61 ppm), Cr (1.26-7.67 ppm), Yb (0.32-0.82 ppm) and Y (4.48-11.5 ppm) contents. Plots show large variation in La/Yb and Sr/Y ratios and pronounced depletion in Nb, Ta and Ti in the primitive mantle-normalized spiderdiagram. The gneiss suite also displays two-stage Nd model ages close to its crystallization age with corresponding εNd(t) values of -2.5 to +3.5. It is thus suggested that the Taoyuan gneisses, in fact, is part of the Archean Kongling basement complex. Geochemical evidence implies that the TTG rocks may be derived from partial melting of subducted oceanic crust from a garnetiferous amphibolite source with residual assemblage of garnet + amphibole + plagioclase. Our study further indicates that the nucleus of the Yangtze block might experience a juvenile continental crustal growth during Mesoarchean. We also suggest that the Yangtze block may have its own crustal evolutionary history independent from the North China craton and the Tarim block before Paleoproterozoic.

  7. Granitic magma emplacement and deformation during early-orogenic syn-convergent transtension: The Stare Sedlo complex, Bohemian Massif

    Czech Academy of Sciences Publication Activity Database

    Tomek, Filip; Žák, J.; Chadima, Martin

    2015-01-01

    Roč. 87, JUL (2015), s. 50-66 ISSN 0264-3707 Institutional support: RVO:67985831 Keywords : anisotropy of magnetic susceptibility (AMS) * Bohemian Massif * pluton emplacement * granite * transtension * Variscan orogeny Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.926, year: 2015

  8. Radar, geologic, airborne gamma ray and Landsat TM digital data integration for geological mapping of the Estrela granite complex (Para State)

    International Nuclear Information System (INIS)

    Cunha, Edson Ricardo Soares Pereira da

    2002-01-01

    This work is focused on the geotectonic context of the Carajas Mineral Province, Amazon Craton, which represents the most important Brazilian Mineral Province and hosts iron, cooper, gold, manganese and nickel deposits. At the end of Archean age, during the techno-metamorphic evolution, moderated alkaline granitoids were generated, such as, Estrela Granite Complex (EGC). This work has used digital integration products with the purpose of study the granite suite, its host rock, and the surrounded area. The digital integrated data were gamma-ray and geological data with satellite images (SAR-SAREX e TM-Landsat). The geophysics data, originally in 32 bits and grid format, were interpolated and converted to 8 bits images. The geological data (facies map) was digitalized and converted to a raster format. The remote sensing images were geometrically corrected to guarantee an accuracy on the geological mapping. On the data processing phase, SAR images were digital integrated with gamma-ray data, TM-Landsat image and the raster facies map. The IHS transformation was used as the technique to integrate the multi-source data. On the photogeological interpretation, SAR data were extremely important to permit the extraction of the main tectonic lineaments which occur on the following directions: +/- N45W, +/- N70W, +/- NS, +/- N20E, +/- N45E e +/- N75E. This procedure was done both in analogic and automatic form, being the automatic process more useful to complement information in the extracting process. Among the digital products generated, SAR/GAMA products (uranium, thorium and total count) were the ones that give the most important contribution. The interpretation of the SAR/GAMA's products added to the field campaign have allowed to map the limits of units that occur in the region and four facies of the Estrela Granite Complex were detected. The origin of the granite suite might be related to a magmatic differentiation or to distinct intrusion pulses. The use of the

  9. The uranium behaviour during rock-water interaction in the granites from the Itu complex (Sao Paulo, Brazil): a laboratory study

    International Nuclear Information System (INIS)

    Silva, Helen S.B. da; Marques, Leila S.; Kawauchi, Roberto K.

    2011-01-01

    In order to elucidate the mechanisms involved in the process of uranium leaching due to the rock-water interaction in the granitic rocks from Itu Complex (Sao Paulo, Brazil), an experimental arrangement was developed and built. About 2.5kg of crushed rock fragments from Cabreuva and Indaiatuba Intrusions were maintained at room temperature within a glass flask filled with circulating water. The percolating water was removed periodically (from 10 to 30 days) for uranium analysis and then replaced by an equal volume of fresh water. Alpha spectrometry was used to determine the activity concentrations of 234 U and 238 U, and 234 U/ 238 U activity ratios, of the waters as well as of the granites. The results for both samples showed that most of the uranium is leached in the first days after the contact between rock and water. The 234 U/ 238 U activity ratios were significantly greater than unity, indicating radioactive disequilibrium between those isotopes, probably due to alpha recoil. Although the uranium activity concentrations in the water samples diminished with the increasing of time, it was not observed considerable variations of the 234 U/ 238 U activity ratios. It was also noticed that, the amount of leached uranium as well as the 234 U/ 238 U activity ratios are characteristics of each sample submitted to leaching, reflecting the differences of the granite facies mineralogy.(author)

  10. The uranium behaviour during rock-water interaction in the granites from the Itu complex (Sao Paulo, Brazil): a laboratory study

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Helen S.B. da; Marques, Leila S.; Kawauchi, Roberto K., E-mail: leila@iag.usp.br, E-mail: keiji@iag.usp.br [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas. Universidade de Sao Paulo (USP), SP (Brazil)

    2011-07-01

    In order to elucidate the mechanisms involved in the process of uranium leaching due to the rock-water interaction in the granitic rocks from Itu Complex (Sao Paulo, Brazil), an experimental arrangement was developed and built. About 2.5kg of crushed rock fragments from Cabreuva and Indaiatuba Intrusions were maintained at room temperature within a glass flask filled with circulating water. The percolating water was removed periodically (from 10 to 30 days) for uranium analysis and then replaced by an equal volume of fresh water. Alpha spectrometry was used to determine the activity concentrations of {sup 234}U and {sup 238}U, and {sup 234}U/{sup 238}U activity ratios, of the waters as well as of the granites. The results for both samples showed that most of the uranium is leached in the first days after the contact between rock and water. The {sup 234}U/{sup 238}U activity ratios were significantly greater than unity, indicating radioactive disequilibrium between those isotopes, probably due to alpha recoil. Although the uranium activity concentrations in the water samples diminished with the increasing of time, it was not observed considerable variations of the {sup 234}U/{sup 238}U activity ratios. It was also noticed that, the amount of leached uranium as well as the {sup 234}U/{sup 238}U activity ratios are characteristics of each sample submitted to leaching, reflecting the differences of the granite facies mineralogy.(author)

  11. Uranium in granites

    International Nuclear Information System (INIS)

    Maurice, Y.T.

    1982-01-01

    Recent research activities of the Canadian Uranium in Granites Study are presented in 18 papers and 3 abstracts. 'Granites' is used as a generic term for granitoids, granitic rocks, and plutonic rocks

  12. Sm/Nd and whole rock geochemistry characterization of the Serra Branca granite: evidence of Archean crust in the Pajeu Paraiba fold belt

    International Nuclear Information System (INIS)

    Guimaraes, Ignez de Pinho; Silva Filho, Adejardo F. da

    1997-01-01

    This work presents and discusses the geochemical and Samarium-Neodymium (SM/Nd) isotopic data for the Serra Branca granite. The Serra Branca granite constitutes one among several brasiliano (=Pan African) intrusions of the transversal zone of the Borborema Tectonica Province, northeastern of Brazil. It is intruded into gneisses and migmatites from the Alto Pajeu Terrain (TAP). The Alto Pajeu Terrain comprises mainly metasediments with minor volcanic contributions and the brasiliano magmatism is restrict to the TAP. After presenting the geological and petrographical considerations, the study shows the Sm-Nd data and concludes that the geochemical and Sm-Nd isotopic signatures of the Serra Branca complex point to a magma generation in the contact zone between an Archean and a Tranzamazonian crust, during decompression, which followed the Brasiliano collisional event

  13. Transpressional granite-emplacement model: Structural and magnetic study of the Pan-African Bandja granitic pluton (West Cameroon)

    Science.gov (United States)

    Sandjo, A. F. Yakeu; Njanko, T.; Njonfang, E.; Errami, E.; Rochette, P.; Fozing, E.

    2016-02-01

    The Pan-African NE-SW elongated Bandja granitic pluton, located at the western part of the Pan-African belt in Cameroon, is a K-feldspar megacryst granite. It is emplaced in banded gneiss and its NW border underwent mylonitization. The magmatic foliation shows NE-SW and NNE-SSW strike directions with moderate to strong dip respectively in its northern and central parts. This mostly, ferromagnetic granite displays magnetic fabrics carried by magnetite and characterized by (i) magnetic foliation with best poles at 295/34, 283/33 and 35/59 respectively in its northern, central and southern parts and (ii) a subhorizontal magnetic lineation with best line at 37/8, 191/9 and 267/22 respectively in the northern, central and southern parts. Magnetic lineation shows an `S' shape trend that allows to (1) consider the complete emplacement and deformation of the pluton during the Pan-African D 2 and D 3 events which occurred in the Pan-African belt in Cameroon and (2) reorganize Pan-African ages from Nguiessi Tchakam et al. (1997) compared with those of the other granitic plutons in the belt as: 686 ±17 Ma (Rb/Sr) for D 1 age of metamorphism recorded in gneiss; and the period between 604-557 Ma for D 2-D 3 emplacement and deformation age of the granitic pluton in a dextral ENE-WSW shear movement.

  14. 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.)

  15. Effect of chemical composition on the electrical conductivity of gneiss at high temperatures and pressures

    Directory of Open Access Journals (Sweden)

    L. Dai

    2018-03-01

    Full Text Available The electrical conductivity of gneiss samples with different chemical compositions (WA = Na2O + K2O + CaO  =  7.12, 7.27 and 7.64 % weight percent was measured using a complex impedance spectroscopic technique at 623–1073 K and 1.5 GPa and a frequency range of 10−1 to 106 Hz. Simultaneously, a pressure effect on the electrical conductivity was also determined for the WA = 7.12 % gneiss. The results indicated that the gneiss conductivities markedly increase with total alkali and calcium ion content. The sample conductivity and temperature conform to an Arrhenius relationship within a certain temperature range. The influence of pressure on gneiss conductivity is weaker than temperature, although conductivity still increases with pressure. According to various ranges of activation enthalpy (0.35–0.52 and 0.76–0.87 eV at 1.5 GPa, two main conduction mechanisms are suggested that dominate the electrical conductivity of gneiss: impurity conduction in the lower-temperature region and ionic conduction (charge carriers are K+, Na+ and Ca2+ in the higher-temperature region. The electrical conductivity of gneiss with various chemical compositions cannot be used to interpret the high conductivity anomalies in the Dabie–Sulu ultrahigh-pressure metamorphic belt. However, the conductivity–depth profiles for gneiss may provide an important constraint on the interpretation of field magnetotelluric conductivity results in the regional metamorphic belt.

  16. Discovery of uranium mineralizations in the rhyolite-granite complex in the Jabal Eghei area of southern Libya

    Directory of Open Access Journals (Sweden)

    Kovačević Jovan

    2013-01-01

    Full Text Available During investigation of the Jabal Eghei area in southern Libya and the production of geological maps at a scale of 1:250 000 (Tibesti sector, sheet Wadi Eghei NF 34-1 and NF 34-2, regional prospecting for mineral raw materials was performed. Radiometric survey of observed targets at the sites indicated two significant uranium mineralizations in rhyolites, and some smaller ones in granites that are in close contact with rhyolites. Rhyolites are located in the central part of the investigated region. They cut through granite rocks. The first mineralization is in the central part of the rhyolite region, which is mostly composed of silificated rhyolites. The second one was discovered near the granite-rhyolite contact zone, characterized by the presence of silicified breccia rocks. These findings were confirmed by laboratory measurements of more than seventy samples collected in the area, using high resolution gamma-ray spectrometry. The concentrations of uranium in these mineralizations were found to range from approx. 50 mg kg-1 to more than 600 mg kg-1. The latter value is about 240 times above the Earth’s average. Besides uranium, these measurements have also given concentrations of thorium and potassium. Additional geochemical analysis was performed on samples taken from locations where uranium anomalies were discovered using ICP-MS technique, in which concentrations of more than forty elements were determined. Uranium mineralizations are accompained by increased contents of silver (up to 17 times, arsenic (up to 8 times, molybdenum (up to 50 times, mercury (up to 9 times, and lead (up to 14 times, in regard to the Clark’s values. These results warrant a continued investigation of this region because of potential interest in the discovery of nuclear mineral raw materials.

  17. An Alternative Source for Ceramics and Glass Raw Materials: Augen-Gneiss

    Directory of Open Access Journals (Sweden)

    Murat Olgaç Kangal

    2017-05-01

    Full Text Available Due to the depletion of well-known feldspar reserves in the forms of granite, trachyte and pegmatite, many investigations are focused on new and economic alternatives to these resources. Of these, gneiss is a metamorphic rock type, which is characterized by dark and light colored minerals including feldspar and quartz. In this study, Augen-Gneiss rock was subjected to flotation tests to produce alkali (Na + Ca feldspar and quartz concentrates by adapting different flotation conditions with/without hydrofluoric acid (HF. During these tests, the effect of particle size and different reagent combinations were investigated. The results of these tests showed that, in the presence of HF, a saleable feldspar concentrate with 0.04% Fe2O3 content and a saleable quartz concentrate with 98.45% SiO2 content were obtained. Products with similar qualities to a feldspar concentrate with 0.13% Fe2O3 and a quartz concentrate with 92.53% SiO2 content were produced without HF. The results of these tests clearly showed that, compared to other types of origin, saleable quality feldspar and quartz could well be enriched with/without HF from Augen-Gneiss rock.

  18. The geological processes time scale of the Ingozersky block TTG complex (Kola Peninsula)

    Science.gov (United States)

    Nitkina, Elena

    2013-04-01

    Ingozersky block located in the Tersky Terrane of the Kola Peninsula is composed of Archean gneisses and granitoids [1; 5; 8]. The Archaean basement complexes on the regional geological maps have called tonalite-trondemit-gneisses (TTG) complexes [6]. In the previous studies [1; 3; 4; 5; 7] within Ingozersky block the following types of rocks were established: biotite, biotite-amphibole, amphibole-biotite gneisses, granites, granodiorites and pegmatites [2]. In the rocks of the complex following corresponding sequence of endogenous processes observed (based on [5]): stage 1 - the biotitic gneisses formation; 2 - the introduction of dikes of basic rocks; 3 phase - deformation and foliation; 4 stage - implementation bodies of granite and migmatization; 5 stage - implementation of large pegmatite bodies; stage 6 - the formation of differently pegmatite and granite veins of low power, with and without garnet; stage 7 - quartz veins. Previous U-Pb isotopic dating of the samples was done for biotite gneisses, amphibole-biotite gneisses and biotite-amphibole gneisses. Thus, some Sm-Nd TDM ages are 3613 Ma - biotite gnesses, 2596 Ma - amphibole-biotite gnesses and 3493 Ma biotite-amphibole gneisses.. U-Pb ages of the metamorphism processes in the TTG complex are obtained: 2697±9 Ma - for the biotite gneiss, 2725±2 and 2667±7 Ma - for the amphibole-biotite gneisses, and 2727±5 Ma for the biotite-amphibole gneisses. The age defined for the biotite gneisses by using single zircon dating to be about 3149±46 Ma corresponds to the time of the gneisses protolith formation. The purpose of these studies is the age establishing of granite and pegmatite bodies emplacement and finding a geological processes time scale of the Ingozerskom block. Preliminary U-Pb isotopic dating of zircon and other accessory minerals were held for granites - 2615±8 Ma, migmatites - 2549±30 Ma and veined granites - 1644±7 Ma. As a result of the isotope U-Pb dating of the different Ingozerskogo TTG

  19. 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.

  20. Pb-Pb and U-Pb zircon ages of archean syntetocnic granites of the Carajas metallogenic province, northern Brazil

    International Nuclear Information System (INIS)

    Barros, Carlos Eduardo de Mesquita; Sardinha, Alex Souza; Barbosa, Jaime dos Passos de Oliveira; Krimski, Robert; Macambira, Moacir Jose Buenano

    2001-01-01

    The Carajas Metallogenic Province is located in the southeastern Amazonian Craton. It has been divided in two domains, the southernmost comprises the Rio Maria region and the northernmost corresponds to Caraj region (Souza et al. 1996). The former domain is made up of Archean greenstone sequences (2,97 Ga), TTG (2,9 Ga) and calc-alkaline granitoids (2,87 Ga) (Macambira and Lafon 1995, Leite et al. 1999, Althoff et al. 2000). The Carajas block is constituted of minor mafic granulites (3,00 Ga) and quartzofeldspathic gneisses (2,81 Ga), metavolcanosedimentary sequences (2,76 Ga) and granites (2,76 to 2,56 Ga) (Machado et al. 1991; Huhn et al. 1999, Pidgeon et al. 2000). Widespread anorogenic A-type granites are found in both areas (Docegeo 1988; Dall'Agnol et al. 1994). In the last two decades several authors (Lindenamyer et al. 1994, Barros and Barbey 1998, Huhn et al. 1999 and others) have emphasized the role of the Archean granite magmatism in the tectonicthermal evolution in the Carajas Province. In this paper we discuss the tectonic significance of the Pb- Pb and U-Pb ages obtained in some granitoids from the Carajas region. The Estrela Granite Complex and the granitoids located to the north of Parauapebas were dated by Pb- Pb evaporation zircon method (cf. Kober 1987). Data are presented considering 2σ ∼ . The Pb corrections have been done in the basis of the evolution model of Pb in double stage (cf. Stacey and Kramers 1975). U-Pb zircon method (cf. Krogh 1973, Stacey and Kramers 1975, Parrish 1987, Ludwuig 1999), recently put on routine in the Para-Iso laboratories, was employed to date the granite from the Serra do Rabo area. Analyses were carried on the Finnigan Mat 262 spectrometer (au)

  1. Complicated secondary textures in zircon record evolution of the host granitic rocks: Studies from Western Tauern Window and Ötztal-Stubai Crystalline Complex (Eastern Alps, Western Austria)

    Science.gov (United States)

    Kovaleva, Elizaveta; Harlov, Daniel; Klötzli, Urs

    2017-07-01

    Samples of metamorphosed and deformed granitic rocks were collected from two Alpine complexes with well-constrained metamorphic history: Western Tauern Window and Ötztal-Stubai Crystalline Complex. Zircon grains from these samples were investigated in situ by a combination of scanning electron microscope techniques, cathodoluminescence (CL) imaging and Raman spectroscopy. The aims were: to describe and interpret complicated secondary textures and microstructures in zircon; based on cross-cutting relationships between secondary microstructures, reconstruct the sequence of processes, affecting zircon crystals; link the evolution of zircon with the history of the host rocks. The results indicate that zircon in the sampled granitic rocks forms growth twins and multi-grain aggregates, which are unusual for this mineral. Moreover, various secondary textures have been found in the sampled zircon, often cross-cutting each other in a single crystal. These include: distorted oscillatory CL zoning with inner zones forming inward-penetrating, CL-bright embayments, which are the evidence of dry recrystallization via annealing/lattice recovery; CL mosaicism with no preservation of growth zoning, but abundant nano- and micro-scale pores and mineral inclusions, which are the evidence of recrystallization by coupled dissolution-reprecipitation and/or leaching; embayed zircon boundaries filled with apatite, monazite, epidote and mylonitic matrix, indicating mineral-fluid reactions resulting in zircon dissolution and fragmentation; overgrowth CL-dark rims, which contain nano-pores and point to transport and precipitation of dissolved zircon matter. We conclude that zircon in our meta-granites is sensitive to metamorphism/deformation events, and was reactive with metamorphic fluids. Additionally, we have found evidence of crystal-plastic deformation in the form of low angle boundaries and bent grain tips, which is a result of shearing and ductile deformation of the host rock. We

  2. 2005 dossier: granite

    International Nuclear Information System (INIS)

    2005-01-01

    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.)

  3. Radiometric age of granite from Campo Formoso, BA-Brazil - a minimum age for Jacobina group

    International Nuclear Information System (INIS)

    Torquato, J.R.; Oliveira, M.A.F.T. de; Bartels, R.L.

    1978-01-01

    The Campo Formoso granite represents the magmatic phase of the remobilized Pre-Jacobina basement, located within an are defined by the Serra de Jacobina, north of Campo Formoso, Bahia. Intrusive relationships between this granite and the Jacobina Group metasediments, gradational changes in textures and compositions between the granite and basement rocks, and the general structural-topographic expression of this suggest a mantled gneiss dome model for this area. A RB/Sr whole rock isochron age of 1911 +- 13 m.y. for the Campo Formoso granite is established. This date is interpreted as the age of the development of the structure, as well as a minimum age for the Jacobina Group metasediments. K/Ar dates on muscovites from the Campo Formoso granite are concordant with the Rb/Sr isocron. It is suggested that a lower regional thermal gradient in the Campo Formoso area during Transamazonic time is the cause for a more rapid cooling environment. (Author) [pt

  4. Durability analysis of gneiss using wear resistance

    Directory of Open Access Journals (Sweden)

    José Luiz Ernandes Dias Filho

    2014-01-01

    Full Text Available This paper presents a study conducted in gneiss in Santo Antonio de Pádua, RJ, BR, including durability analysis of the rock using slake durability test. Rocks in the region of Pádua are mostly used for ornamental purposes. A lab equipment was developed to evaluate the influence of rotation in the test, allowing for the speed variation of 7 RPM to 238 RPM. This study could be implemented in a wide variety of rock materials, targeting them according to their lifetime in the project. With variation of the wear levels, increasing weight loss was observed until the inertia moment in which the sample holds to the machine wall. The results indicate an increase in linear mass loss. These procedures allow a more precise analysis of durability than can be applied in different different regions of the world.

  5. Geophysical interpretation of U, Th, and rare earth element mineralization of the Bokan Mountain peralkaline granite complex, Prince of Wales Island, southeast Alaska

    Science.gov (United States)

    McCafferty, Anne E.; Stoeser, Douglas B.; Van Gosen, Bradley S.

    2014-01-01

    A prospectivity map for rare earth element (REE) mineralization at the Bokan Mountain peralkaline granite complex, Prince of Wales Island, southeastern Alaska, was calculated from high-resolution airborne gamma-ray data. The map displays areas with similar radioelement concentrations as those over the Dotson REE-vein-dike system, which is characterized by moderately high %K, eU, and eTh (%K, percent potassium; eU, equivalent parts per million uranium; and eTh, equivalent parts per million thorium). Gamma-ray concentrations of rocks that share a similar range as those over the Dotson zone are inferred to locate high concentrations of REE-bearing minerals. An approximately 1300-m-long prospective tract corresponds to shallowly exposed locations of the Dotson zone. Prospective areas of REE mineralization also occur in continuous swaths along the outer edge of the pluton, over known but undeveloped REE occurrences, and within discrete regions in the older Paleozoic country rocks. Detailed mineralogical examinations of samples from the Dotson zone provide a means to understand the possible causes of the airborne Th and U anomalies and their relation to REE minerals. Thorium is sited primarily in thorite. Uranium also occurs in thorite and in a complex suite of ±Ti±Nb±Y oxide minerals, which include fergusonite, polycrase, and aeschynite. These oxides, along with Y-silicates, are the chief heavy REE (HREE)-bearing minerals. Hence, the eU anomalies, in particular, may indicate other occurrences of similar HREE-enrichment. Uranium and Th chemistry along the Dotson zone showed elevated U and total REEs east of the Camp Creek fault, which suggested the potential for increased HREEs based on their association with U-oxide minerals. A uranium prospectivity map, based on signatures present over the Ross-Adams mine area, was characterized by extremely high radioelement values. Known uranium deposits were identified in the U-prospectivity map, but the largest tract occurs

  6. Generation of early Archean felsic volcanics and TTG gneisses through crustal melting, eastern Kaapvaal craton, southern Africa

    Science.gov (United States)

    Kröener, A.; Hoffmann, J.; Xie, H.; Wu, F.; Münker, C.; Hegner, E.; Wong, J.; Wan, Y.; Liu, D.

    2012-12-01

    An unresolved question in early Archean granite-gneiss-greenstone terranes is whether they evolved in oceanic environments or whether older continental crust was involved. We investigated felsic volcanic rocks of the 3.55-3.2 Ga Barberton Greenstone Belt (BGB) and adjacent 3.66-3.45 TTGs in the Ancient Gneiss Complex (AGC) of Swaziland, southern Africa, using SHRIMP zircon dating as well as whole-rock Nd-Hf and Hf-in-zircon isotopes. Xenocrystic zircons in BGB felsic rocks and negative whole-rock ɛNd(t)-values with model ages of 3.6-3.7 Ga question models whereby these rocks resulted from differentiation of mafic precursors. Involvement of older crust was also likely in the formation of several TTGs and is supported by rare zircon xenocrysts and Hf-in-zircon isotopic data suggesting at least partial cannibalistic recycling of older continental crust. The felsic volcanics, interlayered with basalts and komatiites, exhibit REE patterns with distinct negative Eu-anomalies. 3 samples from the oldest felsic unit (Theespruit Fm.) have zircon ages of 3529-3552 Ma, whole-rock Nd isotopic values of -1.1 to +1.1, and model ages of 3.55-3.73 Ga. Hf isotopic data were acquired on concordant or near-concordant zircon domains analyzed on SHRIMP, and most analyses show negative ɛHf(t)-values, suggesting zircon derivation from older crustal protoliths, whereas a few analyses suggest input from a juvenile source. Hf crustal model ages are 3.60-3.95 Ga and imply a heterogeneous crustal source. The younger felsic rocks (Hoogenoeg Fm.) display well-preserved volcanic and/or sedimentary textures, and some are high in K2O and contain primary magmatic K-feldspar. 4 samples have zircon ages of 3447-3462 Ma, and 3 samples contain 3499-3541 Ma xenocrysts. Whole-rock Nd isotopic values are around -1.5 with a model age of ca. 3.69 Ga. Hf-in-zircon isotopic data are similar to those of the Theespruit rocks, and most analyses show negative ɛHf(t)-values, suggesting zircon derivation from a

  7. Some geotechnical properties of a cement-stabilized granite-gneiss ...

    African Journals Online (AJOL)

    This was with a view to determining the influence of cement on some engineering properties of the soil. ... the maximum Dry Density and the percentage cement of the samples compacted at the West African and Modified American Association of State Highways and Transportation Officials (AASHTO) levels respectively.

  8. Laboratory and in situ determination of the migration processes of actinide complexes and colloids in a fissured granitic environment. El Berrocal project (preliminary activities - phase 0)

    International Nuclear Information System (INIS)

    Astudillo, J.; Del Olmo, C.; Commission of the European Communities, Ispra

    1993-01-01

    The experimental site of El Berrocal has been chosen for a study of the migration of natural radionuclides in a fractured granitic environment. The granite is classified as an alkaline feldspar-rich quartz granite with two micas. The fresh granite is affected by hydrothermal alteration processes related to fractures, which has led to a strong sericitization of albite, and the precipitation of secondary chlorites and carbonates. The most important U-bearing and Th-bearing accessory minerals are uraninite, thorite-auerlite, monazite, anatase, apatite and zircon. Approximately 65% of the total of U in the rock is held as uraninite. In the altered granite, most of the U is held as autunite. Hydrogeochemical data show that Co 2 /H 2 CO 3 is the dominant system, followed by the silica-silicate system. Based on their stability analyses, two zones can be defined: (i) waters north of the dyke and from deep zones where calcite is in equilibrium and albite and gibbsite precipitate, and (ii) surface waters, south of the dyke, subsaturated in relation to calcite, producing the alteration of albite and the precipitation of montmorillonite. The size distribution of the colloids varies, depending on the treatment given to the water samples. The particles are mainly composed of K-feldspars and clay minerals (smectite) and occasionally by quartz, mica, calcite and pollen. The El Berrocal groundwaters have a very low amount of organic matter. Column migration tests have been carried out and were performed with intact granitic cores and with crushed granite. Np proved to be an adequate radionuclide for these experiments. Under oxic conditions and in the absence of organic matter, it was completely retained in both types of columns, whereas in the presence of organic matter a more rapid breakthrough was observed. Under anoxic conditions, and with or without organic matter, Np was found to move faster than under oxic conditions. (author). 13 refs., 46 figs., 23 tabs

  9. Geochemistry and petrogenesis of Proterozoic granitic rocks from ...

    Indian Academy of Sciences (India)

    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 ...

  10. The GRANIT spectrometer; Le spectrometre GRANIT

    Energy Technology Data Exchange (ETDEWEB)

    Baessler, St. [University of Virginia, Charlottesville, VA 22904 (United States); Oak Ridge Nat. Lab., Oak Ridge, TN 37831 (United States); Beau, M.; Kreuz, M.; Nesvizhevsky, V.V. [ILL, 6 rue Jules Horowitz, Grenoble, F-3804(France); Kurlov, V.N. [ISSP, 2 Institutskaia, Chernogolovka, RU-142432 (Russian Federation); Pignol, G.; Protasov, K.V.; Vezzu, F. [LPSC/IN2P3-UJF-INPG, 53 rue des Martyrs, Grenoble, F-38026 (France); Voronin, A.Y. [Lebedev Institute, 53 Leninskii pr., Moscow, RU-119991 (Russian Federation)

    2010-10-15

    The existence of quantum states of matter in a gravitational field was demonstrated recently in the Institut Laue-Langevin (ILL), Grenoble, in a series of experiments with ultra cold neutrons (UCN). UCN in low quantum states is an excellent probe for fundamental physics, in particular for constraining extra short-range forces; as well as a tool in quantum optics and surface physics. The GRANIT is a follow-up project based on a second-generation spectrometer with ultra-high energy resolution, permanently installed in ILL. It will become operational in 2011. The spectrometer consists of several neutron-optics elements and UCN detectors installed on a massive granite table in an aluminium vacuum chamber with a volume of about 1.5 m{sup 3}. 3 types of detectors will be used at the first stage of the GRANIT experiment: {sup 3}He gaseous proportional counters with extremely low background, position-sensitive nuclear-track UCN detectors will be used to study the spatial distribution in quantum states, and real-time position-sensitive detectors with a resolution of a few hundred microns to measure velocity distributions of neutrons in quantum states. The key elements of the GRANIT spectrometer is a set of mirrors to shape/analyze neutron spectra and to store neutrons in quantum states

  11. 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

  12. Origin of Mafic Microgranular Enclaves (MMEs and Their Host Rocks of the Cretaceous Xiaojiang-Liangnong Granitic Complexes in the Southeast Coast Magmatic Belt, S China

    Directory of Open Access Journals (Sweden)

    Pei-Shan Hsieh

    2009-01-01

    Full Text Available Cretaceous Late Yanshanian (LY magmatism produced large amounts of I-type granitoids in the Southeast Coast Mag matic Belt (SCMB. I-type granitoids from Xiaojiang-Liangnong complexes (N Zhejiang in the northern part of this belt are characterized by containing abundant mafic microgranular enclaves (MMEs. On the basis of petrography and mineralogy, two types of MMEs are recognized. One (Type 1, enclosed in the granodiorite, is composed of amphibole, high-Ti tabularbiotite, plagioclase, K-feld spar, and quartz. Us ing the Al-in-am phibole geobarometer, a shallow origin (4 - 8 km of am phiboles is suggested. The other (Type 2, enclosed in al kali feld spargranite, is amphibole-free and composed of low-Ti acicular biotite, plagioclase, K-feld spar, and quartz. Geo chemistry of major and traceel ements seems to re flect two different evolving trends for these host granitoids. The Sr-Nd isotopic features indicate that all the studied samples vary in a narrow range of Isr (0.7078 to 0.7082 and eNd(T (-5.6 to -8.3, except the Type 2 enclaves and hosts that show slightly morede pleted compositions (Isr = 0.7073 to 0.7075 and eNd(T = -5.0 to -6.0. U-Pb zir con ages obtained are 109.6 ¡_ 0.9 Ma for the granodiorite and 113.5 ¡_ 1.1 Ma for the alkalifeld spargran ite, with 103.2 ¡_ 0.9 Ma for the Type 2 MMEs. In her ited ages of 117.0 ¡_ 2.0 Ma and 119.8 ¡_ 1.1 Ma seem to presentin the former two samples. Similarities of mineral chemistry and isotopic composition among the MMEs-host pairs as well as the youn ger age of MMEs suggest that MMEs of Xiaojiang-Liangnong complexes most likely represent mixing/mingling products formed as a consequence of the in tru sion of ba saltic magma into the host granitoids un der dif fer ent cool ing con di tions. Judg ing from the pres ence of in her ited zir con ages, the com po si tion gap be tween high-Ti and low-Ti bi o tite in granodiorite and al kali feld spar gran ite, and lower zirconsaturation temperatures for

  13. Petrochemistry and geochronology of pink granite from Songsak, East Garo Hills, Meghalaya

    International Nuclear Information System (INIS)

    Kumar, Sunil

    1990-01-01

    The pink granite of Songsak area, East Garo Hills district, Meghalaya, intrusive into Precambrian gneisses is inferred to be S-type, peraluminous, low calcium, post-kinematic granite. It is characterised by initial 87 Sr/ 86 Sr ratio of 0.728±.002, high K 2 O, high differentiation index and presence of normative corundum. The major mineral constituents are perthitic microcline, fresh interstitial microline, orthoclase with different degree of triclinisation, two generations of quartz and biotite. Sericitization of feldspars, presence of muscovite, rare chiastolite, fluorite and uraninite are other characteristics of the pink granites. Whole rock Rb-Sr dating assign an age of 500± 40 m.y. (author). 12 refs., 5 figs

  14. Granit, Prof. Ragnar Arthur

    Indian Academy of Sciences (India)

    Home; Fellowship. Fellow Profile. Elected: 1964 Honorary. Granit, Prof. Ragnar Arthur Nobel Laureate (Medicine) - 1967. Date of birth: 30 October 1900. Date of death: 11 March 1991. YouTube; Twitter; Facebook; Blog. Academy News. IAS Logo. Theory Of Evolution. Posted on 23 January 2018. Joint Statement by the ...

  15. Dynamic recrystallization and metamorphic evolution of ca. 1.85 Ga quartzofeldspathic and cordierite-garnet gneisses, western Gyeonggi Massif, Korea

    Science.gov (United States)

    Cho, Moonsup; Yang, Soh-young; Kim, Taehwan; Yi, Keewook

    2013-04-01

    occurs as fine-grained inclusions in the almandine-cordierite corona or as neoblastic phase in the matrix. The weighted mean U-Pb ages of monazite in two cordierite-garnet gneisses are 1850±8 Ma and 1856±8 Ma, respectively, suggesting the Paleoproterozoic high-T metamorphism. On the other hand, the majority of monazite grains in leucocratic and migmatitic gneisses yielded U-Th-Pb ages of 235-228 Ma. In one mylonite sample, monazite was dated at 232 ± 2 Ma. In addition, zircons from a granitic vein free of deformation fabric are dated at 226 ± 4 Ma. These SHRIMP ages suggest that the deformed gneisses and mylonites in the Mt. Cheonggye area is the product of Middle Triassic tectono-metamorphism, associated with the collisional orogeny between North China and South China cratons.

  16. Petrography and geochemistry of five granitic plutons from south central Uruguay: contribution to the knowledge of the Piedra Alta terrane

    International Nuclear Information System (INIS)

    Preciozzi, F.

    2005-01-01

    Granitoid rocks in south-central Uruguay are largely concentrated in three east-west trending metamorphic belts, known as (from south to north) the Montevideo Belt, the San José Belt and the Arroyo Grande Belt. These belts are separated from one another by intervening bands of gneisses of granitic composition. The whole assemblage, the gneisses as well as the metamorphic belts and their associated granites, collectively constitute the Piedra Alta Terrane. Five of these granite plutons, two from the San José Belt and three from the Arroyo Grande Belt, have been studied in some detail and the chemical composition of 86 samples (major elements as well as a selected suite of trace elements) have been determined. These data, as well as Rb-Sr isotopic data, show that these plutons are typically composite in nature, and that the various units range in age from 1900 Ma to 2500 Ma. The older ages were obtained from the main units of the plutons themselves whereas the younger ages are from late dykes which were emplaced into the plutons and which are clearly not related to them. The plutons are predominantly, but not exclusively, of calc-alkaline affinity and are typically synorogenic whereas the dykes are post-orogenic and are either calc-alkaline or alkaline in composition. These data have been incorporated into a tectonic model for the Piedra Alta Terrane which is considerably different from that heretofore proposed. The essential features of the geological history of the area are: 1) development of an older ''basement'' of granitic gneisses 2) deposition, upon or adjacent to this gneisses basement, of a typical Archean greenstone belt assemblage (no komatiites so far reported) 3) Paleo-proterozoic metamorphism, followed by syn-tectonic to post-tectonic intrusion of the plutonic rocks 4) major tectonic dislocation(s) associated with the Transamazonian orogeny 5) dyke emplacement (post-orogenic to anorogenic) following the Transamazonian orogeny

  17. Uranium occurrences in the Granite Zone

    International Nuclear Information System (INIS)

    Nyegaard, P.; Armour-Brown, A.

    1986-04-01

    This report describes the work and results of the South Greenland Exploration Programme (Sydex) during the 1984 field season in the Granite Zone, and discusses the results and conclusions that can be drawn from them. It also contains a structural analysis of the Ivigtut-Julianehaab region, which will help in future exploration by indicating the likely directions of uraniferous faults and fractures. It also includes suggestions for future work with both exploration and scientific aspects. The project was carried out by the Geological Survey Greenland (GGU) in co-operation with Risoe National Laboratory. It was financed by the Danish Ministry of Energy. The structural analysis was carried out using previous geological maps, our own field observations and an analysis of lineament frequencies taken from aerial photographs and satellite images. Major lineaments in the region are due to E-W sinistral wrench faults and NE-SW normal faults. Analysis of the minor lineaments showed that the region could be divided into three blocks which have each reacted differently to the same regional stress field which was active throughout the Gardar period. A northern block which has been influenced by an older system of faults in the Archaean gneiss, a central block dominated by a graben, and a southern block where there is a change to a less intensively faulted area. 2 maps, 27 refs. (EG)

  18. Geochemistry of Pegmatites associated with the cape coast granite ...

    African Journals Online (AJOL)

    Geochemistry of Pegmatites associated with the cape coast granite complex in the Egyaa and Akim Oda areas of southern Ghana. PM Nude, JEK Hanson, SB Dampare, TT Akiti, S Osae, ES Nyarko, N Zkaria, S Enti-Brown ...

  19. Adsorption behavior of Am(III) on granite

    International Nuclear Information System (INIS)

    Zhang Yingjie; Feng Xiaogui; Liang Junfu; Chen Jing; Su Rui; Wang Ju; Liu Chunli

    2009-01-01

    The adsorption behavior of Am(III) on granite (sampled from drilling well BS01 at Beishan (BS) area--a potential candidate site for China's high-level radioactive waste repository, the granite sample's depth about 300 m) was studied in BS03 well groundwater by a batch technique at (25±1) degree C. The influences of pH, sulphate ion, total carbonate ion, humic acid, and concentration of the Am(III) on the adsorption behavior were also studied, and the possible adsorption mechanism was discussed. Experimental results show that the adsorption distribution rate of Am(III) on granite increases with increasing pH of aqueous phase. The chemical composition of the groundwater is the main factor which influences the species of Am(III) and adsorption behavior. The adsorption mechanism of Am(III) on granite is surface complexation. The adsorption isotherm of Am(III) on granite can be described by Freundlich's equation. (authors)

  20. The Serra do Carambei Granite - PR and the uraniferous anomalism

    International Nuclear Information System (INIS)

    Pinto-Coelho, C.V.

    1986-01-01

    The Serra do Carambei Granite forms a pluton relatively homogeneous, covering about 33 km 2 , cropping out as an elongate retangular body trending NE-SW, being emplaced in the Cunhaporanga Granitoid Complex. Its characteristics indicates a kind of hololeucocratic granite, equigranular, medium to coarse-grained, consisting predominantly of microperthitic alkali-feldspar, quartz and a small amount of biotite (less than 1%), thus being classified as an alaskite. Chemical data allows a classification in the group of granite with high contents of silica (74-76% Wt. SiO 2 ), dominantly alkaline chemism and hypersolvus character, derived from a parental magma under saturated in water with distinguished features of granitoids from the magnetite series and types I and A granites. The pluton shows important chemical variations due to weathering processes. However detailed chemical studies reveal the presence of anomalous concentrations of trace elements such as U, Sn, Nb, Y, Zr, the Serra do Carambei Granite lacks economically important mineralizations because of the absence of well-developed tardi/pos-magmatic processes that could concentrate them. The SW side of the granite is cut by leucocratic rhyolite dykes that show some radiometric anomalies. These rocks, which are highly diferentiated, were emplaced contemporaneously to the Serra do Carambei Granite. Although petrographic and chronological similarities are found between the uraniferous alaskite of Roessing (Namibia) and the Serra do Carambei Granite anyhow it was not possible to establish any lateral continuity with the uranifeous Pan-African Province. (Author) [pt

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

    OpenAIRE

    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 – 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 acc...

  2. Thrust tectonics in crystalline domains: The origin of a gneiss dome

    Science.gov (United States)

    Greiling, R. O.

    1997-12-01

    Structural geological field work, microscopic and magnetic fabric studies have been applied in order to assess the structural origin of a gneiss dome, based on a regional example from the Neoproterozoic Pan-African Belt of NE Africa, the Wadi Hafafit Culmination (WHC). The culmination is dominated by a number of major shear zones, which form both the boundaries between the gneissic core and surrounding low grade successions as well as those of minor structural units within the gneisses. These shear zones form a linked fault system, which, based on shear criteria, fault-bend fold and overall geometric interrelationships, can be classified as an antiformal stack. The relative age sequence of the shear zones/thrusts with the highest thrust oldest and the lowermost youngest points to a forward-propagating thrust system. This, together with the shear criteria, exclude an origin of the WHC as a metamorphic core complex, where the highest shear zone should be youngest. The geometry of the WHC antiformal stack is documented by maps and sections as well as section balancing and restoration. Microscopic work showed brittle deformation in feldspar and dynamic recrystallization in quartz ribbons. The asymmetry of the fabric confirmed the macroscopically determined shear sense. However, there is one example of an earlier, perhaps extensional shear movement. Mylonitic foliation and transport-parallel lineation have also been determined by magnetic fabric studies. The observations suggest that thrusts may cut across both previously folded crystalline rocks as well as homogeneous granitoid plutonic bodies. According to the regional tectonic picture the large-scale structure of the gneiss dome originated after a phase of (late-orogenic) extensional collapse. It is speculated that during late-orogenic cooling the upper part of the lithosphere was sufficiently strong to allow brittle thrusting whilst the lithosphere as a whole was still weak enough to allow large-scale compressional

  3. Mid-Cretaceous oblique rifting of West Antarctica: Emplacement and rapid cooling of the Fosdick Mountains migmatite-cored gneiss dome

    Science.gov (United States)

    McFadden, Rory; Teyssier, Christian; Siddoway, Christine; Cosca, Michael A.; Fanning, C. Mark

    2015-01-01

    In Marie Byrd Land, West Antarctica, the Fosdick Mountains migmatite-cored gneiss dome was exhumed from mid- to lower middle crustal depths during the incipient stage of the West Antarctic Rift system in the mid-Cretaceous. Prior to and during exhumation, major crustal melting and deformation included transfer and emplacement of voluminous granitic material and numerous intrusions of mantle-derived diorite in dikes. A succession of melt- and magma-related structures formed at temperatures in excess of 665 ± 50 °C based on Ti-in-zircon thermometry. These record a transition from wrench to oblique extensional deformation that culminated in the development of the oblique South Fosdick Detachment zone. Solid-state fabrics within the detachment zone and overprinting brittle structures record translation of the detachment zone and dome to shallow levels.To determine the duration of exhumation and cooling, we sampled granite and gneisses at high spatial resolution for U–Pb zircon geochronology and 40Ar/39Ar hornblende and biotite thermochronology. U–Pb zircon crystallization ages for the youngest granites are 102 Ma. Three hornblende ages are 103 to 100 Ma and 12 biotite ages are 101 to 99 Ma. All overlap within uncertainty. The coincidence of zircon crystallization ages with 40Ar/39Ar cooling ages indicates cooling rates > 100 °C/m.y. that, when considered together with overprinting structures, indicates rapid exhumation of granite and migmatite from deep to shallow crustal levels within a transcurrent setting. Orientations of structures and age-constrained crosscutting relationships indicate counterclockwise rotation of stretching axes from oblique extension into nearly orthogonal extension with respect to the Marie Byrd Land margin. The rotation may be a result of localized extension arising from unroofing and arching of the Fosdick dome, extensional opening within a pull-apart zone, or changes in plate boundary configuration.The rapid tectonic and

  4. 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.

  5. Measurement of activity concentration of 222Rn in ground waters drawn from two wells drilled in the Amparo Complex metamorphic rocks, municipio de Amparo, SP

    International Nuclear Information System (INIS)

    Oliveira, Igor Jose Chaves de

    2008-01-01

    A sampling system was assembled for field 222 Rn activity concentration measurements in ground waters. The system consists of a sampling flask that prevents the contact between the water sample and the atmosphere and a closed line for radon extraction from water. The system, its operation and calibration, are described in full detail, as well as, the conversion of the measured alpha counting rates in activity concentrations. The assembled system was used in 222 Rn activity concentrations measurements in ground waters drawn from two wells drilled in the Amparo Complex metamorphic rocks. The wells are located at the urban area of the city of Amparo and are exploited for public use water. One well, named Vale Verde, is 56 meters deep and crosses 18 meters of soil, 26 meters of quartz rich gneiss and 12 meters of biotite-gneiss. The other well, named Seabra, is 117 meters deep, crosses 28 meters of soil and weathered rocks and ends in granite-gneiss. The mean activity concentrations for the year long observation were (377 +- 25) Bq/dm 3 , for Seabra well, and (1282 +- 57) Bq/dm3, for the Vale Verde well. The 222 Rn activity concentrations fall in the activity concentration range reported in the literature for similar geology areas and are larger than the concentrations found neighboring areas of the same metamorphic Complex. The seasonal activity concentration variations seem to correlate with rain fall variations in the study area. (author)

  6. Oxigen isotope compositions as indicators of epidote granite genesis in the Borborema Provinces, NE Brazil

    International Nuclear Information System (INIS)

    Ferreira, V.P.; Valley, J.W; Sial, A.N; Spicuzza, M.J

    2001-01-01

    Neoproterozoic magmatic epidote-bearing granitoids intrude low-grade metapelites in the Cachoeirinha-Salgueiro terrane (CST), and gneisses and migmatites in the Serido terrane (ST), in the Borborema structural province, northeastern Brazil. Granitoids in both terranes contain biotite and hornblende, and are metaluminous, calc-alkalic, and oxidized I-type granites according to White's (1992) classification. However, in spite of these similarities, this work shows that mineral oxygen isotope data from plutons of the two terranes indicate different magma sources, and that magmatic epidote besides crystallizing at different pressure conditions, can have variable isotopic composition (au)

  7. 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

    -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, NE Asia: rock chemistry, composition of rock forming minerals, and conditions of formation // Stephan Mueller series. Geology and Tectonic Origins of Northeast Russia: A Tribute to Leonid Parfenov (in press) 28. Velikoslavinsky S.D. Geochemical typification of acid magmatic rocks of leading geodynamic settings // Petrology. 2003. V. 11. № 4. P.363-380. (in Russian) 19. Pearce J.A. Sources and settings of granitic rocks // Episodes. 1996. V. 19. N. 4. P. 120-125

  8. Yeguang granite and uranium metallogeny

    International Nuclear Information System (INIS)

    Gong Wenshu

    1988-03-01

    The geological, petrologic and geochemical characteristics of rock body of yeguang granite are discussed with emphasis on clarification of occurrence of uranium in rock body and uranium deposit characteristics related to rock body, based on extensive field observations and laboratory test. View points are presented that granite refers to genetic series of terrestial crust transformation tye and uranium deposit is hot water deposit

  9. U(VI) sorption on granite: prediction and experiments

    International Nuclear Information System (INIS)

    Nebelung, C.; Brendler, V.

    2010-01-01

    One widely accepted approach - component additivity (CA) - to describe the sorption of contaminants onto complex materials such as rocks or soils is based on the assumption that the surface of a complex mineral assemblage is composed of a mixture of mineral constituents whose surface properties are known from independent studies. An internally consistent SCM (surface complexation model) database can be developed that describes the adsorption reactions of solutes to each phase. Here, the capability of such a methodology was tested, using the code MINTEQA2 including thermodynamic data of the NEA-TDB, and literature data for SCM, namely the DDL model. The sorption characteristics of U(VI) on granite (from Eibenstock, Saxony, Germany, with the main components quartz, albite, orthoclase, and muscovite) was predicted and then compared to batch experiments. Granite plays an important role in the remediation of former uranium ore mining and milling sites, but is also one of the host rocks considered for final disposal of nuclear materials. Safety assessment requires a detailed understanding of this system and its retention potential with regard to hazardous components. Namely the sorption of uranium in this complex rock is not fully understood yet. The experiments thus also provided a better understanding of the far-field behaviour in granitic geological nuclear repositories. The robustness of the prediction was tested by variation of the granite composition and the variation of the specific surface area (SSA) - first all components were predicted with a uniform granite SSA, second with a distinct SSA for each granite component (determined on pure minerals for the same grain size fractions). Changes in compositions yielded only marginal differences in the prediction. Different approaches to SSA showed somewhat larger deviations. In conclusion, the CA methodology is a valid and robust approach to U(VI) sorption onto complex substrates such as granite, provided sufficient

  10. Evaluation of whole-rock lead isotope data for drill cores of the Eye-Dashwa Lakes pluton and the Vermilion granitic complex

    International Nuclear Information System (INIS)

    Doe, B.R.

    1990-01-01

    Disturbances of the U-Th-Pb systems in drill-core samples of the Eye-Dashwa Lakes pluton are related to a fracturing event in the Early Proterozoic and to more recent loss of lead due to fluid ingress at shallow crustal levels. The U-Pb and Th-Pb systems of five samples considered to be fresh on petrographic grounds (gray granite) are closed or show only limited parent/daughter mobility. U-Pb data for these samples are within about 10 percent of being concordant and define a concordia intercept age of 2684 ± 33 Ma, in agreement with the whole-rock Rb-Sr age of 2637 ± 33 Ma and U-Pb age of 2665 Ma inferred from zircon and titanite. The 207 Pb/ 204 Pb- 206 Pb/ 204 Pb plot for the fresh samples is 2684 ± 10 Ma. Three strongly altered samples define a chord on a concordia plot with intercepts at 2471 and 88 Ma. These samples are part of a suite of fractured, oxidized, and epidotized rocks that define a Rb-Sr isochron of 2281 ± 153 Ma. The whole-rock U-Pb systems of the altered samples are interpreted to have been perturbed by loss of Pb or gain of U during the fracturing event and again much more recently (Late Phanerozoic). The U-Pb systems in the fresh samples were not affected by the Early Proterozoic event, indicating that fluid ingress was largely restricted to the fracture zones

  11. 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...... incorporated remains of microorganisms. Two types of microbial communities can be distinguished associated with the speleothems: an Actinobacteria-like biofilm and a fungal community. Actinobacteria seem to play an important role in the formation of speleothem while the fungal community acts as both...... a constructive and a destructive agent. A modern biofilm dominated by Actinobacteria is present in the speleothem-free parts of the dolerite and located in cave ceiling cracks. These biofilms may represent sites of early speleothem formation. Because of its unusual position in between two types of host rock...

  12. Isotopic age determineations on granitic and gneissic rocks from the Ubendian-Usagaran System in southern Tanzania

    International Nuclear Information System (INIS)

    Priem, H.N.A.; Boelrijk, N.A.I.M.; Hebeda, E.H.; Verdurmen, E.A.Th.; Verschure, R.H.; Oen, I.S.; Westra, L.

    1979-01-01

    Isotopic age measurements on granites and gneisses are reported from the Ubendian-Usagaran System in southern Tanzania. For the Lukumburu-Wino Granites a Rb-Sr whole-rock isochron (9 points) of 1771 +- 145 Ma with initial 87 Sr/ 86 Sr of 0.704 +- 0.003 was obtained (γ 87 Rb = 1.42 10 -11 a -1 ; errors 95% confidence level). Two samples from neighbouring granites and three gneisses from the contact zone of the Lukumburu-Wino Granites also fit to this isochron; inclusion into the isochron calculation yields an age of 1747 +- 85 Ma with the same initial Sr composition. Five parts of a banded Usagaran gneiss sample produce an isochron of 589 +- 70 Ma with initial 87 Sr/ 86 Sr of 0.7194 +- 0.0005. This internal isochron is interpreted as reflecting Sr isotopic equilibration through the sample during the main phase (or one of the main phases) of the Pan-African thermotectonic episode. Rb-Sr and K-Ar ages of 17 micas show a general resetting by the Pan-African thermotectonic episode. The Rb-Sr ages of the muscovites and the biotites average 528 Ma and 463 Ma, respectively, and are interpreted as reflecting subsequent stages in the cooling history after the termination of the event. Biotites have K-Ar ages persistently higher than the corresponding Rb-Sr ages, possibly reflecting a high partial 40 Ar pressure through the crust during the resetting of the biotite K-Ar systems. (Auth.)

  13. Climax granite test results

    Energy Technology Data Exchange (ETDEWEB)

    Ramspott, L.D.

