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Sample records for craton geocronologia rb-sr

  1. Proterozoic biotite Rb-Sr dates in the northwestern part of the Yilgarn Craton, Western Australia

    International Nuclear Information System (INIS)

    Libby, W.G.; De Laeter, J.R.; Armstrong, R.A.

    1999-01-01

    Rb-Sr dating of biotite in the northwestern corner of the Yilgarn Craton identified four areas with distinctive age ranges. Biotite in the northwestern area, which includes the Narryer Terrane and part of the Murchison Terrane, yields reset Rb-Sr dates of ca 1650 Ma. In the western area, along the margin of the craton, biotite has been reset to 629 Ma. Eastward of these areas, mainly in the Murchison Terrane, the modal biotite date is near 2450 Ma, though because of a skewed distribution the mean date is closer to 2300 Ma. Dates in a transition zone between the western and eastern areas range broadly between 2000 and 1000 Ma, averaging about 1775 Ma. The western area and the transition zone are continuous with analogous areas south of the limits of the present study. The 1650 Ma dates in the northwestern area are probably related to plutonic and tectonic activity of similar age in the Gascoyne Province to the north. They may represent cooling after thermal resetting during tectonic loading by southward thrust-stacking of slices of Narryer Terrane and allochthonous Palaeoproterozoic volcanic arc and back arc rocks during the Capricorn Orogeny. This episode of crustal shortening resulted from the collision of the Yilgarn and Pilbara Cratons to form the West Australian Craton. The dates reflect cooling associated with subsequent erosion-induced rebound. The 2450 Ma biotite dates of the eastern area are similar to biotite dates found over most of the Yilgarn Craton and represent a background upon which the later dates have been superimposed. The origin of dates in the western area is unknown but may be related to an associated dolerite dyke swarm or to possible thrusting from the west. There is some evidence of minor later intrusion of felsic hypabyssal rock between 2000 and 2200 Ma and localised shearing in the Narryer area at about 1350 to 1400 Ma. One small area near Yalgoo with biotite Rb-Sr dates near 2200 Ma may be co genetic with the Muggamurra Swarm of dolerite

  2. A geochemical and Pb, Sr isotopic study of the evolution of granite-gneisses from the Bastar craton, Central India

    International Nuclear Information System (INIS)

    Sarkar, G.; Paul, D.K.; Misra, V.P.; de Laeter, J.R.; Mc Naughton, N.J.

    1990-01-01

    Preliminary Pb-Pb and Rb-Sr geochronology of granitic and gneissic rocks from the Sukma area of the Bastar craton, Central India, provides important constraints on crustal evolution. Much of the craton is made up of felsic orthogneisses and younger granitic intrusives, compositionally ranging from tonalite to granite. Pb-Pb isotopic data suggest the presence of ca. 3.0 Ga old gneisses. Younger granitic intrusives have been dated at ca. 2.6 Ga which represents a widespread resetting and/or emplacement event. Comparison of the Pb-Pb and Rb-Sr whole rock ages suggests that the latter were more perturbed after the gneiss-forming or emplacement events. All rock suites show significant geological scatter of isotopic data probably because of sampling on a regional scale, and reflect multi-stage isotopic evolution in a complex terrain. The present isotopic data indicate the presence of Archaean rock in the Bastar craton and suggest temporal similarity with the oldest crustal rocks in the Singhbhum and Dharwar cratons. (author). 18 refs., 4 tabs., 8 figs

  3. Preliminary study of geotectonic evolution of the southern region of Sao Francisco (MG, Brazil) craton: an interpretation based on Rb-Sr, K-Ar, Pb-Pb and fission track data

    International Nuclear Information System (INIS)

    Teixeira, W.; Fonseca, A.C.; Poupeau, G.; Padilha, A.V.; Zapparolli, L.H.; Kawashita, K.; Khoury, M.C.

    1985-01-01

    The results obtained from isotopic dating techniques (Rb-Sr, K-Ar, Pb-Pb and fission tracks) applied to samples from the southern region of Sao Francisco craton (Mg, Brazil) are discussed. Rb-Sr and Pb-Pb ages, in total rock, allowed the determination of crust enlargement, with eventual modifications of the pre-existing crust, during the Late Archean period (3000 to 2600 million years) and the Inferior Proterozoic period (2400 to 2100 m.y.). Three main cooling periods of time were determined by K-Ar dating of mica, amphiboles and total rock at the craton border: 2200 to 1700 m.y., 1300 to 1100 m.y. and 900 to 400 m.y. related, respectively, to superposition of three cycles: Transamazonico, Uruacuano and Brasiliano. Cooling below 110 0 C, detected by the fission track method applied to apatites, pointed out an age of 850 m.y. at the internal parts and 550 m.y. at the craton periphery, thus showing a progressive action of Brazilian marginal movable zones in the studied region. The application of these two techniques together enabled the evaluation of the rocks cooling shape. Cooling of these samples was complex between 2700 and 2200 m.y. and slow from 2000 m.y. onwards. The integrated treatment of data from the various dating techniques is of great importance to know the geotectonic evolution of ancient polycyclic sites. (C.L.B.) [pt

  4. Archean crustal growth of the Imataca complex, Amazonian craton: Evidence from U-Pb-Sm-Nd and Rb-Sr geochronology

    International Nuclear Information System (INIS)

    Tassinari, C.C.G.; Teixeira, W; Nutman, A.P; Szabo, G.; Mondin, M.; Sato, K; Santos, A.P; Siso, C.S

    2001-01-01

    The Archean Imataca Complex (IC), NW Amazonian Craton, forms a ENE-trending, fault-bounded block adjacent to the Paleoproterozoic Maroni-Itacai as magmatic arc (2.2 2.0 Ga) (Tassinari and Macambira, 1999). The IC rocks are complexely deformed, exhibiting elongated and symmetrical domes and thrusts combined with isoclinal folds. Transcurrent faults are also important, like the Guri Fault System - a zone of multiple faulting, shearing and mylonitization along the southeastern edge of the IC. In a pre-Pangean reconstruction using paleomagnetic data from rocks of the African counterpart, the Guri System is contiguous to the Sassandra (Ivory coast) and Zednes (Mauritaine) faults, in agreement also with the comparable geologic evolution between the NW Amazonian and the West Africa cratons, during the Archean and Late-Paleoproterozoic. The IC mainly composed of medium- to high grade quartz-feldspathic paragneiss, exhibits extensive mortar, augen, flaser and mylonitic textures. Calc-alkaline gneiss and granitoid rocks of igneous protolith are also present in the IC, as well as dolomitic marbles, orthopyroxene and magnetite quartzites, and BIFs that include huge ore deposits of Algoma type. Moreover, migmatite injections and anatexis (devoid of metasedimentary components) are widespread in the western part of Complex, the largest migmatite mass centered in Cerro La Ceiba. This paper reports zircon U-Pb SHRIMP, Sm-Nd and Rb-Sr isotopic data of different IC rocks in order to investigate their age and geological evolution within the tectonic framework of the Amazonian Craton (au)

  5. Musa's granite and Rio Maria's granodiorite Rb/Sr isotopic ages and geochemistry

    International Nuclear Information System (INIS)

    Gastal, M.C.P.; Macambira, M.J.B.; Medeiros, H.; Dall'Agnol, R.

    1987-01-01

    The Musa Granite and the Rio Maria Granodiorite are located at the eastern margin of the Amazonian craton, in the Rio Maria region, where a typical granite-greenstone terrain is characterized. Rb-Sr dating of six samples from different facies of Rio Maria Granodiorite furnished an age of 2564 ± 68 Ma with initial 87 Sr/ 86 Sr radio (IR) of 0.70288 ± 0.00092 (whole rock isochron; 1 ο error; MSWD = 2.26). Thirteen samples from the three facies of Musa Granite (monzogranites, syenogranites and intermediate to felsic hypabyssal rocks) gave Rb-Sr whole rock isochron with an age of 1692 ± 11 Ma and IR of 0.70777 ± 0.00023 (1 ο error, MSWD = 1.89). A preliminary attempt to individualize geochronologically the three facies was done resulting different ages and IRs. There is a coincidence between these ages and the emplacement sequence of these facies of the pluton. The actual meaning of the Rio Maria Granodiorite Rb-Sr age is still uncertain. It could be related to the end of the magmatic crystallization of the batholith as well as to the metamorphic-mylonitic event that affect it. Considering that the Jamon and Musa Granites are petrologically similar that they occur in the same area, it is interesting to note that latter is apparently a little older than the former. The IRs obtained for the two plutons are also not coincident. The isotopic Rb-Sr available data show that the exposed rocks of the Rio Maria Granodiorite have not been able to generate magmas with the compositions of the monzongranitic and the hypabyssal facies of the Musa pluton. On the other hand, rocks isotopically similar to the Rio Maria Granodiorite would theorically be able to generate the Jamon and a magma with the characteristics of the syenogranitic facies of the Musa pluton. (author) [pt

  6. 82Sr--82Rb radioisotope generator

    International Nuclear Information System (INIS)

    Grant, P.M.; Erdal, B.R.; O'Brien, H.A.

    1976-01-01

    An improved 82 Sr- 82 Rb radioisotope generator system, based upon the complexing ion exchange resin Chelex-100, has been developed. Columns of this material can be easily and rapidly milked, and the Rb-Sr separation factor for a fresh generator was found to be greater than 10 7 . Approximately 80 percent of the 82 Rb present was delivered in a 15-ml volume of aqueous 0.2 M NH 4 Cl solution. After more than 6 liters of eluant had been put through the generator, the Rb-Sr separation factor was still observed to be greater than 10 5 , and no unusual strontium breakthrough behavior was seen in the system over nearly three 82 Sr half lives. 2 claims, no drawings

  7. New Rb-Sr isotopic ages and geochemistry of granitic gneisses from southern Bastar: implications for crustal evolution

    International Nuclear Information System (INIS)

    Sarkar, G.; Gupta, S.N.; Bishui, P.K.

    1994-01-01

    Deformed gneisses from the southern Bastar craton yield Rb-Sr whole-rock ages of 2560 Ma and 2659 Ma with initial Sr ratios ranging between 0.70899 and 0.70726 respectively. The isotopic data are found to be scattered even at the outcrop scale which possibly indicate large-scale reworking of the gneisses during the period. The high initial Sr ratios that associate with scattering of the isotopic data reflect reworking of older gneisses. Geochemically, these gneisses are considered to be derived from an amphibolitic or basaltic protolith. The 2095 Ma (initial Sr ratio of 0.74312) old leucocratic granite intrusive into these gneisses represent early Proterozoic magmatic activity. Based on the available isotopic and geochemical data, it is suggested that the Bastar craton represents a polyphase, multicomponent terrain developed by repeated magmatism at a much earlier, probably during mid-Archaean, time and was extensively reworked during the time span between end-Archaean and early Proterozoic period. This reworking may be synchronous with coalescing of smaller crustal components possibly during the end-Archaean time. (author). 21 refs., 5 figs., 2 tabs

  8. The tectonic evolution of Southern part of the Sao Francisco Craton

    International Nuclear Information System (INIS)

    Teixeira, W.

    1986-01-01

    The potentiality of geochronology when it is applied to the geologic context of craton basement of archean areas is shown. Samples from southern part of the Sao Francisco Craton, in Brazil, were collected for petrographic analysis and geochronological data interpretation. The set of radiometric determinations was obtained by K-Ar, Rb-Sr, Pb-Pb and U-Pb methods. (M.C.K.) [pt

  9. Behaviour of the Sm-Nd and Rb-Sr systems of the mafic-ultramafic layered sequence from Ribeirao dos Motas (Archaean), meridional craton Sao Francisco: evidences of mantle source enrichment and isotopic fractionation; Comportamento dos sistemas Sm-Nd e Rb-Sr da sequencia acamadada mafico-ultramafico Ribeirao dos Motas (Arqueano), craton Sao Francisco Meridional: evidencias de enriquecimento mantelico e fracionamento isotopico

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, Mauricio Antonio; Carvalho Junior, Irneu Mendes de; Oliveira, Arildo Henrique de [Ouro Preto Univ., (UFOP), MG (Brazil). Dept. de Geologia]. E-mail: mauricio@degeo.ufop.br; Teixeira, Wilson [Sao Paulo Univ., SP (Brazil). Inst. de Geociencias. Dept. de Mineralogia e Geotectonica; Pimentel, Marcio Martins [Brasilia Univ., DF (Brazil). Inst. de Geociencias. Lab. de Geocronologia

    2004-10-15

    The Ribeirao dos Motas layered sequence (SARM) crops out in the southern part of the Sao Francisco Craton, Brazil. This sequence comprises phaneritic meta ultramafic and metamafic rocks, which, although slightly deformed and metamorphosed, retain primary igneous layers. Porphyritic rocks with idiomorphic pyroxene crystals and heteradcumulate and adcumulate textures are also present. Eighteen isotopic analyses were performed in the SARM, comprising rocks with primary (relict) textures, as well as rocks in amphibolite facies and retro-metamorphosed to green-schist facies. Seven samples yield a Sm/Nd isochron age of 2.79 +- 0.30 Ga (MSWD=1.2 e epsilon {sub Ndt}=+0.48), constraining the accretion time of the SARM rocks. The positive epsilon {sub Ndt} value coupled with the Rb/Sr evidence is consistent with mantle source relatively enriched in Nd and Sr isotopes. Nevertheless, some SARM samples display isotopic fractionation and disturbance, which can be ascribed to the following processes or their combinations: a) mobilization of the incompatible elements due to regional high grade metamorphism; b) isotopic changes during upper amphibolite facies overprint; c) isotopic resetting by low-grade fluids associated to the Claudio Shear zone, which is located nearby the SARM. (author)

  10. Rb-Sr isochrone dating of granitoids from Tribec Mts

    International Nuclear Information System (INIS)

    Bagdasaryan, G.P.; Gukasyan, R.Kh.; Cambel, B.; Broska, I.

    1990-01-01

    The results of Rb-Sr isochrone dating of granitoids from the Tribec-Zobor crystalline complex region are presented. Whole-rock Rb-Sr isochrone indicates an age of 352±5 m.y., the initial ratio being ( 87 Sr/ 86 Sr) 0 =0.70582±0.00008, which approaches the hitherto published initial ratios from the Tatric-Veporide part of the crystalline complex. This indicates a common source of granitoid rocks over the entire region studied. (author). 2 figs., 1 tab., 15 refs

  11. Rb-Sr dating of sphalerites from Mississippi Valley-type (MVT) ore deposits

    Energy Technology Data Exchange (ETDEWEB)

    Nakai, S.; Halliday, A.N.; Kesler, S.E.; Jones, H.D. (Univ. of Michigan, Ann Arbor (United States)); Kyle, J.R. (Univ. of Texas, Austin (United States)); Lane, T.E. (Memorial Univ. of Newfoundland, St. John' s (Canada))

    1993-01-01

    Mississippi Valley-type (MVT) ore deposits are epigenetic carbonate-hosted Pb-Zn deposits that contain galena, sphalerite, fluorite, barite, dolomite, calcite, and quartz. Although they are thought to form from basinal brines, their exact origins are still unclear, partly because of the scarcity of reliable geochronological data. Rb-Sr dating of sphalerites has recently been shown to be a promising technique for the direct dating of ore minerals in MVT deposits. This paper reports the results of a reconnaissance study of sphalerites, their fluid inclusions, and associated minerals from MVT deposits of North America. Sphalerites from Immel mine, Mascot-Jefferson City district, east Tennessee, define a Rb-Sr age of 347 [plus minus] 20 Ma consistent with a Rb-Sr age of 377 [plus minus] 29 Ma for sphalerites from Coy mine in the same district, but inconsistent with models that ascribe their genesis to the effects of the late Paleozoic Alleghenian orogeny. Rb-Sr isotopic analyses of K-feldspar from Immel mine preclude the possibility that the Rb-Sr data reflect feldspar inclusions. Sphalerites from the main ore zone of Daniel's Harbour mine, Newfoundland, do not form a linear isochron and open behavior of the Rb-Sr system is suspected. Sphalerites from the Pine Point district, Northwest Territories, Canada, define a Rb-Sr age of 361 [plus minus] 13 Ma, indicating that the mineralization took place shortly after the deposition of the middle Devonian host carbonate rocks. These results are not compatible with mineralization models based on regional fluid migration related to early Tertiary Cordilleran deformation. Sphalerites from northern Arkansas have very low Rb and Sr concentrations (less than 0.1 ppm). The Rb-Sr data do not form isochrons and the sphalerites have higher [sup 87]Sr/[sup 86]Sr ratios than expected, given their Rb/Sr ratios and reasonable constraints on their ages. 58 refs., 7 figs., 2 tabs.

  12. The Rb-Sr system

    International Nuclear Information System (INIS)

    Graham, I.J.

    1983-11-01

    This manual is intended to serve as a guide to the chemical procedures involved in Rb-Sr isotopic analysis as conducted at the Institute of Nuclear Sciences. Included are notes on the experimental developments made over the last 2.5 years, especially those involving rock dissolution and cation exchange chromatography

  13. Rb-Sr mantle isochrons from oceanic regions

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, C; Hart, S R; Hofmann, A; James, D E [Carnegie Institution of Washington, D.C. (USA). Dept. of Terrestrial Magnetism

    1976-09-01

    Existing data for /sup 87/Sr//sup 86/Sr and Rb/Sr ratios of basalts from oceanic islands and mid-ocean spreading ridges show significant positive correlations on a Rb-Sr isochron diagram (when data are averaged by island group). Furthermore, tholeiites and alkali basalts occupy distinct non-overlapping fields on this plot. The tholeiite correlation is interpreted as a mantle isochron, and the agreement of this age (1.6+-0.2 b.y.) with that reported for Pb-Pb isochrons from oceanic basalts lends strong support to the use of such isochrons for tracing mantle evolution. Oceanic basalts are apparently sampling a mantle in which chemical heterogeneities have persisted for at least 1.5-2.0 b.y. The data support a kinematic model for the mantle in which a relatively uniform and non-radiogenic asthenosphere is penetrated by, and mixed with, blobs or plumes derived from an isolated (1.5-2 b.y.) and chemically heterogeneous mesosphere.

  14. U/Pb (SHRIMP), {sup 207}Pb/{sup 206}Pb, Rb/Sr, Sm/Nd e K/Ar geochronology of granite-greenstone terrains of Gaviao Block: implications for the Proterozoic and Archean evolution of Sao Francisco Craton, Brazil; Geocronologia U/Pb (SHRIMP), {sup 207}Pb/{sup 206}Pb, Rb/Sr, Sm/Nd e K/Ar dos terrenos granito-greenstone do Bloco do Gaviao: implicacoes para a evolucao arqueana e proterozoica do craton do Sao Francisco, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Leal, Luiz Rogerio Bastos

    1998-07-01

    The Gaviao Block (GB) in the northern portion of the Sao Francisco Craton-Northeast of Brazil, constitutes one of the oldest Archean fragments of the South American Platform Archean crust. GB underwent several events of juvenile accretion and reworking of continental crust along its evolutionary history, notably between the Archean and the Paleoproterozoic. {sup 207}Pb/{sup 206}Pb isotopic analyses were carried out in two zircons populations from strongly migmatized TTG terranes found in the proximity of Brumado: the first population (7 crystals) is taken as representative of the crystallization period of the TTG terranes at 3300 {+-} 45 Ma; the second (2 crystals) represents the age of the first even of metamorphism/migmatization at 2910 {+-} 10 Ma. {sup 207} Pb/{sup 206} Pb analyses in zircons from an outcrop of non-migmatized TTG in the area yielded a 3202 {+-} 15 Ma age (4 crystals), interpreted to be the crystallization period of the gneiss protolith. Sm/Nd analyses on the TTG rocks of the Brumado region yielded T{sub DM} model ages varying between 3.26 and 3.36 Ga and {epsilon}{sub Nd}{sup (t)} between -3.5 and +0.7. These data suggest the occurrence of juvenile accretions to the continental crust during the Archean, with differential involvement of crustal materials. The geochemical data of rare earth elements corresponding to the TTG terranes revealed moderate LRRE contents (La{sub N}=83,5), low HREE contents (La{sub N}=2,5) and a fairly fractionated pattern (La/Yb){sub N}=34, besides lack of negative Eu anomaly, showing that these rocks have similar compositions to those TTG terranes of cratonic continents, as well as some Archean rocks from CSF (e.g. Sete Voltas, Boa Vista). Finally, the youngest ages present in GB rocks (ca. 1.2-0.45 Ga) represent the role played by tectono thermal events, which produced partial or total rejuvenation of the Rb/Sr and K/Ar isotopic systems during the Espinhaco and Brasiliano cycles. In particular, K/Ar ages illustrate the

  15. Rb-Sr dating in orthogneisses and the age of Serido group, Brazil

    International Nuclear Information System (INIS)

    Macedo, M.H.F.; Sa, E.F.J. de; Sa, J.M.

    1984-01-01

    The conclusions of the geochronologic study, by Rb-Sr method, of orthogneisses from Serido Group, Northeast of Brazil, are presented. Metamorphic and granitic rocks were analysed by X-ray fluorescence, to determine the Rb and Sr quantity. (M.C.K.) [pt

  16. Derivation of Apollo 14 High-Al Basalts at Discrete Times: Rb-Sr Isotopic Constraints

    Science.gov (United States)

    Hui. Hejiu; Neal, Clive, R.; Shih, Chi-Yu; Nyquist, Laurence E.

    2012-01-01

    Pristine Apollo 14 (A-14) high-Al basalts represent the oldest volcanic deposits returned from the Moon [1,2] and are relatively enriched in Al2O3 (>11 wt%) compared to other mare basalts (7-11 wt%). Literature Rb-Sr isotopic data suggest there are at least three different eruption episodes for the A-14 high-Al basalts spanning the age range approx.4.3 Ga to approx.3.95 Ga [1,3]. Therefore, the high-Al basalts may record lunar mantle evolution between the formation of lunar crust (approx.4.4 Ga) and the main basin-filling mare volcanism (groups [5,6], and then regrouped into three with a possible fourth comprising 14072 based on the whole-rock incompatible trace element (ITE) ratios and Rb-Sr radiometric ages [7]. However, Rb-Sr ages of these basalts from different laboratories may not be consistent with each other because of the use of different 87Rb decay constants [8] and different isochron derivation methods over the last four decades. This study involved a literature search for Rb-Sr isotopic data previously reported for the high-Al basalts. With the re-calculated Rb-Sr radiometric ages, eruption episodes of A-14 high-Al basalts were determined, and their petrogenesis was investigated in light of the "new" Rb-Sr isotopic data and published trace element abundances of these basalts.

  17. Rb/Sr establishes an age of 61 to 67 Ma for Colombian emeralds

    International Nuclear Information System (INIS)

    Ordonez, F Romero; Kawashita, Koji; Schultz-Guttler, R

    2001-01-01

    The age of emeralds is related to the environment within which they form and can be dated by geochronological methods of which the rubidium-strontium (Rb-Sr) method (Faure, 1986) is the best to date the emeralds and its host rocks (Vidal et al., 1992). Isotopic studies done by Vidal et al. (1992) established two different geochronological environments for dating emeralds depending on their ages: emeralds from Precambrian rocks in Brazil, Madagascar and Zambia with high radiogenic strontium enrichment due to the older ages and high Rb contents and emeralds hosted by younger rocks in Colombia, Paquistan and Afganistan generally, with low 87 Rb/ 86 Sr range and low radiogenic Sr enrichment, and low content of Rb (au)

  18. K-Ca and Rb-Sr Dating of Lunar Granite 14321 Revisited

    Science.gov (United States)

    Simon, Justin I.; Shih, C.-Y.; Nyquist, L. E.

    2011-01-01

    K-Ca and Rb-Sr age determinations were made for a bulk feldspar-rich portion of an Apollo rock fragment of the pristine lunar granite clast (14321,1062), an acid-leached split of the sample, and the leachate. K-Ca and Rb-Sr data were also obtained for a whole rock sample of Apollo ferroan anorthosite (FAN, 15415). The recent detection [1] of widespread intermediate composition plagioclase indicates that the generation of a diversity of evolved lunar magmas maybe more common and therefore more important to our understanding of crust formation than previously believed. Our new data strengthen the K-Ca and Rb-Sr internal isochrons of the well-studied Apollo sample 14321 [2], which along with a renewed effort to study evolved lunar magmas will provide an improved understanding of the petrogenetic history of evolved rocks on the Moon.

  19. Rb/Sr dating of rock samples from Antarctica

    International Nuclear Information System (INIS)

    Ahmed, A.; Awan, M.A.; Mehjabeen, A.; Jabeen, N.; Majid, C.A.

    1996-01-01

    Soon after the discovery of radioactivity in 1896 by Becquerel, the phenomenon was applied to geochronology. From 1902 onwards, rapid advances were made in this field of science. Using radiometric techniques of Rb/Sr the whole rock granitic pegmatite samples from two localities in the North Eastern Antarctica have been dated. The rock samples have yielded Rb/Sr ages around 200 nd 173 million year. The ages around 200 million year have been correlated to the orogenic/epeirogenic activities associated with the breaking up of the Pangaea which led to the dispersion of the continents to form Gondwanaland and Laurasia which subsequently gave rise to the present day configuration of the globe. The younger age of 173 million year corresponds to Jurassic dole rites from Western queens Maud Land and other areas of Antarctica. (author)

  20. The Rb-Sr geochronology of the Colossus kimberlite pipe, Zimbabwe

    International Nuclear Information System (INIS)

    Allsopp, H.L.

    1985-01-01

    The Colossus kimberlite is one of several such occurrences situated in central Zimbabwe. A relationship with alluvial diamond deposits in the same area has been suggested, and on this basis a pre-Permian age has been inferred. The general geology and petrography of the Colossus kimberlite pipe are described. Rb-Sr age measurements on somewhat weathered kimberlite micas are reported, and the best estimate for the age of the kimberlite is reported as 502+-47 Ma. A model Rb-Sr age of 2 630 Ma for the Formona granite, which forms the country rock to the kimberlite, is also reported

  1. The geotectonic evolution of southern part of Sao Francisco Craton, based in geochronologic interpretation

    International Nuclear Information System (INIS)

    Teixeira, W.

    1985-01-01

    Interpretation of available radiometric data from poly metamorphic terranes of southern part of the Sao Francisco Craton demonstrates the importance of geochronology as a tool in the study of ancient crustal evolution. In addition, radiometric study of basic intrusive magmatism helps define the most important epochs of crustal rifting during the Proterozoic. The definition of the southern border of the cratonic area based on distinctive age patterns of the geochronological provinces is also discussed. Finally, the geochronologic evolution of the Bambui platform cover is presented. Approximately 250 radiometric age determinations (Rb-Sr, K-Ar and Pb-Pb methods) were interpreted principally through the use of iso chronic diagrams. The geologic history tectonomagnetic events identified in this study is compared to the crustal evolution of similar segments of the Sao Francisco Craton and elsewhere. (author)

  2. Rb-Sr geochronology and geochemical characteristics of mafic dikes in the Nova Lacerda and Conquista D'Oeste region, Mato Grosso, SW Amazonian Craton; Geocronologia Rb-Sr e caracteristicas geoquimicas dos diques maficos da regiao de Nova Lacerda e Conquista D'Oeste (MT), porcao sudoeste do Craton Amazonico

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Paulo Cesar Correa da; Matos, Joao Batista de [Universidade Federal de Mato Grosso (UFMT), Cuiaba, MT (Brazil). Dept. de Recursos Minerais; Grupo de Pesquisas em Evolucao Crustal e Metalogenia Guapore, Cuiaba, MT (Brazil)], e-mail: pccorrea@ufmt.br, e-mail: jmatos@cpd.ufmt.br; Girardi, Vicente Antonio Vitorio [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Dept. de Mineralogia e Geotectonica], e-mail: girardi@usp.br; Ruiz, Amarildo Salina [Universidade Federal de Mato Grosso (UFMT), Cuiaba, MT (Brazil). Dept. de Geologia Geral; Grupo de Pesquisas em Evolucao Crustal e Metalogenia Guapore, Cuiaba, MT (Brazil)], e-mail: asruiz@rc.unesp.br

    2009-07-01

    In the Nova Lacerda and Conquista D'Oeste regions, Mato Grosso State, SW part of the Amazonian Craton, mafic dikes trending NNW intrude the Nova Lacerda Granite (1462{+-}12 Ma), within the Jauru Domain, in the Rondonia-San Ignacio Province (1.55 - 1.3 Ga). The mafic swarm comprises diabases, metadiabases and amphibolites. Metadiabases originated from uralitization of diabases. These rocks have tholeiitic affinity and predominant basaltic composition. Some samples are andesi-basalts. The ages of diabases and metabasites are 1380 {+-} 32 Ma and 1330 {+-} 120 Ma respectively. Geochemical data indicate that the compositional variation of diabases and metadiadases is due to fractional crystallization of evolved tholeiitic magmas. The origin of the basaltic magmas is related to a heterogeneous mantle source. (author)

  3. Evidence of three-body correlation functions in Rb+ and Sr2+ acetonitrile solutions

    Science.gov (United States)

    D'Angelo, P.; Pavel, N. V.

    1999-09-01

    The local structure of Sr2+ and Rb+ ions in acetonitrile has been investigated by x-ray absorption spectroscopy (XAS) and molecular dynamics simulations. The extended x-ray absorption fine structure above the Sr and Rb K edges has been interpreted in the framework of multiple scattering (MS) formalism and, for the first time, clear evidence of MS contributions has been found in noncomplexing ion solutions. Molecular dynamics has been used to generate the partial pair and triangular distribution functions from which model χ(k) signals have been constructed. The Sr2+ and Rb+ acetonitrile pair distribution functions show very sharp and well-defined first peaks indicating the presence of a well organized first solvation shell. Most of the linear acetonitrile molecules have been found to be distributed like hedgehog spines around the Sr2+ and Rb+ ions. The presence of three-body correlations has been singled out by the existence of well-defined peaks in the triangular configurations. Excellent agreement has been found between the theoretical and experimental data enforcing the reliability of the interatomic potentials used in the simulations. These results demonstrate the ability of the XAS technique in probing the higher-order correlation functions in solution.

  4. Rb-Sr geochronology of some Miocene West Australian lamproites

    International Nuclear Information System (INIS)

    Allsopp, H.L.; Scott Smith, B.H.; Danchin, R.V.

    1985-01-01

    Rb-Sr ages are presented for four lamproite intrusions (Mount North, Old Leopold Hill, Mount Rose and Seltrust Pipe 2) located in the west Kimberley region of West Australia. The data are in agreement with the early Miocene ages previously obtained for the lamproites of this area. The lamproites are characterized by high initial-Sr ratios, indicative of derivation from an enriched source. Localized and regional mantle heterogeneity is indicated by new and existing data

  5. Application of Sm/Eu/, Rb/Sr, Ce/Yb and F-Rb ratios to discriminate between Tin mineralized and non-mineralized S-type granites

    International Nuclear Information System (INIS)

    Karimpour, M.H.

    1998-01-01

    Mash had granites and Gran diorites are divided into three groups bas sed on their ages and composition: (1) Deh Now-Vakilabad-Kuhsangi Granodiorites and Quartz monzodiorites, (2) Sang bast Granite and (3) Khalaj- Gheshlagh Biotite-muscovite Granite. All these intrusive s belong to S-type granite, The oldest are in the range of intermediate and the youngest are acidic in composition. Intrusive rocks in the area of Deh now to Kuhsangi show trend of differentiation. Major, trace and rare earth elements within the source rocks of porphyry Sn, Mo, and Cu deposits were compared and very distinct differences were noticed. Differentiation index, Rb/Sr, Ce/Yb, and (Sr 87 /Sr 86 ) ratios can be used to identify the source rocks for porphyry Sn, Mo, or Cu. Major, as well as trace and rare earth elements of Mash had Granites and Granodiorites were compared with tin mineralized granites of the world. As a result, four diagrams were presented to be utilized in order to discriminate between Sn mineralized and non-mineralized granites. Such as Rb to the ratio of Sm/Eu, F to Rb and the three angle of F, Rb, Sr + Ba

  6. Evaluation and application of alumina-based Rb-82 generators charged with high levels of Sr-82/85

    International Nuclear Information System (INIS)

    Yano, Y.; Budinger, T.F.; Chiang, G.; O'Brien, H.A.; Grant, P.M.

    1979-01-01

    Generator-produced Rb-82, a 75-sec positron emitter with potential for myocardial blood-flow imaging, was studied with various ion-exchange columns to evaluate the characteristics of alumina as an adsorber for the 25-day Sr-82 parent. Test columns of alumina, Bio Rex 70, and Chelex 100 were loaded with multimillicurie amounts of no-carrier-added Sr-82/Sr-85 (Sr-85 is a production contaminant). The breakthrough of Sr-82/Sr-85, and the yield of Rb-82, were determined for long-term elutions from each column with up to 4 liter of 2% NaCl solution at pH 8 to 9. The breakthrough of Sr-82/85 was 10 -6 to 10 -5 from alumina and 10 -6 to 10 -4 from Chelex 100 and Bio Rex 70. The effects of eluent flow rate and concentration, and of alumina volume, on the breakthrough and yield were also studied. An improved and automated Rb-82 generator was used for myocardial and brain blood-flow studies in experimental animals and in man; it was equipped with solenoid flow-control valves and five in. of lead shielding for the alumina columns, which were charged with 25 to 50 mCi Sr-82 (100 to 150 mCi Sr-85). The Rb-82 generator with alumina column provided up to 20 to 40 mCi of Rb-82 as often as every 5 to 10 min with -5 breakthrough of Sr-82/85 over the 2- to 3-mo, useful life of the generator

  7. Rb-Sr isochronous age of Vepor pluton granitoids

    International Nuclear Information System (INIS)

    Bagdasaryan, G.P.; Gykasyan, R.Kh.; Cambel, B.

    1986-01-01

    The result are presented of geochronological investigations of the Vepor pluton granitoids by the Rb-Sr isochronous method. The results prove the Variscan age of granodiorite magmatism of the Sihla type (387±27 m.y.) and the Early Variscan age of leucocratic granitoids of the Vepor and the Ipel types (284±22 m.y.). Since the initial ratio of 87 Sr/ 86 Sr in granitoids of the Sihla type is 0.7054 and of the Vepor type 0.7060, it can be assumed that during the formation of the granitoids of veporides there was an increased supply of matter from the main source affecting genesis of granitoids. The results prove a polyphase character of the Variscan granitoids of Veporicum. (author)

  8. Apollo 17 'melt sheet': chemistry, age and Rb/Sr systematics

    Energy Technology Data Exchange (ETDEWEB)

    Winzer, S R [Martin Marietta Labs., Baltimore, Md. (USA); Nava, D F; Schuhmann, S; Philpotts, J A [National Aeronautics and Space Administration, Greenbelt, Md. (USA). Goddard Space Flight Center; Schuhmann, P J; Lum, R K.L.; Lindstrom, M M; Lindstrom, D J [Maryland Univ., College Park (USA)

    1977-01-01

    Major, minor and trace element compositions, age data and Rb/Sr systematics of Apollo 17 boulders have been compiled, and additional analyses performed on a norite breccia clast (77215) included in the Apollo 17, Station 7 boulder. The Apollo 17 boulders are found to be identical or nearly so in major, minor and trace element composition, suggesting that they all originated as an impact melt analogous to melt sheets found in larger terrestrial craters. The matrix dates (/sup 40/Ar//sup 39/Ar) and Rb/Sr systematics available suggest that this impact melt formed by a single impact about 4 b.y. ago. This impact excavated, shocked, brecciated and melted norites, norite cumulates and possibly anorthositic gabbros and dunites about 4.4 b.y. old. The impact was likely a major one, possibly the Serenitatis basin-forming event.

  9. Investigation of the weathering effect on Rb-Sr systematics and trace element abundances in Antarctic and non-Antarctic meteorites

    International Nuclear Information System (INIS)

    Nishikawa, Yoshiyuki; Nakamura, Noboru; Misawa, Keiji; Okano, Osamu; Yamamoto, Koshi; Kagami, Hiroo.

    1990-01-01

    In order to examine weathering effects on chondritic meteorites in Antarctic and non-Antarctic environments, the Rb-Sr isotopic ratios and abundances of REE, Ba, Sr, Rb, and K were determined for 8H-group chondrites (Yamato-790986 [H3], Yamato-74492 [H3], Grady [H3], Brownfield [H3], Clovis (No.1) [H3], Yamato-74155 [H4], Allegan [H5] [one whole-rock and two chondrules], and Yamato-74371 [H5]), and partly for the Etter (L5) chondrite. The Allegan whole-rock shows a flat REE pattern with a large negative Eu anomaly and Sr depletion. Analyses of Rb-Sr systematics of one whole-rock and two chondrules show somewhat younger age 4.38±0.12 b.y. It is suggested that REE and Rb-Sr were redistributed during the early thermal metamorphism. Except for Allegan, most other H-chondrites (finds) show the perturbation of the Rb-Sr systematics, indicating recent loss of Rb. It was found that the weathering degree is related with the Rb-Sr disturbance in Antarctic H-chondrite. In spite of different degrees of weathering, all the Antarctic H-chondrites studied (including heavily weathered ones) show flat REE patterns normal as H-chondrite with occasional occurrence of minor Eu anomalies, indicating the tough resistance of REE in H-chondrites to the Antarctic weathering. On the other hand, non-Antarctic finds (particularly the weathered chondrites) indicate light-REE enriched patterns with a large negative Ce anomaly and extreme enrichment of Ba, suggestive of terrestrial contaminations. (author)

  10. Geochronological studies by Rb/Sr method in rocks of the Jundiai block and surroundings. [Ampario group

    Energy Technology Data Exchange (ETDEWEB)

    Wernick, E [Faculdade de Filosofia Ciencias e Letras de Rio Claro; Oliveira, M A.F. de; Kawashita, K; Cordani, U G [Sao Paulo Univ. (Brazil). Inst. de Geociencias; Delhal, J [Musee Royal de l' Afrique Centrale, Belgica

    1976-01-01

    Field and petrological data, as well as radiometric results performed in granulitic, gneissic, migmatitic, and granitic rocks from the 'Jundiai tectonic block' (States of Sao Paulo and Minas Gerais), show for that region the existence of two superposed orogeneses. To the older, of transamazonian age whole rock Rb-Sr isochron 2,010 m.y. Rb/sup 87//Sr/sup 86/ initial = 0.702), belongs the Amparo Group, composed of gneisses, migmatites, and granulites, with intercalation of quartzites, schists and calc-silicate rocks. To the younger, of brazilian age whole rock Rb-Sr isochron 690 m.y. (Sr/sup 87//Sr/sup 86/ initial = 0.702), are related the feldspathization and migmatization of the Amparo Group, as well as the intrusion of granitic bodies. Possibly, also the metasediments around Jacarei belong to the brazilian cycle. This pattern of geologic evolution is similar to that observed for the Serra dos Orgaos region (States of Rio de Janeiro and Minas Gerais).

  11. Results of Rb-Sr dating of metamorphic rocks of crystalline complexes of Male Karpaty Mts

    International Nuclear Information System (INIS)

    Bagdasaryan, G.P.; Gukasyan, P.Kh.; Cambel, B.; Veselsky, J.

    1983-01-01

    The paper follows up on a recently published paper on Rb-Sr isochrone dating of granitoid rocks of the Male Karpaty Mts. Data are given on comparative statistical analysis of isochrones obtained for the Bratislava and Modra massifs (isochrone of the latter is complemented with the analyses of two new samples) and the results of age determination of metasedimentary rocks of the Pezinok-Pernek zone and the Bratislava area by the Rb-Sr isochrone. Regression analysis shows that there is no statistically significant difference between the age of the Bratislava massif (347+-4 m.y.) and the Modra massif (326+-22 m.y.) and between their initial ratios 87 Sr/ 86 Sr (i.e., they are synchronous, having the same magma source) which makes it possible to calculate uniform value for age. Whole-rock samples of metamorphic and crystalline schists (gneisses) of the Male Karpaty Mts. also determine the isochrone corresponding to the age 387+-38 m.y. (2σ) and initial ratio ( 87 Sr/ 86 Sr)=0.7100+-0.00O8 (2σ). Rb-Sr isotope analyses of several pairs of biotite-crystalline schist (from which biotite was separated) point out that redistribution of Sr isotopes among the mineral phases of rocks takes place during the periplutonic metamorphism, while the whole-rock samples remain chemically closed systems. (author)

  12. Rb-Sr isochronous dating of granitoids of Dumbier zone of Low Tatras (Western Carpathians)

    International Nuclear Information System (INIS)

    Bagdasaryan, G.P.; Gukasyan, R.Kh.; Cambel, B.; Vesel'skij, J.

    1985-01-01

    The results are discussed of isotopic-geochronological research and age determination of characteristic samples of granitoid rocks, obtained by the Rb/Sr isochronous method. The samples were biotite granodiorites and granites taken from various parts of the Dumbier massif and small granite bodies of the Kralicka type. Rb/Sr isochrones of the rock samples show identical age values: 362+-21 m.y. for the Dumbier massif and 365+-17 m.y. correspnding to the Middle - Upper Devonian. Initial 87 Sr/ 86 Sr ratios equal to 0.7079 and 0.7157, respectively, allow to make a presumption that the rocks of the Dumbier massif may have been derived both from crustal and from mantle sources while granites of the Kralicka type are close to the rocks of the crustal origin

  13. Use of Sr and Pb isotopes in gneissic-migmatic rocks in Itacambira-Barrocao, MG, Brazil

    International Nuclear Information System (INIS)

    Siga Junior, O.; Cordani, U.G.; Basei, M.A.S.; Kawashita, K.

    1987-01-01

    This work tries to show the potential of the Rb-Sr, Pb-Pb and K-Ar methods applied to basic geological mapping. The different interpretative values of these methodologies contribute to the understanding of the tectonic processes developed in the southeastern border of the Sao Francisco Craton. The Rb-Sr and Pb-Pb isotopic data for the gneissic-migmatitic unit of this sector indicates their generation during the Archean (-2.7 Ga) and Early Proterozoic (-2.1 Ga.). The high (Sr 87 /Sr 86 ) and μ 1 values also suggest an origin through reworking of older crustal rocks. The K-Ar data (and one fission track age) allow the thermal history of this domain to be delineated and suggest a vertical tectonic in the Late Brazilian Cycle, putting side by side blocks formed in different depths. (M.V.M.)

  14. Geological, Geochemical 1 and Rb-Sr isotopic studies on tungsten 2 ...

    Indian Academy of Sciences (India)

    37

    Geological, Geochemical and Rb-Sr isotopic studies on tungsten. 1 mineralised ..... From the field relations it is demonstrated that SG (biotite-bearing granitic gneiss) and. 120 ..... cases Ba) and vice-versa for the low concentration. 291.

  15. The Apollo 17 'melt sheet': chemistry, age and Rb/Sr systematics

    International Nuclear Information System (INIS)

    Winzer, S.R.; Nava, D.F.; Schuhmann, S.; Philpotts, J.A.

    1977-01-01

    Major, minor and trace element compositions, age data and Rb/Sr systematics of Apollo 17 boulders have been compiled, and additional analyses performed on a norite breccia clast (77215) included in the Apollo 17, Station 7 boulder. The Apollo 17 boulders are found to be identical or nearly so in major, minor and trace element composition, suggesting that they all originated as an impact melt analogous to melt sheets found in larger terrestrial craters. The matrix dates ( 40 Ar/ 39 Ar) and Rb/Sr systematics available suggest that this impact melt formed by a single impact about 4 b.y. ago. This impact excavated, shocked, brecciated and melted norites, norite cumulates and possibly anorthositic gabbros and dunites about 4.4 b.y. old. The impact was likely a major one, possibly the Serenitatis basin-forming event. (Auth.)

  16. Rb-Sr age of a basic dyke, Schirmacher oasis, east Antarctica

    International Nuclear Information System (INIS)

    Dayal, A.M.; Hussain, S.M.

    1996-01-01

    In order to understand the crustal evolution in east Antartica, detailed geological, geochemical and isotopic studies of the various rocks in the area are necessary. This paper reports the Rb-Sr isotopic data on a gabbroic dyke in the Schirmacher oasis

  17. Ab initio study of the RbSr electronic structure: Potential energy curves, transition dipole moments, and permanent electric dipole moments

    Energy Technology Data Exchange (ETDEWEB)

    Pototschnig, Johann V., E-mail: johann.pototschnig@tugraz.at; Krois, Günter; Lackner, Florian; Ernst, Wolfgang E., E-mail: wolfgang.ernst@tugraz.at [Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz (Austria)

    2014-12-21

    Excited states and the ground state of the diatomic molecule RbSr were calculated by post Hartree-Fock molecular orbital theory up to 22 000 cm{sup −1}. We applied a multireference configuration interaction calculation based on multiconfigurational self-consistent field wave functions. Both methods made use of effective core potentials and core polarization potentials. Potential energy curves, transition dipole moments, and permanent electric dipole moments were determined for RbSr and could be compared with other recent calculations. We found a good agreement with experimental spectra, which have been obtained recently by helium nanodroplet isolation spectroscopy. For the lowest two asymptotes (Rb (5s {sup 2}S) + Sr (5s4d {sup 3}P°) and Rb (5p {sup 2}P°) + Sr (5s{sup 2} {sup 1}S)), which exhibit a significant spin-orbit coupling, we included relativistic effects by two approaches, one applying the Breit-Pauli Hamiltonian to the multireference configuration interaction wave functions, the other combining a spin-orbit Hamiltonian and multireference configuration interaction potential energy curves. Using the results for the relativistic potential energy curves that correspond to the Rb (5s {sup 2}S) + Sr (5s4d {sup 3}P°) asymptote, we have simulated dispersed fluorescence spectra as they were recently measured in our lab. The comparison with experimental data allows to benchmark both methods and demonstrate that spin-orbit coupling has to be included for the lowest states of RbSr.

  18. Ab initio study of the RbSr electronic structure: potential energy curves, transition dipole moments, and permanent electric dipole moments.

    Science.gov (United States)

    Pototschnig, Johann V; Krois, Günter; Lackner, Florian; Ernst, Wolfgang E

    2014-12-21

    Excited states and the ground state of the diatomic molecule RbSr were calculated by post Hartree-Fock molecular orbital theory up to 22 000 cm(-1). We applied a multireference configuration interaction calculation based on multiconfigurational self-consistent field wave functions. Both methods made use of effective core potentials and core polarization potentials. Potential energy curves, transition dipole moments, and permanent electric dipole moments were determined for RbSr and could be compared with other recent calculations. We found a good agreement with experimental spectra, which have been obtained recently by helium nanodroplet isolation spectroscopy. For the lowest two asymptotes (Rb (5s (2)S) + Sr (5s4d (3)P°) and Rb (5p (2)P°) + Sr (5s(2) (1)S)), which exhibit a significant spin-orbit coupling, we included relativistic effects by two approaches, one applying the Breit-Pauli Hamiltonian to the multireference configuration interaction wave functions, the other combining a spin-orbit Hamiltonian and multireference configuration interaction potential energy curves. Using the results for the relativistic potential energy curves that correspond to the Rb (5s (2)S) + Sr (5s4d (3)P°) asymptote, we have simulated dispersed fluorescence spectra as they were recently measured in our lab. The comparison with experimental data allows to benchmark both methods and demonstrate that spin-orbit coupling has to be included for the lowest states of RbSr.

  19. Rb-Sr ages and palaeomagnetic data for some Angolan alkaline intrusives

    International Nuclear Information System (INIS)

    Allsopp, H.L.; Hargraves, R.B.

    1985-01-01

    New Rb-Sr age measurements are reported for a number of intrusives from Angola. Data for the Njoio and Tchivira nepheline syenite bodies yield mineral isochrons indicating ages of 104,3+-0,8 Ma and 130,8+-1,4 Ma respectively. Palaeomagnetic studies on the same occurrences gave marginal and scattered results respectively. Micas from the Camafuca crater-facies kimberlite yielded and apparent age of 1 822+-151 Ma, a result that is far in excess of the Tertiary (or younger) age inferred for this pipe. Similarly conflicting data were obtained for the Nova Lisboa kimberlite. It is likely that older crustal micas incorporated in the kimberlite breccias are responsible for the anomalous ages reported on the kimberlites. Satisfactory palaeomagnetic data are reported for the Zenza and Bailundu occurrences, not dated by the Rb-Sr method. A convenient K-Ar age of 80+-0,8 Ma was obtainable for Zenza

  20. Western cratonic domains in Uruguay: geochronology

    International Nuclear Information System (INIS)

    Preciozzi, F.; Peel, E.; Muzio, E.; Ledesma, R.; Guerequiz, R.

    2001-01-01

    The western cratonic domains in Uruguay are divided into three major units: Piedra Alta Terrane, Valentines Block and Pavas Block. Piedra Alta Terrane lacks of evidence of Neoproterozoic orogenesis (deformation, metamorphism or magmatism). Sarandí del Yi - Arroyo Solís Grande shear zone, separates it from Valentines Block. Valentines Block is separated from Pavas Block by Cueva del Tigre shear zone. Magmatic rocks with different ages, compositions and emplacements occur all over the Piedra Alta Terrane distributed in three metamorphic belts (Arroyo Grande, San José and Montevideo) as well as in the Central Gneissic-Migmatitic Complex (Figure 1). Samples from the Gneissic-Migmatitic complex, late tectonic granitoids and basic rocks associated to the metamorphic belts were analyzed using Rb/Sr, U/Pb, K/Ar and Sm/Nd methodologies. The age ranges obtained for granitoids

  1. K, Rb and Sr abundances and Sr isotopic composition of the Tanzawa granitic and associated gabbroic rocks, Japan: low-potash island arc plutonic complex

    International Nuclear Information System (INIS)

    Ishizaka, K.; Yanagi, T.

    1977-01-01

    The granitic and associated gabbroic rocks of the Tanzawa plutonic complex of Miocene age occurring in the northern part of the Izu-Bonin arc are characterized by low abundances of K (229-6790 ppm) and Rb (0.414-12.1 ppm), low K 2 O/Na 2 O ratios (0.037-0.21), moderately high K/Rb ratios (541-630), low Rb/Sr ratios (0.00137-0.0579) and low initial 87 Sr/ 86 Sr ratios (0.70332-0.70372). This indicates that acid to intermediate plutonic rocks with these geochemical characteristics also occur in island arc environments besides mid-oceanic ridge environments. They represent, together with associated gabbroic rocks, a low-potash island arc plutonic complex and are expected to occur beneath young island arcs, although now unexposed. The Tanzawa plutonic complex may have been formed by differentiation of low-K calc-alkaline magma. (Auth.)

  2. Contrasting isotopic mantle sources for proterozoic lamproites and kimberlites from the Cuddapah basin and eastern Dharwar craton: implication for proterozoic mantle heterogeneity beneath southern India

    International Nuclear Information System (INIS)

    Chalapathi Rao, N.V.; Gibson, S.A.; Pyle, D.M.; Dickin, A.P.

    1998-01-01

    Kimberlites intruding the Precambrian basement towards the western margin of the Cuddapah basin near Anantapur (1090 Ma) and Mahbubnagar (1360 Ma) in Andhra Pradesh have initial 87 Sr/ 86 Sr between 0.70205 to 0.70734 and σNd between +0.5 to +4.68. Mesoproterozoic lamproites (1380 Ma) from the Cuddapah basin (Chelima and Zangamarajupalle) and its NE margin (Ramannapeta) have initial 87 Sr/ 86 Sr between 0.70520 and 0.7390 and εNd from -6.43 to -8.29. Combined Sr- and Nd- isotopic ratios suggest that lamproites were derived from enriched sources which have time-averaged higher Rb/Sr and lower Sm/Nd ratios than the Bulk Earth whereas kimberlites were derived from depleted source with lower Rb/Sr and higher Sm/Nd ratios. Calculated T DM model ages suggest that the lamproite source enrichment (∼2 Ga) preceded that of kimberlites (∼1.37 Ga). Our work demonstrates the existence of isotopically contrasting upper mantle sources for southern Indian kimberlites and lamproites and provides evidence for a lateral, isotopically heterogeneous mantle beneath the Cuddapah basin and eastern Dharwar craton. The significance of our results in the context of diamond exploration is also highlighted. (author)

  3. U/Pb (SHRIMP), 207Pb/206Pb, Rb/Sr, Sm/Nd e K/Ar geochronology of granite-greenstone terrains of Gaviao Block: implications for the Proterozoic and Archean evolution of Sao Francisco Craton, Brazil

    International Nuclear Information System (INIS)

    Leal, Luiz Rogerio Bastos

    1998-01-01

    The Gaviao Block (GB) in the northern portion of the Sao Francisco Craton-Northeast of Brazil, constitutes one of the oldest Archean fragments of the South American Platform Archean crust. GB underwent several events of juvenile accretion and reworking of continental crust along its evolutionary history, notably between the Archean and the Paleoproterozoic. 207 Pb/ 206 Pb isotopic analyses were carried out in two zircons populations from strongly migmatized TTG terranes found in the proximity of Brumado: the first population (7 crystals) is taken as representative of the crystallization period of the TTG terranes at 3300 ± 45 Ma; the second (2 crystals) represents the age of the first even of metamorphism/migmatization at 2910 ± 10 Ma. 207 Pb/ 206 Pb analyses in zircons from an outcrop of non-migmatized TTG in the area yielded a 3202 ± 15 Ma age (4 crystals), interpreted to be the crystallization period of the gneiss protolith. Sm/Nd analyses on the TTG rocks of the Brumado region yielded T DM model ages varying between 3.26 and 3.36 Ga and ε Nd (t) between -3.5 and +0.7. These data suggest the occurrence of juvenile accretions to the continental crust during the Archean, with differential involvement of crustal materials. The geochemical data of rare earth elements corresponding to the TTG terranes revealed moderate LRRE contents (La N =83,5), low HREE contents (La N =2,5) and a fairly fractionated pattern (La/Yb) N =34, besides lack of negative Eu anomaly, showing that these rocks have similar compositions to those TTG terranes of cratonic continents, as well as some Archean rocks from CSF (e.g. Sete Voltas, Boa Vista). Finally, the youngest ages present in GB rocks (ca. 1.2-0.45 Ga) represent the role played by tectono thermal events, which produced partial or total rejuvenation of the Rb/Sr and K/Ar isotopic systems during the Espinhaco and Brasiliano cycles. In particular, K/Ar ages illustrate the effect of younger regional cooling episodes related to the

  4. Fluid inclusion, geochemical, Rb-Sr and Sm-Nd isotope studies on ...

    Indian Academy of Sciences (India)

    10

    Degana granites is quiet high and ranges from 958 to 1907 ppm except B-24, Zr .... According to Pearson's hard soft acid base (HSAB) principle, tungsten which occurs ... could explain lower Sr abundances in the Balda and Degana granites, Rb ...... Oceanic ridge granites (ORG), within-plate granite (WPG), volcanic arc ...

  5. Trace-element and Sr, Nd, Pb, and O isotopic composition of Pliocene and Quaternary alkali basalts of the Patagonian Plateau lavas of southernmost South America

    Science.gov (United States)

    Stern, C.R.; Frey, F.A.; Futa, K.; Zartman, R.E.; Peng, Z.; Kurtis, Kyser T.

    1990-01-01

    The Pliocene and Quaternary Patagonian alkali basalts of southernmost South America can be divided into two groups. The "cratonic" basalts erupted in areas of Cenozoic plateau volcanism and continental sedimentation and show considerable variation in 87Sr/86Sr (0.70316 to 0.70512), 143Nd/144Nd (e{open}Nd) and 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios (18.26 to 19.38, 15.53 to 15.68, and 38.30 to 39.23, respectively). These isotopic values are within the range of oceanic island basalts, as are the Ba/La, Ba/Nb, La/Nb, K/Rb, and Cs/Rb ratios of the "cratonic" basalts. In contrast, the "transitional" basalts, erupted along the western edge of the outcrop belt of the Pliocene and Quaternary plateau lavas in areas that were the locus of earlier Cenozoic Andean orogenic arc colcanism, have a much more restricted range of isotopic composition which can be approximated by 87Sr/86Sr=0.7039??0.0004, e{open}Nd, 206Pb/204Pb=18.60??0.08, 207Pb/204Pb=15.60??0.01, and 208Pb/204Pb=38.50??0.10. These isotopic values are similar to those of Andean orogenic are basalts and, compared to the "cratonic" basalts, are displaced to higher 87Sr/86Sr at a given 143Nd/144Nd and to higher 207Pb/204Pb at a given 208Pb/204Pb. The "transitional" basalts also have Ba/La, Ba/Nb, La/Nb, and Cs/Rb ratios higher than the "cratonic" and oceanic island basalts, although not as high as Andean orogenic are basalts. In contrast to the radiogenic isotopes, ??18O values for both groups of the Patagonian alkali basalts are indistinguishable and are more restricted than the range reported for Andean orogenic are basalts. Whole rock ??18O values calculated from mineral separates for both groups range from 5.3 to 6.5, while measured whole rock ??18O values range from 5.1 to 7.8. The trace element and isotopic data suggest that decreasing degrees of partial melting in association with lessened significance of subducted slabderived components are fundamental factors in the west to east transition from arc

  6. Rb-Sr And Sm-Nd Ages, and Petrogenesis of Depleted Shergottite Northwest Africa 5990

    Science.gov (United States)

    Shih, C. Y.; Nyquist, L. E.; Reese, Y.; Irving, A. J.

    2011-01-01

    Northwest Africa (NWA) 5990 is a very fresh Martian meteorite recently found on Hamada du Draa, Morocco and was classified as an olivine-bearing diabasic igneous rock related to depleted shergottites [1]. The study of [1] also showed that NWA 5990 resembles QUE 94201 in chemical, textural and isotopic aspects, except QUE 94201 contains no olivine. The depleted shergottites are characterized by REE patterns that are highly depleted in LREE, older Sm-Nd ages of 327-575 Ma and highly LREE-depleted sources with Nd= +35+48 [2-7]. Age-dating these samples by Sm-Nd and Rb-Sr methods is very challenging because they have been strongly shocked and contain very low abundances of light rare earth elements (Sm and Nd), Rb and Sr. In addition, terrestrial contaminants which are commonly present in desert meteorites will compromise the equilibrium of isotopic systems. Since NWA 5990 is a very fresh meteorite, it probably has not been subject to significant desert weathering and thus is a good sample for isotopic studies. In this report, we present Rb-Sr and Sm-Nd isotopic results for NWA 5990, discuss the correlation of the determined ages with those of other depleted shergottites, especially QUE 94201, and discuss the petrogenesis of depleted shergottites.

  7. Rb-Sr geochronological study on Tatehira granodiorite, Oshima Peninsula, Southwest Hokkaido, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Iizumi, Shigeru; Kobayashi, Hideo; Toyoda, Minoru

    1984-10-01

    It has been known that Tatehira granodiorite, a pluton which occurs sporadically in the southwest region of Hokkaido, is related with Kanoite formation. The radiometric age of this granodiorite still remains unknown. The Tatehira granodiorite intrudes into late Paleozoic or early Mesozoic Matsumae group, and is overlain by Miocene Usubetsu formation unconformably. It occurs as several separated small plutons. The samples for Rb-Sr analysis were collected from one of the plutons in southern part. The determination of the isochron age of rock-minerals and the initial Sr isotopic ratio of Tatehira granodiorite were carried out. This granodiorite is able to be classified into two phases, namely melanocratic (WRM) and leucocratic (WRL) phases. The samples of WRM and WRL were powdered and subjected to X-ray analysis. It was found that the chemical compositions were similar except slight differences in FeO + Fe2O3, CaO and K2O. The Sr isotopic ratio was determined with a MAT 261 mass spectrometer, and the results were analyzed statistically. The Rb and Sr concentrations and the Sr isotopic ratio of WRM, WRL, and PRF (plagio-clase rich fraction) and BRF (biotite rich fraction) separated from the WRL were determined, and the age of 102.5 +- 0.3 Ma and the initial ratio of 0.70538 +- 0.00001 were obtained. The ratio of Tatehira granodiorite is comparable to that of Okushiri Island. Comparing with the data obtained from other region, the granodiorites of Tatehira and Okushiri Island should be related with the granitoids of Abukuma granite province.

  8. Potentiality if Rb-Sr method for dating the argillous sedimentary rocks

    International Nuclear Information System (INIS)

    Thomaz Filho, A.

    1976-01-01

    The potentiality of application Rb-Sr method in argillous sediments, using samples from paleozoic and mesozoic formation in brazilian sedimentaries basin was tested. Physical, chemistry and isotopic analysis of thirty eight samples were made in the laboratories of geochronology Research Center from the University of Sao Paulo. Four isochronic diagrams for the argillous sedimentary rocks were also proposed. (author)

  9. K-Ar and Rb-Sr dating results of the Malyshevsky leucogranite massif (eastern slope of the Middle Urals)

    International Nuclear Information System (INIS)

    Smirnov, V.N.; Ivanov, K.S.; Ronkin, Yu.L.; Levin, V.Ya.; Bushlyakov, I.N.; Lepikhina, O.P.; Popova, O.Yu.

    2005-01-01

    The age of leucogranites and minerals forming the Malyshevsky massif was identified by the methods of K-Ar- and Rb-Sr dating for refining the sequence of magmatic complexes formation on the eastern slope of the Middle Urals. The obtained isotope age values, i.e. 229-277 mln. years (K-Ar) and 277.1±1.1 mln. years (Rb-Sr), permit considering the age of 277 mln. years as the period of the leucogranites formation and of the associated molybdenum mineralization [ru

  10. The age of Male Karpaty Mts. granitoid rocks determined by Rb-Sr isochrone method

    International Nuclear Information System (INIS)

    Badgasaryan, G.P.; Gukasyan, R.Kh.; Veselsky, J.

    1982-01-01

    The results are presented of nuclear geochronological datings of Male Karpaty Mts. granitoids by Rb-Sr isochrone method. Using the method the age of Bratislava massif granitoids was established to be 347+-4 mil. y. at ( 87 Sr/ 86 Sr)=0.7076+-0.0013 and the age of Modra massif granitoids to be 324+-18 mil. y. at ( 87 Sr/ 86 Sr)=0.7075+-0.00032 (2σ). The relative agreement of age of both massifs as well as the agreement of the primary ratio ( 87 Sr/ 86 Sr) 0 not only testifies to their continuity in age but also in genesis. The same relations also confirm the genetic dependence of pegmatites and leucocratic granitoids on fundamental types of granitoids building up the Bratislava and Modra massifs. (author)

  11. Western cratonic domains in Uruguay, geochronology

    International Nuclear Information System (INIS)

    Preciozzi, F; Pell, E; Muzio, R; Ledesma, J.J; Guerequiz, R

    2001-01-01

    The western cratonic domains in Uruguay are divided into three major units: Piedra Alta Terrane, Valentines Block and Pavas Terrane. Piedra Alta Terrane lacks of evidence of Neo proterozoic oro geneses (deformation, metamorphism or magmatism). Sarandi del Yi - Arroyo Solis Grande shear zone, separates it from Valentines Block. Valentines Block is separated from Pavas Terrane by Cueva del Tigre shear zone. Magmatic rocks with different ages, compositions and emplacements occur all over the Piedra Alta Terrane distributed in three metamorphic belts (Arroyo Grande, San Jose and Montevideo) as well as in the Central Gneissic-Migmatitic Complex. Samples from the gneissic-migmatitic complex, late tectonic granitoids and basic rocks associated to the metamorphic belts were analyzed using Rb/Sr, U/Pb, K/Ar and Sm/Nd methodologies. The age ranges obtained for granitoids and gneissicmigmatitic samples using Rb/Sr whole rock (WR) systematics are 1.7 to 2.5 Ga, showing two intervals: 1.9 to 2.05 Ga (intrusion of late granites) and 2.1 to 2.2 Ga (deformation and metamorphism). K/Ar cooling ages present several ranges: 1.3 to 1.35 Ga (probable local heating of the crust), 1.7 to 1.8 Ga (microgabbro magmatism, data confirmed by the Ar/Ar method) and ages between 2.0 to 2.2 Ga. Rb/Sr (WR) data yielded an isochronic age of 2094 ± 28.3 Ma, Ro = 0.70174 ± 0.00009, MSWD 19.74, interpreted as the time of the metamorphic event recognized for all the Piedra Alta Terrane. TDM Sm/Nd model ages presented a range from 2065 Ma to 2450 Ma. U/Pb systematics yield ages in migmatitic and gneissic rocks from 2.16 Ga to 2.21 Ga, showing metamorphism and deformation phenomena. While the ages of granitoids associated to the San Jose Belt are between 2.06 Ga and 2.08 Ga (Isla Mala) to 2.1 Ga (Granito de Cufre). None of them show metamorphic phenomena. Valentines Block (Preciozzi et al., 1979) comprises granulitic gneisses, granitoids and mafic rocks of different compositions. The geologic complexity

  12. Rb-Sr and Sm-Nd chronology and genealogy of mare basalts from the Sea of Tranquility

    Science.gov (United States)

    Papanastassiou, D. A.; Depaolo, D. J.; Wasserburg, G. J.

    1977-01-01

    Rb-Sr and Sm-Nd ages of two Apollo 11 mare basalts, high-K basalt 10072 and low-K basalt 10062, are reported. Rb-Sr, Sm-Nd, and Ar-40-Ar-39 ages are in good agreement and indicate an extensive time interval for filling of the Sea of Tranquility, presumably by thin lava flows, in agreement with similar observations for the Ocean of Storms. Initial Sr and Nd isotopic compositions on Apollo 11 basalts reveal at least two parent sources producing basalts. The Sm-Nd isotopic data demonstrate that low-K and high-Ti basalts from Apollo 11 and 17 derived from distinct reservoirs, while low-Ti Apollo 15 mare basalt sources have Sm/Nd similar to the sources of Apollo 11 basalts. Groupings of mare basalt based on Ti content and on isotopic data do not coincide.

  13. Integrated elemental and Sr-Nd-Pb-Hf isotopic studies of Mesozoic mafic dykes from the eastern North China Craton: implications for the dramatic transformation of lithospheric mantle

    Science.gov (United States)

    Liu, Shen; Feng, Caixia; Santosh, M.; Feng, Guangying; Coulson, Ian M.; Xu, Mengjing; Guo, Zhuang; Guo, Xiaolei; Peng, Hao; Feng, Qiang

    2018-02-01

    Evolution of the lithospheric mantle beneath the North China Craton (NCC) from its Precambrian cratonic architecture until Paleozoic, and the transformation to an oceanic realm during Mesozoic, with implications on the destruction of cratonic root have attracted global attention. Here we present geochemical and isotopic data on a suite of newly identified Mesozoic mafic dyke swarms from the Longwangmiao, Weijiazhuang, Mengjiazhuang, Jiayou, Huangmi, and Xiahonghe areas (Qianhuai Block) along the eastern NCC with an attempt to gain further insights on the lithospheric evolution of the region. The Longwangmiao dykes are alkaline with LILE (Ba and K)- and LREE-enrichment ((La/Yb) N > 4.3) and EM1-like Sr-Nd-Pb-Hf isotopic signature ((87Sr/86Sr) i > 0.706; ε Nd (t) 16.6, (207Pb/204Pb) i > 15.4, (208Pb/204Pb) i > 36.8, ε Hf (t) 3.7), and display similar EM1-like isotopic features ((87Sr/86Sr) i > 0.706; ε Nd (t) 16.7, (207Pb/204Pb) i > 15.4, (208Pb/204Pb) i > 36.9, ε Hf (t) 2.4) and EM1-like isotopic features((87Sr/86Sr) i > 0.706; ε Nd (t) 16.7, (207Pb/204Pb) i > 15.4, (208Pb/204Pb) i > 36.9, ε Hf (t) 3.7) and EM1-like Sr-Nd-Pb-Hf isotopic features ((87Sr/86Sr) i > 0.706; ε Nd(t) 16.7, (207Pb/204Pb) i > 15.4, (208Pb/204Pb) i > 36.9, ε Hf (t) 9.3) and EM1-like isotopic composition ((87Sr/86Sr) i > 0.705; ε Nd (t) 16.9, (207Pb/204Pb) i > 15.5, (208Pb/204Pb) i > 36.9, ε Hf (t) 0.705; ε Nd (t) 16.9, (207Pb/204Pb) i > 15.5, (208Pb/204Pb) i > 36.9, ε Hf (t) < -8.6). Our data from the various mafic dyke suites suggest that the magmas were derived from EM1-like lithospheric mantle, corresponding to lithospheric mantle modified by the previously foundered lower crust beneath the eastern NCC. Our results suggest contrasting lithospheric evolution from Triassic (212 Ma) to Cretaceous (123 Ma) beneath the NCC. These mafic dykes mark an important phase of lithospheric thinning in the eastern North China Craton.

  14. Rb-Sr, Pb-Pb, U-Pb dating in the Bandja plutonic series of Western Cameroon. Donnees geochronologiques (Rb-Sr, Pb-Pb, U-Pb) sur le complexe plutonique de Bandja (Centre-Ouest Cameroun)

    Energy Technology Data Exchange (ETDEWEB)

    Tchankam, C N [Nancy-1 Univ., 54 (France); Vialette, Y [Clermont-Ferrand-2 Univ., 63 - Aubiere (France)

    1994-08-01

    The results of U-Pb zircon and Pb-Pb on minerals and whole rocks are reported on a charnockite syn-D1 from the Bandja series in the western Cameroon. Data are interpreted as representing a plutonic emplacement at 640 Ma. A syn- to post-tectonic pluton is dated at 557 [+-] 8 Ma (Rb-Sr whole rocks isochron). These results confirm the Pan-African age of the charnockitic intrusive body. Initial isotopic [sup 87]Sr/[sup 86]Sr ratios of charnockite (0.709) and granite (0.7089) show the importance of crustal imprint in the magma genesis. (authors).

  15. A Rb-Sr geochronological study on Tatehira granodiorite, Oshima Peninsula, Southwest Hokkaido, Japan

    International Nuclear Information System (INIS)

    Iizumi, Shigeru; Kobayashi, Hideo; Toyoda, Minoru.

    1984-01-01

    It has been known that Tatehira granodiorite, a pluton which occurs sporadically in the southwest region of Hokkaido, is related with Kanoite formation. The radiometric age of this granodiorite still remains unknown. The Tatehira granodiorite intrudes into late Paleozoic or early Mesozoic Matsumae group, and is overlain by Miocene Usubetsu formation unconformably. It occurs as several separated small plutons. The samples for Rb-Sr analysis were collected from one of the plutons in southern part. The determination of the isochron age of rock-minerals and the initial Sr isotopic ratio of Tatehira granodiorite were carried out. This granodiorite is able to be classified into two phases, namely melanocratic (WRM) and leucocratic (WRL) phases. The samples of WRM and WRL were powdered and subjected to X-ray analysis. It was found that the chemical compositions were similar except slight differences in FeO + Fe 2 O 3 , CaO and K 2 O. The Sr isotopic ratio was determined with a MAT 261 mass spectrometer, and the results were analyzed statistically. The Rb and Sr concentrations and the Sr isotopic ratio of WRM, WRL, and PRF (plagio-clase rich fraction) and BRF (biotite rich fraction) separated from the WRL were determined, and the age of 102.5 +- 0.3 Ma and the initial ratio of 0.70538 +- 0.00001 were obtained. The ratio of Tatehira granodiorite is comparable to that of Okushiri Island. Comparing with the data obtained from other region, the granodiorites of Tatehira and Okushiri Island should be related with the granitoids of Abukuma granite province. (Ishimitsu, A.)

  16. 87Rb-87Sr chronology of H chondrites: constraint and speculations on the early evolution of their parent body

    International Nuclear Information System (INIS)

    Minster, J.-F.; Allegre, C.J.

    1979-01-01

    A precise 87 Rb- 87 Sr whole-rock isochron for H chrondrites and an internal isochron for Tieschitz (H3) have been determined. The age and 87 Sr/ 86 Sr initial ratio of the whole rocks are 4.25 +- 0.05 b.y. and 0.69876 +- 0.00040 (lambda( 87 Rb) = 1.42 X 10 -11 yr -1 ). For Tieschitz, whereas handipicked separates plot on a well-defined line, heavy liquid separates scatter in the 87 Rb/ 86 Sr vs. 87 Sr/ 86 Sr diagram. Leaching experiments by heavy liquids indicate that they might have a sizeable effect on Tieschitz minerals. The age and 87 Sr/ 86 Sr initial ratio as determined by handpicked separates are 4.53 +- 0.06 b.y. and 0.69880 +- 0.00020, indistinguishable from the whole-rock isochron. These results are interpreted as 'primitive isochrons' dating the condensation of chondrites from the solar nebula. The best value of this event is given by joining both isochrons together at 4.518 +- 0.026 b.y. and 87 Sr/ 86 Sr = 0.69881 +- 0.00016. The near identity of this initial ratio with the one of Allende white inclusions argues in favor of a sharp isochronism of condensation from a 87 Sr/ 86 Sr homogeneous nebula. Data from Guarena and Richardton are interpreted as secondary internal isochrons, 100 m.y. after the condensation of the whole rocks. The data are then used to constrain a thermal evolution model of the H chondrite parent body. This body might have a 150-175 km radius, and might have been heated by 26 Al. An 26 Al/ 27 Al ratio of 4-6 X 10 -6 is enough for heating such a body. Further tests for this model are proposed. (Auth.)

  17. Derivation of Apollo 14 High-Al Basalts at Discrete Times: Rb-Sr Isotopic Constraints

    Science.gov (United States)

    Hui, H.; Neal, C. R.; Shih, C.-Y.; Nyquist, L. E.

    2012-03-01

    Four eruption episodes were identified for A-14 high-Al basalts. Rb-Sr isotopic data and ITE ratios show that their parental melt compositions of are correlated through mixing of evolved components with a relatively primitive magma ocean cumulate.

  18. Rb-Sr ages of Precambrian sediments from the Ovruch mountain range, northwestern Ukraine (U.S.S.R.)

    International Nuclear Information System (INIS)

    Gorokhov, I.M.; Varshavskaya, E.S.; Kutyavin, E.P.; Clauer, N.; Drannik, A.S.

    1981-01-01

    A mineralogical and Rb-Sr geochronological study of Precambrian sediments and metasediments from the Ovruch mountain range (northwestern Ukraine) shows two distinct events: a slight metamorphism of the Belokorovichi Formation 1575 +- 30 Ma ago which precedes the deposition of the Zbranki Formation at 1389 +- 71 Ma (lambda 87 Rb = 1.42 x 10 -11 y -1 ). (Auth.)

  19. Unusual Rb-Sr data on the age of two typical peralkaline granitoid plutons in West Transbeikalia

    International Nuclear Information System (INIS)

    Litvinovskij, B.A.; Posokhov, V.F.; Zanvilevich, A.N.

    1995-01-01

    Rb-Sr isotope study of two typical plutons in West Transbaikalia (Bryansk and Kharitonov) has been carried out. For alkaline and peralkaline suits of the Bryansk pluton the obtained data are 287 ± m.y., I Sx =0.7054 ± 3 and 285 ± 1 m.y., I Sr =0.7037 ± 3 respectively. Rb-Sr age of peralkaline syenites and granites from the Kharitonov pluton are in more or less consistency with those on the Malokunal pluton (233 ± 5 m.y.) and much less than the age of the Khorinsk pluton (253 ± 3 m.y.). Taking into account the K-Ar data on amphibole from the peralkaline granitoids it is concluded that probable age of these rocks span the interval 250-220 m.y. However results obtained from the Bryansk pluton suggest that within the Mongolia-Transbaikalia belt one more stage of peralkaline granitoid generation i.e. the Early Permian stage could be manifested as well. 20 refs.; 5 figs.; 3 tabs

  20. The Sr:Ba:Rb ratio and zircon typology in granitoid complexes of Sao Paulo, Parana and Minas Gerais states (Brazil)

    International Nuclear Information System (INIS)

    Wernick, E.; Galembeck, T.M.B.; Artur, A.C.; Rigo Junior, L.; Weber-Diefenbach, K.

    1990-01-01

    Chemical (Sr: Ba: Rb) and zircon typology data from the Nazare Paulista, Mairipora/Cantareira, Cunhaporanga, Tres Corregos, Morungaba, Socorro, Itu, Graciosa and Serra Carambei granitoid complexes from the states of Minas Gerais, Sao Paulo and Parana (SE/S Brazil) are presented and discussed. By the zircon typology method these complexes are reffered, respectively, to the 2nd crustal, 3rd crustal/low temperature C-A, low temperature C-A, medium temperature C-A, medium/high temperature C-A, K-SA/Alkaline and alkaline serie which are considered as generated under increasing temperature associated with a progressive major participation of mantellic material. All these series, with the exception of the medium to high temperature calc-alkaline complexes Socorro and Morungaba whose chemical data come from several laboratories, display different positions and behaviour in the Sr: Ba: Rb diagram which reinforce the use of the zircon typology method in the study of granitoids. From the 2nd crustal serie up to the medium temperature C-A serie the complexes show a regular shift in their chemical composition which became progressively richer in Sr and depleted in Rb. The highly differentiades hypersolvus Serra do Carambei granite is strongly enriched in Rb and impoverish in Ba with respect to the Itu and the Graciosa complex which itself is slighly more depleted in Sr than the Itu granite. (author)

  1. The Transhimalaya (Gangdese) plutonism in the Ladakh region: A U-Pb and Rb-Sr study

    International Nuclear Information System (INIS)

    Schaerer, U.; Hamet, J.; Allegre, C.J.

    1984-01-01

    The age and origin of the Transhimalaya (Gangdese) plutonic belt in the Ladakh area has been studied by high-resolution U-Pb analyses of accessory minerals (zircon and monazite/allanite) and Rb-Sr measurements on whole rock samples. The ages determined of 101+-2 m.y. for a granodiorite and of 60.7+-0.4 m.y. for a granite substantiate that the Transhimalaya plutonism was active at least in mid-Cretaceous (Albian) and earliest Tertiary (Palaeocene) times. A Rb-Sr isochron of 73.4+-2.4 m.y. might be fortuitous because the Rb-Sr systematics shows important heterogeneities on the whole rock scale. The inherited radiogenic lead in zircon demonstrates that anatexis of continental crust was involved in magma genesis. The thus recycled continental material was heterogeneous with respect to its primary ages and/or metamorphic history; the approximate minimum ages of the continental sources range from 350 to 590 m.y. The 101+-2 m.y. old Transhimalaya granodiorite, which intrudes a series of mainly basaltic island arc rocks (Dras Series) shows that this island arc was attached to the continental margin at that times. This is consistent with the hypothesis that the ''Ladakh Tethys'' closed through two subduction regimes: (1) an early Cretaceous subduction, which formed the Dras island arc, and (2) a late Cretaceous to Palaeocene subduction at the continental margin, which caused the emplacement of the Transhimalaya plutonic belt. (orig.)

  2. The use of Rb-Sr and K-Ar dating methods as a stratigraphic tool applied to sedimentary rocks and minerals

    International Nuclear Information System (INIS)

    Bonhomme, M.G.

    1982-01-01

    Rb-Sr and K-Ar methods can be used for direct numerical chronostratigraphy of sediments using the clay silicates they contain. The interpretation of the ages calculated depends on the satisfaction of the following requirements: (1) The series studied must include diagenetic clay sediments. Coarsely-detrital or slightly-metamorphic formations must be excluded. Studies in progress concerning decarbonatation may lead to the application of direct dating of sediments being extended to carbonate sediments. (2) Careful mineralogical study of the clay minerals must prove early diagenetic recrystallization or new formation. This part of the study must precede any isotopic work. (3) The isotopic study must involve the use of both Rb-Sr and K-Ar methods. The extreme sensibility of the K-Ar isotopic system to late diagenesis helps to choose between early or late diagenesis: a younger K-Ar age may generally be regarded as that of the late diagenesis, whereas the Rb-Sr age may be that of the early diagenesis. (4) The initial 87 Sr/ 86 Sr isotopic ratio is not always a reliable criterion, owing to the effects of the dilution of the radiogenic 87 Sr by the great amounts of primary Sr contained in carbonates. (5) The regularly-decreasing succession of isotopic ages must follow the stratigraphic succession. When this condition is satisfied, there is a high probability that the calculated ages are indeed those of the deposition dates. (Auth.)

