The Friningen Garnet Peridotite (central Swedish Caledonides). A good example of the characteristic PTt path of a cold mantle wedge garnet peridotite

NARCIS (Netherlands)

Gilio, Mattia; Clos, Frediano; van Roermund, Herman L M|info:eu-repo/dai/nl/068882432

2015-01-01

We present pseudosections of Cr-bearing garnet peridotite that together with new mineral–chemical data allow quantification of the early PT conditions of the original lithospheric mantle assemblage (M1) of the Friningen Garnet Peridotite (FGP) located in the central/middle belt of the Seve Nappe

Portuguese granites associated with Sn-W and Au mineralizations

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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.

Late Variscan, Permo-Carboniferous, Al-K plutonism in the South Portuguese Zone: El Crispinejo cordierite-bearing granite

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Díez Montes, A.; Valverde-Vaquero, P.; Rey-Moral, C.; Sánchez García, L.

2017-07-01

The El Crispinejo granite forms part of a small, but distinctive late intrusive suite of cordierite-bearing peraluminous granites in the South Portuguese Zone (SPZ). This granite has the best outcrop relationships of the suite. It cross-cuts different members of the Sierra Norte Batholith of the SPZ and the Carboniferous Volcano-Sedimentary Complex of the Iberian Pyrite Belt, producing contact metamorphism. This late pluton has a high K content which results in a contrasting geophysical response (K-Th-U) with respect to the surrounding trondhjemitic granitoids of the TTG suite of the Sierra Norte Batholith. A concordant monazite-zircon U-Pb ID-TIMS age of 300.5 +0.5/-1.5Ma demonstrates Permo-Carboniferous age for this late Variscan magmatic event. The granite is associated with a series of ore showings (F-Pb-Zn and Sn-W) which are completely different from the nearby, massive sulphide and manganese ore deposits of the Iberian Pyrite Belt, indicating the unique character of this intrusion.

Presumed Multiple Metasomatism underneath the Colorado Plateau; Decoding from Chemistry and Inclusion/Lamella Mineralogy of Diverse Garnets from the Garnet Ridge, Northern Arizona

Science.gov (United States)

Sato, Y.; Ogasawara, Y.

2015-12-01

Various garnets containing the information on mantle petrology and related metasomatism occur at the Garnet Ridge, Colorado Plateau. The origins of garnets range from deep mantle to shallow continental crust. These garnets were delivered by kimberlitic diatreme of 30 Ma (Smith et al. 2004). We have classified the garnets into 10 groups (A to J, see figure) by naked eye observation, major chemistry, minor Na-Ti-P, inclusion/lamella mineralogy. Among them, groups A to D are of mantle origin, E to G of subducted oceanic crust origin, and H to J of continental crust origin. We summarized results as in the followings. A: Cr and pyrope-rich garnet has Cr2O3(0.8-6.3 wt.%) and inclusions of Ol, Cpx, Opx, Ti-Chu/Chn and carbonates, indicating carbonated garnet lherzolites as host. Cr contents negatively correlates with Na-Ti-P contents and occurrence of exsolved Rt, Ilm and crichtonite. This indicates Cr-rich end-member is the most "primitive" mantle garnet before metasomatism. B: Pyrope-rich reddish brown garnet of peridotitic origins was subdivided into 4 subgroups (B1 to B4, see figure). Compositional range in Ca-Mg-Fe triangle expands to Fe-rich side from group A. Exsolved Na-bearing amphibole and inclusions of Ap, carbonates and fluid were identified. These indicate metasomatism of group A. C: Garnet megacryst is coarse-grained garnet (2-10 cm across) with crystal faces. This garnet has wide chemical variation plotted in the center area of Ca-Mg-Fe triangle. D: Garnet aggregate has similar chemistry of group C and is composed of several grains. Grain boundaries of garnet were recognized by Rt, Ilm and other minerals and oscillatory zonings of Ca, Mg, Fe and Na-Ti-P. Fluid inclusions of groups C and D suggest these garnets might crystalized from fluid. E: Garnet in eclogite and F: Garnet in metasomatized eclogite are xenolith samples (the Fallaron Plate origin?). Aggregate of Zo+Ab contained in group E indicates decomposed precursor lawsonite inclusion. G: Quartz

Garnet peridotite found in the Greater Antilles

Science.gov (United States)

Abbott, Richard N., Jr.; Draper, Grenville; Keshav, Shantanu

Although Alpine peridotites are relatively common in collisional orogenic zones, garnet-bearing peridotites are rare and only associated with high pressure/ultra-high pressure or temperature (HP/UHP or T) terranes [Brueckner and Medaris, 2000; Medaris, 1999]. Until recently all reported occurrences of Alpine-type garnet peridotites and HP/UHP terranes were in Eurasia and Africa, with one occurrence in the Seward Peninsula, Alaska [Till, 1981;Lieberman and Till, 1987]. Now a new Alpine-type garnet peridotite locality has been discovered in the Caribbean island of Hispaniola. This discovery is the second of its kind in the Americas.

The Gondwana Orogeny in northern North Patagonian Massif: Evidences from the Caita Có granite, La Seña and Pangaré mylonites, Argentina

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Daniel A. Gregori

2016-07-01

Full Text Available Structural analyses in the northern part of the North Patagonia Massif, in the foliated Caita Có granite and in La Seña and Pangaré mylonites, indicate that the pluton was intruded as a sheet-like body into an opening pull-apart structure during the Gondwana Orogeny. Geochronological studies in the massif indicate a first, lower to middle Permian stage of regional deformation, related to movements during indentation tectonics, with emplacement of foliated granites in the western and central areas of the North Patagonian Massif. Between the upper Permian and lower Triassic, evidence indicates emplacement of undeformed granitic bodies in the central part of the North Patagonian Massif. A second pulse of deformation between the middle and upper Triassic is related to the emplacement of the Caita Có granite, the development of mylonitic belts, and the opening of the Los Menucos Basin. During this pulse of deformation, compression direction was from the eastern quadrant.

Foliation theory in algebraic geometry

CERN Document Server

McKernan, James; Pereira, Jorge

2016-01-01

Featuring a blend of original research papers and comprehensive surveys from an international team of leading researchers in the thriving fields of foliation theory, holomorphic foliations, and birational geometry, this book presents the proceedings of the conference "Foliation Theory in Algebraic Geometry," hosted by the Simons Foundation in New York City in September 2013.  Topics covered include: Fano and del Pezzo foliations; the cone theorem and rank one foliations; the structure of symmetric differentials on a smooth complex surface and a local structure theorem for closed symmetric differentials of rank two; an overview of lifting symmetric differentials from varieties with canonical singularities and the applications to the classification of AT bundles on singular varieties; an overview of the powerful theory of the variety of minimal rational tangents introduced by Hwang and Mok; recent examples of varieties which are hyperbolic and yet the Green-Griffiths locus is the whole of X; and a classificati...

Mineral chemistry of garnet in pegmatite and metamorphic rocks in the Hamedan area

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Ahmad Ahmadi Khalaji

2015-10-01

Full Text Available Introduction The area of this study is located near Hamadan within the Sanandaj - Sirjan tectonic zone. In the Hamadan area, consisting mainly of Mesozoic plutonic and metamorphic rocks, aplites and pegmatites locally contain garnets.(Baharifar et al., 2004, Amidi and Majidi, 1977; Torkian, 1995. Garnet-bearing schists and hornfelses in the area are products of regional metamorphism shown by slate and phyllite (Baharifar, 2004. In this investigation the distribution of elements in garnet in different rock type was studied to determine their mineral types and conditions of formation. Garnet samples from igneous and metamorphic rocks were analyzed by electron microprobe (EMPA, the results of which are presented in this article. Materials and methods Thirty-five samples were selected for thin section preparation and twenty thin-polished sections were prepared for mineralogical and microprobe analysis. Thin sections of garnet-bearing igneous (pegmatite and metamorphic rocks (schist and hornfels were studied by polarizing microscope. Chemical analysis was performed on the garnets (38 points using a Caimeca SX100 electron microprobe at an acceleration voltage of 15 kV and electric current of 15 nA in the Mineral Processing Research Center, Iran. Separation of iron (II and Fe (III was calculated by Droop’s method (1987 and the structural formulas of the garnets were calculated using 24 oxygens to determine the relative proportions of the end-members using the mineral spreadsheet software of Preston and Still (2001. Results Based on the analyses, almandine (Fe - Al garnet and spessartine (Mn - Al garnet are the principal types of the (Kamari metamorphic and (Abaro pegmatitic garnets, that belong to the well-known pyralspite garnet group. Chemical zoning patterns of the garnets in the metamorphic rocks (schists differ from those in the igneous rocks (pegmatite, showing different compositions from core to rim. Petrographic evidence such as: co

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

The Friningen Garnet Peridotite (central Swedish Caledonides). A good example of the characteristic PTt path of a cold mantle wedge garnet peridotite

Science.gov (United States)

Gilio, Mattia; Clos, Frediano; van Roermund, Herman L. M.

2015-08-01

We present pseudosections of Cr-bearing garnet peridotite that together with new mineral-chemical data allow quantification of the early PT conditions of the original lithospheric mantle assemblage (M1) of the Friningen Garnet Peridotite (FGP) located in the central/middle belt of the Seve Nappe Complex in central Sweden. Results indicate that the early, coarse grained, olivine + orthopyroxene + clinopyroxene + "high Cr" garnet assemblage (M1a) was formed at 1100 ± 100 °C and 5.0 ± 0.5 GPa. These metamorphic conditions were followed by an inferred late Proterozoic exhumation event down to 850-900 °C and 1.5 GPa (M1b). The latter PT estimate is based on the breakdown of high-Cr M1a garnet (Cr# = 0.065) + olivine into an orthopyroxene + clinopyroxene + spinel (Cr# = 0.15-0.25) ± pargasite kelyphite (M1b) and the exsolution of garnet from Al-rich orthopyroxene and clinopyroxene. The M1b kelyphite is overprinted by an early-Caledonian UHPM mineral assemblage (M2; T = 800 °C and P = 3.0 GPa), equivalent to the earlier discovered UHP assemblage within an eclogitic dyke that cross-cuts FGP. In the garnet peridotite M2 is displayed by low-Cr garnet (Cr# = 0.030) growing together with spinel (Cr# = 0.35-0.45), both these minerals form part of the olivine + orthopyroxene + clinopyroxene + garnet + spinel + pargasite M2 assemblage. The formation of plagioclase + diopside symplectites after omphacite and breakdown of kyanite to sapphirine + albite in internal eclogite and the breakdown of M2 olivine + garnet to amphibole + orthopyroxene + spinel assemblages (M3) in garnet peridotite indicate post-UHP isothermal decompression down to 750-800 °C and 0.8-1.0 GPa (= M3). Multiphase solid-and fluid inclusion assemblages composed of Sr-bearing magnesite, dolomite or carbon decorate linear defect structures within M1a-b minerals and/or form subordinate local assemblages together with M2 minerals. The latter are interpreted as evidence for infiltration of early-Caledonian COH-bearing

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

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

Method for the radioactive determination of the foliates

International Nuclear Information System (INIS)

Rosen, H.

1976-01-01

A method is described for the radioactive determination of the foliates, in which a determination is made of the uptake on a protein fraction of the milk taking up the foliates by competition between the foliate(s) to be determined and a folic acid by-product labelled with a radioactive isotope. The characteristics of this method is that it consists in using tyramide of iodinated folic acid 125 [fr

Experimental and geochemical evidence for derivation of the El Capitan Granite, California, by partial melting of hydrous gabbroic lower crust

Science.gov (United States)

Ratajeski, K.; Sisson, T.W.; Glazner, A.F.

2005-01-01

Partial melting of mafic intrusions recently emplaced into the lower crust can produce voluminous silicic magmas with isotopic ratios similar to their mafic sources. Low-temperature (825 and 850??C) partial melts synthesized at 700 MPa in biotite-hornblende gabbros from the central Sierra Nevada batholith (Sisson et al. in Contrib Mineral Petrol 148:635-661, 2005) have major-element and modeled trace-element (REE, Rb, Ba, Sr, Th, U) compositions matching those of the Cretaceous El Capitan Granite, a prominent granite and silicic granodiorite pluton in the central part of the Sierra Nevada batholith (Yosemite, CA, USA) locally mingled with coeval, isotopically similar quartz diorite through gabbro intrusions (Ratajeski et al. in Geol Soc Am Bull 113:1486-1502, 2001). These results are evidence that the El Capitan Granite, and perhaps similar intrusions in the Sierra Nevada batholith with lithospheric-mantle-like isotopic values, were extracted from LILE-enriched, hydrous (hornblende-bearing) gabbroic rocks in the Sierran lower crust. Granitic partial melts derived by this process may also be silicic end members for mixing events leading to large-volume intermediate composition Sierran plutons such as the Cretaceous Lamarck Granodiorite. Voluminous gabbroic residues of partial melting may be lost to the mantle by their conversion to garnet-pyroxene assemblages during batholithic magmatic crustal thickening. ?? Springer-Verlag 2005.

Geochemistry and petrogenesis of the proterozoic granites from Jhabua and Dhar districts, Madhya Pradesh, India and their bearing on uranium mineralisation

International Nuclear Information System (INIS)

Pant, P.C.; Goyal, Navin; Rawal, Neeru

2004-01-01

In the western part of Madhya Pradesh a number of small plutonic granites occur as intrusive into the gneisses and Aravalli metasediments. Granites are of grey, pink colour and gneissic varieties. Mineralogically, the granites are two mica bearing. Chemically they are K 2 O rich, calc-alkaline, metaluminous to peraluminous and differentiated in nature. Tectonically they are volcanic arc types with an affinity to syn-collisional setup. Basement reactivation may be the cause of the emplacement of these granites as the area is traversed by a number of basement lineaments. They are enriched in light REE with Ce/Yb ratio ranging from 1.4 to 8.4. Negative Eu anomaly (Eu/Eu* 0.2 to 0.8) suggests that they are fractionated. High Th/U ratio (1-18) indicates that uranium has been leached out. Hence the overlying infratrappeans hold potential for litho/structural controlled uranium mineralisation.(author)

Oster pluton (Central Karelia) - the ancient massif of two-feldspar granites of Baltic Shield

International Nuclear Information System (INIS)

Kovalenko, A.V.; Rizvanova, N.G.

2000-01-01

Geochronological study of two-feldspar granites forming the Oster pluton in the Central Karelia was performed using the methods of U-Pb- and Sm-Nd-dating. U-Pb isotope data for zircons from granite of the Oster pluton correspond to the age of 2876±21 mln. years, whereas Sm-Nd isotope data obtained for three samples of the garnet correspond to the age varying from 3.0 to 3.5 bln. years. The ancient age of granites of the Oster pluton is explained by the presence of a sufficiently powerful crust in the region by that moment [ru

A discussion on the tectonic implications of Ediacaran late- to post-orogenic A-type granite in the northeastern Arabian Shield, Saudi Arabia

Science.gov (United States)

Robinson, F. A.; Bonin, B.; Pease, V.; Anderson, J. L.

2017-03-01

The transition from late-orogenic to post-orogenic magmatism following major orogenic episodes such as the Neoproterozoic to Cambrian East African Orogen (EAO) is an important, yet not well-understood geological event marking the cessation of subduction-controlled magmatism between buoyant lithospheric fragments. Forming the northern part of the EAO in the Arabian-Nubian Shield are three granitic suites that successively intruded the same northeastern area and post-date the 640 Ma major orogenic episode: (1) 620-600 Ma alkali feldspar (hypersolvous) granite with alkaline/ferroan/A-type geochemistry, (2) 599 Ma granite cumulates (some garnet-bearing) with calc-alkaline/magnesian affinities, and (3) 584-566 Ma alkali feldspar (hypersolvous) granite (aegirine-bearing) with a distinctive peralkaline/ferroan/A-type signature. Combining whole-rock geochemistry from the southern and northern Arabian Shield, suites 1 and 2 are suggested to be products of late-orogenic slab tear/rollback inducing asthenospheric mantle injection and lower crustal melting/fractionation toward A-type/ferroan geochemistry. Suite 3, however, is suggested to be produced by post-orogenic lithospheric delamination, which replaced the older mantle with new asthenospheric (rare earth element-enriched) mantle that ultimately becomes the thermal boundary layer of the new lithosphere. Major shear zones, such as the 620-540 Ma Najd Fault System (NFS), are some of the last tectonic events recorded across the Arabian Shield. Data presented here suggest that the NFS is directly related to the late-orogenic (620-600 Ma) slab tear/rollback in the northeastern Shield as it met with opposing subduction polarity in the southern Shield. Furthermore, this study infers that east and west Gondwana amalgamation interacted with opposing convergence reflected by the NFS.

Pre-impact tectonothermal evolution of the crystalline basement-derived rocks in the ICDP-USGS Eyreville B core, Chesapeake Bay impact structure

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Gibson, R.L.; Townsend, G.N.; Horton, J. Wright; Reimold, W.U.

2009-01-01

Pre-impact crystalline rocks of the lowermost 215 m of the Eyreville B drill core from the Chesapeake Bay impact structure consist of a sequence of pelitic mica schists with subsidiary metagraywackes or felsic metavolcanic rocks, amphibolite, and calc-silicate rock that is intruded by muscovite (??biotite, garnet) granite and granite pegmatite. The schists are commonly graphitic and pyritic and locally contain plagioclase porphyroblasts, fi brolitic sillimanite, and garnet that indicate middle- to upper-amphibolite-facies peak metamorphic conditions estimated at ??0.4-0.5 GPa and 600-670 ??C. The schists display an intense, shallowly dipping, S1 composite shear foliation with local micrometer- to decimeter-scale recumbent folds and S-C' shear band structures that formed at high temperatures. Zones of chaotically oriented foliation, resembling breccias but showing no signs of retrogression, are developed locally and are interpreted as shear-disrupted fold hinges. Mineral textural relations in the mica schists indicate that the metamorphic peak was attained during D1. Fabric analysis indicates, however, that subhorizontal shear deformation continued during retrograde cooling, forming mylonite zones in which high-temperature shear fabrics (S-C and S-C') are overprinted by progressively lower- temperature fabrics. Cataclasites and carbonate-cemented breccias in more competent lithologies such as the calc-silicate unit and in the felsic gneiss found as boulders in the overlying impactite succession may refl ect a fi nal pulse of low-temperature cataclastic deformation during D1. These breccias and the shear and mylonitic foliations are cut by smaller, steeply inclined anastomosing fractures with chlorite and calcite infill (interpreted as D2). This D2 event was accompanied by extensive chlorite-sericitecalcite ?? epidote retrogression and appears to predate the impact event. Granite and granite pegmatite veins display local discordance to the S1 foliation, but elsewhere

Distribution of garnet grain sizes and morphologies across the Moine Supergroup, northern Scottish Caledonides

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Ashley, Kyle T.; Thigpen, J. Ryan; Law, Richard D.

2016-04-01

Garnet is used in a wide range of geologic studies due to its important physical and chemical characteristics. While the mineral is useful for thermobarometry and geochronology constraints and can often be correlated to deformation and fabric development, difficulties remain in making meaningful interpretations of such data. In this study, we characterize garnet grain sizes and crystal morphologies from 141 garnet-bearing metasedimentary rock samples collected from the northern part of the Moine Supergroup in the Scottish Caledonides. Larger, euhedral crystals are indicative of prograde metamorphic growth and are typically associated with the most recent phase of orogenesis (Scandian, ˜430 Ma). Small, rounded ("pin-head") garnets are interpreted as detrital in origin. A subhedral classification is more subjective and is used when garnets contains portions of straight boundaries but have rounded edges or rims that have been altered through retrograde metamorphic reactions. From our collection, 88 samples contain anhedral garnets (maximum measured grain size d = 0.46 ± 0.21 mm), 34 bear subhedral garnets (d = 2.0 ± 1.0 mm), and the remaining 19 samples contain garnets with euhedral grains (d = 4.4 ± 2.6 mm). Plotting the distribution of garnets relative to the mapped thrust contacts reveals an abrupt change in morphology and grain size when traced from the Moine thrust sheet across the Ben Hope and Sgurr Beag thrusts into the higher-grade, more hinterland-positioned thrust sheets. The dominance of anhedral garnets in the Moine thrust sheet suggests that these grains should not be used for peak P - T estimation associated with relatively low temperature (advance of interpreting large suits of garnet-derived thermodynamic and geochronologic data.

Braid foliations in low-dimensional topology

CERN Document Server

LaFountain, Douglas J

2017-01-01

This book is a self-contained introduction to braid foliation techniques, which is a theory developed to study knots, links and surfaces in general 3-manifolds and more specifically in contact 3-manifolds. With style and content accessible to beginning students interested in geometric topology, each chapter centers around a key theorem or theorems. The particular braid foliation techniques needed to prove these theorems are introduced in parallel, so that the reader has an immediate "take-home" for the techniques involved. The reader will learn that braid foliations provide a flexible toolbox capable of proving classical results such as Markov's theorem for closed braids and the transverse Markov theorem for transverse links, as well as recent results such as the generalized Jones conjecture for closed braids and the Legendrian grid number conjecture for Legendrian links. Connections are also made between the Dehornoy ordering of the braid groups and braid foliations on surfaces. All of this is accomplished w...

Transversal Dirac families in Riemannian foliations

International Nuclear Information System (INIS)

Glazebrook, J.F.; Kamber, F.W.

1991-01-01

We describe a family of differential operators parametrized by the transversal vector potentials of a Riemannian foliation relative to the Clifford algebra of the foliation. This family is non-elliptic but in certain ways behaves like a standard Dirac family in the absolute case as a result of its elliptic-like regularity properties. The analytic and topological indices of this family are defined as elements of K-theory in the parameter space. We indicate how the cohomology of the parameter space is described via suitable maps to Fredholm operators. We outline the proof of a theorem of Vafa-Witten type on uniform bounds for the eigenvalues of this family using a spectral flow argument. A determinant operator is also defined with the appropriate zeta function regularization dependent on the codimension of the foliation. With respect to a generalized coupled Dirac-Yang-Mills system, we indicate how chiral anomalies are located relative to the foliation. (orig.)

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.

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

Geology and geochronology of Mata Surrao granites - South-West of Rio Maria - Para State, Brazil

International Nuclear Information System (INIS)

Duarte, K.D.; Pereira, E.D.; Dall'Agnol, R.; Lafon, J.M.

1991-01-01

This paper summarize the preliminary data about a geological mapping on the scale 1:50.000 located at an area in the southeastern part of the Para State. The recognized units comprise the Mata Surrao granite, which is within the typical Archean Granite-Greenstone Terrain of Rio Maria, and has mainly a monzogranitic composition. Its foliation is restricted to the north and east borders. The mapped host rocks are represented by Tonalitic Ortho gneisses, Gneisses with Pegmatites, Migmatite Gneisses, both latter show different deformation rates. Rb/Sr on whole rock systematics had been applied for the Mata Surrao granite and yield an age of 2541 ± 74 Ma with Sr initial ratio of 0.71040 ± 343 (MSWD = 2.81). This data revealed another Archean granitic body (strictu sensu) related to the Rio Maria Granite-Greenstone Terrain. Such age can be interpreted either as the crystallization age of this granitic body, or a renewed one caused by the thermo tectonic event that affected the region at the end of Archean time. It can be deduced from the initial ratio that an important crustal contribution controlled the Mata Surrao granite genesis. (author)

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.

Strongly foliated garnetiferous amphibolite clasts in ophiolitic melanges, Yarlung Zangbo Suture Zone, Tibet; Early Cretaceous disruption of a back-arc basin?

Science.gov (United States)

Guilmette, C.; Hebert, R.; Wang, C.; Indares, A. D.; Ullrich, T. D.; Dostal, J.; Bedard, E.

2007-12-01

Metre to decameter-size clasts of amphibolite are found embedded in ophiolitic melanges underlying the Yarlung Zangbo Suture Zone Ophiolites, South Tibet, China. These ophiolites and melanges occur at the limit between Indian and Tibetan-derived rocks and represent remnants of an Early Cretaceous intraoceanic supra-subduction zone domain, the Neo-Tethys. In the Saga-Dazuka segment (500 km along-strike), we discovered new occurrences of strongly foliated amphibolites found as clasts in the ophiolitic melange. In garnet-free samples, hornblende is green-blue magnesio-hornblende and cpx is low-Al diopside. In garnet- bearing samples, garnet is almandine with a strong pyrope component (up to 30 mol%) whereas coexisting hornblende is brown Ti-rich tschermakite and clinopyroxene is Al-diopside. Plagioclase composition was ubiquitously shifted to albite during a late metasomatic event. Geochemistry of these rocks indicates that their igneous protoliths crystallized from a slightly differentiated tholeiitic basaltic liquid that did not undergo major fractionation. Trace element patterns reveal geochemical characteristics identical to those of the overlying ophiolitic crust. These are 1) trace element abundances similar to that of N-MORBs or BABBs, 2) a slight depletion of LREE and 3) a moderate to strong Ta-Nb negative anomaly and a slight Ti anomaly. Such characteristics suggest genesis over a spreading center close to a subduction zone, possibly a back-arc basin. Step-heating Ar/Ar plateau ages were obtained from hornblende separates. All ages fall in the range of 123-128 Ma, overlapping the crystallization ages from the overlying ophiolite (126-131 Ma). Pseudosections were built with the THERMOCALC software in the system NCFMASH. Results indicate that the observed assemblage Hb+Pl+Gt+Cpx is stable over a wide range of P-T conditions, between 10-18 kbars and at more than 800°C. Measured mineral modes and solid solution compositions were successfully modeled, indicating

Quartz-Amethyst Hosted Hydrocarbon-Bearing Fluid Inclusions from the Green Ridge Breccia in the Snoqualmie Granite, North Cascades, WA, USA

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Martin Feely

2017-09-01

Full Text Available The Green Ridge Breccia cuts the composite Miocene Snoqualmie Batholith in King County, WA, USA. The granite was emplaced at ~5 km depth between ~17 and 20 Ma and the crosscutting NW trending breccia contains large angular blocks of the host granite (<1 m in longest dimension. The brecciated granite blocks are cemented by quartz-amethyst euhedra (<10 cm in longest dimension bearing vugs. A notable feature is the presence of centimetric scale amber coloured oil inclusions within the quartz-amethyst crystals. Fluid inclusion studies using Transmitted Light Petrography, UV Microscopy, Microthermometry, Laser Raman Microspectroscopy and Gas Chromatography-Mass Spectrometry record the presence and the fluid composition of three fluid inclusion types hosted by the euhedra: primary Type 1 (liquid rich two-phase (L + V aqueous inclusions and secondary Type 2 bituminous two-phase (S + L inclusions and Type 3 amber coloured oil bearing two-phase immiscible liquid inclusions. The Green Ridge Breccia was the locus for convective hydrothermal fluid flow that formed the quartz-amethyst vugs formed at T~390 °C assuming a trapping pressure of ~1.65 kb. Later, hydrocarbon fluids migrated downwards from the roof source rock (e.g., the Guye Sedimentary Member and were trapped in the euhedra. This was followed by unroofing of the batholith and exposure of the Green Ridge Breccia. This study highlights the potential for other oil migrations into the Snoqualmie Batholith in areas where it forms the basement capped by the Guye Sedimentary Member.

Selenium-75-labelled foliate compounds

International Nuclear Information System (INIS)

1974-01-01

A saturation method to analyze a foliate is presented; it uses competitive reaction of the compound to be measured and of a radioactive-labelled version of this compound with a reagent specific to this compound present in insufficient quantity to combine with the whole of the compound and its labelled version, separation of the bound compound from its non-bound homologue and measurement of the radioactivity concentration in the bound compound, the non-bound compound or both. The radioactive isotope used in the labelled foliate is selenium 75 [fr

Petrography and petrology of the Ayghalesi granite, east of Takab area (northwest of Iran

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Saeed Kamran

2017-03-01

Full Text Available The investigated granite intrusion is located at the north of Ayghalesi village, east of Takab The Ayghalesi granite has been intruded the Eocene sandstone and conglomerate rocks and low grade metamorphic hornfels have been metamorphosed host rocks. The main constituent minerals are K-feldspar, plagioclase, quartz and muscovite.and minor garnet. The main texture is granular but pegmatitic, myrmektitic, graphic and perthitic occur as minor textures. Chemically, the rocks are granite on the various classification diagrams. The Ayghalesi intrusion body is classified as S-type, peraluminous composition, calc-alkaline nature and is calcic-alkali to alkali-calcic on the base of modified alkali lime index (MALI. The investigated body, on the tectonic discrimination diagrams, fall on syn-collisional tectonic setting domain, suggesting that it was originated during collision of Central Iranian and Arabian plates Key words: granite,

Geochronological investigation of the Ingerdal granite gneiss and discordant pegmatites from the western gneiss region, Norway

International Nuclear Information System (INIS)

Tucker, R.D.; Krogh, T.E.

1988-01-01

A seven-point (three zircon and four titanite ) U-Pb discordia-line from the Ingdal granite gneiss defines upper- and lover-intercept ages of 1653 ±2 Ma and 396 ±5 Ma interpreted as the time of Ingdal granite emplacement, and the time of gneiss formation and partial Pb-loss from zircon and titanite during a regional metamorphic event, respectively. These isotopic data suggest that this part of the western gneiss region was heated and cooled very quickly at both the upper- and lower-intercept ages, and that it did not experience significant Sveconorwegian (appr. 1250-900 Ma) or Finnmarkian (appr. 530-480 Ma) isotopic disturbance. A six-point Rb-Sr whole-rock errorchron (MSWD=11) from the same body of the Ingdal granite gneiss defines a date of 1665 ±49 Ma interpreted as a less precise age of granite emplacement. Rb-Sr mineral dates from three strongly discordant, non-foliated granite pegmatites fall in the age range of 415-379 Ma. A Rb-Sr biotite date of 372 ±4 Ma from the Ingdal granite gneiss establishes a minimum age of isotopic disturbance in the region

Foliated eight-manifolds for M-theory compactification

Science.gov (United States)

Babalic, Elena Mirela; Lazaroiu, Calin Iuliu

2015-01-01

We characterize compact eight-manifolds M which arise as internal spaces in flux compactifications of M-theory down to AdS3 using the theory of foliations, for the case when the internal part ξ of the supersymmetry generator is everywhere non-chiral. We prove that specifying such a supersymmetric background is equivalent with giving a codimension one foliation of M which carries a leafwise G 2 structure, such that the O'Neill-Gray tensors, non-adapted part of the normal connection and the torsion classes of the G 2 structure are given in terms of the supergravity four-form field strength by explicit formulas which we derive. We discuss the topology of such foliations, showing that the C * algebra is a noncommutative torus of dimension given by the irrationality rank of a certain cohomology class constructed from G, which must satisfy the Latour obstruction. We also give a criterion in terms of this class for when such foliations are fibrations over the circle. When the criterion is not satisfied, each leaf of is dense in M.

Group foliation of finite difference equations

Science.gov (United States)

Thompson, Robert; Valiquette, Francis

2018-06-01

Using the theory of equivariant moving frames, a group foliation method for invariant finite difference equations is developed. This method is analogous to the group foliation of differential equations and uses the symmetry group of the equation to decompose the solution process into two steps, called resolving and reconstruction. Our constructions are performed algorithmically and symbolically by making use of discrete recurrence relations among joint invariants. Applications to invariant finite difference equations that approximate differential equations are given.

Foliated control theory and its applications

Energy Technology Data Exchange (ETDEWEB)

Jones, L E [Department of Mathematics, State University of New York at Stony Brook, Stony Brook (United States)

2002-08-15

The control theorems and fibered control theorems due to Chapman, Ferry and Quinn, concerning controlled h-cobordisms and controlled homotopy equivalences, are reviewed. Some foliated control theorems, due to Farrell and Jones, are formulated and deduced from the fibered control theorems. The role that foliated control theory plays in proving the Borel conjecture for closed Riemannian manifolds having non-positive sectional curvat and in calculating Whitehead groups for the fundamental group of such manifolds, is described. (author)

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

Temporal and spatial foliations of spacetimes.

Science.gov (United States)

Herold, H.

For the solution of initial-value problems in numerical relativity usually the (3+1) splitting of Einstein's equations is employed. An important part of this splitting is the choice of the temporal gauge condition. In order to estimate the quality of time-evolution schemes, different time slicings of given well-known spherically symmetric spacetimes have been studied. Besides the maximal slicing condition the harmonic slicing prescription has been used to calculate temporal foliations of the Schwarzschild and the Oppenheimer-Snyder spacetime. Additionally, the author has studied a recently proposed, geometrically motivated spatial gauge condition, which is defined by considering the foliations of the three-dimensional space-like hypersurfaces by 2-surfaces of constant mean extrinsic curvature. Apart from the equations for the shift vector, which can be derived for this gauge condition, he has investigated such spatial foliations for well-known stationary axially symmetric spacetimes, namely for the Kerr metric and for numerically determined solutions for rapidly rotating neutron stars.

Experimental study of quartz inclusions in garnet at pressures up to 3.0 GPa: evaluating validity of the quartz-in-garnet inclusion elastic thermobarometer

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Thomas, Jay B.; Spear, Frank S.

2018-05-01

Garnet crystals with quartz inclusions were hydrothermally crystallized from oxide starting materials in piston-cylinder apparatuses at pressures from 0.5 to 3 GPa and temperatures ranging from 700 to 800 °C to study how entrapment conditions affect remnant pressures of quartz inclusions used for quartz-in-garnet (QuiG) elastic thermobarometry. Systematic changes of the 128, 206 and 464 cm-1 Raman band frequencies of quartz were used to determine pressures of quartz inclusions in garnet using Raman spectroscopy calibrations that describe the P-T dependencies of Raman band shifts for quartz under hydrostatic pressure. Within analytical uncertainties, inclusion pressures calculated for each of the three Raman band frequencies are equivalent, which suggests that non-hydrostatic stress effects caused by elastic anisotropy in quartz are smaller than measurement errors. The experimental quartz inclusions have pressures ranging from - 0.351 to 1.247 GPa that span the range of values observed for quartz inclusions in garnets from natural rocks. Quartz inclusion pressures were used to model P-T conditions at which the inclusions could have been trapped. The accuracy of QuiG thermobarometry was evaluated by considering the differences between pressures measured during experiments and pressures calculated using published equation of state parameters for quartz and garnet. Our experimental results demonstrate that Raman measurements performed at room temperature can be used without corrections to estimate garnet crystallization pressures. Calculated entrapment pressures for quartz inclusions in garnet are less than 10% different from pressures measured during the experiments. Because the method is simple to apply with reasonable accuracy, we expect widespread usage of QuiG thermobarometry to estimate crystallization conditions for garnet-bearing silicic rocks.

Geology and geochemistry of the Middle Proterozoic Eastern Ghat mobile belt and its comparison with the lower crust of the Southern Peninsular shield

Science.gov (United States)

Rao, M. V. Subba

1988-01-01

Two prominent rock suites constitute the lithology of the Eastern Ghat mobile belt: (1) the khondalite suite - the metapelites, and (2) the charnockite suite. Later intrusives include ultramafic sequences, anorthosites and granitic gneisses. The chief structural element in the rocks of the Eastern Ghats is a planar fabric (gneissosity), defined by the alignment of platy minerals like flattened quartz, garnet, sillimanite, graphite, etc. The parallelism between the foliation and the lithological layering is related to isoclinal folding. The major structural trend (axial plane foliation trend) observed in the belt is NE-SW. Five major tectonic events have been delineated in the belt. A boundary fault along the western margin of the Eastern Ghats, bordering the low grade terrain has been substantiated by recent gravity and the deep seismic sounding studies. Field evidence shows that the pyroxene granulites (basic granulites) post-date the khondalite suite, but are older than the charnockites as well as the granitic gneisses. Polyphase metamorphism, probably correlatable with different periods of deformation is recorded. The field relations in the Eastern Ghats point to the intense deformation of the terrain, apparently both before, during and after metamorphism.

Foliation: Geological background, rock mechanics significance, and preliminary investigations at Olkiluoto

International Nuclear Information System (INIS)

Milnes, A.G.; Hudson, J.; Wikstroem, L.; Aaltonen, I.

2006-01-01

A well developed, pervasive foliation is a characteristic feature of the migmatites and gneisses in the Olkiluoto bedrock, and is expected to have a significant influence on the underground construction, the design and layout and the groundwater flow regime of a deep spent nuclear fuel repository. This Working Report reviews the geological background and rock mechanics significance of foliation, and develops a methodology for the systematic acquisition of foliation data in cored boreholes and in tunnels at the Olkiluoto site, to provide the necessary basis for future geological, rock mechanics and hydrogeological modelling. The first part of the methodology concerns foliation characterisation, and develops a characterisation scheme based on two variables: the foliation type (G = gneissic, B = banded, S = schistose), which is a function of mineral composition and degree of smallscale heterogeneity, and the foliation intensity (1 = low, 2 = intermediate, 3 = high), which is a function of the type and intensity of the deformation by which it was produced (under high-grade metamorphic conditions in the core of the Svecofennian orogenic belt). At the suggested reference scales (1 m length of core, 10 m 2 area of tunnel wall), the most representative foliation type and intensity is assessed using a standard set of core photographs, which are included as an Appendix at the end of the report, providing a systematic description in terms of 9 descriptive types (G1, G2, G3, B1, B2, B3, S1, S2, S3). As a further step, the rock mechanics significance of these types is assessed and a rock mechanics foliation (RMF) number is assigned (RMF 0 = no significance, RMF 1, RMF 2 and RMF 3 = low, intermediate and high significance, respectively). The second part of the methodology concerns the orientations of the foliation within the same 1 m core lengths or 10 m2 wall areas, which have been characterised as above. This combined analysis of foliation character and foliation orientation

Smooth Maps of a Foliated Manifold in a Symplectic Manifold

Indian Academy of Sciences (India)

Let be a smooth manifold with a regular foliation F and a 2-form which induces closed forms on the leaves of F in the leaf topology. A smooth map f : ( M , F ) ⟶ ( N , ) in a symplectic manifold ( N , ) is called a foliated symplectic immersion if restricts to an immersion on each leaf of the foliation and further, the ...

Release of uranium through cataclastic deformation of Mansehra granite gneiss and its precipitation in the overlying intramontane basin in northern Pakistan

International Nuclear Information System (INIS)

Butt, K.A.

1989-01-01

The Mansehra pluton belongs to a discontinuous belt of two mica granites of the Lesser Himalayas. The Mansehra granite is generally foliated except in the area around Mansehra. Several phases of granitic activity have been reported from the Mansehra Complex. Shams and Rahman have demonstrated that the younger phases tend to be enriched in Na 2 O. Ashraf extensively studied minor bodies ranging from albitites through aplites to pegmatites and suggested a late stage albitization event. The northern edge of this sheet-like granitic mass has undergone extensive cataclastic deformation, resulting in the formation of shear zones, mylonites and cataclasites. A chemical comparison of crushed granite with granite outside the shear zone suggests little chemical reconstitution in terms of major elements during cataclastic deformation. A huge shear zone in albitized granite gneiss has yielded secondary uranium minerals at water seepages, suggesting a liberation of uranium. Hydrogeochemical surveys of the crushed granite and adjoining areas suggest that uranium from crushed granite was easily leachable in comparison with rocks outside the shear zone. The uranium thus liberated was trapped in a Pleistocene sequence of clays and unsorted fluviatile sand overlying the granite and country rock metamorphics. (author). 17 refs, 2 figs, 2 tabs

Smooth maps of a foliated manifold in a symplectic manifold

Indian Academy of Sciences (India)

Abstract. Let M be a smooth manifold with a regular foliation F and a 2-form ω which induces closed forms on the leaves of F in the leaf topology. A smooth map f : (M, F) −→ (N,σ) in a symplectic manifold (N,σ) is called a foliated symplectic immersion if f restricts to an immersion on each leaf of the foliation and further, the.

Geochemistry, geochronology and Nd isotopes of the Gogó da Onça Granite: A new Paleoproterozoic A-type granite of Carajás Province, Brazil

Science.gov (United States)

Teixeira, Mayara Fraeda Barbosa; Dall'Agnol, Roberto; Santos, João Orestes Schneider; de Sousa, Luan Alexandre Martins; Lafon, Jean-Michel

2017-12-01

The Gogó da Onça Granite (GOG) comprise a stock located in the Carajás Province in the southeastern part of Amazonian Craton near its border with the Araguaia Belt. Three facies were identified in the pluton: biotite-amphibole granodiorite, biotite-amphibole monzogranite and amphibole-biotite syenogranite. The GGO crosscut discordantly the Archean country rocks and are not foliated. All Gogó da Onça Granite varieties are metaluminous, ferroan A2-subtype granites with reduced character. The major and trace element behavior suggests that its different facies are related by fractional crystallization. Zircon and titanite U-Pb SHRIMP ages show that the pluton crystallized at ∼1880-1870 Ma and is related to the remarkable Paleoproterozoic magmatic event identified in the Carajás Province. Whole-rock Nd isotope data (TDM ages 2.78 to 2.81, εNd values of -9.07 to -9.48) indicate that the GOG magmas derived from an Archaean source compatible with that of some other Paleoproterozoic suites from Carajás Province. The GOG show significant contrasts with the Jamon and Velho Guilherme Paleoproterozoic suites from Carajás Province and the inclusion of the Gogó da Onça granite in any of these suites is not justified. The GOG is more akin to the Serra dos Carajás Suite and to the Seringa and São João granites of Carajás and to the Mesoproterozoic Sherman granite of USA and the Paleoproterozoic Suomenniemi Batholith of Finland. This study puts in evidence the relevance of precise geochronological data and estimation of magma oxidation state in the characterization and correlation of A-type granites.

β-Catenin is critical for cerebellar foliation and lamination.

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Jing Wen

Full Text Available The cerebellum has a conserved foliation pattern and a well-organized layered structure. The process of foliation and lamination begins around birth. β-catenin is a downstream molecule of Wnt signaling pathway, which plays a critical role in tissue organization. Lack of β-catenin at early embryonic stages leads to either prenatal or neonatal death, therefore it has been difficult to resolve its role in cerebellar foliation and lamination. Here we used GFAP-Cre to ablate β-catenin in neuronal cells of the cerebellum after embryonic day 12.5, and found an unexpected role of β-catenin in determination of the foliation pattern. In the mutant mice, the positions of fissure formation were changed, and the meninges were improperly incorporated into fissures. At later stages, some lobules were formed by Purkinje cells remaining in deep regions of the cerebellum and the laminar structure was dramatically altered. Our results suggest that β-catenin is critical for cerebellar foliation and lamination. We also found a non cell-autonomous role of β-catenin in some developmental properties of major cerebellar cell types during specific stages.

Greenschist-Facies Pseudotachylytes and Gouge: a Microstructural Study of the Deformation Propagation at the Boundary Between Hp-Metabasite and Calcite Bearing Metasediments

Science.gov (United States)

Crispini, L.; Scambelluri, M.; Capponi, G.

2013-12-01

Recent friction experiments on calcite-bearing systems reproduce pseudotachylyte structures, that are diagnostic of dinamic calcite recrystallization related to seismic slip in the shallow crust. Here we provide the study of a pseudotachylyte (PT) bearing low angle oblique-slip fault. The fault is linked to the exhumation of Alpine HP-ophiolites and it is syn- to post-metamorphic with respect to retrograde greenschist facies metamorphism. The observed microstructures developed at the brittle-ductile transition and suggest that seismic and interseismic slip was enhanced by interaction with fluids. The fault zone is in-between high-pressure eclogite-facies metabasites (hangingwall) and calcite bearing metasediments (footwall). The mafic rocks largely consist of upper greenschist facies hornblende, albite, chlorite, epidote with relict eclogitic garnet, Na-pyroxene and rutile; metasediments correspond to calcschist and micaschist with quartz, phengite, zoisite, chlorite, calcite and relics of garnet. Key features of the oucrop are: the thickness and geometry of the PT and gouge; the multiple production of PT characterized by overprinting plastic and brittle deformation; the occurrence in footwall metasediments of mm-thick bands of finely recrystallized calcite coeval with PT development in the hangingwall. The damage zone is ca. 2 m-thick and is characterized by two black, ultra-finegrained straight and sharp Principal Slip Zones (PSZ) marked by PT. The damage zone shows a variety of fault rocks (cataclasite and ultracataclasite, gouge and PT) with multiple crosscutting relationships. Within the two main PSZ, PT occurs in 10-20 cm thick layer, in small scale injection veins and in microfractures. In the mafic hanging wall, the PT is recrystallized and does not preserve glass: it shows flow structures with subrounded, embayed and rebsorbed quartz in a fine grained matrix composed of isotropic albite + chlorite + quartz + epidote + titanite, suggesting recrystallization

On the existence of Levi Foliations

Directory of Open Access Journals (Sweden)

RENATA N. OSTWALD

2001-03-01

Full Text Available Let L be a real 3 dimensional analytic variety. For each regular point p L there exists a unique complex line l p on the space tangent to L at p. When the field of complex line p l p is completely integrable, we say that L is Levi variety. More generally; let L M be a real subvariety in an holomorphic complex variety M. If there exists a real 2 dimensional integrable distribution on L which is invariant by the holomorphic structure J induced by M, we say that L is a Levi variety. We shall prove: Theorem. Let be a Levi foliation and let be the induced holomorphic foliation. Then, admits a Liouvillian first integral. In other words, if is a 3 dimensional analytic foliation such that the induced complex distribution defines an holomorphic foliation ; that is, if is a Levi foliation; then admits a Liouvillian first integral--a function which can be constructed by the composition of rational functions, exponentiation, integration, and algebraic functions (Singer 1992. For example, if f is an holomorphic function and if theta is real a 1-form on ; then the pull-back of theta by f defines a Levi foliation : f*theta = 0 which is tangent to the holomorphic foliation : df = 0. This problem was proposed by D. Cerveau in a meeting (see Fernandez 1997.Seja L Ì uma variedade real de dimensão 3. Para todo ponto regular p Î L existe uma única reta complexa l p no espaço tangente à L em p. Quando o campo de linhas complexas p l p é completamente integrável, dizemos que L é uma variedade de Levi. Mais geralmente, seja L Ì M uma subvariedade real em uma variedade analítica complexa. Se existe uma distribuição real integrável de dimensão 2 em L que é invariante pela estrutura holomorfa J induzida pela variedade complexa M, dizemos que L é uma variedade de Levi. Vamos provar: Teorema. Seja uma folheação de Levi e seja a folheação holomorfa induzida. Então tem integral primeira Liouvilliana. Em outras palavras, se é uma folheação real de

Pluton emplacement in a releasing bend in a transpressive regime: the arrozal granite in the Paraíba do Sul shear belt, Rio de Janeiro

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Alexis R. Nummer

2007-06-01

Full Text Available The Arrozal Granite, situated in the southwestern region of the State of Rio de Janeiro, has a granitic to granodioritic composition. It contains a strong mylonitic foliation along its border, passing gradually to a well-developed magmatic foliation towards its center. Structural analysis indicates that the Arrozal Granite was emplaced along the Além-Paraíba Shear Zone in a dextral transpressive tectonic regime. A regional shift of the trend along this shear zone from NE-SW to E-W, observed in the area, is interpreted to be casually related to the creation of space for the emplacement of the granite. Our data indicate that releasing bends may have played an important role for space generation during the emplacement of the Arrozal Granite and other plutons.O Granito Arrozal ocorre na porção sudoeste do Estado do Rio de Janeiro e associa-se à Zona de Cisalhamento de Além-Paraíba. Possui composição granítica a granodiorítica eexibe predomínio de estruturas magmáticas na parte central, e estruturas de alto strain (miloníticas nas bordas. Os dados estruturais sugerem colocação em segmentos extensionais(releasing bends associados a uma tectônica transcorrentedestral, sob regime transpressivo. A forte mudança do trend estrutural desta zona de cisalhamento na região, passando de NE-SW para próximo de E-W, criou condições para geração de espaços que favoreceram a colocação do Granito Arrozal, além de outros granitos associados à referida zona.

Defining conditions of garnet growth across the central and southern Menderes Massif, western Turkey

Science.gov (United States)

Etzel, T. M.; Catlos, E. J.; Kelly, E. D.; Cemen, I.; Ozerdem, C.; Atakturk, K. R.

2017-12-01

Here we apply thermodynamic modeling using Theriak-Domino to garnet-bearing rocks from the central and southern portions of the Menderes Massif to gain insight into the dynamics of western Turkey as the region experienced a transition from collisional to extensional tectonics. To this end, we report new pressure-temperature (P-T) paths from garnet-bearing rocks collected along the Alasehir detachment fault, a prominent exhumation structure in the central portion of the Menderes Massif in western Turkey, constituting the southern margin of the Alasehir Graben. These paths are compared to those from the Selimiye shear zone in the Southern (Cine) Massif. Two Alasehir garnets collected from the same outcrop record two P-T paths: 1) a prograde path beginning at 565oC and 6.4 kbar increasing to 592 oC and 7.5 kbar; and 2) near isobaric growth initiating at 531oC and 7.1 kbar and terminating at 571oC and 7.3 kbar. High-resolution P-T paths could not be modeled for the majority of Alasehir samples due to diffusional modification of garnet. However, conditions were estimated by garnet isopleth thermobarometry at the point of highest spessartine content for each crystal. Calculated P-T values for this subset of samples range between 566-651oC and 6.2-6.8 kbar. Despite this broad range, these P-T conditions are consistent with what is observed in the modeled paths. Th-Pb ages of matrix monazite range from 35.8±3.0 to 20.6±2.4 Ma, suggesting metamorphism in the central Menderes Massif occurred over a 15 m.y. period. Selimiye shear zone rocks show distinct N-shaped P-T paths, suggesting garnets in the central and southern portion of the Menderes Massif record distinctly different tectonic histories.

Industrial garnet

Science.gov (United States)

Olson, D.W.

2000-01-01

The state of the global industrial garnet industry in 1999 is discussed. Industrial garnet mined in the U.S., which accounts for approximately one-third of the world's total, is usually a solid-solution of almandine and pyrope. The U.S. is the largest consumer of industrial garnet, using an estimated 47,800 st in 1999 as an abrasive and as a filtration medium in the petroleum industry, filtration plants, aircraft and motor vehicle manufacture, shipbuilding, wood furniture finishing operations, electronic component manufacture, ceramics manufacture, and glass production. Prices for crude concentrates ranged from approximately $50 to $110/st and refined garnet from $50 to $215/st in 1999, depending on type, source, quantity purchased, quality, and application.

Foliated vector fields, the Godbillon-Vey invariant and the invariant I(F)

International Nuclear Information System (INIS)

Banyaga, A.; Landa, Alain Musesa

2004-03-01

We prove that if the invariant I(F) constructed in 'An invariant of contact structures and transversally oriented foliations', Ann. Global Analysis and Geom. 14(1996) 427-441 (A. Banyaga), through the Lie algebra of infinitesimal automorphisms of transversally oriented foliations F is trivial, then the Godbillon-Vey invariant GV (F) of F is also trivial, but that the converse is not true. For codimension one foliations, the restrictions I τ , (F) of I(F) to the Lie subalgebra of vector fields tangent to the leaves is the Reeb class R(F) of F. We also prove that if there exists a foliated vector field which is everywhere transverse to a codimension one foliation, then the Reeb class R(F) is trivial, hence so is the GV(F) invariant. (author)

Zircon U-Pb geochronology and geochemistry of granites in the Zhuguangshan complex, South China: Implications for uranium mineralization

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Zhang, Long; Chen, Zhenyu; Li, Xiaofeng; Li, Shengrong; Santosh, M.; Huang, Guolong

2018-05-01

The Zhuguangshan complex, composed of Caledonian, Indosinian, and Yanshanian granites, and Cretaceous mafic dykes, is one of the most important granite-hosted uranium producers in South China. Here we present LA-ICP-MS zircon U-Pb and hornblende 40Ar/39Ar geochronology and whole-rock and biotite geochemistry for the granites in this complex to evaluate the magmatism and its constraints on uranium mineralization. Samples collected from the Fuxi, Youdong, Longhuashan, Chikeng, Qiling, and Sanjiangkou intrusions yield zircon weighted 206Pb/238U ages of 426.7 ± 5.4 Ma, 226.4 ± 3.5 Ma, 225.0 ± 2.7 Ma, 152.2 ± 3.0 Ma, 153.9 ± 2.1 Ma, and 155.2 ± 2.1 Ma, respectively. A new Ar-Ar dating of the hornblende of the diabase from the Changjiang uranium ore field yields a plateau age of 145.1 ± 1.5 Ma. These results coupled with published geochronological data indicate that six major magmatic events occurred in the study area at 420-435 Ma, 225-240 Ma, 150-165 Ma, 140 Ma, 105 Ma, and 90 Ma. Both U-bearing and barren granites occur in this complex, and they display differences in whole-rock and biotite geochemistry. The barren granites show higher Al2O3, CaO, TFMM, Rb, Zr, Ba, SI, Mg#, (La/Yb)N, and Eu/Eu*, but lower SiO2, ALK, Rb, DI, Rb/Sr, and TiO2/MgO than those of the U-bearing granites. Biotites in the U-bearing granites are close to the Fe-rich siderophyllite-annite end member with Fe/(Fe + Mg) ratios higher than 0.66, whereas those in the barren granites are relatively close to the Mg-rich eastonite-phlogopite end member with Fe/(Fe + Mg) ratios uranium ore potential of the granites in the Zhuguangshan complex. The geochemical variations of U-bearing and barren granites can serve as a potential detector for granite-hosted uranium deposits.

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

The first discovery of Hadean zircon in garnet granulites from the Sutam River (Aldan Shield)

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Glukhovskii, M. Z.; Kuz'min, M. I.; Bayanova, T. B.; Lyalina, L. M.; Makrygina, V. A.; Shcherbakova, T. F.

2017-09-01

For the first time in Russia, a Hadean zircon grain with an age of 3.94 Ga (ID-TIMS) has been discovered in high-aluminous garnet granulites of the Aldan Shield among the U-Pb zircons with an age from 1.92 Ga. In this connection, the problems of its parental source, the petrogenesis of granulites that captured this zircon, and the mechanism of occurrence of these deep rocks in the upper horizons of the crust have been solved. The comparison of the geochemistry of garnet granulites and the middle crust has shown that the granulites are enriched in the entire range of rare-earth elements (except for the Eu minimum), as well as in Al2O3, U, and Th and are depleted in the most mobile elements (Na, Ca, Sr). In the upper part of the allitic weathering zone of the middle crust, which formed under conditions of arid climate, this zircon grain was originated from the weathered granites from the middle crust. In the latter case, they were empleced discretely in the upper granite-gneiss crust under high pressure conditions (the rutile age is 1.83-1.82 Ga). The zircon with an age of 3.94 Ga is comparable to the Hadean zircons from orthogneisses of the Acasta region (Canadian Shield, 4.03-3.94 Ga).

Strain-dependent evolution of garnets in a high pressure ductile shear zone using Synchroton x-ray microtomography

Science.gov (United States)

Macente, Alice; Fusseis, Florian; Menegon, Luca; John, Timm

2016-04-01

unobstructed by reaction products. - Neighbouring garnet coronas are interconnected, i.e. in direct contact to each other. From a mechanical point of view, we interpret touching garnet coronas that form a rigid, potentially load-supporting framework to affect the rheology of the rock. - In the most highly deformed eclogites, the oblate shapes of elongated garnet clusters reflect a deformational origin of the microfabrics. The clusters define a foliation, whose orientation and intensity we quantified using a star volume distribution algorithm. We interpret the aligned garnet clusters to direct synkinematic fluid flow and consequently influence the transport of dissolved chemical components. - EBSD on garnets shows that, there is no evidence for crystal plastic deformation and all the garnets are internally strain free and show a near-random crystal preferred orientation. There is, however evidence for minor fracturing. We interpret these observations as pointing to a mechanical disintegration of the garnet coronas during strain localisation, and their rearrangement into individual clusters. This process will have been supported by pressure solution/reprecipitation processes. Our study clearly demonstrates what 3- or even 4-dimensional data from reaction microfabrics can add to the understanding of metamorphic processes.