    1980-01-15

    The Lawrence Livermore Laboratory (LLL), as part of the Nevada Nuclear Waste Storage Investigations (NNWSI) program, is carrying out in situ rock mechanics testing in the Climax granitic stock at the Nevada Test Site (NTS). This summary addresses only those field data taken to date that address thermomechanical modeling for a hard-rock repository. The results to be discussed include thermal measurements in a heater test that was conducted from October 1977 through July 1978, and stress and displacement measurements made during and after excavation of the canister storage drift for the Spent Fuel Test (SFT) in the Climax granite. Associated laboratory and field measurements are summarized. The rock temperature for a given applied heat load at a point in time and space can be adequately modeled with simple analytic calculations involving superposition and integration of numerous point source solutions. The input, for locations beyond about a meter from the source, can be a constant thermal conductivity and diffusivity. The value of thermal conductivity required to match the field data is as much as 25% different from laboratory-measured values. Therefore, unless we come to understand the mechanisms for this difference, a simple in situ test will be required to obtain a value for final repository design. Some sensitivity calculations have shown that the temperature field is about ten times more sensitive to conductivity than to diffusivity under the test conditions. The orthogonal array was designed to detect anisotropy. After considering all error sources, anisotropic efforts in the thermal field were less than 5 to 10%.

  14. Mo-mineralized porphyries are relatively hydrous and differentiated: insights from the Permian-Triassic granitic complex in the Baituyingzi Mo-Cu district, eastern Inner Mongolia, NE China

    Science.gov (United States)

    Sun, Yan; Liu, Jianming; Zeng, Qingdong; Wang, Jingbin; Wang, Yuwang; Hu, Ruizhong; Zhou, Lingli; Wu, Guanbin

    2017-08-01

    Mo-Cu mineralization in the Baituyingzi district of eastern Inner Mongolia occurs within a granitic complex. This paper presents and discusses zircon U-Pb ages and whole-rock geochemical and Sr-Nd-Pb isotopic data from the granitic complex as potential indicators for porphyry Mo fertility. The U-Pb ages indicate that five units of the granitic complex were emplaced between 265.2 ± 0.7 and 246.5 ± 1.0 Ma. Constrained by crosscutting dikes, Mo-Cu mineralization was probably related to the Baituyingzi monzogranite porphyry dated at 248.2 ± 0.64 Ma. The intrusions belong to high-K calc-alkaline to shoshonitic series that are characterized by highly fractionated rare earth element (REE) patterns and strong enrichments of large ion lithophile elements, relative to high-field strength elements. Apart from the ˜246-Ma dike that shows negative ɛNd ( t) values (-14.9 to -13.1), the intrusions have ɛNd( t) values ranging from -3.9 to 1.0, relatively young depleted mantle model ages (811 to 1183 Ma), 206Pb/204Pb of 18.137-18.335, and 207Pb/204Pb of 15.591-15.625, which are consistent with a juvenile lower crustal origin. Among the intrusions, the ˜248-Ma porphyry and the ˜246-Ma dike show adakite-like characteristics (e.g., Sr/Y = 44.9-185) and listric-shaped REE patterns that indicate amphibole fractionation and a hydrous magma source. However, the porphyry exhibits a higher differentiation index (81.4-91.5) and a steeper REE profile (e.g., LaN/YbN = 25.6-87.0) than those of the ˜246-Ma dike, which suggests that it is highly differentiated. We propose that the complex was generated by the partial melting of juvenile mafic lower crust (containing minor old crustal relicts) that was triggered by collision between the North China Craton and Siberian Craton. As indicated by the Th/Nb, Th/Yb, Ba/Th, and Ba/La ratios of the intrusions, the crust may have been derived from the melting of the fertile mantle wedge that was metasomatized by various amounts of slab

  15. Zircon - A possible indicator of mass transfer in deformation zones: A solution for the Roffna gneiss controversy (Suretta nappe, Switzerland)

    Science.gov (United States)

    Steyrer, Hans Peter; Sturm, Robert

    2017-11-01

    This paper proposes a simple volume (mass) balancing technique as a means to assess the volume loss and tectonic flattening of mylonitic shear zones. The method involves counting the number of zircon crystals in oriented polished thin sections, analyzed subsequently in the electron microprobe, using the BSEI mode, and a spectrometer setup for detection of the element Zr. Here we present an application to the Roffna gneiss (Eastern Switzerland), a porphyritic granite of Permian origin, which has been metamorphosed and transformed into a phengitic schist under low-grade metamorphic conditions. Mass balances for this material have produced controversial interpretations, in that a first analysis of chemical data of wall rock and mylonite suggested an isochoric mylonitic transition event, while a dramatic volume loss of some 50% in the course this process was inferred after a re-evaluation of the same data. Electron-microscopy of zircon crystals that were retrieved from rocks which had undergone different degrees of deformation revealed only minor alterations and mechanical damage of single grains. This stability of zircon justified the use of single crystals, and in consequence of the element Zr, as passive markers in determining volume (mass) changes during deformation. Results obtained by this method allow us to confirm that the deformation of the Roffna gneiss involved a volume loss of 29 ± 6%, accompanied by chemical alterations. Deformation-induced mobility changes of various elements lead to small gains in Mg and Cr but significant losses Si, Al, Na, Ca, and Sr during the metamorphic event. All other elements, including the REE, underwent no substantial long-range transport.

  16. Mafic rocks from Erinpura gneiss terrane in the Sirohi region ...

    Indian Academy of Sciences (India)

    (2011). (b) Lithostratigraphic map (adapted from Roy and Sharma 1999) showing occurrence of the Daba mafic body within Erinpura granite terrane around Sirohi (SW Rajasthan). Sampled section along NW–SE traverse is also shown. sector of the Delhi Fold Belt (DFB) represents a. Grenvillian age (∼1 Ga) arc terrane ...

  17. Uranium enriched granites in Sweden

    International Nuclear Information System (INIS)

    Wilson, M.R.; Aakerblom, G.

    1980-01-01

    Granites with uranium contents higher than normal occur in a variety of geological settings in the Swedish Precambrian, and represent a variety of granite types and ages. They may have been generated by (1) the anatexis of continental crust (2) processes occurring at a much greater depth. They commonly show enrichement in F, Sn, W and/or Mo. Only in one case is an important uranium mineralization thought to be directly related to a uranium-enriched granite, while the majority of epigenetic uranium mineralizations with economic potential are related to hydrothermal processes in areas where the bedrock is regionally uranium-enhanced. (Authors)

  18. Granites and granitoids of the southern region - Granite molybdenite system

    International Nuclear Information System (INIS)

    Issler, R.S.

    1987-01-01

    Economic concentrations of molybdenum are genetically closely associated with acidic and moderately acid granitoids-granites, granodiorites, monzonites and diorites, and are located in two geotectonic settings: subduction-related and rift-related. The aim of this paper is twofold, first succinctly approach the geology, tectonic setting and chemical parameters of the 'granite molybdenite system' as defined by Mutschler and/or alcali granite porphyry bodies emplaced in the North American continent for occasion of a Mesozoic-Fanerozoic extensile event; second to relate the computer-assisted evaluation of 422 major element chemical analysis of granites and granitoids of southern region of Brazil, using chemical fingerprints (SiO 2 ≥ 74. Owt%, Na 2 O ≤ 3.6wt%, K 2 O ≥ 4.5wt%), and K 2 O/Na 2 O ratio > 1.5 developed and testified from North American and Finnish occurrences, may locate molybdenite-bearing granite bodies with high exploration potential. These techniques suggest that some late Precambrian to early Paleozoic granite-rhyolite assemblages inserted at domains of the SG. 22/23 Curitiba/Iguape, SH. 21/22 Uruguaiana/Porto Alegre and SI.22 Lagoa Mirim Sheets, have exploration potential for molybdenum. (author) [pt

  19. A combined geochronological approach to investigating long lived granite magmatism, the Shap granite, UK

    Science.gov (United States)

    Miles, A. J.; Woodcock, N. H.

    2018-04-01

    With the advent of more precise dating methods, it has become apparent that zircon dates from granite plutons frequently indicate older emplacement ages than other dating methods. Here we attempt to reconcile a number of dating methods from the c. 5 km2 Caledonian Shap granite, Northern England. The results reveal a more complex and protracted evolution than indicated by application of any single dating method. Zircon U-Pb dates give a weighted mean age of 415.6 ± 1.4 (2σ) Ma. A mafic enclave, dated at 412 ± 2 (2σ) Ma (revised Rb-Sr feldspar age from Davidson et al., 2005), contains resorbed K-feldspar and zircon crystals scavenged from the host crystal mush. These ages are at odds with field relations in the thermal aureole that suggest final emplacement at approximately 404 Ma or later during Acadian deformation. Previously reported Re-Os ages on molybdenites associated with magmatic fluids, have given ages of 405.2 ± 1.8 (2σ) Ma (Selby et al., 2008) and confirm the overlap of at least some magmatic activity with Acadian deformation. A similar emplacement age is supported by Rb-Sr whole-rock-mineral and biotite K-Ar dates when adjusted for revised decay constants (402 ± 3 Ma and 401 ± 7 Ma, respectively, Wadge et al., 1978). The lower closure temperatures of these systems relative to the U-Pb system in zircon means that they are more likely to record the timing of final granite emplacement. These data suggest that most zircons grew before final granite emplacement, by about 10 Ma on average. We suggest that the majority of zircon crystals record pre-emplacement magmatic activity within a deeper part of the system. Mafic enclaves and their scavenged cargo of crystals record the assembly of a mid-crustal batholith where crystals remained at least locally mobile at 412 Ma. Gravity data support the existence of an extensive, 1500 km2 intrusive body, originally at about 15 km depth beneath Shap. This batholith is likely to have remained below the granite

  20. Rare earths elements in the rocks of the Cinovec granite cupola (Czechoslovakia)

    International Nuclear Information System (INIS)

    Stemprok, M.

    1989-01-01

    Rare earth elements (REE) were analyzed by the nondestructive INAA method in samples from drilling CS-1 situated in the center of the Cinovec granite cupola, eastern Krusne hory Mts., Czechoslovakia. The 1596 m deep drilling found upper zinnwaldite and lower protolithionite granites which differ in their amounts of REE. Both types of granites that belong to the granites of the Younger Intrusive Complex of the Krusne Hory Mts. give flat chondrite-normalized patterns characterized by a large negative Eu anomaly. (author). 9 figs., 5 tabs., 25 refs

  1. Petrography and geochronology (U/Pb-Sm/Nd) the Passagem Granite, Pensamiento Granitoid Complex, Paragua Terrane, SW Amazon Craton, Mato Grosso, Brazil; Petrologia e geocronologia (U/Pb-Sm/Nd) do Granito Passagem, Complexo Granitoide Pensamiento, SW do Craton Amazonico (MT)

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, Gisely Carmo de, E-mail: giselycarmo@hotmail.co [Universidade Federal de Mato Grosso (ICET/UFMT), Cuiaba, MT (Brazil). Inst. de Ciencias Exatas e da Terra. Programa de Pos-Graduacao em Geociencias; Sousa, Maria Zelia Aguiar de, E-mail: mzaguiar@terra.com.b [Universidade Federal de Mato Grosso(ICET/UFMT), Cuiaba, MT (Brazil). Inst. de Ciencias Exatas e da Terra. Dept. de Recursos Minerais; Ruiz, Amarildo Salina; Matos, Joao Batista de, E-mail: asruiz@gmail.co, E-mail: jmatos@cpd.ufmt.b [Universidade Federal de Mato Grosso (ICET/UFMT), Cuiaba, MT (Brazil). Inst. de Ciencias Exatas e da Terra. Dept. de Geologia Geral

    2010-09-15

    The Passagem granite includes stocks, plugs and dikes located in the Ricardo Franco hill - Vila Bela da Santissima Trindade region - state of Mato Grosso, central Brazil. The Passagem Granite is included in the Paragua terrane - SW Amazonian Craton. It consists of isotropic monzogranite, sienogranite and more rarely granodiorites with leucocratic dark gray to white color. These rocks range from hypidomorphic inequigranular to xenomorphic texture, fine to medium grained. Biotite is the only primary mafic present as essential phase and characterize an expanded slightly acid sequence formed by a sub-alkaline magmatism of high-potassium calc-alkaline, slightly peraluminous composition from arc magmatic tectonic environment during a post-collisional period. Mechanism of fractional crystallization of plagioclase, biotite, titanite, apatite and zircon associated with simultaneous crustal assimilation are suggested for the evolution of these rocks. The results support the hypothesis of a post-collisional magmatism in the Paragua terrane at 1284 +- 20 Ma corresponding to the crystallization age of the Passagem granite. This paper propose that Passagem Granite represents as an extension in Brazilian terrane of the Pensamiento Granitoid Complex. (author)

  2. Measurement of activity concentration of {sup 222}Rn in ground waters drawn from two wells drilled in the Amparo Complex metamorphic rocks, municipio de Amparo, SP; Medida da atividade do {sup 222}Rn em aguas subterraneas extraidas de dois pocos perfurados em rochas metamorficas do Complexo Amparo, municipio de Amparo, SP

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Igor Jose Chaves de

    2008-07-01

    A sampling system was assembled for field {sup 222}Rn activity concentration measurements in ground waters. The system consists of a sampling flask that prevents the contact between the water sample and the atmosphere and a closed line for radon extraction from water. The system, its operation and calibration, are described in full detail, as well as, the conversion of the measured alpha counting rates in activity concentrations. The assembled system was used in {sup 222}Rn activity concentrations measurements in ground waters drawn from two wells drilled in the Amparo Complex metamorphic rocks. The wells are located at the urban area of the city of Amparo and are exploited for public use water. One well, named Vale Verde, is 56 meters deep and crosses 18 meters of soil, 26 meters of quartz rich gneiss and 12 meters of biotite-gneiss. The other well, named Seabra, is 117 meters deep, crosses 28 meters of soil and weathered rocks and ends in granite-gneiss. The mean activity concentrations for the year long observation were (377 +- 25) Bq/dm{sup 3}, for Seabra well, and (1282 +- 57) Bq/dm3, for the Vale Verde well. The {sup 222}Rn activity concentrations fall in the activity concentration range reported in the literature for similar geology areas and are larger than the concentrations found neighboring areas of the same metamorphic Complex. The seasonal activity concentration variations seem to correlate with rain fall variations in the study area. (author)

  3. Permian ultrafelsic A-type granite from Besar Islands group, Johor ...

    Indian Academy of Sciences (India)

    mon and developed mainly along the biotite cleav- age. Occasionally, secondary muscovite crystals can be seen developed in the biotite cleavage. The ...... 10.1016/j.gr.2013.03.019. Orajaka I P 1986 Geochemistry of Kaffo Valley albiteriebeckite-granite, Liruei granite ring-complex, northern Nigeria; Chem. Geol. 56 85–92.

  4. Petrography, mineral chemistry and lithochemistry of the albitite and granite-gneissics rocks of anomaly 35 from Lagoa Real uranium province

    International Nuclear Information System (INIS)

    Santos, Camila Marques dos

    2016-01-01

    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

  5. 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.

  6. Status of LLNL granite projects

    International Nuclear Information System (INIS)

    Ramspott, L.D.

    1980-01-01

    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. Geochemical characteristics of Proterozoic granite magmatism from ...

    Indian Academy of Sciences (India)

    T Yellappa

    2018-03-06

    -type granites; Neoproterozoic .... morphosed carbonates, iron formations and pelites, all suggesting an ..... Table 2. Average concentrations of whole rock geochemistry of different granite plutons of the present study. Location.

  8. 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...

  9. fracture systems in the younger granite rocks around fobur, northern ...

    African Journals Online (AJOL)

    Admin

    Bowden, P. and Turner, D.C., 1974. Peralkaline and associated ring complexes in the Nigerian-Niger. Province, West Africa. In: The Alkaline Rocks,. H. Serensen (ed) John Willey, New York. pp.330-351. Bowden, P., Whitley, J.E. and Van Breeman, O., 1989. Geochemical studies on the Younger Granites of northern Nigeria.

  10. Geology and structural outline of the Lagoa Real Complex, BA, Brazil

    International Nuclear Information System (INIS)

    Cruz, Simone Cerqueira Pereira; Cunha, Jose Carlos; Marinho, Moacir Moura; Noce, Carlos Mauricio

    2007-01-01

    The Lagoa Real Complex is constituted by 1.7 Ga granitoids that occur along the Paramirim valley. The granitoids are formed by the Sao Timoteo Granite and a set of alkali-gneisses that were crystallized during a compressional sin-metamorphic deformation episode. The carried out structural analysis has identified two deformation patterns. The compressional episode is represented by shear zones, compositional layering, milonite foliation and folds. The extensional episode is characterized by the nucleation of normal shear zones. The geometric patterns of the finite deformation are similar to the ones that occur in the Ituacu synclinal where the Salitre e Bebedouro formations of Una Group outcrop. An ancient geometric pattern was not found in the area; consequently we propose that the deformation episodes were related to the neoproterozoic Orogeny. (author)

  11. MORPHOMETRY OF ZIRCON FROM BETLIAR GRANITE

    Directory of Open Access Journals (Sweden)

    Jakabská Katarína

    1997-10-01

    Full Text Available Morphometrical analyse has been provided, using the method of [10] , on zircon from granite porphyry at Betliar. The result of this investigation indicate a comagmatic origin of Betliar and other granite bodies in the Gemericum. The source materila for at the granite magma formation originated by hybridization of crust-mantle rocks.

  12. Geochemical characteristics of Proterozoic granite magmatism from ...

    Indian Academy of Sciences (India)

    57

    Proterozoic A-type granites in parts of Madurai district, Tamil Nadu: Implications on uranium, rare earth, rare metal ... Key words: Southern Granulite Terrain, Cauvery Suture Zone, I-type and A-type granites, Neoproterozoic ...... I-S type characteristic in the Main Range Granite, Peninsular Malaysia; J. Asian Earth Sci.

  13. Measurements of cesium and strontium diffusion in biotite gneiss

    International Nuclear Information System (INIS)

    Skagius, K.; Neretnieks, I.

    1988-01-01

    A significant retardation of radionuclides transported by flowing water from an underground repository can be expected if the nuclides are able to diffuse into the water filled micropores in the rock. This diffusion into the pores will also increase the surface available to interactions between the nuclides in the ground water and the rock material, such as sorption. To calculate the retardation, it is necessary to know the sorption properties and the diffusivities in the rock matrix for the radionuclides. Diffusion experiments with cesium and strontium in biotite gneiss samples have been performed. Both the transport of strontium and cesium through rock samples and the concentration profiles of cesium and strontium inside rock samples have been determined. The result shows that diffusion of cesium and strontium occurs in the rock material. A diffusion model has been used to evaluate the diffusivity. Both pore diffusion and surface diffusion had to be included in the model to give good agreement with the experimental data. If surface diffusion is not included in the model, the effective pore diffusivity that gives the best fit to the experimental data is found to be higher than expected from earlier measurement of iodide diffusion in the same type of rock material. This indicates that the diffusion of cesium and strontium (sorbing components) in rock material is caused by both pore diffusion and surface diffusion acting in parallel

  14. Radon exhalation from granitic rocks

    International Nuclear Information System (INIS)

    Del Claro, Flávia; Paschuk, Sergei A.; Corrêa, Janine N.; Mazer, Wellington; Narloch, Danielle Cristine; Martin, Aline Cristina; Denyak, Valeriy

    2017-01-01

    Naturally occurring radionuclides such as radon ( 222 Rn), its decay products and other elements from the radioactive series of uranium ( 238 U and 235 U) and thorium ( 232 Th) are an important source of human exposure to natural radioactivity. The worldwide evaluation of health radiobiological effects and risks from population exposure to natural radionuclides is a growing concern. About 50% of personal radiation annual dose is related to radionuclides such as radon ( 222 Rn), thoron ( 220 Rn), radium ( 226 Ra), thorium ( 232 Th) and potassium ( 40 K), which are present in modern materials commonly used in construction of dwellings and buildings. The radioactivity of marbles and granites is of big concern since under certain conditions the radioactivity levels of these materials can be hazardous to the population and require the implementation of mitigation procedures. Present survey of the 222 Rn and 220 Rn activity concentration liberated in the air was performed using commercialized Brazilian granite rocks at national market as well as exported to other countries. The 222 Rn and 220 Rn measurements were performed using the AlphaGUARD instant monitor and RAD7 detector, respectively. This study was performed at the Applied Nuclear Physics Laboratory of the Federal University of Technology – Paraná (UTFPR). Obtained results of radon concentration activity in air exhaled studied samples of granites varied from 3±1 Bq/m 3 to 2087±19 Bq/m 3 , which shows that some samples of granitic rocks represent rather elevated health risk the population. (author)

  15. Potassium-argon ages of gneisses from the basin granitoid in South ...

    African Journals Online (AJOL)

    eastern Ghana were separated and analyzed for potassiumargon (K / Ar) ages. The results indicated that the gneisses have average biotite and hornblende ages of 1942 ± 11 Ma and 2044 ± 17 Ma, respectively. The highest single hornblende ...

  16. Radar, geologic, airborne gamma ray and Landsat TM digital data integration for geological mapping of the Estrela granite complex (Para State); Integracao digital de imagens de radar e Landsat-TM com dados geologicos e aerogamaespectrometricos no auxilio ao mapeamento geologico da regiao do complexo granitico Estrela-Para (PA)

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Edson Ricardo Soares Pereira da

    2002-07-01

    This work is focused on the geotectonic context of the Carajas Mineral Province, Amazon Craton, which represents the most important Brazilian Mineral Province and hosts iron, cooper, gold, manganese and nickel deposits. At the end of Archean age, during the techno-metamorphic evolution, moderated alkaline granitoids were generated, such as, Estrela Granite Complex (EGC). This work has used digital integration products with the purpose of study the granite suite, its host rock, and the surrounded area. The digital integrated data were gamma-ray and geological data with satellite images (SAR-SAREX e TM-Landsat). The geophysics data, originally in 32 bits and grid format, were interpolated and converted to 8 bits images. The geological data (facies map) was digitalized and converted to a raster format. The remote sensing images were geometrically corrected to guarantee an accuracy on the geological mapping. On the data processing phase, SAR images were digital integrated with gamma-ray data, TM-Landsat image and the raster facies map. The IHS transformation was used as the technique to integrate the multi-source data. On the photogeological interpretation, SAR data were extremely important to permit the extraction of the main tectonic lineaments which occur on the following directions: +/- N45W, +/- N70W, +/- NS, +/- N20E, +/- N45E e +/- N75E. This procedure was done both in analogic and automatic form, being the automatic process more useful to complement information in the extracting process. Among the digital products generated, SAR/GAMA products (uranium, thorium and total count) were the ones that give the most important contribution. The interpretation of the SAR/GAMA's products added to the field campaign have allowed to map the limits of units that occur in the region and four facies of the Estrela Granite Complex were detected. The origin of the granite suite might be related to a magmatic differentiation or to distinct intrusion pulses. The use of the

  17. The ongoing search for the oldest rock on the Danish island of Bornholm: new U-Pb zircon ages for a quartz-rich xenolith and country rock from the Svaneke Granite

    DEFF Research Database (Denmark)

    Waight, Tod Earle; Serre, Simon H.; Næsby, Sebastian H.

    2017-01-01

    Previous geochronological studies on the Danish island of Bornholm have not identified any rocks older than c. 1.46 Ga. New LA-ICP-MS U-Pb zircon ages are presented for a xenolith within, and the country rock gneiss adjacent to, the Svaneke Granite on Bornholm. The xenolith is fine-grained and qu......Previous geochronological studies on the Danish island of Bornholm have not identified any rocks older than c. 1.46 Ga. New LA-ICP-MS U-Pb zircon ages are presented for a xenolith within, and the country rock gneiss adjacent to, the Svaneke Granite on Bornholm. The xenolith is fine...... been a felsic volcanic or shallow intrusive rock. A skarn-like inclusion from a nearby locality likely represents an originally carbonate sediment and is consistent with supracrustal rocks being present at least locally. Zircon data from the xenolith define an upper intercept age of 1483 ± 12 Ma (2σ......, MSWD = 2.5) with a poorly defined lower intercept age of 474 ± 250 Ma, and a weighted average 207Pb/206Pb age of 1477.9 ± 4.6 Ma; both these ages are older than the host Svaneke Granite (weighted average 207Pb/206Pb age of 1465.0 ± 4.8 Ma). Zircons from the gneiss define an upper intercept age of 1477...

  18. Geophysical evaluation of groundwater potential in part of southwestern Basement Complex terrain of Nigeria

    Science.gov (United States)

    Bayewu, Olateju O.; Oloruntola, Moroof O.; Mosuro, Ganiyu O.; Laniyan, Temitope A.; Ariyo, Stephen O.; Fatoba, Julius O.

    2017-12-01

    The geophysical assessment of groundwater in Awa-Ilaporu, near Ago Iwoye southwestern Nigeria was carried out with the aim of delineating probable areas of high groundwater potential. The area falls within the Crystalline Basement Complex of southwestern Nigeria which is predominantly underlain by banded gneiss, granite gneiss and pegmatite. The geophysical investigation involves the very low frequency electromagnetic (VLF-EM) and Vertical Electrical Sounding (VES) methods. The VLF-EM survey was at 10 m interval along eight traverses ranging between 290 and 700 m in length using ABEM WADI VLF-EM unit. The VLF-EM survey was used to delineate areas with conductive/fractured zones. Twenty-three VES surveys were carried out with the use of Campus Ohmega resistivity meter at different location and at locations areas delineated as high conductive areas by VLF-EM survey. The result of VLF-EM survey along its traverse was used in delineating high conductive/fractured zones, it is, however, in agreement with the delineation of the VES survey. The VES results showed 3-4 geoelectric layers inferred as sandy topsoil, sandy clay, clayey and fractured/fresh basement. The combination of these two methods, therefore, helped in resolving the prospecting location for the groundwater yield in the study area.

  19. Matrix diffusion in crystalline rocks: coupling of anion exclusion, surface diffusion and surface complexation

    Energy Technology Data Exchange (ETDEWEB)

    Olin, M.; Valkiainen, M.; Aalto, H. [VTT Chemical Technology, Espoo (Finland)

    1997-12-01

    This report includes both experimental and modelling parts. Also, a novel approach to the diffusion experiments is introduced, where ions of the same electric charge diffuse in opposite directions through the same rock sample. Six rock-types from Olkiluoto radioactive waste disposal investigation site were used in the experiments: granite, weathered granite, mica gneiss, weathered mica gneiss, tonalite and altered mica gneiss/migmatite. The experiments consisted of the determination of the effective diffusion coefficient and the rock capacity factor for tritium, chloride (Cl-36) and sodium (Na-22). The modelling consisted of a chemical model for small pores (< 100 nm), a model for counter ion diffusion and models for the laboratory experiments. 21 refs.

  20. Radon exhalation from granitic rocks

    Energy Technology Data Exchange (ETDEWEB)

    Del Claro, Flávia; Paschuk, Sergei A.; Corrêa, Janine N.; Mazer, Wellington; Narloch, Danielle Cristine; Martin, Aline Cristina [Universidade Tecnológica Federal do Paraná (UTFPR), Curitiba, PR (Brazil); Denyak, Valeriy, E-mail: flaviadelclaro@gmail.com, E-mail: spaschuk@gmail.com, E-mail: janine_nicolosi@hotmail.com, E-mail: denyak@gmail.com [Instituto de Pesquisa Pelé Pequeno Príncipe (IPPP), Curitiba, PR (Brazil)

    2017-07-01

    Naturally occurring radionuclides such as radon ({sup 222}Rn), its decay products and other elements from the radioactive series of uranium ({sup 238}U and {sup 235}U) and thorium ({sup 232}Th) are an important source of human exposure to natural radioactivity. The worldwide evaluation of health radiobiological effects and risks from population exposure to natural radionuclides is a growing concern. About 50% of personal radiation annual dose is related to radionuclides such as radon ({sup 222}Rn), thoron ({sup 220}Rn), radium ({sup 226}Ra), thorium ({sup 232}Th) and potassium ({sup 40}K), which are present in modern materials commonly used in construction of dwellings and buildings. The radioactivity of marbles and granites is of big concern since under certain conditions the radioactivity levels of these materials can be hazardous to the population and require the implementation of mitigation procedures. Present survey of the {sup 222}Rn and {sup 220}Rn activity concentration liberated in the air was performed using commercialized Brazilian granite rocks at national market as well as exported to other countries. The {sup 222}Rn and {sup 220}Rn measurements were performed using the AlphaGUARD instant monitor and RAD7 detector, respectively. This study was performed at the Applied Nuclear Physics Laboratory of the Federal University of Technology – Paraná (UTFPR). Obtained results of radon concentration activity in air exhaled studied samples of granites varied from 3±1 Bq/m{sup 3} to 2087±19 Bq/m{sup 3}, which shows that some samples of granitic rocks represent rather elevated health risk the population. (author)

  1. Thermal expansion behaviour of granites

    Czech Academy of Sciences Publication Activity Database

    Plevová, Eva; Vaculíková, Lenka; Kožušníková, Alena; Ritz, M.; Simha Martynková, G.

    2016-01-01

    Roč. 123, č. 2 (2016), s. 1555-1561 ISSN 1388-6150 R&D Projects: GA MŠk ED2.1.00/03.0082; GA MŠk(CZ) LO1406 Institutional support: RVO:68145535 Keywords : thermomechanical analysis * differential thermal analysis * granites Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.953, year: 2016 http://link.springer.com/article/10.1007/s10973-015-4996-z

  2. The Keimoes Suite redefined: The geochronological and geochemical characteristics of the ferroan granites of the eastern Namaqua Sector, Mesoproterozoic Namaqua-Natal Metamorphic Province, southern Africa

    Science.gov (United States)

    Bailie, Russell; Macey, Paul Hugh; Nethenzheni, Sedzani; Frei, Dirk; le Roux, Petrus

    2017-10-01

    Voluminous granite gneisses and granites straddle the boundary between the Kakamas and Areachap Terranes in the eastern Namaqua Sector (NS) of the Mesoproterozoic Namaqua-Natal Metamorphic Province (NNMP). These rocks have been previously poorly defined and loosely grouped into the Keimoes Suite, but a recent U-Pb age study has suggested the suite be subdivided into syn-tectonic and post-tectonic groups relative to the main phase of the Namaqua Orogeny. This study adds new whole rock geochemical, isotopic and age data for these granites that confirms the subdivision is appropriate. The older group of syn-tectonic granite gneisses, dated between 1175 and 1146 Ma, have penetrative foliations and are largely derived from fractionated, leucogranitic metaluminous to peraluminous magmas with low maficity, low Ti, Mn and Ca. They were derived from mildly depleted sources (εNd(t): -1.47 to 1.78), with Meso-to Paleoproterozoic Nd model ages (1.57-1.91 Ga), and high initial Sr ratios (0.71970-0.75567) suggesting mixing between younger depleted and older, arc-like sources imparting an arc-like signature to the magmas. High initial Sr ratios appear to be an intrinsic character of these granites reflecting those of granites in the region and the highly radiogenic nature of the NS. The weakly to unfoliated late-to post-tectonic megacrystic granodiorites and monzogranites, including charnockites, intruded between 1110 and 1078 Ma and constitute the Keimoes Suite proper. They have I-type characteristics, being strongly metaluminous and locally hornblende- and orthopyroxene-bearing with moderate SiO2 and with arc-type affinities (LILE enrichment relative to the HFSE, Ta-Nb, Ti and P anomalies). However, the granitoids also have high Fe/Mg ratios, along with high HFSE, LILE and REE contents more indicative of A-type granites. They show an increasing maficity, metaluminous character, and general decreasing degree of fractionation with decreasing age. They are similar to the syn

  3. 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 (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 syn-rift basin subsidence values. Results showing extension is preferentially accommodated in the lower crust are used to constrain a 2-D numerical model of uplift of the DEI domes showing vertical exhumation of post-orogenic lower crust driven by far-field extension and an inverted two-layer crustal density structure.

  4. Alkaline lixiviation of uranium in granitic pegmatite

    International Nuclear Information System (INIS)

    Jambor, S.

    1980-06-01

    The work described herein concerns the determination of the experimental optimum conditions for the alkaline lixiviation of uranium based on the following parameters: time, pH, temperature, density and grane size. The samples were obtained from the Supamo complex, near the Currupia river in the Piar District of the Bolivar State in Venezuela. They have a granitic composition and graphitic texture. The uranium was found in them as a secondary oxidized mineral of green-yellow colour localized in fractures fissures, intergranular spaces and also in the mica as. Secondary uranitite. The lixiviation process was carried out using Na 2 CO 3 /NaHCO 3 buffer solution and for 100 gr. samples the best values for an efficient process were found by using 170 mesh grane size and 500 ml of pH buffer at 70 0 C for a 24 hour time period. (author)

  5. Natural radionuclide distribution in Brazilian commercial granites

    International Nuclear Information System (INIS)

    Anjos, R.M.; Veiga, R.; Soares, T.; Santos, A.M.A.; Aguiar, J.G.; Frasca, M.H.B.O.; Brage, J.A.P.; Uzeda, D.; Mangia, L.; Facure, A.; Mosquera, B.; Carvalho, C.; Gomes, P.R.S.

    2005-01-01

    The dimension stones sector in Brazil produces several varieties of granites, marbles, slates and basalts. More than half of this production corresponds to around 200 different commercial types of granites with specific names, geographical and geological origins and mineral compositions. The well-known natural radioactivity present in rocks, where high radiation levels are associated with igneous rocks such as granite, can be used to determine their general petrologic features. This subject is important in environmental radiological protection, since granites are widely used as building and ornamental stones. In this paper, it is applied to correlate the petrographic characteristics of commercial granites with their corresponding dose rates for natural radioactivity. Amounts of thorium, uranium and potassium concentrations have been reported in several Brazilian commercial granite samples

  6. Himalayan gneiss dome formation in the middle crust and exhumation by normal faulting: New geochronology of Gianbul dome, northwestern India

    Science.gov (United States)

    Horton, Forrest; Lee, Jeffrey; Hacker, Bradley; Bowman-Kamaha'o, Meilani; Cosca, Michael A.

    2015-01-01

    A general lack of consensus about the origin of Himalayan gneiss domes hinders accurate thermomechanical modeling of the orogen. To test whether doming resulted from tectonic contraction (e.g., thrust duplex formation, antiformal bending above a thrust ramp, etc.), channel flow, or via the buoyant rise of anatectic melts, this study investigates the depth and timing of doming processes for Gianbul dome in the western Himalaya. The dome is composed of Greater Himalayan Sequence migmatite, Paleozoic orthogneiss, and metasedimentary rock cut by multiple generations of leucogranite dikes. These rocks record a major penetrative D2 deformational event characterized by a domed foliation and associated NE-SW–trending stretching lineation, and they are flanked by the top-down-to-the-SW (normal-sense) Khanjar shear zone and the top-down-to-the-NE (normal sense) Zanskar shear zone (the western equivalent of the South Tibetan detachment system). Monazite U/Th-Pb geochronology records (1) Paleozoic emplacement of the Kade orthogneiss and associated granite dikes; (2) prograde Barrovian metamorphism from 37 to 33 Ma; (3) doming driven by upper-crustal extension and positive buoyancy of decompression melts between 26 and 22 Ma; and (4) the injection of anatectic melts into the upper levels of the dome—neutralizing the effects of melt buoyancy and potentially adding strength to the host rock—by ca. 22.6 Ma on the southwestern flank and ca. 21 Ma on the northeastern flank. As shown by a northeastward decrease in 40Ar/39Ar muscovite dates from 22.4 to 20.2 Ma, ductile normal-sense displacement within the Zanskar shear zone ended by ca. 22 Ma, after which the Gianbul dome was exhumed as part of a rigid footwall block below the brittle Zanskar normal fault, tilting an estimated 5°–10°SW into its present orientation.

  7. Achaean TTG and high alimunia gneisses on Baltic Shield: Precise U-Pb (ID-TIMS) and SHRIMP-II ages on single zircon

    Science.gov (United States)

    Bayanova, Tamara; Morozova, Ludmila; Mitrofanov, Felix; Serov, Pavel; Nitkina, Elena; Fedotov, Dzorzh; Larionov, Alexander

    2014-05-01

    New U-Pb (ID-TIMS) data on single zircon from high alimunia gneisses near Murmansk in the Central-Kola domain gave 3.17 Ga. Core from these zircon population has the age 3695±5 Ma by SHRIMP-II. Time of amphibolites metamorphism was dated with 2753±3 Ma. Achaean gneisses in Monchegorsk ore region were firstly dated in the Central-Kola domain. Single zircon from gneisses in Monchegorsk region which are the basement for Paleoproterozoic PGE layered intrusions with U-Pb ages on zircon and baddeleyite from 2.4-to 2.5 Ga (Bayanova et all, 2009) has 3.16 Ga. Single zircon from gnneisses gave 2776±3 Ma and is considered as amphibolites metamorphism. Voche-Lambina international polygon lies on the boundary between Belomorian mobile block and Central -Kola domain (Morozova et al, 2011). New neoarhaean U-Pb data on single zircon from TTG of polygon yielded 3158.2±8.2. Zircon are characterized by low concentration U and Pb, low U/Th ratio with 0.2. REE diagrams of grey gneisses reflect high fractionation La/Yb>30,encriched by light REE and depleted by heavy Yb<0.6 ppm. Model Sm-Ng ages on the rocks have protolith from with the ages 3.4 to 3.2 Ga, positive ɛNd from +1.29 to +3.3, ISr equals 0.702. Precise (ID-TIMS) age of amphibolites metamorphism has been dated on single zircon with 2704.3±5.9 Ma. In the frame of the Central-Kola domain there is an Ingosersky TTG complex. Firstly U-Pb dating on single zircon from Bt-gneisses reflects 3149±49 Ma. Metamorphic alterations were in 2725.2±2.5 Ma and connected with origin of Amf-Bt gneisses and 2733.6±6.6 with Bt-Amf gneisses. (NItkina et al., 2012). Therefore based on the new data on single zircon from TTG and high alimunia gneisses from Central-Kola domain leads to the long history of continental crust origin in the Baltic or Fennoscandian Shield from 3.16 to 3.7 Ga. We thank to G. Wasserburg for 205 Pb artificial spike, J. Ludden for 91500 and Temora standards, F. Corfu, V. Todt and U. Poller for assistance in the

  8. The Taitao Granites: I-type granites formed by subduction of the Chile Ridge and its implication in growth of continental crusts

    Science.gov (United States)

    Anma, Ryo

    2016-04-01

    Late Miocene to Early Pliocene granite plutons are exposed at the tip of the Taitao peninsula, the westernmost promontory of the Chilean coast, together with a contemporaneous ophiolite with a Penrose-type stratigraphy. Namely, the Taitao granites and the Taitao ohiolite, respectively, are located at ~30 km southeast of the Chile triple junction, where a spreading center of the Chile ridge system is subducting underneath the South America plate. This unique tectonic setting provides an excellent opportunity to study the generation processes of granitic magmas at a ridge subduction environment, and the complex magmatic interactions between the subducting ridge, overlying crust and sediments, and mantle. This paper reviews previous studies on the Taitao ophiolite/granite complex and use geochemical data and U-Pb age distributions of zircons separated from igneous and sedimentary rocks from the area to discuss the mechanism that formed juvenile magma of calc-alkaline I-type granites during ridge subduction. Our model implies that the magmas of the Taitao granites formed mainly due to partial melting of hot oceanic crust adjacent to the subducting mid-oceanic ridge that has been under influence of deep crustal contamination and/or metasomatized sub-arc mantle through slab window. The partial melting took place under garnet-free-amphibolite conditions. The juvenile magmas then incorporated a different amount of subducted sediments to form the I-type granites with various compositions. The Taitao granites provide an ideal case study field that shows the processes to develop continental crusts out of oceanic crusts through ridge subduction.

  9. Recycling of gneiss rock waste in the manufacture of vitrified floor tiles.

    Science.gov (United States)

    Souza, A J; Pinheiro, B C A; Holanda, J N F

    2010-01-01

    The present study focuses on the recycling of gneiss rock waste generated by the ornamental rock industry for manufacturing vitrified floor tile products. The gneiss rock waste came from a rock-cutting plant located in Santo Antônio de Pádua-RJ, Brazil. Initially the waste sample was characterized for chemical composition, X-ray diffraction, particle size, morphology, and pollution potential. Floor tiles containing up to 47.5wt.% waste were prepared. The tiles were tested to determine their physical-mechanical properties (linear shrinkage, water absorption, apparent density, and flexural strength). Microstructural evolution was carried out by scanning electron microscopy. The results indicate that the gneiss rock waste could be used for vitrified floor tile production, resulting in a new possibility for recycling this waste and conserving natural resources. 2009 Elsevier Ltd. All rights reserved.

  10. Geology and structural outline of the Lagoa Real Complex, BA, Brazil;Geologia e arcabouco estrutural do Complexo Lagoa Real, Vale do Paramirim, Centro-Oeste da Bahia

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Simone Cerqueira Pereira, E-mail: simoneufba@gmail.co [Universidade Federal da Bahia (IG/UFBA), Salvador, BA (Brazil). Inst. de Geociencias; Alkmim, Fernando Flecha; Jordt-Evangelista, Hanna, E-mail: ffalkmim@gmail.co [Universidade Federal de Ouro Preto (DG/UFOP), MG (Brazil). Dept. de Geologia; Leite, Carlson Matos Maia, E-mail: cmmleite@petrobras.com.b [PETROBRAS, Salvador, BA (Brazil); Cunha, Jose Carlos; Marinho, Moacir Moura, E-mail: zecunha@cbpm.com.b [Companhia Baiana de Pesquisa Mineral, Salvador, BA (Brazil). Centro Administrativo da Bahia; Matos, Evando Carele, E-mail: carele@inb.b [Industrias Nucleares do Brasil, Caetite, BA (Brazil); Noce, Carlos Mauricio [Universidade Federal de Minas Gerais (DG/IG/UFMG), Belo Horizonte (Brazil). Inst. de Geociencias. Dept. de Geologia

    2007-12-15

    The Lagoa Real Complex is constituted by 1.7 Ga granitoids that occur along the Paramirim valley. The granitoids are formed by the Sao Timoteo Granite and a set of alkali-gneisses that were crystallized during a compressional sin-metamorphic deformation episode. The carried out structural analysis has identified two deformation patterns. The compressional episode is represented by shear zones, compositional layering, milonite foliation and folds. The extensional episode is characterized by the nucleation of normal shear zones. The geometric patterns of the finite deformation are similar to the ones that occur in the Ituacu synclinal where the Salitre e Bebedouro formations of Una Group outcrop. An ancient geometric pattern was not found in the area; consequently we propose that the deformation episodes were related to the neoproterozoic Orogeny. (author)

  11. Radionuclide migration through fractured granite

    International Nuclear Information System (INIS)

    Grondin, D.M.; Vandergraaf, T.T.; Drew, D.J.

    1988-01-01

    Radionuclide migration has been studied in natural fractures in granite blocks of up to 30 cm in length. Results are reported for four migration experiments involving synthetic groundwaters containing tritiated water, 95m Tc, 75 Se, 137 Cs, or 60 Co-labelled natural colloids, which were injected into the fractures at flow rates of 0.4-0.45 mL/h, giving residence times in the fractures of up to 15 h. Also presented are the results of the post-experiment analyses, including an autoradiograph of one of the fracture surfaces, and the spatial distribution of the sorbed radionuclides determined by γ-scanning and selective chemical extractions

  12. U-Th mineralisation in Berach Granite around Belwa, Devtalai and Gudalia, Bhilwara, Rajasthan

    International Nuclear Information System (INIS)

    Saini, S.N.; Yadav, G.S.; Fahmi, Sohail

    2008-01-01

    Uranium - thorium mineralization in Belwa, Devtalai and Gudalia areas is hosted in pink phase of Berach Granite (BG) at the western intrusive contact with the rocks of Mangalwar Complex (MC) in the northern apical region of the granite body. It occurs at the foot wall side of copper mineralization that is associated with quartz reefs. Although surface manifestation of mineralization is limited, its subsurface continuity has been traced over 5 km length in between Belwa and Gudalia. Core samples of pink granite have radiometrically assed from 0.014 to 0.036% U 3 O 8 , <0.01 to 0.032% U 3 O 8 and <0.005 to 0.015 ThO 2 . The Berach Granite (BG) has two phases. An early grey and later pink phase. The pink variety hosts mineralization and is a high silica, low-Ca and peraluminous granite, while the grey granite is characterised by low-silica and high-Ca content. Mineralisation falls along the Bharatpur-Mount Abu lineament, close to thrust zone of Mangalwars and Jahazpurs. Radioactivity due to uranium and thorium in pink granite is associated with titanomagnetite, zircon, ilmenite and monazite. (author)

  13. A-type granite and the Red Sea opening

    Science.gov (United States)

    Coleman, R.G.; DeBari, S.; Peterman, Z.

    1992-01-01

    Miocene-Oligocene A-type granite intrudes the eastern side of the Red Sea margin within the zone of extension from Jiddah, Saudi Arabia south to Yemen. The intrusions developed in the early stages of continental extension as Arabia began to move slowly away from Africa (around 30-20 Ma). Within the narrow zone of extension silicic magmas formed dikes, sills, small plutons and extrusive equivalents. In the Jabal Tirf area of Saudi Arabia these rocks occur in an elongate zone consisting of late Precambrian basement to the east, which is gradually invaded by mafic dikes. The number of dikes increases westward until an igneous complex is produced parallel to the present Red Sea axis. The Jabal Tirf igneous complex consists of diabase and rhyolite-granophyre sills (20-24 Ma). Although these are intrusine intrusive rocks their textures indicate shallow depths of intrusion (Yemen, contemporaneous with alkali basaltic eruptions (26-30 Ma) and later silicic eruptions, small plutons, dikes, and stocks of alkali granite invaded thick (1500 m) volcanic series, at various levels and times. Erosion within the uplifted margin of Yemen suggests that the maximum depth of intrusion was less than 1-2 km. Granophyric intrusions (20-30 Ma) within mafic dike swarms similar to the Jabal Tirf complex are present along the western edge of the Yemen volcanic plateau, marking a north-south zone of continental extension. The alkali granites of Yemen consist primarily of perthitic feldspar and quartz with some minor alkali amphiboles and acmite. These granites represent water-poor, hypersolvus magmas generated from parent alkali basalt magmas. The granophyric, two-feldspar granites associated with the mafic dike swarms and layered gabbros formed by fractional crystallization from tholeiitic basalt parent developed in the early stages of extension. Initial 87Sr/86Sr ratios of these rocks and their bulk chemistry indicate that production of peralkaline and metaluminous granitic magmas involved

  14. Geochronological data for lithostratigraphic complexes of a crystalline basement from the South regions of Minas Gerais and adjacent areas of the Sao Paulo state

    International Nuclear Information System (INIS)

    Kawashita, K.; Artur, A.C.; Wernick, E.

    1988-01-01

    New geochronological data (Rb/Sr, Pb/Pb) for the Amparo and Pinhal Complexes, southern State of Minas Gerais and adjacent areas of the State of Sao Paulo are presented and discussed with respect to other lithostratigraphic complexes which there occur. Among the different complexes considered, 4 are composed mainly by rock belonging to typical infrastructure associations. They are the Barcelona, the Guaxupe, the Amparo and the Pinhal complexes. The Barbacena Complex is a typical gray gneiss complex and geochronological data by different methods confirm its Archean age. The Guaxupe Complex is composed mainly by different types of charnockitic rocks and an Archean age is assumed on geotectonic basis due to its neighboring association with the gray gneiss/greenstone belt, a though confirming geochronological data are still missing, a normal feature in this type of mobile belts which generally show a complex, polycyling evolution. Geochronological data by different methods on diverse rock types indicates that the Amparo and Pinhal complexes are respectively of Lower an Upper proterozoic age. Geochronological, geological and petrographic data reveal that both complexes are composed mainly by 3 basic rock associations: a-mainly derived magmatic rocks including mafic/ultramafic ones as well as calc-alkaline, subalcaline and even alkaline granitoids; b-orthogneisses, migmatites and crustal granites derived by metamorphic processes acting on older, pre-existing rocks; corthogneisses and migmatites resulting from metamorphic processes acting on magmatic rocks intruded during the same tecto-metamorphic cycle during which its transformation took place. The results suggest a polycyclic evolution by successive tecto-metamorphic events which affected the older rocks of the considered are either by the reworking of enclosing rocks around pericratonic continental main magmatic arcs or by the remobilisation of older basement rocks during continental collisions. (author) [pt

  15. FROGS (Friends of Granites) report

    Science.gov (United States)

    Miller, Calvin

    This VGP News, which is devoted to petrology, is a good one for noting the existence of FROGS. FROGS is, as the name suggests, an informal organization of people whose research relates in one way or another to granitic rocks. Its purpose has been to promote communication among geoscientists with different perspectives and concerns about felsic plutonism. Initially, a major focus was experimental petrology and integration of field-oriented and lab-oriented viewpoints; now that there is the opportunity to communicate with the Eos readership, an obvious additional goal will be to bring together volcanic and plutonic views of felsic magmatism.FROGS first gathered in late 1982 under the guidance of E-an Zen and Pete Toulmin (both at U.S. Geological Survey (USGS), Reston, Va.), who saw a need for greater interaction among those interested in granites and for renewed, focused experimental investigations. They produced two newsletters (which were sent out by direct mail) and organized an informal meeting at the Geological Society of America meeting at Indianapolis, Ind., and then turned over the FROG reins to Sue Kieffer (USGS, Flagstaff, Ariz.) and John Clemens (Arizona State University, Tempe). They generated another newsletter, which was directly mailed to a readership that had grown beyond 200.

  16. Characterization of weathering profile in granites and ...

    Indian Academy of Sciences (India)

    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, ...

  17. Characterization of weathering profile in granites and ...

    Indian Academy of Sciences (India)

    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 volcanosed- imentrary rocks. Therefore, we propose three models describing the weathering profiles in granites, metasediments ...

  18. Pb–Pb zircon ages of Archaean metasediments and gneisses from ...

    Indian Academy of Sciences (India)

    Pb–Pb zircon ages of Archaean metasediments and gneisses. 647. 3.1 Samples from the western Dharwar craton (WDC). 3.1.1 Quartzite, quartz–mica–chlorite schist, and paragneiss from Sargur Group. We sampled a quartzite representative of Sargur. Group from a hillock near Thattekere village. (WD-1; 12. ◦. 48 16.4 N ...

  19. Pb–Pb zircon ages of Archaean metasediments and gneisses from ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 120; Issue 4. Pb–Pb zircon ages of Archaean metasediments and gneisses from the Dharwar craton, southern ... of Earth Sciences, Manipur University, Canchipur, Imphal 795 003, Manipur, India. Geomysore Services (India) Pvt. Ltd., Bangalore 560 028, India.

  20. Rubidium-strontium whole-rock ages of Kataragama and Pottuvil charnockites and East Vijayan gneiss: Indication of a 2 Ga metamorphism in the highlands of southeast Sri Lanka

    Energy Technology Data Exchange (ETDEWEB)

    De Maesschalck, A.A.; Oen, I.S. (Vrije Universiteit, Amsterdam (Netherlands)); Hebeda, E.H.; Verschure, R.H. (NWO Laboratorium voor Isotopen Geologie, Amsterdam (Netherlands)); Arps, C.E.S. (RGM, Leiden (Netherlands))

    1990-09-01

    Highland Group granulite-facies rocks of the Kataragama klippe in southeast Sri Lanka yield a Rb-Sr whole-rock apparent age of 1,930 {plus minus} 130 Ma, MSWD = 39, and a {sup 87}Sr/{sup 86}Sr intercept of 0.715 {plus minus} 0.005, indicating a Highlandian metamorphism about 2.0 Ga ago. A charnockitic gneiss at Komari near Pottuvil, east Sri Lanka, gives a Rb-Sr whole-rock isochron age of 820 {plus minus} 70 Ma, MSWD = 0.78, initial {sup 87}Sr/{sup 86}Sr = 0.725 {plus minus} 0.007, suggesting a metamorphic resetting at about 0.8 Ga. The Rb-Sr whole-rock data of an East Vijayan biotite-hornblende gneiss fit a reference isochron of 800 Ma with a {sup 87}Sr/{sup 86}Sr intercept of 0.705; the low {sup 87}Sr/{sup 86}Sr intercept may be explained by a juvenile addition to the older crust. A review of available data from various isotopic dating methods suggests that the Highland Group supracrustals were deposited 2.5-2.0 Ga ago, metamorphosed in the granulite-facies about 2.0 Ga (M1) ago, and disturbed by resetting events about 1.1 Ga (M2), 0.8 Ga (M3), and 0.55 Ga (M4) ago. The East Vijayan supracrustals were deposited 2.0-1.1 Ga ago, invaded by granites and metamorphosed in the amphibolite-facies about 1.1 Ga (M2) ago, and disturbed by resetting events about 0.8 (M3) and 0.55 Ga (M4) ago. Overthrusting of the Kataragama granulites over the East Vijayan gneisses occurred post-M3.

  1. Thermal expansion of granite rocks

    International Nuclear Information System (INIS)

    Stephansson, O.

    1978-04-01

    The thermal expansion of rocks is strongly controlled by the thermal expansion of the minerals. The theoretical thermal expansion of the Stripa Granite is gound to be 21 . 10 -6 [deg C] -1 at 25 deg C and 38 . 10 -6 [deg C] -1 at 400 deg C. The difference in expansion for the rock forming minerals causes micro cracking at heating. The expansion due to micro cracks is found to be of the same order as the mineral expansion. Most of the micro cracks will close at pressures of the order of 10 - 20 MPa. The thermal expansion of a rock mass including the effect of joints is determined in the pilot heater test in the Stripa Mine

  2. Automated tone grading of granite

    International Nuclear Information System (INIS)

    Catalina Hernández, J.C.; Fernández Ramón, G.