  3. Rb-Sr geochronology of leucocratic granitoid rocks from the Spissko-Gemerske Rudohorie Mts. and Veporicum

    International Nuclear Information System (INIS)

    Cambel, B.; Veselsky, J.

    1989-01-01

    Information is given on new Rb-Sr data from leucocratic types of rocks occurring in the Gemericum and Veporicum. Basses on isochron geochronological data, mutual geochronological and geochemical relations are discussed. (author). 3 figs., 47 tabs., 14 refs

  4. Rb-Sr geochronology of the rocks of the Himalayas, Eastern Nepal, (1)

    International Nuclear Information System (INIS)

    Kai, Kunio

    1981-01-01

    Rb-Sr isotopic measurements were carried out for whole rock and small sliced rock from the Himalayan gneiss which constitutes the metamorphosed basement of the Tethyan sediments. The results of the measurements on whole rock from the Barun migmatite, the Barun gneiss and the Irkhua gneiss indicate that complete Sr isotopic redistribution occurred about 520 m.y. ago. This age is interpreted as the time of the regional metamorphism. The analytical results of the small sliced slabs of the Himalayan gneiss indicate that Sr isotopic redistribution occurred among the sliced slabs 33.3 +- 13.2 m.y. ago. This age is interpreted as the time of the metamorphism in the sillimanite-amphibolite facies. The high initial 87 Sr/ 86 Sr ratio of 0.7372 +- 0.0031 from the Barun migmatite of the Himalayan gneiss suggests the Precambrian Origin of the source rocks. The analytical results on the sliced slab of the Barun migmatite indicate that the original age of the rocks is about 800 m.y. The rock is interpreted as the remobilized Precambrian crustal rock. The high initial 87 Sr/ 86 Sr ratio of the Barun gneiss and the Irkhua gneiss of the Himalayan gneiss (0.7234 +- 0.0013) indicates also the Precambrian origin of the source rocks. (author)

  5. Screening of plant species for comparative uptake abilities of radioactive Co, Rb, Sr and Cs from soil

    International Nuclear Information System (INIS)

    Gouthu, S.; Arie, T.; Ambe, S.; Yamaguchi, I.

    1997-01-01

    In case of radioactive fallout, persistence of long lived nuclides in soil and subsequent transfer into the food chain through plants over a long period is the key factor. The possibility of 'phytoremediation'is suggested to reduce the radionuclides in soil. To exploit the natural potential of some plants in absorbing or accumulating certain radionuclides and depleting the soil radioactivity, thirty-two plant species were tested under laboratory conditions for their comparative ability in taking up radioactive Rb, Co, Sr and Cs. Broccoli and tomato for Co; tomato, chard, sunflower and cucumber for Rb; cucumber, sunflower and turnip (Kyona) for Sr; and tomato, chard and cucumber for Cs were found to be effective compared to other species tested. (author)

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

    International Nuclear Information System (INIS)

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

    1979-01-01

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

  7. Geochronology (Rb-Sr, Sm-Nd and Pb-Pb) of the proterozoic granulitic and granitic rocks around Usilampatti, Madurai district, Tamil Nadu: implication on age of various lithounits

    International Nuclear Information System (INIS)

    Pandey, U.K.; Pandey, B.K.; Krishnamurthy, P.

    2005-01-01

    Rb-Sr, Sm-Nd and Pb-Pb systematics on mafic granulites, intermediate- charnockites, charnockites, calc-granulites, orthogneisses, leptynites, granites and two (2) mineral samples (microcline and muscovite) from pegmatite have been studied. Sm-Nd model ages (T DM ) for most of the rocks cluster around 2.1 Ga. Calc-granulites gave Rb-Sr whole rock isochron age of 1339 ± 110 Ma with initial 87 Sr/ 86 Sr ratio (I.R.) = 0.709. Mesoproterozoic age for the Metasedimentary Group of rocks (calc-granulites) has been inferred based on their 87 Sr/ 86 Sr ratio also. Granites and leptynites have yielded Rb-Sr whole rock isochron ages of 823± 38 Ma, with I.R. = 0.713 and 894± 82 Ma, with I.R. = 0.708 respectively which are younger than the calc-granulites. Microcline and muscovite from pegmatite gave Rb-Sr model ages as 532 and 491 Ma respectively. Granites, leptynites and calc-granulites are derived from the crustal source as indicated by their high initial 87 Sr/ 86 Sr ratios. Most probably the protolith of the granitic and granulitic rocks is of Palaeoproterozoic age in this part of the Madurai Block. The minimum age of granulite grade of metamorphism has been inferred at c. 850 Ma, indirectly on the basis of Rb-Sr ages of leptynites, which normally form during the evolution of granulite facies assemblages. Both granulite facies metamorphism and granitic magmatism probably took place during Neoproterozoic period correlatable to the early phase of Pan-African orogeny. Later decompression, causing mineral scale resetting of the Rb-Sr and Sm-Nd systematics, around 450-550 Ma, may correspond to the final exhumation, which brought the middle to lower crustal granulites to upper crustal levels, during the last phase of Pan-African activity. As per ages obtained on various lithounits in the present study the Metasedimentary Group of rocks (Mesoproterozoic) are younger than the Charnockite Group of rocks (Palaeoproterozoic) followed by the rocks belonging to the Migmatite Complex

  8. Geochronology (Rb-Sr, Sm-Nd and Pb-Pb) of the proterozoic granulitic and granitic rocks around Usilampatti, Madurai District, Tamil Nadu: implication on age of various lithounits

    International Nuclear Information System (INIS)

    Pandey, U.K.; Pandey, B.K.; Krishnamurthy, P.

    2005-01-01

    Rb-Sr, Sm-Nd and Pb-Pb systematics on mafic granulites, intermediate-charnockites, charnockites, calc- granulites, orthogneisses, leptynites, granites and two (2) mineral samples (microcline and muscovite) from pegmatite have been studied. Sm-Nd model ages (T DM ) for most of the rocks cluster around 2.1 Ga. Calc-granulites gave Rb-Sr whole rock isochron age of 1339± 110 Ma with initial 87 Sr/ 86 Sr ratio (IR)= 0.709. Mesoproterozoic age for the metasedimentary group of rocks (calc-granulites) has been inferred based on their 86 Sr/ 86 Sr ratio also. Granites and leptynites have yielded Rb-Sr whole rock isochron ages of 823 ± 38 Ma, with I.R. = 0.713 and 894± 82 Ma, with I.R.= 0.708 respectively which are younger than the calc-granulites. Microcline and muscovite from pegmatite gave Rb-Sr model ages as 532 and 491 Ma respectively. Granites, leptynites and calc-granulites are derived from the crustal source as indicated by their high initial 87 Sr/ 86 Sr ratios. Most probably the protolith of the granitic and granulitic rocks is of Palaeoproterozoic age in this part of the Madurai Block. The minimum age of granulite grade of metamorphism has been inferred at c. 850 Ma, indirectly on the basis of Rb-Sr ages of leptynites, which normally form during the evolution of granulite facies assemblages. Both granulite facies metamorphism and granitic magmatism probably took place during Neoproterozoic period correlatable to the early phase of Pan-African orogeny. Later decompression, causing mineral scale resetting of the Rb-Sr and Sm-Nd systematics, around 450-550 Ma, may correspond to the final exhumation, which brought the middle to lower crustal granulites to upper crustal levels, during the last phase of Pan-African activity. As per ages obtained on various lithounits in the present study the Metasedimentary Group of rocks (Mesoproterozoic) are younger than the Charnockite Group of rocks (Palaeoproterozoic) followed by the rocks belonging to the Migmatite Complex

  9. Rb-Sr age of the Sivamalai alkaline complex, Tamil Nadu

    International Nuclear Information System (INIS)

    Subba Rao, T.V.; Narayana, B.L.; Gopalan, K.

    1994-01-01

    The Sivamalai alkaline complex comprises ferro-, pyroxene- hornblende-and nepheline-syenites. Field relations show that the nepheline syenites followed the emplacement of non-feldspathoidal syenites. Mineralogical data on the syenite suite have been reviewed. The Sivamalai alkaline rocks are not strongly enriched in rare-earth elements like most miaskites. Rb-Sr isotopic analyses of a suite of six samples from the various members of the complex define an isochron corresponding to an age of 623 ± 21 Ma (2σ) and initial Sr ratio of 0.70376 ± 14 (2σ). This is consistent with a model of fractional crystallization of a parent magma derived from an upper mantle source with apparently no isotopic evidence for more than one magma source for the complex. The Sivamalai alkaline complex represents a Pan-African alkaline magmatic event in the southern granulite terrane of peninsular India. (author). 26 refs., 4 figs., 4 tabs

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

    International Nuclear Information System (INIS)

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

    1995-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Dikshitulu, G R; Dhana Raju, R [Dept. of Atomic Energy, Bangalore (India). Atomic Minerals Division; Pandey, B K; Krishna, Veena [Department of Atomic Energy, Hyderabad (India). Atomic Minerals Div.

    1995-01-01

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

  12. Absolute branching intensities in the decay of 92Rb to 92Sr

    CERN Document Server

    Lhersonneau, G; Rizzi, V; Alyakrinskiy, O; Lanchais, A; Volkov, Yu.M; Barzakh, A.E; Fedorov, D.V; Ionan, A.M; Ivanov, V.S; Mezilev, K.A; Moroz, F.V; Orlov, S.Yu; Panteleev, V.N; Lau, C; Bajeat, O; Essabaa, S; Leroy, R; Jardin, P; Stroe, L; 10.1103/PhysRevC.74.017308

    2006-01-01

    The branching of the 2+ to 0+ transition in 92Sr has been measured to 0.032(4) per 92Rb decay. It confirms an earlier measurement however discarded in nuclear data evaluations since in contradiction with accepted lower logft limits. The conflict could be solved assuming that close to half of the decay intensity, mostly as high-energy ground-state transitions, is missing in th edecay scheme.

  13. Rb-Sr ages and initial 87Sr/86Sr ratios of late paleozoic granitic rocks from northern Chile

    International Nuclear Information System (INIS)

    Shibata, Ken; Ishihara, Shunso; Ulriksen, C.E.

    1984-01-01

    Rb-Sr whole-rock isochron ages were determined on three suites of so-called Paleozoic granitic rocks from northern coastal Chile. The granitic rocks from the Valparaiso and Ci Funcho areas are dated as 296.3 +- 5.4 Ma and 262.2 +- 4.6 Ma, respectively, which are in accord with geologically estimated age. The rocks from the Chanaral area is dated as 212.8 +- 8.6 Ma, which is correlated close to the Triassic-Jurassic boundary age. A K-Ar age of 196 +- 6 Ma was obtained on biotite in granite from Esmeralda between Ci Funcho and Chanaral. These age results demonstrate that no Precambrian plutonism occurred in the studied area, and that so-called Paleozoic granitic rocks in the Ci Funcho-Chanaral area are divided into Permian and early Mesozoic in age. Initial 87 Sr/ 86 Sr ratios of the ilmenite-series granitic rocks from the coastal region are 0.70641 (Valparaiso), 0.70635 (Ci Funcho) and 0.70455 (Chanaral). These relatively low ratios deny substantial crustal contribution to the granitoids. The initial ratios of magnetite-series granitoids from porphyry- and manto-type mineralized areas (Chiquicamata, El Salvador and Tocopilla) are as low as 0.70344 to 0.70464. (author)

  14. Rb-Sr Isotopic Systematics of Alkali-Rich Fragments in the Yamato-74442 LL-Chondritic Breccia

    Science.gov (United States)

    Yokoyama, T.; Misawa, K.; Okano, O.; Shih, C.-Y.; Nyquist, L. E.; Simo, J. I.; Tappa, M. J.; Yoneda, S.

    2012-01-01

    Alkali-rich igneous fragments were identified in the brecciated LL-chondrites, Kr henberg (LL5)], Bhola (LL3-6) and Yamato (Y)-74442 (LL4), and show characteristic fractionation patterns of alkaline elements. The K-Rb-Cs-rich fragments in Kr henberg, Bhola, and Y-74442 are very similar in mineralogy and petrography (olivine + pyroxene + glass), suggesting that they could have come from related precursor materials. We have undertaken Rb-Sr isotopic studies on alkali-rich fragments in Y-74442 to precisely determine their crystallization ages and the isotopic signatures of their precursor material(s).

  15. Screening of plant species for comparative uptake abilities of radioactive Co, Rb, Sr and Cs from soil

    Energy Technology Data Exchange (ETDEWEB)

    Gouthu, S; Arie, T; Ambe, S; Yamaguchi, I [Institute of Physical and Chemical Research, Wako, Saitama (Japan)

    1997-08-01

    In case of radioactive fallout, persistence of long lived nuclides in soil and subsequent transfer into the food chain through plants over a long period is the key factor. The possibility of `phytoremediation`is suggested to reduce the radionuclides in soil. To exploit the natural potential of some plants in absorbing or accumulating certain radionuclides and depleting the soil radioactivity, thirty-two plant species were tested under laboratory conditions for their comparative ability in taking up radioactive Rb, Co, Sr and Cs. Broccoli and tomato for Co; tomato, chard, sunflower and cucumber for Rb; cucumber, sunflower and turnip (Kyona) for Sr; and tomato, chard and cucumber for Cs were found to be effective compared to other species tested. (author). 13 refs.

  16. Prospects for transferring 87Rb84Sr dimers to the rovibrational ground state based on calculated molecular structures

    Science.gov (United States)

    Chen, Tao; Zhu, Shaobing; Li, Xiaolin; Qian, Jun; Wang, Yuzhu

    2014-06-01

    Using fitted model potential curves of the ground and lowest three excited states yielded by the relativistic Kramers-restricted multireference configuration interaction method with 19 electrons correlated, we theoretically investigate the rovibrational properties including the number of vibrational state and diagonally distributed Franck-Condon factors for a 87Rb84Sr molecule. Benefiting from a turning point at about v'=20 for the Franck-Condon factors between the ground state and spin-orbit 2(Ω=1/2) excited state, we choose |2(Ω=1/2),v'=21,J'=1> as the intermediate state in the three-level model to theoretically analyze the possibility of performing stimulated Raman adiabatic passage to transfer weakly bound RbSr molecules to the rovibrational ground state. With 1550 nm pump laser (2 W/cm2) and 1342 nm dump laser (10 mW/cm2) employed and appropriate settings of pulse time length (about 300 μs), we have formalistically achieved a round-trip transfer efficiency of 60%, namely 77% for one-way transfer. The results demonstrate the possibility of producing polar 87Rb84Sr molecules efficiently in a submicrokelvin regime, and further provide promising directions for future theoretical and experimental studies on alkali-alkaline(rare)-earth dimers.

  17. Rb-Sr dating of low-grade metamorphics in the U.S.S.R

    International Nuclear Information System (INIS)

    Gorokhov, I.M.; Varshavskaya, E.S.; Kutyavin, E.P.; Melnikov, N.N.

    1982-01-01

    Geologically well-dated low-grade metasedimentary and metavolcanic rocks from five localities have been studied using the whole-rock Rb-Sr age method. All age values obtained are younger than those suggested by stratigraphy. When whole-rock points fit either an isochron or an errorchron with low value of the mean square of weighted deviates, the slope of this line gives the age of metamorphism. (Auth.)

  18. Rb-Sr geochronology of neoproterozoic syenites in parts of northern Tamil Nadu: implication on Pan-African magmatism

    International Nuclear Information System (INIS)

    Pandey, U.K.; Prasad, R.N.; Krishna, Veena; Paneer Selvam, A.; Chabria, Tikam

    1996-01-01

    This paper presents Rb-Sr whole rock isochron age data on two syenite plutons viz. Elagiri and Rasimalai, and results of this study may constrain the timing of magmatic event and crystal evolution in northern granulite segment

  19. Rb-Sr Autunian age of cordierite-bearing migmatites from northern Cevennes (French Massif Central)

    International Nuclear Information System (INIS)

    Chenevoy, M.; Gay, M.; Duthou, J.L.

    1995-01-01

    On the basis of whole rock Rb-Sr data, an Autunian age (287 ± 6 Ma) is ascribed to the cordierite-bearing migmatites occurring south of Mt Pilat. The related anatexis is therefore linked with the low pressure metamorphism, and is distinct from the Devonian anatexis with gave rise to the Barrovian cordierite migmatites in the Lyonnais area. (authors). 34 refs., 2 figs

  20. Rb-Sr and K-Ar isotopic evidence for neoproterozoic (Pan-African) granulite metamorphism from the basement of Mumbai offshore basin, India

    International Nuclear Information System (INIS)

    Rathore, S.S.; Vijan, A.R.; Singh, M.P.; Misra, K.N.; Prabhu, B.N.

    2000-01-01

    Precambrian basement from well HBM-1 in the Heera oil field of Mumbai offshore basin has been dated by Rb-Sr and K-Ar methods. Five granulitic basement samples from three conventional drill cores have yielded Rb-Sr isochron age of 502±25 Ma with an initial Sr ratio of 0.70855±0.00013. This age has been interpreted as the time of granulite facies metamorphism of the basement rocks in the region. Two whole rock samples from the basement of this well have yielded mutually concordant K-Ar ages of 505±16 Ma and 507±17 Ma. The K-Ar ages are significantly similar to Rb-Sr age obtained from this well, suggesting complete isotopic reequilibration around 500 Ma ago. The time of secondary thermal heating around 500 Ma ago in the basement of Heera field coincides with the widespread neoproterozoic (Pan-African) thermo-tectonic event extending from the Arabian Peninsula and eastern Africa covering Madagascar, southern India. Sri Lanka and East Antarctica. This study widens the limit of the Pan-African zone, which hitherto was thought to be confined to the western part (presently southern part) of the Indian subcontinent, towards further east. (author)

  1. Reaction of Rb and oxygen overlayers with single-crystalline Bi2Sr2CaCu2O/sub 8+//sub δ/ superconductors

    International Nuclear Information System (INIS)

    Lindberg, P.A.P.; Shen, Z.; Wells, B.O.; Dessau, D.S.; Mitzi, D.B.; Lindau, I.; Spicer, W.E.; Kapitulnik, A.

    1989-01-01

    Single crystals of Bi 2 Sr 2 CaCu 2 O/sub 8+//sub δ/ superconductors, in situ cleaved and modified by Rb and oxygen overlayers, have been studied using ultraviolet and x-ray photoemission spectroscopy. The core-level results show that Rb strongly reacts with the Bi and O states, while the Cu and Sr states are left unchanged. This observation strongly indicates that the Bi-O plane forms the surface layer. Subsequent exposure to oxygen results in new oxygen states at the surface as monitored by the O 1s core-level data. For both Rb and oxygen overlayers the valence-band spectra are severely altered. In particular, new valence-band states, presumably of oxygen character, are formed

  2. Granitoids of the Mala Fatra and Velka Fatra Mts.: Rb/Sr isochron geochronology (Western Carpathians)

    International Nuclear Information System (INIS)

    Bagdasaryan, G.P.; Gukasyan, R.C.; Cambel, B.; Kamenicky, L.; Macek, J.

    1992-01-01

    New data formerly lacking (with exceptions - Dubna Skala, 1990) were gained from the Western Carpathian core mountain - Mala Fatra and Velka Fatra - by the Rb/Sr method. The isochron based on 13 samples gave the age of 361±10 Ma for Mala Fatra and Velka Fatra intrusions. (author) 4 tabs., 4 figs., 8 refs

  3. Determination of Sr, Ba, Rb, and Cs in biological reference materials using a radiochemical NAA group separation procedure

    International Nuclear Information System (INIS)

    Mizera, J.; Randa, Z.

    2008-01-01

    Strontium, barium, rubidium, and cesium in selected, predominantly biological, reference materials (NIST 1515, 1547, 1549, 1566a, 1571, 1577b, 2704, CTA-OTL-1, and Bowen's Kale) were determined using neutron activation analysis (NAA) in two different analytical modes - instrumental NAA with epithermal neutrons (ENAA), and NAA with radiochemical group separation of Sr-Ba and Rb-Cs (RNAA). The ENAA mode was based on long-term (5 h) irradiation of samples in a Cd shielding. The RNAA procedure was based on long-term (20 h) irradiation of samples, their decomposition / dissolution by alkaline-oxidative fusion, and precipitation of Sr and Ba sulfates, and sorption of Rb and Cs onto ammonium phosphomolybdate (APM). Both methods provided element contents in the analyzed reference materials consistent with certified and/or literature values. (author)

  4. Absolute transition intensities in decay of 92Rb

    International Nuclear Information System (INIS)

    Lhersonneau, G.; Rizzi, V.; Barzakh, A.

    2005-01-01

    In a first step studied the evolution of the ion current of 92 Rb and 94 Sr produced by surface ionisation versus temperature. Ratios of peak areas of γ lines emitted in Sr (1428 keV) and Rb (837 keV) decays are shown. The temperature is decreased from working conditions until the ion currents become very weak. The plateau at low temperature can be understood by the fact that Sr is not ionised anymore and there is no more decease possible. Then, the only contribution to the Sr decay peak is from the decay of Rb collected before transport of the activity to the counting station

  5. Rb/Sr ages of metamorphites of the Herbert Mountains, Shackleton Range, Antarctica

    International Nuclear Information System (INIS)

    Hofmann, J.; Pilot, J.; Schlichting, M.

    1981-01-01

    Results of Rb/Sr-age determinations from six mica schists, sampled in the upper part of the Shackleton metamorphic complex (Herbert Mountains, Shackleton Range, Antarctica) are reported. A three point isochrone gives an age of 470 +- 36 mio. yrs., a two point isochrone an age of 1414 +- 185 mio yrs. The first age marks a thermo-magmatic activation of early paleozoic age, the second one is interpretated as the age of regional metamorphism from the upper parts of the Shackleton metamorphic complex. The results are discussed under consideration of former age determinations. (author)

  6. Rb-Sr and Sm-Nd Isotopic Studies of Lunar Green and Orange Glasses

    Science.gov (United States)

    Shih, C.-Y.; Nyquist, L. E.; Reese, Y.

    2012-01-01

    Lunar volcanic glassy beads have been considered as quenched basaltic magmas derived directly from deep lunar mantle during fire-fountaining eruptions [1]. Since these sub-mm size glassy melt droplets were cooled in a hot gaseous medium during free flight [2], they have not been subject to mineral fractionations. Thus, they represent primary magmas and are the best samples for the investigation of the lunar mantle. Previously, we presented preliminary Rb- Sr and Sm-Nd isotopic results for green and orange glassy samples from green glass clod 15426,63 and orange soil 74220,44, respectively [3]. Using these isotopic data, initial Sr-87/Sr-86 and Nd ratios for these pristine mare glass sources can be calculated from their respective crystallization ages previously determined by other age-dating techniques. These isotopic data were used to evaluate the mineralogy of the mantle sources. In this report, we analyzed additional glassy samples in order to further characterize isotopic signatures of their source regions. Also, we'll postulate a relationship between these two major mare basalt source mineralogies in the context of lunar magma ocean dynamics.

  7. Rb/Sr and K/Ar dating of Slovakia's rocks, its possibilities and interpretation

    International Nuclear Information System (INIS)

    Cambel, B.; Bagdasaryan, G.P.; Gukasyan, P.Kh.; Veselskij, I.

    1979-01-01

    Nuclear geochronological data are evaluated and summarized into histograms. On the basis of an evaluation, the results are compared obtained using various methods (K/Ar, Rb/Sr and U-Th-Pb) and the age of rocks in West Carpathians determined. It is pointed out that the age determination is dependent on the geochemical state of the studied minerals and rocks. The obtained results confirm the palaeozoic age of the majority of rocks of West Carpathians. Direct nuclear geochronological evidence of precambrium rocks has not yet been obtained. (author)

  8. Age Rb/Sr de 1670 M.a. pour les mylonites de l'accident du Sassandra (Côte d'Ivoire) conséquence pour la datation des mouvements fini-éburnéens dans le craton ouest-africain

    Science.gov (United States)

    Caen-Vachette, M.; Tempier, P.; Camil, J.

    An eight point Rb/Sr isochron determination on whole rocks yielded an age of 1670 M.a. for the mylonites from the Sassandra couloir of ductile deformation, which extends N-S. A similar age is proposed for the mylonite from a zone of parallel trend stretching NNW-SSE in the Reguibat dome (Mauritania). A correlation is suggested with the Guri fault of the Guayana shield in South America.

  9. On the chemical resolution of the {sup 87}Rb{sup +} (s{sup 0})/{sup 87}Sr{sup +} (s{sup 1}) isobaric interference: A kinetic search for an optimum reagent

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Ping; Koyanagi, Gregory K. [Department of Chemistry, Centre for Research in Mass Spectrometry and Centre for Research in Earth and Space Science, York University, Toronto, Ontario, M3J 1P3 (Canada); Bohme, Diethard K. [Department of Chemistry, Centre for Research in Mass Spectrometry and Centre for Research in Earth and Space Science, York University, Toronto, Ontario, M3J 1P3 (Canada)], E-mail: dkbohme@yorku.ca

    2008-10-03

    Room-temperature reactions of the atomic cations Sr{sup +} and Rb{sup +} have been surveyed systematically with a variety of gases using an Inductively-Coupled Plasma/Selected-Ion Flow Tube (ICP/SIFT) tandem mass spectrometer. Rate coefficients and product distributions have been measured in He buffer gas at 0.35 Torr and 295 K for reactions of Sr{sup +} and Rb{sup +} with CH{sub 3}F, CH{sub 3}Cl, N{sub 2}O, CO{sub 2}, CS{sub 2}, SF{sub 6}, D{sub 2}O and NH{sub 3}. Rb{sup +} (s{sup 0}) is seen to be quite inert with these molecules and reacts either slowly by molecule addition or not at all, while Sr{sup +} (s{sup 1}) is much more reactive with all these 8 molecules, especially with CH{sub 3}F, CH{sub 3}Cl, N{sub 2}O and SF{sub 6}. Sr{sup +} reacts with CH{sub 3}F and SF{sub 6} by F-atom transfer, with CH{sub 3}Cl by Cl-atom transfer and with N{sub 2}O by O-atom transfer, and the reaction rate coefficients are all quite high, k {>=} 1.4 x 10{sup -11} cm{sup 3} molecules{sup -1} s{sup -1}. The extreme differences in reactivity with CH{sub 3}F, SF{sub 6}, CH{sub 3}Cl and N{sub 2}O provide a chemical basis for the separation of isobaric interferences of {sup 87}Rb{sup +} and {sup 87}Sr{sup +} often encountered in ICP-MS. Among these four molecules, SF{sub 6} exhibits the largest difference in reactivity, almost a factor of 10{sup 4}, and so is identified as the kinetically recommended reagent for the chemical resolution of the isobaric interference of {sup 87}Rb{sup +} and {sup 87}Sr{sup +}.

  10. Rb-Sr measurements on metamorphic rocks from the Barro Alto Complex, Goias, Brazil

    International Nuclear Information System (INIS)

    Fuck, R.A.; Neves, B.B.B.; Cordani, U.G.; Kawashita, K.

    1988-01-01

    The Barro Alto Complex comprises a highly deformed and metamorphosed association of plutonic, volcanic, and sedimentary rocks exposed in a 150 x 25 Km boomerang-like strip in Central Goias, Brazil. It is the southernmost tip of an extensive yet discontinuous belt of granulite and amphibolite facies metamorphic rocks which include the Niquelandia and Cana Brava complexes to the north. Two rock associations are distinguished within the granulite belt. The first one comprises a sequence of fine-grained mafic granulite, hypersthene-quartz-feldspar granulite, garnet quartzite, sillimanite-garnet-cordierite gneiss, calc-silicate rock, and magnetite-rich iron formation. The second association comprises medium-to coarse-grained mafic rocks. The medium-grade rocks of the western/northern portion (Barro Alto Complex) comprise both layered mafic rocks and a volcanic-sedimentary sequence, deformed and metamorphosed under amphibolite facies conditions. The fine-grained amphibolite form the basal part of the Juscelandia meta volcanic-sedimentary sequence. A geochronologic investigation by the Rb-Sr method has been carried out mainly on felsic rocks from the granulite belt and gneisses of the Juscelandia sequence. The analytical results for the Juscelandia sequence are presented. Isotope results for rocks from different outcrops along the gneiss layer near Juscelandia are also presented. In conclusion, Rb-Sr isotope measurements suggest that the Barro Alto rocks have undergone at least one important metamorphic event during Middle Proterozoic times, around 1300 Ma ago. During that event volcanic and sedimentary rocks of the Juscelandia sequence, as well as the underlying gabbro-anorthosite layered complex, underwent deformation and recrystallization under amphibolite facies conditions. (author)

  11. Precambrain Rb-Sr isochron ages from the crystalline complexes of inner Forsblads Fjord, East Greenland fold belt

    International Nuclear Information System (INIS)

    Rex, D.C.; Gledhill, A.R.; Higgins, A.K.

    1977-01-01

    Several collections of samples were made from crystalline units in inner Forsblads Fjord in 1974. Results of whole rock Rb-Sr analyses on two of these collections are presented, and give an Archaean age for banded gneisses and a middle Proterozoic age for quartzitic metasediments. These ages confirm the occurence of major Precambrian complexes within the East Greenland Caledonian fold belt. (author)

  12. Between carbonatite and lamproite—Diamondiferous Torngat ultramafic lamprophyres formed by carbonate-fluxed melting of cratonic MARID-type metasomes

    Science.gov (United States)

    Tappe, Sebastian; Foley, Stephen F.; Kjarsgaard, Bruce A.; Romer, Rolf L.; Heaman, Larry M.; Stracke, Andreas; Jenner, George A.

    2008-07-01

    New U-Pb perovskite ages reveal that diamondiferous ultramafic lamprophyre magmas erupted through the Archean crust of northern Labrador and Quebec (eastern Canada) between ca. 610 and 565 Ma, a period of strong rifting activity throughout contiguous Laurentia and Baltica. The observed Torngat carbonate-rich aillikite/carbonatite and carbonate-poor mela-aillikite dyke varieties show a large spread in Sr-Nd-Hf-Pb isotope ratios with pronounced correlations between isotope systems. An isotopically depleted component is identified solely within aillikites ( 87Sr/ 86Sr i = 0.70323-0.70377; ɛNd i = +1.2-+1.8; ɛHf i = +1.4-+3.5; 206Pb/ 204Pb i = 18.2-18.5), whereas some aillikites and all mela-aillikites range to more enriched isotope signatures ( 87Sr/ 86Sr i = 0.70388-0.70523; ɛNd i = -0.5 to -3.9; ɛHf i = -0.6 to -6.0; 206Pb/ 204Pb i = 17.8-18.2). These contrasting isotopic characteristics of aillikites/carbonatites and mela-aillikites, along with subtle differences in their modal carbonate, SiO 2, Al 2O 3, Na 2O, Cs-Rb, and Zr-Hf contents, are consistent with two distinctive metasomatic assemblages of different age in the mantle magma source region. Integration of petrologic, geochemical, and isotopic information leads us to propose that the isotopically enriched component originated from a reduced phlogopite-richterite-Ti-oxide dominated source assemblage that is reminiscent of MARID suite xenoliths. In contrast, the isotopically depleted component was derived from a more oxidized phlogopite-carbonate dominated source assemblage. We argue that low-degree CO 2-rich potassic silicate melts from the convective upper mantle were preferentially channelled into an older, pre-existing MARID-type vein network at the base of the North Atlantic craton lithosphere, where they froze to form new phlogopite-carbonate dominated veins. Continued stretching and thinning of the cratonic lithosphere during the Late Neoproterozoic remobilized the carbonate-rich vein material and

  13. Age of meta-rhyolite of Marata sequence, Araxa Group, Goias: geochronology study by U-Pb in zircon, Rb-Sr and Sm-Nd methods

    International Nuclear Information System (INIS)

    Pimentel, M.M.; Heaman, L.; Fuck, R.A.

    1992-01-01

    U-Pb isotopic analyses in eight zircon fractions separated from a meta-rhyolite sample of the Marata sequence (Araxa Group, Goias) are presented. Two morphologically distinct zircon populations were identified: stubby prismatic crystals (width:length of 1:2 to 1:3) in which core-overgrowth relationships are observed; long prismatic crystals (needles) with width:length ratios of ca. 1:10. Analyses performed on group zircons indicated the presence of a ca. 2.0 Ga. old inherited component. Analyses of group zircons plot very close to the concordia and yield an upper intercepts age of 794 ± 10 Ma for the crystallization of the volcanic protolith. The study was complemented with whole-rock isotopic analyses by the Rb-Sr and Sm-Nd methods. Rb-Sr isochron obtained with samples from two different outcrops gave data of 829 ± 82 Ma (initial 87 Sr/ 86 Sr of 0.7057 ± 0.0157) and 691 ± 30 Ma (initial 87 Sr/ 86 Sr of 0.7337 ± 0.0034). The latter reflects a later Sr-isotopic re-homogenization episode, possibly associated with the intense deformation and metamorphism suffered by these rocks. Sm-Nd isotopic analyses on three samples reveal EN d (T) (T =794 Ma) values in the range of -6.1 to -9.5 which indicate the presence of older (early Proterozoic) crustal Nd. This is consistent with the inheritance pattern shown in the U-Pb isotopic results. (author)

  14. Rb-Sr geochronology from Barro Alto Complex, Goias: metamorphism evidence of high degree and continental collision around 1300 Ma ago in Central Brazil

    International Nuclear Information System (INIS)

    Fuck, R.A.; Neves, B.B.B.; Cordani, U.G.; Kawashita, K.

    1989-01-01

    Rb-Sr geochronologic investigation carried out on rocks from the Barro Alto Complex, Goias, yielded iso chronic ages of 1266 +- 17 Ma, for felsic rocks from the granulite belt and 1330 +- 67 Ma, for gneisses belonging to the Juscelandia Sequence. Rb-Sr isotope measurements suggest that Barro Alto rocks have undergone an important metamorphic event during middle Proterozoic times, around 1300 Ma ago. During that event, volcanic and sedimentary rocks of Juscelandia Sequence, as well as the underlying gabbros-anorthosite layered complex, underwent deformation and recrystallization under amphibolite facies conditions. Deformation and metamorphism took place during the collision of two continental blocks, which resulted in a southeastward directed thrust complex, allowing the exposure of granulite slices from the middle-lower crust of the overthrusted block. (author)

  15. Rb-Sr ages of the biotite and muscovite of the Himalayas, eastern Nepal

    International Nuclear Information System (INIS)

    Kai, Kunio

    1981-01-01

    Rb-Sr ages of biotite from the southern flank of Mt. Everest, eastern Nepal, range from 14.1 to 1.3 m.y., the youngest biotite coexists with muscovite of 7.3 m.y. These different ages for different samples reflect the difference in cooling history related to the uplift of the Himalayas. The biotite ages decrease with increasing distance from the high mountain range, suggesting that the high range, i.e., the northern area, was uplifted earlier than the southern area. The relationship between the ages and altitutes of sampling sites indicates that the uplift rate of the northern area was 0.60 mm/yr. (author)

  16. Piedra lata terrane of Uruguay: Rb-Sr geochronological data of two new paleoproterozoic (transamazonian) granitoids

    International Nuclear Information System (INIS)

    Cingolani, C; Bossi, J; Varela, R; Maldonado, S.; Pineyro, D.; Schipilov, A

    2001-01-01

    The Precambrian basement of Uruguay consists of three major terranes separated and crosscut by wide NE-striking subvertical transcurrent shear zones. The western terrane as a part of the Rio de la Plata Craton is known as the Piedra Alta Terrane (PAT). This is separated from the Nico Perez Terrane by the Sarandi del Yi-Piri olis subvertical shear zone (Bossi et al., 1993). A mafic dykes complex intruded the PAT at 1.8 Ga and was not later deformed. The PAT has equivalent rocks in the igneous-metamorphic basement of Tandilia region and the Martin Garcia Island, Buenos Aires Province, Argentina (Dalla Salda et al., 1988; Cingolani and Dalla Salda, 2000). The PAT shows no evidence of the Neoproterozoic orogenies and is considered a best preserved Paleoproterozoic block (Transamazonian Cycle). It contains three E-W trending belts of volcano-sedimentary rocks with low grade metamorphism. These are from south to north: Pando, San Jose and Andresito belts (Bossi et al., 1996). Associated with them, three granitic-gneissic zones he Ecilda Paullier, Florida and Feliciano- were recognized with magmatic intrusives emplaced at different crustal levels. The San Jose belt is the largest supracrustal unit and contains abundant volcanic and volcaniclastic rocks of low grade metamorphic (Paso Severino Fm.) with sheets of granitic rocks intercalated (Mutti et al., 1996; Bossi et al., 1996). The associated granitic rocks are of large areal extension, mostly granodiorites and tonalites, and minor monzogranite and gabbro (e.g. Cerro Rospide region), including xenoliths from Paso Severino Fm. Towards the north of the San Jose belt an important Florida granitized zone is developed in the central part of the PAT, where the Pintos massif was recognized. The main purpose of this contribution is to offer new Rb-Sr geochronological data from two granitoid units, The Cerro Rospide intrusive in Paso Severino Fm. and Pintos massif included in medium grade migmatic-metamorphic complex and its

  17. Rock Rb-Sr ages from Bananal region - Sao Paulo State, Brazil

    International Nuclear Information System (INIS)

    Dias Neto, C.M.; Tassinari, C.G.C.; Silva, M.E.

    1996-01-01

    New Rb-Sr whole rock isochron ages have been determined for the main lithological units that occur in Sao Paulo and Rio de Janeiro States. These rocks belong to Serra do Mar domain. The purpose of this work is to characterize the sequence of the geological events as well as the possible relationship between the different rocks. The geochronological data suggest that the paragneisses and the basement rocks, represented by ortho gneisses nuclei, were generated under amphibolite conditions around 700 Ma. At the same time the leucogranites were generated by partial melting processes and injected into both gneiss types. Tarditectonic granitic magmatic activities took place within ductile shear zones. One of the granites, the Getulandia granite, yielded an age of 514 Ma, falling in the range of the late Brasiliano Cycle which extended into the Middle Cambrian. (author). 9 figs., 1 tab

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

    International Nuclear Information System (INIS)

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

    1998-01-01

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

  19. 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

  20. A high 87Sr 86Sr mantle source for low alkali tholeiite, northern Great Basin

    Science.gov (United States)

    Mark, R.K.; Lee, Hu C.; Bowman, H.R.; Asaro, F.; McKee, E.H.; Coats, R.R.

    1975-01-01

    Olivine tholeiites, the youngest Tertiary units (about 8-11 m.y. old) at five widely spaced localities in northeastern Nevada, are geologically related to the basalts of the Snake River Plain, Idaho, to the north and are similar in major element and alkali chemistry to mid-ocean ridge basalts (MORB) and island arc tholeiites. The measured K (1250-3350 ppm), Rb (1??9-6??2 ppm) and Sr (140-240 ppm) concentrations overlap the range reported for MORB. Three of the five samples have low, unfractionated rare earth element (REE) patterns, the other two show moderate light-REE enrichment. Barium concentration is high and variable (100-780 ppm) and does not correlate with the other LIL elements. The rocks have 87Sr/86Sr = 0??7052-0??7076, considerably higher than MORB (~0??702-0??703). These samples are chemically distinct (i.e. less alkalic) from the olivine tholeiites from the adjacent Snake River Plain, but their Sr isotopic compositions are similar. They contain Sr that is distinctly more radiogenic than the basalts from the adjacent Great Basin. About 10 b.y. would be required for the mean measured Rb/Sr (~ 0??02) of these samples to generate, in a closed system, the radiogenic Sr they contain. The low alkali content of these basalts makes crustal contamination an unlikely mechanism. If the magma is uncontaminated, the time-averaged Rb/Sr of the source material must have been ~0??04. A significant decrease in Rb/Sr of the source material (a factor 2??) thus most probably occurred in the relatively recent (1??09 yr) past. Such a decrease of Rb/Sr in the mantle could accompany alkali depletion produced by an episode of partial melting and magma extraction. In contrast, low 87Sr 86Sr ratios indicate that the source material of the mid-ocean ridge basalts may have been depleted early in the Earth's history. ?? 1975.

  1. Investigation into the metamorphic Nappes of the Central Scandinavian Caledonides on the basis of Rb-Sr and K-Ar age determination

    International Nuclear Information System (INIS)

    Reymer, A.P.S.

    1979-01-01

    This study concerns age determinations on several rock units of metamorphic nappes in the central Scandinavian Caledonides. Rb-Sr analyses on whole-rocks and minerals (biotite, muscovite/phengite, feldspars, garnet) were made as well as K-Ar determinations on biotite, muscovite/phengite, amphibole and feldspar. (Auth.)

  2. Sr-isotope stratigraphy and dating of Neo-proterozoic carbonates and glacials from the northern and western parts of the Congo Craton

    International Nuclear Information System (INIS)

    Poidevin, J.L.

    2007-01-01

    Numerous occurrences of Neo-proterozoic carbonate platforms and glacigenic litho-facies are present around the Congo craton. They are especially well developed on its western and northern borders, i.e. in the fore-lands of the West Congo and Oubanguides belts. Sr isotopic stratigraphy enables us to characterize the deposition age of some carbonate units from these two domains. The 87 Sr/ 86 Sr isotopic ratios of limestones from the late 'Haut Shiloango' (0.7068) and the 'Schisto-calcaire' (0.7075) of the West-Congo domain are of post-Sturtian and post-Marinoan ages, respectively. The Lenda carbonates (0.7066) from the Northeast of the Democratic Republic of Congo and the limestones (0.7076) from the Bangui Basin, both in the Oubanguides fore-land, are of pre-Sturtian and post-Marinoan ages, respectively. These data associated with lithostratigraphic correlations allow us to ascribe the 'Bas Congo' lower mixtite (tillite) and the Akwokwo tillite (Lindian) to the Sturtian ice age. In the same way, the 'Bas Congo' upper mixtite (tillite) and the Bondo tillite (Bakouma Basin) are likely Marinoan in age. A new synthetic stratigraphy for these Neo-proterozoic domains is developed. (author)

  3. Rb-Sr systematics in drill core samples of the Eye-Dashwa Lakes pluton at the whole rock and mineral scale

    International Nuclear Information System (INIS)

    Peterman, Z.E.; Futa, K.; Kamineni, D.C.

    1990-01-01

    Twenty-one whole-rock samples from boreholes ATK-1 and ATK-6 define a precise Rb-Sr isochron with an age of 2637 ± 33 Ma and initial 87 Sr/ 86 Sr intercept, IR(Sr), of 0.70144 ± 0.00006. An internal mineral isochron for ATC-1 (991-997) and biotites from ATK-1 (35.63) and ATK-1 (3.84) give younger ages of 2541 ± 14 Ma 2574 ± 25 Ma, and 2534 ± 25 Ma, respectively. Data for samples from fracture zones scatter but correlate around an isochron of 2281 ± 153 Ma. The internal isochron and biotite ages record cooling below about 300 C due to uplift and erosion. The younger age, 2281 ± 153 Ma, records an episode or episodes of brittle failure at relatively high crustal levels. These fractures provided pathways for infiltration of water, which facilitated the mineralogical alteration

  4. Possible two-stage 87Sr evolution in the Stockdale Rhyolite

    International Nuclear Information System (INIS)

    Compston, W.; McDougall, I.; Wyborn, D.

    1982-01-01

    The Rb-Sr total-rock data for the Stockdale Rhyolite, of significance for the Palaeozoic time scale, are more scattered about a single-stage isochron than expected from experimental error. Two-stage 87 Sr evolution for several of the samples is explored to explain this, as an alternative to variation in the initial 87 Sr/ 86 Sr which is customarily used in single-stage dating models. The deletion of certain samples having very high Rb/Sr removes most of the excess scatter and leads to an estimate of 430 +- 7 m.y. for the age of extrusion. There is a younger alignment of Rb-Sr data within each sampling site at 412 +- 7 m.y. We suggest that the Stockdale Rhyolite is at least 430 m.y. old, that its original range in Rb/Sr was smaller than now observed, and that it experienced a net loss in Sr during later hydrothermal alteration at ca. 412 m.y. (orig.)

  5. Rb-Sr geochronology from Sao Felix to Xingu: preliminary results

    International Nuclear Information System (INIS)

    Lafon, J.M.; Pereira, E.D.; Silva Barradas, J.A. da

    1991-01-01

    Rb-Sr systematics have been applied on rocks from the Sao Felix do Xingu region, in the southeastern part of the State of Para. An age of 2716 ± 34 Ma with IR of 0.70292 ± 0.00030 (MSWD = 1.54) and an age of 2677 ± 50 Ma with IR of 0.70161 ± 0.00022 (MSWD = 5.21) had been obtained for a granitic body and a tonalitic body respectively, both of them associated to the green stones belts that occur in this area. Gneisses from the Xingu complex gave an age of 2574 ± 57 Ma with an IR of 0.70416 ± 0.00054 (MSWD = 5.06). An age of 1653 ± 14 Ma with IR of 0.70823 ± 0.02361 (MSWD = 1.71) had been obtained for the Velho Guilherme granite that crosscut the granite-green stones terrains. Such geochronological data show the existence of a magmatic event between 2.72 Ga and 2.68 Ga and permit us to conclude on the archaean age of the green stones terrains. (author)

  6. The effect of secondary apatite on the initial 87Sr/86Sr ratio determination in granitic rocks: a case study of the Tadamigawa pluton, northeastern Japan

    Science.gov (United States)

    Wakasugi, Y.; Ichino, K.; Tanioka, Y.; Wakaki, S.; Tsuboi, M.; Ishikawa, T.

    2017-12-01

    Apatite is a major accessory mineral in igneous rocks. Because Rb contents in apatite are very low, 87Sr/86Sr ratios of magmatic apatite are useful to estimate the initial 87Sr/86Sr ratio (SrI) of igneous rocks. Secondary post-magmatic event such as hydrothermal alteration may also crystallize secondary apatite, which may inhibit the estimation of SrI of igneous rocks. In this study, we examine the effects of secondary apatite on the initial 87Sr/86Sr ratio determination of granitic rocks by using acid leaching technique. Leached apatite samples were first separated from the whole rock powder as a heavy mineral fraction by heavy liquid technique, and the heavy mineral fraction was then leached by 3 M HNO3. The isotopic ratios of Sr and the concentrations of Rb and Sr were analyzed by TIMS and ICP-MS at Kochi Core Center, respectively. The Tadamigawa Older-stage granites, which locate in the Taishaku Mountains at the northeastern part of Japan, intrude into the Ashio Jurassic complex, and the ages of these rocks are late Cretaceous to Paleogene. The U-Pb ages of zircon and the K-Ar ages of biotite for these rocks are c. 100 Ma [1, 2]. Rb-Sr whole-rock isochron age of the pluton is 96.5 ± 1.3 Ma (SrI = 0.70534 ± 0.00003) and it is concordant with other radiometric ages. Rb-Sr mineral isochron ages range from 84.4 to 97.3 Ma and these ages are relatively younger than the Rb-Sr whole-rock isochron age. The difference among radiometric ages may reflect the difference of the closure temperature in each isotopic system. The Tadamigawa Older-stage granites have SrI for Rb-Sr mineral isochron range from 0.7053 to 0.7061 and are very similar to that (0.70534) for Rb-Sr whole-rock isochron. These may suggest that the Tadamigawa Older-stage granites are generated from same parental magma. However, 87Sr/86Sr ratios of the leached apatite samples were 0.70544-0.70856 and are relatively higher than SrI obtained from the Rb-Sr mineral isochrons (0.7053-0.7061). This result

  7. Precambrian-Cambrian boundary in the Tal formation of Garhwal Lesser Himalaya : Rb-Sr age evidence from black shales underlying phosphorites

    International Nuclear Information System (INIS)

    Sharma, K.K.; Rameshwar Rao, D.; Azmi, R.J.; Gopalan, K.; Pantulu, G.V.C.

    1991-01-01

    The recently reported faunal evidence for placing the Precambrian-Cambrian boundary within the main phosphorite unit of the Chert-Phosphorite Member of the Tal Formation, Garhwal Lesser Himalaya, is supported by the present report of 626 ± 13 myr for the whole-rock Rb-Sr isochron age of the black shales directly underlying the phosphorite band. (author). 15 refs., 2 figs., 1 tab

  8. First record of 1.2 Ga quartz dioritic magmatism in the Archaean Yilgarn Craton, Western Australia, and its significance

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Y.; McNaughton, N.J.; Groves, D.I.; Dunphy, J.M. [University of Western Australia, Nedlands, WA (Australia). Centre for Strategic Mineral Deposits, Department of Geology and Geophysics

    1999-06-01

    Ion microprobe (SHRIMP) U-Pb zircon dating. Pb-Nd isotope tracer studies and major, trace and rare-earth element analyses have identified, for the first time. a Mesoproterozoic (1.2 Ga) quartz diorite intrusion in the central part of the Archaean Yilgarn Craton. Western Australia The quartz diorite is characterised by intergrowths of quartz and plagioclase, having low A/CNK (0 8). low K{sub 2}O (0.28 wt%), Ba (54 ppm), Rb (11 ppm), Sr (92 ppm), Pb (13 ppm), U (1.7 ppm) and Th (6 ppm) contents, high Nd (41 ppm), Sm (10.5 ppm), Zr (399 ppm). Nb (18.5 ppm). Y (57.5 ppm) and Sc (19 ppm) contents. a low Pb isotope two-stage model {mu} value (6.3), and a primitive initial e{sub Nd} value (+3.4) at 1.2 Ga. It is interpreted that the 1.2 Ga quartz diorite was derived from a predominantly mantle source, with minor crustal contamination, possibly from the surrounding Archaean monzogranites or their source region, during magma ascent. The age (1215 {+-} 11 Ma) of the intrusion overlaps with the timing of a major continental collisional orogeny in the Albany-Fraser Orogen, about 400km south, and is broadly coeval with the diamond-bearing Argyle lamproites in the east Kimberley Block. This study extends the history of granitoid magmatism in the central craton by more than 1.0 billion years (2.6 to 1.2 Ga), and has implications for isotopic data interpretations of tectonothermal events in the craton. Copyright (1999) Blackwell Science Pty Ltd 33 refs., 3 tabs., 6 figs.

  9. Application of specific extraction chromatographic methods to the Rb-Sr, Sm-Nd isotope study of geological samples: The Hombreiro-Santa Eulalia Granite (Lugo, NW Spain)

    OpenAIRE

    Santos Zalduegui, J. F.; Pin, C.; Aranguren, A.; Gil Ibarguchi, José Ignacio

    1996-01-01

    The analytical application to geological samples of three new chromatographic resins, TRU-Spec ®, Sr-Spec ® and LN-Spec ®) has been investigated. Seven samples of the Hombreiro massif (Lugo, NW Spain) have been studied, that yield a Rb-Sr age of 298 ±5 Ma (SrQ = 0.7086, MSWD = 7.64) for the magma crystallization. Sm-Nd data results for the same massif give eNd values dose to -2 at 300 Ma. This suggests that the origin of the magma might be related to the partial melting of immature sediments,...

  10. Possible two-stage /sup 87/Sr evolution in the Stockdale Rhyolite

    Energy Technology Data Exchange (ETDEWEB)

    Compston, W.; McDougall, I. (Australian National Univ., Canberra. Research School of Earth Sciences); Wyborn, D. (Department of Minerals and Energy, Canberra (Australia). Bureau of Mineral Resources)

    1982-12-01

    The Rb-Sr total-rock data for the Stockdale Rhyolite, of significance for the Palaeozoic time scale, are more scattered about a single-stage isochron than expected from experimental error. Two-stage /sup 87/Sr evolution for several of the samples is explored to explain this, as an alternative to variation in the initial /sup 87/Sr//sup 86/Sr which is customarily used in single-stage dating models. The deletion of certain samples having very high Rb/Sr removes most of the excess scatter and leads to an estimate of 430 +- 7 m.y. for the age of extrusion. There is a younger alignment of Rb-Sr data within each sampling site at 412 +- 7 m.y. We suggest that the Stockdale Rhyolite is at least 430 m.y. old, that its original range in Rb/Sr was smaller than now observed, and that it experienced a net loss in Sr during later hydrothermal alteration at ca. 412 m.y.

  11. History of the Pasamonte achondrite: relative susceptibility of the Sm-Nd, Rb-Sr, and U-Pb systems to metamorphic events

    International Nuclear Information System (INIS)

    Unruh, D.M.; Tatsumoto, M.; Nakamura, N.

    1977-01-01

    The Rb-Sr, Sm-Nd, and U-Pb systematics of the eucrite Pasamonte have been studied in order to investigate the relative susceptibility of the different systems to post-crystallization events and to determine the age and history of the meteorite. The Rb-Sr and 238 U- 206 Pb data of mineral separates do not define an isochron but the Sm-Nd data define an internal isochron which corresponds to the formation age of 4.58+-0.12 b.y. (10 9 years). The 207 Pb- 206 Pb data of mineral separates define an apparent age of 4.53+-0.03 b.y., however it is concluded that this age, while in agreement with the Sm-Nd age, is not strictly valid since the U-Pb data indicate at least three stages of evolution. The U-Pb data indicate that the parent body of the meteorite experienced brecciation shortly after the formation of the parent body surface (approximately 4.2-4.45 b.y. ago) and a recent disturbance (collision) 6+-30 m.y. ago. The latter age is within the range of cosmic ray exposure ages for achondrites. (Auth.)

  12. Rb-Sr and Nd-Sr isotope geochemistry and petrogenesis of the Misho Mountains mafic dikes (NW Iran

    Directory of Open Access Journals (Sweden)

    Maryam Ahankoub

    2017-02-01

    Full Text Available Introduction There are some theories about the Paleotethys event during the Paleozoic that have been proposed by geologists (Metcalfe, 2006. Some scientist offered some pieces of evidence about the northern margin of Gondwana (Zhu et al., 2010. The Paleotethys Ocean and Hercynian orogenic report first in Iran, have been Offered from the Morrow and Misho Mountain (Eftekharnejad, 1981. Misho Mountains is located between the north and south Misho faults and cause the formation of a positive flower structure (Moayyed and Hossainzade, 2011. There is theory about Misho southern fault as the best candidate of the Paleotethys suture zone (Moayyed and Hossainzade, 2011. Geochemistry and Sr –Nd isotopic data of the A2 granitic and Synite rocks of the East Misho, indicate that the magmatism post collision has occurred in the active continental margin by extensional zones of the following the closure of the Paleotethys (Ahankoub, 2012. Granite and syenite rocks have been cut by mafic dikes. Mafic dikes are often formed in extensional tectonic settings related to mantle plume or continental break –up (Zhu et al., 2009. In this paper, we use the geochemistry and Nd-Sr isotope data to determined petrogenesis, tectono-magmatic setting and age of Misho mafic dikes. Materials and methods After petrography study of 30 thin sections of mafic dike rocks, 8 samples were selected for whole-rock chemical analyses using ICP-MS and ICP-AES instruments by ACME Company in Vancouver, Canada. We prepared 6 sample For Sm-Nd and Rb-Sr analysis. Sr and Nd isotope ratios were measured with a thermal ionization mass spectrometer, VG Sector 54–30 at the Nagoya University. The isotope abundances of Rb, Sr, Nd, and Sm were measured by the ID method with a Finnigan MAT Thermoquad THQ thermal ionization quadrupole mass spectrometer at the Nagoya University. NBS987 and JNdi-1 were measured as natural Sr and Nd isotope ratio standards (Tanaka et al., 2000. Averages and 2σ errors

  13. A reconnaissance Rb-Sr, Sm-Nd, U-Pb, and K-Ar study of some host rocks and ore minerals in the West Shasta Cu- Zn district, California ( USA).

    Science.gov (United States)

    Kistler, R.W.; McKee, E.H.; Futa, K.; Peterman, Z.E.; Zartman, R.E.

    1985-01-01

    The Copley Greenstone, Balaklala Rhyolite, and Mule Mountain stock in the West Shasta Cu-Zn district, California, have Rb-Sr, Sm-Nd, U-Pb, and K-Ar systematics that indicate they are a cogenetic suite of ensimatic island-arc rocks about 400 Ma. Pervasive alteration and mineralization of these rocks, for the most part, was syngenetic and the major component of the mineralizing fluid was Devonian seawater. K-Ar ages of quarz-sericite concentrates from ore horizons and Rb-Sr systematics of a few rock and ore specimens record a later thermal and mineralizing event in the district of about 260 Ma. Contamination of some rocks with pelagic sediments is indicated by the Sm-Nd data. -Authors

  14. Metasomatism and the Weakening of Cratons: A Mechanism to Rift Cratons

    Science.gov (United States)

    Wenker, Stefanie; Beaumont, Christopher

    2016-04-01

    The preservation of cratons is a demonstration of their strength and resistance to deformation. However, several cratons are rifting now (e.g. Tanzania and North China Craton) or have rifted in the past (e.g. North Atlantic Craton). To explain this paradox, we suggest that widespread metasomatism of the originally cold depleted dehydrated craton mantle lithosphere root can act as a potential weakening mechanism. This process, particularly melt metasomatism, increases root density through a melt-peridotite reaction, and reduces root viscosity by increasing the temperature and rehydrating the cratonic mantle lithosphere. Using 2D numerical models, we model silicate-melt metasomatism and rehydration of cold cratonic mantle lithosphere that is positioned beside standard Phanerozoic lithosphere. The models are designed to investigate when a craton is sufficiently weakened to undergo rifting and is no longer protected by the initially weaker adjacent standard Phanerozoic lithosphere. Melt is added to specified layers in the cratonic mantle lithosphere at a uniform volumetric rate determined by the duration of metasomatism (3 Myr, 10 Myr or 30 Myr), until a total of ~30% by volume of melt has been added. During melt addition heat and mass are properly conserved and the density and volume increase by the respective amounts required by the reaction with the peridotite. No extensional boundary conditions are applied to the models during the metasomatism process. As expected, significant refertilization leads to removal and thinning of progressively more gravitationally unstable cratonic mantle lithosphere. We show that the duration of metasomatism dictates the final temperature in the cratonic upper mantle lithosphere. Consequently, when extensional boundary conditions are applied in our rifting tests in most cases the Phanerozoic lithosphere rifts. The craton rifts only in the models with the hottest cratonic upper mantle lithosphere. Our results indicate rifting of cratons

  15. Age of granitoids from the Kohut Veporic zone according to Rb-Sr isochrone analysis

    International Nuclear Information System (INIS)

    Cambel, B.; Bagdasaryan, G.P.; Gukasyan, R.K.; Dupej, J.

    1988-01-01

    Rb-Sr isochrone analyses of granitoid rocks from the southern part of the Veporic zone - the so-called Kohut zone - are presented. In this region, the Sinec (Rimavica) type of granitoids formerly considered to be Late Palaeozoic to Neoide, is found. The present isochrone research determines them as equivalents of granitoids of the Sihla type (387±27 m.y.). The Sinec (Rimavica) granite reaches an age of 392±5 m.y. This extended age must partly be attributed to additional processes which took place in the stage of retrograde alterations. The conclusions are of considerable importance in clarifying the metamorphic age and stratigraphy of the crystalline complex in the region of the southern Veporic zone. (author). 9 figs., 4 tabs., 38 refs

  16. Application of the Rb-Sr, Pb-Pb and Sm-Nd systems on the Salobe 3A polymetallic deposit, Carajas Mineral Province, Para, Brazil; Aplicacao dos sistemas Rb-Sr, Pb-Pb e Sm-Nd do deposito polimetalico do Salobo 3A, Provincia Mineral de Carajas, Para

    Energy Technology Data Exchange (ETDEWEB)

    Mellito, Katia Maria

    1998-07-01

    The Salobo 3A polymetallic Cu (Au-Mo-Ag) deposit, located in the northern part of the Carajas Mineral Province, Para, consists of a metavolcano-sedimentary sequence represented by iron formation, amphibolite, schist and quartzite of the Igarape Salobo Group. This rock sequence rest uncomformably on the gneissic basement of the Xingu Complex. The copper mineralization hosted by iron formation consists of bornite-chalcocite and bornite-chalcopyrite disseminations associated with magnetite. The geochronological data determined through the application of the Rb-Sr, Sm-Nd and Pb-Pb methods, contribute to characterize the complex evolution of both the geological setting and the cupriferous mineralization of the Salobo deposit. The 3.11-2.92 Ga interval (T{sub DM}, Sm-Nd, whole rock) represents the age of the igneous protholith of the gneiss. The {epsilon}{sub Nd} values calculated for the time of the gneiss formation (2859 Ma) vary between +1.02 and -1.08, and indicate a short period between the mantle-crust differentiation epoch and the gneiss formation. Moreover, the {epsilon}{sub Nd} parameter suggest a mantle source with late crustal contamination. The application of the leaching technique allows a gradual extraction of Pb at each leaching step and it was applied to chalcocite and magnetite. The 2762 {+-} 180 Ma and 2776 {+-} 240 Ma ages determined on those minerals are interpreted to be close to the epoch of the formation of the copper mineralization with Uu and Th enrichment and of the iron formation deposition, respectively, in a conventional setting. The leaching technique was also applied to tourmaline from gneiss and quartzite, and the age near to 2400 Ma was attributed to its formation. The random variability of the Pb isotope compositions of the tourmaline together with its petrographic characteristics suggest the boron source is not associated with the metassedimentary rocks of the Igarape Salobo Group. The Sm-Nd mineral isochron attributed to schists

  17. RB research nuclear reactor - Annual report for 1986, I - III

    International Nuclear Information System (INIS)

    Markovic, H.; Pesic, M.; Vranic, S.; Petronijevic, M.; Jevremovic, M.; Ilic, I.

    1987-01-01

    This report includes data concerning the RB reactor operation in 1986, state of the reactor components, data about the employed personnel and the database of experimental and other reactor related devices. It is made of 3 parts: Engineering description and operation of the RB reactor including dosimetry, reactor staff data and financial report; Reactor facility components and maintenance; RB reactor operation and utilization in 1986 [sr

  18. Recognition of the Kaweka Terrane in northern South Island, New Zealand : preliminary evidence from Rb-Sr metamorphic and U-Pb detrital zircon ages

    International Nuclear Information System (INIS)

    Adams, C.J.; Mortimer, N.; Campbell, H.J.; Griffin, W.L.

    2011-01-01

    Detrital zircon U-Pb ages and Rb-Sr metamorphic ages from low-grade Torlesse Supergroup metasedimentary rocks from North Canterbury and Marlborough provide preliminary evidence for a continuation of the Kaweka Terrane of the central North Island into the Torlesse Composite Terrane of the South Island. This would extend from the south side of the Wairau Fault in the upper Wairau River valley southwards to the Lake Tennyson and Lake Sumner areas, and as far as Hawarden. Rb-Sr ages indicate Jurassic metamorphism, 170±24 Ma, with initial 87 Sr/ 86 Sr ratios at that time 0.7073 ± 0.0007 i.e. similar to their North Island counterparts. These Kaweka Terrane rocks have detrital zircon ages that follow the distinctive pattern of the Torlesse rocks in general, i.e. substantial (>30%) Permian-Triassic and Precambrian-Early Palaeozoic groupings, but they also have minor youngest age components c. 175-165 Ma which constrain a maximum Early-Middle Jurassic depositional age. In detail, significant, older zircon components are Late Permian-Early Triassic (260-240 Ma) and Late Triassic (220-210 Ma), but the Precambrian-Early Palaeozoic detrital zircon ages are more scattered. The Kaweka Terrane thus forms a linear belt (c. 500 km) along the length of the Torlesse Composite Terrane in both North and South Islands. In the South Island it coincides with the Esk Head Belt, i.e. east of the Rakaia Terrane (Triassic-Late Permian) and west of the Pahau Terrane (Early Cretaceous-Late Jurassic). (author). 61 refs., 4 figs., 2 tabs.

  19. Rb-Sr and K-Ar age of globular phyllosilicates and biostratigraphy of the Riphean deposits of the Olenek Uplift (North Siberia)

    Science.gov (United States)

    Zaitseva, T. S.; Gorokhov, I. M.; Semikhatov, M. A.; Ivanovskaya, T. A.; Kuznetsov, A. B.; Dorzhieva, O. V.

    2017-11-01

    This work presents results of the complex mineralogical, geochemical, and isotope-geochronological investigation of globular dioctahedral 2: 1 phyllosilicates (GPS) of the illite-glauconite series from the Riphean sequences of the Olenek Uplift. It is established that GPS (glauconite, Al-glauconite, Fe-illite) in deposits of the Arymass, Debengda, and Khaipakh formations are represented by mixed-layer varieties of two types: (1) with relatively low (cell of minerals varies from 9.18 to 9.72 Å. The Rb-Sr age dating of GPS was first carried out in combination with the calculation of theoretical pattern of the cation distribution in the mineral structure and comparison of the calculation results obtained with the Mössbauer and IR spectroscopy data. This approach is based on the assumption that development and evolution of isotope systems in GPS are synchronous with the evolution of the crystalline structure of the mineral at various stages of the geological and geochemical history of the development of sedimentary units. Analysis of the obtained data allows us to state that the structural features of the Riphean GPS from the Olenek section reflect the early diagenetic stages of the formation of the minerals studied. The 87Sr/86Sr initial ratios in the studied sediments are consistent with the range of variations in this ratio in the Middle Riphean Ocean (0.7049-0.7061). The Rb-Sr and K-Ar ages of the GPS of the Arymass (1305 ± 8 and 1302 Ma, respectively), Debengda (1265 ± 12 and 1284 ± 22 Ma), and Khaipakh (1172 ± 18 and 1112 ± 24 Ma) formations in the Olenek Uplift section are close to the accumulation time of corresponding deposits and, correspondingly, have significance for stratigraphic correlations.

  20. Sm-Nd, Rb-Sr and K-Ar age constraints of the El Molle and Barroso plutons, western Sierra de San Luis, Argentina

    International Nuclear Information System (INIS)

    Sato, A.M.; Gonzalez, P.D; Petronilho, L.A; Llambias, E.J.; Varela, R; Basei, M.A.S

    2001-01-01

    Within the Early Paleozoic Famatinian orogeny of Southern Sierras Pampeanas (Sierra de San Luis and Sierra de Cordoba), the post-orogenic granitoids are characterized by circular intrusions. The published Rb-Sr and K-Ar ages from plutons in the Sierra de San Luis range between 408 and 320 Ma (see synthesis in Llambias et al., 1998). The El Molle and Barroso plutons (Sims et al., 1997; Gonzalez and Sato, 2000) are the two main exposures of a post-orogenic intrusive complex located in the western area of the Sierra de San Luis basement. They also exhibit an overall circular map view of almost 8 km in diameter, and are emplaced in a metamorphic complex developed through pre-Famatinian (Proterozoic? to Early Paleozoic) to Famatinian (Early Paleozoic) orogenies (Gonzalez and Llambias, 1998; von Gosen and Prozzi, 1998). We are carrying out isotopic datings of the El Molle and Barroso plutons in order to contribute to the understanding of the magmatic and metamorphic evolution of the final stages of the Famatinian orogenic cycle in the Sierra de San Luis. The first results of the Sm-Nd, Rb-Sr and K-Ar dates are here presented (au)

  1. Trace elements (Rb, Cs, Sr, Pb, Th, U) bioavailability potential and speciation in the Piracicaba river bottom sediments, Sao Paulo, Brazil

    International Nuclear Information System (INIS)

    Fernandes, Alexandre Martins; Mortatti, Jefferson; Oliveira, Helder de; Bibian, Joao Paulo Rambelli; Moraes, Graziela Meneghel de; Probst, Jean-Luc

    2007-01-01

    It was studied the bioavailability potential of Rb, Cs, Sr, Pb, Th and U and their chemical speciation in Piracicaba river bottom sediments. This river system crosses important agricultural and urban areas of Sao Paulo state, which groups about 3 million people and receives a large load of agricultural, industrial and domestic wastes. The procedure used to estimate trace elements bioavailability potential was related to a 7-step sequential chemical extraction. This scheme was designed to dissolved and separate sample chemical phases, which can be affected by changes in physical-chemical conditions; in the following order: water soluble, exchangeable, bound to carbonates or acid fraction, bound to Mn-oxides, bound to Fe-oxides and bound to organic matter. Trace element concentrations were determined by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) after each extraction step. With the used extraction procedure, it was possible to identify the fraction where some trace elements could be found in order to evaluate their bioavailability potential. Rb and Cs were particularly involved with the organic fraction, while Sr revealed to be associated mainly to the exchangeable fraction (clay minerals). Pb, Th and U were mainly bound to the residual and Fe-oxide fractions. (author)

  2. Neoarchean granite-greenstone belts and related ore mineralization in the North China Craton: An overview

    Directory of Open Access Journals (Sweden)

    Li Tang

    2018-05-01

    Full Text Available Tectonic processes involving amalgamations of microblocks along zones of ocean closure represented by granite-greenstone belts (GGB were fundamental in building the Earth's early continents. The crustal growth and cratonization of the North China Craton (NCC are correlated to the amalgamation of microblocks welded by 2.75–2.6 Ga and ∼2.5 Ga GGBs. The lithological assemblages in the GGBs are broadly represented by volcano-sedimentary sequences, subduction-collision related granitoids and bimodal volcanic rocks (basalt and dacite interlayered with minor komatiites and calc-alkalic volcanic rocks (basalt, andesite and felsic rock. The geochemical features of meta-basalts in the major GGBs of the NCC display affinity with N-MORB, E-MORB, OIB and calc-alkaline basalt, suggesting that the microblocks were separated by oceanic realm. The granitoid rocks display arc signature with enrichment of LILE (K, Rb, Sr, Ba and LREE, and depletion of HFSE (Nb, Ta, Th, U, Ti and HREE, and fall in the VAG field. The major mineralization includes Neoarchean BIF-type iron and VMS-type Cu-Zb deposits and these, together with the associated supracrustal rocks possibly formed in back-arc basins or arc-related oceanic slab subduction setting with or without input from mantle plumes. The 2.75–2.60 Ga TTG rocks, komatiites, meta-basalts and metasedimentary rocks in the Yanlingguan GGB are correlated to the upwelling mantle plume with eruption close to the continental margin within an ocean basin. The volcano-sedimentary rocks and granitoid rocks in the late Neoarchean GGBs display formation ages of 2.60–2.48 Ga, followed by metamorphism at 2.52–2.47 Ga, corresponding to a typical modern-style subduction-collision system operating at the dawn of Proterozoic. The late Neoarchean komatiite (Dongwufenzi GGB, sanukitoid (Dongwufenzi GGB and Western Shandong GGB, BIF (Zunhua GGB and VMS deposit (Hongtoushan-Qingyuan-Helong GGB have closer connection to a combined

  3. Investigation of the structural, electronic and optical properties of the cubic RbMF{sub 3} perovskites (M = Be, Mg, Ca, Sr and Ba) using modified Becke-Johnson exchange potential

    Energy Technology Data Exchange (ETDEWEB)

    Sandeep, E-mail: sndp.chettri@gmail.com [Department of Physics, Mizoram University, Aizawl, 796004 (India); Rai, D.P. [Department of Physics, Pachhunga University College, Mizoram University, 796001 (India); Shankar, A. [Department of Physics, University of North Bengal, Darjeeling, 734013 (India); Ghimire, M.P. [Condensed Matter Physics Research Center, Butwal-13, Rupandehi, Lumbini (Nepal); IFW-Dresden, Helmholtzstraße 20, D-01069, Dresden (Germany); Khenata, R. [Laboratoire de Physique Quantique de la Mati´ere et de Modélisation Mathématique LPQ3M, Université de Mascara, Mascara, 29000 (Algeria); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P. O. Box 2455, Riyadh, 11451 (Saudi Arabia); Syrotyuk, S.V. [Semiconductor Electronics Department, Lviv Polytechnic National University, Lviv, 79013 (Ukraine); Thapa, R.K. [Department of Physics, Mizoram University, Aizawl, 796004 (India)

    2017-05-01

    The structural, electronic and optical properties of the cubic RbMF{sub 3} perovskites (M = Be, Mg, Ca, Sr, Ba) have been investigated using the full-potential linearized augmented plane wave (FP-LAPW) method. The exchange and correlation potential was applied using the generalized gradient approximation for calculating the structural properties In addition, the modified Becke-Johnson (TB-mBJ) potential was used for calculating the electronic and optical properties. It was found that the lattice constant increases while the bulk modulus decreases with the change of cation (M) in going from Be to Ba in the RbMF{sub 3} perovskites (M = Be, Mg, Ca, Sr, Ba). The reflectivity and absorption properties were also studied using the mBJ method to understand the inter-band transitions and their possible applications in absorption devices in the UV-region. - Highlights: • Closer estimate of the band-gaps of RbMF{sub 3} with experimental results using GGA and mBJ results predicting them to be absorption devices and substrates for thin film growth. • The RbMF{sub 3} were also found to be potential candidate for in absorption devices in UV-region which were correlated to their calculated optical properties. • The materials are transparent, so may be used as substrates for thin film growth, for the optoelectric applications.

  4. Development of an on-line flow injection Sr/matrix separation method for accurate, high-throughput determination of Sr isotope ratios by multiple collector-inductively coupled plasma-mass spectrometry.

    Science.gov (United States)

    Galler, Patrick; Limbeck, Andreas; Boulyga, Sergei F; Stingeder, Gerhard; Hirata, Takafumi; Prohaska, Thomas

    2007-07-01

    This work introduces a newly developed on-line flow injection (FI) Sr/Rb separation method as an alternative to the common, manual Sr/matrix batch separation procedure, since total analysis time is often limited by sample preparation despite the fast rate of data acquisition possible by inductively coupled plasma-mass spectrometers (ICPMS). Separation columns containing approximately 100 muL of Sr-specific resin were used for on-line FI Sr/matrix separation with subsequent determination of (87)Sr/(86)Sr isotope ratios by multiple collector ICPMS. The occurrence of memory effects exhibited by the Sr-specific resin, a major restriction to the repetitive use of this costly material, could successfully be overcome. The method was fully validated by means of certified reference materials. A set of two biological and six geological Sr- and Rb-bearing samples was successfully characterized for its (87)Sr/(86)Sr isotope ratios with precisions of 0.01-0.04% 2 RSD (n = 5-10). Based on our measurements we suggest (87)Sr/(86)Sr isotope ratios of 0.713 15 +/- 0.000 16 (2 SD) and 0.709 31 +/- 0.000 06 (2 SD) for the NIST SRM 1400 bone ash and the NIST SRM 1486 bone meal, respectively. Measured (87)Sr/(86)Sr isotope ratios for five basalt samples are in excellent agreement with published data with deviations from the published value ranging from 0 to 0.03%. A mica sample with a Rb/Sr ratio of approximately 1 was successfully characterized for its (87)Sr/(86)Sr isotope signature to be 0.718 24 +/- 0.000 29 (2 SD) by the proposed method. Synthetic samples with Rb/Sr ratios of up to 10/1 could successfully be measured without significant interferences on mass 87, which would otherwise bias the accuracy and uncertainty of the obtained data.

  5. Study of Ne and Kr production in Mg, Al, Rb, Sr and Y targets by 0-180 MeV neutrons. Cosmochemical application

    International Nuclear Information System (INIS)

    Bertin, P.

    1989-07-01

    High sensitivity mass spectrometry technique has been used to measure production of noble gases Ne and Kr induced by 0-180 MeV neutrons in Mg, Al, Rb, Sr and Y targets. This experiment allowed us an evaluation of the implied excitation functions, in an energy range where no experimental data were available. These results have exhibited the importance of secondary neutrons induced in the interaction of cosmic rays with meteorites and moon surface [fr

  6. Erosion of the Alps: use of Rb-Sr isotopic data from molassic sediments to identify the ages of the metamorphism recorded by the eroded rocks; Erosion des Alpes: histoire metamorphique des roches erodees par l`analyse du couple Rb-Sr des sediments molassiques

    Energy Technology Data Exchange (ETDEWEB)

    Henry, P; Deloule, E [Centre National de la Recherche Scientifique (CNRS), 54 - Nancy (France). Centre de Recherches Petrographiques et Geochimiques; Michard, A [Aix-Marseille-3 Univ., 13 - Marseille (France)

    1994-06-01

    Rb-Sr isotopic data from Oligocene and Miocene peri-alpine molassic sediments allow us to identify the different periods for which the eroded rocks have or have not recorded an alpine metamorphism. The Chattian and the Burdigalian sediments result from the erosion of rocks for which the latest metamorphic event was variscan, while the Stampian, Aquitanian and ``Helvetian`` sediments show evidence for the erosion of rocks which have recorded alpine metamorphic events. The application of this method to old detrital sediments could permit determination of the ages of the tectonic events which occurred in the sediment source regions. (authors). 18 refs., 6 figs.

  7. Rb/Sr geochronology in whole rocks and minerals of the Cumaru granodiorite, Serra dos Gradaus, Para state, Brazil

    International Nuclear Information System (INIS)

    Lafon, J.M.; Scheller, T.; Pereira, E.D.; Macambira, J.B.

    1990-01-01

    The Cumaru granodiorite occurs in the Serra dos Gradaus region, southeastern part of the Metallogenic Province of Carajas, Para. Rb-Sr systematics have been provided in whole rocks and minerals for samples of the Cumaru granodiorite thus an age of 2543 ± 53 Ma, with an initial isotopic ratio of 0.70311 ± 34 (MSWD+1.87) was obtained for whole rocks samples. Taking in account that these rocks are not affected by metamorphism and/or deformation, we consider the age of 2543 ± 53 Ma as an emplacement age corresponding to the crystallization of the body. Such an age confirms the existence of a late Archaean plutonic event in the Serra dos Gradaus area and the interpretation of the Cumaru granodiorite as a contemporaneous and cogenetic body of the Juruena type granites (Ca. 2000 Ma old), as proposed previously, must be definitively abandoned. Therefore, Archaean ages for the greenstone belt sequence (Gradaus group) as well as for the Xingu complex in this area are also confirmed, although by indirect evidence. The age obtained implies that the latter represents an Archaean metamorphic basement in the Serra dos Gradaus region rather than the reworking of the late archaean granitics rocks during the Transmazonian orogenic event. The initial isotopic ratio of 0.70311 ± 34 is close to a mantellic or low time of crustal residence source material ratios at the end of Archaean times. Therefore, comparison with isotopic initial ratios of other granitic rocks which occur in the Rio Maria region identifies an evolution line with a Rb-Sr ratio of 0.25 for a crustal source material that would have separated from mantle about 2.8 Ga ago. (author)

  8. The initial 87Sr/86Sr ratios of the Kirwan Volcanics of Dronning Maud Land: Comparison with the Kirkpatrick Basalt, Transantarctic Mountains

    International Nuclear Information System (INIS)

    Faure, G.; Bowman, J.R.; Elliot, D.H.

    1979-01-01

    A series of lava flows from Mountain B (6 0 13.9'W, 74 0 06.9'S) of the Kirwan Escarpment in Dronning Maud Land, Antarctica, is composed of tholeiite basalts of Jurassic age. Their chemical compositions are similar to those of Jurassic basalts elsewhere in Dronning Maud Land but differ from those of the Kirkpatrick Basalt of the Transantarctic Mountains. The basalts on Mountain B contain 50.39% SiO 2 , 9.7 ppm Rb, 174.4 ppm Sr, have a Rb/Sr ratio of 0.057, and a K/Rb ratio of 417. Their average initial 87 Sr/ 86 Sr ratio is 0.7044 +- 0.0010 (1sigma) which suggests that the magma from which they formed could have been derived from the upper mantle without extensive contamination with 87 Sr and other elements. These results confirm earlier suggestions that the Jurassic basalts of Dronning Maud Land differ significantly from the Kirkpatrick Basalt and the Ferrar Dolerite of the Transantarctic Mountains. These differences in chemical and Sr-isotopic composition may be related to tectonic activity and magma formation during the break-up of Gondwanaland. (Auth.)

  9. The Rb/Sr ages for granitoids of the Middle Chukotka: a new approach to the geological history of the region

    International Nuclear Information System (INIS)

    Efremov, S.V.; Kozlov, V.D.; Sandimirova, G.P.