Evolution of fabric in Chitradurga granite (south India) - A study based on microstructure, anisotropy of magnetic susceptibility (AMS) and vorticity analysis

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Mondal, Tridib Kumar

2018-01-01

In this paper, the fabric in massive granite ( 2.6 Ga) from the Chitradurga region (Western Dharwar Craton, south India) is analyzed using microstructure, anisotropy of magnetic susceptibility (AMS) study and kinematic vorticity analysis. The microstructural investigation on the granite shows a progressive textural overprint from magmatic, through high-T to low-T solid-state deformation textures. The mean magnetic foliation in the rocks of the region is dominantly NW-SE striking which have developed during regional D1/D2 deformation on account of NE-SW shortening. The plunge of the magnetic lineation varies from NW to vertical to SE, and interpreted to be a consequence of regional D3 deformation on account of NW-SE to E-W shortening. The vorticity analysis from magnetic fabric in the region reveals that the NW-SE oriented fabric formed under pure shear condition during D1/D2 regional deformation. However, some parts of the region particularly close to the adjacent Chitradurga Shear Zone show that the magnetic fabrics are oblique to the foliation as well as shear zone orientation and inferred to be controlled by simple shearing during D3 regional deformation. The shape preferred orientation (SPO) analysis from oriented thin sections suggest that the shape of the recrystallized quartz grains define the magnetic fabric in Chitradurga granite and the degree of the SPO reduces away from the Chitradurga Shear Zone. It is interpreted that the change in magnetic fabrics in some parts of the granite in the region are dominantly controlled by the late stage sinistral shearing which occurred during the development of Chitradurga Shear Zone. Anisotropy of magnetic susceptibility (AMS) data of granite from the Chitradurga region (West Dharwar Craton, southern India). Km = Mean susceptibility; Pj = corrected degree of magnetic anisotropy; T = shape parameter. K1 and K3 are the maximum and minimum principal axes of the AMS ellipsoid, respectively. dec = Declination; inc

Mixed Messages from Garnet Lu-Hf and Sm-Nd Geochronology

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Vervoort, J. D.; Wang, D.; Johnson, T. A.

2017-12-01

Garnet geochronology provides important information on the timing and conditions of metamorphism. As a major indicator mineral formed during metamorphism, its direct dating can not only help establish the timing of metamorphism, provide the "t" for P-T-t paths, but also, if the dated garnet can be placed in a textural context, can provide information on the timing of deformational features. With advances in chemistry and mass spectrometry, garnet Lu-Hf and Sm-Nd geochronology has become an important geochronological tool and we can now reliably (if not routinely) date a wide variety of garnet compositions formed under diverse conditions. In the course of dating a variety of lithologies using both Lu-Hf and Sm-Nd isotope systems, however, some intriguing results have emerged. Although there are many examples where the Lu-Hf and Sm-Nd systems give the same date within uncertainty, there are also many cases where these systems yield significantly different dates, and the differences between these dates can be considerable—many 10's of Ma of and even 100's of Ma. For example, in garnet-bearing Mesoproterozoic gneisses from across the Blue Ridge Province in Virginia, both Lu-Hf and Sm-Nd analyses (determined on the same solutions) define narrow time spans, but with the Sm-Nd dates systematically younger (for orthogneisses Lu-Hf dates are 1032 to 1019 Ma whereas Sm-Nd dates are 965 to 949 Ma—a difference of 67 to 80 Ma). There are many other examples of systematically younger Sm-Nd garnet dates in both the literature and with our ongoing research. Potential explanations for these differences include: 1) strong partitioning of Lu into garnet during growth yielding ages weighted toward the beginning of growth; 2) faster Lu diffusion from high Lu regions after garnet formation, potentially leading to isochron rotation and anomalously old Lu-Hf dates; and 3) differences in closure temperatures of the two isotope systems. We will review several examples of divergent Lu

The shear zone-related gold mineralization at the Turmalina deposit, Quadrilátero Ferrífero, Brazil: structural evolution and the two stages of mineralization

Science.gov (United States)

Fabricio-Silva, Wendell; Rosière, Carlos Alberto; Bühn, Bernhard

2018-05-01

Turmalina is an important orogenic gold deposit located in the NW region of the Quadrilátero Ferrífero. The deposit is hosted in an Archean greenstone belt composed of ortho-amphibolites and pelites with interleaved tuffs metamorphosed under amphibolite facies conditions and intruded by a granite stock. The orebodies are controlled by WNW-ESE-trending shear zones, associated with hydrothermal alteration. Three deformation events are recognized in the Turmalina gold deposit: D1 and D2 are the result of a progressive Archean deformation under ductile conditions between 2749 ± 7 and 2664 ± 35 Ma; D3 is characterized by a transpressional event under ductile-brittle conditions with the age still unclear. The three generations of garnet observed show that Grt1 blastesis is pre- to syn-D1 and Grt2 growth during the late to post-deformation stages of the D2 event. The initial temperature (Grt1 core) is around 548-600 °C, whereas during late D2, the temperatures reached 633 °C (metamorphic peak-Grt2 rim), likely as a result of granite intrusion. The Grt3 resulted from re-equilibration under retrograde conditions. Two gold-bearing sulfide stages were identified: pyrrhotite-arsenopyrite ± löllingite ± chalcopyrite ± gold stage I precipitated below a metamorphic peak temperature of 598 ± 19 °C associated with S1 foliation (D1), and pyrrhotite-pyrite-arsenopyrite ± chalcopyrite ± gold stage II is located commonly along V3 quartz-carbonate veinlets with a temperature range between 442 ± 9 and 510 ± 30 °C. We suggest that the granite intrusion imposed an additional thermal effect that promoted further dehydration of country rocks. The Au derived mainly from a metamorphic fluid source but potentially mixed with magmatic fluids from the granite.

Difference of ore-bearing and non-ore-bearing pegmatite in the Guangshigou area and its research significance

International Nuclear Information System (INIS)

Zuo Wenqian; Zhang Zhanshi; Sha Yazhou; Rao Chaojun

2011-01-01

Guangshigou uranium deposit is one of the typical granite-pegmatite uranium deposits in China, the ore-body are located in the density zone of the outside contact zone of granite pluton. To distinguish the ore-bearing and Non-ore-bearing pegmatite is one of the most practices and have great significance for the effect of mineral exploration. Based on the field investigation and former research results, contrast research on the characteristics of the pegmatite on petrology, geophysical, geochemistry and stable isotopes have been carried out. It is pointed out that the ore-bearing pegmatite differ from the non-ore-bearing one from macro-and-micro-view in Guangshigou Uranium deposits, the main characteristics are summarized; the macro-and-micro signs are established, the genetic difference between the ore-bearing and non-ore-bearing pegmatite are discussed primarily. The achievements would be helpful for prospecting and researching of this type uranium deposits in China. (authors)

P-T-t metamorphic evolution of highly deformed metapelites from the Pinkie unit of western Svalbard using quartz-in-garnet barometry, trace element thermometry, P-T-X-M diagrams and monazite in-situ dating

Science.gov (United States)

Kośmińska, Karolina; Spear, Frank; Majka, Jarosław

2017-04-01

We present the results of quartz-in-garnet (QuiG) Raman barometry coupled with P-T-X-M diagrams, trace element thermometry, and monazite dating from metapelites of the Pinkie unit on Prins Karls Forland, western Svalbard. This unconventional approach, which combines traditional and novel thermobarometry techniques as well as dating results, provides the opportunity to decipher the pressure-temperature-time (P-T-t) metamorphic evolution of these highly deformed rocks, for which the P-T conditions could not have been obtained using traditional techniques. The Pinkie unit is comprised of Barrovian-type zones expressed by the following three mineral assemblages: Grt+St+Ms+Bt+Pl+Q, Grt+St+Ky+Ms+Bt+Pl+Q and Grt+Ky+Ms+Bt+Pl+Q. The metamorphic assemblages have been strongly affected by pervasive mylonitization. Two generations of garnet are present. Early garnet-I forms large (up to 2 mm) anhedral and inclusion-rich porphyroblasts that are strongly deformed with resorbed rims. Its composition varies from Alm81Grs5Prp11Sps3 in the core to Alm84Grs4Prp10Sps2 in the rim for a St-bearing sample. St-Ky bearing metapelites contain garnet-I, which is characterized by Alm88Grs2Prp8Sps2 in the core and Alm89Grs2Prp8Sps1 in the rim. In the Ky-bearing sample garnet-I composition is varying from Alm77Grs4Prp11Sps8 in the core to Alm83Grs4Prp9Sps4 in the rim. Garnet-II is characterized by small (up to 0.5 mm) euhedral grains that locally overgrows garnet-I. It contains very scarce inclusions, mostly quartz. Grt-II composition is very similar in all Pinkie unit samples and is characterized by Alm80Grs11Prp8Sps1(0). The measured maximum shift of the 464 cm-1 Raman band for quartz in garnet-I is 1.05 cm-1 for St-bearing samples, 1.80 cm-1 for St-Ky bearing rocks, and 2.10 cm-1 for Ky-bearing samples, respectively. The highest shift obtained for inclusions in garnet-II is 2.7 cm-1. Monazite-in-garnet thermometry combined with the QuiG yielded P-T conditions of garnet-I nucleation as

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

Zeroth Poisson Homology, Foliated Cohomology and Perfect Poisson Manifolds

Science.gov (United States)

Martínez-Torres, David; Miranda, Eva

2018-01-01

We prove that, for compact regular Poisson manifolds, the zeroth homology group is isomorphic to the top foliated cohomology group, and we give some applications. In particular, we show that, for regular unimodular Poisson manifolds, top Poisson and foliated cohomology groups are isomorphic. Inspired by the symplectic setting, we define what a perfect Poisson manifold is. We use these Poisson homology computations to provide families of perfect Poisson manifolds.

On the classification of elliptic foliations induced by real quadratic fields with center

Science.gov (United States)

Puchuri, Liliana; Bueno, Orestes

2016-12-01

Related to the study of Hilbert's infinitesimal problem, is the problem of determining the existence and estimating the number of limit cycles of the linear perturbation of Hamiltonian fields. A classification of the elliptic foliations in the projective plane induced by the fields obtained by quadratic fields with center was already studied by several authors. In this work, we devise a unified proof of the classification of elliptic foliations induced by quadratic fields with center. This technique involves using a formula due to Cerveau & Lins Neto to calculate the genus of the generic fiber of a first integral of foliations of these kinds. Furthermore, we show that these foliations induce several examples of linear families of foliations which are not bimeromorphically equivalent to certain remarkable examples given by Lins Neto.

EPMA major and trace element analysis in garnet and its petrological application

International Nuclear Information System (INIS)

Borghi, A.; Ruffini, R.; Cossio, R.; Olmi, F.

2002-01-01

A comparison between major and trace element concentrations in garnet performed by electron microprobe (EPMA) technique is reported. Quantitative spot analyses and x-ray maps of major elements (Fe, Mg, Mn, Ca) and the trace element yttrium in garnets from metamorphic rocks are presented. The selected garnet samples come from meta-pelitic and meta-basic specimens belonging to the tectonic unit of the Monte Rosa Nappe (Western Alps). In the metapelites, the quantitative Y distribution maps display a prominent increase at the core, the Y abundance varying by over two orders of magnitude, from about 80 ppm (rim) to over 2100 ppm. (core). The Y profiles show well defined patterns with sharp features that do not correlate with major element distributions. A roughly comparable pattern can be supposed only with Mn. The Y distribution suggests that the diffusion of Y through the garnet is very slow compared to the major elements, thus the Y results are suitable for geothermometric estimates. In the metabasites, the Y spatial distribution is characterized by an increasing content from the core to the rim, displaying a zoning pattern opposite to the metapelite garnet. Quantitative EPMA analyses range from 1100 ppm at the rim to values lower than the detection limit at the core. Therefore, the Y content in the garnet can be related to several chemical and physical variables such as the bulk rock composition and the phase assemblage. In particular, in the xenotime-bearing metapelitic system the Y distribution seems to be correlated with metamorphic peak temperature. (author)

Preserved magnetic fabrics vs. annealed microstructures in the syntectonic recrystallised George granite, South Africa

Science.gov (United States)

Ferré, E. C.; Améglio, L.

2000-08-01

The Saldanian basement of the Cape Fold Belt of South Africa outcrops in the Kaaimans inlier with granite plutons intruded in low-grade pelitic and quartzitic metasediments around 535 Ma. New field data support a ubiquitous Saldanian top-to-the-north thrust kinematics coeval with granite emplacement with no substantial Cape tectonic overprint. The granites and their contact aureoles display both synkinematic and post-kinematic fabrics. This and the high strain zone commonly observed all along the contact between the Kaaimans inlier and the Cape Fold Belt, suggest a structural decoupling between the basement and its cover. Microstructures in the Kaaimans inlier and in the George pluton establish a post-kinematic, pervasive and thermal overprint of Saldanian age. Granites and country rocks record a medium-temperature/high-strain deformation phase followed by a strong low-temperature/static recrystallisation. Two sets of andalusite porphyroblasts occur systematically in the contact aureoles of the studied plutons and cannot be explained by successive magmatic pulses. The granites, studied by the Anisotropy of Magnetic Susceptibility (AMS) technique, are paramagnetic (20law) and on intrinsic mineral susceptibilities. The magnetic foliations and lineations are homogeneous throughout the George pluton and are consistent with field structures. The AMS results mainly from the magneto-crystalline anisotropy of biotite and from its lattice preferred orientation (LPO) in the rock. The magnetic fabric reveals the biotite subfabrics that had been acquired before static recrystallisation and which was not modified by the subsequent thermal metamorphic event. The magnetic fabric therefore preserves the emplacement-related deformation fabric.

Geology, petrology and geochemistry of the Cacapava do Sul Granitic complex, RS

International Nuclear Information System (INIS)

Nardi, L.V.S.; Bitencourt, M. de F.

1989-01-01

The Cacapava do Sul Granitic Complex comprises mainly hornblende and biotite-rich granodioritic rocks, leucogranitoids which may contain muscovite and garnet, and transitional types of granitoids. The available data suggest that it is a diapiric intrusion synchronous, with the second regional metamorphism and deformation phase, inprinted on the country rocks and on the batholith itself. Geochemical evidences are consistent with a comagmatic character for the granitic rocks and also indicate calc-alkaline affinity, with an origin either from partial melting of the lower crust or from differentiation of mantle-derived basaltic magmas, with crustal contamination. The geochemical features indicate strong similarities with orogenic granitoids intruded in highly mature arcs. The re-evaluation of Rb-Sr data indicates an age of 549 Ma and initial ratio of 0.7051 for the leucogranites. The available data suggest that the studied complex has been emplaced during the late stages of the Brasiliano Cycle, which were marked by the development of ensialic basins and shear zones, with associated granitic magmatism. In its early stages, this orogeny may be interpreted according to the classical model, involving subduction of oceanic crust. (author) [pt

Compositional trends among Kaapvaal Craton garnet peridotite xenoliths and their effects on seismic velocity and density

DEFF Research Database (Denmark)

Schutt, Derek; Lesher, Charles

2010-01-01

garnet and clinopyroxene enrichment. Using the parameterization of Schutt and Lesher (2006) we show that at cratonic mantle temperatures and pressures, orthopyroxene enrichment results in little change in bulk density (ρbulk) and shear-wave velocity (VS), but decreases compressional wave velocities (VP......We examine the modes and compositions of garnet-bearing peridotite xenoliths from the Kaapvaal Craton to quantify factors governing density and seismic velocity variations within metasomatically altered cratonic mantle. Three distinct compositional trends are resolved by principal component...... analysis. The first reflects differences in residue composition resulting from partial melting. The second is associated with orthopyroxene (opx) enrichment, possibly due to silica addition by subduction zone fluids in the source region of the xenoliths. The third principal component reflects garnet...

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

Directory of Open Access Journals (Sweden)

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

Emplacement and deformation of the A-type Madeira granite (Amazonian Craton, Brazil)

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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

The late Variscan ferroan granite magmatism of southern Sardinia: inferences from Mo metallogenesis

Science.gov (United States)

Naitza, Stefano; Conte, Aida Maria; Cuccuru, Stefano; Fadda, Sandro; Fiori, Maddalena; Oggiano, Giacomo; Secchi, Francesco

2017-04-01

Metallogeny is a powerful tool to investigate crustal evolution; a good example is offered by the Variscan basement of Sardinia and its Mo deposits. Mo ores are poorly represented in Variscan metallogenic provinces of Europe: however, in Sardinia, numerous small Mo deposits, often associated to Sn, W and F ores, are present, invariably related to an early Permian intrusive peak bracketed at about 290 Ma (Fadda et al., 2015; Naitza et al., 2017). In Sardinia, two main magmatic peaks have been schematized at pre-300 and 290 Ma. In southern Sardinia, the 290 magmatic peak is made up of several intrusive F-bearing rock-suites (Conte et al., 2016), belonging to ilmenite series, showing a slight peraluminous character and mostly classifiable as ferroan granites (sensu Frost and Frost, 2011). Mo-bearing granites form a distinct suite of relatively small plutons, emplaced at very shallow depth (about 1kb) in an exhumed Variscan low-grade basement. Peculiar characters of Mo-bearing granites are the occurrence of greisenized microgranite and granophyre cupolas, with fayalite-bearing pegmatites, and ilmenite, xenotime-(Y), monazite, fluorite, and local topaz as accessory phases. Recently, Conte et al. (2016) interpreted these granites as originated by partial melting of low crustal felsic metaigneous photoliths enriched in granophiles (Mo, Sn, W). Mo ores occur as: a) endo- and exo- quartz-muscovite greisens with molybdenite±Fe-Cu sulphides, and b) quartz-molybdenite±wolframite±Fe-Cu-Zn sulphides±fluorite±topaz hydrothermal veins and stockworks, hosted in granites or in country rocks. Redox state of magmas exerts a strong control on Mo metallogeny, as in Mo districts worldwide ores are usually hosted by high-fO2 magnetite series intrusions (Ishihara, 1981). The close field association of Sardinian Mo mineralization with ferroan, low-fO2 ilmenite-series granites may be explained in terms of Mo-enriched crustal sources of magmas, and very efficient geochemical

Petrographic and mineralogical features of the uraniferous pink granites in the north eastern desert of egypt

International Nuclear Information System (INIS)

Atawiya, M.Y.; Salman, A.B.; El-Bayyomi, R.M.

1998-01-01

The present work is concerned with the petrological, mineralogical and geochemical studies of some uranium bearing younger granites in the north eastern desert of egypt particularly Gebel Gattar area. The area around Gebel Gattar comprises the following rock units (starting from the oldest): meta volcanic, diorite-grano-diorite complex- Dokhan volcanics- Hammamat sediments, younger granites and dykes. The most significant structural features are represented by NNE-ENE dominantly trending faults and joints. Petrographicaly, the pink granites are divided into normal and mineralized (uraniferous) granites. Normal granites are classified into three types; a) leucocratic perthitic granite, b) hornblende- biotite perthitic granite and c) two feldspars perthitic granite. Mineralized granites are sheared, deformed, pinkish brown in colour and strongly altered. A remarkable secondary uranium mineralization has been recorded along fault and fracture zones

Fluid-aided incorporation of Y into almandine-pyrope garnet via coupled dissolution-reprecipitation

Science.gov (United States)

Harlov, D. E.

2009-12-01

sharp compositional boundaries, which appear to be defined by specific lattice planes as determined by the crystallographic axes of the garnet. These textures are the result of coupled dissolution-reprecipitation (Putnis, 2002, Min Mag, 66, 689), which essentially has resulted in the pseudomorphic partial replacement of a portion of the original garnet by a re-precipitated garnet now enriched in Y. The result from this study suggest that Y may be incorporated into garnet by the aid of fluids, which are both reactive with garnet and in which Y is mobile. In general, this result has strong implications with respect to incorporation of REE (and more specifically HREE) into garnet. It provides a mechanism by which garnet and other Y-bearing minerals, such as xenotime, may equilibrate hence enhancing their use as geothermometers. It also indicates that with respect to both Sm/Nd and Lu/Hf dating, the garnet geochronometer can be reset. More importantly, it implies that diffusion after or inclusion during garnet growth is not the only way by which trace elements may be incorporated into garnet.

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.

2007-02-01

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.

A study of the Eocene S-type granites of Chapedony metamorphic core complex (northeast of Yazd province, Central Iran)

International Nuclear Information System (INIS)

Zakipour, A.; Torabi, Gh.

2016-01-01

The Eocene Chapedony metamorphic core complex, is located in western part of the Posht-e-Badam block. This complex is consisting of migmatite, gneiss, amphibolite, marble, micaschist and various types of granitoids. In middle part of this complex (Kalut-e-Chapedony), an Eocene granitic rock unit cross cuts the other rocks. The minerals of this granite are plagioclase (An 9 Ab 8 7O r 4), potassium feldspars (orthoclase), quartz, euhedral garnet (Alm 7 7Sps 1 3Prp 9 Grs 1 ), zircon, apatite, fibrolitic sillimanite and muscovite. Petrology and geochemical studies reveal calc-alkaline, peraluminous and S-type nature of the studied granites. Chondrite-normalized REE patterns represent evident negative anomaly of Eu and low values of the REEs. Continental crust and North American shale composite (NASC) - normalized multi-elements spider diagrams indicate trace elements depletion. These granites are formed by melting of continental crust sedimentary rocks, resulted by emplacement of mantle-derived magma at the bottom of continental crust which formed the Chapedony metamorphic core complex. The source rock of these granites should be a clay-rich sedimentary rock with low amount of plagioclase and CaO/Na 2 O ratio.

Surfaces foliated by planar geodesics: a model forcurved wood design

DEFF Research Database (Denmark)

Brander, David; Gravesen, Jens

2017-01-01

Surfaces foliated by planar geodesics are a natural model for surfaces made from wood strips. We outline how to construct all solutions, and produce non-trivial examples, such as a wood-strip Klein bottle......Surfaces foliated by planar geodesics are a natural model for surfaces made from wood strips. We outline how to construct all solutions, and produce non-trivial examples, such as a wood-strip Klein bottle...

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.)

Fluid-present melting of meta-igneous rocks and the generation of leucogranites – Constraints from garnet major and trace element data, Lu-Hf whole rock-garnet ages and whole rock Nd-Sr-Hf-O isotope data

NARCIS (Netherlands)

Jung, C.; Jung, S.; Nebel, O.; Hellebrand, E.; Masberg, P.; Hoffer, E.

2009-01-01

Pan-African high-grade metamorphism in the Proterozoic Damara orogen (Namibia) led to formation of garnet-bearing leucosomes in potassic meta-igneous gneisses producing a meta-igneous migmatite. In addition, the migmatite (gneiss (mesosome) plus leucosome) was intruded by small-scale leucogranitic

Determining Age and Origin of Spodumene-Bearing Pegmatites in Southeastern Ireland

Science.gov (United States)

Brown, A. A.; Barros, R.; Menuge, J. F.

2017-12-01

Exploration prospecting around Caldonian Leinster Granite has revealed pegmatite intrusions containing spodumene, a lithium ore, on the eastern margin of the Tullow Lowlands Pluton. Drill cores of these pegmatites have been extracted and studied due to increasing economic interest. Ages between 430 and 400 Ma for spodumene pegmatites have been previously determined using the in situ Rb-Sr isochron method [1]. Here we use the Sm-Nd isochron method to see if the less-mobile nature of REEs during contact metamorphism and deformation impacts ages. Suitable samples containing garnet and feldspar from spodumene and barren pegmatites were studied using regular microscopy and SEM; minerals were then isolated manually. After mineral dissolution and elemental separation via ion exchange columns, a Neptune MS measured Sm and Nd isotope ratios. Blank corrections were applied. Both types of pegmatites were used to calculate an isochron using Isoplot 3.7 [2] which yielded an initial 143Nd/144Nd ratio of 0.51190±0.00009, and an age of 414±52 Ma. Ages and ɛNd, relating to the initial Nd ratio, were compared with previous whole rock data of Leinster Granite [3] and Rb-Sr multimineral data [1]. Comparable ages from both methods likely represent crystallization age. At the minimum possible age considering uncertainty, the origins of pegmatites and granitic rocks are indistinguishable, but at the maximum age, pegmatites show lower ɛNd values suggesting heterogeneous sources. All representative data points held negative ɛNd values signifying crustal assimilation. The Sm-Nd method was found suitable for age/ source investigation; however, Leinster pegmatite garnet is particularly depleted in Nd (Microsoft Excel. Berkeley Geochronology Center Special Publication, 4 [3] Mohr, Peter (1991): "Cryptic Sr and Nd isotopic variation across the Leinster Granite, Southeast Ireland" Geology Magazine, Vol 128, 3, 251-256

Petrographic and geochemical comparisons between the lower crystalline basement-derived section and the granite megablock and amphibolite megablock of the Eyreville-B core, Chesapeake Bay impact structure

Science.gov (United States)

Townsend, Gabrielle N.; Gibson, Roger L.; Horton, J. Wright; Reimold, Wolf Uwe; Schmitt, Ralf T.; Bartosova, Katerina

2009-01-01

The Eyreville B core from the Chesapeake Bay impact structure, Virginia, USA, contains a lower basement-derived section (1551.19 m to 1766.32 m deep) and two megablocks of dominantly (1) amphibolite (1376.38 m to 1389.35 m deep) and (2) granite (1095.74 m to 1371.11 m deep), which are separated by an impactite succession. Metasedimentary rocks (muscovite-quartz-plagioclase-biotite-graphite ± fibrolite ± garnet ± tourmaline ± pyrite ± rutile ± pyrrhotite mica schist, hornblende-plagioclase-epidote-biotite-K-feldspar-quartz-titanite-calcite amphibolite, and vesuvianite-plagioclase-quartz-epidote calc-silicate rock) are dominant in the upper part of the lower basement-derived section, and they are intruded by pegmatitic to coarse-grained granite (K-feldspar-plagioclase-quartz-muscovite ± biotite ± garnet) that increases in volume proportion downward. The granite megablock contains both gneissic and weakly or nonfoliated biotite granite varieties (K-feldspar-quartz-plagioclase-biotite ± muscovite ± pyrite), with small schist xenoliths consisting of biotite-plagioclase-quartz ± epidote ± amphibole. The lower basement-derived section and both megablocks exhibit similar middle- to upper-amphibolite-facies metamorphic grades that suggest they might represent parts of a single terrane. However, the mica schists in the lower basement-derived sequence and in the megablock xenoliths show differences in both mineralogy and whole-rock chemistry that suggest a more mafic source for the xenoliths. Similarly, the mineralogy of the amphibolite in the lower basement-derived section and its association with calc-silicate rock suggest a sedimentary protolith, whereas the bulk-rock and mineral chemistry of the megablock amphibolite indicate an igneous protolith. The lower basement-derived granite also shows bulk chemical and mineralogical differences from the megablock gneissic and biotite granites.

Geology and mineralization of the Jabalat alkali-feldspar granite, northern Asir region, Kingdom of Saudi Arabia

Science.gov (United States)

Al Tayyar, Jaffar; Jackson, Norman J.; Al-Yazidi, Saeed

The Jabalat post-tectonic granite pluton is composed of albite- and oligoclase-bearing, low-calcium, F-, Sn- and Rb-rich subsolvus granites. These granites display evidence of late-magmatic, granitophile- and metallic-element specialization, resulting ultimately in the development of post-magmatic, metalliferous hydrothermal systems characterized by a Mo sbnd Sn sbnd Cu sbnd Pb sbnd Zn sbnd Bi sbnd Ag sbnd F signature. Two main types of mineralization are present within the pluton and its environs: (1) weakly mineralized felsic and aplitic dikes and veins enhanced in Mo, Bi, Ag, Pb and Cu; and (2) pyrite—molybdenite—chalcopyrite-bearing quartz and quartz—feldspar veins rich in Mo, Sn, Bi, Cu, Zn and Ag. A satellite stock, 3 km north of the main intrusion, is composed of fine-grained, miarolitic, muscovite—albite—microcline (microperthite) granite. The flanks of this intrusion and adjacent dioritic rocks are greisenized and highly enriched in Sn, Bi and Ag. Quartz veins which transect the satellite stock contain molybdenite and stannite.

Unimodularity criteria for Poisson structures on foliated manifolds

Science.gov (United States)

Pedroza, Andrés; Velasco-Barreras, Eduardo; Vorobiev, Yury

2018-03-01

We study the behavior of the modular class of an orientable Poisson manifold and formulate some unimodularity criteria in the semilocal context, around a (singular) symplectic leaf. Our results generalize some known unimodularity criteria for regular Poisson manifolds related to the notion of the Reeb class. In particular, we show that the unimodularity of the transverse Poisson structure of the leaf is a necessary condition for the semilocal unimodular property. Our main tool is an explicit formula for a bigraded decomposition of modular vector fields of a coupling Poisson structure on a foliated manifold. Moreover, we also exploit the notion of the modular class of a Poisson foliation and its relationship with the Reeb class.

Late Paleozoic onset of subduction and exhumation at the western margin of Gondwana (Chilenia Terrane): Counterclockwise P-T paths and timing of metamorphism of deep-seated garnet-mica schist and amphibolite of Punta Sirena, Coastal Accretionary Complex, central Chile (34° S)

Science.gov (United States)

Hyppolito, T.; García-Casco, A.; Juliani, C.; Meira, V. T.; Hall, C.

2014-10-01

In this study, the Paleozoic albite-epidote-amphibolite occurring as meter-sized intercalations within garnet-mica schist at Punta Sirena beach (Pichilemu region, central Chile) is characterized for the first time. These rocks constitute an unusual exposure of subduction-related rocks within the Paleozoic Coastal Accretionary Complex of central Chile. Whereas high pressure (HP) greenschist and cofacial metasediments are the predominant rocks forming the regional metamorphic basement, the garnet-mica schist and amphibolite yield higher P-T conditions (albite-epidote amphibolite facies) and an older metamorphic age. Combining detailed mineral chemistry and textural information, P-T calculations and Ar-Ar ages, including previously published material from the Paleozoic Accretionary Complex of central Chile, we show that the garnet-mica schist and associated amphibolite (locally retrograded to greenschist) are vestiges of the earliest subducted material now forming exotic bodies within the younger HP units of the paleo-accretionary wedge. These rocks are interpreted as having been formed during the onset of subduction at the southwestern margin of Gondwana. However, we show that the garnet-mica schist formed at a slightly greater depth (ca. 40 km) than the amphibolite (ca. 30 km) along the same hot-subduction gradient developed during the onset of subduction. Both lithotypes reached their peak-P conditions at ca. 335-330 Ma and underwent near-isobaric cooling followed by cooling and decompression (i.e., counterclockwise P-T paths). The forced return flow of the garnet-mica schist from the subduction channel started at ca. 320 Ma and triggered the exhumation of fragments of shallower accreted oceanic crust (amphibolite). Cores of phengite (garnet-mica schist) and amphibole (amphibolite) grains have similar chemical compositions in both the S1 and S2 domains, indicating rotation of these grains during the transposition of the burial-related (prograde peak-T) foliation S1

AMS studies in Portuguese variscan granites

Science.gov (United States)

Sant'Ovaia, Helena; Martins, Helena; Noronha, Fernando

2014-05-01

A large volume of Variscan granitic rocks outcrop in Central Iberian Zone which are well documented concerning geological mapping, petrography and geochemistry but whose magnetic characteristics and fabric remain unknown. In this study we summarize the available AMS data from approximately 644 sampling stations (5152 samples) on different massifs of Variscan Portuguese granites. Despite their different geological, petrographic and geochemical characteristics, magnetic susceptibility (K) values obtained for the majority of the studied granites range from 15 to 300 × 10-6 SI. The dominant paramagnetic behaviour of the granite bodies reflects the presence of ilmenite as the main iron oxide. This feature indicates the reduced conditions involved in the granite melt formation during the Variscan orogeny. The two-mica granites show K values ranging between 15 to 70 × 10-6 SI which are lower than values displayed by the biotite-rich facies scattered within the interval of 70 and 300 × 10-6 SI. The magnetite-bearing granites are scarce but represented in Lavadores, Gerês and Manteigas. Even so, only the Lavadores body could be considered as a true magnetite-type granite (K >3.0 × 10-3 SI) in face of its K, comprised between 1550 and 19303 × 10-6 SI. Magnetic anisotropy can be used as a "marker" for the deformation experienced by granite mushes during their crustal emplacement and further cooling. Magnetic anisotropy can thus be correlated with the finite deformation of a rock, as record by mineral fabrics. Post-tectonic granites, such as those from Vila Pouca de Aguiar, Pedras Salgadas, Caria, Vila da Ponte, Chaves and Lamas de Olo, have a magnetic anisotropy <2.5% which corresponds to a deformation hardly visible to the naked eye. Nevertheless, at microscopic scale, these granites display almost ubiquitous magmatic to submagmatic microstructures (rare wavy extinction in quartz, erratic subgrain boundaries in quartz and, eventually, folded or kinked biotites). For

Petrographic and geochemical comparisons between the lower crystalline basement-derived section and the granite megablock and amphibolite megablock of the Eyreville B core, Chesapeake Bay impact structure, USA

Science.gov (United States)

Townsend, G.N.; Gibson, R.L.; Horton, J. Wright; Reimold, W.U.; Schmitt, R.T.; Bartosova, K.

2009-01-01

The Eyreville B core from the Chesapeake Bay impact structure, Virginia, USA, contains a lower basement-derived section (1551.19 m to 1766.32 m deep) and two megablocks of dominantly (1) amphibolite (1376.38 m to 1389.35 m deep) and (2) granite (1095.74 m to 1371.11 m deep), which are separated by an impactite succession. Metasedimentary rocks (muscovite-quartz-plagioclase-biotite-graphite ?? fibrolite ?? garnet ?? tourmaline ?? pyrite ?? rutile ?? pyrrhotite mica schist, hornblende-plagioclase-epidote-biotite- K-feldspar-quartz-titanite-calcite amphibolite, and vesuvianite-plagioclase- quartz-epidote calc-silicate rock) are dominant in the upper part of the lower basement-derived section, and they are intruded by pegmatitic to coarse-grained granite (K-feldspar-plagioclase-quartz-muscovite ?? biotite ?? garnet) that increases in volume proportion downward. The granite megablock contains both gneissic and weakly or nonfoliated biotite granite varieties (K-feldspar-quartz-plagioclase-biotite ?? muscovite ?? pyrite), with small schist xenoliths consisting of biotite-plagioclase-quartz ?? epidote ?? amphibole. The lower basement-derived section and both megablocks exhibit similar middleto upper-amphibolite-facies metamorphic grades that suggest they might represent parts of a single terrane. However, the mica schists in the lower basement-derived sequence and in the megablock xenoliths show differences in both mineralogy and whole-rock chemistry that suggest a more mafi c source for the xenoliths. Similarly, the mineralogy of the amphibolite in the lower basement-derived section and its association with calc-silicate rock suggest a sedimentary protolith, whereas the bulk-rock and mineral chemistry of the megablock amphibolite indicate an igneous protolith. The lower basement-derived granite also shows bulk chemical and mineralogical differences from the megablock gneissic and biotite granites. ?? 2009 The Geological Society of America.

Foliations and the geometry of 3-manifolds

CERN Document Server

Calegari, Danny

2014-01-01

This unique reference, aimed at research topologists, gives an exposition of the 'pseudo-Anosov' theory of foliations of 3-manifolds. This theory generalizes Thurston's theory of surface automorphisms and reveals an intimate connection between dynamics, geometry and topology in 3 dimensions.

Transversal infinitesimal automorphisms on K\\"ahler foliations

OpenAIRE

Jung, Seoung Dal

2011-01-01

Let F be a K\\"ahler foliation on a compact Riemannian manifold M. we study the properties of infinitesimal automorphisms on (M,F), and in particular we concentrate on the transversal conformal field, transversal projective field and transversally holomorphic field

Structural Characterization of the Foliated-Layered Gabbro Transition in Wadi Tayin of the Samail Ophiolite, Oman; Oman Drilling Project Holes GT1A and GT2A

Science.gov (United States)

Deans, J. R.; Crispini, L.; Cheadle, M. J.; Harris, M.; Kelemen, P. B.; Teagle, D. A. H.; Matter, J. M.; Takazawa, E.; Coggon, J. A.

2017-12-01

Oman Drilling Project Holes GT1A and GT2A were drilled into the Wadi Tayin massif, Samail ophiolite and both recovered ca. 400 m of continuous core through a section of the layered gabbros and the foliated-layered gabbro transition. Hole GT1A is cut by a discrete fault system including localized thin ultracataclastic fault zones. Hole GT2A is cut by a wider zone of brittle deformation and incipient brecciation. Here we report the structural history of the gabbros reflecting formation at the ridge to later obduction. Magmatic and high temperature history- 1) Both cores exhibit a pervasive, commonly well-defined magmatic foliation delineated by plagioclase, olivine and in places clinopyroxene. Minor magmatic deformation is present. 2) The dip of the magmatic foliation varies cyclically, gradually changing dip by 30o from gentle to moderate over a 50 m wavelength. 3) Layering is present throughout both cores, is defined by changes in mode and grain size ranging in thickness from 2 cm to 3 m and is commonly sub-parallel to the foliation. 4) There are no high temperature crystal-plastic shear zones in the core. Key observations include: no simple, systematic shallowing of dip with depth across the foliated-layered gabbro transition and layering is continuous across this transition. Cyclic variation of magmatic foliation dip most likely reflects the process of plate separation at the ridge axis. Near-axis faulting- i) On or near-axis structures consist of epidote-amphibole bearing hydraulic breccias and some zones of intense cataclasis with intensely deformed epidote and seams of clay and chlorite accompanied by syntectonic alteration of the wall rock. Early veins are filled with amphibole, chlorite, epidote, and anhydrite. ii) The deformation ranges from brittle-ductile, causing local deflection of the magmatic foliation, to brittle offset of the foliation and core and mantle structures in anhydrite veins. iii) The prevalent sense of shear is normal and slickenfibers

Seismic slip on clay nano-foliation

Science.gov (United States)

Aretusini, S.; Pluemper, O.; Passelègue, F. X.; Spagnuolo, E.; Di Toro, G.

2017-12-01

Deformation processes active at seismic slip rates (ca. 1 m/s) on smectite-rich slipping zones are not well understood, although they likely control the mechanical behaviour of: i) subduction zone faults affected by tsunamigenic earthquakes (e.g. Japan Trench affected by Tohoku-Oki 2011 earthquake), ii) plate-boundary faults (e.g. San Andreas Fault), and iii) landslide decollements (e.g. 1963 Vajont landslide). Here we present a set of rotary experiments performed on water-dampened 2 mm thick clay-rich (70% wt. smectite and 30% wt. opal) gouge layers sheared at slip rates V ranging from 0.01 to 1.3 m/s, for 3 m of displacement under 5 MPa normal stress. Microstructural analyses were conducted on pre- and post-sheared gouges using focused ion beam scanning electron and transmission electron microscopy. All sheared gouges were slip weakening in the first 0.1 m of displacement, with friction coefficient decreasing from 0.3-0.45 to 0.5-0.15. Then, with progressive slip, gouges evolved to slip-strengthening (final friction coefficient of 0.35-0.48) at V ≤0.1 m/s and slip-neutral (final friction of 0.05) at V=1.3 m/s. Despite the large difference in the imposed slip rate and frictional behaviour, the slipping zone always consisted of a nano-foliation defined by sub-micrometric smectite crystals wrapping opal grains. The nano-foliated layer thickness decreased from 1.5 mm at V≤0.1 m/s to 0.15 mm at V=1.3 m/s. The presence of a similar nano-foliation in all the smectite-rich wet gouges suggests the activation of similar deformation processes, dominated by frictional slip on grain boundary and basal planes. The variation of deformed thickness with slip rate shows that dynamic weakening, occurring only at seismic slip rates, is controlled by strain localization.

On deformation of foliations with a center in the projective space

Directory of Open Access Journals (Sweden)

MOVASATI HOSSEIN

2001-01-01

Full Text Available Let be a foliation in the projective space of dimension two with a first integral of the type , where F and G are two polynomials on an affine coordinate, = and g.c.d.(p, q = 1. Let z be a nondegenerate critical point of , which is a center singularity of , and be a deformation of in the space of foliations of degree deg( such that its unique deformed singularity near z persists in being a center. We will prove that the foliation has a first integral of the same type of . Using the arguments of the proof of this result we will give a lower bound for the maximum number of limit cycles of real polynomial differential equations of a fixed degree in the real plane.

The foliation operator in history quantum field theory

International Nuclear Information System (INIS)

Isham, C.J.; Savvidou, K.

2002-01-01

As a preliminary to discussing the quantization of the foliation in a history form of general relativity, we show how the discussion in an earlier work [J. Math. Phys. 43, 3053 (2002)] of a history version of free, scalar quantum field theory can be augmented in such a way as to include the quantization of the unit-length, timelike vector that determines a Lorentzian foliation of Minkowski space-time. We employ a Hilbert bundle construction that is motivated by (i) discussing the role of the external Lorentz group in the existing history quantum field theory [J. Math. Phys. 43, 3053 (2002)] and (ii) considering a specific representation of the extended history algebra obtained from the multi-symplectic representation of scalar field theory

Geochemical and chronological characteristics of Xiangcaoping granite pluton in Miaoershan area

International Nuclear Information System (INIS)

Li Wuwei; Wang Gan; Chen Weifeng; Zhao Kuidong

2010-01-01

Xiangcaoping granite pluton is mainly composed of medium-macro grain porphyritic biotite. The age of signle zircon dated by SHRIMP U-Pb is 211 ± 2 Ma, which suggest s that this pluton was formed during Indosinan. The geochemical characteristics is A > CNK, trace elements spider chart is slightly oblique to the right, enriched in LREE and bears obvious negative Eu anomaly which is similar to that of the S-type granite in South China. High ("8"7Sr/"8"6Sr)_i and low ε_N_d (t) suggest that this pluton was derived from partial melting of middle maturity Precambrian basement rock, which was rich in uranium and had supplied enough U element to the formation of Xiangcaoping granite pluton. (authors)

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.

Raman spectroscopy of garnet-group minerals

Science.gov (United States)

Mingsheng, P.; Mao, Ho-kwang; Dien, L.; Chao, E.C.T.

1994-01-01

The Raman spectra of the natural end members of the garnet-group minerals, which include pyrope, almandine and spessarite of Fe-Al garnet series and grossularite, andradite and uvarovite of Ca-Fe garnet series, have been studied. Measured Raman spectra of these minerals are reasonably and qualitatively assigned to the internal modes, translational and rotatory modes of SiO4 tetrahedra, as well as the translational motion of bivalent cations in the X site. The stretch and rotatory Alg modes for the Fe-Al garnet series show obvious Raman shifts as compared with those for the Ca-Fe garnet series, owing to the cations residing in the X site connected with SiO4 tetrahedra by sharing the two edges. The Raman shifts of all members within either of the series are attributed mainly to the properties of cations in the X site for the Fe-Al garnet series and in the Y site for the Ca-Fe garnet series. ?? 1994 Institute of Geochemistry, Chinese Academy of Sciences.

Constraining the deformation and exhumation history of the Ronda Massif, Southern Spain

Science.gov (United States)

Myall, Jack; Donaldson, Colin

2016-04-01

The Ronda peridotite, southern Spain is comprised of four peridotite units hosted within metasedimentary units of the Betic Cordillera, Western Alps. These four areas of differing mineral facies are termed: the Garnet Mylonite , the Foliated Spinel Peridotite, the Granular Spinel Peridotite and the Foliated Plagioclase Peridotite. Whilst two of these units show a strong NE-SW foliation, the granular unit has no foliation and the Plagioclase facies shows a NW-SE foliation. The massif is separated from the metasedimentary host through a mylonite shear zone to the NW and thrust faults to the SE. The Garnets contain rims of Kelyphite which when combined with the rims of Spinel on the Plagioclase crystals illustrate the complicated exhumation of this massif. The Kelyphite shows the breakdown of garnet back to spinel and pyroxene showing the deeper high pressure high temperature mineral is under shallowing conditions whereas in contrast to this the low pressure low temperature plagioclase crystals have spinel rims showing that they have been moved into deeper conditions. The P-T-t pathway of the massif suggests slow exhumation to allow for partial recrystallisation of not only the garnets and plagioclases but of a 100m band of peridotite between the Foliated Spinel Peridotite and the Granular Spinel Peridotite facies. The tectonic model for the Ronda Peridotite that best describes the field data and subsequent lab work of this study is Mantle Core complex and slab roll back models. These models support mantle uprising during an extensional event that whereby slab roll back of the subducting lithosphere provides uplift into a void and emplacement into the crust. Further extension and final exhumation causes rotation of a mantle wedge into its present day position.

Workshop on Singularities in Geometry, Topology, Foliations and Dynamics

CERN Document Server

Lê, Dung; Oka, Mutsuo; Snoussi, Jawad

2017-01-01

This book features state-of-the-art research on singularities in geometry, topology, foliations and dynamics and provides an overview of the current state of singularity theory in these settings. Singularity theory is at the crossroad of various branches of mathematics and science in general. In recent years there have been remarkable developments, both in the theory itself and in its relations with other areas. The contributions in this volume originate from the “Workshop on Singularities in Geometry, Topology, Foliations and Dynamics”, held in Merida, Mexico, in December 2014, in celebration of José Seade’s 60th Birthday. It is intended for researchers and graduate students interested in singularity theory and its impact on other fields.

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

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)

The solubility and site preference of Fe3+ in Li7−3xFexLa3Zr2O12 garnets

International Nuclear Information System (INIS)

Rettenwander, D.; Geiger, C.A.; Tribus, M.; Tropper, P.; Wagner, R.; Tippelt, G.; Lottermoser, W.; Amthauer, G.

2015-01-01

A series of Fe 3+ -bearing Li 7 La 3 Zr 2 O 12 (LLZO) garnets was synthesized using solid-state synthesis methods. The synthetic products were characterized compositionally using electron microprobe analysis and inductively coupled plasma optical emission spectroscopy (ICP-OES) and structurally using X-ray powder diffraction and 57 Fe Mössbauer spectroscopy. A maximum of about 0.25 Fe 3+ pfu could be incorporated in Li 7−3x Fe x La 3 Zr 2 O 12 garnet solid solutions. At Fe 3+ concentrations lower than about 0.16 pfu, both tetragonal and cubic garnets were obtained in the synthesis experiments. X-ray powder diffraction analysis showed only a garnet phase for syntheses with starting materials having intended Fe 3+ contents lower than 0.52 Fe 3+ pfu. Back-scattered electron images made with an electron microprobe also showed no phase other than garnet for these compositions. The lattice parameter, a 0 , for all solid-solution garnets is similar with a value of a 0 ≈12.98 Å regardless of the amount of Fe 3+ . 57 Fe Mössbauer spectroscopic measurements indicate the presence of poorly- or nano-crystalline FeLaO 3 in syntheses with Fe 3+ contents greater than 0.16 Fe 3+ pfu. The composition of different phase pure Li 7−3x Fe x La 3 Zr 2 O 12 garnets, as determined by electron microprobe (Fe, La, Zr) and ICP-OES (Li) measurements, give Li 6.89 Fe 0.03 La 3.05 Zr 2.01 O 12 , Li 6.66 Fe 0.06 La 3.06 Zr 2.01 O 12 , Li 6.54 Fe 0.12 La 3.01 Zr 1.98 O 12 , and Li 6.19 Fe 0.19 La 3.02 Zr 2.04 O 12 . The 57 Fe Mössbauer spectrum of cubic Li 6.54 Fe 0.12 La 3.01 Zr 1.98 O 12 garnet indicates that most Fe 3+ occurs at the special crystallographic 24d position, which is the standard tetrahedrally coordinated site in garnet. Fe 3+ in smaller amounts occurs at a general 96h site, which is only present for certain Li-oxide garnets, and in Li 6.54 Fe 0.12 La 3.01 Zr 1.98 O 12 this Fe 3+ has a distorted 4-fold coordination. - Graphical abstract: Cubic nominally Li 7 La 3 Zr 2 O

Regional metallogenic essential factor of granite-type uranium deposits in Guangdong province

International Nuclear Information System (INIS)

Pan Yongzheng

1987-12-01

The uranium origin, activation region, red basin, and fault depressed zone constitute the regional metallogenic essential factor of the four united like one granite-type uranium deposits in the post-Caledonian rise area in China. In the development of sub-geosyncline in the Caledonian, the clastic formation with widely deposited carbon, silicon, mud rich bearing organic matter, which drow a great amount of uranium formed the uranium-bearing system in the Sinian-Cambrian period. The magmagranite activation in a large scale in the Indosinian-Yenshanian period caused the continental crust to be suffered strong reformation and the uranium-bearing basement system to be eroded and remelted, and formed the rich uranium granite body. The multiple structure-magmatic movement further made the uranium in the rock body suffered the endogenic, structure, supergene active reformation, and produced mobile uranium concentrated area. Under the dry and hot paleoclimate condition in the Cretaceous-Tertiary period, strong weathering and hot water leaching forced uranium to be concentrated into the 'rock origin activation' type uranium deposits in the fault depressed zone

Uranium rich granite and uranium productive granite in south China

Energy Technology Data Exchange (ETDEWEB)

Mingyue, Feng; Debao, He [CNNC Key Laboratory of Uranium Resource Exploration and Evaluation Technology, Beijing Research Institute of Uranium Geology (China)

2012-07-15

The paper briefly introduces the differences between uranium rich granite and uranium productive granite in the 5 provinces of South China, and discusses their main characteristics in 4 aspects, the uranium productive granite is highly developed in fracture, very strong in alteration, often occurred as two-mica granite and regularly developed with intermediate-basic and acid dikes. The above characteristics distinguish the uranium productive granite from the uranium rich granite. (authors)

Uranium rich granite and uranium productive granite in south China

International Nuclear Information System (INIS)

Feng Mingyue; He Debao

2012-01-01

The paper briefly introduces the differences between uranium rich granite and uranium productive granite in the 5 provinces of South China, and discusses their main characteristics in 4 aspects, the uranium productive granite is highly developed in fracture, very strong in alteration, often occurred as two-mica granite and regularly developed with intermediate-basic and acid dikes. The above characteristics distinguish the uranium productive granite from the uranium rich granite. (authors)

Spacetimes foliated by Killing horizons

International Nuclear Information System (INIS)

Pawlowski, Tomasz; Lewandowski, Jerzy; Jezierski, Jacek

2004-01-01

It seems to be expected that a horizon of a quasi-local type, such as a Killing or an isolated horizon, by analogy with a globally defined event horizon, should be unique in some open neighbourhood in the spacetime, provided the vacuum Einstein or the Einstein-Maxwell equations are satisfied. The aim of our paper is to verify whether that intuition is correct. If one can extend a so-called Kundt metric, in such a way that its null, shear-free surfaces have spherical spacetime sections, the resulting spacetime is foliated by so-called non-expanding horizons. The obstacle is Kundt's constraint induced at the surfaces by the Einstein or the Einstein-Maxwell equations, and the requirement that a solution be globally defined on the sphere. We derived a transformation (reflection) that creates a solution to Kundt's constraint out of data defining an extremal isolated horizon. Using that transformation, we derived a class of exact solutions to the Einstein or Einstein-Maxwell equations of very special properties. Each spacetime we construct is foliated by a family of the Killing horizons. Moreover, it admits another, transversal Killing horizon. The intrinsic and extrinsic geometries of the transversal Killing horizon coincide with the one defined on the event horizon of the extremal Kerr-Newman solution. However, the Killing horizon in our example admits yet another Killing vector tangent to and null at it. The geometries of the leaves are given by the reflection

Zircon and cassiterite U-Pb ages, petrogeochemistry and metallogenesis of Sn deposits in the Sibao area, northern Guangxi: constraints on the neoproterozoic granitic magmatism and related Sn mineralization in the western Jiangnan Orogen, South China

Science.gov (United States)

Chen, Lei; Wang, Zongqi; Yan, Zhen; Gong, Jianghua; Ma, Shouxian

2018-01-01

A number of Sn deposits associated with Neoproterozoic granites are located in the western Jiangnan Orogen of northern Guangxi. The distribution of Sn mineralization is controlled by faults occurring within and around the Neoproterozoic granites. The hydrothermal alteration and mineralization of these Sn deposits exhibit zoning from the granite to the wall rock. The laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb ages of the cassiterite and zircon from ore-bearing granite in the Menggongshan Sn deposit are 829 ± 19 Ma and 822 ± 4 Ma, respectively, indicating that the Sn mineralization and granites formed in the Neoproterozoic and can considered to be products of coeval magmatic and hydrothermal activities. The ore-bearing granite and Neoproterozoic granites in northern Guangxi are high-K, calc-alkaline, peraluminous, S-type granites that are depleted in Nb, Ti, Sr and Ba and highly enriched in Rb, U and Pb. All the granites show steep fractionated light rare earth element (LREE) and flat heavy rare earth element (HREE) patterns, with strongly negative Eu anomalies. The ɛHf(t) values of the ore-bearing granite vary from - 9.0 to - 1.7, with an average value of - 4.1. Additionally, the ore-bearing granite exhibits low oxygen fugacity values. The magmatic source experienced partial melting during their evolution, and the source was dominated by recycled heterogeneous continental crustal materials. Our evidence confirms that the Neoproterozoic granites in northern Guangxi formed in a collisional tectonic setting. The collision between the Cathaysia and Yangtze blocks or between the Sibao arc (Jiangnan arc) and the Yangtze Block caused asthenospheric upwelling, leading to partial melting and recycling of the crust, forming the peraluminous S-type granites in the Neoproterozoic. The Sn mineralization has a close genetic relationship with the Neoproterozoic granite. The highly differentiated, peraluminous, B-enriched, crustally derived

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

Uranium migration and retention during weathering of a granitic waste rock pile

International Nuclear Information System (INIS)

Boekhout, F.; Gérard, M.; Kanzari, A.; Michel, A.; Déjeant, A.; Galoisy, L.; Calas, G.; Descostes, M.

2015-01-01

Highlights: • We investigate the environmental impact of the granitic waste rock piles. • The majority of the waste rocks in the pile is barren- or overburden rock. • The main neo-formed U-bearing phases are (Ca) and (Cu) uranyl phosphates. • Under circum-neutral pH conditions they do not pose an environment threat. - Abstract: This study investigates the post-mining evolution of S-type granitic waste rocks around a former uranium mine, Vieilles Sagnes (Haute Vienne, NW Massif Central, France). This mine was operated between 1957 and 1965 in the La Crouzille former world-class uranium mining district and is representative of intra-granitic vein-type deposits. 50 years after mine closure and the construction and subsequent re-vegetation of the granitic waste rock pile, we evaluate the environmental evolution of the rock pile, including rock alteration, neo-formation of U-bearing phases during weathering, and U migration. Vertical trenches have been excavated through the rock pile down to an underlying paleo-soil, allowing the investigation of the vertical differentiation of the rock pile and its influence on water pathways, weathering processes and U migration and retention. Arenization dominantly drives liberation of U, by dissolution of uraninite inclusions in the most alterable granitic minerals (i.e. K-feldspar and biotite). Retention of U in the matrix at the base of the waste rock pile, and in the underlying paleo-soil most likely occurs by precipitation of (nano-) uranyl phosphates or a combination of co-precipitation and adsorption reactions of U onto Fe (oxy)hydroxides and/or clay minerals. Even though U-migration was observed, U is retained in stable secondary mineral phases, provided the current conditions will not be modified

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

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Stephen Frindt

2002-01-01

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

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

compositions of the Tongbai gneissic granites, while the compositions of the Jigongshan granites were mainly controlled by partial melting. The adakitic signatures of the Jigongshan granites were either inherited from their source or ascribed to more garnet in their residues. The voluminous post-collisional granites might form by the collapse of the thickened Tongbai orogenic root. The normal Tongbai gneissic granites occurred slightly earlier than the Jigongshan adakitic granites in the Tongbai orogen, suggesting that it is not a mandate to sign the tectonic transition from adakitic to normal calc-alkaline granites in post-collisional settings. Therefore, this study provides another example supporting the burst of voluminous post-collisional granites with different compositions as a consequence of the collapse of the thickened orogenic roots of collisional orogens.

Spherical spacelike geometries in static spherically symmetric spacetimes: Generalized Painlevè–Gullstrand coordinates, foliation, and embedding

Energy Technology Data Exchange (ETDEWEB)

Akbar, M.M., E-mail: akbar@utdallas.edu

2017-06-10

It is well known that static spherically symmetric spacetimes can admit foliations by flat spacelike hypersurfaces, which are best described in terms of the Painlevè–Gullstrand coordinates. The uniqueness and existence of such foliations were addressed earlier. In this paper, we prove, purely geometrically, that any possible foliation of a static spherically symmetric spacetime by an arbitrary codimension-one spherical spacelike geometry, up to time translation and rotation, is unique, and we find the algebraic condition under which it exists. This leads us to what can be considered as the most natural generalization of the Painlevè–Gullstrand coordinate system for static spherically symmetric metrics, which, in turn, makes it easy to derive generic conclusions on foliation and to study specific cases as well as to easily reproduce previously obtained generalizations as special cases. In particular, we note that the existence of foliation by flat hypersurfaces guarantees the existence of foliation by hypersurfaces whose Ricci curvature tensor is everywhere non-positive (constant negative curvature is a special case). The study of uniqueness and the existence concurrently solves the question of embeddability of a spherical spacelike geometry in one-dimensional higher static spherically symmetric spacetimes, and this produces known and new results geometrically, without having to go through the momentum and Hamiltonian constraints.

Regularization of discontinuous foliations: Blowing up and sliding conditions via Fenichel theory

Science.gov (United States)

Panazzolo, Daniel; da Silva, Paulo R.

2017-12-01

We study the regularization of an oriented 1-foliation F on M ∖ Σ where M is a smooth manifold and Σ ⊂ M is a closed subset, which can be interpreted as the discontinuity locus of F. In the spirit of Filippov's work, we define a sliding and sewing dynamics on the discontinuity locus Σ as some sort of limit of the dynamics of a nearby smooth 1-foliation and obtain conditions to identify whether a point belongs to the sliding or sewing regions.