    2017-01-01

    The production of a natural stone processing plant is subject to the intrinsic variability of the stone blocks that constitute its raw material, which may cause problems of lack of uniformity in the visual appearance of the produced material that often triggers complaints from customers. The best way to tackle this problem is to classify the product according to its visual features, which is traditionally done by hand: an operator observes each and every piece that comes out of the production line and assigns it to the closest match among a number of predefined classes, taking into account visual features of the material such as colour, texture, grain, veins, etc. However, this manual procedure presents significant consistency problems, due to the inherent subjectivity of the classification performed by each operator, and the errors caused by their progressive fatigue. Attempts to employ automated sorting systems like the ones used in the ceramic tile industry have not been successful, as natural stone presents much higher variability than ceramic tiles. Therefore, it has been necessary to develop classification systems specifically designed for the treatment of the visual parameters that distinguish the different types of natural stone. This paper describes the details of a computer vision system developed by AITEMIN for the automatic classification of granite pieces according to their tone, which provides an integral solution to tone grading problems in the granite processing and marketing industry. The system has been designed to be easily trained by the end user, through the learning of the samples established as tone patterns by the user. [es

  3. 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

  4. Geochemistry and geochronology Rb-Sr, K-Ar and 40Ar/39Ar of the Pan-African granitic complexes of the Tamanrasset area (Algeria): relationships with the associated Sn-W mineralizations and tectonic evolution of Central Hoggar

    International Nuclear Information System (INIS)

    Bertrand, J.M.; Zimmermann, J.L.; Dautel, D.; Boullier, A.M.; Bouabsa, L.; Farrar, E.; Archibald, D.A.; Moulahoum, O.

    1992-01-01

    New field mapping, petrographic and mineralogic, geochemical and geochronological data allow us to distinguish two successive magmatic suites with contrasting geochemistry: (1) granites with subalkaline affinity between 615 Ma (Anfeg) and 576 Ma (Tifferkit); (2) peraluminous magmatism and Li-F specialized leucogranites with associated Sn-W mineralization between 539 and 525 Ma. Such a magmatic evolution is interpreted as resulting from thickening of the continental crust during the Pan-African collision. Earliest magmas show mantle contribution and were formed close to the crust-mantle boundary where synchronous crustal stacking developed in amphibolite facies conditions. Latest peraluminous magmatism of crustal derivation and albite-topaz leucogranites appear to be controlled by localized extensional structures, 80 Ma after the main tectono-metamorphic event

  5. Determination of dispersity of crushed granite

    International Nuclear Information System (INIS)

    Liu Dejun; Fan Xianhua; Zhang Yingjie; Yao Jun; Zhou Duo; Wang Yong

    2004-01-01

    The experimental crushed granite column breakthrough curves, using 99 Tc as spike tracer and 3 H as invariant tracer, are analyzed by different linear regression techniques. Dispersity of crushed granite and retardation factor of 99 TcO 4 - on the crushed granite are determined simultaneously by one linear regression technique. Dispersity of crushed granite is also obtained with 3 H as invariant tracer by the other linear regression technique. The dispersities found by spike source and invariant source methods are compared. The experimental results show that the dispersity found by spike source method is close to that found by invariant source method. It indicates that dispersity is only the characteristic of dispersion medium

  6. Determination of dispersity of crushed granite

    International Nuclear Information System (INIS)

    Liu, D.J.; Fan, X.H.

    2005-01-01

    Experimental crushed granite column breakthrough curves, using 99 Tc as spike tracer and 3 H as invariant tracer, were analyzed by different linear regression techniques. Dispersity of crushed granite and the retardation factor of 99 TcO 4 - on the crushed granite were determined simultaneously by one linear regression. Dispersity of crushed granite was also obtained with 3 H as invariant tracer by the other linear regression. The dispersities found by spike source and invariant source methods are compared. Experimental results show that the dispersity found by the spike source method is close to that found by the invariant source method. This indicates that dispersity is only a characteristic of the dispersion medium. (author)

  7. An Early Cretaceous garnet-bearing metaluminous A-type granite intrusion in the East Qinling Orogen, central China: Petrological, mineralogical and geochemical constraints

    Directory of Open Access Journals (Sweden)

    Jinyang Zhang

    2012-09-01

    Full Text Available The Erlangmiao granite intrusion is located in the eastern part of the East Qinling Orogen. The granite contains almost 99 vol.% felsic minerals with accessory garnet, muscovite, biotite, zircon, and Fe-Ti oxide. Garnet is the dominant accessory mineral, shows zoned texture, and is rich in w(FeO (14.13%–16.09% and w(MnO (24.21%–27.44%. The rocks have high SiO2, alkalis, FeOt/MgO, TiO2/MgO and low Al2O3, CaO with w(Na2O/w(K2O> 1. Their Rb, Ga, Ta, Nb, Y, and Yb contents are high and Sr, Ba, Eu, Zr, P, and Ti contents are low. These features indicate that the Erlangmiao granite is a highly evolved metaluminous A-type. Garnet crystallized at the expense of biotite from the MnO-rich evolved melt after fractionation of biotite, plagioclase, K-feldspar, zircon, apatite, and ilmenite. The relatively high initial 87Sr/86Sr ratios (0.706–0.708, low and negative εNd (120 Ma values (−6.6 to −9.0, and old Nd model ages (1.5–1.7 Ga suggest that the rocks were probably formed by partial melting of the Paleoproterozoic granitic gneisses from the basement, with participation of depleted mantle in an extensional setting.

  8. Groundwater evolution of the granite area, Korea

    International Nuclear Information System (INIS)

    Kim, C.S.; Bae, D.S.; Koh, Y.K.; Kim, K.S.; Kim, G.Y.

    2001-01-01

    The geochemistry and environmental isotopes of groundwater in the Cretaceous granite of the Yeongcheon area has been investigated. The hydrochemistry of groundwater belongs to the Ca-HCO 3 type. The oxygen-18 and deuterium data are clustered along the meteoric water line, indicating that the groundwater is of meteoric water origin. Tritium data show that the groundwaters were mostly recharged before pre-thermonuclear period and have been mixed with younger surface water flowing rapidly along fractured zones. Based on the mass balance and reaction simulation approaches using both the hydrochemistry of groundwater and the secondary mineralogy of fracture-filling materials, the low-temperature hydrogeochemical evolution of groundwater in the area has been modeled. The results of geochemical simulation show that the concentrations of Ca, Na and HCO 3 and pH of waters increase progressively owing to the dissolution of reactive minerals in flow paths. The concentrations of Mg and K first increase with the dissolution of reactant minerals, but later decrease when montmorillonite and illitic material are precipitated respectively. The continuous adding of reactive minerals, i. e. the progressively larger degrees of water/rock interaction, causes the formation of secondary minerals with the following sequence: hematite > gibbsite > kaolinite > montmorillonite > illitic material > microcline. The results of reaction simulation agree well with the observed water chemistry and secondary mineralogy, indicating the successful applicability of this simulation technique to delineate the complex hydrogeochemistry of bedrock groundwaters. (author)

  9. Rn-222 release to the environment: comparison between different granite sources

    International Nuclear Information System (INIS)

    Mamoon, M.; Kamal, S.M.

    2005-01-01

    In this work three different types of granites were studied, namely: pure granite, alkali granite and altered (hydrated) alkali granite. General radioactivity of the granites was studied along with the potential for 222 Rn emanation. The study indicated that altered alkali granite releases, relatively, the highest 222 Rn emanation to the surrounding air while alkali granite emits the more intense gamma radiation of the three granites. Hence, altered alkali granite can be used as a laboratory source for 222 Rn.

  10. Gneiss Macuira: tectonic evolution of Paleozoic metamorphic rocks of the Alta Guajira, Colombia

    International Nuclear Information System (INIS)

    Lopez I; A Julian; Zuluaga C; A, Carlos

    2012-01-01

    The Macuira Gneiss is a Paleozoic metamorphic unit that outcrops in the Simarua, Jarara and Macuira ranges, Alta Guajira. It is composed by a lithologies metamorphosed under amphibolite facies P-T conditions and consist of amphibolitic and quartz feldspathic gneisses, amphibolites, schists, pegmatites, calc-silicated rocks and marbles, with migmatization evidences in gneisses and amphibolites. Five foliations (S1-5) and three folding events (F1-3) were identified and interpreted as product of two metamorphic events, developed in a progressive barrovian metamorphic gradient of intermediate pressure with intermediate P-T ratio, interpreted as product of continental collision tectonics. This unit is important in understanding of the tectonic evolution of the Alta Guajira and Caribbean because it records different deformational phases pre-, syn- and post-migmatitic, that could be related with different tectonic episodes: the first associated with the collision between Laurasia and Gondwana (Alleghanian Orogeny - Late Paleozoic), and the second related with the Caribbean Plate evolution (Andean Orogeny - Meso-Cenozoic).

  11. Reconnaissance Rb-Sr dates for the Himalayan Central Gneiss, Northwest India

    International Nuclear Information System (INIS)

    Powell, C. McA.; Crawford, A.R.; Armstrong, R.L.; Wynne-Edwards, H.R.; Prakash, R.

    1979-01-01

    Rb-Sr analysis of whole-rock samples and biotite and biotite - or muscovite - whole rock pairs suggests that the Himalayan Central Gneiss in the crystalline nappes of the Lesser Himalaya and the root zone in the High Himalaya was formed during Oligocene to mid-Miocene times by deformation and metamorphism of older rocks, including Precambrian. Four whole-rock samples from the Almora-Askot thrust sheets define an isochron of 1620 +- 90 Ma with a high initial 87 Sr/ 86 Sr ratio of 0.749 +- 0.007; other single whole-rock samples give dates in the range 268 to 1065 Ma, assuming an initial 87 Sr/ 86 Sr ratio of 0.704. These dates are considered to represent either depositional or early instructive/deformational events. Three biotite-whole rock pairs from the root zone of the Himalayan Central Gneiss in Lahaul give aqes of 16 to 19 Ma and two muscovite-whole rock pairs give similar mid-Cenozoic ages (12 and 26 Ma); two muscovite-whole rock pairs give Paleozoic ages, which suggests incomplete resetting of the muscovite by the Cenozoic metamorphism. The pattern of ages is similar to recent results from adjacent areas, and consistent with models of Himalayan tectonics involving formation of the Central Gneiss from older Indian crust during the mid-Cenozoic. (auth.)

  12. Lu-Hf total-rock age for the Amîtsoq gneisses, West Greenland

    Science.gov (United States)

    Pettingill, H.S.; Patchett, P.J.

    1981-01-01

    Lu-Hf total-rock data for the Amîtsoq gneisses of West Greenland yield an age of 3.55±0.22Gy(2σ), based on the decay constant λ176Lu=1.96×10−11y−1, and an initial176Hf/177Hf ratio of 0.280482±33. The result is in good agreement with Rb-Sr total-rock and U-Pb zircon ages. In spite of severe metamorphism of the area at 2.9 Gy, zircons from two of the samples have remained on the total-rock line, and define points close to the initial Hf ratio. The initial176Hf/177Hf lies close to a chondritic Hf isotopic evolution curve from 4.55 Gy to present. This is consistent with the igneous precursors to the Amîtsoq gneisses having been derived from the mantle at or shortly before 3.6 Gy. Anomalous relationships between Hf concentration and the176Lu/177Hf ratio may suggest that trace element abundances in the Amîtsoq gneisses are partly controlled by processes related to metamorphism.

  13. Age of Pedra Branca granite (Goias) and possible geotectonic implications

    International Nuclear Information System (INIS)

    Marini, O.J.; Botelho, N.F.; Macambira, M.J.B.; Provost, A.

    1986-01-01

    Rb-Sr geochronologic dating of granites from the Pedra Branca Granite Massif (Nova Roma, Goias) shown an age of 1405 ± 21My. and a questionable initial Sr 87 /Sr 86 ratio of 0,7004 ± 0,006. Rhyolite from the base of the Arai Group is probably of the same age as the granitic intrusion. The 475 ± 19 My. age for the granitic intrusion is evidence of the Brasiliano Cycle imprint in Pedra Branca region. The age attributed to the Pedra Branca Granite is lower than known ages of the Goias tin granites giving rise to new geotectonic interpretations. It is possible that the Pedra Branca Granite represents a low-level intrusion emplaced at the beginning of structuration and deposition of the Arai basin. It may be correlated with granitic intrusions related to a rift stage above mantle hot spots, like the Nigerian tin younger granites. (author)

  14. Two contrasting granite types: 25 years later

    International Nuclear Information System (INIS)

    Chappell, B.W.; White, A.J.R.

    2001-01-01

    The concept of I- and S-type granites was introduced in 1974 to account for the observation that, apart from the most felsic rocks, the granites in the Lachlan Fold Belt have properties that generally fall into two distinct groups. This has been interpreted to result from derivation by partial melting of two kinds of source rocks, namely sedimentary and older igneous rocks. The original publication on these two granite types is reprinted and reviewed in the light of 25 years of continuing study into these granites. Data on oxygen isotopic compositions of the two granite types were not available in 1974. O'Neil and Chappell (1977) found differences in such composition between the I- and S-type granites of the Berridale Batholith, with the two types having δ 18 O values less than and greater than 10%o, respectively, relative to SMOW This division is supported by our additional unpublished data on granites from other parts of the Lachlan Fold Belt, but needs to be tested further. Chappell and White (1974) noted that the initial 87 Sr/ 86 Sr values for a single S-type pluton are more variable than for I-type plutons, interpreted to reflect the more heterogeneous nature of the source material. That observation has been confirmed by later observations. The heterogeneity of isotopic compositions of S-type plutons is illustrated by the Jillamatong Granodiorite of the Kosciuszko Batholith. For that single unit, the range in 87 Sr/ 86 Sr calculated at 430 Ma is from 0.71115 to 0.71541. Copyright (2001) Geological Society of Australia

  15. The Mesoarchean Tiejiashan-Gongchangling potassic granite in the Anshan-Benxi area, North China Craton: Origin by recycling of Paleo- to Eoarchean crust from U-Pb-Nd-Hf-O isotopic studies

    Science.gov (United States)

    Dong, Chunyan; Wan, Yusheng; Xie, Hangqiang; Nutman, Allen P.; Xie, Shiwen; Liu, Shoujie; Ma, Mingzhu; Liu, Dunyi

    2017-10-01

    Mesoarchean and older potassic granites are important indicators of recycling of ancient continental crust early in Earth's history. This study of integrated whole rock and zircon geochemistry and geochronology reports the age and identification of the source materials of the > 200 km2 Mesoarchean Tiejiashan-Gongchangling granite in the Anshan-Benxi area, North China Craton, the largest pre-Neoarchean granite domain in the craton. SHRIMP U-Pb zircon dating on 15 samples indicates the magmatic crystallization of the granites between 2.95 and 3.0 Ga and reveals a superimposed tectonothermal event at 2.91 Ga. The granites are characterized by high SiO2 and K2O, low CaO, FeOt, MgO and TiO2 with peraluminuous features. They show large variations in (La/Yb)n and strong negative Eu and Ba anomalies and Nb, P and Ti depletions. Whole rock Nd and magmatic zircon Hf isotopic compositions show large variations, but with most having εNd(t) and εHf(t) values ancient gneisses, together with yet to be identified Paleo- to Eoarchean materials affected by early low temperature alteration (weathered rocks or clastic sediment).

  16. 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

  17. Estimation of crystallization pressure of granite intrusions

    Science.gov (United States)

    Yang, Xue-Ming

    2017-08-01

    A numerical method is presented to estimate the crystallization pressure of granite intrusions based on two polynomial equations obtained by an analysis of the existing haplogranite ternary phase diagram and associated dataset. The results indicate that the pressure is correlated respectively with normative quartz (Qtz) content and with normative albite (Ab) plus orthoclase (Or) contents of granitic rocks as follows. where P is pressure in MPa, and R denotes correlation coefficient. It is noted that the procedure of normalizing the sum of CIPW norm (quartz, albite, orthoclase) contents to 100% is required before using Eqs. (1) and (2). The difference in pressure calculations between these two equations is ≤ 16 MPa for the range of normative quartz contents from 15 to 40 wt%. An example of how to use these equations to estimate the crystallization pressure of a granite intrusion is also provided to show the validity and convenience of this method. The uncertainty of such pressure estimation is not well known, although it must fall into the uncertainty range of the existing experimental work on pressure constraints. The simplicity of this empirical method is appreciable, although its applicability to natural granitoids needs further test. More experimental work is required to constrain the effects of components, such as CaO, FeO, MgO, F, Cl, CO2, on the granite phase equilibria. These equations, however, can be used for estimating crystallization pressures of water-saturated and quartz-oversaturated granitic systems.

  18. 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

  19. Patherns in the rare earth elements of the Serra do Carambei granite (Parana) and the others associated ignous rocks

    International Nuclear Information System (INIS)

    Pinto-Coelho, C.V.; Marini, O.J.

    1986-01-01

    The rare earth elements (REE) distribution patters in igneous rocks of the Serra do Carambei Granite area (Parana) were a very important tool to elucidate the genetic processes and the cogenetic relationships between these rocks. The porphyroid facies of the Cunhaporanga Granitoid Complex has a REE distribution pattern characterized by decreasing concentrations in direction to the heavy rare earth elements (HREE) and the smooth Eu negative anomalie, compatible with amphibole fractionation during the magma ascent and the incipient plagioclase fractionation. The REE pattern of the Serra do Carambei Granite is characterized by the strong Eu negative anomalie, by the light rare earth element (LREE) depletion and by the HREE increase. This shape of the REE patterns is frequently observed in Sn-W granites, according to French authors. However in the igneous rocks of the Serra do Carambei Granite area this is not true. ''Rhyolite'' dytes intrusives in the Serra do Carambei Granite exhibit REE pattern similar to the wall rock, indicating then the same genetic processes. The Castro Group rhyolites have REE patterns with decreasing concentrations in direction to the HREE and smooth Eu negative anomalie. The REE distribution patterns is against the consanguinity between the ''rhyolites'' intruded in the Serra do Carambei Granite and the rhyolites of the Castro Group and also between these rhyolites and the above mentioned Granite. (author) [pt

  20. 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

  1. Mesozoic Granitic Magmatism in Macao, Southeast China

    Science.gov (United States)

    Quelhas, P. M.; Mata, J.; Lou, U. T.; Ribeiro, M. L.; Dias, Á. A.

    2016-12-01

    Macao ( 30 Km2) is a territory characterized by small granitic intrusions, located along the coastal region of Southeast China (Cathaysia Block). Granitoids occur as different facies, including microgranite dykes, with distinct textural, mineralogical and geochemical features, for which a middle-upper Jurassic age ( 164 Ma) has been proposed. New data suggest that these granitoids are mostly high-K calc-alkaline metaluminous (A/CNK = 0.8 - 1.1) biotite granites, consistent with total absence of primary muscovite. They show variable amounts of SiO2 (67-77%), reflecting different degrees of magmatic evolution. There is also variability in terms of trace elements, particularly Rare Earth Elements (REEs), evidenced by decreasing (La/Sm)N, (Gd/Lu)N, (Ce/Yb)N and (Eu/Eu*)N towards the more evolved samples, which can be partly attributed to fractional crystallization processes. Most of the granitoids are characterized by (La/Yb)N = 3 - 10.8, showing negative Ba, Nb, Sr, Zr, P, Ti and Eu anomalies. On the other hand, microgranite dykes, along with a few more evolved granites, show an opposite tendency, being usually enriched in HREEs relatively to LREEs with (La/Yb)N = 0.4 - 1.1. Our data suggests intermediate genetic affinities between I-type and A-type granites. Although these granitoids are mostly metaluminous (characteristic of I-types), Ga/Al ratios, usually used to identify A-types, are close to the accepted boundary between A-type and other granite types. The affinities with A-type granites are more marked for the more evolved facies, which depict higher values of FeOt/MgO (14 - 60) and K2O/MgO (60 - 250). Their trace element characteristics are also transitional between WPG (Within-plate granites) and Syn-COLG (Collision Granites). We interpret those transitional characteristics (A/I and WPG/Syn-COLG) of Macao granitoids as reflecting an origin by melting of infracrustal sources over a period of high heat transfer from mantle to crust during an extensional tectonic

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

    Czech Academy of Sciences Publication Activity Database

    René, Miloš; Finger, F.

    2016-01-01

    Roč. 110, č. 4 (2016), 503-514 ISSN 0930-0708 R&D Projects: GA MŠk ME 555 Institutional support: RVO:67985891 Keywords : leucogranite * turmaline * petrology * geochemistry * Bohemian Massif Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.236, year: 2016

  3. Research of environmentally-friendly utilization methods of the crushed stone waste on granite quarries

    Directory of Open Access Journals (Sweden)

    Levytskyi V.G.

    2017-12-01

    Full Text Available The analysis of activity of stone-mining enterprises shows the low competitiveness of crushed stone products Upgrading the quality of crushed stone and production of the European standard fractions requires to use of new technologies and equipment. The main waste of crushed stone pits is сrushed granite waste, which high percent of an exit is caused by outdated equipment and incorrectly selected technological parameters of the crushing process. Crushed-granite waste is stored in dumps which occupy large areas and negatively effect on production area ecology. In November 2017, the Government of Ukraine accepted the National Waste Management Strategy until 2030, the main aim of it is develop a strategy of the mineral raw materials balanced use and international standards introduction at the national level. Therefore, the problem of complex utilization and recycling of waste from stone-mining enterprises with receiving a qualitative secondary product is relevant. The publication presents the сrushed granite waste volumes by crushed stone pit, its properties and main directions of utilization. The ecological influence of waste dumps, in particular granite dust, on the environment and human, the strategy of using non-waste technologies and ecological features of сrushed granite waste secondary processing are considered

  4. Partial melting of UHP calc-gneiss from the Dabie Mountains

    Science.gov (United States)

    Liu, Penglei; Wu, Yao; Liu, Qiang; Zhang, Junfeng; Zhang, Li; Jin, Zhenmin

    2014-04-01

    Exhumation melting has been proposed for the ultra-high pressure (UHP) metamorphic rocks in the Dabie Mountains based on melting experiments. We document here the first petrological and mineralogical evidence demonstrating that the UHP calc-gneisses from the Ganjialing area in the Dabie Mountains experienced partial melting during early exhumation. The assemblage of garnet, phengite (Si = 3.65 pfu), coesite, rutile and carbonate preserved in the calc-gneisses indicates a peak metamorphic condition of 692-757 °C and 4.0-4.8 GPa. Partial melting is indicated by several lines of evidence: the melting textures of phengite, the feldspar-dominated films, bands, branches, blebs and veins, the euhedral K-feldspars, the intergrowth film of plagioclase and K-feldspar, the plagioclase + biotite intergrowth after garnet and the epidote poikiloblasts. Polyphase inclusions in garnet are characterized with wedge-like offshoots and serrate outlines whereas those in epidote display negative crystal shapes, which can be best interpreted by entrapment of former melts. We propose a wet melting reaction of Phn + Q ± Na-Cpx + H2O = Bt + Pl + Grt + felsic melts, which likely took place at ca.650-800 °C and ca.1.0-2.0 GPa, to interpret the melting event in the calc-gneisses. Chemical exchanges between garnet and melts produced new garnet domains with higher almandine, spessartine, MREE, HREE and Y but lower grossular, pyrope, P, Sc, Ti, V and Zr contents. Zr-in-rutile thermometer reveals a low temperature of 620-643 °C at 5 GPa, indicating a later reset for Zr in rutile. Healed fractures are suggested to be responsible for the formation of some polyphase inclusions in garnet.

  5. Geochemistry and petrogenesis of Proterozoic granitic rocks from ...

    Indian Academy of Sciences (India)

    granites, 5 pink granites and 7 porphyritic gran- ites) with least alteration and deformation were analysed for major oxides, trace elements and rare earth elements (table 1). The average chemical index of alteration (CIA) value of all samples is. 53, which lies within the accepted 45–55 range for unweathered granites (Nesbitt ...

  6. Tasmanian tin and tungsten granites - their radiometric characteristics

    International Nuclear Information System (INIS)

    Yeates, A.N.

    1982-01-01

    A radiometric survey of Tasmanian granites has shown, with one exception, that tin and tungsten-bearing granites have high radioactivity, largely owing to increased uranium. Many have a high uranium/thorium ratio as well. Radiometric measurements can also delineate different granite types within composite bodies

  7. Metamorphic history and age of aluminous gneisses of the Belomorian belt of the Baltic shield

    International Nuclear Information System (INIS)

    Bibikova, E.V.; Borisova, E.Yu.; Makarov, V.A.; Drugova, G.M.

    1997-01-01

    Metamorphic conditions and age are determined for the early metamorphic stage of aluminous gneisses in the Chupa nappe in the Belomorian Mobile Belt. The granulite-facies metamorphic conditions during Late Archean time are determined based on the composition of garnet and biotie from the metapelites. The early metamorphic stage was dated at 2860 ± 30 Ma based on the U-Pb systematics of granulitic zircon from the metapelites. The U-Pb isotopic system of the zircon was strongly affected by Svecogennian metamorphism (at 1750 Ma). The geodynamic evolution of the Belomorian Mobile Belt is discussed in light of the data of this work

  8. Petrogenesis of low-δ18O quartz porphyry dykes, Koegel Fontein complex, South Africa

    Science.gov (United States)

    Harris, Chris; Mulder, Kwenidyn; Sarkar, Saheli; Whitehead, Benjamin; Roopnarain, Sherissa

    2018-04-01

    This paper investigates the origin of low-δ18O quartz porphyry dykes associated with the 144-133 Ma Koegel Fontein Igneous Complex, which was intruded during the initial phase of breakup of Africa and South America. The 25-km diameter Rietpoort Granite is the largest and youngest phase of activity, and is roofed by a 10-km diameter pendant of gneiss. Quartz porphyry (QP) dykes, up to 15 m in width, strike NW-SE across the complex. The QP dykes that intruded outside the granite have similar quartz phenocryst δ18O values (average 8.0‰, ± 0.7, n = 33) to the granite (average 8.3 ± 1.0, n = 7). The QP dykes that intruded the roof pendant have quartz phenocrysts with more variable δ18O values (average 1.6‰, ± 2.1, n = 55). In some cases quartz phenocrysts have δ18O values as low as - 2.5‰. The variation in δ18O value within the quartz crystal population of individual dykes is small relative to the overall range, and core and rim material from individual quartz phenocrysts in three samples are identical within error. There is no evidence that quartz phenocryst δ18O values have been affected by fluid-rock interaction. Based on a Δquartz-magma value of 0.6‰, magma δ18O values must have been as low as - 3.1‰. Samples collected along the length of the two main QP dykes that traverse the roof pendant have quartz phenocryst δ18O values that range from + 1.1 to + 4.6‰, and - 2.3 to + 5.6‰, respectively. These δ18O values correlate negatively ( r = - 0.96) with initial 87Sr/86Sr, which can be explained by the event that lowered δ18O values of the source being older than the dykes. We suggest that the QP dykes were fed by magma produced by partial melting of gneiss, which had been variably altered at high temperature by 18O-depleted meteoric water during global glaciation at 550 Ma. The early melts had variable δ18O value but as melt pockets interconnected during melting, the δ18O values approached that of average gneiss. Variable quartz phenocryst

  9. Distinguishing major lithologic types in rocks of precambrian age in central Wyoming using multilevel sensing, with a chapter on possible economic significance of iron formation discovered by use of aircraft images in the Granite Mountains of Wyoming

    Science.gov (United States)

    Houston, R. S. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Information obtained by remote sensing from three altitude levels: ERTS-1 (565 miles), U-2 (60,000 feet), and C-130 aircraft (15,000 feet) illustrates the possible application of multilevel sensing in mineral exploration. Distinction can be made between rocks of greenstone belts and rocks of granite-granite gneiss areas by using ERTS-1 imagery in portions of the Precambrian of central Wyoming. Study of low altitude color and color infrared photographs of the mafic terrain revealed the presence of metasedimentary rocks with distinct layers that were interpreted as amphibolite by photogeologic techniques. Some of the amphibolite layers were found to be iron formation when examined in the field. To our knowledge this occurrence of iron formation has not been previously reported in the literature.

  10. 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.

  11. Petrochemical characteristics of Serra do Meio alkaline granite (Campo Alegre de Lourdes - Bahia State)

    International Nuclear Information System (INIS)

    Matos Maia Leite, C. de; Froes, R.J.B.

    1989-01-01

    The Serra do Meio granite outcrops near the town of Campo Alegre de Lourdes, north-northeast of Bahia State. The granite is intrusive into micachists, which are correlatives of the Salgueiro-Cachoeirinha Group (Early Proterozoic), during early to the syn-tectonic shear phase. The geological setting also comprises a phosphatic rock-bearing carbonatitic complex and gabbroid complexes with one of the main world resources of Fe-Ti-V. The granite mineralogical composition grades from Aegerine-augite alkali-feldspar granite/syenites to Leuco alcali-feldspar granite. The geochemical analysis shows SiO 2 -enrichment (67 to 76%), in alkalis (Na 2 +K 2 O, 7,5 to 12,5%), Nb (up to 680ppm), Zr (up to 2,390ppm), Y (up to 250ppm) e REE (up to 796ppm). The geochemical behaviour is peculiar to alkaline series, denoting a silica-oversaturated, potassium-rich, magma. The chondrite-normalized REE patterns display a first group with smooth slopes from the La to Lu, and a second one with negative slopes. Negative Eu anomalies are displayed in all the patterns. The first group is HREE-enriched, with low fractionation ratios. Samples with milonytic fabrics and higher fractionation ratios are related to the second group, suggesting the interaction of metassomatic fluids and the alkaline magma. Discriminant diagrams for Nb, Y and Rb, coupled with geophysical data, point to an intrusive granite in an extensional within a plate tectonic setting of attenuated continental crust. (author) [pt

  12. Physics of the granite sphere fountain

    NARCIS (Netherlands)

    Snoeijer, Jacobus Hendrikus; van der Weele, J.P.

    2014-01-01

    A striking example of levitation is encountered in the “kugel fountain” where a granite sphere, sometimes weighing over a ton, is kept aloft by a thin film of flowing water. In this paper, we explain the working principle behind this levitation. We show that the fountain can be viewed as a giant

  13. Geochemical characteristics of Proterozoic granite magmatism from ...

    Indian Academy of Sciences (India)

    T Yellappa

    2018-03-06

    Mar 6, 2018 ... rocks occur near the transition zone around Krish- nagiri in the northern part of Tamil Nadu ... Archean and Neoproterozoic high-grade metamor- phic and magmatic rocks. The important ... Western Dharwar Craton, EDC: Eastern Dharwar Craton, Tz: Transition Zone. Location of the granite plutons are also.

  14. Characterization of weathering profile in granites and ...

    Indian Academy of Sciences (India)

    Characterization of weathering profile in granites and volcanosedimentary rocks in West Africa under humid tropical climate conditions. Case of the Dimbokro Catchment (Ivory Coast). M Koita1,2,∗, H Jourde1, K J P Koffi3, K S Da Silveira1 and A Biaou1. 1Water and Climate Research Center, International Institute for Water.

  15. Granite-hosted molybdenite mineralization from Archean ...

    Indian Academy of Sciences (India)

    discovered uranium content (Pathak et al. 2009) in the impact melt breccias of granitic compo- sition from Dhala structure (Pati et al. 2008a). The incidences of ...... affinity of the metal to felsic melts is expected. Isuk and Carman (1981) measured solubility of Mo in silicate melt and suggested that the metal is pos- sibly carried ...

  16. Landslides and the weathering of granitic rocks

    Science.gov (United States)

    Philip B. Durgin

    1977-01-01

    Abstract - Granitic batholiths around the Pacific Ocean basin provide examples of landslide types that characterize progressive stages of weathering. The stages include (1) fresh rock, (2) corestones, (3) decomposed granitoid, and (4) saprolite. Fresh granitoid is subject to rockfalls, rockslides, and block glides. They are all controlled by factors related to...

  17. Transpressional granite-emplacement model: Structural and ...

    Indian Academy of Sciences (India)

    the complete emplacement and deformation of the pluton during the Pan-African D2 and D3 events which occurred in the Pan-African belt in Cameroon and (2) reorganize Pan-African ages from Nguiessi. Tchakam et al. ... emplacement and deformation age of the granitic pluton in a dextral ENE–WSW shear movement. 1.

  18. Magma mixing in granite petrogenesis: Insights from biotite inclusions in quartz and feldspar of Mesozoic granites from South China

    Science.gov (United States)

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

    2016-06-01

    Magma mixing is a common process in granite petrogenesis. The major element composition of biotites in granites is primarily controlled by the composition of magmas from which they crystallized. Biotite grains enclosed in quartz and feldspars of granites are naturally protected by their host minerals, so that their compositions are likely original and can potentially be used to track the magma mixing. This is illustrated by a combined study of matrix and inclusion biotites from Mesozoic granites in the Nanling Range, South China. Three granite samples have been used in this study: one two-mica granite and two biotite granites. The biotites of different occurrences in the two-mica granite have no compositional distinctions. Biotites in the two-mica granite have higher Al2O3 and lower MgO than those in the biotite granites. The former is consistent with biotites from typical S-type granites of metasedimentary origin. In contrast, biotites from the biotite granites can be categorized into different groups based on their paragenetic minerals and geochemical compositions. They have relatively low aluminous saturation indices but higher Mg numbers, falling in the transitional field between typical S- and I-type granites. In addition, there are two contrasting zircon populations with nearly identical U-Pb ages in the biotite granites. One shows clearly oscillatory zonings in CL images, whereas the other is totally dark and often overgrew on the former one. The zircons with oscillatory zonings have higher δ18O values than the dark ones, indicating their growth from two compositionally different magmas, respectively, with different sources. An integrated interpretation of all these data indicates that mixing of two different magmas was responsible for the petrogenesis of biotite granites. Therefore, the study of biotite inclusions provides insights into the magma mixing in granite petrogenesis.

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

    OpenAIRE

    Ana M.R. Neiva

    2002-01-01

    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 cr...

  20. Mise en place, pétrographie, géochimie et minéralogie des granites associés aux skarns minéralisés en tungstène de Fumade (Tarn, France)

    OpenAIRE

    Tessier, Bruno

    1989-01-01

    348 pages; The scheelite skarn deposit of Fumade is hosted in carbonate bearing black schists units belonging to the lower Cambrian, on the northern flank of the Montagne Noire (Tarn, France), near the Sidobre granitic batholith. This deposit has been extensively drilled by the SNEA(P) and shows a narrow association between the tungsten mineralization and a differentiated granitic complex. These granites appear as centimeter to decameter wide veins whose location is largely controled by the p...

  1. Alteration, fracture infills and weathering of the Strath Halladale granite

    International Nuclear Information System (INIS)

    Storey, B.C.; Lintern, B.C.

    1981-12-01

    The Strath Halladale Granite has undergone a complex history of faulting, alteration and weathering. The alteration varies from thin ramifying veins and irregular diffuse areas within fresh rock to alteration zones in which all the major phases have been partially or completely replaced. Initial reactions were associated with magmatic fluids which formed pegmatites and aplites within extensional fractures. Introduction of meteoric waters resulted in the formation of a convecting hydrothermal system driven by a magmatic heat energy source. The migrating fluids formed secondary dioctahedral micas and chlorite within the granite, and calcite, siderite, iron sulphide, iron oxides, smectites and quartz within the brittle fractures. Many fractures are shear zones which are infilled by granulated quartz, feldspar and mica. The presence of montmorillonite, the lowest temperature mineral phase, and a preliminary study of stable isotopes indicate temperatures in excess of 100 deg C for migrating alkali-rich fluids. In an assessment of the feasibility of the disposal of high level radioactive waste the ubiquitous presence of montmorillonite, which has a high sorption capacity, is important. (author)

  2. Hydrogeologic characterization of a fractured granitic rock aquifer, Raymond, California

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Andrew J.B. [Univ. of California, Berkeley, CA (United States)

    1993-10-01

    The hydrogeologic properties of a shallow, fractured granitic rock aquifer in the foothills of the Sierra Nevada, California were investigated via the analysis of borehole geophysical logs and pumping tests. The drawdowns produced during these tests are not indicative of any simple conceptual aquifer model, and borehole logs show that the granite is intensely fractured. These observations are suggestive of a complex fracture-flow geometry which is extremely difficult to decipher. However, through the measurement of orientations of individual subsurface fractures from acoustic televiewer logs, and correlation between particular fractures and electrical resistivity and thermal-pulse flowmeter logs, it was found that the aquifer is, in general, comprised of two subhorizontal and nearly parallel zones of unloading fractures. Downhole flowmeter measurements taken in several wells provide further evidence for the inferred dual-layer structure of the aquifer, as well as yield quantitative measures of the contribution of flow from each zone. Analysis of drawdowns in pumped wells reveals that there are zones of relatively high transmissivity immediately around them. It was found that these properties, as well as a nearby zone of lower transmissivity, can account for their observed drawdowns. A numerical model was constructed to test whether these major heterogeneities could also account for the drawdowns in observation wells. This stepwise analysis of both the geophysical and hydrological data resulted in the formulation of a conceptual model of the aquifer which is consistent with observations, and which can account for its behavior when subjected to pumping.

  3. Geochronology and geochemistry of the granites from the Zhuxi W-Cu ore deposit in South China: Implication for petrogenesis, geodynamical setting and mineralization

    Science.gov (United States)

    Pan, Xiaofei; Hou, Zengqian; Zhao, Miao; Chen, Guohua; Rao, Jianfeng; Li, Yan; Wei, Jin; Ouyang, Yongpeng

    2018-04-01

    The giant Zhuxi tungsten deposit is located in the Taqian-Fuchun Ore Belt in northeastern Jiangxi province, and genetically associated with the Zhuxi granitic stocks and dykes. Three mineralization-related granites including granite porphyry dykes (GP), biotite granitic stocks (BG), and white granitic dykes (WG), were identified in the Zhuxi deposit. SHRIMP zircon U-Pb analysis for the three granitic rocks present ages ranging from 153.5 ± 1.0 Ma to 150.4 ± 1.0 Ma. The BG mainly contains quartz, microcline, albite, biotite and muscovite with minor accessory minerals including zircon, apatite, monazite, Ti/Fe oxides, and dolerite. However, the WG is mainly composed of quartz, microcline and albite with minor muscovite and accessory minerals. The GP is a medium-grained porphyritic granite and its phenocrysts include quartz, alkali feldspar, muscovite and plagioclase. All the Zhuxi granites have high SiO2 content (71.97 wt%-81.19 wt%) and total alkali (3.25 wt%-9.42 wt%), and their valid aluminum saturation index (ASI) values show a wide range of 1.03 to 2.49. High Rb/Sr ratios, low Sr content (values fall into the ranges of -6.98 to -11.97, and -3.1 to -11.5, and the Nd (TDM2) and Hf two-stage model ages (TDMc) are 1.51-1.92 Ga and 1.42-2.01 Ga, respectively. Geochemical and isotopic data suggest that these highly fractionated I-S transform-type granites were originated from magmas which showed affinity with the Proterozoic continent and the Shuangqiaoshan Group and little mantle contribution was involved during the generation of Zhuxi granitic rocks. Extreme fractional crystallization resulted in further enrichment of tungsten in the evolved granitic magma. New data, presented together with previously published data, suggest that the Zhuxi granitic complex was likely to be formed during lithospheric compression setting during the late Jurassic to early Cretaceous. The biotite granite stock predominately contributed to the production of skarn alteration and

  4. The nature of the basement in the archaean Dharwar carton of southern India and the age of the peninsular gneiss

    International Nuclear Information System (INIS)

    Naha, K.; Vrevsky, A.B.; Bogomolov, Ye.S.

    1993-01-01

    The archaean peninsular gneiss of southern India is considered by a number of workers to be the basement upon which the Dharwar supra crustal rocks were deposited. However, the peninsular gneiss in its present state is a composite gneiss formed by syn kinematic migmatization during successive episodes of folding (DhF 1 , DhF 1a and DhF 2 ) that affected the Dharwar supra crustal rocks. An even earlier phase of migmatization and deformation (DhF * ) is evident from relict fabrics in small enclaves to represent the original basement for the Dharwar supra crustal rocks. Tonalitic pebbles in conglomerates of the Dharwar supergroup confirm the inference that the supra crustal rocks were deposited on a gneissic basement. Whole rock Rb-Sr ages of gneisses showing only the DhF 1 structure fall in the range of 3100-3200 Ma. Where the later deformation (DhF 2 ) has been associated with considerable recrystallization, the Rb-Sr ages are between 2500 Ma and 2700 Ma. Significantly, a new Rb-Sr analysis of tonalitic gneiss pebbles in the Kaldurga conglomerate of the Dharwar sequence is consistent with an age of ∼ 2500 Ma and not that of 3300 Ma reported earlier by Venkatasubramanian and Narayanaswamy (1974). Pb-Pb ages based on direct evaporation of detrital zircon grains from the metasedimentary rocks of the Dharwar sequence fall into two groups, 3300-3100 Ma, and 2800-3000 Ma. Stratigraphic, structural, textural and geochronologic data, therefore, indicate that the peninsular gneiss of the Dharwar craton evolved over a protracted period of time ranging from >3300 Ma to 2500 ma. (author). 26 refs., 13 figs., 8 tabs

  5. Hercynian late-post-tectonic granitic rocks from the Fornos de Algodres area (Northern Central Portugal)

    Science.gov (United States)

    Azevedo, M. R.; Nolan, J.

    1998-10-01

    The Fornos de Algodres Complex (FAC) comprises several intrusions of late-post-tectonic Hercynian granitic rocks ranging in composition from hornblende granodiorites and quartz monzodiorites, through coarse porphyritic biotite granites and two-mica granites (coarse-, medium- and fine-grained), to muscovite-rich leucogranites. Field and regional constraints show that the emplacement of this large, composite, batholithic complex post-dates the main Variscan regional deformation phases (D 1+D 2+D 3) and associated metamorphic events. Field, petrographic and geochemical data suggest a strong genetic relationship between most of the members of the FAC. However, their Rb-Sr and Sm-Nd isotopic signatures appear to rule out any genetic process involving a single homogeneous source and/or closed-system fractional crystallization of the same parental magma. A model involving hybridization of mantle-derived basaltic liquids with crustal anatectic melts followed by further contamination and fractional crystallization is proposed to explain the isotopic and geochemical variation trends defined by the FAC granitic rocks.

  6. ``Granite tectonics'' revisited: insights from comparison of K-feldspar shape-fabric, anisotropy of magnetic susceptibility (AMS), and brittle fractures in the Jizera granite, Bohemian Massif

    Science.gov (United States)

    Žák, Jiří; Verner, Kryštof; Klomínský, Josef; Chlupáčová, Marta

    2009-07-01

    In the Jizera granite of the Krkonoše-Jizera Plutonic Complex, northern Bohemian Massif, contrasting patterns of magmatic K-feldspar fabrics and brittle fractures characterize different structural levels of the pluton. The uppermost exposed level at ˜800-1,100 m above sea level is dominated by flat foliation that overprints two steep foliations. In contrast, K-feldspar shape-fabric in an underground tunnel (˜660 m above sea level) shows complex variations in orientation and intensity. Magnetic fabric carried by coaxial contributions of biotite, magnetite, and maghemite is homogeneous along the examined section of the tunnel, and is decoupled from the K-feldspar fabric. The Jizera granite is crosscut by two regional sets of subvertical fractures (˜NE-SW and ˜NW-SE) and by near-surface exfoliation joints. The multiple fabrics are inferred to reflect a complex magmatic strain history at different structural levels of the pluton, bearing little or no relationship to the fracture network. In contrast to the original concept of Hans Cloos (“granite tectonics”), we conclude that no simple genetic relationship exists between fabrics and fractures in plutons. An alternative classification of fractures in plutons thus should avoid relationships to magmatic fabrics and should instead consist of cooling, syntectonic, uplift, and post-uplift fractures.

  7. Paleo-redox boundaries in fractured granite

    DEFF Research Database (Denmark)

    Dideriksen, K.; Christiansen, B. C.; Frandsen, Cathrine

    2010-01-01

    At the Earth's surface, Fe(II) often oxidises and forms insoluble Fe(III)-(oxyhydr)oxides, whose particle size and structure depend on solution composition and temperature during formation and afterwards. Bacterial processes and exposure to reducing environments reduces them again, releasing....... In samples taken from similar to 120 m drill cores in granite from SE Sweden, X-ray amorphous, superparamagnetic, nanometre-sized Fe-oxides are confined to fractures of the upper,-,50 m, whereas well-crystalline Fe-oxides, with particle sizes typical for soils, occur down to similar to 110 m. We also...... that are not significantly altered, indicating formation during periods of oxidation. Our results show that oxygenated water may reach depths of similar to 110 m in fractured granite. The absence of natural, low-temperature Fe-oxides from deeper drill cores suggests that oxygenated waters do not readily penetrate beyond...

  8. Retention of Anionic Species on Granite: Influence of Granite Composition - 12129

    Energy Technology Data Exchange (ETDEWEB)

    Videnska, Katerina [Institute of Chemical Technology, Prague (Czech Republic); Havlova, Vaclava [Nuclear Research Institute Rez, Rez, 25068 (Czech Republic)

    2012-07-01

    Technetium (Tc-99, T{sub 1/2} = 2.1.10{sup 5} yrs) and selenium (Se-79, T{sub 1/2} = 6.5.10{sup 4} yrs) belong among fission products, being produced by fission of nuclear fuel. Both elements can significantly contribute to risk due to their complicated chemistry, long life times, high mobility and prevailing anionic character. Therefore, knowledge of migration behaviour under different conditions can significantly improve input into performance and safety assessment models. Granite is considered as a potential host rock for deep geological disposal of radioactive waste in many countries. Granitic rocks consist usually of quartz, feldspar, plagioclase (main components), mica, chlorite, kaolinite (minor components). The main feature of the rock is advection governed transport in fractures, complemented with diffusion process from fracture towards undisturbed rock matrix. The presented work is focused on interaction of anionic species (TcO{sub 4}{sup -}, SeO{sub 4}{sup 2-}, SeO{sub 3}{sup 2-}) with granitic rock. Furthermore, the importance of mineral composition on sorption of anionic species was also studied. The batch sorption experiments were conducted on the crushed granite from Bohemian Massive. Five fractions with defined grain size were used for static batch method. Mineral composition of each granitic fraction was evaluated using X-ray diffraction. The results showed differences in composition of granitic fractions, even though originating from one homogenized material. Sorption experiments showed influence of granite composition on adsorption of both TcO4{sup -} and SeO3{sup 2-} on granitic rock. Generally, Se(IV) showed higher retention than Tc(VII). Se(VI) was not almost sorbed at all. Fe containing minerals are pronounced as a selective Se and Tc sorbent, being reduced on their surface. As micas in granite are usually enriched in Fe, increased sorption of anionic species onto mica enriched fractions can be explained by this reason. On the other hand

  9. Magmatic-hydrothermal evolution of the Kymi topaz granite stock, SE Finland: Mineral chemistry evidence for episodic fluid exsolution

    Science.gov (United States)

    Berni, Gabriel V.; Wagner, Thomas; Fusswinkel, Tobias; Wenzel, Thomas

    2017-11-01

    from the equigranular granite and the stockscheider pegmatite, compared with those from the earlier porphyritic granites, show pronounced tetrad effects and correlated Y anomalies. This suggests that the F enrichment in the equigranular granite and the stockscheider pegmatite, in conjunction with major fluid exsolution and REEY complexing as fluoride species at this stage, have been key to development of the tetrad effect and Y anomalies. The fluorite from hydrothermal greisen alteration and quartz veins shows different chondrite normalized REEY patterns, indicating contributions from other sources such as meteoric fluids and/or interaction with the surrounding host rocks. The major and trace element data from the biotites of the Kymi stock are distinct from those of the host rapakivi granites, suggesting that the parental melts have not been entirely derived from fractionated rapakivi granite melts.

  10. Natural radioactivity of granites used as building materials

    International Nuclear Information System (INIS)

    Pavlidou, S.; Koroneos, A.; Papastefanou, C.; Christofides, G.; Stoulos, S.; Vavelides, M.

    2006-01-01

    Sixteen kinds of different granites, used as building materials, imported to Greece mainly from Spain and Brazil, were sampled and their natural radioactivity was measured by gamma-ray spectrometry. The activity concentrations of 238 U, 226 Ra, 232 Th and 4 K of granites are presented and compared to those of other building materials as well as other granite types used all over the world. In order to assess the radiological impact from the granites investigated, the absorbed and the effective doses were determined. Although the annual effective dose is higher than the limit of 1 mSv y -1 for some studied granites, they could be used safely as building materials, considering that their contribution in most of the house constructions is very low. An attempt to correlate the relatively high level of natural radioactivity, shown by some of the granites, with their constituent radioactive minerals and their chemical composition, was also made

  11. On the interaction of granite with Tc(IV) and Tc(VII) in aqueous solution

    International Nuclear Information System (INIS)

    Eriksen, T.E.; Cui, Daquing

    1991-10-01

    The behaviour of technetium in granite-groundwater systems under reducing conditions was investigated. The anion TcO 4 - was reduced to Tc(IV) and simultaneously precipitated as TcO 2 xnH 2 O on the granite surfaces. The electron sources are assumed to be iron oxides and/or iron containing minerals in the granite. The technetium concentration in ground water under repository conditions may be predicted assuming TcO 2 xnH 2 O as the solid phase and TcO(OH) 2 0 and TcO 4 - as the predominant aqueous complexes using a formation constant for TcO(OH) 2 0 of log K = -8.16 and a standard reduction potential E 0 for the reaction TcO 4 - + 3e - + 4H + = TcO 2 xnH 2 O of 0.738 V. The surface related distribution ratio K a for TcO(OH) 2 0 between Stripa granite and ground water is approximately 1 cm based on geometrical surface area. (au)

  12. Index of granitic rock masses in the state of Nevada

    Science.gov (United States)

    Maldonado, Florian; Spengler, Richard W.; Hanna, W.F.; Dixon, G.L.

    1988-01-01

    A compilation of 205 areas of exposed granitic rock in Nevada was undertaken for the U.S. Department of Energy. The purpose was to obtain data for evaluating granitic rock masses as potential underground nuclear waste repositories. Information, compiled by county for areas of granitic rock exposure, includes general location, coordinates, land classification, areal extent, accessibility, composition, age, rocks intruded, aeromagnetic expression, mining activity, and selected references.

  13. Rare-earth elements in granites: concentration and distribution pattern

    International Nuclear Information System (INIS)

    Galindo, A.C.

    1983-01-01

    The geochemistry of rare earth elements in granites is studied. The rare earth element (REE) distribution pattern in granites is characterized by a smooth curve with decreasing concentrations from La to Lu, and frequently a marked Eu negative anomaly. It seems to exist relationship between granite genesis and its REE pattern, in that bodies of primary (magmatic differentiation) origin always show this negative Eu anomaly, while those bodies generated by crustal anatexis do not show this anomaly. (E.G.) [pt

  14. 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.

  15. A Bibliography on the Chemical Weathering of Granitic Rocks

    Science.gov (United States)

    1988-09-01

    Figuerda, H. 1970. (Observations of weathering a,d morphology of granitic blocks, El Roble Mountain). Revista Geografica de Valparaiso, vol. 4, pp. 64-68...weathering of granite. Geochimica et Cosmochimica Acta , vol. 48, pp. 1249-1255. Moeyersons, J. 1977. Joint patterns and their influence on the form of...transported quartz grains from the Harney Peak granite, Black Hills, South Dakota. Geochimica et Cosmochimica Acta , vol. 43, pp. 137-146. Pye, K. 1986

  16. 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.

  17. Characterization of mechanical damage in granite

    Directory of Open Access Journals (Sweden)

    Minh-Phong Luong

    2014-01-01

    Full Text Available This paper aims to illustrate the use of infrared thermography as a non-destructive and non-contact technique to observe the phenomenological manifestation of damage in granite under unconfined compression. It allows records and observations in real time of heat patterns produced by the dissipation of energy generated by plasticity. The experimental results show that this technique, which couples mechanical and thermal energy, can be used for illustrating the onset of damage mechanism by stress concentration in weakness zones.

  18. Petrology and geochronology of Stock Santos Ferreira granitic and their correlation with the Batholith of Cacapava do Sul, Rio Grande do Sul State

    International Nuclear Information System (INIS)

    Sartori, P.L.P.; Kawashita, K.

    1989-01-01

    The small Stock Santos Ferreira (15 km 2 ), situated in the Sul-rio-grandense Shields, comprises syeno- and monzogranites correlated with the granite rocks of the Batholith of Cacapava do Sul. Rb-Sr total rock isochron determinations indicates an age around 550 m.y. and the iso chronic pattern of distribution of the analytic points is similar to the Cacapava do Sul granitic complex. (author)

  19. Warren Hunt to test granite well

    International Nuclear Information System (INIS)

    Harvie, W.

    1996-01-01

    Various theories which purport to explain the existence of the Alberta oil sands, were discussed briefly. One theory, held among others by Warren Hunt, speculates that oil is formed deep in the Precambrian basement and not in the higher sedimentary rock. According to this theory, methane in the crust is the abiogenic product that results from hydrogen reacting with silicon carbide in the lower mantle. As it rises through the fractures, it encounters the microbiota, and hydrogen is stripped away making larger molecules until only bitumen remains. Hunt and other adherents of this theory believe that hydrocarbon reservoirs are replenished as oil is produced, hence there is no end to the world's oil supply. This theory is about to be tested by retesting a granite well near Fort McMurray, which was suspended in September 1994, when funding dried up. Kaleeda Enterprises, owners of the well, believe that the well bottom is currently in a granite pool, and oil will be found by deepening the well to 2,150 metres from the current 1,650 metres. While this is not universally accepted, if true, the abiogenic theory would go a long way towards explaining the origin of the oil sands

  20. The 'Granite' collegial mission of dialogue. Report

    International Nuclear Information System (INIS)

    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.)