    2000-01-01

    For studying the history of geological evolution of the Middle Chukotka in the Mesozoic by the method of Rb-Sr dating the age of granitoids in the region was determined. It was ascertained that the granitoids have different genetic nature, their formation involving the most intensive tectonic restructuring. Magmatism was manifested in two stages. Formation of the first stage granitoids (126-144 mln. years) relates to orogenesis, while that of the second stage granitoids (∼ 80 mln. years) - to the process of the Chukotka folded region activation [ru

  10. A summary of Rb-Sr isotope studies in the Archean Hopedale Block and the adjacent proterozoic Makkovik subprovince, Labrador

    International Nuclear Information System (INIS)

    Grant, N.K.; Hickman, M.H.; Marzano, M.S.; Ermanovics, I.F.

    1983-01-01

    Rb-Sr isotope study of thirteen whole-rock suites of Archean and Proterozoic rocks from Hopedale block and Makkovik Subprovince shows that the crustal history began about 3115 Ma ago. We tentatively recognize younger crustal segments that formed 2920 Ma ago, from which Kanairktok intrusives were derived at 2832 +- 178 Ma. In Makkovik Subprovince the Island Harbour granites range in age from 1843 +- 90 to 1794 +- 71 Ma. These ages overlap with the 1847 +-87 Ma age for Kanairktok shear zone mylonites. The Island Harbour granodiorites from inland localities to the southwest are contaminated with Archean rocks in Makkovik Subprovince and their initial 87 Sr/ 86 ratios imply a crustal contribution to their source. In contrast, the Island Harbour granites of Striped Island were derived from a mantle source. The sills of Striped Island are 1635 +- 47 Ma old. An undeformed northeast trending Kikkertavak dolerite dyke from Hopedale block is 1206 +- 120 Ma

  11. Dating the Martian meteorite Zagami by the ⁸⁷Rb-⁸⁷Sr isochron method with a prototype in situ resonance ionization mass spectrometer.

    Science.gov (United States)

    Anderson, F Scott; Levine, Jonathan; Whitaker, Tom J

    2015-01-30

    The geologic history of the Solar System builds on an extensive record of impact flux models, crater counts, and ~270 kg of lunar samples analyzed in terrestrial laboratories. However, estimates of impactor flux may be biased by the fact that most of the dated Apollo samples were only tenuously connected to an assumed geologic context. Moreover, uncertainties in the modeled cratering rates are significant enough to lead to estimated errors for dates on Mars and the Moon of ~1 Ga. Given the great cost of sample return missions, combined with the need to sample multiple terrains on multiple planets, we have developed a prototype instrument that can be used for in situ dating to better constrain the age of planetary samples. We demonstrate the first use of laser ablation resonance ionization mass spectrometry for (87)Rb-(87)Sr isochron dating of geological specimens. The demands of accuracy and precision have required us to meet challenges including regulation of the ambient temperature, measurement of appropriate backgrounds, sufficient ablation laser intensity, avoidance of the defocusing effect of the plasma created by ablation pulses, and shielding of our detector from atoms and ions of other elements. To test whether we could meaningfully date planetary materials, we have analyzed a piece of the Martian meteorite Zagami. In each of four separate measurements we obtained (87)Rb-(87)Sr isochron ages for Zagami consistent with its published age, and, in both of two measurements that reached completion, we obtained better than 200 Ma precision. Combining all our data into a single isochron with 581 spot analyses gives an (87)Rb-(87)Sr age for this specimen of 360 ±90 Ma. Our analyses of the Zagami meteorite represent the first successful application of resonance ionization mass spectrometry to isochron geochronology. Furthermore, the technique is miniaturizable for spaceflight and in situ dating on other planetary bodies. © 2014 The Authors. Rapid Communications in

  12. Devonian alkaline magmatism in the northern North China Craton: Geochemistry, SHRIMP zircon U-Pb geochronology and Sr-Nd-Hf isotopes

    Directory of Open Access Journals (Sweden)

    Dingling Huang

    2017-01-01

    Full Text Available The Wulanhada pluton is among the rare suite of Devonian alkaline plutons occurring along the northern margin of the North China Craton (NCC. The intrusion is mainly composed of quartz-monzonite. Here we report zircon SHRIMP U-Pb data from this intrusion which shows emplacement age of ca. 381.5 Ma. The rock is metaluminous with high (Na2O + K2O values ranging from 8.46 to 9.66 wt.%. The REE patterns of the rocks do not show any Eu anomaly whereas the primitive-mantle-normalized spider diagram shows strong positive Sr and Ba anomalies. The Wulanhada rocks exhibit high initial values of (87Sr/86Srt = 0.70762–0.70809, low ɛNd(t = −12.76 to −12.15 values and negative values of ɛHf(t = −23.49 to −17.02 with small variations in (176Hf/177Hft (0.281873–0.282049. These geochemical features and quantitative isotopic modeling results suggest that the rocks might have been formed through the partial melting of Neoarchean basic rocks in the lower crust of the NCC. The Wulanhada rocks, together with the Devonian alkaline rocks and mafic-ultramafic complex from neighboring regions, constitute a post-collisional magmatic belt along the northern NCC.

  13. Synthesis of leucite, sanidine and a melt of sanidine at 930-10300C and 2 Kb: partition coefficients of Rb, Ca, Sr and Ba between these phases and hydrothermal solution of KCl. Geological utilizations

    International Nuclear Information System (INIS)

    Moreira, A.H.P.

    1988-01-01

    This work shows the results of hydrothermal experiments to determine the distribution coefficients of alcali and alcaline earth elements in trace concentrations between sanidine and liquids of same composition and between leucite and liquid. At 2 Kb pressure and 930 0 C for sanidine, 930 0 and 1030 0 C for leucite and 1030 0 C for a melt of sanidine composition the concentration of trace elements (TE) in the coexisting potassium bearing aqueous fluid phase was varied between 10 -1 to 10 -6 mole to one mol of K + . By use of radioactive tracers (Rb 86 , Ca 45 , Sr 85 , Ba 133 ) the concentrations in TE of the aqueous phase, the solids and melts has been determined. This indirect method will give a good aproximation of the behaviour of TE between a melt and crystallising solids. These aprotimations lead to following conclusions: a) during the crystallisation of leucite, this phase incorporates large quantities of Ba and Rb, depleting the residual melt in those elements. Sr and Ca, on the other hand are enriched in the residual melt. b) the crystallisation of sanidine depletes even more the residual melt in Ba, Sr shows similias behaviour, Rb and Ca, however, are enriched in the residual melt phase. (author) [pt

  14. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Trace, rare earth elements (REE), Rb-Sr, Sm-Nd and O isotope studies have been carried out on ultramafic (harzburgite and lherzolite) dykes belonging to the newer dolerite dyke swarms of eastern Indian craton. The dyke swarms were earlier considered to be the youngest mafic magmatic activity in this region having ages ...

  15. Suppression of the stellar enhancement factor and the reaction 85Rb(p,n)85Sr

    International Nuclear Information System (INIS)

    Rauscher, T.; Kiss, G. G.; Gyuerky, Gy.; Simon, A.; Fueloep, Zs.; Somorjai, E.

    2009-01-01

    It is shown that a Coulomb suppression of the stellar enhancement factor occurs in many endothermic reactions at and far from stability. Contrary to common assumptions, reaction measurements for astrophysics with minimal impact of stellar enhancement should be preferably performed for those reactions instead of their reverses, despite of their negative Q value. As a demonstration, the cross section of the astrophysically relevant 85 Rb(p,n) 85 Sr reaction has been measured by activation between 2.16≤E c.m. ≤3.96 MeV and the astrophysical reaction rates at p process temperatures for (p,n) as well as (n,p) are directly inferred from the data. Additionally, our results confirm a previously derived modification of a global optical proton potential. The presented arguments are also relevant for other α- and proton-induced reactions in the p, rp, and νp processes.

  16. Dating and source determination of volcanic rocks from Khunik area (South of Birjand, South Khorasan using Rb-Sr and Sm-Nd isotopes

    Directory of Open Access Journals (Sweden)

    Somayeh Samiee

    2016-12-01

    Full Text Available The Khunik area is located in the south of Birjand, Khorasan province, in the eastern margin of Lut block. Tertiary volcanic rocks have andesite to trachy-andesite composition. Dating analyzing by Rb-Sr method on plagioclase and hornblende as well as whole-rock isochron method was performed on pyroxene-hornblende andesite rock unit. On this basis the emplacement age is Upper Paleocene (58±11 Ma. These rocks have initial 87Sr/86Sr and εNd 0.7046-0.7049 and 2.16-3.12, respectively. According to isotopic data, volcanic rocks originated from depleted mantle and have the least crust contamination while it was fractionated. Geochemically, Khunik volcanic rocks have features typical of calk-alkaline to shoshonite and are metaluminous. Enrichment in LILEs and typical negative anomalies of Nb and Ti are evidences that the volcanic rocks formed in a subduction zone and active continental margin. Modeling suggests that these rocks were derived dominantly from 1–5% partial melting of a mainly spinel garnet lherzolite mantle source that is metasomatized by slab-derived fluid.

  17. Experimental techniques applied at the RB reactor

    International Nuclear Information System (INIS)

    Markovic, H.; Takac, S.; Sotic, O.; Dimitrijevic, Z.

    1979-12-01

    This paper contains a brief description of research and operations at the RB reactor which are concerned with experiments and results of measuring typical reactor parameters, neutron characteristics as well as parameters related to reactor operation and utilization. Annex contains a list of relevant original papers and publications [sr

  18. Kimberlite emplacement time and duration of kimberlite magmatism in the Zimnii Bereg diamond-diferrous district, Arkhangelsk Region: Rb-Sr age of kimberlite sills, Mela River

    International Nuclear Information System (INIS)

    Pervov, V.A.; Larchenko, V.A.; Minchenko, G.V.; Stepanov, V.P.; Bogomolov, E.S.; Levskij, L.K.; Sergeev, S.A.

    2006-01-01

    The Rb-Sr isotope data for kimberlites and carbonate-rich sills of the Mela River were obtained for identifying the age and duration of magmatism in the Zimnii Bereg district of the Archangelsk region. It is shown that estimated age of the kimberlite (366.4 mln. years) falls in the age range corresponding to the main phase of alkaline magmatism in the Kola Peninsula (410-362 mln. years) [ru

  19. Rb-Sr geochronolgy of the Jervois Range area in the eastern part of the Arunta Block, NT

    International Nuclear Information System (INIS)

    Black, L.P.

    1980-01-01

    New Rb-Sr isotopic data are presented for the Jervois Range area in the eastern part of the Arunta Block. The post-metamorphic Jinka and Jervois Granites yield an age of about 1750 m.y. An alaskitic granite is dated at about 1460 m.y. Pegmatite formation occurred about 1660 m.y. ago. Mineral ages are generally younger than total-rock ages, but no values significantly less than that of the alaskitic granite were found. This means that the Alice Springs Orogeny, which extensively reset large areas of the Arunta Block to the west, did not effect the Jervois area. In this and other geochronological comparisons, the Jervois area seems more akin to the rocks of the Tennant Creek Block, 400 km to the northwest, than to those of the Arunta Block

  20. Investigation of the s-process branch-point nucleus {sup 86}Rb at HIγS

    Energy Technology Data Exchange (ETDEWEB)

    Erbacher, Philipp; Glorius, Jan; Reifarth, Rene; Sonnabend, Kerstin [Goethe Universitaet Frankfurt am Main (Germany); Isaak, Johann; Loeher, Bastian; Savran, Deniz [GSI Helmholzzentrum fuer Schwerionenforschung (Germany); Tornow, Werner [Duke University (United States)

    2016-07-01

    The branch-point nucleus {sup 86}Rb determines the isotopic abundance ratio {sup 86}Sr/{sup 87}Sr in s-process nucleosynthesis. Thus, stellar parameters such as temperature and neutron density and their evolution in time as simulated by modern s-process network calculations can be constrained by a comparison of the calculated isotopic ratio with the one observed in SiC meteoritic grains. To this end, the radiative neutron-capture cross section of the unstable isotope {sup 86}Rb has to be known with sufficient accuracy. Since the short half-life of {sup 86}Rb prohibits the direct measurement, the nuclear-physics input to a calculation of the cross section has to be measured. For this reason, the γ-ray strength function of {sup 87}Rb was measured using the γ{sup 3} setup at the High Intensity γ-ray Source facility at TUNL in Durham, USA. First experimental results are presented.

  1. Precision flow-controlled Rb-82 generator for bolus or constant-infusion studies of the heart and brain

    International Nuclear Information System (INIS)

    Yano, Y.; Cahoon, J.L.; Budinger, T.F.

    1981-01-01

    A precision flow-controlled rubidium-82 generator has been constructed to deliver 76-sec Rb-82 at either fast or slow flow rates for bolus or constant-infusion studies. A stepping motor drive is interfaced to a microprocessor for pulsed control of flow rate to deliver the saline eluant solution from a large-volume (150 ml) machined pumping syringe through an alumina column that retains the 25-day Sr-82 parent. The generator system delivers 70-90% of the maximum Rb-82 activity in a 20-25 ml bolus elution of 2% NaCl. The Sr-82/Sr-85 breakthrough is 10 -7 - 10 -6 . Both yield and breakthrough are functions of column length and flow rate. Six separate Sr-82 loadings of the generator were evaluated over a period of nearly 2 yr in studies of myocardial blood perfusion and permeability changes in the blood-brain barrier. Sterility and apyrogenicity of the Rb-82 eluate were maintained during multiple elutions and long-term use of 3-4 mo for each generator loading

  2. Potential of Sr isotopic analysis in ceramic provenance studies: Characterisation of Chinese stonewares

    Science.gov (United States)

    Li, Bao-Ping; Zhao, Jian-Xin; Greig, Alan; Collerson, Kenneth D.; Zhuo, Zhen-Xi; Feng, Yue-Xin

    2005-11-01

    We compare the trace element and Sr isotopic compositions of stoneware bodies made in Yaozhou and Jizhou to characterise these Chinese archaeological ceramics and examine the potential of Sr isotopes in provenance studies. Element concentrations determined by ICP-MS achieve distinct characterisation for Jizhou samples due to their restricted variation, yet had limited success with Yaozhou wares because of their large variability. In contrast, 87Sr/86Sr ratios in Yaozhou samples have a very small variation and are all significantly lower than those of Jizhou samples, which show a large variation and cannot be well characterised with Sr isotopes. Geochemical interpretation reveals that 87Sr/86Sr ratios will have greater potential to characterise ceramics made of low Rb/Sr materials such as kaolin clay, yet will show larger variations in ceramics made of high Rb/Sr materials such as porcelain stone.

  3. Potential of Sr isotopic analysis in ceramic provenance studies: Characterisation of Chinese stonewares

    International Nuclear Information System (INIS)

    Li Baoping; Zhao Jianxin; Greig, Alan; Collerson, Kenneth D.; Zhuo Zhenxi; Feng Yuexin

    2005-01-01

    We compare the trace element and Sr isotopic compositions of stoneware bodies made in Yaozhou and Jizhou to characterise these Chinese archaeological ceramics and examine the potential of Sr isotopes in provenance studies. Element concentrations determined by ICP-MS achieve distinct characterisation for Jizhou samples due to their restricted variation, yet had limited success with Yaozhou wares because of their large variability. In contrast, 87 Sr/ 86 Sr ratios in Yaozhou samples have a very small variation and are all significantly lower than those of Jizhou samples, which show a large variation and cannot be well characterised with Sr isotopes. Geochemical interpretation reveals that 87 Sr/ 86 Sr ratios will have greater potential to characterise ceramics made of low Rb/Sr materials such as kaolin clay, yet will show larger variations in ceramics made of high Rb/Sr materials such as porcelain stone

  4. Decay studies of Sr isotpes with high resolution and total absorption techniques

    CERN Document Server

    Perez-Cerdan, Ana-Belen

    2012-04-03

    High Resolution measurements The beta/EC decay of 77,78Sr and 76,78Rb have been studied in this work. Measurements were carried out of the energies and intensities of the emitted gamma-rays and conversion electrons as well as gamma-gamma and gamma-X-ray coincidences in the decays of 77,78Sr, which have extended our knowledge of their decay schemes including spin and parity assignments to the levels populated in the daughter nucleus, 77Rb and 78Rb respectively. For the decay of 78Sr, 16 new levels and 44 new gamma-ray transitions have been identified. The very much improved experimental knowledge of the 78Rb levels populated in the decay and the strong link between the parent and the daughter states has allowed us to infer some possible level configurations by comparison with HF+BCS calculations using the SG2 Skyrme force. For the decay of 77Sr, 9 new levels and 15 new gamma-ray transitions have been identified. The levels in the low energy part of the level scheme have been discussed in terms of HF+BCS+QRPA c...

  5. Synthesis, structure, and electrical conductivity of A'[A(sub 2)B(sub 3)O(sub 10)] (A'=Rb, Cs A=Sr, Ba; B=Nb, Ta)

    International Nuclear Information System (INIS)

    Thangadurai, Venkataraman; Schmid-Beurmann, Peter; Weppner, Werner

    2001-01-01

    New members of Dion-Jacobson (D-J)-type layered perovskites of the general formula A'[A(sub 2)B(sub 3)O(sub 10)] (A'=Rb, Cs; A=Sr, Ba; B=Nb, Ta) were prepared by solid-state reactions between the metal oxides, nitrates, and carbonates under specific conditions. The crystal structures were determined using powder X-ray diffraction data in combination with Rietveld analysis. The c-axis lattice parameter increases as the size of the alkaline earth ion increases. Both Sr and Ba compounds crystallize in a tetragonal cell, while the corresponding Ca compounds crystallize in an orthorhombic cell. The electrical conductivity of the layered perovskites was determined using AC impedance analysis and DC methods. Among the compounds with the same alkali ion and different alkaline earth ions, the Ca compound exhibits a higher electrical conductivity than the corresponding Sr and Ba compounds. DC measurements reveal that the layered perovskites exhibit both ionic and electronic conduction

  6. Measurement of strontium isotope ratio in nitric acid extract of peanut testa by ICP-Q-MS after removal of Rb by extraction with pure water.

    Science.gov (United States)

    Zhu, Yanbei; Hioki, Akiharu; Chiba, Koichi

    2014-02-01

    The difference in the distributions of Sr and Rb in peanut seeds was utilized to develop a precise method for Sr isotope ratio measurement by inductively coupled plasma quadruple mass spectrometry (ICP-Q-MS). The testa instead of the whole peanut seed was selected as the sample because apparent enrichment of Sr in comparison to Rb was found in the testa. Furthermore, Rb in the testa was removed by pure water extraction with the aid of sonication to remove the isobaric interference in Sr isotope ratio measurement. The testa taken from one peanut seed was treated as one sample for the analysis. After optimization of the operating conditions, pure water (10 mL for each sample) extraction in 30 min with sonication was able to remove over 95% of Rb in the testa, while after the Rb removal Sr could be completely extracted using 10 mL of 0.3 mol L(-1) HNO3 for each sample. The integration time in ICP-Q-MS measurement was optimized to achieve a lower measurement uncertainty in a shorter time; the results showed that 1s was required and enough for the precise measurement of Sr isotope ratios giving a relative standard uncertainty (n=10) of ca. 0.1%. The present method was applied to peanut seeds grown in Japan, China, USA, India, and South Africa. © 2013 Published by Elsevier B.V.

  7. How to make a craton

    Science.gov (United States)

    Lee, C.; Chin, E. J.; Erdman, M.; Gaschnig, R. M.; Lederer, G. W.; Savage, P. S.; Zhong, S.; Zincone, S.

    2013-12-01

    Most Archean cratons are underlain by long-lived 200-300 km thick thermal boundary layers, significantly thicker than oceanic boundary layers, which eventually subduct. The longevity of cratons is perplexing because cold thermal boundary layers should be gravitationally unstable or should thermally erode with time. However, it is agreed that thermal contraction of the cratonic root is compensated by intrinsic compositional buoyancy due to extreme melt depletion. This melt depletion is also thought to have dehydrated the peridotitic residue, strengthening the cratonic mantle, making it resistant to thermo-mechanical erosion. Exactly how cratonic mantle arrives at this chemically buoyant and dehydrated state is unknown. Possible scenarios include formation by melting within a large plume head, accretion of oceanic lithosphere, and accretion of sub-arc mantle. The high degrees of melting would seem to imply formation in hot plume heads, but low Al and heavy rare earth element contents suggest formation in the spinel stability field, implying formation at shallower depths than their current equilibration pressures. We present a new thermobarometer designed to estimate the average melting pressures and temperatures of residual peridotites using whole rock major element compositions. We find that the average melting pressures and temperatures of cratonic peridotites range between 3-4 GPa and 1600 °C. If cratonic peridotites melted via adiabatic decompression, these average pressures represent maximum bounds on the final pressures of melt extraction. Currently, cratonic peridotites derive from 4-7 GPa, implying that the building blocks of peridotites experienced an increase of 1-3 GPa, equivalent to 30-90 km of overburden. Our results thus imply that cratonic mantle most likely formed by tectonic thickening of oceanic or arc lithospheres. But because both arc and oceanic lithospheres might be expected to be wet due to hydrous flux melting and serpentinization

  8. Kr-Ar and Rb-Sr dating and the genesis of tungsten at the Clea tungsten skarn property, Selwyn Mountains, Yukon Territory

    International Nuclear Information System (INIS)

    Godwin, C.I.; Armstrong, R.L.; Tompson, K.M.

    1980-01-01

    Tungsten skarn deposits on the Clea property in the Selwyn Mountains, Y.T., are related genetically to a quartz monzonite stock, about 500 metres in diameter at the surface. Lower Paleozoic sedimentary rocks are metamorphosed for a distance of 3 km from the stock. Tugnsten-bearing skarn mineralization within the altered sedimentary rocks is of two types: sulphide-rich pods and calc-silicate beds. The most significant sheelite concentration is in calc-silicate beds near or adjacent to the quartz monzonite stock. Discordant K-Ar and Rb-Sr isotopic dates indicate that the stock is probably of early Late Cretaceous age, 94 Ma or slightly older, and that it cooled slowly. High initial 87 Sr/ 86 Sr ratios and disequilibrium relationships between K-feldspar phenocrysts and groundmass minerals in the porphyritic phase of the granite rock, and between different granite rock specimens, indicate contamination of crystallizing magma by old sialic continental crust which extends westward under the Selwyn Basin. This study is significant to regional tungsten exploration. Granite rocks associated with tungsten deposits, in this part of the Canadian Cordillera at least, appear to have specific isotope characteristics that indicate they were generated at a specific time and in a particular way. (auth)

  9. Os-Hf-Sr-Nd isotope and PGE systematics of spinel peridotite xenoliths from Tok, SE Siberian craton: Effects of pervasive metasomatism in shallow refractory mantle

    Science.gov (United States)

    Ionov, Dmitri A.; Shirey, Steven B.; Weis, Dominique; Brügmann, Gerhard

    2006-01-01

    Os-Hf-Sr-Nd isotopes and PGE were determined in peridotite xenoliths carried to the surface by Quaternary alkali basaltic magmas in the Tokinsky Stanovik Range on the Aldan shield. These data constrain the timing and nature of partial melting and metasomatism in the lithospheric mantle beneath SE Siberian craton. The xenoliths range from the rare fertile spinel lherzolites to the more abundant, strongly metasomatised olivine-rich (70-84%) rocks. Hf-Sr-Nd isotope compositions of the xenoliths are mainly within the fields of oceanic basalts. Most metasomatised xenoliths have lower 143Nd / 144Nd and 176Hf / 177Hf and higher 87Sr / 86Sr than the host basalts indicating that the metasomatism is older and has distinct sources. A few xenoliths have elevated 176Hf / 177Hf (up to 0.2838) and plot above the Hf-Nd mantle array defined by oceanic basalts. 187Os / 188Os in the poorly metasomatised, fertile to moderately refractory (Al2O3 ≥ 1.6%) Tok peridotites range from 0.1156 to 0.1282, with oldest rhenium depletion ages being about 2 Ga. The 187Os / 188Os in these rocks show good correlations with partial melting indices (e.g. Al2O3, modal cpx); the intercept of the Al-187Os / 188Os correlation with lowest Al2O3 estimates for melting residues (∼0.3-0.5%) has a 187Os / 188Os of ∼0.109 suggesting that these peridotites may have experienced melt extraction as early as 2.8 Gy ago. 187Os / 188Os in the strongly metasomatised, olivine-rich xenoliths (0.6-1.3% Al2O3) ranges from 0.1164 to 0.1275 and shows no apparent links to modal or chemical compositions. Convex-upward REE patterns and high abundances of heavy to middle REE in these refractory rocks indicate equilibration with evolved silicate melts at high melt / rock ratios, which may have also variably elevated their 187Os / 188Os. This inference is supported by enrichments in Pd and Pt on chondrite-normalised PGE abundance patterns in some of the rocks. The melt extraction ages for the Tok suite of 2.0 to 2.8 Ga are

  10. Potential of Sr isotopic analysis in ceramic provenance studies: Characterisation of Chinese stonewares

    Energy Technology Data Exchange (ETDEWEB)

    Li Baoping [Advanced Centre for Queensland University Isotope Research Excellence (ACQUIRE), University of Queensland, Brisbane, Qld 4072 (Australia)]. E-mail: b.li@uq.edu.au; Zhao Jianxin [Advanced Centre for Queensland University Isotope Research Excellence (ACQUIRE), University of Queensland, Brisbane, Qld 4072 (Australia); Greig, Alan [Advanced Centre for Queensland University Isotope Research Excellence (ACQUIRE), University of Queensland, Brisbane, Qld 4072 (Australia); Collerson, Kenneth D. [Advanced Centre for Queensland University Isotope Research Excellence (ACQUIRE), University of Queensland, Brisbane, Qld 4072 (Australia); Zhuo Zhenxi [Shaanxi Provincial Institute of Archaeology, Xi' an 710054 (China); Feng Yuexin [Advanced Centre for Queensland University Isotope Research Excellence (ACQUIRE), University of Queensland, Brisbane, Qld 4072 (Australia)

    2005-11-15

    We compare the trace element and Sr isotopic compositions of stoneware bodies made in Yaozhou and Jizhou to characterise these Chinese archaeological ceramics and examine the potential of Sr isotopes in provenance studies. Element concentrations determined by ICP-MS achieve distinct characterisation for Jizhou samples due to their restricted variation, yet had limited success with Yaozhou wares because of their large variability. In contrast, {sup 87}Sr/{sup 86}Sr ratios in Yaozhou samples have a very small variation and are all significantly lower than those of Jizhou samples, which show a large variation and cannot be well characterised with Sr isotopes. Geochemical interpretation reveals that {sup 87}Sr/{sup 86}Sr ratios will have greater potential to characterise ceramics made of low Rb/Sr materials such as kaolin clay, yet will show larger variations in ceramics made of high Rb/Sr materials such as porcelain stone.

  11. Water in the Cratonic Mantle: Insights from FTIR Data on Lac De Gras Xenoliths (Slave Craton, Canada)

    Science.gov (United States)

    Peslier, Anne H.; Brandon, Alan D.; Schaffer, Lillian Aurora; O'Reilly, Suzanne Yvette; Griffin, William L.; Morris, Richard V.; Graff, Trevor G.; Agresti, David G.

    2014-01-01

    The mantle lithosphere beneath the cratonic part of continents is the deepest (> 200 km) and oldest (>2-3 Ga) on Earth, remaining a conundrum as to how these cratonic roots could have resisted delamination by asthenospheric convection over time. Water, or trace H incorporated in mineral defects, could be a key player in the evolution of continental lithosphere because it influences melting and rheology of the mantle. Mantle xenoliths from the Lac de Gras kimberlite in the Slave craton were analyzed by FTIR. The cratonic mantle beneath Lac de Gras is stratified with shallow (water contents extending to higher values than those from the shallow ones. The FTIR spectra of olivines from the shallow samples have more prominent Group II OH bands compared to the olivines from the deep samples, consistent with a more oxidized mantle environment. The range of olivine water content is similar to that observed in Kaapvaal craton peridotites at the same depths (129-184 km) but does not extend to as high values as those from Udachnaya (Siberian craton). The Slave, Kaapvaal and Siberian cratons will be compared in terms of water content distribution, controls and role in cratonic root longevity.

  12. Isotopic characteristics (Nd and Sr) of the intrusive plutonism at the northwestern Amazonian Craton, Venezuela, and implications for the Paleoproterozoic evolution

    International Nuclear Information System (INIS)

    Teixeira, Wilson; Tassinari, Colombro Celso G.; Mondin, M.

    2002-01-01

    Nd and Sr analyses were performed on selected granitoid plutons that intrude Archean and Paleoproterozoic domains of the Guyana shield (Venezuela). The isotopic signatures of these plutons together with the geochronologic background of the country rocks are used to constrain their magma genesis and tectonic setting within the Paleoproterozoic evolutions of mobile belts (Maroni-Itacaiunas and Ventuari-Tapajos provinces) of the Amazonian Craton. The Encrucijada Suite (2187 +- 94 Ma), which intrudes Archean rocks of the Imataca Complex, originated predominantly from partial melt of this crust, as supported by negative epsilon Nd(2.1Ga ) values (-2.2 to - 4.9) and T DM ages between 2.82 and 2.49 Ga. Conversely, the plutons from the Supamo Complex (2230 - 2050 Ma) and Cuchivero Group (1980 - 1830 Ma), occurring within the adjoining Paleoproterozoic provinces, are juvenile in nature (derived from roughly contemporary protoliths). These bodies display T DM ages between 2.13 and 2.22 Ga, as well as positive epsilon Nd(2.1Ga ) values (+0.74 to + 3.05). Isotopic correlation diagrams 143 Nd/144 Nd vs. 147 Sm/144 Nd and 143 Nd/144 Nd vs. time) plotted together with the plutonic rocks and Imataca Complex rocks were evaluated taking into account the geologic background of the NW part of the Amazonian Craton. Interpretation of these isotopic data supports the idea of tectonic juxtaposition between the Imataca Complex and the Maroni-Itacaiunas province during the Transamazonian orogeny (2.25 - 2.05 Ga). On the other hand, the Cuchivero Group plutons have a contrasting isotopic signature compared to the other Paleoproterozoic plutonic rocks. This is consistent with the existence of a tectonic boundary between the Maroni-Itacaiunas and the Ventuari-Tapajos province in the late Paleoproterozoic. (author)

  13. Identification of thermotectonics events by 40Ar/39Ar methodology, in Jauru, Pontes e Lacerda and Rio Alegre Terrane - southwest portion of Amazon Craton

    International Nuclear Information System (INIS)

    Paulo, Valeria Guimaraes de

    2005-01-01

    The southwest portion of Amazon Craton, subject of these work, correspond to the southwest region of Mato Grosso State and is inserted on Rio Negro-Juruena, Rondoniana-San Ignacio and Sunsas-Aguapei geochronologic Provinces. This region is surrounded by three big terranes: Jauru, Pontes e Lacerda and Rio Alegre. The main aim of this study is to use the ages of termochronologic events obtained by 40 Ar/ 39 Ar methodology, including data of literature, to contribute with the study of the geotectonic evolution on this region. Twenty samples were analyzed and 40 Ar/ 39 Ar ages found for the Jauru Terrane vary of 1539 ± 3 Ma to 1338 ± 3 Ma, for the Pontes e Lacerda Terrane the interval obtained was of 946,1 ± 0,8 Ma to 890 ± 2 Ma and for Rio Alegre Terrane the ages are between 1407 ± 3 Ma to 1321 ± 2 Ma. U/Pb, Rb/Sr and Sm/Nd data from previous works, together with 40 Ar/ 39 Ar results allowed to obtain cooling average rates to each terrane. The Jauru Terrane units cooling age is equivalent to 1,52 Ga. The cooling average rates found to Alto Jauru Greenstone belt rocks is 2,4 deg C - 1,0 Ma and to Magmatic Arc Cachoeirinha is 10,8 deg C - 1,0 Ma. Stabilization age obtained for Pontes and Lacerda Terrane is about 900 Ma coherent with the cooling age of the Sunsas Aguapei Event (1,0 - 0,9 Ga) and cooling average rates calculate were the lower, equivalent to 1,0 deg C - 1,0 Ma. Cooling age found in Rio Alegre Terrane was 1,35 Ga, possibility correspond to collision age these terrane with Amazonian protoCraton and cooling average rates of 5,0 deg C - 1,0 Ma. Finally, younger age found of 900 Ma, coherent to the Sunsas - Aguapei Event, probably represent the last regional event that affected these rocks, characterizing the stabilization period of the southwest portion of Amazon Craton. (author)

  14. Acaiaca Granulite Complex, MG: age, petrogenesis and tectonics implications

    International Nuclear Information System (INIS)

    Teixeira, W.; Kawashita, K.; Evangelista, H.J.; Taylor, P.N.

    1987-01-01

    Rb-SR and Pb-Pb geochronological work has been carried out on rocks from the Acaiaca granulite complex (mainly pyribolites, piriclasites and plagiogranulites) in Minas Gerais state. The results are interpreted together with petrographical and geochemical data, in order to delineate the evolution of those rocks. The Rb-Pb whole rock isochrons are concordant in age (around 2.0 b.y.) and they define the Transamazonian orogeny as the main event in the investigated area. In addition, the Sr and Pb evidences suggest a strong reworking of prior continental crust at that time. In turn, the estimation of P-T conditions of regional metamorphism based on geo thermo barometric calculations and on petrology resulted in T ≅ 700-900 O C and P tot =5,6-8 and 8-10 Kbar. The whole group of data is coherent with the development of is Transamazonian mobile zone of ensialic character, along the eastern border of an Archaean fragment. Within an area considered cratonic during the Upper Proterozoic. A model of evolution of the Sao Francisco Craton as well the differences between the Archaean and early Proterozoic domains are discussed. (M.V.M.)

  15. Continental lithospheric evolution: Constraints from the geochemistry of felsic volcanic rocks in the Dharwar Craton, India

    Science.gov (United States)

    Manikyamba, C.; Ganguly, Sohini; Saha, Abhishek; Santosh, M.; Rajanikanta Singh, M.; Subba Rao, D. V.

    2014-12-01

    Felsic magmatism associated with ocean-ocean and ocean-continent subduction processes provide important evidence for distinct episodes of crust-generation and continental lithospheric evolution. Rhyolites constitute an integral component of the tholeiitic to calc-alkaline basalt-andesite-dacite-rhyolite (BADR) association and contribute to crustal growth processes at convergent plate margins. The evolution of the Dharwar Craton of southern peninsular India during Meso- to Neoarchean times was marked by extensive development of greenstone belts. These granite-greenstone terranes have distinct volcano-sedimentary associations consistent with their geodynamic setting. The present study deals with geochemistry of rhyolites from the Chitradurga-Shimoga greenstone belts of western (WDC) and the Gadwal-Kadiri greenstone belts of eastern (EDC) sectors of Dharwar Craton to compare and evaluate their petrogenesis and geodynamic setting and their control on the continental lithospheric evolution of the Dharwar Craton. At a similar range of SiO2, Al2O3, Fe2O3, the rhyolites of WDC are more potassic, whereas the EDC rhyolites are more sodic and less magnesian with slight increase in TiO2. Minor increase in MgO content of WDC rhyolites reflects their ferromagnesian trace elements which are comparatively lower in the rhyolites of EDC. The relative enrichment in LILE (K, Rb) and depletion in HFSE (Nb, Ta, Zr, Hf) marked by negative Nb-Ta, Zr-Hf and Ti anomalies endorse the convergent margin processes for the generation of rhyolites of both the sectors of Dharwar Craton. The high silica potassic rhyolites of Shimoga and Chitradurga greenstone belts of WDC showing prominent negative Eu and Ti anomalies, flat HREE patterns correspond to Type 3 rhyolites and clearly point towards their generation and emplacement in an active continental margin environment. The geochemical characteristics of Gadwal and Kadiri rhyolites from eastern Dharwar Craton marked by aluminous compositions with

  16. Contribution to the geologic evolution from the Eastern part of Central Amazonia Province by Rb-Sr geochronology from the Carajas Mineral Province and the Sao Felix do Xingu region, Para State

    International Nuclear Information System (INIS)

    Pereira, Edilea Dutra.

    1992-01-01

    This work deals with a Rb/Sr geochronological study carried on granitoids and granulites of the Carajas Mineral Province (Rio Maria, Serra dos Gradaus and Serra do Pium regions) and Sao Felix do Xingu regions. The Manelao and Ourilandia granitoids of the Sao Felix do Xingu region are associated with the greenstone terrains of the Tucuma Group, and yield an age of 2749 ± 24 Ma with an initial ratio of 0.07028 ± 19, and 2677 ± 50 Ma with an initial ratio of 0.07016 ± 22, respectively. In the Rio Maria region, an age of 2541 ± 74 Ma with an initial ratio of 0.7104 ± 343 was obtained on the Mata Surrao Granite located near the Marajoara Village. This age confirms an archaean monzogranitic magmatism in this region. In the Gradaus area, the Cumaru Granodiorite give an mineral age of 2577 ± 27 Ma similar to the age obtained by whole rock method. Finally, Rb/Sr ages were obtained from granulitic rocks of the Pium Complex located at the Serra do Pium and near the Catete River. Samples of the Serra do Pium yielded ages of 2325 ± 71 Ma (whole rock) and 1857 ± 48 (minerals). Samples from the Catete River area give a whole rock age of 2018 ± 25 Ma with an initial ratio of 0.7039 ± 25. These data show that the Rb/Sr system in these granulitic rocks suffered changes during the Early Proterozoic times. The geochronological data here obtained confirm promptly an Archaean evolution in the studied regions, besides give rise the discussion about the problem related to the Transamazonian Event inside them. (author). 92 refs., 32 figs., 10 tabs

  17. Contributions to the petrography, geochemistry and geochronology (U-Pb and Sm-Nd) of the Paleoproterozoic effusive rocks from Iricoume Group, Amazonian Craton, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Suelen Nonata de Souza; Nascimento, Rielva Solimairy Campelo do, E-mail: suelen-marques@hotmail.com, E-mail: rielva@ufam.edu.br [Universidade Federal do Amazonas (UFAM), Manaus, AM (Brazil). Inst. de Geociencias; Souza, Valmir da Silva; Dantas, Elton Luiz, E-mail: vsouza@unb.br, E-mail: elton@unb.br [Universidade de Brasilia (UnB), DF (Brazil). Inst. de Geociencias; Valerio, Cristovao da Silva, E-mail: cristovao@igeo.ufrr.br [Universidade Federal de Roraima (UFRR), Boa Vista, RR (Brazil). Inst. de Geociencias

    2014-07-01

    The southernmost region of the Guyana shield, Amazonian craton, hosts large record of Paleoproterozoic effusive rocks of the Iricoume Group. They present remarkably well-preserved igneous textures and structures. The SiO{sub 2} contents reveal a bimodal association marked by a compositional gap between acid (SiO{sub 2} > 67 wt%) and intermediate (SiO{sub 2} < 57.7 wt%) rocks. The acid effusive rocks are rhyolites to rhyodacites with high SiO{sub 2}, alkali, Rb, Zr, Nb + Ta, La + Ce and 104 Ga/Al content and low Fe{sub 2}O{sub 3tot}, TiO{sub 2}, CaO, Sr and Co content. They exhibit subalkaline, metaluminous-to-peraluminous compositions, and geochemically compatible to A-type magmatism emplaced in post-collisional to within-plate tectonic settings. The intermediate rocks are andesitic/basalt to andesite relatively high contents of TiO{sub 2}, Al{sub 2}O{sub 3}, Fe{sub 2}O{sub 3total}, MgO, CaO, Sr and Co; low SiO{sub 2}, K{sub 2}O, Rb, Zr, Nb + Ta, La + Ce. They have subalkaline and metaluminous geochemical composition and plot on within-plate basalt field. The acid rocks crystallized at 1882 ± 11 Ma in U-Pb analyses for LA-MC-ICPMS zircon data. The Sm-Nd isotopic data on all rocks reveal a Nd TDM model ages between 2.59 and 2.16 Ga and ε{sub Nd}(t) values between -5.78 and 0.03, indicate that the magmatic evolution was related to the reworking of older Paleoproterozoic at the Rhyacian-Siderian period, continental crust (Transamazonian crust-forming event) with some mixing with a limited amount mantle-derived magmas or with contamination by Archean crust. The petrographic, geochemical and geochronological data presented in this paper suggest a within-plate to post-collisional tectonic setting for the Iricoume volcanism, involving lower crust uplift and generation of basalt magma in an extensional regime. (author)

  18. First observation of isomeric state in {sup 97}Rb

    Energy Technology Data Exchange (ETDEWEB)

    Rudigier, Matthias; Blazhev, Andrey; Regis, Jean-Marc; Warr, Nigel; Jolie, Jan; Fransen, Christoph; Hackstein, Matthias; Pfeiffer, Michael; Rother, Wolfram; Thomas, Tim [IKP, Univ. Koeln (Germany); Simpson, Gary; Ramdhane, Mourad [LPSC, Grenoble (France); Koester, Ulli; Materna, Thomas; Urban, Waldemar [ILL, Grenoble (France); Daugas, Jean-Michel [CEA, DAM, DIF, Arpajon (France)

    2012-07-01

    Data on a new microsecond isomer in {sup 97}Rb are presented. The measurement was conducted at the LOHENGRIN mass separator at the ILL, Grenoble. We were able to deduce the level energy and lifetime of the state. The multipolarity of the transition to the ground state was determined using conversion electron spectroscopy. This information enabled us to assign a spin and parity to the state, based on quasi-particle-rotor model calculations. The nucleus {sup 97}Rb has neutron number 60, and is thus situated in the shape-phase transition line of the mass 100 nuclei. It is discussed how the new state fits into the region and the Rb-isotopic chain. Furthermore some new results on the decay of the 9/2{sup +} microsecond isomer of {sup 97}Sr are presented and discussed.

  19. Geochemistry of organic-rich river waters in Amazonia: Insights on weathering processes of intertropical cratonic terrain

    International Nuclear Information System (INIS)

    Horbe, Adriana Maria Coimbra; Lages, Anderson da Silva; Moquet, Jean-Sébastien; Santos, Roberto Ventura; Seyler, Patrick

    2016-01-01

    In this study, eight organic-rich rivers that flow through the Brazilian craton in the southwestern Amazon rainforest are investigated. This investigation is the first of its type in this area and focuses on the effects of lithology, long-term weathering, thick soils, forest cover and hydrological period on the dissolved load compositions in rivers draining cratonic terrain. The major dissolved ion concentrations, alkalinity (TAlk), SiO 2 , trace element concentrations, and Sr isotope contents in the water were determined between April 2009 and January 2010. In addition, the isotopic values of oxygen and hydrogen were determined between 2011 and 2013. Overall, the river water is highly dilute and dominated by the major dissolved elements TAlk, SiO 2 and K + and the major dissolved trace elements Al, Fe, Ba, Mn, P, Zn and Sr, which exhibit large temporal and spatial variability and are closely correlated with the silicatic bedrock and hydrology. Additionally, rainwater and recycled water vapor and the size of the basin contribute to the geochemistry of the waters. The total weathering flux estimated from our results is 2–4 t km −2 .yr −1 , which is one of the lowest fluxes in the world. The CO 2 consumption rate is approximately 21–61 10 3  mol km −2  yr −1 , which is higher than expected given the stability of the felsic to basic igneous and metamorphic to siliciclastic basement rocks and the thick tropical soil cover. Thus, weathering of the cratonic terrain under intertropical humid conditions is still an important consumer of CO 2 . - Highlights: • Were studied rivers flowing the Brazilian craton covered by lateritic soils. • The river waters are highly diluted and dominated by TAlk, SiO 2 and K + . • There is spatial and temporal variability in the chemical composition. • The rain amount and recycled water vapor affect the O and D isotopes. • Geology, weathering, discharge and seasonality highlight a singular composition.

  20. Rb-Sr geochronology of coarse-grained greywackes and argillites from the Coffs Harbour Block, eastern Australia

    International Nuclear Information System (INIS)

    Graham, I.J.; Korsch, R.J.

    1985-01-01

    The Coffs Harbour Block, eastern Australia, includes a sequence of turbidity-current-deposited greywackes and argillites dominated by quartz-poor to quartz-intermediate, volcanic-lithic and feldspathic types. The rocks have a common provenance consisting of dacite with minor andesite and rhyolite, derived from a continental margin volcanic arc. Rb-Sr whole-rock dating of coarse-grained greywackes and argillites suggests that low-grade regional metamorphism (prehnite-pumpellyite to lowest greenschist facies) has completely equilibrated sediments of all grain sizes, giving an age of 318 +- 8 Ma. A subsequent metamorphism which produced thermal biotite on a regional scale over the southern part of the area, re-equilibrated only the fine-grained sediments 238 +- 5 Ma ago; the coarse-grained sediments were unaffected isotopically and still lie on the older isochron. The wide variations in sandstone petrographic modes imply that the older isochron represents neither the age of volcanism in the magmatic arc nor the age of sedimentation at the deposition site, but rather dates the time of earlier metamorphism. (orig.)

  1. Sr and Nd isotopic and trace element compositions of Quaternary volcanic centers of the Southern Andes

    Science.gov (United States)

    Futa, K.; Stern, C.R.

    1988-01-01

    Isotopic compositions of samples from six Quaternary volcanoes located in the northern and southern extremities of the Southern Volcanic Zone (SVZ, 33-46??S) of the Andes and from four centers in the Austral Volcanic Zone (AVZ, 49-54??S) range for 87Sr 86Sr from 0.70280 to 0.70591 and for 143Nd 144Nd from 0.51314 to 0.51255. The ranges are significantly greater than previously reported from the southern Andes but are different from the isotopic compositions of volcanoes in the central and northern Andes. Basalts and basaltic andesites from three centers just north of the Chile Rise-Trench triple junction have 87Sr 86Sr, 143Nd 144Nd, La Yb, Ba La, and Hf Lu that lie within the relatively restricted ranges of the basic magmas erupted from the volcanic centers as far north as 35??S in the SVZ of the Andes. The trace element and Sr and Nd isotopic characteristics of these magmas may be explained by source region contamination of subarc asthenosphere, with contaminants derived from subducted pelagic sediments and seawater-altered basalts by dehydration of subducted oceanic lithosphere. In the northern extremity of the SVZ between 33?? and 34??S, basaltic andesites and andesites have higher 87Sr 86Sr, Rb Cs, and Hf Lu, and lower 143Nd 144Nd than basalts and basaltic andesites erupted farther south in the SVZ, which suggests involvement of components derived from the continental crust. In the AVZ, the most primitive sample, high-Mg andesite from the southernmost volcanic center in the Andes (54??S) has Sr and Nd isotopic compositions and K Rb and Ba La similar to MORB. The high La Yb of this sample suggests formation by small degrees of partial melting of subducted MORB with garnet as a residue. Samples from centers farther north in the AVZ show a regionally regular northward increase in SiO2, K2O, Rb, Ba, Ba La, and 87Sr 86Sr and decrease in MgO, Sr, K Rb, Rb Cs, and 143Nd 144Nd, suggesting increasingly greater degrees of fractional crystallization and associated intra

  2. Permian alkali granitoids of the transbaikal region (new Rb-Sr dates)

    Energy Technology Data Exchange (ETDEWEB)

    Sukhanov, M K; Ryakhovskij, V M; Abramov, A V

    1984-01-01

    Rubidium-strontium isotopic investigations of granitoids from Khorinsk and Middle Oninsk massifs were conducted. Isochrones for two chief-modifications of rocks - subalkaline syenites and alkaline granites-were constructed. The age of syenites is determined to be (293 + 20) x 10/sup 6/ at (/sup 87/Sr//sup 86/Sr)/sub 0/=0.7044 +- 0.0106 that of alkaline granites - (253 +- 3) x 10/sup 6/ at (/sup 87/Sr//sup 86/Sr)/sub 0/=0.7077 +- 0.0033. Analytical data for determination of rubidium-strontium age of rocks of the mentioned massits are presented as well.

  3. 44/40Ca and 87Sr/86Sr isotopes as tracers of silicate weathering in small catchments of the Massif Central, France

    Science.gov (United States)

    Négrel, Philippe; Guerrot, Catherine; Millot, Romain; Petelet-Giraud, Emmanuelle; Bullen, Thomas

    2013-04-01

    We present calcium stable isotope and strontium radiogenic isotope data for soils and sediments developed on volcanic and igneous rocks forming small catchments in the Massif Central (France). Measurements of 44/40Ca isotope ratios (44/40Ca measured by the double spike method on TIMS and normalized to the value for seawater Ca in delta units) in rocks, sediments and soils from silicate catchments (e.g. granite and basalts) together with 87Sr/86Sr isotope ratios permit an examination of the relationships of these isotope systematics during weathering of silicate rocks. We have analysed the granite, weathered granite (arene) and saprolite, sediment and soil overlying the granite on one hand and the basanite, sediment and soil overlying the basanite on the other. The main bedrock in the volcanic zone (e.g. Allanche catchment) is 11 to 2.5 Ma basanite (nephelinitic to leucitic basalts) having SiO2 between 41-45 wt. %, Na2O + K2O bank have 87Sr/86Sr ratios greater than that of the arene with values increasing in the sediment from the surface down to soil. The 87Sr/86Sr vs. Rb/Sr variation observed in the volcanic area likewise confirms the weathering of low 87Sr/86Sr, low Rb/Sr phases in the bedrock, and there is a linear increase in 87Sr/86Sr and Rb/Sr ratios from those in the sediment up to the values observed in the soils. In the volcanic area, the basanite bedrock has 44/40Ca = -0.94 ± 0.05‰ (n = 7), while the soils and sediments have 44/40Ca of -0.75 to -1.13‰ and -0.79 to -1.01‰, respectively. These results suggest that Ca isotopes are not strongly fractionated during weathering of the basalt. The granite whole-rock has 44/40Ca of -1.29‰, while the soil and sediments have 44/40Ca of -1.93 to -2.07‰ and -1.98 to -2.81‰, respectively, with values decreasing as the Ca content decreases. The 44/40Ca ratios of arene, soil and sediment are similar to or less than that of K- feldspar, reflecting complete loss of the relatively heavy Ca from plagioclase and

  4. Contribution on the Northeastern Minas Gerais geologic-geochronologic study, Brazil

    International Nuclear Information System (INIS)

    Siga Junior, O.; Cordani, U.G.; Basei, M.A.S.; Teixeira, W.; Kawashita, K.

    1987-01-01

    This work demonstrates the potential of integrated Rb-Sr, K-Ar, and U-Pb determinations, when applied to basic regional geology. The different interpretative values of these methodologies contribute to the understanding of the tectonic processes developed in the south-eastern border of the Sao Francisco Craton (northeastern Minas Gerais). The Brazilian Orogenic Cycle is characterized in the area by the Salinas metasediments and the gneissic-migmatitic rocks of the eastern sector. Rb-Sr and U-Pb data indicate the generation of most or even all of these rocks in the 660-570 Ma, interval. No indications of ancient terrains were obtained, and previous ideas of a pervasive reworking of an Archean or Lower Proterozoic crust must be discarded. The K-Ar analyses indicate a crustal level in which temperature remained above 250 O C until at least 480 Ma. (author)

  5. Re-Os geochronology of a Mesoproterozoic sedimentary succession, Taoudeni basin, Mauritania: Implications for basin-wide correlations and Re-Os organic-rich sediments systematics

    Science.gov (United States)

    Rooney, Alan D.; Selby, David; Houzay, Jean-Pierre; Renne, Paul R.

    2010-01-01

    The exceptionally well-preserved sedimentary rocks of the Taoudeni basin, NW Africa represent one of the world's most widespread (> 1 M km 2) Proterozoic successions. Hitherto, the sedimentary rocks were considered to be Mid Tonian based on Rb-Sr illite and glauconite geochronology of the Atar Group. However, new Re-Os organic-rich sediment (ORS) geochronology from two drill cores indicates that the Proterozoic Atar Group is ˜ 200 Ma older (1107 ± 12 Ma, 1109 ± 22 Ma and 1105 ± 37 Ma). The Re-Os geochronology suggests that the Rb-Sr geochronology records the age of diagenetic events possibly associated with the Pan African collision. The new Re-Os geochronology data provide absolute age constraints for recent carbon isotope chemostratigraphy which suggests that the Atar Group is Mesoproterozoic and not Neoproterozoic. The new Re-Os ORS geochronology supports previous studies that suggest that rapid hydrocarbon generation (flash pyrolysis) from contact metamorphism of a dolerite sill does not significantly disturb the Re-Os ORS systematics. Modelled contact conditions suggest that the Re-Os ORS systematics remain undisturbed at ˜ 650 °C at the sill/shale contact and ≥ 280 °C 20 m from the sill/shale contact. Moreover, the Re-Os geochronology indicates that the West African craton has a depositional history that predates 1100 Ma and that ORS can be correlated on a basin-wide scale. In addition, the Re-Os depositional ages for the ORS of the Taoudeni basin are comparable to those of ORS from the São Francisco craton, suggesting that these cratons are correlatable. This postulate is further supported by identical Os i values for the Atar Group and the Vazante Group of the São Francisco craton.

  6. Erosion of the Alps: use of Rb-Sr isotopic data from molassic sediments to identify the ages of the metamorphism recorded by the eroded rocks

    International Nuclear Information System (INIS)

    Henry, P.; Deloule, E.

    1994-01-01

    Rb-Sr isotopic data from Oligocene and Miocene peri-alpine molassic sediments allow us to identify the different periods for which the eroded rocks have or have not recorded an alpine metamorphism. The Chattian and the Burdigalian sediments result from the erosion of rocks for which the latest metamorphic event was variscan, while the Stampian, Aquitanian and ''Helvetian'' sediments show evidence for the erosion of rocks which have recorded alpine metamorphic events. The application of this method to old detrital sediments could permit determination of the ages of the tectonic events which occurred in the sediment source regions. (authors). 18 refs., 6 figs

  7. Rb-Sr, K-Ar, and stable isotope evidence for the ages and sources of fluid components of gold-bearing quartz veins in the northern Sierra Nevada foothills metamorphic belt, California

    Science.gov (United States)

    Böhlke, John Karl; Kistler, R. W.

    1986-01-01

    Gold-bearing quartz veins occur in and near major fault zones in deformed oceanic and island-arc rocks west of the main outcrop of the Sierra Nevada composite batholith. Veins typically occupy minor reverse faults that crosscut blueschist to amphibolite-grade metamorphic rocks whose metamorphic ages range from early Paleozoic to Jurassic. Vein micas and carbonate-quartz-mica assemblages that formed by hydrothermal metasomatism of ultramafic wall rocks in the Alleghany, Grass Valley, Washington, and Mother Lode districts yield concordant K-Ar and Rb-Sr ages. The dated veins are significantly younger than prograde metamorphism, penetrative deformation, and accretion of their host rocks to the continental margin. New and previously published mineralization ages from 13 localities in the Sierra foothills range from about 140 to 110 m.y. ago, with mean and median between 120 and 115 m.y. The age relations suggest that mineralizing fluids were set in motion by deep magmatic activity related to the resumption of east-dipping subduction along the western margin of North America following the Late Jurassic Nevadan collision event.CO 2 -bearing fluids responsible for metasomatism and much of the vein mica, carbonate, albite, and quartz deposition in several northern mines were isotopically heavy (delta 18 O [asymp] 8-14ppm; delta D between about -10 and -50ppm) and do not resemble seawater, magmatic, or meteoric waters. Metasomatic and vein-filling mica, dolomite, magnesite, and quartz in altered ultramafic rocks generally formed from fluids with similar Sr and O isotope ratios at a given locality. Consistent quartz-mica delta 18 O fractionations (delta 18 O (sub Q-M) = 4.5-4.9ppm) from various localities imply uniform equilibration temperatures, probably between 300 degrees and 350 degrees C. On a local (mine) scale, fluids responsible for both carbonate alteration of mafic and ultramafic wall rocks and albitic alteration of felsic and pelitic rocks had similar Sr isotope

  8. Dating Melt Rock 63545 By Rb-Sr and Sm-Nd: Age of Imbrium; Spa Dress Rehearsal

    Science.gov (United States)

    Nyquist, L. E.; Shih, C. Y.; Reese, Y. D.

    2011-01-01

    Apollo 16 sample 63545 was initially described as one of a group of 19 generally rounded, fine-grained, crystalline rocks that were collected as rake samples [1]. This 16 g "rocklet" was collected at Station 13 on the ejecta blanket of North Ray Crater at the foot of Smoky Mountain [2]. Originally classified as a Very High Alumina (VHA) basalt on geochemical grounds [3], it was later argued to be an impact melt rock [4]. Here we report a Rb-Sr and Sm-Nd isotopic study that shows that some portions of the rock failed to reach isotopic equilibrium on last melting in agreement with the impact melt rock interpretation. Nevertheless, by omitting mineral fractions that are discordant with the majority of the data, we arrive at the time of last melting as 3.88 plus or minus 0.05 Ga ago. This age is in agreement with the Ar-39/Ar-40 plateau age of 3839 plus or minus 23 Ma [5], if the latter is adjusted for the 1.4-1.8% revision in the age of the hornblende monitor [6]. This investigation was undertaken in part as proof-of-concept for SPA-basin sample return.

  9. Granitoids of the Dry Valleys area, southern Victoria Land : geochemistry and evolution along the early Paleozoic Antarctic Craton margin

    International Nuclear Information System (INIS)

    Allibone, A.H.; Cox, S.C.; Smillie, R.W.

    1993-01-01

    Field relationships and geochemistry indicate granitoid plutons of the Dry Valleys area comprise at least three petrogenetically distinct suites. The older Dry Valleys 1a (DV1a) suite, comprising the Bonney, Catspaw, Denton, Cavendish, and Wheeler Plutons and hornblende-biotite orthogneisses, and Dry Valleys 1b (DV1b) suite, comprising the Hedley, Valhalla, St Johns, Dun, Calkin, and Suess Plutons, biotite granitoid dikes and biotite orthogneisses, were emplaced before prominent swarms of Vanda mafic and felsic dikes. Both the DV1a and DV1b suites are time transgressive, with older intrusions in each suite being emplaced during the later stages of deformation of the Koettlitz Group. Younger granitoids that postdate the majority of the Vanda dikes include: the Dry Valleys 2 (DV2) suite, comprising the Pearse and Nibelungen Plutons plus several smaller, unnamed plugs; and the Harker, Swinford, Orestes, and Brownworth Plutons with identical field relationships and enclaves but distinct chemistries. Chemical characteristics and limited Rb-Sr isotopic dating indicate plutonism before c. 500 Ma was dominated by the Cordilleran I-type DV1a suite, inferred to have developed during melting above a west-dipping subduction zone along the Antarctic Craton margin. The chemical characteristics of the DV1b suite indicate large-scale melting of a quartzo-feldspathic protolith lacking residual plagioclase, but containing refractory garnet. Potential DV1b suite source rocks include metamorphosed immature sediments, possibly underplated along the subduction zone associated with DV1a magmatism, or older granitoid orthogneisses. Major DV1b plutonism at 490 Ma marks the end of subduction-related plutonism in southern Victoria Land. Younger DV2 alkali-calcic, Caledonian I-type plutonism is inferred to have formed in response to uplift and extension between 480 and 455 Ma. Lack of DV2 suite correlatives and Vanda mafic and felsic dikes in northern Victoria Land suggests significantly

  10. Rb-Sr and Ar-Ar systematics of Malani volcanic rocks of southwest Rajasthan: evidence for a younger post-crystallization thermal event

    International Nuclear Information System (INIS)

    Rathore, S.S.; Srivastava, R.K.

    1996-01-01

    A new Rb-Sr age of 779 ± 10 Ma has been obtained for a suite of andesite-dacite-rhyolite from the Malani igneous province of southwestern Rajasthan, dated earlier at 745 ± 10 Ma by Crawford and Compston (1970). The associated basalts may be slightly younger than the felsic volcanics and have a mantle source. The felsic volcanics on the other hand were most probably derived by fractional crystallization of a crustal magma. 40 Ar- 39 Ar systematics of three samples viz., a basalt, a dacite and a rhyolite show disturbed age spectra indicating a thermal event around 500-550 Ma ago. This secondary thermal event is quite wide-spread and possibly related to the Pan-African thermo-tectonic episode observed in the Himalayas and south India. (author). 38 refs., 5 figs., 2 tabs

  11. Rb/Sr and U/Pb isotopic ages in basement rocks of Mina Gonzalito and Arroyo Salado, Atlantic North-Patagonian Massif, Rio Negro, Argentina

    International Nuclear Information System (INIS)

    Varela, Ricardo; Sato, Ana M.; Cingolani, Carlos A.; Basei, Miguel A.S.; Siga, Oswaldo; Sato, Kei

    1998-01-01

    Isotopic ages from metamorphic and plutonic rocks of the Atlantic area of North Patagonian basement indicate that the main crustal tectonic events occurred during the late Proterozoic to early Paleozoic times. Rb/Sr and U/Pb data in the 550-470 Ma interval suggest an old tecto-thermal activity during the upper Brazilian Cycle (Rio Doce Orogeny). At regional scale, the comparable Neo proterozoic basement of Ventania and sedimentary for eland cover of Tandilia continues to the Northeast, in the Dom Feliciano Belt. A possible correlation of the North Patagonian basement with igneous-metamorphic relics of Central Argentina (Pampean Ranges of San Luis-Cordoba and at La Pampa province) is also indicated. (author)

  12. Effect of Wood Aging on Wine Mineral Composition and 87Sr/86Sr Isotopic Ratio.

    Science.gov (United States)

    Kaya, Ayse D; Bruno de Sousa, Raúl; Curvelo-Garcia, António S; Ricardo-da-Silva, Jorge M; Catarino, Sofia

    2017-06-14

    The evolution of mineral composition and wine strontium isotopic ratio 87 Sr/ 86 Sr (Sr IR) during wood aging were investigated. A red wine was aged in stainless steel tanks with French oak staves (Quercus sessiliflora Salisb.), with three industrial scale replicates. Sampling was carried out after 30, 60, and 90 days of aging, and the wines were evaluated in terms of general analysis, phenolic composition, total polysaccharides, multielement composition, and Sr IR. Li, Be, Mg, Al, Sc, Ti, V, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Mo, Sb, Cs, Ba, Pr, Nd, Sm, Eu, Dy, Ho, Er, Yb, Lu, Tl, and Pb elements and 87 Sr/ 86 Sr were determined by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) and Na, K, Ca, and Fe by flame atomic absorption spectrometry (FAAS). Two-way ANOVA was applied to assess wood aging and time effect on Sr IR and mineral composition. Wood aging resulted in significantly higher concentrations of Mg, V, Co, Ni, and Sr. At the end of the aging period, wine exhibited statistically identical Sr IR compared to control. Study suggests that wood aging does not affect 87 Sr/ 86 Sr, not precluding the use of this parameter for wine traceability purposes.

  13. Craton stability and continental lithosphere dynamics during plume-plate interaction

    Science.gov (United States)

    Wang, H.; Van Hunen, J.; Pearson, D.

    2013-12-01

    Survival of thick cratonic roots in a vigorously convecting mantle system for billions of years has long been studied by the geodynamical community. A high cratonic root strength is generally considered to be the most important factor. We first perform and discuss new numerical models to investigate craton stability in both Newtonian and non-Newtonian rheology in the stagnant lid regime. The results show that only a modest compositional rheological factor of Δη=10 with non-Newtonian rheology is required for the survival of cratonic roots in a stagnant lid regime. A larger rheological factor (100 or more) is needed to maintain similar craton longevity in a Newtonian rheology environment. Furthermore, chemical buoyancy plays an important role on craton stability and its evolution, but could only work with suitable compositional rheology. During their long lifespan, cratons experienced a suite of dynamic, tectonothermal events, such as nearby subduction and mantle plume activity. Cratonic nuclei are embedded in shorter-lived, more vulnerable continental areas of different thickness, composition and rheology, which would influence the lithosphere dynamic when tectonothermal events happen nearby. South Africa provides a very good example to investigate such dynamic processes as it hosts several cratons and there are many episodic thermal events since the Mesozoic as indicated by a spectrum of magmatic activity. We numerically investigate such an integrated system using the topographic evolution of cratons and surrounding lithosphere as a diagnostic observable. The post-70Ma thinning of pericratonic lithosphere by ~50km around Kaapvaal craton (Mather et al., 2011) is also investigated through our numerical models. The results show that the pericratonic lithosphere cools and grows faster than cratons do, but is also more likely to be effected by episodic thermal events. This leads to surface topography change that is significantly larger around the craton than within

  14. Geological evolution of the Antongil Craton, NE Madagascar

    Science.gov (United States)

    Schofield, D.I.; Thomas, Ronald J.; Goodenough, K.M.; De Waele, B.; Pitfield, P.E.J.; Key, R.M.; Bauer, W.; Walsh, G.J.; Lidke, D.J.; Ralison, A.V.; Rabarimanana, M.; Rafahatelo, J.-M.; Randriamananjara, T.

    2010-01-01

    The Antongil Craton, along with the Masora and Antananarivo cratons, make up the fundamental Archaean building blocks of the island of Madagascar. They were juxtaposed during the late-Neoproterozoic to early Palaeozoic assembly of Gondwana. In this paper we give a synthesis of the geology of the Antongil Craton and present previously published and new geochemical and U-Pb zircon analyses to provide an event history for its evolution.The oldest rocks in the Antongil Craton form a nucleus of tonalitic gneiss, characteristic of Palaeo-Mesoarchaean cratons globally, including phases dated between 3320 ?? 14. Ma to 3231 ?? 6. Ma and 3187 ?? 2. Ma to 3154 ?? 5. Ma. A series of mafic dykes was intruded into the Mesoarchaean tonalites and a sedimentary succession was deposited on the craton prior to pervasive deformation and migmatisation of the region. The age of deposition of the metasediments has been constrained from a volcanic horizon to around 3178 ?? 2. Ma and subject to migmatisation at around 2597 ?? 49. Ma. A subsequent magmatic episode generated voluminous, weakly foliated granitic rocks, that also included additions from both reworked older crustal material and younger source components. An earlier granodiorite-dominated assemblage, dated between 2570 ?? 18. Ma and 2542 ?? 5. Ma, is largely exposed in xenoliths and more continuously in the northern part of the craton, while a later monzogranite-dominated phase, dated between 2531 ?? 13. Ma and 2513 ?? 0.4. Ma is more widely developed. Together these record the stabilisation of the craton, attested to by the intrusion of a younger dyke swarm, the age of which is constrained by a sample of metagabbro dated at 2147 ?? 6. Ma, providing the first evidence for Palaeoproterozoic rocks from the Antongil Craton.The youngest events recorded in the isotopic record of the Antongil Craton are reflected in metamorphism, neocrystallisation and Pb-loss at 792 ?? 130. Ma to 763 ?? 13. Ma and 553 ?? 68. Ma. These events are

  15. Trace element geochemistry (Li, Ba, Sr, and Rb) using Curiosity's ChemCam: early results for Gale crater from Bradbury Landing Site to Rocknest

    Science.gov (United States)

    Ollila, Ann M.; Newsom, Horton E.; Clark, Benton; Wiens, Roger C.; Cousin, Agnes; Blank, Jen G.; Mangold, Nicolas; Sautter, Violaine; Maurice, Sylvestre; Clegg, Samuel M.; Gasnault, Olivier; Forni, Olivier; Tokar, Robert; Lewin, Eric; Dyar, M. Darby; Lasue, Jeremie; Anderson, Ryan; McLennan, Scott M.; Bridges, John; Vaniman, Dave; Lanza, Nina; Fabre, Cecile; Melikechi, Noureddine; Perett, Glynis M.; Campbell, John L.; King, Penelope L.; Barraclough, Bruce; Delapp, Dorothea; Johnstone, Stephen; Meslin, Pierre-Yves; Rosen-Gooding, Anya; Williams, Josh

    2014-01-01

    The ChemCam instrument package on the Mars rover, Curiosity, provides new capabilities to probe the abundances of certain trace elements in the rocks and soils on Mars using the laser-induced breakdown spectroscopy technique. We focus on detecting and quantifying Li, Ba, Rb, and Sr in targets analyzed during the first 100 sols, from Bradbury Landing Site to Rocknest. Univariate peak area models and multivariate partial least squares models are presented. Li, detected for the first time directly on Mars, is generally low (100 ppm and >1000 ppm, respectively. These analysis locations tend to have high Si and alkali abundances, consistent with a feldspar composition. Together, these trace element observations provide possible evidence of magma differentiation and aqueous alteration.

  16. Decay of 83Sr

    International Nuclear Information System (INIS)

    Yu Xiaohan; Shi Shuanghui; Gu Jiahui

    1997-01-01

    The decay of 83 Sr was reinvestigated using γ singles and γ-γ-t coincidence measurement. A new level scheme of Rb, which contains 41 excited levels and about 180 transitions, is constructed. 19 new levels were added to the old level scheme and 8 formerly adopted levels were denied. A new data set of branching ratio, log(ft) value and spin parity was obtained

  17. Geologic evolution of the SE.23 Sheet - Belo Horizonte, MG, Brazil

    International Nuclear Information System (INIS)

    Pereira, A.D.C.; Fonseca, E.G. da; Braz, E.R.C.

    1987-01-01

    The aim of this paper is to present a synthesis of the geologic evolution in the Belo Horizonte Sheet comprising an area about 281.210 Km 2 . Rb-Sr and K-Ar isotope dating methods are used for age estimation of geologic deposits. The geologic evolution of the cratonic area is reflected by a stable central nucleus surrounded by marginal orogenic belts. In the central area were recognized greenstone belts structures involved by granite terrains and bordered by a granulitic region. The framework of the Sao Francisco Craton involves events of metamorphism, granitogenesis, sedimentary, volcanism and plutonism developed in the Early to Late Proterozoic. The stratigraphic column is complemented by Late Jurassic-Early Cretaceous continental deposits belonging to Parana-Basin. (M.V.M.)

  18. Macrocrystal phlogopite Rb-Sr dates for the Ekati property kimberlites, Slave Province, Canada: evidence for multiple intrusive episodes in the Paleocene and Eocene

    Science.gov (United States)

    Creaser, Robert A.; Grütter, Herman; Carlson, Jon; Crawford, Barbara

    2004-09-01

    New Rb-Sr age determinations using macrocrystal phlogopite are presented for 27 kimberlites from the Ekati property of the Lac de Gras region, Slave Province, Canada. These new data show that kimberlite magmatism at Ekati ranges in age from at least Late Paleocene (∼61 Ma) to Middle Eocene time (∼45 Ma). Older, perovskite-bearing kimberlites from Ekati extend this age range to Late Cretaceous time (∼74 Ma). Within this age range, emplacement episodes at ∼48, 51-53, 55-56 and 59-61 Ma can be recognized. Middle Eocene kimberlite magmatism of the previously dated Mark kimberlite (∼47.5 Ma) is shown to include four other pipes from the east-central Ekati property. A single kimberlite (Aaron) may be younger than the 47.5 Ma Mark kimberlite. The economically important Panda kimberlite is precisely dated in this study to be 53.3±0.6 Ma using the phlogopite isochron method, and up to six additional kimberlites from the central Ekati property have Early Eocene ages indistinguishable from that of Panda, including the Koala and Koala North occurrences. Late Paleocene 55-56 Ma kimberlite magmatism, represented by the Diavik kimberlite pipes adjacent to the southeastern Ekati property, is shown to extend onto the southeastern Ekati property and includes three, and possibly four, kimberlites. A precise eight-point phlogopite isochron for the Cobra South kimberlite yields an emplacement age of 59.7±0.4 Ma; eight other kimberlites from across the Ekati property have similar Late Paleocene Rb-Sr model ages. The addition of 27 new emplacement ages for kimberlites from the Ekati property confirms that kimberlite magmatism from the central Slave Province is geologically young, despite ages ranging back to Cambrian time from elsewhere in the Slave Province. With the available geochronologic database, Lac de Gras kimberlites with the highest diamond potential are currently restricted to the 51-53 and 55-56 Ma periods of kimberlite magmatism.

  19. Tracing subduction zone fluid-rock interactions using trace element and Mg-Sr-Nd isotopes

    Science.gov (United States)

    Wang, Shui-Jiong; Teng, Fang-Zhen; Li, Shu-Guang; Zhang, Li-Fei; Du, Jin-Xue; He, Yong-Sheng; Niu, Yaoling

    2017-10-01

    Slab-derived fluids play a key role in mass transfer and elemental/isotopic exchanges in subduction zones. The exhumation of deeply subducted crust is achieved via a subduction channel where fluids from various sources are abundant, and thus the chemical/isotopic compositions of these rocks could have been modified by subduction-zone fluid-rock interactions. Here, we investigate the Mg isotopic systematics of eclogites from southwestern Tianshan, in conjunction with major/trace element and Sr-Nd isotopes, to characterize the source and nature of fluids and to decipher how fluid-rock interactions in subduction channel might influence the Mg isotopic systematics of exhumed eclogites. The eclogites have high LILEs (especially Ba) and Pb, high initial 87Sr/86Sr (up to 0.7117; higher than that of coeval seawater), and varying Ni and Co (mostly lower than those of oceanic basalts), suggesting that these eclogites have interacted with metamorphic fluids mainly released from subducted sediments, with minor contributions from altered oceanic crust or altered abyssal peridotites. The positive correlation between 87Sr/86Sr and Pb* (an index of Pb enrichment; Pb* = 2*PbN/[CeN + PrN]), and the decoupling relationships and bidirectional patterns in 87Sr/86Sr-Rb/Sr, Pb*-Rb/Sr and Pb*-Ba/Pb spaces imply the presence of two compositionally different components for the fluids: one enriched in LILEs, and the other enriched in Pb and 87Sr/86Sr. The systematically heavier Mg isotopic compositions (δ26Mg = - 0.37 to + 0.26) relative to oceanic basalts (- 0.25 ± 0.07) and the roughly negative correlation of δ26Mg with MgO for the southwestern Tianshan eclogites, cannot be explained by inheritance of Mg isotopic signatures from ancient seafloor alteration or prograde metamorphism. Instead, the signatures are most likely produced by fluid-rock interactions during the exhumation of eclogites. The high Rb/Sr and Ba/Pb but low Pb* eclogites generally have high bulk-rock δ26Mg values

  20. TXRF and XRF techniques for the determination of K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr and Pb in some plant species and their infusion

    Energy Technology Data Exchange (ETDEWEB)

    Khuder, A [Atomic Energy Commission, Damascus (Syrian Arab Republic). Dept. of Chemistry

    2009-02-15

    The content of K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, and Sr elements in some medicinal plants, including: A. herba-alba, T. officinale, M. officinalis, T. syeriacus, T. vulgaris, A. officinalis, R. officinalis, M. piperita, M. aquatica, Zea mays, G. glabra, A. vulgare, U. urens, C. aronica, H. officinalis, M. aurea, C. cyminum, was determined using TXRF technique. Concentrations of Pb upper the detection limits of TXRF method was determined only in A. herba-alba leaves with a mean value of 3.6 ppm. The accuracy and the precision of TXRF method were verified using Apple leaves, Peach leaves, and Hay Powder Standard Reference Materials (SRM) for the analysis of plant samples. The previously mentioned elements were accurately determined by TXRF, except Br. Errors obtained by Br determination may be obtained by the partial losses of element content during evaporation of sample on quartz carrier proposed for TXRF measurements. TXRF results for Ca, Mn, and Sr elements agreed well with these obtained by XRF method with standard relative error (SR) better than 10 %, while, these obtained for rest elements, except Br, were with SR ranging between 11 %-20 %. Br was not included in the determination of elements by TXRF. Transfer of K, Ca, Mn, Fe, Cu, Zn, Br, Rb, and Sr from A. herba-alba, A. vulgare, Zea mays, M. aquatica, M. piperita, C. cyminum, G. glabra, M. officinalis, and R. officinalis plant materials to infusions at different temperatures were studied using XRF method. Data analyses were verified by Peach and Apple leaves of Standard Reference Materials. Potassium represented the dominant element in all studied plants, particularly, in roots of U. dioica plant with concentrations in the range of 59.3 g/Kg-90.8 g/Kg. Independently of brewing 5 temperature, potassium with a high ratio was transferred from plants to infusions. K transfer ratio was in a range from 57.2 % for A. vulgare leaves at 25 .C to 91 % for G. glabra at 55 .C. Although, Fe content in dry plant

  1. TXRF and XRF techniques for the determination of K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr and Pb in some plant species and their infusion

    International Nuclear Information System (INIS)

    Khuder, A.

    2009-02-01

    The content of K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, and Sr elements in some medicinal plants, including: A. herba-alba, T. officinale, M. officinalis, T. syeriacus, T. vulgaris, A. officinalis, R. officinalis, M. piperita, M. aquatica, Zea mays, G. glabra, A. vulgare, U. urens, C. aronica, H. officinalis, M. aurea, C. cyminum, was determined using TXRF technique. Concentrations of Pb upper the detection limits of TXRF method was determined only in A. herba-alba leaves with a mean value of 3.6 ppm. The accuracy and the precision of TXRF method were verified using Apple leaves, Peach leaves, and Hay Powder Standard Reference Materials (SRM) for the analysis of plant samples. The previously mentioned elements were accurately determined by TXRF, except Br. Errors obtained by Br determination may be obtained by the partial losses of element content during evaporation of sample on quartz carrier proposed for TXRF measurements. TXRF results for Ca, Mn, and Sr elements agreed well with these obtained by XRF method with standard relative error (SR) better than 10 %, while, these obtained for rest elements, except Br, were with SR ranging between 11 %-20 %. Br was not included in the determination of elements by TXRF. Transfer of K, Ca, Mn, Fe, Cu, Zn, Br, Rb, and Sr from A. herba-alba, A. vulgare, Zea mays, M. aquatica, M. piperita, C. cyminum, G. glabra, M. officinalis, and R. officinalis plant materials to infusions at different temperatures were studied using XRF method. Data analyses were verified by Peach and Apple leaves of Standard Reference Materials. Potassium represented the dominant element in all studied plants, particularly, in roots of U. dioica plant with concentrations in the range of 59.3 g/Kg-90.8 g/Kg. Independently of brewing 5 temperature, potassium with a high ratio was transferred from plants to infusions. K transfer ratio was in a range from 57.2 % for A. vulgare leaves at 25 .C to 91 % for G. glabra at 55 .C. Although, Fe content in dry plant

  2. Fluorescence of RbH and RbD formed by irradiating the mixed gases Rb + H2 and Rb + D2 with laser light

    International Nuclear Information System (INIS)

    Kato, Hajime; Toyosaka, Yukiko; Suzuki, Tomonari

    1985-01-01

    When a mixture of 85 Rb, 85 Rb 2 , and D 2 was irradiated by laser light at 5145 or 4880 A, small visible particles appeared and the fluorescence spectra were observed. By analyzing these spectra, we determined the rotational constants B v and the centrifugal distortion constants D v and H v for the X 1 Σ + and A 1 Σ + states of 85 RbD. By considering the isotopic dependence of the Dunham coefficients, we determined various molecular constants of 85 RbH whose values were in good agreement with the observed fluorescence spectra of 85 RbH excited by laser lines at 4762, 4765, and 4880 A. The process of RbH formation is discussed. (author)

  3. Rb-Sr, Sm-Nd and Lu-Hf isotope systematics of the lunar Mg-suite: the age of the lunar crust and its relation to the time of Moon formation.

    Science.gov (United States)

    Carlson, Richard W; Borg, Lars E; Gaffney, Amy M; Boyet, Maud

    2014-09-13

    New Rb-Sr, (146,147)Sm-(142,143)Nd and Lu-Hf isotopic analyses of Mg-suite lunar crustal rocks 67667, 76335, 77215 and 78238, including an internal isochron for norite 77215, were undertaken to better define the time and duration of lunar crust formation and the history of the source materials of the Mg-suite. Isochron ages determined in this study for 77215 are: Rb-Sr=4450±270 Ma, (147)Sm-(143)Nd=4283±23 Ma and Lu-Hf=4421±68 Ma. The data define an initial (146)Sm/(144)Sm ratio of 0.00193±0.00092 corresponding to ages between 4348 and 4413 Ma depending on the half-life and initial abundance used for (146)Sm. The initial Nd and Hf isotopic compositions of all samples indicate a source region with slight enrichment in the incompatible elements in accord with previous suggestions that the Mg-suite crustal rocks contain a component of KREEP. The Sm/Nd-(142)Nd/(144)Nd correlation shown by both ferroan anorthosite and Mg-suite rocks is coincident with the trend defined by mare and KREEP basalts, the slope of which corresponds to ages between 4.35 and 4.45 Ga. These data, along with similar ages for various early Earth differentiation events, are in accord with the model of lunar formation via giant impact into Earth at ca 4.4 Ga. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  4. The Thermal Structure and Strength of Cratons and their Margins

    Science.gov (United States)

    Jaupart, C. P.; Mareschal, J. C.