Precipitation of Oriented Rutile and Ilmenite Needles in Garnet, Northeastern Connecticut, USA: Evidence for Extreme Metamorphic Conditions?

Science.gov (United States)

Ague, J. J.; Eckert, J. O.

2011-12-01

We report the discovery of oriented needles of rutile and, less commonly, ilmenite in the cores of garnets from northeastern CT, USA. The rocks preserve granulite facies mineral assemblages, form part of the Merrimack Synclinorium, and underwent metamorphism and deformation during the Acadian orogeny. The needles appear identical to those reported from a number of extreme P-T environments worldwide, including UHP metamorphic rocks, high-P granulites, and garnet peridotites. The needles are predominantly oriented along directions in garnet. The long axes of the rutile needles commonly do not go extinct parallel to the cross hairs under cross-polarized light (e.g., Griffin et al., 1971). This anomalous extinction indicates that the needles do not preserve a specific crystallographic relationship with their garnet hosts (e.g., Hwang et al., 2007). The needles range from a few hundred nm to a few um in diameter, and can be mm-scale in length. Micrometer-scale plates of rutile, srilankite and crichtonite have also been observed in some garnets together with the Fe-Ti oxide needles. Several origins for the needles have been proposed in the literature; we investigate the hypothesis that they precipitated in situ from originally Ti-rich garnet. Chemical profiles across garnets indicate that some retain Ti zoning, with elevated-Ti concentrations in the cores dropping to low values in the rims. For these zoned garnets, high-resolution, 2-D chemical mapping using the JEOL JXA-8530F field emission gun electron microprobe at Yale University reveals that the needles are surrounded by well-defined Ti-depletion halos. Chemical profiles also document strong depletions of Cr (which is present in both rutile and ilmenite) directly adjacent to needles. The observed Ti-depletions demonstrate that the needles precipitated from Ti-bearing garnet, probably during cooling and/or decompression associated with exhumation. The rutile precipitates must be largely incoherent with respect to the

Garnets from the Camafuca-Camazambo kimberlite (Angola

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Correia Eugénio A.

2006-01-01

Full Text Available This work presents a geochemical study of a set of garnets, selected by their colors, from the Camafuca-Camazambo kimberlite, located on northeast Angola. Mantle-derived garnets were classified according to the scheme proposed by Grütter et al. (2004 and belong to the G1, G4, G9 and G10 groups. Both sub-calcic (G10 and Ca-saturated (G9 garnets, typical, respectively, of harzburgites and lherzolites, were identified. The solubility limit of knorringite molecule in G10D garnets suggests they have crystallized at a minimum pressure of about 40 to 45 kbar (4-4.5 GPa. The occurrence of diamond stability field garnets (G10D is a clear indicator of the potential of this kimberlite for diamond. The chemistry of the garnets suggests that the source for the kimberlite was a lherzolite that has suffered a partial melting that formed basaltic magma, leaving a harzburgite as a residue.

Hydrothermally-induced changes in mineralogy and magnetic properties of oxidized A-type granites

Science.gov (United States)

Nédélec, Anne; Trindade, Ricardo; Peschler, Anne; Archanjo, Carlos; Macouin, Mélina; Poitrasson, Franck; Bouchez, Jean-Luc

2015-01-01

The changes in magnetic mineralogy due to the hydrothermal alteration of A-type granitic rocks have been thoroughly investigated in samples from the granite of Tana (Corsica, France), and compared with other A-type granites: Meruoca (NE Brazil), Bushveld (South Africa), Mount Scott (Wichita Mountains, Oklahoma, USA) and the stratoid hypersolvus granites of Madagascar. The altered red-colored samples and their non-altered equivalents were magnetically characterized by means of magnetic susceptibility measurements, hysteresis loops, remanent coercivity spectra, and Lowrie test. It is shown that hydrothermalization in magnetite-bearing granites is related to the formation of fine-grained magnetite and hematite, and to coeval depletion in the content of primary low-coercive coarse-grained magnetite. These mineralogical changes give typical rock magnetic signatures, namely lower susceptibility magnitudes and anisotropy degrees, prolate AMS (anisotropy of magnetic susceptibility) fabrics and increased coercivities. Optical microscopy and SEM (scanning electronic microscopy) images suggest that the orientation of the secondary magnetic minerals is related to fluid-pathways and micro-fractures formed during the hydrothermal event and therefore may be unrelated to magma emplacement and crystallization fabrics. Changes in magnetic mineralogy and grain-size distribution have also to be considered for any paleomagnetic and iron isotope studies in granites.

An overview of the regional, geological and structural setting of the uraniferous granites in the Damara Orogen, Namibia

International Nuclear Information System (INIS)

Brynard, H.J.; Andreoli, M.A.G.

1988-01-01

Uranium-bearing granites, comprising both potentially economic deposits and source rocks for uranium deposits in duricrustal and sedimentary sequences, occur in the Damara Orogen of Namibia. The economically important uraniferous granites are mainly confined to the Central Zone, delimited by the Omaruru and Okahandja lineaments, which demarcate the boundary between two markedly different magnetic and hence depositional and/or tectonic regimes. Various models to explain the origin and evolution of the uranium-enriched granites have been proposed to date, none of which are found to explain the observed petrological phenomena adequately. The paper critically reviews the existing literature on the origin of the granites and some criteria for exploration are discussed. (author). 24 refs, 6 figs, 2 tabs

Fingerprinting the Hydrothermal Fluid Characteristics from LA-ICP-MS Trace Element Geochemistry of Garnet in the Yongping Cu Deposit, SE China

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Yu Zhang

2017-10-01

Full Text Available The large Yongping Cu deposit is situated in the eastern Qin-Hang Metallogenic Belt, Southeast China and on the southern side of the Yangtze—Cathaysia suture zone, and is characterized by large stratiform orebodies. Garnet represents the main non-metallic mineral at Yongping, and shows variations in color from dark red to green to light brown with distance from the Shizitou porphyritic biotite granite stock. An in situ elemental analysis using EPMA and LA-ICP-MS and fluid inclusions microthermometric measurement on the Yongping garnet were conducted to constrain the hydrothermal and physicochemical mineralization conditions and the ore origin. The Yongping garnet ranges from nearly pure to impure andradite, is characterized by low concentrations of MnO (0.11–0.71 wt % with a wide range of Y/Ho (2.1–494.9 and does not exhibit any melting inclusions or fluid-melt inclusions, indicating that they are likely to be resulted from hydrothermal replacements. The Yongping garnet is rich in LREEs, Cs, Th, U and Pb; relatively depleted in HREEs, Rb, Sr and Ba; but exhibits distinct Eu anomalies (δEu of the dark red, green and light brown garnet range 2.12–20.54, 0.74–1.70 and 0.52–0.85, respectively with the homogenization temperatures and salinities of the fluid inclusions principally ranging from 387–477 °C and 7.8–16.0 wt % NaCl equivalent, respectively. The distinct trace elements and microthermometric characteristics reveal that the garnet was formed in a physicochemical conditions of medium-high temperature, 44–64 MPa pressures, mildly acidic pH levels, and unstable oxygen fugacity, and indicate that they were primarily formed by infiltration metasomatism, quite fitting with the scenario that the preferential entrance of magmatic-hydrothermal fluids derived from the Shizitou stock into the relatively low-pressure fracture zones between the limestone and quartz sandstone in the Yejiawan Formation, and further led to the formation

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

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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

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.)

Chemical and isotopic studies of granitic Archean rocks, Owl Creek Mountains, Wyoming: Geochronology of an Archean granite, Owl Creek Mountains, Wyoming

International Nuclear Information System (INIS)

Hedge, C.E.; Simmons, K.R.; Stuckless, J.S.

1986-01-01

Rubidium-strontium analyses of whole-rock samples of an Archean granite from the Owl Creek Mountains, Wyo., indicate an intrusive age of 2640 ± 125 Ma. Muscovite-bearing samples give results suggesting that these samples were altered about 2300 Ma. This event may have caused extensive strontium loss from the rocks as potassium feldspar was altered to muscovite. Alteration was highly localized in nature as evidence by unaffected rubidium-strontium mineral ages in the Owl Creek Mountains area. Furthermore, the event probably involved a small volume of fluid relative to the volume of rock because whole-rock δ 18 O values of altered rocks are not distinct from those of unaltered rocks. In contrast to the rubidium-strontium whole-rock system, zircons from the granite have been so severely affected by the alteration event, and possibly by a late-Precambrian uplift event, that the zircon system yields little usable age information. The average initial 87 Sr/ 86 Sr (0.7033 ± 0.0042) calculated from the isochron intercept varies significantly. Calculated initial 87 Sr/ 86 Sr ratios for nine apparently unaltered samples yield a range of 0.7025 to 0.7047. These calculated initial ratios correlate positively with whole-rock δ 18 O values; and, therefore, the granite was probably derived from an isotopically heterogeneous source. The highest initial 87 Sr/ 86 Sr ratio is lower than the lowest reported for the metamorphic rocks intruded by the granite as it would have existed at 2640 Ma. Thus, the metamorphic sequence, at its current level of exposure, can represent no more than a part of the protolith for the granite

Automorphisms of foliations defined by complex linear vectorfields

International Nuclear Information System (INIS)

Shahshahani, S.

1989-06-01

We study biholomorphisms of C n that preserve the foliation associated with a complex linear vectorfield. It is shown that for a large class the only such biholomorphisms are linear conjugacies of the flow. Nonlinear biholomorphisms emerge in the presence of resonance among the eigenvalues of the system. A complete classification is given in dimension two. (author). 8 refs

A Geothermochronologic Investigation of the Coyote Mountains Metamorphic Core Complex (AZ)

Science.gov (United States)

Borel, M.; Gottardi, R.; Casale, G.

2017-12-01

The Coyote Mountains metamorphic core complex (CM-MCC) makes up the northern end of the Baboquivari Mountain complex, which is composed of Mesozoic rocks, Tertiary granites, pegmatites, and metasediments. The CM-MCC expose the Pan Tak granite, a 58 Ma intrusive muscovite-biotite-garnet peraluminous granite. The Pan Tak and other intrusions within the Baboquivari Mountains have been interpreted as anatectic melts representing the culmination of a Laramide crustal shortening orogenic event started in the Late Cretaceous ( 70 Ma). Evidence of this magmatic episode includes polysynthetic twinning in plagioclase, myrmekitic texture in alkali feldspars, and garnet, mica and feldspar assemblages. The magmatic fabric is overprinted by a Tertiary tectonic fabric, associated with the exhumation of the CM-MCC along the Ajo road décollement and associated shear zone. In the shear zone, the Pan Tak mylonite display N-dipping foliation defined by gneissic layering and aligned muscovite, and N-trending mineral stretching lineation. Various shear sense indicators are all consistent with a top-to the-N shear sense. Preliminary argon geochronology results suggest that the shear zone was exhumed 29 Ma ago, an age similar to the onset of detachment faulting in other nearby MCCs (Catalina, Rincon, Pinaleño). In the Pan Tak mylonite, quartz grains display regime 2 to 3 microstructures and shows extensive recrystallization by subgrain rotation and grain boundary migration. The recrystallized grain size ranges between 20 and 50 µm in all samples. Quartz crystallographic preferred orientation measured using electron backscatter diffraction (EBSD) shows that recrystallization was accommodated by dominant prism and minor rhomb slip, suggesting deformation temperature ranging from 450°C to 550°C. These preliminary results constrain the timing of uplift and exhumation, and thermomechanical evolution of the CM-MCC, and improve our understanding of recycling of the continental crust in

Experimental Constraints on the Partitioning and Valence of V and Cr in Garnet and Coexisting Glass

Science.gov (United States)

Righter, K.; Sutton, S.; Berthet, S.; Newville, M.

2008-01-01

A series of experiments with garnet and coexisting melt have been carried out across a range of oxygen fugacities (near hematite-magnetite (HM) to below the iron-wustite (IW) buffers) at 1.7 GPa to study the partitioning and valence of Cr and V in both phases. Experiments were carried out in a non end loaded piston cylinder apparatus, and the run products were analyzed with electron microprobe and xray absorption near edge structure (XANES) analysis at beamline 13-ID at the Advanced Photon Source of Argonne National Lab. The valence of vanadium and chromium were determined using the position and intensity of the Ka pre-edge peaks, calibrated on a series of Cr and Vbearing standard glasses. This technique has been applied to V and Cr in glasses and V in spinels previously, and in these isotropic phases there are no orientational effects on the XANES spectra (Righter et al., 2006, Amer. Mineral. 91, 1643-1656). We also now demonstrate this to be true for V and Cr in garnet. Also, previous work has shown that V has a higher valence in the glass (or melt) than in the coexisting spinel. This is also true for V in garnet-glass pairs in this study. Vanadium valence in garnets varies from 2.7 below the IW buffer to 3.7 near HM, and for coexisting glass it varies from 3.2 to 4.3. Vanadium valence measured in some natural garnets from mantle localities indicates V in the more reduced range at 2.5. Comparisons will be made between fO2 estimated from V valence and other methods for garnet-bearing mantle samples. In contrast, Cr valence measured in garnet and coexisting glass for all experimental and natural samples is 2.9- 3.0, suggesting that the valence of Cr does not vary within either phase across a large fO2 range. These results demonstrate that while V varies from 2+ to 3+ to 4+ in garnet-melt systems, Cr does not, and this will ultimately affect the partitioning behavior of these two elements in natural systems. Garnet/melt D(Cr) are between 12 and 17 across this range

On the nature and origin of garnet in highly-refractory Archean lithosphere: implications for continent stabilisation

Science.gov (United States)

Gibson, Sally

2014-05-01

because of their unusual pre-metasomatic compositions. We believe they are rare because the low concentrations of trace elements make them readily susceptible to geochemical overprinting. This highly-refractory low-density peridotite may be common in the 'shallow' SCLM but is not normally brought to the surface by ascending melts, which tend to metasomatise and preferentially sample their source regions. The modal abundance of garnet formed by isochemical exsolution from orthopyroxene in sub-cratonic mantle is unclear but may prove to be an important consideration in isopycnic models related to the long-term stability of the Earth's continental lithosphere, e.g. Lee et al. (2011). Gibson, S. A., McMahon, S. C., Day, J. A. & Dawson, J. B. (2013). Highly Refractory Lithospheric Mantle beneath the Tanzanian Craton: Evidence from Lashaine Pre-metasomatic Garnet-bearing Peridotites. J. Petrol. doi:10.1093/petrology/egt020 Stachel, T., Aulbach, A., Brey, G.P., Harris, J.W., Leost, I., Tappert, R. & Viljoen, K.S. (2004). The trace element composition of silicate inclusions in diamonds: a review. Lithos 77, 1-19 Lee, C.-T., Luffi, P. & Chin, E. J. (2011). Building and Destroying Continental Mantle. Annu. Rev. Earth Planet. Sci. 39, 59-90

The regional geological and structural setting of the uraniferous granitic provinces of Southern Africa

International Nuclear Information System (INIS)

Jacob, R.E.; Corner, B.; Brynard, H.J.

1986-01-01

Uranium-bearing granites, comprising both potentially economic deposits and source rocks for uranium deposits is duricrustal and sedimentary sequences, are confined chiefly to the mobile belts of Southern Africa and to the Cape granites emplaced during late Precambrian times. The direct uranium potential of the mobile belts, i.e. the Damara, Namaqua-Natal and Limpopo belts, decreases with an increase in the age of associated ensialic diastrophism. This review paper is thus mainly confined to the Damara Belt, although a brief discussion of the potential of the Namaqua Belt is presented. Aspects of the Damara Belt that are discussed in detail, with particular reference to the occurrence of uraniferous granite, include regional tectonic setting, stratigraphy, structure, metamorphism and the patterns and origin of the uranium mineralization. Initial concentrations of uranium in basement and Nosib rocks have led, through ultrametamorphism and fractionation, to uraniferous granites of both economic and sub-economic grade. These granites, in turn, have acted as source of secondary mineralization in overlying superficial calcareous and gypsiferous deposits. The Damara Belt thus provides a good example of multicyclic processes of ore formation. With regard to the uraniferous granites of Namaqualand it is concluded that the porphyroblastic gneisses and late-intrusive Concordia granites, although not of direct economic interest, represent major sources of uranium for secondary superficial deposits. Smaller bodies of late-phase differentiates associated with the Concordia granitic gneiss may themselves, however, represent potentially economically viable deposits

Abnormalities of cerebellar foliation and fissuration: classification, neurogenetics and clinicoradiological correlations

Energy Technology Data Exchange (ETDEWEB)

Demaerel, P. [University Hospital, Department of Radiology, Herestraat 49, 3000 Leuven (Belgium)

2002-08-01

Several genes have been found to influence the different cells involved in the processes of foliation and fissuration in the mouse and rat cerebellum. In the light of these new concepts and on the basis of the imaging findings in 42 patients, a classification is proposed for abnormalities of foliation and fissuration. On the basis of recent genetic and experimental evidence on mechanisms which control the origin of the cerebellum, it is suggested that abnormalities of foliation and fissuration form a single group, with a spectrum of severity. Some patients have only abnormal fissuration of the anterior lobe (type 1a) and others additional dysplasia of the anterior and part of the posterior lobe (type 1b). Extension of abnormalities into the hemispheres is often seen in the latter group. A second group has vermian and hemisphere abnormalities (type 2). In addition to the malformation of the anterior lobe of the vermis, three different hemispheric lesions can be seen in this group: cortical dysgenesis, hypertrophy of the cerebellar cortex, and malorientation of the folia. The mild abnormalities (type 1a) can be considered an incidental observation without clinical relevance. The moderate and severe cerebellar anomalies (type 1b and 2) are always associated with cerebellar symptoms and/or signs. (orig.)

Abnormalities of cerebellar foliation and fissuration: classification, neurogenetics and clinicoradiological correlations

International Nuclear Information System (INIS)

Demaerel, P.

2002-01-01

Several genes have been found to influence the different cells involved in the processes of foliation and fissuration in the mouse and rat cerebellum. In the light of these new concepts and on the basis of the imaging findings in 42 patients, a classification is proposed for abnormalities of foliation and fissuration. On the basis of recent genetic and experimental evidence on mechanisms which control the origin of the cerebellum, it is suggested that abnormalities of foliation and fissuration form a single group, with a spectrum of severity. Some patients have only abnormal fissuration of the anterior lobe (type 1a) and others additional dysplasia of the anterior and part of the posterior lobe (type 1b). Extension of abnormalities into the hemispheres is often seen in the latter group. A second group has vermian and hemisphere abnormalities (type 2). In addition to the malformation of the anterior lobe of the vermis, three different hemispheric lesions can be seen in this group: cortical dysgenesis, hypertrophy of the cerebellar cortex, and malorientation of the folia. The mild abnormalities (type 1a) can be considered an incidental observation without clinical relevance. The moderate and severe cerebellar anomalies (type 1b and 2) are always associated with cerebellar symptoms and/or signs. (orig.)

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

Magnetic susceptibility of Variscan granite-types of the Spanish Central System and the redox state of magma

Energy Technology Data Exchange (ETDEWEB)

Villaseca, C.; Ruiz-Martínez, V.C.; Pérez-Soba, C.

2017-07-01

Magnetic susceptibility (MS) has been measured in Variscan granites from central Spain. They yield values in the order of 15 to 180μSI units for S- and I-type granites, indicating that both types belong to the ilmenite series. Only samples from magnetite-bearing leucogranites from the I-type La Pedriza massif show high MS values, in the order of 500-1400μSI, reflecting the presence of this ferromagnetic mineral. Mineral chemistry of magmatic Fe-rich minerals (mainly biotite) suggests similar oxidation values for both granite types. MS values change in highly fractionated granites accordingly either with the presence of rare new Fe-oxide phases (some I-type leucogranites) or with the marked modal amount decrease of Fe-rich minerals (I- and S-type leucogranites). The redox state in highly fractionated granite melts is mostly controlled by magmatic processes that modify redox conditions inherited from the source region. Thus, the occurrence of magnetite or ilmenite in granites is primarily controlled by the oxidation state of the source material but also by the differentiation degree of the granite melt. The presence of magnetite in some Variscan I-type leucogranites might be a consequence of crystal fractionation processes in a more limited mafic mineral assemblage than in S-type granite melts.

Systematic hardness measurements on some rare earth garnet ...

Indian Academy of Sciences (India)

Unknown

Microhardness measurements were undertaken on twelve rare earth garnet crystals. In yttrium aluminium garnet and gadolinium ... syan (1997) has quoted a single value for Gd3Sc2Ga3O12. In the present study measurements have ... small and within the limits of experimental error. There- fore, where pure garnet crystals ...

First report of garnet corundum rocks from southern India: Implications for prograde high-pressure (eclogite-facies?) metamorphism

Science.gov (United States)

Shimpo, Makoto; Tsunogae, Toshiaki; Santosh, M.

2006-02-01

We report here for the first time the occurrence of garnet and corundum in Mg-Al-rich rocks at Sevitturangampatti (Namakkal district) in the Palghat-Cauvery Shear Zone System (PCSS), southern India. The rocks contain several rare mineral assemblages such as garnet-corundum-sillimanite-cordierite-sapphirine-spinel-Mg-rich staurolite, garnet-corundum-sodic gedrite-cordierite-sillimanite/kyanite, garnet-Mg-rich staurolite-sillimanite/kyanite, sodic gedrite-Mg-rich staurolite-corundum-sapphirine, biotite-corundum-sapphirine and sodic gedrite-sapphirine-spinel-cordierite. Both garnet and corundum in these rocks occur as coarse-grained (1 mm to 10 cm) porphyroblasts in the matrix of sillimanite, cordierite and gedrite. Kyanite is common as inclusions in garnet, but matrix aluminosilicates are mainly sillimanite. The presence of rare garnet + corundum, which has so far been reported from kimberlite xenoliths, aluminous eclogites and ultrahigh-pressure metamorphic rocks as well as in high-pressure experiments, suggests that the assemblage is an indicator of an unusually high-pressure event, which has not been recorded in previous studies from southern India. Phase analysis of quartz-absent MAS system also suggests high-pressure stability of the assemblage. The inference of high pressure metamorphism is also supported by the presence of Mg-rich [Mg/(Fe + Mg) = 0.51] staurolite, which has been reported from high-pressure rocks, included from cores of coarse-grained garnet and gedrite. Porphyroblastic occurrence of garnet + corundum as well as staurolite and kyanite inclusions suggests that the area underwent prograde high-pressure metamorphism, probably in the eclogite field. The rocks subsequently underwent continuous heating at 940 to 990 °C, suggesting ultrahigh-temperature (UHT) metamorphism along a clockwise trajectory. Sapphirine + cordierite and spinel + cordierite symplectites between garnet and sillimanite suggest near isothermal decompression after the peak event

Lu-Hf geochronology on cm-sized garnets using microsampling: New constraints on garnet growth rates and duration of metamorphism during continental collision (Menderes Massif, Turkey)

Science.gov (United States)

Schmidt, Alexander; Pourteau, Amaury; Candan, Osman; Oberhänsli, Roland

2015-12-01

This study shows Lu-Hf geochronology of zoned garnet crystals contained in mica schists from the southern Menderes Massif, Turkey. Selected samples are four 3-5 cm large garnet megacrysts of which several consecutive garnet shells have been sampled with a micro-saw and analyzed for dating. The results are used to extract growth rates of garnet, and also to improve the time constraint for Alpine-aged overprint of the Pan-African basement in the Menderes Massif. Lu-Hf ages of the sampled garnet shells are determined by two-point garnet-only isochrons using the garnets' Lu-depleted rim compositions. This yields a consistent decrease of age information from core to rim segments of individual garnet crystals and the calculated isochron ages propose a time frame of growth between 42.6 ± 1.9 and 34.8 ± 3.1 Ma. Major element profiles in the investigated garnets characterize zoning patterns indicative of prograde conditions: Rayleigh fractionated bell-shaped Mn and decreasing Fe/(Fe + Mg) are recorded by the garnets' core to rim compositions. Therefore the obtained Lu-Hf ages record timing of early prograde growth for the cores of the garnets. Two of the large garnet crystals also yield isochron ages of 58.83 ± 0.69 and 50.16 ± 0.84 Ma in their innermost cores, which appear to record an early nucleation event. This view, however, is not in concordance with the observed major element profiles of these garnets, and therefore is interpreted with caution. Termination of the garnet growth period is determined through the calculation of radial growth rates based on the size of the garnets and the Lu-Hf ages obtained for consecutive shells. Extrapolation of these rates potentially constrains the total duration for garnet growth terminating at 31 ± 6 Ma. Comparison of the growth rates calculated for individual crystals shows a variety of slow and fast growing garnets, and similar results have been previously obtained with the Rb-Sr and Sm-Nd isotope systems. The new data

Lesser Himalayan sequences in Eastern Himalaya and their deformation: Implications for Paleoproterozoic tectonic activity along the northern margin of India

Directory of Open Access Journals (Sweden)

Dilip Saha

2013-05-01

Full Text Available Substantial part of the northern margin of Indian plate is subducted beneath the Eurasian plate during the Caenozoic Himalayan orogeny, obscuring older tectonic events in the Lesser Himalaya known to host Proterozoic sedimentary successions and granitic bodies. Tectonostratigraphic units of the Proterozoic Lesser Himalayan sequence (LHS of Eastern Himalaya, namely the Daling Group in Sikkim and the Bomdila Group in Arunachal Pradesh, provide clues to the nature and extent of Proterozoic passive margin sedimentation, their involvement in pre-Himalayan orogeny and implications for supercontinent reconstruction. The Daling Group, consisting of flaggy quartzite, meta-greywacke and metapelite with minor mafic dyke and sill, and the overlying Buxa Formation with stromatolitic carbonate-quartzite-slate, represent shallow marine, passive margin platformal association. Similar lithostratigraphy and broad depositional framework, and available geochronological data from intrusive granites in Eastern Himalaya indicate strikewise continuity of a shallow marine Paleoproterozoic platformal sequence up to Arunachal Pradesh through Bhutan. Multiple fold sets and tectonic foliations in LHS formed during partial or complete closure of the sea/ocean along the northern margin of Paleoproterozoic India. Such deformation fabrics are absent in the upper Palaeozoic–Mesozoic Gondwana formations in the Lesser Himalaya of Darjeeling-Sikkim indicating influence of older orogeny. Kinematic analysis based on microstructure, and garnet composition suggest Paleoproterozoic deformation and metamorphism of LHS to be distinct from those associated with the foreland propagating thrust systems of the Caenozoic Himalayan collisional belt. Two possibilities are argued here: (1 the low greenschist facies domain in the LHS enveloped the amphibolite to granulite facies domains, which were later tectonically severed; (2 the older deformation and metamorphism relate to a Pacific type

Parameter prediction for microwave garnets

International Nuclear Information System (INIS)

Ramer, R.

1996-01-01

Full text: Linearity of the microwave parameters (resonance linewidth ΔH and effective linewidth ΔH eff ) is demonstrated and their use in the Computer-aided design (CAD)/Computer-aided manufacturing (CAM) of new microwave garnets is proposed. Such an approach would combine a numerical database of microwave data and several computational programs. The model is an applied formulation of the analysis of a wide range of microwave garnets

Industrial garnet

Science.gov (United States)

Olson, D.W.

2013-01-01

Garnet has been used as a gemstone since the Bronze Age. However, garnet’s angular fractures, relatively high hardness and specific gravity, chemical inertness and nontoxicity make it ideal for many industrial applications. It is also free of crystalline silica and can be recycled.

Geochronology, petrogenesis and tectonic settings of pre- and syn-ore granites from the W-Mo deposits (East Kounrad, Zhanet and Akshatau), Central Kazakhstan

Science.gov (United States)

Li, GuangMing; Cao, MingJian; Qin, KeZhang; Evans, Noreen J.; Hollings, Pete; Seitmuratova, Eleonora Yusupovha

2016-05-01

There is significant debate regarding the mineralization ages of the East Kounrad, Zhanet and Akshatau W-Mo deposits of Central Kazakhstan, and the petrogenesis and tectono-magmatic evolution of the granites associated with these deposits. To address these issues, we present molybdenite Re-Os dating, zircon U-Pb dating, whole rock geochemistry as well as Sr-Nd-Pb and zircon O-Hf isotopic analyses on the pre-mineralization and ore-forming granites. U-Pb dating of zircons from pre-mineralization granitic rocks yield Late Carboniferous ages of 320-309 Ma, whereas ore-forming granites have Early Permian ages of 298-285 Ma. Molybdenite Re-Os isotopic data indicate a mineralization age of 296 Ma at East Kounrad, 294 Ma at Akshatau and 285 Ma at Zhanet. The pre-ore and ore-forming granites are high-K calc-alkaline, metaluminous to slightly peraluminous I-type granites. The pre-mineralization granites are relatively unfractionated, whereas the ore-forming granites are highly fractionated. The fractionating mineral phases are probably K-feldspar, apatite, Ti-bearing phases and minor plagioclase. The pre-mineralization and ore-forming rocks are characterized by similar Sr-Nd-Pb-Hf-O isotopic compositions ((87Sr/86Sr)i = 0.70308-0.70501, εNd (t) = - 0.5 to + 2.8, 207Pb/204Pb = 15.60-15.82, zircon εHf (t) = + 1.2 to + 15.6 and δ18O = + 4.6 to + 10.3‰), whole rock TDMC (Nd) (840-1120 Ma) and zircon TDMC (Hf) (320-1240 Ma). The isotopic characteristics are consistent with a hybrid magma source caused by 10-30% assimilation of ancient crust by juvenile lower crust. The geochronology and geochemistry of these granites show that the Late Carboniferous pre-mineralization granitic rocks formed during subduction, whereas the Early Permian ore-forming, highly fractionated granite probably underwent significant fractionation with a restite assemblage of K-feldspar, apatite, Ti-bearing phases and minor plagioclase and developed during collision between the Yili and Kazakhstan

Minor elements, HREE and d18O distribution in UHP garnets from the Dora-Maira massif (western Alps)

Science.gov (United States)

Brunet, F.; Chazot, G.; Vielzeuf, D.; Chopin, C.

2003-04-01

The spatial distribution of minor elements, HREE and δ18O in garnet can be used as a probe of the availability and mobility of those elements and isotopes at the time of crystal growth, provided that the initial record was not significantly modified by intracrystalline diffusion and that growth took place under nearly constant pressure and temperature conditions. Garnets from three different Dora-Maira rock-types have been studied, (1) nearly pure pyrope (GT1) from the magnesian coesite-bearing quartzites, (2) almandine/pyrope dominant garnets (GT2) from jadeite-quartzite veins which crosscut the Mg-quartzite body, (3) almandine/grossular dominant garnets (GT3) from the country-rock gneiss, sampled in the vicinity of the quartzites. In GT1, minor elements are mainly Fe, Na and P. Na and P are incorporated according to a Na^+ + P5+ = Me2+ + Si4+ substitution with P_2O_5 contents up to 2000 to 2500 ppm. HREE concentrations obtained by LA-ICP-MS, vary by 2 orders of magnitude from core to rim. The δ18O ratio (Cameca 1270, Nancy), around 5 ppm (SMOW), is constant within error throughout the analysed crystals. In GT2, the situation is different since HREE concentrations appear remarkably constant within a given crystal and from one crystal to the other. In contrast with GT1, Na in GT2 is partly charge-balanced by yttrium incorporation. The δ18O ratio in GT2 of around 7 ppm is close to that encountered in GT3 (gneiss) between 7 and 8 ppm. In GT3, phosphorus content is close to detection limit (P_2O_5 below 300 ppm). HREE concentrations are highly variable from one crystal to the other and unfortunately, the size of garnet crystals does not allow profiling. Although δ18O ratio in garnet is imposed by the bulk-rock isotopic composition, HREE distribution is dominated by element availability through the fluid composition and/or absence/presence of accessory phases. The decrease in HREE and P concentration from GT1 cores to rims suggest that these elements are

Isotopic data bearing on the origin of Mesozoic and Tertiary granitic rocks in the western United States

International Nuclear Information System (INIS)

DePaolo, D.J.; Farmer, G.L.

1984-01-01

A regional survey of initial Nd and Sr isotopic compositions has been done on Mesozoic and Tertiary granitic rocks from a 500 000 km 2 area in California, Nevada, Utah, Arizona, and Colorado. The plutons, which range in composition from quartz diorite to monzogranite, are intruded into accreted oceanic geosynclinal terrains in the west and north and into Precambrian basement in the east. Broad geographic coverage allows the data to be interpreted in the context of the regional pre-Mesozoic crustal structure. Initial Nd isotopic compositions exhibit a huge range, encompassing values typical of oceanic magmatic arcs and Archean basement. The sources of the magmas can be inferred from the systematic geographic variability of Nd isotopic compositions. The plutons in the accreted terrains represent mantle-derived magma that assimilated crust while differentiating at deep levels. Those emplaced into Precambrian basement are mainly derived from the crust. The regional patterns can be understood in terms of: (1) the flux of mantle magma entering the crust; (2) crustal thickness; and (3) crustal age. The mantle magma flux apparently decreased inland; in the main batholith belts purely crustal granitic rocks are not observed because the flux was too large. Inland, crustal granite is common because mantle magma was scarce and the crust was thick, and hot enough to melt. The epsilonsub(Nd) values of peraluminous granite formed by melting of the Precambrian basement depend on the age of the local basement source. (author)

Geological environment and mineralizations associated to granite from Serra Dourada (meridional edge) - Goias

International Nuclear Information System (INIS)

Macambira, M.J.B.

1983-01-01

The Serra Dourada granite is related to one of the various large tin-bearing domic structures that occur in central-eastern Goias, where rocks of Uruacu and Brasilia folded belts and of Goias median massif crop out. The present study was undertaken in the southern part of Serra Dourada as an attempt to contribute to the petrologic, metallogenetic and stratigraphic aspects of the granitic rocks present in that region. The methodological approach consisted of the preparation of a 1:45.000 geological map and included the obtention of petrographic, ore microscopic and geochronological data, as well as the determination of major element concentrations in rocks and some minerals. Trace elements were only determined for rocks. (author)

S-type granite generation and emplacement during a regional switch from extensional to contractional deformation (Central Iberian Zone, Iberian autochthonous domain, Variscan Orogeny)

Science.gov (United States)

Pereira, M. F.; Díez Fernández, R.; Gama, C.; Hofmann, M.; Gärtner, A.; Linnemann, U.

2018-01-01

Zircon grains extracted from S-type granites of the Mêda-Escalhão-Penedono Massif (Central Iberian Zone, Variscan Orogen) constrain the timing of emplacement and provide information about potential magma sources. Simple and composite zircon grains from three samples of S-type granite were analyzed by LA-ICP-MS. New U-Pb data indicate that granites crystallized in the Bashkirian (318.7 ± 4.8 Ma) overlapping the proposed age range of ca. 321-317 Ma of the nearby S-type granitic rocks of the Carrazeda de Anciães, Lamego and Ucanha-Vilar massifs. The timing of emplacement of such S-type granites seems to coincide with the waning stages of activity of a D2 extensional shear zone (i.e. Pinhel shear zone) developed in metamorphic conditions that reached partial melting and anatexis (ca. 321-317 Ma). Dykes of two-mica granites (resembling diatexite migmatite) are concordant and discordant to the compositional layering and S2 (main) foliation of the high-grade metamorphic rocks of the Pinhel shear zone. Much of the planar fabric in these dykes was formed during magmatic crystallization and subsequent solid-state deformation. Field relationships suggest contemporaneity between the ca. 319-317 Ma old magmatism of the study area and the switch from late D2 extensional deformation to early D3 contractional deformation. Inherited zircon cores are well preserved in these late D2-early D3 S-type granite plutons. U-Pb ages of inherited zircon cores range from ca. 2576 to ca. 421 Ma. The spectra of inherited cores overlap closely the range of detrital and magmatic zircon grains displayed by the Ediacaran to Silurian metasedimentary and metaigneous rocks of the Iberian autochthonous and parautochthonous domains. This is evidence of a genetic relationship between S-type granites and the host metamorphic rocks. There is no substantial evidence for the addition of mantle-derived material in the genesis of these late D2-early D3 S-type granitic rocks. The ɛNd arrays of heterogeneous

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

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.

Magnetodielectric coupling in multiferroic holmium iron garnets

International Nuclear Information System (INIS)

Malar Selvi, M.; Chakraborty, Deepannita; Venkateswaran, C.

2017-01-01

Single phase magneto-electric multiferroics require a large magnetic or electric field for producing magneto-electric (ME) and magnetodielectric (MD) effects. For utilizing these effects in devices investigations on the room temperature and low field MD studies are necessary. Recently, efforts have been largely devoted to the investigation of rare earth iron garnets. In the physical method, the preparation of rare earth iron garnet requires high sintering temperature and processing time. To solve these problems, ball milling assisted microwave sintering technique is used to prepare nanocrystalline holmium iron garnets (Ho_3Fe_5O_1_2). Magnetic and dielectric properties of the prepared sample are investigated. These properties get enhanced in nanocrystalline form when compared to the bulk. The MD coupling of the prepared sample is evident from the anomaly in the temperature dependent dielectric constant plot and the ME coupling susceptibility is derived from the room temperature MD measurements. - Highlights: • Formation of single phase Holmium iron garnet reported. • Ball milling assisted microwave sintering reduces the sintering temperature and time. • Holmium iron garnet shows enhanced magnetic and dielectric properties. • Pyromagnetic and pyroelectric measurements confirm the magnetoelectric coupling. • Room temperature magnetodielectric measurements show the nonlinear behaviour.

Garnet - two pyroxene rock from the Gridino complex, Russia: a record of the early metasomatic stage

Science.gov (United States)

Morgunova, Alena A.; Perchuk, Alexei L.

2010-05-01

The Gridino complex is one of the oldest high pressure complexes on the Earth. The most spectacular exposures occur in islands and in a 10-50 m wide belt along the shore of the White Sea in the Gridino area. The exotic blocks show wide range of compositions. In addition to predominating amphibolites and eclogites, there are also peridotites, zoisitites and sapphirine-bearing rocks. The peridotites are represented by garnet - two pyroxene rocks and orthopyroxenites. It this paper we present an intriguing results of the petrological study of the garnet- two pyroxene rock. The garnet- two pyroxene rock considered occurs as elliptical body 4×6 m in size within amphibole-biotite gneiss in the island Visokii. The rock consists of mosaic of coarse-grained primary garnet, clinopyroxene and orthopyroxene. Accessories are represented by magnetite, ilmenite, pyrite and zircon. Garnet contains inclusions of clinopyroxene, Mg-calcite and chlorite. The chlorite inclusions always intergrow with dendritic mineral enriched in REE (mainly Ce) situated on the wall of vacuole which shows the tendency of negative crystal shape. Similar chlorite inclusions are hosted by clino- and orthopyroxenes. The chlorite is of diabantite composition. The inclusions are often surrounded by the two systems of cracks - radial and concentric, which is really exotic phenomenon for crystalline rock. The primary minerals experienced different degree of the retrograde alteration expressed as amphibolization and/or growth of the orthopyroxene-amphibole-garnet symplectites. The retrogression is patchy in the central part of garnet- two pyroxene body, but intensifies towards the rims where primary minerals are absent. Mineral thermobarometry reveals HP rock equilibration at 670-750 оС and 14-20 kbar followed by subisothermal decompression down to 640-740 оС and 6-14 kbar. Specific composition of the chlorite and its association with REE phase in all rock-forming minerals suggests that anhydrous HP

Petrology of the Fort Smith - Great Slave Lake radiometric high near Pilot Lake, N.W.T

International Nuclear Information System (INIS)

Burwash, R.A.; Cape, D.F.

1981-01-01

Near Pilot Lake, the east boundary of the Fort Smith - Great Slave Lake radiometric high coincides with the contact of a well-foliated, porphyroblastic microcline-plagioclase-quartz-garnet-biotite gneiss (Pilot Lake Gneiss) with a hybrid assemblage of quartzite, mica schist, garnet-cordierite gneiss, and minor amphibolite (Variable Paragneiss). Anomalously high concentrations of uranium and thorium are associated with mafic-rich, lenticular bodies with a mineral assemblage biotite + monazite + zircon + ilmenite + hematite +- plagioclase +- quartz, within both the Variable Paragneiss and the Pilot Lake Gneiss. Corundum and spinel occur in the mafic lenses and sillimanite, kyanite, and hypersthene in other inclusions of the Pilot Lake Gneiss. The ilmenite-magnetite--monazite-zircon-apatite assemblage is interpreted as a 'black sand' concentration in a clastic sedimentary sequence subsequently metamorphosed by a regional granulite facies event. A granite pluton intruded during the same orogenic cycle assimilated the clastic metasedimentary rocks containing black sand interlayers, becoming enriched in thorium from the monazite. A second metamorphic event at lower P-T conditions, accompanied by strong cataclasis, developed the texture of the Pilot Lake Gneiss as now observed. Shearing within the gneiss locally concentrated hematite + quartz + uranium. Regional tectonic extrapolations suggest that the pyroxene granulite event was Kenoran and the later amphibolite event Hudsonian. (author)

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

Three tier transition of Neoarchean TTG-sanukitoid magmatism in the Beit Bridge Complex, Southern Africa

Science.gov (United States)

Rajesh, H. M.; Belyanin, G. A.; Van Reenen, D. D.

2018-01-01

Neoarchean TTG-sanukitoid associations of contrasting scales occur within the Beit Bridge Complex terrane of the Limpopo Complex in southern Africa. These include the smaller 2.65-2.63 Ga Avoca granitoid and the voluminous 2.73-2.64 Ga Alldays granitoid. This study characterizes the wide compositional spectrum preserved in these two granitoids. The elliptical Avoca pluton consists of a biotite-amphibole-orthopyroxene ± clinopyroxene-bearing core that is dominantly trondhjemite with less dominant tonalite and granodiorite variants, and a thin amphibole-biotite-bearing granite rim, with local occurrence of two-pyroxene-bearing metabasite boudins. While both the core and rim rocks exhibit a linear fabric, the granite in addition preserves a penetrative foliation. Field relations of granite enclaves in the core rocks together with available ages indicate that the core rocks intruded the granite. The foliated biotite ± amphibole-bearing Alldays granitoid contains inclusions of older supracrustals and rocks of the Messina layered intrusion, and is widely distributed. Compositionally, it include tonalites and granodiorites and to a lesser extent trondhjemites. Both the Avoca core and rim rocks are characterized by difference in mineral chemistry, with the mafic minerals Mg-rich in the TTG core, while they are Fe-rich in the granite and metabasite. In comparison, biotite is Mg-rich and amphibole is Fe-rich in the Alldays granitoid. Two groups of Alldays TTG can be delineated in terms of whole-rock geochemical characteristics, and are comparable to the low- to medium-pressure TTG groups delineated by Moyen (2011), while the Avoca TTG is similar to the high-pressure TTG group. The lowest silica samples from each group of granitoid have geochemical characteristics comparable to Archean sanukitoids, with those from the Avoca granitoid similar to low-Ti sanukitoids, and those from the Alldays granitoid similar to low-Ti and high-Ti sanukitoids. Separate petrogenetic models

The solubility and site preference of Fe3+ in Li7-3xFexLa3Zr2O12 garnets

Science.gov (United States)

Rettenwander, D.; Geiger, C. A.; Tribus, M.; Tropper, P.; Wagner, R.; Tippelt, G.; Lottermoser, W.; Amthauer, G.

2015-10-01

A series of Fe3+-bearing Li7La3Zr2O12 (LLZO) garnets was synthesized using solid-state synthesis methods. The synthetic products were characterized compositionally using electron microprobe analysis and inductively coupled plasma optical emission spectroscopy (ICP-OES) and structurally using X-ray powder diffraction and 57Fe Mössbauer spectroscopy. A maximum of about 0.25 Fe3+ pfu could be incorporated in Li7-3xFexLa3Zr2O12 garnet solid solutions. At Fe3+ concentrations lower than about 0.16 pfu, both tetragonal and cubic garnets were obtained in the synthesis experiments. X-ray powder diffraction analysis showed only a garnet phase for syntheses with starting materials having intended Fe3+ contents lower than 0.52 Fe3+ pfu. Back-scattered electron images made with an electron microprobe also showed no phase other than garnet for these compositions. The lattice parameter, a0, for all solid-solution garnets is similar with a value of a0≈12.98 Å regardless of the amount of Fe3+. 57Fe Mössbauer spectroscopic measurements indicate the presence of poorly- or nano-crystalline FeLaO3 in syntheses with Fe3+ contents greater than 0.16 Fe3+ pfu. The composition of different phase pure Li7-3xFexLa3Zr2O12 garnets, as determined by electron microprobe (Fe, La, Zr) and ICP-OES (Li) measurements, give Li6.89Fe0.03La3.05Zr2.01O12, Li6.66Fe0.06La3.06Zr2.01O12, Li6.54Fe0.12La3.01Zr1.98O12, and Li6.19Fe0.19La3.02Zr2.04O12. The 57Fe Mössbauer spectrum of cubic Li6.54Fe0.12La3.01Zr1.98O12 garnet indicates that most Fe3+ occurs at the special crystallographic 24d position, which is the standard tetrahedrally coordinated site in garnet. Fe3+ in smaller amounts occurs at a general 96h site, which is only present for certain Li-oxide garnets, and in Li6.54Fe0.12La3.01Zr1.98O12 this Fe3+ has a distorted 4-fold coordination.

A study of small-scale foliation in lengths of core enclosing fault zones in borehole WD-3, Permit Area D, Lac du Bonnet Batholith

Energy Technology Data Exchange (ETDEWEB)

Ejeckam, R. B.

1992-12-01

Small-scale foliation measurements in lengths of core from borehole WD-3 of Permit Area D of the Lac du Bonnet Batholith have defined five major mean orientation sets. They strike NW, N and NE. The orientations (strike to the left of the dip direction/dip) of these sets are as follows: Set I - 028/74 deg; II - 001/66 deg; III - 100/58 deg; IV - 076/83 deg; and V - 210/40 deg. The small-scale foliations were defined by different mineral types such as biotite crystals, plagioclase, mineral banding and quartz lenses. Well-developed biotite foliation is commonly present whenever well-developed plagioclase foliation exists, but as the strength of development weakens, the preferred orientations of plagioclase foliation do not correspond to those of biotite. It is also noted that the foliations appear to strike in directions orthogonal to the fractures in the fracture zones in the same depth interval. No significant change in foliation orientation was observed in Zones I to IV. Set V, however, whose mean orientation is 210/40 deg, is absent from the Zone IV interval, ranging from 872 to 905 m. (auth)

The solubility and site preference of Fe{sup 3+} in Li{sub 7−3x}Fe{sub x}La{sub 3}Zr{sub 2}O{sub 12} garnets

Energy Technology Data Exchange (ETDEWEB)

Rettenwander, D., E-mail: daniel.rettenwander@sbg.ac.at [Department of Materials Research and Physics, University of Salzburg, 5020 Salzburg (Austria); Geiger, C.A. [Department of Materials Research and Physics, University of Salzburg, 5020 Salzburg (Austria); Tribus, M.; Tropper, P. [Institute of Mineralogy and Petrography, Faculty of Geo- and Atmospheric Sciences, University of Innsbruck, Innrain 52, 6020 Innsbruck (Austria); Wagner, R.; Tippelt, G.; Lottermoser, W.; Amthauer, G. [Department of Materials Research and Physics, University of Salzburg, 5020 Salzburg (Austria)

2015-10-15

A series of Fe{sup 3+}-bearing Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} (LLZO) garnets was synthesized using solid-state synthesis methods. The synthetic products were characterized compositionally using electron microprobe analysis and inductively coupled plasma optical emission spectroscopy (ICP-OES) and structurally using X-ray powder diffraction and {sup 57}Fe Mössbauer spectroscopy. A maximum of about 0.25 Fe{sup 3+} pfu could be incorporated in Li{sub 7−3x}Fe{sub x}La{sub 3}Zr{sub 2}O{sub 12} garnet solid solutions. At Fe{sup 3+} concentrations lower than about 0.16 pfu, both tetragonal and cubic garnets were obtained in the synthesis experiments. X-ray powder diffraction analysis showed only a garnet phase for syntheses with starting materials having intended Fe{sup 3+} contents lower than 0.52 Fe{sup 3+} pfu. Back-scattered electron images made with an electron microprobe also showed no phase other than garnet for these compositions. The lattice parameter, a{sub 0}, for all solid-solution garnets is similar with a value of a{sub 0}≈12.98 Å regardless of the amount of Fe{sup 3+}. {sup 57}Fe Mössbauer spectroscopic measurements indicate the presence of poorly- or nano-crystalline FeLaO{sub 3} in syntheses with Fe{sup 3+} contents greater than 0.16 Fe{sup 3+} pfu. The composition of different phase pure Li{sub 7−3x}Fe{sub x}La{sub 3}Zr{sub 2}O{sub 12} garnets, as determined by electron microprobe (Fe, La, Zr) and ICP-OES (Li) measurements, give Li{sub 6.89}Fe{sub 0.03}La{sub 3.05}Zr{sub 2.01}O{sub 12}, Li{sub 6.66}Fe{sub 0.06}La{sub 3.06}Zr{sub 2.01}O{sub 12}, Li{sub 6.54}Fe{sub 0.12}La{sub 3.01}Zr{sub 1.98}O{sub 12}, and Li{sub 6.19}Fe{sub 0.19}La{sub 3.02}Zr{sub 2.04}O{sub 12}. The {sup 57}Fe Mössbauer spectrum of cubic Li{sub 6.54}Fe{sub 0.12}La{sub 3.01}Zr{sub 1.98}O{sub 12} garnet indicates that most Fe{sup 3+} occurs at the special crystallographic 24d position, which is the standard tetrahedrally coordinated site in garnet. Fe{sup 3+} in smaller

Disorganized foliation of unilateral cerebellar hemisphere as cerebellar cortical dysplasia in patients with recurrent seizures: A case report

Energy Technology Data Exchange (ETDEWEB)

Baek, Hye Jin [Dept. of Radiology, Haeundae Paik Hospital, Inje University College of Medicine, Busan (Korea, Republic of)

2013-09-15

We present a rare case of abnormal foliation for one cerebellar hemisphere on MR imaging, showing vertically-oriented folia. Foliation of contralateral cerebellar hemisphere and other structures in the posterior fossa were normal, and the patient has no neurologic deficits. This rare and unique abnormality is considered a kind of developmental error of the cerebellum.

Isotopic chronometry of zoned garnets: Growth kinetics and metamorphic histories

International Nuclear Information System (INIS)

Vance, D.; O'Nions, R.K.

1990-01-01

Basic information on the chronological and pressure-temperature evolution of regional metamorphic terrains may in principle be derived from metamorphic garnets because of the similarly low diffusivities of Sm, Nd and major cations in this mineral. We report here Sm-Nd and Rb-Sr isotopic and major element data on prograde garnets from regionally metamorphosed pelites from Newfoundland. The garnets preserve a prograde major element zonation as well as a sympathetic variation in Sm/Nd ratio. Sm-Nd data for separated portions of the garnet from core to rim provide both upper limits on the time for garnet growth and demonstrate synchronous growth of different garnet grains on a hand specimen scale. The Rb-Sr data on the same garnet fractions are in general agreement with these results but in some cases cannot be interpreted in terms of growth. A minimum heating rate of 3 K Ma -1 is derived by combining the estimates for garnet growth time with the apparent temperature interval over which the garnet grew, deduced from the major element zonation. This value is similar to the minimum suggested by theoretical models for the thermal evolution of thickened continental crust. The growth rate is within the range of 1.3-19 mm Ma -1 , set respectively by the isotopic data and the likely upper limit for heating rate during regional metamorphism. These growth rates appear too slow to be controlled by surface reaction and suggest that other factors, such as transport, may be rate-limiting. In this case, the limits set of the effective diffusion coefficient for material transport to the growth site (=0.4-6.1x10 -17 m 2 s -1 ) suggest that grain boundary diffusion is probably the transport mechanism for supply of material to the growing garnet. (orig.)

Selected visualizations and summaries of the contents of the foliation and lithology data regarding drillholes OL-KR1 - OL-KR38

International Nuclear Information System (INIS)

Kuusisto, S.; Raunio, J.-P.

2010-01-01

Posiva Oy has acquired an extensive amount of data on the geology of the Olkiluoto Island. Part of that data is the collection of foliation information, known as the foliation database. In this work, the foliation database was studied and analyzed using data mining techniques aiming to characterize the properties of the database. The goal was to discover previously unknown correlations, patterns, and properties contained within the data. In addition to the foliation database, deviation survey measurements were used as a supporting dataset. The following analyses related to the general properties of the database were carried out: logical discrepancies and potential errors in data; statistics of alphanumeric strings, numeric values, and empty fields; discovery of stereotypic data items whose appearance count deviates significantly from the count that would be expected if the properties were assumed independent; analysis of free text remarks; comparison between reported foliation orientations with those that were recalculated using the core orientations and foliation orientations with respect to core. Rock and foliation type sequences were analysed both in terms of the lengths of contiguous segments and the frequencies in which different sequences appear in the drillholes. The variance of rock types and the density of measurements was assessed by dividing the bedrock volume of interest into cubes and providing numerical values for these quantities for each cube. This was carried out in two resolutions: cube's sides were 500 m and 200 m. The foliation orientations were summarized also with respect to these cubes. In addition to analysis tasks, another task was to come up with alternative bedrock models - in terms of rock type units - based on data that contains rock type classifications and foliation orientation measurements obtained from drillholes. The interpretation of the analysis results was beyond the scope of this work. The assessment of the novelty and the

Measurement of natural radioactivity in granites and its quartz-bearing gold at El-Fawakhir area (Central Eastern Desert, Egypt

Directory of Open Access Journals (Sweden)

M.A.M. Uosif

2015-07-01

Full Text Available The distribution of natural radionuclides (226Ra, 232Th and 40K in Granites and its quartz-bearing gold at El-Fawakhir area (Central Eastern Desert, Egypt were measured by using γ-ray spectroscopy [NaI (Tl 3″ × 3″]. X-Ray Fluorescence technique was used for chemical analyses of the studied samples. The specific activity of 226Ra, 232Th and 40K values are in range (3 ± 0.5 to 43 ± 2 Bqkg−1, (5 ± 0.7 to 41 ± 2 Bqkg−1 and (128 ± 6 to 682 ± 35 Bqkg−1 respectively. The absorbed dose rates ranged from 13.8 to 58.4 nGy h−1, where the total effective dose rates were determined to be between 16.7 and 70.9 μSvy−1. The maximum external hazard index (Hex is 0.3 nGyh−1. The calculated values of the excess lifetime cancer risks (ELCR and annual effective dose rate values are in between (8.48 × 10−5 and 2.63 × 10−4 and (24.2 and 72.9 μSvy−1 respectively. Geochemically, the studied granites consist of major oxides, they are characterized by SiO2, K2O, Na2O, Al2O3, and depleted in CaO, MgO, TiO2, and P2O5. The average absorbed dose rate (Do in air is 37.8 nGyh−1 for the whole studied samples, this value is about 3.78% of the 1.0 mSvy−1 recommended by (ICRP-60,1991 to the public, so there is no radiological risk for the workers in that area.

On the automorphisms of foliations defined by complex linear vectorfields

International Nuclear Information System (INIS)

Shahshahani, S.

1989-04-01

We study biholomorphisms of C n that preserve the foliation associated to a complex linear vector fields. It is shown that for hyperbolic Poincare vector fields the only such biholomorphisms are linear. Nonlinear biholomorphisms emerge in the presence of resonance among the eigenvalues of the system. A complete classification is given in dimension 2. (author). 8 refs, 1 fig

Temporal evolution of granitic magmas in the Luanchuan metallogenic belt, east Qinling Orogen, central China: Implications for Mo metallogenesis

Science.gov (United States)

Li, Dong; Han, Jiangwei; Zhang, Shouting; Yan, Changhai; Cao, Huawen; Song, Yaowu

2015-11-01

The Luanchuan metallogenic belt, located within the eastern part of the Qinling Orogen, central China, hosts a number of world-class Mo deposits that are closely related to small late Mesozoic granitic plutons. Zircon U-Pb dating of distinct plutons in the Luanchuan metallogenic belt has yielded ages of 153 ± 1, 154 ± 2, 152 ± 2, and 148 ± 1 Ma. Molybdenite Re-Os isotopic compositions of Yuku ore district in the southern part of Luanchuan metallogenic belt has yielded an isochron age of 146 ± 1 Ma, which is consistent with the large-scale mineralization ages in the northern part of the Luanchuan metallogenic belt. A combination of previous studies and new geochronological and isotopic data show a concordant temporal and genetic link between granitic magmatism and Mo mineralization in the Luanchuan metallogenic belt, suggesting that this mineralization episode formed the most extensive Mo mineralization belt in the east Qinling Orogen. Zircon grains from Mo-related granitic plutons show similar trace element distributions. High-precision Multi Collector-Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS) Pb isotope analysis of K-feldspar megacrysts from mineralization-related granites suggest that they were derived from the lower crust. Similarly, the Pb isotopic compositions of pyrite coprecipitated with molybdenite also suggest that the metals were derived form the lower crust, with probably minor mantle contribution. A continuum mineralization model that describes the sourcing of Mo from an evolving granitic magma over successive differentiation events, possibly in separate but connected magma chambers, could explain the remarkable Mo enrichment in the Luanchuan metallogenic belt. The volatile- and Mo-bearing granitic magmas ascended as diapirs from the deep crust, and were emplaced as dikes in the upper crust. Lithological differences between these Mo-bearing granites may relate to different stages in the evolution of individual magmas. Finally, ore

Lu-Hf and Sm-Nd garnet geochronology

DEFF Research Database (Denmark)

Smit, Matthijs Arjen; Scherer, Erik E.; Mezger, Klaus

2013-01-01

To investigate the systematics of the 176Lu–176Hf and 147Sm–143Nd garnet chronometers, we performed REE and isotope analyses on garnet crystals of different size (0.55–3.1 mm radius) from a single granulite specimen (Archean Pikwitonei Granulite Domain, Manitoba, Canada). The Lu–Hf dates are simi...