  1. 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

  2. Geochemical study of volcanic and associated granitic rocks from ...

    Indian Academy of Sciences (India)

    and pyroclastic rocks are closely associated with granitic rock. In the south of Peninsular Malaysia, the volcanic rocks, especially the lava type, usually occur in close association with the I-type granitic rock. The study area is part of the Endau Rompin. National Park, Johor State, located in the south- ern part of Peninsular ...

  3. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Soil Radon In The Nigerian Younger Granites | Dewu | Nigerian ...

    African Journals Online (AJOL)

    ... not had enough time to attain equilibrium with its daughters. In general, the results suggest that with proper control, soil radon measurements over the Younger Granite can be used for uranium exploration in the region. Keywords: Radon, younger granite, soil uranium, half-lifeand thorium. Nigerian Journal of Physics Vol.

  5. Tectonic imprints within a granite exposed near Srinagar, Rajasthan ...

    Indian Academy of Sciences (India)

    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 ...

  6. Early Neoarchaean A-type granitic magmatism by crustal reworking ...

    Indian Academy of Sciences (India)

    29

    dyke swarm). It is suggested that the ~2.8 Ga A-type granites in the Singbhum craton mark a significant crustal reworking event attendant to mantle-derived mafic magmatism in an extensional tectonic setting. Key words: Granite; A-type; Geochemistry; Archaean; Crustal reworking; Singhbhum craton. Abstract. Click here to ...

  7. Early Neoarchaean A-type granitic magmatism by crustal reworking ...

    Indian Academy of Sciences (India)

    Abhishek Topno

    2018-04-11

    Apr 11, 2018 ... crustal melting of tonalitic/granodioritic source similar to the ~3.3 Ga Singhbhum Granite. Intrusion of the Pala Lahara granites was coeval with prominent mafic magmatism in the Singhbhum craton (e.g., the Dhanjori mafic volcanic rocks and NNE–SSW trending mafic dyke swarm). It is suggested that the.

  8. Geochemical study of volcanic and associated granitic rocks from ...

    Indian Academy of Sciences (India)

    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 ...

  9. Distribution of elements among minerals of a single (muscovite-) biotite granite sample – an optimal approach and general implications

    Czech Academy of Sciences Publication Activity Database

    Janoušek, V.; Navrátil, Tomáš; Trubač, J.; Strnad, J.; Laufek, F.; Minařík, Luděk

    2014-01-01

    Roč. 65, č. 4 (2014), s. 257-271 ISSN 1335-0552 Institutional research plan: CEZ:AV0Z30130516 Institutional support: RVO:67985831 Keywords : modal analyses * trace-element residence * ICP-MS * Central Bohemian Plutonic Complex * Říčany granite Subject RIV: DD - Geochemistry Impact factor: 0.761, year: 2014

  10. Chemical characteristics of zircon from A-type granites and comparison to zircon of S-type granites

    Czech Academy of Sciences Publication Activity Database

    Breiter, Karel; Lamarão, C. N.; Krás Borges, R. M.; Dall'Agnol, R.

    1192/195, April (2014), s. 208-225 ISSN 0024-4937 Institutional support: RVO:67985831 Keywords : zircon * A-type granites * S-type granites * Wiborg batholith * Brazil * Krušné hory/Erzgebirge Subject RIV: DD - Geochemistry Impact factor: 4.482, year: 2014

  11. 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

  12. 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

  13. Ion microprobe zircon geochronology of the Uivak Gneisses: Implications for the evolution of early terrestrial crust in the North Atlantic Craton

    Science.gov (United States)

    Collerson, K. D.

    1983-01-01

    Ion microprobe U-Pb results for zircons from three Uivak I gneisses and one specimen of Uivak II gneiss, from the Saglek-Hebron area of Northern Labrador are reported. These results are compared with interpretations based on published conventional U-Pb zircon results and with conclusions about crustal evolution in the NAC derived from Rb-Sr, Sm-Nd and Pb-Pb isotopic studies.

  14. Radionuclide sorption on granitic drill core material

    International Nuclear Information System (INIS)

    Eriksen, T.E.; Locklund, B.

    1987-11-01

    Distribution ratios were determined for Sr-85, Cs-134 and Eu-152 on crushed granite and fissure coating/filling material from Stripa mines. Measurements were also carried out on intact fissure surfaces. The experimental data for Sr-85, Cs-134 on crushed material can be accomodated by a sorption model based on the assumption that the crushed material consists of porous spheres with outer and inner surfaces available for sorption. In the case of Eu-152 only sorption on the outer surfaces of the crushed material was observed. The absence of sorption on inner surfaces is most probably due to high depletion of the more strongly sorbed Eu-152 in the water phase and very low diffusivity of Eu-152 in the sorbed state. (orig./HP)

  15. Diffusion data in granite. Recommended values

    International Nuclear Information System (INIS)

    Ohlsson, Yvonne; Neretniks, I.

    1997-10-01

    Diffusion data for radionuclide transport in the porous matrix of rock are proposed for Swedish rock and ground waters, for performance assessment. Suggested data are based on an experimental diffusion study, where tritiated water was used as noninteracting diffusing species in stationary diffusion experiments in Aespoe fine grained granite and diorite. These data, for tritiated water, were used as reference in our study. For other species the effective diffusivities could be predicted from knowledge of the relative behaviour of these species to that of tritiated water. The behaviour is influenced by the difference in free water diffusivity and sometimes the existence of anion exclusion of surface diffusion. Apparent diffusivities are also calculated using sorption data, in addition to the effective diffusivities. Data are proposed for high saline and low saline ground water conditions

  16. Expected repository environments in granite: thermal environment

    International Nuclear Information System (INIS)

    Osnes, J.D.; Coates, G.K.; DeJong, K.B.; Loken, M.C.; Wagner, R.A.

    1984-10-01

    This report was prepared for the Reference Repository Conditions - Interface Working Group and will be used to formulate a standardized description of repository conditions for use by the Civilian Radioactive Waste Management Program. A baseline repository in granite is defined and three waste types are considered: unreprocessed spent fuel, commercial high-level waste, and defense high-level waste. Three different scales of repository environment are described - the very-near field (near the waste canister), the near field (the room and pillar), and the far field (the entire repository and surroundings). Information was compiled from the literature and, in addition, a number of calculations were performed. The major emphasis is on describing the thermal environment although the ground-water flow and chemical and radiation environments are also described. 61 figures, 24 tables

  17. Origin and age of the Eisenkappel gabbro to granite suite (Carinthia, SE Austrian Alps).

    Science.gov (United States)

    Miller, C; Thöni, M; Goessler, W; Tessadri, R

    2011-07-01

    The northern part of the Karawanken plutonic belt is a gabbro-granite complex located just north of the Periadriatic lineament near the Slovenian-Austrian border. Petrographic and geochemical studies of the Eisenkappel intrusive complex indicate that this multiphase plutonic suite developed by a combination of crystal accumulation, fractional crystallization and assimilation processes, magma mixing and mingling. The mafic rocks are alkaline and have within-plate geochemical characteristics, indicating anorogenic magmatism in an extensional setting and derivation from an enriched mantle source. The mafic melts triggered partial melting of the crust and the formation of granite. The granitic rocks are alkalic, metaluminous and have the high Fe/Fe + Mg characteristics of within-plate plutons. Temperature and pressure conditions, derived from amphibole-plagioclase and different amphibole thermobarometers, suggest that the analysed Eisenkappel gabbros crystallized at around 1000 ± 20 °C and 380-470 MPa, whereas the granitic rock crystallized at T ≤ 800 ± 20 °C and ≤ 350 MPa. Mineral-whole rock Sm-Nd analyses of two cumulate gabbros yielded 249 ± 8.4 Ma and 250 ± 26 Ma (εNd: + 3.6), garnet-whole rock Sm-Nd analyses of two silicic samples yielded well-constrained ages of 238.4 ± 1.9 Ma and 242.1 ± 2.1 Ma (εNd: - 2.6).

  18. Design of a dosimetric evaluation protocol workers granite quarries

    International Nuclear Information System (INIS)

    Guillen, J.; Tejado, J. J.; Baeza, A.

    2011-01-01

    The Autonomous Community of Extremadura is one of the major regions of Spain as far as the extraction of granite and further processing of products derived from it are concerned. One of the most industrialized areas of the sector presents a serious problem for non-radiological occupational health of workers, particularly silicosis. Since in this area of activity levels of granites can be classified as medium-high within the precipitates ranges, the question is whether in addition to this occupational disease, there is a radiological impact associated with the activity NORM extraction and manufacturing of granite.

  19. Gneisses of Brazil's cultural heritage buildings and its most frequent degradations

    Science.gov (United States)

    Gilberto Costa, Antônio

    2017-04-01

    Macroscopic descriptions of cultural heritage buildings constructed using gneisses in the cities of Rio de Janeiro, Belo Horizonte and Ouro Preto, Brazil, allowed to identify alterations and degradations, in part conditioned by the mineralogical composition and the structures present in these stone materials. It is important to emphasize that: - some changes still begin in the environments where these materials were formed, experiencing an intensification from the processes of extraction, processing and application; - modifications occurring after the applications are understood herein as degradations. The studied gneisses present banding consisting of parts with different thicknesses and mineralogical contents. Due to these differentiated contents, clear bands were identified and constituted essentially by felsic minerals, such as feldspars and quartz, as well as dark bands formed by mafic minerals represented by: biotite, garnets, amphiboles, such as hornblende or pyroxene (hyperstene). In addition to these minerals, low contents of oxides and sulphides were found. Also under the influence of this distribution of minerals, planar structures or foliations, more or less developed, that can be very penetrative have been identified, mainly when these rocks were submitted to the performance of milonitization processes. From the set of changes and degradations observed stand out those related to the decomposition of minerals that make up these materials. In these cases, feldspars and other silicates, such as micas, amphiboles and pyroxenes, were decomposed due to the hydrolysis and products were generated which compromised the resistance of these stone materials, leading to their consequent disintegration. On the other hand, the presence of expansive clays in these products, caused volume increases which also contributed to the expansion of the weathered surface layer (blistering). This process may result detachments in the form of scales to cavities in cases of

  20. Microfabric reconstruction via quantitative digital petrographic image analysis for weakly foliated gneisses

    Science.gov (United States)

    Yeh, Meng-Wan; Lin, Yu-Ling; Lee, Tung-Yi; Ji, Jian-Qing

    2013-03-01

    Detection and documentation of petro-structural features such as alignment features of minerals/grains, and extraction of such spatial property data are two fundamental steps for structural geology. Such tasks were mostly carried out manually. However, manual analysis is laborious and potentially biased. These drawbacks are less obvious when the foliation is well developed and the amount of platy mineral is higher. For samples with weakly developed foliation and low platy mineral content, automatic method is required for subjective interpretation. A semi-automatic computerized method of 3D foliation orientation reconstruction via two-dimensional petrographic-shape fabric analysis from serial oriented digital microphotograph has been developed and demonstrated in this study. The foliation is reconstructed by fitting a best fitting plane to the maximum modal peaks of micro textural parameters (SPO) for different mineral groups of platy and granular minerals from each thin section on a stereonet for four coarse grained biotite gneiss samples collected along the Jialie fault, SE Tibet, China. Regardless of platy or granular mineral aggregates, the reconstructed foliations showed similar orientation within 10° angular variation to the field measurement. The 10° angular variation can be maintained if the foliations are reconstructed by consecutive thin section groupings ≦ 50° angular intervals and a horizontal thin section. The angular spread increased to 30° for thin section groupings with > 50° to 100° angular intervals with a horizontal thin section. Major advantages of the computerized photometric methods demonstrated by this study are: the reduction of human prejudice and obtaining quantified and repeatable data sets.

  1. Convergent radial tracing of viral and solute transport in gneiss saprolite.

    Science.gov (United States)

    Taylor, Richard; Tindimugaya, Callist; Barker, John; Macdonald, David; Kulabako, Robinah

    2010-01-01

    Deeply weathered crystalline rock aquifer systems comprising unconsolidated saprolite and underlying fractured bedrock (saprock) underlie 40% of sub-Saharan Africa. The vulnerability of this aquifer system to contamination, particularly in rapidly urbanizing areas, remains poorly understood. In order to assess solute and viral transport in saprolite derived from Precambrian gneiss, forced-gradient tracer experiments using chloride and Escherichia coli phage PhiX174 were conducted in southeastern Uganda. The bacteriophage tracer was largely unrecovered; adsorption to the weathered crystalline rock matrix is inferred and enabled by the low pH (5.7) of site ground water and the bacteriophage's relatively high isoelectric point (pI = 6.6). Detection of the applied PhiX174 phage in the pumping well discharge at early times during the experiment traces showed, however, that average ground water flow velocities exceed that of the inert solute tracer, chloride. This latter finding is consistent with observations in other hydrogeological environments where statistically extreme sets of microscopic flow velocities are considered to transport low numbers of fecal pathogens and their proxies along a selected range of linked ground water pathways. Application of a radial advection-dispersion model with an exponentially decaying source term to the recovered chloride tracer estimates a dispersivity (alpha) of 0.8 +/- 0.1 m over a distance of 4.15 m. Specific yield (S(y)) is estimated to be 0.02 from volume balance calculations based on tracer experiments. As single-site observations, our estimates of saprolite S(y) and alpha are tentative but provide a starting point for assessing the vulnerability of saprolite aquifers in sub-Saharan Africa to contamination and estimating quantitatively the impact of climate and abstraction on ground water storage.

  2. 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.)

  3. Investigation of the subsurface features of the basement complex of ...

    African Journals Online (AJOL)

    3D seismic reflection survey was recently carried out within the Zaria area of the basement complex of northern Nigeria, in order to investigate the complexity of the subsurface features within the basement. The geology of the survey area was characterized by gneisses and low grade meta-sedimentary rocks that form the ...

  4. Geochronology of granitic magmatism from Caraculo-Bibala region (SW Angola) and its correlation with Ribeira fold belt (SE Brazil)

    International Nuclear Information System (INIS)

    Carvalho, Heitor de; Tassinari, Colombo C.G.

    1992-01-01

    Rb-Sr whole-rock analyses of representative granitic rocks from the Bibala-Caraculo region, southwestern Angola, are used to determine the age and evolution of the acid plutonic events in this segment of the Angolan continental crust. The granitoids present a wide range of lithological types and compositions. Three time-intervals have been defined for the magmatism: 1,950 - 1,900 Ma; 1,750 - 1,700 Ma; 1,550 - 1,500 Ma. The oldest, though not very well defined, was obtained for the Chicalengue granitoid, the second one represents the Serra dos Gandarengos and Chonga granitoids and Luchipa-Pungue Granitic Complex and the youngest one comprises the Chicate and Caraculo granitic bodies and Numhino Granitic Complex. The initial 87 Sr/ 86 Sr ratios show characteristic values for each time-interval, as follows; 1,950 -1,900 Ma = 0,7015; 1,750 - 1,700 Ma = 0,7060 to 0,7075; 1,550 - 1,500 Ma 0,7048 - 0,7057, suggesting different sources for the granitoids within each geological period. In addition are presented two K-Ar ages for the basic rocks in SW Angola, with values of 1700 and 600 Ma, which represent a minimum ages for these rocks and are probably related to the Damara Orogeny. (author). 24 refs., 11 figs., 2 tabs

  5. The search for the youngest granites in the southern part of the Natal Metamorphic Province

    International Nuclear Information System (INIS)

    Thomas, R.J.; Eglington, B.M.

    1990-01-01

    It is clear that the Belmont Pluton and the dykes are geochemically, isotopically and therefore, genetically distinct. The Belmont pluton is probably related to the garnet leucogranite phase of the Margate Complex. It is suggested that the dykes (∼ 965 Ma) are younger than the Belmont pluton (∼1055 Ma). The relatively low initial 87 Sr/ 86 Sr are typical of the granites intruded at ∼1000 Ma. The age of the dykes is comparable with the 951 ± 16 Ma (R o =.70320 ± 13) given for the Sezela pluton. The high R o (∼0.715) of the dykes is similar to other, minor granite sheets from southern Natal, and is compatible with an origin by late-stage melting of pre-existing radiogenic material. Both the dykes and the Sezela pluton are unequivocally younger than the D 3 deformation, whereas the young dates from the Oribi Gorge Suite are controversial. Thus, although it is possible that some of the minor, intrusive granitic sheets could yet be shown to be of Pan-African age, it is evident that no significant Pan-African magmatism or thermal overprinting has affected the Natal sector of the Namaqua-Natal-Maudheim belt. 1 fig., 7 refs

  6. Radioactivity and radon emanation fraction of the granites sampled at Misasa and Badgastein.

    Science.gov (United States)

    Sakoda, Akihiro; Hanamoto, Katsumi; Ishimori, Yuu; Nagamatsu, Tomohiro; Yamaoka, Kiyonori

    2008-05-01

    The chemical composition was analyzed and the radioactivity, radon exhalation rate and emanation fraction were measured to investigate the characteristics of the granites sampled at Misasa and Badgastein, world famous for radon therapy. The Misasa granite was probably composed of quartz, albite and microcline. The Badgastein granite was probably composed of quartz and muscovite. The radon exhalation rates and emanation fractions of the Misasa granite were much higher than those of the Badgastein granite, regardless of the (226)Ra activity concentrations.

  7. Granite-related hypothermal uranium mineralization in South China

    International Nuclear Information System (INIS)

    Liu, X.; Wu, J.; Pan, J.; Zhu, M.

    2014-01-01

    As one of the important geological types, granite-related uranium deposits account for about 29% of the total discovered natural uranium resources in China. Most of the granite-related uranium deposits located in Taoshan - Zhuguang uranium metallogenic belt, South China. In addition to the typical pitchblende vein-type uranium mineralization of epithermal metallogenic system, a new type of granite-related uranium mineralization with characteristics of hypothermal matallogenic system was discovered in South China by current studies. However, hypothermal is contact thermal to epithermal mineralization, and not the conventional intrusive high temperature mineralization. Hypothermal uranium mineralization is presented by disseminated uraninite or pitchblende stockwork in fissures in granites normally with extensive alkaline alteration. The high temperature mineral assemblage of uraninite associate with scheelite and tourmaline was identified in hypothermal uranium mineralization. Fluid inclusion studies on this type mineralization indicated the middle to high temperature (>250℃) mineralization with the mixing evidence of ore forming solution derived from deep level, and the boiling and mixing of ore forming solution are regarded as the dominant mineralization mechanism for the precipitating of uranium. In contrast to the mineralization ages of 67 Ma to 87 Ma for typical pitchblende vein mineralization of epithermal metallogenic system, the mineralization age is older than 100 Ma for hypothermal uranium mineralization in granite. In the Shituling deposit, Xiazhuang uranium ore field, uraninite and pitchblende micro veins with extensive potassic alteration, chloritization and sericitization are hosted in fissures of Indo-Chinese epoch granites with the uranium mineralization age of 130 Ma to 138 Ma with a mineralization temperature of 290℃ to 330℃ indicated. Other examples sharing the similar characters of hypothermal uranium mineralization have been recognized in

  8. Radionuclide Transport in Fracture-Granite Interface Zones

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Q; Mori, A

    2007-09-12

    In situ radionuclide migration experiments, followed by excavation and sample characterization, were conducted in a water-conducting shear zone at the Grimsel Test Site (GTS) in Switzerland to study diffusion paths of radionuclides in fractured granite. In this work, we employed a micro-scale mapping technique that interfaces laser ablation sampling with inductively coupled plasma-mass spectrometry (LA/ICP-MS) to measure the fine-scale (micron-range) distribution of actinides ({sup 234}U, {sup 235}U, and {sup 237}Np) in the fracture-granite interface zones. Long-lived {sup 234}U, {sup 235}U, and {sup 237}Np were detected in flow channels, as well as in the adjacent rock matrix, using the sensitive, feature-based mapping of the LA/ICP-MS technique. The injected sorbing actinides are mainly located within the advective flowing fractures and the immediately adjacent regions. The water-conducting fracture studied in this work is bounded on one side by mylonite and the other by granitic matrix regions. These actinides did not penetrate into the mylonite side as much as the relatively higher-porosity granite matrix, most likely due to the low porosity, hydraulic conductivity, and diffusivity of the fracture wall (a thickness of about 0.4 mm separates the mylonite region from the fracture) and the mylonite region itself. Overall, the maximum penetration depth detected with this technique for the more diffusive {sup 237}Np over the field experimental time scale of about 60 days was about 10 mm in the granitic matrix, illustrating the importance of matrix diffusion in retarding radionuclide transport from the advective fractures. Laboratory tests and numerical modeling of radionuclide diffusion into granitic matrix was conducted to complement and help interpret the field results. Measured apparent diffusivity of multiple tracers in granite provided consistent predictions for radionuclide transport in the fractured granitic rock.

  9. Heat transfer studies in salt and granite

    International Nuclear Information System (INIS)

    Just, R.A.

    1978-10-01

    Results are presented of a scoping study on the feasibility of using a multi-layer terminal repository design in both salt and granite formations to store either high-level waste or spent fuel. Calculations have been made to determine temperature profiles within the repository and to provide an estimate of the thermal uplift that can be expected. Near-field models developed to compare temperature profiles in the regions close to the waste canisters indicated that maximum thermal gradients and maximum temperature increases could be significantly reduced by changing from a single to a multi-layer repository design. For both high-level waste and for spent fuel, the maximum temperature increase in the multi-level repositories was reduced to approximately 60 percent of the temperature increase predicted for the single-level repositories at the same areal loading. After the near-field models had verified that maximum thermal gradients and temperature increases could be reduced by using a multilevel repository design, a series of far-field models was developed. The far-field models used to provide qualitative comparisons of the maximum thermal uplift indicate that the thermal uplift is roughly proportional to the energy supplied to the formation. Changing from a single- to a multi-layer repository but keeping the areal loading constant results in increased thermal uplifts

  10. The correlation between selenium adsorption and the mineral and chemical composition of Taiwan local granite samples

    International Nuclear Information System (INIS)

    Wang, TsingHai; Chiang, Chu-Ling; Wang, Chu-Fang

    2015-01-01

    Selenium-79 (Se-79) is a radioactive isotope of selenium, which is considered as one of the highly mobile nuclides since Se-79 would be presented in an anion species when dissolving into the intruded groundwater. Being an anionic species, the transport of Se-79 would be regulated by the metal oxides relevant minerals such as goethite and hematite (Jan et al., 2008). This is true that the transport of selenium in the shallow surface environment could be relatively easy to estimate by considering the amount of these metal oxides presenting in the soils and sediments. However, when dealing with deep geological repository, the transport of Se-79 becomes less predictable because of the much less content of metal oxide residing in the host rock such as granite. In order to conduct a reliable performance assessment of repository, it is very important to establish the correlation between selenium adsorption and the properties of potential host rock, in this study, the mineral and chemical compositions of Taiwan local granite. From this point of view, selenium adsorption experiments were conducted with 54 different Taiwan local granite samples collected from the depth ranging from 100 ∝ 400 meters below the surface. These granite samples represent a variety of deep geological environments, including the intact rock, groundwater intruded zones, and some weathered samples. Based upon our preliminary results, several solid conclusions could be made. First, the correlation coefficients between the Kd values and the mineral and chemical compositions are rather low (R-square values are often < 0.2). This points out the complexity of these geological samples and strongly suggests more efforts should be put into to acquire more relevant information. Second, the correlation between the selenium Kd values and the content of iron oxide (R-square 0.110) is much higher than that between the CEC of these granite samples (R-square 0.001). This clearly indicates that the minerals that

  11. Geotectonic structural interpretation of the basement complex at the eastern border of the Espinhaco ridge, in Guanhaes and Gouveia region, based on an integration of their U/Pb and K/Ar geochronology united

    International Nuclear Information System (INIS)

    Teixeira, W.; Salvador, E.D.; Siga Junior, O.; Sato, K.; Dossin, I.A.; Dossin, T.M.

    1990-01-01

    The basement complex at the eastern border of the Espinhaco ridge is composed of predominantly gneissic rocks which were subjected to migmatization and granitization. Overall the area shows complex tectonic evolution with recurrence of tectonomagmatic and metamorphic events as supported by geological, geochronological and structural studies. The Rb/Sr geochronology carried out on the basement rocks and metavolcanics from the Espinhaco interpreted together with the published U-Pb, Rb-Sr and K-Ar data defines the following scenario for the Precambrian crustal evolution. 1. Primary origin of a sialic crust at 2.97-2.84 Ga. ago as supported by U-Pb zircon ages. 2. Crustal reworking of the Archean crust and subordinate juvenile accretion from upper mantle during the 2.2-2.OGa. period, as suggested by the isochrons. 3. Recurrence of Middle Proterozoic events over the basement rocks (gneisses and charnockites) and metavolcanics of the Espinhaco as showed by isochrons. 4. Development of Late Proterozoic migmatization over the basement rocks (0.75 Ga., R.I.= 0.787) is association with Collisional tectonics and resetting of K-Ar mineral systems. (author)

  12. Análise da erodibilidade de saprolitos de gnaisse Erodibility analysis of gneiss saprolite

    Directory of Open Access Journals (Sweden)

    F. Morais

    2004-12-01

    Full Text Available As voçorocas são freqüentes em áreas com rochas do embasamento cristalino. A evolução destas feições é sempre fortemente condicionada pelos processos de erosão hídrica subsuperficial, embora os processos superficiais também sejam importantes. Este trabalho objetivou investigar os processos erosivos subsuperficiais atuantes nas voçorocas e compreender que fatores mineralógicos e texturais poderiam influenciar a erodibilidade dos saprolitos. Para tanto, foram realizados ensaios de caracterização e de avaliação da erodibilidade em amostras representativas, sendo o principal destes o ensaio de furo de agulha. Os resultados indicam que a erosão por carreamento não ocorre e que os saprolitos apresentam susceptibilidade variável à erosão por piping, mesmo quando derivados de uma mesma unidade litológica, mas superior à do horizonte B latossólico. Dados preliminares indicam que os saprolitos mais susceptíveis à erosão por piping são os de textura siltosa (determinados em ensaios granulométricos sem defloculante e agitação e pobres em minerais agregadores, como os argilominerais.Gully erosion are very common in areas with gneiss basement rocks. Their development is strongly influenced by subsuperficial processes, although the surface ones are also important. This study aimed to investigate the subsuperficial erosion mechanisms of these gullies and to understand how mineralogy and texture could influence the saprolite erodibility. Some basic trials and erodibility tests were carried out in representative samples, with imphasis to especially the pin-hole test. The results showed that seepage erosion does not occur and that saprolite present variable susceptibility to piping erosion, even if they are in the same geologic unit. The data confirm that soils with Bw horizon (Oxisols are less erodible than any of the tested saprolites. Preliminary data suggest that saprolites with a silty texture (determined without dispersant

  13. Smolt Monitoring at the Head of Granite Reservoir and Lower Granite Dam, 1989 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Edwin W.; Nelson, V. Lance

    1990-04-01

    This project monitored the daily passage of chinook salmon Oncorhynchus tshawytscha and steelhead trout O. mykiss smolts during the 1989 spring outmigration at a migrant trap on the Snake River and the Clearwater River. Chinook salmon catch at the Snake River trap was much higher in 1989 than in either of the 1987 or 1988 drought years. The 1989 Snake River trap catch was similar to 1986. Effort was the same during the four years. Steelhead trout catch was greater than in any previous year. Chinook salmon and steelhead trout catch at the Clearwater River trap was similar to 1986, even though effort was greatly reduced in 1989 due to high runoff during most of the season. The 1989 Clearwater River trap catch was lower than in the two drought years (1987 and 1988) and was due to the minimal number of days the trap was operated. Fish tagged with Passive Interrogated Transponder (PIT) tags at the Snake River trap were recovered at the three dams (Lower Granite, Little Goose, and McNary) with PIT tag detection systems. Travel time (days) and migration rate (km/d) 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. 11 refs., 8 figs., 17 tabs.

  14. 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.)

  15. Resetting of Rb-Sr whole-rock isochrons during Sveconorwegian low-grade events in the Gjerstad augen gneiss, Telemark, southern Norway

    International Nuclear Information System (INIS)

    Smalley, P.C.; Field, D.; Raaheim, A.

    1983-01-01

    The Gjerstad augen gneiss comprises a single igneous body that shows intrusive relationships to the surrounding older Telemark gneisses. The formation of the gneissic structure and augen texture was due to mylonitic deformation along a major shear zone, the Porsgrunn-Kristiansand fault zone. The augen gneiss can be divided petrographically into green, grey (both pyroxene-bearing) and pink types. Samples from three locations were analysed isotopically. Two distinct (at 2sigma level) groups of ages were obtained which are interpreted as: (a) (approx. 1250 Ma) cooling after high temperature deformation and formation of retrogressive corona structures; (b) (approx. 1080 Ma) resetting of whole-rock systems during low-grade mineral alteration by hydrous fluids. At approx. 900 Ma, there was further isotopic disturbance during low-grade alteration related to the intrusion of pegmatite veins. The significant age differences are not related to colour (=grade) of samples, and significantly different ages have been found in the same rock body within a single locality. As the Gjerstad augen gneiss was intruded before approx. 1250 Ma into a previously; existing gneissic terrain, the gneiss-forming event and associated upper amphibolite facies metamorphism in the Gjerstad region is constrained to be pre approx. 1250 Ma, i.e. Pre-Sveconorwegian. (Auth.)

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

    International Nuclear Information System (INIS)

    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 2 O 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

  17. 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.

  18. Thermomechanical studies in granite at Stripa, Sweden

    International Nuclear Information System (INIS)

    Cook, N.G.W.; Myer, L.R.

    1981-01-01

    Media other than rock salt are being considered for the deep, geologic disposal of nuclear wastes. The disposal of high-level nuclear waste in a deep, underground repository will subject the rock to a thermal pulse that will induce displacements, strains, and stresses in the rock. Thermomechanical experiments, with electrical heaters simulating the thermal output of waste canisters, were carried out in granite at a depth of 340 m below surface adjacent to a defunct iron ore mine at Stripa, Sweden. Changes in temperature, displacement, and stress in the rock around these heaters were measured, and the measurements were compared with predictions calculated from the theory of linear thermoelasticity. Measured temperature changes agreed well with predictions, but measured displacements and stresses were consistently less than those predicted with constant values for the coefficient of thermal expansion and elastic properties of the rock. A laboratory test program to measure these coefficients over ranges of stress and temperature representing those in the field experiment has been initiated. Test specimens were taken from cores recovered from the instrumentation holes in the Stripa experiments. Preliminary results from laboratory tests on specimens free of joints indicate that the values of Young's modulus and Poisson's ratio increase from about 60 to 80 MPa and from 0.15 to 0.22, respectively, as the confining stress is increased from 2 to 55 MPa; these values decrease with increasing temperature, more so at 2 MPa than at 55 MPa. The linear coefficient of thermal expansion at a confining stress of 30 MPa increases from about 10 x 10 - 6 / 0 C at 40 0 C to about 14 x 10 - 6 / 0 C. The magnitudes of these changes are not sufficient to resolve the disparity between measured and predicted results. Perhaps the properties of test specimens containing joints will show greater variations in the values of the thermomechanical coefficients with temperature and pressure

  19. Determination of Matrix Diffusion Properties of Granite

    International Nuclear Information System (INIS)

    Holtta, Pirkko; Siitari-Kauppi, Marja; Huittinen, Nina; Poteri, Antti

    2007-01-01

    Rock-core column experiments were introduced to estimate the diffusion and sorption properties of Kuru Grey granite used in block-scale experiments. The objective was to examine the processes causing retention in solute transport through rock fractures, especially matrix diffusion. The objective was also to estimate the importance of retention processes during transport in different scales and flow conditions. Rock-core columns were constructed from cores drilled into the fracture and were placed inside tubes to form flow channels in the 0.5 mm gap between the cores and the tube walls. Tracer experiments were performed using uranin, HTO, 36 Cl, 131 I, 22 Na and 85 Sr at flow rates of 1-50 μL.min -1 . Rock matrix was characterized using 14 C-PMMA method, scanning electron microscopy (SEM), energy dispersive X-ray micro analysis (EDX) and the B.E.T. method. Solute mass flux through a column was modelled by applying the assumption of a linear velocity profile and molecular diffusion. Coupling of the advection and diffusion processes was based on the model of generalised Taylor dispersion in the linear velocity profile. Experiments could be modelled applying a consistent parameterization and transport processes. The results provide evidence that it is possible to investigate matrix diffusion at the laboratory scale. The effects of matrix diffusion were demonstrated on the slightly-sorbing tracer breakthrough curves. Based on scoping calculations matrix diffusion begins to be clearly observable for non-sorbing tracer when the flow rate is 0.1 μL.min -1 . The experimental results presented here cannot be transferred directly to the spatial and temporal scales that prevail in an underground repository. However, the knowledge and understanding of transport and retention processes gained from this study is transferable to different scales from laboratory to in-situ conditions. (authors)

  20. Fertility of Rare-Metal Peraluminous Granites and Formation Conditions of Tungsten Deposits

    Science.gov (United States)

    Syritso, L. F.; Badanina, E. V.; Abushkevich, V. S.; Volkova, E. V.; Terekhov, A. V.

    2018-01-01

    The tungsten distribution in rocks of the Kukulbei Complex in eastern Transbaikal region results in a high potential of rare-metal peraluminous granites (RPG) for W mineralization and displays a different behavior of W in Li-F and "standard" RPG. These subtypes differ in the behavior of W in melt, spatial localization of mineralization, and the timing of wolframite crystallization relative to the age of the parental granitic rocks. The significant of W concentration is assumed to be due to fractionation of the Li-F melt; however, wolframite mineralization in Li-F enriched granite is not typical in nature. The results of experiments and our calculations of W solubility in granitic melt show that wolframite hardly ever crystallizes directly from melt; it likely migrates in the fluid phase and is then removes from the magma chamber to the host rocks, where secondary concentration takes place in exocontact greisens and quartz-cassiterite-wolframite veins. At the same time, the isotopic age of accessory wolframite (139.5 ± 2.1 Ma) within the Orlovka massif of Li-F granite is close to the formation age of the massif (140.6 ± 2.9 Ma). A different W behavior is recorded in the RPG subtype with a low lithium and fluorine concentration, exemplified by the Spokoininsky massif. There is no significant W gain in the melt. All varieties of wolframite mineralization in the Spokoininsky massif are derived from greisens, veins, and pegmatoids yielding the same crystallization ages (139.5 ± 1.1 Ma), which are 0.9-1.8 Ma later (taking into account the mean-square weighted deviation) than the Spokoininsky granite formation (144.5 ± 1.4 Ma). Perhaps this period corresponds to the time of transition from the magmatic stage to hydrothermal alteration. Comparison of the isotope characteristics (Rb-Sr and Sm-Nd isotope systems) of rocks and the associated ore minerals (wolframite, cassiterite) from all examined deposits shows a depletion in ɛNd values for ore minerals relative to the

  1. Les « granites à tablettes d'orthose » du Vivarais, témoins d'un magmatisme post-épaississement d'âge Dinantien inférieur ; identification d'une unité géologique Nord-Ouest-VivaraisThe orthoclase lath-rich granites from Vivarais, products of a Dinantian post-tectonic magmatism; identification of a NW-Vivarais geological unit

    Science.gov (United States)

    Briand, Bernard; Duthou, Jean-Louis; Guerrot, Catherine; Chenevoy, Maurice

    On the southern side of the Mont Pilat (eastern French Massif Central), an orthoclase-rich granite, which intrudes orthogneisses overlying a granito-migmatitic complex, gives a Dinantian age (RbSr age: 353±21 Ma; UPb age: 341+8/-5 Ma). Such a dating confirms the reality of a 'northwestern Vivarais' geological unit, whose metamorphic and granitic evolution cannot be assigned to a Late-Carboniferous event. These results impose a re-examination of both the 'granite du Velay' problematic and the geodynamic evolution of the eastern French Massif Central. To cite this article: B. Briand et al., C. R. Geoscience 334 (2002) 741-747.

  2. Long length scales of element transport during reaction texture development in orthoamphibole-cordierite gneiss: Thor-Odin dome, British Columbia, Canada

    Science.gov (United States)

    Goergen, Eric T.; Whitney, Donna L.

    2012-02-01

    First-order factors controlling the textural and chemical evolution of metamorphic rocks are bulk composition and pressure-temperature-time ( P- T- t) path. Although it is common to assume that major element bulk composition does not change during regional metamorphism, rocks with reaction textures such as corona structures record evidence for major changes in effective bulk composition (EBC) and therefore provide significant insight into the scale, pathways, and mechanisms of element transport during metamorphism. Quantifying changes in EBC is essential for petrologic applications such as calculation of phase diagrams (pseudosections). The progressive growth of complex corona structures on garnet and Al2SiO5 porphyroblasts in orthoamphibole-cordierite gneiss Thor-Odin dome (British Columbia, Canada) reduced the EBC volume of the rock during metamorphism and therefore had a dramatic effect on the evolution of the stable mineral assemblage. These rocks contain a chemical and textural record of metamorphic reactions and preserve 3D networks (reaction pathways) connecting corona structures. These coronal networks record long (>cm) length scales of localized element transport during metamorphism. P- T, T- X, and P- X pseudosections are used to investigate the control of effective bulk composition on phase assemblage evolution. Despite textural complexity and evidence for disequilibrium, mineral assemblages and compositions were successfully modeled and peak metamorphic conditions estimated at 750°C and 9 kbar. These results illustrate how textural and chemical changes during metamorphism can be evaluated using an integrated petrographic and pseudosection approach, highlight the importance of effective bulk composition choice for application of phase equilibria methods in metamorphic rocks, and show how corona structures can be used to understand the scale of compositional change and element transport during metamorphism.

  3. Smolt Monitoring at the Head of Lower Granite Reservoir and Lower Granite Dam, 2005 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 2005 spring out-migration at migrant traps on the Snake River and Salmon River. In 2005 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, the age-1 and older fish were distinguishable from wild fish by the occurrence of fin erosion. Age-0 Chinook salmon are more difficult to distinguish between wild and non-adclipped hatchery fish and therefore classified as unknown rearing. The total annual hatchery spring/summer Chinook salmon catch at the Snake River trap was 0.34 times greater in 2005 than in 2004. The wild spring/summer Chinook catch was 0.34 times less than the previous year. Hatchery steelhead trout catch was 0.67 times less than in 2004. Wild steelhead trout catch was 0.72 times less than the previous year. The Snake River trap collected 1,152 age-0 Chinook salmon of unknown rearing. During 2005, the Snake River trap captured 219 hatchery and 44 wild/natural sockeye salmon and 110 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 6 and were terminated on June 3. The trap was out of operation for a total of one day due to heavy debris. FPC requested that the trap be restarted on June 15 through June 22 to collect and PIT tag age-0 Chinook salmon. Hatchery Chinook salmon catch at the Salmon River trap was 1.06 times greater and wild Chinook salmon catch was 1.26 times greater than in 2004. The hatchery steelhead trout collection in 2005 was 1.41 times greater and wild steelhead trout collection was 1.27 times greater than the previous year. Trap operations

  4. 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

  5. Smolt Monitoring at the Head of Lower Granite Reservoir and Lower Granite Dam, 2002 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 smolts O. nerka during the 2002 spring out-migration at migrant traps on the Snake River and Salmon River. In 2002 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 11.4 times greater in 2002 than in 2001. The wild Chinook catch was 15.5 times greater than the previous year. Hatchery steelhead trout catch was 2.9 times greater than in 2001. Wild steelhead trout catch was 2.8 times greater than the previous year. The Snake River trap collected 3,996 age-0 Chinook salmon of unknown rearing. During 2002, the Snake River trap captured 69 hatchery and 235 wild/natural sockeye salmon and 114 hatchery coho salmon O. kisutch. 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. The significant increase in catch in 2002 was due to a 3.1 fold increase in hatchery Chinook production and a more normal spring runoff. Trap operations began on March 10 and were terminated on June 7. The trap was out of operation for a total of four days due to mechanical failure or debris. Hatchery Chinook salmon catch at the Salmon River trap was 4.2 times greater and wild Chinook salmon catch was 2.4 times greater than in 2001. The hatchery steelhead trout collection in 2002 was 81% of the 2001 numbers. Wild steelhead trout collection in 2002 was 81% of the previous year's catch. Trap operations began on March 10 and were terminated on May 29 due to high flows. The trap was out of operation for four days due to high flow or debris. The

  6. Smolt Monitoring at the Head of Lower Granite Reservoir and Lower Granite Dam, 2003 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 2003 spring out-migration at migrant traps on the Snake River and Salmon River. In 2003 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 2.1 times less in 2003 than in 2002. The wild Chinook catch was 1.1 times less than the previous year. Hatchery steelhead trout catch was 1.7 times less than in 2002. Wild steelhead trout catch was 2.1 times less than the previous year. The Snake River trap collected 579 age-0 Chinook salmon of unknown rearing. During 2003, the Snake River trap captured five hatchery and 13 wild/natural sockeye salmon and 36 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. The significant differences in catch between 2003 and the previous year were due mainly to low flows during much of the trapping season and then very high flows at the end of the season, which terminated the trapping season 12 days earlier than in 2002. Trap operations began on March 9 and were terminated on May 27. 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 16.8% less and wild Chinook salmon catch was 1.7 times greater than in 2002. The hatchery steelhead trout collection in 2003 was 5.6% less than in 2002. Wild steelhead trout collection was 19.2% less than the previous year. Trap operations began on March 9 and were terminated on May 24 due to high

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

    International Nuclear Information System (INIS)

    Bucher, Kurt; Zhang Lifei; Stober, Ingrid

    2009-01-01

    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 -1 Na-SO 4 -Cl water with a temperature of 55 deg. C having a total mineralization of about 1 g L -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 4 and Cl, Ca is a minor component. Dissolved silica (1.04 mmol L -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 -1 F - 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. Sodium chloride is stored in fluid

  8. Uranium distribution in Brazilian granitic rocks. Identification of uranium provinces

    International Nuclear Information System (INIS)

    Tassinari, C.G.G.

    1993-01-01

    The research characterized and described uranium enriched granitoids in Brazil. They occur in a variety of tectonic environments and are represented by a variety granite types of distinct ages. It may be deduced that in general they have been generated by partial melting process of continental crust. However, some of them, those with tonality composition, indicate a contribution from mantle derived materials, thus suggesting primary uranium enrichment from the upper mantle. Through this study, the identification and characterization of uranium enriched granite or uranium provinces in Brazil can be made. This may also help identify areas with potential for uranium mineralization although it has been note that uranium mineralization in Brazil are not related to the uranium enrichment process. In general the U-anomalous granitoids are composed of granites with alkaline composition and granite ''sensu strictu'' which comprise mainly of syenites, quartz-syenites and biotite-hornblende granites, with ages between 1,800 - 1,300 M.a. The U-anomalous belongings to this period present high Sr initial ratios values, above 0.706, and high Rb contents. Most of the U-enriched granitoids occur within ancient cratonic areas, or within Early to Mid-Proterozoic mobile belts, but after their cratonization. Generally, these granitoids are related to the border zones of the mobile belts or deep crustal discontinuity. Refs, 12 figs, 3 tabs

  9. Constraints from geochemistry and oxygen isotopes for the hydrothermal origin of orthoamphibole mafic gneiss in the New Jersey Highlands, north-central Appalachians, USA

    Science.gov (United States)

    Volkert, Richard A.; Peck, William H.

    2017-12-01

    Rare exposures of orthoamphibole mafic (Oam) gneiss of Mesoproterozoic age in the north-central Appalachians are confined to the northwestern New Jersey Highlands where they form thin lens-shaped bodies composed of gedrite and sparse anthophyllite, oligoclase (An13-An20), biotite, magnetite, and local fluorapatite, rutile, and ilmenite. The gneiss is penetratively foliated and has sharp, conformable contacts against enclosing supracrustal paragneiss and marble. Orthoamphibole mafic gneiss is characterized by low SiO2 (48 ± 2.5 wt%), CaO (1.9 ± 1.3 wt%), and high Al2O3 (18 ± 1.2 wt%), Fe2O3 (10.5 ± 1.6 wt%), and MgO (12 ± 2.3 wt%). Trace element abundances overlap those of unaltered amphibolites in the study area and, coupled with δ18O values of 9.45 ± 0.6‰ (VSMOW) from gedrite separates, support an origin from a basalt protolith. The geochemical and isotopic data are consistent with the formation of Oam gneiss through sea floor hydrothermal alteration of basalt at low temperature of 150-200 °C. Mass-balance calculations indicate gains during alteration mainly in MgO and Al2O3 and losses in CaO, Sr, and light rare earth elements. Our results are compatible with the pre-metamorphic alteration of the basalt protoliths through chloritization and plagioclase dissolution that produced a Mg-rich and Ca-poor rock. Subsequent metamorphism of this chlorite-rich rock to the current mineral assemblage of Oam gneiss took place at ca. 1045 Ma, during the Ottawan phase of the Grenvillian Orogeny. The close spatial association in the study area of Oam gneiss bodies and sulfide occurrences suggests an affinity to the style of mineralization associated with volcanogenic massive sulfide (VMS)-type deposits.

  10. 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.

  11. First data on Sm-Nd ages of Archean basalts of the Karelian granite-green rock region

    International Nuclear Information System (INIS)

    Sochevanov, N.N.; Arestov, N.A.; Matrenichev, V.A.; Lobach-Zhuchenko, S.B.; Guseva, V.F.

    1991-01-01

    The first results of Sm-Nd dating of metabasalts of two green-rock structures located in the South-East part of the Baltic shield are presented. The age of formation of basalt mass and differentiated mass was 2916±70 and 2960±150 Ma, respectively. Reliable determination of basalt vulcanism manifestation time (2.9 Ga) permits evaluating the lower boundary of formation of granite-green rock complex as 3.0±0.1 Ga

  12. 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.

  13. Smolt Monitoring at the Head of Lower Granite Reservoir and Lower Granite Dam, 1994 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Edwin W.; Brimmer, Arnold F.

    1994-10-01

    This project monitored the daily passage of chinook salmon Oncorhynchus tshawytscha and steelhead trout O. mykiss smolts during the 1994 spring outmigration at migrant traps on the Snake River, Clearwater River, and Salmon River. The 1994 snowpack was among the lowest since the beginning of the present drought, and the subsequent runoff was very poor. All hatchery chinook salmon released above Lower Granite Dam were marked with a fin clip in 1994. Total annual (hatchery + wild) chinook salmon catch at the Snake River trap was 1.5 times greater than in 1993. Hatchery and wild steelhead trout catches were similar to 1993. The Snake River trap collected 30 age 0 chinook salmon. Hatchery chinook salmon catch at the Clearwater River trap was 3.5 times higher than in 1993, and wild chinook salmon catch was 4.2 times higher. Hatchery steelhead trout trap catch was less than half of 1993 numbers because the trap was fishing near the north shore during the majority of the hatchery steelhead movement due to flow augmentations from Dworshak. Wild steelhead trout trap catch was 2 times higher than in 1993. The Salmon River trap was operated for about a month longer in 1994 than in 1993 due to extremely low flows. Hatchery chinook salmon catch was 1.4 times greater in 1994 than the previous year. Wild chinook salmon catch was slightly less in 1994. The 1994 hatchery steelhead trout collection did not change significantly from 1993 numbers. Wild steelhead trout collection in 1994 was 59% of the 1993 catch. Fish tagged with Passive Integrated Transponder (PIT) tags at the Snake River trap were interrogated at four dams with PIT tag detection systems (Lower Granite, Little Goose, Lower Monumental, and McNary dams). Because of the addition of the fourth interrogation site (Lower Monumental) in 1993, cumulative interrogation data is not comparable with the prior five years (1988-1992).

  14. Radiatives elements distribution in Serra do Carambei granite, Parana, Brazil

    International Nuclear Information System (INIS)

    Pinto-Coelho, C.V.; Siedlecki, K.N.

    1988-01-01

    In the Serra do Carambei Granite, the uranium present in the rock in anomalous concentration is hosted, preferentially, in accessory mineralogical phases-zircon, xenotime, magnetite and ilmenite, and, in lesser proportion, in the essential minerals of the rock-potassium feldspar and also iron oxydes/hydroxydes and alterated biotite. Optical petrography, autorradiomicrography, scanning electronic microscopy, and the utilization of correlation matrixes and the respective dendrograms revealed a distribution of radioactive elements basically controlled by autometassomatic, tardi/pos-magmatic or supergene processes. Intrusive felsic dikes in the Serra do Carambei Granite have radioelement concentration level approximately four times higher than the enclosing granite, where uranium as well as thorium is preferentially found in metamictized accessory minerals-zircon and allanite. (author) [pt

  15. 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.

  16. Analysis of Shield Construction in Spherical Weathered Granite Development Area

    Science.gov (United States)

    Cao, Quan; Li, Peigang; Gong, Shuhua

    2018-01-01

    The distribution of spherical weathered bodies (commonly known as "boulder") in the granite development area directly affects the shield construction of urban rail transit engineering. This paper is based on the case of shield construction of granite globular development area in Southern China area, the parameter control in shield machine selection and shield advancing during the shield tunneling in this special geological environment is analyzed. And it is suggested that shield machine should be selected for shield construction of granite spherical weathered zone. Driving speed, cutter torque, shield machine thrust, the amount of penetration and the speed of the cutter head of shield machine should be controlled when driving the boulder formation, in order to achieve smooth excavation and reduce the disturbance to the formation.

  17. Association of lung cancer mortality with precambrian granite

    International Nuclear Information System (INIS)

    Archer, V.E.

    1987-01-01

    Sixteen counties in New York, Pennsylvania, and New Jersey that are associated with the Reading Prong granite deposits have significantly higher age-adjusted lung cancer rates among whites of both sexes (1950-1979) than do 17 nearby control counties. Elevated radon daughter concentrations have been found in homes near the Reading Prong granites. Fraction of populations living in cities with over 5,000 persons, industrial centers, cities with populations above 20,000, and median incomes did not differ significantly for three county groups (those which include the granite, fringe area, and control areas). Weaknesses were inadequate home measurements of radon and lack of smoking information. Findings are consistent with several other studies relating radon in homes to lung cancer

  18. 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.

  19. 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

  20. Late Triassic granites from Bangka, Indonesia: A continuation of the Main Range granite province of the South-East Asian Tin Belt

    Science.gov (United States)

    Ng, Samuel Wai-Pan; Whitehouse, Martin J.; Roselee, Muhammad H.; Teschner, Claudia; Murtadha, Sayed; Oliver, Grahame J. H.; Ghani, Azman A.; Chang, Su-Chin

    2017-05-01

    The South-East Asian Tin Belt is one of the most tin-productive regions in the world. It comprises three north-south oriented granite provinces, of which the arc-related Eastern granite province and the collision-related Main Range granite province run across Thailand, Singapore, and Indonesia. These tin-producing granite provinces with different mineral assemblages are separated by Paleo-Tethyan sutures exposed in Thailand and Malaysia. The Eastern Province is usually characterised by granites with biotite ± hornblende. Main Range granites are sometimes characterised by the presence of biotite ± muscovite. However, the physical boundary between the two types of granite is not well-defined on the Indonesian Tin Islands, because the Paleo-Tethyan suture is not exposed on land there. Both hornblende-bearing (previously interpreted as I-type) and hornblende-barren (previously interpreted as S-type) granites are apparently randomly distributed on the Indonesian Tin Islands. Granites exposed on Bangka, the largest and southernmost Tin Island, no matter whether they are hornblende-bearing or hornblende-barren, are geochemically similar to Malaysian Main Range granites. The average ɛNd(t) value obtained from the granites from Bangka (average ɛNd(t) = -8.2) falls within the range of the Main Range Province (-9.6 to -5.4). These granites have SIMS zircon U-Pb ages of ca. 225 Ma and ca. 220 Ma, respectively that are both within the period of Main Range magmatism (∼226-201 Ma) in the Peninsular Malaysia. We suggest that the granites exposed on Bangka represent the continuation of the Main Range Province, and that the Paleo-Tethyan suture lies to the east of the island.

  1. Alteration and arenization processes of granitic waste rock piles from former uranium Mines in Limousin, France.

    Science.gov (United States)

    Kanzari, Aisha; Boekhout, Flora; Gérard, Martine; Galoisy, Laurence; Phrommavanh, Vannapha; Descostes, Michael

    2014-05-01

    France counts approximately 200 former uranium mines, 50 of which are located in the Limousin region. Mining activities between 1945 and 2001 have generated close to 200 000 tons of waste rocks in the Limousin, with uranium levels corresponding essentially to the geological background. Waste rock piles from three former mining sites in this region, were selected according to their age, uranium content and petrological signature. These sites are part of the two-mica granitic complex of St Sylvestre massif, formed 324 million years ago. Granitic blocks that build up the waste rock piles have experienced different processes and intensities of alteration before their emplacement at the surface. These processes are responsible for the petrological heterogeneity throughout the waste rock pile at the time of construction. It is important to make a distinction within waste rocks between natural-cut-off waste rocks and economic-cut-off waste rocks. The latter represents a minority and is linked to stock prices. Natural-cut-off waste rocks contain about 20 ppm of uranium; economic-cut-off waste rocks contain about 100 to 300 ppm of uranium. The aims of this study are to 1) assess the neo-formation of U-bearing minerals hosted by these rocks, and 2) to characterize the weathering processes since the construction of the rock piles, including both mechanical and chemical processes. The structure of the waste rocks piles, from metric blocks to boulders of tens centimeters, induces an enhanced weathering rate, compared to a granitic massif. Mechanical fracturing and chemical leaching by rainwater (arenization) of the waste rocks produce a sandy-silty alteration phase. Silty-clay weathering aureoles of submetric-granitic blocks evolving into technic soil are mainly located below growing birch trees. Sampling on the rock piles was restricted to surface rocks. Samples collected consist mainly of granites, and rare lamprophyres with a high radiometric signal, thereby especially

  2. Polymetamorphic history of the Crixas-Acu gneiss, central Brazil: SHRIMP U-Pb evidence from titanite and zircon

    International Nuclear Information System (INIS)

    Queiroz, Claudia Lima; Jost, Hardy; McNaughton, Neil J.; Fletcher, I.R.; Barley, Mark E.