    2015-12-01

    The large cratons of today are made of younger terranes that wrap around older cores. Deformation due to accretion did not proceed in homogeneous fashion and was concentrated in the younger belts. This is illustrated clearly in the Archean Superior Province, Canada. In this area, one observes little imbrication of accreted crust and craton core, in contrast to the laterally extensive thrusting that has affected the younger terranes to the South. The boundary between the craton core and accreted belts is a nearly vertical interface delineated by steeply dipping electrical and seismic anomalies extending to the base of the lithosphere. These steeply dipping structures have been interpreted as relicts of the subduction that drove accretion. By contrast, the sub-crustal subduction remnant that is imaged beneath younger terranes to the south shows up as a moderately dipping (≈30°) structure. These observations suggest a stiff craton surrounded by weaker belts. This strength contrast may have affected later events, such as the Keweenawan rifing, which propagated northward through the accreted terranes but stopped short of impinging the craton core. In the Superior Province, crustal heat production is much higher in the accreted terranes than in the craton core, implying higher temperatures and lower mechanical strength. Such a remarkable dichotomy also exists in South Africa, where the Limpopo and Namaqua belts are characterized by higher heat flux and crustal heat production than the adjacent Archean Kaapvaal and Zimbabwe cratons. The generality of this cannot be assessed on the basis of heat flow and heat production data which are scarce in most other cratons. These cratons, however, are characterized by post-orogenic high temperature metamorphism which is best explained by high crustal heat production. This is true, for example, for the Jimperding metamorphic belt at the edge of the Yilgarn craton, Western Australia. Thus, cratons appear to be surrounded, and

  5. Genesis of Neoproterozoic granitoid magmatism in the Eastern Aracuai Fold Belt, eastern Brazil: field, geochemical and Sr-Nd isotopic evidence

    International Nuclear Information System (INIS)

    Celino, Joil Jose; Botelho, Nilson Francisquini; Pimentel, Marcio Martins

    2000-01-01

    The Neoproterozoic granitoid magmatism of the Aracuai Fold Belt (AFB) is an important element for the discussion of the evolution of this belt and its relationships with the African counterpart, the West Congo Belt. In the eastern part of the AFB, four different granitoid suites were recognized. The Nanuque Suite (NQS) comprises syn-tectonic peraluminous cordierite-bearing monzogranites. The Sao Paulinho Suite (SPS) consists of Th-rich peraluminous two mica or biotite-only granitoids. Calc-alkalic granitoids with magmatic epidote were grouped into the Itagimirim Suite (ITS) and post-tectonic charnockitic rocks were grouped into the Salomao Suite (SLS). Sm-Nd mineral isochron and Rb- isochron yielded ages of yielded ages of respectively 761 Ma and 714 Ma for the Nanuque and Sao Paulino suites. The general Sr-Nd isotopic characteristics of the granitoid suites and some country rocks indicate that the parental magmas were mostly the product of melting of the Paraiba do Sul metasediments. The chronological and genetic evolution the Neoproterozoic plutonism can be envisaged in a model of est-dipping subduction zone, followed by a continental collision between the Brasiliano/Pan-African (Brazil) and Congo (Africa cratons and final episodes of uplift and collapse. (author)

  6. Definition of the optimal terms of isotope 82Sr obtaining on cyclotron U-240

    Directory of Open Access Journals (Sweden)

    O. E. Valkov

    2014-09-01

    Full Text Available Analysis of the various nuclear reactions for the production of radionuclide 82Sr was performed and optimum process for the production of this radionuclide was determined. Proton beam energy range for minimizing 85Sr impurity was also determined. The thickness of the RbCl target was calculated.

  7. Cooling age of the Birimian juvenile crust in West Africa. U-Pb, Rb-Sr and K-Ar data on the 2.1 Ga granite-greenstone terrains from SW-Niger

    International Nuclear Information System (INIS)

    Lama, C.; Dautel, D.; Zimmermann, J.L.; Cheilletz, A.; Pons, J.

    1994-01-01

    A comparison between zircon U-Pb, whole-rock Rb-Sr and biotite-amphibole K-Ar data on Birimian granite-greenstone terrains from SW-Niger indicates that the youngest granitic plutons were emplaced at 2.115 ± 5 Ma and that both the plutons and the surrounding greenstones yield cooling ages around 2.118 Ma. The age similarity between the end of the plutonism and the cooling of plutons and surrounding greenstone further suggests rapid cooling at the end of the plutonic event and, thus, corroborates a model of greenstone metamorphism linked to the thermal effect of the plutons. (authors)

  8. Density heterogeneity of the cratonic lithosphere

    DEFF Research Database (Denmark)

    Cherepanova, Yulia; Artemieva, Irina

    2015-01-01

    Using free-board modeling, we examine a vertically-averaged mantle density beneath the Archean-Proterozoic Siberian craton in the layer from the Moho down to base of the chemical boundary layer (CBL). Two models are tested: in Model 1 the base of the CBL coincides with the LAB, whereas in Model 2...... the base of the CBL is at a 180 km depth. The uncertainty of density model is density structure of the Siberian lithospheric mantle with a strong...... correlation between mantle density variations and the tectonic setting. Three types of cratonic mantle are recognized from mantle density anomalies. 'Pristine' cratonic regions not sampled by kimberlites have the strongest depletion with density deficit of 1.8-3.0% (and SPT density of 3.29-3.33 t/m3...

  9. Sources and mobility of carbonate melts beneath cratons, with implications for deep carbon cycling, metasomatism and rift initiation

    Science.gov (United States)

    Tappe, Sebastian; Romer, Rolf L.; Stracke, Andreas; Steenfelt, Agnete; Smart, Katie A.; Muehlenbachs, Karlis; Torsvik, Trond H.

    2017-05-01

    Kimberlite and carbonatite magmas that intrude cratonic lithosphere are among the deepest probes of the terrestrial carbon cycle. Their co-existence on thick continental shields is commonly attributed to continuous partial melting sequences of carbonated peridotite at >150 km depths, possibly as deep as the mantle transition zone. At Tikiusaaq on the North Atlantic craton in West Greenland, approximately 160 Ma old ultrafresh kimberlite dykes and carbonatite sheets provide a rare opportunity to study the origin and evolution of carbonate-rich melts beneath cratons. Although their Sr-Nd-Hf-Pb-Li isotopic compositions suggest a common convecting upper mantle source that includes depleted and recycled oceanic crust components (e.g., negative ΔεHf coupled with > + 5 ‰ δ7Li), incompatible trace element modelling identifies only the kimberlites as near-primary low-degree partial melts (0.05-3%) of carbonated peridotite. In contrast, the trace element systematics of the carbonatites are difficult to reproduce by partial melting of carbonated peridotite, and the heavy carbon isotopic signatures (-3.6 to - 2.4 ‰ δ13C for carbonatites versus -5.7 to - 3.6 ‰ δ13C for kimberlites) require open-system fractionation at magmatic temperatures. Given that the oxidation state of Earth's mantle at >150 km depth is too reduced to enable larger volumes of 'pure' carbonate melt to migrate, it is reasonable to speculate that percolating near-solidus melts of carbonated peridotite must be silicate-dominated with only dilute carbonate contents, similar to the Tikiusaaq kimberlite compositions (e.g., 16-33 wt.% SiO2). This concept is supported by our findings from the North Atlantic craton where kimberlite and other deeply derived carbonated silicate melts, such as aillikites, exsolve their carbonate components within the shallow lithosphere en route to the Earth's surface, thereby producing carbonatite magmas. The relative abundances of trace elements of such highly

  10. The electrical lithosphere in Archean cratons: examples from Southern Africa

    Science.gov (United States)

    Khoza, D. T.; Jones, A. G.; Muller, M. R.; Webb, S. J.

    2011-12-01

    The southern African tectonic fabric is made up of a number Archean cratons flanked by Proterozoic and younger mobile belts, all with distinctly different but related geological evolutions. The cratonic margins and some intra-cratonic domain boundaries have played major roles in the tectonics of Africa by focusing ascending magmas and localising cycles of extension and rifting. Of these cratons the southern extent of the Congo craton is one of the least-constrained tectonic boundaries in the African tectonic architecture and knowledge of its geometry and in particular the LAB beneath is crucial for understanding geological process of formation and deformation prevailing in the Archean and later. In this work, which forms a component of the hugely successful Southern African MagnetoTelluric Experiment (SAMTEX), we present the lithospheric electrical resistivity image of the southern boundary of the enigmatic Congo craton and the Neoproterozoic Damara-Ghanzi-Chobe (DGC) orogenic belt on its flanks. Magnetotelluric data were collected along profiles crossing all three of these tectonic blocks. The two dimensional resistivity models resulting from inverting the distortion-corrected responses along the profiles all indicate significant lateral variations in the crust and upper mantle structure along and across strike from the younger DGC orogen to the older adjacent craton. The are significant lithospheric thickness variations from each terrane. The The Moho depth in the DGC is mapped at 40 km by active seismic methods, and is also well constrained by S-wave receiver function models. The Damara belt lithosphere, although generally more conductive and significantly thinner (approximately 150 km) than the adjacent Congo and Kalahari cratons, exhibits upper crustal resistive features interpreted to be caused by igneous intrusions emplaced during the Gondwanan Pan-African magmatic event. The thinned lithosphere is consistent with a 50 mW.m-2 steady-state conductive

  11. Studies of inelastic cross-section in Rb(7S) + Rb(5S) collisions

    International Nuclear Information System (INIS)

    Caiyan, L.; Ekers, A.; Latvia Univ., Riga; Klavins, J.; Jansons, M.

    1996-01-01

    The cross section σ = (8 ± 4) x 10 -15 cm 2 was determined for the Rb(7S) + Rb(5S) → Rb(5D) + Rb(5S) excitation energy transfer process, and the quenching cross section σ q = (2 ± 1) x 10 -14 cm 2 for the Rb(5D) state in collisions with ground state Rb atoms. Applying rubidium quasimolecular asymptotic potential curves at relatively large internuclear distances, a qualitative interpretation of the experimental results is presented. It is shown that the quenching of the Rb(5D) atoms in collisions may be explained by a reversed energy pooling process Rb(5D) + Rb(5S) → Rb(5P) + Rb(5P). (orig.)

  12. Ab Initio Study of Chemical Reactions of Cold SrF and CaF Molecules with Alkali-Metal and Alkaline-Earth-Metal Atoms: The Implications for Sympathetic Cooling.

    Science.gov (United States)

    Kosicki, Maciej Bartosz; Kędziera, Dariusz; Żuchowski, Piotr Szymon

    2017-06-01

    We investigate the energetics of the atom exchange reaction in the SrF + alkali-metal atom and CaF + alkali-metal atom systems. Such reactions are possible only for collisions of SrF and CaF with the lithium atoms, while they are energetically forbidden for other alkali-metal atoms. Specifically, we focus on SrF interacting with Li, Rb, and Sr atoms and use ab initio methods to demonstrate that the SrF + Li and SrF + Sr reactions are barrierless. We present potential energy surfaces for the interaction of the SrF molecule with the Li, Rb, and Sr atoms in their energetically lowest-lying electronic spin states. The obtained potential energy surfaces are deep and exhibit profound interaction anisotropies. We predict that the collisions of SrF molecules in the rotational or Zeeman excited states most likely have a strong inelastic character. We discuss the prospects for the sympathetic cooling of SrF and CaF molecules using ultracold alkali-metal atoms.

  13. Evidences of a transamazonic cycle in Cabo Frio region, RJ, Brazil and its correlation with the craton of Angola, Africa

    International Nuclear Information System (INIS)

    Zimbres, E.; Kawashita, K.; Van Schmus, W.R.

    1990-01-01

    The U-Pb dating in zircon based on air-abrasion method, whole rock Rb-Sr one, and K-Ar ones in biotite and amphibole of the samples collected from the Cabo Frio Region, Ribeira Orogenic Belt, have been carried out. The concordia diagram of the U-Pb dating indicates 2 different ages: 1981 ± 18 Ma for the upper intersect corresponding to the Transamazonic Cycle, and 488 ± 55 Ma for the lower one, Brazilian Cycle. The former is interpreted as age of zircon formation and the latter, as the time elapsed since epsodic lead loss. The whole rock Rb-Sr dating also shows Transamazonic age: 1799 ± 62 Ma, IR=0.706, and MSWD+0.570. The K-Ar age in amphibole is 571 ± 44 Ma and that in biotite is 474 ± 6 Ma. These data lead to the conclusion that the rocks of this region was formed in the Trasamazonic Cycle and remetamorphosed in the Brazilian Cycle. (author)

  14. U-Pb and Rb-Sr geochronology of the Wedgeport granitoid pluton, southwestern Nova Scotia

    International Nuclear Information System (INIS)

    Cormier, R.F.; Keppie, J.D.; Odom, A.L.

    1988-01-01

    Zircons from biotite monzogranite of the Wedgeport Pluton, intrusive into deformed metasediments of the Cambrian(?) Goldenville formation in the southwestern Meguma Terrane of Nova Scotia, yield concordant U-Pb ages of 316 ± 5 Ma. This is interpreted as the time of intrusion and crystallization. Within the error limits, the 323 ± 0.0056 Rb-Sr analyses of mineral separates of biotite, potassium feldspar, and quartz-plagioclase from several samples yield subparallel, internal isochrons with an average age of 257 ± 8 Ma. Initial ratios of the internal isochrons range from 0.716 to 0.759. A slow-cooling model for the latter data is discarded because the mineral data fall on straight lines. Instead, a reheating event related to plutonism ca 257 Ma ago, which was sufficient to cause local grain-to-grain migration and reequilibration of strontium and rubidium but not large-scale redistribution, is invoked. This reheating is also inferred to be responsible for the hydrothermal alteration and Sn-U mineralization concentrated along the northwestern margin of the pluton. A dextral northeast-southeast shear zone cutting the pluton is also inferred to be ca. 257 Ma old. It may be related to the last stages of westward abduction of the Meguma Terrane. These results provide a clear example of Permo-Carboniferous plutonism in the southwestern Meguma Terrane and suggest a similar interpretation may apply to other anomalously young ages recorded in this area. In light of these results, the Permo-Carboniferous age of the large East Kemptville tin deposit and its location in a dextral shear zone suggest that the association of younger plutonism and shear zones may be a significant factor for economic mineralization. (22 refs., 4 tabs., 3 figs.)

  15. Development of positron emitting radionuclides for imaging with improved positron detectors. [/sup 82/Rb, /sup 62/Zn, /sup 64/Cu, /sup 67/Ga

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Y.

    1976-10-01

    Recent advances in positron cameras and positron ring detectors for transverse section reconstruction have created renewed interest in positron emitting radionuclides. This paper reports on: generator-produced /sup 82/Rb; cyclotron-produced /sup 62/Zn; and reactor-produced /sup 64/Cu. Investigation of the /sup 82/Sr (25 d)--/sup 82/Rb (75 s) generator determined the elution characteristics for Bio-Rex 70, a weakly acidic carboxylic cation exchanger, using 2% NaCl as the eluent. The yield of /sup 82/Rb and the breakthrough of /sup 82/Sr were determined for newly prepared columns and for long term elution conditions. Spallation-produced /sup 82/Sr was used to charge a compact /sup 82/Rb generator to obtain multi-millicurie amounts of /sup 82/Rb for myocardial imaging. Zinc accumulates in the islet cells of the pancreas and in the prostate. Zinc-62 was produced by protons on Cu foil and separated by column chromatography. Zinc-62 was administered as the amino acid chelates and as the ZnCl/sub 2/ to tumor and normal animals. Tissue distribution was determined for various times after intravenous injection. Pancreas-liver images of /sup 62/Zn-histidine uptake were obtained in animals with the gamma camera and the liver uptake of /sup 99m/Tc sulfur colloid was computer subtracted to image the pancreas alone. The positron camera imaged uptake of /sup 62/Zn-histidine in the prostate of a dog at 20 h. /sup 64/Cu was chelated to asparagine, a requirement of leukemic cells, and administered to lymphoma mice. Uptake in tumor and various tissues was determined and compared with the uptake of /sup 67/Ga citrate under the same conditions. /sup 64/Cu-asparagine had better tumor-to-soft tissue ratios than /sup 67/Ga-citrate.

  16. Research reactor RB, technical characteristics and experimental possibilities

    International Nuclear Information System (INIS)

    Sotic, O.; Vranic, S.

    1978-01-01

    Nuclear research reactor RB tn the Nuclear Engineering Laboratory at the Institute of Nuclear Sciences 'Boris Kidric' in Vinca is the first reactor system built in Yugoslavia in 1958. In this report, the basic technical characteristics of this reactor are described, as well as the experimental possibilities it offers to the users. Its relatively simple construction and flexibility enables direct measurements of a series of physical parameters, and the absence of the biological protection shield makes it very useful for Various biological and other irradiations and dosimetric measurements Where strong neutron source is required. (author) [sr

  17. Rb-Sr isochronous of the alkaline volcanoes from the Bonin-Mariana tectonics zone (Pacific Ocean)

    International Nuclear Information System (INIS)

    Govorov, I.N.; Gerasimov, N.S.; Tatarin, I.A.

    1996-01-01

    Description of petrogeochemical peculiarities of rocks of the Bonin-Mariana tectonic zone (Pacific Ocean) and the results on the dating of the alkaline volcanoes are presented. The established age of the Kadzan volcano equals approximately 138 ± 30 mln years; the initial ratio 87 Sr/ 86 Sr) 0 is equal to 0.70275 ± 0.0047. The age of the Ramapo complex constitutes 4 ± 66 mln years; the initial ratio ( 87 Sr/ 86 Sr) 0 equals 0.70313 ± 0.00045 [ru

  18. The land Piedra Alta : A geotectonic unit in the juvenile Paleoproterozoic craton del Rio de la Plata ( Uruguay )

    International Nuclear Information System (INIS)

    Preciozzi, F.; Sanchez Bettucci, L.; Oyhantcabal, P.; Pecoits, E.; Aubet, N.; Peel, E.; Basei, M.

    2003-01-01

    Brazilian Shield (Rio Grande do Sul) where Paleoproterozoic os land, located in the region Western, are covered by Paleozoic sediments of the Paraná Basin. The Neoproterozoic domains develop east of the Precambrian shield of Uruguay. The Exceptions to this comparative correlation are represented by the Campanero Unit and Field Suspect Punta del Este, only identified in Uruguayan territory. The Piedra Alta (Río de la Plata Craton, ss.) Is composed of a complex gneissic-migmatítico plant, essentially composed of porphyritic foliated granitoids interspersed with different types of mafic rocks Paleoproterozoicas Migmatites and, at least in the southern portion, where four metamorphic belts of different degree and extent are interleaved (Montevideo, San Jose, Cerros de San Juan and Arroyo Grande). Granites, granodiorites, and bodies mafic, of different composition, age and location environment are intruding the whole ground. The last magmatic activity is represented by a swarm of dykes aged mafic ca. 1750 - 1790 Ma (Bossi and Pitched, 1991, Halls et al., 2001) and meta tuffs acid intercalated in the Belt of Los Cerros de San Juan whose ages by the method U / Pb located in the vicinity of 1753 ± 5 Ma (Preciozzi et al, in prep.). The Piedra Alta Terrane no evidence of being affected by events tectonotérmicos Neoproterozoic and is separated from the Block Valentines by the shear zone Sarandi del Yi (Preciozzi et al., 1979). From geochronological studies U / Pb, Rb / Sr, K / Ar and Sm / Nd recent, carried out on the rocks Intrusive and Piedra Alta Land gneisses, it has been possible to observe a set of events that They affected the Land

  19. Beta-delayed proton decay of 73Sr

    International Nuclear Information System (INIS)

    Batchelder, J.C.; Moltz, D.M.; Ognibene, T.J.; Rowe, M.W.; Tighe, R.J.; Cerny, J.

    1993-01-01

    The T z =-3/2, A=4n+1 nuclide 73 Sr produced in the 40 Ca( 36 Ar,3n) reaction has been observed via beta-delayed proton emission. A single proton group at a laboratory energy of 3.75±0.04 MeV has been observed, corresponding to decay of the T=3/2 isobaric analog state in 73 Rb to the ground state of 72 Kr. Combining this measurement with a Coulomb displacement energy calculation yields a mass excess for 73 Sr of -31.82±0.24 MeV based on a predicted mass for 72 Kr of -53.94±0.24 MeV

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

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  1. Sr isotopic tracer study of the Samail ophiolite, Oman

    International Nuclear Information System (INIS)

    Lanphere, M.A.; Coleman, R.G.; Hopson, C.A.

    1981-01-01

    We have measured Rb and Sr concentrations and Sr isotopic compositions in 41 whole-rock samples and 12 mineral separates from units of the Samail ophiolite, including peridotite, gabbro, plagiogranite diabase dikes, and gabbro and websterite dikes within the metamorphic peridotite. Ten samples of cummulate gabbro from the Wadir Kadir section and nine samples from the Wadi Khafifah section have mean 87 Sr/ 86 Sr ratios and standard deviations of 0.70314 +- 0.00030 and 0.70306 +- 0.00034, respectively. The dispersion in Sr isotopic composition may reflect real heterogeneities in the magma source region. The average Sr isotopic composition of cumulate gabbro falls in the range of isotopic compositions of modern midocean ridge basalt. The 87 Sr/ 86 Sr ratios of noncumulate gabbro, plagiogranite, and diabase dikes range from 0.7034 to 0.7047, 0.7038 to 0.7046, and 0.7037 to 0.7061, respectively. These higher 87 Sr/ 86 Sr ratios are due to alteration of initial magmatic compositions by hydrothermal exchange with seawater. Mineral separates from dikes that cut harzburgite tectonite have Sr isotopic compositions which agree with that of cumulate gabbro. These data indicate that the cumulate gabbro and the different dikes were derived from partial melting of source regions that had similar long-term histories and chemical compositions

  2. Magnetic anomalies across Bastar craton and Pranhita–Godavari ...

    Indian Academy of Sciences (India)

    Such intrusions can be explained considering the collision of the Bastar and Dharwar cratons by the ... that there was no imprint of magnetization of a later date, it is concluded that the Indian plate was located in the .... swarms, that occur in this craton. Thus the .... b, c and d, needed to explain the anomalies along with the ...

  3. Petrological study of the eastern part of Rio Maria batholith located in the SE of Para State

    International Nuclear Information System (INIS)

    Medeiros, H. de.

    1987-01-01

    This work is a petrological and geochronological study in the eastern part of Rio Maria batholith located in the SE of Para State (Brazil), in which granodioritic composition predominates. Selected samples including all varieties present in the eastern portion of Rio Maria granodioritic batholith were analyzed for major, minor and some trace elements. The results suggest two differentiation trends. The first is (BHGd + HBGd) - HBM sub(z)G, with decrease in CaO, TiO sub(2), Fe total, MgO and Sr contents, whereas K2O and Rb increase. The second trend is (BHGd + HBGd) - BGd, where the BGd have the highest values of SiO sub(2), and low CaO, TiO sub(2), Fe total, MgO and Sr contents. This results are in agreement with that obtained to the calc-alkaline rock series. Six selected samples, including all varieties, were dated by the Rb/Sr Whole-rock method, producing a isochronic age of 2564 +- 68 m.y. with an initial Sr sup(87)/Sr sup(86) ratio of 0.70288 +- 00092. The crystallization sequence proposed to the BHGd and BHGd, when correlated to the experimental results obtained in the rocks of granodioritic composition, suggests that the magma crystallization was in low pressure conditions (2 to 4kb). The temperature interval would be between 950 and +- 700 sup(0)C. The best explanation to the granodioritic magma origin is by partial fusion in the crustal base, with contribution of mantle material or not. The association of the rock units, including granodiorites, trondhjemites, meta-volcan-sedimentary sequences and gneisses of tonalitic to granodioritic composition observed in the Rio Maria region, and the Archaeyan ages obtained by the Rb/Sr method suggest that this region can be correlated with granite-greenstone terrains exposed in the Rhodesian, Kaapvaal and western Australia cratons. (author)

  4. Re-Os dating of molybdenites from Southern India: implication for Pan-African metallogeny

    International Nuclear Information System (INIS)

    Santosh, M.; Suzuki, Katsuhiko; Masuda, Akimasa

    1994-01-01

    Rhenium-osmium (Re-Os) dating of two molybdenite samples from the alkali granite and pegmatite of Ambalavayal in northern Kerala (S. India) yielded ages of 567 ±28 Ma and 566±77 Ma, respectively. These ages closely compare with the previously determined Rb-Sr whole rock age of 595±20 Ma Rb-Sr for granite, and K-Ar biotite age of 560±30 Ma for the pegmatite. Our study provides the first direct determination of the timing of ore mineralization associated with felsic magmatism in southern India, and reveals the fingerprints of a prominent Pan-African metallogenic event. This timing coincides with the formation of rare metal and gemstone-bearing pegmatites in different parts of southern India, Sri Lanka, Madagascar and East Antarctica. In most cases, the mineralizations are genetically related to felsic magmas emplaced along structural conduits, suggesting that the magmatism and metallogeny are related to deep-seated extension in the cratonized crustal segments of the Gondwana assembly. (author). 20 refs., 3 figs., 1 tab

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

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  6. EVOLUTION OF SOUTHERN AFRICAN CRATONS BASED ON SEISMIC IMAGING

    DEFF Research Database (Denmark)

    Thybo, Hans; Soliman, Mohammad Youssof Ahmad; Artemieva, Irina

    2014-01-01

    present a new seismic model for the structure of the crust and lithospheric mantle of the Kalahari Craton, constrained by seismic receiver functions and finite-frequency tomography based on the seismological data from the South Africa Seismic Experiment (SASE). The combination of these two methods...... since formation of the craton, and (3) seismically fast lithospheric keels are imaged in the Kaapvaal and Zimabwe cratons to depths of 300-350 km. Relatively low velocity anomalies are imaged beneath both the paleo-orogenic Limpopo Belt and the Bushveld Complex down to depths of ~250 km and ~150 km...

  7. Evaluation of blood--brain barrier permeability changes in rhesus monkeys and man using 82Rb and positron emission tomography

    International Nuclear Information System (INIS)

    Yen, C.K.; Budinger, T.F.

    1981-01-01

    Dynamic positron tomography of the brain with 82 Rb, obtained from a portable generator [ 82 Sr (25 days) -- 82 Rb (76 sec)], provides a means of studying blood-brain barrier (BBB) permeability in physiological and clinical investigations. The BBB in rhesus monkeys was opened unilaterally by intracarotid infusion of 3 M urea. This osmotic barrier opening allowed entry into the brain of intravenously administered rubidium chloride. The BBB opening was demonstrated noninvasively using 82 Rb and positron emission tomography and corroborated by the accumulation of 86 Rb in tissue samples. Positron emission tomography studies can be repeated every 5 min and indicate that dynamic tomography or static imaging can be used to study BBB permeability changes induced by a wide variety of noxious stimuli. Brain tumors in human subjects are readily detected because of the usual BBB permeability disruption in and around the tumors

  8. Sr and Ar isotope studies of detrital smectites from the Atlantic Ocean (D.S.D.P., Legs 43, 48 and 50)

    International Nuclear Information System (INIS)

    Clauer, N.; Lucas, J.

    1984-01-01

    Mineralogical, morphological and isotopic (Rb-Sr and K-Ar) determinations were made on some detrital smectites of Palaeocene and Cenomanian ages from D.S.D.P. drillings in the Atlantic Ocean. These minerals are not inert in their depositional environment; authigenic laths grow on detrital sheets with sharp borders. This authigenesis could occur slightly after deposition in a closed system, for some of these smectites. It has been tentatively quantified by the Rb-Sr and K-Ar isotopic methods, which seem also well suited to evaluate the chemical extent of this authigenesis. At least, no preferential loss of 40 Ar vs. 87 Sr could be detected in the minerals, even in those which are smaller than 0.2 μm. (Auth.)

  9. Formation of cratonic lithosphere: An integrated thermal and petrological model

    Science.gov (United States)

    Herzberg, Claude; Rudnick, Roberta

    2012-09-01

    The formation of cratonic mantle peridotite of Archean age is examined within the time frame of Earth's thermal history, and how it was expressed by temporal variations in magma and residue petrology. Peridotite residues that occupy the lithospheric mantle are rare owing to the effects of melt-rock reaction, metasomatism, and refertilization. Where they are identified, they are very similar to the predicted harzburgite residues of primary magmas of the dominant basalts in greenstone belts, which formed in a non-arc setting (referred to here as "non-arc basalts"). The compositions of these basalts indicate high temperatures of formation that are well-described by the thermal history model of Korenaga. In this model, peridotite residues of extensive ambient mantle melting had the highest Mg-numbers, lowest FeO contents, and lowest densities at ~ 2.5-3.5 Ga. These results are in good agreement with Re-Os ages of kimberlite-hosted cratonic mantle xenoliths and enclosed sulfides, and provide support for the hypothesis of Jordan that low densities of cratonic mantle are a measure of their high preservation potential. Cratonization of the Earth reached its zenith at ~ 2.5-3.5 Ga when ambient mantle was hot and extensive melting produced oceanic crust 30-45 km thick. However, there is a mass imbalance exhibited by the craton-wide distribution of harzburgite residues and the paucity of their complementary magmas that had compositions like the non-arc basalts. We suggest that the problem of the missing basaltic oceanic crust can be resolved by its hydration, cooling and partial transformation to eclogite, which caused foundering of the entire lithosphere. Some of the oceanic crust partially melted during foundering to produce continental crust composed of tonalite-trondhjemite-granodiorite (TTG). The remaining lithosphere gravitationally separated into 1) residual eclogite that continued its descent, and 2) buoyant harzburgite diapirs that rose to underplate cratonic nuclei

  10. The Role of Water in the Stability of Cratonic Keels

    Science.gov (United States)

    Peslier, Anne H.; Woodland, Alan B.; Bell, David R.; Lazarov, Marina

    2011-01-01

    Cratons are typically underlain by large, deep, and old lithospheric keels (to greater than 200 km depth, greater than 2.5 Ga old) projecting into the asthenosphere (e.g., Jordan, 1978; Richardson et al., 1984). This has mystified Earth scientists as the dynamic and relatively hot asthenosphere should have eroded away these keels over time (e.g., Sleep, 2003; O'Neill et al., 2008; Karato, 2010). Three key factors have been invoked to explain cratonic root survival: 1) Low density makes the cratonic mantle buoyant (e.g., Poudjom Djomani et al., 2001). 2) Low temperatures (e.g., Pollack, 1986; Boyd, 1987), and 3) low water contents (e.g., Pollack, 1986), would make cratonic roots mechanically strong. Here we address the mechanism of the longevity of continental mantle lithosphere by focusing on the water parameter. Although nominally anhydrous , olivine, pyroxene and garnet can accommodate trace amounts of water in the form of H bonded to structural O in mineral defects (e.g., Bell and Rossman, 1992). Olivine softens by orders of magnitude if water (1-1000 ppm H2O) is added to its structure (e.g., Mackwell et al., 1985). Our recent work has placed constraints on the distribution of water measured in peridotite minerals in the cratonic root beneath the Kaapvaal in southern Africa (Peslier et al., 2010). At P greater than 5 GPa, the water contents of pyroxene remain relatively constant while those of olivine systematically decrease from 50 to less than 10 ppm H2O at 6.4 GPa. We hypothesized that at P greater than 6.4 GPa, i.e. at the bottom of the cratonic lithosphere, olivines are essentially dry (greater than 10 ppm H2O). As olivine likely controls the rheology of the mantle, we calculated that the dry olivines could be responsible for a contrast in viscosity between cratonic lithosphere and surrounding asthenosphere large enough to explain the resistance of cratonic root to asthenospheric delamination.

  11. Identification of the neutron-rich nuclides /sup 147; 148/Ba and half- life determination of the heavy isotopes of Rb, Sr, Y, Cs, Ba and La

    CERN Document Server

    Amiel, S; Nir-El, Y; Shmid, M

    1976-01-01

    The neutron nuclides /sup 147; 148/Ba were produced in the thermal neutron induced fission of /sup 235/U. A new surface ionization integrated target ion source operating at temperatures in the region of 1800 degrees C permits the measurement of half-lives of isotopes down to about 0.1 sec due to the very fast release of atoms from the target. Isotopes of Rb, Sr, Cs, and Ba were separated by positive surface ionization and their half-lives measured using beta activity detected by a silicon surface barrier detector with a depletion depth of 300 mu . The isotopes /sup 147/Ba and /sup 148/Ba were identified for the first time and their half-lives were found to be 0.72+or-0.07 sec and 0.47+or-0.20 sec, respectively. (0 refs).

  12. Le craton ouest-africain et le bouclier guyanais: un seul craton au Protérozoïque inférieur?

    Science.gov (United States)

    Caen-Vachette, Michelle

    Geochronological and paleomagnetism data for southern West African craton and Guyana shield in South America, are concordant and suggest the existence of a large unit grouping them during Archean and Lower Proterozoic times. The paleomagnetism data allow to put on a single line, the Zednes (Mauritania), Sassandra (Ivory Coast) and Guri (Venezuela) fault zones, the mylonites of which were dated 1670 Ma. This age reflects the end of the eburnean-transamazonian shearing tectonic, which affected the large West Africa-Guyana unit. This line separates the western Archean domain from the eastern lower Proterozoic one; thence it is possible to correlate the Sasca (Ivory Coast) and Pastora (Venezuela) areas. Archean relics have been found in mobile pan-african-bresiliano zones which surround the Precambrian cratons; this fact suggests the existence of still more extended Archean craton than defined above.

  13. Comparative kinetic analysis of89 Sr,60 Co and65 Zn Uptake by human bone powder

    International Nuclear Information System (INIS)

    Abdel-Fatah, A.T.A.; Essa, M.W.A.; Mohamed, S.A.; Molokhia, M.K.

    1990-01-01

    Human bone powder samples were prepared from recent femurs. The Bone particles range between 30 and 40 MU in diameter. One portion of this powder was prepared fat-free (FFB), the second portion as protein-free (PFB) and the last portion was left as raw bone powder-(RB). The sequence of uptake of 89 Sr by these types of bone powder is : FFB > RB > PFB, while that of 60 Co and 65 Zn is: PFB > FFB > RB. Kinetic analysis of the uptake curves of the 3 isotopes indicated that these processes proceed in 3 distinct steps; very fast initial, moderate intermediate and slow last step. The obtained rates of uptake indicated that : (1) the uptake by PEB is faster in its third step than the other types, (2) the most predominant step in case of 89 Sr and 60 Co is the third step (ion exchange step) while in case of 65 Zn it is the first step (physical adsorption), (3) defatenisation or deproteinisation, in general, inhances the uptake process

  14. The 3-dimensional construction of the Rae craton, central Canada

    Science.gov (United States)

    Snyder, David B.; Craven, James A.; Pilkington, Mark; Hillier, Michael J.

    2015-10-01

    Reconstruction of the 3-dimensional tectonic assembly of early continents, first as Archean cratons and then Proterozoic shields, remains poorly understood. In this paper, all readily available geophysical and geochemical data are assembled in a 3-D model with the most accurate bedrock geology in order to understand better the geometry of major structures within the Rae craton of central Canada. Analysis of geophysical observations of gravity and seismic wave speed variations revealed several lithospheric-scale discontinuities in physical properties. Where these discontinuities project upward to correlate with mapped upper crustal geological structures, the discontinuities can be interpreted as shear zones. Radiometric dating of xenoliths provides estimates of rock types and ages at depth beneath sparse kimberlite occurrences. These ages can also be correlated to surface rocks. The 3.6-2.6 Ga Rae craton comprises at least three smaller continental terranes, which "cratonized" during a granitic bloom. Cratonization probably represents final differentiation of early crust into a relatively homogeneous, uniformly thin (35-42 km), tonalite-trondhjemite-granodiorite crust with pyroxenite layers near the Moho. The peak thermotectonic event at 1.86-1.7 Ga was associated with the Hudsonian orogeny that assembled several cratons and lesser continental blocks into the Canadian Shield using a number of southeast-dipping megathrusts. This orogeny metasomatized, mineralized, and recrystallized mantle and lower crustal rocks, apparently making them more conductive by introducing or concentrating sulfides or graphite. Little evidence exists of thin slabs similar to modern oceanic lithosphere in this Precambrian construction history whereas underthrusting and wedging of continental lithosphere is inferred from multiple dipping discontinuities.

  15. New internal standard method for activation analysis and its application. Determination of Co, Ni, Rb, Sr in pepperbush by means of photon activation

    Energy Technology Data Exchange (ETDEWEB)

    Yagi, M.; Masumoto, K. (Tohoku Univ., Sendai (Japan). Lab. of Nuclear Science)

    1984-08-01

    A new internal standard method for activation analysis has been developed. In this method a suitable element present originally in the sample is used as an internal standard and the comparative standard is prepared by applying the standard addition method to the duplicated sample. The present method has the great advantages that the comparative standard spiked with the element of interest has the same matrix as the sample, and then the amount of the element to be determined in the sample can be evaluated easily by using a very simple equation even though the sample and comparative standard are irradiated separately by particles with different flux. Neither correction of the inhomogeneities of flux between the sample and comparative standard, nor that of the self-shielding effects are necessary for the present method. The usefulness of the method was examined through the determination of Co, Ni, Rb and Sr in pepperbush by means of photon activation, and the precision and accuracy of the method were proved to be valid. 29 refs.

  16. Isotopic strontium, carbon and oxygen study on neoproterozoic marbles from Sierra de Umango, Andean Foreland, Argentina

    International Nuclear Information System (INIS)

    Varela, R; Valencio, S.; Ramos, A; Sato, K; Gonzalez, P; Panarello, H; Roverano, D

    2001-01-01

    The Umango Hill (La Rioja Province, 29 o 00'S-68 o 40'W) is one of the mountain blocks of Sierras Pampeanas Occidentales (Caminos, 1979), bounded by thrust faults and surrounded by Upper Devonian to Tertiary marine and continental sedimentites. The exposed crystalline basement is composed of basic igneous rocks and a siliciclastic-limestone sequence, both affected by amphibolite facies metamorphic peak. In the southern area (Juchi creek), the metamorphic complex carries relics of granitic orthogneisses, with Rb/Sr and U/Pb dates of ∼1000 Ma (Varela et al., 1996). These ancient inliers were asigned to a Mesoproterozoic Grenville Orogenic Cycle. Granitic bodies, intrusives at different ages in the Metamorphic Complex, have also been distinguished. The most ancient is El Penon Granite, with 469±9 Ma Rb/Sr age (Varela et al., 2000) and 523±26 Ma U/Pb zircon age (unpublished data). In this way it is possible to point out broadly that the siliciclastic-limestone sequence belongs to the Neoproterozoic-Early Palaeozoic times. It was a platform cover over grenvillian cratonic basement. The metamorphism and deformation, we understand, took place in the Early Palaeozoic, related to the Pampean-Famatinian Orogenic Cycle. In this work, compositional and isotopic data of Strontium ( 87 Sr/ 86 Sr), Carbon (δ 13 Cv PDB ) and Oxygen (δ 18 Ov PDB ) of the marbles derived from the siliciclastic-limestone sequence are presented. The results are interpreted and correlated with the temporal variation curves of 87 Sr/ 86 Sr and δ 13 C from Neoproterozoic marine carbonates (Jacobsen and Kaufman, 1999) (au)

  17. Do cratons preserve evidence of stagnant lid tectonics?

    Directory of Open Access Journals (Sweden)

    Derek Wyman

    2018-01-01

    Full Text Available Evidence for episodic crustal growth extending back to the Hadean has recently prompted a number of numerically based geodynamic models that incorporate cyclic changes from stagnant lid to mobile lid tectonics. A large part of the geologic record is missing for the times at which several of these cycles are inferred to have taken place. The cratons, however, are likely to retain important clues relating to similar cycles developed in the Mesoarchean and Neoarchean. Widespread acceptance of a form of plate tectonics by ∼3.2 Ga is not at odds with the sporadic occurrence of stagnant lid tectonics after this time. The concept of scale as applied to cratons, mantle plumes and Neoarchean volcanic arcs are likely to provide important constraints on future models of Earth's geodynamic evolution. The Superior Province will provide some of the most concrete evidence in this regard given that its constituent blocks may have been locked into a stagnant lid relatively soon after their formation and then assembled in the next global plate tectonic interval. Perceived complexities associated with inferred mantle plume – volcanic arc associations in the Superior Province and other cratons may be related to an over estimation of plume size. A possible stagnant lid episode between ∼2.9 Ga and ∼2.8 Ga is identified by previously unexplained lapses in volcanism on cratons, including the Kaapvaal, Yilgarn and Superior Province cratons. If real, then mantle dynamics associated with this episode likely eliminated any contemporaneous mantle plume incubation sites, which has important implications for widespread plumes developed at ∼2.7 Ga and favours a shallow mantle source in the transition zone. The Superior Province provides a uniquely preserved local proxy for this global event and could serve as the basis for detailed numerical models in the future.

  18. RB1CC1 activates RB1 pathway and inhibits proliferation and cologenic survival in human cancer.

    Directory of Open Access Journals (Sweden)

    Tokuhiro Chano

    2010-06-01

    Full Text Available RB1-inducible coiled-coil 1 (RB1CC1, also known as FIP200 plays a role in the enhancement of the RB1 pathway through the direct binding to a GC-rich region 201bp upstream (from the initiation ATG of the RB1 promoter. Here, we identified hSNF5 and p53 as the binding partners of RB1CC1 by immunoprecipitation and immunofluorescence assays. Interaction between these molecules and the RB1 pathway was analyzed by the assays of chromatin immunoprecipitation, luciferase-reporter, reverse transcription-polymerase chain reaction and immunoblot. The tumor growth suppression by RB1CC1 was evaluated by flow cytometry or by a cell growth assay. The nuclear RB1CC1 complex involving hSNF5 and/or p53 activated transcription of RB1, p16 and p21, and suppressed tumor cell growth. Furthermore, nuclear RB1CC1 expression significantly correlated with those of RB1 and p16 in breast cancer tissue in vivo, and the Ki-67 proliferation index was dependent on p53 as well as RB1CC1. The present study indicates that RB1CC1 together with hSNF5 and/or p53 enhances the RB1 pathway through transcriptional activation of RB1, p16 and p21. Evaluation of RB1CC1 expression combined with RB1 and p53 status is expected to provide useful information in clinical practice and future therapeutic strategies in breast cancer.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-15

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

  20. The 1000Ma reassembly of Dharwar and Bastar cratons – Evidence ...

    Indian Academy of Sciences (India)

    8

    2. General Geology. The geology of the study area comprises of the rocks of the Dharwar craton, the ...... Craton-mobile belt relations in in Southern Granulite Terrain. Geol. Soc. .... chemistry: a case study from the Eastern Ghats Belt. India.

  1. Origins of cratonic mantle discontinuities: A view from petrology, geochemistry and thermodynamic models

    Science.gov (United States)

    Aulbach, Sonja; Massuyeau, Malcolm; Gaillard, Fabrice

    2017-01-01

    Geophysically detectible mid-lithospheric discontinuities (MLD) and lithosphere-asthenosphere boundaries (LAB) beneath cratons have received much attention over recent years, but a consensus on their origin has not yet emerged. Cratonic lithosphere composition and origin is peculiar due to its ultra-depletion during plume or accretionary tectonics, cool present-day geothermal gradients, compositional and rheological stratification and multiple metasomatic overprints. Bearing this in mind, we integrate current knowledge on the physical properties, chemical composition, mineralogy and fabric of cratonic mantle with experimental and thermodynamic constraints on the formation and migration of melts, both below and within cratonic lithosphere, in order to find petrologically viable explanations for cratonic mantle discontinuities. LABs characterised by strong seismic velocity gradients and increased conductivity require the presence of melts, which can form beneath intact cratonic roots reaching to 200-250 km depth only in exceptionally warm and/or volatile-rich mantle, thus explaining the paucity of seismical LAB observations beneath cratons. When present, pervasive interaction of these - typically carbonated - melts with the deep lithosphere leads to densification and thermochemical erosion, which generates topography at the LAB and results in intermittent seismic LAB signals or conflicting seismic, petrologic and thermal LAB depths. In rare cases (e.g. Tanzanian craton), the tops of live melt percolation fronts may appear as MLDs and, after complete lithosphere rejuvenation, may be sites of future, shallower LABs (e.g. North China craton). Since intact cratons are presently tectonomagmatically quiescent, and since MLDs produce both positive and negative velocity gradients, in some cases with anisotropy, most MLDs may be best explained by accumulations (metasomes) of seismically slow minerals (pyroxenes, phlogopite, amphibole, carbonates) deposited during past

  2. Sr-Nd-Pb isotopes of the post-paleozoic magmatism from eastern Paraguay

    International Nuclear Information System (INIS)

    Comin-Chiaramonti, P; Gasparon, M; Gomes, C.B; Antonini, P

    2001-01-01

    The Parana Angola-Namibia igneous province (PAN) is characterized by Early Cretaceous flood tholeiites and tholeiitic dyke swarms associated with alkaline rocks of Early and Late Cretaceous ages, respectively, and with scarce post-Mesozoic magmatic rocks (Comin-Chiaramonti et al., 1997; 1999; Marques et al., 1999). The Eastern Paraguay, at the westernmost side of the Parana Basin, is of special interest because: (1) it is located between two main cratonic blocks, i.e. the southernmost tip of the Amazon Craton, and the northermost exposure of the Rio de La Plata Craton; (2) it was the site of repeated Na-K-alkaline magmatism since Late-Permian-Triassic times (i.e.: 250-240 Ma, Na-alkaline; c. 145 Ma, K-alkaline; 128-126 Ma, K-alkaline; 120-90 Ma, Na-alkaline; 61-33 Ma, Na-alkaline; cf. Comin-Chiaramonti and Gomes, 1996; Comin-Chiaramonti et al., 1999), and of Early Cretaceous tholeiitic magmatism, both low- and high-Ti variants, L-Ti and H-Ti, respectively (133-131 Ma; cf. Marzoli et al., 1999); (3) the younger sodic magmatic rocks are closely associated in space to the potassic analogues (Comin- Chiaramonti et al., 1999). The paper aims discussing the most important Sr- Nd-Pb isotope features of the alkaline and tholeiitic magmas from Eastern Paraguay in comparison with the PAN analogues (au)

  3. Radiochronological age and correlation of proterozoic sediments in Brazil

    International Nuclear Information System (INIS)

    Bonhomme, M.G.; Macedo, M.-H.F.; Filho, A.T.

    1982-01-01

    A review of available Rb-Sr and K-Ar datings obtained on sedimentary sequences, metamorphosed or not, interbedded volcanics and cross-cutting intrusives of the Precambrian of Brazil yields the following conclusions: (1) The Roraima and Rio Fresco Formations, resting upon the Amazonian craton, have been affected by the Trans-Amazonian orogeny and are of Lower Proterozoic age. (2) The Beneficiente Group, in the same region, seems to be of Middle Proterozoic, Lower Riphean age. (3) Upon the Sao Francisco craton, and upon the Lower Proterozoic Rio dos Remedios complex, the Paraguacu Group might be of middle Riphean age and the glacial sequences, Macaubas Group and Bebedouro Formation, date back to between 950 and 1000 Ma. (4) The age of the Bambui and Una Groups, in the same region, remains undetermined. It might be either Upper Riphean, or Upper Riphean and Vendian. (5) The molassic series associated with the Brazilian orogeny are dated back to between the Proterozoic-Phanerozoic boundary and the Ordovician. (Auth.)

  4. The Vendian-Early Palaeozoic sedimentary basins of the East European Craton

    NARCIS (Netherlands)

    Sliaupa, S.; Fokin, P.A.; Lazauskiene, J.; Stephenson, R.A.

    2006-01-01

    Vendian-Early Palaeozoic sedimentation on the East European Craton (EEC) was confined to the cratonic margins with limited intracratonic subsidence. Generally, there are two geodynamic stages involved: in stage 1, basins formed in response to continental break-up processes; in stage 2, basins formed

  5. The Pan-African continental margin in northeastern Africa: Evidence from a geochronological study of granulites at Sabaloka, Sudan

    International Nuclear Information System (INIS)

    Kroener, A.

    1987-01-01

    Ion microprobe zircon ages, a Nd model age and Rb-Sr whole-rock dates are reported from the high-grade gneiss terrain at Sabaloka on the River Nile north of Khartoum, formally considered to be part of the Archaean/early Proterozoic Nile craton. The granulites, which are of both sedimentary and igneous derivation, occur as remnants in migmatites. Detrital zircon ages range from ≅ 1000 to ≅ 2650 Ma and prove the existence of Archaean to late Proterozoic continental crust in the sedimentary source region. The Nd model age for one sedimentary granulite is between 1.26 (T CHUR ) and 1.70 (T DM ) Ga and provides a mean crustal residence age for the sedimentary precursor. Igneous zircons in enderbitic gneiss crystallized at 719±81 Ma ago, an age that also corresponds to severe Pb loss in the detrital zircons and whic probably reflects the granulite event at Sabaloka. The Rb-Sr data indicate isotropic homogenization at about 700 Ma ago in the granulites and severe post-granulite disturbance at ≅ 570 Ma in the migmatites. We associate this disturbance with hydration, retrograde metamorphism and anatexis that produced undeformed granites ≅ 540 Ma ago. The ≅ 700 Ma granulite event at Sabaloka suggests that this part of the Sudan belongs to the Pan-African Mozambique belt while the ancient Nile craton lay farther west. The gneisses studied here may represent the infrastructure of the ancient African continental margin onto which the juvenile arc assemblage of the Arabian-Nubian shield was accreted during intense horizontal shortening and crustal interstacking of a major collision event. (orig.)

  6. 3D Numerical Model of Continental Breakup via Plume Lithosphere Interaction Near Cratonic Blocks: Implications for the Tanzanian Craton

    Science.gov (United States)

    Koptev, A.; Calais, E.; Burov, E. B.; Leroy, S. D.; Gerya, T.

    2014-12-01

    Although many continental rift basins and their successfully rifted counterparts at passive continental margins are magmatic, some are not. This dichotomy prompted end-member views of the mechanism driving continental rifting, deep-seated and mantle plume-driven for some, owing to shallow lithospheric stretching for others. In that regard, the East African Rift (EAR), the 3000 km-long divergent boundary between the Nubian and Somalian plates, provides a unique setting with the juxtaposition of the eastern, magma-rich, and western, magma-poor, branches on either sides of the 250-km thick Tanzanian craton. Here we implement high-resolution rheologically realistic 3D numerical model of plume-lithosphere interactions in extensional far-field settings to explain this contrasted behaviour in a unified framework starting from simple, symmetrical initial conditions with an isolated mantle plume rising beneath a craton in an east-west tensional far field stress. The upwelling mantle plume is deflected by the cratonic keel and preferentially channelled along one of its sides. This leads to the coeval development of a magma-rich branch above the plume head and a magma-poor one along the opposite side of the craton, the formation of a rotating microplate between the two rift branches, and the feeding of melt to both branches form a single mantle source. The model bears strong similarities with the evolution of the eastern and western branches of the central EAR and the geodetically observed rotation of the Victoria microplate. This result reconciles the passive (plume-activated) versus active (far-field tectonic stresses) rift models as our experiments shows both processes in action and demonstrate the possibility of developing both magmatic and amagmatic rifts in identical geotectonic environments.

  7. Electromagnetic evidence of high angle convergence between the Congo and Kalahari cratons in southern Africa

    Science.gov (United States)

    Khoza, D. T.; Jones, A. G.; Muller, M. R.; Miensopust, M. P.; Webb, S. J.; Share, P.

    2010-12-01

    The southern African tectonic fabric is made up of a number Archean cratons flanked by Proterozoic and younger mobile belts, all with distinctly different but related geological evolutions. The cratonic margins and some intra-cratonic domain boundaries have played major roles in the tectonics of Africa by focusing ascending magmas and localising cycles of extension and rifting. Of these cratons the southern extent of the Congo craton is one of the least-constrained tectonic boundaries in the African tectonic architecture and knowledge of its geometry is crucial for understanding geological process of formation and deformation prevailing in the Archean and later. In this work, which forms a component of the hugely successful Southern African MagnetoTelluric Experiment (SAMTEX), we present the first-ever lithospheric electrical resistivity image of the southern boundary of the enigmatic Congo craton and the Neoproterozoic Damara-Ghanzi-Chobe (DGC) orogenic belt on its flanks. The DGC belt is highly complex and records the transpressive collision between the Congo to the north and Kalahari craton to the south. Magnetotelluric data were collected along a profile crossing all three of these tectonic blocks. The two-dimensional resistivity models resulting from inverting the distortion-corrected responses along the profiles all indicate significant lateral variations in the crust and upper mantle structure along and across strike from the younger DGC orogen to the older adjacent craton. The Moho depth in the DGC is mapped at 40 km by active seismic methods, and is also well constrained by S-wave receiver function models. The Damara belt lithosphere, although generally more conductive and significantly thinner (approximately 150 km) than the adjacent Congo and Kalahari cratons, exhibits upper crustal resistive features interpreted to be caused by igneous intrusions emplaced during the Gondwanan Pan-African magmatic event. The thinned lithosphere is consistent with a 50 m

  8. Palaeomagnetism of the Palaeoproterozoic Boonadgin Dyke Suite, Yilgarn Craton: Possible connection with India

    Science.gov (United States)

    Liu, Y.; Li, Z. X.; Pisarevsky, S.; Kirscher, U.; Mitchell, R.; Stark, J. C.

    2017-12-01

    A palaeomagnetic study was carried out on the newly identified 1.9 Ga Boonadgin dyke swarm in the Yilgarn Craton, Western Australia. Ten dykes revealed a high-temperature characteristic remanent magnetisation (ChRM) with dual polarities, directing either SW shallow downward (4 sites) or NE shallow upward (6 sites). Our results reveal that the Yilgarn Craton was at an equatorial palaeolatitude at 1.9 Ga. Meanwhile, a paleopole from the ca. 1.9 Ga Dharwar dykes of South India, supported by a positive baked-contact test, puts India at a similar paleolatitude. The Boonadgin dyke swarm can be interpreted to represent an arm of a radiating dyke swarm that shared the same plume centre with coeval mafic dykes in the Dharwar and Bastar cratons of southern India. We therefore propose that the Western Australia Craton (WAC, consisting of the the Yilgarn and Pilbara cratons) and South India were connected at ca. 1.89 Ga.

  9. What is a craton? How many are there? How do they relate? And how did they form?

    Science.gov (United States)

    Bleeker, W.; Davis, B. W.

    2004-05-01

    What is a craton? A craton is a large, coherent domain of Earth's continental crust that has attained and maintained long-term stability, having undergone little internal deformation, except perhaps near its margins due to interaction with neighbouring terranes. Stable continental crust is an end product of intense magmatic, tectonic, and metamorphic reworking; hence, cratons consist of polydeformed and metamorphosed crystalline and metamorphic rocks (e.g., typically "granite-greenstone terrains" in the most ancient cratons). Reworked crust only becomes a craton once the cumulative tectonic, magmatic, and metamorphic reprocessing has self-organized the crust and underlying lithosphere into a stable density, compositional, and thermal profile. Major late-stage "granite bloom" events play a critical role in attaining such stable lithospheric profiles. Once above average stability has been reached, deformation will be concentrated in adjacent domains with weaker strength profiles. Significant rifting events, assisted by mantle plume activity and mafic dyke swarms, are then needed to break up cratonic lithosphere. Where cratons are exposed, they form "shields" dominated by crystalline and metamorphic rocks; where younger, weakly deformed cover overlies cratonic basement, these areas are referred to as "platforms". Shields and platforms are physiographic terms rather than tectonic entities. Another concept, related but not identical to cratons is that of "structural provinces" and the two are commonly confused. Perhaps there is a slight bias for Archean cratons with buoyant mantle keels to form relatively high-standing areas, thus forming shields. However, large parts of Archean cratons are buried underneath platformal cover. There is no strict age connotation to the term "craton", and implied age depends on context. In a context of mantle keels, diamonds and kimberlites, there often is an implicit tendency to equate cratons with stable crust of Archean age. Elsewhere

  10. New Sm-Nd isotopic data from the Southern Aracuai-Ribeira belt: Parabaiba Do Sul group and associated granitic intrusions

    International Nuclear Information System (INIS)

    Medeiros, Silvia Regina de; Wiedemann, Cristina Maria

    2001-01-01

    The Aracuai-Ribeira belt is a Neoproterozoic orogenic belt extending along the Brazilian Coast, bordering the eastern margin of the Sao Francisco craton (Pedrosa Soares et al., in press). In this work we start unveiling the magmatic source characteristics of the southern Espirito Santo segment of this belt through the use of new Sm-Nd data were obtained from exactly the same sample which Sollner et al. (1991), took their U-Pb and Rb-Sr measurements (the major isotopic informations available up to now) allowing thus a correlation with this previous geochronologic work, contributing for an improvement of the evolution model of the whole belt (au)

  11. RB975242 and RB975201 - Late maturation sugarcane varieties

    Directory of Open Access Journals (Sweden)

    Monalisa Sampaio Carneiro

    2016-11-01

    Full Text Available The sugarcane varieties RB975201 and RB975242 were developed and released for harvest at the end of the season (late maturation in the CentralSouth region of Brazil. In specific environments, these varieties were compared with commercial standards in sugar yield per area. They are resistant to major sugarcane diseases and present the Bru1 gene of resistance to brown rust.

  12. 3-D Structure of the Slave and Rae Cratons Provides Clues to Their Construction

    Science.gov (United States)

    Snyder, D. B.

    2013-12-01

    Deep geologic structures within cratons that make up continental cores were long neglected. Recently acquired geophysical data from large observational arrays and geochemical data resulting from exploration for diamond has now made possible co-registration of large-scale (400-km depth), truly 3-dimensional data sets. P-waves, surface waves and magnetotelluric observations provide 3-D wavespeed and conductivity models. Multi-azimuthal receiver functions map seismic discontinuity surfaces in 3-D. Xenolith suites erupted in kimberlites provide rock samples at key lithospheric depths, albeit at sparsely distributed locations. These multi-disciplinary models are becoming available for several key cratons worldwide; here the deep structure of the Slave and Rae cratons of the Canadian Shield is described. Lithospheric layers with tapered, wedge-shaped margins are common. Slave craton layers are sub-horizontal and indicate construction of the craton core at 2.7 Ga by underthrusting and flat stacking of lithosphere. The central Rae craton has predominantly dipping discontinuities that indicate construction at 1.9 Ga by thrusting similar to that observed in crustal ';thick-skinned' fold-and-thrust belts. 3-D mapping of conductivity and metasomatism, the latter via mineral recrystallization and resetting of isotopic ages, overprints primary structures in both cratons. Distribution of more conductivitve mantle suggests that assumed causative pervasive metasomatism occurs at 100-200 km depths with ';chimneys' reaching to shallower depths, typically in locations where kimberlites or mineralization has occurred.

  13. The age and emplacement of obducted oceanic crust in the Urals from Sm-Nd and Rb-Sr systematics

    International Nuclear Information System (INIS)

    Edwards, R.L.; Wasserburg, G.J.

    1985-01-01

    The Urals contain a 2000 km belt of mafic-ultramafic bodies. The Sm-Nd and Rb-Sr systematics of two of these bodies, the Kempersai Massif in the South Ural Mountains and the Voykar-Syninsky Ophiolite Complex in the Polar Ural Mountains have been examined. These data confirm the hypothesis that these bodies represent fragments of pre-collision oceanic crust and establish constraints on the nature and timing of events in the Uralian Orogeny. Two Kempersai gabbros define Sm-Nd internal isochrons of 397 +- 20 My and 396 +- 33 My with epsilonsub(Nd)(T) = +8.7 -+ 0.6 and +8.4 -+ 1.3, respectively. Whole rock samples of pillow basalt, diabase, gabbros, troctolite, and a metasediment give Sm-Nd values which lie on this isochron indicating that these rocks are genetically related and have an igneous crystallization age of 397 My. Whole rock samples of Voykar-Syninsky diabase, gabbros, and clinopyroxenite give Sm-Nd values which lie on or within proportional 1 epsilon-unit of this isochron indicating an age and epsilonsub(Nd)(T) virtually identical to those of Kempersai. epsilonsub(Nd)(T) for the Kempersai and Voykar-Syninsky mafic samples range from +7.3 to +9.0 with an average value of +8.4. This indicates that the Urals ophiolites are derived from an ancient depleted mantle source and are most plausibly pieces of the oceanic crust and lithosphere. The fact that a metasediment has the same epsilonsub(Nd)(397 My) as the other samples indicates derivation from an oceanic source with negligible continental input. epsilonsub(Nd)(T) for the massifs is proportional 1.5 epsilon-units lower than the average for modern MORBs. (orig./HSI)

  14. Rb-Sr and Sm-Nd isotopic compositions and Petrogenesis of ore-related intrusive rocks of gold-rich porphyry copper Maherabad prospect area (North of Hanich), east of Iran

    International Nuclear Information System (INIS)

    Malekzadeh Shafaroudi, A.; Karimpour, M. H.; Mazaheri, S. A.

    2010-01-01

    The Maherabad gold-rich porphyry copper prospect area is located in the eastern part of Lut block, east of Iran. This is the first porphyry Cu-Au prospecting area which is discovered in eastern Iran. Fifteen mineralization-related intrusive rocks range (Middle Eocene 39 Ma) in composition from diorite to monzonite have been distinguished. Monzonitic porphyries had major role in Cu-Au mineralization. The ore bearing porphyries are I-type, meta luminous, high-Kcalc-alkaline to shoshonite intrusive rocks which were formed in island arc setting. These rocks are characterized by average of SiO 2 > 59 wt %, Al 2 O 3 > 15 wt %, MgO 2 O> 3 wt %, Sr> 870 ppm, Y 55, moderate Light rare earth elements, relatively low heavy rare earth elements and enrichment LILE (Sr, Cs, Rb, K and Ba) relative to HFSE (Nb, Ta, Ti, Hf and Zr). They are chemically similar to some adakites, but their chemical signatures differ in some ways from normal adakites, including higher K 2 O contents and K 2 O/Na 2 O ratios and lower Mg, (La/Yb) N , (Ce/Yb) N and εNd in Maherabad rocks. Maherabad intrusive rocks are the first K-rich adakites that can be related with subduction zone. Partial melting of mantle hybridized by hydrous, silica-rich slab-derived melts or/and input of enriched mantle-derived ultra-potassic magmas during or prior to the formation and migration of adakitic melts could be explain their high K 2 O contents and K 2 O/Na 2r atios. Low Mg values and relatively low MgO, Cr and Ni contents imply limited interaction between adakite-like magma and mantle wedge peridotite. The initial 87 Sr/ 86 Sr and ( 143 Nd/ 144 Nd)i was recalculated to an age of 39 Ma (unpublished data). Initial 87 Sr/ 86 Sr ratios for hornblende monzonite porphyry are 0.7047-0.7048. The ( 143 Nd/ 144 Nd)i isotope composition are 0.512694-0.512713. Initial εNd isotope values 1.45-1.81. These values could be considered as representative of oceanic slab-derived magmas. Source modeling indicates that high-degree of

  15. Final report on the IAEA research contracts No. 1194/RB, 1194/R1/RB and 1194/R2/RB

    International Nuclear Information System (INIS)

    Zobor, E.; Janosy, J.S.; Szentgali, A.

    1980-09-01

    The final report summarizes the research activities made in the framework of the IAEA Research Contracts No. 1194/RB, 1194/R1/RB and 1194/R2/RB. A multilevel hierarchical control system is treated which uses weakly-coupled low dimensional subsystems under the supervision of a dynamic coordinator program. This self-organizing adaptive control system was checked by a 5 MW research reactor. As an example the paper describes the experimental computer control system of the 5 MW WWR-SM research reactor, where the reactor power and outlet temperature have been controlled on the basis of the treated control concept since 1978. (author)

  16. Ion microprobe Sr isotope analysis of carbonates with about 5 μm spatial resolution: An example from an ayu otolith

    International Nuclear Information System (INIS)

    Sano, Yuji; Shirai, Kotaro; Takahata, Naoto; Amakawa, Hiroshi; Otake, Tsuguo

    2008-01-01

    A high lateral resolution secondary ion mass spectrometer (NanoSIMS NS50 ion microprobe) has been used to measure 87 Sr/ 86 Sr ratios in natural CaCO 3 samples. A ∼2 nA O - primary beam was used to sputter a 5-7-μm diameter crater on the sample surface and secondary positive ions were extracted for mass analysis using an accelerating voltage of 8 kV and a Mattauch-Herzog geometry. The multi-collector system was adjusted to detect 43 Ca + (by a detector EM2), 80 Ca 2 + (EM3), 86 Sr + (EM4), and 87 Sr + (EM4b) ions at the same time. Then the magnetic field was scanned for the EM4 to detect 85 Rb + , 86 Sr + and 87 Sr + , while the EM4b can measure 86 Sr + , 87 Sr + and 88 Sr + , respectively. A mass resolution of 3600 at 10% peak height was attained with a flat peak top, while the sensitivity of Sr was about 10 cps/nA/ppm. An aragonite sample (coral skeleton standard; JCp-1) was used as a reference for Sr isotope ratio calibration. Repeated analyses of the JCp-1 show that the 87 Sr/ 86 Sr ratio agrees well with the seawater signature within a precision of 0.3 per mille at 2σ, after the series of corrections such as the Ca dimer, 87 Rb, and a mass bias estimated by the 88 Sr/ 86 Sr ratio. The method was applied to an otolith (ear-stone) from ayu (Plecoglossus altivelis altivelis) collected from the Yodo river, Japan. Although experimental errors are relatively large, up to 3 per mille at 2σ, the ratios of the core region are higher than the seawater signature while more distal values agree well with seawater. The very outermost part again shows the relatively higher 87 Sr/ 86 Sr ratios. The spatial variation of 87 Sr/ 86 Sr ratios was consistent with amphidromous migration of the fish, namely, born in the lake and grown in the coastal sea and finally collected in a river

  17. Characterization of recombinant B. abortus strain RB51SOD towards understanding the uncorrelated innate and adaptive immune responses induced by RB51SOD compared to its parent vaccine strain RB51

    Directory of Open Access Journals (Sweden)

    Jianguo eZhu

    2011-11-01

    Full Text Available Brucella abortus is a Gram-negative, facultative intracellular pathogen for several mammals, including humans. Live attenuated B. abortus strain RB51 is currently the official vaccine used against bovine brucellosis in the United States and several other countries. Overexpression of protective B. abortus antigen Cu/Zn superoxide dismutase (SOD in a recombinant strain of RB51 (strain RB51SOD significantly increases its vaccine efficacy against virulent B. abortus challenge in a mouse model. An attempt has been made to better understand the mechanism of the enhanced protective immunity of RB51SOD compared to its parent strain RB51. We previously reported that RB51SOD stimulated enhanced Th1 immune response. In this study, we further found that T effector cells derived from RB51SOD-immunized mice exhibited significantly higher cytotoxic T lymphocyte (CTL activity than T effector cells derived from RB51-immunized mice against virulent B. abortus-infected target cells. Meanwhile, the macrophage responses to these two strains were also studied. Compared to RB51, RB51SOD cells had a lower survival rate in macrophages and induced lower levels of macrophage apoptosis and necrosis. The decreased survival of RB51SOD cells correlates with the higher sensitivity of RB51SOD, compared to RB51, to the bactericidal action of either Polymyxin B or sodium dodecyl sulfate (SDS. Furthermore, a physical damage to the outer membrane of RB51SOD was observed by electron microscopy. Possibly due to the physical damage, overexpressed Cu/Zn SOD in RB51SOD was found to be released into the bacterial cell culture medium. Therefore, the stronger adaptive immunity induced by RB51SOD did not correlate with the low level of innate immunity induced by RB51SOD compared to RB51. This unique and apparently contradictory profile is likely associated with the differences in outer membrane integrity and Cu/Zn SOD release.

  18. Proterozoic orogenic belts and rifting of Indian cratons: Geophysical constraints

    Directory of Open Access Journals (Sweden)

    D.C. Mishra

    2014-01-01

    Full Text Available The Aravalli–Delhi and Satpura Mobile Belts (ADMB and SMB and the Eastern Ghat Mobile Belt (EGMB in India form major Proterozoic mobile belts with adjoining cratons and contemporary basins. The most convincing features of the ADMB and the SMB have been the crustal layers dipping from both sides in opposite directions, crustal thickening (∼45 km and high density and high conductivity rocks in upper/lower crust associated with faults/thrusts. These observations indicate convergence while domal type reflectors in the lower crust suggest an extensional rifting phase. In case of the SMB, even the remnant of the subducting slab characterized by high conductive and low density slab in lithospheric mantle up to ∼120 km across the Purna–Godavari river faults has been traced which may be caused by fluids due to metamorphism. Subduction related intrusives of the SMB south of it and the ADMB west of it suggest N–S and E–W directed convergence and subduction during Meso–Neoproterozoic convergence. The simultaneous E–W convergence between the Bundelkhand craton and Marwar craton (Western Rajasthan across the ADMB and the N–S convergence between the Bundelkhand craton and the Bhandara and Dharwar cratons across the SMB suggest that the forces of convergence might have been in a NE–SW direction with E–W and N–S components in the two cases, respectively. This explains the arcuate shaped collision zone of the ADMB and the SMB which are connected in their western part. The Eastern Ghat Mobile Belt (EGMB also shows signatures of E–W directed Meso–Neoproterozoic convergence with East Antarctica similar to ADMB in north India. Foreland basins such as Vindhyan (ADMB–SMB, and Kurnool (EGMB Supergroups of rocks were formed during this convergence. Older rocks such as Aravalli (ADMB, Mahakoshal–Bijawar (SMB, and Cuddapah (EGMB Supergroups of rocks with several basic/ultrabasic intrusives along these mobile belts, plausibly formed during

  19. Sr and Pb isotopic composition of five USGS glasses (BHVO-2G, BIR-1G, BCR-2G, TB-1G, NKT-1G)

    NARCIS (Netherlands)

    Elburg, M.A.; Vroon, P.Z.; van der Wagt, R.A.C.A.; Tchalikian, A.

    2005-01-01

    Sr isotopic compositions and Rb/Sr ratios of three USGS glasses (BHVO-2G, BIR-1G, BCR-2G) are identical to those of the original USGS reference materials. NKT-1G and TB-1G give values of 0.70351 and 0.70558, respectively. Pb isotopic ratios were measured by the standard-sample bracketing technique

  20. First-principles calculations of two cubic fluoropervskite compounds: RbFeF3 and RbNiF3

    International Nuclear Information System (INIS)

    Mubarak, A.A.; Al-Omari, Saleh

    2015-01-01

    We present first-principles calculations of the structural, elastic, electronic, magnetic and optical properties for RbFeF 3 and RbNiF 3 . The full-potential linear augmented plan wave (FP-LAPW) method within the density functional theory was utilized to perform the present calculations. We employed the generalized gradient approximation as exchange-correlation potential. It was found that the calculated analytical lattice parameters agree with previous studies. The analysis of elastic constants showed that the present compounds are elastically stable and anisotropic. Moreover, both compounds are classified as a ductile compound. The calculations of the band structure and density functional theory revealed that the RbFeF 3 compound has a half-metallic behavior while the RbNiF 3 compound has a semiconductor behavior with indirect (M–Γ) band gap. The ferromagnetic behavior was studied for both compounds. The optical properties were calculated for the radiation of up to 40 eV. A beneficial optics technology is predicted as revealed from the optical spectra. - Highlights: • RbFeF 3 and RbNiCl 3 compounds are elastically stable. • RbFeF 3 and RbNiCl 3 compounds are classified as a ductile compound. • The RbFeF 3 compound has a half-metallic behavior while the RbNiF 3 compound has a semiconductor behavior. • The optical properties were calculated for the radiation of up to 40 eV

  1. Synthesis and Characterization of the Rubidium Thiophosphate Rb 6 (PS 5 )(P 2 S 10 ) and the Rubidium Silver Thiophosphates Rb 2 AgPS 4 , RbAg 5 (PS 4 ) 2 and Rb 3 Ag 9 (PS 4 ) 4

    KAUST Repository

    Alahmary, Fatimah S.; Davaasuren, Bambar; Khanderi, Jayaprakash; Rothenberger, Alexander

    2016-01-01

    The metal thiophosphates Rb2AgPS4 (2), RbAg5(PS4)2 (3), and Rb3Ag9(PS4)4 (4) were synthesized by stoichiometric reactions, whereas Rb6(PS5)(P2S10) (1) was prepared with excess amount of sulfur. The compounds crystallize as follows: 1 monoclinic, P21

  2. Archean and proterozoic in the West-European Hercynian chain: isotopic geochemistry (Sr-Nd-Pb) and U-Pb geochronology on zircons

    International Nuclear Information System (INIS)

    Guerrot, C.

    1989-01-01

    The first part of this research thesis reports the study of isotopic (Sr-Nd-Pb) geochemistry and U-Pb geochronology on zircons in the immersed granulites of the Bay of Biscay: U-Pb geochronology on zircons, Nd isotopic geochemistry, Sr isotopic geochemistry, common Pb, Rb-Sr, Sm-Nd and rare earth data on minerals, comparison with other European granulites, comparison with West-Africa, study of Archean and proterozoic in the Hercynian chain. The second part reports the study of the U-Pb geochronology on zircon in the Cadomian, and the third part addresses the Sr-Nd isotopic geochemistry of some Cadomian granitoid, and the crust contamination in different regions [fr

  3. U-Pb, Sm-Nd and Rb-Sr systematics of mid-ocean ridge basalt glasses

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, R S; Evensen, N M; Hamilton, P J; O' Nions, R K [Columbia Univ., Palisades, NY (USA). Lamont-Doherty Geological Observatory

    1980-01-10

    The measurement of Pb, Nd and Sr isotopes in basalt glasses from mid-ocean ridges reveals correlations in isotope parameters which have important implications for the differentiation history of the mantle.

  4. Petrogenesis of the middle Jurassic appinite and coeval granitoids in the Eastern Hebei area of North China Craton

    Science.gov (United States)

    Fan, Wenbo; Jiang, Neng; Xu, Xiyang; Hu, Jun; Zong, Keqing

    2017-05-01

    An integrated study of zircon U-Pb ages and Hf-O isotopic compositions, whole rock elemental and Sr-Nd isotope geochemistry was conducted on three lithologically diverse middle Jurassic plutons from the Eastern Hebei area of the North China Craton (NCC), in order to reveal both their petrogenesis and possible tectonic affinity. The three plutons have consistent magmatic zircon U-Pb ages from 167 ± 1 Ma to 173 ± 1 Ma. The Nianziyu pluton has typical characteristics of appinite with low SiO2 (43.7-52.6%), high Ca, Mg, Fe and H2O contents. It possesses subduction-related trace element patterns, enriched Nd-Hf isotopic signatures as well as elevated zircon δ18O values (6.2-7.2‰), arguing for an enriched mantle source metasomatized by fluids related to subduction. The Shuihutong monzogranites have high silica (SiO2 = 75.4-75.9%) and alkali contents, low Ca contents and striking negative Ba, Sr and Eu anomalies. Samples from the pluton have more evolved Nd-Hf isotopic values and are considered to be most likely derived from anatexis of ancient lower continental crust. Hybridization between mantle- and ancient lower crust-derived magmas is proposed for the mafic microgranular enclave-bearing Baijiadian granitoids, which are characterized by variable εNd (t) and εHf(t) values. Integrated with the regional geologic history, we suggest that the formation of the three middle Jurassic plutons were related to the subduction of the Paleo-Pacific ocean plate beneath the NCC. Their petrogenetic differences reflect complex magmatic processes in subduction settings involving melting of multiple sources, possible partly facilitated by fluid metasomatism and water-rich magma injection, accompanied with various degrees of magma mixing. The appearance of middle Jurassic appinitic rocks leads us to propose that the NCC destruction and lithosphere thinning were facilitated and controlled by the weakening of the lithospheric mantle after hydration because of the subduction of the

  5. The geotectonic evolution of the Northeastern Minas Gerais, based in geochronological interpretation

    International Nuclear Information System (INIS)

    Siga Junior, O.

    1986-01-01

    This work tries to show the potential of the Rb-Sr, K-Ar, Pb-Pb and U-Pb methods applied to basic geological maping. The different interpretative values of these methodologies contribute to the understanding of the tectonic processes developed in the southeastern border of the Sao Francisco Craton (northeastern Minas Gerais and southern Bahia). The geochronological data for this region represents sampling of the several lithological units characterized and corresponds to about 230 determinations. The radiometric age distribution pattern together with other geological information suggest the subdivision into two main geochronological domains: the external Brazilian domain (at the western portion) and the internal Brazilian domain (at the center-eastern part). (author) [pt

  6. Craton Heterogeneity in the South American Lithosphere

    Science.gov (United States)

    Lloyd, S.; Van der Lee, S.; Assumpcao, M.; Feng, M.; Franca, G. S.

    2012-04-01

    We investigate structure of the lithosphere beneath South America using receiver functions, surface wave dispersion analysis, and seismic tomography. The data used include recordings from 20 temporary broadband seismic stations deployed across eastern Brazil (BLSP02) and from the Chile Ridge Subduction Project seismic array in southern Chile (CRSP). By jointly inverting Moho point constraints, Rayleigh wave group velocities, and regional S and Rayleigh wave forms we obtain a continuous map of Moho depth. The new tomographic Moho map suggests that Moho depth and Moho relief vary slightly with age within the Precambrian crust. Whether or not a correlation between crustal thickness and geologic age can be derived from the pre-interpolation point constraints depends strongly on the selected subset of receiver functions. This implies that using only pre-interpolation point constraints (receiver functions) inadequately samples the spatial variation in geologic age. We also invert for S velocity structure and estimate the depth of the lithosphere-asthenosphere boundary (LAB) in Precambrian South America. The new model reveals a relatively thin lithosphere throughout most of Precambrian South America (< 140 km). Comparing LAB depth with lithospheric age shows they are overall positively correlated, whereby the thickest lithosphere occurs in the relatively small Saõ Francisco craton (200 km). However, within the larger Amazonian craton the younger lithosphere is thicker, indicating that locally even larger cratons are not protected from erosion or reworking of the lithosphere.

  7. Evaluating crustal contributions to enriched shergottites from the petrology, trace elements, and Rb-Sr and Sm-Nd isotope systematics of Northwest Africa 856

    Science.gov (United States)

    Ferdous, J.; Brandon, A. D.; Peslier, A. H.; Pirotte, Z.