Petrology of skarns in the north and the southwest of Qazan (South Qamsar with emphasis on the mineral chemistry of garnet and pyroxene

Directory of Open Access Journals (Sweden)

Maria Chavideh

2018-03-01

Full Text Available The Oligo-Miocene Qazan granitoid body caused contact metamorphic of surrounding rocks and skarn formation in the wall limestone. The main intrusive rocks are essentially granite to diorite in composition. Two different types of skarn, exo and endoskarn have been developed. On the base of microprobe data, the northern skarn are characterized by zoning and the amounts of andradite and grossular changes oscillatory. While garnets from the southwestern skarn is predominantly andradite in composition. Using Fe/Ti vs. Al/ (Al+Fe+Mn diagram that were calculated based on the mole percent of the used elements, it is estimated that about less than 50 percent hydrothermal waters were involved for the northern skarn whereas it was over this amount for the southwestern skarn. This leds to difference in garnet composition. The composition of clinopyroxene in both skarns is the same (diopside. As a result, hydrothermal fluids have not had much influence on pyroxene genesis. With regards to the occurrence of mineral assemblage and the presence of wollastonite in the skarns under study, these rocks have evolved in temperature above 500 ° C and O2 fugacity in the range of 10-17 to 10-15.

Mueilha rare metals granite, Eastern Desert of Egypt: An example of a magmatic-hydrothermal system in the Arabian-Nubian Shield

Science.gov (United States)

Abu El-Rus, Mohamed A.; Mohamed, Mohamed A.; Lindh, Anders

2017-12-01

The Mueilha granite pluton is one of the rare-metals bearing peraluminous granitic plutons in the Arabian-Nubian Shield. It represents the apical part of a highly evolved magma chamber emplaced at a shallow level subsequent to the post Pan-African orogeny. The pluton can be seen as a highly leucocratic medium-grained albite/oligoclase framework infilled with quartz, K-feldspar and muscovite that are variably overgrown by K-feldspar, muscovite, quartz and topaz megacrysts. The increasing number and size of the K-feldspar megacrysts at the expense of the whitened albite/oligoclase framework imparts variably red color to the Mueilha granite. Contacts between the milky white and red granites are usually gradational, but may be locally sharp or may form narrow transition zones resulting from abrupt variations in texture and lithology. Textural relations indicate an initial stage of hydrothermal albitization of magmatic plagioclase and crystallization of topaz megacrysts resulting from infiltration of Na-rich fluorine bearing fluids. A subsequent stage of metasomatic enrichment is characterized by extensive growth of large K-feldspar, quartz and muscovite megacrysts at the expense of the albite/oligoclase crystals as a result of infiltration of K-Si rich hydrous fluids. Post-magmatic infiltration of hydrous fluids along the fault planes is shown by the intense replacement of alkali feldspar megacrysts by quartz, development of myrmekitic intergrowth pockets along the K-feldspar megacrysts and sealing of the micro-fractures by cryptocrystalline mixtures of clay minerals, iron oxides, sericite and chlorite. Compositionally, the red granitic rocks have higher SiO2, Fe2O3total, K2O/Na2O, Σ REE, Y, Th, U, Zr and Zn and lower Al2O3, Ga, Ta, Nb and Mo compared to the milky white granites. LILE and Sn do not show clear variation trends throughout the Mueilha granite pluton, suggesting their immobility during hydrothermal alteration. Microthermometric measurements indicate that

Static Magnetic Properties of AL800 Garnet Material

Energy Technology Data Exchange (ETDEWEB)

Kuharik, J. [Fermilab; Madrak, R. [Fermilab; Makarov, A. [Fermilab; Pellico, W. [Fermilab; Sun, S. [Fermilab; Tan, C. Y. [Fermilab; Terechkine, I. [Fermilab

2017-05-17

A second harmonic tunable RF cavity is being devel-oped for the Fermilab Booster. This device, which prom-ises reduction of the particle beam loss at the injection, transition, and extraction stages, employs perpendicularly biased garnet material for frequency tuning. The required range of the tuning is significantly wider than in previously built and tested tunable RF devices. As a result, the mag-netic field in the garnet comes fairly close to the gyromag-netic resonance line at the lower end of the frequency range. The chosen design concept of a tuner for the cavity cannot ensure uniform magnetic field in the garnet mate-rial; thus, it is important to know the static magnetic prop-erties of the material to avoid significant increase in the lo-cal RF loss power density. This report summarizes studies performed at Fermilab to understand variations in the mag-netic properties of the AL800 garnet material used to build the tuner of the cavity.

Low-degree partial melting of metapelites - another possible implement for selective concentration of uranium: Example from the Rozna uranium deposit, Bohemian Massif

International Nuclear Information System (INIS)

Leichmann, J.; Matula, M.; Broska, I.; Holeczy, D.

2002-01-01

Monazite, as the main carrier of U and Th in host biotite gneiss at the Rozna uranium deposit, was replaced by allanite during the process of partial melting. The transformation was accompanied by a release of U, and to a lesser extent of Th, from the monazite lattice. The liberated U and Th crystallized in the extracted granitic melt mainly in the form of thorogummite or cheralite. The granites are depleted in HFS and LREE. Garnet-poor granites are depleted in HREE as well, whereas garnet-rich types are enriched in HREE. (author)

A-type granites from the Guéra Massif, Central Chad: Petrology, geochemistry, geochronology, and petrogenesis.

Science.gov (United States)

Pham, Ngoc Ha T.; Shellnutt, J. Gregory; Yeh, Meng-Wan; Lee, Tung-Yi

2017-04-01

The poorly studied Saharan Metacraton of North-Central Africa is located between the Arabian-Nubian Shield in the east, the Tuareg Shield in the west and the Central African Orogenic Belt in the south. The Saharan Metacraton is composed of Neoproterozoic juvenile crust and the relics of pre-Neoproterozoic components reactivated during the Pan-African Orogeny. The Republic of Chad, constrained within the Saharan Metacraton, comprises a Phanerozoic cover overlying Precambrian basement outcroppings in four distinct massifs: the Mayo Kebbi, Tibesti, Ouaddaï, and the Guéra. The Guéra massif is the least studied of the four massifs but it likely preserves structures that were formed during the collision between Congo Craton and Saharan Metacraton. The Guéra Massif is composed of mostly granitic rocks. The granitoids have petrologic features that are consistent with A-type granite, such as micrographic intergrowth of sodic and potassic feldspar, the presence of sodic- and iron-rich amphibole, and iron-rich biotite. Compositionally, the granitic rocks of the Guéra Massif have high silica (SiO2 ≥ 68.9 wt.%) content and are metaluminous to marginally peraluminous. The rocks are classified as ferroan calc-alkalic to alkali-calcic with moderately high to very high Fe* ratios. The first zircon U/Pb geochronology of the silicic rocks from the Guéra Massif yielded three main age groups: 590 Ma, 570 Ma, 560 Ma, while a single gabbro yielded an intermediate age ( 580 Ma). A weakly foliated biotite granite yielded two populations, in which the emplacement age is interpreted to be 590 ± 10 Ma, whereas the younger age (550 ± 11 Ma) is considered to be a deformation age. Furthermore, inherited Meso- to Paleoproterozoic zircons are found in this sample. The geochemical and geochronology data indicate that there is a temporal evolution in the composition of rocks with the old, high Mg# granitoids shifting to young, low Mg# granitoids. This reveals that the A-type granites in

Charnockites and granites of the western Adirondacks, New York, USA: a differentiated A-type suite

Science.gov (United States)

Whitney, P.R.

1992-01-01

Granitic rocks in the west-central Adirondack Highlands of New York State include both relatively homogeneous charnockitic and hornblende granitic gneisses (CG), that occur in thick stratiform bodies and elliptical domes, and heterogeneous leucogneisses (LG), that commonly are interlayered with metasedimentary rocks. Major- and trace-element geochemical analyses were obtained for 115 samples, including both types of granitoids. Data for CG fail to show the presence of more than one distinct group based on composition. Most of the variance within the CG sample population is consistent with magmatic differentiation combined with incomplete separation of early crystals of alkali feldspar, plagioclase, and pyroxenes or amphibole from the residual liquid. Ti, Fe, Mg, Ca, P, Sr, Ba, and Zr decrease with increasing silica, while Rb and K increase. Within CG, the distinction between charnockitic (orthopyroxene-bearing) and granitic gneisses is correlated with bulk chemistry. The charnockites are consistently more mafic than the hornblende granitic gneisses, although forming a continuum with them. The leucogneisses, while generally more felsic than the charnockites and granitic gneisses, are otherwise geochemically similar to them. The data are consistent with the LG suite being an evolved extrusive equivalent of the intrusive CG suite. Both CG and LG suites are metaluminous to mildly peraluminous and display an A-type geochemical signature, enriched in Fe, K, Ce, Y, Nb, Zr, and Ga and depleted in Ca, Mg, and Sr relative to I- and S-type granites. Rare earth element patterns show moderate LREE enrichment and a negative Eu anomaly throughout the suite. The geochemical data suggest an origin by partial melting of biotite- and plagioclase-rich crustal rocks. Emplacement occurred in an anorogenic or post-collisional tectonic setting, probably at relatively shallow depths. Deformation and granulite-facies metamorphism with some partial melting followed during the Ottawan phase

Combined external-beam PIXE and {mu}-Raman characterisation of garnets used in Merovingian jewellery

Energy Technology Data Exchange (ETDEWEB)

Calligaro, T. E-mail: thomas.calligaro@culture.gouv.fr; Colinart, S.; Poirot, J.-P.; Sudres, C

2002-04-01

Red garnets were the dominant gemstones used for jewels in Europe during the Early Middle Ages. We have studied over 350 garnets set on 12 jewels unearthed in the royal necropolis of the Saint-Denis Basilica, close to Paris. This famous collection of 'cloisonne' style artefacts dates from the Merovingian period (late fifth century AD to early seventh century AD). The archaeological issue addressed is the identification of the geographical origin of these garnets, in view to establish the gem trading routes during the Dark Ages. External beam PIXE was used to determine the major constituents (Mg, Al, Si, Ca, Mn, Fe), specifying the garnet type (composition in various mineralogical end-members, e.g. almandine, pyrope, spessartite, ...), and the trace element content (Cr, Y). Three sorts of garnets were identified. Ten jewels are adorned with almandine garnets (Fe-rich). One jewel has intermediate almandine-pyrope garnets ('rhodolite'). The last and most recent jewel is inlaid with pyrope (Mg-rich) garnets. Trace element content and slight differences in major composition allowed to distinguish five different sources: two sources for pyrope garnets (with and without chromium), and two sources for almandine garnets (distinctive calcium, magnesium and yttrium contents). A preliminary comparison with literature data suggested that almandine garnets may have been mined from India while the 'rhodolite' garnets may have been imported from Sri Lanka. The sources of pyrope garnets could be the Bohemian deposits (Czech republic). In addition, {mu}-Raman spectrometry was used to identify most of the mineral inclusions (apatite, zircon, ilmenite, monazite, calcite, quartz) present in almandine garnets. Even if two specific types of inclusions were not identified, due to the lack of corresponding reference spectra in our database, the Raman spectra collected provided an interesting inclusion fingerprint.

Industrial garnet

Science.gov (United States)

Olson, D.W.

2007-01-01

World production of industrial garnet was about 326 kt in 2006, with the U.S. producing about 11 percent of this total. U.S. consumption, imports, and exports were estimated at 74.3 kt, 52.3 kt, and 13.2 kt, respectively. The most important exporters are Australia, China, and India. Although demand is expected to rise over the next 5 years, prices are expected to remain low in the short term.

Unraveling the history of complex zoned garnets from the North Motagua Mélange (Guatemala)

Science.gov (United States)

Barickman, M. H.; Martin, C.; Flores, K. E.; Harlow, G. E.; Bonnet, G.

2016-12-01

The Guatemala Suture Zone (GSZ) is situated in central Guatemala, between the North American and Caribbean plates. Two serpentinite mélanges straddle the Motagua Fault system: the North Motagua Mélange (NMM) and the South Motagua Mélange (SMM). In this study, chemically zoned garnet grains from four eclogite blocks from the NMM were analyzed by EMPA for major elements and LA-ICP-MS for trace elements to unravel the geological history of the eclogites. These eclogites typically consist of euhedral to subhedral garnets, partly retrogressed omphacite grains, and accessory minerals such as phengite and epidote as inclusions in garnet. EBSD was employed to examine apparent garnet inclusions in garnet. The garnet grains in NMM eclogites display complex chemical zonations: all grains roughly show a spessartine-rich core, an almandine-rich core and/or intermediate zone, and a pyrope and grossular-rich rim. Additionally, crystal resorption can be observed between the different zones, and the pyrope-grossular rim can display oscillatory zoning. Finally, grossular-rich zones (crystallographically syntactic) within garnet are present in all studied samples. REE and spider diagrams do not show any significant difference in the patterns of the different zones within the garnet, or indicating that the chemical environment from which each garnet zone grew was broadly the same. The lack of significant variation in LILE content indicates that a fluid influx during garnet growth is unlikely. Consequently, we interpret that garnet grains grew in a largely closed system; however, the presence of the grossular-rich zones, argues for occasional excursions into conditions when either two garnets crystallized or Ca-rich overgrowths that were largely resorbed prior to subsequent continued garnet growth.

Heat production in granitic rocks

DEFF Research Database (Denmark)

Artemieva, Irina; Thybo, Hans; Jakobsen, Kiki

2017-01-01

Granitic rocks play special role in the dynamics and evolution of the Earth and its thermal regime. First, their compositional variability, reflected in the distribution of concentrations of radiogenic elements, provides constraints on global differentiation processes and large scale planetary...... evolution, where emplacement of granites is considered a particularly important process for the formation of continental crust. Second, heat production by radioactive decay is among the main heat sources in the Earth. Therefore knowledge of heat production in granitic rocks is pivotal for thermal modelling...... of the continental lithosphere, given that most radiogenic elements are concentrated in granitic rocks of the upper continental crust whereas heat production in rocks of the lower crust and lithospheric mantle is negligible. We present and analyze a new global database GRANITE2017 (with about 500 entries...

Geochemical comparison between topaz-bearing granites of the Central and Western Krušné Hory Mts

Czech Academy of Sciences Publication Activity Database

René, Miloš

21(125) (2002), s. 111-126 ISSN 1211-1910 R&D Projects: GA MŠk ME 364 Institutional research plan: CEZ:AV0Z3046908 Keywords : Bohemian Massif * P-rich granite * peraluminous Subject RIV: DB - Geology ; Mineralogy

Natural analogue studies in crystalline rock: the influence of water-bearing fractures on radionuclide immobilisation in a granitic rock repository

International Nuclear Information System (INIS)

Alexander, W.R.; MacKenzie, A.B.; Scott, R.D.; McKinley, I.G.

1990-06-01

Current Swiss concepts for the disposal of radioactive waste involve disposal in deep mined repositories to ensure that only insignificant quantities of radionuclides will ever reach the surface and so enter the biosphere. The rock formations presently considered as potential candidates for hosting radwaste repositories have thus been selected on the basis of their capacity to isolate radionuclides from the biosphere. An important factor in ensuring such containment is a very low solute transport rate through the host formation. However, it is considered likely that, in the formations of interest in the Swiss programme (eg. granites, argillaceous sediments, anhydrite), the rocks will be fractured to some extent even at repository depth. In the instance of the cumulative failure of near-field barriers in the repository, these hydraulically connected fractures in the host formation could be very important far-field routes of migration (and possible sites of retardation) of radionuclides dissolved in the groundwaters. In this context, the so-called 'matrix diffusion' mechanism is potentially very important for radionuclide retardation. This report is the culmination of a programme which has attempted to assess the potential influence of these water-bearing fractures on radionuclide transport in a crystalline rock radwaste repository. 162 refs., 36 figs., 16 tabs

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

Microstructures and physical properties of waste garnets as a promising construction materials

Directory of Open Access Journals (Sweden)

Habeeb Lateef Muttashar

2018-06-01

Full Text Available Rapid industrial growth has witnessed the ever-increasing utilization of sand from rivers for various construction purposes, which caused an over-exploitation of rivers’ beds and disturbed the eco-system. strong engineering properties of waste garnets offer a recycling alternative to create efficient construction materials. Recycling of garnets provides a cost-effective and environmentally responsible solution rather than dumping it as industrial waste. In this spirit, this article presents an investigation into the capacity of spent garnets as sand replacement. The main parameters studied were the evolution of leaching performance, microstructure of the raw spent garnet and sand specimens. The microstructures, boning vibrations and thermal properties of the raw materials were determined using X-ray diffraction (XRD, field emission scanning microscopy (FESEM, Fourier transform infrared (FTIR spectroscopy, and thermo gravimetric analysis (TGA. Admirable features of the results suggest that the spent garnet is proven to be suitable replacement of sand. It is established that proper exploitation of spent garnet as an alternative to sand could save the earth from depleting the natural resources which is essential for sustainable development. Keywords: Spent garnet, Sand, Micro-structures, Recycling, Concrete

Comparison of Conventional, Trace Element, and Pseudosection Thermobarometry in UHP Eclogite, North Qaidam Terrane, Western China

Science.gov (United States)

Mattinson, C. G.; Regel, M. E.; Zhang, J.

2014-12-01

In the southeastern North Qaidam terrane, near Dulan, felsic host gneisses enclose minor eclogite lenses. A small (~3°C/km) increase in temperatures to the west based on Zr-in-Rt thermometry is supported by a textural trend of zoned garnet with prograde mineral inclusions in the west to unzoned garnet with only peak-stage inclusions in the east. A western eclogite sample contains minor Ep and trace Phe in addition to Grt-Omp-Qtz-Rt; a strong foliation is defined by banding of Grt and Omp. Garnet Ca falls significantly from core (Alm44Prp23Grs32) to rim (Alm48Prp27Grs23). Phengite contains 3.34-3.36 Si pfu. Conventional Grt-Omp-Phe thermobarometry yields 23-27 kbar, 660-730°C, and Zr-in-Rt thermometry yields 671 ± 9°C (n = 37). An isochemical phase diagram (pseudosection) for the system NCKFMASHO calculated with PerpleX indicates that garnet Xgrs decreases with increasing P and T, suggesting that observed garnet zoning reflects prograde growth. Garnet rim compositional isopleths intersect at 23-27 kbar, 580-620°C, depending on choice of effective bulk composition and assumed Fe3+/Fetotal. Garnet rims help define the foliation, suggesting that these P-T conditions apply to this deformation. An eastern eclogite sample contains minor Ep and abundant, coarse-grained Phe in addition to Grt-Omp-Qtz-Rt; foliation is weak. Garnet zoning is weak; compositions are Alm41-43Prp26-28Grs29-32. Phengite cores contain 3.48-3.56 Si pfu. Conventional Grt-Omp-Phe thermobarometry yields 32-36 kbar, 700-750°C, and Zr-in-Rt thermometry yields 691 ± 12°C (n = 34). Conventional thermobarometry and pseudosections yield similar peak P-T conditions, but from different mineral compositions: thermobarometry yields peak P from high-Ca Grt, but the pseudosection yields peak P from intermediate-Ca Grt; maximum Ca in Grt is predicted at lower P and T. Pseudosection-based peak Ts are significantly lower than those from Zr-in-Rt and conventional thermometry. Wide isopleth spacing in the

UHP metamorphism recorded by kyanite-bearing eclogite in the Seve Nappe Complex of northern Jämtland, Swedish Caledonides

NARCIS (Netherlands)

Janák, M.; Van Roermund, H.; Majka, J.; Gee, D.

The first evidence for ultrahigh-pressure (UHP) metamorphism in the Seve Nappe Complex of the Scandinavian Caledonides is recorded by kyanite-bearing eclogite, found in a basic dyke within a garnet peridotite body exposed close to the lake Friningen in northern Jämtland (central Sweden). UHP

Insights into the mantle geochemistry of scandium from a meta-analysis of garnet data

Science.gov (United States)

Chassé, Mathieu; Griffin, William L.; Alard, Olivier; O'Reilly, Suzanne Y.; Calas, Georges

2018-06-01

The meta-analysis of about 13,000 analyses of scandium content in garnet grains shows that, below the spinel-garnet transition, this phase carries about three-quarters of the Sc budget of the mantle, indicating its control on Sc mobility. The Sc content of garnets in mafic rocks is low, due to a dilution effect resulting from their high modal content in garnet. Garnets from ultramafic rocks exhibit a wider range of Sc concentrations. We assess the relative influence of thermobarometry, crystal chemistry and fluid-related events on the distribution of Sc in garnet from such rocks to improve the tracking of geochemical processes in the mantle. Pressure and temperature of equilibration in the mantle are second-order factors influencing the Sc content of garnet, while crystal chemistry, in particular Cr/Cr+Al and Ca/Ca+Mg, is the main parameter controlling the compatibility of Sc. Scandium is incorporated in both X and Y sites of Cr-Ca-rich garnets, resulting in a behaviour intermediate between rare-earth elements, incorporated in the X site, and trivalent transition elements, occupying the Y site. This affinity for both sites results in a mild compatibility of Sc in the garnet stability field of the mantle; hence Sc concentration in garnet increases with melt extraction and can be reduced by silicate-melt metasomatism. In contrast, metasomatism by volatile-rich fluids increases the Sc concentration in garnet. The control of garnet on the compatibility of Sc in deep lithospheric rocks demonstrates the potential of using Sc to track the conditions of formation of magmas and their residual rocks, as well as the origin and nature of metasomatic fluids.

On fabrication procedures of Li-ion conducting garnets

Energy Technology Data Exchange (ETDEWEB)

Hanc, Emil [The Mineral and Energy Economy Research Institute, Polish Academy of Sciences, ul. Wybickiego 7, 31-261 Kraków (Poland); Zając, Wojciech, E-mail: wojciech.zajac@agh.edu.pl [AGH University of Science and Technology, Faculty of Energy and Fuels, al. Mickiewicza 30, 30-059 Kraków (Poland); Lu, Li; Yan, Binggong; Kotobuki, Masashi [Materials Science Group, Department of Mechanical Engineering, National University of Singapore (Singapore); Ziąbka, Magdalena [AGH University of Science and Technology, Faculty of Materials Science and Ceramics, al. Mickiewicza 30, 30-059 Kraków (Poland); Molenda, Janina [AGH University of Science and Technology, Faculty of Energy and Fuels, al. Mickiewicza 30, 30-059 Kraków (Poland)

2017-04-15

Ceramic oxides exhibiting high lithium-ion mobility at room temperature receive broad attention as candidate electrolytes for lithium batteries. Lithium-stuffed garnets from the Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} group seem to be especially promising because of their high ionic conductivity at room temperature and their electrochemical stability. In this work, we discuss factors that affect formation of the garnet in its bulk form or in the form of thick and thin films. We demonstrate that zinc oxide can be applied as a sintering aid that facilitate the formation of the highly conducting cubic Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} garnet phase in a single-step sintering procedure. Based on our experience with the single-step sintering experiments, we successfully fabricated a thick-film membrane consisting of a garnet solid electrolyte using the tape casting technique. In order to reduce the thickness of the electrolyte even further we investigated the fabrication of a thin-film Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} electrolyte by means of the pulsed laser deposition technique.

EXPLOITATION OF GRANITE BOULDER

Directory of Open Access Journals (Sweden)

Ivan Cotman

1994-12-01

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

Study of the provenance of Belgian Merovingian garnets by PIXE at IPNAS cyclotron

International Nuclear Information System (INIS)

Mathis, F.; Vrielynck, O.; Laclavetine, K.; Chene, G.; Strivay, D.

2008-01-01

Recent archaeological excavation in Belgium reveals one of the biggest Merovingian necropolis ever found in this country. This necropolis contains 436 tombs with a period of occupation of almost two centuries. Some of these tombs were very rich, especially two of them, and delivered an important funerary furniture. About 60 jewels inlaid with red garnets have been found, most of them of 'cloisonne' style (namely about 450 garnets). The new extracted beam set-up of the IPNAS cyclotron (University of Liege, Belgium) has been improved in order to analyse by PIXE these garnets and try to determine their provenance. These analyses reveal that the garnets found in the necropolis of Grez-Doiceau are very homogeneous in composition (almandine garnets) and are coming almost from a unique source. These results have been compared to previous studies led in France during these past five years. This permits to identify the source of almandine garnet situated in India and to highlight differences in garnet supply between France and Belgium in Merovingian times

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...

Petrography, Mineral Chemistry and Geothermobarometry of Andalusite- Bearing Schists North of Azna (Northern Sanandaj-Sirjan Zone, Iran

Directory of Open Access Journals (Sweden)

Karim Abdollahi Silabi

2016-07-01

deformation that hasproduced the current morphologyof the Sanandaj-Sirjan zone (Shabanian Borujeni, 2008. In this paper we focused on petrography and mineral chemistry and thermodynamic conditions of the metapelites. Materials and methods The chemical compositions of minerals were determined by a CAMECA SX100 electron microprobe (EMP at Universität Stuttgart (Germany. The instrument is equipped with five wavelength dispersive spectrometers. The beam current and acceleration voltage were 15 nA and 15 kV, respectively. v Discussion and Results The Azna regional metamorphic rocks include quartz-feldspar schists, mica schists, andalusite-bearing schists and quartzites. The Azna metapelites are schists, containing quartz, feldspars, andalusite, muscovite, biotite, muscovite, chlorite and garnet, in variable proportions, characterized byporphyroblastic and lepidoblastic textures. Based on mineralogy, minerals of these rocks contain andalusite, garnet, feldspar, muscovite, biotite, quartz and chlorite. Microprobe analyses show that the mineral compositions are as follows: White micas in the andalusite-bearing schists are muscovite, plagioclases are albite-oligoclase, garnets are almandine-spessartine with weak chemical zoning and biotites are siderophylite-annite. Based on geothermobarometry, these rocks formed in the hornblende-hornfels facies and the low pressure part of the amphibolite facies,with temperatures about 562-692 °C and pressures1.07-4.12 kbar. After the regional metamorphism of these rocks,granitoidintrusions causedthermal metamorphism of these rocks and the formation of andalusite-bearing schists. Acknowledgments The authors wish to thank the Office of Graduate Studies of the University of Isfahan for their support. We also thank Prof. Hans-JoachimMassonne, who played major roles during the microprobe analysis of minerals at the InstitutfürMineralogie und Kristallchemie, Universität Stuttgart (Germany. References Aghanabati, A., 2004. Geology of Iran. Geological

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

Microstructures and magnetic fabrics of the Ngaoundéré granite pluton (Cameroon): Implications to the late-Pan-African evolution of Central Cameroon Shear Zone

Science.gov (United States)

Dawaï, Daouda; Tchameni, Rigobert; Bascou, Jérome; Awe Wangmene, Salomon; Fosso Tchunte, Périclex Martial; Bouchez, Jean-Luc

2017-05-01

The Ngaoundéré granite pluton, in Central-North Cameroon, located near the Central Cameroon Shear zone (CCSZ), and previously studied for its petrography and geochemistry, is characterized by the absence of macroscopic markers of deformation. In this study, we report microstructures and magnetic fabrics (AMS) of this pluton and discuss the relationship with the Pan-African evolution of the CCSZ. The pluton consists of a porphyritic Hbl-Bt-monzogranite at its rim and a porphyritic biotite-granite at its core, a petrographic distribution denoting a normal zoning pattern, i.e. more silicic toward the centre. As expected, magnetic susceptibilities values also exhibit a zoning pattern in agreement with petrographic zonation. Thermomagnetic data indicate that this pluton is dominantly ferromagnetic in behaviour. As indicated by its microstructures, the pluton has suffered a continuum of deformation from the magmatic state to the high temperature solid-state during magma crystallization and solidification. The magnetic foliations dominantly strike NE-SW and dip moderately to steeply and the lineations mostly plunge shallowly to the NE or SW, roughly parallel to NE-to ENE-trending Central Cameroun Shear Zone (CCSZ). The foliation poles define a girdle pattern with a zone axis (52°/11°) rather close to the best line of the lineations (44°/21°). These fabrics correlate with the structures of the country rocks ascribed by several workers to a regional transpression. Toward the margins of the pluton, particularly the northern one, the lineations tend to rotate from NE to N in azimuth. This change is interpreted as due to strain partitioning, simple shearing with NE-SW extension being relayed by compression toward the northern pluton border. This new magnetic fabric study suggests that the Ngaoundéré pluton (poorly dated at c. 575 Ma) was emplaced during the late stages of the CCSZ dextral transpressive movement. It also provides some more constraints on the correlation

The Influence Of Hydrothermal Alteration And Weathering On Rock Magnetic Properties Of Granites From The Eps-1 Drilling (soultz-sous-forÊts / France)

Science.gov (United States)

Just, J.; Schleicher, A.; Kontny, A.; de Wall, H.

The EPS-1 drilling in Soultz-sous-Forêts (Rhinegraben, France) recovered a core pro- file of Tertiary to Permo-Mesozoic sediments deposited on a Variscan granitic base- ment. Magnetic susceptibility (k) measurements on the core material revealed a con- tinous increase from the basement/cover boundary (kmean 0.4 x 10-3 SI) into the magnetite-bearing granite (kmean 13 x 10-3 SI) over a depth range of 1417 U 1555 m. Rock magnetic and mineralogic studies were performed for the fresh granite, the hydrothermally altered granite near a fault zone and the altered granite from the fossil land surface near the basement/cover boundary. The decrease in susceptibility can be correlated with a gradual decomposition of magnetite to hematite and an alteration of the matrix minerals feldspars, biotite and hornblende to clay minerals and carbon- ates. Along with this transition, characteristic rock magnetic signatures can be dis- criminated for different degrees of alteration. While temperature-dependent magnetic susceptibility k(T)-curves in fresh granites indicate a typical multidomain magnetite course with good reversibility, different types of irreversible courses are observed for the altered granite. However, hematite could not be identified in the k(T)-curves. Al- tered granite shows relatively weak magnetic behaviour in AF-demagnetisation exper- iments, untypical for hematite. The alteration of the fresh granite also causes a change in magnetic fabric parameter, especially of the anisotropy factor. The magnetic min- eralogy from the altered granite in respect to the changes in rock magnetic properties will be discussed.

Shp2-Dependent ERK Signaling Is Essential for Induction of Bergmann Glia and Foliation of the Cerebellum

Science.gov (United States)

Li, Kairong; Leung, Alan W.; Guo, Qiuxia; Yang, Wentian

2014-01-01

Folding of the cortex and the persistence of radial glia (RG)-like cells called Bergmann glia (BG) are hallmarks of the mammalian cerebellum. Similar to basal RG in the embryonic neocortex, BG maintain only basal processes and continuously express neural stem cell markers. Past studies had focused on the function of BG in granule cell migration and how granule cell progenitors (GCP) regulate cerebellar foliation. The molecular control of BG generation and its role in cerebellar foliation are less understood. Here, we have analyzed the function of the protein tyrosine phosphatase Shp2 in mice by deleting its gene Ptpn11 in the entire cerebellum or selectively in the GCP lineage. Deleting Ptpn11 in the entire cerebellum by En1-cre blocks transformation of RG into BG but preserves other major cerebellar cell types. In the absence of BG, inward invagination of GCP persists but is uncoupled from the folding of the Purkinje cell layer and the basement membrane, leading to disorganized lamination and an absence of cerebellar folia. In contrast, removing Ptpn11 in the GCP lineage by Atoh1-cre has no effect on cerebellar development, indicating that Shp2 is not cell autonomously required in GCP. Furthermore, we demonstrate that Ptpn11 interacts with Fgf8 and is essential for ERK activation in RG and nascent BG. Finally, expressing constitutively active MEK1 rescues BG formation and cerebellar foliation in Shp2-deficient cerebella. Our results demonstrate an essential role of Shp2 in BG specification via fibroblast growth factor/extracellular signal-regulated protein kinase signaling, and reveal a crucial function of BG in organizing cerebellar foliation. PMID:24431450

High-coercive garnet films for thermo-magnetic recording

International Nuclear Information System (INIS)

Berzhansky, V N; Danishevskaya, Y V; Nedviga, A S; Milyukova, H T

2016-01-01

The possibility of using high-coercive of garnet films for thermo-magnetic recording is related with the presence of the metastable domain structure, which arises due to a significant mismatch of the lattice parameters of the film and the substrate. In the work the connection between facet crystal structure of elastically strained ferrite garnets films and the domain structure in them is established by methods of phase contrast and polarization microscopy. (paper)

Properties of Exchange Coupled All-garnet Magneto-Optic Thin Film Multilayer Structures

Science.gov (United States)

Nur-E-Alam, Mohammad; Vasiliev, Mikhail; Kotov, Viacheslav A.; Balabanov, Dmitry; Akimov, Ilya; Alameh, Kamal

2015-01-01

The effects of exchange coupling on magnetic switching properties of all-garnet multilayer thin film structures are investigated. All-garnet structures are fabricated by sandwiching a magneto-soft material of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 or Bi3Fe5O12:Dy2O3 in between two magneto-hard garnet material layers of composition type Bi2Dy1Fe4Ga1O12 or Bi2Dy1Fe4Ga1O12:Bi2O3. The fabricated RF magnetron sputtered exchange-coupled all-garnet multilayers demonstrate a very attractive combination of magnetic properties, and are of interest for emerging applications in optical sensors and isolators, ultrafast nanophotonics and magneto-plasmonics. An unconventional type of magnetic hysteresis behavior not observed previously in magnetic garnet thin films is reported and discussed. PMID:28788043

Properties of Exchange Coupled All-garnet Magneto-Optic Thin Film Multilayer Structures

Directory of Open Access Journals (Sweden)

Mohammad Nur-E-Alam

2015-04-01

Full Text Available The effects of exchange coupling on magnetic switching properties of all-garnet multilayer thin film structures are investigated. All-garnet structures are fabricated by sandwiching a magneto-soft material of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 or Bi3Fe5O12:Dy2O3 in between two magneto-hard garnet material layers of composition type Bi2Dy1Fe4Ga1O12 or Bi2Dy1Fe4Ga1O12:Bi2O3. The fabricated RF magnetron sputtered exchange-coupled all-garnet multilayers demonstrate a very attractive combination of magnetic properties, and are of interest for emerging applications in optical sensors and isolators, ultrafast nanophotonics and magneto-plasmonics. An unconventional type of magnetic hysteresis behavior not observed previously in magnetic garnet thin films is reported and discussed.

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

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

Science.gov (United States)

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

2016-11-01

At Vila Pouca de Aguiar area, northern Portugal, crops out a post-tectonic Variscan granite pluton, related with the Régua-Vila Real-Verín fault zone, comprising three types of biotite granites. Among these granites, PSG granite yield the highest average contents of U, probably due to its enrichment in accessory U-bearing minerals such as zircon. In the proximity of faults and joints, these granites are often affected by different degrees of hydrothermal alteration, forming reddish altered rocks, commonly known as "episyenites". These altered rocks are probably associated to the occurrence of hydrothermal processes, which led to uranium enrichment in the most advanced stages of episyenitization. In these granites, both average gamma absorbed dose rates in outdoor and indoor air are higher than those of the world average. Furthermore, even in the worst usage scenario, all these granites can be used as a building material, since their annual effective doses are similar to the limit defined by the European Commission. The geometric mean of radon activity of 91 dwellings located at the Vila Pouca de Aguiar pluton is 568Bqm(-3), exceeding that of other northern Portuguese granites. Measurements carried out during a winter season, indicate that 62.6% of the analysed dwellings yield higher indoor radon average values than the Portuguese legislation limit (400Bqm(-3)), and annual effective doses due higher than the world's average value (1.2mSvy(-1)). The interaction of geogenic, architectural and anthropogenic features is crucial to explain the variance in the geometric mean of radon activity of dwellings from Vila Pouca de Aguiar pluton, but the role of geologic faults is probably the most important decisive factor to increase the indoor radon concentration in dwellings. Hence, the development of awareness campaigns in order to inform population about the incurred radiological risks to radon exposure are highly recommended for this specific area. Copyright © 2016

Petrogenesis of the Baishan granite stock, Eastern Tianshan, NW China: Geodynamic setting and implications for potential mineralization

Science.gov (United States)

Cao, MingJian; Qin, KeZhang; Li, GuangMing; Evans, Noreen J.; McInnes, Brent I. A.; Lu, WeiWei; Deng, Gang

2017-11-01

Located in a region rich in Cu-Ni and Mo mineralization, the Baishan granitic stock is barren for reasons that remain enigmatic. Whole rock elemental and Sr-Nd isotope analysis, major element analysis of a number of minerals, and zircon trace element, U-Pb and Hf isotope analysis were undertaken in order to reveal the petrogenesis of the granites. All granites show typical I-type characteristics including metaluminous to slightly peraluminous, calc-alkaline signatures with a strong depletion of Nb, Ta, Ti and P, enrichment of light rare earth elements and large ion lithophile elements (e.g., Cs, Rb, Th, U, K). In addition, a strong depletion in Ti and P, highly fractionated light rare earth element patterns and less fractionated heavy rare earth element patterns, and negative correlations between SiO2 and TiO2, Al2O3, MgO, FeOT, P2O5, Zr and Hf suggest significant fractional crystallization of amphibole, apatite, zircon and Ti-bearing minerals. Whole rock Sr-Nd and zircon Hf isotopic compositions show wide variations with (87Sr/86Sr)i values of 0.70358 to 0.70505, εNd (t) of 3.8 to 7.2, and εHf (t) of 2.4 to 12.2 indicating derivation from partial melting of juvenile lower crust with obvious addition of ancient crust. Zircon U-Pb ages indicate a formation age of 292 Ma, significantly older than the ore-forming granite porphyry and slightly older than the regional mafic-ultramafic, A-type and diabase magmatism of Eastern Tianshan. The granite stocks were likely derived during heating of ascending asthenospheric mantle above a mantle plume in the Early Permian. Mineral chemistry, saturation thermometry, mineral species and whole rock Fe2O3/FeO ratios indicate a crystallization temperature of > 980 to 665 °C, pressure of 1.6 kbar and oxygen fugacity of ≤ NNO for the granite stock. Comparing the geochemistry, magma source and crystallization environment for the Early Permian barren granite and Late Triassic ore-related granite porphyry, the low ratios of Sr/Y and

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

Superposition de la tectonique éburnéenne et panafricaine dans les granitoïdes de la bordure nord du craton ouest africain, boutonniére de Zenaga, Anti-Atlas central, Maroc(Pan-african overprint on Eburnian granitoids at the northern boundary of the West African Craton, Zenaga Inlier, central Anti-Atlas, Morocco)

Science.gov (United States)

Ennih, N.; Laduron, D.; Greiling, R. O.; Errami, E.; de Wall, H.; Boutaleb, M.

2001-05-01

The Zenaga Inlier shows a comprehensive record of the Eburnian and Pan-African Orogenies. The Eburnian is characterised by high-temperature regional metamorphism and complex magmatism. The early (Azguemerzi) granodiorite has an isotopic mantle signature and was emplaced diapirically during the Eburnian Orogeny causing local thermal metamorphism. The foliation observed in this granitoid is a result of the interference between its primary syn-emplacement foliation and the regional foliation under amphibolite-facies conditions. The northern part of Zenaga has been intruded by the leucocratic granites of Tazenakht. These granites are cut by mylonites and phyllonites, corresponding to the Pan-African shear zones and accompanied with sub-greenschist-facies metamorphism during the Pan-African Orogeny. The deformation was the result of a regional sinistral transpressive event. This study in the northern part of the West African Craton shows the superposition of the Pan-African on the Eburnian Orogeny and the presence of a major fault in the Anti-Atlas.

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.)

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.)

The influence of the iron content on the reductive decomposition of A{sub 3−x}Fe{sub x}Al{sub 2}Si{sub 3}O{sub 12} garnets (A = Mg, Mn; 0.47 ≤ x ≤ 2.85)

Energy Technology Data Exchange (ETDEWEB)

Aparicio, Claudia, E-mail: claudia.aparicio@upol.cz; Filip, Jan, E-mail: claudia.aparicio@upol.cz; Mashlan, Miroslav, E-mail: claudia.aparicio@upol.cz; Zboril, Radek, E-mail: claudia.aparicio@upol.cz [Regional Centre of Advanced Technologies and Materials, Departments of Experimental Physics and Physical Chemistry, Faculty of Science, Palacky University, 17. listopadu 1192/12, 77146 Olomouc (Czech Republic)

2014-10-27

Thermally-induced reductive decomposition of natural iron-bearing garnets of the almandine-pyrope and almandine-spessartine series were studied at temperatures up to 1200 °C (heating rate of 10 °C/min) under atmosphere of forming gas (10% of H{sub 2} in N{sub 2}). Crystallochemical formula of the studied garnet was calculated as {sup VIII}(A{sub 3−x}Fe{sub x}{sup 2+}){sup VI}(Al,Fe{sup 3+}){sub 2}Si{sub 3}O{sub 12}, where the amount of Fe{sup 3+} in the octahedral sites is negligible with the exception of pyrope, A = Mg, Mn, and 0.47 ≤ x ≤ 2.85. The observed decomposition temperature, determined from differential scanning calorimetry and thermogravimetry, is greater than 1000 °C in all cases and showed almost linear dependence on the iron content in the dodecahedral sites of the studied garnets, with the exception of garnet with a near-pyrope composition (Prp{sub 80}Alm{sub 20}). The initial garnet samples and decomposition products were characterized in details by means of X-ray powder diffraction and {sup 57}Fe Mössbauer spectroscopy. We found that all studied garnets have common decomposition products such as metallic iron (in general, rounded particles below 4 μm) and Fe-spinel; the other identified decomposition products depend on starting chemical composition of the garnet: Fe-cordierite, olivine (fayalite or tephroite), cristobalite, pyroxene (enstatite or pigeonite), and anorthite. Anorthite and pigeonite were only present in garnets with Ca in the dodecahedral site. All the identified phases were usually well crystallized.

Two-mica granites of northeastern Nevada.

Science.gov (United States)

Lee, D.E.; Kistler, R.W.; Friedman, I.; Van Loenen, R. E.

1981-01-01

The field settings are described and analytical data are presented for six two-mica granites from NE Nevada. High delta 18O and 87Sr/86Sr values indicate that all are S-type granite, derived from continental crust. The major element chemistry and accessory mineral contents of these rocks also are characteristic of S-type granites. Chemical, X ray, and other data are presented for the micas recovered from these granites. The muscovites are notably high in Fe2O3, FeO, and MgO. Except for one hydrobiotite, each of the biotites has an MgO content near 6.0 wt%. Two different types of two-mica granites are recognized in the area of this study. One type is distinguished by the presence of many biotite euhedra within muscovite phenocrysts and by an unusual suite of accessory minerals completely devoid of opaque oxides. This type probably resulted from anatexis of late Precambrian argillites under conditions of relatively low oxygen fugacity, along a line that roughly coincides with the westward disappearance of continental basement. In the other textural type of two-mica granite the micas are equigranular and there is a greater variety of accessory minerals. The magmatic evolution of this type also appears to reflect the influence of late Precambrian argillites; there may be age differences between the two types of two-mica granites.-Author

Anomalously low strength of serpentinite sheared against granite and implications for creep on the Hayward and Calaveras Faults

Science.gov (United States)

Moore, Diane E.; Lockner, David A.; Ponce, David A.

2010-01-01

Serpentinized ophiolitic rocks are juxtaposed against quartzofeldspathic rocks at depth across considerable portions of the Hayward and Calaveras Faults. The marked compositional contrast between these rock types may contribute to fault creep that has been observed along these faults. To investigate this possibility, we are conducting hydrothermal shearing experiments to look for changes in frictional properties resulting from the shear of ultramafic rock juxtaposed against quartzose rock units. In this paper we report the first results in this effort: shear of bare-rock surfaces of serpentinite and granite, and shear of antigorite-serpentinite gouge between forcing blocks of granitic rock. All experiments were conducted at 250°C. Serpentinite sheared against granite at 50 MPa pore-fluid pressure is weaker than either rock type separately, and the weakening is significantly more pronounced at lower shearing rates. In contrast, serpentinite gouge sheared dry between granite blocks is as strong as the bare granite surface. We propose that the weakening is the result of a solution-transfer process involving the dissolution of serpentine minerals at grain-to-grain contacts. Dissolution of serpentine is enhanced by modifications to pore-fluid chemistry caused by interaction of the fluid with the quartz-bearing rocks. The compositional differences between serpentinized ultramafic rocks of the Coast Range Ophiolite and quartzofeldspathic rock units such as those of the Franciscan Complex may provide the mechanism for aseismic slip (creep) in the shallow crust along the Hayward, Calaveras, and other creeping faults in central and northern California.

Intensive low-temperature tectono-hydrothermal overprint of peraluminous rare-metal granite: a case study from the Dlhá dolina valley (Gemericum, Slovakia

Directory of Open Access Journals (Sweden)

Breiter Karel

2015-02-01

Full Text Available A unique case of low-temperature metamorphic (hydrothermal overprint of peraluminous, highly evolved rare-metal S-type granite is described. The hidden Dlhá dolina granite pluton of Permian age (Western Carpathians, eastern Slovakia is composed of barren biotite granite, mineralized Li-mica granite and albitite. Based on whole-rock chemical data and evaluation of compositional variations of rock-forming and accessory minerals (Rb-P-enriched K-feldspar and albite; biotite, zinnwaldite and di-octahedral micas; Hf-(Sc-rich zircon, fluorapatite, topaz, schorlitic tourmaline, the following evolutionary scenario is proposed: (1 Intrusion of evolved peraluminous melt enriched in Li, B, P, F, Sn, Nb, Ta, and W took place followed by intrusion of a large body of biotite granites into Paleozoic metapelites and metarhyolite tuffs; (2 The highly evolved melt differentiated in situ forming tourmaline-bearing Li-biotite granite at the bottom, topaz-zinnwaldite granite in the middle, and quartz albitite to albitite at the top of the cupola. The main part of the Sn, Nb, and Ta crystallized from the melt as disseminated cassiterite and Nb-Ta oxide minerals within the albitite, while disseminated wolframite appears mainly within the topaz-zinnwaldite granite. The fluid separated from the last portion of crystallized magma caused small scale greisenization of the albitite; (3 Alpine (Cretaceous thrusting strongly tectonized and mylonitized the upper part of the pluton. Hydrothermal low-temperature fluids enriched in Ca, Mg, and CO2 unfiltered mechanically damaged granite. This fluid-driven overprint caused formation of carbonate veinlets, alteration and release of phosphorus from crystal lattice of feldspars and Li from micas, precipitating secondary Sr-enriched apatite and Mg-rich micas. Consequently, all bulk-rock and mineral markers were reset and now represent the P-T conditions of the Alpine overprint.

Intensive low-temperature tectono-hydrothermal overprint of peraluminous rare-metal granite: a case study from the Dlhá dolina valley (Gemericum, Slovakia)

Science.gov (United States)

Breiter, Karel; Broska, Igor; Uher, Pavel

2015-02-01

A unique case of low-temperature metamorphic (hydrothermal) overprint of peraluminous, highly evolved rare-metal S-type granite is described. The hidden Dlhá dolina granite pluton of Permian age (Western Carpathians, eastern Slovakia) is composed of barren biotite granite, mineralized Li-mica granite and albitite. Based on whole-rock chemical data and evaluation of compositional variations of rock-forming and accessory minerals (Rb-P-enriched K-feldspar and albite; biotite, zinnwaldite and di-octahedral micas; Hf-(Sc)-rich zircon, fluorapatite, topaz, schorlitic tourmaline), the following evolutionary scenario is proposed: (1) Intrusion of evolved peraluminous melt enriched in Li, B, P, F, Sn, Nb, Ta, and W took place followed by intrusion of a large body of biotite granites into Paleozoic metapelites and metarhyolite tuffs; (2) The highly evolved melt differentiated in situ forming tourmaline-bearing Li-biotite granite at the bottom, topaz-zinnwaldite granite in the middle, and quartz albitite to albitite at the top of the cupola. The main part of the Sn, Nb, and Ta crystallized from the melt as disseminated cassiterite and Nb-Ta oxide minerals within the albitite, while disseminated wolframite appears mainly within the topaz-zinnwaldite granite. The fluid separated from the last portion of crystallized magma caused small scale greisenization of the albitite; (3) Alpine (Cretaceous) thrusting strongly tectonized and mylonitized the upper part of the pluton. Hydrothermal low-temperature fluids enriched in Ca, Mg, and CO2 unfiltered mechanically damaged granite. This fluid-driven overprint caused formation of carbonate veinlets, alteration and release of phosphorus from crystal lattice of feldspars and Li from micas, precipitating secondary Sr-enriched apatite and Mg-rich micas. Consequently, all bulk-rock and mineral markers were reset and now represent the P-T conditions of the Alpine overprint.

Attachment study of Agrobacterium tumefaciens to yam spp

African Journals Online (AJOL)

Charles S.Wortmann

of microcontinents. Key words/phrases: Accretion, cratonisation, isotope systems, subduction, ... N-S striking structures dominate Pan-African tectonics, although ... (a) Foliation trends, shear sense and brittle faults in the Gore-Gambella area; heavy .... intergrown sillimanite, quartz and plagioclase (Plate 1F), and large garnet.

High density Gd-substituted yttrium iron garnets by coprecipitation

International Nuclear Information System (INIS)

Lamastra, Francesca Romana; Bianco, Alessandra; Leonardi, Federica; Montesperelli, Giampiero; Nanni, Francesca; Gusmano, Gualtiero

2008-01-01

Gadolinium-substituted yttrium iron garnets are ferrite materials of primary importance in microwave engineering. Stoichiometric powders of nominal composition Y 2.6 Gd 0.4 Fe 5 O 12 (i.e. Fe/(Y + Gd) = 1.67) were prepared by reverse strike coprecipitation of metal nitrates. In order to investigate the influence of composition on phase formation, non-stoichiometric powders were also synthesised. On the basis of DTA/TGA analysis, dried coprecipitates were calcined between 600 deg. C and 1200 deg. C and then characterised by ICP, XRD and HT-XRD. Amorphous coprecipitates crystallise around 700 deg. C in cubic garnet phase along with small amounts of YFeO 3 and/or α-Fe 2 O 3 . Only iron-rich garnets, either pure or Gd-substituted, calcined at 1200 deg. C or above display a single-phase cubic garnet. According to thermal dilatometry results, calcined powders were sintered in air up to 1470 deg. C. The microstructure of sintered ceramics is made up of fine grains, the average size ranging between 3 μm and 13 μm. Density of sintered bodies ranged from 88% to 98%. Ferromagnetic resonance linewidth (ΔH -3dB ) ranged between 4352.9 A m -1 and 4392.7 A m -1 , depending on composition and microstructure

Fracture hydrology relevant to radionuclide transport. Field work in a granite formation in Cornwall

International Nuclear Information System (INIS)

Bourke, P.J.; Hodgkinson, D.P.; Durrance, E.M.; Heath, M.J.

1985-01-01

Separation, orientation, apertures and intersections of water-bearing fractures are the variables which control water flow and affect radionuclide transport through fractured rocks. The need is discussed for information on the distribution of these variables in statistical treatments of flow and transport, because of the inadequacy of permeability and porosity data in continuum treatments. Satisfactory methods of measuring distributions of separation, orientation and apetures have been developed and data for Cornish granite are presented. An estimate of the average distance between fracture intersections is made

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

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)

Formation of atoll garnets in the UHP eclogites of the Tso Morari Complex, Ladakh, Himalaya

Science.gov (United States)

Jonnalagadda, Mallika K.; Karmalkar, Nitin R.; Duraiswami, Raymond A.; Harshe, Shivani; Gain, Sarah; Griffin, William L.

2017-12-01

The eclogites of the Tso Morari Complex, Ladakh, NW Himalayas preserve both garnets with spectacular atoll textures, as well as whole porphyroblastic garnets. Whole garnets are euhedral, idiomorphic and enclose inclusions of amphibole, phengite and zoisite within the cores, and omphacite and quartz/coesite towards the rims. Detailed electron microprobe analyses and back-scattered electron images show well-preserved prograde zoning in the whole garnets with an increase in Mg and decrease in Ca and Mn contents from the core to the rim. The atoll garnets commonly consist of euhedral ring over island/peninsular core containing inclusions of phengite, omphacite and rarely amphibole between the core and ring. Compositional profiles across the studied atoll grains show elemental variations with higher concentrations of Ca and Mn with low Mg at the peninsula/island cores; contrary to this low Ca, Mn and high Mg is observed at the outer rings. Temperature estimates yield higher values at the Mg-rich atoll garnet outer rings compared to the atoll cores. Atoll garnet formation was favoured by infiltration of fluid formed due to breakdown of hydrous phases, and/or the release of structurally bounded OH from nominally anhydrous minerals at the onset of exhumation. Infiltration of fluids along pre-existing fracture pathways and along mineral inclusion boundaries triggered breakdown of the original garnet cores and released elements which were subsequently incorporated into the newly-grown garnet rings. This breakdown of garnet cores and inward re-growth at the outer ring produced the atoll structure. Calibrated geo-thermobarometers and mineral equilibria reflect that the Tso Morari eclogites attain peak pressures prior to peak temperatures representing a clockwise path of evolution.

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 the anatexis of continental crust or processes occurring at a much greater depth. They commonly show enrichment 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. (author)

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)

The research frontier and beyond: granitic terrains

Science.gov (United States)

Twidale, C. R.

1993-07-01

Investigations of granite forms and landscapes over the past two centuries suggest that many features, major and minor, are shaped by fracture-controlled subsurface weathering, and particularly moisture-driven alteration: in other words etch forms are especially well represented in granitic terrains. Commonly referred to as two stage forms, many are in reality multistage in origin, for the structural contrasts exploited by weathering and erosion that are essential to the mechanism originated as magmatic, thermal or tectonic events in the distant geological past. Fracture patterns are critical to landform and landscape development in granitic terrains, but other structural factors also come into play. Location with respect to water table and moisture contact are also important. Once exposed and comparatively dry, granite forms tend to stability; they are developed and diversified, and many are gradually destroyed as new, epigene, forms evolve, but many granite forms persist over long ages. Reinforcement effects frequently play a part in landform development. Several granite forms are convergent, i.e. features of similar morphology evolve under the influence of different processes, frequently in contrasted environments. On the other hand many landforms considered to be typical of granitic terrains are also developed in bedrock that is petrologically different but physically similar to granite; and in particular is subdivided by fractures of similar pattern and density. To date, most of the general statements concerning the evolution of granitic terrains have been based in work in the tropics but other climatic settings, and notably those of cold land, are now yielding significant results. Future research will extend and develop these avenues, but biotic factors, and particularly the role of bacteria, in such areas as weathering, will take on a new importance. Structural variations inherited from the magnetic, thermal and tectonic events to which granite bodies have

Identification of granite varieties from colour spectrum data.

Science.gov (United States)

Araújo, María; Martínez, Javier; Ordóñez, Celestino; Vilán, José Antonio

2010-01-01

The granite processing sector of the northwest of Spain handles many varieties of granite with specific technical and aesthetic properties that command different prices in the natural stone market. Hence, correct granite identification and classification from the outset of processing to the end-product stage optimizes the management and control of stocks of granite slabs and tiles and facilitates the operation of traceability systems. We describe a methodology for automatically identifying granite varieties by processing spectral information captured by a spectrophotometer at various stages of processing using functional machine learning techniques.

Tibetan garnet records early Eocene initiation of thickening in the Himalaya

DEFF Research Database (Denmark)

Smit, Matthijs Arjen; Hacker, Bradley; Lee, Jeffrey

2014-01-01

Tectonic reconstructions of the Himalayan orogeny depend on the age at which crustal thickening commenced. To investigate this age, we analyzed garnet from middle crustal rocks exposed in the north Himalayan Mabja and Kangmar gneiss domes of Tibet using Lu-Hf geochronology. Garnet yielded Lu-Hf a...