    2000-01-01

    A sample of the Crixas-Acu gneiss in Central Brazil contains protolith and metamorphic zircons, and two generations of metamorphic titanite. SHRIMP U-Pb data of these different mineral generations indicate the following temporal sequence: tonalitic magmatism at 2817 ± 9 M.y derived from an older source region (3050 to 2930 M.y zircon cores); Archaen metamorphic at 2772±6 M.y (from zircon)with cooling to the blocking temperature of titanite (at 2711 ±34 Ma); followed by Paleoproterozoic metamorphism and weak fabric development at 2011 ±+ 15 Ma, and a possible Neoproterozoic metamorphism. The field relations and these age data indicate the polymetamorphic history of the area and demonstrate the value of in situ age determinations on well-characterized rocks. (author)

  3. 76 FR 62758 - Wallowa-Whitman and Umatilla National Forests, Oregon Granite Creek Watershed Mining Plans

    Science.gov (United States)

    2011-10-11

    ... Granite Creek Watershed Mining Plans AGENCY: Forest Service, USDA. ACTION: Notice of intent to prepare an... to authorize the approval of mining Plans of Operation in the Granite Creek Watershed Mining Plans... environmental analyses for proposed mining Plans in the portions of the Granite Creek Watershed under their...

  4. Evidence for diamond-grade ultra-high pressure metamorphism and fluid interaction in the Swartberget Fe-Ti garnet periodotite-websterite body, Western Gneiss Region, Norway

    NARCIS (Netherlands)

    Vrijmoed, J.C.; Van Roermund, H.L.M.; Davies, G.R.

    2006-01-01

    Based on mineral-chemical evidence we propose that the northernmost Scandian ultra-high pressure (UHP) metamorphic domain within the Western Gneiss Region of Norway can be extended 25 km northeastwards. A newly discovered, well preserved, fine-grained, Fe-Ti type garnet peridotite body at

  5. Elastic anisotropy of layered rocks: Ultrasonic measurements of plagioclase-biotite-muscovite (sillimanite) gneiss versus texture-based theoretical predictions (effective media modeling)

    Czech Academy of Sciences Publication Activity Database

    Ivankina, T. I.; Zel, I. Yu.; Lokajíček, Tomáš; Kern, H.; Lobanov, K. V.; Zharikov, A. V.

    712/713, 21 August (2017), s. 82-94 ISSN 0040-1951 R&D Projects: GA MŠk LH13102 Institutional support: RVO:67985831 Keywords : compositional layering * crystallographic texture * effective elastic properties calculation * neutron diffraction * plagioclase-biotite-muscovite (sillimanite) gneiss * velocity measurements Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 2.693, year: 2016

  6. Smolt Monitoring at the Head of Lower Granite Reservoir and Lower Granite Dam, 1998 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Edwin W.; Brimmer, Arnold F.

    2000-04-01

    This project monitored the daily passage of chinook salmon Oncorhynchus tshawytscha, steelhead trout O. mykiss, and sockeye salmon smolts O. nerka, during the 1998 spring outmigration at migrant traps on the Snake and Salmon rivers. All hatchery chinook salmon released above Lower Granite Dam 19 1998 were marked with a fin-clip. Total annual hatchery chinook salmon catch at the Snake River trap was 226% of the 1997 number and 110% of the 1996 catch. The wild chinook catch was 120% of the 1997 catch but was only 93% of 1996. Hatchery steelhead trout catch was 501% of 1997 numbers but only 90% of the 1996 numbers. Wild steelhead trout catch was 569% of 1997 and 125% of the 1996 numbers. The Snake River trap collected 106 age-0 chinook salmon. During 1998, for the first time, the Snake River trap captured a significant number of hatchery sockeye salmon (1,552) and hatchery coho salmon O. kisutch (166). 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 high flows. Trap operations began on March 8 and were terminated for the season due to high flows on June 12. The trap was out of operation for 34 d during the season due to high flow and debris. Hatchery chinook salmon catch at the Salmon River trap was 476% and wild chinook salmon catch was 137% of 1997 numbers and 175% and 82% of 1996 catch, respectively. The hatchery steelhead trout collection in 1998 was 96% of the 1997 catch and 13% of the 1996 numbers. Wild steelhead trout collection in 1998 was 170% of the 1997 catch and 37% of the 1996 numbers. Travel time (d) and migration rate (km/d) through Lower Granite Reservoir for PIT-tagged chinook salmon and steelhead trout, marked at the head of the reservoir were affected by discharge. For fish tagged at the Snake River trap, statistical analysis of 1998 detected a significant relation between migration rate and discharge. For hatchery and

  7. Smolt monitoring at the head of Lower Granite Reservoir and Lower Granite Dam, 1998.; ANNUAL

    International Nuclear Information System (INIS)

    2000-01-01

    This project monitored the daily passage of chinook salmon Oncorhynchus tshawytscha, steelhead trout O. mykiss, and sockeye salmon smolts O. nerka, during the 1998 spring outmigration at migrant traps on the Snake and Salmon rivers. All hatchery chinook salmon released above Lower Granite Dam 19 1998 were marked with a fin-clip. Total annual hatchery chinook salmon catch at the Snake River trap was 226% of the 1997 number and 110% of the 1996 catch. The wild chinook catch was 120% of the 1997 catch but was only 93% of 1996. Hatchery steelhead trout catch was 501% of 1997 numbers but only 90% of the 1996 numbers. Wild steelhead trout catch was 569% of 1997 and 125% of the 1996 numbers. The Snake River trap collected 106 age-0 chinook salmon. During 1998, for the first time, the Snake River trap captured a significant number of hatchery sockeye salmon (1,552) and hatchery coho salmon O. kisutch (166). 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 high flows. Trap operations began on March 8 and were terminated for the season due to high flows on June 12. The trap was out of operation for 34 d during the season due to high flow and debris. Hatchery chinook salmon catch at the Salmon River trap was 476% and wild chinook salmon catch was 137% of 1997 numbers and 175% and 82% of 1996 catch, respectively. The hatchery steelhead trout collection in 1998 was 96% of the 1997 catch and 13% of the 1996 numbers. Wild steelhead trout collection in 1998 was 170% of the 1997 catch and 37% of the 1996 numbers. Travel time (d) and migration rate (km/d) through Lower Granite Reservoir for PIT-tagged chinook salmon and steelhead trout, marked at the head of the reservoir were affected by discharge. For fish tagged at the Snake River trap, statistical analysis of 1998 detected a significant relation between migration rate and discharge. For hatchery and

  8. Smolt Monitoring at the Head of Lower Granite Reservoir and Lower Granite Dam, 1990 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Edwin W.; Nelson, V. Lance

    1991-05-01

    This project monitored the daily passage of chinook salmon Oncorhynchus tshawytscha and steelhead trout Oncorhynchus mvkiss smolts during the 1990 spring outmigration at migrant traps on the Snake River and the Clearwater River. Chinook salmon catch at the Snake River trap was similar to 1987 and 1988, drought years, but considerably less than 1989, a near normal flow year. Trapping effort was the same during the four years. Hatchery steelhead trout catch was similar to 1988 and 1989. Wild steelhead trout catch was greater than in any previous year. Chinook salmon catch at the Clearwater River trap was slightly less than in 1987 or 1988 and considerably higher than in 1989. Hatchery steelhead trout trap catch was 3 to 26 times greater than in previous years. Wild steelhead trout trap catch was 2 to 11 times greater than in previous years. Fish tagged with Passive Integrated Transponder (PIT) tags at the Snake River trap were recovered at the three dams with PIT tag detection systems (Lower Granite, Little Goose, and McNary dams). Cumulative recovery at the three dams for fish marked at the Snake River trap was 64.4% for chinook salmon, 83.1% for hatchery steelhead trout, and 79.0% for wild steelhead trout. Cumulative recovery at the three dams for fish PIT-tagged at the Clearwater River trap was 54.6% for chinook salmon, 77.6% for hatchery steelhead trout, and 70.4% for wild steelhead trout. Travel time (days) and migration rate (km/d) 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 a two-fold increase in discharge increased migration rate by 2.2 times for PIT-tagged chinook salmon released from the Snake River trap and 1.8 times for chinook salmon released from the Clearwater River trap. A two-fold increase in discharge increased migration rate by 3.1 times for PIT-tagged hatchery steelhead trout released from the Snake River trap

  9. THE KIGOM PERALKALINE GRANITE PLUTON OF THE NIGERIAN ...

    African Journals Online (AJOL)

    The kigom granites in central Nigeria are alkali amphibole bearing and peralkaline in nature. They are hypersolvus in character and contain mesoperthite in which the albite (Or1-2) and microcline are present in approximately equal proportions. The albite is fully ordered while K-rich feldspar is dominantly microcline.

  10. Erosion over time on severely disturbed granitic soils: a model

    Science.gov (United States)

    W. F. Megahan

    1974-01-01

    A negative exponential equation containing three parameters was derived to describe time trends in surface erosion on severely disturbed soils. Data from four different studies of surface erosion on roads constructed from the granitic materials found in the Idaho Batholith were used to develop equation parameters. The evidence suggests that surface "armoring...

  11. Assessment of radioactivity in building material(granite) in Sudan

    International Nuclear Information System (INIS)

    Osman, Z. A; Salih, I; Albadwai, K. A; Salih, A. M; Salih, S. A.

    2016-01-01

    In the present work radioactivity in building materials (granite) central Sudan was evaluated. In general the building materials used in Sudan are derived either from rocks or soil. These contain trace amounts of naturally occurring radioactive materials(NORMs), so it contains radionuclides from uranium and thorium series and natural potassium. The levels of these radionuclides vary according to the geology of their site of origin. High levels increase the risk of radiation exposure in homes(especially exposure due to radon). Investigation of radioactivity in granite used of the building materials in Sudan is carried out, a total of 18 major samples of granite have been collected and measured using X- ray fluorescence system (30 mci). The activity concentrations have been determined for uranium ( 238 U), thorium ('2 32 Th) and potassium( 40 K) in each sample. The concentrations of uranium have been found to range from 14.81 Bq/kg to 24.572 Bq/kg, thorium between 10.02 Bq/kg and 10.020-84.79 Bq/kg and the potassium concentration varies between 13.33 Bq/kg to 82.13 Bq/kg. Limits of radioactivity in the granite are based on dose criteria for controls. This study can be used as a reference for more extensive studies of the same subject in future. (Author)

  12. lithologic features and uranium possibilities of the granites of pupule ...

    African Journals Online (AJOL)

    and interpretation of the result suggest that the fairly enhanced radioactivity in the fine-grained granite, southeast of. Pupule, may be related to ..... Elements distribution patterns in the uranium occurrence at Mika, Northeastern Nigeria. Chemie der Erde,. 56, 215-260. Geological Survey of Nigeria, (1974). Geological map of.

  13. Fourier-transform Infrared Characterization of Kaolin, Granite ...

    African Journals Online (AJOL)

    Fourier-transform Infrared Characterization of Kaolin, Granite, Bentonite and Barite. ... Diazonium salts at the peak region frequency of 3200-3100cm-1, organic substance at peak region of 2900-2700cm-1, by comparing the spectra obtained with those ... Keywords: characterization; clays; infrared; minerals; spectroscopy ...

  14. Extraction of Th and U from Swiss granites

    International Nuclear Information System (INIS)

    Bajo, C.

    1980-12-01

    The extraction, at the laboratory level, of U and Th from Swiss granites is discussed. The Mittagfluh, Bergell and Rotondo granites and the Giuv syenite offered a wide range of U and Th concentrations; 7.7 to 20.0 ppm U and 25.5 to 67.0 ppm Th. U and Th were determined in the leach solutions by the fission track method and by spectrophotometry, respectively. Samples containing less than 0.3 μg U and 4 μg Th, could be measured with an accuracy of 10% for U and 5% for Th. Leach tests were performed during which the following parameters were varied: granite-type, grain size, acid-type, acid concentration, temperature and time. There were very great leaching differences between the granites studied. Temperature was the most important parameter. Sharp differences in extraction occurred between 20 0 C, 50 0 C and 80 0 C. At 80 0 C, more than 85% U and Th were extracted. The extraction curve (percent extracted as a function of time) of aliquots sampled after 1, 2, 4, 8, 12 and 24 hours showed a plateau after 8 hours. The half life of the reaction was between one and two hours. As a general rule, Th was better extracted than U. (Auth.)

  15. Characteristics of pegmatoidal granite exposed near Bayalan, Ajmer ...

    Indian Academy of Sciences (India)

    Introduction. A long geological history since Middle Archaean is recorded in ... Keywords. Pegmatoidal granite; Bhim Group; South Delhi Fold Belt; phacolith. J. Earth Syst. Sci. 120, No. 4, August 2011, pp. 617–626. cO Indian Academy of Sciences. 617 ... ates, epidote, sphene, apatite, zircon with rare occurrences of zoisite ...

  16. Water–rock interaction on the development of granite gneissic ...

    Indian Academy of Sciences (India)

    Water–rock interaction on the development of granite gneissic weathered profiles in Garhwal Lesser Himalaya, India. S Vyshnavi and R Islam∗. Wadia Institute of Himalayan Geology, Dehradun 248 001, India. ∗Corresponding author. e-mail: rislam@wihg.res.in. The development and sustainability of weathered profiles are ...

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

    Indian Academy of Sciences (India)

    schists, argillites, and quartzite. He did not men- tion the occurrence of any granite from the area. The presence of thick conglomerate along the east- ern margin is a rare feature in the DFB rocks unlike the western margin of DFB, where Heron (1953),. Murthy and Bhargava (1972), Biswal (1993) and. Dasgupta et al. (2012) ...

  18. Aggregate impact testing of selected granite samples from sites in ...

    African Journals Online (AJOL)

    The Aggregate Impact Testing machine was used to measure the resistance to fa ilure of Rocks from five (5) selected granite quarries to a suddenly applied force using S ingapore standard. The results obtained show that brittleness (S20) value of the rocks were between 2 - 10. These values are less than the stated ...

  19. Characteristics of pegmatoidal granite exposed near Bayalan, Ajmer ...

    Indian Academy of Sciences (India)

    Roy 1984; Gupta and Bose 2000). The aim of the present study is to elucidate the tectonic evolu- ... on the hinges of the folds defined by the gneissosity. Keywords. Pegmatoidal granite; Bhim Group; South Delhi Fold Belt; phacolith. J. Earth Syst. Sci. 120, No. 4, August 2011, pp. 617–626. cO Indian Academy of Sciences.

  20. 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

  1. the use of fk filter in the elimination of artefacts from a shallow ...

    African Journals Online (AJOL)

    DJFLEX

    Near surface high resolution 2-D seismic reflection survey was carried out along the Zaria batholith. Zaria area forms part of the Precambrian basement complex of north central Nigeria which comprises Precambrian rocks made up of granite, gneiss and Low-grade metasediments. The granitic Zaria batholith intruded the ...

  2. The use of F-K filter in the elimination of artefacts from a shallow ...

    African Journals Online (AJOL)

    Near surface high resolution 2-D seismic reflection survey was carried out along the Zaria batholith. Zaria area forms part of the Precambrian basement complex of north central Nigeria which comprises Precambrian rocks made up of granite, gneiss and Low-grade metasediments. The granitic Zaria batholith intruded the ...

  3. Sm-Nd Ages of Two Meta-Anorthosite Complexes Around ...

    Indian Academy of Sciences (India)

    Whole-rock Sm-Nd isochron ages are reported for two stratiform meta-anorthosite complexes emplaced into the Archean supracrustal-gneiss association in the amphibolite facies terrain around Holenarsipur, in the Dharwar carton, South India. While these metaperidotite-pyroxenite-gabbro-anorthosite complexes are ...

  4. 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

  5. Petrogenesis of the Late Jurassic peraluminous biotite granites and muscovite-bearing granites in SE China: geochronological, elemental and Sr-Nd-O-Hf isotopic constraints

    Science.gov (United States)

    Jiang, Yao-Hui; Zhu, Shu-Qi

    2017-12-01

    Biotite granites and muscovite-bearing granites are dominant rock types of the widespread granites in SE China. However, their petrogenesis has been enigmatic. A combined study of zircon U-Pb dating and Lu-Hf isotopes, whole-rock element geochemistry and Sr-Nd-O isotopes was performed for three late Mesozoic granitic plutons (Xinfengjie, Jiangbei and Dabu) in central Jiangxi province, SE China. All the plutons are composed of biotite granites and muscovite-bearing granites that have been poorly investigated previously. The new data not only allow us to assess their sources and magma evolution processes, but also helps us to better understand the genetic link to the large-scale polymetallic mineralization in SE China. LA-ICP-MS zircon U-Pb dating shows that three plutons were emplaced in the Late Jurassic (159-148 Ma) and that the muscovite-bearing granites are almost contemporaneous with the biotite granites. The biotite granites have SiO2 contents of 70.3-74.4 wt% and are weakly to strongly peraluminous with ASI from 1.00 to 1.26, and show a general decrease in ASI with increasing SiO2. They have relatively high zircon saturation temperatures ( T Zr = 707-817 °C, most > 745 °C) and show a general decrease in T Zr with increasing SiO2. They have high initial 87Sr/86Sr ratios (0.7136 to 0.7166) and high δ18O values (9.1-12.8‰, most > 9.5‰) and clearly negative ɛ Nd (T) (- 9.5 to - 11.8) and ɛ Hf (T) (in situ zircon) (- 13.1 to - 13.5). The muscovite-bearing granites have high SiO2 contents (74.7-78.2 wt%). They are also weakly to strongly peraluminous with ASI of 1.04-1.18 but show a general increase in ASI with increasing SiO2. They have relatively low T Zr (671-764 °C, most 9.5‰) and ɛ Hf (T) (in situ zircon) of - 11.3 to - 13.1. Geochemical data suggest the origin of the biotite granites and muscovite-bearing granites as follows: Partial melting of Precambrian metasedimentary rocks (mainly two-mica schist) in the lower crust at temperatures of ca

  6. 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

  7. Mineral equilibria and zircon, garnet and titanite U-Pb ages constraining the PTt path of granite-related hydrothermal systems at the Big Bell gold deposit, Western Australia

    Science.gov (United States)

    Mueller, Andreas G.; McNaughton, Neal J.

    2018-01-01

    The Big Bell deposit (75 t gold) is located in a narrow spur of the Meekatharra greenstone belt, Yilgarn Craton, Western Australia. Two ore bodies are located in a calcic-potassic contact alteration zone overprinting lineated granodiorite dykes and amphibolite: almandine-cummingtonite-hornblende skarn (1-3 g/t Au, 1700 g/t As, 330 g/t W) and the muscovite-microcline gneiss (3-5 g/t Au, 580 g/t Sb, 620 g/t W) of the Main Lode. Genetic models vary from pre- to post-metamorphic replacement. Hornblende-plagioclase pairs in amphibolite constrain peak metamorphic temperature to 670 ± 50 °C. In contrast, garnet-biotite thermometry provides estimates of 578 ± 50 and 608 ± 50 °C for garnet-cordierite-biotite schist bordering the skarn and enveloping the Main Lode. Garnet-cordierite and garnet-hornblende pairs extend the range of fluid temperature to 540 ± 65 °C, well below peak metamorphic temperature. At 540-600 °C, the alteration assemblage andalusite + sillimanite constrains pressure to 300-400 MPa corresponding to 11-14 km crustal depth. Published U-Pb ages indicate that metamorphism took place in the aureole of the southeast granodiorite-tonalite batholith (2740-2700 Ma), followed by gold mineralization at 2662 ± 5 Ma and by the emplacement of biotite granite and Sn-Ta-Nb granite-pegmatite dykes at 2625-2610 Ma. Amphibolite xenoliths in granite northwest of the deposit record the lowest temperature (628 ± 50 °C), suggesting it lacks a metamorphic aureole. The rare metal dykes are spatially associated with epidote-albite and andradite-diopside skarns (≤1.5 g/t Au), mined where enriched in the weathered zone. We analysed hydrothermal zircon intergrown with andradite. Concordant U-Pb ages of 2612 ± 7 and 2609 ± 10 Ma confirm the presence of a second granite-related system. The zircons display oscillatory zoning and have low Th/U ratios (0.05-0.08). Low-Th titanite from an albite granite dyke has a concordant but reset U-Pb age of 2577 ± 7 Ma.

  8. Geochemical evolution of magmatism in Archean granite-greenstone terrains

    Science.gov (United States)

    Samsonov, A. V.; Larionova, Yu. O.

    2006-05-01

    Evolution of Archean magmatism is one of the key problems concerning the early formation stages of the Earth crust and biosphere, because that evolution exactly controlled variable concentrations of chemical elements in the World Ocean, which are important for metabolism. Geochemical evolution of magmatism between 3.5 and 2.7 Ga is considered based on database characterizing volcanic and intrusive rock complexes of granite-greenstone terrains (GGT) studied most comprehensively in the Karelian (2.9-2.7 Ga) and Kaapvaal (3.5-2.9 Ga) cratons and in the Pilbara block (3.5-2.9 Ga). Trends of magmatic geochemical evolution in the mentioned GGTs were similar in general. At the early stage of their development, tholeiitic magmas were considerably enriched in chalcophile and siderophile elements Fe2O3, MgO, Cr, Ni, Co, V, Cu, and Zn. At the next stage, calc-alkaline volcanics of greenstone belts and syntectonic TTG granitoids were enriched in lithophile elements Rb, Cs, Ba, Th, U, Pb, Nb, La, Sr, Be and others. Elevated concentrations of both the “crustal” and “mantle-derived” elements represented a distinctive feature of predominantly intrusive rocks of granitoid composition, which were characteristic of the terminal stage of continental crust formation in the GGTs, because older silicic rocks and lithospheric mantle were jointly involved into processes of magma generation. On the other hand, the GGTs different in age reveal specific trends in geochemical evolution of rock associations close in composition and geological position. First, the geochemical cycle of GGT evolution was of a longer duration in the Paleoarchean than in the Meso-and Neoarchean. Second, the Paleoarche an tholeiitic associations had higher concentrations of LREE and HFSE (Zr, Ti, Th, Nb, Ta, Hf) than their Meso-and Neoarchean counterparts. Third, the Y and Yb concentrations in Paleoarchean calc-alkaline rock associations are systematically higher than in Neoarchean rocks of the same type

  9. Structural and metamorphic evolution of the Turku migmatite complex, southwestern Finland

    Directory of Open Access Journals (Sweden)

    Väisänen, M.

    1999-06-01

    Full Text Available The Turku migmatite complex in southwestern Finland is a representative area for the type of tectonic and metamorphic evolution seen within the Palaeoproterozoic Svecofennian Orogen in southern Finland. The orogeny can be divided into early, late and postorogenic stages. The early orogenic structural evolution of the crust is expressed by a D1/D2 deformation recorded as bedding-parallel S1 mica foliation deformed by tight to isoclinal D2 folds with subhorizontal axial planes and a penetrative S2 axial plane foliation. Syntectonic ca. 1890-1870 Ma tonalites were emplaced during D2 as sheet intrusions. This deformation is attributed to thrust tectonics and thickening of the crust. The late orogenic structural evolution produced the main D3 folding, which transposed previous structures into a NE-SW trend. The doubly plunging fold axis produced dome-and-basin structures. The attitude of the F3 folds varies from upright or slightly overturned to locally recumbent towards the NW. Granite dikes were intruded along S3 axial planes. Large D3 fold limbs are often strongly deformed, intensively migmatized and intruded by garnet- and cordierite-bearing granites. These observations suggest that these potassium-rich granites, dated at 1840-1830 Ma, were emplaced during D3. This late orogenic NW-SE crustal shortening further contributed to crustal thickening. Subvertical D4 shear zones that cut all previous rock types possibly controlled the emplacement of postorogenic granitoids. Steeply plunging lineations on D4 shear planes suggest vertical displacements during a regional uplift stage. Metamorphic grade increases from cordierite-sillimanite-K-feldspar gneisses in the northwest and from muscovite-quartz±andalusite rocks in the southeast to high-temperature granulite facies migmatites in the middle of the study area. Block movements during D4 caused the observed differences in metamorphic grade. Garnet and cordierite are mostly breakdown products of biotite

  10. Gamma-spectrometric surveys in differentiated granites. I: a review of the method and of the geochemical behavior of K, Th and U

    International Nuclear Information System (INIS)

    Ulbrich, Horstpeter Herberto Gustavo Jose; Ulbrich, Mabel Norma Costas; Guimaraes, Gilson Burigo

    2009-01-01

    This contribution is part of a research project on the Neo proterozoic Cunhaporanga Granitic Complex (CGC), cropping out in the Ponta Grossa Arch (Parana state, SE Brazil). An initial study used the gamma-spectrometric data of the Serra do Mar Sul Aero geophysical Project, performed during the 70's for CPRM. Later, terrestrial gamma-spectrometric surveys focused on the study of the differentiated Joaquim Murtinho Granite (JMG) in the NW corner of CGC, and the Serra do Carambei Granite, to the SW. In this paper, the results obtained for JMG are presented in two parts. The first deals with methodology and the presentation of several gamma-spectrometric 'color-scale' maps, indicating that results obtained in granites depend strongly on a climatic factor, given the mobility of K during weathering in subtropical climates with strong rainfalls, also favoring a greater mobility of U. Minerals that are U and Th hosts, documented in granites, are reviewed, together with the weathering processes that control the mobility of K, U and Th in soils. Strong K signals in granitic areas submitted to these climates document the presence of fresh rock and/or effects of hydrothermal alteration, while weak or nil signals are evidence of strong leaching of K during weathering. U and Th will be retained in the residual soils, in part leading to their selective enrichment, also coupled with soil migration to lower topographic levels by colluvial transport. The larger solubility of U (as uranyl ion) allows its liberation under oxidizing conditions, and its migration, limited by the possibility of absorption in newly formed mineral and organic soil phases. Th should be retained almost totally in resistant phases and, when liberated in solution, will mostly be fixed in organic and inorganic soil substances. (author)

  11. 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

  12. Smolt Monitoring at the Head of Lower Granite Reservoir and Lower Granite Dam, 1997 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Edwin W.; Nelson, William R.

    1999-04-01

    This project monitored the daily passage of chinook salmon Oncorhynchus tshawytscha and steelhead trout O. mykiss smolts during the 1997 spring out-migration at migrant traps on the Snake River and Salmon River. All hatchery chinook salmon released above Lower Granite Dam were marked with a fin clip in 1997. Total annual hatchery chinook salmon catch at the Snake River trap was 49% of the 1996 number but only 6% of the 1995 catch. The wild chinook catch was 77% of the 1996 but was only 13% of 1995. Hatchery steelhead trout catch was 18% of 1996 numbers but only 7% of the 1995 numbers. Wild steelhead trout catch was 22% of 1996 but only 11% of the 1995 numbers. The Snake River trap collected eight age-0 chinook salmon and one sockeye/kokanee salmon O. nerka. 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 high flows. Trap operations were terminated for the season due to high flows and trap damage on May 8 and were out of operation for 23 d due to high flow and debris. Hatchery chinook salmon catch at the Salmon River trap was 37% and wild chinook salmon catch was 60% of 1996 numbers but only 5% and 11% of 1995 catch, respectively. The 1997 hatchery steelhead trout collection was 13% of the 1996 catch and 32% of the 1995 numbers. Wild steelhead trout collection in 1997 was 21% of the 1996 catch and 13% of the 1995 numbers. Trap operations were terminated for the season due to high flows and trap damage on May 7 and were out of operation for 19 d due to high flow and debris.

  13. Smolt Monitoring at the Head of Lower Granite Reservoir and Lower Granite Dam, 1999 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Edwin W.; Brimmer, Arnold F.; Putnam, Scott A.

    2001-06-01

    This project monitored the daily passage of chinook salmon Oncorhynchus tshawytscha, steelhead trout O. mykiss, and sockeye salmon smolts O. nerka during the 1999 spring out-migration at migrant traps on the Snake River and Salmon River. All hatchery chinook salmon released above Lower Granite Dam were marked with a fin clip in 1999. Total annual hatchery chinook salmon catch at the Snake River trap was 440% of the 1998 number. The wild chinook catch was 603% of the previous year's catch. Hatchery steelhead trout catch was 93% of 1998 numbers. Wild steelhead trout catch was 68% of 1998 numbers. The Snake River trap collected 62 age-0 chinook salmon. During 1998 the Snake River trap captured 173 hatchery and 37 wild/natural sockeye salmon and 130 hatchery coho salmon O. kisutch. 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 high flows. Trap operations began on March 14 and were terminated for the season due to high flows on May 25. The trap was out of operation for 18 d during the season due to high flow and debris. Hatchery chinook salmon catch at the Salmon River trap was 214%, and wild chinook salmon catch was 384% of 1998 numbers. The hatchery steelhead trout collection in 1999 was 210% of the 1998 numbers. Wild steelhead trout collection in 1999 was 203% of the 1998 catch. Trap operations began on March 14 and were terminated for the season due to high flows on May 21. The trap was out of operation for 17 d during the season due to high flow and debris.

  14. The Paleoproterozoic Nattanen-type granites in northern Finland and vicinity – a postcollisional oxidized A-type suite

    Directory of Open Access Journals (Sweden)

    Esa Heilimo

    2009-06-01

    Full Text Available The ~1.8 Ga Nattanen-type granites in the Finnish Lapland and western Kola Peninsula are found as several relatively small, high-level, discordant plutons that are easily discernible as weak maxima on aeromagnetic maps. We present U–Pb mineral isotope data on the Finnishplutons. The concordia ages are in the 1.79−1.77 Ga range and there is little evidence for inheritance. Initial radiogenic isotope compositions (our common-Pb data combined with previously published whole-rock Nd and Hf data imply a major, yet varying, Archeansource component. Elemental geochemical data on five Finnish intrusions (the Nattanen stock, the Tepasto and Pomovaara complexes, the Riestovaara and Vainospää batholiths, as well as associated dyke rocks allow the Nattanen-type granites to be classified as oxidizedA-type granites. Their petrogenesis may be related to partial melting of the lower crust by mafic underplating (extensional setting or as a result of thermal relaxation in thickened crustal setting.

  15. Propellant Preparation Laboratory Complex (Area1-21)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: Area 1-21 is an explosion resistant complex of nine cells built into the side of a granite ridge. Three solid propellant cutting cells are housed in the...

  16. Failure of Sierra White granite under general states of stress

    Science.gov (United States)

    Ingraham, M. D.; Dewers, T. A.; Lee, M.; Holdman, O.; Cheung, C.; Haimson, B. C.

    2017-12-01

    The effect of the intermediate principal stress on the failure of Sierra White granite was investigated by performing tests under true triaxial states of stress. Tests were performed under constant Lode angle conditions with Lode angles ranging from 0 to 30°, pure shear to axisymmetric compression. Results show that the failure of Sierra White granite is heavily dependent on the intermediate principal stress which became more dramatic as the mean stress increased. An analysis of the shear bands formed at failure was performed using an associated flow rule and the Rudnicki and Rice (1975) localization criteria. The localization analysis showed excellent agreement with experimental results. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525.

  17. Quantized Ultracold Neutrons in Rough Waveguides: GRANIT Experiments and Beyond

    Directory of Open Access Journals (Sweden)

    M. Escobar

    2014-01-01

    Full Text Available We apply our general theory of transport in systems with random rough boundaries to gravitationally quantized ultracold neutrons in rough waveguides as in GRANIT experiments (ILL, Grenoble. We consider waveguides with roughness in both two and one dimensions (2D and 1D. In the biased diffusion approximation the depletion times for the gravitational quantum states can be easily expressed via each other irrespective of the system parameters. The calculation of the exit neutron count reduces to evaluation of a single constant which contains a complicated integral of the correlation function of surface roughness. In the case of 1D roughness (random grating this constant is calculated analytically for common types of the correlation functions. The results obey simple scaling relations which are slightly different in 1D and 2D. We predict the exit neutron count for the new GRANIT cell.

  18. 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.

  19. 1997 Lower Granite dam smolt monitoring program : annual report.; ANNUAL

    International Nuclear Information System (INIS)

    Morrill, Charles; Ross, Doug; Verhey, Peter; Witalis, Shirley

    1997-01-01

    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

  20. Static and kinetic friction of granite at high normal stress

    Science.gov (United States)

    Byerlee, J.D.

    1970-01-01

    Frictional sliding on ground surfaces of granite, angle of sliding planes 30?? and 45??, was investigated as a function of confining pressure. Over the normal stress range of 2-12 kb, the static frictional shear stress ??s follows the relationship ??s = 0??5 + 0?? ??n and the kinetic frictional shear stress ??k was calculated to be ??k = 0??25 + 0??47 ??n. ?? 1970.

  1. Heat transfer experiment in a granite formation at Cornwall

    International Nuclear Information System (INIS)

    Bourke, P.J.; Hodgkinson, D.P.

    1985-01-01

    An experiment simulating a waste package was started in 1978 in Cornish granite. To obtain measurable temperature rises through large volumes of rock, an electrical heater at 50m depth was run for four years. The heater was then switched off and the cooling was monitored for another year. The results show that most of the heat transfer was by conduction but that some convection occurred and that temperatures can be predicted with some confidence

  2. Lower Granite dam smolt monitoring program: annual report, 2000; ANNUAL

    International Nuclear Information System (INIS)

    Morrill, Charles

    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)

  3. Study of natural radioactivity in Mansehra granite, Pakistan: environmental concerns

    International Nuclear Information System (INIS)

    Qureshi, Aziz Ahmed; Manzoor, Shahid; Waheed, Abdul; Tubassam, Aneela; Khan Jadoon, Ishtiaq Ahmed; Wajid, Ali Abbas; Attique, Ahsan; Masood, Adil; Anees, Muhammad

    2014-01-01

    A part of Mansehra Granite was selected for the assessment of radiological hazards. The average activity concentrations of 226 Ra, 232 Th and 40 K were found to be 27.32, 50.07 and 953.10 Bq kg -1 , respectively. These values are in the median range when compared with the granites around the world. Radiological hazard indices and annual effective doses were estimated. All of these indices were found to be within the criterion limits except outdoor external dose (82.38 nGy h -1 ) and indoor external dose (156.04 nGy h -1 ), which are higher than the world's average background levels of 51 and 55 nGy h -1 , respectively. These values correspond to an average annual effective dose of 0.867 mSv y -1 , which is less than the criterion limit of 1 mSv y -1 (ICRP-103). Some localities in the Mansehra city have annual effective dose higher than the limit of 1 mSv y -1 . Overall, the Mansehra Granite does not pose any significant radiological health hazard in the outdoor or indoor. (authors)

  4. Geochronology and geochemistry of upper proterozoic granites from Southern Benin

    International Nuclear Information System (INIS)

    Cordani, U.G.; Kawashita, K.; Vancini, K.R.B.; Cadoppi, P.; Sacchi, R.

    1993-01-01

    The Upper Proterozoic basement of Benin, like that of nearby Nigeria and like the polycyclic basement of Central Hoggar, belongs to the hinterland of the Pharusian Chain (Pan-African Trans-Saharan Belt) generated by the collision between the (passive) margin of the West African craton and the (reactivated) margin of the Tuareg Shield and its southern extension. Rb-Sr dating of sub alkaline, meta-aluminums, syn-Kinematic granite forming tabular bodies near Dassa-Zoume and near Save yielded two WR isochron ages of 650 ± 35 Ma (I.R. = 0.7043) and 705 ± 70 Ma (I.R. = 0.7045). Emplacement of these bodies was clearly controlled by trans current movements along the Kandi Fault System. The analyzed granites are comparable with those of Central Hoggar and North-Central Nigeria on the ground of field, geochronological and geochemical data; they also display some affinities with the late-tectonic granites of the Adrar des Iforas. They are expected to find their Brazilian continuation in the Chaval Granitoids west of Fortaleza, but data for comparison are inadequate. (author)

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

    Science.gov (United States)

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

    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.

  6. Continental vertical growth in the transitional zone between South Tianshan and Tarim, western Xinjiang, NW China: Insight from the Permian Halajun A1-type granitic magmatism

    Science.gov (United States)

    Huang, He; Zhang, Zhaochong; Kusky, Timothy; Santosh, M.; Zhang, Shu; Zhang, Dongyang; Liu, Junlai; Zhao, Zhidan

    2012-12-01

    The South Tianshan Collisional Belt (STCB) and northern margin of the Tarim Block (NTB) are key areas for understanding the prolonged tectonic evolution of the Central Asian Orogenic Belt (CAOB). The Halajun region in Xinjiang province, NW China is located within the tectonic transition zone between STCB and Tarim Blocks. Several granitic intrusions and one mafic-ultramafic complex (Piqiang complex) are exposed in this region. Zircon U-Pb dating, whole-rock major oxide, trace element and Nd isotopic data are presented for the Huoshibulake, Tamu, Kezi'ertuo and Halajun II granitic intrusions in this area. New LA-ICP-MS U-Pb age for Kezi'ertuo intrusion, coupled with previously published SHIRMP U-Pb ages for Huoshibulake and Halajun II intrusions and Piqiang complex, reveals that all the igneous rocks in the Halajun region are coeval (~ 275 Ma). Geochemically, the four granitic intrusions show high contents of SiO2, K2O and total alkalis and possess trace element patterns characterized by Rb, Nb, Ta, Zr and Hf enrichment and significantly negative Ba, Sr, P, Eu and Ti anomalies. These features strongly favor an A1-type affinity for the Halajun granitic intrusions. Among the four intrusions, the Kezi'ertuo, Tamu and Halajun II intrusions possess positive to slightly negative ɛNd(t) values ranging from - 0.9 to + 0.6, whereas the Huoshibulake intrusion displays less depleted ɛNd(t) values of - 2.6 to - 2.9. Our new elemental and isotopic data suggest that the four granitic intrusions were generated by the partial melting of a common Neoproterozoic gabbroic source, probably as a result of the ~ 275 Ma underplating of the asthenosphere mantle-derived magmas. The variable involvement of the mantle components accounts for the range of ɛNd(t) values. After the generation of the parental magma, alkali feldspar, arfvedsonite, biotite, Fe-Ti oxides and zircon seem to have fractionated prior to the final emplacement of the granitic magmas. In combination with the regional

  7. Smolt Monitoring at the Head of Lower Granite Reservoir and Lower Granite Dam, 1992 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, Edwin W.; Brimmer, Arnold F.

    1993-11-01

    This project monitored the daily passage of chinook salmon Oncorhynchus tshawytscha and steelhead trout 0. mykiss smolts during the 1992 spring outmigration at migrant traps on the Snake River and the Clearwater River. Annual chinook salmon catch at the Snake River trap was the second lowest since the beginning of this project. The low trap catch wall due to extremely poor trap efficiency associated with severe low flows. Hatchery steelhead trout catch was similar to 1988 through 1991. Wild steelhead trout catch was 35% less than in 1991. Operations at the Snake River trap and a new screw trap were extended through the end of July to collect summer-migrating age-0 chinook. The differentiation of age-0 chinook from spring and Bummer chinook (age-1) using physical characteristics was again employed in 1992. The Snake River trap and the screw trap collected 20 and 18 age-0 chinook salmon, respectively, due to extremely low discharge. Chinook salmon catch at the Clearwater River trap was the highest since trap operation began in 1984. Hatchery steelhead trout trap catch was 23% lower than in 1991. Wild steelhead trout trap catch wall the highest since trap operation began. Fish tagged with Passive Integrated Transponder (PIT) tags at the Snake River trap were interrogated at three dams with PIT-tag detection systems (Lower Granite, Little Goose, and McNary dams). Cumulative interrogation, for fish marked at the Snake River trap, was not calculated for chinook salmon due to a lack of data over the entire migration season. The rates for hatchery steelhead trout and wild steelhead trout were 44.9% and 72.9% respectively. Cumulative interrogation at the three dams for fish PIT-tagged at the Clearwater River trap was 55.1% for chinook salmon, 60.4% for hatchery steelhead trout, and 73.1% for wild steelhead trout. Cumulative interrogations for hatchery steelhead tagged at the Snake River trap and recovered at the downstream dams was about 50% less than in previous years.

  8. Zircon and monazite geochronology of the granulites and associated gneisses from the Rengali Province, India: Growth of the southern margin of the Singhbhum Craton

    Science.gov (United States)

    Bose, S.; Das, K.; Kimura, K.; Hayasaka, Y.; Hidaka, H.; Dasgupta, A.; Ghosh, G.; Mukhopadhyay, J.

    2013-12-01

    Geological evidences show that cratons grew in size by multiple orogenic cycles which can best be studied in their marginal orogenic belts. Rengali Province, occurring at the southern margin of the Singhbhum Craton, India is one such belt, characterized by low- to high-grade metamorphic signatures. This is sharply different from the virtually unmetamorphosed cratonic rocks in north and ultrahigh temperature metamorphosed rocks of the Eastern Ghats Province in south. High-grade gneisses and granitoids (including charnockite) constitute the central highland of this province. Several large-scale faults and shear zones juxtapose rocks of contrasting metamorphic grades. Our geochronological investigation from samples of high-grade orthogneiss and paragneiss along with the intrusive granitoids from central and eastern part of the Rengali Province using zircon (SHRIMP) and monazite chemical techniques reveal a complex evolutionary history. Zircon grains of the metapelitic granulites from the eastern segment yield detrital ages in the time span of ca. 3528-3087 Ma, without perceptible evidence of subsequent metamorphism. In contrast, monazite grains from the same samples record strong metamorphic signature at ca. 2.8-2.7 Ga along with inherited populations of ca. 3.0-2.9 Ga. Charnockite from the eastern segment has protolith age of 3058×15 Ma while that from the central segment records high-grade metamorphism at 2818×15 Ma. Mafic granulite from the central segment preserves the oldest core age of 2844×7 Ma. Synkinematic leucogranite in the central and undeformed granitoid in the eastern segment were emplaced at 2807×13 Ma and 2809×13 Ma respectively. Most of the samples show zircon overgrowth at ca. 2500 Ma, which possibly caused by a separate tectonothermal overprinting. From the available geochronological data, we postulate the existence of marine basin which opened at ca. 3050 Ma, received sediments from the adjacent cratonic hinterland, switched to an active

  9. Exhumation And Evolution Of Al-Taif Metamorphic Core Complex (Western Arabian Shield) During Dextral Transpressional Regime

    Science.gov (United States)

    El-Fakharani, Abdelhamid; El-Shafei, Mohamed; Hamimi, Zakaria

    2013-04-01

    Al-Taif metamorphic belt is a NE-trending belt decorating steeply dipping major transpressional shear zone in western central Arabian Shield. It comprises gneisses and migmatites that were syn-kinematically invaded under relatively high-grade metamorphic conditions by voluminous granitic bodies and a confluence of pegmatitic veins. Field mapping and outcrop investigation reveal that the belt was evolved during at least three Neoproterozoic deformations (D1-D3). D1 and D2 were progressive deformations, took place during a contractional regime, and resulted in SW-mildly plunging isoclinal folds, superimposed by NE- gently to moderately plunging folds. The prevailed tectonic regime during D3was primordially plastic, accompanied with a NE-oriented oblique shearing that was subsequently evolved as semi ductile-semi brittle shearing during an episode of exhumation. Mesoscopic kinematic indicators, as well as microstructural analysis of the collected rock samples, reflect dextral sense of shearing. Such style of shearing is most probably the conjugate trend of the NNW- to NW- oriented sinistral Najd Fault System. Various cross cutting structures and overprinting relations were detected at both the outcrop- and microscopic scales, including; ductile S2folia with ESE-plunging amphibole mineral lineations; narrow, steeply dipping ductile D2 shear zones; and semi brittle to brittle fault zones. S-C' fabrics, asymmetric strain shadows around porphyroclasts and drag fault indicate a top-to-the-NE sense of shear for most structures. The geometry and style of deformation, together with map pattern highlighted in this study attest a simple shear rotational strain origin for the domed mylonitic foliation (S1) and mineral elongation lineation (L1). This result is in congruent with the landform pattern recorded in the inner parts of the metamorphic core complexes.

  10. 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.

  11. 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.

  12. Elastic anisotropy of Tambo gneiss from Promontogno, Switzerland: a comparison of crystal orientation and microstructure-based modelling 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.

    2017-04-01

    Felsic and mafic gneisses constitute large proportions of the upper and lower continental crust. Gneisses often display 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.

  13. Petrography and geochemistry of the topaz-bearing granite stocks in Artjärvi and Sääskjärvi, western margin of the Wiborg rapakivi granite batholith

    Directory of Open Access Journals (Sweden)

    Sari Lukkari

    2002-01-01

    Full Text Available The Artjärvi and Sääskjärvi granite stocks at the western margin of the Wiborg rapakivi batholith are multiphase rapakivi granite intrusions in which the most evolved phase is topaz-bearing granite. The Artjärvi stock is composed of porphyritic and even-grained biotite granite and even-grained topaz granite, and the Sääskjärvi stock comprises even-grained biotite granite and porphyritic topazgranite. The granites are metaluminous to peraluminous A-type granites, showing within-plate (WPG geochemical characteristics. The topaz granites from the Artjärvi and Sääskjärvi stocks are petrographically and geochemically similar to other topaz-bearing rapakivi granites in Finland. The anomalous geochemistry of the topaz granite is essentially magmatic; postmagmatic reactions have only slightly modified its composition. Greisen veins, some of which are mineralized, are widely found associated with the Artjärvi and Sääskjärvi stocks.The most characteristic feature of the Artjärvi granite stock is a stockscheider at the roof contact of the topaz granite. The stockscheider is composed of schlieren layering and pegmatite layers parallel to the contact. The most probable mechanism for the formation of the schlieren layering is velocity-gradient sorting parallel to the flow, which led to accumulation of mafic minerals along the upper contact of the topaz granite. Cooling and contraction of the topaz granite formed fractures parallel to the roof contact and the residual pegmatite magmas were injected along the fractures forming pegmatite layers. Textures like graphic intergrowths, aplitic groundmass and fan-shaped alkali feldspar crystals associated with the Artjärvi porphyritic biotite granite and pegmatite indicatecrystallization from undercooled magma. Miarolitic cavities found in the porphyritic biotite granite and topaz granite indicate at least local volatile saturation.

  14. Critical element ratio maps of granitic terrains for exploration of atomic minerals

    International Nuclear Information System (INIS)

    Viswanathan, S.; Singh, Yamuna

    2010-01-01

    The paper proposes a new type of geochemical map, named the 'Critical Element Ratio Map', involving K/Rb, Ba/Rb, and Rb/Sr ratios, to aid exploration programmes for atomic minerals in granitic terrains. Granitic rocks formed from highly evolved melts are favourable for hosting ore deposits of U, Th, Li, Be, Nb, Ta, Y, the rare-earth elements (REEs), Sn, W, and Cs. The characteristic geochemical features of this type of granite are low K/Rb and Ba/Rb ratios and high Rb/Sr ratios. The average K/Rb, Ba/Rb, and Rb/Sr ratios of high-calcium granitic rocks (tonalites, granodiorites, and leucogranodiorites) are 229, 8.18, and 0.25, and those for low-calcium granitic rocks (adamellites, granites, leucogranites, and alaskites) are 247, 2.35, and 1.70, respectively. In sharp contrast, the K/Rb, Ba/Rb, and Rb/Sr ratios of granitic rocks formed from highly evolved melts will be less than 100, less than 0.25, and more than 5, respectively. The paper also describes a simple, accurate, precise, rapid, and non-destructive method for determining K, Rb, Sr, and in granitic rocks by wavelength-dispersive X-ray fluorescence spectrometry (WDXRFS) and outlines the methodology for preparing 'Critical Element Ratio Maps' of granitic terrains. granite-hosted 'Rossing-Type' of uranium ore deposits are to be discovered in India, it will be possible only by launching an intensive programme for preparing 'Critical Element Ratio Maps' to identify granitic bodies characterized anomalously low K/Rb and Ba/Rb ratios and high Rb/Sr ratios within the large granitic terrains of Peninsular and Extra-Peninsular India. (author)

  15. New data on the age and nature of the Khan-Bogd alkaline granites, Mongolia

    Science.gov (United States)

    Gerdes, A.; Kogarko, L. N.; Vladykin, N. V.

    2017-11-01

    New age dating (291 Ma) was obtained for one of the largest alkaline granite massifs in the world, the Khan-Bogd Massif (Mongolia). For the first time, apart from zircon, other zirconium silicates, elpidite and armstrongite, have been analyzed. Our determinations showed the highly depleted nature of the mantle sources of granites with ɛNd = 12. All the studied Zr-silicates demonstrate positive Eu anomalies in the REE patterns, which indicate a low oxidation potential during alkaline granite formation.

  16. Geology of the Pan-African basement Complex in Ube-Wulko area ...

    African Journals Online (AJOL)

    The Ube-Wulko area of southeast Akwanga falls within the Pan-African remobilized Basement Complex of northcentral Nigeria. It consists of intensely multi-deformed high grade polymetamorphic basement rocks, predominantly composed of migmatitic gneisses and schists and subordinate quartzites, marbles, and ...

  17. Magmatic and crustal differentiation history of granitic rocks from Hf-O isotopes in zircon.

    Science.gov (United States)

    Kemp, A I S; Hawkesworth, C J; Foster, G L; Paterson, B A; Woodhead, J D; Hergt, J M; Gray, C M; Whitehouse, M J

    2007-02-16

    Granitic plutonism is the principal agent of crustal differentiation, but linking granite emplacement to crust formation requires knowledge of the magmatic evolution, which is notoriously difficult to reconstruct from bulk rock compositions. We unlocked the plutonic archive through hafnium (Hf) and oxygen (O) isotope analysis of zoned zircon crystals from the classic hornblende-bearing (I-type) granites of eastern Australia. This granite type forms by the reworking of sedimentary materials by mantle-like magmas instead of by remelting ancient metamorphosed igneous rocks as widely believed. I-type magmatism thus drives the coupled growth and differentiation of continental crust.

  18. 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

  19. Evolution of zircons from postorogenic intrusive series with Li-F granites, Russian Far East

    Science.gov (United States)

    Alekseev, V. I.; Polyakova, E. V.; Machevariani, M. M.; Marin, Yu. B.

    2014-12-01

    The paper discusses the morphology, anatomy, and geochemistry of zircons from granitic rocks of postorogenic intrusive series with Li-F granites in the Russian Far East. The multiphase Upper Urmi pluton in the Amur region and the Severny pluton in the Chukchi Peninsula have been chosen as reference objects. The directed variations of zircon morphology and geochemistry in the history of Pacific postorogenic granitic magmatism reflect decrease in depth of magma generation and crystallization temperature along with an increase in alkalinity, fluid saturation, and rare-metal potential of granitic melts.

  20. Genetic Affiliation of Gold and Uranium Mineralization in El-Missikat Granite, Central Eastern Desert, Egypt

    International Nuclear Information System (INIS)

    Ammar, F.A.; Omar, S.A.M.; El Sawey, El.H.

    2016-01-01

    Gabal El-Missikat granitic pluton is affected by two fault systems trending NW-SE (the oldest) and ENE-WSW directions. It is one of the uranium occurrences in the Eastern Desert of Egypt. The northwestern margins of El-Missikat pluton, along its contact with the gneissose quartz diorite, are dissected by numerous reactivated fractured shear zones running generally ENE-WSW to NE-SW and dipping about 60°-70° to SE. Many white (oldest), smoky or black and jasperoid (youngest) silica veinlets fill the fractures of these shear zones. These veins are of irregular shape and variable thickness ranging from few centimeters to about three meters. They are chiefly affected by silicification, sericitization, hematitization , kaolinization and hydrothermal alterations processes. The smoky black veins are hosting secondary uranium and fluorite-, sulphide-gold mineralizations. Polished surface studies, ICP-ES and Atomic Absorption as well as Scanning Electron Microscope measurements recorded galena, pyrite chalcopyrite, sphalerite and molybdenite in the black and jasperoid mineralized veins. Gold associated with ore mineral assemblage as pyrite, chalcopyrite, sphalerite, galena, sheelite and iron oxides. The identified sulphide minerals not bearing gold are recorded. Gold are relatively coarse-grained, massive and metallic yellow or stretched bronze colored particles. The recorded secondary U minerals associates the sulphide gold-mineralization in the black and jasperoid silica veins. Regarding the mobility of both uranium and gold, U 4+ mobilized in oxidizing medium and migrate and transport as U 6+ , then deposited later as U 4+ when the medium changes to be reducing characterized by high /O 2 . On contrary, gold mobilized when the medium is complex AuCl 3- ion bearing. Consequently, El- Missikat granitic pluton affected by oxidizing Au and Cl 3- bearing high temperature hydrothermal solutions that leached U 4+ , W and Mo from the granitic mass as U 6 + , later decrease of

  1. The Seis Lagos Carbonatite Complex

    International Nuclear Information System (INIS)

    Issler, R.S.; Silva, G.G. da.