    2017-08-01

    The origin of the incompatible trace element (ITE) characteristics of enriched shergottites has been critical for examining two contradicting scenarios to explain how these Martian meteorites form. The first scenario is that it reflects ITE enrichment in an early-formed mantle reservoir whereas the second scenario attributes it to assimilation of ancient Martian crust (∼4-4.5 Ga) by ITE-depleted magmas. Strongly differentiated shergottite magmas may yield added constraints for determining which scenario can best explain this signature in enriched shergottites. The meteorite Northwest Africa (NWA) 856 is a basaltic shergottite that, unlike many enriched shergottites, lacks olivine and has undergone extensive differentiation from more primitive parent magma. In similarity to other basaltic shergottites, NWA 856 is comprised primarily of compositionally zoned clinopyroxenes (45% pigeonite and 23% augite), maskelynite (23%) and accessory minerals such as ulvöspinel, merrillite, Cl-apatite, ilmenite, pyrrhotite, baddeleyite and silica polymorph. The CI-chondrite normalized rare earth element (REE) abundance patterns for its maskelynite, phosphates, and its whole rock are flat with corresponding light-REE depletions in clinopyroxenes. The 87Rb-87Sr and 147Sm-143Nd internal isochron ages are 162 ± 14 (all errors are ±2σ) Ma and 162.7 ± 5.5 Ma, respectively, with an initial εNdI = -6.6 ± 0.2. The Rb-Sr isotope systematics are affected by terrestrial alteration resulting in larger scatter and a less precise internal isochron age. The whole rock composition is used in MELTS simulations to model equilibrium and fractional crystallization sequences to compare with the crystallization sequence from textural observations and to the mineral compositions. These models constrain the depth of initial crystallization to a pressure range of 0.4-0.5 GPa (equivalent to 34-42 km) in anhydrous conditions at the Fayalite-Magnetite-Quartz buffer, and consistently reproduce the

  8. Contrasted continental rifting via plume-craton interaction: Applications to Central East African Rift

    Directory of Open Access Journals (Sweden)

    Alexander Koptev

    2016-03-01

    Full Text Available The East African Rift system (EARS provides a unique system with the juxtaposition of two contrasting yet simultaneously formed rift branches, the eastern, magma-rich, and the western, magma-poor, on either sides of the old thick Tanzanian craton embedded in a younger lithosphere. Data on the pre-rift, syn-rift and post-rift far-field volcanic and tectonic activity show that the EARS formed in the context of the interaction between a deep mantle plume and a horizontally and vertically heterogeneous lithosphere under far-field tectonic extension. We bring quantitative insights into this evolution by implementing high-resolution 3D thermo-mechanical numerical deformation models of a lithosphere of realistic rheology. The models focus on the central part of the EARS. We explore scenarios of plume-lithosphere interaction with plumes of various size and initial position rising beneath a tectonically pre-stretched lithosphere. We test the impact of the inherited rheological discontinuities (suture zones along the craton borders, of the rheological structure, of lithosphere plate thickness variations, and of physical and mechanical contrasts between the craton and the embedding lithosphere. Our experiments indicate that the ascending plume material is deflected by the cratonic keel and preferentially channeled along one of its sides, leading to the formation of a large rift zone along the eastern side of the craton, with significant magmatic activity and substantial melt amount derived from the mantle plume material. We show that the observed asymmetry of the central EARS, with coeval amagmatic (western and magmatic (eastern branches, can be explained by the splitting of warm material rising from a broad plume head whose initial position is slightly shifted to the eastern side of the craton. In that case, neither a mechanical weakness of the contact between the craton and the embedding lithosphere nor the presence of second plume are required to

  9. Mirror decay of $^{75}$Sr

    CERN Document Server

    Huikari, J; Algora, A; Cederkäll, J; Courtin, S; Dessagne, P; Fraile-Prieto, L M; Franchoo, S; Fynbo, H O U; Huang Wan Xia; Jokinen, A; Knipper, A; Maréchal, F; Miehé, C; Nácher, E; Peräjärvi, K; Poirier, E; Weissman, L; Äystö, J

    2003-01-01

    The beta -decay of /sup 75/Sr to its mirror nucleus /sup 75/Rb was studied at the ISOLDE PSB facility at CERN by means of beta -delayed gamma and proton spectroscopy. The decay Q-value and beta -delayed gamma intensity were measured for the first time. These results, 10.60+or-0.22 MeV and 4.5/sub -0.7//sup +1.9/%, together with accurate measurements of the beta -decay half-life and beta -delayed proton branching ratio yielded the Gamow-Teller strength 0.35+or-0.05 for the mirror transition. Implications of the results on studies of deformation effects and on the path of the rapid proton capture process are discussed. (24 refs).

  10. Ion microprobe Sr isotope analysis of carbonates with about 5 {mu}m spatial resolution: An example from an ayu otolith

    Energy Technology Data Exchange (ETDEWEB)

    Sano, Yuji [Center for Advanced Marine Research, Ocean Research Institute, University of Tokyo, Nakano-ku, Tokyo 164-8639 (Japan)], E-mail: ysano@ori.u-tokyo.ac.jp; Shirai, Kotaro [International Coastal Research Center, Ocean Research Institute, University of Tokyo, Otsuchi, Iwate 028-1102 (Japan); Takahata, Naoto; Amakawa, Hiroshi [Center for Advanced Marine Research, Ocean Research Institute, University of Tokyo, Nakano-ku, Tokyo 164-8639 (Japan); Otake, Tsuguo [International Coastal Research Center, Ocean Research Institute, University of Tokyo, Otsuchi, Iwate 028-1102 (Japan)

    2008-08-15

    A high lateral resolution secondary ion mass spectrometer (NanoSIMS NS50 ion microprobe) has been used to measure {sup 87}Sr/{sup 86}Sr ratios in natural CaCO{sub 3} samples. A {approx}2 nA O{sup -} primary beam was used to sputter a 5-7-{mu}m diameter crater on the sample surface and secondary positive ions were extracted for mass analysis using an accelerating voltage of 8 kV and a Mattauch-Herzog geometry. The multi-collector system was adjusted to detect {sup 43}Ca{sup +} (by a detector EM2), {sup 80}Ca{sub 2}{sup +} (EM3), {sup 86}Sr{sup +} (EM4), and {sup 87}Sr{sup +} (EM4b) ions at the same time. Then the magnetic field was scanned for the EM4 to detect {sup 85}Rb{sup +}, {sup 86}Sr{sup +} and {sup 87}Sr{sup +}, while the EM4b can measure {sup 86}Sr{sup +}, {sup 87}Sr{sup +} and {sup 88}Sr{sup +}, respectively. A mass resolution of 3600 at 10% peak height was attained with a flat peak top, while the sensitivity of Sr was about 10 cps/nA/ppm. An aragonite sample (coral skeleton standard; JCp-1) was used as a reference for Sr isotope ratio calibration. Repeated analyses of the JCp-1 show that the {sup 87}Sr/{sup 86}Sr ratio agrees well with the seawater signature within a precision of 0.3 per mille at 2{sigma}, after the series of corrections such as the Ca dimer, {sup 87}Rb, and a mass bias estimated by the {sup 88}Sr/{sup 86}Sr ratio. The method was applied to an otolith (ear-stone) from ayu (Plecoglossus altivelis altivelis) collected from the Yodo river, Japan. Although experimental errors are relatively large, up to 3 per mille at 2{sigma}, the ratios of the core region are higher than the seawater signature while more distal values agree well with seawater. The very outermost part again shows the relatively higher {sup 87}Sr/{sup 86}Sr ratios. The spatial variation of {sup 87}Sr/{sup 86}Sr ratios was consistent with amphidromous migration of the fish, namely, born in the lake and grown in the coastal sea and finally collected in a river.

  11. Studies on the decoupled rotation bands in the nuclei 79Rb, 81Rb, and 79Kr

    International Nuclear Information System (INIS)

    Panqueva Alvarez, J.H.

    1982-01-01

    High spin states in 79 Rb, 81 Rb, and 79 Kr were studied by means of the following reactions: 63 Cu( 19 F,p2n) 79 Rb, 70 Ge( 12 C,p2n) 79 Rb, 65 Cu( 16 O,2n) 79 Rb, 65 Cu( 19 F,p2n) 81 Rb, 63 Cu( 19 F,2pn) 79 Kr, and 70 Ge( 12 C,2pn) 79 Kr. On the base of γ single spectra, excitation functions, γ angular distributions, γγ and nγ coincidences, RDDS- and DSA lifetime measurements a level scheme of 79 Rb with 13 new found excited states is proposed. Also a series of stretched E2-transitions between posivite parity states in 79 Kr could be identified. The observed M1 and E2 transition probabilities, which were obtained via the experimental determination of the lifetime as well the branching ratio of 26 excited states, form the base for a comprehensive discussion of the nuclear structure of the studied isotopes. For this reason theoretical calculations with the asymmetric rotor-plus-quasiparticle with variable moment of inertia (AROVMI) as well with the interacting boson-fermion (IBVM) model were performed. The good agreement between experiment and theory permits to relate the decrease of the B(E2)-values in 79 Rb to a finite dimensional (N=8) boson space, to cancel the discrepancies stated by Friederichs et.al., and to analyze 79 Kr the influence of a gsub(9/2) neutron on the deformation of the 78 Kr core. (orig./HSI) [de

  12. Petrology, geochemistry of major elements, traces, rare earths and isotopes (Sr, O, H, S) on Meruoca and Mocambo batholith, Ceara State, Northeast of Brazil

    International Nuclear Information System (INIS)

    Sial, A.N.

    1989-01-01

    Values of δ sup(18) O of whole-rock Meruoca granite and mineral separates form a remarkable bull's-eye pattern. Toward the periphery, the granite appears to be normal I type (δ sup(18) O = +7 to +8 permil sub(SMOW)). Whole-rock isochron gives an age of 491 + 19 Ma and an initial sup(87) Sr/ sup(86) Sr of 0.07076 + 0.0028 but with data points scattering outside experimental error attesting to a significant disturbance of the Rb-Sr relationships.(author)

  13. Sr-Nd-Hf isotopic fingerprinting of transatlantic dust derived from North Africa

    Science.gov (United States)

    Zhao, Wancang; Balsam, William; Williams, Earle; Long, Xiaoyong; Ji, Junfeng

    2018-03-01

    Long-range transport of African dust plays an important role in understanding dust-climate relationships including dust source areas, dust pathways and associated atmospheric and/or oceanic processes. Clay-sized Sr-Nd-Hf isotopic compositions can be used as geochemical fingerprints to constrain dust provenance and the pathways of long-range transported mineral dust. We investigated the clay-sized Sr-Nd-Hf isotopic composition of surface samples along four transects bordering the Sahara Desert. The transects are from Mali, Niger/Benin/Togo, Egypt and Morocco. Our results show that the Mali transect on the West African Craton (WAC) produces lower εNd (εNd-mean = -16.38) and εHf (εHf-mean = -9.59) values than the other three transects. The Egyptian transect exhibits the lowest 87Sr/86Sr ratios (87Sr/86Srmean = 0.709842), the highest εHf (εHf-mean = -0.34) and εNd values of the four transects. Comparison of the clay-sized Sr-Nd-Hf isotopic values from our North African samples to transatlantic African dust collected in Barbados demonstrates that the dust's provenance is primarily the western Sahel and Sahara as well as the central Sahel. Summer emission dust is derived mainly from the western Sahel and Sahara regions. The source of transatlantic dust in spring and autumn is more varied than in the summer and includes dust not only from western areas, but also south central areas. Comparison of the Sr-Nd-Hf isotopic fingerprints between the source and sink of transatlantic dust also suggests that a northwestward shift in dust source occurs from the winter, through the spring and into the summer. The isotopic data we develop here provide another tool for discriminating changes in dust archives resulting from paleoenvironmental evolution of source regions.

  14. Rifting an Archaean Craton: Insights from Seismic Anisotropy Patterns in E. Africa

    Science.gov (United States)

    Ebinger, C. J.; Tiberi, C.; Currie, C. A.; van Wijk, J.; Albaric, J.

    2016-12-01

    Few places worldwide offer opportunities to study active deformation of deeply-keeled cratonic lithosphere. The magma-rich Eastern rift transects the eastern edge of the Archaean Tanzania craton in northeastern Tanzania, which has been affected by a large-scale mantle upwelling. Abundant xenolith locales offer constraints on mantle age, composition, and physical properties. Our aim is to evaluate models for magmatic fluid-alteration (metasomatism) and deformation of mantle lithosphere along the edge of cratons by considering spatial variations in the direction and magnitude of seismic anisotropy, which is strongly influenced by mantle flow patterns along lithosphere-asthenosphere topography, fluid-filled cracks (e.g., dikes), and pre-existing mantle lithosphere strain fabrics. Waveforms of teleseismic earthquakes (SKS, SKKS) recorded on the 39-station CRAFTI-CoLiBREA broadband array in southern Kenya and northern Tanzania are used to determine the azimuth and amount of shear-wave splitting accrued as seismic waves pass through the uppermost mantle and lithosphere at the craton edge. Lower crustal earthquakes enable evaluation of seismic anisotropy throughout the crust along the rift flanks and beneath the heavily intruded Magadi and Natron basins, and the weakly intruded Manyara basin. Our results and those of earlier studies show a consistent N50E splitting direction within the craton, with delay times of ca. 1.5 s, and similar direction east of the rift in thinner Pan-African lithosphere. Stations within the rift zone are rotated to a N15-35E splitting, with the largest delay times of 2.5 s at the margin of the heavily intruded Magadi basin. The short length scale of variations and rift-parallel splitting directions are similar to patterns in the Main Ethiopian rift attributed to melt-filled cracks or oriented pockets rising from the base of the lithosphere. The widespread evidence for mantle metasomatism and magma intrusion to mid-crustal levels suggests that

  15. U-Pb age of the Anuri dyke: paleoproterozoic potassic alkaline magmatism and implications for the Transamazonic orogeny in the Sao Francisco Craton

    International Nuclear Information System (INIS)

    Conceicao, Herbet; Rios, Debora Correia; Oberli, Felix

    2007-01-01

    The Anuri Syenitic Dyke (72 km 2 ) is the south representative of a 1000 km N-S alignment of syenitic dykes which occur at the East Bahia. As the others bodies, Anuri is essentially composed of hypersolvus ultrapotassic syenites, which show the records of its differentiation by the presence of mafic-ultramafic apatite-rich cumulates. Its crystallization age of 2095- 4 Ma (U-Pb zircao ) is quite similar with results obtained for the other syenitic dykes, which suggest that their intrusions occur almost at the same time, sincronically, after the Transamazonic Orogeny climax. The geochemical data reveal that Anuri syenites are Ba, Sr, P, LREE enriched and show negative anomalies of Ti and Nb, suggesting a mantelic source subduction related. The initial Sr ratio and ε Nd values confirms the presence of this anomalous mantle. These data suggest that at the end of Transamazonic Orogeny, at the Sao Francisco Craton, there were particular conditions which allow the generation of alkaline magmas through the melting of an EMI reservoir. (author)

  16. Calibration of RB reactor power; Kalibrisanje snage reaktora RB

    Energy Technology Data Exchange (ETDEWEB)

    Sotic, O; Markovic, H; Ninkovic, M; Strugar, P; Dimitrijevic, Z; Takac, S; Stefanovic, D; Kocic, A; Vranic, S [Boris Kidric Institute of Nuclear Sciences Vinca, Beograd (Yugoslavia)

    1976-09-15

    The first and only calibration of RB reactor power was done in 1962, and the obtained calibration ratio was used irrespective of the lattice pitch and core configuration. Since the RB reactor is being prepared for operation at higher power levels it was indispensable to reexamine the calibration ratio, estimate its dependence on the lattice pitch, critical level of heavy water and thickness of the side reflector. It was necessary to verify the reliability of control and dosimetry instruments, and establish neutron and gamma dose dependence on reactor power. Two series of experiments were done in June 1976. First series was devoted to tests of control and dosimetry instrumentation and measurements of radiation in the RB reactor building dependent on reactor power. Second series covered measurement of thermal and epithermal neuron fluxes in the reactor core and calculation of reactor power. Four different reactor cores were chosen for these experiments. Reactor pitches were 8, 8{radical}2, and 16 cm with 40, 52 and 82 fuel channels containing 2% enriched fuel. Obtained results and analysis of these results are presented in this document with conclusions related to reactor safe operation.

  17. Mesozoic mafic dikes from the Shandong Peninsula, North China Craton: Petrogenesis and tectonic implications

    International Nuclear Information System (INIS)

    Liu Shen; Hu Ruizhong; Zhao Junhong; Feng Caixia; Zou, Haibo

    2006-01-01

    Mesozoic mafic dikes are widely distributed in Luxi (Mengyin and Zichuan) and Jiaodong regions of the Shandong Peninsula, China, providing an opportunity of investigating the nature of the lost lithospheric mantle beneath the North China Craton (NCC). The mafic dikes are characterized by strong depletion in high field strength elements (HFSE), enrichment in light rare earth elements (LREE), highly variable Th/U ratios, high initial ( 87 Sr/ 86 Sr) i (0.7050-0.7099) and negative ε Nd (T) (-6.0 to -17.6). They were derived from melting of metasomatized portions of the subcontinental lithospheric mantle, followed by fractionation of clinopyroxenes. The similarity in Nd isotopic compositions between the Mengyin gabbro dikes and the Paleozoic peridotite xenoliths suggests that ancient lithospheric mantle was still retained at 120 Ma below Mengyin, although the ancient lithospheric mantle in many other places beneath NCC had been severely modified. There might be multiple enrichment events in the lithospheric mantle. An early-stage (before or during Paleozoic) rutile-rich metasomatism affected the lithospheric mantle below Mengyin, Jiaodong and Zichuan. Since then, the lithospheric mantle beneath Mengyin was isolated. A late-stage metasomatism by silicate melts modified the lithospheric mantle beneath Jiaodong and Zichuan but not Mengyin. The removal of the enriched lithospheric mantle and the generation of the mafic dikes may be mainly related to the convective overturn accompanying Jurassic-Cretaceous subduction of the paleo-Pacific plate. (author)

  18. Petrogenesis of Jurassic granitoids at the northeastern margin of the North China Craton: New geochemical and geochronological constraints on subduction of the Paleo-Pacific Plate

    Science.gov (United States)

    Liu, Jin; Zhang, Jian; Liu, Zhenghong; Yin, Changqing; Zhao, Chen; Peng, Youbo

    2018-06-01

    At the junction between the North China Craton (NCC) and the Central Asian Orogenic Belt (CAOB), northern Liaoning province, NE China, there are widespread Jurassic igneous rocks. The tectonic setting and petrogenesis of these rocks are unresolved. Zircon U-Pb dating, whole-rock geochemistry, and Hf isotopic compositions of Jurassic granitoids were investigated to constrain their ages and petrogenesis in order to understand the tectonic evolution of the Paleo-Pacific Ocean along the northeastern margin of the NCC. Geochronological data indicate that magmatism occurred between the early and late Jurassic (180-156 Ma). Despite the wide range in ages of the intrusions, Jurassic granitoids were likely derived from a similar or common source, as inferred from their geochemical and Hf isotopic characteristics. Compared to the island arc andesite-dacite-rhyolite series, the Jurassic granitoids are characterized by higher SiO2, Al2O3, and Sr contents, and lower MgO, FeOT, Y, and Yb contents, indicating that the primary magmas show typical characteristics of adakitic magmas derived from partial melting of thickened lower crust. These findings, combined with their εHf(t) values (+1.4 to +5.4) and two-stage model ages (1515-1165 Ma), indicate the primary magmas originated from partial melting of juvenile crustal material accreted during the Mesoproterozoic. They are enriched in large-ion lithophile elements (e.g., Rb, K, Th, Ba, and U) and light rare-earth elements (REE), and depleted in high-field-strength elements (e.g., Nb, Ta, Ti, and P) and heavy REE. Based on these findings and previous studies, we suggest that the Jurassic adakitic granitoids (180-156 Ma) were formed in an active continental margin and compressive tectonic setting, related to subduction of the Paleo-Pacific Plate.

  19. Analysis list: RB1 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available RB1 Prostate,Uterus + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/R...B1.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/RB1.5.tsv http://dbarchive.biosciencedbc.jp/...kyushu-u/hg19/target/RB1.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/RB1.Prostate.tsv,http://dbarchive.bioscience...dbc.jp/kyushu-u/hg19/colo/RB1.Uterus.tsv http://dbarchive.bioscience...dbc.jp/kyushu-u/hg19/colo/Prostate.gml,http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/Uterus.gml ...

  20. Juvenile helium in ancient rocks: II. U-He,K-Ar, Sm-Nd, and Rb-Sr systematics in the Monche Pluton. 3He/4He ratios frozen in uranium-free ultramafic rocks

    International Nuclear Information System (INIS)

    Tolstikhin, I.N.; Dokuchaeva, V.S.; Kamensky, I.L.; Amelin, Yu.V.

    1992-01-01

    The important geodynamic parameter, the 3 He/ 4 He ratio in rocks and fluids of the continental crust, is generally decreasing from the mantle values (≅ 10 -5 ) to the radiogenic ratio (≅ 10 -8 ) on the time scale of about 1 Ga or less. However, the ratios, observed in some ancient rocks and minerals, are much higher than the radiogenic value due to a preferential retention of trapped He, when compared with radiogenic helium and/or a low U/ 3 He ratio in a sample. The distribution of He, Ar, Nd, and Sr isotopes, K, Rb, Sm, and U in ultrabasic rocks, in rock-forming minerals, in ores from the 2.49 Ga Monche Pluton, and in basic rocks of the Main Range (the Kola Peninsula) enables one to distinguish sources of the rocks and trapped fluids and outline some peculiarities of petrogenetic and fluid processes. The initial values of var-epsilon Nd (T) = -0.9 ± 0.5 , 87 Sr/ 86 Sr(T) = 0.7021 ± 0.0002, for the 2.49 Ga Monche Pluton are rather similar to these for other layered intrusions of the Baltic Shield. They differ considerably from the model values for the depleted 2.5 Ga old mantle. The observed and rather different sources of 3 He and 4 He as well as the considerable constancy of their ratio in different minerals, separated from both the ultramafic rocks and gabbros, implies: (1) an intensive process of mixing between mantle and crustal components: a melt convection in the chamber may have occurred; (2) the two types of rocks could originate by crystallization differentiation of one and the same melt. Practically all 3 He and 4 He are concentrated in secondary amphiboles; hence the fluid which stimulated the metamorphic process was probably released from the ultramafite-bearing melt

  1. Cyclic Cratonic Carbonates and Phanerozoic Calcite Seas.

    Science.gov (United States)

    Wilkinson, Bruce H.

    1982-01-01

    Discusses causes of cyclicity in cratonic carbonate sequences and evidence for and potential significance of postulated primary calcite sediment components in past Paleozoic seas, outlining problems, focusing on models explaining existing data, and identifying background. Future sedimentary geologists will need to address these and related areas…

  2. On the origin of cratonic `high-mu' isotopic signatures

    Science.gov (United States)

    Reimink, J. R.; Carlson, R.; Shirey, S. B.; Pearson, D. G.; Kamber, B. S.

    2017-12-01

    Some Archean cratons (i.e. Slave, Wyoming) contain Neoarchean granitoids with initial Pb isotopic compositions indicative of derivation from sources characterized by high time-integrated U/Pb ratios (high-mu [1]). Single-stage high-m precursor source reservoir separation from the depleted mantle occurred no later than 3.9 Ga [2]. However, multi-stage separation could have occurred in the Hadean, suggesting that recycling or reworking of Eoarchean/Hadean crust played a significant role in the generation of Neoarchean granitic crust in many cratons. The Sm-Nd system is similar to the U-Pb system in that it has a short-lived parent-daughter pair (146Sm-142Nd) that is sensitive to very early differentiation events, as well as a long-lived parent-daughter pair (147Sm-143Nd) that is sensitive to differentiation throughout all of Earth history. The 103 Ma half-life of 146Sm makes it sensitive only to Sm/Nd fractionation that occurred in the Hadean, providing a useful tracker for very early differentiation events. Indeed, evidence for Neoarchean remelting of ancient crust in another craton has come from analyses of the paired Sm-Nd isotope systems from the Hudson Bay terrane of the northeastern Superior Province. These results indicate that the source of 2.7 Ga Hudson Bay terrane granitoids was Hadean mafic crust, and not Eoarchean felsic crust [3]. Here, we present new data from Neoarchean granites located in the Slave and Wyoming cratons, along with modeling of the dual paired-isotope systems of U-Pb and Sm-Nd to achieve a tighter constraint on the composition of the precursors and the timing of their melting. Combining our newly collected 142Nd data with the high-m signature of these Neoarchean rocks, we evaluate precursor source separation ages along with the source Sm/Nd and U/Pb compositions. In the simplest end-member scenarios, use of the 142Nd system allows us to test whether the cratonic high-mu signature was created by melting of Hadean mafic crust or Eoarchean

  3. Western cratonic domain in Uruguay: geochronology

    International Nuclear Information System (INIS)

    Preciozzi, F.; Peel, F.; Muzio, R.; Ledesma, J.; Guerequiz, R.

    2009-01-01

    In this article has been studied the Western cratonic in Uruguay are divided into three major units: Piedra Alta Terrane, Valentines Block and Pavas Terrane. Piedra Alta Terrane has of evidence of Neo proterozoic orogenesis . Sarandi del Yi -Arroyo Solis Grande shear zone separate, it from Valentine block . Valentine Block separate it from Pavas terrane by Cueva del Tigre shear zone

  4. Regulations and instructions for RB reactor operation; Propisi i uputstva za rad reaktora RB

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1977-07-01

    This document includes regulations for reactor RB operation, behaviour and presence of staff in the reactor building; regulations for performing experiments at the RB reactor, regulations and int ructions for the reactor operators and other staff on duty. A chapter is devoted to instruction for reactor operation with the operating documentation and special duties of the operators. Regulations and instruction concerned with accidents are described with classification of accidents and evacuation plan. Annexes to this document include: the present status of the reactor; program for training the reactor operators; forms which are obligatory to be signed for any operating activity, and the certificate of the RB reactor lattice.

  5. Plume-induced dynamic instabilities near cratonic blocks: Implications for P-T-t paths and metallogeny

    NARCIS (Netherlands)

    Guillou-Frottier, L.; Burov, E.; Cloetingh, S.; Le Goff, E.; Deschamps, Y.; Huet, B.; Bouchot, V.

    2012-01-01

    Plume head - lithosphere interactions around cratonic blocks result in thermo-mechanical disturbances that lead to heating and burial phases of crustal rocks. We present results from numerical models of plume head - cratonic blocks interactions where a free upper surface condition and realistic

  6. Paleomagnetic study of 1765 Ma dyke swarm from the Singhbhum Craton: Implications to the paleogeography of India

    Science.gov (United States)

    Shankar, Ravi; Srinivasa Sarma, D.; Ramesh Babu, N.; Parashuramulu, V.

    2018-05-01

    We report the first key paleopole as a result of paleomagnetic study on a precisely dated 1765.3 ± 1.0 Ma WNW-ESE trending dyke swarm from Singhbhum Craton. This pole has been used in this study to propose the paleogeographic reconstruction of India with Baltica Craton and North China Craton. Incremental alternating field (AF) and thermal demagnetization, isolated high coercivity components with north to north-westerly declination and shallow negative inclination from 9 sampling sites which are representing different individual dykes. The primary origin of the ChRM is supported by the positive baked contact test. The WNW-ESE trending dykes yield a mean paleomagnetic direction with a declination = 329.2° and an inclination = -22.8° (k = 31.6; α95 = 9.3°). The positive bake contact test proves the primary nature of remanence. The pole position of Singhbhum Craton at 1765 Ma is 45°N, 311°E (dp = 5.2 and dm = 9.9). Paleogeographic reconstruction at ca. 1770 Ma, supported by geological, tectonic and metallogenic evidences indicate that the Baltica Craton and India linkage can be stable for at least ∼370 Ma (∼1770-1400 Ma). There is also reasonable evidence in support of India-North China Craton spatial proximity at ∼1770 Ma.

  7. Sr - an element shows the way - Applications of Sr isotopes for provenance, tracing and migration (Invited)

    Science.gov (United States)

    Prohaska, T.; Irrgeher, J.; Zitek, A.; Teschler Nicola, M.

    2010-12-01

    Strontium - named after the small Scottish town Strontian - as such is an element with little popularity. Firstly described by Martin Heinrich Klaproth in 1798, the metal is used in metallurgy to some extent whereas its compounds are interesting in glass industries, electronics and pyrotechnics. The element has chemical similarity to Ca and makes up 1/60 of the earth’s amount of the latter. Nonetheless, it is its isotopic composition which makes Sr so interesting for a large number of scientists. The natural composition of the four naturally occurring isotopes (84Sr, 86Sr 87Sr and 88Sr) varies in nature due to the radioactive decay of 87Rb to 87Sr. Thus, it was early recognized as geochronometer especially in Ca rich matrices. With increasing precision of applied methodology, the natural variation of the 87Sr/86Sr isotope ratio (analyzed at first mainly by thermal ionization mass spectrometry (TIMS)) became more and more popular in provenance studies. The natural variation of the ratio is mainly determined by the geological age and the original composition of the rock and can be used therefore as fingerprint of the local geology. The ratio is transferred with no significant fractionation via the water into plants and finally via the food chain into animal and human tissues (especially bones and teeth). As the element is chemically similar to Ca, it appears in most matrices. The use for provenance studies is supported by the fact that the long half life (4.8 x 1010 years) does not lead to an alteration during the time scales which are investigated (from recent samples to human or animal skeletal remains which date back up to 30.000 BC). The uniqueness of the system besides the natural variation is defined by the ubiquity in nature and the relatively high (and thus measurable) elemental concentration in most tissues. It was finally the advent of multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) which augmented the number of applications

  8. RB Research nuclear reactor RB reactor, Annual report for 2000

    International Nuclear Information System (INIS)

    Milosevic, M.

    2000-12-01

    Report on RB reactor operation during 2000 contains 3 parts. Part one contains a brief description of reactor operation and reactor components, relevant dosimetry data and radiation protection issues, personnel and financial data. Part two is devoted to maintenance of the reactor components, namely, fuel, heavy water, reactor vessel, heavy water circulation system, absorption rods and heavy water level-meters, maintenance of electronic, mechanical, electrical and auxiliary equipment. Part three contains data concerned with reactor operation and utilization with a comprehensive list of publications resulting from experiments done at the RB reactor. It contains data about reactor operation during previous 14 years, i.e. from 1986 - 2000

  9. ∼2.5 Ga late cratonisation events in Dharwar craton: insights from the gold mineralisation ages

    International Nuclear Information System (INIS)

    Srinivasa Sarma, D.; Ram Mohan, M.; McNaughton, Neal

    2013-01-01

    The history of volcanism, granitic magmatism, and gold mineralization is defined by U-Pb geochronology of magmatic zircons and hydrothermal monazite and xenotime respectively. The felsic volcanic host rocks from Hutti greenstone belt have a U-Pb zircon age of 258 ±7 Ma, about 40 m.y. older than the age of gold mineralization at 2547±10 Ma determined from hydrothermal monazite in the Hutti gold deposit. The syntectonic Kavital granitoid in the Hutti greenstone belt has a U-Pb zircon age of 2545±7 Ma, which overlaps with the timing of gold deposition and is consistent with structural interpretations. Zircon U-Pb ages for a felsic volcanic rock (2,588±10 Ma) and an intrusive granite (e''2,555±6 Ma) in the Gadag greenstone belt in the Western Dharwar Craton. In situ U-Pb dating of monazite and xenotime in gold reefs of the Gadag (2,522±6 Ma) and Ajjanahalli (2,520±9 Ma) gold deposits reveal a previously undated episode of gold mineralization at 2.52 Ga, substantially younger than the 2.55 Ga Hutti deposit in the eastern Dharwar Craton. The Hutti, Gadag and Ajjanahalli gold geochronology suggests that gold mineralization occurred throughout the Dharwar craton some 80 to 120 m.y. later than the major peak of Late Archean world-class orogenic gold mineralization in most other Archean cratons. Although gold mineralization across the craton postdates most of the magmatic activity and metamorphism at upper crustal levels, widespread thermal reworking of the lower middle crust, involving partial melting, metamorphism, and lower crustal granitoid intrusion, occurred concurrently with gold mineralization. It is likely that the large-scale hydrothermal fluid flow that produced widespread gold deposition was also part of this tectono-thermal event during the final stages of cratonization of the Dharwar Craton in southern India. (author)

  10. Half-life measurement of 89Rb

    International Nuclear Information System (INIS)

    Guo Xiaoqing; Yuan Daqing; Xu Lijun; Chen Kesheng; Wu Yongle; Zheng Yanming; Yao Shunhe

    2013-01-01

    89 Rb is an important fission product used for monitoring possible release of fission products from fuel element. The half-life is one of important nuclear parameters. The half-life of 89 Rb was determined using reference source method with two sets of HPGe detectors by place-relay way. In reference source method, the ratio of net full- energy peak areas from the measure nuclide and the reference source was used to avoid the count correction caused by dead time and pileup. For the very short half-life of 89 Rb, the half-life iterative method was used in data analysis and the translation method was used in data unification. Finally, the measured half-life of 89 Rb is (14.41±0.04) min. (authors)

  11. RV Ronald H. Brown Cruise RB1201 (EM122)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Cruise RB1201 was led by Chief Scientist Molly Baringer (AOML, NOAA, Miami) as per previous cruises RB0602, RB0701 and RB0901. The three main objectives were:...

  12. Production, quality control and initial imaging studies of [82mRb]RbCl for PET studies

    International Nuclear Information System (INIS)

    Rowshanfarzad, P.; Jalilian, A.R.; Kiyomarsi, M.; Sabet, M.; Karimian, A.R.; Moradkhani, S.; Mirzaii, M.

    2006-01-01

    Rubidium-82m was prepared via 15.4 MeV proton irradiation of a krypton-82 gaseous target (30% enrichment). Washing the target chamber with hot water yielded a Rb-82m containing solution, which was further purified using short column chromatography in order to remove organic/inorganic impurities. The flowthrough was formulated in normal saline for injection. Radionuclide, radiochemical and chemical purity tests were performed prior to administration to rats for imaging (radiochemical yield: 95-97%, radiochemical purity > 97%). Preliminary dual-head coincidence studies were performed to determine the distribution of [ 82m Rb]Rb in normal rats. For biodistribution studies, Rb-81 was injected to rats and tracer accumulation in heart, GI and bladder was determined after sacrification in time intervals. A yield of 1.3 GBq at EOB, 235.7 MBq/μAh was obtained. (authors)

  13. Rb1 loss modifies but does not initiate alveolar rhabdomyosarcoma

    Science.gov (United States)

    2013-01-01

    Background Alveolar rhabdomyosarcoma (aRMS) is a myogenic childhood sarcoma frequently associated with a translocation-mediated fusion gene, Pax3:Foxo1a. Methods We investigated the complementary role of Rb1 loss in aRMS tumor initiation and progression using conditional mouse models. Results Rb1 loss was not a necessary and sufficient mutational event for rhabdomyosarcomagenesis, nor a strong cooperative initiating mutation. Instead, Rb1 loss was a modifier of progression and increased anaplasia and pleomorphism. Whereas Pax3:Foxo1a expression was unaltered, biomarkers of aRMS versus embryonal rhabdomyosarcoma were both increased, questioning whether these diagnostic markers are reliable in the context of Rb1 loss. Genome-wide gene expression in Pax3:Foxo1a,Rb1 tumors more closely approximated aRMS than embryonal rhabdomyosarcoma. Intrinsic loss of pRb function in aRMS was evidenced by insensitivity to a Cdk4/6 inhibitor regardless of whether Rb1 was intact or null. This loss of function could be attributed to low baseline Rb1, pRb and phospho-pRb expression in aRMS tumors for which the Rb1 locus was intact. Pax3:Foxo1a RNA interference did not increase pRb or improve Cdk inhibitor sensitivity. Human aRMS shared the feature of low and/or heterogeneous tumor cell pRb expression. Conclusions Rb1 loss from an already low pRb baseline is a significant disease modifier, raising the possibility that some cases of pleomorphic rhabdomyosarcoma may in fact be Pax3:Foxo1a-expressing aRMS with Rb1 or pRb loss of function. PMID:24274149

  14. Geology of the Terre Adélie Craton (135 – 146˚ E)

    Science.gov (United States)

    Ménot, R.P.; Duclaux, G.; Peucat, J.J.; Rolland, Y.; Guillot, S.; Fanning, M.; Bascou, J.; Gapais, D.; Pêcher, A.

    2007-01-01

    More than 15 years of field and laboratory investigations on samples from Terre Adélie to the western part of George Vth Land (135 to 146°E) during the GEOLETA program allow a reassessment of the Terre Adélie Craton (TAC) geology. The TAC represents the largest exposed fragment of the East Antarctic Shield preserved from both Grenville and Ross tectono-metamorphic events. Therefore it corresponds to a well-preserved continental segment that developed from the Neoarchean to the Paleoproterozoic. Together with the Gawler Craton in South Australia, the TAC is considered as part of the Mawson continent, i.e. a striking piece of the Rodinia Supercontinent. However, this craton represents one of the less studied parts of the East Antarctic Shield. The three maps presented here clearly point out the extent of two distinct domains within the Terre Adélie Craton and suggest that the TAC was built up through a polyphased evolution during the Neoarchean-Siderian (c.a. 2.5Ga) and the Statherian (c.a. 1.7Ga) periods. These data support a complete re-assessment of the TAC geology and represent a valuable base for the understanding of global geodynamics changes during Paleoproterozoic times.

  15. Comparison of mantle lithosphere beneath early Triassic kimberlite fields in Siberian craton reconstructed from deep-seated xenocrysts

    Directory of Open Access Journals (Sweden)

    I.V. Ashchepkov

    2016-07-01

    Kharamai mantle clinopyroxenes represent three geochemical types: (1 harzburgitic with inclined linear REE, HFSE troughs and elevated Th, U; (2 lherzolitic or pyroxenitic with round TRE patterns and decreasing incompatible elements; (3 eclogitic with Eu troughs, Pb peak and high LILE content. Calculated parental melts for garnets with humped REE patterns suggest dissolution of former Cpx and depression means Cpx and garnets extraction. Clinopyroxenes from Ary-Mastakh fields show less inclined REE patterns with HMREE troughs and an increase of incompatible elements. Clinopyroxenes from Kuranakh field show flatter spoon-like REE patterns and peaks in Ba, U, Pb and Sr, similar to those in ophiolitic harzburgites. The PT diagrams for the mantle sections show high temperature gradients in the uppermost SCLM accompanied by an increase of P-Fe#Ol upward and slightly reduced thickness of the mantle keel of the Siberian craton, resulting from the influence of the Permian–Triassic superplume, but with no signs of delamination.

  16. Synthesis and characterization of the superonic-based secondary battery cell Ag/RbAg4I5/RbI3

    International Nuclear Information System (INIS)

    Effendi Nurdin; Jahja, A.K.; Purnama, S.

    2000-01-01

    The solid electrolyte material silver based, RbAg 4 I 5 had been used as electrolyte in making a secondary rechargeable battery cell with silver (Ag) as the anode and rubidium tri-iodide (RbI 3 ) as the cathode.The charge-discharge characteristics measurements and the battery polarization in normal atmospheric pressure, at ambient temperature had been carried out. It can be deduced that the cell configuration Ag/RbAg 4I5/ RbI 3 has performed as a secondary battery. The cell performed well with current density up to 230 μA/cm 2

  17. Identification of Marchfeld asparagus using Sr isotope ratio measurements by MC-ICP-MS.

    Science.gov (United States)

    Swoboda, S; Brunner, M; Boulyga, S F; Galler, P; Horacek, M; Prohaska, T

    2008-01-01

    This work focuses on testing and application of Sr isotope signatures for the fast and reliable authentication and traceability of Asparagus officinalis originating from Marchfeld, Austria, using multicollector inductively coupled plasma mass spectrometry after optimised Rb/Sr separation. The major sample pool comprises freeze-dried and microwave-digested asparagus samples from Hungary and Slovakia which are compared with Austrian asparagus originating from the Marchfeld region, which is a protected geographical indication. Additional samples from Peru, The Netherlands and Germany were limited in number and allowed therefore only restricted statistical evaluation. Asparagus samples from Marchfeld were harvested within two subsequent years in order to investigate the annual variation. The results show that the Sr isotope ratio is consistent within these 2 years of investigation. Moreover, the Sr isotope ratio of total Sr in soil was found to be significantly higher than in an NH4NO3 extract, reflecting the mobile (bioavailable) phase. The isotope composition in the latter extract corresponds well to the range found in the asparagus samples in Marchfeld, even though the concentration of Sr in asparagus shows no direct correlation to the concentration of Sr in the mobile phase of the soil. The major question was whether the 'Marchfelder Spargel' can be distinguished from samples from the neighbouring countries of Hungary and Slovakia. According to our findings, they can be clearly (100%) singled out from the Hungarian samples and can be distinguished from the Slovakian asparagus samples with a probability of more than 80%.

  18. Production of 83Rb and development of a generator for the separation of sup(83m)Kr from 83Rb

    International Nuclear Information System (INIS)

    Krueger, A.; Lieser, K.H.

    1975-01-01

    83 Rb was produced from rubidium by a (γ,2n)-reaction. The specific activity in the irradiated samples of RbCl was 0.2 to 0.3mCi 83 Rb/gRb. For the separation of the sup(83m)Kr in the liquid phase the cation exchanger Dowex-50WX12 proved to be a suitable carrier. sup(83m)Kr was eluted by bidistilled water. The yield ranged from 85-95%, at an elution time of 3 minutes. The decontamination factor was > 10 6 . The separation of sup(83m)Kr in the gaseous phase was effected by floating a 83 Rb loaded column with an elution gas. The best results were obtained with a generator containing aluminium oxide as carrier for 83 Rb. The yield of sup(83m)Kr was 90-100%, the decontamination factor > 10 4 , the time needed for the separation 20-60 seconds. All generators proved to be very safe even after long time of use. (orig.) [de

  19. Petrochemical and Sr-Nd isotope investigations of Cretaceous intrusive rocks and their enclaves in the Togouchi-Yoshiwa district, northwest Hiroshima prefecture, SW Japan

    International Nuclear Information System (INIS)

    Ishioka, Jun; Iizumi, Shigeru

    2003-01-01

    Petrographic, petrochemical and Sr-Nd isotopic data are presented for granitoids and microdioritic enclaves from two Cretaceous stocks (Togouchi granodiorite and Tateiwayama granite porphyry) from the Togouchi-Yoshiwa district, northwest Hiroshima prefecture, SW Japan. The data are used to examine the genetic relationships between the microdioritic enclaves and their granitoid hosts. The granodiorite, granite porphyry and the microdioritic enclaves are all calc-alkaline in nature, and belong to the I-type ilmenite series. The Togouchi graniodiorite has a Rb-Sr whole rock isochron age of 85.6±4.7 Ma with an initial Sr isotope ratio (SrI) of 0.70634±0.00012 (2σ). The Tateiwayama granite porphyry has a slightly younger Rb-Sr whole isochron age (77.4±3.1 Ma) but similar SrI of 0.70653±0.00015, suggesting that both stocks may have been derived from the same source. Despite diverse whole rock chemistry, the microdioritic enclaves in the respective intrusives have quite similar initial Sr and Nd isotope ratios, suggesting that they formed by fractional crystallization of a single magma, and also that the source of the enclaves in both intrusives had similar geochemical characteristics. In both stocks, however, the enclaves have distinctly lower initial Sr isotope ratios than their respective host rocks, indicating that they were derived from a different source than their hosts. In view of the geochemical and Sr-Nd isotope data, we infer that the enclave magmas were derived from a similar LILE- and LREE-enriched source to that of the Cretaceous basalts and gabbroic-dioritic rocks that are sporadically distributed in SW Japan. Such mafic to intermediate magmas were probably derived from the upper mantle, and transferred both heat and material to the lower crust, thus producing granitic magmas by partial melting. Successive mafic magmas or their differentiates could then have been injected into the granitic magma chamber, trapped and quenched, resulting in the formation

  20. Sr isotope geochemistry of voluminous acidic pyroclastics erupted at 1-3 Ma in Northeast Japan

    International Nuclear Information System (INIS)

    Shirahase, Teruo; Tamanyu, Shiro; Togashi, Shigeko

    1989-01-01

    Sr isotope ratios are analyzed for voluminous acidic pyroclastics erupted at 1 - 3 Ma in five areas on the volcanic front of Northeast Japan. The initial values of 87 Sr/ 86 Sr ratios range from 0.7040 to 0.7055. There is no significant difference in ratios between 1 - 3 Ma acidic pyroclastics and 0 - 1 Ma andesitic volcanics in each area in spite of differences in age and in mean SiO 2 content. On the other hand, the ratios in both of 1 - 3 Ma and 0 - 1 Ma volcanics vary along arc in the same manner. The changes of Sr and Rb contents in each area are consistent with systematic changes by fractional crystallization. The low 87 Sr/ 86 Sr ratios and chemistry suggest that 1 - 3 Ma acidic pyroclastics of Northeast Japan formed by a high degree of fractional crystallization from basic magma which is common in genesis with young andesitic volcanism. The mechanisms of the formation of the basic magma and the character of mantle source in each area have not changed for the past 3 Ma. Degrees of fractional crystallization changed with changes of the tectonic condition of shallow magma chamber from a weak horizontal compression stress field to a strong one. (author)

  1. On most ancient geologic events on the Anabar Shield

    International Nuclear Information System (INIS)

    Melnikow, A.I.; Lepin, V.S.; Solodyankina, V.N.; Kolosnicyna, T.I.; Oxmann, V.S.; Petrov, A.F.

    1987-01-01

    The Anabar Shield is considered in geologic literature as one of the oldest formations of the Earth. In present work a special selection of two series of samples was undertaken: crystallic schists of the Daldynskaya Series and plagio-granito-gneisses from the basin of the Knyasevaya River. Concentrations of Rb, Sr, K and 87 Sr/ 86 Sr, 87 Rb/ 86 Sr isotope ratios were determined. A Rb-Sr isochron for plagio-granito-gneisses gives ages 1.1 and 1.8 by (depending on interpretation). According to the data obtained the plagio-granito-gneisses may not be regarded as oldest formations of the Earth. In contrast to these, the crystallic schists allow to obtain a reliable Rb-Sr isochron age of 3.8 ± 0.2 by with ( 87 Sr/ 86 Sr) 0 = 0.7010. Thus, on the Anabar shield one of the oldest events of the Earth is detected. It is stated that K/Rb and 87 Rb/ 86 Sr ratios are correlated and are quite specific for oldest formations of the Earth. (author)

  2. Craton-derived alluvium as a major sediment source in the Himalayan Foreland Basin of India

    DEFF Research Database (Denmark)

    Sinha, R.; Kettanah, Y.; Gibling, M.R.

    2009-01-01

    of the Bundelkhand Complex. Along the Yamuna Valley the red alluvium is overlain by gray alluvium dated at 82–35 ka ago, which also yields a cratonic signature, with large amounts of smectite derived from the Deccan Traps. Cratonic contributions are evident in alluvium as young as 9 ka ago in a section 25 km north...

  3. Crustal structure of the Siberian craton and the West Siberian basin

    DEFF Research Database (Denmark)

    Cherepanova, Yulia; Artemieva, Irina; Thybo, Hans

    2013-01-01

    We present a digital model SibCrust of the crustal structure of the Siberian craton (SC) and the West Siberian basin (WSB), based on all seismic profiles published since 1960 and sampled with a nominal interval of 50. km. Data quality is assessed and quantitatively assigned to each profile based...... and ~. 6.2-6.6. km/s in parts of the WSB and SC. Exceptionally high basement Vp velocities (6.8-7.0. km/s) at the northern border between the SC and the WSB indicate the presence of magmatic intrusions and are proposed to mark the source zone of the Siberian LIP. The cratonic crust generally consists...

  4. Sources of metals in the Porgera gold deposit, Papua New Guinea: Evidence from alteration, isotope, and noble metal geochemistry

    Science.gov (United States)

    Richards, Jeremy P.; McCulloch, Malcolm T.; Chappell, Bruce W.; Kerrich, Robert

    1991-02-01

    The Porgera gold deposit is spatially and temporally associated with the Late Miocene, mafic, alkalic, epizonal Porgera Intrusive Complex (PIC), located in the highlands of Papua New Guinea (PNG). The highlands region marks the site of a Tertiary age continent-island-arc collision zone, located on the northeastern edge of the Australasian craton. The PIC was emplaced within continental crust near the Lagaip Fault Zone, which represents an Oligocene suture between the craton and volcano-sedimentary rocks of the Sepik terrane. Magmatism at Porgera probably occurred in response to the Late Miocene elimination of an oceanic microplate, and subsequent Early Pliocene collision between the craton margin and an arc system located on the Bismarck Sea plate. Gold mineralization occurred within 1 Ma of the time of magmatism. Metasomatism accompanying early disseminated Au mineralization in igneous host rocks resulted in additions of K, Rb, Mn, S, and CO 2, and depletions of Fe, Mg, Ca, Na, Ba, and Sr; rare-earth and high-field-strength elements remained largely immobile. Pervasive development of illite-K-feldspar-quartz-carbonate alteration assemblages suggests alteration by mildly acidic, 200 to 350°C fluids, at high water/ rock ratios. Strontium and lead isotopic compositions of minerals from early base-metal sulphide veins associated with K-metasomatism, and later quartz-roscoelite veins carrying abundant free gold and tellurides, are remarkably uniform (e.g., 87Sr /86Sr = 0.70745 ± 0.00044 [n = 10] , 207Pb /204Pb = 15.603 ± 0.004 [n = 15] ). These compositions fall between those of unaltered igneous and sedimentary host rocks, and specifically sedimentary rocks from the Jurassic Om Formation which underlies the deposit (igneous rocks: 87Sr /86Sr ≈ 0.7035 , 207Pb /204Pb ≈ 15.560 ; Om Formation: 87Sr /86Sr |t~ 0.7153 , 207Pb /204Pb ≈ 15.636 ). It is therefore suggested that the hydrothermal fluids acquired their Sr and Pb isotopic signatures by interaction with, or

  5. Application of boat method in emissive flame photometry for determination of Li, Rb, Cs, Na, K, Ca, Sr, Ba

    International Nuclear Information System (INIS)

    Orlov, N.A.; Pobedonostsev, V.A.; Savel'ev, Yu.A.

    1976-01-01

    Study of the flame temperature and dependence of adsorbance on the C/O ratio over the boat for the carbide forming elements and the effect of material, thickness, and the height of the boat on the vaporization of alkaline and alkaline earth metals is described. For a boat (70x8, and 0.3 mm thickness), made from Cu, brass, and Ni, the fall in temperature over the boat was 70, 130, 250, and 340 0 , respectively, for air-C 2 H 2 and 50, 100, 210, and 280 0 for N 2 O-C 2 H 2 flame. Introduction of the boat increases the C/O ratio in the analytical zone of the flame, probably caused by a creation of a shaded space, immediately above the boat. Smaller amounts of atmospheric O enter into the space, when compared with the flame in the absence of the boat. The increase in the C/O ratio decreases the absorbance, which in turn, is caused by the fall in temperature and formation of carbides. Time lag between heating of the boat and the initiation of vaporization of the sample and the duration of evaporation impulse were measured. Solutions of CsCl, containing 1 μg Cs/ml were used at 852.1 nm. The boats, previously treated with 0.1% polystyrene in C 6 H 6 , to give a hydrophobic surface and an uniform salt layer distribution, containing the sample were dried under an ir lamp and introduced into the flame. The dependence of Cs emission on the thickness of the different materials (Ni, Cu, Ta) and heights of boats in the air-C 2 H 2 flame is illustrated. The duration of the emission impulse decreases linearly with the decrease of thickness of the boat for all materials tested. Limits of detection of Na, K, Li, Rb, Cs, Ca, Sr, and Ba were determined by using the equilibrium and the boat methods, the latter being some 1-2 orders lower than the former

  6. Inclusions of crichtonite-group minerals in Cr-pyropes from the Internatsionalnaya kimberlite pipe, Siberian Craton: Crystal chemistry, parageneses and relationships to mantle metasomatism

    Science.gov (United States)

    Rezvukhin, Dmitriy I.; Malkovets, Vladimir G.; Sharygin, Igor S.; Tretiakova, Irina G.; Griffin, William L.; O'Reilly, Suzanne Y.

    2018-05-01

    Cr-pyrope xenocrysts and associated inclusions of crichtonite-group minerals from the Internatsionalnaya kimberlite pipe were studied to provide new insights into processes in the lithospheric mantle beneath the Mirny kimberlite field, Siberian craton. Pyropes are predominantly of lherzolitic paragenesis (Cr2O3 2-6 wt%) and have trace-element spectra typical for garnets from fertile mantle (gradual increase in chondrite-normalized values from LREE to MREE-HREE). Crichtonite-group minerals commonly occur as monomineralic elongated inclusions, mostly in association with rutile, Mg-ilmenite and Cr-spinel within individual grains of pyrope. Sample INT-266 hosts intergrowth of crichtonite-group mineral and Cl-apatite, while sample INT-324 contains polymineralic apatite- and dolomite-bearing assemblages. Crichtonite-group minerals are Al-rich (1.1-4.5 wt% Al2O3), moderately Zr-enriched (1.3-4.3 wt% ZrO2), and are Ca-, Sr-, and occasionally Ba-dominant in terms of A-site occupancy; they also contain significant amounts of Na and LREE. T-estimates and chemical composition of Cr-pyropes imply that samples represent relatively low-T peridotite assemblages with ambient T ranging from 720 to 820°С. Projected onto the 35 mW/m2 cratonic paleogeotherm for the Mirny kimberlite field (Griffin et al., 1999b. Tectonophysics 310, 1-35), temperature estimates yield a P range of 34-42 kbar ( 110-130 km), which corresponds to a mantle domain in the uppermost part of the diamond stability field. The presence of crichtonite-group minerals in Cr-pyropes has petrological and geochemical implications as evidence for metasomatic enrichment of some incompatible elements in the lithospheric mantle beneath the Mirny kimberlite field. The genesis of Cr-pyropes with inclusions of crichtonite-group minerals is attributed to the percolation of Ca-Sr-Na-LREE-Zr-bearing carbonate-silicate metasomatic agents through Mg- and Cr-rich depleted peridotite protoliths. The findings of several potentially

  7. U-Pb zircon geochronology of intrusive and basement rocks in the Jacurici Valley region, Sao Francisco Craton, BA, Brazil; Geocronologia U-Pb em zircao de rochas intrusivas e de embasamento na regiao do Vale do Jacurici, Craton do Sao Francisco, BA

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, Carlos Jose Sobrinho da; Frantz, Jose Carlos; Marques, Juliana Charao; Roos, Siegbert; Peixoto, Vinicius Medina, E-mail: silveira.carlosjose@hotmail.com, E-mail: jose.frantz@propesq.ufrgs.br, E-mail: juliana.marques@ufrgs.br, E-mail: sig_duda@yahoo.com.br, E-mail: vinimpeixoto@hotmail.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Laboratorio de Geologia Isotopica; Queiroz, Waldemir Jose Alves de, E-mail: waldemirqueiroz@hotmail.com [Companhia de Ferro Ligas da Bahia (FERBASA), Pojuca, BA (Brazil)

    2015-09-15

    The Jacurici Complex, located in the NE of the Sao Francisco Craton, is constituted by several Cr-mineralized mafic-ultramafic N-S bodies, possible fragments of a single sill disrupted during deformation. Some works suggest it is intruded on the Serrinha Block while others consider it in the Salvador-Curaca Belt. The basement on this region is informally divided into paragneisses and orthogneisses; the latter is supposed to be younger considering it is less deformed. Petrography revealed that some of the paragneisses are alkali-feldspar granite strongly milonitized. The orthogneisses occur at the north and consist, at least in part, of monzogranites with heterogeneous deformation, locally of low temperature. U-Pb zircon dating were performed for five representative samples. Just three provided good concordia ages. A mafic rock produced a 2102 ± 5 Ma age and it is petrographically similar to the metanorites described in the Jacurici Complex, being interpreted as the record of the first pulses of the mafic magmatism. A monzogranite yielded a 2995 ± 15 Ma age, older than expected, related to the Serrinha Block. The alkali-feldspar granite yielded a 2081 ± 3 Ma age. The Itiuba Syenite and the pegmatites that crosscut the Jacurici Complex have similar ages. Considering the lack of information about the supracrustal sequence that hosts the intrusive alkaline and mafic-ultramafic rocks at the Ipueira and the Medrado areas, it is possible that part of the terrain belongs to the Salvador-Curaca Belt. We suggest that the Jacurici Complex could be intruded after the tectonic amalgamation between the Serrinha Block and the older part of the Salvador-Curaca Belt and, therefore, could be hosted by both terrains. (author)

  8. The stratigraphy of the Marydale Group west of Prieska

    International Nuclear Information System (INIS)

    Potgieter, G.J.A.; Botha, B.J.V.

    1982-01-01

    Isolated outcrops of the Marydale Group are present in a narrow belt along the south-western edge of the Kaapvaal Craton. The belt outcrops along a total distance of 120 km from Soetvlei, 35 km south-east of Prieska, to Marydale. The best exposure of this unit is west of Prieska, between Prieskapoort and Copperton. Outcrops are generally very poor except along a few road and rail cuttings. The Marydale Group consists of a quick alternation of immature clastic and volcanoclastic rocks and lava. The exact stratigraphic position of the Marydale Group could not be deduced from field evidence. Provisional Pb/Pb and Rb-Sr isotope work on the banded iron formation the Modderfontein Formation and the metalava of the Uitzigt Formation respectively, indicate an age of 3 100 Ma

  9. Differential gene expression profiling of endometrium during the mid-luteal phase of the estrous cycle between a repeat breeder (RB) and non-RB cows.

    Science.gov (United States)

    Hayashi, Ken-Go; Hosoe, Misa; Kizaki, Keiichiro; Fujii, Shiori; Kanahara, Hiroko; Takahashi, Toru; Sakumoto, Ryosuke

    2017-03-23

    Repeat breeding directly affects reproductive efficiency in cattle due to an increase in services per conception and calving interval. This study aimed to investigate whether changes in endometrial gene expression profile are involved in repeat breeding in cows. Differential gene expression profiles of the endometrium were investigated during the mid-luteal phase of the estrous cycle between repeat breeder (RB) and non-RB cows using microarray analysis. The caruncular (CAR) and intercaruncular (ICAR) endometrium of both ipsilateral and contralateral uterine horns to the corpus luteum were collected from RB (inseminated at least three times but not pregnant) and non-RB cows on Day 15 of the estrous cycle (4 cows/group). Global gene expression profiles of these endometrial samples were analyzed with a 15 K custom-made oligo-microarray for cattle. Immunohistochemistry was performed to investigate the cellular localization of proteins of three identified transcripts in the endometrium. Microarray analysis revealed that 405 and 397 genes were differentially expressed in the CAR and ICAR of the ipsilateral uterine horn of RB, respectively when compared with non-RB cows. In the contralateral uterine horn, 443 and 257 differentially expressed genes were identified in the CAR and ICAR of RB, respectively when compared with non-RB cows. Gene ontology analysis revealed that genes involved in development and morphogenesis were mainly up-regulated in the CAR of RB cows. In the ICAR of both the ipsilateral and contralateral uterine horns, genes related to the metabolic process were predominantly enriched in the RB cows when compared with non-RB cows. In the analysis of the whole uterus (combining the data above four endometrial compartments), RB cows showed up-regulation of 37 genes including PRSS2, GSTA3 and PIPOX and down-regulation of 39 genes including CHGA, KRT35 and THBS4 when compared with non-RB cows. Immunohistochemistry revealed that CHGA, GSTA3 and PRSS2 proteins

  10. Lateral heterogeneity and vertical stratification of cratonic lithospheric keels: a case study of the Siberian craton

    DEFF Research Database (Denmark)

    Artemieva, Irina; Cherepanova, Yulia; Herceg, Matija

    2014-01-01

    by regional xenolith P-T arrays,lithosphere density heterogeneity as constrained by free-board and satellite gravity data, and the non-thermalpart of upper mantle seismic velocity heterogeneity based on joint analysis of thermal and seismic tomography data.Density structure of the cratonic lithosphere...... and strongly depleted lithospheric mantle of the Archean nuclei, particularly below the Anabar shield.Since we cannot identify the depth distribution of density anomalies, we complement the approach by seismicdata. An analysis of temperature-corrected seismic velocity structure indicates strong vertical...

  11. Identification of Marchfeld asparagus using Sr isotope ratio measurements by MC-ICP-MS

    Energy Technology Data Exchange (ETDEWEB)

    Swoboda, S; Brunner, M; Boulyga, S F; Galler, P; Prohaska, T [University of Natural Resources and Applied Life Sciences, Department of Chemistry-VIRIS Project, Vienna (Austria); Horacek, M [Austrian Research Centers GmbH, Seibersdorf (Austria)

    2008-01-15

    This work focuses on testing and application of Sr isotope signatures for the fast and reliable authentication and traceability of Asparagus officinalis originating from Marchfeld, Austria, using multicollector inductively coupled plasma mass spectrometry after optimised Rb/Sr separation. The major sample pool comprises freeze-dried and microwave-digested asparagus samples from Hungary and Slovakia which are compared with Austrian asparagus originating from the Marchfeld region, which is a protected geographical indication. Additional samples from Peru, the Netherlands and Germany were limited in number and allowed therefore only restricted statistical evaluation. Asparagus samples from Marchfeld were harvested within two subsequent years in order to investigate the annual variation. The results show that the Sr isotope ratio is consistent within these 2 years of investigation. Moreover, the Sr isotope ratio of total Sr in soil was found to be significantly higher than in an NH{sub 4}NO{sub 3} extract, reflecting the mobile (bioavailable) phase. The isotope composition in the latter extract corresponds well to the range found in the asparagus samples in Marchfeld, even though the concentration of Sr in asparagus shows no direct correlation to the concentration of Sr in the mobile phase of the soil. The major question was whether the 'Marchfelder Spargel' can be distinguished from samples from the neighbouring countries of Hungary and Slovakia. According to our findings, they can be clearly (100%) singled out from the Hungarian samples and can be distinguished from the Slovakian asparagus samples with a probability of more than 80%. (orig.)

  12. Identification of Marchfeld asparagus using Sr isotope ratio measurements by MC-ICP-MS

    Energy Technology Data Exchange (ETDEWEB)

    Swoboda, S.; Brunner, M.; Boulyga, S.F.; Galler, P.; Prohaska, T. [University of Natural Resources and Applied Life Sciences, Department of Chemistry-VIRIS Project, Vienna (Austria); Horacek, M. [Austrian Research Centers GmbH, Seibersdorf (Austria)

    2008-01-15

    This work focuses on testing and application of Sr isotope signatures for the fast and reliable authentication and traceability of Asparagus officinalis originating from Marchfeld, Austria, using multicollector inductively coupled plasma mass spectrometry after optimised Rb/Sr separation. The major sample pool comprises freeze-dried and microwave-digested asparagus samples from Hungary and Slovakia which are compared with Austrian asparagus originating from the Marchfeld region, which is a protected geographical indication. Additional samples from Peru, the Netherlands and Germany were limited in number and allowed therefore only restricted statistical evaluation. Asparagus samples from Marchfeld were harvested within two subsequent years in order to investigate the annual variation. The results show that the Sr isotope ratio is consistent within these 2 years of investigation. Moreover, the Sr isotope ratio of total Sr in soil was found to be significantly higher than in an NH{sub 4}NO{sub 3} extract, reflecting the mobile (bioavailable) phase. The isotope composition in the latter extract corresponds well to the range found in the asparagus samples in Marchfeld, even though the concentration of Sr in asparagus shows no direct correlation to the concentration of Sr in the mobile phase of the soil. The major question was whether the 'Marchfelder Spargel' can be distinguished from samples from the neighbouring countries of Hungary and Slovakia. According to our findings, they can be clearly (100%) singled out from the Hungarian samples and can be distinguished from the Slovakian asparagus samples with a probability of more than 80%. (orig.)

  13. First-principles calculations of two cubic fluoropervskite compounds: RbFeF3 and RbNiF3

    Science.gov (United States)

    Mubarak, A. A.; Al-Omari, Saleh

    2015-05-01

    We present first-principles calculations of the structural, elastic, electronic, magnetic and optical properties for RbFeF3 and RbNiF3. The full-potential linear augmented plan wave (FP-LAPW) method within the density functional theory was utilized to perform the present calculations. We employed the generalized gradient approximation as exchange-correlation potential. It was found that the calculated analytical lattice parameters agree with previous studies. The analysis of elastic constants showed that the present compounds are elastically stable and anisotropic. Moreover, both compounds are classified as a ductile compound. The calculations of the band structure and density functional theory revealed that the RbFeF3 compound has a half-metallic behavior while the RbNiF3 compound has a semiconductor behavior with indirect (M-Γ) band gap. The ferromagnetic behavior was studied for both compounds. The optical properties were calculated for the radiation of up to 40 eV. A beneficial optics technology is predicted as revealed from the optical spectra.

  14. Updating the Geologic Barcodes for South China: Discovery of Late Archean Banded Iron Formations in the Yangtze Craton.

    Science.gov (United States)

    Ye, Hui; Wu, Chang-Zhi; Yang, Tao; Santosh, M; Yao, Xi-Zhu; Gao, Bing-Fei; Wang, Xiao-Lei; Li, Weiqiang

    2017-11-08

    Banded iron formations (BIFs) in Archean cratons provide important "geologic barcodes" for the global correlation of Precambrian sedimentary records. Here we report the first finding of late Archean BIFs from the Yangtze Craton, one of largest Precambrian blocks in East Asia with an evolutionary history of over 3.3 Ga. The Yingshan iron deposit at the northeastern margin of the Yangtze Craton, displays typical features of BIF, including: (i) alternating Si-rich and Fe-rich bands at sub-mm to meter scales; (ii) high SiO 2  + Fe 2 O 3total contents (average 90.6 wt.%) and Fe/Ti ratios (average 489); (iii) relative enrichment of heavy rare earth elements and positive Eu anomalies (average 1.42); (iv) and sedimentary Fe isotope compositions (δ 56 Fe IRMM-014 as low as -0.36‰). The depositional age of the BIF is constrained at ~2464 ± 24 Ma based on U-Pb dating of zircon grains from a migmatite sample of a volcanic protolith that conformably overlied the Yingshan BIF. The BIF was intruded by Neoproterozoic (805.9 ± 4.7 Ma) granitoids that are unique in the Yangtze Craton but absent in the North China Craton to the north. The discovery of the Yingshan BIF provides new constraints for the tectonic evolution of the Yangtze Craton and has important implications in the reconstruction of Pre-Nuna/Columbia supercontinent configurations.

  15. New Constraints on Upper Mantle Structure Underlying the Diamondiferous Central Slave Craton, Canada, from Teleseismic Body Wave Tomography

    Science.gov (United States)

    Esteve, C.; Schaeffer, A. J.; Audet, P.

    2017-12-01

    Over the past number of decades, the Slave Craton (Canada) has been extensively studied for its diamondiferous kimberlites. Not only are diamonds a valuable resource, but their kimberlitic host rocks provide an otherwise unique direct source of information on the deep upper mantle (and potentially transition zone). Many of the Canadian Diamond mines are located within the Slave Craton. As a result of the propensity for diamondiferous kimberlites, it is imperative to probe the deep mantle structure beneath the Slave Craton. This work is further motivated by the increase in high-quality broadband seismic data across the Northern Canadian Cordillera over the past decade. To this end we have generated a P and S body wave tomography model of the Slave Craton and its surroundings. Furthermore, tomographic inversion techniques are growing ever more capable of producing high resolution Earth models which capture detailed structure and dynamics across a range of scale lengths. Here, we present preliminary results on the structure of the upper mantle underlying the Slave Craton. These results are generated using data from eight different seismic networks such as the Canadian National Seismic Network (CNSN), Yukon Northwest Seismic Network (YNSN), older Portable Observatories for Lithospheric Analysis and Reseach Investigating Seismicity (POLARIS), Regional Alberta Observatory for Earthquake Studies Network (RV), USArray Transportable Array (TA), older Canadian Northwest Experiment (CANOE), Batholith Broadband (XY) and the Yukon Observatory (YO). This regional model brings new insights about the upper mantle structure beneath the Slave Craton, Canada.

  16. The peculiar case of Marosticano xenoliths: a cratonic mantle fragment affected by carbonatite metasomatism in the Veneto Volcanic Province (Northern Italy)

    Science.gov (United States)

    Brombin, Valentina; Bonadiman, Costanza; Coltorti, Massimo; Florencia Fahnestock, M.; Bryce, Julia G.; Marzoli, Andrea

    2017-04-01

    the typical OSMA array (Arai, 1994b) is observed in typical on-craton mantle rocks (Downes et al., 2004). To corroborate the cratonic "flavour" of these peridotites, in-situ trace element analyses show that Marosticano clinopyroxene have modified their residual characteristics by interaction with deep metasomatic melt, which was able to strong enrich in U, Th, LILE (Rb-Ba) and LREE with respect to the restitic preserved HREE and HFSE (e.g. Nb, Ta, Zr and Hf) contents. The general clinopyroxene trace element distribution and elemental ratios ((La/Yb)N and Ti/Eu; Coltorti et al., 1999) are consistent with enrichment provided by a carbonatitic rather than a silicate metasomatizing agent. To characterize the chemical-physical frame of the MA mantle segment, peridotites equilibration temperatures and oxygen fugacities were also estimated and compared with those of the other VVP xenoliths. The latter comparison leads to i) Marosticano samples record relatively high oxidation conditions (as Mts. Lessini peridotites) in agreement with the range assigned to continental lithosphere (Foley et al., 2011) and ii) these T-fO2 values account for CO2 mole fractions dissolved in a potential metasomatic melt close to 1, further supporting the carbonatitic nature of the infiltrating melt. In this case it can be speculated that the usually low oxidizing conditions of the cratonic mantle have been augmented by the interaction with a carbonatitic melt or with a CO2-rich fluid released by the reaction with a peridotitic matrix. References Arai, S., 1994b. Compositional variation of olivine chromian spinel in Mg-rich magmas as a guide to their residual spinel peridotites. Journal of Volcanology and Geothermal Research 59, 279-293. Beccaluva L., Bianchini G., Bonadiman C., Coltorti M., Milani L., Salvini L., Siena F., Tassinari R. (2007). Intraplate lithospheric and sublithospheric components in the Adriatic domain: Nephelinite to tholeiite magma generation in the Paleogene Veneto Volcanic

  17. RB research nuclear reactor - Annual report for 1986, I - III; Istrazivacki nuklearni reaktor RB (Izvestaj o radu u 1986. godini), I-III

    Energy Technology Data Exchange (ETDEWEB)

    Markovic, H; Pesic, M; Vranic, S; Petronijevic, M; Jevremovic, M; Ilic, I [Boris Kidric Institute of Nuclear Sciences Vinca, Beograd (Yugoslavia)

    1987-07-01

    This report includes data concerning the RB reactor operation in 1986, state of the reactor components, data about the employed personnel and the database of experimental and other reactor related devices. It is made of 3 parts: Engineering description and operation of the RB reactor including dosimetry, reactor staff data and financial report; Reactor facility components and maintenance; RB reactor operation and utilization in 1986. Izvestaj pokazuje podatke o radu reaktora RB u toku 1986. godine, stanje reaktorske opreme, podatke o angazovanom osoblju na reaktoru i datoteku sa podacima o eksperimentalnoj i drugoj opremi reaktora RB. Sastoji se od 3 dela: tehnicki opis, pogon i rad reaktora, oprema postrojenja i njeno odrzavanje, koriscenje reaktora u 1986. godini.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-07-01

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

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

    International Nuclear Information System (INIS)

    Teixeira, Wilson; Avila, Ciro Alexandre; Nunes, Luciana Cabral

    2008-01-01

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

  20. Mg-Fe Isotope Systems of Mantle Xenoliths: Constrains on the Evolution of Siberian Craton

    Science.gov (United States)

    An, Y.; Kiseeva, E. S.; Sobolev, N. V.; Zhang, Z.

    2017-12-01

    Mantle xenoliths bring to the surface a variety of lithologies (dunites, lherzolites, harzburgites, wehrlites, eclogites, pyroxenites, and websterites) and represent snapshots of the geochemical processes that occur deep within the Earth. Recent improvements in the precision of the MC-ICP-MS measurements have allowed us to expand the amount of data on Mg and Fe isotopes for mantle-derived samples. For instance, to constrain the isotopic composition of the Earth based on the study of spinel and garnet peridotites (An et al., 2017; Teng et al., 2010), to trace the origin and to investigate the isotopic fractionation mechanism during metamorphic process using cratonic or orogenic eclogites (Li et al., 2011; Wang et al., 2012) and to reveal the metasomatism-induced mantle heterogeneity by pyroxenites (Hu et al., 2016). Numerous multi-stage modification events and mantle layering are detected in the subcontinental lithospheric mantle under the Siberian craton (Ashchepkov et al., 2008a; Sobolev et al., 1975, etc). Combined analyses of Mg and Fe isotopic systems could provide new constraints on the formation and evolution of the ancient cratonic mantle. In order to better constrain the magnitude and mechanism of inter-mineral Mg and Fe isotopic fractionations at high temperatures, systematic studies of mantle xenoliths are needed. For example, theoretical calculations and natural samples measurements have shown that large equilibrium Mg isotope fractionations controlled by the difference in coordination number of Mg among minerals could exist (Huang et al., 2013; Li et al., 2011). Thus, the Mg isotope geothermometer could help us trace the evolution history of ancient cratons. In this study we present Mg and Fe isotopic data for whole rocks and separated minerals (clinopyroxene (cpx) and garnet (grt)) from different types of mantle xenoliths (garnet pyroxenites, eclogites, grospydites and garnet peridotites) from a number of kimberlite pipes in Siberian craton (Udachnaya

  1. RB reactor noise analysis; Analiza sumova reaktora RB

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, M; Velickovic, Lj; Markovic, V; Jovanovic, S [Institut za nuklearne nauke Boris Kidric, Vinca, Beograd (Yugoslavia)

    1964-07-01

    Statistical fluctuations of reactivity represent reactor noise. Analysis of reactor noise enables determining a series of reactor kinetic parameters. Fluctuations of power was measured by ionization chamber placed next to the tank of the RB reactor. The signal was digitized by an analog-digital converter. After calculation of the mean power, 3000 data obtained by sampling were analysed.

  2. Silencing of RB1 and RB2/P130 during adipogenesis of bone marrow stromal cells results in dysregulated differentiation.

    Science.gov (United States)

    Capasso, Stefania; Alessio, Nicola; Di Bernardo, Giovanni; Cipollaro, Marilena; Melone, Mariarosa Ab; Peluso, Gianfranco; Giordano, Antonio; Galderisi, Umberto

    2014-01-01

    Bone marrow adipose tissue (BMAT) is different from fat found elsewhere in the body, and only recently have some of its functions been investigated. BMAT may regulate bone marrow stem cell niche and plays a role in energy storage and thermogenesis. BMAT may be involved also in obesity and osteoporosis onset. Given the paramount functions of BMAT, we decided to better clarify the human bone marrow adipogenesis by analyzing the role of the retinoblastoma gene family, which are key players in cell cycle regulation. Our data provide evidence that the inactivation of RB1 or RB2/P130 in uncommitted bone marrow stromal cells (BMSC) facilitates the first steps of adipogenesis. In cultures with silenced RB1 or RB2/P130, we observed an increase of clones with adipogenic potential and a higher percentage of cells accumulating lipid droplets. Nevertheless, the absence of RB1 or RB2/P130 impaired the terminal adipocyte differentiation and gave rise to dysregulated adipose cells, with alteration in lipid uptake and release. For the first time, we evidenced that RB2/P130 plays a role in bone marrow adipogenesis. Our data suggest that while the inactivation of retinoblastoma proteins may delay the onset of last cell division and allow more BMSC to be committed to adipocyte, it did not allow a permanent cell cycle exit, which is a prerequisite for adipocyte terminal maturation.

  3. Geochemistry and geochronology of the Archean and palaeo-Proterozoic formations of southern Cameroon (Ntem group, Congo craton)

    International Nuclear Information System (INIS)

    Rchameni, R.

    1997-01-01

    The aim of this work is to understand the crustal evolution of the NW margin of the Congo craton using structural, petrography, isotopic, geochemical and geochronological studies of the Archean and palaeo-Proterozoic formations of the Ntem group of southern Cameroon. The synthesis of these studies allows to propose a diapir-type gravity model linked with the genesis of granitoids to explain the geodynamical evolution of this part of the craton during the Archean. A convergence model with the collision of the Congo and Sao-Francisco cratons and with crust thickening followed by a relaxation phase is proposed for the palaeo-Proterozoic. (J.S.)

  4. Geochronology of sedimentary and metasedimentary Precambrian rocks of the West African craton

    International Nuclear Information System (INIS)

    Clauer, N.; Jeannette, D.; Trompette, R.

    1982-01-01

    This contribution summarizes current knowledge of the geochronology of the Upper Proterozoic sedimentary rocks covering the West African craton. This was done by using direct dating methods. Correlations between the northern edge of the Tindouf basin and the northern and southern part of the Taoudeni basin, as well as the Volta basin, are proposed. Tectonic, volcanic and thermal activities in connection with the Pan-African orogeny are recorded only around the craton. They induced either sedimentation lacks in Morocco or sedimentation excesses in Hoggar. Unsolved problems such as the precise stratigraphic position of the uppermost Proterozoic tillitic episode and the correlation within the Moroccan Anti-Atlas are also raised. (Auth.)

  5. 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...

  6. Radiation protection at reactors RA and RB

    International Nuclear Information System (INIS)

    Ninkovic, M.

    2003-02-01

    Radiation protection activities at the RA and RB reactors are imposed by the existing legal regulations and international recommendations in this field. This annual report contains five parts which cover the following topics: Radiation safety, dosimetry control and technical radiation protection at reactors RA and RB; Handling of radioactive waste, actions and decontamination; Control of the environment (surroundings of RA and RB reactors) and meteorological measurements; Control of internal contamination and internal exposure; Health control od personnel exposed to radiation. Personnel as well as financial data are part of this report

  7. Dosimetry system of the RB reactor; Dozimetarski sistem reaktora RB

    Energy Technology Data Exchange (ETDEWEB)

    Lolic, B; Vukadin, D [Boris Kidric Institute of nuclear sciences, Vinca, Belgrade (Yugoslavia)

    1962-07-01

    Although RB reactor is operated at very low power levels, safety and dosimetry systems have high importance. This paper shows detailed dosimetry system with fundamental typical components. Estimated radiation doses dependent on reactor power are given at some characteristic points in the rooms nearby reactor.

  8. Seismic Structure of Southern African Cratons

    DEFF Research Database (Denmark)

    Soliman, Mohammad Youssof Ahmad; Artemieva, Irina; Levander, Alan

    2014-01-01

    functions and finite-frequency tomography based on data from the South Africa Seismic Experiment (SASE). Combining the two methods provides high vertical and lateral resolution. The main results obtained are (1) the presence of a highly heterogeneous crustal structure, in terms of thickness, composition (as......Cratons are extremely stable continental crustal areas above thick depleted lithosphere. These regions have remained largely unchanged for more than 2.5 Ga. This study presents a new seismic model of the seismic structure of the crust and lithospheric mantle constrained by seismic receiver...

  9. Seismic imaging of Southern African cratons

    DEFF Research Database (Denmark)

    Soliman, Mohammad Youssof Ahmad

    Cratonic regions are the oldest stable parts of continents that hold most of Earth’s mineral resources. There are several open questions regarding their formation and evolution. In this PhD study, passive source seismic methods have been used to investigate the crustal and lithosphere structures...... of this research was based on Ps- and Sp- receiver functions analysis to determine crustal thickness while finite-frequency traveltime tomography is utilized to model 3D heterogeneity in the upper mantle. Combining the two methods provides high vertical and lateral resolution....

  10. Metamorphism, metasomatism and mineralization at Lagoa Real, Bahia, Brazil

    International Nuclear Information System (INIS)

    Lobato, L.M.

    1985-09-01

    Uranium deposits cumulatively in the 100,000 tonne U 3 O 8 range occur within ductile shear zones transecting Archean basement gneisses of the Sao Francisco Craton, at the Lagoa Real region of south-central Bahia, Brasil. The gneisses, dated at 2.6-3.0Ga, are at amphibolite and granulite facies and overlie to the west, the Proterozoic Espinhaco metasedimentary sequence along a thrust fault. Petrography and mineral chemistry show that in the zones of alteration/mineralization, the original K-feldspar + quartz + albite/oligoclase + hastingsite assemblage, is replaced by albite + aegirine - angite + andradite + hematite assemblages, with or without uraninite. This information along with oxygen isotope, whole rock geochemistry and fluid inclusion studies indicate that the alteration process involves removal of Si, K, Rb, Ba and addition of Na under oxidizing conditions. V, Pb and Sr were introduced along with U via interaction with saline SO 2 - rich, isotopically light fluids under varying water/rock ratios and at temperatures of 500 - 550 0 C. 87 Sr/ 86 Sr systematics suggest that it is unlikely that Sr, and by extension uranium, were introduced by fluids originating from the basement gneisses. Geological constraints and the general alteration pattern are consistent with the release of the mineralizing fluids in response to the overloading of the basement rocks onto the Sedimentary Espinhaco via a thrust mechanism. (Author) [pt

  11. The decay of 93Rb

    International Nuclear Information System (INIS)

    Mitamura, Tohru; Hiromura, Kazuyuki; Aoki, Kazuhiko; Sekioka, Tsuguhisa; Matsui, Hiroshi; Okano, Kotoyuki; Kawase, Yoichi.