On the C*-algebras of foliations in the plane

CERN Document Server

Wang, Xiaolu

1987-01-01

The main result of this original research monograph is the classification of C*-algebras of ordinary foliations of the plane in terms of a class of -trees. It reveals a close connection between some most recent developments in modern analysis and low-dimensional topology. It introduces noncommutative CW-complexes (as the global fibred products of C*-algebras), among other things, which adds a new aspect to the fast-growing field of noncommutative topology and geometry. The reader is only required to know basic functional analysis. However, some knowledge of topology and dynamical systems will be helpful. The book addresses graduate students and experts in the area of analysis, dynamical systems and topology.

Energy Evolution Mechanism and Confining Pressure Effect of Granite under Triaxial Loading-Unloading Cycles

Science.gov (United States)

Wang, Hao; Miao, Sheng-jun

2018-05-01

Rock mass undergoes some deformational failure under the action of external loads, a process known to be associated with energy dissipation and release. A triaxial loading-unloading cycle test was conducted on granite in order to investigate the energy evolution pattern of rock mass under the action of external loads. The study results demonstrated: (1) The stress peaks increased by 50% and 22% respectively and the pre-peak weakening became more apparent in the ascending process of the confining pressure from 10MPa to 30MPa; the area enclosed by the hysteresis loop corresponding to 30MPa diminished by nearly 60% than that corresponding to 10MPa, indicating a higher confining pressure prohibits rock mass from plastic deformation and shifts strain toward elastic deformation. (2) In the vicinity of the strength limit, the slope of dissipation energy increased to 1.6 from the original 0.7 and the dissipation energy grew at an accelerating rate, demonstrating stronger propagation and convergence of internal cracks. (3) At a pressure of 70% of the stress peak, the elastic energy of the granite accounted for 88% of its peak value, suggesting the rock mechanical energy from the outside mostly changes into the elastic energy inside the rock, with little energy loss.(4) Prior to test specimen failure, the axial bearing capacity dropped with a decreasing confining pressure in an essentially linear way, and the existence of confirming pressure played a role in stabilizing the axial bearing capacity.

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2010-06-15

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

Elastic properties and seismic anisotropy of the Seve Nappe Complex - Laboratory core measurements from the International Continental Drilling Project COSC-1 well, Åre, Sweden

Science.gov (United States)

Wenning, Q. C.; Almqvist, B. S. G.; Zappone, A. S.

2015-12-01

The COSC-1 scientific borehole was drilled in the summer of 2014 to ~2.5 km depth to study the structure and composition of the Middle Allochthon of the Central Scandinavian Caledonides. It crosscuts the amphibolite-grade lower part of the Seve nappe and intersects a mylonite zone in the lower 800 m of the borehole. We selected six core samples representing the primary lithologies in the COSC-1 borehole for laboratory investigation of elastic properties. The cores consisted of two amphibolites with differing grain sizes, a calc-silicate gneiss, a felsic gneiss, a coarse grained amphibole bearing gneiss, and a garnet bearing mylonitic schist from the basal shear zone. Both P- and S-waves were measured at ultrasonic frequency (1 MHz), and room temperature hydrostatic pressure conditions up to 260 MPa. Measurements were made along three mutually perpendicular directions, one perpendicular to foliation and two parallel to the foliation with one aligned with mineral lineation. Vp and Vs, anisotropy, and elastic properties are reported as an extrapolation of the high-pressure portion of the ultrasonic measurements back to the intersection with the zero pressure axis. The Vp and Vs in the direction perpendicular to foliation ranges from 5.51-6.67 km/s and 3.18-4.13 km/s, respectively. In the direction parallel to foliation the Vp and Vs ranges from 6.31-7.25 km/s and 3.52-4.35 km/s, respectively. Vp anisotropy ranges from 3% in the calc-silicate gneiss to 18% in mylonitic schist. Acoustic impedance estimations at lithostatic pressure conditions at base of the borehole (70 MPa) show that acoustic impedance contrast generating reflection coefficients between the basal shear zone and overlying units are significant enough to cause seismic reflections. Above the mylonite zone/shear zone, the reflectivity within the lower Seve nappe is due to the impedance contrast between the felsic gneiss and the amphibolite. This result fits with 3D seismic reflection imaging in the area of

Garnet Yield Strength at High Pressures and Implications for Upper Mantle and Transition Zone Rheology

International Nuclear Information System (INIS)

Kavner, A.

2008-01-01

Garnet helps control the mechanical behavior of the Earth's crust, mantle, and transition zone. Here, measurements are presented suggesting that garnet, long considered to be a high-viscosity phase, is actually weaker than the other dominant components in the transition zone. The mechanical behavior of garnet at high pressures was examined using radial diffraction techniques in the diamond anvil cell. The yield strength of grossular garnet was inferred from synchrotron X-ray measurements of differential lattice strains. The differential stress was found to increase from 1.3 (±0.6) GPa at a hydrostatic pressure 5.8 (±1.1) GPa to 4.1 (±0.4) GPa at 15.7 (±1.0) GPa, where it was level to 19 GPa. The strength results are consistent with inferred strength values for majorite garnet from measurements in the diamond cell normal geometry, bolstering the idea that garnet-structured materials may all have similar strengths. In this low-temperature, high differential stress regime, garnet is shown to be significantly weaker than anhydrous ringwoodite and to have a strength similar to hydrous ringwoodite. This result suggests that the presence of water in the transition zone may not be required to explain a weak rheology, and therefore models of transition zone behavior built assuming that garnet is the high-strength phase may need to be revised.

Radiometric analysis of Chinese commercial granites

International Nuclear Information System (INIS)

Xinwei, L.; Lingqing, W.; Xiaodan, J.

2006-01-01

Due to the widespread use of granites as building and ornamental materials, measurements of 226 Ra, 232 Th and 40 K activities in commercial granites have been carried out using a NaI(Tl) γ-ray spectrometer with a matrix-inversion-based spectral stripping technique. The concentrations of 226 Ra, 232 Th and 40 K in Chinese commercial granite range from 14.5 to 204.7 Bq x kg -1 , 16.7 to 186.7 Bq x kg -1 and 185.7 to 1745.6 Bq x kg -1 , respectively. The mean values of the activity concentrations of 226 Ra, 232 Th and 40 K in red and pink commercial granites are all higher than those in black and gray commercial ones. The radium equivalent activity (Ra eq ), the external hazard index (H ex ), the internal hazard index (H in ) and the annual gonadal dose equivalent (AGDE) were also calculated and compared to the international recommended values. Six types of red commercial granites (CBR, MLR, QXR, PBR, JXR, LQR, YDR and TSR) of China do not satisfy the universal standards. (author)

Nd:YVO4 laser removal of graffiti from granite. Influence of paint and rock properties on cleaning efficacy

International Nuclear Information System (INIS)

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

2012-01-01

Highlights: ► Cleaning using NdYVO 4 laser at 355 nm of four different graffiti colours applied on granites. ► Analysis of the influence of paint composition and properties of rocks on the process. ► Composition of the paints and, in turn reflectance, determine the removal effectiveness. ► The laser removal is not conditioned by properties of the stones. - Abstract: This paper presents the cleaning efficiency results for four differently coloured graffiti paints applied to two types of granitic stone by Nd:YVO 4 laser at 355 nm. The paints were characterized in terms of mineralogy and chemistry using x-ray fluorescence, X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM); paint absorbance in the ultraviolet–visible-infrared range (200–2000 nm) was also assessed. The studied granites had different mineralogy, texture and porosity properties. Cleaning efficiency was evaluated by polarized microscopy, SEM, FTIR spectroscopy and spectrophotometer colour measurements. The results indicate differences in the effectiveness of surface cleaning for the blue, red and black paints as opposed to the silver paint, mainly attributed to chemical composition. No evidence was found that the granite properties had a bearing on laser effectiveness, although the degree, type and spatial distribution of transgranular fissures in the stone affected the overall assessment of cleaning effectiveness. Polarized light microscopy observations and colour measurements showed that the intensity and distribution of fissures affect the depth of paint penetration, ultimately affecting the cleaning efficiency for both granites.

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

Science.gov (United States)

Breiter, K.; Ďurišová, J.; Hrstka, T.; Korbelová, Z.; Vašinová Galiová, M.; Müller, A.; Simons, B.; Shail, R. K.; Williamson, B. J.; Davies, J. A.

2018-03-01

The genetic relationship between a granite pluton and adjacent complex of rare-metal pegmatite-aplite-banded sheets (Megiliggar Sheet Complex - MSC) has been studied at the border of the Tregonning topaz granite at Megiliggar Rocks, Cornwall, SW England. Similarities in whole-rock chemical and mineralogical compositions, together with a gradual change in textures away from the granite margin, provide strong evidence for a genetic link between the Tregonning Granite and MSC. The sheets are likely to represent apophyses of residual melt which escaped from the largely crystallized roof of the granite pluton. The escaping melt was peraluminous, had a composition near the F, B, Li slightly enriched granite minimum, and, in comparison with other Cornish granites, was enriched in F, Li, Rb, Cs, Sn, W, Nb, Ta, and U, and depleted in Fe, Mg, Ca, Sr, Th, Zr, and REE. With increasing distance from the Tregonning Granite, the silicate melt crystallized as homogeneous leucogranite sheets and banded complex sheets (i.e. combinations of bands with granitic, aplitic and pegmatitic textures), then layered aplite-pegmatites; this sequence becoming progressively more depleted in the fluxing and volatile elements F, Li, Rb, and Cs, but showing no change in Zr/Hf ratios. The fixed Zr/Hf ratio is interpreted as indicating a direct genetic link (parental melt) between all rock types, however the melt progressively lost fluxing and volatile elements with distance from the granite pluton, probably due to wall-rock reaction or fluid exsolution and migration via fractures. Differentiation of the primary melt into Na-Li-F-rich and separate K-B-rich domains was the dominant chemical process responsible for the textural and mineral diversity of the MSC. On a large (cliff-section) scale, the proximal Na-Li-F-rich leucogranite passes through complex sheets into K-B-rich aplite-pegmatites, whilst at a smaller (<1 m) scale, the K-B-rich bands are interspersed (largely overlain) by Na

Ce3+-Doped garnet phosphors : Composition modification, luminescence properties and applications

NARCIS (Netherlands)

Xia, Zhiguo; Meijerink, Andries

2017-01-01

Garnets have the general formula of A3B2C3O12 and form a wide range of inorganic compounds, occurring both naturally (gemstones) and synthetically. Their physical and chemical properties are closely related to the structure and composition. In particular, Ce3+-doped garnet phosphors have a long

Geologic Map of the Estes Park 30' x 60' Quadrangle, North-Central Colorado

Science.gov (United States)

Cole, James C.; Braddock, William A.

2009-01-01

The rocks and landforms of the Estes Park 30 x 60 minute quadrangle display an exceptionally complete record of geologic history in the northern Front Range of Colorado. The Proterozoic basement rocks exposed in the core of the range preserve evidence of Paleoproterozoic marine sedimentation, volcanism, and regional soft-sediment deformation, followed by regional folding and gradational metamorphism. The metasedimentary rocks of the Estes Park quadrangle are distinct within northern Colorado for preserving the complete metamorphic zonation from low-grade chlorite-muscovite phyllites, through middle greenschist-grade rocks with sequential aluminous porphyroblasts, to partially melted gneisses that contain high-grade cordierite and garnet in the non-melted residues. Regional and textural evidence shows that the widespread metamorphism was essentially concurrent with intrusion of the Boulder Creek Granodiorite and related magmas and with the peak of deformation in the partially melted high-grade rocks. The metamorphic thermal pulse arrived later following the peak of deformation in the physically higher, cooler, low-grade terrane. Mesoproterozoic time was marked by intrusion of biotite granite in the Longs Peak-St Vrain batholith, a complex, irregular body that occupies nearly half of the core of the Front Range in this quadrangle. The magma was dry and viscous as it invaded the metamorphic rocks and caused wholesale plastic folding of the wall rock structure. Steep metamorphic foliation that resulted from the Paleoproterozoic deformations was bowed upward and re-oriented into flat-lying attitudes as the crystal-rich magma rose buoyantly and spread out in the middle crust. Magma invaded the schists and gneisses along weak foliation planes and produced a characteristic sill-upon-sill intrusive fabric, particularly in the higher parts of the batholith. Broad, open arches and swales that are defined by the flow-aligned feldspar foliation of the granite, as well as by

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.

Controls on fault zone structure and brittle fracturing in the foliated hanging wall of the Alpine Fault

Science.gov (United States)

Williams, Jack N.; Toy, Virginia G.; Massiot, Cécile; McNamara, David D.; Smith, Steven A. F.; Mills, Steven

2018-04-01

Three datasets are used to quantify fracture density, orientation, and fill in the foliated hanging wall of the Alpine Fault: (1) X-ray computed tomography (CT) images of drill core collected within 25 m of its principal slip zones (PSZs) during the first phase of the Deep Fault Drilling Project that were reoriented with respect to borehole televiewer images, (2) field measurements from creek sections up to 500 m from the PSZs, and (3) CT images of oriented drill core collected during the Amethyst Hydro Project at distances of ˜ 0.7-2 km from the PSZs. Results show that within 160 m of the PSZs in foliated cataclasites and ultramylonites, gouge-filled fractures exhibit a wide range of orientations. At these distances, fractures are interpreted to have formed at relatively high confining pressures and/or in rocks that had a weak mechanical anisotropy. Conversely, at distances greater than 160 m from the PSZs, fractures are typically open and subparallel to the mylonitic or schistose foliation, implying that fracturing occurred at low confining pressures and/or in rocks that were mechanically anisotropic. Fracture density is similar across the ˜ 500 m width of the field transects. By combining our datasets with measurements of permeability and seismic velocity around the Alpine Fault, we further develop the hierarchical model for hanging-wall damage structure that was proposed by Townend et al. (2017). The wider zone of foliation-parallel fractures represents an outer damage zone that forms at shallow depths. The distinct inner damage zone. This zone is interpreted to extend towards the base of the seismogenic crust given that its width is comparable to (1) the Alpine Fault low-velocity zone detected by fault zone guided waves and (2) damage zones reported from other exhumed large-displacement faults. In summary, a narrow zone of fracturing at the base of the Alpine Fault's hanging-wall seismogenic crust is anticipated to widen at shallow depths, which is

Fracture patterns and stresses in granite

International Nuclear Information System (INIS)

Price, N.J.

1979-01-01

If granite bodies are to be used as receptacles for toxic waste materials, the presence or absence of barren fractures and the virgin stresses in the granite are of fundamental importance. Unfortunately, very little is known regarding the incidence of fractures, or stresses, which exist at depths (of about 1 km) in granite bodies. A simple analysis is presented of a hypothetical intrusion which indicates the magnitudes of stresses and the possible fracture development which may be expected in such bodies. (auth)

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

Rare metal granites and related rocks of the Ukrainian shield

Directory of Open Access Journals (Sweden)

Esipchuk, K.Ye.

1993-12-01

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

D/H variations of granitoids and of their OH--bearing minerals

International Nuclear Information System (INIS)

Boettger, T.; Stiehl, G.; Wand, U.

1987-01-01

Granitic rocks from the Thueringer Hauptgranit Massif (THM) and the western Lausitzer Granodiorit Massif (GDR) have been analyzed for their hydrogen isotope composition (D/H) and water content. Some whole-rock samples especially from the THM as well as the OH - bearing minerals (mica, hornblende) separated from them yielded extremely high D/H ratios. An attempt is made to explain this anomalous deuterium enrichment. (author)

Lithium Behavior during Growth of Metasedimentary Garnets from the Cignana UHP Locality, Italy

Science.gov (United States)

Bebout, G. E.; Tsujimori, T.; Ota, T.; Shimaki, Y.; Kunihiro, T.; Carlson, W. D.; Nakamura, E.

2014-12-01

We investigated major and trace element concentrations and δ7Li in garnets in Lago di Cignana metasedimentary rocks (peak conditions ~550˚C, 2.5-3.0 GPa), following the EPMA-SIMS approach of Tsujimori et al. (2014; IMA conference abstract). Previous work on the devolatilization history of these rocks (Bebout et al., 2013; Cook-Kollars et al., 2014; both in Chemical Geology) provides a petrologic and geochemical context for this study. Lithium is of interest as a tracer of fluid-rock interactions and because of its potential to isotopically fractionate during diffusional processes. All garnets are almandine-rich with strongly decreasing MnO and increasing MgO toward rims. HREEs, Y, and Li also show strong zoning, with elevated concentrations in cores (15-50 ppm Li) and marked high-concentration anomalies (up to 117 ppm Li, 5500 ppm Y), with little or no major element shift, as growth annuli at which some garnets have elevated δ7Li. In all garnets, rutile inclusions appear abruptly at annuli and outward toward rims, accompanied by inclusions of a Ca- and LREE-rich phase and decreased Nb concentrations in garnet. These relationships appear to reflect prograde garnet-forming reaction(s) that in part involved titanite breakdown to stabilize rutile, which resulted in delivery of more abundant Y and HREEs at surfaces of growing garnets to produce growth annuli. The co-enrichment of Li and Y+REEs is attributed to their mutual incorporation via a charge-coupled substitution (Carlson et al., 2014; American Mineralogist); thus the increased Li uptake is a passive consequence of the elevated concentrations of Y+REEs. Distributions of δ7Li are complex, with most garnets showing only subtle core-to-rim variation other than at Y+REE annuli. At annuli, some garnets display elevated δ7Li (by up to 8‰), while others in the same rock do not. Small-scale fluctuations in δ7Li may correlate with abrupt shifts in major and trace element concentrations, suggesting that changes in

(South- ern-Cameroon): Evidence for Pan-African thrust tectonic

African Journals Online (AJOL)

2010-04-28

Apr 28, 2010 ... field geological mapping and petro-structural analyses .... + Gr + Kfs; garnet occurs as rounded porphyroblast wrapped around by the main foliation; (b) Photograph of a ..... (c) Eye structures (sheath folds) induced by C2 flat lying shear planes); .... obtained by application of Grt-Bt thermometer (Ferry.

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)

Study of Y and Lu iron garnets using Bethe-Peierls-Weiss method

Science.gov (United States)

Goveas, Neena; Mukhopadhyay, G.; Mukhopadhyay, P.

1994-11-01

We study here the magnetic properties of Y- and Lu- Iron Garnets using the Bethe- Peierls-Weiss method modified to suit complex systems like these Garnets. We consider these Garnets as described by Heisenberg Hamiltonian with two sublattices (a,d) and determine the exchange interaction parameters Jad, Jaa and Jdd by matching the exerimental susceptibility curves. We find Jaa and Jdd to be much smaller than those determined by Néel theory, and consistent with those obtained by the study of spin wave spectra; the spin wave dispersion relation constant obtained using these parameters gives good agreement with the experimental values.

Nd:YVO{sub 4} laser removal of graffiti from granite. Influence of paint and rock properties on cleaning efficacy

Energy Technology Data Exchange (ETDEWEB)

Rivas, T., E-mail: trivas@uvigo.es [Dpto. Ingenieria de los Recursos Naturales y Medio Ambiente. Universidad de Vigo, Lagoas-Marcosende s/n, 36310 Vigo (Spain); Pozo, S. [Dpto. Ingenieria de los Recursos Naturales y Medio Ambiente. Universidad de Vigo, Lagoas-Marcosende s/n, 36310 Vigo (Spain); Fiorucci, M.P.; Lopez, A.J.; Ramil, A. [Centro de Investigacions Tecnoloxicas (CIT), Universidade da Coruna, 15403 Ferrol (Spain)

2012-12-15

Highlights: Black-Right-Pointing-Pointer Cleaning using NdYVO{sub 4} laser at 355 nm of four different graffiti colours applied on granites. Black-Right-Pointing-Pointer Analysis of the influence of paint composition and properties of rocks on the process. Black-Right-Pointing-Pointer Composition of the paints and, in turn reflectance, determine the removal effectiveness. Black-Right-Pointing-Pointer The laser removal is not conditioned by properties of the stones. - Abstract: This paper presents the cleaning efficiency results for four differently coloured graffiti paints applied to two types of granitic stone by Nd:YVO{sub 4} laser at 355 nm. The paints were characterized in terms of mineralogy and chemistry using x-ray fluorescence, X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM); paint absorbance in the ultraviolet-visible-infrared range (200-2000 nm) was also assessed. The studied granites had different mineralogy, texture and porosity properties. Cleaning efficiency was evaluated by polarized microscopy, SEM, FTIR spectroscopy and spectrophotometer colour measurements. The results indicate differences in the effectiveness of surface cleaning for the blue, red and black paints as opposed to the silver paint, mainly attributed to chemical composition. No evidence was found that the granite properties had a bearing on laser effectiveness, although the degree, type and spatial distribution of transgranular fissures in the stone affected the overall assessment of cleaning effectiveness. Polarized light microscopy observations and colour measurements showed that the intensity and distribution of fissures affect the depth of paint penetration, ultimately affecting the cleaning efficiency for both granites.

Hydrothermal modification of host rock geochemistry within Mo-Cu porphyry deposits in the Galway Granite, western Ireland

Science.gov (United States)

Tolometti, Gavin; McCarthy, Will

2016-04-01

Hydrothermal alteration of host rock is a process inherent to the formation of porphyry deposits and the required geochemical modification of these rocks is regularly used to indicate proximity to an economic target. The study involves examining the changes in major, minor and trace elements to understand how the quartz vein structures have influenced the chemistry within the Murvey Granite that forms part of the 380-425Ma Galway Granite Complex in western Ireland. Molybdenite mineralisation within the Galway Granite Complex occurred in close association with protracted magmatism at 423Ma, 410Ma, 407Ma, 397Ma and 383Ma and this continues to be of interest to active exploration. The aim of the project is to characterize hydrothermal alteration associated with Mo-Cu mineralisation and identify geochemical indicators that can guide future exploration work. The Murvey Granite intrudes metagabbros and gneiss that form part of the Connemara Metamorphic complex. The intrusion is composed of albite-rich pink granite, garnetiferous granite and phenocrytic orthoclase granite. Minor doleritic dykes post-date the Murvey Granite, found commonly along its margins. Field mapping shows that the granite is truncated to the east by a regional NW-SE fault and that several small subparallel structures host Mo-Cu bearing quartz veins. Petrographic observations show heavily sericitized feldspars and plagioclase and biotite which have undergone kaolinization and chloritisation. Chalcopyrite minerals are fine grained, heavily fractured found crystallized along the margins of the feldspars and 2mm pyrite crystals. Molybdenite are also seen along the margins of the feldspars, crystallized whilst the Murvey Granite cooled. Field and petrographic observations indicate that mineralisation is structurally controlled by NW-SE faults from the selected mineralization zones and conjugate NE-SW cross cutting the Murvey Granite. Both fault orientations exhibit quartz and disseminated molybdenite

A NEW INTERPRETATION FOR THE GARNET ZONING IN METAPELITIC ROCKS OF THE SILGARÁ FORMATION, SOUTHWESTERN SANTANDER MASSIF, COLOMBIA

Directory of Open Access Journals (Sweden)

Ríos Reyes Carlos Alberto

2008-06-01

Full Text Available A Barrovian sequence of the Silgará Formation at the southwestern Santander Massif, Colombian Andes, contains zoned garnets in which major and trace element zoning correlates with distribution of mineral inclusions, which may indicate that garnet growth rate varied through time and affected both composition and texture ofgarnets, although different garnet producing reactions have also played an important role in the chemical zoning of garent. However, a local metasomatism process associated to the action of late magmatic fluids associated to the emplacement of the Pescadero Pluton (external forcing mechanism would be also considered. In particular, Ca, Mn and Y zoning patterns in some garnets correspond with inclusion-rich vs. inclusion-free zones, althoughthe distribution of inclusions does not correlate with chemical zoning (i.e., the same inclusions are found in Ca-rich and Ca-poor zones of the garnet. There is a similar lack of correlation with accessory phases (apatite, monazite, xenotime, ilmenite or rutile. In a garnet from the garnet-staurolite zone, a high Mn core containsabundant and randomly oriented apatite, monazite and ilmenite inclusions, while a euhedral low Ca mantle zone is inclusion-free and the high Ca / low Mn rim zone contains apatite, monazite and ilmenite aligned parallel to the margins of the garnet. Inclusions in garnet can also represent mineral phases were not completely consumed during garnet growth. Association of garnet zoning trends and patterns with inclusion distribution may help differentiatebetween processes that identically affect major-element zoning but that produced variable textures in the garnet.

Magnetic anisotropies in ultrathin bismuth iron garnet films

International Nuclear Information System (INIS)

Popova, Elena; Franco Galeano, Andres Felipe; Deb, Marwan; Warot-Fonrose, Bénédicte; Kachkachi, Hamid; Gendron, François; Ott, Frédéric

2013-01-01

Ultrathin bismuth iron garnet Bi 3 Fe 5 O 12 films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi 3 Fe 5 O 12 films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization. - Highlights: ► Ultrathin Bi 3 Fe 5 O 12 films were grown epitaxially on structure-matching substrates. ► Magnetic properties of Bi 3 Fe 5 O 12 were studied down to the thickness of 2.5 nm. ► Reorientation of easy magnetization axis as a function of film thickness was observed

Magnetic anisotropies in ultrathin bismuth iron garnet films

Energy Technology Data Exchange (ETDEWEB)

Popova, Elena, E-mail: popova@physique.uvsq.fr [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Franco Galeano, Andres Felipe [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Deb, Marwan [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Warot-Fonrose, Bénédicte [Centre d' Elaboration de Matériaux et d' Etudes Structurales (CEMES), CNRS, 29 rue Jeanne Marvig, 31055 Toulouse (France); Transpyrenean Associated Laboratory for Electron Microscopy (TALEM), CEMES-INA, CNRS–Universidad de Zaragoza (Spain); Kachkachi, Hamid [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Gendron, François [Institut des NanoSciences de Paris (INSP), CNRS/Université Pierre et Marie Curie-Paris 6, 4 place Jussieu, Boîte courrier 840, 75252 Paris Cedex 05 (France); Ott, Frédéric [Laboratoire Léon Brillouin (LLB), CNRS/CEA, Bâtiment 563, CEA Saclay, 91191 Gif sur Yvette Cedex (France); and others

2013-06-15

Ultrathin bismuth iron garnet Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi{sub 3}Fe{sub 5}O{sub 12} films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization. - Highlights: ► Ultrathin Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on structure-matching substrates. ► Magnetic properties of Bi{sub 3}Fe{sub 5}O{sub 12} were studied down to the thickness of 2.5 nm. ► Reorientation of easy magnetization axis as a function of film thickness was observed.

Magnetic field strength dependence of the magnetostriction of rare-earth iron garnets

International Nuclear Information System (INIS)

Zvezdin, A.K.; Levitin, R.Z.; Popov, A.I.; Silant'ev, V.I.

1981-01-01

The magnetostriction of holmium-yttrium iron garnets Hosub(x)Ysub(3-x)Fesub(5)Osub(12) (x=3 or 1.05) is measured in pulsed magnetic fields up to 200 kOe at 78 K. It is shown that the magnetostriction constants lambda 111 and lambda 100 of these ferrimagnets depends on the magnetic field strength. The magnetostriction constant of the iron garnet Ho 3 Fe 5 O 12 increases and of the iron garnet Hosub(1.05)Ysub(1.95)Fesub(5)Osub(12) decreases with increase of the field strength. The field dependences of the anisotropic magnetostriction constants lambda 111 and lambda 100 for Hosub(1.05)Ysub(1.95)Fesub(5)Osub(12) are fundamentally different. Thus lambda 111 depends quadratically on the total effective field Hsub(eff) whereas lambda 100 depends almost linearly on Hsub(eff). A theoretical analysis of the magneto-elastic interaction in rare-earth iron garnets is carried out [ru

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)

Experimental early crystallization of K-feldspar in granitic systems. Implications on the origin of magmatic fabrics in granitic rocks

Energy Technology Data Exchange (ETDEWEB)

Díaz-Alvarado, J.

2017-07-01

One of the most outstanding characteristics of some granodioritic to granitic rocks is the presence of K-feldspar megacrysts. For instance, granodiorites and monzogranites of the Spanish Central System batholith present variable amounts of large (up to 10cm in length) euhedral K-feldspar crystals. The porphyritic textures, the euhedral shape, the alignment of plagioclase and biotite inclusions and the magmatic fabrics point to a magmatic origin for these megacrysts. This work presents a phase equilibria study in a high-K2O granodioritic system. A series of experiments were conducted with a granodioritic composition (GEMbiot) to study the crystallization sequence at the emplacement conditions in the Gredos massif, i.e. 4 H2O wt.% and 0.4GPa. Experimental results show that orthopiroxene is the liquidus phase at 1010ºC, which reacts with the H2O-rich melt to stabilize biotite between 980 and 940ºC. Plagioclase crystallizes at around 910ºC, and K-feldspar crystallizes in the matrix between 750 and 700ºC when the crystal fraction is around 0.5. However, at 850 ºC, a pelite-doped experiment shows euhedral K-feldspar (≈5vol%) in both the reactive xenolith domain together with cordierite and the granodioritic domain, where the K2O wt.% rise from 4.5 in the normal experiment to 5.9 in the doped experiment. These results suggest that the bulk-assimilation process promotes the bulk and heterogeneous K2O enrichment in a huge granodioritic magma volume, which triggers an early crystallization of K-feldspar megacrysts. Because of this early crystallization of the megacrysts, the magmatic foliations defined by K-feldspar megacrysts are formed during and after the emplacement processes and are highly influenced by tectonic kinematics.

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)

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

Petrology of Olkiluoto

International Nuclear Information System (INIS)

Kaerki, A.; Paulamaeki, S.

2006-11-01

The rocks of Olkiluoto fall into four main groups: (1) gneisses, (2) migmatitic gneisses, (3) TGG-gneisses (TGG = tonalite-granodiorite-granite) and 4) pegmatitic granites. In addition, narrow diabase dykes occur sporadically. The gneisses include homogeneous mica-bearing quartz gneisses, banded mica gneisses and hornblende or pyroxene-bearing mafic gneisses. The migmatitic gneisses, which typically comprise 20 - 40% leucosome, can be divided into three subgroups in terms of their migmatite structures: veined gneisses, stromatic gneisses and diatexitic gneisses. The leucosomes of the veined gneisses show vein-like, more or less elongated traces with some features similar to augen structures. Planar leucosome layers characterize the stromatic gneisses, while the migmatite structure of the diatexitic gneisses is asymmetric and irregular. The TGG gneisses are medium-grained, relatively homogeneous rocks that can show a blastomylonitic foliation, but they can also resemble plutonic, unfoliated rocks. The pegmatitic granites are leucocratic, very coarse-grained rocks, which may contain large garnet, tourmaline and cordierite phenocrysts. Mica gneiss inclusions are typical of the larger pegmatitic bodies. Gneisses, which are weakly or not at all migmatitic, make ca. 9% of the bedrock. Migmatitic gneisses make up over 64% of the volume of the Olkiluoto bedrock, with the veined gneisses accounting for 43%, the stromatic gneisses for 0.4% and the diatexitic gneisses for 21%, based on drill core logging. Of the remaining lithologies, TGG gneisses constitute 8% and pegmatitic granites almost 20% by volume. The supracrustal rocks of Olkiluoto can be divided into four series by reference to whole rock chemical composition: a T series, S series, P series and basic, volcanogenic gneisses. Rocks of the T, S and P series seem to make up 42%, 12% and 26%, respectively, of the volume of central part of the island of Olkiluoto, in addition to which, pegmatitic granites and diabases

The distribution of radioelements in archaean granites of the Kaapvaal Craton, with implications for the source of uranium in the Witwatersrand Basin

International Nuclear Information System (INIS)

Robb, L.J.; Meyer, M.; Ferraz, M.F.; Drennan, G.R.

1989-05-01

Approximately 500 samples from the Archaean granitic basement of the southern Kaapvaal Craton have been analysed, for U and Th. When viewed in conjunction with geological relationships, the radioelement distribution patterns in the Archaean basement provide contraints regarding the origin of uranium in the Witwatersrand Basin. Granites in the Baberton region are sub-divided into three magnetic cycles, the earliest cycle comprising tonalite-trondhjemite gneisses, the intermediate cycle comprising literally extensive K-rich batholiths and the final stage consisting of discrete intrusive granitic plutons. Uranium and thorium contents vary as a function of age and rock type, an increase progressively from the first cycle through to the third cycle. Certain of the late granite plutons may have been S-type in origin, have relatively low Th/U ratios, high U contents, and are characterized by accessory minerals dominated by monazite-like phases. The late granite plutons with highest radioelement contents appear to have formed circa 2,8 Ga, an age which coincides with granulite facies metamorphism and uranium-thorium depletion in the lower crust, as recrorded in the Vredeford crustal profile. Uranium has been leached from portions of the regolith profile, but also concentrated into leucoxene-rich zones derived from the breakdown of pre-existing titanium-bearing phases. The widespread development of an uraniferous leucoxene protore in weathered source rocks of the Witwatersrand Basin has relevance to the genesis of authigenic U-Ti phases (brannerite) in the reefs themselves. The study of radioelement distribution in Archaean granites adjacent to the Witwatersrand Basin provides a framework within which considerations regarding the origin of the uranium deposits in the basin can be viewed. The secular evolution of the Archaean granitic basement, hydrothermal processes, and palaeoweathering all played a role in the formation of the Witwatersrand deposits

Verification of the both hydrogeological and hydrogeochemical code results by an on-site test in granitic rocks

Directory of Open Access Journals (Sweden)

Michal Polák

2007-01-01

Full Text Available The project entitled “Methods and tools for the evaluation of the effect of engeneered barriers on distant interactions in the environment of a deep repository facility” deals with the ability to validate the behavior of applied engeneered barriers on hydrodynamic and migration parameters in the water-bearing granite environment of a radioactive waste deep repository facility. A part of the project represents a detailed mapping of the fracture network by means of geophysical and drilling surveys on the test-site (active granite quarry, construction of model objects (about 100 samples with the shape of cylinders, ridges and blocks, and the mineralogical, petrological and geochemical description of granite. All the model objects were subjected to migration and hydrodynamic tests with the use of fluorescein and NaCl as tracers. The tests were performed on samples with simple fractures, injected fractures and with an undisturbed integrity (verified by ultrasonic. The gained hydrodynamic and migration parameters of the model objects were processed with the modeling software NAPSAC and FEFLOW. During the following two years, these results and parameters will be verified (on the test-site by means of a long-term field test including the tuning of the software functionality.

Magnetic fabrics of the syn to post orogenic granite suites of the Brusque metamorphic complex (Dom Feliciano Belt, Santa Catarina, Brasil

International Nuclear Information System (INIS)

Steenken, A; Basei, M.; Lopez de Luchi, M.

2007-01-01

The Dom Feliciano belt in southern Brazil and Uruguay has accommodated the collision between the cratons of Kalahari and Congo versus the Luis Alves microplate as a fragment of the Rio de La Plata craton during the Rio Doce orogeny in the late Neoproterozoic. The Sierra Ballena - Major Gercino shear zone was interpreted as the suture between the cratons. In the state of Santa Catarina three suites of highly evolved granites intruded the Brusque metamorphic complex in the northwest of the Major Gercino shear zone. Magmatic contacts between the different suites denote to their close temporal intrusion sequence. Shear zone activity is documented by local low temperature brittle deformation of the intrusive suites. Fabrics of the granites were obtained by the measurement of the anisotropy of the magnetic susceptibility (AMS). Low bulk susceptibilities (Kvol -6 SI) and a low degree of the total anisotropy (P' < 1.07) suggest a paramagnetic origin of the magnetic fabrics that may be directly correlated with the macroscopic rock fabric. Planar fabrics form a dome-like foliation pattern for the main Valsungana intrusion occupying the southwestern part of the NE-SW elongated intrusion. Linear fabrics show a weakly defined ENE-WSW trend parallel to the late stage transcurrent extension of the basement. It is suggested that a number of dome-like intrusions that follow the trend of the Major Gercino shear zone in the northwest were emplaced and subsequently amalgamated in the course of magma ascent leading to present outcrop shape of the intrusive complex

RBS Characterization of Yttrium Iron Garnet Thin Films

International Nuclear Information System (INIS)

Roumie, M; Abdel samad, B.

2008-01-01

Magnetic materials such as yttrium iron garnet (YIG) are of great importance for its magneto-optic properties and for their potential applications in the domain of optical telecommunications. The deposition of thin films of YIG, on quartz or GGG (gadolinium gallium garnet) substrate, was performed using radio frequency non reactive magnetron sputtering, followed by high temperature annealing which is needed to enhance the crystallinity of the layers. Rutherford backscattering spectrometry RBS was used to determine the thickness and stoichiometry of the performed layers in order to investigate correlations between growth conditions and the quality of the final material. RBS measurements showed the influence of the deposition time and the temperature substrate on the film growth and its stoichiometry. (author)

An exotic terrane in the Sulu UHP region, China

Science.gov (United States)

Chu, W.; Zhang, R.; Tsujimori, T.; Liou, J. G.

2004-12-01

The Haiyangsuo region of about 15 km2 along the coast in the NE part of the Triassic Sulu UHP terrane occurs three major rock types: amphibolitized metagabbro, gneiss and granitic dikes. Three different gneisses were observed in the field: A) Light color felsic gneiss is the dominant country rock and contains Qtz, Pl, Ms and Bi. B) Dark color plagioclase-amphibole gneiss occurs as thin layers within country rock; C) Granulite facies rock occurs as discontinuous lens. The amphibolitized metagabbros intrude into the gneisses as massive bodies (several m to hundreds of m in size) and thin dikes. Both metamorphic intrusives and gneisses are cross-cut by granitic dikes. The amphibolitized metagabbro was divided into three types: coronal metagabbro, transitional rock and garnet amphibolite: 1) Coronal metagabbro preserves gabbroic texture and primary assemblage of Opx+Cpx+Pl+Amp+Ilm. Most pyroxene grains are partially rimmed by thin corona of Amp+Ab+Qtz. Garnet occurs as fine-grained coronas at interface between plagioclase, pyroxene or ilmenite. 2) Transitional rocks contain similar assemblage and texture but most orthopyroxenes were partially or totally replaced by Amp+Qtz; garnet increases in content and size. Some gabbroic textures are preserved, but calcic plagioclase was replaced by zoisite, albite and muscovite. 3) Garnet amphibolite occurs at the margins of intrusive bodies and boudins where only minor relict clinopyroxenes preserve. Garnet coronal chains are not clear any more. Granitic dikes show pronounced deformation with mylonitic texture and contain 40-50% quartz porphyroclasts. Zircon separates from 2 metagabbros, 4 gneisses and 1 granitic rock were dated by using Stanford SHRIMP-RG. Metagabbroic zircons are angular and fractured shapes. The upper-intercept ages of gneisses rang from 1730 to about 2400 Ma, indicating variable protoith age. The 2 garnet amphibolites have upper-intercept ages 1734±5Ma and 1735±21Ma respectively. They are much older than

Polycrystalline magnetic garnet films comprising weakly coupled crystallites for piezoelectrically-driven magneto-optic spatial light modulators

Energy Technology Data Exchange (ETDEWEB)

Mito, S.; Sakurai, H.; Takagi, H.; Inoue, M. [Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Baryshev, A. V. [Electronics-Inspired Interdisciplinary Research Institute Toyohashi, Aichi 441-8580 (Japan); Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russian Federation)

2012-04-01

We have investigated the magnetization process of the polycrystalline magnetic garnet films in order to determine the most suitable composition of garnet films for piezoelectrically-driven magneto-optic spatial light modulators (MOSLMs). For experiment, the bismuth-dysprosium-aluminum-substituted yttrium iron (Bi{sub 1.3}Dy{sub 0.7}Y{sub 1.0}Fe{sub 3.1}Al{sub 1.9}O{sub 12}) garnet films were deposited by an RF magnetron sputter and annealed at 700 deg. C in air. The annealing time was varied in a range of several minutes to control the grain size. The saturation magnetization, the remanent magnetization and the composition of the fabricated garnet films slightly changed versus the annealing time. Experiments showed that the coercivity and the grain size increased at longer annealing; the coercivity was larger for films with bigger grains. This work shows that garnet films with smaller coercivity are most suitable for controlling the magnetization of garnet and, correspondingly, the magneto-optical rotation of MOSLM pixels driven by piezoelectrics.

Variscan thrusting in I- and S-type granitic rocks of the Tribeč Mountains, Western Carpathians (Slovakia: evidence from mineral compositions and monazite dating

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Broska Igor

2015-12-01

Full Text Available The Tribeč granitic core (Tatric Superunit, Western Carpathians, Slovakia is formed by Devonian/Lower Carboniferous, calc-alkaline I- and S-type granitic rocks and their altered equivalents, which provide a rare opportunity to study the Variscan magmatic, post-magmatic and tectonic evolution. The calculated P-T-X path of I-type granitic rocks, based on Fe-Ti oxides, hornblende, titanite and mica-bearing equilibria, illustrates changes in redox evolution. There is a transition from magmatic stage at T ca. 800–850 °C and moderate oxygen fugacity (FMQ buffer to an oxidation event at 600 °C between HM and NNO up to the oxidation peak at 480 °C and HM buffer, to the final reduction at ca. 470 °C at ΔNN= 3.3. Thus, the post-magmatic Variscan history recorded in I-type tonalites shows at early stage pronounced oxidation and low temperature shift back to reduction. The S-type granites originated at temperature 700–750 °C at lower water activity and temperature. The P-T conditions of mineral reactions in altered granitoids at Variscan time (both I and S-types correspond to greenschist facies involving formation of secondary biotite. The Tribeč granite pluton recently shows horizontal and vertical zoning: from the west side toward the east S-type granodiorites replace I-type tonalites and these medium/coarse-grained granitoids are vertically overlain by their altered equivalents in greenschist facies. Along the Tribeč mountain ridge, younger undeformed leucocratic granite dykes in age 342±4.4 Ma cut these metasomatically altered granitic rocks and thus post-date the alteration process. The overlaying sheet of the altered granites is in a low-angle superposition on undeformed granitoids and forms “a granite duplex” within Alpine Tatric Superunit, which resulted from a syn-collisional Variscan thrusting event and melt formation ~340 Ma. The process of alteration may have been responsible for shifting the oxidation trend to the observed

Contribution to 57Fe ion implanted garnet study by Moessbauer effect

International Nuclear Information System (INIS)

Kornilios, N.

1986-11-01

Due to because of their numerous physical properties, garnets are often used in new technologies. In order to improve their properties, ion implantation of inert gases has been proved to be a powerful technique to elaborate bubble memories. Recently it has been shown that high doses implanted ions, chemically reacting with the matrix could give interesting results. If the bulk is completely amorphized after implantation, further annealings can recrystallize it. In this study Y 3 F 5 O 12 , Y 3 Al 5 O 12 and Gd 3 Ga 5 O 12 single crystals were 100 keV implanted with 57 Fe ions at doses ranging between 10 16 and 10 17 ions cm -2 . The iron chemical states were determined thanks to Conversion Electron Moessbauer Spectroscopy (CEMS) and it was shown that the alloying elements of the matrix could influence the nature of the created phases. After thermal treatments the sample superficial layers were characterized using CEMS, grazing angle X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Rutherford Backscattering Spectroscopy (RBS). Different annealing stages were put forward: the oxidation of the implanted iron below 650 0 C and the garnet recrystallization around 850 0 C with some iron substitution in the garnet octahedral and tetraedral sites. The overstoechiometric iron forms particles of mixed oxides (FeAl) 2 O 3 , (FeGa) 2 O 3 or particles of pure Fe 2 O 3 oxide depending on the garnet. For the first time it is proved that after annealing around 1200-1300 0 C a complete rebuilding of the garnet matrix can induce for these oxide particles at room temperature a Morin transition [fr

Effect of Bacillus subtilis on Granite Weathering: A Laboratory Experiment

Science.gov (United States)

Song, W.; Ogawa, N.; Oguchi, C. T.; Hatta, T.; Matsukura, Y.

2006-12-01

We performed a comparative experiment to investigate how the ubiquitous soil bacterium Bacillus subtilis weathers granite and which granite-forming minerals weather more rapidly via biological processes. Batch type experiments (granite specimen in a 500 ml solution including NaCl, glucose, yeast extract and bacteria Bacillus subtilis at 27°E C) were carried out for 30 days. Granite surfaces were observed by SEM before and after the experiment. Bacillus subtilis had a strong influence on granite weathering by forming pits. There were 2.4 times as many pits and micropores were 2.3 times wider in granite exposed to Bacillus subtilis when compared with bacteria-free samples. Bacillus subtilis appear to preferentially select an optimum place to adhere to the mineral and dissolve essential elements from the mineral to live. Plagioclase was more vulnerable to bacterial weathering than biotite among the granite composing minerals.

Melts of garnet lherzolite: experiments, models and comparison to melts of pyroxenite and carbonated lherzolite

Science.gov (United States)

Grove, Timothy L.; Holbig, Eva S.; Barr, Jay A.; Till, Christy B.; Krawczynski, Michael J.

2013-01-01

Phase equilibrium experiments on a compositionally modified olivine leucitite from the Tibetan plateau have been carried out from 2.2 to 2.8 GPa and 1,380–1,480 °C. The experiments-produced liquids multiply saturated with spinel and garnet lherzolite phase assemblages (olivine, orthopyroxene, clinopyroxene and spinel ± garnet) under nominally anhydrous conditions. These SiO2-undersaturated liquids and published experimental data are utilized to develop a predictive model for garnet lherzolite melting of compositionally variable mantle under anhydrous conditions over the pressure range of 1.9–6 GPa. The model estimates the major element compositions of garnet-saturated melts for a range of mantle lherzolite compositions and predicts the conditions of the spinel to garnet lherzolite phase transition for natural peridotite compositions at above-solidus temperatures and pressures. We compare our predicted garnet lherzolite melts to those of pyroxenite and carbonated lherzolite and develop criteria for distinguishing among melts of these different source types. We also use the model in conjunction with a published predictive model for plagioclase and spinel lherzolite to characterize the differences in major element composition for melts in the plagioclase, spinel and garnet facies and develop tests to distinguish between melts of these three lherzolite facies based on major elements. The model is applied to understand the source materials and conditions of melting for high-K lavas erupted in the Tibetan plateau, basanite–nephelinite lavas erupted early in the evolution of Kilauea volcano, Hawaii, as well as younger tholeiitic to alkali lavas from Kilauea.

The comparative hydrochemistry of two granitic island aquifers. The Isles of Scilly, UK and the Hvaler Islands, Norway

International Nuclear Information System (INIS)

Banks, D.; Reimann, C.; Skarphagen, H.

1998-01-01

A comparative study is presented of granitic groundwaters from the Hvaler Islands, south-eastern Norway (11 samples) and the Scilly Islands, south-western England (10 samples). The islands display similar bulk lithologies (peraluminous S-type, U/Th-enriched granites) and land use, but differing glaciation and hence weathering histories. The groundwater of both groups bears a strong marine signature, although the Hvaler Islands display less marine influence and a greater degree of water-rock interaction. The most interesting hydrochemical dissimilarities concern the health related trace elements Rn, U and F. These display median (and maximum) values of 2510 Bq/l (8520 Bq/l), 15 μg/l (170 μg/l) and 3.3 mg/l (4.4 mg/l), respectively for Hvaler, compared with 140 Bq/l (200 Bq/l), 1.5 μg/l (4 μg/l) and 0.1 mg/l (0.27 mg/l) for Scilly. Commonly employed drinking water limits for these parameters are 500 Bq/l (Norwegian action level), 20 μg/l (Canadian limit) and 1.5 mg/l. The differences in groundwater contents of these elements between Hvaler and Scilly may be ascribed to: (1) differing trace element compositions of the granites and fracture mineralisations; (2) radically differing recent weathering histories; and (3) hydrodynamic factors

Depositional features and stratigraphic sections in granitic plutons: implications for the emplacement and crystallization of granitic magma

Science.gov (United States)

Wiebe, R. A.; Collins, W. J.

1998-09-01

Many granitic plutons contain sheet-like masses of dioritic to gabbroic rocks or swarms of mafic to intermediate enclaves which represent the input of higher temperature, more mafic magma during crystallization of the granitic plutons. Small-scale structures associated with these bodies (e.g. load-cast and compaction features, silicic pipes extending from granitic layers into adjacent gabbroic sheets) indicate that the sheets and enclave swarms were deposited on a floor of the magma chamber (on granitic crystal mush and beneath crystal-poor magma) while the mafic magma was incompletely crystallized. These structures indicate 'way up', typically toward the interior of the intrusions, and appear to indicate that packages of mafic sheets and enclave concentrations in these plutons are a record of sequential deposition. Hence, these plutons preserve a stratigraphic history of events involved in the construction (filling, replenishment) and crystallization of the magma chamber. The distinctive features of these depositional portions of plutons allow them to be distinguished from sheeted intrusions, which usually preserve mutual intrusive contacts and 'dike-sill' relations of different magma types. The considerable thickness of material that can be interpreted as depositional, and the evidence for replenishment, suggest that magma chamber volumes at any one time were probably much less than the final size of the pluton. Thus, magma chambers may be constructed much more slowly than presently envisaged. The present steep attitudes of these structures in many plutons may have developed gradually as the floor of the chamber (along with the underlying solidified granite and country rock) sank during continuing episodes of magma chamber replenishment. These internal magmatic structures support recent suggestions that the room problem for granites could be largely accommodated by downward movement of country rock beneath the magma chamber.

Granitic rocks from the southern Gyeongsang basin, southeastern Korea, (1)

International Nuclear Information System (INIS)

Lee, Yoon-Jong

1980-01-01

In southern Gyeongsang basin, southeastern Korea, there are many granitic rock masses. They were divided into 7 groups according to their geological evidences. K-Ar age was determined on 36 samples obtained from the respective groups. Group A: pre-Gyeongsang granitic rock (Pre-Cretaceous), A 1 220 m.y., A 2 166 m.y.; group B: outer zone granitic rock (Cretaceous), 115-72 m.y.; group C: ditto (ditto), 97-70 m.y.; group D: ditto (ditto), 89-68 m.y.; group E: ditto (ditto), 82-68 m.y.; group F: inner zone granitic rock (Cretaceous), 75-74 m.y.; group G: Tertiary granitic rock, 63-41 m.y. The large part of the Cretaceous granitic masses show the double elongated ring form. Most of the Tertiary granitic rocks were probably emplaced in close relation with the Eonyang fault line and Ulsan fault line/or their extension line of the area. (J.P.N.)

2005 dossier: granite. Tome: phenomenological evolution of the geologic disposal

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 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.)

Analysis of garnets from the archaeological sites in Slovenia

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Šmit, Ž., E-mail: ziga.smit@fmf.uni-lj.si [Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana (Slovenia); Jožef Stefan Institute, Ljubljana (Slovenia); Fajfar, H. [Jožef Stefan Institute, Ljubljana (Slovenia); Jeršek, M. [Slovenian Museum of National History, Ljubljana (Slovenia); Knific, T. [National Museum of Slovenia, Ljubljana (Slovenia); Lux, J. [Institute for the Protection of Cultural Heritage of Slovenia, Ljubljana (Slovenia)

2014-06-01

Garnets (62 individual stones) originating from the Migration Period cemeteries and hilltop settlements in Slovenia were analyzed by the combined PIXE/PIGE method for their chemical composition. Typologically, the analyzed stones may be classified as almandines originating from the sites in India, belonging to types I and II according to Calligaro. A smaller group of pyraldines intermediate between almandines and pyropes was also determined; identified as type III, their source is most likely in Sri Lanka. No garnets from Bohemia (Czech Republic) have been discovered, which may be related to important political changes in the 7th c. AD, induced by Slavic and Avaric migrations.

Synthesis of complex oxides with garnet structure by spray drying of an aqueous salt solution

Science.gov (United States)

Makeenko, A. V.; Larionova, T. V.; Klimova-Korsmik, O. G.; Starykh, R. V.; Galkin, V. V.; Tolochko, O. V.

2017-04-01

The use of spray drying to obtain powders of complex oxides with a garnet structure has demonstrated. The processes occurring during heating of the synthesized oxide-salt product, leading to the formation of a material with a garnet structure, have been investigated using DTA, TGA, XPS, and XRD. It has been shown that a single-phase garnet structure of system (Y x Gd(3- x))3Al5O12 can be synthesized over the entire range of compositions.

Au-As (lead) vein mineralizations of the Cevennes and Chataigneraie regions (French Massif Central). Isotopic characterization (Pb). Mineralizing role of granites in the setting up of these mineralizations

International Nuclear Information System (INIS)

Havard, M.L.

1997-06-01

This work has been carried out in the Frame of the national program 'Geofrance 3D' jointly organized by the French office for geologic and mining researches (BRGM), and the CNRS-INSU/DSPT3. Its aim is the study of the formation of gold-bearing mineralizations of the Variscan chain in the Cevennes and Chataigneraie regions (French Massif Central). In the Cevennes region, the gold-bearing veins are linked with the intrusion of the late-tectonic granodioritic plutons. The aim of this study is to determine the chronology of the mineralizing episodes and to analyze the relationship between the metal concentrates and the setting up of the granites. In the Chataigneraie region, the granites are intrusive in ortho- and para-gneiss series. The hydrothermal activity associated with the contact metamorphism should be responsible for the deposition of gold-bearing wolfram mineralization. The geochemistry of lead isotopes is used to determine the origin of metals in the sulfide mineralizations. The scanning electron microscopy (SEM) is used for the visualization of the microstructure heterogeneities of the minerals and for the quantitative chemical analysis of their successive para-geneses. The comparison between the results obtained in both regions allows to make a difference between their relative degree of erosion and their gold potentialities. (J.S.)

Magma flow recorded by magmatic and magnetic fabrics in a shallow granitic pluton: La Gloria Pluton, central Chile

Science.gov (United States)

Payacán, I. J.; Gutiérrez, F. J.; Gelman, S. E.; Bachmann, O.; Parada, M. A.

2013-12-01

To better understand the dynamics of a small, shallow, silicic magma reservoir, magmatic and magnetic (AMS) fabrics are compared in samples obtained from La Gloria Pluton (LGP), a 10 Ma granitic intrusion located in southern Andes. The magnetic fabric of LGP, mainly given by magnetite, is characterized by oblate shapes. Magnetic lineations have a NW trend with subhorizontal dip, following the main pluton elongation, while magnetic foliation planes have dips varying gradually from vertical at the walls to subhorizontal toward the center and the roof of the pluton. On the basis of numerical simulations, magnetic fabric was interpreted to represent the shear record induced by magmatic convection along solidification fronts as the reservoir reached its rheological locking point. Magmatic fabric (mineral orientation) was determined on 12 samples along the pluton. Three mutually orthogonal thin sections were produced for each sample, perpendicular to the AMS tensor axes. Size and orientation of individual crystals were obtained by image analysis. A 2-D tensor for two mineral groups (plagioclase and amphibole+biotitie) was defined in each mineral plane projecting the crystal lengths on the main crystal orientation (given by Bingham statistics). A 3-D magmatic fabric tensor was obtained. In order to compare the magmatic and magnetic fabrics, magmatic anisotropy parameters were defined similar to the AMS tensors. Magmatic fabric and anisotropy parameter values vary depending on the location inside the pluton: (1) Samples located at the borders exhibit vertical foliations and lineations with a NW trend, similar to the magnetic fabric tensors and higher anisotropy values for plagioclase than amphibole+biotite,; (2) samples located at the center of the LGP commonly present subvertical foliations/lineations, which differ from the magnetic fabric, and higher magmatic anisotropy degree values for amphibole+biotite than plagioclase. Based on numerical simulations of the fluid

Corresponding between geothermometry based on mineral chemistry and deformation temperature for mylonitized granite of Noghan bridge (Sanandaj-Sirjan zone)

International Nuclear Information System (INIS)

Ataeifard, N.; Shabanian, N.; Davoudian, A.

2016-01-01

Noghan granitoid intrusion is located at the NW of Boin- Miandasht and lies in the Sanandaj-Sirjan structural zone (SSZ). Body shape is a stretched ellipsoid with NW-SE strike. The meta-granite body is extremely deformed and displays mylonitic structure such as lineation and foliation. Mylonitic texture is main texture but also show seriate granular and lipido-granoblastic textures. The main minerals are quartz, K-feldspar, plagioclase, Biotite and muscovite. Chlorite is an accessory mineral. The biotite is magmatic and recrystallized. The chlorites are alteration product. The geothermometry of biotites and chlorites shows the temperatures of 397-549°C and 231-252 °C that show good correlation with microstructure in the rock. Therefore, mantle microstructure including recrystallized subgrains in porphyroclast rims that result to Grain boundary migration and chessboard undulose extinction with fine blocky grains and amoeboid grain in quartz grains show formation temperature close to 500 °C. Microstructures such as undulose extinction, pressure solution and in quartz, tensile fracture and bookshelf sliding in feldspar, brittle fractures and displacement of folded pieces in biotite display that temperature is lower than 300°C.

PREVALENCE OF METABOLIC SYNDROME IN GRANITE WORKERS

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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

U-TH-REE mobility and diffusion in granitic environments during alteration of accessory minerals and U-ores

International Nuclear Information System (INIS)

Cathelineau, M.; Vergneaud, M.