    1980-01-01

    The Seis Lagos Carbonatite Complex located about 840 Km from Manaus, on the northwestern part of the Estado do Amazonas, Brazil is described. Geological reconnaissance mapping by Radam Project/DNPM, of the southwestern portion of the Guianes Craton, determined three circular features arranged in a north-south trend and outcroping as thick lateritic radioactive hills surrounded by gneisses and mignatites of the peneplained Guianense Complex. Results of core drilling samples analysis of the Seis Lagos Carbonatite Complex are compared with some igneous rocks and limestones of the world on the basis of abundance of their minor and trace elements. Log-log variation diagram of strontium and barium in carbonatite and limestone, exemplifield by South Africa and Angola carbonatites, are compared with the Seis Lagos Carbonatite Complex. The Seis Lagos Carbonatite Complex belongs to the siderite-soevite type. (E.G.) [pt

  2. Ultrasonic evaluation of the physical and mechanical properties of granites.

    Science.gov (United States)

    Vasconcelos, G; Lourenço, P B; Alves, C A S; Pamplona, J

    2008-09-01

    Masonry is the oldest building material that survived until today, being used all over the world and being present in the most impressive historical structures as an evidence of spirit of enterprise of ancient cultures. Conservation, rehabilitation and strengthening of the built heritage and protection of human lives are clear demands of modern societies. In this process, the use of nondestructive methods has become much common in the diagnosis of structural integrity of masonry elements. With respect to the evaluation of the stone condition, the ultrasonic pulse velocity is a simple and economical tool. Thus, the central issue of the present paper concerns the evaluation of the suitability of the ultrasonic pulse velocity method for describing the mechanical and physical properties of granites (range size between 0.1-4.0 mm and 0.3-16.5 mm) and for the assessment of its weathering state. The mechanical properties encompass the compressive and tensile strength and modulus of elasticity, and the physical properties include the density and porosity. For this purpose, measurements of the longitudinal ultrasonic pulse velocity with distinct natural frequency of the transducers were carried out on specimens with different size and shape. A discussion of the factors that induce variations on the ultrasonic velocity is also provided. Additionally, statistical correlations between ultrasonic pulse velocity and mechanical and physical properties of granites are presented and discussed. The major output of the work is the confirmation that ultrasonic pulse velocity can be effectively used as a simple and economical nondestructive method for a preliminary prediction of mechanical and physical properties, as well as a tool for the assessment of the weathering changes of granites that occur during the serviceable life. This is of much interest due to the usual difficulties in removing specimens for mechanical characterization.

  3. Characterization of granite waste for use in red ceramic

    International Nuclear Information System (INIS)

    Aguiar, M.C.; Monteiro, S.N.; Vieira, C.M.F.; Borlini, M.C.

    2011-01-01

    This work aims to study the characterization of the granite waste from the city of Santo Antonio de Padua-RJ for the use in red ceramic. The chemical, physical and morphological characterization of the waste was performed by chemical analysis, X-ray diffraction, particle size distribution, thermal analysis and scanning electron microscopy (SEM). The results indicated that this waste is a material with great potential to be used as a component of ceramic body due to its capacity to act as flux during the firing, and to improve the properties of the ceramic when is incorporate. (author)

  4. Interwell tracer analyses of a hydraulically fractured granitic geothermal reservoir

    International Nuclear Information System (INIS)

    Tester, J.W.; Potter, R.M.; Bivins, R.L.

    1979-01-01

    Field experiments using fluorescent dye and radioactive tracers (Br 82 and I 131 ) have been employed to characterize a hot, low-matrix permeability, hydraulically-fractured granitic reservoir at depths of 2440 to 2960 m (8000 to 9700 ft). Tracer profiles and residence time distributions have been used to delineate changes in the fracture system, particularly in diagnosing pathological flow patterns and in identifying new injection and production zones. The effectiveness of one- and two-dimensional theoretical dispersion models utilizing single and multiple porous, fractured zones with velocity and formation dependent effects are discussed with respect to actual field data

  5. Study of deep fracturation of granitic rock mass. Documentary study

    International Nuclear Information System (INIS)

    Bles, J.L.; Landry, J.

    1984-01-01

    This documentary study realized with the financial support of the European Communities and the CEA aims at the utilization of available data for the understanding of the evolution of natural fractures in granitic rocks from the surface to deep underground. The Mt Blanc road tunnel, the EDF's Arc-Isere gallerie, the Auriat deep borehole and the Pyrenean rock mass of Bassies are studied because detailed structural and geological studies have been realized these last 20 years. In this study are more particularly analyzed the relationship between small fractures and large faults, evolution with depth of fracture density and direction, consequences of rock decompression and relationship between fracturation and groundwater

  6. Underground nuclear explosion effects in granite rock fracturing

    International Nuclear Information System (INIS)

    Derlich, S.

    1970-01-01

    On the Saharan nuclear test site in Hoggar granite, mechanical properties of the altered zones were studied by in situ and laboratory measurements. In situ methods of study are drillings, television, geophysical and permeability measurements. Fracturing is one of the most important nuclear explosion effects. Several altered zones were identified. There are: crushed zone, fractured zone and stressed zone. Collapse of crushed and fractured zone formed the chimney. The extent of each zone can be expressed in terms of yield and of characteristic parameters. Such results are of main interest for industrial uses of underground nuclear explosives in hard rock. (author)

  7. Granite ascent and emplacement during contractional deformation in convergent orogens

    Science.gov (United States)

    Brown, Michael; Solar, Gary S.

    1998-09-01

    Based on a case study in the Central Maine Belt of west-central Maine, U.S.A., it is proposed that crustal-scale shear zone systems provide an effective focussing mechanism for transfer of granite melt through the crust in convergent orogens. During contractional deformation, flow of melt in crustal materials at depths below the brittle-plastic transition is coupled with plastic deformation of these materials. The flow is driven by pressure gradients generated by buoyancy forces and tectonic stresses. Within the oblique-reverse Central Maine Belt shear zone system, stromatic migmatite and concordant to weakly discordant irregular granite sheets occur in zones of higher strain, which suggests percolative flow of melt to form the migmatite leucosomes and viscous flow of melt channelized in sheet-like bodies, possibly along fractures. Cyclic fluctuations of melt pressure may cause instantaneous changes in the effective permeability of the flow network if self-propagating melt-filled tensile and/or dilatant shear fractures are produced due to melt-enhanced embrittlement. Inhomogeneous migmatite and schlieric granite occur in zones of lower strain, which suggests migration of partially-molten material through these zones en masse by granular flow, and channelized flow of melt carrying entrained residue. Founded on the Central Maine Belt case study, we develop a model of melt extraction and ascent using the driving forces, stress conditions and crustal rheologies in convergent, especially transpressive orogens. Ascent of melt becomes inhibited with decreasing depth as the solidus is approached. For intermediate a(H 2O) muscovite-dehydration melting, the water-saturated solidus occurs between 400 and 200 MPa, near the brittle-plastic transition during high- T-low- P metamorphism, where the balance of forces favors (sub-) horizontal fracture propagation. Emplacement of melt may be accommodated by ductile flow and/or stoping of wall rock, and inflation may be accommodated

  8. Characterizing gas permeability and pore properties of Czech granitic rocks

    Czech Academy of Sciences Publication Activity Database

    Konečný, Pavel; Kožušníková, Alena

    2016-01-01

    Roč. 13, č. 4 (2016), s. 331-338 ISSN 1214-9705 R&D Projects: GA ČR GA105/09/0089; GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : granitic rocks * permeability * pore properties Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.699, year: 2016 https://www.irsm.cas.cz/materialy/acta_content/2016_doi/Konecny_AGG_2016_0015.pdf

  9. 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.

  10. Reactive transport model and apparent Kd of Ni in the near field of a HLW repository in granite

    Science.gov (United States)

    Lu, Chuanhe; Samper, Javier; Luis Cormenzana, José; Ma, Hongyun; Montenegro, Luis; Ángel Cuñado, Miguel

    2012-12-01

    Current performance assessment models for radionuclide migration through the near field of high-level radioactive waste repositories often rely on the assumption of a constant Kd for sorption. The validity of such assumption is evaluated here with a reactive transport model for Ni2+ in the near field of a repository in granite. Model results show that Ni2+ sorbs mainly by surface complexation on weak sorption sites. The apparent Kd of Ni2+, Kda, depends on the concentration of dissolved Ni and pH and is constant only when the concentration of dissolved Ni is smaller than 10-6 mol/L. The results of the sensitivity runs show that Kda is sensitive to the water flux at the bentonite-granite interface, the effective diffusion of the bentonite and the concentration of weak sorption sites of the bentonite. The competition of other nuclides such as Cs+ on Ni2+ sorption is not important. Corrosion products, however, affect significantly the sorption of Ni2+ on the bentonite. The model with a constant Kd does not reproduce the release rates of Ni2+ from the bentonite into the granite. A model with a variable Kd which depends on the concentration of dissolved Ni2+ and pH may provide an acceptable surrogate of the multicomponent reactive transport model for the conditions of the repository considered in our model. Simulations using the Kd-approach were performed with GoldSim based on the interpolation in the pH and concentration table, while the reactive transport model simulations were performed with CORE2D which incorporates multisite surface complexation.

  11. Heat production in granitic rocks: Global analysis based on a new data compilation

    Science.gov (United States)

    Artemieva, I. M.; Thybo, H.; Jakobsen, K.; Sørensen, N. K.; Nielsen, L. S. K.

    2017-12-01

    Granitic rocks play special role in the evolution of the Earth and its thermal regime. Their compositional variability provides constraints on global differentiation processes and large scale planetary evolution, while heat production by radioactive decay is among the main heat sources in the Earth. We analyze a new global database GRANITE2017 on the abundances of Th, U, K and heat production in granitic rocks based on all available published data. Statistical analysis of the data shows a huge scatter in all parameters, but the following conclusions can be made. (i) Bulk heat production in granitic rocks of all ages is ca. 2.0 microW/m3 . It is very low in Archean-Early Proterozoic granitic rocks and there is a remarkable peak in Middle Proterozoic granites followed by a gradual decrease towards Cenozoic granites. (ii) There is no systematic correlation between the tectonically controlled granite-type and bulk heat production, although A-type (anorogenic) granites are the most radioactive, and many of them were emplaced in Middle Proterozoic. (iii) There is no systematic correlation between heat flow and concentrations of radiogenic elements. (iv) The present-day global average Th/U value is 4.75 with a maximum in Archean-Early Proterozoic granites (5.75) and a minimum in Middle-Late Proterozoic granites (3.78). The Th/U ratio at the time of granite emplacement has a minimum in Archean (2.78). (v) The present-day K/U ratio is close to a global estimate for the continental crust only for the entire dataset (1460), but differs from the global ratio for each geological time. (vi) We recognize a sharp change in radiogenic concentrations and ratios from the Early Proterozoic to Middle Proterozoic granites. The Proterozoic anomaly may be caused by major plate reorganizations possibly related to the supercontinent cycle when changes in the granite forming processes may be expected, or it may even indicate a change in global thermal regime, mantle dynamics and plate

  12. Modelling mid-crustal migmatite terrains as feeder zones for granite plutons: the competing dynamics of melt transfer by bulk versus porous flow

    OpenAIRE

    Olsen, Sakiko N.; Marsh, Bruce D.; Baumgartner, Lukas P.

    2017-01-01

    The common association of mid-crustal migmatites with an upper-level granite pluton could indicate that the migmatites are a feeder zone for the pluton. If magma from a deeper level pervasively intrudes a high temperature metamorphic complex, most of the intruded magma would not freeze because of the prevailing temperature. The interaction between the magma and country rocks, which could include partial melting and crystallisation of the magma passing through, would modify magma to a more gra...

  13. Hydrothermal alterations as natural analogues of radionuclide migration in granitic rocks

    International Nuclear Information System (INIS)

    Piantone, P.

    1989-01-01

    The document is the final report of the project Hydrothermal alteration systems as analogues of nuclear waste repositories in granitic rocks which was the subject of contract n 0 F1 1 W/0072-F (CD) performed at shared cost between the Bureau de Recherches Geologiques et Minieres (BRGM), the Commissariat a l'Energie Atomique and the Commission of the European Communities as part of the MIRAGE programme. This study is the continuation of a preliminary study made by BRGM in 1986 and which concerned the same programme. The data given in this report were obtained from the study of the infilling and hydrothermalized walls of a mineralized vein located at Fombillou, Lot Department, in the French Massif Central. A satisfactory model of the processes generated by hydrothermal alteration then by climatic weathering such as formation of new minerals, flow of elements and variations in volume, was thus built. The mobility of elements displaying physical and chemical properties similar to those of radionuclides present in high-level radioactive waste was studied. A preliminary thermodynamic simulation of mineral transformations and transfers of matter during hydrothermal alteration was performed using the calculation code CEQCSY (Chemical EQuilibrium in Complex SYstem). This simulation is based on the values of the main physical and chemical parameters deduced from the analysis of the natural system. On the basis of the results obtained from Fombillou, an appraisal was made of the response of the granitic environment which has been disturbed by a hydrothermal system produced by heat emitted by the storage of high-level radio-active waste as well as its potential capacities of retention in case of possible leakage

  14. Investigation of the influence of lineaments, lineament intersections and geology on groundwater yield in the basement complex terrain of Ondo State, Southwestern Nigeria

    Science.gov (United States)

    Akinluyi, Francis O.; Olorunfemi, Martins O.; Bayowa, Oyelowo G.

    2018-03-01

    The influence of lineaments, lineament intersections and geology on the groundwater yield of the basement terrain of Ondo State was investigated using optical remote sensing data, Aster DEM, geology, and borehole yield data. Landsat-7 ETM+ and Aster DEM were processed to generate composite lineament map. The study area was traversed by five (5) main lineament populations trending N-S, NE-SW, E-W, ENE-WSW, NNW-SSE. Boreholes sited on lineament exhibited a yield range of between 0.8 and 1.28 l/s with an average yield of 1.04 l/s. Boreholes sited close to lineament gave groundwater yield values of between 0.5 and 1.28 l/s and an average yield of 1 l/s, while boreholes located outside lineament gave groundwater yield range of between 0.2 and 1.26 l/s with an average yield of 0.98 l/s. The investigation of the hydrogeological characteristics of the lithologies by superimposing the yield data showed average yield of 0.98 l/s for migmatite gneiss biotite granite undifferentiated (M), 1.01 l/s for porphyritic granite (OGp), 1.03 l/s for medium- to coarse-grained (OGe), 1.17 l/s for pelitic schist undifferentiated (Su), 1.24 l/s for quartz schist and quartzite (Eq), 1.12 l/s for older granite undifferentiated (OGu), 0.5 l/s for slightly migmatised medium-grained granite-gneiss (gg) and 1.23 l/s for fine-grained flaggy quartzite and schists (Sf). The study concluded that borehole data located on or near lineaments or at intersection of lineaments gave higher yields more than those located before lineaments or outside lineaments, while quartz schist and quartzite exhibited the highest average groundwater yield of all the lithological units.

  15. Study of deep fractures of granitic rocks: structural study of Saint-Sylvestre granite fractures (Fanay-Augeres and Margnac Mines, Haute-Vienne, France)

    International Nuclear Information System (INIS)

    Bles, J.L.; Dutartre, P.; Feybesse, J.Y.; Gros, Y.; Martin, P.

    1984-01-01

    Radioactive waste disposal in deep geologic formation requires a good knowledge of the host rock characteristics. The present study, concentrated on granitic formations, looks for extrapolation in deep underground of fracturation data obtained at the surface

  16. 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.

  17. In-situ diffusion in granite: results from scoping experiments

    International Nuclear Information System (INIS)

    Cramer, J.J.; Melynk, T.W.; Miller, H.G.

    1997-03-01

    This report describes the scoping experiments carried out, both in the laboratory and in-situ at a depth of ∼450 m in the Underground Research Laboratory, for the study to determine the diffusion parameters of intact granite/granodiorite under natural high-stress conditions. The study includes four in-situ diffusion experiments (one each in four separate boreholes with experiment times from six months to two years), and supporting laboratory experiments. Tentative conclusions from the first 203-day in-situ experiment in hole DIF4 indicate that the in-situ tortuosity value of granodiorite under high stress conditions may be significantly higher than those obtained from measurements on the same rock under ambient conditions in the laboratory. Because problems were encountered during drilling of the in-situ sample core, potentially adversely affecting the analytical data, further work needs to be carried out to substantiate these tentative conclusions. Tortuosity values obtained in the laboratory for de-stressed rock from the in-situ experiment zones range between 2.4 and 4.6, falling well within the range of tortuosity values reported by Davison et al. (1994) that were used for the assessment modelling of the reference disposal system (Goodwin et al. 1994). The granodiorite samples have lower tortuosity values (between 2.4 and 3.9) compared with that of the single granite sample (4.6). (author)

  18. Technical concept for rock mechanics tests, Climax Granite, NTS

    Energy Technology Data Exchange (ETDEWEB)

    Hearst, J.R.

    1979-02-01

    If we are to believe our predictions of the thermomechanical behavior of the material surrounding a nuclear waste repository in granite, we must test the computational methods used in making the predictions. If thermal loadings appropriate to a real repository are used, thermally induced displacements and strains are quite small, and available geotechnical instrumentation is only marginally able to measure these effects to the accuracy desired to make thorough tests of the predictions. We outline a three-step program to address these issues. (1) Conduct experiments in which the thermal loading is large compared to that induced by a real repository. This will permit us to make accurate measurements with available instrumentation. (2) Simultaneously, develop improved instrumentation that will enable us to make accurate measurements of motions induced by thermal loadings appropriate to a real repository. (3) Finally, conduct a second set of experiments, with the improved instrumentation and thermal loading similar to that of a real repository in granite. If we can predict the effects of this thermal loading to a few percent over distances of tens of meters for time periods of a few years, and demonstrate that these predictions are correct, we can have reasonable confidence that, using the same methods, we can predict the behavior over thousands of meters for hundreds of years to an order of magnitude. That accuracy should be satisfactory for those distances and times.

  19. Desorption of cesium from granite under various aqueous conditions

    International Nuclear Information System (INIS)

    Wang, T.-H.; Li, M.-H.; Wei, Y.-Y.; Teng, S.-P.

    2010-01-01

    In this work the desorption of cesium ions from crushed granite in synthetic groundwater (GW) and seawater (SW) was investigated. Results were compared with those obtained in deionized water (DW) and in two kinds of extraction solutions, namely: MgCl 2 and NaOAc (sodium acetate). In general, the desorption rate of Cs from crushed granite increased proportionally with initial Cs loadings. Also, amounts of desorbed Cs ions followed the tendency in the order SW>GW>NaOAc∼MgCl 2 >DW solutions. This indicated that the utilization of extraction reagents for ion exchange will underestimate the Cs desorption behavior. Fitting these experimental data by Langmuir model showed that these extraction reagents have reduced Cs uptake by more than 90%, while only less than 1% of adsorbed Cs ions are still observed in GW and SW solutions in comparison to those in DW. Further SEM/EDS mapping studies clearly demonstrate that these remaining adsorbed Cs ions are at the fracture areas of biotite.

  20. Forsmark site investigation. Granitic groundwater colloids sampling and characterisation

    International Nuclear Information System (INIS)

    Nilsson, A.C.; Degueldre, C.

    2007-08-01

    Natural ground water colloids were sampled by micro-filtration of water samples collected from a granitic groundwater and maintained at the in situ thermodynamic conditions. The methodology avoids the generation of artefacts produced by pH changes due to CO 2 exchange, yielding potential carbonate precipitation, or by O 2 contaminations yielding oxidized insoluble phases. The enhanced pressure and the anoxic conditions are maintained also through the filtering procedure. In situ groundwater sampling followed by micro-filtration of the colloids were carried out after a period of regular sampling of groundwater pumped to the ground surface and continuous on-line long-term measurements (weeks, months) of chemical and physical parameters in the unbroken sample water both at the ground surface and at depth down-hole. Colloid samples were characterized by scanning electron microscopy. At deep granitic groundwater conditions, natural colloids occur sparsely. The colloid concentration was determined C col ∼1 μg/L for sizes ranging from 50 to 500 nm or N col ∼10 8 /L for sizes larger than 100 nm. These colloids are clay with an average size smaller than 200 nm. For the Na-Ca-Cl groundwater (pH 7.53, ionic strength ∼0.1M), the colloid concentration values are comparable with values reported earlier in the literature

  1. 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.)

  2. Geochronological constraints on granitic magmatism, deformation, cooling and uplift on Bornholm, Denmark

    DEFF Research Database (Denmark)

    Waight, Tod Earle; Frei, Dirk; Storey, Michael

    2012-01-01

    U-Pb ages on zircon from 11 samples of granitoid and gneiss from the Danish island of Bornholm have been obtained using laser ablation - inductively coupled plasma mass spectrometry. These ages indicate that the felsic basement rocks were generated over a restricted period in the Mesoproterozoic...

  3. A fractal derivative constitutive model for three stages in granite creep

    Directory of Open Access Journals (Sweden)

    R. Wang

    Full Text Available In this paper, by replacing the Newtonian dashpot with the fractal dashpot and considering damage effect, a new constitutive model is proposed in terms of time fractal derivative to describe the full creep regions of granite. The analytic solutions of the fractal derivative creep constitutive equation are derived via scaling transform. The conventional triaxial compression creep tests are performed on MTS 815 rock mechanics test system to verify the efficiency of the new model. The granite specimen is taken from Beishan site, the most potential area for the China’s high-level radioactive waste repository. It is shown that the proposed fractal model can characterize the creep behavior of granite especially in accelerating stage which the classical models cannot predict. The parametric sensitivity analysis is also conducted to investigate the effects of model parameters on the creep strain of granite. Keywords: Beishan granite, Fractal derivative, Damage evolution, Scaling transformation

  4. Characteristics and significance of uranium bearing pan african younger granite in the eastern desert, Egypt

    International Nuclear Information System (INIS)

    Hassan, M.A.; Dabbour, G.A.; Mohammden, T.F.

    1998-01-01

    Surficial uranium mineralization was discovered in four pan african younger granite plutons in the eastern desert of egypt. The present study revealed great similarity between these plutons both in petrography and geochemistry. They are two-feldspar, two-mica peraluminous granites which have been formed by melting of crustal materials and emplaced during the late stage stage of a late proterozoic orogenic cycle. Radiometric and geochemical investigations indicate that these granites are fertile with respect to U and form a potential target for primary uranium deposits. Four models are suggested to explain the source and mechanism of the surficial uranium mineralization in these granites. The most applicable model is the oxidation of U +4 found in minute disseminated uraninite grains and its subsequent mobilization. This is supported by petrographic and autoradiographic studies. The bearings of the present study on further exploration for uranium deposits in granites of the arabian- Nubian shield in general are discussed

  5. The distribution and uranium content characteristics of Indosinian granite in South China

    International Nuclear Information System (INIS)

    Sun Wenliang; Zhang Zhuo; Chen Wenwen; Chen Lulu; Xu Wenzheng

    2014-01-01

    In recent years, more and more Indosinian granite plutons has been found in South China, so some new ideas about the granity were proposed by scholars. The Indosinian granite in South China distributed in lineshape, and is controlled by some regional faults. Its formation was mainly related to geodynamic setting which began in the late Permian (about 256 Ma) by the subduction of the ancient Pacific Plate to the Eurasia. The average uranium content of Indosinian granite is 10.34ppm, much higher than the average value of world's acid rock. There occurs some couplings between the distribution of the Indosinian granite plutons and uranium mineralization belt in South China. So the Indosinian granite in South China may act as important uranium sources for the mineralization. (authors)

  6. 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.)

  7. Mafic microgranular enclaves (MMEs) in amphibole-bearing granites of the Bintang batholith, Main Range granite province: Evidence for a meta-igneous basement in Western Peninsular Malaysia

    Science.gov (United States)

    Quek, Long Xiang; Ghani, Azman A.; Chung, Sun-Lin; Li, Shan; Lai, Yu-Ming; Saidin, Mokhtar; Amir Hassan, Meor H.; Muhammad Ali, Muhammad Afiq; Badruldin, Muhammad Hafifi; Abu Bakar, Ahmad Farid

    2017-08-01

    Mafic microgranular enclaves (MMEs) with varying sizes are a common occurrence in porphyritic amphibole-bearing granite of the Bintang batholith, which is part of the Main Range granite province. The MMEs of the amphibole-bearing granite are significant as they are related to the I-type granitoids within the Main Range granite province. Petrographic observations indicate the MMEs are mantled with coarse mafic crystals on the rim and contain similar minerals to the host (biotite + plagioclase + K-feldspar + pyroxene + amphibole), but in different proportions. Geochemical analyses indicate the MMEs are shoshonitic with mg# comparable to the granite host. Substantial similarities exist between the MMEs and granite with regards to the normalized rare earth element patterns and trace elements variation diagrams. The MMEs and granite are not completely coeval as the MME zircon U-Pb age (224.3 ± 1.2 Ma) is slightly older than its granite host zircon U-Pb age (216.2 ± 1.0 Ma). The age difference is also observed from the unusual 500 m-long Tiak MME and another amphibole-bearing granite sample from the south of the pluton, which yield 221.8 ± 1.1 Ma and 217.4 ± 1.0 Ma respectively. The oldest inherited zircons found in the MME and granite are 2.0 Ga and 1.3 Ga respectively, while the oldest xenocrystic zircons found in the MME and granite are 2.5 Ga and 1.5 Ga respectively. Identical negative εHf(t) values from zircon U-Pb and Lu-Hf analysis for a MME-granite pair indicates the rocks were generated from a similar, ancient source in the basement. Combining the results, we suggest that incongruent melting of an ancient protolith played an important part in the evolution of the MMEs and granite and the MMEs characteristics are best explained as restite. The zircon Hf model age (two-stage) and the I-type peritectic and restitic mineral assemblages in the MMEs further describe the protolith as Early Proterozoic-Late Archean (≈2.5 Ga) meta-igneous rock. This shows the

  8. Mobility of heavy metals through granitic soils using mini column infiltration test

    Science.gov (United States)

    Zarime, Nur'Aishah; Yaacob, W. Z. W.

    2014-09-01

    This study is about the mobility of cadmium through compacted granitic soils. Two granitic soils namely the Broga (BGR) and Kajang (KGR) granitic soils were collected in Selangor, Malaysia. Physical and chemical tests were applied for both granitic soils to determine the physical and chemical properties of soil materials. Physical test results shows granitic soils (BGR and KGR) have high percentage of sand ranging between 54%-63% and 46%-54% respectively, an intermediate and intermediate to high plasticity index as well as high specific gravity ie; 2.50-2.59 and 2.45-2.66 respectively. For chemical test, granitic soils shows acidic pH values ranged from 5.35-5.85 for BGR and pH 5.32-5.54 for KGR. For organic matter, SSA and CEC test, it shows low values ranged from 0.22%-0.34% and 0.39%- 0.50% respectively for organic matter test, 17.96 m2/g-21.93 m2/g and 25.76 m2/g-26.83 m2/g respectively for SSA test and 0.79 meq/100g-1.35 meq/100g and 1.31 meq/100g-1.35 meq/100g respectively for CEC test. Mini column infiltration test was conducted to determine the retention of cadmium while flowing through granite soils. This test conducted based on the falling head permeability concepts. Different G-force ranging from 231G to 1442G was used in this test. The breakthrough curves show the concentration of Cd becomes higher with the increasing of G-force for both granitic samples (BGR and KGR). The selectivity sorption for both granites ranked in the following decreasing order of; 231G>519G>923G>1442G. Results demonstrated that granitic soils also have low buffering capacity due to low resist of pH changes.

  9. 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)

  10. New Rb-Sr isotope data from the Mzumbe Gneiss Suite, the oldest granitoid in the Mzumbe Terrane, Natal Metamorphic Province

    International Nuclear Information System (INIS)

    Thomas, R.J.; Eglington, B.M.

    1990-01-01

    Although the rocks of the Mzumbe Gneiss suite display a close similarity to many Archaean, high-alumina tonalite-trondhjemite suites, an origin by the reactivation of a pre-existing Archaean or early Proterozoic infrastructure during the Namaqua-Natal orogenesis, can be effectively excluded. It is proposed that the Natal Metamorphic Provunce was formed by the generation and successive accretion of discrete fragments of juvenile crust onto the southern margin of the Kaapvaal craton between ∼1200 and 900 Ma. 1 fig., 9 refs

  11. Geochronology, geochemistry, and petrogenesis of late Permian to early Triassic mafic rocks from Darongshan, South China: Implications for ultrahigh-temperature metamorphism and S-type granite generation

    Science.gov (United States)

    Xu, Wang-Chun; Luo, Bi-Ji; Xu, Ya-Jun; Wang, Lei; Chen, Qi

    2018-05-01

    The role of the mantle in generating ultrahigh-temperature metamorphism and peraluminous S-type granites, and the extent of crust-mantle interaction are topics fundamental to our understanding of the Earth's evolution. In this study we present geochronological, geochemical, and Sr-Nd-Hf isotopic data for dolerites and mafic volcanic rocks from the Darongshan granite complex belt in western Cathaysia, South China. LA-ICP-MS U-Pb zircon analyses yielded magma crystallization ages of ca. 250-248 Ma for the dolerites, which are coeval with eruption of the mafic volcanic rocks, ultrahigh-temperature metamorphism, and emplacement of S-type granites in the Darongshan granite complex belt. The mafic volcanic rocks are high-K calc-alkaline or shoshonitic, enriched in Th, U, and light rare earth elements, and depleted in Nb, Ta and Ti. The dolerites are characterized by high Fe2O3tot (11.61-20.39 wt%) and TiO2 (1.62-3.17 wt%), and low MgO (1.73-4.38 wt%), Cr (2.8-10.8 ppm) and Ni (2.5-11.4 ppm). Isotopically, the mafic volcanic rocks have negative whole-rock εNd(t) values (-6.7 to -9.0) and high ISr values (0.71232 to 0.71767), which are slightly depleted compared with the dolerite samples (εNd(t) = -10.3 to -10.4 and ISr = 0.71796 to 0.71923). Zircons in the dolerites have εHf(t) values of -7.6 to -10.9. The mafic volcanic rocks are interpreted to have resulted from the partial melting of an enriched lithospheric mantle source with minor crustal contamination during ascent, whereas the dolerites formed by late-stage crystallization of enriched lithospheric mantle-derived magmas after fractionation of olivine and pyroxene. The formation of these mantle-derived mafic rocks may be attributed to transtension along a NE-trending strike-slip fault zone that was related to oblique subduction of the Paleo-Pacific plate beneath South China. Such underplated mafic magmas would provide sufficient heat for the generation of ultrahigh-temperature metamorphism and S-type granites, and

  12. Granite emplacement at the termination of a major Variscan transcurrent shear zone: The late collisional Viseu batholith

    Science.gov (United States)

    Valle Aguado, B.; Azevedo, M. R.; Nolan, J.; Medina, J.; Costa, M. M.; Corfu, F.; Martínez Catalán, J. R.

    2017-05-01

    A major event of plutonic activity occurred all across the Central Iberian Zone of the Iberian Variscan Belt at the end of Late Paleozoic Variscan collisional tectonism. The present study focuses on the western sector of the Viseu late-post-tectonic batholith (central Portugal), a large composite intrusion comprising three main plutonic units: (a) small bodies of mafic to intermediate composition preferentially concentrated along the northern border, (b) a wide ring of coarse porphyritic biotite monzogranite (Cota-Viseu granite) and (c) a more evolved medium porphyritic, biotite-muscovite monzogranite occupying the central part of the intrusion (Alcafache granite). The compositional zonation pattern of the whole batholith and the complex mixing/mingling relationships between the voluminous Cota-Viseu porphyritic granite and the mafic/intermediate rocks suggest that these melts were withdrawn from a lower crustal source region undergoing partial melting, invasion by mantle-derived mafic magmas, mixing and fractional crystallization. New CA-ID-TIMS U-Pb zircon ages indicate that pluton assembly via multipulse injection of successive magma batches took place between 299.4 ± 0.4 Ma and 296.0 ± 0.6 Ma. A detailed anisotropy of magnetic susceptibility (AMS) survey suggests that pluton emplacement occurred at the extensional termination of a regional-scale, ENE-WSW trending, sinistral D3 shear zone - the Juzbado-Penalva Shear Zone (JPSZ). A dilational opening model involving the development of "en-échelon" tensional gashes at the extensional termination of the fault, followed by progressive opening and widening of north-south trending fractures, provided the space into which the successive magma batches arriving from below were emplaced. Vertical inflation was accommodated by depression of the pluton floor. The proposed model is consistent with the asymmetric wedge-shaped geometry of the intrusion (steep root zone on the northern side, discordant subvertical walls and

  13. 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.

  14. Mineralogical Control on Microbial Diversity in a Weathered Granite?

    Science.gov (United States)

    Gleeson, D.; Clipson, N.; McDermott, F.

    2003-12-01

    Mineral transformation reactions and the behaviour of metals in rock and soils are affected not only by physicochemical parameters but also by biological factors, particularly by microbial activity. Microbes inhabit a wide range of niches in surface and subsurface environments, with mineral-microbe interactions being generally poorly understood. The focus of this study is to elucidate the role of microbial activity in the weathering of common silicate minerals in granitic rocks. A site in the Wicklow Mountains (Ireland) has been identified that consists of an outcrop surface of Caledonian (ca. 400 million years old) pegmatitic granite from which large intact crystals of variably weathered muscovite, plagioclase, K-feldspar and quartz were sampled, together with whole-rock granite. Culture-based microbial approaches have been widely used to profile microbial communities, particularly from copiotrophic environments, but it is now well established that for oligotrophic environments such as those that would be expected on weathering faces, perhaps less than 1% of microbial diversity can be profiled by cultural means. A number of culture-independent molecular based approaches have been developed to profile microbial diversity and community structure. These rely on successfully isolating environmental DNA from a given environment, followed by the use of the polymerase chain reaction (PCR) to amplify the typically small quantities of extracted DNA. Amplified DNA can then be analysed using cloning based approaches as well as community fingerprinting systems such as denaturing gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (TRFLP) and ribosomal intergenic spacer analysis (RISA). Community DNA was extracted and the intergenic spacer region (ITS) between small (16S) and large (23S) bacterial subunit rRNA genes was amplified. RISA fragments were then electrophoresed on a non-denaturing polyacrylamide gel. Banding patterns suggest that

  15. Origin of granite at Cabo de Santo Agostinho, Northeast Brazil

    Science.gov (United States)

    Long, Leon E.; Sial, Alcides N.; Nekvasil, Hanna; Borba, Glicia S.

    1986-09-01

    A 4 km2 exposure of shallowly-emplaced leucogranite on the Atlantic coast at Cabo de Santo Agostinho, 30 km south of Recife, Brazil has been extensively studied chemically and isotopically. Twenty-three major-element analyses indicate that the Cabo granite ranges from peralkaline to peraluminous; Na2O+K2O is very high (7.4 to 10.4 wt.%), with CaO low (˜0.3%) and MgO vanishing (<0.06%). Microprobe analyses confirm the presence of arfvedsonite (biotite absent), and nearly total absence of plagioclase. The rocks are moderately to highly enriched in LREE (La 45 to 350 times chondritic), with extremely pronounced negative Eu anomalies (Eu/Eu*=0.02 to 0.07). Whole-rock δ 18O is consistent at +8.5±0.3%.oSMOW A Rb-Sr isochron age of isotopically slightly disturbed samples is 104.8±1.8 Ma, with initial87Sr/86Sr=0.7084±0.0011. Sr is depleted (2 20 ppm) but Ba is 200 750 ppm. Crystallization path calculations and petrographic observations suggest that magma formed at a pressure close to 6 kbar but rose to a crustal level equivalent to roughly 1 kbar. Quartz, the liquidus phase at moderate H2O concentrations and pressures above 2 kbar, was resorbed during decompression as the magma moved upwards. Ultimately, quartz and alkali feldspar coprecipitated. Feldspar was not retained in the source rock nor removed early from the fractionating magma. Therefore the strong negative Eu anomaly and low Sr abundance are characteristics inherited from the source. A high H2O concentration necessary for a large degree of melting was lacking, hence the Cabo magma composition must reflect a small degree of partial melting of a rather quartz-rich rock such as a feldspathic arenite. In a pre-drift reconstruction of Gondwanaland, the Cabo granite fits on the southernmost and youngest end of the trend of the Niger-Nigerian igneous centers with which it has close affinity. The Cabo granite occupies the western end of the trace of the ancestral Ascension mantle plume which presumably served as

  16. 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.

  17. Waste disposal in granitic rocks: analysis of thermal microcracks

    International Nuclear Information System (INIS)

    Montoto, M.; Roeshoff, K.; Leojon, B.; Bel-Lan, A.

    1981-04-01

    The possible development of microcracks from a thermal origin has been researched in the granitic rocks of Shipa (Sweden), within which in a real scale have been originated some thermal gradients similar to the ones which could take place in the waste disposal. To achieve an optimal fratographic information, with some petrographic meaning, different microscopic techniques, optical and electronic, have been combined and an automatized quantification methodology has also been developed by means of digitals. Between warmed and unwarmed granitis no microfractographic differences have been detected. The observed variations are only apparent and may be explained as a function of the inherent petrographic heterogeneity of rocky blocks. In any case in the internal temperatures generated within these rocks have not attained its own threshold of thermal microcracking. (author)

  18. Geoscience parameter data base handbook: granites and basalts

    International Nuclear Information System (INIS)

    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

  19. 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...

  20. 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.

  1. Thermal cracking of Westerly granite: from physical to numerical experiment

    Science.gov (United States)

    Schrank, Christoph; Fusseis, Florian; Karrech, Ali; Revets, Stefan; Regenauer-Lieb, Klaus; Liu, Jie

    2010-05-01

    Laboratory experiments provide some of the most comprehensive constraints on rock properties such as permeability, porosity, and rheology. However, in most cases such experiments are performed on length and time scales that are much smaller than geological scales. Upscaling, physically sound methods for extrapolation, of the obtained constitutive laws is therefore a matter of hot debate. Here, we present a numerical approach for the upscaling of the porosity evolution due to thermal cracking of Westerly granite. This project draws upon actual laboratory step-heating experiments of Westerly granite observed with high-resolution 3D synchrotron tomography (see Fusseis and others:" Formation of secondary porosity in 4D Synchrotron X-ray tomography experiments"). First, we use tomography time-series data to calibrate numerical simulations at the laboratory scale. In effect, the real-world sample is discretised and "heated" numerically. The software is an implicit Lagrangian finite-element code (Abaqus Standard) using elastoplastic rheologies in coupled temperature-displacement analysis. To minimize computational costs, indirect feedbacks, namely temperature-dependent functions of density, coefficient of thermal expansion, specific heat capacity, Poisson's ratio, and Young's modulus, are pre-calculated with PerpleX (Connolly 2005) and implemented as table input. Direct feedbacks are computed in the framework of thermodynamic equations and solved for explicitly. Next, we repeat the above numerical experiments for simplified stochastic models of the actual sample at the laboratory scale. Finally, we generate stochastic numerical models on increasing scales to determine the scale at which rock properties remain constant regardless of the specific microstructure. This empirical homogenization allows the derivation of constitutive laws which can be employed for large-scale simulations. In this contribution, we will briefly outline this workflow and present first results for

  2. 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.

  3. 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.

  4. Structural and petrophysical characterisation of granite: intended for radioactive waste stocking

    International Nuclear Information System (INIS)

    Stanek, Martin

    2013-01-01

    Structural and petrophysical analysis have been conducted within the Melechov massif with focus on structures controlling the porosity, permeability and thermal conductivity of the rock. The structure of the massif has been constrained based on extensive dataset including AMS and field structural measurements of ductile and brittle structures. The fracture system of the massif has been described by four sets of fractures. The measured petrophysical data have been used to characterize the effect of fracturing and alteration on pore space geometry and in turn on permeability, thermal conductivity and elastic properties of the studied granite. Distinct petrophysical properties have been identified for pristine granite, for fractured fresh granite as well as for fractured granite altered by Fe-oxide, chlorite and clay minerals. A detailed microstructural study combined with multidirectional P-wave velocity measurements at high confining pressure and with AMS analysis has been conducted on a Schlieren bearing sample of Lipnice granite. The granite VP anisotropy at low confining pressure was controlled by intergranular cracks interconnecting Schlieren-sub parallel cleavage cracks in micas and feldspars and by exfoliation fracture-sub parallel intra- or trans-granular cracks in cleavage-free quartz. Major closing of the crack porosity linked to the Schlieren granite below depth of 500 m has been interpreted in terms of crack compliance reflected by rapid increase in VP with confining pressure. (author)

  5. Rb-Sr dating of strain-induced mineral growth in two ductile shear zones in the western gneiss region of Nord-Troendelag, Central Norway

    International Nuclear Information System (INIS)

    Piasecki, M.A.; Cliff, R.A.

    1988-01-01

    In the Bjugn district of the northern part of the Western Gneiss Region, Nord-Troendelag, a basement gneiss-cover nappe boundary is marked by a thick zone of ductile shearing. In this zone a layer-parallel mylonitic fabric with related new mineral growth overprints and retrogresses a previous fabric associated with a granulite facies mineral assemblage. Related minor shear belts contain abundant new minerals and vein systems, including pegmatites, believed to represent strain-induced products formed at the time of the shearing movements. Central parts of two large muscovite books from such a pegmatite yielded Rb-Sr, Early to Middle Devonian ages of 389±6 Ma and 386±6 Ma, interpreted as indicating the approximate time of pegmatite formation and of the shearing. Small, matrix-size muscovite and biotite grains from the host mylonite gave ages of 378±6 Ma and 365±5 Ma, respectively, supposed to relate to post-shearing uplift and cooling

  6. Contribution of Portuguese two-mica granites to stone built heritage

    Science.gov (United States)

    Almeida, Angela; Begonha, Arlindo

    2013-04-01

    The present study deals with the importance of the application of natural stone in monuments in urban setting, both as the main building material during the historical evolution of a city and as a means to increase the public awareness of the social role of geological resources of a specific region. The City of Oporto, World Heritage of the Humanity , has been selected to illustrate the use of the local granite since ancient times to the present day, a two-mica peraluminous granite ,classified as syn-tectonic relatively to the third tectonic deformation phase of the Hercynian orogeny, included in an expressive group that occurs extensively in northern Portugal . The Oporto granite has been the object of several geochemical, structural and geotechnical approaches. Despite the urban development, outcrops of this granite can be observed in different areas of the city, side by side with the urban constructions, and particularly in the imposing and intensely fractured escarpments carved by the river Douro. Oporto monumental heritage goes back to Roman occupation and the profile has been developed by the construction of granite buildings, following history and the social evolution, of an impressive grey architecture according to different styles of granite work that characterize the city in all its aspects, namely the old city wall, the medieval and baroque churches, the neoclassic houses but also the small humble habitations. The Oporto granite is always affected by weathering processes and the buildings exhibit various aspects of stone decay such as granular desintegration, plates, flakes, black crusts, thin black layers, efflorescences and biological colonization. The description of selected sites within the historical centre , where it is possible to recognize the importance of the granite in the character of the city, aims to call the attention to the inextricable role of geology in built heritage and in the culture, as well as to diagnose the deterioration

  7. Mineralogy, geochemistry and petrophysics of red coloured granite adjacent to fractures

    International Nuclear Information System (INIS)

    Eliasson, T.

    1993-03-01

    Mineralogical, geochemical and petrophysical investigations were conducted of red-coloured alteration rims and of the neighbouring unaltered equivalents along fractures within granite from Aespoe. An investigation was made also of a weak to rather strong, red-coloured granite from the Stripa mine, as well as a weak brownish-red colouration, definitely no hydrothermal in origin, of weathered rinds at a glacial polished rock surface in the Bohus granite. When approaching the fracture planes in the Aespoe granite, the most diagnostic alteration features are * the saussuritisation and Fe-oxyhydroxide staining of plagioclase, * the crystallisation chlorite pseudomorphs after biotite and * the hematisation of magnetite. The porosity within the alteration zones increases generally 2 to 3 times compared with the protolith rock, whereas the densities decrease by some 5 to 10%. The oxidation of magnetite gives as much as a tenfold lowering of the magnetic susceptibility. The red colouration of the Stripa granite is caused by hematite ± Fe-oxyhydroxide formation along microfractures, grain boundaries and, subordinately, the main minerals. Oxidation and re-precipitation of iron liberated during a retrograde muscovitisation of principally chlorite is interpreted to be the cause of the formation of the ferric oxides. The rather homogeneous density and porosity values of the grey and of the red-coloured granites reflect the minor change in the mineralogy when going from fresh into altered granite. Weathering and whitening of plagioclase in the bleached, outer zone and precipitation of small quantities of Fe-oxyhydroxides/hydroxides in the brownish-red zone cause the macroscopic colouration of the weathering rind below the glacial polished rock surface of Bohus granite. There is a marked increase in porosity from the interior fresh (c. 0.4-0.5%) towards the exterior bleached zone (c.1.5-2%) of the subaerialy, weathered Bohus granite surface. The incipient decomposition of

  8. Paleoarchaean rhyolitic volcanism and the origin of the granitic continental crust

    Science.gov (United States)

    Sanchez-Garrido, C.; Stevens, G.; Armstrong, R.; Moyen, J.; Herve, M.; Doucelance, R.

    2009-12-01

    Earth’s continental crust is dominated by granitic (s. s.) rocks with substantial K2O contents and K/Na > 0.6. However, 75% of Earth’s continental crust formed during the Archaean (4.0—2.5 Ga), as sodic Tonalite-Trondhjemite-Granodiorite (TTG) granitoids (K/Na ~ 0.23). It is generally assumed that the more potassic granites arose by intracrustal recycling of this material. This assumption predicts that Earth’s bulk crustal composition remains TTG-like, limiting the volume of granitic material that can form and necessitating that it would be counterbalanced by a substantially larger volume of refractory residua from the partial melting of TTGs. Consequently, the composition of the post-Archaean crust requires an additional source of crustal K2O. Here we present evidence that in the Barberton Greenstone Belt (BGB) in South Africa, TTG magmas were formed concurrently with sub-volcanic granitic and rhyolitic magmas. This granitic magmatism occurred during each of three documented cycles of TTG magmatism at ca 3550, 3450 and 3230 Ma. The granites and rhyolites from each episode display the same major- and trace- element compositions, which preclude their derivation through fractional crystallization or partial melting of a protolith of TTG composition and indicate their source to be potassic clay-bearing sediments derived predominantly from the weathering of mafic rocks. The production of these granitic magmas that lack crustal residency and are destined to erupt, during each tectono-magmatic episode of crust production, provides a path for the accumulation of potassium in volcano-sedimentary depositories, despite the absence of granites in the plutonic record at the time. In the BGB, the orogenic reworking of the first major accumulation of these sediments (the Fig Tree Group) coincided with the last TTG producing event and fertilised the middle and lower crust for the subsequent production of granitic magmas.

  9. K/Ar age dating of Oshnaviyeh plutonic complex

    International Nuclear Information System (INIS)

    Ghalamghash, J.; Vosoughi Abedini, M.; Bellon, H.; Emami, M.H.; Pourmafi, M.; Rashid, H.

    2003-01-01

    Oshnaviyeh plutonic complex, the western member of Urumiyeh-Golpayehgan intrusive plutons is located in northern part of Sanandaj-Sirjan zon. Oshnaviyeh plutonic complex, exposing in an area of about 700 km 2 , comprises 10 plutons that can be divided into three suites, i.e.,diorite,granite,and alkali syenite-alkali granite. Dioritic bodies are the oldest intrusive rocks of the region, which on the basis of the field study, their relative age of emplacement is estimated to be post-Jurassic and pre-miocene. However, with respect to the age of other similar intrusive bodies in Naghadeh area, they are most likely of post early cretaceous-pre miocene age. Hybrid intrusive rocks, occurring at the contact of dioritic and granitic rocks may suggest a simultaneous emplacement of both magmas. Syntetic pluton from alkali syenite-alkali granite has intruded dioritic and granitic rocks, in contrast, flourine bearing alkali granite pluton from this suite shows no contact with other igneous rocks in the area. K-Ar age determinations obtained on amphibole specimens from diorite suite are 91.9±2.3, 94.1±2.3 and 100±2.4 Ma, and on biotite specimens from granite suite are 100±1.5 to 98.9±1.5 Ma. Chronology study using same method on arfvedsonite specimens from syenite pluton shows 78.9±3.1, 79.6±1.9 and 81.7±2.0 Ma and on K-fled par samples of flourine bearing alkali granite pluton from the alkali syenite-alkali granite suite presents 76±3.4 and 77.1±1.8. Therefore, based on field evidence and K/Ar age dating, Oshnaviyeh plutonic complex presumably formed during two episodes: granite and diorite suites formed simultaneously at about 100 Ma, then plutons of alkali syenite-alkali granite suite emplaced at about 80 Ma

  10. Greisen deposits associated to carboniferous post-orogenic granites with mineralization potential, Sierra de Fiambala, Catamarca, Argentina

    International Nuclear Information System (INIS)

    Fogliata, A. S.; Rubinstein, N. R.; Avila, J. C.; Baez, M.

    2008-01-01

    The Fiambala range is located in the central south part of the province of Catamarca, Western Sierras Pampeanas, Argentina. It is largely conformed by Precambrian metamorphic rocks, a Cambrian granitic intrusive, Ordovician basic and ultra basic rocks and epi zonal Carboniferous granites (Los Ratones, El Salto and Ayacucho Granites). The Carboniferous granites are sub alkaline, weakly peraluminous, high silica (except for the porphyritic facies of Los Ratones granite) and moderately enriched in K. Contents of trace elements and REE indicate that El S alto and Ayacucho granites and the granular facies of Los Ratones granite have characteristics of evolved and differentiated granite associated with hydrothermal systems. The variations of trace elements, particularly Sn, W, U, Rb, Ba, Zr and Sr suggest that they correspond to granites with mineralization potential. Genetically linked to these granites there are Sn, W, U and minor base metals greisen deposits. The hydrothermal process that yield to these deposits involved two main alteration stages, beginning with alkali metasomatism follow by greissenization. According to the isotopic ages the hydrothermal processes postdate about 1 Ma the magmatic activity. The analyses of the granites and the associated greisen deposits confirm that the post orogenic carboniferous magmatism is the major metallogenetic control of the ore deposits from the studied area. This metallogenetic control could be a useful tool in prospecting similar deposits in the rest of the Western Sierras Pampeanas. (Author)

  11. Study on Time-Dependent Behavior of Granite and the Creep Model Based on Fractional Derivative Approach Considering Temperature

    Directory of Open Access Journals (Sweden)

    Zhilei He

    2016-01-01

    Full Text Available Based on mineral components and the creep experimental studies of Three Gorges granite and Beishan granite from different regions of China at various temperatures, the strength and creep property of two types of granites are compared and analyzed. Considering the damage evolution process, a new creep constitutive model is proposed to describe the creep property of granite at different temperatures based on fractional derivative. The parameters of the new creep model are determined on the basis of the experimental results of the two granites. In addition, a sensitivity study is carried out, showing effects of stress level, fractional derivative order, and the exponent m. The results indicate that the proposed creep model can describe the three creep stages of granite at different temperatures and contribute to further research on the creep property of granite.

  12. Rational Rock Physics for Improved Velocity Prediction and Reservoir Properties Estimation for Granite Wash (Tight Sands in Anadarko Basin, Texas

    Directory of Open Access Journals (Sweden)

    Muhammad Z. A. Durrani

    2014-01-01

    Full Text Available Due to the complex nature, deriving elastic properties from seismic data for the prolific Granite Wash reservoir (Pennsylvanian age in the western Anadarko Basin Wheeler County (Texas is quite a challenge. In this paper, we used rock physics tool to describe the diagenesis and accurate estimation of seismic velocities of P and S waves in Granite Wash reservoir. Hertz-Mindlin and Cementation (Dvorkin’s theories are applied to analyze the nature of the reservoir rocks (uncemented and cemented. In the implementation of rock physics diagnostics, three classical rock physics (empirical relations, Kuster-Toksöz, and Berryman models are comparatively analyzed for velocity prediction taking into account the pore shape geometry. An empirical (VP-VS relationship is also generated calibrated with core data for shear wave velocity prediction. Finally, we discussed the advantages of each rock physics model in detail. In addition, cross-plots of unconventional attributes help us in the clear separation of anomalous zone and lithologic properties of sand and shale facies over conventional attributes.

  13. Preliminary experiences of radionuclide migration with granitic materials: El Berrocal (Spain)

    International Nuclear Information System (INIS)

    Garcia Gutierrez, M.

    1994-01-01

    This report presents the radionuclide migration in granitic rocks used for radioactive waste storage. This project is developed in El Berrocal (Spain). The author studies the absorption process, applies the transport equation, the column migration and analyzes the curves

  14. Characteristics and its uranium metallogenic potential of the granite belt between Bange and Jiali county, tibet

    International Nuclear Information System (INIS)

    Zhao Baoguang; Wang Qin; Liu Zhipeng; Chen Yuliang; Xu Wei

    2012-01-01

    The granite belt between Bange and Jiali county is a composite batholith which intruded at multistage, it con- trolled by several groups of the fault system, the alteration is developed, with the alaskite, aplite, pegmatitic vein intruded, it is type Ⅰ in the beginning of forming, and change to type S in the late time. There is a large of geochemical anomalies of uranium (U>6.8 X 10 -6 ) in Gulu town and Sangba village, of which middle of the granite belt and Bianba county of which east of the granite belt, that anomalies area have 1200 km 2 , 800 km”2 and 1500 km 2 . All the anomalies is considered that its forming relate to batholith and its external contact, so it shows that it has favorite geological conditions for granite type uranium metallogenesis. (authors)

  15. 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...