    1987-01-01

    The isotope mass separator installed at the Research Reactor Institute of Kyoto University (KUR-ISOL) is used to separate 93 Rb (half-life 5.85 sec.) resulting from fission of 235 U and the levels in its daughter nuclide, 93 Sr, resulting from its decay is examined by means of nuclear spectrometric measurements including Eγ, Iγ, γ-γ coincidence and conversion electron observation. Analysis of gamma-ray spectra obtained identifies a total of 241 gamma-ray peaks including those found only in coincidence spectra. The γ-γ measurements are analyzed in relation to 21 gamma-ray gates selected. For each coincident gamma-ray peak in coincidence of the gate gamma-rays, the ratio of its area in the γ-γ coincidence spectrum to that in the singles spectrum is determined. By examining the ratio, it is possible in most cases to determine whether coincident gamma-rays are directly related with those selected as the gates or indirectly related with them. A decay diagram is constructed based on the relations in energy, intensity and coincidence among these gamma-rays. Results obtained demonstrate a high reliability of the method employed in this study. Conversion electron spectrometry is carried out using an Si(Li) and a Ge(Li) detector in combination with a plastic scintillator for beta-ray detection. Analysis of the results has not yet been completed. Some findings are briefly outlined. (Nogami, K.)

  12. Lattice Dynamics of NaCI, KCI, RbCl and RbF

    Energy Technology Data Exchange (ETDEWEB)

    Raunio, G; Rolandson, S [Physics Dept., Chalmers Univ. of Technology, Goet eborg (Sweden)

    1970-07-01

    In a series of earlier papers experimental results on phonon dispersion relations at 80 K in NaCl, KCl, RbCl and RbF have been reported. We now present calculations on these halides using the extended shell model approach with both ions polarizable and including next-nearest neighbour interactions. The parameters obtained in a least squares fit to the experimental points in the symmetry directions have been used to calculate the phonon frequencies in 512,000 equally spaced points in an octant of the Brillouin zone, -whereby, after sorting these into intervals of width {delta}{omega} = 2 x 10{sup 11} rad/sec , the frequency spectrum was obtained. From these spectra the variation of the Debye temperature with temperature was also calculated. The agreement with results from specific heat measurements for NaCl and KCl is quite satisfactory at low temperatures.

  13. RB Research nuclear reactor, 30 years of operation; Istrazivacki nuclearni reaktor RB, povodom 30 godina rada

    Energy Technology Data Exchange (ETDEWEB)

    Pesic, M; Stefanovic, D [Boris Kidric Institute of nuclear sciences Vinca, Belgrade (Yugoslavia)

    1988-06-15

    Paper describes utilization, modifications and changes of construction and control-safety systems done at the RB reactor during 30 years of operation. Experiments performed at the reactor are summarized, new reactor equipment is described and the future plans are shown. Rad prikazuje eksploataciju reaktora RB tokom 30 godina rada, modifikacije i izmene u konstruktivnim i upravljacko-sigurnosnim sistemima. Sumirani su eksperimenti izvedeni na njemu, prikazana je nova oprema i planovi za buduci rad.

  14. The geological record of base metal sulfides in the cratonic mantle: A microscale 187Os/188Os study of peridotite xenoliths from Somerset Island, Rae Craton (Canada)

    Science.gov (United States)

    Bragagni, A.; Luguet, A.; Fonseca, R. O. C.; Pearson, D. G.; Lorand, J.-P.; Nowell, G. M.; Kjarsgaard, B. A.

    2017-11-01

    We report detailed petrographic investigations along with 187Os/188Os data in Base Metal Sulfide (BMS) on four cratonic mantle xenoliths from Somerset Island (Rae Craton, Canada). The results shed light on the processes affecting the Re-Os systematics and provide time constraints on the formation and evolution of the cratonic lithospheric mantle beneath the Rae craton. When devoid of alteration, BMS grains mainly consist of pentlandite + pyrrhotite ± chalcopyrite. The relatively high BMS modal abundance of the four investigated xenoliths cannot be reconciled with the residual nature of these peridotites, but requires addition of metasomatic BMS. This is especially evident in the two peridotites with the highest bulk Pd/Ir and Pd/Pt. Metasomatic BMS likely formed during melt/fluid percolation in the Sub Continental Lithospheric Mantle (SCLM) as well as during infiltration of the host kimberlite magma, when djerfisherite crystallized around older Fe-Ni-sulfides. On the whole-rock scale, kimberlite metasomatism is visible in a subset of bulk xenoliths, which defines a Re-Os errorchron that dates the host magma emplacement. The 187Os/188Os measured in the twenty analysed BMS grains vary from 0.1084 to >0.17 and it shows no systematic variation depending on the sulfide mineralogical assemblage. The largest range in 187Os/188Os is observed in BMS grains from the two xenoliths with the highest Pd/Ir, Pd/Pt, and sulfide modal abundance. The whole-rock TRD ages of these two samples underestimate the melting age obtained from BMS, demonstrating that bulk Re-Os model ages from peridotites with clear evidence of metasomatism should be treated with caution. The TRD ages determined in BMS grains are clustered around 2.8-2.7, ∼2.2 and ∼1.9 Ga. The 2.8-2.7 Ga TRD ages document the main SCLM building event in the Rae craton, which is likely related to the formation of the local greenstone belts in a continental rift setting. The Paleoproterozoic TRD ages can be explained by

  15. Realization of a gain with electromagnetically induced transparency system using non-degenerate Zeeman sublevels in 87 Rb

    Science.gov (United States)

    Zhou, Minchuan; Zhou, Zifan; Shahriar, Selim M.

    2017-11-01

    Previously, we had proposed an optically-pumped five-level Gain EIT (GEIT) system, which has a transparency dip superimposed on a gain profile and exhibits a negative dispersion suitable for the white-light-cavity signal-recycling (WLC-SR) scheme of the interferometric gravitational wave detector (Zhou et al., 2015). Using this system as the negative dispersion medium (NDM) in the WLC-SR, we get an enhancement in the quantum noise (QN) limited sensitivity-bandwidth product by a factor of ∼ 18. Here, we show how to realize this GEIT system in a realistic platform, using non-degenerate Zeeman sublevels in cold Rb atoms, employing anomalous dispersion at 795 nm. Using the Caves model for a phase insensitive linear amplifier, we show that an enhancement of the sensitivity-bandwidth product by a factor of ∼ 17 is possible for potentially realizable experimental parameters. While the current LIGO apparatus uses light at 1064 nm, a future embodiment thereof may operate at a wavelength that is consistent with the wavelength considered here.

  16. Moho Depth Variations in the Northeastern North China Craton Revealed by Receiver Function Imaging

    Science.gov (United States)

    Zhang, P.; Chen, L.; Yao, H.; Fang, L.

    2016-12-01

    The North China Craton (NCC), one of the oldest cratons in the world, has attracted wide attention in Earth Science for decades because of the unusual Mesozoic destruction of its cratonic lithosphere. Understanding the deep processes and mechanism of this craton destruction demands detailed knowledge about the deep structure of the region. In this study, we used two-year teleseismic receiver function data from the North China Seismic Array consisting of 200 broadband stations deployed in the northeastern NCC to image the Moho undulation of the region. A 2-D wave equation-based poststack depth migration method was employed to construct the structural images along 19 profiles, and a pseudo 3D crustal velocity model of the region based on previous ambient noise tomography and receiver function study was adopted in the migration. We considered both the Ps and PpPs phases, but in some cases we also conducted PpSs+PsPs migration using different back azimuth ranges of the data, and calculated the travel times of all the considered phases to constrain the Moho depths. By combining the structure images along the 19 profiles, we got a high-resolution Moho depth map beneath the northeastern NCC. Our results broadly consist with the results of previous active source studies [http://www.craton.cn/data], and show a good correlation of the Moho depths with geological and tectonic features. Generally, the Moho depths are distinctly different on the opposite sides of the North-South Gravity Lineament. The Moho in the west are deeper than 40 km and shows a rapid uplift from 40 km to 30 km beneath the Taihang Mountain Range in the middle. To the east in the Bohai Bay Basin, the Moho further shallows to 30-26 km depth and undulates by 3 km, coinciding well with the depressions and uplifts inside the basin. The Moho depth beneath the Yin-Yan Mountains in the north gradually decreases from 42 km in the west to 25 km in the east, varying much smoother than that to the south.

  17. Considerations on the age of the Bambui Group (MG, Brazil) based on isotopic analyses of Sr and Pb

    International Nuclear Information System (INIS)

    Couto, J.G.P.; Cordani, U.G.; Kawashita, K.

    1981-01-01

    Based on radiometric ages, the Bambui Group deposition time is related to the end of the Precambrian. However, the ages determined and released through scientific magazines are mot in agreement (600-1350 m.y.) and many doubts about the geochrological picture of this important lithostratigraphic unit remained for a long time. As a result of the work developed by Metamig, CPGeo (IG-USP) and IPEN (SP), Rb/Sr and Pb/Pb isotopic determinations were done on 31 rocks samples and 17 galenas collected from the Bambui Basin distributed in Minas Gerais State. The Rb/Sr ages of 590 m.y. for Pirapora Formation, 620 m.y. for Tres Marias Formation, and 640 m.y. for the Paraopeba Formation situated in the stable area are linked to sedimentation processes. In the Paracatu region the age of 680 m.y. found for the Paraopeba Formation is related to metamorphic events. The lead isotopic ratios from the galenas suggest an isotopic evolution in two stages. The first ended with the lead separation from the mantle and its incorporation to the crust during events of the Transamazonic Cycle. The second ended when the lead were incorporated to the galenas and seems to be related to one or more events of the Brazilian Cycle. (Author) [pt

  18. RB research nuclear reactor, Annual report for 1981; Istrazivacki nuklearni reaktor RB, Izvestaj o radu u 1981. godini

    Energy Technology Data Exchange (ETDEWEB)

    Markovic, H; Sotic, O; Pesic, M; Vranic, S; Zivkovic, B; Bogdanovic, M; Petronijevic, M [Boris Kidric Institute of Nuclear Sciences Vinca, Beograd (Yugoslavia)

    1981-07-01

    The annual report for 1981 includes the following: utilization of the RB reactor; accident and incidents analysis; description of the reactor equipment status; dosimetry and radiation protection; RB reactor staff; financial data. Seven Annexes to this report are concerned with: maintenance of the reactor components and equipment, including nuclear fuel, heavy water, reactor vessel, heavy water coolant circuit, experimental platforms, absorption rods; maintenance of the electric power supply system, neutron source equipment, crane; control and maintenance of ventilation and heating systems, gas and comprised gas systems, fire protection system; plan for renewal of the reactor components; contents of the RB reactor safety report; reactor staff; review of measured radiation doses; experimental methods; training of the staff; and financial report.

  19. Magnetotelluric investigations of the lithosphere beneath the central Rae craton, mainland Nunavut, Canada

    Science.gov (United States)

    Spratt, Jessica E.; Skulski, Thomas; Craven, James A.; Jones, Alan G.; Snyder, David B.; Kiyan, Duygu

    2014-03-01

    New magnetotelluric soundings at 64 locations throughout the central Rae craton on mainland Nunavut constrain 2-D resistivity models of the crust and lithospheric mantle beneath three regional transects. Responses determined from colocated broadband and long-period magnetotelluric recording instruments enabled resistivity imaging to depths of > 300 km. Strike analysis and distortion decomposition on all data reveal a regional trend of 45-53°, but locally the geoelectric strike angle varies laterally and with depth. The 2-D models reveal a resistive upper crust to depths of 15-35 km that is underlain by a conductive layer that appears to be discontinuous at or near major mapped geological boundaries. Surface projections of the conductive layer coincide with areas of high grade, Archean metasedimentary rocks. Tectonic burial of these rocks and thickening of the crust occurred during the Paleoproterozoic Arrowsmith (2.3 Ga) and Trans-Hudson orogenies (1.85 Ga). Overall, the uppermost mantle of the Rae craton shows resistivity values that range from 3000 Ω m in the northeast (beneath Baffin Island and the Melville Peninsula) to 10,000 Ω m beneath the central Rae craton, to >50,000 Ω m in the south near the Hearne Domain. Near-vertical zones of reduced resistivity are identified within the uppermost mantle lithosphere that may be related to areas affected by mantle melt or metasomatism associated with emplacement of Hudsonian granites. A regional decrease in resistivities to values of 500 Ω m at depths of 180-220 km, increasing to 300 km near the southern margin of the Rae craton, is interpreted as the lithosphere-asthenosphere boundary.

  20. Correlation of proterozoic sediments of Western and Central Africa and South America based upon radiochronological and paleontological data

    International Nuclear Information System (INIS)

    Bonhomme, M.G.

    1982-01-01

    Nearly 70 new Rb-Sr isochron ages and many K-Ar conventional ages have been determined between 1975 and 1980 on Proterozoic sedimentary or metasedimentary sequences in western and Central Africa and South America. Some stratigraphic results have been established: (1) five formations have been dated of the Lower Proterozoic; (2) a long sedimentation gap occurs, mainly in western Africa and in some regions of Central Africa and South America between nearly 1600 and 1100 Ma; (3) the upper Riphean assemblages of stromatolites have been dated and compared to those of the Eurasian craton; (4) two main glacial events have been dated, the first one placed at ca. 950 Ma, the second during the Vendian, at ca. 650-620 Ma; (5) it can be stated that, when applied to Precambrian sequences, all stratigraphic methods must be used together. (Auth.)

  1. Geochronology Intermediary Laboratory implantation at the Rio Grande do Norte Federal University: the dating of the Serrinha Granitoid (RN) and the correlate Brasiliana extensional deformation; Implantacao do Laboratorio Intermediario de Geocronologia na UFRN: a datacao do granitoide de Serrinha (RN) e da deformacao extensional brasiliana correlata

    Energy Technology Data Exchange (ETDEWEB)

    Macedo, Maria Helena F.; Sa, Emanuel F. Jardim de; Souza, Zorano S. [Pernambuco Univ., Recife, PE (Brazil). Nucleo de Pesquisa em Geodinamica e Geofisica; Mendes, Franklin S. [Pernambuco Univ., Recife, PE (Brazil). Curso de Quimica; Ramalho, Karlos A.C. [Pernambuco Univ., Recife, PE (Brazil). Curso de Geologia

    1997-12-31

    The article describes the activities developed by the Geochronology Intermediary Laboratory at the Federal University of the Rio Grande do Norte, a Brazilian university, where there were the preoccupation of establishing strategies for a geochronological development. It relates the Rubidium-Strontium (Rb/Sr) and Samarium-Neodymium (Sm/Nd) methods, describing the analysis realized in these methodologies. Afterward, it presents the geological and petrographic situation of the Granitoide de Serrinha, located at Rio Grande do Norte State, Brazil and its geochronological data 8 refs., 2 figs.

  2. 87Rb-NMR in Rb2ZnCl4 below the incommensurable phase

    International Nuclear Information System (INIS)

    Grande, S.; Moskvich, Yu.N.; Aleksandrova, I.P.

    1983-01-01

    In Rb 2 ZnCl 4 crystals the curly polar phase, which changes into the incommensurable phase below 192 K, has been investigated by pulsed NMR. The angular correlations of the second-order quadrupole shifts have been measured and the corresponding tensors of the electric field gradient have been calculated. The six Rb layers change differently in magnitude and orientation compared to the paraelectric phase. The temperature dependences within the C-phase are also different. The spin-lattice relaxation times have been measured and discussed for each layer in the C-phase. All relaxation times show an anomaly at a further phase transition occurring at 72 K connected with an increase of the number of spectral lines

  3. Small-scale convection at a continental back-arc to craton transition: Application to the southern Canadian Cordillera

    Science.gov (United States)

    Hardebol, N. J.; Pysklywec, R. N.; Stephenson, R.

    2012-01-01

    A step in the depth of the lithosphere base, associated with lateral variations in the upper mantle temperature structure, can trigger mantle flow that is referred to as edge-driven convection. This paper aims at outlining the implications of such edge-driven flow at a lateral temperature transition from a hot and thin to a cold and thick lithosphere of a continental back-arc. This configuration finds application in the southern Canadian Cordillera, where a hot and thin back-arc is adjacent to the cold and thick North American Craton. A series of geodynamical models tested the thermodynamical behavior of the lithosphere and upper mantle induced by a step in lithosphere thickness. The mantle flow patterns, thickness and heat flow evolution of the lithosphere, and surface topography are examined. We find that the lateral temperature transition shifts cratonward due to the vigorous edge-driven mantle flow that erodes the craton edge, unless the craton has a distinct high viscosity mantle lithosphere. The mantle lithosphere viscosity structure determines the impact of edge-driven flow on crustal deformation and surface heat flow; a dry olivine rheology for the craton prevents the edge from migrating and supports a persistent surface heat flow contrast. These phenomena are well illustrated at the transition from the hot Canadian Cordillera to craton that is supported by a rheological change and that coincides with a lateral change in surface heat flow. Fast seismic wave velocities observed in the upper mantle cratonward of the step can be explained as downwellings induced by the edge-driven flow.

  4. Neoproterozoic stratigraphic framework of the Tarim Craton in NW China: Implications for rift evolution

    Science.gov (United States)

    Wu, Lin; Guan, Shuwei; Zhang, Shuichang; Yang, Haijun; Jin, Jiuqiang; Zhang, Xiaodan; Zhang, Chunyu

    2018-06-01

    The Tarim Craton is overlain by thick Neoproterozoic sedimentary successions in rift tectonic setting. This study examines the latest outcrop, seismic, and drilling core data with the objective of investigating the regional stratigraphy to deeply recognize the evolution of rifting in the craton. Cryogenian to Lower Ediacaran successions are mainly composed of clastic rocks with thicknesses of 2000-3000 m, and the Upper Ediacaran successions are composed of carbonate rocks with thicknesses of 500-800 m. The rift basins and stratigraphic zones are divided into northern and southern parts by a central paleo-uplift. The northern rift basin extends through the northern Tarim Craton in an E-W direction with two depocenters (Aksu and Kuruktag). The southern rift basin is oriented NE-SW. There are three or four phases of tillites in the northern zone, while there are two in the southern zone. Given the north-south difference of the stratigraphic framework, the northern rift basin initiated at ca. 740 Ma and the southern rift basin initiated at ca. 780 Ma. During the Cryogenian and Ediacaran, the northern and southern rift basins were separated by the central paleo-uplift, finally connecting with each other in the early Cambrian. Tectonic deformation in the Late Ediacaran led to the formation of a parallel unconformity in the rift basins and an angular unconformity in the central paleo-uplift. The Neoproterozoic rift basins continued to affect the distribution of Lower Cambrian hydrocarbon source rocks. The north-south distribution and evolution of the rift basins in the Tarim Craton have implications for reconstructions of the Rodinia supercontinent.

  5. Elemental concentration analysis in PCa, BPH and normal prostate tissues using SR-TXRF

    International Nuclear Information System (INIS)

    Leitao, Roberta G.; Anjos, Marcelino J.; Canellas, Catarine G.L.; Lopes, Ricardo T.

    2009-01-01

    Prostate cancer (PCa) is one of the main causes of illness and death all over the world. In Brazil, prostate cancer currently represents the second most prevalent malignant neoplasia in men, representing 21% of all cancer cases. Benign Prostate Hyperplasia (BPH) is an illness prevailing in men above the age of 50, close to 90% after the age of 80. The prostate presents a high zinc concentration, about 10-fold higher than any other body tissue. In this work, samples of human prostate tissues with cancer (PCa), BPH and normal tissue were analyzed utilizing the total reflection X-ray fluorescence spectroscopy using synchrotron radiation technique (SRTXRF) to investigate the differences in the elemental concentrations in these tissues. SR-TXRF analyses were performed at the X-Ray fluorescence beamline at Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, Sao Paulo. It was possible to determine the concentrations of the following elements: P, S, K, Ca, Fe, Cu, Zn, Br and Rb. By using Mann-Whitney U test it was observed that almost all elements presented concentrations with significant differences α = 0.05) between the groups studied. The elements and groups were: S, K, Ca, Fe, Zn, Br and Rb (PCa X Normal); S, Fe, Zn and Br (PCa X BPH); K, Ca, Fe, Zn, Br and Rb (BPH X Normal). (author)

  6. Pb, Sr and Nd isotope geological characteristics and its evolution of Jianchaling rock

    International Nuclear Information System (INIS)

    Pang Chunyong; Chen Minyang; Xu Wenxin

    2003-01-01

    It has been a long time debatable subject on the raw material source and its genesis of Jianchaling ultrabasic rock, because the original rock phases, the original mineral compositions, texture and structure, even part of the chemical components of the rocks had been changed completely after many periods and phases of metamorphism. According to the content of Pb, Rb, Sr, Nd elements and their Pb, Sr, Nd isotope compositions of the rocks, together with the isotope geological age of late magmatic activities, the authors analyze the evolution of Pb, Sr, Nd isotope compositions, The inferred initiate Nd isotope ratio of ultrabasic rocks is 0.510233, lower than that of meteorite unity at a corresponding period, its ε Nd(T)>O; The initiate Sr ratios inferred by the isotope geological age ranges from 0.702735 to 0.719028; Projecting the lead isotope compositions on the Pb tectonic evolution model, the result indicates that the raw material of Jianchaling ultrabasic rock coming from the deplete upper mantle. The ultrabasic magma which enrich of Mg, Ni and less S intruded the crust and formed the Jianchaling ultrabasic rock at late Proterozoic era (927 Ma±). The forming time of serpentinite is mostly equal to the granitoid intruding time, showing the intrusion o flate acidic magma caused a large scale alteration of the ultrabasic rocks and formed the meta-ultrabasic phase rock observed today. (authors)

  7. 76 FR 24793 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-524 Series and RB211 Trent 500, 700, and 800...

    Science.gov (United States)

    2011-05-03

    ... Airworthiness Directives; Rolls-Royce plc (RR) RB211-524 Series and RB211 Trent 500, 700, and 800 Series... the AD. Costs of Compliance Based on the service information, we estimate that this AD would affect...

  8. Is Nubia plate rigid? A geodetic study of the relative motion of different cratonic areas within Africa.

    Science.gov (United States)

    Njoroge, M. W.; Malservisi, R.; Hugentobler, U.; Mokhtari, M.; Voytenko, D.

    2014-12-01

    Plate rigidity is one of the main paradigms of plate tectonics and a fundamental assumption in the definition of a global reference frame as ITRF. Although still far for optimal, the increased GPS instrumentation of the African region can allow us to understand how rigid one of the major plate can be. The presence of diffused band of seismicity, the Cameroon volcanic line, Pan African Kalahari orogenic belt and East Africa Rift suggest the possibility of relative motion among the different regions within the Nubia. The study focuses on the rigidity of Nubia plate. We divide the plate into three regions: Western (West Africa craton plus Nigeria), Central (approximately the region of the Congo craton) and Southern (Kalahari craton plus South Africa) and we utilize Euler Vector formulation to study internal rigidity and eventual relative motion. Developing five different reference frames with different combinations of the 3 regions, we try to understand the presence of the relative motion between the 3 cratons thus the stability of the Nubia plate as a whole. All available GPS stations from the regions are used separately or combined in creation of the reference frames. We utilize continuous stations with at least 2.5 years of data between 1994 and 2014. Given the small relative velocity, it is important to eliminate eventual biases in the analysis and to have a good estimation in the uncertainties of the observed velocities. For this reason we perform our analysis using both Bernese and Gipsy-oasis codes to generate time series for each station. Velocities and relative uncertainties are analyzed using the Allan variance of rate technique, taking in account for colored noise. An analysis of the color of the noise as function of latitude and climatic region is also performed to each time series. Preliminary results indicate a slight counter clockwise motion of West Africa craton with respect to South Africa Kalahari, and South Africa Kalahari-Congo Cratons. In addition

  9. New neutron and gamma dosimetry equipment at the RB reactor; Nova merna neutronska i gama dozimetrijska oprema na reaktoru RB

    Energy Technology Data Exchange (ETDEWEB)

    Pesic, M; Stefanovic, D; Jevremovic, M; Petronijevic, M; Vranic, S; Ilic, I [Boris Kidric Institute of Nuclear Sciences Vinca, Beograd (Yugoslavia)

    1992-07-15

    In the frame of bilateral cooperation between Germany and Yugoslavia, complete control, safety and dosimetry equipment of the shut-down SNEAK reactor was donated to Vinca Institute and transported to be installed at the RB reactor. This report contains detailed description of instrumentation components including detectors, electronic components and electronic circuits. Experimental data which verified correct functioning of the installed devices are part of this document. The objective of the RB reactor staff is to achieve new safety and dosimetry system in order to improve the reliability and availability of the RB reactor for future experiments.

  10. Precision study of the $\\beta$-decay of $^{74}$Rb

    CERN Multimedia

    Van Duppen, P L E; Lunney, D

    2002-01-01

    We are proposing a high-resolution study of the $\\beta$-decay of $^{74}$Rb in order to extrapolate our precision knowledge of the superallowed $\\beta$-decays from the sd and fp shells towards the medium-heavy Z=N nuclei. The primary goal is to provide new data for testing the CVC hypothesis and the unitarity condition of the CKM matrix of the Standard Model. The presented programme would involve the careful measurements of the decay properties of $^{74}$Rb including the branching ratios to the excited states as well as the precise determination of the decay energy of $^{74}$Rb. The experimental methods readily available at ISOLDE include high-transmission conversion electron spectroscopy, $\\gamma$-ray spectroscopy as well as the measurements of the masses of $^{74}$Rb and $^{74}$Kr using two complementary techniques, ISOLTRAP and MISTRAL. The experiment would rely on a high-quality $^{74}$Rb beam available at ISOLDE with adequate intensity.

  11. Hydrothermal synthesis and polymorphism of RbPr(MoO4)2

    International Nuclear Information System (INIS)

    Protasova, V.I.; Kharchenko, L.Yu.; Klevtsov, P.V.

    1977-01-01

    Hydrothermal method has been successfully used to obtain crystals of rubidium-rare-earth molibdates of RbLn(MoO 4 ) 2 composition (Ln is a rare earth element). In Rb 2 MoO 4 solutions at 575-600degC the RbPr(MoO 4 ) 2 crystals were obtained in a modification new for Rb-Ln-molibdates, i.e. isostructural to triclinic α-KEu(MoO 4 ) 2 , and in a structural modification of laminated rhombic KY(MoO 4 ) 2 type. Polymorphism of RbPr(MoO 4 ) 2 has been studied, four crystalline modifications found and their complex interchanges investigated

  12. The RB/E2F pathway and regulation of RNA processing

    Energy Technology Data Exchange (ETDEWEB)

    Ahlander, Joseph [Department of Molecular and Cellular Biology, 1007 East Lowell Street, University of Arizona, Tucson, AZ 85721 (United States); Bosco, Giovanni, E-mail: gbosco@email.arizona.edu [Department of Molecular and Cellular Biology, 1007 East Lowell Street, University of Arizona, Tucson, AZ 85721 (United States)

    2009-07-03

    The retinoblastoma tumor suppressor protein (RB) is inactivated in a majority of cancers. RB restricts cell proliferation by inhibiting the E2F family of transcription factors. The current model for RB/E2F function describes its role in regulating transcription at gene promoters. Whether the RB or E2F proteins might play a role in gene expression beyond transcription initiation is not well known. This review describes evidence that points to a novel role for the RB/E2F network in the regulation of RNA processing, and we propose a model as a framework for future research. The elucidation of a novel role of RB in RNA processing will have a profound impact on our understanding of the role of this tumor suppressor family in cell and developmental biology.

  13. Photoemission and muon spin relaxation spectroscopy of the iron-based Rb0.77Fe1.61Se2 superconductor: Crucial role of the cigar-shaped Fermi surface

    Science.gov (United States)

    Maletz, J.; Zabolotnyy, V. B.; Evtushinsky, D. V.; Yaresko, A. N.; Kordyuk, A. A.; Shermadini, Z.; Luetkens, H.; Sedlak, K.; Khasanov, R.; Amato, A.; Krzton-Maziopa, A.; Conder, K.; Pomjakushina, E.; Klauss, H.-H.; Rienks, E. D. L.; Büchner, B.; Borisenko, S. V.

    2013-10-01

    In this study, we investigate the electronic and magnetic properties of Rb0.77Fe1.61Se2 (Tc = 32.6 K) in normal and superconducting states by means of photoemission and μSR spectroscopies as well as band-structure calculations. We demonstrate that the unusual behavior of these materials is the result of separation into metallic (˜12%) and insulating (˜88%) phases. Only the former becomes superconducting and has a usual electronic structure of electron-doped FeSe slabs. Our results thus imply that the antiferromagnetic insulating phase is just a by-product of Rb intercalation and its magnetic properties have no direct relation to the superconductivity. Instead, we find that also in this class of iron-based compounds, the key ingredient for superconductivity is a certain proximity of a Van Hove singularity to the Fermi level.

  14. Ouabain-sensitive Rb+ uptake in mouse eggs and preimplantation conceptuses

    International Nuclear Information System (INIS)

    Van Winkle, L.J.; Campione, A.L.

    1991-01-01

    The results of histochemical and immunocytochemical studies have been used elsewhere to support the hypothesis that Na+/K(+)-ATPase expression is initiated or increases dramatically in preimplantation mouse conceptuses just before they begin to cavitate. Moreover, localization of the enzyme in the inner membrane of the mural trophoblast is thought to be involved directly in formation and maintenance of the blastocyst cavity. Presumably, Na+/K(+)-ATPase extrudes the cation, Na+, and therefore water into the cavity. The cation transporting activity of the enzyme can be determined by measuring ouabain-sensitive Rb+ uptake by cells. Therefore, we measured Rb+ uptake in mouse eggs and preimplantation conceptuses at various stages of development. 86Rb+ uptake by conceptuses increased linearly with time for at least 60 min in medium containing 0.7 mM total Rb+ plus K+ in the absence or presence of 1.0 mM ouabain, and ouabain inhibited more than 70% of 86Rb+ uptake. The ouabain concentration at 1/2 of maximum inhibition of the ouabain-sensitive component of 86Rb+ uptake was about 10-20 microM in eggs and conceptuses at all stages of preimplantation development. Moreover, ouabain-sensitive Rb+ uptake had a twofold higher Vmax value in blastocysts than in eggs or conceptuses at earlier stages of development (i.e., approximately 173 vs 70-100 fmole.conceptus-1.min-1), although the total cell surface area also was probably about two times greater in blastocysts than in eggs or other conceptuses. Ouabain-sensitive Rb+ transport in eggs and conceptuses may have occurred via a single ouabain-sensitive Rb+ transporter with a Hill coefficient of 1.5-1.8 (Hill plots). When it was assumed that the Hill coefficient had a value of 2.0, however, eggs and conceptuses appeared to contain at least two forms of Na+/K(+)-ATPase activity

  15. Nuclear RB research reactor. Thirty years of anniversary; Istrazhivacki nuklearni reaktor RB. Povodom 30 godina rada

    Energy Technology Data Exchange (ETDEWEB)

    Pesic, M; Stefanovic, D [Institut za Nuklearne Nauke Boris Kidric, Belgrade (Yugoslavia)

    1988-07-01

    Nuclear research reactor RB in the Nuclear Engineering Laboratory - NET at the 'Boris Kidric' Institute of Nuclear Sciences in Vinca is the first reactor system built in Yugoslavia in 1958. This year is the thirtieth anniversary of the RB reactor operation, which has survived a series of modifications trying to follow a contemporary nuclear research directions. This report describes its basic technical characteristics and experimental possibilities. Especially, the modifications in the last 25 years are underlined, the experiences gained, and new plans for the future are presented. (author)

  16. 207Pb-206Pb zircon ages of eastern and western Dharwar craton, southern India : Evidence for contemporaneous Archaean crust

    Science.gov (United States)

    Maibam, B.; Goswami, J. N.; Srinivasan, R.

    2009-04-01

    Dharwar craton is one of the major Archaean crustal blocks in the Indian subcontinent. The craton is comprised of two blocks, western and eastern. The western domain is underlain by orthogneisses and granodiorites (ca. 2.9-3.3 Ga) collectively termed as Peninsular Gneiss [e.g., 1] interspersed with older tracts of metasedimentary and metamorphosed igneous suites (Sargur Group and Dharwar Group; [2]). The eastern part of the craton is dominated by Late Archaean (2.50-2.75 Ga) granitoids and their gneissic equivalents. They are interspersed with schist belts (also of Sargur Group and Dharwar Group), which are lithologically similar to the Dharwar Supergroup in the western block, but are in different metamorphic dress. Here we report 207Pb-206Pb age of zircons separated from the metasedimentary and gneissic samples from the two blocks to constrain the evolution of the Dharwar craton during the early Archaean. Detrital zircons of the metasedimentary rocks from both the blocks show a wide range of overlapping ages between ~2.9 to >3.5 Ga. Zircon ages of the orthogneisses from the two blocks showed that most of the analysed grains of the eastern Dharwar block are found to be of the age as old as the western Dharwar gneisses. Imprints of younger events could be discerned from the presence of overgrowths in zircons from the studied samples throughout the craton. Our data suggest that crust forming cycles in the two blocks of the Dharwar craton occurred contemporaneously during the Archaean. References [1] Beckinsale, R.D., Drury, S.A., Holt, R.W. (1980) Nature 283, 469-470. [2] Swami Nath J., Ramakrishnan M., Viswanatha M.N. (1976) Rec. Geol. Surv. Ind., 107, 149-175.

  17. Thermodynamic studies of (RbF + RbCl + H2O) and (CsF + CsCl + H2O) ternary systems from potentiometric measurements at T = 298.2 K

    International Nuclear Information System (INIS)

    Huang, Xiaoting; Li, Shu’ni; Zhai, Quanguo; Jiang, Yucheng; Hu, Mancheng

    2016-01-01

    Graphical abstract: Thermodynamic properties, such as mean activity coefficients, osmotic coefficients and excess Gibbs free energies, of the RbF + RbCl + H 2 O and CsF + CsCl + H 2 O ternary systems were determined from potentiometric measurement at 298.2 K. The Pitzer model and the Harned rule were used to fit the experimental data. - Highlights: • Thermodynamic properties of RbF + RbCl + H 2 O and CsF + CsCl + H 2 O ternary systems were determined. • The Pitzer model and the Harned rule were used to correlate the experimental data. • The mean activity coefficients, osmotic coefficients, and the excess Gibbs free energy were also obtained. - Abstract: Thermodynamic properties of (RbF + RbCl + H 2 O) and (CsF + CsCl + H 2 O) systems were determined by the potentiometric method for different ionic strength fractions y B of RbCl/CsCl at 298.2 K. The Pitzer model and the Harned rule were used to fit the experimental values. The Pitzer mixing parameters and the Harned coefficients were evaluated. In addition, the mean ionic activity coefficients of RbF/CsF and RbCl/CsCl, the osmotic coefficients, and the excess Gibbs energies of the systems studied were calculated.

  18. Calibration of RB reactor power

    International Nuclear Information System (INIS)

    Sotic, O.; Markovic, H.; Ninkovic, M.; Strugar, P.; Dimitrijevic, Z.; Takac, S.; Stefanovic, D.; Kocic, A.; Vranic, S.

    1976-09-01

    The first and only calibration of RB reactor power was done in 1962, and the obtained calibration ratio was used irrespective of the lattice pitch and core configuration. Since the RB reactor is being prepared for operation at higher power levels it was indispensable to reexamine the calibration ratio, estimate its dependence on the lattice pitch, critical level of heavy water and thickness of the side reflector. It was necessary to verify the reliability of control and dosimetry instruments, and establish neutron and gamma dose dependence on reactor power. Two series of experiments were done in June 1976. First series was devoted to tests of control and dosimetry instrumentation and measurements of radiation in the RB reactor building dependent on reactor power. Second series covered measurement of thermal and epithermal neuron fluxes in the reactor core and calculation of reactor power. Four different reactor cores were chosen for these experiments. Reactor pitches were 8, 8√2, and 16 cm with 40, 52 and 82 fuel channels containing 2% enriched fuel. Obtained results and analysis of these results are presented in this document with conclusions related to reactor safe operation

  19. RB research nuclear reactor, Annual report for 1982; Istrazivacki nuklearni reaktor RB, Izvestaj o radu u 1981. godini

    Energy Technology Data Exchange (ETDEWEB)

    Markovic, H; Pesic, M; Vranic, S; Petronijevic, M; Zivkovic, B [Boris Kidric Institute of Nuclear Sciences Vinca, Beograd (Yugoslavia)

    1982-12-15

    This report includes data concerned with reactor operation and utilization, status of reactor components and equipment, refurbishment of the equipment, dosimetry and radiation protection, reactor staff, financing. It includes 7 Annexes as follows: Maintenance of reactor equipment in 1982; contents of the RB reactor safety report; review of radiation doses in the reactor building and exposure doses for the reactor staff; utilization of the RB reactor in 1982; and financial data.

  20. Human biodistribution and radiation dosimetry of 82Rb.

    Science.gov (United States)

    Senthamizhchelvan, Srinivasan; Bravo, Paco E; Esaias, Caroline; Lodge, Martin A; Merrill, Jennifer; Hobbs, Robert F; Sgouros, George; Bengel, Frank M

    2010-10-01

    Prior estimates of radiation-absorbed doses from (82)Rb, a frequently used PET perfusion tracer, yielded discrepant results. We reevaluated (82)Rb dosimetry using human in vivo biokinetic measurements. Ten healthy volunteers underwent dynamic PET/CT (6 contiguous table positions, each with separate (82)Rb infusion). Source organ volumes of interest were delineated on the CT images and transferred to the PET images to obtain time-integrated activity coefficients. Radiation doses were estimated using OLINDA/EXM 1.0. The highest mean absorbed organ doses (μGy/MBq) were observed for the kidneys (5.81), heart wall (3.86), and lungs (2.96). Mean effective doses were 1.11 ± 0.22 and 1.26 ± 0.20 μSv/MBq using the tissue-weighting factors of the International Commission on Radiological Protection (ICRP), publications 60 and 103, respectively. Our current (82)Rb dosimetry suggests reasonably low radiation exposure. On the basis of this study, a clinical (82)Rb injection of 2 × 1,480 MBq (80 mCi) would result in a mean effective dose of 3.7 mSv using the weighting factors of the ICRP 103-only slightly above the average annual natural background exposure in the United States (3.1 mSv).

  1. 86Rb Distribution in the Lung of the Rabbit with Pneumothorax

    International Nuclear Information System (INIS)

    Huh, Kap To

    1972-01-01

    86 Rb uptake of some organs and tissues, eg. both lungs, both renal cortices. small intestine, liver and skeletal muscle were studied in the control and the rabbit subjected to pneumothorax. 86 Rb in the form of chloride mixed with physiological saline was intravenously injected. The doses were 100 μc for a rabbit. The rabbits were sacrificed at intervals of 10, 20, 40, and 60 seconds after the injection of 86 Rb, by the injection of saturated KCI solution. After scarification, the organ and tissue sample were quickly removed. 86 Rb uptake in gm of the organs and tissues were measured. On the basis of uptake value, administered doses and body weight, % dose/gm tissues per 200 gm body weight was calculated. Followings were the results: 1. Pneumothorax resulted in a marked elevation in 86 Rb uptake value of collapsed lung and returned to normal level lately. 2. Contralateral lung of pneumothorax also showed marked elevation in 86 Rb uptake value and recovered to normal level. 3. Initial 86 Rb uptake value of liver, small intestine of the rabbit with pneumothorax showed some elevation as compared to control, but that of late stage were similar with control. 4. Local blood flow determination by means of 86 Rb uptake were inadequate in the collapsed lung of pneumothorax. 5. It was suggested that the mechanism for the initial elevation of 86 Rb uptake value in each organs and tissue were different from each other.

  2. RB1 mutation spectrum in a comprehensive nationwide cohort of retinoblastoma patients

    NARCIS (Netherlands)

    Dommering, Charlotte J.; Mol, Berber M.; Moll, Annette C.; Burton, Margaret; Cloos, Jacqueline; Dorsman, Josephine C.; Meijers-Heijboer, Hanne; van der Hout, Annemarie H.

    Background Retinoblastoma (Rb) is a childhood cancer of the retina, commonly initiated by biallelic inactivation of the RB1 gene. Knowledge of the presence of a heritable RB1 mutation can help in risk management and reproductive decision making. We report here on RB1 mutation scanning in a unique

  3. Fast neutron fields at the RB reactor; Polja brzih neutron na reacktoru RB

    Energy Technology Data Exchange (ETDEWEB)

    Strugar, P; Pesic, M; Dasic, N [Institut za nuklearne nauke Boris Kidric Vinca, Beograd (Yugoslavia)

    1984-07-01

    Paper deals with the reasons and methods of realization of the RB neutron converters. The methods and results of neutron flux intensities and spectra measurements as well as gamma dose determination are presented. (author)

  4. An isotopic perspective on growth and differentiation of Proterozoic orogenic crust: From subduction magmatism to cratonization

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Simon P.; Korhonen, Fawna J.; Kirkland, Christopher L.; Cliff, John B.; Belousova, Elena A.; Sheppard, Stephen

    2017-01-01

    The in situ chemical differentiation of continental crust ultimately leads to the long-term stability of the continents. This process, more commonly known as ‘cratonization’, is driven by deep crustal melting with the transfer of those melts to shallower regions resulting in a strongly chemically stratified crust, with a refractory, dehydrated lower portion overlain by a complementary enriched upper portion. Since the lower to mid portions of continental crust are rarely exposed, investigation of the cratonization process must be through indirect methods. In this study we use in situ Hf and O isotope compositions of both magmatic and inherited zircons from several felsic magmatic suites in the Capricorn Orogen of Western Australia to highlight the differentiation history (i.e. cratonization) of this portion of late Archean to Proterozoic orogenic crust. The Capricorn Orogen shows a distinct tectonomagmatic history that evolves from an active continental margin through to intracratonic reworking, ultimately leading to thermally stable crust that responds similarly to the bounding Archean Pilbara and Yilgarn Cratons.

  5. Synthesis and Characterization of the Rubidium Thiophosphate Rb 6 (PS 5 )(P 2 S 10 ) and the Rubidium Silver Thiophosphates Rb 2 AgPS 4 , RbAg 5 (PS 4 ) 2 and Rb 3 Ag 9 (PS 4 ) 4

    KAUST Repository

    Alahmary, Fatimah S.

    2016-02-18

    The metal thiophosphates Rb2AgPS4 (2), RbAg5(PS4)2 (3), and Rb3Ag9(PS4)4 (4) were synthesized by stoichiometric reactions, whereas Rb6(PS5)(P2S10) (1) was prepared with excess amount of sulfur. The compounds crystallize as follows: 1 monoclinic, P21/c (no. 14), a = 17.0123(7) Å, b = 6.9102(2) Å, c = 23.179(1) Å, β = 94.399(4)°; 2 triclinic, P ¯ (no. 2), a = 6.600(1) Å, b = 6.856(1) Å, c = 10.943(3) Å, α = 95.150(2)°, β = 107.338(2)°, γ = 111.383(2)°; 3 orthorhombic, Pbca (no. 61), a = 12.607(1) Å, b = 12.612(1) Å, c = 17.759(2) Å; 4 orthorhombic, Pbcm (no. 57), a = 6.3481(2) Å, b = 12.5782(4) Å, c = 35.975(1) Å. The crystal structures contain discrete units, chains, and 3D polyanionic frameworks composed of PS4 tetrahedral units arranged and connected in different manner. Compounds 1-3 melt congruently, whereas incongruent melting behavior was observed for compound 4. 1-4 are semiconductors with bandgaps between 2.3 and 2.6 eV and thermally stable up to 450 °C in an inert atmosphere. Copyright © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Optical pumping in a microfabricated Rb vapor cell using a microfabricated Rb discharge light source

    International Nuclear Information System (INIS)

    Venkatraman, V.; Kang, S.; Affolderbach, C.; Mileti, G.; Shea, H.

    2014-01-01

    Miniature ( 3 ) vapor-cell based devices using optical pumping of alkali atoms, such as atomic clocks and magnetometers, today mostly employ vertical-cavity surface-emitting lasers as pump light sources. Here, we report on the demonstration of optical pumping in a microfabricated alkali vapor resonance cell using (1) a microfabricated Rb discharge lamp light source, as well as (2) a conventional glass-blown Rb discharge lamp. The microfabricated Rb lamp cell is a dielectric barrier discharge (DBD) light source, having the same inner cell volume of around 40 mm 3 as that of the resonance cell, both filled with suitable buffer gases. A miniature (∼2 cm 3 volume) test setup based on the M z magnetometer interrogation technique was used for observation of optical-radiofrequency double-resonance signals, proving the suitability of the microfabricated discharge lamp to introduce efficient optical pumping. The pumping ability of this light source was found to be comparable to or even better than that of a conventional glass-blown lamp. The reported results indicate that the micro-fabricated DBD discharge lamp has a high potential for the development of a new class of miniature atomic clocks, magnetometers, and quantum sensors

  7. 75 FR 51654 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-22B and RB211-524 Series Turbofan Engines

    Science.gov (United States)

    2010-08-23

    ... Airworthiness Directives; Rolls-Royce plc (RR) RB211-22B and RB211-524 Series Turbofan Engines AGENCY: Federal... that air safety and the public interest require adopting the AD as proposed. Costs of Compliance Based... labor rate is $85 per work-hour. Required parts will cost about $15,000 per product. Based on these...

  8. Long wavelength magnetic anomalies over continental rifts in cratonic region

    Science.gov (United States)

    Friedman, S. A.; Persaud, P.; Ferre, E. C.; Martín-Hernández, F.; Feinberg, J. M.

    2017-12-01

    New collections of unaltered mantle xenoliths shed light on potential upper mantle contributions to long wavelength magnetic anomalies (LWMA) in continental rifts in cratonic / shield areas. The new material originates from the East African Rift (Tanzania), the Rio Grande Rift (U.S.A.), the Rhine Rift (Germany), and the West Antarctic Rift (Antarctica). The xenoliths sample the uppermost ( 0.2 or Fe geotherms (>60ºC/km) that are characteristic of rifted regions preclude any contribution to LWMA at depths >10 km. Hence, only upper basalts and hypovolcanic mafic sills would constitute potential magnetic sources. In contrast, the margins of these rifted regions consist of refractory cratonic domains, often characterized by oxidized sublithospheric mantle that host significant concentrations of primary magnetite. The higher NRMs of these peridotites (up to 15 A/m, Qn > 2.5) combined with much lower geotherms (as low as 15ºC/km) allows for a 5 to 10 km layer of uppermost mantle to potentially contribute to LWMA. Assuming that Qn values in rift margins are also gradient across the rift would primarily reflect thermal equilibration over time.

  9. Lithospheric diamond formation as a consequence of methane-rich volatile flooding: An example from diamondiferous eclogite xenoliths of the Karelian craton (Finland)

    Science.gov (United States)

    Smart, K. A.; Cartigny, P.; Tappe, S.; O'Brien, H.; Klemme, S.

    2017-06-01

    A collection of 61 xenocrystic and 12 eclogite xenolith-derived diamonds from the 600 Ma Lahtojoki kimberlite in central Finland has been investigated. Calculated pressure and temperature conditions for the diamondiferous eclogites are in excess of 5.5 GPa and 1300 °C, suggesting residence depths greater than 180 km, near the base of the Karelian cratonic mantle lithosphere. Geochemically, the eclogite xenoliths have gabbroic compositions showing positive Eu and Sr anomalies, relatively low ΣREE and elevated Al2O3 contents, yet garnets have ambiguous δ18O values of 5.7‰ and 5.9‰. Gabbroic eclogite formation could therefore be linked to either subduction processes during the 1.9 Ga Svecofennian orogeny or to cumulate processes during 2.1 Ga rift-induced magmatism. Determination of the oxygen fugacity of Lahtojoki eclogite xenoliths from both this work and previous studies suggests that diamond-bearing eclogites may be more reduced (ΔFMQ-3.5) compared to barren eclogites (ΔFMQ-1.7). While recycled oceanic crust protoliths for the eclogites remain a possibility, the carbon isotopic compositions and nitrogen abundances of the Lahtojoki diamonds indicate mantle-derived volatile sources. All diamonds (i.e., loose and eclogite xenolith-derived) display a restricted range of δ13C values from -7.8‰ to -3.7‰ that overlaps with the carbon isotopic composition of Earth's mantle. The Lahtojoki diamond δ13C values form a negatively skewed distribution, indicating diamond growth from reduced mantle-derived carbon sources such as methane- (CH4) bearing fluids. Nitrogen contents of the Lahtojoki diamonds range from 40 to 1830 atomic ppm with a mean of ∼670 atomic ppm; these elevated nitrogen contents combined with the close association to eclogites suggest an eclogitic or crustal volatile source. However, the Karelian craton was periodically intruded by ultramafic alkaline magmas since at least 1.8 Ga, noting in particular the occurrence of phlogopite

  10. Biosafety of parenteral Brucella abortus RB51 vaccine in bison calves

    Science.gov (United States)

    Roffe, T.J.; Olsen, S.C.; Gidlewski, T.; Jensen, A.E.; Palmer, M.V.; Huber, R.

    1999-01-01

    Vaccination is considered among the primary management tools for reducing brucellosis prevalence in Greater Yellowstone Area (GYA) ungulates. Before their use, however, vaccine safety and efficacy must be demonstrated. Twenty-seven female bison (Bison bison) calves (approx 5 months old) were vaccinated with Brucella abortus Strain RB51 (1.5 x 1010 colony forming units [CFU], subcutaneously) as part of routine management. We assessed the persistence, pathology, shedding, and transmission associated with RB51 by serial necropsy, bacteriology, histopathology, and serology of 20 of these 27 vaccinated calves, and RB51 serology of 10 nonvaccinated, commingling adult females. With the exception of 1 calf, RB51 dot-blot titers at necropsy were <1:80. Strain RB51 was cultured from lymph nodes in 4 of 4 calves at 14 weeks postvaccination (PV), 4 of 4 calves at 18 weeks PV, 1 of 4 calves at 22 weeks PV, 3 of 4 at 26 weeks PV, and 0 of 4 calves at 30 weeks PV. No gross lesions were observed. Mild histologic changes occurred only in a few draining lymph nodes early in sampling. Adverse clinical effects were not observed in vaccinates. Swabs from nasopharynx, conjunctiva, rectum, and vagina were uniformly culture negative for RB51. Strain RB51 dot-blot assays of bison cows were negative at a 1:20 dilution at 26 weeks PV. Our results suggest that RB51 persists longer in bison calves than in domestic cattle and is systemically distributed within lymphatic tissues. However, bison apparently clear the RB51 vaccine strain without shedding, transmission, or significant adverse reactions.

  11. Occurrence of Two Different Types of Paleoarchean TTGs in Singhbhum craton, Eastern India: Insight from Geochemistry and Zircon Saturation Thermometry

    Science.gov (United States)

    Mitra, A.; Dey, S.

    2017-12-01

    Paleoarchean era is marked as an active period of continental crust genesis. A large part of the paleoarchean crust is made up of grey sodic granitoids collectively referred as Tonalite Trondjhemite Granodiorite (TTG). Generation and evolution of TTGs are still highly debated, though researchers agree on their generation through partial melting of hydrated basalt at garnet or amphibole stability field. Discrete remnants of paleoarchean TTGs are exposed in several parts of the Singhbhum craton, eastern India. Our study exhibits occurrence of two different types of TTGs based on REE pattern in a chondrite normalized REE diagram. Accordingly, TTGs have been grouped into two different types, namely (1) High HREE TTG [low SiO2; high HREE avg. (Gd/Er)n=2.23; less fractionated REE avg. (La/Yb)n=27.9 and relatively low Sr/Y avg. Sr/Y=53.59] and Low HREE TTG [high SiO2; depleted HREE avg. (Gd/Er)n=3.23; steeply fractionated REE avg. (La/Yb)n=46.11 and relatively high Sr/Y avg. Sr/Y= 95.49]. The two types of TTGs mainly differ in pressure sensitive signatures like Sr/Y and (La/Yb)n ratio. Considering the major element composition both the types are consistent with a low-K mafic source. This indicates, melting occurred at different crustal levels from a same/similar source. Moderate Al2O3, high Sr contents coupled with depleted HREE and Y are linked to the presence of garnet in either residual or fractionating phase. However, HREE variation is controlled by the amount of Garnet retained in the restite. Thus, in spite of melting of the source rock in garnet stability field, only the minor change in depth of melting and in turn different amount of retention of garnet in the source caused the difference in HREE pattern. Zircon saturation temperature (TZr) calculated on the basis of whole rock Zr concentration ranges from 735˚C to 760 ˚C (avg. 749˚C) for high HREE TTG and 750 ˚C to 802˚C (avg. 773˚C) for low HREE TTG. Absence of zircon xenocryst depicts zircon

  12. Shear-Velocity Structure and Azimuthal and Radial Anisotropy Beneath the Kaapvaal Craton From Bayesian Inversion of Surface-Wave Data: Inferences for the Architecture and Early Evolution of Cratons

    Science.gov (United States)

    Lebedev, S.; Ravenna, M.; Adam, J.

    2017-12-01

    Seismic anisotropy provides essential information on the deformation of the lithosphere. Knowledge of anisotropy also allows us to isolate the isotropic-average seismic velocities, relatable to the lithospheric temperature and composition. We use Rayleigh and Love-wave phase velocities and their azimuthal anisotropy measured in broad period ranges across the footprint of the Southern Africa Seismic Experiment (SASE), from the Kaapvaal Craton to the Limpopo Belt. We invert the data using our recently developed, fully non-linear Markov Chain Monte Carlo method and determine, for the first time, both the isotropic-average S velocity and its radial and azimuthal anisotropy as a function of depth from the upper crust down to the asthenosphere. The probabilistic inversion provides a way to quantify non-uniqueness, using direct parameter-space sampling, and assess model uncertainties. The high-velocity anomaly indicative of the cold cratonic lithosphere bottoms at 200-250 km beneath the central and western Kaapvaal Craton, underlain by a low-velocity zone. Beneath northern Kaapvaal and Limpopo, by contrast, high velocities extend down to 300-350 km. Although this does not require a lithosphere that has maintained this thickness over a geologically long time, the data does require the mantle to be anomalously cold down to 300-350 km. Interestingly, topography correlates with the thickness of this high-velocity layer, with lower elevations where the lid is thicker. Radial shear-wave anisotropy is in the 2-5 percent range (Vsh > Vsv) from the lower crust down to 200 km, below which depth it decreases gradually. Radial variations in the amplitude of radial anisotropy show no clear relationship with those in the amplitude of azimuthal anisotropy or isotropic-average Vs anomalies. Azimuthal anisotropy changes the fast-propagation direction near the base of the lithosphere (200-300 km depth), from the laterally varying fast azimuths in the lower lithosphere to a spatially

  13. Geochronology of granitoids and gnaisses from the Rio Maria, Mata Geral farm and Itacaiunas river regions, southern Para, Brazil

    International Nuclear Information System (INIS)

    Montalvao, R.M.G. de; Tassinari, C.C.G.; Bezerra, P.E.L.; Prado, P.

    1984-01-01

    Granitoids and gneisses occurring at Rio Maria, Mata Geral farm and Itacaiunas river regions, southern Para, underwent radiometric age determinations by Rb/Sr method using conventional isochrons. Results obtained from the Rio Maria and Mata Geral farm regions allowed te establishment of a reference 2,600 my Rb/Sr isochron with an initial Sr 87 /Sr 86 ratio of 0.7009. This result resembles the one obtained for granitoids and gneisses hosting rocks of the Serra do Inaja greenstone belt, located some what south of this area, which yielded, in Rb/Sr isochron, a radiometric age of 2,696 + - 79 my with an initial Sr 87 /Sr 86 ratio of 0.701. Results obtained from the Itacaiunas river region allowed for the establishment of a Rb/Sr referential isochron of 2,480 + - 40 my wth an initial Sr 87 /.Sr 86 ratio of 0.7072. Due to low initial ratios, it is suggested that the rocks from the Rio Maria, Mata Geral farm and Serra do Inaja regions formed from Mafic crust or superior mantle reworking, while those from the Itacaiunas river region, due to a high initial ratio, result from reworking at high crustal levels. (Author) [pt

  14. Brazil Geological Basic Survey Program - Espera River - Sheet SF.23-X-B-IV - Minas Gerais State

    International Nuclear Information System (INIS)

    Raposo, F.O.

    1991-01-01

    The present report refers to the Rio Espera sheet (SF.23.X-B-IV) systematic geological mapping, on the 1:100.000 scale. The sheet, which covers Zona da Mata region, includes the Southeastern bord of Minas Gerais Metallurgic Zone, SE of Quadrilatero Ferrifero, in the Sao Francisco craton bord, and Mantiqueira province. Since only one doubtful 2,5 thousand million year - Rb/Sr isochron was obtained in the sheet, Archacan and Proterozoic ages have been attributed to the metamorphic rocks by comparison to other ones elsewhere. An analysis of the crustal evolution pattern based on gravimetric survey data, aeromagnetometry and available geochronological data is given in the 6. Chapter, Part II of the text. Major elements oxides and rare-earths were analysed to establish parameters for the rocks environment elucidation. The geochemical survey was carried out with base on pan concentrated and stream sediments distributed throughout the sheet. (author)

  15. Terminalia catappa as bioindicator of environmental pollution in Cubatao city by SR-TXRF

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Silvana; Geraldo, Simoni Michetti, E-mail: silvana@fec.unicamp.b [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Civil, Arquitetura e Urbanismo. Dept. de Saneamento e Ambiente; Barroso, Regina Cely, E-mail: cely_barroso@hotmail.co [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Inst. de Fisica. Dept. de Fisica Aplicada; Vives, Ana Elisa Sirito de, E-mail: aesvives@unimep.b [Universidade Metodista de Piracicaba (UNIMEP), Santa Barbara D' Oeste, SP (Brazil). Faculdade de Engenharia, Arquitetura e Urbanismo; Cardoso, Simone Coutinho, E-mail: simone@if.ufrj.b [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Faculdade de Engenharia, Arquitetura e Urbanismo. Inst. de Fisica

    2009-07-01

    Fertilizer industries are considered the main environmental polluting of fluoride (F) and the industrial complex of the city of Cubatao, SP, Brazil, is an important fertilizer producer. This study aimed to evaluate the local pollution for toxic elements and its comparison with fluoride concentration using the urban vegetation as biomarker. For this, leaves of Terminalia catappa (popularly known for Hat-of-sun or Almond tree of the beach) were tested. The leaves were collected in the winter of 2007 in the industrial region around the fertilizer plants and other industries, in the municipal urban areas of Cubatao and Santos cities. The samples were dehydrated, powdered and submitted to an acid digestion for multi-elemental determination by Synchrotron Radiation Total Reflection X-Ray Fluorescence (SR-TXRF). All the measurements were performed at Synchrotron Light Source Laboratory. The results obtained by SR-TXRF were compared to fluoride determinations. The variance analysis showed the correlation between F and S concentrations (p<0.05). The concentrations of these elements are concentrated around the fertilizer industries (p< 0.05). Using SR-TXRF was possible to determine several elements as: Si, K, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Br, Rb, Sr and Pb in the leaves of Terminalia catappa. Chromium in the areas near to fertilizer industries and also in Santos city which is considered as a control area, present concentrations higher than 18 mg kg{sup -1}, this is considered a toxic value (author)

  16. Emission spectra of Rb*Hen exciplexes in a cold 4He gas

    International Nuclear Information System (INIS)

    Hirano, K.; Enomoto, K.; Kumakura, M.; Takahashi, Y.; Yabuzaki, T.

    2003-01-01

    We report on the systematic observation of emission spectra of Rb * He n exciplexes (n=1,2,...,6), realized by exciting Rb atoms to the 5 2 P states (Rb * ) in a cold 4 He gas. The observed broad spectral components are assigned to Rb * He n (n=1-6) using theoretical spectra obtained from ab initio potential curves. The dynamics of the exciplex formation is discussed, based on the observed temperature dependence of the spectra. The He gas density dependence of the spectra of Rb * He is understood as a change in the population distribution over the vibrational levels. The present results are compared with our previous work with Cs [K. Enomoto et al., Phys. Rev. A 66, 042505 (2002)], and differences are explained in terms of the difference in the fine-structure splitting. Furthermore, we show the emission spectrum observed after the excitation of Rb in liquid He and conclude that it is the fluorescence from the exciplex Rb * He 6

  17. Crystal structure of 4-RbHo(PO3)4, 4-RbTm(PO3)4 and 4-CsEr(PO3)4

    International Nuclear Information System (INIS)

    Maksimova, S.I.; Palkina, K.K.; Chibiskova, N.T.

    1982-01-01

    X-ray structural study of 4-RbLn(PO 3 ) 4 (Ln=Mo, Tm) and 4-CsEr(PO 3 ) 4 is carried out. The compounds are crystallized in monoclinic crystal system, sp. gr P2 1 /n. Parameters of their unit cell, atom coordinates, anisotropic heat parameters, interatomic distances and valent angles are given. 4-RbHo(PO 3 ) 4 , 4-RbTm(PO 3 ) 4 , 4-CsEr(PO 3 ) 4 are isostructural to previously studied TlNd(PO 3 ) and 4-RbNd(PO 3 ) 4 . Using as an example the structural type 4-M 1 Ln(PO 3 ) 4 it is shown that the change of the shortest distances Ln-Ln, M 1 -M 1 and M 1 -Ln, as well as of degree of polymorphous chain corrugation to a higher extent depends on rare earth atom dimensions, than on monovalent metal ion dimensions [ru

  18. Deregulation of the RB pathway in human testicular germ cell tumours

    DEFF Research Database (Denmark)

    Bartkova, Jirina; Lukas, Claudia; Sørensen, Claus S

    2003-01-01

    Deregulation of the RB pathway is shared by most human malignancies. Components upstream of the retinoblastoma tumour suppressor (pRB), namely the INK4 family of cyclin-dependent kinase (CDK) inhibitors, the D-type cyclins, their partner kinases CDK4/CDK6, and pRB as their critical substrate...

  19. Strontium and argon isotopes in naturally weathered biotites, muscovites and feldspars

    International Nuclear Information System (INIS)

    Clauer, N.

    1981-01-01

    A Rb-Sr and K-Ar isotopical study on progressively weathered biotites, muscovites and feldspars from plutonic and eruptive rocks shows that their continental weathering is a complex phenomenon controlled by environmental conditions. During weathering of biotites, the K-Ar couple often mimics the Rb-Sr couple. The radiogenic Sr and Ar isotopes are systematically leached out, but the behaviour of the elemental Rb, K, Sr and Ar depends upon the environment. In contrast, the Sr and Ar balances of muscovites are maintained, even during very intensive weathering. In mixtures of feldspars, the common Sr seems to be leached out preferentially to the radiogenic isotope, while the K-Ar balance is maintained. (Auth.)

  20. Research Project 'RB research nuclear reactor' (operation and maintenance), Final report; Naucnoistrazivacki projekt 'Istrazivacki nuclearni reaktor RB, (pogon i odrzavanje), Zavrsni elaborat projekta

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1985-07-01

    This final report covers operation and maintenance activities at the RB reactor during period from 1981-1985. First part covers the RB reactor operation, detailed description of reactor components, fuel, heavy water, reactor vessel, cooling system, equipment and instrumentation, auxiliary systems. It contains data concerned with dosimetry and radiation protection, reactor staff, and financial data. Second part deals maintenance, regular control and testing of reactor equipment and instrumentation. Third part is devoted to basic experimental options and utilization of the RB reactor including training.

  1. The immunological response of RB51 vaccinated buffalo calves ...

    African Journals Online (AJOL)

    radosova

    2011-09-07

    Sep 7, 2011 ... Consequently, cattle vaccinated with RB51 do not sero- convert on conventional .... 1997), iELISAs using a 5% optical density heat-killed whole RB51 .... In: Yousef MK (Ed.), Stress Physiology in Livestock,. Ungulates, vol. 2.

  2. Age and origin of anorthosites, charnockites, and granulites in the Central Virginia Blue Ridge: Nd and Sr isotopic evidence

    Science.gov (United States)

    Pettingill, H.S.; Sinha, A.K.; Tatsumoto, M.

    1984-01-01

    Rb-Sr isotopic data for anorthosites, charnockites, ferrodioritic to quartz monzonitic plutons, and high-grade gneisses of the Blue Ridge of central Virginia show evidence of post-emplacement metamorphism, but in some cases retain Grenville ages. The Pedlar River Charnockite Suite yields an isochron age of 1021 +/-36 Ma, (initial 87Sr/86Sr ratio of 0.7047 +/-6), which agrees with published U-Pb zircon ages. Five samples of that unit which contain Paleozoic mylonitic fabrics define a regression line of 683 Ma, interpreted as a mixing line with no age significance. Samples of the Roseland Anorthosite Complex show excessive scatter on a Rb-Sr evolution diagram probably due to Paleozoic (475 m.y.) metamorphism. Data from the ferrodioritic to quartz monzonitic plutons of the area yield an age of 1009 +/-26 Ma (inital ratio=0.7058 +/-4), which is in the range of the U-Pb zircon ages of 1000-1100 Ma. The Stage Road Layered Gneiss yields an age of 1147 +/-34 Ma (initial ratio of 0.7047 +/- 5). Sm-Nd data for the Pedlar River Charnockite Suite reflect a pre-Grenville age of 1489 +/-118 Ma (e{open}Nd=+6.7 +/-1.2). Data for the Roseland Anorthosite Complex and the ferrodioritic to quartz monzonitic plutons yield Grenville isochron ages of 1045 +/44 Ma (e{open}Nd=+1.0 +/-0.3) and 1027 +/-101 Ma (e{open}Nd=+1.4 +/-1.0), respectively. Two Roseland Anorthosite samples plot far above the isochron, demonstrating the effects of post-emplacement disturbance of Sm-Nd systematics, while mylonitized Pedlar River Charnockite Suite samples show no evidence of Sm-Nd redistribution. The disparity of the Sm-Nd age and other isotopic ages for the Pedlar River Charnockite Suite probably reflects a Sm-Nd "source" age, suggesting the presence of an older crust within this portion of the ca. 1 Ga old basement. ?? 1984 Springer-Verlag.

  3. Accretionary Tectonics of Rock Complexes in the Western Margin of the Siberian Craton

    Science.gov (United States)

    Likhanov, I. I.; Nozhkin, A. D.; Savko, K. A.

    2018-01-01

    The geological, geochemical, and isotope-geochronological evidence of the events at the final stage of the Neoproterozoic history of the Yenisei Range is considered (beginning from the formation of fragments of the oceanic crust in the region and their accretion to the Siberian Craton until the postaccretionary stage of crustal tension and onset of the Caledonian orogeny). Based on an analysis of new data on the petrogeochemical composition, age, and geodynamic nature of the formation of contrasting rocks in the composition of tectonic mélange of the Near-Yenisei (Prieniseiskaya) regional shear zone, we have found the chronological sequence of events that marks the early stages of the Paleoasian Ocean evolution in the zone of its junction with the Siberian Craton. These events are documented by the continental marginal, ophiolitic, and island-arc geological complexes, each of which has different geochemical features. The most ancient structures are represented by fragments of oceanic crust and island arcs from the Isakovka terrane (700-620 Ma). The age of glaucophane-schist metamorphic units that formed in the paleosubduction zone corresponds to the time interval of 640-620 Ma. The formation of high-pressure tectonites in the suture zone, about 600 Ma in age, marks the finishing stage of accretion of the Isakovka block to the western margin of the Siberian Craton. The final events in the early history of the Asian Paleoocean were related to the formation of Late Vendian riftogenic amygdaloidal basalts (572 ± 6.5 Ma) and intrusion of postcollisional leucogranites of the Osinovka massif (550-540 Ma), which intruded earlier fragments of the oceanic crust in the Isakovka terrane. These data allow us to refine the Late Precambrian stratigraphic scheme in the northwestern Trans-Angarian part of the Yenisei Range and the evolutionary features of the Sayan-Yenisei accretionary belt. The revealed Late Neoproterozoic landmarks of the evolution of the Isakovka terrane are

  4. RB research nuclear reactor, Annual report for 1981

    International Nuclear Information System (INIS)

    Markovic, H.; Sotic, O.; Pesic, M.; Vranic, S.; Zivkovic, B.; Bogdanovic, M.; Petronijevic, M.

    1981-01-01

    The annual report for 1981 includes the following: utilization of the RB reactor; accident and incidents analysis; description of the reactor equipment status; dosimetry and radiation protection; RB reactor staff; financial data. Seven Annexes to this report are concerned with: maintenance of the reactor components and equipment, including nuclear fuel, heavy water, reactor vessel, heavy water coolant circuit, experimental platforms, absorption rods; maintenance of the electric power supply system, neutron source equipment, crane; control and maintenance of ventilation and heating systems, gas and comprised gas systems, fire protection system; plan for renewal of the reactor components; contents of the RB reactor safety report; reactor staff; review of measured radiation doses; experimental methods; training of the staff; and financial report

  5. Optical pumping in a microfabricated Rb vapor cell using a microfabricated Rb discharge light source

    Energy Technology Data Exchange (ETDEWEB)

    Venkatraman, V.; Kang, S.; Affolderbach, C.; Mileti, G., E-mail: gaetano.mileti@unine.ch [Laboratoire Temps-Fréquence, University of Neuchâtel, Neuchâtel 2000 (Switzerland); Shea, H. [Microsystems for Space Technologies Laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), Neuchâtel 2002 (Switzerland)

    2014-02-03

    Miniature (Rb discharge lamp light source, as well as (2) a conventional glass-blown Rb discharge lamp. The microfabricated Rb lamp cell is a dielectric barrier discharge (DBD) light source, having the same inner cell volume of around 40 mm{sup 3} as that of the resonance cell, both filled with suitable buffer gases. A miniature (∼2 cm{sup 3} volume) test setup based on the M{sub z} magnetometer interrogation technique was used for observation of optical-radiofrequency double-resonance signals, proving the suitability of the microfabricated discharge lamp to introduce efficient optical pumping. The pumping ability of this light source was found to be comparable to or even better than that of a conventional glass-blown lamp. The reported results indicate that the micro-fabricated DBD discharge lamp has a high potential for the development of a new class of miniature atomic clocks, magnetometers, and quantum sensors.

  6. Petrogenesis of Luchuba and Wuchaba granitoids in western Qinling: geochronological and geochemical evidence

    Science.gov (United States)

    Kong, Juanjuan; Niu, Yaoling; Duan, Meng; Zhang, Yu; Hu, Yan; Li, Jiyong; Chen, Shuo

    2017-12-01

    The West Qinling Orogenic Belt (WQOB) is a major portion of the Qinling-Dabie-Sulu Orogen and holds essential information for understanding the prolonged evolution of the northeastern branch of the Paleo-Tethys in East Asia. This study focuses on the petrogenesis of granitoids from Luchuba and Wuchaba plutons in the WQOB. We obtained zircon U-Pb ages of 211 ± 1.4 Ma for the Luchuba pluton and 218.7 ± 1.3 Ma for the Wuchaba pluton, which are the same as the proposed timing of continental collision at ˜220 Ma. We thus interpret the granitoids to represent a magmatic response to the collision between the North China Craton (NCC) and the Yangtze Block (YB). The two plutons are metaluminous to weakly peraluminous I-type granitoids. Samples from the two plutons show strong light rare earth element (REEs) enrichment and weak heavy REE depletion, with varying negative Eu anomalies, which is most consistent with significant plagioclase fractionation although the possible effect of plagioclase as residual phase in the magma source region cannot be ruled out. In primitive mantle normalized multi-element variation diagrams, nearly all the samples show negative Nb, Ta, P and Ti anomalies and relative enrichment in Rb, Pb, U and K. These characteristics resemble those of the average continental crust. The Luchuba pluton has lower (87Sr/86Sr)i (0.7051 to 0.7104), higher ɛNd(t) (-8.11 to -5.73) and ɛHf(t) (-6.70 to -1.65) than mature continental crust ([87Sr/86Sr] i > 0.72, ɛNd(t) pluton also has lower (87Sr/86Sr)i (0.7069 to 0.7080), higher ɛNd(t) (-9.86 to -3.34) and ɛHf(t) (-5.69 to 1.58) than mature continental crust. We conclude that the Luchuba and Wuchaba granitoids in the WQOB are best explained as resulting from fractional crystallization with crustal assimilation of parental magmas derived from melting of Mianlue oceanic crust under amphibolite facies conditions during the initial stage of continental collision between the North China Craton and the Yangtze Block

  7. Satellite bands of the RbCs molecule in the range of highly excited states

    Energy Technology Data Exchange (ETDEWEB)

    Rakić, Mario; Beuc, Robert; Skenderović, Hrvoje, E-mail: hrvoje@ifs.hr [Institute of Physics, Bijenička cesta 46, Zagreb 10000 (Croatia); Bouloufa-Maafa, Nadia; Dulieu, Olivier; Vexiau, Romain [Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, Université Paris-Saclay, Bât. 505, Campus d’Orsay, Orsay Cedex 91405 (France); Pichler, Goran [Physics Department, Kuwait University, PO Box 5969, Safat—13060 (Kuwait)

    2016-05-28

    We report on the observation of three RbCs satellite bands in the blue and green ranges of the visible spectrum. Absorption measurements are performed using all-sapphire cell filled with a mixture of Rb and Cs. We compare high resolution absorption spectrum of Rb-Cs vapor mixture with pure Rb and Cs vapor spectra from the literature. After detailed analysis, the new satellite bands of RbCs molecule at 418.3 nm, 468.3, and 527.5 nm are identified. The origin of these bands is discussed by direct comparison with difference potentials derived from quantum chemistry calculations of RbCs potential energy curves. These bands originate from the lower Rydberg states of the RbCs molecule. This study thus provides further insight into photoassociation of lower Rydberg molecular states, approximately between Cs(7s) + Rb(5s) and Cs(6s) + Rb(6p) asymptotes, in ultracold gases.

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

    International Nuclear Information System (INIS)

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

    1979-01-01

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

  9. Intermediate-range chemical ordering of cations in molten RbCl-AgCl

    Energy Technology Data Exchange (ETDEWEB)

    Tahara, S. [Department of Physics and Earth Sciences, Faculty of Science, University of the Ryukyus, Okinawa 903-0213 (Japan); Research and Utilization Division, Japan Synchrotron Radiation Research Institute (JASRI, SPring-8), Hyogo 679-5198 (Japan); Kawakita, Y. [J-PARC Center, Japan Atomic Energy Agency (JAEA), Ibaraki 319-1195 (Japan); Shimakura, H. [Faculty of Pharmacy, Niigata University of Pharmacy and Applied Life Sciences, Niigata 956-8603 (Japan); Ohara, K. [Research and Utilization Division, Japan Synchrotron Radiation Research Institute (JASRI, SPring-8), Hyogo 679-5198 (Japan); Fukami, T. [Department of Physics and Earth Sciences, Faculty of Science, University of the Ryukyus, Okinawa 903-0213 (Japan); Takeda, S. [Department of Physics, Faculty of Sciences, Kyushu University, Fukuoka 812-8581 (Japan)

    2015-07-28

    A first sharp diffraction peak (FSDP) is observed in the X-ray total structure factor of a molten mixture of RbCl-AgCl, while both pure melts of RbCl and AgCl do not exhibit FSDP individually. Molecular dynamics simulations were performed to investigate the origin of the FSDP with the polarizable ion model (PIM). Coexistence of covalent Ag–Cl and ionic Rb–Cl bonds leads the system to evolve intermediate range ordering, which is simulated by introducing the induced polarization in different ways between Ag–Cl with fully polarizable treatment based on Vashishta-Raman potential and Rb–Cl with suppression over-polarization in the nearest neighbor contribution based on Born-Meyer potential. The partial structure factors for both the Ag–Ag and Rb–Rb correlations, S{sub AgAg}(Q) and S{sub RbRb}(Q), show a positive contribution to the FSDP, while S{sub AgRb}(Q) for the Ag–Rb correlation exhibits a negative contribution, indicating that Ag and Rb ions are distributed in an alternating manner within the intermediate-range length scale. The origin of the intermediate-range chemical ordering of cations can be ascribed to the preferred direction of the dipole moments of anions in the PIM.

  10. Immunohistochemical study of p53, pRb, p16 in esophageal cancer

    International Nuclear Information System (INIS)

    Zo, Jae Ill; Zo, Kyung Ja; Park, Jong Ho; Kim, Mi Hee

    1998-01-01

    To confirm the expression of molecular genetic alterations of p53, pRb, p16 in esophageal cancer and to investigate the expression of p53, pRb, p16 in esophageal cancer according to the pathologic steps of carcinogenesis, immuno-histochemistry was performed in 15 resected esophageal cancer specimens with multiple separated lesions after pathologic mapping. The accumulation of mutant p53 was observed in 60 % of dysplasia and 47 % of invasive cancer, while pRb was not detected in 91 % of dysplasia and 72.7 % of invasive cancer. But p16 was not observed in 0 % in dysplasia and 7 % of invasive cancer. But p16 was not observed in 0 % in dysplasia and 28.6 % in invasive cancer. There was no simultaneous negative pRb and p16 expression. There was no relations between p53 and p16, pRb. As a results, the expression of p53, pRb, p16 was co-related well with molecular genetic changes and inactivation of p53, pRb, p16 was co-related well with molecular genetic changes and inactivation of p53 and pRb was common and early event in esophageal carcinogenesis in Korea, but inactivation of p16 was a infrequent change. (author). 17 refs., 2 tabs., 7 figs

  11. Intermediate-range chemical ordering of cations in molten RbCl-AgCl

    International Nuclear Information System (INIS)

    Tahara, S.; Kawakita, Y.; Shimakura, H.; Ohara, K.; Fukami, T.; Takeda, S.

    2015-01-01

    A first sharp diffraction peak (FSDP) is observed in the X-ray total structure factor of a molten mixture of RbCl-AgCl, while both pure melts of RbCl and AgCl do not exhibit FSDP individually. Molecular dynamics simulations were performed to investigate the origin of the FSDP with the polarizable ion model (PIM). Coexistence of covalent Ag–Cl and ionic Rb–Cl bonds leads the system to evolve intermediate range ordering, which is simulated by introducing the induced polarization in different ways between Ag–Cl with fully polarizable treatment based on Vashishta-Raman potential and Rb–Cl with suppression over-polarization in the nearest neighbor contribution based on Born-Meyer potential. The partial structure factors for both the Ag–Ag and Rb–Rb correlations, S AgAg (Q) and S RbRb (Q), show a positive contribution to the FSDP, while S AgRb (Q) for the Ag–Rb correlation exhibits a negative contribution, indicating that Ag and Rb ions are distributed in an alternating manner within the intermediate-range length scale. The origin of the intermediate-range chemical ordering of cations can be ascribed to the preferred direction of the dipole moments of anions in the PIM

  12. RbCuFe(PO42

    Directory of Open Access Journals (Sweden)

    Mongi Ben Amara

    2013-08-01

    Full Text Available A new iron phosphate, rubidium copper(II iron(III bis(phosphate, RbCuFe(PO42, has been synthesized as single crystals by the flux method. This compound is isostructural with KCuFe(PO42 [Badri et al. (2011, J. Solid State Chem. 184, 937–944]. Its structure is built up from Cu2O8 units of edge-sharing CuO5 polyhedra, interconnected by FeO6 octahedra through common corners to form undulating chains that extend infinitely along the [011] and [01-1] directions. The linkage of such chains is ensured by the PO4 tetraedra and the resulting three-dimensional framework forms quasi-elliptic tunnels parallel to the [101] direction in which the Rb+ cations are located.