1989-01-01

U, Th and REE concentrations and distributions have been studied in granitic rocks, using a multidisciplinary approach involving micromapping of cracks in oriented samples, together with mineralogical and geochemical studies of the different U-Th-REE bearing phases. The behavior of U, Th and Nd, considered as chemical analogue elements of the radiotoxic nuclides, was investigated either in the vicinity of microsites (accessory mineral enviornment) or along plurimetric sections around U-ore bodies. The different granite minerals, especially the accessory minerals (uraninite, monazite, thorite, apatite, xeonotime), as well as U-ores, present different initial concentrations of U, Th and REE. Limitations to the analogy between these U-Th-REE concentrations and the radwastes is discussed as a function of their mineralogical features, chemical compostion, size and solubilities. These primary concentrations present different behavior when subjected to hydrothermal alteration, such as propylitization, phyllite type alteration, or clay alteration. Results show that in reduced media, in the temperature range 80-2000 0 C, the rate of mobilization of U, Th, REE is relatively moderate. However, fluids enriched in flourides, phosphates or carbonates may significantly solubilize and transport U and REE under specific conditions. In addition, the degree of opening of the microcracks and faults, as well as the oxidation-reduction processes, are critical parameters for the efficiency of the granitic geological barrier

Orphan Strontium-87 in Abyssal Peridotites: Daddy Was a Granite

Science.gov (United States)

Snow, Jonathan E.; Hart, Stanley R.; Dick, Henry J. B.

1993-12-01

The 87Sr/86Sr ratios in some bulk abyssal and alpine peridotites are too high to be binary mixtures of depleted mantle and seawater components. The apparent excess, or "orphan," 87Sr appears to be separated from its radioactive parent. Such observations were widely held to be analytical artifacts. Study of several occurrences of orphan 87Sr shows that the orphan component in abyssal peridotite is located in the alteration products of olivine and enstatite in the peridotite. The orphan 87Sr is most likely introduced by infiltration of low-temperature (<200^circC) seawater bearing suspended detrital particulates. These particulates include grains of detrital clay that are partly derived from continental (that is, granitic) sources and thus are highly radiogenic. Orphan 87Sr and other radiogenic isotopes may provide a tracer for low-temperature seawater penetrating into the oceanic crust.

Optical and magnetic properties of a transparent garnet film for atomic physics experiments

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Mari Saito

2016-12-01

Full Text Available We investigated the optical and magnetic properties of a transparent magnetic garnet with a particular focus on its applications to atomic physics experiments. The garnet film used in this study was a magnetically soft material that was originally designed for a Faraday rotator at optical communication wavelengths in the near infrared region. The film had a thickness of 2.1 μm and a small optical loss at a wavelength of λ=780 nm resonant with Rb atoms. The Faraday effect was also small and, thus, barely affected the polarization of light at λ=780 nm. In contrast, large Faraday rotation angles at shorter wavelengths enabled us to visualize magnetic domains, which were perpendicularly magnetized in alternate directions with a period of 3.6 μm. We confirmed the generation of an evanescent wave on the garnet film, which can be used for the optical observation and manipulation of atoms on the surface of the film. Finally, we demonstrated a magnetic mirror for laser-cooled Rb atoms using the garnet film.

Multielemental analyses of isomorphous Indian garnet gemstones by XRD and external pixe techniques.

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Venkateswarulu, P; Srinivasa Rao, K; Kasipathi, C; Ramakrishna, Y

2012-12-01

Garnet gemstones were collected from parts of Eastern Ghats geological formations of Andhra Pradesh, India and their gemological studies were carried out. Their study of chemistry is not possible as they represent mixtures of isomorphism nature, and none of the individual specimens indicate independent chemistry. Hence, non-destructive instrumental methodology of external PIXE technique was employed to understand their chemistry and identity. A 3 MeV proton beam was employed to excite the samples. In the present study geochemical characteristics of garnet gemstones were studied by proton induced X-ray emission. Almandine variety of garnet is found to be abundant in the present study by means of their chemical contents. The crystal structure and the lattice parameters were estimated using X-Ray Diffraction studies. The trace and minor elements are estimated using PIXE technique and major compositional elements are confirmed by XRD studies. The technique is found very useful in characterizing the garnet gemstones. The present work, thus establishes usefulness and versatility of the PIXE technique with external beam for research in Geo-scientific methodology. Copyright © 2012 Elsevier Ltd. All rights reserved.

Multistage magma emplacement and progressive strain accumulation in the shallow-level Krkonoše-Jizera plutonic complex, Bohemian Massif

Science.gov (United States)

Žák, Jiří; Verner, Kryštof; Sláma, Jiří; Kachlík, Václav; Chlupáčová, Marta

2013-09-01

relationships combined with new U-Pb zircon geochronology suggest that the shallow-level Krkonoše-Jizera plutonic complex, northern Bohemian Massif, was assembled successively from bottom to top, starting with emplacement of the separately evolved S-type Tanvald granite (317.3 ± 2.1 Ma), followed by at least two voluminous batches of the I-type porphyritic Liberec (319.5 ± 2.3 Ma) and Jizera (320.1 ± 3.0 Ma and 319.3 ± 3.7 Ma) granites. The intrusive sequence was completed by uppermost, minor intrusions of the equigranular Harrachov (315.0 ± 2.7 Ma) and Krkonoše granites. The I-type granites exhibit an unusually complex pattern of superposed feldspar phenocryst and magnetic fabrics as revealed from the anisotropy of magnetic susceptibility (AMS). The outer Liberec granite preserves margin-parallel foliations and lineations, interpreted to record emplacement-related strain captured by cooling from the pluton floor and walls. In contrast, the inner Jizera, Harrachov, and Krkonoše granites were overprinted by synmagmatic strain resulting from dextral movements along regional strike-slip faults cutting the opposite ends of the plutonic complex. Late-stage felsic dikes in the Liberec and Jizera granites reorient from horizontal to vertical (lineation-perpendicular) attitude in response to changing the least principal stress direction, whereas mafic schlieren do not do so, representing only randomly oriented small-scale thermal-mechanical instabilities in the phenocryst framework. In general, this case example challenges the common approach of inferring pluton-wide magma flow from interpolated foliation, lineation, and schlieren patterns. More likely, magmatic fabrics in large plutons record complex temporal succession of superposed strains resulting from diverse processes at multiple scales.

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

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

Sorption of Np (Ⅴ) on Beishan granite fracture filling materials

International Nuclear Information System (INIS)

Jiang Tao; Wang Bo; Bao Liangjin; Zhou Duo; Long Haoqi; Song Zhixin; Chen Xi

2012-01-01

The sorption behaviors of Np (Ⅴ) on the granite fracture filling materials were studied by batch experiments under anaerobic in Beishan groundwater. The impact of pH of groundwater, CO 3 2- , humic acid and different components of granite fracture filling materials on sorption of Np (Ⅴ) was investigated. The results show that the granite fracture filling materials have strong capacity of Np (Ⅴ) adsorption. The value of K d , for Np (Ⅴ) sorption on the granite fracture filling materials is 843 mL/g. With the increase of pH, the value of K d increases at first and then decreases. K d of Np sorption on granite fracture filling materials in the presence of CO 3 2- and humic acid decreases. The chlorite and feldspar are major contributors to the sorption of Np (Ⅴ) on Beishan granite fracture filling materials. (authors)

Possible genetic link between I-type granite and orogenic gold deposits in Egypt (metamorphic-magmatic interaction?)

Science.gov (United States)

Abd El Monsef, Mohamed

2015-04-01

ores revealed two main groups of fluid inclusions in both areas: A) Aqueous inclusions (H2O-NaCl±KCl system), and B) Carbonic inclusions (H2O-CO2-NaCl±CH4). A drop of pressure during the migration of these fluids to shallower depths along the shear zones was the main reason for phase separation. Isochores calculation from microthermometric results proved that, the P-T boundary conditions outlined for Fatira gold deposits are of 275° to 297° C and between (0.2 - 1.2 Kbar); and of 277° to 300° C and between (0.2 - 1 Kbar) for Gidami gold deposits. The normalization Chondrite patterns of rare earth elements (REEs) for the gold-ore deposits with the surrounding I-type granitic rocks exhibit an obvious similarity and positive correlation. The geological, mineralogical, geochemical and fluid inclusions studies revealed a genetic link between gold mineralization and intrusion of calc-alkaine granitic magma. Whereas, The granitic magma acts as a supplier for the ore-bearing fluid and as a heat source for metamorphic processes, leading to hydrothermal convection currents.

geological mapping of the Onkalo open cut

Energy Technology Data Exchange (ETDEWEB)

Talikka, M. [Geological Survey of Finland, Espoo (Finland)

2005-11-15

Posiva Oy and Geological Survey of Finland carried out geological mapping of the ONKALO open cut in the latter half of the year 2004. The study area is located on the Olkiluoto Island in Eurajoki, SW Finland. The study included geological mapping, stereo-photography, and interpretation of 3D images. Fieldwork was carried out during the construction work. The main rock types are vein migmatite and grey gneiss with variation to granitic grey gneiss. The contacts of the rock types are gradual. The vein migmatite consists of fine- to medium-grained mica gneiss paleosome and granite or granite pegmatite neosome. The proportion of the neosome material varies between 15 and 35 percent and the neosome occurs as veins and bands up to ten centimetres in thickness. The granite I granite pegmatite is medium- to coarse-grained and not orientated. Main minerals in the mica gneiss are plagioclase, biotite, quartz, and in the granite / granite pegmatite potassium feldspar, plagioclase, and quartz. The grey gneiss is medium grained and fairly homogenous comprising mainly plagioclase, biotite, and quartz. The granitic grey gneiss contains also potassium feldspar crystals up to five cm in length. The rocks within the study area are generally well preserved. There is, however, a zone of strongly weathered rocks east of the ONKALO open cut. The main structural feature in the study area is S{sub 2} foliation, which is seen in the orientation of biotite grains. The degree of the foliation is weak to medium in the vein migmatite and weak to non-existence in the grey gneiss. The foliation (S{sub 2}) dips 20-70 deg to southeast with an average direction of 150/45 deg. The migmatisation took place during the second deformation phase and possibly proceeded along the lithologic layers. The neosome veins bend irregularly and folding is present in places. The fold axis of the small scale, isoclinal folds dip 50-70 deg to northeast. In fracture mapping a total of 231 fractures were measured

geological mapping of the Onkalo open cut

International Nuclear Information System (INIS)

Talikka, M.

2005-11-01

Posiva Oy and Geological Survey of Finland carried out geological mapping of the ONKALO open cut in the latter half of the year 2004. The study area is located on the Olkiluoto Island in Eurajoki, SW Finland. The study included geological mapping, stereo-photography, and interpretation of 3D images. Fieldwork was carried out during the construction work. The main rock types are vein migmatite and grey gneiss with variation to granitic grey gneiss. The contacts of the rock types are gradual. The vein migmatite consists of fine- to medium-grained mica gneiss paleosome and granite or granite pegmatite neosome. The proportion of the neosome material varies between 15 and 35 percent and the neosome occurs as veins and bands up to ten centimetres in thickness. The granite I granite pegmatite is medium- to coarse-grained and not orientated. Main minerals in the mica gneiss are plagioclase, biotite, quartz, and in the granite / granite pegmatite potassium feldspar, plagioclase, and quartz. The grey gneiss is medium grained and fairly homogenous comprising mainly plagioclase, biotite, and quartz. The granitic grey gneiss contains also potassium feldspar crystals up to five cm in length. The rocks within the study area are generally well preserved. There is, however, a zone of strongly weathered rocks east of the ONKALO open cut. The main structural feature in the study area is S 2 foliation, which is seen in the orientation of biotite grains. The degree of the foliation is weak to medium in the vein migmatite and weak to non-existence in the grey gneiss. The foliation (S 2 ) dips 20-70 deg to southeast with an average direction of 150/45 deg. The migmatisation took place during the second deformation phase and possibly proceeded along the lithologic layers. The neosome veins bend irregularly and folding is present in places. The fold axis of the small scale, isoclinal folds dip 50-70 deg to northeast. In fracture mapping a total of 231 fractures were measured. Field

Rare Earth Garnet Selective Emitter

Science.gov (United States)

Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

1994-01-01

Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approx. = 0.75, sup 4)|(sub 15/2) - (sup 4)|(sub 13/2),for Er-YAG and epsilon(sub lambda) approx. = 0.65, (sup 5)|(sub 7) - (sup 5)|(sub 8) for Ho-YAG) at 1500 K. In addition, low out-of-band spectral emittance, epsilon(sub lambda) less than 0.2, suggest these materials would be excellent candidates for high efficiency selective emitters in thermophotovoltaic (TPV) systems operating at moderate temperatures (1200-1500 K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. Selective emitters in the near IR are of special interest for thermophotovoltaic (TPV) energy conversion. The most promising solid selective emitters for use in a TPV system are rare earth oxides. Early spectral emittance work on rare earth oxides showed strong emission bands in the infrared (0.9 - 3 microns). However, the emittance outside the emission band was also significant and the efficiency of these emitters was low. Recent improvements in efficiency have been made with emitters fabricated from fine (5 - 10 microns) rare earth oxide fibers similar to the Welsbach mantle used in gas lanterns. However, the rare earth garnet emitters are more rugged than the mantle type emitters. A thin film selective emitter on a low emissivity substrate such as gold, platinum etc., is rugged and easily adapted to a wide variety of thermal sources. The garnet structure and its many subgroups have been successfully used as hosts for rare earth ions, introduced as substitutional

A study of the isotopic and geochemical gradients in the old granite of the Vredefort structure, with implications for continental heat flow

International Nuclear Information System (INIS)

Hart, R.J.

1978-01-01

The presence of granite of pre-Witwatersrand age forming the core of an updomed and overturned sequence of strata at Vredefort, South Africa, has been known for over seventy years. It is only recent geophysical, geochemical and geological evidence that has given rise to the proposal that the basement core has also been overturned, presenting a section of the earth's granitic crust to view. Comprehensive geochemical and isotope studies on this section are presented in the thesis. Detailed trace element profiles across the granite basement inidicate that (i) the central part of the core is depleted in the large ion lithophile elements U, Th and Rb, relative to the perimeter, (ii) the concentrations of U, Th and Rb falls of regularly from the granite margin inwards, and the distribution of these elements over the outer 8 km is consistent with an exponential depth-function, and (iii) the central part of the core is characterised by high K/Rb, Th/U, K/U, K/Th, Ba/Rb and low Rb/Sr ratios, and it is only the outer 5 km of the basement core that has elemental ratios which approach those found in 'normal' surface granites. The heat generation from the entire exposed vertical section of the Vredefort granite, together with heat production in the overlying stratified rocks, has been examined. By comparing the heat production in the crust to heat flow in the nearby Far West Witwatersrand goldfield, a reasonable estimate of the heat flow from the mantle has been made. A value of between .25 and .36 HFU has been estimated. The mantle heat flow has an important bearing on the depth of the lithosphere - asthenosphere boundary. Whole rock Rb-Sr, Th-Pb isotopic investigations were made on the granite and basic rocks of the Vredefort basement. The measured ages and initial ratios provide evidence that well preserved remnants of sedimentary supracrustals and basic to intermediate volcanics existed as a protocrust in pre-3.5 b.y. times

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

Granite-related Yangjiashan tungsten deposit, southern China

Science.gov (United States)

Xie, Guiqing; Mao, Jingwen; Li, Wei; Fu, Bin; Zhang, Zhiyuan

2018-04-01

The Yangjiashan scheelite-bearing deposit (38,663 metric tons of WO3 with an average ore grade of 0.70% WO3) is hosted in quartz veins in a biotite monzogranite intrusion and surrounding slate in the Xiangzhong Metallogenic Province of southern China. The monzogranite has a zircon SHRIMP U-Pb age of 406.6 ± 2.8 Ma (2σ, n = 20, MSWD = 1.4). Cassiterite coexisting with scheelite yields a weighted mean 206Pb/238U age of 409.8 ± 5.9 Ma (2σ, n = 30, MSWD = 0.20), and molybdenite intergrown with scheelite yields a weighted mean Re-Os age of 404.2 ± 3.2 Ma (2σ, n = 3, MSWD = 0.10). These results suggest that the Yangjiashan tungsten deposit is temporally related to the Devonian intrusion. The δD and calculated δ18OH2O values of quartz intergrown with scheelite range from - 87 to - 68‰, and - 1.2 to 3.4‰, respectively. Sulfides have a narrow range of δ34S values of - 2.9 to - 0.7‰ with an average value of - 1.6‰ (n = 16). The integration of geological, stable isotope, and geochronological data, combined with the quartz-muscovite greisen style of ore, supports a magmatic-hydrothermal origin for the tungsten mineralization. Compared to the more common tungsten skarn, quartz-wolframite vein, and porphyry tungsten deposits, as well as orogenic gold deposits worldwide, the Yangjiashan tungsten deposit is an unusual example of a granite-related, gold-poor, scheelite-bearing quartz vein type of deposit. The calcium needed for the formation of scheelite is derived from the sericitization of calcic plagioclase in the monzogranite and Ca-bearing psammitic country rocks, and the relatively high pH, reduced and Ca-rich mineralizing fluid may be the main reasons for the formation of scheelite rather than wolframite at Yangjiashan.

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)

Sol–gel preparation of selected lanthanide aluminium garnets

Czech Academy of Sciences Publication Activity Database

Dubnikova, N.; Garskaite, E.; Pinkas, J.; Bezdička, Petr; Beganskiene, A.; Kareiva, A.

2010-01-01

Roč. 55, č. 2 (2010), s. 213-219 ISSN 0928-0707 Institutional research plan: CEZ:AV0Z40320502 Keywords : lanthanide aluminium garnets * sol-gel processing Subject RIV: CA - Inorganic Chemistry Impact factor: 1.525, year: 2010

Foliation and the first law of black hole thermodynamics

International Nuclear Information System (INIS)

Siddiqui, Azad A.; Riaz, Syed Muhammad Jawwad; Akbar, M.

2011-01-01

There has been lots of interest in exploring the thermodynamic properties at the horizon of a black hole spacetime. It has been shown earlier that for different spacetimes, the Einstein field equations at the horizon can be expressed as the first law of black hole thermodynamics. Using the idea of foliation, we develop a simpler procedure to obtain such results. We consider r = constant slices, for the Schwarzschild and Reissner-Nordstrom black hole spacetimes. The Einstein field equations for the induced 3-dimensional metrics of the hypersurfaces are expressed in thermodynamic quantities under the virtual displacements of the hypersurfaces. As expected, it is found that the field equations of the induced metric corresponding to the horizon can be written as a first law of black hole thermodynamics. It is to be mentioned here that our procedure is much easier, to obtain such results, as here one has to essentially deal with (n - 1)-dimensional induced metric for an n-dimensional spacetime. (authors)

Nonlinear quantum gravity on the constant mean curvature foliation

International Nuclear Information System (INIS)

Wang, Charles H-T

2005-01-01

A new approach to quantum gravity is presented based on a nonlinear quantization scheme for canonical field theories with an implicitly defined Hamiltonian. The constant mean curvature foliation is employed to eliminate the momentum constraints in canonical general relativity. It is, however, argued that the Hamiltonian constraint may be advantageously retained in the reduced classical system to be quantized. This permits the Hamiltonian constraint equation to be consistently turned into an expectation value equation on quantization that describes the scale factor on each spatial hypersurface characterized by a constant mean exterior curvature. This expectation value equation augments the dynamical quantum evolution of the unconstrained conformal three-geometry with a transverse traceless momentum tensor density. The resulting quantum theory is inherently nonlinear. Nonetheless, it is unitary and free from a nonlocal and implicit description of the Hamiltonian operator. Finally, by imposing additional homogeneity symmetries, a broad class of Bianchi cosmological models are analysed as nonlinear quantum minisuperspaces in the context of the proposed theory

Foliation and the First Law of Black Hole Thermodynamics

International Nuclear Information System (INIS)

Siddiqui, Azad A.; Riaz, Syed Muhammad Jawwad; Akbar, M.

2011-01-01

There has been lots of interest in exploring the thermodynamic properties at the horizon of a black hole spacetime. It has been shown earlier that for different spacetimes, the Einstein field equations at the horizon can be expressed as the first law of black hole thermodynamics. Using the idea of foliation, we develop a simpler procedure to obtain such results. We consider r = constant slices, for the Schwarzschild and Reissner—Nordstrom black hole spacetimes. The Einstein field equations for the induced 3-dimensional metrics of the hypersurfaces are expressed in thermodynamic quantities under the virtual displacements of the hypersurfaces. As expected, it is found that the field equations of the induced metric corresponding to the horizon can be written as a first law of black hole thermodynamics. It is to be mentioned here that our procedure is much easier, to obtain such results, as here one has to essentially deal with (n — 1)-dimensional induced metric for an n-dimensional spacetime. (general)

Geochemistry and petrogenesis of Proterozoic granitic rocks from ...

Indian Academy of Sciences (India)

Geochemistry and petrogenesis of Proterozoic granitic ... This study presents the geochemical characteristics of granitic rocks located on the northern ... Frost and Frost 2013). ...... King P L, White A J R, Chappell B W and Allen C M 1997.

Bonding mechanism of a yttrium iron garnet film on Si without the use of an intermediate layer

International Nuclear Information System (INIS)

Pantzas, Konstantinos; Patriarche, Gilles; Talneau, Anne; Youssef, Jamal Ben

2014-01-01

Direct bonding of yttrium iron garnet (YIG) on silicon without the use of an intermediate bonding layer is demonstrated and characterized using scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy. During the bonding experiment, the garnet is reduced in the presence of oxide-free silicon. As a result, a 5 nm thick SiO 2 /amorphous-YIG bilayer is formed and welds the garnet to silicon.

Wear performance of garnet aluminium composites at high contact pressure

Science.gov (United States)

Sharma, Anju; Arora, Rama; Kumar, Suresh; Singh, Gurmel; Pandey, O. P.

2016-05-01

To satisfy the needs of the engineering sector, researchers and material scientists in this area adopted the development of composites with tailor made properties to enhance efficiency and cost savings in the manufacturing sector. The technology of the mineral industry is shaping the supply and demand of minerals derived materials. The composites are best classified as high performance materials have high strength-to-weight ratios, and require controlled manufacturing environments for optimum performance. Natural mineral garnet was used as the reinforcement of composite because of satisfactory mechanical properties as well as an attractive ecological alternative to others ceramics. For this purpose, samples have been prepared with different sizesof the garnet reinforcement using the mechanical stirring method to achieve the homogeneously dispersed strengthening phase. A systematic study of the effect of high contact pressure on the sliding wear behaviour of garnet reinforced LM13 alloy composites is presented in this paper. The SEM analysis of the worn samples and debris reveals the clues about the wear mechanism. The drastic improvement in the wear resistance of the composites at high contact pressure shows the high potential of the material to be used in engineering applications.

The source rock characters of U-rich granite

Energy Technology Data Exchange (ETDEWEB)

Mingyue, Feng; Debao, He [CNNC Key Laboratory of Uranium Resources Exploration and Evaluation Technology, Beijing Research Institute of Uranium Geology (China)

2012-03-15

This paper discusses the stratum composition, lithological association, uranium content of crust and the activation, migration, concentration of uranium at each tectonic cycle in South China. The authors point out that the source rock of U-rich granite is U-rich continental crust which is rich in Si, Al and K. The lithological association is mainly composed of terrestrial clastic rocks formation of mudstone and sandstone, mingled with intermediate-acidic, mafic pyroclastic rocks and carbonate rocks formation. During tectonic movements, the rocks had undergone regional metamorphism, migmatitization, granitization, and formed U-rich granites finally. (authors)

The source rock characters of U-rich granite

International Nuclear Information System (INIS)

Feng Mingyue; He Debao

2012-01-01

This paper discusses the stratum composition, lithological association, uranium content of crust and the activation, migration, concentration of uranium at each tectonic cycle in South China. The authors point out that the source rock of U-rich granite is U-rich continental crust which is rich in Si, Al and K. The lithological association is mainly composed of terrestrial clastic rocks formation of mudstone and sandstone, mingled with intermediate-acidic, mafic pyroclastic rocks and carbonate rocks formation. During tectonic movements, the rocks had undergone regional metamorphism, migmatitization, granitization, and formed U-rich granites finally. (authors)

The major and trace element geochemistry of garnets from the Vargem 1 Kimberlite pipe, Minas Gerais State, Brazil

International Nuclear Information System (INIS)

Esperanca, S.; Murray, D.C.; Lambert, D.D.

1995-01-01

ICP-MS minor and trace element analysis of four single red garnets and two purple garnet composites show that: Ni contents of the bulk garnets are consistent with temperatures of equilibration in the range of 1050-1100 C; the amount of LREE enrichment appears to correlate with increasing CR contents in the garnets and, overall, the REE patterns of the six samples show normal rather than sinusoidal characteristics; relative to primitive mantle, the incompatible-element enrichment is selective across the samples but Pb shows a positive anomaly relative to La, Ce and Sr. 9 figs., 2 tabs

Neoarchean metamorphism recorded in high-precision Sm-Nd isotope systematics of garnets from the Jack Hills (Western Australia)

Science.gov (United States)

Eccles, K. A.; Baxter, E. F.; Mojzsis, S. J.; Marschall, H.; Williams, M. L.; Jercinovic, M. J.

2013-12-01

Studies of metasedimentary rocks from the Jack Hills, which host Earth's oldest known detrital minerals, have focused on zircon and occasionally monazite or xenotime, but no attention has been directed toward one of the most common mineral markers of metamorphism: garnet. Garnet can provide a record of the post-depositional, prograde metamorphic history of Archean metasedimentary rocks. Additionally, the use of a newly developed detrital garnet dating technique [1,2] may reveal information about pre-depositional metamorphism that could address lingering questions about the nature and timing of Earth's earliest tectonometamorphic events. Here we investigate garnet from the Jack Hills metasedimentary rocks to test whether they record in situ metamorphism or are a detrital relict of even older metamorphic events. We identified garnet in two bulk quartz-pebble conglomerate samples collected from the 'discovery' outcrop at Eranondoo Hill in the Jack Hills of Western Australia. Electron microprobe analyses of polished grains and SEM measurements of unpolished grain surfaces are consistent, revealing garnet composition indicative of a single generation/population of predominantly almandine-spessartine solid solution (~10-35% mole fraction spessartine). Compositional maps of garnet grains reveal little zoning and no discontinuities, most consistent with a single growth event. Dating Jack Hills' garnet via the Sm-Nd system is possible due to continued development of small sample analysis techniques, including running NdO+ TIMS analyses with Ta2O5 activator [3] permitting Ma for two point isochrons between clean garnet (Sm/Nd ≥ 1.0) and their leached inclusion populations [2]. Four grouped garnet grain separates from one sample yield preliminary dates of 2703.6×6.0Ma, 2612.4×6.0Ma, 2605.0×5.5Ma, and 2567.3×8.3Ma, while the second sample yielded a date of 2579.6×4.6 Ma (2σ). Compositional and geochronologic data indicate likely in situ garnet growth during a late

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)

Progade PT path, prograde fluid flow, metasomatism and hydrous melting in the Osor high-grade HT-LP complex (Catalan Coastal Ranges-CCR, NE Iberia).

Science.gov (United States)

Reche, Joan; Martínez, Francisco; Leoz, Gisela

2015-04-01

Fast thermal pulses related to HT-LP metamorphism may imply dehydration reaction overstepping, higher than normal fluid production rates, quick local increases in Pfluid and common situations of Pfluid >> Plitostatic and surpassing locally the tensile stresses. This ambient would be favorable to transient hydrofracturing and fluid flow even if the ongoing HT-LP event develops on dominantly ductile crustal levels. In inner zones where temperatures are high enough, hydrous melting and melt migration would be favored as well. Such movement of fluids and melts would tend to be sustained if non-hydrostatic stresses are active during heating, and would be favored in high strain domains such high-T shear zones or along foliation planes. In such scenario, local metasomatic processes and mass-transfer phenomena are expected to occur along these high strain zones and so distributed along tectonic anisotropies. A variety of features found in high T Garnet - biotite-sillimanite±cordierite±plagioclase±K-feldspar±quartz metapelitic gneisses from the Osor Complex (Guilleries massif, CCR), testify from this kind of processes operating in the lower crustal section, at the amphibolite to granulite transition zone during a prograde Variscan HT-LP thermal pulse. Such features include: syn-D2 quartz veining, leucogranitoid (leucotonalite, trondhjemitic) lenses sub parallel to S2 dominant foliation, fibrolite-rich foliation planes and prograde sub-idiomorphic garnet developing preferentially near fluid migration channels (quartz veins) or near melt lenses.

A 3D Magnetotelluric Perspective on the Galway Granite, Western Ireland

Science.gov (United States)

Farrell, Thomas; Muller, Mark; Vozar, Jan; Feely, Martin; Hogg, Colin

2017-04-01

Magnetotelluric (MT) and audi-magnetotelluric (AMT) data were acquired at 75 locations across the exposed calc-alkaline Caledonian Galway granite batholith and surrounding country rocks into which the granite intruded. The Galway granite is located in western Ireland on the north shore of Galway bay, and has an ESE-WNW long axis. The granite is cut by trans-batholith faults, the Shannawona Fault Zone (SFZ) in the western part of the batholith, which has a NE-SW trend, and the Bearna Fault Zone (BFZ) in the eastern sector that has a NW-SE trend. Geobarometry data indicate that the central granite block between these fault zones has been uplifted, with the interpretation being that the granite in this central block is thinned. To the west of the SFZ, much of the Galway granite is below sea level, with the majority of the southern granite contact also beneath the sea in Galway bay. To the east of the batholith, the Carboniferous successions, consisting of mainly limestone with shale, overlie the basement rocks. The country rock to the north includes the metagabbro-gneiss suite, which itself intruded the deformed Dalradian successions that were deposited on the Laurentian margin of the Iapetus Ocean. The deformation of the Dalradian rocks, the intrusion of the metagabbro-gneiss suite and the intrusion of the Galway granite were major events in the protracted closure of the Iapetus Ocean. It is clear from geological mapping, from geobarometry and from the present submergence by the sea of a large part of the Galway granite, that inversion of MT data in this structurally complex geology is likely to require a 3D approach. We present a summary of 3D inversion of the Galway MT and AMT data. The study shows that the structure of the Galway granite is quite different from the pre-existing perspective. The central block, thought by its uplifting to be thinned, is shown to be the thickest part of the batholith. A geological model of granite intrusion is offered to explain this

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

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.)

Geology and petrography of basement in south extreme in Sierra Grande de San Luis, Argentina

International Nuclear Information System (INIS)

Morosini, A.; Ortiz Suarez, A.

2007-01-01

In the south of the Sierra de San Luis is recognized a basement composed by La Escalerilla and Los Puquios granites, accompanied by schist, mylonite s and mafic-ultramafic rocks. The schists, La Escalerilla granite and the mafic -ultramafic rocks are affected by a regional metamorphism in anphibolites facies, the two first present a N-S foliation di ping to east. The mylonite s correspond to a second event of deformation, distributed in thin belts of NNE-SSO direction and inclination to east, developed in green schist to anphibolites facies. Los Puquios granite represents the more young of the basement rocks and the intrusion was associated with a shear zone. Los Puquios granite forms dikes and small plutons cutting La Escalerilla granite and micas chits in high cortical levels

Protracted deformation during cooling of the Paleoproterozoic arc system as constrained by {sup 40}Ar/{sup 39}Ar ages of muscovite from brittle faults: the Transamazonan Bacajá Terrane, Brazil

Energy Technology Data Exchange (ETDEWEB)

Perico, Edimar; Barros, Carlos Eduardo de Mesquita; Mancini, Fernando [Universidade Federal do Paraná – UFPR, Curitiba, PR (Brazil); Rostirolla, Sidnei Pires, E-mail: sidneiprostirolla@gmail.com [Rosneft, Rio de Janeiro, RJ (Brazil)

2017-07-15

In the Paleoproterozoic Transamazonas Province, synkinematic granitogenesis has taken place synchronously with compressive tectonic stress. The synkinematic character of the granites is marked by their WNW elongate shape, and by the presence of pervasive and concordant synmagmatic foliation. Ductile shear zones are concordant to the previous regional WNW structures, and tend to be accommodated along contacts between Rhyacian synkinematic granitoids and both Archean orthogneisses and Siderian metabasites. Locally phyllonitic shear zones and brittle-ductile shear zones with cataclasites are oriented subparallel to the preexisting ductile foliation. Late orogenic brittle faults N30E-trending strike-slip faults are either sinistral or destral. {sup 40}Ar/{sup 39}Ar dating of muscovite developed on fault planes gave ages of 1977 ± 8 Ma and 1968 ± 11 Ma. Structural and geochronological data from rocks of the Transamazonas Province permit to conclude that most mylonites and brittle structures were controlled by preexisting structures such as geological contacts and petrographic facies boundaries. Compressive tectonic stress would have initiated at ca. 2100 Ma, since the former magmatic arc (Bacajaí complex), still present at 2070 Ma when syntectonic granites were emplaced and remained until 1975 Ma after granite plutonism and regional cooling. (author)

Movement of fossil pore fluids in granite basement, Illinois

International Nuclear Information System (INIS)

Couture, R.A.; Seitz, M.G.

1986-01-01

The compositions of pore fluids in granite cores from the Precambrian basement in northern Illinois were determined. The estimated chloride concentration in the aqueous phase increases from near zero at the upper contact with sandstone to 2.7 M at 624 m below the contact. Traces of aliphatic oil are present in the overlying sandstone and the upper 516 m of granite, and oil occupies most of the pore space in one sample of unaltered granite 176 m below the contact. The oil has a Δ 13 C of -25%, about the same as average petroleum. The high concentrations of salt more than 500 m below the contact imply that little or no fresh water has reached these levels of the granite by flow. Lower concentrations near the contact are consistent with replacement of brine in the sandstone by fresh water at least 11 m.y. ago and subsequent upward diffusion of salt from the granite. Geologic data suggest that the time of replacement was about 130 Ma. The purpose of the investigation is to study the record of movement of intergranular fluids within a granite pluton. The composition and movement of ground waters can determine the extent that hazardous or radioactive wastes disposed in igneous rock will remain isolated

Influence of chromium ions on the color center formation in crystals with garnet structure

International Nuclear Information System (INIS)

Ashurov, M.Kh.; Zharikov, E.V.; Laptev, V.V.

1985-01-01

The in fluence of chromium ions on the color center formation in crystals of yttrium-aluminium garnet, gadolinium-gallium garnet, gadolinium-scandium-gallium garnet, and yttrium-scandium-gallium garnet is studied. In addition to basic activator ions these crystals were coactivated also by chromium ions with two wide bands of fundamental absorption within the range of pump tube radiation with maximas close to 450 and 650 nm. The color centers for γ-irradiated samples were observed at 300 K by measuring the adsorption spectra within the 300-800 nm range. Temperature of destruction of the charge trapping sites was determined by the method of thermoluminescence measuring in the 100-500 K temperature range. Detection of recombination center luminescence was accomplished within the 200-1600 nm wavelength range. Chromium ions are found to hinder the formation of color centers as a result of γ-irradiation at room and higher temperatures within the wavelength range over 300 nm; i.e. Cr 3+ ions increase radiation resistance of all the investigated crystals

Strain Distribution in a Partially Molten Crust: Insights from the AMS Study of Carlos Chagas Anatexite, ARAÇUAI Belt (se Brazil)

Science.gov (United States)

Cavalcante, G.; Silva, M.; Vauchez, A. R.

2012-12-01

Anatectic domains, characterized by abundant migmatites, represent portions of the middle crust that have been partially molten. The Carlos Chagas anatexite is a unit that includes diatexites, metaxites and anatetic, peraluminous granites. It is localized in eastern domain of the Araçuaí Belt, which was formed during the amalgamation of West Gondwana by the collision of the Sao Francisco and Congo cratons. This orogenic segment underwent a synkinematic high temperature (>750oC)-low pressure (~ 6MPa) metamorphism that causes widespread partial melting of the middle crust. The Carlos Chagas unit is composed by quartz, feldspar, garnet, biotite, sillimanite, ilmenite, rutile and cordierite. U-Pb data indicates that its crystallization occurred c. a. 574 ~ 3 Ma. The main feature of this migmatite is the presence of a pervasive magmatic foliation, which is marked by the preferential alignment of biotite, alkali feldspars and plagioclase. At the grain scale, quartz displays evidence of interstitial crystallization and few solid-state deformation fabrics are observed. We used anisotropy of magnetic susceptibility (AMS) as a tool for recovering mineral fabric and thus the flow field of the Carlos Chagas anatexite. Magnetic properties of 153 samples were measured. They yield dominantly low values of the bulk magnetic susceptibility (km 0) being dominantly more frequent than prolates ones. These magnetics characteristics are consistent with biotite being the dominant carrier of the AMS. Magnetic foliations and lineations suggest two main structural patterns. The northern portion of the studied area shows shallowly plunging lineations (02° - 20°) to SE (140°-120°) or NW (340°-300°), while the foliation strikes NW-SE with shallow dips (03°-10°). Local subvertical foliation dips (70°) are due to NE-SW trending transcurrent shear zones. The southern region shows complex magnetic fabric patterns. Magnetic lineation plunges range from 05° to 58°, in varied directions

Limit of the radionuclides in granite

International Nuclear Information System (INIS)

Wang Shaling; Jiang Rangrong

2003-01-01

Granite is an important sort of building materials. Their radionuclide contents are limited by the national standard GB6566-2001 just as other building materials. This standard divides them into main materials and decorative materials, and relaxes the limit of the latter obviously. Owing to the consideration of public dose limit and environment protection, this method needs discussion. Otherwise, red granite contains high radionuclide contents relatively, especially the sort of Indian Red, and need be paid more attention

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

Investigations of garnets from polymetamorphic rocks of the Lapland Granulite Belt of the Kandalaksha Region

Directory of Open Access Journals (Sweden)

Miłosz A. Huber

2012-01-01

Full Text Available Introduction: The Lapland Granulite Belt is placed on the Kandalaksha region (Kola Peninsula, Russia. The rocks of this Belt are composed mainly of amphibolites and granulites.Materials and methods: The research were focused on the garnets from the amphibolite and granulite rocks of Lapland Granulite Belt. The petrological methods like polarizing microscopy (PM, SEM-EDS, XRD for powdered samples and single crystal diffraction were used together with IR and Mössbauer spectroscopy and REE analysis by ion–microprobe.Results: It was found that the garnets from studied amphibolite and granulite rocks could be classified to pyralspite group without hydrogarnets components, so they were formed in high metamorphic facies.Conclusions: The joint geological observations and results of the performed experiments suggest that the garnets were subject of a blastesy, i.e. there were formed in long lasting metamorphic processes of low dynamics, except of those garnets from tectonic zones, found in the vicinity of mineral veins.

Lower crustal xenoliths, Chinese Peak lava flow, central Sierra Nevada.

Science.gov (United States)

Dodge, F.C.W.; Calk, L.C.; Kistler, R.W.

1986-01-01

This assemblage of pyroxenite, peridotite and mafic granulite xenoliths in the toe of a 10 m.y. trachybasalt flow remnant overlying late Cretaceous granitic rocks, indicates the presence of a mafic-ultramafic complex beneath this part of central California; orthopyroxenites, websterites and clinopyroxenites are dominant. A few of the xenoliths contain ovoid opaque patches that are apparently pseudomorphs after garnet and have pyralspite garnet compositions; using a garnet-orthopyroxene geobarometer, they indicate a lower crustal depth of approx 40 km. Abundant mafic granulites can be subdivided into those with Al2O3 = or 15% and showing considerable scatter on oxide variation diagrams. The high-alumina granulite xenoliths have relatively low 87Rb/86Sr but high 87Sr/86Sr, whereas the low-alumina and ultramafic xenoliths have a wide range of 87Rb/86Sr, but lower 87Sr/86Sr; the isotopic data indicate roughly the same age as that of overlying granitic plutons (approx 100 m.y.). However, the granitic rocks have initial 87Sr/86Sr ratios intermediate between those of the high-alumina and ultramafic xenoliths, suggesting that they result from the mixing of basaltic magma (represented by the ultramafic rocks) and crustal materials, with subsequent crystal fractionation.-R.A.H.

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)

Compositional controls on spinel clouding and garnet formation in plagioclase of olivine metagabbros, Adirondack Mountains, New York

Science.gov (United States)

McLelland, J.M.; Whitney, P.R.

1980-01-01

Olivine metagabbros from the Adirondacks usually contain both clear and spinel-clouded plagioclase, as well as garnet. The latter occurs primarily as the outer rim of coronas surrounding olivine and pyroxene, and less commonly as lamellae or isolated grains within plagioclase. The formation of garnet and metamorphic spinel is dependent upon the anorthite content of the plagioclase. Plagioclase more sodic than An38??2 does not exhibit spinel clouding, and garnet rarely occurs in contact with plagioclase more albitic than An36??4. As a result of these compositional controls, the distribution of spinel and garnet mimics and visually enhances original igneous zoning in plagioclase. Most features of the arrangement of clear (unclouded) plagioclase, including the shells or moats of clear plagioclase which frequently occur inside the garnet rims of coronas, can be explained on the basis of igneous zoning. The form and distribution of the clear zones may also be affected by the metamorphic reactions which have produced the coronas, and by redistribution of plagioclase in response to local volume changes during metamorphism. ?? 1980 Springer-Verlag.

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

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.

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

Uranium-thorium disequilibria and partitioning on melting of garnet peridotite

International Nuclear Information System (INIS)

Beattie, P.

1993-01-01

The abundances of isotopes in the 238 U decay series can be used as both tracers and chronometers of magmatic processes. In the subsolidus asthenosphere, the activity of each daughter isotope (defined as the product of its concentration and decay constant, and denoted by parentheses) is assumed to be equal to that of its parent. By contrast, ( 230 Th/ 238 U) is greater than unity in most recent mid-ocean-ridge and ocean-island basalts, implying that thorium is more incompatible (that is, it is partitioned into the melt phase more strongly) than uranium. Melting of spinel peridotite cannot produce the ( 230 Th) excesses, because measured partition coefficients for pyroxenes and olivine demonstrate that uranium is more incompatible than thorium for this rock. Here I report garnet-melt partitioning data which show that for this mineral-melt pair thorium does behave more incompatibility than uranium, thus supporting the suggestion that mid-ocean-ridge basalts (MORB) are produced by melting initiated at depths where garnet is stable. Using these data, I show that the observed ( 230 Th/ 238 U) ratios of MORB and most ocean-island basalts can be explained by slow, near-fractional melting initiated in the garnet stability field. (author)

Present understanding of the stability of Li-stuffed garnets with moisture, carbon dioxide, and metallic lithium

Science.gov (United States)

Hofstetter, Kyle; Samson, Alfred Junio; Narayanan, Sumaletha; Thangadurai, Venkataraman

2018-06-01

Fast lithium-ion conducting garnet-type metal oxides are promising membranes for next-generation all-solid-state Li batteries and beyond Li-ion batteries, including Li-air and Li-S batteries, due to their high total Li-ion conductivity and excellent chemical stability against reaction with elemental Li. Several studies have been reported on structure-chemical composition-ionic conductivity property in Li-stuffed garnet-type metal oxides. Here, an overview of the chemical and electrochemical stability of lithium-based garnets against moisture/humidity, aqueous solutions, carbon dioxide, sulfur, and metallic lithium are analyzed. Moisture and aqueous stability studies focus on understanding the crystal structure stability, the proton exchange capacity as a function of Li content in Li-stuffed garnets, and how the protonated species affect the crystal structure and mass transport properties. H+/Li+ exchange was found to be in the range of 2-100%. Stability concerning Li-ion conductivity and morphology under carbon dioxide are discussed. Interfacial chemical stability with lithium metal characterized by electrochemical stability window, Li dendrite formation and area specific resistance (ASR) for the reaction Li ⇌ Li+ +e- are presented. Recent attempts to suppress dendrite formation and to reduce ASR via surface modification are also highlighted. Li and Li-stuffed garnet interface ASR values are shown to be as high as >2000 Ω cm2 and as low as 1 Ω cm2 at room temperature for surface modified Li-stuffed samples. Furthermore, recent studies on Li-S battery utilizing chemically stable Li - garnet electrolyte are also discussed.

Functional and comparative study of lingual papillae in four species of bear (Ursidae) by scanning electron microscopy.

Science.gov (United States)

Pastor, J F; Barbosa, M; de Paz, F J; García, M; Ferrero, E

2011-10-01

The eight current species of bear (Ursidae) are widely distributed throughout Europe, Asia, and America. They are mainly encountered in the northern hemisphere, except for the spectacled bear and the sun bear, which are also found in the south of the equator. Adaptations of the masticatory apparatus (teeth, tongue, and musculature) to diet are one of the factors that imply the greatest structural changes in the cranium. This diet may be carnivorous, herbivorous, melliferous, or insectivorous, with one type of food predominating according to the time of year. The way in which food is eaten determines the morphology of the lingual surface; generally speaking, all bears put their mouth to the food, which, initially, they lick or they let the food stick to their tongue, as occurs when insects are eaten. As in all mammals, a distinction can be made between mechanical and gustatory papillae and the development and distribution of which depend on the species and their eating habits. In this study of the complete tongues of four species of adult bears, we describe the morphology of the lingual surfaces, the different types of papillae, their characteristics, and topographic distribution. It was seen that there were five main types of lingual papillae: filiform, conical, fungiform, foliate, and vallate. Morphology of the microgrooves and pores was similar to that observed in other mammals. In general, there were no great differences among the four species of bears studied, perhaps due to the similarity in the kind of food they consume in captivity. Copyright © 2011 Wiley-Liss, Inc.

Granite Exfoliation, Cosumnes River Watershed, Somerset, California

Science.gov (United States)

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

2015-12-01

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

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

Coercive force features in stressed epitaxial ferrite-garnet films

International Nuclear Information System (INIS)

Dubinko, S.V.; Nedviga, A.S.; Vishnevskij, V.G.; Shaposhnikov, A.N.; Yagupov, V.S.; Nesteruk, A.G.; Prokopov, A.R.

2005-01-01

One has investigated into effect of a relative mismatching of periods of lattices of a film and of a substrate within 0.5-0.85% range on behavior of the coercive force of (Bi, Sm, Lu, Ca) 3 (Fe, Sc, Ga, Al) 5 O 12 composition ferrite garnet epitaxial films (FGEF) synthesized at (111) orientation gadolinium-gallium garnet substrates. One has revealed that the FGEF coercive force at increase of the relative mismatching of periods of lattices of a film and of a substrate increases at first, while when reaching the maximum value it begins to decrease. The coercive force maximum value is shown to result from the periodical localized stresses. The period of the localized stresses is determined by the value of mismatching of periods of lattices of a film and of a substrate [ru

Weathering-related origin of widespread monazite in S-type granites

Energy Technology Data Exchange (ETDEWEB)

Sawka, W N; Banfield, J F; Chappell, B W

1986-01-01

The S-type granite suites comprising more than a quarter of the extensively developed granites in the Lachlan Fold Belt, Australia, contain monazite which may be related to the chemical weathering of the sedimentary source rocks. We report a process whereby chemical weathering fixes mobile rare-earth elements (REE) in hydrous phosphate phases such as florencite and rhabdophane. This material contains up to 50 wt.% LREE and occurs as very small particles (approx. 3 ..mu..m). Dehydration of these hydrous REE phases during anatexis directly yields monazite. The low solubility of phosphorus in S-type granite melts inhibits dissolution of both monazite and apatite. Refractory monazite may be thus entrained and transported in S-type granites in a manner similar to processes resulting in inherited zircon. Since both Th and the light REE are major components in monazite, materials containing this minute phase may be of widespread geochemical significance in both granites and metamorphic rocks.

Garnet film rotator applied in polarizing microscope for domain image modulation (abstract)

Science.gov (United States)

Wakabayashi, K.; Numata, T.; Inokuchi, S.

1991-04-01

A garnet film polarization rotator placed before the analyzer in a polarizing microscope was investigated to obtain the difference image of a positive and a negative one of magnetic domain in real time along with an image processor. In the difference image, a nonmagnetic image can be reduced and hence the weak magnetic contrast enhanced. Theoretical calculation of S/N and contrast C of the domain image as a function of the rotation shows they take maxima at the rotation angle of 2.6° and 0.1°, respectively, with the extinction ratio of e=4×10-6 of a polarizing microscope. Thus, since the thickness of the garnet film required is 1 μm or so, the absorption by the garnet rotator does not bring a serious problem even in a visible region for the domain observation. The optimum rotation of the rotator for a high quality observation was obtained by a quantitative study of images obtained experimentally as well as by a visual evaluation. A magnetically unsaturated garnet film with perpendicular magnetization (i.e., multidomain) was employed as a rotator, in which the polarization rotation angle θm of the undeflected beam with respect to the light diffraction could be continuously varied by an applied magnetic field. The dependences of S/N and C on θm were measured, resulting in a well agreement between the measured and the calculated. The visually best image was obtained at θm=0.5° which made the product of S/N and C maximum. The domain image of the Kerr rotation angle of θk=0.22° was observed in S/N=47 dB and C=0.4 when Ar+ laser (λ=515 nm) of tenths of a watt was employed as a light source. Since the domain image with 47 dB S/N does not need an image summation for a noise reduction, a garnet film rotator makes it possible to invert the contrast of a domain image in a real time for an improved domain observation.

Study of relaxation processes and uniaxial anisotropy in the Europium Gallium Garnet epitaxial films

International Nuclear Information System (INIS)

Mukhopadhyay, P.

1987-04-01

We report here the magnetic properties of Europium-Gallium Garnet LPE films of the type Eu x Y 3-x Fe 5-y Ga y O 12 (where O< x<1.2 and 1< y<1.1). The mechanism by which the magnetic moments relax in Eu or Sm Garnets is still not fully understood. We have made studies on Eu-Ga garnet films and explain some of the results observed in these films. Pb and Pt ions are always found as impurities in our films. Pb ions contribute to the anisotropy in the film. Most of the experimental results can be explained with the three sub lattice model. The shape of the FMR line width shows strong sensitivity towards the surface impurities. (author). 18 refs, 6 figs, 1 tab

Computational modelling of Er(3+): Garnet laser materials

Science.gov (United States)

Spangler, Lee H.

1994-01-01

The Er(3+) ion has attracted a lot of interest for four reasons: (1) Its (4)I(sub 13/2) yields (4)I(sub 15/2) transition lases in the eyesafe region near 1.5 micron; (2) the (4)I(sub 13/2) transition lases near 2.8 micron, an important wavelength for surgical purposes; (3) it displays surprisingly efficient upconversion with lasing observed at 1.7, 1.2, 0.85, 0.56, 0.55, and 0.47 micron following 1.5 micron pumping; and (4) it has absorption bands at 0.96 and 0.81 micron and thus can be diode pumped. However, properties desirable for upconversion reduce the efficiency of 1.5 and 3 micron laser operation and vice versa. Since all of the processes are influenced by the host via the crystal field induced stark splittings in the Er levels, this project undertook modelling of the host influence on the Er lasinng behavior. While growth and measurement of all ten Er(3+) doped garnets is the surest way of identifying hosts which maximize upconversion (or conversly, 1.5 and 3 micron performance), it is also expensive - costing approximately $10,000/material or approximately $100,000 for the materials computationally investigated here. The calculations were performed using a quantum mechanical point charge model developed by Clyde Morrison at Harry Diamond Laboratories. The programs were used to fit the Er:YAG experimental energy levels so that the crystal field parameters, B(sub nm) could be extracted. From these radial factors, rho (sub n) were determined for Er(3+) in garnets. These, in combination with crystal field components, Anm, available from X-ray data, were used to predict energy levels for Er in the other nine garnet hosts. The levels in Er:YAG were fit with an rms error of 12.2/cm over a 22,000/cm range. Predicted levels for two other garnets for which literature values were available had rms errors of less than 17/cm , showing the calculations to be reliable. Based on resonances between pairs of calculated stark levels, the model predicts GSGG as the best host

Investigation on the elastic properties of Gd-Sc-Al garnet by the Mandelstam-Brillouin light scattering method

International Nuclear Information System (INIS)

Zharikov, E.V.; Zagumennyj, A.I.; Kitaeva, V.F.; Lutts, G.B.; Terskov, D.B.

1991-01-01

The Gd-Sc-Al garnet (GSAG) crystals grown from the melt with composition Gd 2.88 Sc 1.89 Al 3.23 O 12 , were investigated. The GSAG doped with chromium was also studied. The Mandelstam-Brillouin (MB) light scattering in the GSAG crystals was observed. The garnet elastic components were determined using the data on the MB component shifts, the products of the elastic constants by molar volume were calculated as well. The GSAG is elastically anisotropic. The doping addition introduction do not cause noticeable change in the elastic properties. The obtained values of elastic constants and their combinations for GSAG were compared with the data for aluminium and gallium garnets. The comparison has shown that the values of elastic constants for GSAG is closer to those for Gd-Sc-Ga garnet than to the corresponding values for the Y-Al one

Age and composition of the UHP garnet peridotites in the Dabie orogenic belt (central China) record complex crust-mantle interaction in continental margin

Science.gov (United States)

Zhao, Y.; Zheng, J.; Wang, B.

2017-12-01

The Dabie-Sulu UHP belt was created by the collision between the North and South China cratons in Middle Triassic time (240-225 Ma). There are lots of garnet-bearing ultramafic body occurs as a lens in the belt. Age and composition of the Maowu garnet peridotites in the Dabie orogenic belt are reported. The garnet harzburgites are main moderately refractory (Mg#Ol=92) and minor fertile (Mg#Ol=88) with high Ni (2344-2603 ppm) and low Al2O3 (0.35-0.54 wt.%), CaO (0.76-2.19 wt.%) and TiO2 (˜0.01 wt.%). Zircons in the harzburgites mainly document metamorphism at 230 ± 2 Ma, 275 ± 5 Ma, 357 ± 4 Ma, and complex minor populations of ages including: 1.8 Ga, 1.3 Ga, and Neoproterozic-early Paleozoic ages (901-420 Ma). The early Meszosic and late Paleozoic zircons have similar trace-element patterns and ranges in ɛHf(t) (+0.6 to +3.4), Th/U ratio (0.2-0.7) and Hf depleted-mantle model ages (TDM ) mainly cluster in the interval 1.2-0.9 Ga. In contrast, the Paleo-Mesoproterozoic zircons have negative ɛHf(t) (-24.9 to -2.7) and oldest Hf TDM = 3.4Ga. Zircons of Neoproterozic-early Paleozoic have a wide range of Hf depleted-mantle model ages (2.4-0.7Ga) and ɛHf(t) (-15.3 to +9.5). Above of the all, we suggest that the Maowu garnet harzburgites are interpreted as a fragment of the metasomatized ancient lithospheric mantle beneath the southern margin of the North China Craton. They experienced the Proterozoic thermal event (1.9-1.8Ga), which is coeval with the assembly of the supercontinent Columbia. And then 1.3Ga mantle metasomatism with asthenospheric materials resulted in the final breakup of the Columbia supercontinent. Neoproterozic-early Paleozoic (901-420 Ma), deep parts of the south margin of the craton were metasomatized during the assembly and breakup of the Rodinia supercontinent. Then, the southern margin of the craton occurred oceanic crust subduction ( 357 Ma), subsequent continental deep subduction and final continent-continent collision in Triassic.