  16. Petrogenesis of Malaysian tin granites: geochemistry, fractional crystallization, U-Pb zircon geochronology and tectonic setting

    Science.gov (United States)

    Wai-Pan Ng, Samuel; Searle, Mike; Whitehouse, Martin; Chung, Sun-Lin; Ghani, Azman; Robb, Laurence; Sone, Masatoshi; Oliver, Grahame; Gardiner, Nick; Roselee, Mohammad

    2014-05-01

    The Malaysian tin granites forming the backbone of the Thai-Malay Peninsula has been long recognized with two distinct granitic provinces:- 1. Early Permian to Late Triassic Eastern Province with mainly "I-type" (Hbl)-Bt granites with associated Cu-Au deposits, with subordinate Bt granites hosting limited Sn-W deposits, and 2. Late Triassic Main Range Province with mainly "S-type" Bt granites with associated Sn-W deposits, and subordinate (Hbl)-Bt granites. New geochemical data show that Chappell and White's (1974) I-S granite classification adopted in the existing model does not adequately distinguish the granites from one another as previously implied. Trace element geochemistry and Sr-Nd isotopic compositions show that the Malaysian tin granites in both provinces have transitional I-S characteristics. In addition, they inherited within-plate signature from Cambro-Ordovician Gondwana-related source rocks. Previous ages were obtained by whole rock Rb-Sr and biotite K-Ar geochronology in the 70s and 80s, dating methods that may not accurately represent the crystallization age of granites. We re-sampled the entire Malaysian Peninsula and 40 samples were collected for high-precision U-Pb SIMS dating on extracted zircon grains in order to better constrain the magmatic and tectonic evolution of Southeast Asia. The crystallization ages of the Eastern Province granitoids have been constrained ranging from 220 to 290 Ma, while the Main Range (Western) Province granitoids have ages ranging from 200 to 230 Ma. A progressive westward younging trend is apparent across the Eastern Province, but becomes less obvious in the Main Range Province. Our model suggests two east dipping subduction zones. We suggest that subduction roll-back along the Bentong-Raub suture might account for the westward younging trend, in the Eastern province. A second Late Triassic east-dipping subduction zone beneath western Malaysia is proposed in order to explain the "I-type" components to the Main

  17. Strontium isotopes as tracers of water-rocks interactions, mixing processes and residence time indicator of groundwater within the granite-carbonate coastal aquifer of Bonifacio (Corsica, France).

    Science.gov (United States)

    Santoni, S; Huneau, F; Garel, E; Aquilina, L; Vergnaud-Ayraud, V; Labasque, T; Celle-Jeanton, H

    2016-12-15

    This study aims at identifying the water-rock interactions and mixing rates within a complex granite-carbonate coastal aquifer under high touristic pressure. Investigations have been carried out within the coastal aquifer of Bonifacio (southern Corsica, France) mainly composed of continental granitic weathering products and marine calcarenite sediments filling a granitic depression. A multi-tracer approach combining physico-chemical parameters, major ions, selected trace elements, stable isotopes of the water molecule and 87 Sr/ 86 Sr ratios measurements is undertaken for 20 groundwater samples during the low water period in November 2014. 5 rock samples of the sedimentary deposits and surrounding granites are also analysed. First, the water-rock interactions processes governing the groundwater mineralization are described in order to fix the hydrogeochemical background. Secondly, the flow conditions are refined through the quantification of inter aquifer levels mixing, and thirdly, the kinetics of water-rock interaction based on groundwater residence time from a previous study using CFCs and SF 6 are quantified for the two main flow lines. A regional contrast in the groundwater recharge altitude allowed the oxygene-18 to be useful combined with the 87 Sr/ 86 Sr ratios to differentiate the groundwater origins and to compute the mixing rates, revealing the real extension of the watershed and the availability of the resource. The results also highlight a very good correlation between the groundwater residence time and the spatial evolution of 87 Sr/ 86 Sr ratios, allowing water-rock interaction kinetics to be defined empirically for the two main flow lines through the calcarenites. These results demonstrate the efficiency of strontium isotopes as tracers of water-rock interaction kinetics and by extension their relevance as a proxy of groundwater residence time, fundamental parameter documenting the long term sustainability of the hydrosystem. Copyright © 2016

  18. Omphacite and quartz lattice-preferred orientations in the UHP-bearing migmatitic gneisses of the D'Entrecasteaux Islands, Papua New Guinea

    Science.gov (United States)

    Little, T. A.; Hacker, B. R.; Wihare, G.; Brownlee, S. J.; Seward, G.

    2012-12-01

    Lattice Preferred Orientation (LPO) of omphacite and quartz in the gneiss domes of the D'Entrecasteaux Islands, Woodlark Rift shed insight into the geodynamics of the world's youngest (crystallization at 5-8 Ma) UHP terrane. Seven samples of mafic boudins that preserve eclogite-facies assemblages, and 37 samples of quartzofeldspathic and/or migmatitic gneisses that were later strongly retrogressed in the amphibolite-facies were measured by Electron Backscatter Diffraction (EBSD). Omphacite grains in most of the eclogites define a weak Shape Preferred Orientation (SPO) together with a distinct LPO that includes a point maximum of [001] axes and variably girdled distributions of (110) and (010) poles. The LPO data suggest dislocation creep at (U)HP conditions as a result of glide on [001]{110} and [001](100), and a strain ellipsoid between L and LS in shape. Most samples suggest a (U)HP foliation that dipped gently N and an extension direction trending N—possibly in alignment with the dip of the paleosubduction channel. Retrogressed host gneisses surrounding the mafic blocks yield LPOs that transition rapidly with structural depth in the domes. In the relatively chilled and strongly deformed outer carapaces of the domes, quartz [c]-axis LPOs consist of crossed-girdles (mostly) with some cleft girdles and small-circle patterns. Most patterns are symmetrical. These LPOs reflect a dominance of coaxial flow (and plane strain) at temperatures above 400°C. In the deeper, migmatitic cores of the domes, quartz LPOs record activity of prism-[c] slip together with some basal slip. Chessboard subgrains and amoeboid grain boundaries are common, and we infer deformation temperatures of >650°C. There, conjugate ductile shears accomplished a bulk deformation in the core zones that was nearly coaxial, and we infer that horizontal ductile flow thinned the UHP terrane by 10's of km after it had temporarily ponded in the lower crust at 4-2.5 Ma. Quartz LPOs are remarkably weak over

  19. 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.

  20. Trace elements in feldspars and micas in granite pegmatites from northern Minas Gerais

    International Nuclear Information System (INIS)

    Wegner, R.R.

    1983-01-01

    A contribution to the geochemistry of granite pegmatites in Minas Gerais, Brazil is presented. Special emphasis is given to trace element contents in feldspars and muscovites of 25 different pegmatites and their geochemical significance. 180 potassium feldspars 110 albites and 64 muscovites have been analized. It could be demonstrated, that the trace element distributions in feldspars taken along cross-sections through some pegmatite bodies, show some regularities in those, which have a relatively simple mineralization. Other ones with a more complex composition are more characterize by a lack of these conformities. Potassium feldspars from pegmatites with a significant phosphate compound, on the average include more than 0.30% P 2 O 5 . Those of pegmatites with an extend Li-admixture contain more than 90 ppm Li. These observations may be useful to help classificate little known pegmatites in respect to economical purposes. Late formed muscovites from highly differenciated pegmatites contain beyond others - increased contents of Zn and Ga. This, too, may be a useful indicator to the further discovery of these kind of pegmatites, mostly enriched in minerals of economic interest. (Author) [pt

  1. Workability of glass reinforced concrete (GRC) with granite and silica sand aggregates

    Science.gov (United States)

    Moceikis, R.; Kičaitė, A.; Keturakis, E.

    2017-10-01

    Glass fiber reinforced concrete (GRC) opens the door for lightweight and complex shaped innovative construction, adding architectural value to buildings. With panel thickness down to 15 mm, considerable amount of total loads and materials per square meter of facade can be saved, if compared to conventionally used 80 mm thickness outer layer in insulated precast concrete wall elements. Even though GRC is used for over 50 years in such countries as Great Britain, USA and Japan, there are very few examples and little research done in Eastern Europe with this building material. European Commission propagates sustainable design as commitment to energy efficiency, environmental stewardship and conservation. For this reason, GRC plays important role in mowing toward these goals. In this paper, GRC premix recipes including fine granite and silica sands, reinforced with 13mm length alkali resistant glass fibers are investigated. Two CEM I 52,5R cements with different particle sizes were used and severe water dissociation noticed in one of concrete mixes. Cement particle size distribution determined with laser diffraction particle analyser Cilas 1090LD. To determine modulus of rupture (M.O.R.) and limit of proportionality (L.O.P), plates thickness 15 and 20 mm were produced and tested for flexural resistance according to 4-point bending scheme. Concrete workability tests were made according EN 1170-1.

  2. An experimental study of granitic water-saponitic bentonite interaction under hydrothermal conditions

    International Nuclear Information System (INIS)

    Garralon, A.; Cuevas, J.; Leguey, S.

    1994-01-01

    The interaction of a saponitic clay from the Madrid Basin with synthetic groundwater (GW) simulating those from granitic areas is investigated. The experiments performed explore the reaction of clay with GW (1:3 solid to water ratio) at 45, 60 and 90 degrees C. Water extracted from the clay slurries has been analyzed and water of this composition synthesized again to run a new reaction with the original clay (salt concentration process). The clay product of the first reaction was reacted again with GW (leaching process). These reactions were repeated in successive equilibrating steps. Multicationic selectivity coefficients have been calculated. K > Ca > Mg > Na is the order of preference for adsorption by the clay. The selectivity of Ca is highly enhanced in both processes, the clay acting as a true complexing agent for Ca, as calcite controls the carbonate equilibrium. A clear dependence of the exchange constants on temperature with the range explored was not detected. The GW composition evolves from Ca,Na-HCO 3 , to Na,Mg-HCO 3 , (leaching) and NaCl (concentration), the solutions being buffered at pH 8.0. Mechanical properties, clay mineralogy and bulk adsorption properties remained virtually unchanged in the successive one month experiments although a slight decrease in BET specific surface area indicated some sepiolite dissolution at 90 degrees C

  3. Strength and permeability tests on ultra-large Stripa granite core

    International Nuclear Information System (INIS)

    Thorpe, R.; Watkins, D.J.; Ralph, W.E.; Hsu, R.; Flexser, S.

    1980-09-01

    This report presents the results of laboratory tests on a 1 meter diameter by 2 meters high sample of granitic (quartz monzonite) rock from the Stripa mine in Sweden. The tests were designed to study the mechanical and hydraulic properties of the rock. Injection and withdrawal permeability tests were performed at several levels of axial stress using a borehole through the long axis of the core. The sample was pervasively fractured and its behavior under uniaxial compressive stress was very complicated. Its stress-strain behavior at low stresses was generally similar to that of small cores containing single healed fractures. However, this large core failed at a peak stress of 7.55 MPa, much less than the typical strength measured in small cores. The complex failure mechanism included a significant creep component. The sample was highly permeable, with flows-per-unit head ranging from 0.11 to 1.55 cm 2 /sec. Initial application of axial load caused a decrease in permeability, but this was followed by rapid increase in conductivity coincident with the failure of the core. The hydraulic regime in the fracture system was too intricate to be satisfactorily modeled by simple analogs based on the observed closure of the principal fractures. The test results contribute to the data base being compiled for the rock mass at the Stripa site, but their proper application will require synthesis of results from several laboratory and in situ test programs

  4. Guide of Black granite prospect ion for the department of Florida

    International Nuclear Information System (INIS)

    Bossi, J.; Campal, N.

    1989-01-01

    The black granite prospection project is between the government of Canada and Uruguay agreement (Facultad de Agronomia - Universidad de la Republica). The main objective is the location and mapping of black granite veins to obtain potential deposits. The study of the relations between surface and deep features of these veins. The preparation of a guide to exploration and exploitation plan for mining companies. Reinforce the capacity of research in economic geology as well as increasing the exports by resources jobs

  5. 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.

  6. Geochemical geochronology and genesis of granite from Coronel Murta, Northeast of Minas Gerais, Brazil

    International Nuclear Information System (INIS)

    Soares, A.C.P.; Siga Junior, O.

    1987-01-01

    Geological, petrographic, geochemical (including rare-earth elements) and geochronological data of the Coronel Murta (Northeast Minas Gerais State) post-tectonic intrusive alkalic granites were summarized in order to discuss their genesis. This paper shows that Coronel Murta granites were generated by anatexis of dominantly metasedimentary rocks, in an ensialic environment, as the late results of an intraplate A-type subduction during the Brazilian Cycle. (author) [pt

  7. Development of a geophysical methodology from boreholes for the study of granitic formation storage site

    International Nuclear Information System (INIS)

    Le Masne, D.

    1983-01-01

    The aim of this work is the characterization of the fracturation of a granitic formation by the examination of borehole environment. Two types of methods are used. Methods using one borehole only: well logging (electrical and nuclear). Didier logs (electric dipole-dipole), Eric probes (electromagnetic dipole-dipole) and methods between boreholes (grounding). These methods were applied to two boreholes of 500m and 1000 meters drilled into granite at Auriat (France)

  8. Modeling of lung cancer risk due to radon exhalation of granite stone in dwelling houses

    Directory of Open Access Journals (Sweden)

    Akbar Abbasi

    2017-01-01

    Conclusions: The estimated numbers of lung cancer deaths attributable to indoor radon due to granite stones in 2013 were 145 (3.33% and 103 (2.37% for poor and normal ventilation systems, respectively. According to our estimations, the values of 3.33% and 2.37% of lung cancer deaths in 2013 are attributed to radon exhalation of granite stones with poor and normal ventilation systems, respectively.

  9. Geochemical and geochronological study of the non-granitic pegmatite body "La Panchita", Oaxaca state, Southern Mexico

    Science.gov (United States)

    Shchepetilnikova, Valentina; Solé, Jesús; Solari, Luigi; Abdullin, Fanis

    2014-05-01

    The La Panchita pegmatite body intrudes a >10 m thick pyroxenite dike that in turn is cutting the central portion of ~1Ga Oaxacan Complex rocks, Southern Mexico. The Oaxacan Complex is the largest exposure in Mexico of Neoproterozoic basement rocks metamorphosed up to the granulite facies during the Grenville orogeny. This Complex has multiple intrusions of pegmatite bodies along its extension, some mineralogically simple, some complex. As for the mineralogy, the La Panchita pegmatite is distinct from other pegmatites of the Oaxacan Complex. It contains unusual minerals for a pegmatite, like scapolite and calcite, and it is a non-granitic pegmatite, as suggested before. This work presents preliminary geochemical and geochronological results of this pegmatite body and a discussion about its possible origin. The geochronological study shows that the time of emplacement of this pegmatite is 981.4 ± 7.4 Ma and it is post-tectonic with respect to the granulite facies metamorphic event of the Oaxacan Complex. The geochemical study shows that the pegmatite La Panchita formed during the evolution of an anorogenic magmatic source of carbonatitic-alkaline composition related to a post-Grenvillian rifting event. Medium to low-temperature thermochronometers (K-Ar, fission track and U-Th-He) from this pegmatite are under progress and the results will be given at the meeting.

  10. The role of granites for the ore mineralization in South German Variscides

    International Nuclear Information System (INIS)

    Dill, H.G.

    1987-01-01

    Granites are of widespred occurrence in the South German Variscides (F.R. of Germany), the Black Forest (=BF), and the NE Bavarian Basement (=NEBB). These areas are crossed by the Saxothuringian-Moldanubian plate boundary and were also affected by crustal subdulction and nappe tectonism, both of which are thought to be responsible for granitisation and enrichment of Sn, W,U,Au, Sb,Pb,Zn,F, and Ba in veins of different kind. Heat produced by gliding of plates above each other, by decay of radioctive elements in granites as well as set free by the granites themselves caused the above-mentioned elements to be released from their protores, which formed during Late Proterozoic and Early Paleozoic rifting. These hypogene ore mineralizations may be crudely subdivided into thrustbound, granite-related and granite-induced ore deposites. During Tertiary-Quaternary these granites were exposed the pervasive weathering under subtropical conditions, so that ''U yellow ores'' and china clay deposits came into existence. The whole ore mineralization in that region may be explained by a simple four-step model: preconcentration, fracturation, activation and peneplaination. (author) [pt

  11. ASSESSING LAND COVER CHANGES CAUSED BY GRANITE QUARRYING USING REMOTE SENSING

    Directory of Open Access Journals (Sweden)

    R. S. Moeletsi

    2017-11-01

    Full Text Available Dimension stone quarrying in the area between Rustenburg and Brits in the North West Province of South Africa has been in existence for over 70 decades. The unique characteristics of the granite deposits in South Africa resulted in making the country a global producer of the granite rocks. This led to intensified quarrying activities between Rustenburg and Brits town. However, this surface mining method, has a potential to impact the environment in a negative way causing loss in vegetation, depletion of natural resources, loss of scenic beauty and contamination of surface water resources. To assess the land cover changes caused by granite quarrying activities, remotely sensed data in the form of Landsat images between 1998 and 2015 were used. Supervised classification was used to create maps. Accuracy assessment using Google EarthTM as a reference data yielded an overall accuracy of 78 %. The post classification change detection method was used to assess land cover changes within the granite quarries. Granite quarries increased by 1174.86 ha while formation of quarry lakes increased to 5.3 ha over the 17-year period. Vegetation cover decreased by 1308 ha in area while 18.3 ha bare land was lost during the same period. This study demonstrated the utility of remote sensing to detect changes in land cover within granite quarries.

  12. 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%.

  13. Uraniferous alaskitic granites with special reference to the Damara Orogenic Belt

    International Nuclear Information System (INIS)

    Toens, P.D.; Corner, B.

    1980-10-01

    The control and patterns of uranium mineralisation in the alaskitic granites of the Damara Orogenic Belt are discussed. The polyphase Damara metamorphism produced high-grade metamorphic assemblages, migmatites and syn-, late-, and post-tectonic anatectic granites through reactivation of the basement and overlying Damara rocks. During anatexis the incompatible elements, particularly the uranium derived from these formations, were incorporated into the melts which then rose, in an attempt to attain gravitational equilibrium, by varying distances depending on the depth of origin of the melts, on their water content and on the availability of tensional environments. Fractional crystallisation during ascent and increased water content concentrated the uranium into residual melts which finally crystallised as alaskitic pegmatitic granite. Structural episodes played an important part in the emplacement of the uraniferous granites and the presence of marble bands was an important factor in not only providing a structural trap for the alaskitic melts and associated uranium-rich volatiles, but also by leading to the boiling of the magma and the subsequent deposition of uranium. The present-day level of erosion is considered to be an important factor contributing to the preservation of many of the uraniferous granite bodies. In addition it is suggested that secondary enrichment occurring above the water-table in the prevailing desert environment is an important criterion in enriching the tenor of mineralisation to ore grades. The exploration techniques necessary for the location of uraniferous granite bodies are briefly outlined [af

  14. Cordilleran metamorphic core complexes and their uranium favorability. Final report

    International Nuclear Information System (INIS)

    Coney, P.J.; Reynolds, S.J.

    1980-11-01

    The objective of this report is to provide a descriptive body of knowledge on Cordilleran metamorphic core complexes including their lithologic and structural characteristics, their distribution within the Cordillera, and their evolutionary history and tectonic setting. The occurrence of uranium in the context of possibility for uranium concentration is also examined. Chapter 1 is an overview of Cordilleran metamorphic core complexes which describes their physical characteristics, tectonic setting and geologic history. This overview is accompanied by a tectonic map. Chapter 2 is a discussion of the mantled gneiss dome concept. The purpose of including this work is to provide a basic history of this concept and to describe the characteristics and distribution of gneiss domes throughout the world to enable one to compare and contrast them with the metamorphic core complexes as discussed in this report. Some gneiss domes are known producers of uranium (as are also some core complexes). Chapter 3 is an examination of the effects of the core complex process on adjacent sedimentary and volcanic cover terranes. Also included is a discussion of the kinematic significance of these cover terranes as they are related to process within the cores of the complexes. Some of the cover terranes have uranium prospects in them. Chapter 4 is a detailed discussion of uranium in Cordilleran metamorphic core complexes and includes the conceptual basis for the various types of occurrences and the processes that might favor concentration of uranium. The report is supported by a 5-part Appendix. The majority of the core complexes discussed in this report either do not appear or are not recognizable on existing published geologic maps

  15. Polishing Knowledge: A Study of Marble and Granite Processing

    Directory of Open Access Journals (Sweden)

    Simone De Bruim Babisk Mezadre

    2014-07-01

    Full Text Available The aim of this article is to understand the work situations and highlight aspects of the knowledge invested by workers when performing marble and granite processing activities. The survey is qualitative and was based on the reality of a small industrial company that deals with processing activities. The case study was based on theoretical and analytical ergology tools by analyzing the organizational documents and safety and health standards that regulate activity. It involved conducting individual interviews with nine workers, organizing a focus group with these workers, and directly observing work for four months while recording a field notebook. The workers’ experiences in the renormalization of working processes, or the introduction of improvements guided by singular aspects of the local work organization, were identified. The workers, through use of oneself, place more importance on meeting deadlines and production targets than on their own safety. Worker competency is directly related to the professional training obtained on the job and is associated with working experience in the absence of an a priori formal education. This article contributes to the field of organizational studies and human resource management because there is a lack of studies on workers from this field that describe the competencies used in actual work. Thus it may guide theoretical and practical management aspects in such working environments and small businesses regarding safer work organization.

  16. Hydraulic testing in granite using the sinusoidal variation of pressure

    International Nuclear Information System (INIS)

    Black, J.H.; Holmes, D.C.; Noy, D.J.

    1982-09-01

    Access to two boreholes at the Carwynnen test site in Cornwall enabled the trial of a number of innovative approaches to the hydrogeology of fractured crystalline rock. These methods ranged from the use of seisviewer data to measure the orientation of fractures to the use of the sinusoidal pressure technique to measure directional hydraulic diffusivity. The testing began with a short programme of site investigation consisting of borehole caliper and seisviewer logging followed by some single borehole hydraulic tests. The single borehole hydraulic testing was designed to assess whether the available boreholes and adjacent rock were suitable for testing using the sinusoidal method. The main testing methods were slug and pulse tests and were analysed using the fissured porous medium analysis proposed in Barker and Black (1983). Derived hydraulic conductivity (K) ranged from 2 x 10 -12 m/sec to 5 x 10 -7 m/sec with one near-surface zone of high K being perceived in both boreholes. The results were of the form which is typical of fractured rock and indicated a combination of high fracture frequency and permeable granite matrix. The results are described and discussed. (author)

  17. Rock mass characterization for storage of nuclear waste in granite

    International Nuclear Information System (INIS)

    Witherspoon, P.A.; Nelson, P.; Doe, T.; Thorpe, R.; Paulsson, B.; Gale, J.; Forster, C.

    1979-02-01

    The rock mass characterization in granite adjacent to an iron mine at Stripa, Sweden is being carried out by four different methods. The mechanical characterization includes monitoring the responses to thermal loading of jointed rock in situ, and mechanical tests on cores from 25 mm to 1 m in diameter. Geological characterization includes detailed surface mapping, subsurface mapping, and core mapping. Geophysical characterization uses a variety of borehole techniques, with emphasis on sonic methods. The hydrologic characterization is done through injection tests, pump tests, water pressure measurements, and controlled inflow tests to tunnels. Since the data are not yet complete, only tentative conclusions can be drawn regarding the best combinations of techniques for rock-mass characterization. Mapping studies are useful in defining continuity and fracture-system geometry. They do not give aperture, a factor significant in terms of both water flow and the displacements due to heating. Of the geophysical techniques, sonic methods appear most effective in fracture definition; other methods, gamma and neutron particularly, give data on radionuclide and water content and need further analysis with geologic and hydrologic data to determine their significance. Hydrologic work yields primarily aperture data, which with fracture geometry can be used to calculate directional permeabilities. Pressure measurements may provide one means of assessing fracture continuity. Finally, laboratory tests on large cores suggest considerable refinement in testing techniques may be needed before stress-aperture data can be extrapolated from laboratory to field

  18. Inelastic deformations of fault and shear zones in granitic rock

    International Nuclear Information System (INIS)

    Wilder, D.G.

    1986-02-01

    Deformations during heating and cooling of three drifts in granitic rock were influenced by the presence of faults and shear zones. Thermal deformations were significantly larger in sheared and faulted zones than where the rock was jointed, but neither sheared nor faulted. Furthermore, thermal deformations in faulted or sheared rock were not significantly recovered during subsequent cooling, thus a permanent deformation remained. This inelastic response is in contrast with elastic behavior identified in unfaulted and unsheared rock segments. A companion paper indicates that deformations in unsheared or unfaulted rock were effectively modeled as an elastic response. We conclude that permanent deformations occurred in fractures with crushed minerals and fracture filling or gouge materials. Potential mechanisms for this permanent deformation are asperity readjustments during thermal deformations, micro-shearing, asperity crushing and crushing of the secondary fracture filling minerals. Additionally, modulus differences in sheared or faulted rock as compared to more intact rock would result in greater deformations in response to the same thermal loads

  19. Characterization of microbial communities in deep groundwater from granitic rock

    International Nuclear Information System (INIS)

    Jain, D.K.; Stroes-Gascoyne, S.; Providenti, M.; Tanner, C.; Cord, I.

    1997-01-01

    The microbial characteristics of deep granitic nutrient-poor groundwater from two boreholes at the Underground Research Laboratory of Atomic Energy of Canada Limited were studied. Scanning electron microscopy of the groundwater samples revealed significant numbers of bacteria of various sizes and shapes, including spherical, rod, and curved shaped. A few bacteria with appendages were also observed. Significant numbers of bacteria (∼l0 5 /mL) were enumerated using acridine orange (AO) staining. An active microbial population was detected with three direct methods and it ranged from 1 to 83% of the AO count, depending on the method used. Culturable aerobic and anaerobic (including facultative) heterotrophic bacteria ranged from 0.06 to 10.2% and 0.008 to 7.35%, respectively, of the AO count. Denitrifying. N 2 - fixing, sulphate-reducing, and iron-precipitating bacteria were present, but no iron-oxidizing bacteria or methanogens could be detected. Tentative identification of 160 isolates using the Biolog system showed a predominance of three Pseudomonas species, P. fluorescens, P. marginalis, and P. corrugata. Phospholipid fatty acid analysis showed that the bacteria in the groundwater samples faced starvation stress. However, laboratory studies showed that these bacteria can efficiently uptake and mineralize organic substrates when supplied. (author)

  20. Metasomatism along fluid pathways in the ultra-high pressure Svartberget garnet-peridotite (Western Gneiss Region, Norway): Implications for the transport of slab-derived fluids within the mantle wedge

    NARCIS (Netherlands)

    Vrijmoed, J.C.; Austrheim, H.; John, T.; Hin, R.C.; Corfu, F.; Davies, G.R.

    2013-01-01

    Garnet-peridotites often contain veins or layers of pyroxenite and eclogite of uncertain origin. We investigate the Svartberget garnetperidotite from the northernmost ultrahigh-pressure domain in the Western Gneiss Region (WGR) in Norway and show that the observed layering represents a sequence of

  1. Natural organics in groundwaters and their potential effect on contaminant transport in granitic rock

    International Nuclear Information System (INIS)

    Vilks, P.; Bachinski, D.B.; Richer, D.

    1996-07-01

    Naturally occurring organics in groundwaters of the Whiteshell Research Area (WRA) of southern Manitoba and of the Atikokan Research Area of northwestern Ontario were investigated to assess their potential role in radionuclide transport within granite fractures of the Canadian Shield. A survey of dissolved organic carbon (DOC) concentrations, carried out to determine the variability in the organic content of these groundwaters, showed average concentrations in WRA deep groundwaters of 0.8 ± 0.1 mg/L for Fracture Zone 2, 0.8 ± 0.4 mg/L for near-vertical fractures, and 2.3 ± 0.8 mg/L for deeper saline groundwater. Surface waters and near-surface groundwaters had significantly higher DOC with 29.2 ± 0.6 mg/L in streams from the East Swamp. The DOC consisted mainly of hydrophilic neutral compounds 60 to 75%, and hydrophobic and hydrophilic acids 23 to 39%, along with very small amounts of hydrophobic bases and neutrals, and hydrophilic bases. The average complexing capacity of natural organics in WRA deep groundwaters was calculated to be 6.7 x 10 -6 eq/L. The ability of these organics to complex radionuclides was tested using conditional stability constants from the literature for humic complex formation with trivalent, tetravalent, pentavalent and hexavalent actinides. The chemistries of Np(V) and U(VI) were predicted to be dominated by inorganic complexes and not significantly affected by organics. Accurate predictions for AM(III) and Th(IV) could not be made since the literature contains a wide range in values of stability constants for humic complexes with these elements. Surface waters and near-surface groundwaters in many areas of the Canadian Shield contain enough humics to complex a significant fraction of dissolved actinides. Radiocarbon ages of humics from WRA groundwater varied between 3600 and 6200 years before present, indicating that a component of humic substances in deep groundwaters must originate from near-surface waters. 54 refs., 15 tabs., 5

  2. Study on Sr-Nd isotopes of mesozoic-cenozoic granites in Qinghai-Tibetan plateau

    International Nuclear Information System (INIS)

    Qiu Ruizhao; Deng Jinfu; Zhou Su; Xiao Qinghui; Cai Zhiyong

    2003-01-01

    Mesozoic-Cenozoic magmatic activities were intensive in Qinghai-Tibetan plateau. Nd-Sr isotopic compositions of representative granitic plutons in western Qinghai-Tibetan plateau are reported in this paper. Combining with past isotopic data, which has reported in eastern Qinghai-Tibetan plateau, Sr-Nd isotopic compositions and material source and genesis of Mesozoic and Cenozoic granites in Qinghai-Tibetan plateau have been studied. The research result indicates there are three types of granite existing in Qinghai-Tibetan plateau, the granites of Late stage of Yanshan Period which distributing on north and south boundary of Gandes block (namely in north and south granitic belts of Dangdes) and cause of oceanic crust subduction, have ( 87 Sr/ 86 Sr)i of 0.7041-0.7064, ε (Nd) t of +2.5 - +5.7 and TDM age of 312-562 Ma, positive ε Nd, low ( 87 Sr/ 86 Sr)i ratio and young Nd model ages suggest relatively high contents of mantle-derived components in their sources, and this type granite might melt from subduction oceanic crust. The granites occurred intra-Gangdes block which were caused by collision of continent and post-collision, have ( 87 Sr/ 86 Sr)i of 0.706-0.719, ε (Nd) t of -5.3 - -8.3 and TDM age of 1323-1496 Ma, negative ε Nd, relative high ( 87 Sr/ 86 Sr)i ratio with an mid-Proterozoic Nd model ages, suggest granite has the mixing genesis of mantle-derived components and old crustal components in their sources. With relatively small variation range in ε (Nd) t and TDM age, it might imply granitic isotopic source in Gandes block to keep relative homogenization in long period. The granites in Himalayan block which there is not oceanic material to join in melting and to cause of intra-continental subduction, has most ( 87 Sr/ 86 Sr)i ratio more than 0.720, ε (Nd) t of -10.3 - -16.3 and TDM age of 1792-2206 Ma, high ( 87 Sr/ 86 Sr)i ratio, low negative ε (Nd)t with old Nd isotopic model ages and consistent with the Sr, Nd isotopic compositions of basement

  3. Rapakivi Granite: An architectural emblem of St Petersburg and its utilisation in other world cities

    Science.gov (United States)

    Bulakh, Andrey; Gavrilenko, Vladimir; Panova, Helen

    2015-04-01

    The wide-ranging utilisation of Rapakivi Granite in St Petersburg is typified by the the famous Alexander Column, and 114 stone columns of St Isaac's Cathedralas well as the pedestal of the Nicholas I monument, and portals and basements of buildings of the Admiralty, General Staff, Senate and Synod. The stone is also frequently seen among pavement slabs and in parapets of embankments and bridges around the city. This list of examples where Rapakivi Granite has been used could be expanded further. All Rapakivi Granites used in the buildings of St.Petersburg were quarried from the so-called Vyborg massif. At present it has been found that the massif occupies an area of about 18 000 km2. In the past granite of the Vyborg massif was worked from several quarries in the vicinity of Fredrikshamn (Hamina) in Finland for use in St Peterburg. The best known granite quarries are at Piterlaks (Piuterlahti) and Gimmekyul (Hämeenkylä). Sometimes Rapakivi Granite form Finland differs in appearance from typical varieties. Thus columns of a classical portal in the house at N 7 in Pochtamtskaya Street are hewn from this greyish variety. Other examples are the plinth of the General Staff and Trade Store buildings. After the 1960s varieties from the Leningrad district, and Korosten (Ukraine) massifs were used in St Petersburg. Today it is possible to find examples of Rapakivi Granite from Finland in cities in the USA, South Africa, United Kingdom and Germany. It is a long used stone as demonstrated by its cultural heritage. It is also used as an ornamental or decorative stone in modern architecture. References: 1) Bulakh, A.G., Abakumova, N.B., and Romanovsky, J.V. St Petersburg: a History in Stone. 2010. Print House of St Petersburg State University. 173 p. (In English). 2) Tutakova, A.Ya., Romanovskiy, A.Z., Bulakh, A.G., and Leer, V.I. Dimension Stone of the Leningrad Region. Granites of the Karelia Isthmus in Architecture of the Modern St Petersburg. 2011. St Petersburg. 78 p

  4. Mafic and related complexes in Galicia: an excursion guide

    NARCIS (Netherlands)

    Arps, C.E.S.; Calsteren, van P.W.C.; Hilgen, J.D.; Kuijper, R.P.; Tex, den E.

    1978-01-01

    In Galicia occur several polymetamorphic complexes that contain mafic and ultramafic rocks. Mafic volcanics and gabbros are situated in or near the complexes. An episode of metamorphism and granitization encompassed the generation of the volcanics and gabbros. Gravity surveys revealed the existence

  5. Biotite stability in peraluminous granitic melts: Compositional dependence and application to the generation of two-mica granites in the South Bohemian batholith (Bohemian Massif, Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    René, Miloš; Holtz, F.; Cherhui, L.; Beermann, O.; Stelling, J.

    2008-01-01

    Roč. 102, 3-4 (2008), s. 538-553 ISSN 0024-4937 R&D Projects: GA MŠk(CZ) ME 555 Institutional research plan: CEZ:AV0Z30460519 Keywords : S-type granite * experiments * biotite stability Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.303, year: 2008

  6. [Analysis of X-ray fluorescence spectroscopy and plasma mass spectrometry of the Guidong granite body and its implications to granite evolution].

    Science.gov (United States)

    Li, Hong-Wei; Chen, Guo-Neng; Peng, Zhuo-Lun

    2013-07-01

    The Guidong composite granite body (CGB) located in the north Guangdong Province consists of numerous rock bodies formed respectively in the early and late Jurassic and early Cretaceous. Analysis of the granites of different period with X-ray fluorescence spectroscopy and plasma mass spectrometry indicates: (1) From the top of a granite body downwards, the felsic components of rock decrease, while the mafic and sigmaREE, LREE/HREE, (La/Yb)N, as well as delta Eu value increase, suggesting the material differentiation in the in-situ melting of crustal rocks and crystallisation of magma; (2) From old to young of the different period granite-massifs in the Guidong CGB, the felsic compositions totally decrease, and the mafic components, sigmaEE, LREE/HREE, (La/Yb)N, and delta Eu value increase as well, implying multiple crustal melting (remelting) events in the Mesozoic in this area; and (3) Primitive mantle-normalized spider diagram for trace elements of Guidong CGB suggests high maturity of the crust involved in the in-situ melting.

  7. Lithium and boron in late-orogenic granites - Isotopic fingerprints for the source of crustal melts?

    Science.gov (United States)

    Romer, Rolf L.; Meixner, Anette; Förster, Hans-Jürgen

    2014-04-01

    Geochemically diverse late- and post-Variscan granites of the Erzgebirge-Vogtland, the Saxon Granulite Massif, and Thuringia (Germany) formed by anatectic melting of Palaeozoic sedimentary successions and associated mafic to felsic volcanic rocks. The compositional diversity of the least evolved of these granites is largely inherited from the protoliths. We present Li and B-isotopic data of these granites and compare them with the isotopic composition of their protoliths, to investigate whether (i) there exist systematic differences in the Li and B-isotopic composition among different granite types and (ii) Li and B-isotopic compositions provide information on the granite sources complementary to information from the isotopic composition of Sr, Nd, and Pb and the trace-element signatures. Low-F biotite and two-mica granite types have flat upper continental crust (UCC)-normalized trace-element pattern with variable enrichments in Li, Rb, Cs, Sn, and W and depletions in Sr, Ba, and Eu. These signatures are least pronounced for the Niederbobritzsch biotite granite, which has the largest contribution of mafic material, and most pronounced for the two-mica granites. The granites show a relatively narrow range of δ7Li values (-3.0 to -0.5) and a broad range of δ11B values (-13.4 to +20.1). The δ11B values are lower in rocks with distinctly higher contents of Li, Rb, Cs, and Sn. The high δ11B of the Niederbobritzsch granite may be explained by the melting of former altered oceanic crust in its source. Relative to UCC, intermediate-F to high-F low-P granites show strong depletions in Sr, Ba, Eu as well as Zr and Hf, strong enrichments in Li, Rb, and Cs as well as Nb, Sn, Ta, and W, and REE pattern with stronger enrichments for HREE than for LREE. These granites show narrow ranges of δ7Li (-2.0 to +1.6) and δ11B values (-14.7 to -9.1), reflecting the smaller variability of the Li and B-isotopic composition in their source lithologies. The anomalously high δ7Li value

  8. Radon emanation during compression, fracturing and heating of granites

    Science.gov (United States)

    Pili, E.; Nicolas, A.; Girault, F.; Schubnel, A.; Fortin, J.; Passelègue, F. X.; Richon, P.

    2013-12-01

    Radon emanation during compression, fracturing and heating of granites É. Pili1,2, A. Nicolas3, F. Girault3, A. Schubnel3, J. Fortin3, F. Passelègue3, P. Richon1 1CEA, DAM, DIF, F-91297 Arpajon, France 2Institut de Physique du Globe, Sorbonne Paris Cité, 1 rue Jussieu, F-75005 Paris, France 3Ecole Normale Supérieure, 24 rue Lhomond, F-75005 Paris, France Precursory radon emissions have been reported previously in various seismically active areas. Nevertheless such observations, only partially understood, are the subject of much skepticism. Radon-222 is a radioactive gas, daughter of radium-226 from alpha-decay in the uranium-238 decay chain that is naturally present in rocks and soils. Its escape is facilitated by preferential pathways such as fractures. Its half-life is 3.8 days only. As a consequence, radon may accumulate during short period only, and is thought to be released prior, during and after earthquakes as stress is discharged and new fluid pathways are made available. However, the physical processes involved in radon emanation during stress variations remain mostly unknown in the field and poorly studied in the laboratory. Here, we investigate radon emanation from various granite samples: Isla Craig, Westerly, La Peyratte and various leucogranites. Radon emanation and diffusion length, measured first on intact samples, are compared with measurements performed after heating at 850°C. Despite extensive thermal fracturing, radon emanation decreases irreversibly after heating compared to intact sample, and the higher the heating temperature the smaller the radon emanation. This is explained by the disappearance of water-film at grain boundaries, which plays an important role in radon percolation through the porous space, and then, at higher temperatures, by dehydration and melting of biotites where radium is concentrated. The recoil range of radon is likely shorter in melted biotites than in intact ones. The effect of mechanical fracturing on radon

  9. Jurassic high heat production granites associated with the Weddell Sea rift system, Antarctica

    Science.gov (United States)

    Leat, Philip T.; Jordan, Tom A.; Flowerdew, Michael J.; Riley, Teal R.; Ferraccioli, Fausto; Whitehouse, Martin J.

    2018-01-01

    The distribution of heat flow in Antarctic continental crust is critical to understanding continental tectonics, ice sheet growth and subglacial hydrology. We identify a group of High Heat Production granites, intruded into upper crustal Palaeozoic metasedimentary sequences, which may contribute to locally high heat flow beneath the West Antarctic Ice Sheet. Four of the granite plutons are exposed above ice sheet level at Pagano Nunatak, Pirrit Hills, Nash Hills and Whitmore Mountains. A new Usbnd Pb zircon age from Pirrit Hills of 178.0 ± 3.5 Ma confirms earlier Rbsbnd Sr and Usbnd Pb dating and that the granites were emplaced approximately coincident with the first stage of Gondwana break-up and the developing Weddell rift, and 5 m.y. after eruption of the Karoo-Ferrar large igneous province. Aerogeophysical data indicate that the plutons are distributed unevenly over 40,000 km2 with one intruded into the transtensional Pagano Shear Zone, while the others were emplaced within the more stable Ellsworth-Whitmore mountains continental block. The granites are weakly peraluminous A-types and have Th and U abundances up to 60.7 and 28.6 ppm respectively. Measured heat production of the granite samples is 2.96-9.06 μW/m3 (mean 5.35 W/m3), significantly higher than average upper continental crust and contemporaneous silicic rocks in the Antarctic Peninsula. Heat flow associated with the granite intrusions is predicted to be in the range 70-95 mW/m2 depending on the thickness of the high heat production granite layer and the regional heat flow value. Analysis of detrital zircon compositions and ages indicates that the high Th and U abundances are related to enrichment of the lower-mid crust that dates back to 200-299 Ma at the time of the formation of the Gondwanide fold belt and its post-orogenic collapse and extension.

  10. Magnetic fabric, shape preferred orientation and regional strain in granitic rocks

    Science.gov (United States)

    Sen, Koushik; Mamtani, Manish A.

    2006-10-01

    Since granites do not preserve easily mappable foliations, lineations, and strain markers, determining the degree of shape preferred orientation (SPO) in them is challenging. The aim of this paper is to present a methodology for determining variation in the degree of SPO in granites and to test the feasibility of correlating the same with regional strain. The case of the Godhra Granite located in the southern parts of Aravalli Mountain Belt (India) is taken as an example. Degree of SPO is determined using two different techniques (a) anisotropy of magnetic susceptibility (AMS) and (b) strength of mineral lineation determined by calculating the concentration parameter ( κ) of von Mises distribution by digital image analysis of biotite ( κbi) and feldspar ( κf) in thin sections prepared parallel to the magnetic foliation plane. SPO data obtained using the above two techniques from 20 samples distributed across the entire granite are analysed. Samples with a higher κ also have a stronger magnetic fabric (magnetic lineation, L and degree of magnetic anisotropy P'). Also, the degree of SPO is greater for granites from the southern parts as compared to the northern parts. It is argued that this variation in degree of SPO cannot be attributed to rheological differences or strain resulting from difference in aspect ratios. Regional strain is inferred as the dominant factor. Since the emplacement of the Godhra Granite is synchronous with the tectonic rejuvenation along the Central Indian Tectonic Zone (CITZ) that lies to its south, the higher degree of SPO in the southern parts is attributed to its proximity to the CITZ. Whilst caution needs to be exercised to directly apply magnetic data as a measure of strain-intensity on a regional scale, it can be a useful guide to select samples for detailed SPO analysis using some alternative technique, especially for granites and other magmatic rocks that are devoid of mesoscopic strain markers.

  11. 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

  12. Petrogenesis of Karamaili alkaline A-type granites from East Junggar, Xinjiang (NW China) and their relationship with tin mineralization

    International Nuclear Information System (INIS)

    Su Yuping; Tang Hongfeng; Liu Congqiang; Hou Guangshun; Cong Feng; Sylvester, Paul J.; Qu Wenjun

    2007-01-01

    Several types of granites including alkaline granites and alkali feldspar granites are distributed in the Karamaili tectonic belt of East Junggar, Xinjiang, China. Some medium-small tin deposits are located within or near the contact zones of the granitic intrusions. The alkaline granites share all the features commonly observed in peralkaline A-type granites. They contain alkalic mafic minerals such as riebeckite and aegirine; have high contents of SiO 2 , alkalis, Rb, Th, Zr, Hf, REE (except Eu), and high ratios of FeO/MgO and Ga/Al; and show strong depletions in Ba, Sr, Eu in the spidergrams. Laser ablation-ICPMS U-Pb zircon geochronology indicates a crystallization age of ca. 305 Ma for the granites; TIMS analyses of the granites found high ε Nd (T) values of +5.9 to +6.5. Considering their geochemical features, alkaline granites most likely formed by fractional crystallization of graodioritic magmas, which were probably produced by partial melting of lower crustal basaltic to andesitic rocks formed from oceanic crustal materials that were deeply buried during late Palezoic subduction and accretion. Six molybdenite samples from the Sareshike tin deposit in East Junggar yielded an isochron age of 307±11 Ma (2σ) and a weighted mean model age of 306.5±3.4 Ma, consistent with zircon U-Pb ages of the alkaline granites. Low Re contents (0.323-0.961 ppm) in the molybdenite suggest that they originated from crustal sources related to the alkaline granites. Considering their identical ages, close spatial distribution, and similar sources, we argue that the A-type granites have a genetic relationship with the tin mineralization, and that the same association may be important elsewhere. (author)

  13. U-Pb ages and Nd isotope characteristics of the lateorogenic, migmatizing microcline granites in southwestern Finland

    Directory of Open Access Journals (Sweden)

    Matti Kurhila

    2005-01-01

    Full Text Available U-Pb ages and whole-rock Nd isotope data have been obtained from the Paleoproterozoic lateorogenic migmatizing microcline granites of southwestern Finland. Isotope dilution and ion microprobe U-Pb data on zircons and monazites show that the age spectrum of these granites is at least 1.85-1.82 Ga. Commonly, zircons and monazites record the same ages. The age variation in the Veikkola granite area is of the order of 25 Ma and indicates that this seemingly homogeneous granite consists of two separate intrusions. The zircons of the lateorogenic granites are pervasively altered and conventional U-Pb results are commonly discordant. The ion microprobe studies reveal that the granites contain very few inherited zircons with preserved original U-Pb isotope ratios, with the exception of the Oripää granite. Initial εNd values, mostly in the range of ‑0.5 to ‑1.0, imply a moderate input of older crustal material into most of the lateorogenic granites. A shift from more juvenile to less radiogenic Nd isotope composition is observed from north to south, and the variation pattern of εNd values of the lateorogenic granites is thus similar to that of the surrounding synorogenic granitoid rocks.

  14. Hydrothermal alteration and permeability changes in granitic intrusions related to Sn-W deposits : case study of Panasqueira (Portugal)

    Science.gov (United States)

    Launay, Gaetan; Sizaret, Stanislas; Guillou-Frottier, Laurent; Gloaguen, Eric; Melleton, Jérémie; Pichavant, Michel; Champallier, Rémi; Pinto, Filipe

    2017-04-01

    The Panasqueira Sn-W deposit occurs as a dense network of flat wolframite and cassiterite-bearing quartz veins concentrated in the vicinity of a hidden greisen cupola, and to a lesser extent as disseminated cassiterites in the greisen. Previous studies (Thadeu 1951; 1979) have suggested that the Panasqueira deposit is genetically related to magmatic activity for which the most part is unexposed, and being only represented by the greisen cupola. Hydrothermal fluid circulation during the final stages of granite crystallisation has probably led to the greisenisation of the cupola followed by the deposition of the mineralization in the veins system. Mineral replacement reactions that occurred during the greisenisation could affect rock properties (porosity, density and permeability) which control fluid circulation in the granite. This study aims to investigate effects of greisenisation reactions on the dynamic (time varying) permeability that ultimately leads to fluid circulation in the greisen cupola. To do so, petrological study and experimental determinations of hydrodynamic features (porosity and permeability) for different granite alteration levels and petrographic types (unaltered granite to greisen) are combined and then integrated in coupled numerical models of fluid circulation around the granitic intrusion. Greisen occurs in the apical part of the granitic body and results in the pervasive alteration of the granite along the granite-schist contact. This greisen consists mainly of quartz and muscovite formed by the replacement of feldspars and bleaching of biotites of the initial granite. Otherwise, greisen is generally vuggy which suggests a porosity increase of the granite during hydrothermal alteration processes. This porosity increase has a positive effect on the permeability of the granitic system. Indeed, experimental measurements of permeability with the Paterson press indicate that the initial granite is impermeable (10-20 m2) whereas the greisen is

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

    OpenAIRE

    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 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 monz...

  16. Late Mesoproterozoic to Early Paleozoic history of metamorphic basement from the southeastern Chiapas Massif Complex, Mexico, and implications for the evolution of NW Gondwana

    Science.gov (United States)

    Weber, Bodo; González-Guzmán, Reneé; Manjarrez-Juárez, Román; Cisneros de León, Alejandro; Martens, Uwe; Solari, Luigi; Hecht, Lutz; Valencia, Victor

    2018-02-01

    In this paper, U-Pb zircon geochronology, Lu-Hf and Sm-Nd isotope systematics, geochemistry and geothermobarometry of metaigneous basement rocks exposed in the southeastern Chiapas Massif Complex are presented. Geologic mapping of the newly defined "El Triunfo Complex" located at the southeastern edge of the Chiapas Massif reveals (1) partial melting of a metamorphic basement mainly constituted by mafic metaigneous rocks (Candelaria unit), (2) an Ediacaran metasedimentary sequence (Jocote unit), and (3) occurrence of massif-type anorthosite. All these units are intruded by undeformed Ordovician plutonic rocks of the Motozintla suite. Pressure and temperature estimates using Ca-amphiboles, plagioclase and phengite revealed prograde metamorphism that reached peak conditions at 650 °C and 6 kbar, sufficient for partial melting under water saturated conditions. Relict rutile in titanite and clinopyroxene in amphibolite further indicate a previous metamorphic event at higher P-T conditions. U-Pb zircon ages from felsic orthogneiss boudins hosted in deformed amphibolite and migmatite yield crystallization ages of 1.0 Ga, indicating that dry granitic protoliths represent remnants of Rodinia-type basement. Additionally, a mid-Tonian ( 920 Ma) metamorphic overprint is suggested by recrystallized zircon from a banded gneiss. Zircon from folded amphibolite samples yield mainly Ordovician ages ranging from 457 to 444 Ma that are indistinguishable from the age of the undeformed Motozintla plutonic suite. Similar ages between igneous- and metamorphic- zircon suggest a coeval formation during a high-grade metamorphic event, in which textural discrepancies are explained in terms of differing zircon formation mechanisms such as sub-solidus recrystallization and precipitation from anatectic melts. In addition, some amphibolite samples contain inherited zircon yielding Stenian-Tonian ages around 1.0 Ga. Lu-Hf and Sm-Nd isotopes and geochemical data indicate that the protoliths of

  17. Smolt monitoring at the head of lower granite reservoir and lower Granite Dam, annual report 1999 operations.; ANNUAL

    International Nuclear Information System (INIS)

    United States. Bonneville Power Administration. Division of Fish and Wildlife; Idaho. Dept. of Fish and Game.

    2001-01-01

    This project monitored the daily passage of chinook salmon Oncorhynchus tshawytscha, steelhead trout O. mykiss, and sockeye salmon smolts O. nerka during the 1999 spring out-migration at migrant traps on the Snake River and Salmon River. All hatchery chinook salmon released above Lower Granite Dam were marked with a fin clip in 1999. Total annual hatchery chinook salmon catch at the Snake River trap was 440% of the 1998 number. The wild chinook catch was 603% of the previous year's catch. Hatchery steelhead trout catch was 93% of 1998 numbers. Wild steelhead trout catch was 68% of 1998 numbers. The Snake River trap collected 62 age-0 chinook salmon. During 1998 the Snake River trap captured 173 hatchery and 37 wild/natural sockeye salmon and 130 hatchery coho salmon O. kisutch. 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 high flows. Trap operations began on March 14 and were terminated for the season due to high flows on May 25. The trap was out of operation for 18 d during the season due to high flow and debris. Hatchery chinook salmon catch at the Salmon River trap was 214%, and wild chinook salmon catch was 384% of 1998 numbers. The hatchery steelhead trout collection in 1999 was 210% of the 1998 numbers. Wild steelhead trout collection in 1999 was 203% of the 1998 catch. Trap operations began on March 14 and were terminated for the season due to high flows on May 21. The trap was out of operation for 17 d during the season due to high flow and debris

  18. Smolt monitoring at the head of Lower Granite Reservoir and Lower Granite Dam, annual report 1997 operations.; ANNUAL

    International Nuclear Information System (INIS)

    United States. Bonneville Power Administration. Division of Fish and Wildlife.