  13. CENPA overexpression promotes genome instability in pRb-depleted human cells

    Directory of Open Access Journals (Sweden)

    Lentini Laura

    2009-12-01

    Full Text Available Abstract Background Aneuploidy is a hallmark of most human cancers that arises as a consequence of chromosomal instability and it is frequently associated with centrosome amplification. Functional inactivation of the Retinoblastoma protein (pRb has been indicated as a cause promoting chromosomal instability as well centrosome amplification. However, the underlying molecular mechanism still remains to be clarified. Results Here we show that pRb depletion both in wild type and p53 knockout HCT116 cells was associated with the presence of multipolar spindles, anaphase bridges, lagging chromosomes and micronuclei harbouring whole chromosomes. In addition aneuploidy caused by pRb acute loss was not affected by p53 loss. Quantitative real-time RT-PCR showed that pRB depletion altered expression of genes involved in centrosome duplication, kinetochore assembly and in the Spindle Assembly Checkpoint (SAC. However, despite MAD2 up-regulation pRb-depleted cells seemed to have a functional SAC since they arrested in mitosis after treatments with mitotic poisons. Moreover pRb-depleted HCT116 cells showed BRCA1 overexpression that seemed responsible for MAD2 up-regulation. Post-transcriptional silencing of CENPA by RNA interference, resulting in CENP-A protein levels similar to those present in control cells greatly reduced aneuploid cell numbers in pRb-depleted cells. Conclusion Altogether our findings indicate a novel aspect of pRb acute loss that promotes aneuploidy mainly by inducing CENPA overexpression that in turn might induce micronuclei by affecting the correct attachment of spindle microtubules to kinetochores.

  14. An isotopic perspective on growth and differentiation of Proterozoic orogenic crust: From subduction magmatism to cratonization

    Science.gov (United States)

    Johnson, Simon P.; Korhonen, Fawna J.; Kirkland, Christopher L.; Cliff, John B.; Belousova, Elena A.; Sheppard, Stephen

    2017-01-01

    The in situ chemical differentiation of continental crust ultimately leads to the long-term stability of the continents. This process, more commonly known as 'cratonization', is driven by deep crustal melting with the transfer of those melts to shallower regions resulting in a strongly chemically stratified crust, with a refractory, dehydrated lower portion overlain by a complementary enriched upper portion. Since the lower to mid portions of continental crust are rarely exposed, investigation of the cratonization process must be through indirect methods. In this study we use in situ Hf and O isotope compositions of both magmatic and inherited zircons from several felsic magmatic suites in the Capricorn Orogen of Western Australia to highlight the differentiation history (i.e. cratonization) of this portion of late Archean to Proterozoic orogenic crust. The Capricorn Orogen shows a distinct tectonomagmatic history that evolves from an active continental margin through to intracratonic reworking, ultimately leading to thermally stable crust that responds similarly to the bounding Archean Pilbara and Yilgarn Cratons. The majority of magmatic zircons from the main magmatic cycles have Hf isotopic compositions that are generally more evolved than CHUR, forming vertical arrays that extend to moderately radiogenic compositions. Complimentary O isotope data, also show a significant variation in composition. However, combined, these data define not only the source components from which the magmas were derived, but also a range of physio-chemical processes that operated during magma transport and emplacement. These data also identify a previously unknown crustal reservoir in the Capricorn Orogen.

  15. He 3 -Xe 129 Comagnetometery using Rb 87 Detection and Decoupling

    Science.gov (United States)

    Limes, M. E.; Sheng, D.; Romalis, M. V.

    2018-01-01

    We describe a He 3 -Xe 129 comagnetometer using Rb 87 atoms for noble-gas spin polarization and detection. We use a train of Rb 87 π pulses and σ+/σ- optical pumping to realize a finite-field Rb magnetometer with suppression of spin-exchange relaxation. We suppress frequency shifts from polarized Rb by measuring the He 3 and Xe 129 spin precession frequencies in the dark, while applying π pulses along two directions to depolarize Rb atoms. The plane of the π pulses is rotated to suppress the Bloch-Siegert shifts for the nuclear spins. We measure the ratio of He 3 to Xe 129 spin precession frequencies with sufficient absolute accuracy to resolve Earth's rotation without changing the orientation of the comagnetometer. A frequency resolution of 7 nHz is achieved after integration for 8 h without evidence of significant drift.

  16. Rb-intercalated C60 compounds studied by Inverse Photoemission Spectroscopy

    International Nuclear Information System (INIS)

    Finazzi, M.; Brambilla, A; Biagioni, P.; Cattoni, A.; Duo, L.; Ciccacci, F.; Braicovich, L.; Giovanelli, L.; Goldoni, A.

    2004-01-01

    Full text: Since the discovery of superconductivity in alkali-doped solid C 60 , the electronic structure of the host material (C 60 ) and the doped compounds (A x C 60 , where A is an alkali metal), has been the subject of a considerable amount of work, both theoretical and experimental. The spectroscopic investigations of the alkali-doped C 60 compounds has been mainly focussed on the valence states, while much less information is available on the unoccupied states. In particular, inverse photoemission data on the complete set of stable Rb x C 60 compounds was, so far, still missing. We have performed Inverse Photoemission (IPE) spectroscopy on Rb x C 60 compounds (x = 1, 3, 4, 6). IPE spectra were obtained using a band-pass photon detector (hv = 9.4 eV, FWHM = 0.7 eV) and scanning the kinetic energy of the electrons impinging on the sample. Rb was evaporated on C 60 films (thickness = 6-12 atomic layers) grown in situ on a Cu(100) substrate. The temperature of the substrate was kept equal to T = 100 deg C, which is lower than the C 60 sublimation temperature. The amount of Rb was checked by measuring the intensity of the C1s and Rb3d photoemission lines. After the required amount of Rb had been deposited, the samples were annealed to distillate the desired stable phase

  17. The Cretaceous Duimiangou adakite-like intrusion from the Chifeng region, northern North China Craton: Crustal contamination of basaltic magma in an intracontinental extensional environment

    Science.gov (United States)

    Fu, Lebing; Wei, Junhao; Kusky, Timothy M.; Chen, Huayong; Tan, Jun; Li, Yanjun; Shi, Wenjie; Chen, Chong; Zhao, Shaoqing

    2012-03-01

    Zircon U-Pb ages, major and trace element and Sr, Nd and Pb isotope compositions of the Duimiangou (DMG) quartz monzonite from the Chifeng region on the northern North China Craton (NCC) were studied to investigate its derivation, evolution and geodynamic significance. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U-Pb dating yields an emplacement age of 128 ± 1 Ma for this intrusion, with numerous Mesozoic inherited zircons clustering at 219 ± 12 Ma and 161 ± 3 Ma, along with some ancient zircons with ages of 2.5 Ga, 1.77 Ga and 324 Ma. Bulk-rock analyses show that this intrusion is characterized by variable SiO2 (63.4-69.4 wt.%), Al2O3 (14.5-16.3 wt.%), Na2O + K2O (8.01-8.95 wt.%), and Mg# (41.3-48.0). They are enriched in large ion lithophile elements and light rare earth elements without significant Eu anomalies (mostly between 0.89-1.10), and depleted in heavy rare earth elements and high field strength elements, with high Sr/Y (63.7-101.7) and (La/Yb)N (20.5-31.0) ratios. The DMG intrusion formed in an intracontinental extensional setting contemporaneous with the formation of pull-apart basins, metamorphic core complexes and intense magmatism, rather than in a convergent margin. It has homogeneous Sr ((87Sr/86Sr)i = 0.7059-0.7066), Nd (εNd(t) = - 6.2 to - 7.2) and Pb ((206Pb/204Pb)i = 17.289-17.375, (207Pb/204Pb)i = 15.359-15.463, (208Pb/204Pb)i = 37.130-37.472) isotope compositions. Sr-Nd isotope modeling results, plus relatively young Nd model ages (1522-1618 Ma) and the presence of relict zircons, suggest that this intrusion could have originated from crustal contamination of newly formed basaltic melts derived from asthenospheric mantle, accompanied by fractional crystallization of K-feldspar, biotite, apatite, Fe-Ti oxides and minor hornblende and plagioclase. Thus, the DMG adakite-like intrusion may record the magmatic event associated with underplating of asthenospheric magma in an intracontinental extensional

  18. Molecular dissociation and nascent product state distributions detected with atomic wavepacket interferometry and parametric four-wave mixing: Rb2 predissociation observed by quantum beating in Rb at 18.2 THz

    International Nuclear Information System (INIS)

    Xiao, Y; Senin, A A; Ricconi, B J; Kogler, R; Zhu, C J; Eden, J G

    2008-01-01

    Dissociation of a diatomic molecule and the excited-state distribution of the nascent atomic fragments can be detected and characterized by atomic wavepacket interferometry and a coherent nonlinear optical process, such as parametric four-wave mixing (PFWM), in ultrafast pump-probe experiments. Underlying these experiments is a reliance on atom-atom interaction to alter the properties of an atomic wavepacket which, in turn, impacts the phase and amplitude of a coherent optical signal. Specifically, quantum beating in the atomic species provides a sensitive, in situ probe of molecular dissociation by detecting approaching dissociation fragments through long-range dipole-dipole interaction. The resulting influence of this interaction on the amplitude and phase of the quantum beating is observed in temporal or Fourier domains by probing the wavepacket by interferometry and PFWM with 100-150 fs laser pulses. The wavepacket thus serves as a detector of molecular dissociation fragments and the dynamics of atom-atom interactions are converted into the macroscopic domain by the PFWM signal and idler waves. Femtosecond pump-probe experiments are described in which the predissociation of electronically excited Rb 2 states in the ∼24 000-28 000 cm -1 interval, and the distribution of nascent atomic fragments into Rb excited states (7s, 5d, 6s, 4d and 5p) spanning an energy range >1.25 eV, have been observed in Rb vapour with atomic number densities of ∼6 x 10 13 -3 x 10 17 cm -3 . Quantum beating at 18.2 THz (corresponding to the Rb 7s-5d J (J = 5/2) energy defect of ∼608 cm -1 ) is superimposed onto the axially phase matched PFWM signal wave generated at λ S ∼ 420 nm (Rb 6 2 P J → 5 2 S 1/2 transitions) and recovered by Fourier analysis of the signal wave intensity as the pump-probe time delay (Δt) is scanned. The dominant exit channels for Rb 2 predissociation are found to be sensitive to the interval of internuclear separation R in which the molecular

  19. ATM/RB1 mutations predict shorter overall survival in urothelial cancer.

    Science.gov (United States)

    Yin, Ming; Grivas, Petros; Emamekhoo, Hamid; Mendiratta, Prateek; Ali, Siraj; Hsu, JoAnn; Vasekar, Monali; Drabick, Joseph J; Pal, Sumanta; Joshi, Monika

    2018-03-30

    Mutations of DNA repair genes, e.g. ATM/RB1 , are frequently found in urothelial cancer (UC) and have been associated with better response to cisplatin-based chemotherapy. Further external validation of the prognostic value of ATM/RB1 mutations in UC can inform clinical decision making and trial designs. In the discovery dataset, ATM/RB1 mutations were present in 24% of patients and were associated with shorter OS (adjusted HR 2.67, 95% CI, 1.45-4.92, p = 0.002). There was a higher mutation load in patients carrying ATM/RB1 mutations (median mutation load: 6.7 versus 5.5 per Mb, p = 0.072). In the validation dataset, ATM/RB1 mutations were present in 22.2% of patients and were non-significantly associated with shorter OS (adjusted HR 1.87, 95% CI, 0.97-3.59, p = 0.06) and higher mutation load (median mutation load: 8.1 versus 7.2 per Mb, p = 0.126). Exome sequencing data of 130 bladder UC patients from The Cancer Genome Atlas (TCGA) dataset were analyzed as a discovery cohort to determine the prognostic value of ATM/RB1 mutations. Results were validated in an independent cohort of 81 advanced UC patients. Cox proportional hazard regression analysis was performed to calculate the hazard ratio (HR) and 95% confidence interval (CI) to compare overall survival (OS). ATM/RB1 mutations may be a biomarker of poor prognosis in unselected UC patients and may correlate with higher mutational load. Further studies are required to determine factors that can further stratify prognosis and evaluate predictive role of ATM/RB1 mutation status to immunotherapy and platinum-based chemotherapy.

  20. PALEOARCHEAN MAFIC ROCKS OF THE SOUTHWESTERN SIBERIAN CRATON: PRELIMINARY GEOCHRONOLOGY AND GEOCHEMICAL CHARACTERIZATION

    Directory of Open Access Journals (Sweden)

    A. V. Ivanov

    2017-01-01

    Full Text Available The Siberian craton consists of Archean blocks, which were welded up into the same large unit by ca 1.9 Ga [Gladkochub et al., 2006; Rojas-Agramonte et al., 2011]. The history of the constituent Archean blocks is mosaic because of limited number of outcrops, insufficient sampling coverage because of their location in remote regions and deep forest and difficulties with analytical studies of ancient rocks, which commonly underwent metamorphic modifications and secondary alterations. In this short note, we report data on discovery of unusual for Archean mafic rocks of ultimate fresh appearance. These rocks were discovered within southwestern Siberian craton in a region near a boundary between Kitoy granulites of the Sharyzhalgai highgrade metamorphic complex and Onot green-schist belt (Fig. 1. Here we present preliminary data on geochronology of these rocks and provide their geochemical characterization.

  1. Study of positive-parity yrast band in 83Rb

    International Nuclear Information System (INIS)

    Ganguly, S.; Banerjee, P.; Ray, I.; Kshetri, R.; Bhattacharya, S.; Saha Sarkar, M.; Goswami, A.; Muralithar, S.; Singh, R.P.; Kumar, R.; Bhowmik, R.K.

    2005-01-01

    The properties of the positive-parity yrast band in the odd-A 81,83,85 Rb (Z=37) isotopes show remarkable changes as N increases. The objective of the present work is to study the structure of the lowest positive-parity band in 83 Rb from lifetime studies

  2. Microbial conversion of major ginsenoside Rb1 to minor ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-12-15

    Dec 15, 2009 ... minor ginsenoside Rd by Indian fermented food bacteria. Kalaiselvi ... South Korea. Accepted 17 April, 2009. Ginsenoside Rb1 is the predominant secondary metabolite (saponin) in Panax ginseng. Hydrolysis of the sugar .... culture and 200 µl of major ginsenoside Rb1. The reaction mixture was incubated ...

  3. Ginsenoside Rb1 Protects Rat Neural Progenitor Cells against Oxidative Injury

    Directory of Open Access Journals (Sweden)

    Na Ni

    2014-03-01

    Full Text Available Ginseng, the root of Panax ginseng C.A. Meyer, has been used as a tonic to enhance bodily functions against various ailments for hundreds of years in Far Eastern countries without apparent adverse effects. Ginsenoside Rb1, one of the most active ingredients of ginseng, has been shown to possess various pharmacological activities. Here we report that Rb1 exhibits potent neuroprotective effects against oxidative injury induced by tert-butylhydroperoxide (t-BHP. Lactate dehydrogenase (LDH assay demonstrated that incubation with 300 µm t-BHP for 2.5 h led to a significant cell loss of cultured rat embryonic cortex-derived neural progenitor cells (NPCs and the cell viability was pronouncedly increased by 24 h pretreatment of 10 µm Rb1. TUNEL staining further confirmed that pretreatment of Rb1 significantly reduced the cell apoptosis in t-BHP-induced oxidative injury. Real time PCR revealed that pretreatment with Rb1 activated Nrf2 pathway in cultured NPCs and led to an elevated expression of HO-1. The results of the present study demonstrate that Rb1 shows a potent anti-oxidative effect on cultured NPCs by activating Nrf2 pathway.

  4. Lower Crustal Seismicity, Volatiles, and Evolving Strain Fields During the Initial Stages of Cratonic Rifting

    Science.gov (United States)

    Lambert, C.; Muirhead, J.; Ebinger, C. J.; Tiberi, C.; Roecker, S. W.; Ferdinand-Wambura, R.; Kianji, G.; Mulibo, G. D.

    2014-12-01

    The volcanically active East African rift system in southern Kenya and northern Tanzania transects thick cratonic lithosphere, and comprises several basins characterized by deep crustal seismicity. The US-French-Tanzania-Kenya CRAFTI project aims to understand the role of magma and volatile movement during the initiation and evolution of rifting in cratonic lithosphere. Our 38-station broadband network spans all or parts of fault-bounded rift segments, enabling comparison of lithospheric structure, fault kinematics, and seismogenic layer thickness with age and proximity to the deeply rooted Archaen craton. Seismicity levels are high in all basins, but we find profound differences in seismogenic layer thickness along the length of the rift. Seismicity in the Manyara basin occurs almost exclusively within the lower crust, and in spatial clusters that have been active since 1990. In contrast, seismicity in the ~ 5 My older Magadi basin is localized in the upper crust, and the long border fault bounding the west side of the basin is seismically inactive. Between these two basins lies the Natron rift segment, which shows seismicity between ~ 20 and ~2 km depth, and high concentrations at Oldoinyo Lengai and Gelai volcanoes. Older volcanoes on the uplifted western flank (e.g., Ngorongoro) experience swarms of activity, suggesting that active magmatism and degassing are widespread. Focal mechanisms of the frequent earthquakes recorded across the array are spatially variable, and indicate a stress field strongly influenced by (1) Holocene volcanoes, (2) mechanical interactions between adjacent rift basins, and (3) a far-field ESE-WNW extensional stress regime. We explore the spatial correlation between zones of intense degassing along fault systems and seismicity, and examine the influence of high gas pressures on lower and upper crustal seismicity in this youthful cratonic rift zone.

  5. New paleomagnetic results on ˜ ˜2367 Ma Dharwar giant dyke swarm, Dharwar craton, southern India: implications for Paleoproterozoic continental reconstruction

    Science.gov (United States)

    Babu, N. Ramesh; Venkateshwarlu, M.; Shankar, Ravi; Nagaraju, E.; Parashuramulu, V.

    2018-02-01

    Here we report new paleomagnetic results and precise paleopole position of the extensional study on ˜ 2367 Ma mafic giant radiating dyke swarm in the Dharwar craton, southern India. We have sampled 29 sites on 12 dykes from NE-SW Karimnagar-Hyderabad dykes and Dhone-Gooty sector dykes, eastern Dharwar craton to provide unambiguous paleomagnetism evidence on the spectacular radiating dyke swarm and thereby strengthening the presence of single magmatic event at ˜ 2367 Ma. A total of 158 samples were subjected to detailed alternating field and thermal demagnetization techniques and the results are presented here along with previously reported data on the same dyke swarm. The remanent magnetic directions are showing two components, viz., seven sites representing four dykes show component (A) with mean declination of 94{{}°} and mean inclination of - 70{{}°} (k=87, α_{95}=10{{}°}) and corresponding paleopole at 16{{}°}N, 41{{}°}E (dp=15{{}°} and dm=17{{}°}) and 22 sites representing 8 dykes yielded a component (B) with mean declination of 41{{}°} and mean inclination of - 21{{}°} (k=41, α_{95}=9{{}°}) with a paleopole at 41{{}°}N, 200{{}°}E (dp=5{{}°} and dm=10{{}°}). Component (A) results are similar to the previously reported directions from the ˜ 2367 Ma dyke swarm, which have been confirmed fairly reliably to be of primary origin. The component (B) directions appear to be strongly overprinted by the 2080 Ma event. The grand mean for the primary component (A) combined with earlier reported studies gives mean declination of 97{{}°} and mean inclination of - 79{{}°} (k=55, α_{95}=3{{}°}) with a paleopole at 15{{}°}N, 57{{}°}E (dp=5{{}°}, dm=6{{}°}). Paleogeographical position for the Dharwar craton at ˜ 2367 Ma suggests that there may be a chance to possible spatial link between Dharwar dykes of Dharwar craton (India), Widgemooltha and Erayinia dykes of Yilgarn craton (Australia), Sebanga Poort Dykes of Zimbabwe craton (Africa) and Karelian

  6. Synthesis and structure of a new layered oxyfluoride Sr{sub 2}ScO{sub 3}F with photocatalytic property

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yongkun; Tang, Kaibin, E-mail: kbtang@ustc.edu.cn; Zhu, Baichuan; Wang, Dake; Hao, Qiaoyan; Wang, Yan

    2015-05-15

    Highlights: • A new oxyfluoride compound Sr{sub 2}ScO{sub 3}F was prepared by a solid state route. • The structure of this compound was determined by GSAS program based on XRD data. • The photocatalytic property was investigated under UV irradiation. - Abstract: A new Ruddlesden–Popper type scandium oxyfluoride, Sr{sub 2}ScO{sub 3}F, was synthesized by a conventional solid state reaction route. The detailed structure of Sr{sub 2}ScO{sub 3}F was investigated using X-ray diffraction (XRD) and selected area electron diffraction (SAED). The disorder distribution pattern of fluorine anions was determined by the {sup 19}F nuclear magnetic resonance (NMR) spectrum. The compound crystallizes in a K{sub 2}NiF{sub 4}-type tetragonal structure (space group I4/mmm) with O/F anions disordered over the apical sites of the perovskite-type Sc(O,F){sub 6} octahedron layers interleaved with strontium cations. Ultraviolet–visible (UV–vis) diffuse reflection spectrum of the prepared Sr{sub 2}ScO{sub 3}F indicates that it has an absorption in the UV–vis region. The photocatalytic activity of Sr{sub 2}ScO{sub 3}F was further investigated, showing an effective photodegradation of Rhodamine-B (RB) within 2 h under UV light irradiation.

  7. 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

  8. Field, geochemistry and Sr-Nd isotopes of the Pan-African granitoids from the Tifnoute Valley (Sirwa, Anti-Atlas, Morocco): a post-collisional event in a metacratonic setting

    Science.gov (United States)

    Toummite, A.; Liegeois, J. P.; Gasquet, D.; Bruguier, O.; Beraaouz, E. H.; Ikenne, M.

    2013-10-01

    In the Tifnoute Valley, three plutonic units have been defined: the Askaoun intrusion, the Imourkhssen intrusion and the Ougougane group of small intrusions. They are made of quartz diorite, granodiorite and granite and all contain abundant mafic microgranular enclaves (MME). The Askaoun granodiorite and the Imourkhssen granite have been dated by LA-ICP-MS on zircon at 558 ± 2 Ma and 561 ± 3 Ma, respectively. These granitic intrusions are subcontemporaneous to the widespread volcanic and volcano-detrital rocks from the Ouarzazate Group (580-545 Ma), marking the post-collisional transtensional period in the Anti-Atlas and which evolved towards alkaline and tholeiitic lavas in minor volume at the beginning of the Cambrian anorogenic intraplate extensional period. Geochemically, the Tifnoute Valley granitoids belong to an alkali-calcic series (high-K calc-alkaline) with typical Nb-Ta negative anomalies and no alkaline affinities. Granitoids and enclaves display positive ɛNd-560Ma (+0.8 to +3.5) with young Nd-TDM between 800 and 1200 Ma and relatively low 87Sr/86Sr initial ratios (Sri: 0.7034 and 0.7065). These values indicate a mainly juvenile source corresponding to a Pan-African metasomatized lithospheric mantle partly mixed with an old crustal component from the underlying West African Craton (WAC). Preservation in the Anti-Atlas of pre-Pan-African lithologies (c. 2.03 Ga basement, c. 800 Ma passive margin greenschist-facies sediments, allochthonous 750-700 Ma ophiolitic sequences) indicates that the Anti-Atlas lithosphere has not been thickened and was never an active margin during the Neoproterozoic. After a transpressive period, the late Ediacaran period (580-545 Ma) is marked by movement on near vertical transtensional faults, synchronous with the emplacement of the huge Ouarzazate Group and the Tifnoute Valley granitoids. We propose here a geodynamical model where the Tifnoute Valley granitoids as well as the Ouarzazate Group were generated during the post

  9. Exploring Moho sharpness in Northeastern North China Craton with frequency-dependence analysis of Ps receiver function

    Science.gov (United States)

    Zhang, P.; Yao, H.; Chen, L.; WANG, X.; Fang, L.

    2017-12-01

    The North China Craton (NCC), one of the oldest cratons in the world, has attracted wide attention in Earth Science for decades because of the unusual Mesozoic destruction of its cratonic lithosphere. Understanding the deep processes and mechanism of this craton destruction demands detailed knowledge about the deep structure of this region. In this study, we calculate P-wave receiver functions (RFs) with two-year teleseismic records from the North China Seismic Array ( 200 stations) deployed in the northeastern NCC. We observe both diffused and concentered PpPs signals from the Moho in RF waveforms, which indicates heterogeneous Moho sharpness variations in the study region. Synthetic Ps phases generated from broad positive velocity gradients at the depth of the Moho (referred as Pms) show a clear frequency dependence nature, which in turn is required to constrain the sharpness of the velocity gradient. Practically, characterizing such a frequency dependence feature in real data is challenging, because of low signal-to-noise ratio, contaminations by multiples generated from shallow structure, distorted signal stacking especially in double-peak Pms signals, etc. We attempt to address these issues by, firstly, utilizing a high-resolution Moho depth model of this region to predict theoretical delay times of Pms that facilitate more accurate Pms identifications. The Moho depth model is derived by wave-equation based poststack depth migration on both Ps phase and surface-reflected multiples in RFs in our previous study (Zhang et al., submitted to JGR). Second, we select data from a major back azimuth range of 100° - 220° that includes 70% teleseismic events due to the uneven data coverage and to avoid azimuthal influence as well. Finally, we apply an adaptive cross-correlation stacking of Pms signals in RFs for each station within different frequency bands. High-quality Pms signals at different frequencies will be selected after careful visual inspection and adaptive

  10. The Re-evaluation of 84Rb decay data

    International Nuclear Information System (INIS)

    Huang Xiaolong; Zhou Chunmei

    1996-01-01

    The 84 Rb is an important radionuclide and its decay data are fundamental data in nuclear applications. The decay data for 84 Rb were re-evaluated. The energies and intensities of γ rays and their internal conversion coefficients, energies and intensities of Auger electrons, conversion electrons and x-rays, were recommended. The decay scheme was also given. The balance of radiation rays intensities and energies was checked. (9 tabs., 2 figs.)

  11. Mechanisms for strain localization within Archaean craton: A structural study from the Bundelkhand Tectonic Zone, north-central India

    Science.gov (United States)

    Sarkar, Saheli; Patole, Vishal; Saha, Lopamudra; Pati, Jayanta Kumar; Nasipuri, Pritam

    2015-04-01

    The transformation of palaeo-continents involve breakup, dispersal and reassembly of cratonic blocks by collisional suturing that develop a network of orogenic (mobile) belts around the periphery of the stable cratons. The nature of deformation in the orogenic belt depends on the complex interaction of fracturing, plastic deformation and diffusive mass transfer. Additionally, the degree and amount of melting during regional deformation is critical as the presence of melt facilitates the rate of diffusive mass transfer and weakens the rock by reducing the effective viscosity of the deformed zone. The nature of strain localization and formation of ductile shear zones surrounding the cratonic blocks have been correlated with Proterozoic-Palaeozoic supercontinent assembly (Columbia, Rodinia and Gondwana reconstruction). Although, a pre-Columbia supercontinent termed as Kenorland has been postulated, there is no evidence that supports the notion due to lack of the presence of shear zones within the Archaean cratonic blocks. In this contribution, we present the detailed structural analysis of ductile shear zones within the Bundelkhand craton. The ductlile shear zone is termed as Bundelkhand Tectonic Zone (BTZ) that extends east-west for nearly 300 km throughout the craton with a width of two-three kilometer . In the north-central India, the Bundelkhand craton is exposed over an area of 26,000 sq. The craton is bounded by Central Indian Tectonic zone in the south, the Great Boundary fault in the west and by the rocks of Lesser Himalaya in the north. A series of tonalite-trondjhemite-granodiorite gneiss are the oldest rocks of the Bundelkhand craton that also contains a succession of metamorphosed supracrustal rocks comprising of banded iron formation, quartzite, calc-silicate and ultramafic rocks. K-feldspar bearing granites intrude the tonalite-trondjhemite-granodiorite and the supracrustal rocks during the time span of 2.1 to 2.5 Ga. The TTGs near Babina, in central

  12. 50 years of the RB reactor utilization

    International Nuclear Information System (INIS)

    Milosevic, M.; Pesic, M.; Ljubenov, V.

    2008-01-01

    This paper is dedicated to the 50 th anniversary of the RB reactor operation, which was the first nuclear reactor built in former Yugoslavia. Information about the construction period, basic technical characteristics and experimental possibilities of the facility, description of first experiments performed 50 years ago, utilisation and modifications done during the implementation of different state nuclear programs and the most important research results are presented in the paper. Role of the RB reactor in the forthcoming decommissioning of the RA research reactor and some plans for future utilisation are underlined also. (author)

  13. Geochemical fingerprinting of ∼2.5 Ga forearc-arc-backarc related magmatic suites in the Bastar Craton, central India

    Science.gov (United States)

    Asthana, Deepanker; Kumar, Sirish; Vind, Aditya Kumar; Zehra, Fatima; Kumar, Harshavardhan; Pophare, Anil M.

    2018-05-01

    The Pitepani volcanic suite of the Dongargarh Supergroup, central India comprises of a calc-alkaline suite and a tholeiitic suite, respectively. The rare earth element (REE) patterns, mantle normalized plots and relict clinopyroxene chemistry of the Pitepani calc-alkaline suite are akin to high-Mg andesites (HMA) and reveal remarkable similarity to the Cenozoic Setouchi HMA from Japan. The Pitepani HMAs are geochemically correlated with similar rocks in the Kotri-Dongargarh mobile belt (KDMB) and in the mafic dykes of the Bastar Craton. The rationale behind lithogeochemical correlations are that sanukitic HMAs represent fore-arc volcanism over a very limited period of time, under abnormally high temperature conditions and are excellent regional and tectonic time markers. Furthermore, the tholeiitic suites that are temporally and spatially associated with the HMAs in the KDMB and in the mafic dykes of the Bastar Craton are classified into: (a) a continental back-arc suite that are depleted in incompatible elements, and (b) a continental arc suite that are more depleted in incompatible elements, respectively. The HMA suite, the continental back-arc and continental arc suites are lithogeochemically correlated in the KDMB and in the mafic dykes of the Bastar Craton. The three geochemically distinct Neoarchaean magmatic suites are temporally and spatially related to each other and to an active continental margin. The identification of three active continental margin magmatic suites for the first time, provides a robust conceptual framework to unravel the Neoarchaean geodynamic evolution of the Bastar Craton. We propose an active continental margin along the Neoarchaen KDMB with eastward subduction coupled with slab roll back or preferably, ridge-subduction along the Central Indian Tectonic Zone (CITZ) to account for the three distinct magmatic suites and the Neoarchean geodynamic evolution of the Bastar Craton.

  14. Decay of84fRb

    International Nuclear Information System (INIS)

    Passaro, A.M.P.

    1987-01-01

    For the first time, low intensity beta ramifications were determined in the decay of 84 Rb to 84 Kr. The methodology and apparatus employed are presented as well as the advantages and experimental array. (A.C.A.S.) [pt

  15. Herbarium collection of the Rio de Janeiro Botanical Garden (RB), Brazil.

    Science.gov (United States)

    Lanna, João M; da Silva, Luís Alexandre E; Morim, Marli P; Leitman, Paula M; Queiroz, Natália O; Filardi, Fabiana L R; Dalcin, Eduardo C; Oliveira, Felipe A; Forzza, Rafaela C

    2018-01-01

    This paper provides a quantitative and general description of the Rio de Janeiro Botanical Garden herbarium (RB) dataset. Created over a century ago, the RB currently comprises ca. 750,000 mounted specimens, with a strong representation of Brazilian flora, mainly from the Atlantic and Amazon forests. Nearly 100% of these specimens have been entered into the database and imaged and, at present, about 17% have been geo-referenced. This data paper is focused exclusively on RB's exsiccatae collection of land plants and algae, which is currently increasing by about twenty to thirty thousand specimens per year thanks to fieldwork, exchange and donations. Since 2005, many national and international projects have been implemented, improving the quality and accessibility of the collection. The most important facilitating factor in this process was the creation of the institutional system for plants collection and management, named JABOT. Since the RB is continuously growing, the dataset is updated weekly on SiBBr and GBIF portals. The most represented environments are the Atlantic and Amazon forests, a biodiversity hotspot and the world's largest rain forest, respectively. The dataset described in this article contains the data and metadata of plants and algae specimens in the RB collection and the link to access the respective images. Currently, the RB data is publicly available online at several biodiversity portals, such as our institutional database JABOT, the Reflora Virtual Herbarium, the SiBBr and the GBIF portal. However, a description of the RB dataset as a whole is not available in the literature.

  16. Herbarium collection of the Rio de Janeiro Botanical Garden (RB), Brazil

    Science.gov (United States)

    da Silva, Luís Alexandre E; Morim, Marli P.; Leitman, Paula M.; Queiroz, Natália O.; Filardi, Fabiana L. R.; Dalcin, Eduardo C.; Oliveira, Felipe A.

    2018-01-01

    Abstract Background This paper provides a quantitative and general description of the Rio de Janeiro Botanical Garden herbarium (RB) dataset. Created over a century ago, the RB currently comprises ca. 750,000 mounted specimens, with a strong representation of Brazilian flora, mainly from the Atlantic and Amazon forests. Nearly 100% of these specimens have been entered into the database and imaged and, at present, about 17% have been geo-referenced. This data paper is focused exclusively on RB's exsiccatae collection of land plants and algae, which is currently increasing by about twenty to thirty thousand specimens per year thanks to fieldwork, exchange and donations. Since 2005, many national and international projects have been implemented, improving the quality and accessibility of the collection. The most important facilitating factor in this process was the creation of the institutional system for plants collection and management, named JABOT. Since the RB is continuously growing, the dataset is updated weekly on SiBBr and GBIF portals. New information The most represented environments are the Atlantic and Amazon forests, a biodiversity hotspot and the world's largest rain forest, respectively. The dataset described in this article contains the data and metadata of plants and algae specimens in the RB collection and the link to access the respective images. Currently, the RB data is publicly available online at several biodiversity portals, such as our institutional database JABOT, the Reflora Virtual Herbarium, the SiBBr and the GBIF portal. However, a description of the RB dataset as a whole is not available in the literature. PMID:29674937

  17. Relative volatility of dilute solutions of Rb-Cs system

    International Nuclear Information System (INIS)

    Gromov, P.B.; Izotov, V.P.; Nisel'son, L.A.

    1984-01-01

    Relative volatility of diluted solutions Rb-Cs in the temperature range 650-820 K and pressures 13-200 gPa has been studied. The system Rb-Cs in the range of diluted solutions obeys the Henry law. It is shown, that liquid-vapour equilibrium in diluted solutions of cesium in rubidium is characterized by negative deviation from perfection

  18. Optimization of 90Sr/89Sr measurements

    Directory of Open Access Journals (Sweden)

    Legarda F.

    2012-04-01

    Full Text Available One of the key points in the double measurement method for the measurement of both, 89Sr and 90Sr, by using a proportional counter is the choice of the times at which the measurements should be done. In this paper, the formulae to calculate the 89Sr and 90Sr detection limits in conditions of radioactive equilibrium between 90Y and 90Sr are derived, and an analysis of them as a function of the time between the two measurements is done. The choice for the time of the second measurement is going to depend on the desired quality of the results to be obtained.

  19. Penning-trap mass spectrometry of radioactive, highly charged ions. Measurements of neutron-rich Rb and Sr nuclides for nuclear astrophysics and development of a novel Penning trap for cooling highly charged ions

    International Nuclear Information System (INIS)

    Simon, Vanessa Veronique

    2012-01-01

    High-precision atomic mass measurements are vital for the description of nuclear structure, investigations of nuclear astrophysical processes, and tests of fundamental symmetries. The neutron-rich A ∼ 100 region presents challenges for modeling the astrophysical r-process because of sudden nuclear shape transitions. This thesis reports on high-precision masses of short-lived neutron-rich 94,97,98 Rb and 94,97-99 Sr isotopes using the TITAN Penning-trap mass spectrometer at TRIUMF. The isotopes were charge-bred to q = 15+; uncertainties of less than 4 keV were achieved. Results deviate by up to 11σ compared to earlier measurements and extend the region of nuclear deformation observed in the A∼100 region. A parameterized r-process model network calculation shows that mass uncertainties for the elemental abundances in this region are now negligible. Although beneficial for the measurement precision, the charge breeding process leads to an increased energy spread of the ions on the order of tens of eV/q. To eliminate this drawback, a Cooler Penning Trap (CPET) has been developed as part of this thesis. The novel multi-electrode trap structure of CPET forms nested potentials to cool HCI sympathetically using either electrons or protons to increase the overall efficiency and precision of the mass measurement. The status of the off-line setup and initial commissioning experiments are presented.

  20. A novel procedure for Rubidium separation and its isotope measurements on geological samples by MC-ICP-MS

    Science.gov (United States)

    Ma, J.; Zhang, Z.; Wei, G.; Zhang, L.

    2017-12-01

    A method including a novel column Rb separation procedure and high-precision Rb isotope measurement in geological materials by using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) in standard-sample-bracketing (SSB) mode has been developed. Sr-Spec resin was employed, in which the distribution coefficients for Rb, K, Ba and Sr are different in nitric acid, to sequentially separate them from the matrix. The dissolved samples were loaded on the column in 3 M HNO3, the main matrix such as Al, Ca, Fe, Mg, Mn and Na were removed by rinsing with 4.5 mL HNO3, Rb and K were then sequentially eluted by 3 M HNO3 in different volumes. After that, Ba was eluted by 8 M HNO3, and Sr was finally eluted by Milli-Q water. This enable us to collect the pure Rb, K, Ba and Sr one by one with recovery close to 100% for their isotopic compositions measurement on MC-ICP-MS. We here focus on Rb isotope measurement. The measurement using MC-ICP-MS yielded an internal precision for δ87Rb of external precision was generally better than ± 0.06‰ (2SD) based on the long-term results of the Rb standard solutions NIST SRM 984. A series of geological rock standards, were analyzed using this method, and the results indicate significant Rb isotope differences in different geologic materials. This will provide a powerful tool to investigate Rb isotope fractionation during geological processes.Based on this method, Rb isotope compositions from a basaltic weathering profile were carried out. The data show the lighter Rb (85Rb) isotope is preferentially leached from the weathering profile and remains heavy Rb isotope (87Rb) in the weathered residues during the incipient weathering stage. From the moderate to advanced weathering stage, the significant variations of Rb isotope were observed and multiple factors, such as leaching, adsorption, desorption, and precipitation, should play important role in fractionating Rb isotope.

  1. Sorption of radiostrontium from liquid metallic rubidium

    International Nuclear Information System (INIS)

    Zhujkov, B.L.; Kokhnyuk, V.M.; Vincent, J.S.

    2008-01-01

    One studied the radiostrontium (in particular, 82 Sr) sorption from the liquid metallic Rb in various inorganic sorbents (both metals and oxides). One studied the temperature dependence and the dynamics of the adsorption and put forward an interpretation of the observed mechanisms. The elaborated approach enables to extract 82 Sr efficiently from the Rb targets upon their irradiation by the accelerated protons. One studies various procedures and the applicability of the process to ensure elaboration of a new highly efficient process to produce 82 Sr, in particular, with the targets of the circulating Rb [ru

  2. Review of accident analyses of RB experimental reactor

    International Nuclear Information System (INIS)

    Pesic, M.

    2003-01-01

    The RB reactor is a uranium fuel heavy water moderated critical assembly that has been put and kept in operation by the VINCA Institute of Nuclear Sciences, Belgrade, Serbia and Montenegro, since April 1958. The first complete Safety Analysis Report of the RB reactor was prepared in 1961/62; yet, the first accident analysis had been made in late 1958 with the aim to examine a power transition and the total equivalent doses received by the staff during the reactivity accident that occurred on October 15, 1958. Since 1960, the RB reactor has been modified a few times. Beside the initial natural uranium metal fuel rods, new types of fuel (TVR-S types of Russian origin) consisting of 2% enriched uranium metal and 80% enriched U0 2 , dispersed in aluminum matrix, have been available since 1962 and 1976, respectively. Modifications of the control and safety systems of the reactor were made occasionally. Special reactor cores were designed and constructed using all three types of fuel elements, as well as the coupled fast-thermal ones. The Nuclear Safety Committee of the VINCA Institute, an independent regulator)' body, approved for usage all these modifications of the RB reactor on the basis of the Preliminary Safety' Analysis Reports, which, beside proposed technical modifications and new regulation rules, included safety analyses of various possible accidents. A special attention was given (and a new safety methodology was proposed) to thorough analyses of the design-based accidents related to the coupled fast-thermal cores that included central zones of the reactor filled by the fuel elements without any moderator. In this paper, an overview of some accidents, methodologies and computation tools used for the accident analyses of the RB reactor is given. (author)

  3. Some Examples of Accident Analyses for RB Reactor

    International Nuclear Information System (INIS)

    Pesic, M.

    2002-01-01

    The RB reactor is heavy water critical assembly operated in the Vinca Institute of Nuclear Sciences, Belgrade, Yugoslavia, since April 1959. The first Safety Analysis Report of the RB critical assembly was prepared in 1961/62. But, the first accidental analysis was done in late 1958 in aim the examine power transient and total equivalent doses received by the staff during the reactivity accident occurred on October 15, 1958. Since 1960, the RB reactor is modified few times. Beside initial natural uranium metal fuel rods, new fuel (TVR-S types) from 2% enriched metal uranium and 80% enriched UO 2 were available since 1962 and 1976, respectively. Also, modifications in control and safety systems of the reactor were done occasionally. Special reactor cores were created using all three types of fuel elements, among them, the coupled fast-thermal ones. Nuclear Safety Committee of the Vinca Institute, an independent regulatory body approved for usage all these modifications of the RB reactor. For those decisions of the Committee, the Preliminary Safety Analysis Reports were prepared that, beside proposed technical modifications and new regulation rules had included analyses of various possible accidents. Special attention is given and new methodology was proposed for thoroughly analyses of design based accidents related to coupled fast-thermal cores, that include reactor central zones filled by fuel elements without moderator. In these accidents, during assumed flooding of the fast zone by moderator, a very high reactivity could be inserted in the system with very high reactivity rate. It was necessary to provide that the safety system of the reactor had fast response to that accident and had enough high (negative) reactivity to shut down the reactor timely. In this paper, a brief overview of some accidents, methodology and computation tools used for the accident analyses at RB reactor are given. (author)

  4. Review of accident analyses of RB experimental reactor

    Directory of Open Access Journals (Sweden)

    Pešić Milan P.

    2003-01-01

    Full Text Available The RB reactor is a uranium fuel heavy water moderated critical assembly that has been put and kept in operation by the VTNCA Institute of Nuclear Sciences, Belgrade, Serbia and Montenegro, since April 1958. The first complete Safety Analysis Report of the RB reactor was prepared in 1961/62 yet, the first accident analysis had been made in late 1958 with the aim to examine a power transition and the total equivalent doses received by the staff during the reactivity accident that occurred on October 15, 1958. Since 1960, the RB reactor has been modified a few times. Beside the initial natural uranium metal fuel rods, new types of fuel (TVR-S types of Russian origin consisting of 2% enriched uranium metal and 80% enriched UO2 dispersed in aluminum matrix, have been available since 1962 and 1976 respectively. Modifications of the control and safety systems of the reactor were made occasionally. Special reactor cores were designed and constructed using all three types of fuel elements as well as the coupled fast-thermal ones. The Nuclear Safety Committee of the VINĆA Institute, an independent regulatory body, approved for usage all these modifications of the RB reactor on the basis of the Preliminary Safety Analysis Reports, which, beside proposed technical modifications and new regulation rules, included safety analyses of various possible accidents. A special attention was given (and a new safety methodology was proposed to thorough analyses of the design-based accidents related to the coupled fast-thermal cores that included central zones of the reactor filled by the fuel elements without any moderator. In this paper, an overview of some accidents, methodologies and computation tools used for the accident analyses of the RB reactor is given.

  5. Electronic properties and surface reactivity of SrO-terminated SrTiO3 and SrO-terminated iron-doped SrTiO3.

    Science.gov (United States)

    Staykov, Aleksandar; Tellez, Helena; Druce, John; Wu, Ji; Ishihara, Tatsumi; Kilner, John

    2018-01-01

    Surface reactivity and near-surface electronic properties of SrO-terminated SrTiO 3 and iron doped SrTiO 3 were studied with first principle methods. We have investigated the density of states (DOS) of bulk SrTiO 3 and compared it to DOS of iron-doped SrTiO 3 with different oxidation states of iron corresponding to varying oxygen vacancy content within the bulk material. The obtained bulk DOS was compared to near-surface DOS, i.e. surface states, for both SrO-terminated surface of SrTiO 3 and iron-doped SrTiO 3 . Electron density plots and electron density distribution through the entire slab models were investigated in order to understand the origin of surface electrons that can participate in oxygen reduction reaction. Furthermore, we have compared oxygen reduction reactions at elevated temperatures for SrO surfaces with and without oxygen vacancies. Our calculations demonstrate that the conduction band, which is formed mainly by the d-states of Ti, and Fe-induced states within the band gap of SrTiO 3 , are accessible only on TiO 2 terminated SrTiO 3 surface while the SrO-terminated surface introduces a tunneling barrier for the electrons populating the conductance band. First principle molecular dynamics demonstrated that at elevated temperatures the surface oxygen vacancies are essential for the oxygen reduction reaction.

  6. Low-dose myocardial blood flow imaging using 82Rb-PET (RUBILOW 2.0)

    DEFF Research Database (Denmark)

    Hoff, Camilla Molich; Tolbod, Lars Poulsen; Harms, Hans

    2017-01-01

    Aim: Relative and absolute measures of myocardial blood flow (MBF) can be derived from a 82Rb PET/CT scan using list mode data to extract static, gated and dynamic PET series. High doses of 82Rb are used to maximize image quality in especially static images. High doses require large eluate volumes......, may degrade scanner dead time performance at first pass and decreases generator lifetime. Lower doses will expand the availability of 82Rb PET/CT and lower doses to personnel and patients. The aim of the current study was to examine MBF with a low dose (LD) 82Rb protocol compared to the institution......’s standard (STD) protocol. Methods: Twenty-one patients referred to 82Rb PET were included in the study. Patients were examined during rest and stress with repeated LD (740 MBq) and STD dose (1110 MBq) Rb-PET during the same imaging session. Regional and global rest and stress MBF values, total perfusion...

  7. Magmatism during the accretion of the late Archaean Dharwar Craton (South India): sanukitoids and related rocks in their geological context.

    Science.gov (United States)

    Moyen, J.-F.; Martin, H.; Jayananda, M.; Peucat, J.-J.

    2003-04-01

    The South Indian Dharwar Craton assembled during the late-Archaean (ca. 2.5 Ga). This event was associated with intense granite genesis and emplacement. Based on petrography and geochemistry, 4 main types of late Archaean granitoids were distinguished: (1) Anatectic granites (and diatexites), formed by partial melting of TTG gneisses; (2) Classical TTGs; (3) Sanukitoids, generated by interaction between slab melts (TTG) and mantle peridotite; (4) The high HFSE Closepet granite, interpreted as derived from partial melting of a mantle metasomatized by slab melts (TTG). While the 3 later groups all are interpreted as resulting from slab melt/mantle wedge interactions, their differences are related to decreasing felsic melt/peridotite ratios during the ascent “slab melts” in the mantle wedge above an active subduction zone. Field data together with geochronology and isotope geochemistry allow to subdivide the Dharwar craton into three main domains: (1) The Western Dharwar Craton (WDC) is an old (3.3 2.9 Ga ), stable continental block with limited amounts of 2.5 Ga old anatectic granites. (2) The Eastern Dharwar Craton (EDC) is subdivided into two parts: (2a) West of Kolar Schist Belt, a region of 3.0-2.7 Ga old basement intruded by 2.5 Ga old anatectic granites; (2b) East of Kolar, an area featuring mainly 2.5 Ga old diatexites and granites, derived of partial melting of a newly accreted TTG crust. Anatectic granites are ubiquitous, and late in the cratonic evolution; they witnessed generalized melting of a juvenile crust. In contrast, deep-originated granites emplaced before this melting and are restricted to the boundaries between the blocks. This structure of distinct terranes separated by narrow bands operating as channels for deep-originated magmas provides independent evidences for a two-stage evolution: an arc accretion context for the TTG, sanukitoids and related rocks, immediately followed by high temperature reworking of the newly accreted craton

  8. The Amazonian Craton and its influence on past fluvial systems (Mesozoic-Cenozoic, Amazonia)

    NARCIS (Netherlands)

    Hoorn, C.; Roddaz, M.; Dino, R.; Soares, E.; Uba, C.; Ochoa-Lozano, D.; Mapes, R.; Hoorn, C.; Wesselingh, F.P.

    2010-01-01

    The Amazonian Craton is an old geological feature of Archaean/Proterozoic age that has determined the character of fluvial systems in Amazonia throughout most of its past. This situation radically changed during the Cenozoic, when uplift of the Andes reshaped the relief and drainage patterns of

  9. Contrasted continental rifting via plume-craton interaction : Applications to Central East African Rift

    NARCIS (Netherlands)

    Koptev, Alexander; Burov, Evgueni; Calais, Eric; Leroy, Sylvie; Gerya, Taras; Guillou-Frottier, Laurent; Cloetingh, Sierd

    The East African Rift system (EARS) provides a unique system with the juxtaposition of two contrasting yet simultaneously formed rift branches, the eastern, magma-rich, and the western, magma-poor, on either sides of the old thick Tanzanian craton embedded in a younger lithosphere. Data on the

  10. Gravity Data Interpretation in the Northern Edge of the Congo Craton, South-Cameroon

    Directory of Open Access Journals (Sweden)

    James Derek Fairhead

    2010-01-01

    Full Text Available Gravity data in the southern Cameroon are interpreted to better understand the organization of underlying structuresthroughout the northern edge of the Congo craton. The Bouguer anomaly maps of the region are characterized by an elongated trending trending negative gravity anomaly which correspond to a collapsed structure associated with a granitic intrusion beneath the cente center of the region r of the region of the region and limited by fault systems. �e applied 3�D gravity modelling and inversion in order to obtain the 3D density structure of the area. Our result demonstrated that observed gravity anomalies in the region are associated to tectonic structures in the subsurface. The resulting model agrees with the hypothesis of the existence of a major continental collision zone between the Congo Craton and the Pan�African belt. The presence of deep granulites structures in the northern part of the region expresses a continental collision.

  11. Accurate 3He polarimetry using the Rb Zeeman frequency shift due to the Rb-3He spin-exchange collisions

    International Nuclear Information System (INIS)

    Romalis, M.V.; Cates, G.D.

    1998-01-01

    We describe a method of 3 He polarimetry relying on the polarization-dependent frequency shift of the Rb Zeeman resonance. Our method is ideally suited for on-line measurements of the 3 He polarization produced by spin-exchange optical pumping. To calibrate the frequency shift we performed an accurate measurement of the imaginary part of the Rb- 3 He spin-exchange cross section in the temperature range typical for spin-exchange optical pumping of 3 He. We also present a detailed study of possible systematic errors in the frequency shift polarimetry. copyright 1998 The American Physical Society

  12. 1.60 Ga felsic volcanic blocks in the moraines of the Terre Adelie Craton, Antarctica: comparisons with the Gawler Range Volcanics, South Australia

    International Nuclear Information System (INIS)

    Peucat, J.J.; Capdevila, R.; Pecora, L.; Fanning, C.M.; Testut, L.

    2002-01-01

    Rhyodacite and rhyolite blocks found in numerous moraines on the Terre Adelie Craton in Antarctica are samples of a high-temperature high-K calc-alkaline to alkali-calcic igneous suite emplaced at ca 1.60Ga. They comprise lavas and pyroclastic rocks, including ignimbritic varieties, chemically representative of anorogenic and post-orogenic igneous suites. The eruptive centres are probably close to the coast according to radar satellite images that show the trace of the ice streams. The volcanic suite is similar in age, petrography and chemical composition (major and trace elements as well as Nd isotopes) to the Gawler Range Volcanics from the Gawler Craton of South Australia. These similarities strengthen correlations previously established between the Gawler Craton and the Terre Adelie Craton (Mawson Continent). Moreover, the present petrological, geochemical and geochronological data give a new insight into the last major thermal event affecting the Mawson Continent. The results also highlight the useful contribution of moraines to our knowledge of Antarctic geology. Copyright (2002) Geological Society of Australia

  13. A measurement of Rb using mutually exclusive tags

    Science.gov (United States)

    Barate, R.; Buskulic, D.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Lucotte, A.; Minard, M.-N.; Nief, J.-Y.; Pietrzyk, B.; Casado, M. P.; Chmeissani, M.; Comas, P.; Crespo, J. M.; Delfino, M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Juste, A.; Martinez, M.; Miquel, R.; Mir, Ll. M.; Orteu, S.; Padilla, C.; Park, I. C.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Gelao, G.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Alemany, R.; Becker, U.; Bazarko, A. O.; Bright-Thomas, P.; Cattaneo, M.; Cerutti, F.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Harvey, J.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Lutters, G.; Mato, P.; Minten, A.; Moneta, L.; Pacheco, A.; Pusztaszeri, J.-F.; Ranjard, F.; Rensing, P.; Rizzo, G.; Rolandi, L.; Schlatter, D.; Schmitt, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Wachsmuth, H.; Wagner, A.; Ajaltouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Ferdi, C.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rosnet, P.; Rossignol, J.-M.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Rensch, B.; Wäänänen, A.; Daskalakis, G.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Focardi, E.; Parrini, G.; Zachariadou, K.; Corden, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Casper, D.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Scarr, J. M.; Smith, K.; Teixeira-Dias, P.; Thompson, A. S.; Thomson, E.; Thomson, F.; Turnbull, R. M.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Schmidt, M.; Sommer, J.; Tittel, K.; Werner, S.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Girone, M.; Goodsir, S.; Martin, E. B.; Moutoussi, A.; Nash, J.; Sedgbeer, J. K.; Stacey, A. M.; Williams, M. D.; Dissertori, G.; Ghete, V. M.; Girtler, P.; Kuhn, D.; Rudolph, G.; Betteridge, A. P.; Bowdery, C. K.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Sloan, T.; Williams, M. I.; Galla, A.; Giehl, I.; Greene, A. M.; Hoffmann, C.; Jakobs, K.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Coyle, P.; Diaconu, C.; Etienne, F.; Konstantinidis, N.; Leroy, O.; Motsch, F.; Payre, P.; Rousseau, D.; Talby, M.; Sadouki, A.; Thulasidas, M.; Trabelsi, K.; Aleppo, M.; Ragusa, F.; Berlich, R.; Blum, W.; Brown, D.; Büscher, V.; Dietl, H.; Dydak, F.; Ganis, G.; Gotzhein, C.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; St. Denis, R.; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Chen, S.; Choi, Y.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Höcker, A.; Jacholkowska, A.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Nilolic, I.; Schune, M.-H.; Simion, S.; Tournefier, E.; Veillet, J.-J.; Videau, I.; Zerwas, D.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; dell'Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Vannini, C.; Venturi, A.; Verdini, P. G.; Blair, G. A.; Bryant, L. M.; Chambers, J. T.; Gao, Y.; Green, M. G.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Maley, P.; Norton, P. R.; Thompson, J. C.; Wright, A. E.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Perez, P.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Black, S. N.; Dann, J. H.; Johnson, R. P.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Kelly, M. S.; Lehto, M.; Newton, W. M.; Reeve, J.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Cowan, G.; Grupen, C.; Saraiva, P.; Smolik, L.; Stephan, F.; Apollonio, M.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Charles, E.; Elmer, P.; Ferguson, D. P. S.; Gao, Y. S.; González, S.; Greening, T. C.; Hayes, O. J.; Hu, H.; Jin, S.; McNamara, P. A.; Nachtman, J. M.; Nielsen, J.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Scott, I. J.; Walsh, J.; Sau, Lan Wu; Wu, X.; Yamartino, J. M.; Zobernig, G.

    1997-02-01

    A measurement of Rb using five mutually exclusive hemisphere tags has been performed by ALEPH using the full LEP1 statistics. Three tags are designed to select the decay of the Z0 to b quarks, while the remaining two selectZ0 decays to c and light quarks, and are used to measure the tagging efficiencies. The result, Rb = 0.2159 +/- 0.0009 (stat) +/- 0.0011 (syst), is in agreement with the electroweak theory prediction of 0.2158 +/- 0.0003.

  14. Grain size effect on Sr and Nd isotopic compositions in eolian dust. Implications for tracing dust provenance and Nd model age

    International Nuclear Information System (INIS)

    Feng Jinliang; Zhu Liping; Zhen Xiaolin; Hu Zhaoguo

    2009-01-01

    Strontium (Sr) and neodymium (Nd) isotopic compositions enable identification of dust sources and reconstruction of atmospheric dispersal pathways. The Sr and Nd isotopic compositions in eolian dust change systematically with grain size in ways not yet fully understood. This study demonstrates the grain size effect on the Sr and Nd isotopic compositions in loess and 2006 dust fall, based on analyses of seven separated grain size fractions. The analytical results indicate that Sr isotopic ratios strongly depend on the grain size fractions in samples from all types of eolian dust. In contrast, the Nd isotopic ratios exhibit little variation in loess, although they vary significantly with grain size in samples from a 2006 dust fall. Furthermore, Nd model ages tend to increase with increasing grain size in samples from all types of eolian dust. Comparatively, Sr isotopic compositions exhibit high sensitively to wind sorting, while Nd isotopic compositions show greater sensitively to dust origin. The principal cause for the different patterns of Sr and Nd isotopic composition variability with grain size appears related to the different geochemical behaviors between rubidium (Rb) and Sr, and the similar geochemical behaviors between samarium (Sm) and Nd. The Nd isotope data indicate that the various grain size fractions in loess have similar origins for each sample. In contrast, various provenance components may separate into different grain size fractions for the studied 2006 dust fall. The Sr and Nd isotope compositions further confirm that the 2006 dust fall and Pleistocene loess in Beijing have different sources. The loess deposits found in Beijing and those found on the Chinese Loess Plateau also derive from different sources. Variations between Sr and Nd isotopic compositions and Nd model ages with grain size need to be considered when directly comparing analyses of eolian dust of different grain size. (author)

  15. An Integrated Geochronological, Petrological, Geochemical and Paleomagnetic Study of Paleoproterozoic and Mesoproterozoic Mafic Dyke Swarms in the Nain Craton, Labrador

    Science.gov (United States)

    Sahin, Tugce

    The Nain craton comprises the western, Labrador segment of the larger North Atlantic craton (NAC) which exposes Early through Late Archean gneisses. The NAC is bounded on all sides by Paleoproterozoic collisional orogens that involved either considerable structural reworking (Torngat-Nagssugtoqidian-Lewisian) or the accretion of juvenile arc magmas (Ketilidian-Makkovik). The NAC remains poorly understood compared to other Archean crustal blocks now dispersed globally. Compounding this problem is a lack of reliable paleomagnetic poles for NAC units that predate its assembly into the supercontinent Laurentia by ca. 1800 Ma, which could be used to test neighboring relationships with other cratonic fragments. In order to understand the history of the NAC as part of a possible, larger supercontinent, the record of mafic dyke swarms affecting the craton, particularly those that postdate the Late Archean terrane assembly, were examined in this study. Diabase or gabbroic dyke swarms are invaluable in such studies because their geometries offer possible locus points, they often have a punctuated emplacement and precisely datable crystallization histories, and they have cooling histories and oxide mineralogy amenable to recovering robust paleopoles. Coastal Labrador exposes a number of mafic dykes, some of which are demonstrably Paleoproterozoic (e.g. 2235 Ma Kikkertavak dykes; 2121 Ma Tikkigatsiagak dykes) or Mesoproterozoic (e.g. 1280-1270 Ma Nain and Harp dykes) in age (U-Pb; baddeleyite or zircon). The southern half of the Nain craton (Hopedale block) in particular preserves a rich array of mafic dykes. Dyke cross-cutting relationships are numerous and relatively well exposed, permitting multiple opportunities for paleomagnetic field tests (e.g. baked contact). The results presented here allow understanding of the tectonic evolution of the NAC with implications for strengthened Labrador-Greenland correlations, and testing possible Paleoproterozoic supercontinent

  16. Interpretation of the CABRI-RAFT RB1 and RB2 tests through detailed data evaluation and PAPAS-2S code analysis

    International Nuclear Information System (INIS)

    Fukano, Yoshitaka; Sato, Ikken

    2001-08-01

    The CABRI-RAFT RB1 and RB2 tests were aiming at a study on impact of fuel pin failure under an overpower condition leading to fuel melting. Using a special technique, combination of through-cladding failure and fuel melting was realized. In the RB1 test, fuel ejection was prevented under a limited fuel melting condition. On the other hand, significant fuel melting was applied in the RB2 test so as to get the fuel ejection, thereby obtaining information on the fuel ejection behavior. Interpretation for these tests through the detailed experimental data evaluation and the PAPAS-2S code analysis is performed in this study. Through this study, it is indicated that molten fuel ejection can be prevented with the low smear density fuel as far as the fuel melting is not large for a slit-type cladding defect. Fuel ejection becomes possible in the case of significant fuel melting with a very thin solid fuel shell surrounding the molten fuel cavity. However, the rapidness of the fuel ejection with the low smear density fuel is less pronounced compared with that of the high smear density fuel. It is also confirmed that there is considerable DN-precursor release into the coolant flow already before fuel ejection. The result is very useful for evaluation of anomaly detection with DN signal observation. (author)

  17. Petrography and geochronology of the Sao Jose dos Quatro Marcos granitoids, southwestern Mato Grosso, Brazil

    International Nuclear Information System (INIS)

    Carneiro, M.A.; Ulbrich, H.H.G.J.; Kawashita, K.

    1989-01-01

    An area of about 400Km 2 was mapped in the region of Sao Jose dos Quatro Marcos, southwestern State of Mato Grosso, western Brazil. Various granitoid rocks were recognized, intrusive into basement gneisses, and mapped as two distinct units, one of massive late granitoids (mostly 3a and 3b granites) and one of foliated granitoids, with oriented mafic minerals, consisting mainly of tonalites and, to a lesser degree, of granodiorites. The sequence of intrusion is from tonalites to granodiorites to late granites. Magmatic textures are usually preserved in the rocks, with the exception of some clearly recrystallized samples. Field aspects, as well as petrography and mineralogy, suggest a genetic relationship between the various granitoid types, showing overall features commonly cited as typical of 'I' lineages. A Rb/Sr whole-rock isochron obtained from 3b granites (six points) shows an age of 1,472 +- 19 Ma, and Sr 87 86 initial ratio of 0.7037 +- 0.0004; a nine point isochron (adding two tonalites and one granodiorite) yelds similar results (age of 1,505 +- 20 Ma, initial ratio of 0.7029+- 0.0003). The obtained ages confirm the existence of a thermal-magmatic event at about 1,500 Ma at the southern border of the Amazon Craton. (author) [pt

  18. Probing the structural and electronic properties of cationic rubidium-gold clusters: [AunRb]+ (n = 1-10)

    Science.gov (United States)

    Zhao, Ya-Ru; Zhang, Hai-Rong; Qian, Yu; Duan, Xu-Chao; Hu, Yan-Fei

    2016-03-01

    Density functional theory has been applied to study the geometric structures, relative stabilities, and electronic properties of cationic [AunRb]+ and Aun + 1+ (n = 1-10) clusters. For the lowest energy structures of [AunRb]+ clusters, the planar to three-dimensional transformation is found to occur at cluster size n = 4 and the Rb atoms prefer being located at the most highly coordinated position. The trends of the averaged atomic binding energies, fragmentation energies, second-order difference of energies, and energy gaps show pronounced even-odd alternations. It indicated that the clusters containing odd number of atoms maintain greater stability than the clusters in the vicinity. In particular, the [Au6Rb]+ clusters are the most stable isomer for [AunRb]+ clusters in the region of n = 1-10. The charges in [AunRb]+ clusters transfer from the Rb atoms to Aun host. Density of states revealed that the Au-5d, Au-5p, and Rb-4p orbitals hardly participated in bonding. In addition, it is found that the most favourable channel of the [AunRb]+ clusters is Rb+ cation ejection. The electronic localisation function (ELF) analysis of the [AunRb]+ clusters shown that strong interactions are not revealed in this study.

  19. Research Project 'RB research nuclear reactor' (operation and maintenance), Final report

    International Nuclear Information System (INIS)

    1985-01-01

    This final report covers operation and maintenance activities at the RB reactor during period from 1981-1985. First part covers the RB reactor operation, detailed description of reactor components, fuel, heavy water, reactor vessel, cooling system, equipment and instrumentation, auxiliary systems. It contains data concerned with dosimetry and radiation protection, reactor staff, and financial data. Second part deals maintenance, regular control and testing of reactor equipment and instrumentation. Third part is devoted to basic experimental options and utilization of the RB reactor including training

  20. Neutron converter at reactor RB; Konvertor neutrona na reaktoru RB

    Energy Technology Data Exchange (ETDEWEB)

    Strugar, P; Sotic, P; Ninkovic, M; Pesic, M [Boris Kidric Institute of nuclear sciences, Vinca, Belgrade (Yugoslavia)

    1977-07-01

    A neutron converter at Reactor RB in the 'Boris Kidric' Institute of Nuclear Sciences - Vinca has been constructed. Preliminary measurements have been shown that the converted neutron spectrum is very similar to the fission neutron spectrum. For the same integral reactor power, the measured neutron radiation dose has been for about ten times larger with the neutron converter. The neutron converter offers wide possibilities, as in investigations in the reactor physics, where the fission neutron spectra have been required, as well as in the field of neutron dosimetry and biological irradiations (author)

  1. The Strontium Fingerprint and Footprint: Using 87Sr/86Sr to Find the Sources and Range of Architectural Timber Acquisition of Great House Construction at Chaco Canyon, New Mexico

    Science.gov (United States)

    English, N. B.; Reynolds, A. C.; Quade, J.; Betancourt, J. L.

    2006-12-01

    We describe the spatial and temporal patterns of timber acquisition by great house builders in Chaco Canyon, New Mexico. The 87Sr/86Sr ratios from annually-dated, architectural logs in 10^{th} to 12^{th} century structures are compared to the 87Sr/86Sr of modern tree stands from the surrounding mountains. Although not a stable isotope system, the long half-life of the 87Sr parent (87Rb, t1/2 = 48.8 Ga) yields a stable isotope system on the timescales used to determine the geographic origin of ecosystem resources. The small mass difference among strontium's isotopes eliminates measurable biologic or kinetic fractionation at earth surface conditions. Strontium tracer studies, however, do require distinct end-member ratios to be feasible. Strontium isotopes, alone or in combination with other isotopes, provide a simple way to study and trace the geographic origin of ecosystem resources. Over the 150 km-wide Chaco Basin, 87Sr/86Sr ratios of modern trees range from 0.7055 to 0.7192. 87Sr/86Sr ratios from this and other studies show that during great house construction Chaco Canyon was provisioned with plant materials that came from more than 75 km away in all directions. This includes (1) corn (Zea mays) grown on the eastern flanks of the Chuska Mountains and floodplain of the San Juan River to the west and north, (2) spruce (Picea sp.) and fir (Abies sp.) architectural beams from the high crests of the Chuska and San Mateo Mountains to the west and south, and (3) ponderosa pine (Pinus ponderosa) from the low slopes of the La Platas and San Juan Mountains to the north, the San Pedro Mountains to the east, the Chuska and San Mateo Mountains and nearby mesas. There are no systematic patterns in spruce/fir or ponderosa provenance by great house (Pueblo Bonito, Chetro Ketl, Pueblo del Arroyo) or by time, suggesting the use of stockpiles from a few preferred sources from the beginning of large scale construction in or around Chaco Canyon. This is contrary to the view that

  2. Multiple protein biomarker assessment for recombinant bovine somatotropin (rbST abuse in cattle.

    Directory of Open Access Journals (Sweden)

    Susann K J Ludwig

    Full Text Available Biomarker profiling, as a rapid screening approach for detection of hormone abuse, requires well selected candidate biomarkers and a thorough in vivo biomarker evaluation as previously done for detection of growth hormone doping in athletes. The bovine equivalent of growth hormone, called recombinant bovine somatotropin (rbST is (illegally administered to enhance milk production in dairy cows. In this study, first a generic sample pre-treatment and 4-plex flow cytometric immunoassay (FCIA were developed for simultaneous measurement of four candidate biomarkers selected from literature: insulin-like growth factor 1 (IGF-1, its binding protein 2 (IGFBP2, osteocalcin and endogenously produced antibodies against rbST. Next, bovine serum samples from two extensive controlled rbST animal treatment studies were used for in vivo validation and biomarker evaluation. Finally, advanced statistic tools were tested for the assessment of biomarker combination quality aiming to correctly identify rbST-treated animals. The statistical prediction tool k-nearest neighbours using a combination of the biomarkers osteocalcin and endogenously produced antibodies against rbST proved to be very reliable and correctly predicted 95% of the treated samples starting from the second rbST injection until the end of the treatment period and even thereafter. With the same biomarker combination, only 12% of untreated animals appeared false-positive. This reliability meets the requirements of Commission Decision 2002/657/EC for screening methods in veterinary control. From the results of this multidisciplinary study, it is concluded that the osteocalcin - anti-rbST-antibodies combination represent fit-for-purpose biomarkers for screening of rbST abuse in dairy cattle and can be reliably measured in both the developed 4-plex FCIA as well as in a cost-effective 2-plex microsphere-based binding assay. This screening method can be incorporated in routine veterinary monitoring

  3. Paleomagnetic Results of the 925 Ma Mafic Dykes From the North China Craton: Implications for the Neoproterozoic Paleogeography of Rodinia

    Science.gov (United States)

    Zhao, X.; Peng, P.

    2017-12-01

    Precambrian mafic dyke swarms are useful geologic records for Neoproterozoic paleogeographic reconstruction. We present a paleomagnetic study of the 925 Ma Dashigou dyke swarm from 3 widely separated locations in the central and northern parts of the North China Craton, which are previously unsampled regions. Stepwise thermal and alternating field demagnetizations were successful in isolating two magnetic components. The lower unblocking temperature component represents the recent Earth magnetic field. The higher unblocking temperature component is the characteristic remanent magnetization and yields positive baked contact test. Results from detailed rock magnetic measurements corroborate the demagnetization behavior and show that titanomagnetites are the main magnetic carrier in these rocks. There was no regional event that has reset the remanent magnetization of all the dyke sites, as indicated by the magnetization directions of both overlying and underlying strata. The similarity of the virtual paleomagnetic poles for the 3 sampled regions also argues that the characteristic remanent magnetizations are primary magnetization when the dykes were emplaced. The paleomagnetic poles from the Dashigou dyke swarm of the North China Craton are not similar to those of the identical aged Bahia dykes from the São Francisco Craton, Brazil, indicating that these mafic dykes may be not parts of a common regional magmatic event that affected North China Craton and NE Brazil at about 925 Ma.

  4. Rb-intercalated C{sub 60} compounds studied by Inverse Photoemission Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Finazzi, M; Brambilla, A; Biagioni, P; Cattoni, A; Duo, L; Ciccacci, F; Braicovich, L [INFM and Dip di Fisica del Politecnico di Milano, Milano (Italy); Giovanelli, L; Goldoni, A [ELETTRA Basovizza (Italy)

    2004-07-01

    Full text: Since the discovery of superconductivity in alkali-doped solid C{sub 60}, the electronic structure of the host material (C{sub 60}) and the doped compounds (A{sub x}C{sub 60}, where A is an alkali metal), has been the subject of a considerable amount of work, both theoretical and experimental. The spectroscopic investigations of the alkali-doped C{sub 60} compounds has been mainly focussed on the valence states, while much less information is available on the unoccupied states. In particular, inverse photoemission data on the complete set of stable Rb{sub x}C{sub 60} compounds was, so far, still missing. We have performed Inverse Photoemission (IPE) spectroscopy on Rb{sub x}C{sub 60} compounds (x = 1, 3, 4, 6). IPE spectra were obtained using a band-pass photon detector (hv = 9.4 eV, FWHM = 0.7 eV) and scanning the kinetic energy of the electrons impinging on the sample. Rb was evaporated on C{sub 60} films (thickness = 6-12 atomic layers) grown in situ on a Cu(100) substrate. The temperature of the substrate was kept equal to T = 100 deg C, which is lower than the C{sub 60} sublimation temperature. The amount of Rb was checked by measuring the intensity of the C1s and Rb3d photoemission lines. After the required amount of Rb had been deposited, the samples were annealed to distillate the desired stable phase.

  5. Emission characteristics of Xe-RbBr plasma

    Science.gov (United States)

    Heneral, A. A.; Avtaeva, S. V.

    2017-12-01

    The luminescence spectra of the longitudinal pulsed-periodic discharge in Xe-RbBr gas-vapour mixtures at low pressures are experimentally studied. Conditions for obtaining strong UV radiation of XeBr* exiplex molecules in the spectral range of 200-425 nm are found. The greatest output of the XeBr* UV radiation is provided at temperature of the gas-discharge tube walls of ~1000 K. The maximum UV emission power of the whole plasma volume is 4.8 W. Formation of XeBr* exciplex molecules in the pulsed-periodic discharge in Xe-RbBr gas-vapour mixtures at low pressures is discussed.

  6. Construction of Rb charge exchange cell and characteristic experiment for He- ion production

    International Nuclear Information System (INIS)

    Lee, Hee Seock; Bak, Jun Gyo; Bak, Hae Ill

    1991-01-01

    The Rb charge exchange cell is constructed as the He - ion source of the SNU 1.5-MV Tandem Van de Graaff accelerator. the characteristic experiments is carried out in order to determine the optimum operational conditions of the cell. The He + ion beam with the energy of 1 - 10 keV, extracted from the duoplasmatron ion source, is passed through the Rb vapor to become He - ions by the two step charge exchange reaction, i.e., He + + Rb → He o* + Rb + and He o* + Rb → He - + Rb + . From the experimental results, it is found that the maximum fractional yield of He - ions is produced at He + /ion energy of 7 keV. The optimum temperatures of the oven and the canal are determined to be 370 deg C and 95 deg C respectively. Under the optimum operational condition the maximum fractional yield of He - ions is 2.42 ± 0.02 5. This charge exchange cell is proved to be an effective system for the production of He - ions. (Author)

  7. Effects of interaction between ultramafic tectonite and mafic magma on Nd-Pb-Sr isotopic systems in the Neoproterozoic Chaya Massif, Baikal-Muya ophiolite belt

    Science.gov (United States)

    Amelin, Yuri V.; Ritsk, Eugeni Yu.; Neymark, Leonid A.

    1997-04-01

    Sm-Nd, Rb-Sr and U-Pb isotopic systems have been studied in minerals and whole rocks of harzburgites and mafic cumulates from the Chaya Massif, Baikal-Muya ophiolite belt, eastern Siberia, in order to determine the relationship between mantle ultramafic and crustal mafic sections. Geological relations in the Chaya Massif indicate that the mafic magmas were emplaced into, and interacted with older solid peridotite. Hand picked, acid-leached, primary rock-forming and accessory minerals (olivine, orthopyroxene, clinopyroxene and plagioclase) from the two harzburgite samples show coherent behavior and yield 147Sm/ 144Nd- 143Nd/ 144Nd and 238U/ 204Pb- 206Pb/ 204Pb mineral isochrons, corresponding to ages of 640 ± 58 Ma (95% confidence level) and 620 ± 71 Ma, respectively. These values are indistinguishable from the crystallization age of the Chaya mafic units of 627 ± 25 Ma (a weighted average of internal isochron Sm-Nd ages of four mafic cumulates). The Rb-Sr and Sm-Nd isotopic systems in the harzburgite whole-rock samples were disturbed by hydrothermal alteration. These alteration-related isotopic shifts mimic the trend of variations in primary isotopic compositions in the mafic sequence, thus emphasizing that isotopic data for ultramafic rocks should be interpreted with great caution. On the basis of initial Sr and Nd values, ultramafic and mafic rocks of the Chaya Massif can be divided into two groups: (1) harzburgites and the lower mafic unit gabbronorites withɛ Nd = +6.6 to +7.1 andɛ Sr = -11 to -16; and (2) websterite of the lower unit and gabbronorites of the upper mafic unit:ɛ Nd = +4.6 to +6.1 andɛ Sr = -8 to -9. Initial Pb isotopic ratios are identical in all rocks studied, with mean values of 206Pb/ 204Pb= 16.994 ± 0.023 and 207Pb/ 204Pb= 15.363 ± 0.015. The similarity of ages and initial isotopic ratios within the first group indicates that the isotopic systems in the pre-existing depleted peridotite were reset by extensive interaction with

  8. Some problems of geologic relations between the Amazon craton and east margins fold belts

    International Nuclear Information System (INIS)

    Almeida, F.F.M. de

    1986-01-01

    This paper deals with some geologic problems related to the limits between the Amazon craton and the fold belts developed at its margins during the Precambrian. These limits are diversified but clearly recognized. To the north, the Araguaia-Tocantins fold belt, of presumed Middle Proterozoic age, is separated from the cratonic block by a deep marginal fracture zone permeated by mafic and ultramafic rocks. The geologic, magmatic and aeromagnetic characteristics of this zone point out the presence of deep faults, supposed to be of Middle Proterozoic age. The southern Paraguay fold belt constitutes and accurated zone of linear structures supposed to be of Late Proterozoic development. Despite the great increase of knowledge during the last ten years many tectonic, stratigraphic and geochronologic problems remain unsolved. The aim of this paper is to point out some of these problems and suggest specific studies to solve them. (author)

  9. 230Th-238U radioactive disequilibria in tholeiites from the FAMOUS zone (Mid-Atlantic Ridge, 36050'N): Th and Sr isotopic geochemistry

    International Nuclear Information System (INIS)

    Condomines, M.; Morand, P.; Allegre, C.J.

    1981-01-01

    We analyzed, U, Th and 230 Th/ 232 Th activity ratios for a few tholeiites from the Mid-Atlantic Ridge FAMOUS zone at 36 0 50'N. The results show a fairly wider scatter for both Th/U and ( 230 Th/ 232 Th) ratios. Seawater contamination appears to be responsible for this scatter and, for the uranium, produces an increase in content yielding a ( 234 U/ 238 U) ratio greater than 1 and, for the Th, an increase of the ( 230 Th/ 232 Th) ratio which is a very sensitive indicator for contamination. Also, the latter often is selective: U, Th and Sr are not affected in the same manner. When discarding all data for contaminated samples, the FAMOUS zone appears to be very homogeneous with a Th/U ratio value of 3.05 and a ( 230 Th/ 232 Th) ratio value of 1.24. Comparison with other active volcanic areas reveals a negative correlation between ( 230 Th/ 232 Th) and 87 Sr/ 86 Sr ratios for present lavas which is indicative of a consistency in Th-U and Rb-Sr fractionation in the source regions of these magmas. The Th isotopic geochemistry can thus provide useful information for the study of present volcanism, information as valuable as that from Sr, Pb or Nd isotopes. (orig.)

  10. The Rooiwater complex and associated rocks, Murchison granitoid-greenstone terrane, Kaapvaal Craton

    International Nuclear Information System (INIS)

    Vearncombe, J.R.; Walsh, K.L.