Geochemistry, mineralogy, and zircon U-Pb-Hf isotopes in peraluminous A-type granite xenoliths in Pliocene-Pleistocene basalts of northern Pannonian Basin (Slovakia)

Science.gov (United States)

Huraiová, Monika; Paquette, Jean-Louis; Konečný, Patrik; Gannoun, Abdel-Mouhcine; Hurai, Vratislav

2017-08-01

Anorogenic granite xenoliths occur in alkali basalts coeval with the Pliocene-Pleistocene continental rifting of the Pannonian Basin. Observed granite varieties include peraluminous, calcic to peralkalic, magnesian to ferroan types. Quartz and feldspars are dominant rock-forming minerals, accompanied by minor early ilmenite and late magnetite-ulvöspinel. Zircon and Nb-U-REE minerals (oxycalciopyrochlore, fergusonite, columbite) are locally abundant accessory phases in calc-alkalic types. Absence of OH-bearing Fe, Mg-silicates and presence of single homogeneous feldspars (plagioclase in calcic types, anorthoclase in calc-alkalic types, ferrian Na-sanidine to anorthoclase in alkalic types) indicate water-deficient, hypersolvus crystallization conditions. Variable volumes of interstitial glass, absence of exsolutions, and lacking deuteric hydrothermal alteration and/or metamorphic/metasomatic overprint are diagnostic of rapid quenching from hypersolidus temperatures. U-Pb zircon ages determined in calcic and calc-alkalic granite xenoliths correspond to a time interval between 5.7 and 5.2 Ma. Positive ɛHf values (14.2 ± 3.9) in zircons from a 5.2-Ma-old calc-alkalic granite xenolith indicate mantle-derived magmas largely unaffected by the assimilation of crustal material. This is in accordance with abundances of diagnostic trace elements (Rb, Y, Nb, Ta), indicating A1-type, OIB-like source magmas. Increased accumulations of Nb-U-REE minerals in these granites indicate higher degree of the magmatic differentiation reflected in Rb-enrichment, contrasting with Ba-enrichment in barren xenoliths. Incipient charnockitization, i.e. orthopyroxene and ilmenite crystallization from interstitial silicate melt, was observed in many granite xenoliths. Thermodynamic modeling using pseudosections showed that the orthopyroxene growth may have been triggered by water exsolution from the melt during ascent of xenoliths in basaltic magma. Euhedral-to-skeletal orthopyroxene growth

Geochemistry of biotite granites from the Lamas de Olo Pluton, northern Portugal

Science.gov (United States)

Fernandes, Susana; Gomes, Maria; Teixeira, Rui; Corfu, Fernando

2013-04-01

In the Central Iberian Zone (CIZ) extensive crustal recycling occurred during the post-thickening extension stage of the Variscan orogeny (~330-290 Ma). After the ductile deformation phase D3 (~320-300 Ma), characterized by the intrusion of large volumes of highly peraluminous granitic magmas, rapid and drastic tectonic changes at about 300 Ma gave rise to the brittle phase of deformation D4 that controlled the emplacement of Fe-K subalkaline granites (296-290 Ma; Dias et al. 1998). The Lamas de Olo Pluton (LOP) is controlled by NE-SW and NW-SE fracture systems, probably related to the Régua-Verin fault zone (Pereira, 1989). The LOP is a medium to coarse-grained, porphyritic biotite granite, accompanied by medium- to fine grained, porphyritic biotite granite (Alto dos Cabeços- AC) and a more leucocratic, fine-grained, slightly porphyritic biotite-muscovite granite (Barragens- BA). The contacts between LO and AC are generally diffuse, whereas those to BA are sharp. In fact, the BA granite can occur in dykes and sills cutting LO and AC. Microgranular enclaves and xenoliths are very rare. The LOP intrudes the Douro Group, presumably of Precambrian to Cambrian age, and two-mica granites from the Vila Real composite massif. The LOP granites consist of quartz, microcline, plagioclase, biotite, zircon, titanite, tourmaline apatite, fluorite, ilmenite, magnetite, and rutile, with muscovite in BA granite and rare allanite in the LO and AC granites. The plagioclase composition is of oligoclase (An12) - andesine (An35) for LO granite, albite (An9) - andesine (An30) for CA granite and albite (An5) - oligoclase (An20) for BA granite. There are decreases in: a) anorthite content from phenocryst to matrix plagioclase; b) Ba content from phenocryst to matrix microcline in all granites. The Fe2+ biotite has a composition similar to that of biotite from calc-alkaline to sub-alkaline rock series. The LO and AC granites are meta- to peraluminous with ASI variable between 1.05 and 1

Dazai super-large uranium-bearing germanium deposit in western Yunnan region metallogenic geological conditions and prospect

International Nuclear Information System (INIS)

Han Yanrong; Yuan Qingbang; Li Yonghua; Zhang Ling; Dai Jiemin

1995-05-01

The Dazai super-large uranium-bearing germanium deposit is located in Bangmai Fault Basin, Western Yunnan, China. The basin basement is migmatitic granite and the cover is miocene coal-bearing clastics, Bangmai Formation. The basin development had undergone faulted rhombus basin forming, synsedimentary structure-developing and up-lifted-denuded stages. Synsedimentary faults had controlled distribution of sedimentary formation and lithofacies, and uranium and germanium mineralization. Germanium ore-bodies occur mainly in master lignite-bed of lower rhythmite. Hosted germanium-lignite is taken as main ore-type. Germanium occurs in vitrinite of lignite in the form of metal-organic complex. The metallogenetic geological conditions of the deposit are that ground preparation is uplift zone-migmatitic granite-fault basin-geothermal anomaly area, rich and thick ore-body is controlled by synsedimentary fault, peat-bog phase is favorable to accumulation for ore-forming elements, and unconformity between overlying cover and underlying basement is a channel-way of mineralizing fluid. A multiperiodic composite, being regarded sedimentation and diagenesis as a major process, uranium and germanium ore deposit has been formed through two mineralization. Four prospecting areas have been forecasted and two deposits have been accordingly discovered again. Technical-economic provableness shows that the deposit is characterized by shallow-buried, rich grade, large scale, easy mining and smelting. (9 figs.)

Granites of Zoz area, Baroda district, Gujarat and its economic significance

International Nuclear Information System (INIS)

Maithani, P.B.; Rathaiah, Y.V.; Varughese, Siby K.; Singh, Rajendra

1998-01-01

The granites around Zoz represent a differentiated, calc-alkaline, subaluminous, A-type granite with higher uranium content. The A-type affinity points to the possibility of encountering Sn, Mo, Bi, Nb, Ta and F mineralization in the area. The low Th/U ratio also favours vein type U-deposits within granites or in adjacent metasediments. (author)

Quantifying elemental compositions of primary minerals from granitic rocks and saprolite within the Santa Catalina Mountain Critical Zone Observatory

Science.gov (United States)

Lybrand, R. A.; Rasmussen, C.

2011-12-01

Granitic terrain comprises a significant area of the earth's land surface (>15%). Quantifying weathering processes involved in the transformation of granitic rock to saprolite and soil is central to understanding landscape evolution in these systems. The quantification of primary mineral composition is important for assessing subsequent mineral transformations and soil production. This study focuses on coupling detailed analysis of primary mineral composition to soil development across an array of field sites sampled from the Santa Catalina Mountain Critical Zone observatory (SCM-CZO) environmental gradient. The gradient spans substantial climate-driven shifts in vegetation, ranging from desert scrub to mixed conifer forests. The parent material is a combination of Precambrian and Tertiary aged granites and quartz diorite. Primary mineral type and composition are known to vary among the various aged granitic materials and this variability is hypothesized to manifest as significant variation in regolith forming processes across the SCM-CZO. To address this variability, the mineral composition and mineral formulae of rock and saprolite samples were determined by electron microprobe chemical analyses. The rocks were pre-dominantly quartz, biotite, muscovite, orthoclase and calcium/sodium-rich plagioclase feldspars. Trace minerals observed in the samples included sphene, rutile, zircon, garnet, ilmenite, and apatite. Mineral formulae from electron microprobe analyses were combined with quantitative x-ray diffraction (QXRD) and x-ray fluorescence (XRF) data to quantify both primary and secondary mineralogical components in soil profiles from each of the field sites. Further, electron microprobe analyses of <2mm mixed conifer saprolite revealed weathered plagioclase grains coated with clay-sized particles enriched in silica and aluminum (~25% and 15%, respectively), suggesting kaolin as the secondary phase. The coatings were interspersed within each plagioclase grain, a

The Effect of fO2 on Partition Coefficients of U and Th between Garnet and Silicate Melt

Science.gov (United States)

Huang, F.; He, Z.; Schmidt, M. W.; Li, Q.

2014-12-01

Garnet is one of the most important minerals controlling partitioning of U and Th in the upper mantle. U is redox sensitive, while Th is tetra-valent at redox conditions of the silicate Earth. U-series disequilibria have provided a unique tool to constrain the time-scales and processes of magmatism at convergent margins. Variation of garnet/meltDU/Th with fO2 is critical to understand U-series disequilibria in arc lavas. However, there is still no systematic experimental study about the effect of fO2 on partitioning of U and Th between garnet and melt. Here we present experiments on partitioning of U, Th, Zr, Hf, Nb, Ta, and REE between garnet and silicate melts at various fO2. The starting material was hydrous haplo-basalt. The piston cylinder experiments were performed with Pt double capsules with C-CO, MnO-Mn3O4 (MM), and hematite-magnetite (HM) buffers at 3 GPa and 1185-1230 oC. The experiments produced garnets with diameters > 50μm and quenched melt. Major elements were measured by EMPA at ETH Zurich. Trace elements were determined using LA-ICP-MS at Northwestern University (Xi'an, China) and SIMS (Cameca1280 at the Institute of Geology and Geophysics, Beijing, China), producing consistent partition coefficient data for U and Th. With fO2 increasing from CCO to MM and HM, garnet/meltDU decreases from 0.041 to 0.005, while garnet/meltDTh ranges from 0.003 to 0.007 without correlation with fO2. Notably, garnet/meltDTh/U increases from 0.136 at CCO to 0.41 at HM. Our results indicate that U is still more compatible than Th in garnet even at the highest fO2 considered for the subarc mantle wedge (~NNO). Therefore, we predict that if garnet is the dominant phase controlling U-Th partitioning during melting of the mantle wedge, melts would still have 230Th excess over 238U. This explains why most young continental arc lavas have 230Th excess. If clinopyroxene is the dominant residual phase during mantle melting, U could be more incompatible than Th at high fO2

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.

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.

Magnetic losses and instabilities in ferrite garnet tuned RF cavities for synchrotrons

International Nuclear Information System (INIS)

Shapiro, V.E.

1994-01-01

The aim of this paper is to introduce basic notions and elucidate the main features of magnetic losses and nonlinear effects in high power rf cavities with perpendicularly biased ferrite garnet used for varying the frequency in rapid cycling synchrotrons. A method of analysis is developed using a minimum of specific details. Simple formulae and estimates of the trend of magnetic loss, nonlinear frequency shift and possible instabilities in the cavities as a function of rf power level and ferrite garnet parameters are presented. Numerical examples correspond to the TRIUMF KAON Booster synchrotron. (author). 14 refs., 5 figs

Geology, petrology, U-Pb (SHRIMP) geochronology of the Morrinhos granite - Paragua terrane, SW Amazonian craton: implications for the magmatic evolution of the San Ignacio orogeny

Energy Technology Data Exchange (ETDEWEB)

Franca, Ohana; Ruiz, Amarildo Salina; Sousa, Maria Zelia Aguiar de, E-mail: ohana.geo@gmail.com, E-mail: asruiz@gmail.com, E-mail: mzaguiar@terra.com.br [Universidade Federal de Mato Grosso (UFMT), Cuiaba, MT (Brazil). Instituto de Ciencias Exatas e da Terra. Dept. de Geologia Geral; Batata, Maria Elisa Froes, E-mail: elisabatata@bol.com.br [Universidade Federal de Mato Grosso (UFMT), Cuiaba, MT (Brazil). Grupo de Pesquisa em Evolucao Crustal e Tectonica; Lafon, Jean-Michel [Universidade Federal do Para (GEOCIAM/UFPA), Belem, PR (Brazil). Inst. Nacional de Cencia e Tecnologia de Geociencias da Amazonia

2014-09-15

Morrinhos granite is a batholith body that is slightly elongated in the NNW direction and approximately 1,140 km{sup 2} long; it is located in the municipality of Vila Bela da Santissima Trindade of the state of Mato Grosso, Brazil, in the Paragua Terrane, Rondonian-San Ignacio Province, in the SW portion of the Amazonian Craton. This intrusion displays a compositional variation from tonalite to monzogranite, has a medium to coarse inequigranular texture and is locally porphyritic; biotite is the predominant mafic in one of the facies, and hornblende is predominant in the other, with both metamorphosed into the green schist facies. The studied rocks characterize an intermediate to acidic sequence that was formed by a subalkaline magmatism; the series is alkali-calcic to metaluminous to slightly peraluminous, and the rocks evolved through fractioned crystallization mechanisms. The structural data show two deformation phases represented by penetrative foliation (S{sub 1}) and open folds (D{sub 2}), and both phases were most likely related to the San Ignacio Orogeny. The geochronological (U-Pb SHRIMP) and isotopic (Sm-Nd) investigations of these rocks indicated a crystallization age of 1350±12Ma, T{sub DM} of approximately 1.77 Ga and εNd{sub (1.35}) with a negative value of -2.57, suggesting that their generation was related to a partial melting process of a Paleoproterozoic (Statherian) continental crust. The results herein indicate that the Morrinhos granite was generated in a continental magmatic arc in a late- to post-orogenic stage of the San Ignacio Orogeny, and it can be recognized as belonging to the Pensamiento Intrusive Suite. (author)

Terrestrial gamma ray dose rates on Ryoke granitic rocks in Ikoma Mountains

International Nuclear Information System (INIS)

Ikeda, Tadashi; Ueshima, Masaaki; Shibayama, Motohiko; Hiraoka, Yoshitsugu; Muslim, Dicky

2012-01-01

We measured the γ dose rate of 16 rock bodies in the field, which belonged to Ryoke granitic rocks distributed over Ikoma Mountains. The measurement points were 190 spots, and the mean dose rate was 82.0 ± 21.0 nGy/h. Results of analysis were summarized as follows. (1) The distribution of the dose rate in the Fukihata quartz diorite showed that the rocks crystallization differentiation had progressed from the south to the north. (2) The dose rate of granite tended to arise with the increase of SiO 2 quantity, but in the Iwahashiyama granite, the Takayasuyama granite, the Omichi granite and the Katakami granite, it was revealed that the dose rate was low in spite of high SiO 2 quantity. (3) It became clear that the dose rate of Ryoke granitic rocks from the first stage to the fourth stage was high to be considered as a new rock body. (4) Because the relationship between the dose rate of rocks and the main chemical elements did not show a common characteristic, it may be that those rocks were formed from different Magma. (author)

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

Energy Technology Data Exchange (ETDEWEB)

Antunes, I. M. H. R.; Neiva, A. M. R.; Silva, M. M. V. G.

2010-07-01

Five granitic rocks, concentrically disposed from core to rim, were distinguished in the Castelo Branco pluton. U-Pb-Th electron microprobe monazite ages from granitic rocks are similar and ranging between 297-303 Ma. The granitic rocks from Castelo Branco pluton are 310 {+-} 1 Ma old, obtained by U-Pb (ID-TIMS) in separated zircon and monazite crystals, indicating a similar emplacement age for all granitic rocks of the pluton. Initial {sup 8}7Sr/{sup 8}6Sr isotopic ratios and {epsilon}Nd{sub 3}10 and {delta}{sup 1}8O values suggest three distinct pulses of granitic magma and that they are derived from partial melting of heterogeneous metasedimentary materials. The other granitic rocks are related by magmatic differentiation and show small variations in ({sup 8}7Sr/{sup 8}6Sr)310, {epsilon}Nd{sub 3}10 and {delta}{sup 1}8O. The granitic pluton of Castelo Branco shows a rare reverse zoning. (Author) 12 refs.

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

Directory of Open Access Journals (Sweden)

He Xiao

2017-01-01

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

The Fort Smith radioactive belt, Northwest Territories

International Nuclear Information System (INIS)

Charbonneau, B.W.

1980-01-01

The Fort Smith Belt is an elongate zone, about 200 km x 50 km, extending from the East Arm of Great Slave Lake southerly into northeastern Alberta. The major feature of the belt is that it is one of the most radioactive regions so far recognized in the Canadian Shield. Potassium, uranium, and thorium are all enriched but the greatest increase is in thorium. The dominant rock type underlying the area is a foliated porphyritic granite. This rock contains an average of about 80 ppm thorium (with areas of tens of square kilometres containing up to 200 ppm) and approximately 11 ppm uranium. In places, dark elongate zones rich in biotite, apatite, and opaque minerals within the porphyritic granite may contain an order of magnitude more uranium and thorium than the porphyry. Radioactive minerals within both the porphyry and the dark zones are principally monazite (containing up to 16% ThO 2 ) and isolated grains of uraninite. This foliated porphyritic granite is interpreted as being pre- or syntectonic with respect to the Hudsonian event because its foliation parallels that of the surrounding rocks. There has been subsequent deformation. The second characteristic feature of the Fort Smith Belt is the development of a peripheral zone where eU is enriched relative to eTh correlating mainly with granitoid rocks which surround the thorium-rich area and wherein ratios of eU/eTh exceed 1:2 (compared to the crustal average of 1:4). Uranium may have moved laterally into this marginal area from the thorium-rich porphyry, possibly in a vapour phase. There is a possibility that concentrations of uranium as well as other metals such as Cu, Mo, Zn, Sn, and W could exist in the porphyry and its margin in appropriate chemical and/or structural traps. The radioactive granite rocks of the Fort Smith Belt are adjacent to uranium-thorium occurrences in the nearby Proterozoic Nonacho sediments but whether or not a genetic relationship exists between the two situations is uncertain. (auth)

Garnet pyroxenite from Nilgiri Block, southern India: Vestiges of a Neoarchean volcanic arc

Science.gov (United States)

Samuel, Vinod O.; Kwon, Sanghoon; Santosh, M.; Sajeev, K.

2018-06-01

Southern peninsular India preserves records of Late Neoarchean-Early Paleoproterozoic continental building and cratonization. A transect from the Paleoarchean Dharwar Craton to the Neoarchean arc magmatic complex in the Nilgiri Block across the intervening Moyar Suture Zone reveals an arc-accretionary complex composed of banded iron formation (BIF), amphibolite, metatuff, garnet-kyanite schist, metagabbro, pyroxenite and charnockite. Here we investigate the petrology, geochronology and petrogenesis of the pyroxenite and garnet-clinopyroxenite. The pyroxenite is mainly composed of orthopyroxene and clinopyroxene with local domains/pockets enriched in a clinopyroxene-garnet assemblage. Thermobarometric calculations and phase equilibria modeling suggest that the orthopyroxene- and clinopyroxene-rich domains formed at 900-1000 °C, 1-1.2 GPa whereas the garnet- and clinopyroxene-rich domains record higher pressure of about 1.8-2 GPa at similar temperature conditions (900-1000 °C). Zircon U-Pb SHRIMP dating show weighted mean 207Pb-206Pb age of 2532 ± 22 Ma, with metamorphic overgrowth at 2520 ± 27 Ma and 2478 ± 27 Ma. We propose a tectonic model involving decoupling and break-off of the oceanic plate along the southern flanks of the Dharwar Craton, which initiated oceanic plate subduction. Slab melting eventually built the Nilgiri volcanic arc on top of the over-riding plate along the flanks of the Dharwar Craton. Our study supports an active plate tectonic regime at the end of the Archean Era, aiding in the growth of paleo-continents and their assembly into stable cratons.

On the sources of uranium in some Scottish Caledonian granites

International Nuclear Information System (INIS)

Halliday, A.N.

1982-01-01

The lead isotope systematics, zircon uranium concentrations and whole-rock rubidium concentrations of 11 Scottish Caledonian granites are examined for clues to the origin of their uranium. A positive correlation between U in zircon and initial lead isotope ratios suggests that U and Pb were derived from the same source which, as some of these granites contain their U in inherited zircons, is likely to have been within the crust. It is argued, therefore, that most of the uranium in these granites had a crustal derivation but lead isotope ratios indicate that any Lewisian contribution was minor in comparison with those from postulated Grenville, Morarian or Caledonian metamorphic reservoirs. However, additional data are required before this conclusion can be extended to include uraniferous Caledonian granites such as Cairngorm. (author)

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.

Study of RE-garnets using BPW method

Science.gov (United States)

Goveas, Neena; Mukhopadhyay, P.; Mukhopadhyay, G.

1995-02-01

The magnetic susceptibility of rare-earth (Y and Lu) iron garnets is studied using a modified Bethe-Peierls-Weiss (BPW) approximation. The modifications enable us to incorporate the three exchange parameters Jad, Jaa and Jdd necessary to describe the systems. We get excellent fits to the experimental susceptibilities from which we determined the J-values. These also give excellent agreement with the spin wave dispersion relation constant D.

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)

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

Low temperature delayed recombination decay in scintillating garnets

Czech Academy of Sciences Publication Activity Database

Mihóková, Eva; Babin, Vladimir; Bartosiewicz, Karol; Schulman, L. S.; Čuba, V.; Kučera, M.; Nikl, Martin

2015-01-01

Roč. 40, Fešb (2015), s. 127-131 ISSN 0925-3467 R&D Projects: GA ČR GA13-09876S EU Projects: European Commission(XE) 316906 - LUMINET Grant - others:AVČR(CZ) M100101212 Institutional support: RVO:68378271 Keywords : luminescence * garnets * scintillator * tunneling Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.183, year: 2015

Study on radon and thoron levels in different types of granitic work industries around Tumkur city

International Nuclear Information System (INIS)

Nagabhushan, S.R.; Ningappa, C.; Srilatha; Shekar, Usha; Sannappa, J.

2011-01-01

Radon is a naturally occurring radioactive noble gas generated by the decay of uranium and thorium bearing minerals in rocks, soils and building materials. Radon and decay products are the major contributors to human exposure from natural radiation sources. Epidemiological evidence indicates that indoor radon and thoron were responsible for a substantial number of lung cancer in publics. UNSCEAR reported recently indicates that there is a remarkable coherence between the risk estimates developed from epidemiological studies from miners and residential case-control radon studies. Hence to select the study area for the estimation of dose due to radon and thoron to the publics and workers, concentration of radon, thoron and their progeny were measured by using SSNTD. Since, activity concentration in granite more, higher concentrations of radon and thoron have been observed in the dwellings near to granite industry and lesser concentration of radon and thoron have been observed in the dwellings near brick industries of Tumkur city. From the study, the concentration of radon and thoron varied from 31 to 70.4 Bq.m 3 and 11.6 to 46.3 Bq.m 3 , respectively. Corresponding progeny level varied from 0.11 to 2.5 mWL and 1.1 to 3.4 mWL, respectively. (author)

Semiconductor sensor for optically measuring polarization rotation of optical wavefronts using rare earth iron garnets

Science.gov (United States)

Duncan, Paul G.

2002-01-01

Described are the design of a rare earth iron garnet sensor element, optical methods of interrogating the sensor element, methods of coupling the optical sensor element to a waveguide, and an optical and electrical processing system for monitoring the polarization rotation of a linearly polarized wavefront undergoing external modulation due to magnetic field or electrical current fluctuation. The sensor element uses the Faraday effect, an intrinsic property of certain rare-earth iron garnet materials, to rotate the polarization state of light in the presence of a magnetic field. The sensor element may be coated with a thin-film mirror to effectively double the optical path length, providing twice the sensitivity for a given field strength or temperature change. A semiconductor sensor system using a rare earth iron garnet sensor element is described.

[Study on the fine structure of K-feldspar of Qichun granite].

Science.gov (United States)

Du, Deng-Wen; Hong, Han-Lie; Fan, Kan; Wang, Chao-Wen; Yin, Ke

2013-03-01

Fine structure of K-feldspar from the Qichun granite was investigated using X-ray diffraction (XRD), Fourier infrared absorption spectroscopy (FTIR), and inductively coupled plasma mass spectrometry methods to understand the evolution of the granitic magmatism and its correlation to molybdenite mineralization. The XRD results showed that K-feldspar of the potassic alteration veins has higher ordering index and triclinicity and is namely microcline with triclinic symmetry. K-feldspar of the early cretaceous granite has relatively lower ordering index and has widening [131] peak and is locally triclinic ordering. K-feldspar of the late cretaceous granite has lowest ordering index and sharp [131] peak and is honiogeneously monoclinic. The FTIR results showed that the IR spectra of the Qichun K-feldspar are similar to that of orthoclase reported by Farmer (1974). The 640 cm-1 absorption band increases while the 540 cm-' absorption band decreases with increase in K-feldspar ordering index, also, the 1,010 cm-1 absorption band separates into 1,010 and 1,046 cm-1 absorption bands, with a change in the band shape from widening to sharp outline. The ICP-MS results suggested that K-feldspar of the early cretaceous granite has relatively higher metal elements and rare earth elements, and the granite exhibits better mineralization background, K-feldspar of the potassic alteration veins has markedly lower Sr and Ba, indicating that the alteration fluid originated from the granitic magmatism, and hence, potassic alteration is a good indicator for molybdenite exploration.

Bi-substituted iron garnet films for one-dimensional magneto-photonic crystals: Synthesis and properties

International Nuclear Information System (INIS)

Shaposhnikov, A.N.; Karavainikov, A.V.; Prokopov, A.R.; Berzhansky, V.N.; Salyuk, O.Y.

2012-01-01

Graphical abstract: Faraday hysteresis loops for Bi 1.0 Y 0.5 Gd 1.5 Fe 4.2 Al 0.8 O 12 film on glass-ceramic substrate (a), Bi 2.8 Y 0.2 Fe 5 O 12 film on gallium–gadolinium garnet (b) and for glass-ceramic/SiO 2 /Bi 1.0 Y 0.5 Gd 1.5 Fe 4.2 Al 0.8 O 12 /Bi 2.8 Y 0.2 Fe 5 O 12 structure (c). Highlights: ► Bismuth-substituted iron garnet films as magneto-optical layers in magneto-photonic crystals. ► It is impossible to crystallize the films with high Bi content on amorphous substrates. ► The crystallization of the films can be achieved by their deposition on buffer layer with low bismuth content. -- Abstract: The crystallization processes in Bi 2.8 Y 0.2 Fe 5 O 12 , Bi 2.5 Gd 0.5 Fe 3.8 Al 1.2 O 12 , Bi 1.5 Gd 1.5 Fe 4.5 Al 0.5 O 12 and Bi 1.0 Y 0.5 Gd 1.5 Fe 4.2 Al 0.8 O 12 garnet films deposited by reactive ion beam sputtering on (1 1 1) gadolinium–gallium garnet substrates, optical glass-ceramic and SiO 2 films have been studied. Films were annealed at low pressure in oxygen atmosphere and in the air. The possibility of preparation of crystalline garnet films with high concentration of bismuth on the SiO 2 films using a buffer layer with low concentration of Bi has been shown. This allows to produce one-dimensional magneto-photonic crystals with high effective Faraday rotation (several tens of°/μm for the visible optical spectrum).

Microstructure and defect chemistry of yttrium aluminium garnet ceramics

International Nuclear Information System (INIS)

Schuh, L.H.

1989-01-01

This thesis describes basic aspects concerning the defect chemistry and the microstructure of yttrium aluminium garnet ceramics. The work consists of three parts: a literature study, an experimental part and a section giving computer simulation data of defects. (author). 320 refs.; 68 figs.; 72 schemes; 32 tabs

Geology of Muntok area and the potency of menumbang granite as source of Uranium and Thorium

International Nuclear Information System (INIS)

Kurniawan Dwi Saksama; Ngadenin

2013-01-01

In the West Bangka there are some granites namely Menumbing, Pelangas, Tempilang, and Jebus granite. The granites is granite tin belt that stretches from Thailand-Malaysia-Bangka Belitung. Granite tin belt or granite source of tin (cassiterite) can act as a source of U and Th. Aims of the study is to find out the information on the geology of Muntok area and its surrounding and to determine the potency of Menumbing granite as a source of U and Th. The methods used is surface geological mapping in Muntok areas and its surrounding with scale 1 : 25.000, measurement grade of uranium and thorium in Menumbing granite areas and petrographic and grain size analysis of sample of Menumbing granite. Determination of granites a source of U and Th is based on content of radioactive mineral, anomaly of U and Th, megascopic and microscopic observation of granite. Morphology of Muntok areas and its surrounding is denudasional undulating plains to hills with an elevation ranging from 0 to 455 meters. Stratigraphy of research areas from old to young is meta sandstone units, granite intrusion of Menumbing and alluvial. Evolving fault is a fault trending West-East. Based on the presence of radioactive minerals, grade of U and Th as well as the type of granite, it was concluded that the Menumbing granite is a source of Th and not sources of U. (author)

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

Helical bifurcation and tearing mode in a plasma—a description based on Casimir foliation

International Nuclear Information System (INIS)

Yoshida, Z; Dewar, R L

2012-01-01

The relation between the helical bifurcation of a Taylor relaxed state (a Beltrami equilibrium) and a tearing mode is analyzed in a Hamiltonian framework. Invoking an Eulerian representation of the Hamiltonian, the symplectic operator (defining a Poisson bracket) becomes non-canonical, i.e. the symplectic operator has a nontrivial cokernel (dual to its nullspace), foliating the phase space into level sets of Casimir invariants. A Taylor relaxed state is an equilibrium point on a Casimir (helicity) leaf. Changing the helicity, equilibrium points may bifurcate to produce helical relaxed states; a necessary and sufficient condition for bifurcation is derived. Tearing yields a helical perturbation on an unstable equilibrium, producing a helical structure approximately similar to a helical relaxed state. A slight discrepancy found between the helically bifurcated relaxed state and the linear tearing mode viewed as a perturbed, singular equilibrium state is attributed to a Casimir element (named ‘helical flux’) pertinent to a ‘resonance singularity’ of the non-canonical symplectic operator. While the helical bifurcation can occur at discrete eigenvalues of the Beltrami parameter, the tearing mode, being a singular eigenfunction, exists for an arbitrary Beltrami parameter. Bifurcated Beltrami equilibria appearing on the same helicity leaf are isolated by the helical-flux Casimir foliation. The obstacle preventing the tearing mode to develop in the ideal limit turns out to be the shielding current sheet on the resonant surface, preventing the release of the ‘potential energy’. When this current is dissipated by resistivity, reconnection is allowed and tearing instability occurs. The Δ′ criterion for linear tearing instability of Beltrami equilibria is shown to be directly related to the spectrum of the curl operator. (paper)

The magmatism and metamorphism at the Malayer area, Western Iran

Science.gov (United States)

Ahadnejad, V.; Valizadeh, M. V.; Esmaeily, D.

2009-04-01

The Malayer area is located in the NW-SE aligned Sanandaj-Sirjan metamorphic belt, western Iran and consists mainly of Mesozoic schists so-called Hamadan Phyllites, Jurassic to Tertiary intrusive rocks and related contact metamorphic aureoles, aplites and pegmatites. The Sanandj-Sirjan Zone is produced by oblique collisional event between Arabian plate and Central Iran microcontinent. Highest level of regional metamorphism in the area is greenschist facies and injection of felsic magmas is caused contact metamorphism. Magmatism is consist of a general northwest trend large felsic to intermediate intrusive bodies. The main trend of structural features i.e. faults, fractures and other structural features is NW-SE. The Malayer granitoid complex is ellipsoid in shape and has NW-SE foliation especially at the corners of the intrusions. Petrography of the magmatic rocks revealed recrystallization of quartz and feldspars, bending of biotite, and aligment of minerals paralle to the main trend of magmatic and metamorphic country rocks. These indicated that intrusion of felsic magma is coincide to the regional metamorphism and is syn-tectoinc. Non-extensive contact metamorphism aureoles and rareness of pegmatite and aplite in the area are interpreted as injection of felsic magmas into the high-strain metamorphic zone. The regional metamorphic rocks mainly consist of meta-sandstone, slate, phyllite, schist. These gray to dark metasedimentary rocks are consist of quartz, muscovite, turmaline, epidote, biotite and chlorite. Sheeted minerals form extended schistosity and study of porphyroblast-matrix relationships shows that injection of granitic magma into the country rocks is syn to post-tectonic. Syn-tectonic indicating porphyroblast growth synchronous with the development of the external fabric. The thermal contact area of the granite can be observed in the contact margin of granite and regional metamorphic rocks, where it produced hornfelses, andalusit-garnet schists and

Mechanical properties of Stripa granite

International Nuclear Information System (INIS)

Stephansson, O.; Swan, G.; Leijon, B.

1978-01-01

For the determination of the mechanical properties of Stripa Granite samples were taken from the boreholes in the vicinity of the test site. The granite type taken from these different sources is of variable character. For the purpose of numerical calculations performed in projects related to the waste storage research program the following parameters have been determined: Young's modulus, Poisson's ratio, compressive fracture stress and expansion coefficient as a function of temperature 20< T<200C; Young's modulus and compressive fracture stress as a function of confining pressure; Brazilian tensile fracture stress; residual shear stress as a function of normal stress; anisotropy ratio for Young's modulus and compressive fracture stress; dilatational wave velocity and deduced dynamic Young's modulus. A brief description of the test methods and the results for each test are presented

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

International Nuclear Information System (INIS)

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

2014-01-01

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 m 2 /g–21.93 m 2 /g and 25.76 m 2 /g–26.83 m 2 /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

Ultra-low damping in lift-off structured yttrium iron garnet thin films

Science.gov (United States)

Krysztofik, A.; Coy, L. E.; Kuświk, P.; Załeski, K.; Głowiński, H.; Dubowik, J.

2017-11-01

We show that using maskless photolithography and the lift-off technique, patterned yttrium iron garnet thin films possessing ultra-low Gilbert damping can be accomplished. The films of 70 nm thickness were grown on (001)-oriented gadolinium gallium garnet by means of pulsed laser deposition, and they exhibit high crystalline quality, low surface roughness, and the effective magnetization of 127 emu/cm3. The Gilbert damping parameter is as low as 5 ×10-4. The obtained structures have well-defined sharp edges which along with good structural and magnetic film properties pave a path in the fabrication of high-quality magnonic circuits and oxide-based spintronic devices.

U-Pb GEOCHRONOLOGY OF METASEDIMENTARY SCHISTS IN ...

African Journals Online (AJOL)

PROF EKWUEME

The geology of Akwnaga area of northcentral Nigeria is dominated by schists, metaigneous gneisses and weakly to non- foliated granites. The Schist shows grades up to the sillimanite zone of the Barrovian type regional metamorphism and occurs as xenoliths in other rocks of the area. The zircons separated from a sample ...

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

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

Science.gov (United States)

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

1996-01-01

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

Differential equilibration and intergranular diffusion of trace elements during rapid regional metamorphism: constraints from LA-ICP-MS mapping of a garnet population

Science.gov (United States)

George, F. R.; Gaidies, F.

2017-12-01

Trace element zoning contained within a metapelitic garnet population yields information pertaining to a more complex prograde reaction history than is evident in major element zoning patterns and other conventional analyses. In particular, while trace elements may not act as a rate-limiting component for garnet crystallization, their incorporation into garnet growth surfaces provides a nuanced insight into the crystallization history of the population, and the extent of equilibration of trace elements in the matrix. In this study, we present LA-ICP-MS raster maps of trace element concentrations from several population-representative, centrally sectioned garnets from a garnet-grade metapelite of the Sikkim Himalaya, India. Equilibrium forward modeling of garnet crystallization and simulation of diffusional modification indicates that the garnet population crystallized rapidly over <1 Myr between 515 °C/4.5 kbar and 565 °C/5.5 kbar, as a consequence of high heating rates during regional amphibolite-facies metamorphism. While the rate of diffusional homogenization of major divalent cations is interpreted to have exceeded the rate of interfacial advance (yielding simple prograde growth zoning), trace element distributions record a more complex transport history. In particular, yttrium and the heavy rare earth elements (HREE) document a transition from an overprinted sigmoidal core to concentric repeated HREE and yttrium annuli in all crystals. This suggests that there was a discrete increase in the length scale of equilibration along the advancing garnet interface at some point in the growth history. However, there is no evidence for a coeval change in HREE transport thorough the intergranular network. Conversely, spiral core-to-rim zoning of chromium indicates the element remains almost completely immobile in the matrix over the duration of garnet growth.

Cathodoluminescence properties of yttrium aluminum garnet doped with Eu2+ and Eu3+ ions

International Nuclear Information System (INIS)

Trofimov, A. N.; Petrova, M. A.; Zamoryanskaya, M. V.

2007-01-01

Yttrium aluminium garnet (YAG) doped with Eu 2+ and Eu 3+ ions is very interesting as a phosphor for conversion of light-emitting diode light for white light sources. The europium ion occupies the structural position of yttrium in yttrium aluminium garnet and has valence state Eu 3+ . Our sample was doped with Zr 4+ , which is why some of the europium ions had valence state Eu 2+ . As a rule, luminescence of Eu 3+ ions is observed in the orange and red range of spectrum. The luminescence of Eu 2+ in yttrium aluminum garnet is characterized by an intensive broad band with maximum of intensity at about 560 nm (green color). In this work, we studied the intensity and decay time dependences on europium concentration, and the influence of excitation power density on the cathodoluminescence of the sample. The most interesting result is the change of visible cathodoluminescence color in dependence on the density of the exciting power

Origin and geodynamic significance of the early Mesozoic Weiya LP and HT granulites from the Chinese Eastern Tianshan

Science.gov (United States)

Mao, Ling-Juan; He, Zhen-Yu; Zhang, Ze-Ming; Klemd, Reiner; Xiang, Hua; Tian, Zuo-Lin; Zong, Ke-Qing

2015-12-01

The Chinese Tianshan in the southwestern part of the Central Asian Orogenic Belt (CAOB) is characterized by a variety of high-grade metamorphic rocks, which provide critical constraints for understanding the geodynamic evolution of the CAOB. In this paper, we present detailed petrological and zircon U-Pb geochronological studies of the Weiya low-pressure and high-temperature (LP-HT) granulites of the Chinese Eastern Tianshan. These granulites were previously considered to be a product of a regional metamorphic orogenic event. Due to different bulk-rock chemistries the Weiya granulites, which occur as lenses within the contact metamorphic aureole of the Weiya granitic ring complex, have a variety of felsic-pelitic and mafic granulites with different textural equilibrium mineral assemblages including garnet-cordierite-sillimanite-bearing granulites, cordierite-sillimanite-bearing granulites, cordierite-orthopyroxene-bearing granulites, and orthopyroxene-clinopyroxene-bearing granulites. Average P-T thermobarometric calculations and conventional geothermobarometry indicates that the Weiya granulites underwent early prograde metamorphism under conditions of 600-650 °C at 3.2-4.2 kbar and peak metamorphism of 750-840 °C at 2.9-6.3 kbar, indicating a rather high geothermal gradient of ca. 60 °C/km. Zircon U-Pb LA-ICP-MS dating revealed metamorphic ages between 244 ± 1 to 237 ± 3 Ma, which are in accordance with the crystallization age of the Weiya granitic ring complex. We suggest that the formation of the Weiya granulites was related to contemporaneous granitic magmatism instead of a regional metamorphic orogenic event. In addition, a Late Devonian metamorphic age of ca. 380 Ma was recorded in zircon mantle domains from two pelitic samples which is consistent with the metamorphic age of the Xingxingxia metamorphic complex in the Chinese Eastern Tianshan. This suggests that the mantle domains of the zircon grains of the Weiya granulites probably formed during the

Monte Carlo simulations for generic granite repository studies

Energy Technology Data Exchange (ETDEWEB)

Chu, Shaoping [Los Alamos National Laboratory; Lee, Joon H [SNL; Wang, Yifeng [SNL

2010-12-08

In a collaborative study between Los Alamos National Laboratory (LANL) and Sandia National Laboratories (SNL) for the DOE-NE Office of Fuel Cycle Technologies Used Fuel Disposition (UFD) Campaign project, we have conducted preliminary system-level analyses to support the development of a long-term strategy for geologic disposal of high-level radioactive waste. A general modeling framework consisting of a near- and a far-field submodel for a granite GDSE was developed. A representative far-field transport model for a generic granite repository was merged with an integrated systems (GoldSim) near-field model. Integrated Monte Carlo model runs with the combined near- and farfield transport models were performed, and the parameter sensitivities were evaluated for the combined system. In addition, a sub-set of radionuclides that are potentially important to repository performance were identified and evaluated for a series of model runs. The analyses were conducted with different waste inventory scenarios. Analyses were also conducted for different repository radionuelide release scenarios. While the results to date are for a generic granite repository, the work establishes the method to be used in the future to provide guidance on the development of strategy for long-term disposal of high-level radioactive waste in a granite repository.

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.)

Performance assessment of geological isolation systems for medium and alpha waste disposal in granitic formations

International Nuclear Information System (INIS)

Lewi, J.; Brun-Yaba, C.; Cernes, A.

1990-01-01

PACOMA (Performance Assessment of Confinement for Medium and Alpha Waste) is a coordinated project of the Commission of the European Communities with the participation of the Member States. This project is intended to evaluate the suitability of clay, granite and salt formations to dispose of conditioned alpha and medium-level radioactive waste. In this report, CEA-IPSN presents the database and the results of evaluating the radiological consequences associated to the disposal of alpha-bearing waste in a deep granite formation. Two repository concepts and three sites have been examined (Auriat, a hypothetical site in the UK and Barfleur) which are identical to those considered in the PAGIS project. The methodology adopted for the PAGIS project has been used for carrying out the deterministic calculations of radiological consequences in the case of normal evolution scenarios and in altered evolutions, as well as for sensitivity analysis of results to the calculation parameters and for uncertainty studies. The calculation of individual doses in the case of normal evolutions show, after a first peak due to I-129, Se-79 and Tc-99 some hundred of thousands years, a maximum, which is reached only after several million of years. In all cases, these maxima are largely lower (by a factor of 1000 at least), than the limit recommended by the IRCP

Calibrated acoustic emission system records M -3.5 to M -8 events generated on a saw-cut granite sample

Science.gov (United States)

McLaskey, Gregory C.; Lockner, David A.

2016-01-01

Acoustic emission (AE) analyses have been used for decades for rock mechanics testing, but because AE systems are not typically calibrated, the absolute sizes of dynamic microcrack growth and other physical processes responsible for the generation of AEs are poorly constrained. We describe a calibration technique for the AE recording system as a whole (transducers + amplifiers + digitizers + sample + loading frame) that uses the impact of a 4.76-mm free-falling steel ball bearing as a reference source. We demonstrate the technique on a 76-mm diameter cylinder of westerly granite loaded in a triaxial deformation apparatus at 40 MPa confining pressure. The ball bearing is dropped inside a cavity within the sample while inside the pressure vessel. We compare this reference source to conventional AEs generated during loading of a saw-cut fault in a second granite sample. All located AEs occur on the saw-cut surface and have moment magnitudes ranging from M −5.7 down to at least M −8. Dynamic events rupturing the entire simulated fault surface (stick–slip events) have measurable stress drop and macroscopic slip and radiate seismic waves similar to those from a M −3.5 earthquake. The largest AE events that do not rupture the entire fault are M −5.7. For these events, we also estimate the corner frequency (200–300 kHz), and we assume the Brune model to estimate source dimensions of 4–6 mm. These AE sources are larger than the 0.2 mm grain size and smaller than the 76 × 152 mm fault surface.

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. 29th Mid-year meeting. Posted on 19 January 2018. The 29th Mid-year ...

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

Reconnaissance geology of the Thaniyah Quadrangle, sheet 20/42 C, Kingdom of Saudi Arabia

Science.gov (United States)

Greene, Robert C.

1983-01-01

The Thaniyah quadrangle, sheet 20/42 C, is located in the transition zone between the Hijaz Mountains and the Najd Plateau of southwestern Saudi Arabia between lat 20?00' and 20?30' N., long 42?00' to 42?30' E. The quadrangle is underlain by Precambrian metavolcanic, metasedimentary, plutonic, and dike rocks. Metavolcanic rocks consist of metamorphosed basalt and andesite with minor dacite and rhyolite and underlie three discontinuous northwest-trending belts. Metasedimentary rocks are confined to small areas underlain by quartzite, metasandstone, marble, and calc-silicate rock. Plutonic rocks include an extensive unit of tonalite and quartz diorite and a smaller unit of diorite and quartz diorite, which occupy much of the central part of the quadrangle. A small body of diorite and gabbro and a two-part zone of tonalite gneiss are also present. All of these plutonic rocks are assigned to the An Nimas batholith. Younger plutonic rocks include extensive graphic granite and rhyolite in the northeastern part of the quadrangle and several smaller bodies of granitic rocks and of gabbro. The metavolcanic rocks commonly have strong foliation with northwest strike and steep to vertical dip. Diorite and quartz diorite are sheared and brecciated and apparently syntectonic. Tonalite and quartz diorite are both foliate and nonfoliate and were intruded in episodes both preceding and following shearing. The granitic rocks and gabbro are post-tectonic. Trends of faults and dikes are mostly related to the Najd faulting episode. Radiometric ages, mostly from adjacent quadrangles, suggest that the An Nimas batholith is 835 to 800 Ma, gabbro and granite, except the graphic granite and rhyolite unit, are about 640 to 615 Ma, and the graphic granite and rhyolite 575 to 565 Ma old. Metavolcanic rocks similar to those hosting copper and gold mineralization in the Wadi Shuwas mining district adjacent to the southwestern part of the quadrangle are abundant. An ancient copper mine was

Metasedimentary, granitoid, and gabbroic rocks from central Stewart Island, New Zealand

International Nuclear Information System (INIS)

Allibone, A.H.; Tulloch, A.J.

1997-01-01

A NNE-NE trending strip, 3-8 km wide, extending from the Freshwater valley across Mt Rakeahua Table Hill, and Mt Allen to the northern end or the Tin Range was mapped at a scale of 1:12,500 to locate and investigate the boundary between the Median Tectonic Zone (MTZ) and Western Province on Stewart Island. A NNE-trending fault, herein termed the Escarpment Fault, separates predominantly ductily deformed rocks on its south side from essentially undeformed rocks to the north. North of the Escarpment Fault, a small (2-3 km 2 ) pluton of alkali-feldspar granite (Freds Camp) intruded gabbroic rocks tentatively considered to be associated with gabbro/anorthosite/diorite of the Rakeahua pluton, centred on Mt Rakeahua. Both units were subsequently intruded by I-type biotite granite of the South West Arm pluton. South of the Escarpment Fault the oldest intrusions are biotite tonalite-granite orthogneisses (Ridge and Table Hill plutons) intercalated with the sillimanite-cordierite-bearing Pegasus Group metasedimentary rocks, considered to represent the Western Province. They contain titanite, allanite, and magmatic epidote-bearing assemblages, implying affinities with I-type granitoids. These older granitoids have been affected by at least three phases of ductile deformation. Immediately south of the Escarpment Fault, the Escarpment pluton (hornblende, biotite, quartz, monzonite-quartz monzodiorite) only exhibit effects of the third phase of deformation. Minor gabbroic intrusives concordant with the S 3 fabric intrude the Pegasus Group and intercalated orthogneisses. Plutons of two-mica, garnet ±cordierite granite (Blaikies and Knob) and younger biotite-titanite-magmatic epidote granite (Campsite) cut fabrics associated with the third phase of ductile deformation. Preliminary U-Pb dating indicate Devonian-Carboniferous, Jurassic, and Early Cretaceous emplacement ages for Ridge Orthogneiss, Freds Camp pluton, South West Arm pluton, and Blaikies pluton, respectively. South

Seismic anisotropy from compositional banding in granulites from the deep magmatic arc of Fiordland, New Zealand

Science.gov (United States)

Cyprych, Daria; Piazolo, Sandra; Almqvist, Bjarne S. G.

2017-11-01

We present calculated seismic velocities and anisotropies of mafic granulites and eclogites from the Cretaceous deep lower crust (∼40-65 km) of Fiordland, New Zealand. Both rock types show a distinct foliation defined by cm-scale compositional banding. Seismic properties are estimated using the Asymptotic Expansion Homogenisation - Finite Element (AEH-FE) method that, unlike the commonly used Voigt-Reuss-Hill homogenisation, incorporates the phase boundary network into calculations. The predicted mean P- and S-wave velocities are consistent with previously published data for similar lithologies from other locations (e.g., Kohistan Arc), although we find higher than expected anisotropies (AVP ∼ 5.0-8.0%, AVS ∼ 3.0-6.5%) and substantial S-wave splitting along foliation planes in granulites. This seismic signature of granulites results from a density and elasticity contrast between cm-scale pyroxene ± garnet stringers and plagioclase matrix rather than from crystallographic orientations alone. Banded eclogites do not show elevated anisotropies as the contrast in density and elastic constants of garnet and pyroxene is too small. The origin of compositional banding in Fiordland granulites is primarily magmatic and structures described here are expected to be typical for the base of present day magmatic arcs. Hence, we identify a new potential source of anisotropy within this geotectonic setting.

Faraday effect in Gd3Al5O12 and Gd3Ga5O12 rare earth garnets

International Nuclear Information System (INIS)

Valiev, U.V.; Klochkov, A.A.; Popov, A.I.; Sokolov, Y.B.

1989-01-01

The dispersion of the Faraday rotation of the garnets Gd 3 Ga 5 O 12 and Gd 3 Al 5 O 12 in the 440--700-nm region in the 85--295-K temperature interval and the spectral dependence of the Faraday effect in the garnets Y 3 Ga 5 O 12 and Y 3 Al 5 O 12 for wavelengths from 250 to 700 nm are investigated. The contributions to the Faraday rotation caused by the Gd 3+ ions and the diamagnetic lattice of the garnets are separated

The strain-dependent spatial evolution of garnet in a high- P ductile shear zone from the Western Gneiss Region (Norway): a synchrotron X-ray microtomography study

Energy Technology Data Exchange (ETDEWEB)

Macente, A. [School of Geosciences, University of Edinburgh, The King' s Building James Hutton Road Edinburgh EH9 3FE UK; Fusseis, F. [School of Geosciences, University of Edinburgh, The King' s Building James Hutton Road Edinburgh EH9 3FE UK; Menegon, L. [School of Geography, Earth and Environmental Sciences, Faculty of Science and Engineering, Plymouth University, Fitzroy Drake Circus Plymouth Devon PL4 8AA UK; Xianghui, X. [Argonne National Laboratory, 9700 S. Cass Ave Building 431-B003 Argonne IL USA; John, T. [Institut für Geologische Wissenschaften, Freie Universität Berlin, Malteserstr. 74-100 12249 Berlin Germany

2017-03-27

Reaction and deformation microfabrics provide key information to understand the thermodynamic and kinetic controls of tectono-metamorphic processes, however they are usually analysed in two dimensions, omitting important information regarding the third spatial dimension. We applied synchrotron-based X-ray microtomography to document the evolution of a pristine olivine gabbro into a deformed omphacite-garnet eclogite in four dimensions, where the 4th dimension is represented by the degree of strain. In the investigated samples, which cover a strain gradient into a shear zone from the Western Gneiss Region (Norway), we focused on the spatial transformation of garnet coronas into elongated clusters of garnets with increasing strain. Our microtomographic data allowed quantification of garnet volume, shape and spatial arrangement evolution with increasing strain. We combined microtomographic observations with light microscope- and backscatter electron images as well as electron microprobe- (EMPA) and electron backscatter diffraction (EBSD) analysis to correlate mineral composition and orientation data with the X-ray absorption signal of the same mineral grains. With increasing deformation, the garnet volume almost triples. In the low strain domain, garnets form a well interconnected large garnet aggregate that develops throughout the entire Page 1 of 52 sample. We also observed that garnet coronas in the gabbros never completely encapsulate olivine grains. In the most highly deformed eclogites, the oblate shapes of garnet clusters reflect a deformational origin of the microfabrics. We interpret the aligned garnet aggregates to direct synkinematic fluid flow and consequently influence the transport of dissolved chemical components. EBSD analyses reveal that garnet show a near-random crystal preferred orientation that testifies no evidence for crystal plasticity. There is, however evidence for minor fracturing, neo-nucleation and overgrowth. Microprobe chemical analysis

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.

Sol gel synthesis for preparation of yttrium aluminium garnet

NARCIS (Netherlands)

Vrolijk, J.W.G.A.; Willems, J.W.M.M.; Metselaar, R.; With, de G.; Terpstra, R.A.; Metselaar, R.

1989-01-01

Sol-gel—synthesis for preparation of pure yttrium aluminium garnet powder with small grain size is subject of this ongoing study. Starting materials were sulfates and chlorides of yttrium and aluminium. To obtain pure YAG (Y3A1SO1Z) pH during hydrolysis as well as temperature during calcination and

Graphite as an indicator of contact influence of Western Keivy alkaline granite intrusion, the Kola Peninsula

Directory of Open Access Journals (Sweden)

Fomina E. N.

2017-03-01

Full Text Available The results of complex petro-mineragraphic, Raman and isotope- geochemical study of three types of graphite- bearing rocks circulated at different distances from the alkaline granites: (1 kyanite schists of Bolshiye Keivy, sampled at a considerable distance from a contact with alkaline gran ites; (2 sillimanite schists, sampled close to the contact, and (3 silexites, located in the inner part of th e alkaline granite massif Western Keivy have been presented. Five morphogenetic types of graphite have been revealed in the rocks under consideration: fine- grained Gr-1, intergranular Gr-2, nest-shaped Gr-3, vein Gr- 4 and spherulitic Gr-5. Current study demonstrates that these five types of graphite distinctly vary not only i n morphology, but also in temperature of crystallization, as determined by RSCM-Raman geothermometer, and in carbon isotop e composition. The most likely source for the anomalous "light" graphite Gr-1 and Gr-2 [δ 13 C(PDB = −43...−45 ‰] from kyanite schists is a water- methane fluid originating from sedimentary rocks with org anic compounds. The carbon of graphite Gr-5 of the silexites selected at the inner part of alkaline granite massif West ern Keivy, on the contrary, proved to be most "heavy" [δ 13 C(PDB = −8 ‰], which indicates its origin from the lower crustal or mantle carbon dioxide fluid. Thus, carbon extracted into the rocks of Keivy structure from at least two contrasting isotope sources. Graphite Gr-3, that makes up the bulk of graphite of exocontact sil limanite schists, is also isotopically light, but not anomalously [δ 13 C(PDB = −17...−28 ‰]. The crystallization temperature of the gi ven graphite (435−520 ºC, and its structural relationships with other minerals of th e rock evidence of its synmetamorphic origin. The presence of veinlets of isotopically heavy [δ 13 C(PDB = −10 ‰...−11 ‰] high-temperature (570−670 ºC graphite intersecting minerals of the metamorphic paragenesis (i

Partner Symmetries, Group Foliation and ASD Ricci-Flat Metrics without Killing Vectors

Directory of Open Access Journals (Sweden)

Andrei A. Malykh

2013-11-01

Full Text Available We demonstrate how a combination of our recently developed methods of partner symmetries, symmetry reduction in group parameters and a new version of the group foliation method can produce noninvariant solutions of complex Monge-Ampère equation (CMA and provide a lift from invariant solutions of CMA satisfying Boyer-Finley equation to non-invariant ones. Applying these methods, we obtain a new noninvariant solution of CMA and the corresponding Ricci-flat anti-self-dual Einstein-Kähler metric with Euclidean signature without Killing vectors, together with Riemannian curvature two-forms. There are no singularities of the metric and curvature in a bounded domain if we avoid very special choices of arbitrary functions of a single variable in our solution. This metric does not describe gravitational instantons because the curvature is not concentrated in a bounded domain.

Magmatism and polymetallic mineralization in southwestern Qinzhou-Hangzhou metallogenic belt, South China

Science.gov (United States)

Huang, Xudong; Lu, Jianjun; Wang, Rucheng; Ma, Dongsheng

2016-04-01

As Neoproterozoic suture zone between the Yangtze Block and Cathaysia Block, Qinzhou-Hangzhou metallogenic belt is one of the 21 key metallogenic belts in China. Intensive multiple-aged felsic magmatism and related polymetallic mineralization take place in this belt. Although Neoproterozoic, Paleozoic, Triassic granites and associated deposits have been found in southwestern Qinzhou-Hangzhou metallogenic belt, Middle-Late Jurassic (150-165 Ma) magmatism and related mineralization is of the most importance. Three major kinds of Middle-Late Jurassic granitoids have been distinguished. (Cu)-Pb-Zn-bearing granitoids are slightly differentiated, calc-alkaline and metaluminous dioritic to granodioritic rocks. Sn-(W)-bearing granites contain dark microgranular enclaves and have high contents of REE and HFSE, suggesting affinities of aluminous A-type (A2) granites. W-bearing granites are highly differentiated and peraluminous rocks. (Cu)-Pb-Zn-bearing granitoids have ɛNd(t) values of -11 ˜ -4 and ɛHf(t) values of -12 ˜ -7, corresponding to TDMC(Nd) from 1.4 to 1.8 Ga and TDMC(Hf) from 1.6 to 2.0 Ga, respectively. The ɛNd(t) values of W-bearing granites vary from -11 to -8 with TDMC(Nd) of 1.6 ˜ 1.9 Ga and ɛHf(t) values change from -16 to -7 with TDMC(Hf) of 1.5 ˜ 2.0 Ga. Compared with (Cu)-Pb-Zn-bearing granitoids and W-bearing granites, the Sn-(W)-bearing granites have higher ɛNd(t) (-8 ˜ -2) and ɛHf(t) (-8 ˜ -2) values and younger TDMC(Nd) (1.1 ˜ 1.6 Ga) and TDMC(Hf) (1.2 ˜ 1.8 Ga) values, showing a more juvenile isotopic character. Sn-(W)-bearing granites originate from partial melting of granulitized lower crust involved with some mantle-derived materials. W-bearing granites are derived from partial melting of crust. (Cu)-Pb-Zn-bearing granitoids are also derived from crust but may be influenced by more mantle-derived materials. For (Cu)-Pb-Zn deposits, skarn and carbonate replacement are the most important mineralization types. Cu ore bodies mainly

Chemical and oxygen isotope zonings in garnet from subducted continental crust record mineral replacement and metasomatism

Science.gov (United States)

Vho, Alice; Rubatto, Daniela; Regis, Daniele; Baumgartner, Lukas; Bouvier, Anne-Sophie

2017-04-01

Garnet is a key mineral in metamorphic petrology for constraining pressure, temperature and time paths. Garnet can preserve multiple growth stages due to its wide P-T stability field and the relatively slow diffusivity for major and trace elements at sub-solidus temperatures. Pressure-temperature-time-fluid paths of the host rock may be reconstructed by combining metamorphic petrology with microscale trace element and oxygen isotope measurements in garnet. Subduction zones represent relevant geological settings for geochemical investigation of element exchanges during aqueous fluid-rock interactions. The Sesia Zone consists of a complex continental sequence containing a variety of mono-metamorphic and poly-metamorphic lithologies such as metagranitoids, sediments and mafic boudins. The precursor Varisican-Permian amphibolite-facies basement (6-9 kbar 650-850°C; Lardeaux and Spalla, 1991; Robyr et al., 2013) experienced high pressure metamorphism (15-22 kbar 500-550°C; Regis, et al. 2014; Robyr et al., 2013) during Alpine subduction. In different lithologies of the Internal Complex (Eclogitic Micaschist Complex), including metabasites from the Ivozio Complex, Ti-rich metasediments from Val Malone and pre-Alpine Mn-quartzites associated to metagabbros from Cima Bonze, garnet is abundant and shows a variety of complex textures that cannot be reconciled with typical growth zoning, but indicate resorption and replacement processes and possible metasomatism. In-situ, microscale oxygen isotopes analysis of garnet zones was performed by ion microprobe with the SwissSIMS Cameca IMS 1280-HR at University of Lausanne and SHRIMP-SI at the Australian National University. Each sample has a distinct δ18O composition, and the δ18O values show different degrees of variation between domains. Homogeneously low values of < 5‰ are measured in the garnets from the Ivozio Complex metagabbro. Intragrain variations of up to 3.5‰ in the porphyroblasts from Val Malone metasediments

Uranium and selected trace elements in granites from the Caledonides of East Greenland

International Nuclear Information System (INIS)

Steenfelt, A.