    1999-01-01

    This project monitored the daily passage of chinook salmon Oncorhynchus tshawytscha and steelhead trout O. mykiss smolts during the 1997 spring out-migration at migrant traps on the Snake River and Salmon River. All hatchery chinook salmon released above Lower Granite Dam were marked with a fin clip in 1997. Total annual hatchery chinook salmon catch at the Snake River trap was 49% of the 1996 number but only 6% of the 1995 catch. The wild chinook catch was 77% of the 1996 but was only 13% of 1995. Hatchery steelhead trout catch was 18% of 1996 numbers but only 7% of the 1995 numbers. Wild steelhead trout catch was 22% of 1996 but only 11% of the 1995 numbers. The Snake River trap collected eight age-0 chinook salmon and one sockeye/kokanee salmon O. nerka. 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 high flows. Trap operations were terminated for the season due to high flows and trap damage on May 8 and were out of operation for 23 d due to high flow and debris. Hatchery chinook salmon catch at the Salmon River trap was 37% and wild chinook salmon catch was 60% of 1996 numbers but only 5% and 11% of 1995 catch, respectively. The 1997 hatchery steelhead trout collection was 13% of the 1996 catch and 32% of the 1995 numbers. Wild steelhead trout collection in 1997 was 21% of the 1996 catch and 13% of the 1995 numbers. Trap operations were terminated for the season due to high flows and trap damage on May 7 and were out of operation for 19 d due to high flow and debris

  19. U-Pb ages in zircon of some classic granites from the Borborema province

    International Nuclear Information System (INIS)

    Neves, Benjamin Bley de Brito; Basei, Miguel Angelo Stipp; Passarelli, Claudia Regina; Santos, Edilton Jose dos

    2003-01-01

    The Neoproterozoic evolution of the Borborema Province in the east-northeast part of the South American platform exhibits remarkable, much studied granitic plutonism. In 1967 F. F. Almeida and co-workers discriminated a series of granitic typologies as 'Conceicao type', 'Itaporanga type' etc, mostly based upon general geological features and petrographic grounds. This preliminary classification has somehow been maintained in all subsequent papers up to now, despite all the newly observed plutons and the newly generated tectonic, geochemical and isotopic data since then. Samples of these classical types of granites from their type-localities were analyzed geo chronologically using the U-Pb method in zircons in response to the felt needs of the geological community, because previous age-determinations involved less accurate methods. The new data have been added to all other preexisting U-Pb data (from other granitic bodies) obtained over the last decade, making it possible to recognize three main stages of granitic magmatism for the Borborema Province: 650-625 Ma, 580-570 Ma and 545-520 Ma. The last group of dates is closely association with the escape tectonics of the Brasiliano-Pan African collage, which preceded the assembly of the super continental landmass of Western Gondwana. (author)

  20. Permeability of Granite Including Macro-Fracture Naturally Filled with Fine-Grained Minerals

    Science.gov (United States)

    Nara, Yoshitaka; Kato, Masaji; Niri, Ryuhei; Kohno, Masanori; Sato, Toshinori; Fukuda, Daisuke; Sato, Tsutomu; Takahashi, Manabu

    2017-11-01

    Information on the permeability of rock is essential for various geoengineering projects, such as geological disposal of radioactive wastes, hydrocarbon extraction, and natural hazard risk mitigation. It is especially important to investigate how fractures and pores influence the physical and transport properties of rock. Infiltration of groundwater through the damage zone fills fractures in granite with fine-grained minerals. However, the permeability of rock possessing a fracture naturally filled with fine-grained mineral grains has yet to be investigated. In this study, the permeabilities of granite samples, including a macro-fracture filled with clay and a mineral vein, are investigated. The permeability of granite with a fine-grained mineral vein agrees well with that of the intact sample, whereas the permeability of granite possessing a macro-fracture filled with clay is lower than that of the macro-fractured sample. The decrease in the permeability is due to the filling of fine-grained minerals and clay in the macro-fracture. It is concluded that the permeability of granite increases due to the existence of the fractures, but decreases upon filling them with fine-grained minerals.

  1. 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.

  2. Permeability of Granite Including Macro-Fracture Naturally Filled with Fine-Grained Minerals

    Science.gov (United States)

    Nara, Yoshitaka; Kato, Masaji; Niri, Ryuhei; Kohno, Masanori; Sato, Toshinori; Fukuda, Daisuke; Sato, Tsutomu; Takahashi, Manabu

    2018-03-01

    Information on the permeability of rock is essential for various geoengineering projects, such as geological disposal of radioactive wastes, hydrocarbon extraction, and natural hazard risk mitigation. It is especially important to investigate how fractures and pores influence the physical and transport properties of rock. Infiltration of groundwater through the damage zone fills fractures in granite with fine-grained minerals. However, the permeability of rock possessing a fracture naturally filled with fine-grained mineral grains has yet to be investigated. In this study, the permeabilities of granite samples, including a macro-fracture filled with clay and a mineral vein, are investigated. The permeability of granite with a fine-grained mineral vein agrees well with that of the intact sample, whereas the permeability of granite possessing a macro-fracture filled with clay is lower than that of the macro-fractured sample. The decrease in the permeability is due to the filling of fine-grained minerals and clay in the macro-fracture. It is concluded that the permeability of granite increases due to the existence of the fractures, but decreases upon filling them with fine-grained minerals.

  3. High radiogenic heat-producing Caenozoic granites: implications for the origin of Quman geothermal field in Taxkorgan, northwestern China

    Science.gov (United States)

    Shuai, W.; Shihua, Q.

    2017-12-01

    As a new found geothermal field, Quman geothermal field (Taxkorgan, China) holds a wellhead temperature of 144 ° and a shallow buried depth of heat reservoir. The heat source of the geothermal field is thought to be the heat flow from the upper mantle, which is disputable with the average Pamir Moho depth of 70 km. The new geochemical data of Taxkorgan alkaline complex, which is located to the west of the geothermal field and is exposed for 60 km along the western side of the Taxkorgan Valley, shed a light on the origin of Quman geothermal field. Together with the lithological association, the geochemical results present that Taxkorgan alkaline complex are mainly composed of alkaline syenites and subalkaline granitoids. Based on the contents of Th, U and K of 25 rock samples, the average radioactive heat generation of the complex (9.08 μW/m3) is 2 times of the standard of high heat production granites (HHPGs) (5 μW/m3), and 4 times of the average upper continental crust (UCC) heat production (2.7 μW/m3). According to U-Pd dating of zircon in aegirine-augite syenite, the crystallization age of the complex is 11 Ma. The complex has incompatible element abundances higher than generally observed for the continental crust, therefore a mantle source should be considered. The results of apatite fission track ange and track length of the complex indicate a low uplift rate (0.11 mm/a) in 3 5 Ma and a high uplift rate (2 3 mm/a) since ca. 2Ma, which indicates a low exposed age of the complex. Therefore, combined with previous studies, we propose that radioactive heat production of the complex and afterheat of magma cooling are the heat source of Quman geothermal field. With a shallow buried heat source, the geothermal field is potential for EGS development.

  4. Mafic inclusions in Yosemite granites and Lassen Pk lavas: records of complex crust-mantle interactions

    Energy Technology Data Exchange (ETDEWEB)

    Reid, J.B. Jr.; Flinn, J.E.

    1985-01-01

    This study compares three small-scale magmatic systems dominated by mafic/felsic interaction that appear to be analogs to the evolution of their larger host systems: mafic inclusions from modern Lassen Pk lavas along with inclusions and related synplutonic dike materials from granitoids in the Tuolumne Intrusive Series. Each system represents quickly chilled mafic melt previously contaminated by digestion of rewarmed, super-solidus felsic hosts. Contaminants occur in part as megacrysts of reworked oligoclase with lesser hb and biot. Within each group MgO-variation diagrams for Fe, Ca, Ti, Si are strikingly linear (r>.96); alkalis are decidedly less regular, and many hybrid rocks show a curious, pronounced Na enrichment. Field data, petrography, and best fit modeling suggests this may result from flow concentration of oligoclase xenocrysts within contaminated synplutonic dikes, and is preserved in the inclusions when dike cores chill as pillows in their felsic host. Dissolution of mafic inclusions erases these anomalies and creates a more regular series of two-component mafic-felsic mixtures in the large host system. The inclusions and dikes thus appear to record a variety of late-stage mafic-felsic interactive processes that earlier and on a larger scale created much of the compositional variety of their intermediate host rocks.

  5. Petrogenesis of Mesozoic granites in the Xitian, South China: Evidence from whole-rock geochemistry and zircon isotopes

    Science.gov (United States)

    Liu, Q.; Sun, J.; He, M.; Hou, Q.; Niu, R.

    2017-12-01

    Mesozoic granitoids are widespread in southeastern China, which accompanied with lots of world-famous polymetallic deposits. The mineralization is believed to be related to the Mesozoic granitic magmatism. However, the petrogenesis of these granites and their relation to the mineralization are still debated. As a typical granitic pluton, Xitian granites from the eastern Hunan Province are formed during this period and associated with tungsten-tin deposit. Whole-rock geochemical, SIMS zircon geochronology and oxygen isotopes, as well as LA-ICPMS zircon Lu-Hf isotopic analyses, were carried out on a suite of rocks from Xitian granitic pluton to constrain their magmatic sources and petrogenesis. Xitian granitic pluton is mainly composed of biotite adamellite, biotite granite, fine-grained granite. SIMS and LA-ICPMS U-Pb dating of zircons indicate that there are two episodes of these rocks, i.e., Late Triassic granites (227-233Ma) and Late Jurassic granites (150-154Ma). The Xitian granites are silica-rich, potassic and weakly peraluminous. Petrographic and geochemical features show that they are highly fractionated I-type granites. The combined elemental and isotopic results indicated that the Late Triassic granite in Xitian area experienced a process of crystal fractionation of crustal-derived magmas coupled with strong assimilation of the surrounding rocks. The occurrence of Jurassic granitoids in Xitian area is attributed to ascending of mantle-derived magmas, which provide heat for partial melting of crustal materials. The Late Jurassic granite may be derived from juvenile crust or partial melting of ancient crustal rocks, whereas high degrees of crystal fractionation further enriched tungsten-tin in the evolved granitic rocks. This work was financially supported by the Research Cooperation between Institute and University of Chinese Academy of Sciences grant (Y552012Y00), Public Welfare Project of the Ministry of land and Resources of China (201211024

  6. Petrological and geochemical evolution of the Kymi stock, a topaz granite cupola within the Wiborg rapakivi batholith, Finland

    Science.gov (United States)

    Haapala, Ilmari; Lukkari, Sari

    2005-03-01

    The 6×3 km Kymi monzogranite stock represents the apical part of an epizonal late-stage pluton that was emplaced within the 1.65 to 1.63 Ga Wiborg rapakivi batholith. The stock has a well-developed zonal structure, from the rim to the center: stockscheider pegmatite, equigranular topaz granite, porphyritic topaz granite. The contact between the two granites is usually gradational within a few centimeters, but local inclusions of the porphyritic granite in the equigranular granite indicate that the latter solidified later. Hydrothermal greisen and quartz veins, some of which contain genthelvite, beryl, wolframite, cassiterite, and sulfides, cut the granites of the stock and the surrounding country rocks. The equigranular granite contains 1 to 4 vol.% topaz, and its biotite is lithian siderophyllite; the porphyritic granite has 0 to 3 vol.% topaz, and the mica is siderophyllite. The equigranular granite is geochemically highly evolved with elevated Li, Rb, Ga, Ta, and F, and very low Ba, Sr, Ti, and Zr. The REE patterns show deep negative Eu anomalies and tetrad effects indicating extreme magmatic fractionation and aqueous fluid-rock interaction. The zonal structure of the stock is interpreted as a result of differentiation within the magma chamber. Internal convection in the crystallizing magma chamber and upward flow of residual melt as a boundary layer along sloping contacts resulted in accumulation of a layer of highly evolved, volatile-rich magma in the apical part of the chamber. Crystallization of this apical magma produced the stockscheider pegmatite and the equigranular granite; the underlying crystal mush solidified as the porphyritic granite. Much of the crystallization took place from volatile-saturated melt, and episodic voluminous degassing expelled fluids into opened fractures where they or their derivatives reacted with country rocks and caused alteration and mineralization.

  7. Quantitative determination and monitoring of water distribution in Aespoe granite

    International Nuclear Information System (INIS)

    Zimmer, U.

    1998-01-01

    To identify possible zones of two-phase-flow and the extension of the excavation disturbed zone, geoelectric measurements are conducted in the ZEDEX- and the DEMO-tunnel. The electric resistivity of a hard rock is usually determined by its water content, its water salinity and its porosity structure. By calibration measurements of the resistivity on rocks with well known water content, a relation between resistivity and water content for Aespoe granite is determined. This relation is used to correlate the in-situ resistivity with the water content of the rock. To determine the in-situ resistivity between the ZEDEX- and the DEMO-tunnel an electrode array of nearly 300 electrodes was installed along the tunnel walls and in one borehole. With a semiautomatic recording unit which is operated by a telephone connection from the GRS-office in Braunschweig/Germany, the resistivity is monitored between and around the tunnels. To correlate the resistivity with the water content, the measured apparent resistivity has to be converted into a resistivity model of the underground. Since many thin water bearing fractures complicate this inversion process, the accuracy and resolution of the different inversion programs are checked before their application to the data. It was found that an acceptable quantitative reconstruction of the resistivity requires the integration of geometric information about the fracture zones into the inversion process. For a rough estimation of the position of possible fracture zones, a simple inversion without any geometric boundary conditions can be used. Since the maximum investigation area is limited along a single tunnel for profile measurements, tomographic measurements were also applied to estimate the resistivity distribution between the ZEDEX- and the DEMO-tunnel. These tomographic measurements have a lower resolution than the profile measurements due to the required large computer power, but result in reconstructions that give an estimate of

  8. 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

  9. Geology and environmental impact of artisanal gold mining around ...

    African Journals Online (AJOL)

    Geology and effect of artisanal gold mining was investigated in Kataeregi and environ, North-central Nigeria with the aim of determining its host rock and assessing the impact of such activity on the surrounding. Geological field mapping show the area comprise of the Migmatite-Gneiss complex, Schist, Granite and ...

  10. Planning and drilling geothermal energy extraction hole EE-2: a precisely oriented and deviated hole in hot granitic rock

    Energy Technology Data Exchange (ETDEWEB)

    Helmick, C.; Koczan, S.; Pettitt, R.

    1982-04-01

    During the preceding work (Phase I) of the Hot Dry Rock (HDR) Geothermal Energy Project at Fenton Hill, two holes were drilled to a depth of nearly 3048 m (10,000 ft) and connected by a vertical hydraulic fracture. In this phase, water was pumped through the underground reservoir for approximately 417 days, producing an energy equivalent of 3 to 5 MW(t). Energy Extraction Hole No. 2 (EE-2) is the first of two deep holes that will be used in the Engineering-Resource Development System (Phase II) of the ongoing HDR Project of the Los Alamos National Laboratory. This phase of the work consists of drilling two parallel boreholes, inclined in their lower, open-hole sections at 35/sup 0/ to the vertical and separated by a vertical distance of 366 m (1200 ft) between the inclined parts of the drill holes. The holes will be connected by a series of vertical, hydraulically produced fractures in the Precambrian granitic rock complex. EE-2 was drilled to a depth of 4660 m (15,289 ft), where the bottom-hole temperature is approximately 320/sup 0/C (608/sup 0/F). Directional drilling techniques were used to control the azimuth and deviation of the hole. Upgrading of the temperature capability of existing hardware, and development of new equipment was necessary to complete the drilling of the hole in the extremely hot, hard, and abrasive granitic formation. The drilling history and the problems with bits, directional tools, tubular goods, cementing, and logging are described. A discussion of the problems and recommendations for overcoming them are also presented.

  11. Coupled THMC modelling of single fractures in novaculite and granite for DECOVALEX-2015

    Science.gov (United States)

    Bond, A.; Chittenden, N.; Fedors, R. W.; Lang, P. S.; McDermott, C.; Neretnieks, I. E.; Pan, P.; Šembara, J.; Brusky, I.; Watanabe, N.; Lu, R.; Yasuhara, H.

    2015-12-01

    The host rock immediately surrounding a nuclear waste repository has the potential to undergo a complex set of physical and chemical processes starting from construction of the facility until many years after completion. Understanding the relevant processes of fracture evolution may be key to supporting the attendant safety arguments for such a facility. In the present phase of the international research project DECOVALEX, the experimental work of Yasuhara et al [1,2] has been examined, wherein artificial fractures in novaculite and granite are subject to a mechanical confining pressure, variable fluid flows and different applied temperatures. Differential pressures across the samples were measured to determine permeability and hence hydraulic aperture evolution, while at the same time the chemical composition of the outflows were continually sampled. For the novaculite experiments, the fracture surfaces' topography were characterised using a high-resolution laser profilometer (see Figure 1), and post-experimental characterisation of the aperture was performed using a Wood's metal fracture cast. This paper presents a synthesis of the ongoing work of six separate research teams. A range of approaches are presented including 2D and 3D high resolution coupled THMC models. Homogenised 'single compartment' models of the fracture have also been adopted, attempting to upscale the processes so that they could be used in larger network or effective continuum models. Particular attention is given to the competing roles of aqueous geochemistry, pressure solution, stress corrosion and pure mechanics in order to reproduce the experimental observations. The results of the work show that while good, physically plausible representations of the experiment can be obtained, there is considerable uncertainty in the relative importance of the various processes and that the parameterisation of these processes can be closely linked to the physical interpretation of the fracture surface

  12. Origins of igneous microgranular enclaves in granites: the example of Central Victoria, Australia

    Science.gov (United States)

    Clemens, J. D.; Elburg, M. A.; Harris, C.

    2017-10-01

    To investigate their genesis and relations with their host rocks, we study igneous microgranular enclaves (IMEs) in the c. 370 Ma, post-orogenic, high-level, felsic plutons and volcanic rocks of Central Victoria, Australia. The IMEs are thermally quenched magma globules but are not autoliths, and they do not form mixing series with their host magmas. These IMEs generally represent hybrids between mantle-derived magmas and very high- T crust-derived melts, modified by fractionation, ingestion of host-derived crystals and, to a lesser extent, by chemical interactions with their hosts. Isotopic and elemental evidence suggests that their likely mafic progenitors formed by partial melting of subcontinental mantle, but that the IME suites from different felsic host bodies did not share a common initial composition. We infer that melts of heterogeneous mantle underwent high- T hybridisation with melts from a variety of crustal rocks, which led to a high degree of primary variability in the IME magmas. Our model for the formation of the Central Victorian IMEs is likely to be applicable to other occurrences, especially in suites of postorogenic granitic magmas emplaced in the shallow crust. However, there are many different origins for the mingled magma globules that we call IMEs, and different phenomena seem to occur in differing tectonic settings. The complexity of IME formation means that it is difficult to unravel the petrogenesis of these products of chaotic magma processes. Nevertheless, the survival of fine-grained, non-equilibrium mineralogy and texture in the IMEs suggests that their tenure in the host magmas must have been geologically brief.

  13. Microstructural variation of vitrified floor tile incorporated with granitic rock waste

    International Nuclear Information System (INIS)

    Souza, A.J.; Holanda, J.N.F.

    2009-01-01

    The ornamental rock industry from Northwest Fluminense generates huge amounts of wastes in the form of a fine powder. These wastes are deposited in nature without any care about environmental degradation, which can cause damage to public health, pollution of the natural water sources, and silted banks of rivers. In addition, they also can to affect the landscape aesthetically. In this work was used a granitic rock waste from Santo Antonio de Padua-RJ. This waste is rich in alkaline oxides, which promote the formation of liquid phase and assist the densification of traditional ceramics. The ceramic bodies with up to 47.5% granitic rock waste were pressed at 50 MPa. The ceramic pieces were fired at 1250 deg C. The evolution of sintered microstructure was evaluated by scanning electron microscopy and X-ray diffraction. The results showed that the granitic rock waste influences significantly the microstructure of the sintered ceramic bodies. (author)

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

    Science.gov (United States)

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

    2014-10-24

    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.

  15. 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.

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

    International Nuclear Information System (INIS)

    Rivas, T.; Lopez, A.J.; Ramil, A.; Pozo, S.; Fiorucci, M.P.; Silanes, M.E. López de; García, A.; Aldana, J. R. Vazquez de; Romero, C.; Moreno, P.

    2013-01-01

    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 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.

  17. 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.

  18. High radioactive heat-producing, economically potential granites around Jodhpur city, Malani Igneous Suite, Northwestern India

    International Nuclear Information System (INIS)

    Shrivastava, K.L.; Prajapat, Tina; Mathur, Anju; Gaur, Virendra; Dadhich; Mamta Chauhan, C.P.; Tripathi, Beena

    2013-01-01

    In the south and southeast periphery of the desert city of Jodhpur, there are pink and grey granite islands in the desert sand at Fitkasni-Rasida and Salawas-Nandanvan areas of Malani Igneous Suite (Neoproterozoic). We are reporting the average heat generation value of 15.33 HGU for first and 8.83 HGU for the second area that is much higher than the average (3.8 HGU) known for the continental crust. The concentration of uranium determined is two to four times higher than the average continental crust and thorium is still higher than U and K. The radioelement concentration (Ur) varies from 25.06 to 27 in the Salawas-Nandanvan granites and 43.73 to 75.81 in Fitkasni-Rasida granites. It clearly indicates a 'hot crust', hence favourable for the formation of mineralization of HFS elements, Nb, Ce, REE, U and Th, which need yet to be explored. (author)

  19. A Study on Tribological Behavior of Glass-Epoxy Composite Filled with Granite Dust

    Science.gov (United States)

    Ray, Subhrajit; Rout, Arun Ku; KuSahoo, Ashok

    2017-08-01

    Granite powder is one of the solid wastes generated from stone processing industry used as organic filler replacing the conventional ceramic fillers in polymer matrix composite to increase the mechanical properties. The present work investigates the addition of granite powder on erosion wear properties of epoxy-glass fiber composite. The solid particle erosion wear rates of these hybrid composites are recorded considering various control parameters as impingement angles, erodent sizes and impact velocities following erosion resistance test in an air erosion test device at room temperatures. The test was conducted as per the Taguchi experimental design to minimize the erosion loss of material. The SEM views show the surface resistivity for the granite added specimens. The microscopic study also indicates various methods of material removal, crater wear and other subjective allocation during erosion experiment of the samples.

  20. Effect of the state of internal boundaries on granite fracture nature under quasi-static compression

    Science.gov (United States)

    Damaskinskaya, E. E.; Panteleev, I. A.; Kadomtsev, A. G.; Naimark, O. B.

    2017-05-01

    Based on an analysis of the spatial distribution of hypocenters of acoustic emission signal sources and an analysis of the energy distributions of acoustic emission signals, the effect of the liquid phase and a weak electric field on the spatiotemporal nature of granite sample fracture is studied. Experiments on uniaxial compression of granite samples of natural moisture showed that the damage accumulation process is twostage: disperse accumulation of damages is followed by localized accumulation of damages in the formed macrofracture nucleus region. In energy distributions of acoustic emission signals, this transition is accompanied by a change in the distribution shape from exponential to power-law. Granite water saturation qualitatively changes the damage accumulation nature: the process is delocalized until macrofracture with the exponential energy distribution of acoustic emission signals. An exposure to a weak electric field results in a selective change in the damage accumulation nature in the sample volume.

  1. Characterization of the weathering of the Auriat granite (Creuse). Study of its porous space

    International Nuclear Information System (INIS)

    Leca, D.

    1990-05-01

    Our aim has been to characterize the alterations of the Auriat granite (Creuse - France) from a deep drilling. The two main parts of this memoir are : alterations prospecting and the analysis of the porous medium. After bibliographic review, we have characterized the Auriat granite and its alterations with classical methods: visual study, optical microscopy, MEB, Vickers micro-hardness, chemical analyses (scales of rock and grain), uniaxial compression and seismic velocities measurement in laboratory. We have defined alteration facies starting from the feldspar colors (rubefaction) that correspond to a physico-chemical reality. The second part of the memoir starts with the measurement of the granite porous volume. We have developed a technique adapted to the measurement of very low porosities (less than 2 %). The distribution of the porosities in relation with the facies shows that fresh granite has very low porosity (less than 1%) and weathered (rubefied) granite is slightly more porous (from about 0 to 2%). The decomposition of the global porosity in 'pore porosity' and 'crack porosity' shows that the fresh facies is affected by a set of open cracks. The rubefied facies presents widely clogged micro-cracks. We have taken up the mercury injection porosimetry test from the calculi used in the physic of high pressure. The study of porosimetry curves shows the existence of an infra-porosity (from 0.001 to 0.01 microns) for the rubefied facies. We have measured the gas permeability of the granite, then we have computed specific areas starting from porosity and permeability. Finally, we have presented a synthesis and the envisaged prospects. (author)

  2. Subsurface profiling of granite pluton using microtremor method: southern Aravalli, Gujarat, India

    Science.gov (United States)

    Joshi, Aditya U.; Sant, Dhananjay A.; Parvez, Imtiyaz A.; Rangarajan, Govindan; Limaye, Manoj A.; Mukherjee, Soumyajit; Charola, Mitesh J.; Bhatt, Meghnath N.; Mistry, Sagar P.

    2018-01-01

    We report, using the microtremor method, a subsurface granitic pluton underneath the Narukot Dome and in its western extension along a WNW profile, in proximity of eastern fringe of Cambay Rift, India. The dome and its extension is a part of the Champaner Group of rocks belonging to the Mesoproterozoic Aravalli Supergroup. The present finding elucidates development of an asymmetric double plunge along Narukot Dome. Microtremor measurements at 32 sites were carried out along the axial trace (N95°) of the dome. Fourier amplitude spectral studies were applied to obtain the ratio between the horizontal and vertical components of persisting Rayleigh waves as local ambient noise. Fundamental resonant frequencies with amplitude ≥1-sigma for each site are considered to distinguish rheological boundary. Two distinct rheological boundaries are identified based on frequency ranges determined in the terrain: (1) 0.2219-10.364 Hz recorded at 31 stations identified as the Champaner metasediment and granite boundary, and (2) 10.902-27.1119 Hz recorded at 22 stations identified as the phyllite and quartzite boundary. The proposed equation describing frequency-depth relationship between granite and overlaying regolith matches with those already published in the literature. The morphology of granite pluton highlights the rootless character of Champaner Group showing sharp discordance with granitic pluton. The findings of manifestation of pluton at a shallower depth imply a steep easterly plunge within the Champaner metasediments, whereas signature of pluton at a deeper level implies a gentle westerly plunge. The present method enables to assess how granite emplacement influences the surface structure.

  3. Radiation dose to workers due to the inhalation of dust during granite fabrication

    International Nuclear Information System (INIS)

    Zwack, L M; Stewart, J H; McCarthy, J F; Allen, J G; McCarthy, W B

    2014-01-01

    There has been very little research conducted to determine internal radiation doses resulting from worker exposure to ionising radiation in granite fabrication shops. To address this issue, we estimated the effective radiation dose of granite workers in US fabrication shops who were exposed to the maximum respirable dust and silica concentrations allowed under current US regulations, and also to concentrations reported in the literature. Radiation doses were calculated using standard methods developed by the International Commission on Radiological Protection. The calculated internal doses were very low, and below both US occupational standards (50 mSv yr −1 ) and limits applicable to the general public (1 mSv yr −1 ). Workers exposed to respirable granite dust concentrations at the US Occupational Safety and Health Administration (OSHA) respirable dust permissible exposure limit (PEL) of 5 mg m −3 over a full year had an estimated radiation dose of 0.062 mSv yr −1 . Workers exposed to respirable granite dust concentrations at the OSHA silica PEL and at the American Conference of Governmental Industrial Hygienists Threshold Limit Value for a full year had expected radiation doses of 0.007 mSv yr −1 and 0.002 mSv yr −1 , respectively. Using data from studies of respirable granite dust and silica concentrations measured in granite fabrication shops, we calculated median expected radiation doses that ranged from <0.001 to 0.101 mSv yr −1 . (paper)

  4. 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...

  5. Emplacement and deformation of the A-type Madeira granite (Amazonian Craton, Brazil)

    Science.gov (United States)

    Siachoque, Astrid; Salazar, Carlos Alejandro; Trindade, Ricardo

    2017-04-01

    The Madeira granite is one of the Paleoproterozoic (1.82 Ga) A-type granite intrusions in the Amazonian Craton. It is elongated in the NE-SW direction and is composed of four facies. Classical structural techniques and the anisotropy of magnetic susceptibility (AMS) method were applied to the study of its internal fabric. Magnetic susceptibility measurements, thermomagnetic curves, remanent coercivity spectra, optical microscopy and SEM (scanning electron microscopy) analyses were carried out on the earlier and later facies of the Madeira granite: the rapakivi granite (RG) and the albite granite (AG) respectively. The last one is subdivided into the border albite granite (BAG) and the core albite granite (CAG) subfacies. AMS fabric pattern is controlled by pure magnetite in all facies, despite significant amounts of hematite in the BAG subfacies. Microstructural observations show that in almost all sites, magnetic fabric correlates to magmatic state fabrics that are defined by a weak NE-SW orientation of mafic and felsic silicates. However, strain mechanisms in both subfacies of AG also exhibit evidence for solid-state deformation at high to moderate temperatures. Pegmatite dyke, strike slip fault (SFA-B-C), hydrothermal vein, normal fault (F1-2) and joint (J) structures were observed and their orientation and kinematics is consistent with the magmatic and solid-state structures. Dykes, SFA-C and F1, are usually orientated along the N70°E/40°N plane, which is nearly parallel to the strike of AMS and magmatic foliations. In contrast, veins, SFB, F2 and some J are oriented perpendicular to the N70°E trend. Kinematic analysis in these structures shows evidence for a dextral sense of movement in the system in the brittle regime. The coherent structural pattern for the three facies of Madeira granite suggests that the different facies form a nested pluton. The coherence in orientation and kinematics from magmatic to high-temperature solid-state, and into the brittle

  6. The natural analogous study of the migration of radionuclides in granite for nuclear waste disposal

    International Nuclear Information System (INIS)

    Yu Jinsheng

    1995-01-01

    Granite is one of the optimum types of surround rock for radioactive waste geological disposal. The study of natural analogues could provide very useful reference materials for selecting validating and designing site of repository in granite. The basic research substances are as follows: the fracture system and the circulation paths of the fluid, the hydrothermal alteration, the evolution of hydrothermal solution, the U, Th, REE element geochemical behaviours, the secondary mineral phases and its retention capacity for the concerned radioactive nuclides and the mass transfer modelling

  7. Age and Isotopic Studies of Some Pan-African Granite from North-Central Nigeria

    International Nuclear Information System (INIS)

    Breemen, O. van; Pidgeon, R.T.; Bowden, P.

    1977-01-01

    Twenty-nine Rb-Sr whole-rock isotopic analyses and three U-Pb zircon analyses on foliated granites and largely unfoliated charnockitic rocks indicate that the central part of the Pan-African belt in west Africa was characterised by intense orogenic plutonism. These data and Rb-Sr analyses on muscovite books from late cross-cutting pegmatites indicate that the peak of magmatic activity occurred 610 +- 10 m.y.ago. Initial 87 Sr/ 86 Sr ratios for the granitic and charnockitic rocks are in the range 0.7065-0.7125, and indicate a significantly older crustal component in the magmas

  8. General conceptual design study for a high-level radioactive waste repository in a granite formation

    International Nuclear Information System (INIS)

    1982-01-01

    The object of the general conceptual design study for a high level radioactive wastes repository in a deep lying granite formation is to ensure that technology available in 1980 is suitable for building, operating and finally closing such a repository. It is feasible to build and operate a 1000 m deep repository, located in a granite batholith, receiving 30000 AVM canisters (after 30 years surface cooling), the disposal rate being 1000 canisters per year. Cost of the operation amounts to 1,3% of the corresponding amount of electricity. The building, operating and final closing phases will take 81 years

  9. Analyses of SRS waste glass buried in granite in Sweden and salt in the United States

    International Nuclear Information System (INIS)

    Williams, J.P.; Wicks, G.G.; Clark, D.E.; Lodding, A.R.

    1991-01-01

    Simulated Savannah River Site (SRS) waste glass forms have been buried in the granite geology of the Stirpa mine in Sweden for two years. Analyses of glass surfaces provided a measure of the performance of the waste glasses as a function of time. Similar SRS waste glass compositions have also been buried in salt at the WIPP facility in Carlsbad, New Mexico for a similar time period. Analyses of the SRS waste glasses buried in-situ in granite will be presented and compared to the performance of these same compositions buried in salt at WIPP

  10. REE enrichment in granite-derived regolith deposits of the southeast United States: Prospective source rocks and accumulation processes

    Science.gov (United States)

    Foley, Nora K.; Ayuso, Robert A.; Simandl, G.J.; Neetz, M.

    2015-01-01

    The Southeastern United States contains numerous anorogenic, or A-type, granites, which constitute promising source rocks for REE-enriched ion adsorption clay deposits due to their inherently high concentrations of REE. These granites have undergone a long history of chemical weathering, resulting in thick granite-derived regoliths, akin to those of South China, which supply virtually all heavy REE and Y, and a significant portion of light REE to global markets. Detailed comparisons of granite regolith profiles formed on the Stewartsville and Striped Rock plutons, and the Robertson River batholith (Virginia) indicate that REE are mobile and can attain grades comparable to those of deposits currently mined in China. A REE-enriched parent, either A-type or I-type (highly fractionated igneous type) granite, is thought to be critical for generating the high concentrations of REE in regolith profiles. One prominent feature we recognize in many granites and mineralized regoliths is the tetrad behaviour displayed in REE chondrite-normalized patterns. Tetrad patterns in granite and regolith result from processes that promote the redistribution, enrichment, and fractionation of REE, such as late- to post- magmatic alteration of granite and silicate hydrolysis in the regolith. Thus, REE patterns showing tetrad effects may be a key for discriminating highly prospective source rocks and regoliths with potential for REE ion adsorption clay deposits.

  11. Geochemistry of metavolcanics and granitic intrusive from western ...

    African Journals Online (AJOL)

    The western margin of northern Afar Depression constitutes various rock units of Neoproterozoic basement complex. Major oxide data of metavolcanic and granitoid rock samples from basement complex indicate significant variation in the concentration of major oxides (e.g. Fe2O3, TiO2, CaO, MgO). Metavolcanic rocks of ...

  12. Calcite veins of the Stripa granite (Sweden) as records of the origin of the ground waters and their interactions with the granitic body

    International Nuclear Information System (INIS)

    Clauer, N.; Fritz, B.; Frape, S.K.

    1989-01-01

    A Sr isotopic study combined with stable isotope determinations (δ 18 O and δ 13 C), petrographic observations and speciation calculations suggests that the Stripa granite (Sweden) contains at least three different types of calcite veins. One type with δ 18 O = -18 to -24 per-thousand (PDB) and 87 Sr/ 86 Sr = 0.7814 to 1.0696 probably formed at temperatures above 200 degree C, together with chlorite and epidote, during one or two metamorphic events which are recorded in the Rb-Sr systematics of some minerals of the granite at 1.4 and 0.8 Ga. Another type with δ 18 O = -12 to -18 per-thousand (PDB) and 87 Sr/ 86 Sr = 0.7406 to 0.7536 and mainly associated with chlorite, is most likely in equilibrium with the present day ground waters, which probably have reacted with the fracture minerals of the granitic body for a long time without any supply of external fluids. The third type of calcite with δ 18 C = -12 to -18 per-thousand (PDB), δ 13 C = -5 to -45 per-thousand (PDB) and 87 Sr/ 86 Sr = 0.7266 to 0.7406, could have formed from reactions involving methane oxidation or sulfate reduction in the presence of bacteria

  13. 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

  14. Geological characteristics of granite type uranium deposits in middle of Inner Mongolia in comparison with south China

    International Nuclear Information System (INIS)

    Wang Gui

    2012-01-01

    Granites extensively distributed in middle of Inner Mongolia and South China, namely Caledonian, Hercynian and Yanshanian. Some of the intrusive are composed of granites which belong to different ages. Some of the uranium deposits were found inside the granite bodies or in sedimentary rocks and meta sedimentary rocks along the exocontact zone. Granite rock was comparing in middle Inner Mongolia and South China, including Uranium ore-forming geological conditions. ore-forming process and Ore-controlling factors. Think the Uranium ore-forming geological conditions is similar; ore-forming process is mainly for low-mid temperature hot liquid; Uranium ore bodies (uranium mineralization) was controlled by fracture. Explain granite type uranium mineralization potential is tremendous in middle of Inner Mongolia. (author)

  15. Generation of post-collisional normal calc-alkaline and adakitic granites in the Tongbai orogen, central China

    Science.gov (United States)

    Zhang, Wen-Xiang; Zhu, Liu-Qin; Wang, Hao; Wu, Yuan-Bao

    2018-01-01

    Post-collisional granites are generally generated by partial melting of continental crust during orogenic extension. The occurrence of normal calc-alkaline granites following adakitic granites in a collisional orogen is frequently supposed as a sign of tectonic regime transition from compression to extension, which has been debated yet. In this paper, we present a comprehensive study of zircon U-Pb ages, Hf-O isotopes, as well as whole-rock major and trace elements and Sr-Nd isotopes, for Tongbai and Jigongshan post-collisional granitic plutons in the Tongbai orogen. Zircon U-Pb dating yields intrusion ages of ca. 140 and 135 Ma for the Tongbai and Jigongshan plutons, respectively, suggesting they are post-collisional granites. These granites are high-K calc-alkaline series, metaluminous to weakly peraluminous with A/CNK ratios of 0.85-1.08. The Tongbai gneissic granites are normal calc-alkaline granite, having variable SiO2 (61.93-76.74 wt%) and Sr/Y (2.9-38.9) and (La/Yb)N (1.7-30.1) ratios with variably negative Eu anomalies (0.41-0.92). They have relatively high initial Sr isotope ratios of 0.707571 to 0.710317, and low εNd(t) (- 15.74 to - 11.09) and εHf(t) (- 17.6 to - 16.9) values. Their Nd and Hf model ages range from 2.2 to 1.8 Ga and 2.3 to 2.2 Ga. On the contrary, the Jigongshan granites show higher SiO2 (66.56-72.11 wt%) and Sr/Y (30.1-182.0) and (La/Yb)N (27.4-91.4) ratios with insignificant Eu anomalies (0.73-1.00), belonging to adakitic granite. They have Isr = 0.707843-0.708366, εNd(t) = - 19.83 to - 17.59, and εHf(t) = - 26.0 to - 23.5. Their Nd and Hf model ages vary from ca. 2.5 to 2.4 Ga and ca. 2.8 to 2.6 Ga. The Tongbai and Jigongshan granites are characterized by mantle-like zircon δ18O values (5.17-5.46‰). These geochemical features suggest that the Tongbai and Jigongshan granites were derived from partial melting of Paleoproterozoic and Archean continental crust, respectively. Fractional crystallization affected the geochemical

  16. Petrology, geochemistry, and geochronology of Paleoproterozoic volcanic and granitic rocks (1.89-1.88 Ga) of the Pitinga Province, Amazonian Craton, Brazil

    Science.gov (United States)

    Ferron, J. Maximino T. M.; Bastos Neto, Artur C.; Lima, Evandro F.; Nardi, Lauro V. S.; Costi, Hilton T.; Pierosan, Ronaldo; Prado, Maurício

    2010-03-01

    This paper presents geochemical, petrographic, and geochronological data on the Uatumã magmatism in the Pitinga Province, where it is represented by volcanic rocks from the Iricoumé Group and granitic rocks from the Mapuera Suite. The Iricoumé Group (1.89-1.88 Ga) is constituted of the Divisor Formation (intermediate volcanic rocks), Ouro Preto Formation (acid effusive rocks), and Paraiso Formation (acid crystal-rich ignimbrites, surge deposits, and basic rocks). The volcanic sequence is intruded by granitoids from the Mapuera Suite (1.88 Ga), mainly represented by monzogranites and syenogranites. Structural and field relations suggest that caldera complex collapse controlled the emplacement of volcanics and granitoids of the Mapuera Suite. Subsequent structure reactivations allowed the younger Madeira Suite (1.82-1.81 Ga) to be emplaced in the central portion of the caldera complex. The felsic Iricoumé magmatism is mainly composed of rhyolites, trachydacites and latites, with SiO 2 contents between 64 wt% and 80 wt%. The plutonic rocks from the Mapuera Suite present SiO 2 between 65 wt% and 77 wt%. Volcanic and granitic rocks present identical geochemical characteristics and that is attributed to their co-magmatic character. The felsic volcanic rocks and granites are metaluminous to slightly peraluminous and show affinity with silica-saturated alkaline series or with A-type magmas. They have Na 2O + K 2O between 6.6% and 10.4%, FeO t/(FeO t + MgO) varying between 0.76 and 0.99, Ga/Al ratios between 1.5 and 4.9, like typical A-type rocks; and plot in the within-plate or post-collisional fields in the (Nb + Y) vs. Rb diagram. The Nb/Y ratios indicate that these rocks are comparable to A2-type granites. This magmatism can be related to the (i) potassic alkaline series, with low Sr content in the felsic rocks explained by plagioclase fractionation at low pressure and high temperature or, alternatively, (ii) a bimodal association where magma had high crustal

  17. Fluid paleocirculations at the cover/granite interface in the Rhine graben

    Science.gov (United States)

    Lerouge, Catherine; Dezayes, Chrystel; Bailly, Laurent; Flehoc, Christine; Guerrot, Catherine; Wille, Guillaume

    2017-04-01

    The Rhine Graben is a major site of development for the geothermal heating production in France. Targeted geothermal reservoirs are in deep Hercynian granitic basement which is fractured dominated system, and more recently at the cover/basement interface. In this framework of geothermal exploration, a better understanding of the hydraulic behaviour of the fracture network and fluid/rock interactions is needed. For that fracture fillings in Hercynian granitic basement and in the formations of the cover (Permian rhyolites, Permian and Triassic sediments) were studied for mineralogy, fluid inclusion microthermometry and (C, O, Sr) isotopes in order to trace paleocirculations at the cover/granite interface in the Rhine Graben. Data were acquired on fracture fillings in samples of the basement/cover interfaces from the EPS1 borehole at Soultz-sous-Forêt in the Rhine graben at 1417 meters depth, and from outcrops in quarries on the flanks of the graben (Waldhambach, Saint Pierre Bois, Windstein, Heidelberg). Mineral sequences of polyphased fillings were interpreted in relation with the geological context including late evolution of the Hercynian basement and major extensive tectonic events. Quartz, carbonates, sulfates and illite are major minerals identified in fractures crosscutting Hercynian granites, Permian rhyolite (Waldhambach) and Permian and Triassic sedimentary cover. Although quartz being considered as a major mineral filling fractures, petrological observations showed that carbonates are also an important and probably underestimated phase of filling, and of interest for two reasons. Firstly, from a geothermal point of view, they contribute to the clogging of fractures. Secondly, from a scientific point of view, they are informative on the variations of fluid chemistry through geological times. Among carbonates, dominant dolomite with minor ankerite, Mn-bearing carbonates and siderite was identified by CL, SEM and EPMA in fractures. A same generation of

  18. Crystallization and Disturbance Histories of Single Zircon Crystals From Hadean-Eoarchean Acasta Gneisses Examined by LA-ICP-MS U-Pb Traverses

    Science.gov (United States)

    Guitreau, Martin; Mora, Nicolas; Paquette, Jean-Louis

    2018-01-01

    Zircon U-Pb geochronology is a very robust dating method but the accuracy of determined ages can sometimes be compromised. This is because, as commonly observed, the U-Pb isotope system can be reopened during the post-crystallization evolution of a zircon. The present manuscript investigates the capability of traverses by LA-ICP-MS to identify zones of well-preserved U-Pb isotope systematics within zircon crystals. The data for the different zones can be used to construct internal Discordia lines that provide age information about crystallization and metamorphism of single zircon crystals. To test our approach, we analyzed zircons from three ca. 3.96 Ga Acasta gneisses. Results demonstrate that such a method allows retrieval of original crystallization age in most of the studied zircons, even in those that experienced ancient U-Pb disturbances resulting in discordant U-Pb data. It was also possible to estimate disturbance ages, though not as precisely as for the igneous crystallization, in many of the studied crystals.

  19. Gneiss wastes as secondary raw material for the ceramic industry: an example from the Verbano Cusio Ossola district (Piedmont, north-western Alps, Italy)

    Science.gov (United States)

    Cavallo, Alessandro

    2015-04-01

    The Verbano Cusio Ossola province (VCO, Piedmont, north-western Italy) is one of the most important Italian quarrying districts, due to the peculiarity and variety of its exploited rock types, mainly orthogneisses such as Serizzo and Beola, and subordinately granites, marbles and other rocks. The most important and extensively exploited ornamental stone from the VCO province is surely the Serizzo, commercialized in four main varieties, and representing about 70% of all the stone production from the VCO area. The protholith of the Serizzo is a Permian granite - granodiorite metamorphosed during the alpine events, and the rock-forming minerals are mainly quartz, K-feldspar, plagioclase (andesine), biotite, with variable amounts of muscovite and epidote (allanite). The other important ornamental stone of the VCO province is the Beola, a series of heterogeneous materials (mainly orthogneisses) with marked (mylonitic) foliation and strong mineralogical lineation, occurring in the median Ossola Valley; its production (15% of the whole stones of the VCO) is subordinated with respect to that of Serizzo. The mineralogical composition of the Beola varieties is similar to Serizzo, consisting of quite homogeneous quartz, K-feldspar (orthoclase or microcline), plagioclase, biotite and muscovite. The main differences relate to the grain size, the rock fabric (generally mylonitic) and to the presence of accessory/secondary minerals. Recent regulatory developments and the growing environmental awareness, require an increasing reuse of wastes deriving from the extraction and processing of dimension stones (up to 50 % of the extracted gross volume). Granite wastes from the VCO (Baveno pink granite and Montorfano white granite), after specific industrial treatments (crushing, sieving, drying, magnetic separation of biotite and hornblende), are used successfully as quartz-feldspars mix in the ceramic industry, with very low FeOtot content. On the other hand, other quartzose

  20. Petrogenesis and tectonic setting of the Devonian Xiqin A-type granite in the northeastern Cathaysia Block, SE China

    Science.gov (United States)

    Cai, Da-wei; Tang, Yong; Zhang, Hui; Lv, Zheng-Hang; Liu, Yun-long

    2017-06-01

    Most Silurian-Devonian granites in South China are S- or I-type granites, which are suggested to be petrogenetically related to the Wuyi-Yunkai orogeny. In this paper, we present the detailed LA-ICP-MS zircon U-Pb dating, major and trace element geochemical, and Nd-Hf isotopic data for Xiqin A-type granites in the northeastern Cathaysia Block, SE China. Zircon U-Pb dating results show that the Xiqin granites were emplaced at about 410 Ma, indicating that they were generated at the end of Wuyi-Yunkai orogeny. These granites are high in K2O + Na2O (6.31-8.79 wt%), high field strength elements (Zr + Nb + Ce + Y = 427-699 ppm), rare earth elements (total REE = 221-361 ppm) as well as high Ga/Al ratios (10,000 Ga/Al = 2.50-3.10), and show characteristics typical of A-type granites. εHf(t) values of the Xiqin granites mainly vary from -0.4 to -3.1 and yield Mesoproterozoic T2DM(Hf) (mainly ranging from 1.29 to 1.45 Ga). The εNd(t) values are from -1.23 to -2.11 and T2DM(Nd) vary from 1.25 to 1.32 Ga. These isotopic data suggest that the Xiqin granites were generated by partial melting of metavolcanic rocks with minor metasedimentary rocks in the lower crust. Our data on the Xiqin granites, coupled with previous studies of Silurian-Devonian magmatism, suggest that the tectonic regime had changed to a strongly post-collisional extension environment in the Wuyi-Yunkai orogen at least since 410 Ma, and that delamination, which accounts for the change in stress from the compression to extension and asthenospheric upwelling during the early Paleozoic, plays a significant role in the generation of Xiqin A-type granites.

  1. Micromorphology of a weathered granite near the Ría de Arosa (NW Spain)

    NARCIS (Netherlands)

    Bisdom, E.B.A.

    1966-01-01

    A detailed study has been made of several weathering profiles on the late-Hercynian Caldas de Reyes granite, NW-Spain. The field examination has been complemented by laboratory studies of large thin sections of hardened weathered material in conjunction with X-ray diffraction analyses. Three groups

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

    International Nuclear Information System (INIS)

    Rocha, Edilson A.; Amaral, Romilton dos S.; Santos Junior, Jose A. dos; Bezerra, Jairo D.

    2011-01-01

    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 ( 238 U and 232 Th) and 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 40 K, and it should not exceed the 1 mSv.y -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 4 :Dy were used. The findings showed doses ranges from the background to 4.7 mSv.y -1 , with general average of dose rate equal to 3.0 mSv.y -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)

  3. Impact of Granite Quarrying on the Health of Workers and Nearby ...

    African Journals Online (AJOL)

    Impact of Granite Quarrying on the Health of Workers and Nearby Residents in Abeokuta Ogun State, Nigeria. ... Suspended Particulate Matter (SPM) meter was employed to monitor the level of particulate matter (PM10) within and around five quarry sites selected for this study. The data collected from hospital records of ...

  4. Muskovit-biotitický granit z Kalvárie v Jihlavě

    Czech Academy of Sciences Publication Activity Database

    René, Miloš

    2013-01-01

    Roč. 20, 1/2 (2013), s. 145-147 ISSN 1212-6209 R&D Projects: GA MŠk ME10083 Institutional support: RVO:67985891 Keywords : granite * petrology * geochemistry * Moldanubian Zone Subject RIV: DB - Geology ; Mineralogy

  5. 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

    Properties of self compacting concrete (SCC) with two types of coarse aggregate - sea dredged gravel with smooth and rounded particles and crushed granite with rough and angular particles - have been studied. Sea gravel allowed a higher aggregate proportion in the concrete leading to a higher...

  6. Study of isotopic desequilibrium of natural radioactive series in granitic environment: Pluton of El Berrocal (Toledo)

    International Nuclear Information System (INIS)

    Hernandez Benitez, A.

    1994-01-01

    This report summarizes the work funded by European Communities with contract '' The Berrocal project: characterization and validation of natural radionuclide migration processes under real conditions in a fissured granitic environment''. The author takes into account the following aspects in his study: isotope of natural radionuclides, sampling methods, analytic methodology and geological characteristics of the area

  7. Isotopic data revaluation from Cabo province, with base in Cabo granite petrographic studies

    International Nuclear Information System (INIS)

    Legrand, J.M.; Figueiredo Filho, O.A.

    1979-01-01

    The Sto Agostinho's Cape granite (NE-Brazil) is formed by two successive instrusions: the first riolitic or migmatitic, replaced by the alkali granite. This process is indicated by the potassic feldspar phenocrystals porpliroblastic assimilation of the riolites, conglobating the re-cristalized matrix minerals. This two times formation is confirmed by geochronological studies in magmatic province. The diagram of the different rocks with alkaline differentiation is distributed in two isochrons. The first isochron age of 135 m.y +- 0,7 λ=1,42x10 -11 ) with a Ri = 0,7023, the second determine to the Cape granite 104 m.y +- 0,7 (λ=1,42x10 -11 ) with a Ri=0,7058. The first pulsation value of 0,7023, indicate a crust origin to the granite. The more elevated value in the second magmatic dike can be explain by the mixture of more or less 99% of crust magma and 1% of plutonic rocks. (C.D.G.) [pt

  8. Performance assessment of alpha wastes disposal in deep geological formations, PACOMA project: granite option

    International Nuclear Information System (INIS)

    Brun-Yaba, C.; Cernes, A.; Mangin, J.P.

    1989-11-01

    After the CEC PAGIS project (for vitrified waste), the PACOMA project has been launched at the end of 1987 for cemented waste. The CEA-IPSN is in charge of the granite option. For the PACOMA project, a representative inventory of this type of waste has been built up, a repository concept (with one variant) has been defined and an adaptation of the near field module, Condiment, of the safety evaluation code MELODIE, has been made in order to take into account the particularities of cemented waste with respect to the vitrified waste. The best-estimate calculations have been performed on one reference site (the French Auriat Site) which is an outcropping granite and two variants, one representing a coastal granite formation (Barfleur) and the other, a granite with a sedimentary cover (notional British site). Moreover, the sensitivity and uncertainty analysis have been performed in the PACOMA project with a 2D modelling of the geosphere (module METIS of MELODIE code) instead of the 1D modelling (stream tube) previously used in the PAGIS project. After a general presentation of these points, the main results, namely the dose rates obtained through deterministic calculations, and the most important geosphere parameters, are presented [fr

  9. SITE-94. Estimated rates of redox-front migration in granitic rocks

    International Nuclear Information System (INIS)

    Arthur, R.C.

    1996-10-01

    Analytical models for the rate of migration of oxidizing groundwaters are derived based on the stationary-state approximation to coupled fluid flow and water-rock interaction, and are constrained by molar concentrations of ferrous silicate, oxide, and sulfide minerals in the granites and associated fractures comprising the host rock beneath Aespoe. Model results indicate that small amounts of ferrous minerals in Aespoe granites and fractures will retard the downward migration of oxidizing conditions that could be generated by infiltration of glacial meltwaters during periods of glacial maxima and retreat. Calculated front velocities are retarded relative to Darcy fluxes observed in conductive fracture zones at Aespoe (0.3 to 3 m/y) by factors ranging from 10 -3 to 10 -4 . Corresponding times for the front to migrate 500 m vary from 5,100 to 4,400,000 years. Retardation efficiency depends on mineralogy and decreases in the order: fractures > altered granites > unaltered granite. The most conductive structures in these rocks are therefore the most efficient in limiting the rate of front migration. Periods of recharge during glaciation are comparable to times required for an oxidizing front to migrate to repository levels. This suggests an oxidizing front could reach repository depths during a single glacial-interglacial event. The persistence of oxidizing conditions could be relatively short lived, however, because reversal of flow conditions driven by the advance and retreat of ice sheets could cause reducing conditions to be restored. 27 refs

  10. Investigation on the Suitability of Fobur Granite in Jos, Plateau State ...

    African Journals Online (AJOL)

    ADOWIE PERE

    was calculated using equation (ISRM, 1981). = ( ). (1). = (2). Porosity Determination of Granite Samples: The samples A, B, C were in seize of cubic, 10mm by. 10mm by 10mm.The samples were then dried in an oven at 110o C. The dry weight of the samples in air were taken and recorded as W1,The sample in air was.

  11. Experimental Investigation of Crack Extension Patterns in Hydraulic Fracturing with Shale, Sandstone and Granite Cores

    Directory of Open Access Journals (Sweden)

    Jianming He

    2016-12-01

    Full Text Available Hydraulic fracturing is an important method of reservoir stimulation in the exploitation of geothermal resources, and conventional and unco