1982-01-01

The Caledonian fold belt of East Greenland contains calc-alkaline granite (sensu lato) intrusions with ages ranging from c.2000 Ma to c.350 Ma. The Proterozoic granites have low U contents and the pre-Devonian Caledonian granites contents of U corresponding to the clarke value for U in granites. Some aspects of the geochemistry of U are discussed using U-K/Rb, U-Sr, U-Zr, and U-Th diagrams. Secondary enrichment and mineralization occurs in fractured and hydrothermally altered granites and rhyolites situated in or near a major NNE fault zone. The U is associated with iron oxides or hydrocarbons. It is suggested that the source of the mineralization was Devonian acid magma, which also acted as a heat source for circulating hydrothermal fluids. (author)

Temperature effect on elastic properties of yttrium ferrite garnet Y3Fe5O12

International Nuclear Information System (INIS)

Burenkov, Yu.A.; Nikanorov, S.P.

2002-01-01

One studied temperature dependence of all independent elastic constants describing comprehensively elastic anisotropy of yttrium ferrite garnet within temperature wide range covering T c . One measured the Young modules for [100] and [110] crystallographic directions and the module of shift for [100] direction of specially pure single crystal of yttrium ferrite garnet within 20-600 deg C temperature range. One analyzed behavior of elastic modules and of elastic anisotropy factor near the critical temperature of magnetic phase transition [ru

Faraday effect in rare-earth ferrite garnets located in strong magnetic fields

International Nuclear Information System (INIS)

Valiev, U.V.; Zvezdin, A.K.; Krinchik, G.S.; Levitin, R.Z.; Mukimov, K.M.; Popov, A.I.

1983-01-01

The Faraday effect is investigated experimentally in single crystal specimens of rare earth iron garnets (REIG) R 3 Fe 5 O 12 (R=Y, Gd, Tb, Dy, Er, Tm, Yb, Eu, Sm and Ho) and also in mixed iron garnets Rsub(x)Ysub(3-x)Fesub(5)Osub(12) (R=Tb, Dy). The m.easurements are carried out in pulsed magnetic fields of intensity up to 200 kOe, in a temperature range from 4.2 to 300 K and at a wavelength of the light lambda=1.15 μm. The field dependence of the Faraday effect observed in the REIG cannot be explained if only the usually considered ''paramagnetic'' contribution to the Faraday effect is taken into account. A theory is developed which, besides the paramagnetic mechanism, takes into account a diamagnetic mechanism and also the mixing of the wave functions of the ground and excited multiplets. The contributions of each of these three mechanisms to the angle of rotation of the plane of polarization by the rare earth sublattice of the iron garnet are estimated theoretically. It is concluded that the mixing mechanism contributes significantly to the field and temperature dependences of the Faraday effect in REIG

A Study of Defect Behavior in Almandine Garnet

Science.gov (United States)

Geiger, C. A.; Brearley, A. J.; Dachs, E.; Tipplet, G.; Rossman, G. R.

2016-12-01

Transport and diffusion in crystals are controlled by defects. However, a good understanding of the defect types in many silicates, including garnet, is not at hand. We undertook a study on synthetic almandine, ideal end-member Fe3Al2Si3O12, to better understand its precise chemical and physical properties and defect behavior. Crystals were synthesized at high pressures and temperatures under different fO2 conditions using various starting materials with H2O and without. The almandine obtained came in polycrystalline and single-crystal form. The synthetic reaction products and crystals were carefully characterized using X-ray powder diffraction, electron microprobe and TEM analysis and with 57Fe Mössbauer, UV/VIS single-crystal absorption and IR single-crystal spectroscopy. Various possible intrinsic defects, such as the Frenkel, Schottky and site-disorder types, along with Fe3+, in both synthetic and natural almandine crystals, were analyzed based on model defects expressed in Kröger-Vink notation. Certain types of minor microscopic- to macroscopic-sized precipitation or exsolution phases, including some that are nanosized, that are observed in synthetic almandine (e.g., magnetite), as well as in more compositionally complex natural crystals (e.g., magnetite, rutile, ilmenite), may result from defect reactions. An explanation for their origin through minor amounts of defects in garnet has certain advantages over other models that have been put forth in the literature that assume strict garnet stoichiometry for their formation and/or open-system atomic transport over relatively long length scales. Physical properties, including magnetic, electrical conductivity and diffusion behavior, as well as the color, of almandine are also analyzed in terms of various possible model defects. It is difficult, if not impossible, to synthesize stoichiometric end-member almandine, Fe3Al2Si3O12, in the laboratory, as small amounts of extrinsic OH- and/or Fe3+ defects, for example

Geology, petrology, U-Pb (shrimp geochronology of the Morrinhos granite -Paraguá terrane, SW Amazonian craton: implications for the magmatic evolution of the San Ignácio orogeny

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Ohana França

Full Text Available Morrinhos granite is a batholith body that is slightly elongated in the NNW direction and approximately 1,140 km2 long; it is located in the municipality of Vila Bela da Santíssima Trindade of the state of Mato Grosso, Brazil, in the Paraguá Terrane, Rondonian-San Ignácio Province, in the SW portion of the Amazonian Craton. This intrusion displays a compositional variation from tonalite to monzogranite, has a medium to coarse inequigranular texture and is locally porphyritic; biotite is the predominant mafic in one of the facies, and hornblende is predominant in the other, with both metamorphosed into the greenschist facies. The studied rocks characterize an intermediate to acidic sequence that was formed by a subalkaline magmatism; the series is alkali-calcic to metaluminous to slightly peraluminous, and the rocks evolved through fractioned crystallization mechanisms. The structural data show two deformation phases represented by penetrative foliation (S1 and open folds (D2, and both phases were most likely related to the San Ignácio Orogeny. The geochronological (U-Pb SHRIMP and isotopic (Sm-Nd investigations of these rocks indicated a crystallization age of 1350 ± 12 Ma, TDMof approximately 1.77 Ga and εNd(1.35with a negative value of -2.57, suggesting that their generation was related to a partial melting process of a Paleoproterozoic (Statherian continental crust. The results herein indicate that the Morrinhos granite was generated in a continental magmatic arc in a late- to post-orogenic stage of the San Ignácio Orogeny, and it can be recognized as belonging to the Pensamiento Intrusive Suite.

Bi-substituted iron garnet films for one-dimensional magneto-photonic crystals: Synthesis and properties

Energy Technology Data Exchange (ETDEWEB)

Shaposhnikov, A.N.; Karavainikov, A.V.; Prokopov, A.R.; Berzhansky, V.N. [Taurida National V.I. Vernadsky University, Vernadsky Av., 4, 95007 Simferopol (Ukraine); Salyuk, O.Y., E-mail: olga-saliuk@yandex.ru [Institute of Magnetizm NASU and MESU, 36-B Vernadsky Blvd., 03142 Kiev (Ukraine)

2012-06-15

Graphical abstract: Faraday hysteresis loops for Bi{sub 1.0}Y{sub 0.5}Gd{sub 1.5}Fe{sub 4.2}Al{sub 0.8}O{sub 12} film on glass-ceramic substrate (a), Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12} film on gallium–gadolinium garnet (b) and for glass-ceramic/SiO{sub 2}/Bi{sub 1.0}Y{sub 0.5}Gd{sub 1.5}Fe{sub 4.2}Al{sub 0.8}O{sub 12}/Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12} structure (c). Highlights: ► Bismuth-substituted iron garnet films as magneto-optical layers in magneto-photonic crystals. ► It is impossible to crystallize the films with high Bi content on amorphous substrates. ► The crystallization of the films can be achieved by their deposition on buffer layer with low bismuth content. -- Abstract: The crystallization processes in Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12}, Bi{sub 2.5}Gd{sub 0.5}Fe{sub 3.8}Al{sub 1.2}O{sub 12}, Bi{sub 1.5}Gd{sub 1.5}Fe{sub 4.5}Al{sub 0.5}O{sub 12} and Bi{sub 1.0}Y{sub 0.5}Gd{sub 1.5}Fe{sub 4.2}Al{sub 0.8}O{sub 12} garnet films deposited by reactive ion beam sputtering on (1 1 1) gadolinium–gallium garnet substrates, optical glass-ceramic and SiO{sub 2} films have been studied. Films were annealed at low pressure in oxygen atmosphere and in the air. The possibility of preparation of crystalline garnet films with high concentration of bismuth on the SiO{sub 2} films using a buffer layer with low concentration of Bi has been shown. This allows to produce one-dimensional magneto-photonic crystals with high effective Faraday rotation (several tens of°/μm for the visible optical spectrum).

The spatial variation of initial 87Sr/86Sr ratios in the Toki granite, Central Japan. Implications for the intrusion and cooling processes of a granitic pluton

International Nuclear Information System (INIS)

Yuguchi, Takashi; Tsuruta, Tadahiko; Hama, Katsuhiro; Nishiyama, Tadao

2013-01-01

The spatial variation in initial 87 Sr/ 86 Sr ratios (SrI) in the Toki granite, Central Japan, shows heterogeneity ranging from 0.708942 to 0.710069, which provides information on the intrusion and cooling processes of plutons. The Toki granite has three mineralogy-based rock facies: muscovite-biotite granite (MBG), hornblende-biotite granite (HBG) and biotite granite (BG). Large SrI values were found to be distributed at the western margin (west MBG) and the lithologically central region (central BG), while small SrI values were found at the northeast margin (northeast MBG). Regions with high and low Sr concentrations were also found in the Toki granite. In the Sr-rich samples, SrI (0.708942-0.709789) increases with 100/Sr (0.7-1.5). This geochemical trend extends towards the country sedimentary rocks of the Mino Terrane, which can be interpreted to result from assimilation and fractional crystallization (AFC) between the original granitic magma and the Mino sedimentary rocks. The SrI values in the Sr-rich regions show a correlation with the Alumina Saturation Index (ASI). In particular, the west MBG, with large SrI values, is classified as a peraluminous granitoid with large ASI, suggesting that the western margin of the pluton was strongly affected by assimilation during the intrusion process. The Sr-poor samples are present both in the central BG, with large SrI values, and in the northeast MBG, with small SrI values. The Sr-poor samples have small ASI and large differentiation indices, indicating that the central BG and the northeast MBG were generated either by different AFC process with different amounts of contaminants or by the intrusion and fractionation of different source magma with different SrI values. Overall, the geochemical spatial variations found in the Toki granite can be explained by various degrees of assimilation and fractional crystallization in the magma chamber and/or multi-stage intrusions with different degrees of crystallization of

Oxygen isotopes in garnet and accessory minerals to constrain fluids in subducted crust

Science.gov (United States)

Rubatto, Daniela; Gauthiez-Putallaz, Laure; Regis, Daniele; Rosa Scicchitano, Maria; Vho, Alice; Williams, Morgan

2017-04-01

Fluids are considered a fundamental agent for chemical exchanges between different rock types in the subduction system. Constraints on the sources and pathways of subduction fluids thus provide crucial information to reconstruct subduction processes. Garnet and U-Pb accessory minerals constitute some of the most robust and ubiquitous minerals in subducted crust and can preserve multiple growth zones that track the metamorphic evolution of the sample they are hosted in. Microbeam investigation of the chemical (major and trace elements) and isotopic composition (oxygen and U-Pb) of garnet and accessory minerals is used to track significant fluid-rock interaction at different stages of the subduction system. This approach requires consideration of the diffusivity of oxygen isotopes particularly in garnet, which has been investigated experimentally. The nature of the protolith and ocean floor alteration is preserved in relict accessory phases within eclogites that have been fully modified at HP conditions (e.g. Monviso and Dora Maira units in the Western Alps). Minerals in the lawsonite-blueschists of the Tavsanli zone in Turkey record pervasive fluid exchange between mafic and sedimentary blocks at the early stage of subduction. High pressure shear zones and lithological boundaries show evidence of intense fluid metasomatism at depth along discontinuities in Monviso and Corsica. In the UHP oceanic crust of the Zermatt-Saas Zone, garnet oxygen isotopes and tourmaline boron isotopes indicate multistage fluid infiltration during prograde metamorphism. Localized exchanges of aqueous fluids are also observed in the subducted continental crust of the Sesia-Lanzo Zone. In most cases analyses of distinct mineral zones enable identification of multiple pulses of fluids during the rock evolution.

Micro tectonic milonitas analysis in the extreme south of the Sarandi del Yi shear zone: Kinematics and deformation conditions

International Nuclear Information System (INIS)

Oyhantçabal, P; Suarez, I; Seluchi, N; Martinez, X.

2010-01-01

The Shear Zone divides Sarandi del Yi Craton River Plate in Piedra Alta and Nico Perez land . The southern end of this zone extends to north - south from the vicinity of the town of Minas to Punta Solis. The predominant lithology of the study area consists of a granitic mylonite with abundant muscovite and biotite. Structural data of foliation , stretching lineation and kinematic indicators were surveyed .Petrographic analysis shows that quartz is presented as ribbons polycrystalline product subgrain rotation recrystallization and grain boundary migration . Feldspar porphyroclasts are partially recrystallized in developing type structures c ore and mantle . Kinematic indicators such as sigma porphyroclasts , mica fish and oblique foliation defined consistently sinistral sense . The presence of stable and mirmequitas in the plane of biotite foliation along the microstructures described in quartz and feldspar , can be inferred temperature conditions between 450 ° C and 550° C during deformation

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

Limpet Shells from the Aterian Level 8 of El Harhoura 2 Cave (Témara, Morocco): Preservation State of Crossed-Foliated Layers

Science.gov (United States)

Nouet, Julius; Chevallard, Corinne; Farre, Bastien; Nehrke, Gernot; Campmas, Emilie; Stoetzel, Emmanuelle; El Hajraoui, Mohamed Abdeljalil; Nespoulet, Roland

2015-01-01

The exploitation of mollusks by the first anatomically modern humans is a central question for archaeologists. This paper focuses on level 8 (dated around ∼ 100 ka BP) of El Harhoura 2 Cave, located along the coastline in the Rabat-Témara region (Morocco). The large quantity of Patella sp. shells found in this level highlights questions regarding their origin and preservation. This study presents an estimation of the preservation status of these shells. We focus here on the diagenetic evolution of both the microstructural patterns and organic components of crossed-foliated shell layers, in order to assess the viability of further investigations based on shell layer minor elements, isotopic or biochemical compositions. The results show that the shells seem to be well conserved, with microstructural patterns preserved down to sub-micrometric scales, and that some organic components are still present in situ. But faint taphonomic degradations affecting both mineral and organic components are nonetheless evidenced, such as the disappearance of organic envelopes surrounding crossed-foliated lamellae, combined with a partial recrystallization of the lamellae. Our results provide a solid case-study of the early stages of the diagenetic evolution of crossed-foliated shell layers. Moreover, they highlight the fact that extreme caution must be taken before using fossil shells for palaeoenvironmental or geochronological reconstructions. Without thorough investigation, the alteration patterns illustrated here would easily have gone unnoticed. However, these degradations are liable to bias any proxy based on the elemental, isotopic or biochemical composition of the shells. This study also provides significant data concerning human subsistence behavior: the presence of notches and the good preservation state of limpet shells (no dissolution/recrystallization, no bioerosion and no abrasion/fragmentation aspects) would attest that limpets were gathered alive with tools by

Limpet Shells from the Aterian Level 8 of El Harhoura 2 Cave (Témara, Morocco: Preservation State of Crossed-Foliated Layers.

Directory of Open Access Journals (Sweden)

Julius Nouet

Full Text Available The exploitation of mollusks by the first anatomically modern humans is a central question for archaeologists. This paper focuses on level 8 (dated around ∼ 100 ka BP of El Harhoura 2 Cave, located along the coastline in the Rabat-Témara region (Morocco. The large quantity of Patella sp. shells found in this level highlights questions regarding their origin and preservation. This study presents an estimation of the preservation status of these shells. We focus here on the diagenetic evolution of both the microstructural patterns and organic components of crossed-foliated shell layers, in order to assess the viability of further investigations based on shell layer minor elements, isotopic or biochemical compositions. The results show that the shells seem to be well conserved, with microstructural patterns preserved down to sub-micrometric scales, and that some organic components are still present in situ. But faint taphonomic degradations affecting both mineral and organic components are nonetheless evidenced, such as the disappearance of organic envelopes surrounding crossed-foliated lamellae, combined with a partial recrystallization of the lamellae. Our results provide a solid case-study of the early stages of the diagenetic evolution of crossed-foliated shell layers. Moreover, they highlight the fact that extreme caution must be taken before using fossil shells for palaeoenvironmental or geochronological reconstructions. Without thorough investigation, the alteration patterns illustrated here would easily have gone unnoticed. However, these degradations are liable to bias any proxy based on the elemental, isotopic or biochemical composition of the shells. This study also provides significant data concerning human subsistence behavior: the presence of notches and the good preservation state of limpet shells (no dissolution/recrystallization, no bioerosion and no abrasion/fragmentation aspects would attest that limpets were gathered alive

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)

X-ray color maps of the zoned garnets from Silgará Formation metamorphic rocks,SantanderMassif, Eastern Cordillera (Colombia

Directory of Open Access Journals (Sweden)

Takasu Akira

2010-12-01

Full Text Available

The metamorphic rocks of the Lower Paleozoic Silgará Formation of the Santander Massif, Eastern Cordillera (Colombia, were affected by a Barrovian-type metamorphism under low to high temperature and medium pressure conditions. These rocks contain garnet porphyroblasts, which show several kinds of chemical zoning patterns. The garnet grains behave as closed systems with respect to the rock matrix. Most of the observed zoning patterns are due to gradual changes in physicochemical conditions during growth. However, some garnet grains show complex zoning patterns during multiple deformation and metamorphic events.

2005 dossier: granite. Tome: architecture and management of the geologic disposal

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 - 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.)

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

Reconnaissance geochemical exploration of the plutons of quartz monzonite and granite in the Jabal Lababa and Ar Rayth areas, southern Asir, Kingdom of Saudi Arabia

Science.gov (United States)

Overstreet, W.C.; Assegaff, A.B.; Jambi, Mohammed; Hussain, M.A.; Selner, G.I.; Matzko, J.J.

1985-01-01

Geochemical reconnaissance for rare metals in plutons of albite-muscovite granite and quartz monzonite in the vicinity of Jabal Lababa disclosed positive geochemical anomalies for beryllium, tantalum, thorium, lanthanum, niobium, tin, yttrium, and zirconium. The low anomalous values for the rare metals in rocks and the short mechanical dispersion trains, seldom exceeding 4 km in length, of rare-metal-bearing heavy minerals, are interpreted to indicate that primary deposits of these metals are lacking, and any placers would be small and low in tenor.

Optimizing white light luminescence in Dy3+-doped Lu3Ga5O12 nano-garnets

International Nuclear Information System (INIS)

Haritha, P.; Linganna, K.; Venkatramu, V.; Martín, I. R.; Monteseguro, V.; Rodríguez-Mendoza, U. R.; Babu, P.; León-Luis, S. F.; Jayasankar, C. K.; Lavín, V.

2014-01-01

Trivalent dysprosium-doped Lu 3 Ga 5 O 12 nano-garnets have been prepared by sol-gel method and characterized by X-ray powder diffraction, high-resolution transmission electron microscopy, dynamic light scattering, and laser excited spectroscopy. Under a cw 457 nm laser excitation, the white luminescence properties of Lu 3 Ga 5 O 12 nano-garnets have been studied as a function of the optically active Dy 3+ ion concentration and at low temperature. Decay curves for the 4 F 9/2 level of Dy 3+ ion exhibit non-exponential nature for all the Dy 3+ concentrations, which have been well-fitted to a generalized energy transfer model for a quadrupole-quadrupole interaction between Dy 3+ ions without diffusion. From these data, a simple rate-equations model can be applied to predict that intense white luminescence could be obtained from 1.8 mol% Dy 3+ ions-doped nano-garnets, which is in good agreement with experimental results. Chromaticity color coordinates and correlated color temperatures have been determined as a function of temperature and are found to be within the white light region for all Dy 3+ concentrations. These results indicate that 2.0 mol% Dy 3+ ions doped nano-garnet could be useful for white light emitting device applications

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

Distribution of monazite in granite and alluvial of South Bangka

International Nuclear Information System (INIS)

Ngadenin

2011-01-01

Monazite is one source of thorium (Th), which has significant economic value and potential as an alternative fuel of nuclear power plants. The aims of research is to find out the distribution monazite alternative fuel of nuclear power plants. The aims of research is to find out the distribution monazite and its potential as a resource of radioactive minerals on the Bangka Island, then the data will be used and its potential as a resource of radioactive minerals on the Bangka Island, then the data will be used as a reference in the development of radioactive minerals exploration areas in the coming year. The research location is in the Bencah and Gadung villages, South Bangka Regency. The method used is the geological mapping, sampling of rock for petrographic, mineragraphic and autoradiographic analysis and heavy mineral for grains counting analysis. The results showed that lithologic area of Bencah Village composed of clay stone and alluvial deposits, while the Gadung Village composed by granite and alluvial deposits. Granite Gadung is predicted as the ilmenite series granite and tend to be of S type, while the material of Bencah alluvial is predicted come from the Klabat granite groups. In general, distribution of monazite in the alluvial slightly more potent of monazite than in the granite so that the development of radioactive minerals exploration will be prioritized in the alluvial areas. (author)

Platinum/yttrium iron garnet inverted structures for spin current transport

Energy Technology Data Exchange (ETDEWEB)

Aldosary, Mohammed; Li, Junxue; Tang, Chi; Xu, Yadong; Shi, Jing [Department of Physics and Astronomy and SHINES Energy Frontier Research Center, University of California, Riverside, California 92521 (United States); Zheng, Jian-Guo [Irvine Materials Research Institute, University of California, Irvine, California 92697 (United States); Bozhilov, Krassimir N. [Central Facility for Advanced Microscopy and Microanalysis, University of California, Riverside, California 92521 (United States)

2016-06-13

30-80 nm thick yttrium iron garnet (YIG) films are grown by pulsed laser deposition on a 5 nm thick sputtered Pt atop gadolinium gallium garnet substrate (GGG) (110). Upon post-growth rapid thermal annealing, single crystal YIG(110) emerges as if it were epitaxially grown on GGG(110) despite the presence of the intermediate Pt film. The YIG surface shows atomic steps with the root-mean-square roughness of 0.12 nm on flat terraces. Both Pt/YIG and GGG/Pt interfaces are atomically sharp. The resulting YIG(110) films show clear in-plane uniaxial magnetic anisotropy with a well-defined easy axis along 〈001〉 and a peak-to-peak ferromagnetic resonance linewidth of 7.5 Oe at 9.32 GHz, similar to YIG epitaxially grown on GGG. Both spin Hall magnetoresistance and longitudinal spin Seebeck effects in the inverted bilayers indicate excellent Pt/YIG interface quality.

A Rb-Sr isotope study of a young granite sheet at Marble Delta, southern Natal

International Nuclear Information System (INIS)

Naidoo, D.D.; Eglington, B.M.; Harmer, R.E.

1989-01-01

Rb-Sr isotope data are presented for two apophyses of a granite sheet intrusive into marble at Marble Delta, southern Natal. Granite samples collected near the margins of these apophyses contain calcite and are thought to have been contaminated by the marble during intrusion of the granite magma. In contrast, those further away from contacts lack calcite. The 'uncontaminated' granite samples define an isochron date of 899 ± 11 Ma. This data is thought to represent the intrusive age of the granite sheet. 11 refs., 5 figs., 2 tabs

Major element composition of the lithospheric mantle under the North Atlantic craton

DEFF Research Database (Denmark)

Bizzarro, Martin; Stevenson, R.K.

2003-01-01

nature of the Sarfartoq mantle showing comparable degrees of depletion to other cratonic roots. Modal analyses indicate that the Sarfartoq mantle is not typified by the orthopyroxene enrichment observed in the Kaapvaal root, but shows more affinity with the Canadian Arctic (Somerset Island), Tanzania...... is compositionally layered as follows: (1) an internally stratified upper layer (70 to 180 km) consisting of coarse, un-deformed, refractory garnet-bearing and garnet-free peridotites and, (2) a lower layer (180 to 225 km) characterized by fertile, CPX-bearing, porphyroclastic garnet lherzolites. The stratification...

Immiscible melt droplets in garnet, as represented by ilmenite-magnetite-spinel spheroids in an eclogite-garnet peridotite association, Blanský les Granulite Massif, Czech Republic

Czech Academy of Sciences Publication Activity Database

Vrána, S.; Ackerman, Lukáš; Erban, V.; Halodová, P.

2016-01-01

Roč. 101, č. 1 (2016), s. 82-92 ISSN 0003-004X Institutional support: RVO:67985831 Keywords : eclogite * Fe-Ti-rich melt * garnet peridotite * garnetite * Ilmenite-magnetite-spinel * Invited Centennial article * Moldanubian Zone * UHP crystallization Subject RIV: DD - Geochemistry Impact factor: 2.021, year: 2016

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

Phonon-impurity relaxation and acoustic wave absorption in yttrium-aluminium garnet crystals with impurities

International Nuclear Information System (INIS)

Ivanov, S.N.; Kotelyanskij, I.M.; Medved', V.V.

1983-01-01

The experimental results of investigations of the influence of substitution impurities in the yttrium-aluminium garnet lattice on absorption of high-frequency acoustic waves are presented. It is shown that the phonon-impurity relaxation processses affect at most the wave absorption and have resonance character when the acoustic wave interacts with the thermal phonon group in the vicinity of the perturbed part of the phonon spectrum caused by the impurity. The differences of time values between inelastic and elastic thermal phonons relaxations determined from the data on longitudinal and shear waves in pure and impurity garnet crystals are discussed

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

Figure-Ground Processing: A Reassessment of Gelb and Granit.

Science.gov (United States)

Nelson, Rolf; Hebda, Nicholas

2018-03-01

In 1923, Adhemar Gelb and Ragnar Granit, two prominent researchers in early Gestalt perceptual theory, reported a lower threshold for detection of a target (a small colored dot) on the ground region of an image than on an adjacent figural region. Although their results had a wide influence on the understanding of figure-ground perception, they are at odds with more recent investigations in which figural regions appear to have a processing advantage over ground regions. The two present studies replicated Gelb and Granit's experiment using a similar figure-ground stimulus albeit with a two-alternative forced choice procedure rather than their original method of adjustment. Experiment 1 found that, contrary to Gelb and Granit's findings, a detection advantage was found for the figural over the ground region. Experiment 2 indicated that explicit contours might have played a role in detection.

Review of geomechanics data from French nuclear explosions in the Hoggar granite, with some comparisons to tests in US granite

International Nuclear Information System (INIS)

Heuze, F.E.

1983-05-01

Numerous unclassified reports on the French nuclear explosions in the Hoggar (1961-1966) were reviewed from the standpoint of geomechanics. The following aspects of the tests are summarized: spectral content of the tests compared to U.S. results; shock front positions with time; cavity radius as a function of yield, coupling, density of rock, rock shear strength, and overburden; radial pressure, tangential pressure and peak velocity as a function of distance and yield; pressure vs. time at various distances; mechanical properties of granite; scaling laws for acceleration, velocity and displacement as a function of yield and distance for all Hoggar shots; extent of tunnel damage as a function of distance and yield; time to collapse of chimney as a function of yield, or cavity radius; extent of granite crushing and disking as a function of distance and yield cavity height relation to cavity radius; faulting and jointing on the Taourirt Tan Afella massif; and influence of water content on cavity radius vs. yield. Whenever possible, these French data are compared to corresponding data obtained in the U.S. granite events Hard Hat, Shoal, and Piledriver. The following results emerge from the comparison: (1) agreement is found between the French and U.S. experience for: mechanical properties of the granites, rock damage due to the blast, and yield-scaled peak values of acceleration, velocity and displacement; and (2) lack of agreement exists for: cavity size, chminey height, and time to cavity collapse. Average spacing of rock joints also was about 5 times greater in the Hoggar

High level and long life radioactive wastes. Todays situation and future evolutions. Framework and process of the Granite collegial mission of dialogue. FAQ about the Granite collegial mission of dialogue

International Nuclear Information System (INIS)

2000-03-01

On December 9, 1998, the French government decided the construction of two underground laboratories for the study of the disposal of radioactive wastes in the deep underground. One site will be located in a granitic massif which remains to be determined. This document presents the framework and the different steps of the 'Granite' mission: the situation of radioactive wastes in France, some data about the conditioning, storage and reprocessing of high activity and long life radioactive wastes, the legal framework of the management of radioactive wastes and the related warranties, the disposal in deep underground and the realization of underground research laboratories, the government decision of December 9, 1998, the 'Granite' collegial mission of dialogue and the different steps of the geological surveys about granites. A second part answers some frequently asked questions about the 'Granite' collegial mission of dialogue: decision procedure, planning of the mission, consultation of the geologic survey, role of the mission, public information etc.. (J.S.)

Laser ablation of Bi-substituted gadolinium iron garnet films

International Nuclear Information System (INIS)

Watanabe, N.; Hayashida, K.; Kawano, K.; Higuchi, K.; Ohkoshi, M.; Tsushima, K.

1995-01-01

Bi-substituted gadolinium iron garnet films were deposited by laser ablation. The composition, the structure and the magnetic properties of the films were found to be strongly dependent both on the compositions of the targets and on the pressure of oxygen. The highest values of Bi-substitution up to x=1.44 with uniform composition were obtained, after annealing in air. ((orig.))

The formation and trace elements of garnet in the skarn zone from the Xinqiao Cu-S-Fe-Au deposit, Tongling ore district, Anhui Province, Eastern China

Science.gov (United States)

Xiao, Xin; Zhou, Tao-fa; White, Noel C.; Zhang, Le-jun; Fan, Yu; Wang, Fang-yue; Chen, Xue-feng

2018-03-01

Xinqiao is a large copper-gold deposit and consists of two major mineralization types: stratabound and skarn. The skarn occurs along the contact between a quartz diorite intrusion and Carboniferous-Triassic limestone. Xinqiao has a strongly developed skarn zone, including endoskarn and exoskarn; the exoskarn is divided into proximal and distal exoskarn. We present systematic major, trace and rare earth element (REE) concentrations for garnets from the skarn zone, discuss the factors controlling the incorporation of trace elements into the garnets, and constrain the formation and evolution of the garnet from skarn zone in Xinqiao deposit. Grossular (Adr20-44Grs56-80) mostly occurs in endoskarn and has typical HREE-enriched and LREE-depleted patterns, with small Eu anomalies and low ∑REE. Garnets from the exoskarn show complex textures and chemical compositions. The composition of garnets range from Al-rich andradite (Adr63-81Grs19-47) to andradite (Adr67-98Grs2-33). Garnet in endoskarn has typical HREE-enriched and LREE-depleted patterns. Al-rich andradite in proximal skarn has small Eu anomalies and moderate ∑REE. Andradite from distal exoskarn shows strong positive Eu anomalies and has variable ∑REE. The U, Y, Fe and Al relationship with ∑REE shows that two mechanisms controlled incorporation of REE into the garnets: crystal chemistry (substitution and interstitial solid solution) mainly controlled in the endoskarn garnet (grossular) and the proximal exoskarn (Al-rich andradite), and fluid and rock chemistry (surface adsorption and occlusion) controlled REEs in the distal exoskarn. Furthermore, Al has a negative relationship with ∑REE indicating that REE3+ did not follow a coupled, YAG-type substitution into the garnets. Variations in textures and trace and rare earth elements of garnets suggest that the garnets in the endoskarn formed by slow crystal growth at low W/R ratios and near-neutral pH in a closed system during periods of diffusive metasomatism

Link between the granitic and volcanic rocks of the Bushveld Complex, South Africa

Science.gov (United States)

Schweitzer, J. K.; Hatton, C. J.; De Waal, S. A.

1997-02-01

Until recently, it was proposed that the Bushveld Complex, consisting of the extrusive Rooiberg Group and the intrusive Rashoop Granophyre, Rustenburg Layered and Lebowa Granite Suites, evolved over a long period of time, possibly exceeding 100 Ma. Most workers therefore considered that the various intrusive and extrusive episodes were unrelated. Recent findings suggest that the intrusive, mafic Rustenburg Layered Suite, siliceous Rashoop Granophyre Suite and the volcanic Rooiberg Group were synchronous, implying that the Bushveld igneous event was short-lived. Accepting the short-lived nature of the complex, the hypothesis that the granites are genetically unrelated to the other events of the Bushveld Complex can be reconsidered. Re-examination of the potential Rooiberg Group/Lebowa Granite Suite relationship suggests that the granites form part of the Bushveld event. Rhyolite lava, granite and granophyre melts originated from a source similar in composition to upper crustal rocks. This source is interpreted to have been melted by a thermal input associated with a mantle plume. Granite intruded after extrusion of the last Rooiberg rhyolite, or possibly overlapped in time with the formation of the youngest volcanic flows.

Rare metal granites in the structures of the Russian sector of Pacific ore belt

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В. И. Алексеев

2016-08-01

Full Text Available Data are presented on the geology of areas of rare metal granites proliferation in the Russian sector of the Pacific Ore Belt that make one take a fresh look at the East Asian granitoid area to update its metallogeny. History is reviewed of studying rare metal granites of the Russian Far East. As a rule, these are found in the vicinity of major tungsten-stanniferous ore deposits, except much later than discovering the former, at the stages of their assessment and survey. Rare earth granites are usually missed by the geologists during the early stages of regional geological surveys due to their small size, weak eroding and external similarity with earlier granites. Using the examples of the Central Polousny, Badzhal and Kuyviveem-Pyrekakay regions the structural and geological conditions are characterized of localization of rare metal granites. Comparative analysis of geological situations made it possible to formulate the areal character of manifestation of rare metal granites; their confinedness to late Mesozoic orogenic arched uplifts of bogen structures above deep granitoid batholiths; positioning in the areas where longitudinal and transversal deep laying faults cross; gravitation to the environs of pre-Cambrian median masses. Similarity of structural-geological conditions for manifestation of the well-studied ore-containing granites serves to confirm the hypothesis on the joint stage of late Cretaceous rare metal magmatism in the Russian sector of the Pacific Ore Belt and the existence in the region of a magmatic super-province – the Far East belt of rare metal granites that includes the Novosibirsk-Chukotka, the Yana-Kolyma and the Sikhote-Alin rare metal – granite provinces.

Comparative Study on The Geological and Geochemical Characteristics of Some Rare-Metal Granites, Southeastern Desert, Egypt

International Nuclear Information System (INIS)

El Galy, M.M.; Khaleal, F.M.; Bakhit, A.F.

2016-01-01

The Egyptian younger granites are characterized by the presence of more than 14 exposures of rare- metal granites. The studied granites are included into three geological modes of occurrence. The first includes Igla and Abu Dabbab plutons, which occur as small stocks of circular, ovoid, or apophyses and leucocratic outcrops. The second comprises the plugs and dyke-like bodies intruded peralkaline granites of Bir Um Hibal. The third includes Homrit Waggat and Muweilha plutons. vThey cover small areas and exhibit obvious pervasive post magmatic alterations. The petrographic and mineralogical studies are confirmed by the geochemical investigations indicating that the concerned rare-metal granites being broadly distinguished into magmatic and metasomatic associations. The magmatic granite associations are further subdivided into two subgroups; i) peraluminous granites (Li-mica rich) including Igla and Abu Dabbab plutons and ii) peralkaline granites including Um Hibal pluton. The studied peraluminous granites are generally enriched in Nb, Rb, Ta, Li, F, Y, Zr, U and Th elements. The peralkaline granites are enriched in K_,0 oxide as well as Zr, Nb, F, U, Th and Ta elements. On the other hand, the metasomatic granite associations are represented by Homrit Waggat and Muweilha plutons. They are characterized by high contents of Na_2O oxide as well as Nb, Ta, U, Th and Rb elements. Igla pluton has highest average U and Th contents (42 ppm and 58 ppm respectively), while Um Hibal pluton has lowest average U and Th contents (14 ppm and 26 ppm respectively)

Dating Ore Deposit Using Garnet U–Pb Geochronology: Example from the Xinqiao Cu–S–Fe–Au Deposit, Eastern China

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Yu Zhang

2018-01-01

Full Text Available The large Xinqiao Cu–S–Fe–Au deposit in the Tongling ore district, Eastern China, is characterized by a large-scale stratiform orebody, in which garnet is widely distributed as the main gangue mineral associated with mineralization. Xinqiao garnet can be divided into early (Grt1 and late (Grt2 generations based on extensive back-scattered electron (BSE imaging observations. Laser ablation (LA-ICP-MS trace element and U–Pb isotope composition analyses indicate that uranium occurs homogeneously within the Xinqiao garnet, and Grt1 and Grt2 have weighted average 207Pb-corrected 206Pb/238U ages of 137.0 ± 7.8 Ma (Mean standard weighted deviation (MSWD = 4.9 and 129.6 ± 7.1 Ma (MSWD = 1.6, respectively, similar to the zircon U–Pb age (139.6 ± 1.5 Ma of the Jitou intrusion. These garnet U–Pb ages, combined with the low MnO content and various Y/Ho ratios, suggest that the Xinqiao garnet is likely to have a magmatic hydrothermal replacement origin associated with the Jitou stock. Based on previous studies of the Xinqiao deposit, we infer that the Xinqiao stratiform orebody may have formed from the Early Cretaceous magmatic hydrothermal fluids associated with the Jitou stock, and may have been generated by the Early Cretaceous tectono-thermal event in Eastern China.

Spectral and luminescence properties of Cr(3+) ad Nd(3+) ions in gallium garnet crystals

Science.gov (United States)

Denisov, A. L.; Ostroumov, V. G.; Saidov, Z. S.; Smirnov, V. A.; Shcherbakov, I. A.

1986-01-01

The effective peak stimulated-emission cross section of chromium-doped gadolinium-scandium-gallium garnets (GSGG) has been determined to be 8.5 x 10 to the -21st sq cm at room temperature. The values of the energy-gap Delta E(2E-4T2) chromim fluorescence lifetime and the chromium to neodymium energy-transfer parameter C(DA) (Cr-Nd) are determined for several gallium garnets. Temperature-dependent absorption and luminescence spectra of neodymium-doped GGG and GSGG are reported and discussed in the context of their use as laser materials.

Magnetooptical garnet films: preparation, characterisation, application

International Nuclear Information System (INIS)

Goernert, P.; Lorenz, A.; Lindner, M.; Richert, H.

2007-01-01

Full text: In contemporary magnetooptics both Kerr effect and Faraday effect are applied. The Kerr effect of metals and alloys - such as Fe, Ni, Co, FePt, CoPt, MnBi, PtMnSb - with thicknesses 300 μm are established as commercial isolators in optical systems and for developments of waveguide applications. Bi-REIG is prepared mostly by conventional liquid phase epitaxy (LPE) in PbO-B 2 O 3 -Bi 2 O 3 based solvents and sometimes by laser ablation and as nanocrystalline powders. In each case high Faraday rotation and low optical absorption is necessary. Additionally, magnetooptical sensors should possess high sensitivity and a large dynamic range. All these demands can be fulfilled with (REBi) 3 (FeGaAl) 5 O 12 LPE layers. Here we discuss some new results concerning preparation, characterisation, and application of Bi-TmIG and Bi-DyIG LPE layers on high-quality gadolinium gallium garnet (GGG) or lattice matched Ca-, Mg-, Zr-substituted GGG substrates. Optimization of flux melt composition and under cooling result in sensor films with a Faraday rotation of e.g. -1.2 0 /μm at a wavelength of l=590 nm and saturation induction of Bs=70 mT. Such films are already applied for forensic investigations. However, the responsivity of the garnet films is restricted by their coercivity Hc. Surface defects are found to give rise to pinned magnetic domains correlated with typical hysteresis. Obviously, Hc and the formation of pits are due to misfit stress and substrate surface quality. Besides, it is shown that an increase of working temperature leads to smaller coercivities. (authors)

Petrology and isotope systematics of magma mushes: some porphyritic granitoids of northeastern Brazil

International Nuclear Information System (INIS)

McMurry, J.; Long, L.E.; Sial, A.N.

1987-01-01

More than 80 coarsely porphyritic granitoid plutons with K-feldspar megacrysts (Itaporanga-type granites) intrude metamorphic rocks of Northeastern Brazil. Textural evidence for filter pressing and flow foliation indicates that these bodies were emplaced as viscous, crystal-laden mushes. A representative Itaporanga-type pluton, the Monte das Gameleiras intrusion, consists of a variety of rock types with SiO 2 ranging from 49.5 to 71.6 weight percent. Chemically and petrographically, this hornblende-bearing pluton has I-type characteristics with some S-type affinities. Whole-rock oxygen isotope data are in keeping with the distribution of δO 18 , for unaltered granitic rocks. Similarly, REE data suggest a single magmatic process, at least for the more felsic rock types, without post-intrusive effects. A 5-point, whole-rock Rb-Sr isochron for the Monte das Gameleiras pluton gives t = 511 ± 26 Ma andan initial, 87 Sr/ 86 Sr = 0.7099 ± 0.0004. This is contrasted with disparate ages calculated from texturally similar bodies such as the Fazenda Nova pluton, for which a 5-point whole-rock isochron gives t = 630 ± 24 Ma with initial 87 Sr/ 86 Sr = 0.7065 ± 0.0005, and the type locality Itaporanga pluton, for which a 6-point isochron gives t= 625 ± 22 Ma. (author) [pt

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

The topology of Lagrangian foliations of integrable systems with hyperelliptic Hamiltonian

International Nuclear Information System (INIS)

Kudryavtseva, Elena A; Lepskii, Timur A

2011-01-01

We study the integrable Hamiltonian systems (C 2 ,Re(dz and dw),H=Ref(z,w)) with the additional first integral F=Imf which correspond to the complex Hamiltonian systems (C 2 ,dz and dw,f(z,w)) with a hyperelliptic Hamiltonian f(z,w)=z 2 +P n (w), n element of N. For n≥3 the system has incomplete flows on any Lagrangian leaf f -1 (a). The topology of the Lagrangian foliation of such systems in a small neighbourhood of any leaf f -1 (a) is described in terms of the number n and the combinatorial type of the leaf--the set of multiplicities of the critical points of the function f that belong to the leaf. For odd n, a complex analogue of Liouville's theorem is obtained for those systems corresponding to polynomials P n (w) with simple real roots. In particular, a set of complex canonical variables analogous to action-angle variables is constructed in a small neighbourhood of the leaf f -1 (0). Bibliography: 12 titles.

Contribution to the radioactivity of Um Ara granitic pluton, south-eastern desert, Egypt

International Nuclear Information System (INIS)

El Reedy, M.W.; Kamel, A.F.; Mansour, S.E.I.

1988-01-01

Um Ara area lies in the southern part of the eastern desert between latitudes 22 0 30' and 22 0 41'N and longitudes 33 0 46' and 33 0 54'E. Several types of granitic varieties ranging from high silica granite (SiO 2 >75%) to low silica granite (SiO 2 68-70%) occur in Um Ara granitic pluton. Surface samples were collected from the high anomalous locations in the pluton together with trenches samples (about 50cm in depth). The U content in the surface samples ranges from 69 to 7 ppm while in trenches samples, it ranges from 38 to 759 ppm. The thorium content on the other hand ranges from 34 to 402 ppm in surface samples and from 158 to 316 ppm in trenches samples. Some samples show no Th contents. The Th/U ratios ranges from 0.065 to 3.137 in surface samples and from 0.386 to 2.590 in trenches samples. An enrichment of U content is the main feature characterising this granitic pluton, it is mainly connected with the fractured zones. Uranium is mostly present as secondary U mineralization accompanied by Fe, Mn and to some extent by carbonate materials. A hydrothermal origin could be considered for this U mineralization in the pluton. Primary U mineralization (pitchblende) together with secondary mineralization was observed in some locations in the area disseminated in the granite, this reflects the syngenetic origin of this granitic type

Nonlinear FMR spectra in yttrium iron garnet

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Yu.M. Bunkov, P.M. Vetoshko, I.G. Motygullin, T.R. Safin, M.S. Tagirov, N.A. Tukmakova

2015-12-01

Full Text Available Results of demagnetizing effect studies in yttrium iron garnet Y3Fe5O12 thin films are reported. Experiments were performed on X-Band of electron paramagnetic resonance spectrometer at room temperature. The ferromagnetic resonance (FMR spectra were obtained for one-layer single crystal YIG films for different values of the applied microwave power. Nonlinear FMR spectra transformation by the microwave power increasing in various directions of magnetic field sweep was observed. It is explained by the influence of the demagnetization action of nonequilibrium magnons.

Carboniferous granite basement dredged from a site on the southwest margin of the Challenger Plateau, Tasman Sea

International Nuclear Information System (INIS)

Tulloch, A.J.; Kimbrough, D.L.; Wood, R.A.

1991-01-01

Discordant zircon fractions from a granite sample dredged off a basement horst on the western margin of the Challenger Plateau yield a 335 ± 7 Ma lower intercept date interpreted as the crystallisation age of the granite. This age, and the modal composition of the granite, is similar to that of the Karamea Suite of Westland and Nelson, New Zealand, and some Tasmanian granites. The concordia upper intercept date of 1747 ± 300 Ma implies the presence of Proterozoic continental crustal material in the source region of the granite. The Challenger granite is distinct from older S-type granites of southeastern Australia and I-type granites of northern Victoria Land and Marie Byrd Land, Antarctica. Subsequent to emplacement, the granite was brecciated and hydrothermally altered. A K-Ar age of 95 Ma on hydrothermal sericite indicates that this event overlapped with a major crustal extension event recorded in Westland and Nelson, and predates the oldest known sea floor in the Tasman Basin by at least 11 Ma. (author). 23 refs., 3 figs., 2 tabs

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.

Fission track dating and estimation of uranium in some garnets of Rajasthan (India)

Energy Technology Data Exchange (ETDEWEB)

Singh, S; Virk, H S [Punjabi Univ., Patiala (India). Dept. of Physics

1978-09-01

The experimental procedure, involving the preparation, etching, thermal neutron irradiation and scanning of the garnet samples, is described. The calculated fission track ages and uranium concentration are tabulated.

Analysis of geological condition and prospecting potential of uranium metallogenesis in Maling granite mass

International Nuclear Information System (INIS)

Shao Fei; Zou Maoqing; Wu Yong; Xu Jinshan; Xu Wang; Chen Chang

2011-01-01

Based on the study of regional geological evolution of Maling granite mass, uranium content of granite mass and its peripheric strata, petrogeochemistry and the known spatial distribution pattern of uranium mineralization and ore-controlling structures, new recognition is 1) Maling composite mass is the 'S' type re-melted granite, 2) the accumulative area of regional uranium metallogenic substances forms uranium-rich re-melted strata, 3) magma evolution is the matter base for the uranium-rich hydrotherm, 4) NE-trending main faults are channels for metallogenesis and the lateral high-angle dipping faults, fractures and interlayer fractures in the peripheric strata are the spaces of mineralization. The ore intersected by drilling in Maling granite is acidic type. Prospecting potential of Maling granite mass is analyzed, and preferable prospecting space is delineated for further exploration. (authors)

High-pressure anatectic paragneisses from the Namche Barwa, Eastern Himalayan Syntaxis: Textural evidence for partial melting, phase equilibria modeling and tectonic implications

Science.gov (United States)

Guilmette, C.; Indares, A.; Hébert, R.

2011-05-01

Rare kyanite-bearing anatectic paragneisses are found as boudins within sillimanite-bearing paragneisses of the core of the Namche Barwa Antiform, Tibet. In the present study, we document an occurrence from the NW side of the Yarlung Zangbo River. These rocks mainly consist of the assemblage garnet + K-feldspar + kyanite ± biotite + quartz + rutile ± plagioclase with kyanite locally pseudomorphed by sillimanite. The documented textures are consistent with the rocks having undergone biotite-dehydration melting in the kyanite stability field, under high-P granulite facies conditions, and having experienced melt extraction. However textures related to melt crystallization are ubiquitous both in polymineralic inclusions in garnet and in the matrix, suggesting that a melt fraction had remained in these rocks. Phase equilibria modelling was undertaken in the NCKFMASTHO system with THERMOCALC. P-T pseudosections built with the bulk compositions of one aluminous and one sub-aluminous paragneiss samples predict a biotite-kyanite-garnet-quartz-plagioclase-K-feldspar-liquid-rutile ± ilmenite field, in which biotite-dehydration melting occurs, located in the P-T range of ~ 800-875 °C and ~ 10-17 kbar. In addition, the topologies of these pseudosections are consistent with substantial melt loss during prograde metamorphism. A second set of P-T pseudosections with melt-reintegrated model bulk compositions were thus constructed to evaluate the effect of melt loss. The integration of textural information, precise mineral modes, mineral chemistry, and phase equilibria modelling allowed to constrain a P-T path where the rocks are buried to lower crustal depths at peak P-T conditions higher than 14 kbar and 825 °C, possibly in the order of 15-16 kbar and 850 °C, followed by decompression and cooling to P-T conditions of around 9 kbar and 810 °C, under which the remaining melt was solidified. The implications for granite production at the NBA and for Himalayan tectonic models

A compilation of radioelement concentrations in granitic rocks of the contiguous United States

International Nuclear Information System (INIS)

Stuckless, J.S.; VanTrump, G. Jr.

1982-01-01

Concentration data for uranium, thorium, and potassium have been compiled for approximately 2,500 granitic samples from the contiguous United States. Uranium and thorium concentrations and ratios involving these elements exhibit a log-normal distribution with statistical parameters. In order to check for a bias in the results due to high concentrations of data in anomalous or heavily sampled areas, the data were reevaluated by averaging all analyses within a 0.5 0 latitude by 0.5 0 longitude grid. The resulting data set contains 330 entries for which radioelements are log-normally distributed. Mean values are not significantly different from those of the ungridded data, but standard deviations are lower by as much as nearly 50 percent. The areal distribution of anomalously high values (more than one standard deviation greater than the geometric mean) does not delineate large uranium districts by either treatment of the data. There is sufficient information for approximately 1,500 samples to permit subdivision of the granites by degree of alumina saturation. Relative to the six variables listed above, peraluminous samples have slightly lower mean values, but the differences are not statistically significant. Standard deviations are also largest for the peraluminous granites with α for Th/U nearly 3 times larger for peraluminous granite than for metaluminous granite. Examination of the variations in Th/U ratios for a few specific granites for which isotopic data are available suggests that variability is caused by late-stage magmatic or secondary processes that may be associated with ore-forming processes. Therefore, although anomalous radioelement concentrations in granitic rocks do not seem to be useful in delineating large uranium provinces with sediment-hosted deposits, highly variable uranium concentrations or Th/U ratios in granitic rocks may be helpful in the search for uranium deposits

Optical bistability in erbium-doped yttrium aluminum garnet crystal combined with a laser diode.

Science.gov (United States)

Maeda, Y

1994-01-10

Optical bistability was observed in a simple structure of an injection laser diode combined with an erbium-doped yttrium aluminum garnet crystal. Since a hysteresis characteristic exists in the relationship between the wavelength and the injection current of a laser diode, an optical memory function capable of holding the output status is confirmed. In addition, an optical signal inversion was caused by the decrease of transmission of the erbium-doped yttrium aluminum garnet crystal against the red shift (principally mode hopping) of the laser diode. It is suggested that the switching time of this phenomenon is the time necessary for a mode hopping by current injection.

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

Recurrent thermo-luminescence phenomenon in yttrium-aluminum garnet crystals

International Nuclear Information System (INIS)

Islamov, A.Kh.; Nuritdinov, I.; Esanov, Z.U.; Eshchanov, B.Kh.; Khayitov, I.A.

2014-01-01

Full text : The crystals of yttrium-aluminum garnet Y 2 Al 2 O 1 2 activated by cerium and praseodymium ions by their thermal and chemical durability as well as fast response are perspective scintillation materials. In this work the capture centres formed by action of the ionizing radiation on pure and doped by praseodymium and cerium crystals were investigated. The samples were grown using Chokhralsky method

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Paharpur gabbroic intrusive is an arcuate body running east–west paralleling the foliation of Chhotanagpur Granite Gneiss which acts as country rock. The main gabbroic body is intruded by a number of dolerite dykes running north–south. It is composed of clinopyroxene (Wo48En40Fs12–Wo51En40Fs09, mg no. 72–82) ...

Retardation of radionuclide transport by fracture flow in granite and argillaceous rocks

International Nuclear Information System (INIS)

Bradbury, M.H.; Green, A.

1985-11-01

Laboratory techniques have been developed for the measurement of diffusion rates and permeabilities through highly consolidated rock samples. The work has predominantly concentrated on the generation of diffusion data for slates and granites in particular. Rock properties fundamental to mass transfer processes have been obtained. Diffusion rates have been measured through weathered granite fissure surfaces and as a function of distance from such surfaces on core samples obtained from Troon, Cornwall. Pore connectivity over metre distances in granite cores has been shown to exist and diffusion coefficients were measured as a function of confining pressure in a specially designed rig. The Dsub(i) (intrinsic diffusion coefficient) values determined at ambient pressure were approximately a factor of 2 greater than those measured at pressures equivalent to 500 m of rock overburden. Some initial experiments on the accessibility of the pore space in granites to colloids based on a permeability technique indicated that such particles neither blocked pores nor penetrated through 15 mm thick samples over times of the order 2 to 3 thousand hours. Diffusion rates through samples of Canadian granites, some of which contained weathered fissure surfaces, were measured. (author)

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.

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 ("2"3"8U), thorium ('2"3"2Th) and potassium("4"0K) 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)

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

Deep fracturing of granite bodies. Literature survey, geostructural and geostatistic investigations

International Nuclear Information System (INIS)

Bles, J.L.; Blanchin, R.

1986-01-01

This report deals with investigations about deep fracturing of granite bodies, which were performed within two cost-sharing contracts between the Commission of the European Communities, the Commissariat a l'Energie Atomique and the Bureau de Recherches Geologiques et Minieres. The aim of this work was to study the evolution of fracturing in granite from the surface to larger depths, so that guidelines can be identified in order to extrapolate, at depth, the data obtained from surface investigations. These guidelines could eventually be used for feasibility studies about radioactive waste disposal. The results of structural and geostatistic investigations about the St. Sylvestre granite, as well as the literature survey about fractures encountered in two long Alpine galleries (Mont-Blanc tunnel and Arc-Isere water gallery), in the 1000 m deep borehole at Auriat, and in the Bassies granite body (Pyrenees) are presented. These results show that, for radioactive waste disposal feasibility studies: 1. The deep state of fracturing in a granite body can be estimated from results obtained at the surface; 2. Studying only the large fault network would be insufficient, both for surface investigations and for studies in deep boreholes and/or in underground galleries; 3. It is necessary to study orientations and frequencies of small fractures, so that structural mapping and statistical/geostatistical methods can be used in order to identify zones of higher and lower fracturing

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

Science.gov (United States)

Hashiba, K.; Fukui, K.

2016-07-01

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

Chemical analysis of minerals in granitic rocks by electron probe micro analyser

International Nuclear Information System (INIS)

Hiraoka, Yoshihiro

1994-01-01

The chemical compositions of minerals in a few granitic rocks were determined by electron probe micro analyser (EPMA). The accurate analytical data for standard feldspar groups were obtained by correcting the low analytical values of sodium and potassium that were arised from the damage in EPMA analysis. Using this method, feldspar groups and biotites in three granitic rocks gathered from Hiei, Hira and Kurama areas respectively, were analyzed. As the results, the local characteristics were observed in the kinds of feldspar groups and the chemical compositions of biotites that were contained in granitic rocks. (author)

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