    1987-01-01

    The greater than 2625 Ma Rooiwater Complex is a thick, on-end differentiated basic igneous body exposed along the northern margin of the Murchison schist belt. It is metamorphosed to amphibolite facies and regionally retrograded and hydrothermally altered. Metamorphosed anorthosite, gabbro, pyroxenite, sulphide-bearing gabbros, thick magnetite layers, and granites are compatible with the hypothesis that the Complex is a layered intrusion, tectonically rotated and intruded by younger, genetically unrelated granites. Increasing TiO 2 and decreasing V 2 O 3 contents southwards in the magnetites layers combined with a general southern disposition of differentiated hornblende granite suggest that the Rooiwater Complex faces south. Although the Rubbervale Formation is pervasively deformed and metamorphosed at the greenschist facies, field relations and isotopic and rare earth element data tentatively suggest that a genetic relationship exists, the Rubbervale Formation being a possible roof to the Rooiwater intrusion, being derived from the same or a similar undepleted magmatic source. A paucity of ultramafic cumulates and up to 1,5 km of hornblende granites may relate to a source magma more felsic than that of other layered intrusions. In order to determine model ages for the Eden pluton, the Free State hornblende granite, the Quagga quartz amphibolite, the Rubbervale formation, and the Novengilla gabbro-anorthosite series. Rb-Sr and Pb isotopic analyses were undertaken

  11. Syntheses and characterization of one-dimensional alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs)

    Energy Technology Data Exchange (ETDEWEB)

    Yohannan, Jinu P.; Vidyasagar, Kanamaluru, E-mail: kvsagar@iitm.ac.in

    2015-01-15

    Three new isostructural quaternary antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs) have been synthesized by using alkali metal thiosulfate flux and structurally characterized by X-ray diffraction. Their structures contain A{sup +} ions around the [Sb{sub 2}Sn{sub 3}S{sub 10}]{sup 2−} chains, which are built from SbS{sub 3} pyramids, SnS{sub 6} octahedra and SnS{sub 4} tetrahedra. Raman and Mössbauer spectroscopic measurements corroborate the oxidation states and coordination environments of Sb(III) and Sn(IV). All three compounds are wide band gap semiconductors. Potassium compound undergoes partial exchange with strontium, cadmium and lead ions. - Graphical abstract: Syntheses, crystal structure, spectroscopic and partial ion-exchange studies of new one-dimensional alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs) are described. - Highlights: • Syntheses of new alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs). • Wide band gap semiconductors with one-dimensional structure. • Topotactic partial exchange of K{sup +} ions of K{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} with Sr{sup 2+}, Cd{sup 2+} and Pb{sup 2+} ions.

  12. Imaging the lithosphere-asthenosphere boundary across the transition from Phanerozoic Europe to the East-European Craton with S-receiver functions

    Science.gov (United States)

    Knapmeyer-Endrun, Brigitte; Krüger, Frank

    2013-04-01

    Cratons are characterized by their thick lithospheric roots. In the case of the Eastern European Craton, high seismic velocities have been imaged tomographically to more than 200 km depth. However, the exact depth extent of the cratonic lithosphere and especially the properties of the transition to a much thinner lithosphere beneath Phanerozoic central Europe still remain under discussion. Whereas a number of recent seismic campaigns has significantly increased the knowledge about crustal structure and Moho topography in central Europe, comparably detailed, 3-D information on upper mantle structure, e.g. the lithosphere-asthenosphere boundary (LAB), is yet missing. The international PASSEQ experiment, which was conducted from 2006 to 2008, strived to fill this gap with the deployment of 196 seismological stations, roughly a quarter of which were equipped with broad-band sensors, between eastern Germany and Lithuania. With a mean inter-station distance of 60 km, reduced to about 20 km along the central profile, PASSEQ offers the densest coverage for a passive experiment in this region yet. Here, we present first S-receiver function results for this data set, complemented by additional data from national and regional networks and other temporary deployments. This increases the number of available broad-band stations to almost 300, though mostly located to the west of the Trans-European Suture Zone (TESZ). Besides, we also process data from short-period (1 s and 5 s) sensors. The visibility of mantle-transition zone phases, even in single-station data, provides confidence in the quality of the obtained S-receiver functions. Moho conversions can be confidently identified for all stations. In case of a low-velocity sedimentary cover, as found for example in the Polish Basin, the S-receiver functions even provide clearer information on Moho depth than the P-receiver functions, which are heavily disturbed by shallow reverberations. For stations west of the TESZ, a clear

  13. A widespread devonian methamorphic episode in northern Patagonia, Argentina

    International Nuclear Information System (INIS)

    Ostera, H.A.; Linares, E; Haller, M.J; Cagnoni, M.C.; Lopez de Luchi, M

    2001-01-01

    One of the greatest difficulties in Rb-Sr dating on metamorphic rocks is the lack of evidences of complete re-homogenization and the assumption of a common initial ratio for all the samples analyzed. The redistribution of parent-daughter elements and the concomitant partial or complete equilibration of the isotopic system could occur on mineral or regional size domains. This fact led to many authors to discard or disapprove the use of this method in metamorphic terranes. However, recent papers suggested that this opinion has been premature and that additional information could be obtained by the Rb-Sr method despite the difficulties that it implies (Patel et al., 1999). Many reports on well fitted Rb-Sr isochrons giving the age of metamorphism in regionally metamorphosed rocks, suggest that the Sr isotopic equilibrium can take place at different scales. This paper presents data and the Rb-Sr system behaviour from a metamorphic unit (Cushamen Formation) in the Northern Patagonia, as a contribution to elucidate the evolution of the North Patagonian Massif (au)

  14. A Measurement of $R_{b}$ using a Double Tagging Method

    CERN Document Server

    Abbiendi, G.; Alexander, G.; Allison, John; Altekamp, N.; Anderson, K.J.; Anderson, S.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Ball, A.H.; Barberio, E.; Barlow, Roger J.; Bartoldus, R.; Batley, J.R.; Baumann, S.; Bechtluft, J.; Behnke, T.; Bell, Kenneth Watson; Bella, G.; Bellerive, A.; Bentvelsen, S.; Bethke, S.; Betts, S.; Biebel, O.; Biguzzi, A.; Bird, S.D.; Blobel, V.; Bloodworth, I.J.; Bobinski, M.; Bock, P.; Bohme, J.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Bright-Thomas, P.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Burgard, C.; Burgin, R.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Chrisman, D.; Ciocca, C.; Clarke, P.E.L.; Clay, E.; Cohen, I.; Conboy, J.E.; Cooke, O.C.; Couyoumtzelis, C.; Coxe, R.L.; Cuffiani, M.; Dado, S.; Dallavalle, G.Marco; Davis, R.; De Jong, S.; del Pozo, L.A.; De Roeck, A.; Desch, K.; Dienes, B.; Dixit, M.S.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Eatough, D.; Estabrooks, P.G.; Etzion, E.; Evans, H.G.; Fabbri, F.; Fanti, M.; Faust, A.A.; Fiedler, F.; Fierro, M.; Fleck, I.; Folman, R.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gascon, J.; Gascon-Shotkin, S.M.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Gibson, V.; Gibson, W.R.; Gingrich, D.M.; Glenzinski, D.; Goldberg, J.; Gorn, W.; Grandi, C.; Gross, E.; Grunhaus, J.; Gruwe, M.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Harder, K.; Hargrove, C.K.; Hartmann, C.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Herndon, M.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hillier, S.J.; Hobson, P.R.; Hocker, James Andrew; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Imrie, D.C.; Ishii, K.; Jacob, F.R.; Jawahery, A.; Jeremie, H.; Jimack, M.; Jones, C.R.; Jovanovic, P.; Junk, T.R.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Kayal, P.I.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Klier, A.; Kluth, S.; Kobayashi, T.; Kobel, M.; Koetke, D.S.; Kokott, T.P.; Kolrep, M.; Komamiya, S.; Kowalewski, Robert V.; Kress, T.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kyberd, P.; Lafferty, G.D.; Lanske, D.; Lauber, J.; Lautenschlager, S.R.; Lawson, I.; Layter, J.G.; Lazic, D.; Lee, A.M.; Lellouch, D.; Letts, J.; Levinson, L.; Liebisch, R.; List, B.; Littlewood, C.; Lloyd, A.W.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Ludwig, J.; Lui, D.; Macchiolo, A.; Macpherson, A.; Mader, W.; Mannelli, M.; Marcellini, S.; Markopoulos, C.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; Mckigney, E.A.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Menke, S.; Merritt, F.S.; Mes, H.; Meyer, J.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mir, R.; Mohr, W.; Montanari, A.; Mori, T.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nellen, B.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Oreglia, M.J.; Orito, S.; Palinkas, J.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Perez-Ochoa, R.; Petzold, S.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poffenberger, P.; Polok, J.; Przybycien, M.; Rembser, C.; Rick, H.; Robertson, S.; Robins, S.A.; Rodning, N.; Roney, J.M.; Roscoe, K.; Rossi, A.M.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sang, W.M.; Sarkisian, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharf, F.; Scharff-Hansen, P.; Schieck, J.; Schmitt, B.; Schmitt, S.; Schoning, A.; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Siroli, G.P.; Sittler, A.; Skuja, A.; Smith, A.M.; Snow, G.A.; Sobie, R.; Soldner-Rembold, S.; Sproston, M.; Stahl, A.; Stephens, K.; Steuerer, J.; Stoll, K.; Strom, David M.; Strohmer, R.; Surrow, B.; Talbot, S.D.; Tanaka, S.; Taras, P.; Tarem, S.; Teuscher, R.; Thiergen, M.; Thomson, M.A.; von Torne, E.; Torrence, E.; Towers, S.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turcot, A.S.; Turner-Watson, M.F.; Van Kooten, Rick J.; Vannerem, P.; Verzocchi, M.; Voss, H.; Wackerle, F.; Wagner, A.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wermes, N.; White, J.S.; Wilson, G.W.; Wilson, J.A.; Wyatt, T.R.; Yamashita, S.; Yekutieli, G.; Zacek, V.; Zer-Zion, D.

    1999-01-01

    The fraction of Z to bbbar events in hadronic Z decays has been measured by the OPAL experiment using the data collected at LEP between 1992 and 1995. The Z to bbbar decays were tagged using displaced secondary vertices, and high momentum electrons and muons. Systematic uncertainties were reduced by measuring the b-tagging efficiency using a double tagging technique. Efficiency correlations between opposite hemispheres of an event are small, and are well understood through comparisons between real and simulated data samples. A value of Rb = 0.2178 +- 0.0011 +- 0.0013 was obtained, where the first error is statistical and the second systematic. The uncertainty on Rc, the fraction of Z to ccbar events in hadronic Z decays, is not included in the errors. The dependence on Rc is Delta(Rb)/Rb = -0.056*Delta(Rc)/Rc where Delta(Rc) is the deviation of Rc from the value 0.172 predicted by the Standard Model. The result for Rb agrees with the value of 0.2155 +- 0.0003 predicted by the Standard Model.

  15. Structural transition induced by charge-transfer in RbMn[Fe(CN) sub 6]. Investigation by synchrotron-radiation X-ray powder analysis

    CERN Document Server

    Moritomo, Y; Sakata, M; Kato, K; Kuriki, A; Tokoro, H; Ohkoshi, S I; Hashimoto, K

    2002-01-01

    Temperature dependence of atomic coordinates is determined for RbMn[Fe(CN) sub 6] by means of synchrotron-radiation (SR) X-ray powder structural analysis. We observed a structural transition from the cubic (F4-bar3m; Z=4) to the tetragonal (I4-barm2; Z=2) phase at approx. =210K in the cooling run and at approx. =300K in the warming run. In the low-temperature tetragonal phase, we found Jahn-Tellar type distortion of the MnN sub 6 octahedra and compression of the averaged Fe-C bond distance. These structural data suggest that the structural transition is triggered by the inter-metallic charge-transfer from the Mn(II) site to the Fe(III) site.

  16. Operation and maintenance of the RB reactor, Annual report for 1977; Pogon i odrzavanje reaktora RB, Izvestaj o radu u 1977. godini

    Energy Technology Data Exchange (ETDEWEB)

    Sotic, O; Vranic, S [Boris Kidric Institute of Nuclear Sciences Vinca, Beograd (Yugoslavia)

    1977-07-01

    The annual report for 1977 includes the following: utilization of the RB reactor; new regulations and instructions for reactor operation; improvement of experimental possibilities of the RB reactor; state of the reactor equipment; dosimetry and radiation protection; reactor staff. Five annexes are concerned with: testing the properties of preamplifiers for linear and logarithmic experimental channels; properties of the neutron converter; maintenance of the reactor equipment; purchase of new equipment; and the program for training reactor operators.

  17. Use of Sr isotopes as a tool to decipher the soil weathering processes in a tropical river catchment, southwestern India

    International Nuclear Information System (INIS)

    Gurumurthy, G.P.; Balakrishna, K.; Tripti, M.; Riotte, Jean; Audry, Stéphane; Braun, Jean-Jacques; Udaya Shankar, H.N.

    2015-01-01

    River water composition (major ion and "8"7Sr/"8"6Sr ratio) was monitored on a monthly basis over a period of three years from a mountainous river (Nethravati River) of southwestern India. The total dissolved solid (TDS) concentration is relatively low (46 mg L"−"1) with silica being the dominant contributor. The basin is characterised by lower dissolved Sr concentration (avg. 150 nmol L"−"1), with radiogenic "8"7Sr/"8"6Sr isotopic ratios (avg. 0.72041 at outlet). The composition of Sr and "8"7Sr/"8"6Sr and their correlation with silicate derived cations in the river basin reveal that their dominant source is from the radiogenic silicate rock minerals. Their composition in the stream is controlled by a combination of physical and chemical weathering occurring in the basin. The molar ratio of SiO_2/Ca and "8"7Sr/"8"6Sr isotopic ratio show strong seasonal variation in the river water, i.e., low SiO_2/Ca ratio with radiogenic isotopes during non-monsoon and higher SiO_2/Ca with less radiogenic isotopes during monsoon season. Whereas, the seasonal variation of Rb/Sr ratio in the stream water is not significant suggesting that change in the mineral phase being involved in the weathering reaction could be unlikely for the observed molar SiO_2/Ca and "8"7Sr/"8"6Sr isotope variation in river water. Therefore, the shift in the stream water chemical composition could be attributed to contribution of ground water which is in contact with the bedrock (weathering front) during non-monsoon and weathering of secondary soil minerals in the regolith layer during monsoon. The secondary soil mineral weathering leads to limited silicate cation and enhanced silica fluxes in the Nethravati river basin. - Highlights: • Systematic monthly geochemical monitoring of a mountainous tropical river. • Soil weathering has dominant control on the surface water chemistry in the basin. • Soil redox process plays a dominant role in leaching of soil minerals. • Soil mineral weathering in

  18. Exploring strategies for the production of ultracold RbYb molecules in conservative traps

    Energy Technology Data Exchange (ETDEWEB)

    Bruni, Cristian

    2015-07-14

    Within the scope of this thesis, the production of ultracold molecules at a temperature of a few μK with various isotopes of rubidium (Rb) and ytterbium (Yb) was examined by means of photoassociation spectroscopy and magnetic Feshbach resonances in combined conservative traps. The long-term goal of this experiment is the production of ultracold RbYb molecules in the rovibronic ground state. It was possible to produce electronically excited {sup 87}Rb {sup 176}Yb molecules in a novel hybrid trap (HT) at a combined temperature of 1.7 μK by means of 1-photon photoassociation close to the Rb D1 line at 795 nm. This HT takes advantage of the different magnetic properties of Rb and Yb and allows for independent trapping and manipulation of the atomic species. It combines an Ioffe-Pritchard type magnetic trap for Rb and a near-resonant optical dipole trap for Yb. The excited molecular {sup 2}Π{sub 1/2} state could be characterized further extending previous works in a combined MOT and vibrational levels reaching binding energies up to E{sub b}=-h x 2.2 THz could be assigned by trap-loss spectroscopy. Almost every detected vibrational state consists of two resonances that could be assigned to the molecular analogue of the hyperfine structure of {sup 87}Rb. An important experimental observation is a decrease in hyperfine splitting with increasing binding energy of a vibrational level. For the deepest found vibrational state the hyperfine splitting amounts only 70 % of the atomic value (817 MHz) which emphasizes a gradual passage from weakly to tightly bound molecules. Furthermore, detailed attempts were undertaken to induce magnetic Feshbach resonances in {sup 85}Rb and different Yb isotopes, especially {sup 171}Yb in a crossed optical dipole trap at 1064 nm at temperatures of 10 μK. For this purpose, a homogeneous magnetic field was applied and scanned in small steps over the range of 495 G ∼ 640 G. Unfortunately, our efforts were without success. Additionally, well

  19. High-precision γ -ray spectroscopy of the cardiac PET imaging isotope 82Rb and its impact on dosimetry

    Science.gov (United States)

    Nino, M. N.; McCutchan, E. A.; Smith, S. V.; Lister, C. J.; Greene, J. P.; Carpenter, M. P.; Muench, L.; Sonzogni, A. A.; Zhu, S.

    2016-02-01

    82Rb is a positron-emitting isotope used in cardiac positron emission tomography (PET) imaging which has been reported to deliver a significantly lower effective radiation dose than analogous imaging isotopes like 201Tl and 99 mTc sestamibi. High-quality β -decay data are essential to accurately appraise the total dose received by the patients. A source of 82Sr was produced at the Brookhaven Linac Isotope Producer (BLIP), transported to Argonne National Laboratory, and studied with the Gammasphere facility. Significant revisions have been made to the level scheme of 82Kr including 12 new levels, 50 new γ -ray transitions, and the determination of many new spin assignments through angular correlations. These new high-quality data allow a precise reappraisal of the β -decay strength function and thus the consequent dose received by patients.

  20. Studies of rubidium selenate with secondary phase of RbOH under humidified reducing atmosphere

    International Nuclear Information System (INIS)

    Beyribey, Berceste; Hallinder, Jonathan; Poulsen, Finn Willy; Bonanos, Nikolaos; Mogensen, Mogens

    2012-01-01

    Highlights: ► Degradation of Rb 2 SeO 3 and Rb 2 SeO 4 to form RbOH provide protonic conductivity. ► The conductivity increases by increasing temperature. ► The highest conductivity value of 2.01·10 −4 S cm −1 is observed at 317 °C. ► The work may state conductivity rise in solid acid electrolytes upon decomposition. - Abstract: The high temperature properties of Rb 2 SeO 4 have been studied by calorimetry, impedance spectroscopy and X-ray powder diffraction. As synthesized, Rb 2 SeO 4 includes a second phase of Rb 2 SeO 3 , which can be eliminated upon heating the compound. As expected, no conductivity is observed in dry (pH 2 O 2 O = 0.1 bar) air at 176 °C, the conductivity increases sharply from 8.6·10 −8 to 1.7·10 −6 S cm −1 . Under humidified (pH 2 O = 0.1 bar) reducing atmosphere (9%H 2 in N 2 ), the conductivity increases to 2.0·10 −4 S cm −1 at 317 °C. Degradation of Rb 2 SeO 3 and Rb 2 SeO 4 to form RbOH, which is known as a proton conductor, are thought to be responsible for the observed conductivity in humidified atmospheres. Our observations may explain the conductivity rise in other solid acid electrolytes, including sulfate and selenate groups, around their decomposition temperatures, in humidified atmospheres.

  1. APW path traced for the Guiana Shield (2070-1960 Ma) and Paleogeographic Implications: Paleomagnetic data from the 1.98-1.96 Ga Surumu Group (Northern Amazonian Craton)

    Science.gov (United States)

    Bispo-Santos, F.; Dagrella Filho, M. S.; Reis, N. J.; Trindade, R. I.

    2013-05-01

    Definition of continental paleogeography for times prior to formation of Columbia Supercontinent (1900-1850 Ma) is very complex, since amalgamation of some continental blocks of Earth was still in progress, as in the case of Laurentia, Baltica and Amazonian Craton. So, paleogeographic models proposed for this time are still very speculative and/or subjective. The use of the paleomagnetic technique tracing apparent polar wander (APW) paths for the various cratonic blocks can contribute to understand the continental amalgamation and breakup, especially for times where all created oceanic lithosphere was fully consumed. In this study, we present the paleomagnetic data obtained for samples collected from 39 sites from the well-dated 1980-1960 Ma (U-Pb) volcanic rocks belonging to the Surumu Group, cropping out in the northern Roraima State (Guiana Shield, Amazonian Craton). AF and thermal treatment revealed northwestern directions with moderate downward inclinations on samples from 20 out of the 39 analyzed sites. Site mean directions cluster around the mean, Dm = 298.6°; Im = 39.4° (N = 20; α95 = 10.1°), which yielded a key paleomagnetic pole (SG) for the Guiana Shield, located at 234.8°E, 27.4°N (A95 = 9.8°). Magnetic mineralogy experiments show that the magnetization of these rocks, probably of primary origin, is carried by magnetite and/or hematite. The SG pole contributes to a better fit of the APW path traced for Guiana Shield during the Paleoproterozoic (2070-1960 Ma). Comparison with the APW path traced for the West-Africa Craton for the same time interval suggests that these cratonic blocks were linked at 2000-1960 Ma ago, forming a paleogeography in which the Guri (Guiana Shield) and Sassandra (West-Africa Craton) shear zones were aligned as suggested in previous geologic models. KEYWORDS: Paleoproterozoic, Paleomagnetism, APWP, Amazonian Craton, Surumu Group.

  2. RB Research nuclear reactor, Annual report for 2006

    International Nuclear Information System (INIS)

    Milosevic, M.; Ljubenov, V.; Pesic, M.; Jevremovic, M.; Minic, D.

    2007-01-01

    Report on RB reactor operation during 2006 contains 3 parts. Part one contains a brief description of the reactor, reactor operation and operational capabilities, reactor components, relevant dosimetry and radiation protection issues, personnel and financial data. Part two is devoted to maintenance of the reactor components, namely, fuel, heavy water, reactor vessel, heavy water circulation system, absorption rods and heavy water level meters, maintenance of electronic, mechanical, electrical and auxiliary equipment. Part three contains detailed data concerned with measurements performed at the RB reactor and a number of significant results obtained

  3. R$_{b}$ - R$_{c}$ crisis and new physics

    CERN Document Server

    Bhattacharya, G; Hou Wei Shu; Bhattacharyya, Gautam; Branco, Gustavo C; Hou, Wei Shu

    1996-01-01

    The experimental values of R_b and R_c are the only data which do not seem to agree with Standard Model predictions. Although it is still premature to draw any definite conclusions, it is timely to look for new physics which could explain the excess in R_b and deficit in R_c. We investigate this problem in a simple extension of the Standard Model, where a charge +2/3 isosinglet quark is added to the standard spectrum. Upon the further introduction of an extra scalar doublet, one finds a solution with interesting consequences.

  4. Electronic parameters and top surface chemical stability of RbPb{sub 2}Br{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V.V., E-mail: atuchin@thermo.isp.nsc.ru [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Isaenko, L.I. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Kesler, V.G. [Laboratory of Physical Principles for Integrated Microelectronics, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Pokrovsky, L.D. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Tarasova, A.Yu. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

    2012-01-16

    Highlights: Black-Right-Pointing-Pointer Bridgman growth of RbPb{sub 2}Br{sub 5} crystal. Black-Right-Pointing-Pointer Electronic structure measurements with XPS. Black-Right-Pointing-Pointer Optical crystalline surface fabrication. - Abstract: The RbPb{sub 2}Br{sub 5} crystal has been grown by Bridgman method. The electronic structure of RbPb{sub 2}Br{sub 5} has been measured with XPS for a powder sample. High chemical stability of RbPb{sub 2}Br{sub 5} surface is verified by weak intensity of O 1s core level recorded by XPS and structural RHEED measurements. Chemical bonding effects have been observed by the comparative analysis of element core levels and crystal structure of RbPb{sub 2}Br{sub 5} and several rubidium- and lead-containing bromides using binding energy difference parameters {Delta}{sub Rb} = (BE Rb 3d - BE Br 3d) and {Delta}{sub Pb} = (BE Pb 4f{sub 7/2} - BE Br 3d).

  5. RB1CC1 Protein Suppresses Type II Collagen Synthesis in Chondrocytes and Causes Dwarfism*

    Science.gov (United States)

    Nishimura, Ichiro; Chano, Tokuhiro; Kita, Hiroko; Matsusue, Yoshitaka; Okabe, Hidetoshi

    2011-01-01

    RB1-inducible coiled-coil 1 (RB1CC1) functions in various processes, such as cell growth, differentiation, senescence, apoptosis, and autophagy. The conditional transgenic mice with cartilage-specific RB1CC1 excess that were used in the present study were made for the first time by the Cre-loxP system. Cartilage-specific RB1CC1 excess caused dwarfism in mice without causing obvious abnormalities in endochondral ossification and subsequent skeletal development from embryo to adult. In vitro and in vivo analysis revealed that the dwarf phenotype in cartilaginous RB1CC1 excess was induced by reductions in the total amount of cartilage and the number of cartilaginous cells, following suppressions of type II collagen synthesis and Erk1/2 signals. In addition, we have demonstrated that two kinds of SNPs (T-547C and C-468T) in the human RB1CC1 promoter have significant influence on the self-transcriptional level. Accordingly, human genotypic variants of RB1CC1 that either stimulate or inhibit RB1CC1 transcription in vivo may cause body size variations. PMID:22049074

  6. Frequent disruption of the RB1 pathway in diffuse large B cell lymphoma

    DEFF Research Database (Denmark)

    Møller, Michael Boe; Kania, P W; Ino, Y

    2000-01-01

    In the present study, we analysed 34 de novo diffuse large B cell lymphoma (DLCL) from a population-based lymphoma registry for alterations of the RB1 pathway at the genetic (RB1 and CDK4) and protein (pRb, cyclin D1, cyclin D3, CDK4, and E2F-1) level. The results were correlated with the data fr...

  7. The Re-evaluation of {sup 84}Rb decay data

    Energy Technology Data Exchange (ETDEWEB)

    Xiaolong, Huang; Chunmei, Zhou [Chinese Nuclear Data Center, Beijing, BJ (China)

    1996-06-01

    The {sup 84}Rb is an important radionuclide and its decay data are fundamental data in nuclear applications. The decay data for {sup 84}Rb were re-evaluated. The energies and intensities of {gamma} rays and their internal conversion coefficients, energies and intensities of Auger electrons, conversion electrons and x-rays, were recommended. The decay scheme was also given. The balance of radiation rays intensities and energies was checked. (9 tabs., 2 figs.).

  8. Study of particulate matter in Limeira (Brazil) using SR-TXRF

    International Nuclear Information System (INIS)

    Canteras, Felippe B.; Moreira, Silvana

    2011-01-01

    Air pollution is a growing problem mainly in metropolitan areas in the world. The atmospheric pollutants are responsible for various environmental problems including the human health. Among the pollutants, the particulate matter is important, since it has a heterogeneous composition. The goal of this work was to analyze quantitatively the particulate matter in Limeira city, Sao Paulo State, Brazil. The sampling was made using a sequential filtering system, containing two filters putted in series, to collect fine and coarse fractions. After a removal in an acid medium, with ultrasound bath, the samples were analyzed by Synchrotron Radiation Total Reflection X-Ray Fluorescence (SR-TXRF). The results obtained for PM10 were in agreement with the standards defined by the Brazilian legislation and also with the standards established by USEPA. In all analyzed samples S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Ba and Pb were quantified. Employing multivariate statistical analysis (principal component and cluster analysis) was possible to identify the emission sources. For coarse fraction the main emission source was soil dusty responsible for 57% of the total in the coarse fraction, followed by vehicular emission with 30% and industrial 13%. In the fine fraction soil dusty was the mainly emission source contributing with 79% of the total, followed by vehicular emission with 13% and finally the industrial emission responsible just for 8%. (author)

  9. Study of particulate matter in Limeira (Brazil) using SR-TXRF

    Energy Technology Data Exchange (ETDEWEB)

    Canteras, Felippe B.; Moreira, Silvana, E-mail: silvana@fec.unicamp.b [Universidade Estadual de Campinas (FEC/UNICAMP), SP (Brazil) Faculdade de Engenharia Civil, Arquitetura e Urbanismo

    2011-07-01

    Air pollution is a growing problem mainly in metropolitan areas in the world. The atmospheric pollutants are responsible for various environmental problems including the human health. Among the pollutants, the particulate matter is important, since it has a heterogeneous composition. The goal of this work was to analyze quantitatively the particulate matter in Limeira city, Sao Paulo State, Brazil. The sampling was made using a sequential filtering system, containing two filters putted in series, to collect fine and coarse fractions. After a removal in an acid medium, with ultrasound bath, the samples were analyzed by Synchrotron Radiation Total Reflection X-Ray Fluorescence (SR-TXRF). The results obtained for PM10 were in agreement with the standards defined by the Brazilian legislation and also with the standards established by USEPA. In all analyzed samples S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Ba and Pb were quantified. Employing multivariate statistical analysis (principal component and cluster analysis) was possible to identify the emission sources. For coarse fraction the main emission source was soil dusty responsible for 57% of the total in the coarse fraction, followed by vehicular emission with 30% and industrial 13%. In the fine fraction soil dusty was the mainly emission source contributing with 79% of the total, followed by vehicular emission with 13% and finally the industrial emission responsible just for 8%. (author)

  10. Heat flow, heat generation and crustal thermal structure of the northern block of the South Indian Craton

    Science.gov (United States)

    Gupta, Mohan L.; Sharma, S. R.; Sundar, A.

    Heat flow values and heat generation data calculated from the concentration of heat producing radioactive elements, U, Th and K in surface rocks were analyzed. The South Indian Craton according to Drury et al., can be divided into various blocks, separated by late Proterozoic shear belts. The northern block comprises Eastern and Western Dharwar Cratons of Rogers (1986), Naqvi and Rogers (1987) and a part of the South Indian granulite terrain up to a shear system occupying the Palghat-Cauvery low lands. The geothermal data analysis clearly demonstrates that the present thermal characteristics of the above two Archaean terrains of the Indian and Australian Shields are quite similar. Their crustal thermal structures are likely to be similar also.

  11. Heat flow, heat generation and crustal thermal structure of the northern block of the South Indian Craton

    Science.gov (United States)

    Gupta, Mohan L.; Sharma, S. R.; Sundar, A.

    1988-01-01

    Heat flow values and heat generation data calculated from the concentration of heat producing radioactive elements, U, Th and K in surface rocks were analyzed. The South Indian Craton according to Drury et al., can be divided into various blocks, separated by late Proterozoic shear belts. The northern block comprises Eastern and Western Dharwar Cratons of Rogers (1986), Naqvi and Rogers (1987) and a part of the South Indian granulite terrain up to a shear system occupying the Palghat-Cauvery low lands. The geothermal data analysis clearly demonstrates that the present thermal characteristics of the above two Archaean terrains of the Indian and Australian Shields are quite similar. Their crustal thermal structures are likely to be similar also.

  12. 40Ar/39Ar dating of 1.0-1.1 Ga magnetizations from the Sao Francisco and Kalahari cratons: tectonic implications for Pan-African and Brasiliano mobile belts

    International Nuclear Information System (INIS)

    Renne, P.R.; Onstott, T.C.; Agrella-Filho, M.S. d'; Pacca, I.G.; Teixeira, W.

    1990-01-01

    Paleomagnetic poles from 1.1-1.0 Ga dyke swarms in eastern Brazil (Sao Francisco Craton) are compared with 1.0 Ga poles from granulites of the Namaqua Province in southern Africa (Kalahari Graton). The intrusive ages of dykes are estimated from 40 Ar/ 39 Ar dating of outgassed biotites from baked country rocks. The age of magnetization for the granulites is derived by combining 40 Ar/ 39 Ar hornblende and biotite dates. When restored to a Mesozoic pre-drift configuration the paleomagnetic poles are in crude spatial agreement but are temporally discordant. To satisfy both paleomagnetic and geochronologic constraints, a reconstruction involving separation of the Sao Francisco and Kalahari cratons is required, indicating that the intervening Pan-African (Brasiliano) mobile belt may record a craton-craton collision. (orig.)

  13. High-resolution sequence stratigraphy of lower Paleozoic sheet sandstones in central North America: The role of special conditions of cratonic interiors in development of stratal architecture

    Science.gov (United States)

    Runkel, Anthony C.; Miller, J.F.; McKay, R.M.; Palmer, A.R.; Taylor, John F.

    2007-01-01

    Well-known difficulties in applying sequence stratigraphic concepts to deposits that accumulated across slowly subsiding cratonic interior regions have limited our ability to interpret the history of continental-scale tectonism, oceanographic dynamics of epeiric seas, and eustasy. We used a multi-disciplinary approach to construct a high-resolution stratigraphic framework for lower Paleozoic strata in the cratonic interior of North America. Within this framework, these strata proved readily amenable to modern sequence stratigraphic techniques that were formulated based on successions along passive margins and in foreland basins, settings markedly different from the cratonic interior. Parasequences, parasequence stacking patterns, systems tracts, maximum flooding intervals, and sequence-bounding unconformities can be confidently recognized in the cratonic interior using mostly standard criteria for identification. The similarity of cratonic interior and foreland basin successions in size, geometry, constituent facies, and local stacking patterns of nearshore parasequences is especially striking. This similarity indicates that the fundamental processes that establish shoreface morphology and determine the stratal expression of retreat and progradation were likewise generally the same, despite marked differences in tectonism, physiography, and bathymetry between the two settings. Our results do not support the widespread perception that Paleozoic cratonic interior successions are so anomalous in stratal geometries, and constitute such a poor record of time, that they are poorly suited for modern sequence stratigraphic analyses. The particular arrangement of stratal elements in the cratonic interior succession we studied is no more anomalous or enigmatic than the variability in architecture that sets all sedimentary successions apart from one another. Thus, Paleozoic strata of the cratonic interior are most appropriately considered as a package that belongs in a

  14. The origin of the RB1 imprint.

    Directory of Open Access Journals (Sweden)

    Deniz Kanber

    Full Text Available The human RB1 gene is imprinted due to a differentially methylated CpG island in intron 2. This CpG island is part of PPP1R26P1, a truncated retrocopy of PPP1R26, and serves as a promoter for an alternative RB1 transcript. We show here by in silico analyses that the parental PPP1R26 gene is present in the analysed members of Haplorrhini, which comprise Catarrhini (Old World Monkeys, Small apes, Great Apes and Human, Platyrrhini (New World Monkeys and tarsier, and Strepsirrhini (galago. Interestingly, we detected the retrocopy, PPP1R26P1, in all Anthropoidea (Catarrhini and Platyrrhini that we studied but not in tarsier or galago. Additional retrocopies are present in human and chimpanzee on chromosome 22, but their distinct composition indicates that they are the result of independent retrotransposition events. Chimpanzee and marmoset have further retrocopies on chromosome 8 and chromosome 4, respectively. To examine the origin of the RB1 imprint, we compared the methylation patterns of the parental PPP1R26 gene and its retrocopies in different primates (human, chimpanzee, orangutan, rhesus macaque, marmoset and galago. Methylation analysis by deep bisulfite sequencing showed that PPP1R26 is methylated whereas the retrocopy in RB1 intron 2 is differentially methylated in all primates studied. All other retrocopies are fully methylated, except for the additional retrocopy on marmoset chromosome 4, which is also differentially methylated. Using an informative SNP for the methylation analysis in marmoset, we could show that the differential methylation pattern of the retrocopy on chromosome 4 is allele-specific. We conclude that the epigenetic fate of a PPP1R26 retrocopy after integration depends on the DNA sequence and selective forces at the integration site.

  15. Sulfate- and Sulfur-Reducing Bacteria as Terrestrial Analogs for Microbial Life on Jupiter's Satellite Io

    Science.gov (United States)

    Pikuta, Elena V.; Hoover, Richard B.; Six, N. Frank (Technical Monitor)

    2001-01-01

    Observations from the Voyager and Galileo spacecraft have revealed Jupiter's moon Io to be the most volcanically active body of our Solar System. The Galileo Near Infrared Imaging Spectrometer (NIMS) detected extensive deposits of sulfur compounds, elemental sulfur and SO2 frost on the surface of Io. There are extreme temperature variations on Io's surface, ranging from -130 C to over 2000 C at the Pillan Patera volcanic vent. The active volcanoes, fumaroles, calderas, and lava lakes and vast sulfur deposits on this frozen moon indicate that analogs of sulfur- and sulfate-reducing bacteria might inhabit Io. Hence Io may have great significance to Astrobiology. Earth's life forms that depend on sulfur respiration are members of two domains: Bacteria and Archaea. Two basic links of the biogeochemical sulfur cycle of Earth have been studied: 1) the sulfur oxidizing process (occurring at aerobic conditions) and 2) the process of sulfur-reduction to hydrogen sulfide (anaerobic conditions). Sulfate-reducing bacteria (StRB) and sulfur-reducing bacteria (SrRB) are responsible for anaerobic reducing processes. At the present time the systematics of StRB include over 112 species distributed into 35 genera of Bacteria and Archaea. Moderately thermophilic and mesophilic SrRB belong to the Bacteria. The hyperthermophilic SrRB predominately belong to the domain Archaea and are included in the genera: Pyrodictium, Thermoproteus, Pyrobaculum, Thermophilum, Desulfurococcus, and Thermodiscus. The StRB and SrRB use a wide spectrum of substrates as electron donors for lithotrophic and heterotrophic type nutrition. The electron acceptors for the StRB include: sulfate, thiosulfate, sulfite, sulfur, arsenate, dithionite, tetrathionate, sulfur monoxide, iron, nitrite, selenite, fumarate, oxygen, carbon dioxide, and chlorine-containing phenol compounds. The Sulfate- and Sulfur-reducing bacteria are widely distributed in anaerobic ecosystems, including extreme environments like hot springs

  16. Special K: testing the potassium link between radioactive rubidium (86Rb) turnover and metabolic rate.

    Science.gov (United States)

    Tomlinson, Sean; Mathialagan, Priya D; Maloney, Shane K

    2014-04-01

    The measurement of (86)Rb turnover recently has been suggested as a useful method for measuring field metabolic rate in small animals. We investigated a proposed mechanism of (86)Rb turnover, its analogy to K(+), by comparing the turnover of (86)Rb in a model insect, the rhinoceros beetle Xylotrupes gideon, fed a diet of plum jam or plum jam enriched with K(+) or Rb(+). The turnover of (86)Rb in the beetles on the K(+) and the Rb(+) diets was higher than that for beetles on the jam diet (F2,311=32.4; P=1.58×10(-13)). We also exposed the beetles to different ambient temperatures to induce differences in metabolic rate ( ) while feeding them the jam and K(+) diets. was higher at higher ambient temperature (Ta) for both jam (F1,11=14.56; P=0.003) and K(+) (F1,8=15.39; P=0.004) dietary groups, and the turnover of (86)Rb was higher at higher Ta for both jam (F1,11=10.80; P=0.007) and K(+) (F1,8=12.34; P=0.008) dietary groups. There was a significant relationship between (86)Rb turnover and for both the jam (F1,11=35.00; P=1.0×10(-3)) and the K(+) (F1,8=64.33; P=4.3×10(-5)) diets, but the relationship differed between the diets (F1,19=14.07; P=0.001), with a higher (86)Rb turnover in beetles on the K(+)-enriched than on the jam diet at all Ta. We conclude that (86)Rb turnover is related to K(+) metabolism, and that this is the mechanism of the relationship between (86)Rb turnover and . Studies relating (86)Rb turnover to should maintain dietary [K] as close as possible to that of natural diets for the most accurate calibrations for free-ranging animals.

  17. Absorption spectra of thin films of triple compounds in the system RbIPbI2

    International Nuclear Information System (INIS)

    Yunakova, O.N.; Miloslavskij, V.K.; Ksenofontova, E.V.; Kovalenko, E.N.

    2012-01-01

    A formation of compounds RbPbI 3 and Rb 4 PbI 6 in the system RbI-PbI 2 is revealed and their absorption spectra are investigated in an energy interval 2-6 eV and a temperatures range 90-500 K. It is established that the low-frequency exciton excitations are localized in PbI 6 4- structural elements of the crystal lattice, they are classified as excitons of intermediate coupling and are of a three-dimensional character in RbPbI 3 and a quasi-two-dimensional one in Rb 4 PbI 6 .

  18. Environmental effects on energy metabolism and 86Rb elimination rates of fishes

    International Nuclear Information System (INIS)

    Peters, E.L.

    1994-01-01

    Relationships between energy metabolism and the turnover rates of number of important chemical and radiological elements (particularly the Group IA alkali metals: K, Rb, and Cs) have been observed in fishes. Using response surface statistics and fractional factorial ANOVA, the author examined the relative influences of temperature, salinity, food intake rate, mass, and their first order interactions on routine energy metabolism and 86 Rb elimination rates. Routine metabolic rates were increased primarily by increased temperature and salinity, with a strong body mass effect and a significant effect of food intake. 86 Rb elimination rates were increased primarily by increased temperature and salinity. There were no interactive effects between mass and either temperature or salinity for either routine energy metabolism or 86 Rb elimination rates. There was a significant interaction effect between temperature and salinity on routine energy metabolism rates, but not on 86 Rb elimination. The authors also observed a relationship between routine energy metabolism and 86 Rb elimination rates that may possibly be exploited as a means of estimating energy metabolic rates of fishes in the field. The statistical techniques used in this experiment have broad potential applications in assessing the contributions of combinations of environmental variables on contaminant kinetics, as well as in multiple toxicity testing, in that they greatly simplify experimental designs compared with traditional full-factorial methods

  19. Perfusion imaging using rubidium-82 ((82)Rb) PET in rats with myocardial infarction

    DEFF Research Database (Denmark)

    Clemmensen, Andreas Ettrup; Ghotbi, Adam Ali; Bodholdt, Rasmus Poul

    2017-01-01

    Assessing myocardial perfusion using 82Rb-PET is emerging as a valuable clinical tool.1,2 The rapid decay (T½ = 76 s) allows for absolute quantification of both rest and stress perfusion within 30 minutes. In addition to evaluation of epicardial disease with perfusion defects, also evaluation...... of balanced coronary and small vessel disease is possible. For further evaluation of how 82Rb-PET can be used clinically, pre-clinical application of the method would be valuable. However, so far no data on the use of 82Rb-PET in small animals have been published nor has the use of 82Rb-PET, to the best...

  20. RB4CD12 epitope expression and heparan sulfate disaccharide composition in brain vasculature.

    Science.gov (United States)

    Hosono-Fukao, Tomomi; Ohtake-Niimi, Shiori; Nishitsuji, Kazuchika; Hossain, Md Motarab; van Kuppevelt, Toin H; Michikawa, Makoto; Uchimura, Kenji

    2011-11-01

    RB4CD12 is a phage display antibody that recognizes a heparan sulfate (HS) glycosaminoglycan epitope. The epitope structure is proposed to contain a trisulfated disaccharide, [-IdoA(2-OSO(3))-GlcNSO(3) (6-OSO(3))-], which supports HS binding to various macromolecules such as growth factors and cytokines in central nervous tissues. Chemically modified heparins that lack the trisulfated disaccharides failed to inhibit the RB4CD12 recognition of HS chains. To determine the localization of the RB4CD12 anti-HS epitope in the brain, we performed an immunohistochemical analysis for cryocut sections of mouse brain. The RB4CD12 staining signals were colocalized with laminin and were detected abundantly in the vascular basement membrane. Bacterial heparinases eliminated the RB4CD12 staining signals. The RB4CD12 epitope localization was confirmed by immunoelectron microscopy. Western blotting analysis revealed that the size of a major RB4CD12-positive molecule is ∼460 kDa in a vessel-enriched fraction of the mouse brain. Disaccharide analysis with reversed-phase ion-pair HPLC showed that [-IdoA(2-OSO(3))-GlcNSO(3) (6-OSO(3))-] trisulfated disaccharide residues are present in HS purified from the vessel-enriched brain fraction. These results indicated that the RB4CD12 anti-HS epitope exists in large quantities in the brain vascular basement membrane. Copyright © 2011 Wiley-Liss, Inc.

  1. Coupled fast-thermal system at the 'RB' nuclear reactor

    International Nuclear Information System (INIS)

    Pesic, M.

    1987-04-01

    The results of the analyses of the possibility of the coupled fast-thermal system (CFTS) design at the 'RB' nuclear reactor are shown. As the proof of the theoretical analyses the first stage CFTS-1 has been designed, realized, and tested. The excellent agreement between the results of the CFTS-1 studies and the theoretical predictions opens a straight way to the second, the final stage - realization of the designed CFST at the 'RB' nuclear reactor. (author)

  2. Study of reactor parameters of on critical systems, Phase I: Safety report for RB zero power reactor; Ispitivanje reaktorskih parametara na kriticnim sistemima, I faza: Izvestaj o sigurnosti reaktora nulte snage RB

    Energy Technology Data Exchange (ETDEWEB)

    Raisic, N [Boris Kidric Institute of Nuclear Sciences Vinca, Belgrade (Yugoslavia)

    1962-09-15

    In addition to the safety analysis for the zero power RB reactor, this report contains a general description of the reactor, reactor components, auxiliary equipment and the reactor building. Reactor Rb has been reconstructed during 1961-1962 and supplied with new safety-control system as well as with a complete dosimetry instrumentation. Since RB reactor was constructed without shielding special attention is devoted to safety and protection of the staff performing experiments. Due to changed circumstances in the Institute ( start-up of the RA 7 MW power reactor) the role of the RB reactor was redefined.

  3. Double photoionisation in Rb and Cs in the threshold region

    International Nuclear Information System (INIS)

    Holland, D.M.P.; Codling, K.

    1981-01-01

    The extreme ultraviolet radiation emitted by the Bonn 2.5-GeV electron synchrotron, monochromatised by a 1-m vertically-dispersing Seya. The radiation, of 2 Angstroem band-pass (0.15 eV at 30 eV), was incident on an atomic beam of Rb or Cs vapour produced by a resistively heated oven. To avoid excessive oxidation, the oven was loaded with the alkali metal still under petroleum spirit and the residual spirit removed on evacuation of the system. The drift tube of a time-of-flight (TOF) mass spectrometer was placed at right angles to both the photon and atomic beams. The singly and doubly charged ions were pulsed out of the interaction region and detected by a microchannel-plate assembly placed at the end of the drift tube. The results for Rb are neither so accurate nor extensive as for Cs because a peak at mass number 44 in the TOF spectrum (probably CO 2 ), due to emission from the oven region, obscured the small Rb 2+ peak. The results for both Rb and Cs are shown as the ratios of double-to-single photoionisation. (orig./AH)

  4. Uptake of /sup 86/Rb/sup +/ into photoautotrophic mesophyll cells of Papaver somniferum

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, W.M.; Jeschke, W.D.; Hartung, W.

    1982-06-01

    Uptake of /sup 86/Rb/sup +/, used as a tracer for potassium, into isolated photoautotrophic mesophyll cells of Papaver somniferum was weakly but consistently stimulated in the light. It showed mono-phasic saturation kinetics with a pH optimum of 7.0, a Vsub(max) of 6.7 ..mu..mol mg/sup -1/ Chl x h/sup -1/ and a Ksub(m) of 2.7 mmol l/sup -1/. Different anions as Cl/sup -/, NO/sub 3//sup -/ and PO/sub 4//sup 3 -/ had no effects on /sup 86/Rb/sup +/ uptake. Sodium ions influenced Rb/sup +/-uptake very weakly, indicating a high K/sup +/ -specificity of the mesophyll cell plasmalemma. Fusicoccin stimulated /sup 86/Rb/sup +/ -uptake strongly whereas abscisic acid inhibited uptake only following preincubation for two hours. Nitrite, CCCP and Dio-9 inhibited /sup 86/Rb/sup +/-uptake which gives evidence that this process is dependent on intact pH-gradients within the cells and on ATP-formation.

  5. Autochthonous tumors driven by Rb1 loss have an ongoing requirement for the RBP2 histone demethylase.

    Science.gov (United States)

    McBrayer, Samuel K; Olenchock, Benjamin A; DiNatale, Gabriel J; Shi, Diana D; Khanal, Januka; Jennings, Rebecca B; Novak, Jesse S; Oser, Matthew G; Robbins, Alissa K; Modiste, Rebecca; Bonal, Dennis; Moslehi, Javid; Bronson, Roderick T; Neuberg, Donna; Nguyen, Quang-De; Signoretti, Sabina; Losman, Julie-Aurore; Kaelin, William G

    2018-04-17

    Inactivation of the retinoblastoma gene ( RB1 ) product, pRB, is common in many human cancers. Targeting downstream effectors of pRB that are central to tumorigenesis is a promising strategy to block the growth of tumors harboring loss-of-function RB1 mutations. One such effector is retinoblastoma-binding protein 2 (RBP2, also called JARID1A or KDM5A), which encodes an H3K4 demethylase. Binding of pRB to RBP2 has been linked to the ability of pRB to promote senescence and differentiation. Importantly, genetic ablation of RBP2 is sufficient to phenocopy pRB's ability to induce these cellular changes in cell culture experiments. Moreover, germline Rbp2 deletion significantly impedes tumorigenesis in Rb1 +/- mice. The value of RBP2 as a therapeutic target in cancer, however, hinges on whether loss of RBP2 could block the growth of established tumors as opposed to simply delaying their onset. Here we show that conditional, systemic ablation of RBP2 in tumor-bearing Rb1 +/- mice is sufficient to slow tumor growth and significantly extend survival without causing obvious toxicity to the host. These findings show that established Rb1 -null tumors require RBP2 for growth and further credential RBP2 as a therapeutic target in human cancers driven by RB1 inactivation.

  6. Cover sequences at the northern margin of the Antongil Craton, NE Madagascar

    Science.gov (United States)

    Bauer, W.; Walsh, G.J.; De Waele, B.; Thomas, Ronald J.; Horstwood, M.S.A.; Bracciali, L.; Schofield, D.I.; Wollenberg, U.; Lidke, D.J.; Rasaona, I.T.; Rabarimanana, M.H.

    2011-01-01

    The island of Madagascar is a collage of Precambrian, generally high-grade metamorphic basement domains, that are locally overlain by unmetamorphosed sedimentary rocks and poorly understood low-grade metasediments. In the Antalaha area of NE Madagascar, two distinct cover sequences rest on high-grade metamorphic and igneous basement rocks of the Archaean Antongil craton and the Neoproterozoic Bemarivo belt. The older of these two cover sequences, the Andrarona Group, consists of low-grade metasedimentary rocks. The younger sequence, the newly defined Ampohafana Formation, consists of unmetamorphosed sedimentary rocks. The Andrarona Group rests on Neoarchaean granites and monzogranites of the Antongil craton and consists of a basal metagreywacke, thick quartzites and an upper sequence of sericite-chlorite meta-mudstones, meta-sandstones and a volcaniclastic meta-sandstone. The depositional age of the volcaniclastic meta-sandstone is constrained in age by U–Pb laser-ablation ICP-MS analyses of euhedral zircons to 1875 ± 8 Ma (2σ). Detrital zircons of Archaean and Palaeoproterozoic age represent an input from the Antongil craton and a newly defined Palaeoproterozoic igneous unit, the Masindray tonalite, which underlies the Andrarona Group, and yielded a U–Pb zircon age of 2355 ± 11 Ma (2σ), thus constraining the maximum age of deposition of the basal part of the Andrarona Group. The Andrarona Group shows a low-grade metamorphic overprint in the area near Antalaha; illite crystallinity values scatter around 0.17°Δ2Θ CuKα, which is within the epizone. The Ampohafana Formation consists of undeformed, polymict conglomerate, cross-bedded sandstone, and red mudstone. An illite crystallinity value of >0.25°Δ2Θ CuKα obtained from the rocks is typical of the diagenetic zone. Occurrences of rhyodacite pebbles in the Ampohafana Formation and the intrusion of a basaltic dyke suggest a deposition in a WSW-ENE-trending graben system during the opening of the Indian

  7. Zero energy reactor 'RB'

    Energy Technology Data Exchange (ETDEWEB)

    Popovic, D; Takac, S; Markovic, H; Raisic, N; Zdravkovic, Z; Radanovic, Lj [Boris Kidric Institute of Nuclear Sciences, Vinca, Beograd (Yugoslavia)

    1959-03-15

    In 1958 the zero energy reactor RB was built with the purpose of enabling critical experiments with various reactor systems to be carried out. The first core assembly built in this reactor consists of heavy water as moderator and natural uranium metal as fuel. In order to be able to obtain very accurate results when measuring the main characteristics of the assembly the reactor was built as a completely bare system. (author)

  8. Short-Wavelength Infrared (SWIR) spectroscopy of low-grade metamorphic volcanic rocks of the Pilbara Craton

    NARCIS (Netherlands)

    Abweny, Mohammad S.; van Ruitenbeek, Frank J A; de Smeth, Boudewijn; Woldai, Tsehaie; van der Meer, Freek D.; Cudahy, Thomas; Zegers, Tanja; Blom, Jan Kees; Thuss, Barbara

    This paper shows the results of Short-Wavelength Infrared (SWIR) spectroscopy investigations of volcanic rocks sampled from low-grade metamorphic greenstone belts of the Archean Pilbara Craton in Western Australia. From the reflectance spectra a range of spectrally active minerals were identified,

  9. Microbial transformation of ginsenoside Rb1 to compound K by Lactobacillus paralimentarius.

    Science.gov (United States)

    Quan, Lin-Hu; Kim, Yeon-Ju; Li, Guan Hao; Choi, Kwang-Tea; Yang, Deok-Chun

    2013-06-01

    In this study, the major ginsenoside Rb1 was transformed into the more pharmacologically active minor compound K by food grade Lactobacillus paralimentarius LH4, which was isolated from kimchi, a traditional Korean fermented food. The enzymatic reaction was analyzed by TLC, HPLC, and NMR. Using the cell-free enzyme of Lactobacillus paralimentarius LH4 at optimal conditions for 30 °C at pH 6.0, 1.0 mg ml(-1) ginsenoside Rb1 was transformed into 0.52 mg ml(-1) compound K within 72 h, with a corresponding molar conversion yield of 88 %. The cell-free enzyme hydrolyzed the two glucose moieties attached to the C-3 position and the outer glucose moiety attached to the C-20 position of the ginsenoside Rb1. The cell-free enzyme hydrolyzed the ginsenoside Rb1 along the following pathway: ginsenoside Rb1 → gypenoside XVII and ginsenoside Rd → ginsenoside F2 → compound K. Our results indicate that Lactobacillus paralimentarius LH4 has the potential to be applied for the preparation of compound K in the food industry.

  10. The Lu-Hf isotope composition of cratonic lithosphere: disequilibrium between garnet and clinopyroxene in kimberlite xenoliths

    NARCIS (Netherlands)

    Simon, N.S.C.; Carlson, R.W.; Pearson, D.G.; Davies, G.R.

    2002-01-01

    12th Annual V.M. Goldschmidt Conference Davos Switzerland, The Lu-Hf isotope composition of cratonic lithosphere: disequilibrium between garnet and clinopyroxene in kimberlite xenoliths (DTM, Carnegie Institution of Washington), Pearson, D.G. (University of Durham)

  11. Ginsenoside Rb1 for Myocardial Ischemia/Reperfusion Injury: Preclinical Evidence and Possible Mechanisms

    Directory of Open Access Journals (Sweden)

    Qun Zheng

    2017-01-01

    Full Text Available Ginseng is an important herbal drug that has been used worldwide for many years. Ginsenoside Rb1 (G-Rb1, the major pharmacological extract from ginseng, possesses a variety of biological activities in the cardiovascular systems. Here, we conducted a preclinical systematic review to investigate the efficacy of G-Rb1 for animal models of myocardial ischemia/reperfusion injury and its possible mechanisms. Ten studies involving 211 animals were identified by searching 6 databases from inception to May 2017. The methodological quality was assessed by using the CAMARADES 10-item checklist. All the data were analyzed using RevMan 5.3 software. As a result, the score of study quality ranged from 3 to 7 points. Meta-analyses showed that G-Rb1 can significantly decrease the myocardial infarct size and cardiac enzymes (including lactate dehydrogenase, creatine kinase, and creatine kinase-MB when compared with control group (P<0.01. Significant decrease in cardiac troponin T and improvement in the degree of ST-segment depression were reported in one study (P<0.05. Additionally, the possible mechanisms of G-Rb1 for myocardial infarction are antioxidant, anti-inflammatory, antiapoptosis, promoting angiogenesis and improving the circulation. Thus, G-Rb1 is a potential cardioprotective candidate for further clinical trials of myocardial infarction.

  12. Paleomagnetism and geochronological studies on a 450 km long 2216 Ma dyke from the Dharwar craton, southern India

    Science.gov (United States)

    Nagaraju, E.; Parashuramulu, V.; Kumar, Anil; Srinivas Sarma, D.

    2018-01-01

    Paleomagnetic and geochronological studies were carried out on a ∼ 450 km long (from 17 sites) N-S striking Paleoproterozoic dyke swarm exposed along a natural crustal cross section of about 10 km (increasing from North to South) in the Dharwar Craton, to study the characteristics of paleomagnetism and geochronology in vertical dimension. U-Pb/Pb-Pb dating on baddeleyite gives a crystallisation age of 2216.0 ± 0.9 Ma for long dyke AKLD. Paleomagnetic data from this well dated ∼ 2216 Ma dyke swarm in Dharwar Craton are of excellent quality. High coercivity and high blocking temperature components are carried by single domain magnetite and show dual polarity remanence directions. Combined normal and reverse polarity remanences on AKLD and other N-S dykes define the most reliable paleomagnetic pole for ∼ 2216 Ma at latitude 36°S and longitude 312°E (A95 = 7°). Though paleomagnetic data is unavailable on other N-S dykes below the Cuddapah basin, high precision geochronology suggest that they are of similar age within errors. Though there is a variation in the crustal depth of Dharwar craton from north to south, consistent Pb-Pb/U-Pb baddeleyite geochronology and paleomagnetic studies along the AKLD established its continuity and preservation along its entire strike length. The virtual geomagnetic poles of these sites confirm a stable remanence and are almost identical to the previously reported paleomagnetic pole and also supported by positive reversal test. Positive paleomagnetic reversal test on these dykes signify that the remanent magnetization is primary and formed during initial cooling of the intrusions. Updated apparent polar wander path of Dharwar craton indicates relatively low drift rate during 2.21-2.08 Ga interval. Magnetogranulometry and SEM studies show that remanent magnetization in this dyke was carried by single domain magnetite residing within silicate minerals.

  13. RB Research nuclear reactor, Annual report for 1995, I-IV; Istrazivacki nuklearni reaktor RB, Izvestaj o radu u 1995. godini, I-IV

    Energy Technology Data Exchange (ETDEWEB)

    Stefanovic, D; Milosevic, M; Pesic, M [Institute of Nuclear Sciences Vinca, Belgrade (Yugoslavia); Marinkovic, P [Elektrotehnicki fakultet, Beograd (Yugoslavia); Ilic, R; Dasic, N; Milovanovic, S; Ljubenov, V; Petronijevic, M; Jevremovic, M [Institute of Nuclear Sciences Vinca, Belgrade (Yugoslavia)

    1995-12-15

    Report on RB reactor operation during 1995 contains 3 parts. Part one contains a brief description of reactor operation and reactor components, relevant dosimetry data and radiation protection issues, personnel and financial data. Part two is devoted to maintenance of the reactor components, namely, fuel, heavy water, reactor vessel, heavy water circulation system, absorption rods and heavy water level-meters, maintenance of electronic, mechanical, electrical and auxiliary equipment. Part three contains data concerned with reactor operation and utilization with a comprehensive list of publications resulting from experiments done at the RB reactor.

  14. Studies of rubidium selenate with secondary phase of RbOH under humidified reducing atmosphere

    DEFF Research Database (Denmark)

    Beyribey, Berceste; Hallinder, Jonathan; Poulsen, Finn Willy

    2012-01-01

    The high temperature properties of Rb2SeO4 have been studied by calorimetry, impedance spectroscopy and X-ray powder diffraction. As synthesized, Rb2SeO4 includes a second phase of Rb2SeO3, which can be eliminated upon heating the compound. As expected, no conductivity is observed in dry (pH2O ....001 bar) air. By changing to humidified (pH2O = 0.1 bar) air at 176 deg. C, the conductivity increases sharply from 8.6·10-8 to 1.7·10-6 S cm-1. Under humidified (pH2O = 0.1 bar) reducing atmosphere (9%H2 in N2), the conductivity increases to 2.0·10-4 S cm-1 at 317 C. Degradation of Rb2SeO3 and Rb2SeO4...

  15. NaPdPS{sub 4} and RbPdPS{sub 4}: systems with infinite straight ((1)/({infinity}))[PdPS{sub 4}]{sup -} chains soluble in polar solvents and the structure of cubic RbPdPS{sub 4}{l_brace}Rb{sub 0.33}P{sub 0.4}S{sub 2.23}O{sub x}{r_brace}

    Energy Technology Data Exchange (ETDEWEB)

    Coste, Servane; Hanko, Jason; Bujoli-Doeuff, Martine; Louarn, Guy; Evain, Michel; Brec, Raymond; Alonso, Bruno; Jobic, S; Kanatzidis, Mercouri G

    2003-11-01

    The synthesis, crystal structures, chemical and spectroscopic properties of NaPdPS{sub 4}, RbPdPS{sub 4}, and RbPdPS{sub 4}{l_brace}Rb{sub 0.33}P{sub 0.4}S{sub 2.23}O{sub x}{r_brace} are described. NaPdPS{sub 4}, RbPdPS{sub 4}, are isostructural and crystallize in the tetragonal system I4/mcm with cell parameters a=7.3074(8) A, c=12.2308(14) A and a=8.2954(3) A, c=12.2284(4) A respectively. RbPdPS{sub 4}{l_brace}Rb{sub 0.33}P{sub 0.4}S{sub 2.23}O{sub x}{r_brace} is cubic, space group Pm-3n and a=12.0042(2) A. All compounds contain the same ((1)/({infinity}))[PdPS{sub 4}]{sup -} chains made of alternating square planar Pd{sup 2+} cations and tetrahedral [PS{sub 4}]{sup 3-} anions. RbPdPS{sub 4}{l_brace}Rb{sub 0.33}P{sub 0.4}S{sub 2.23}O{sub x}{r_brace} contains co-crystallized highly disordered molecular species encapsulated within [Rb{sub 8}] cubic cavities. Spectroscopic solid state {sup 31}P NMR, infrared and Raman data as well as elemental analysis suggest that these species could be S{sub n}{sup 2-} (n=3 or 4) anions and possibly cationic [P{sub 4}S{sub 6}O]{sup 6+} fragments. NaPdPS{sub 4} and RbPdPS{sub 4} exhibit exfoliative dissolution in polar solvents giving rise to solutions that show signs of complex fluid behavior.

  16. Geochemistry of the Serra das Melancias Pluton in the Serra da Aldeia Suite: a classic post-collisional high Ba-Sr granite in The Riacho do Pontal Fold Belt, NE Brazil

    Directory of Open Access Journals (Sweden)

    Marcela Paschoal Perpétuo

    Full Text Available ABSTRACT: The Serra da Aldeia Suite is composed by circular or oval-shaped plutons, intrusive in meta-sedimentary and meta-volcanosedimentary rocks in the Riacho do Pontal Fold Belt, NE Brazil. The Serra das Melancias Pluton, belonging to Serra da Aldeia Suite, is located southeastern of Piaui state, near Paulistana city. These plutons represent a major magmatic expression in this area and contain important information about the late magmatic/collisional geologic evolution of the Brasiliano Orogeny. Based on petrographic and geochemical data, three facies were defined in the Serra das Melancias Pluton: granites, syenites and quartz monzonites. The rocks display high-K and alkaline to shoshonitic affinities, are metaluminous and show ferrous character. They are enriched in Light Rare Earth Elements and Large Ion Lithophile Elements, with negative anomalies in Nb, Ta and Ti. Their high Ba, Sr, K/Rb, low Rb, relatively low U, Th, Nb to very low Heavy Rare Earth Elements and Y resemble those of typical high Ba-Sr granitoids. The geochemical data suggest the emplacement of Serra das Melancias Pluton in a transitional, late to post-orogenic setting in the Riacho do Pontal Fold Belt during the late Brasiliano-Pan African Orogeny.

  17. Production of 81Rb/sup 81m/Kr generators with 60-MeV protons at BLIP

    International Nuclear Information System (INIS)

    Mausner, L.F.; Richards, P.

    1983-01-01

    By bombarding natural krypton gas with approx. 63 MeV protons, 81 Rb is formed by (p,4n) reaction from high abundance 84 Kr (57%) as well as some additional contribution from 83 Kr (11.5%) and 82 Kr (11.6%) by (p,3n) and (p,2n) reactions, respectively. The production rate of 81 Rb is typically 1.5 mCi/μAh. This production rate is sufficient to create up to several hundred millicuries per run if necessary, enough for several high activity 81 Rb/sup 81m/Kr generators. Presently generators that deliver 10 to 20 mCi to the lungs are produced weekly for on-site use. The only other important activity in the solution is Rb-82m (6.4 hr). Small amounts of Br-76 (16.1 hr), Br-77 (57 hr), Br-82 (35.5 hr), Rb-83 (86.2 d), and Rb-84 (33 d) were also present. The bromine impurities pose no problem since they are not trapped on the generator. Rb-82m and Rb-84 decay to stable Kr-82 and Kr-84 in the generator and do not interfere with Kr-81m studies

  18. Topologically identical, but geometrically isomeric layers in hydrous α-, β-Rb[UO2(AsO3OH)(AsO2(OH)2)]·H2O and anhydrous Rb[UO2(AsO3OH)(AsO2(OH)2)

    Science.gov (United States)

    Yu, Na; Klepov, Vladislav V.; Villa, Eric M.; Bosbach, Dirk; Suleimanov, Evgeny V.; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.; Alekseev, Evgeny V.

    2014-07-01

    The hydrothermal reaction of uranyl nitrate with rubidium nitrate and arsenic (III) oxide results in the formation of polymorphic α- and β-Rb[UO2(AsO3OH)(AsO2(OH)2)]·H2O (α-, β-RbUAs) and the anhydrous phase Rb[UO2(AsO3OH)(AsO2(OH)2)] (RbUAs). These phases were structurally, chemically and spectroscopically characterized. The structures of all three compounds are based upon topologically identical, but geometrically isomeric layers. The layers are linked with each other by means of the Rb cations and hydrogen bonding. Dehydration experiments demonstrate that water deintercalation from hydrous α- and β-RbUAs yields anhydrous RbUAs via topotactic reactions.

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

    Directory of Open Access Journals (Sweden)

    Leite Renato J.

    2006-01-01

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

  20. Dosimetry system of the RB reactor

    International Nuclear Information System (INIS)

    Lolic, B.; Vukadin, D.

    1962-01-01

    Although RB reactor is operated at very low power levels, safety and dosimetry systems have high importance. This paper shows detailed dosimetry system with fundamental typical components. Estimated radiation doses dependent on reactor power are given at some characteristic points in the rooms nearby reactor

  1. Trace element and isotopic compositions of Vietnamese basalts: implications for mantle dynamics in the southeast Asian region

    International Nuclear Information System (INIS)

    Nguyen, H.; Fower, M.; Nguyen, H.; Nguyen, X.B.; Nguyen, T.Y.

    1996-01-01

    Cenozoic basalts in Indo-China are part of a regional melting episode along the rifted Eurasian margin. Trace element and isotopic compositions of Vietnamese basalts are used to place constraints on the extent of lithospheric and asthenosphere contributions to the melts and possible mantle dynamic implications. The 87 Sr/ 86 Sr, 207 Pb/ 204 Pb, and 208 Pb/ 204 Pb isotopic ratios of the basalts reflect minimal crustal wall rock reaction, and variable enrichment in EM1 and EM2 of a 208 Pb-rich MORB-like source. Some, but not all, of this variation corresponds to the age of lithospheric sector penetrated. Basalts erupted through a cratonic, central sector (e.g. at Quang Ngai, Pleiku, Song Cau, Kong Plong, and Buon Ma Thuot) and off-cratonic, southwest sector (e.g. Phuoc Long) resemble those of EM2-rich basalts from southern and southeaster China and the South China Sea. Basalts from an off-cratonic, southeast sector (e.g. from Dalat, Xuan Loc, and the offshore Ile des Cendres-Phu Cuy complex) reflect mixing between a low- 206 Pb/ 204 Pb, high- 208 Pb/ 204 Pb, EM1-like component, and resemble basalts from northwest Taiwan, eastern and northeastern China, and parts of the Japan Sea. While EM2 tends to characterise lithospheric sectors, presence of EM1 in off-cratonic rather than cratonic basalts implies an asthenosphere rather than lithospheric source. Pervasive presence of EM1 in southeast Asian and marginal basin asthenosphere corresponds with thermally-anomalous mantle and may involve delaminated cratonic substrate entrained by mobile, extruded asthenosphere. (authors)

  2. Brain Transport Profiles of Ginsenoside Rb1 by Glucose Transporter 1: In Vitro and in Vivo

    Directory of Open Access Journals (Sweden)

    Yu-Zhu Wang

    2018-04-01

    Full Text Available Ginsenoside Rb1 (Rb1 has been demonstrated its protection for central nervous system and is apparently highly distributed to the brain. The objective of this study was to characterize Rb1 transport at the blood–brain barrier (BBB using primary cultured rat brain microvascular endothelial cells (rBMEC, an in vitro BBB model. The initial uptake velocity of Rb1 in rBMEC was temperature- and concentration-dependent, and was significantly reduced by phloretin, an inhibitor of GLUT1 transporter, but was independent of metabolic inhibitor. Furthermore, the transport of Rb1 into rBMEC was significantly diminished in the presence of natural substrate α-D-glucose, suggesting a facilitated transport of Rb1 via GLUT1 transporter. The impact of GLUT1 on the distribution of Rb1 between brain and plasma was studied experimentally in rats. Administration of phloretin (5 mg/kg, i.v. to normal rats for consecutive 1 week before Rb1 (10 mg/kg, i.v. at 0.5, 2, and 6 h did not alter Rb1 concentrations in plasma, but resulted in significant decreased brain concentrations of Rb1 compared to in the phloretin-untreated normal rats (489.6 ± 58.3 versus 105.1 ± 15.1 ng/g, 193.8 ± 11.1 versus 84.8 ± 4.1 ng/g, and 114.2 ± 24.0 versus 39.9 ± 4.9 ng/g, respectively. The expression of GLUT1 in the phloretin-treated group by western blotting analysis in vitro and in vivo experiments was significantly decreased, indicating that the decreased transport of Rb1 in brain was well related to the down-regulated function and level of GLUT1. Therefore, our in vitro and in vivo results indicate that the transport of Rb1 at the BBB is at least partly mediated by GLUT1 transporter.

  3. Rb-Sr and Sm-Nd isotopic relations and ages of the Brasiliano granitic magmatism of the eastern region of the Dom Feliciano belt in the Rio Grande do Sul State, South region Brazil: evidences of the reworking of a paleoproterozoic continental crust, South region, Brazil

    International Nuclear Information System (INIS)

    Frantz, Jose Carlos; Koester, Edinei; Teixeira, Roberto Santos; Botelho, Nilson Francisquini; Pimentel, Marcio Martins; Potrel, Alan

    1999-01-01

    The granitoids belonging to the brasiliano cycle from the eastern region at the Dom Feliciano Belt in the Rio Grande do Sul state have had Rb-Sr data that indicated bodies which were intruded between 800 and 585 Ma. The T DM ages are suggesting the participation of an older source in their generation. This source could be represented by a long period enriched mantle, much than would be expected during the evolution of the magmatic arcs, or could be represented by the interaction between an older continental crust and mantle during a continental collision regime. The tectonic evolution of this area., the existence of a long period of time between the granitic intrusions associated to the tangential regime and to the transpressive regime and to the transpressive regime ones, the isotopic relations between Sr and nd and the very low negative values of ε N dt are suggesting a strong participation of an older continental crust. This older continental crust, may be constituted by gneissic protoliths of paleoproterozoic ages and generated during the evolution of the Transamazonic Cycle, has participated in the formation of the sources of the granitic magmatism of this part of the belt. The variations of the T DM ages and of the Nd ratios in the calc-alkaline granitoids are suggesting different proportions of mixture between and older continental crust and mantle or different homogenization grades in the magmas sources. For the peraluminous granites, that have be resulted from continental crustal melt, there are indications of different sources to the different bodies. (author)

  4. Archaean ultra-depleted komatiites formed by hydrous melting of cratonic mantle.

    Science.gov (United States)

    Wilson, A H; Shirey, S B; Carlson, R W

    2003-06-19

    Komatiites are ultramafic volcanic rocks containing more than 18 per cent MgO (ref. 1) that erupted mainly in the Archaean era (more than 2.5 gigayears ago). Although such compositions occur in later periods of Earth history (for example, the Cretaceous komatiites of Gorgona Island), the more recent examples tend to have lower MgO content than their Archaean equivalents. Komatiites are also characterized by their low incompatible-element content, which is most consistent with their generation by high degrees of partial melting (30-50 per cent). Current models for komatiite genesis include the melting of rock at great depth in plumes of hot, diapirically rising mantle or the melting of relatively shallow mantle rocks at less extreme, but still high, temperatures caused by fluxing with water. Here we report a suite of ultramafic lava flows from the Commondale greenstone belt, in the southern part of the Kaapvaal Craton, which represents a previously unrecognized type of komatiite with exceptionally high forsterite content of its igneous olivines, low TiO(2)/Al(2)O(3) ratio, high silica content, extreme depletion in rare-earth elements and low Re/Os ratio. We suggest a model for their formation in which a garnet-enriched residue left by earlier cratonic volcanism was melted by hydration from a subducting slab.

  5. Complete neutronic nuclear data evaluation for 85Rb and 87Rb from 10-5 eV to 20 MeV

    International Nuclear Information System (INIS)

    Simon, Gerard; Prince, Augustus; Lalie, Evelyne.

    1981-04-01

    The total, elastic, inelastic, capture, (n,p), (n,d), (n,t), (n, 3 He), (n,α), (n,2n), (n,n'p), (n,n'α) cross-sections have been evaluated for 85 Rb and 87 Rb in the 10 -5 eV - 20 MeV energy range. This evaluation is based on available experimental data and theoretical calculations carried out in the framework of spherical optical model and statistical model. Angular distributions for elastic and discret inelastic scattering, and energy distributions for continuum inelastic scattering and for (n,2n) reaction have also been calculated. This evaluation, set under ENDF/BIV format, completes and plainly improves the corresponding evaluation given in the ENDF/BIV files [fr

  6. Rb and p53 Liver Functions Are Essential for Xenobiotic Metabolism and Tumor Suppression.

    Directory of Open Access Journals (Sweden)

    Sathidpak Nantasanti

    Full Text Available The tumor suppressors Retinoblastoma (Rb and p53 are frequently inactivated in liver diseases, such as hepatocellular carcinomas (HCC or infections with Hepatitis B or C viruses. Here, we discovered a novel role for Rb and p53 in xenobiotic metabolism, which represent a key function of the liver for metabolizing therapeutic drugs or toxins. We demonstrate that Rb and p53 cooperate to metabolize the xenobiotic 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC. DDC is metabolized mainly by cytochrome P450 (Cyp3a enzymes resulting in inhibition of heme synthesis and accumulation of protoporphyrin, an intermediate of heme pathway. Protoporphyrin accumulation causes bile injury and ductular reaction. We show that loss of Rb and p53 resulted in reduced Cyp3a expression decreased accumulation of protoporphyrin and consequently less ductular reaction in livers of mice fed with DDC for 3 weeks. These findings provide strong evidence that synergistic functions of Rb and p53 are essential for metabolism of DDC. Because Rb and p53 functions are frequently disabled in liver diseases, our results suggest that liver patients might have altered ability to remove toxins or properly metabolize therapeutic drugs. Strikingly the reduced biliary injury towards the oxidative stress inducer DCC was accompanied by enhanced hepatocellular injury and formation of HCCs in Rb and p53 deficient livers. The increase in hepatocellular injury might be related to reduce protoporphyrin accumulation, because protoporphrin is well known for its anti-oxidative activity. Furthermore our results indicate that Rb and p53 not only function as tumor suppressors in response to carcinogenic injury, but also in response to non-carcinogenic injury such as DDC.

  7. Phase precipitation of Yb 2+ ions in RbCl monocrystals monitored ...

    African Journals Online (AJOL)

    Optical absorption spectra of RbCl:Yb2+ crystals have been measured at several elevated temperatures up to 300C. Results showed that in hot RbCl:Yb2+ crystals, the Yb2+ ions occupied lattice sites with effective octahedral, O, point symmetry. Values of an energy parameter , which is an approximate measure of the ...

  8. Operation of the Ca-dependent K(Rb)-transport in human lymphocytes

    Energy Technology Data Exchange (ETDEWEB)

    Szasz, I.; Sarkadi, B.; Gardos, G. (Orszagos Haematologiai es Vertranszfuzios Intezet, Budapest (Hungary))

    1982-01-01

    The transport pathways of the plasma membrane of human lymphocytes were studied based on /sup 86/Rb and /sup 45/Ca fluxes. Net Ca-uptake increases K(Rb)-permeability (Gardos-effect) and the membrane potential increases due to the subsequent K-efflux, enabling further Ca-uptake. The possible role of the above effects during lymphocyte stimulation is discussed.

  9. Determination of the Rb atomic number density in dense rubidium vapors by absorption measurements of Rb2 triplet bands

    International Nuclear Information System (INIS)

    Horvatic, Vlasta; Veza, Damir; Niemax, Kay; Vadla, Cedomil

    2008-01-01

    A simple and accurate way of determining atom number densities in dense rubidium vapors is presented. The method relies on the experimental finding that the reduced absorption coefficients of the Rb triplet satellite bands between 740 nm and 750 nm and the triplet diffuse band between 600 nm and 610 nm are not temperature dependent in the range between 600 K and 800 K. Therefore, the absolute values of the reduced absorption coefficients of these molecular bands can provide accurate information about atomic number density of the vapor. The rubidium absorption spectrum was measured by spatially resolved white-light absorption in overheated rubidium vapor generated in a heat pipe oven. The absolute values for the reduced absorption coefficients of the triplet bands were determined at lower vapor densities, by using an accurate expression for the reduced absorption coefficient in the quasistatic wing of the Rb D1 line, and measured triplet satellite bands to the resonance wing optical depth ratio. These triplet satellite band data were used to calibrate in absolute scale the reduced absorption coefficients of the triplet diffuse band at higher temperatures. The obtained values for the reduced absorption coefficient of these Rb molecular features can be used for accurate determination of rubidium atomic number densities in the range from about 5 x 10 16 cm -3 to 1 x 10 18 cm -3

  10. /sup 87/Rb NMR study at the cubic to tetragonal phase transition in RbCaF/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Bulou, A [Angers Univ., 72 - Le Mans (France). Centre Universitaire; Theveneau, H; Trokiner, A; Papon, P [Ecole Superieure de Physique et Chimie Industrielles, 75 - Paris (France)

    1979-07-01

    The /sup 87/Rb nuclear magnetic resonance spectrum, in perovskite single crystal of RbCaF/sub 3/, is studied above and below the cubic-to-tetragonal phase transition occurring at 198 K. In the high-temperature cubic phase, the temperature dependence of the resonance line amplitude deviates from the Curie law and this can be attributed to the existence of tetragonal domains. In the low temperature tetragonal phase, a second-order quadrupole shift of the central line is observed, from which the CaF/sub 6/ tilt angle (order parameter) is derived. The order parameter temperature dependence is described by a power law with a cross over from exponent 0.5 to exponent 0.32 at 150 K. The tilt angle PHI is compared to the values obtained from X-ray and neutron powder diffraction data.

  11. A Measurement of $R_b$ using Mutually Exclusive Tags

    CERN Document Server

    Barate, R; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Nief, J Y; Pietrzyk, B; Casado, M P; Chmeissani, M; Comas, P; Crespo, J M; Delfino, M C; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Miquel, R; Mir, L M; Orteu, S; Padilla, C; Park, I C; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Gelao, G; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Alemany, R; Becker, U; Bazarko, A O; Bright-Thomas, P G; Cattaneo, M; Cerutti, F; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Lutters, G; Mato, P; Minten, Adolf G; Moneta, L; Pacheco, A; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rizzo, G; Rolandi, Luigi; Schlatter, W D; Schmitt, M; Schneider, O; Tejessy, W; Tomalin, I R; Wachsmuth, H W; Wagner, A; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Ferdi, C; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rosnet, P; Rossignol, J M; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Rensch, B; Wäänänen, A; Daskalakis, G; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Zachariadou, K; Corden, M; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Casper, David William; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Knowles, I G; Lynch, J G; O'Shea, V; Raine, C; Scarr, J M; Smith, K; Teixeira-Dias, P; Thompson, A S; Thomson, E; Thomson, F; Turnbull, R M; Geweniger, C; Graefe, G; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Schmidt, M; Sommer, J; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Girone, M; Goodsir, S M; Martin, E B; Moutoussi, A; Nash, J; Sedgbeer, J K; Stacey, A M; Williams, M D; Dissertori, G; Ghete, V M; Girtler, P; Kuhn, D; Rudolph, G; Betteridge, A P; Bowdery, C K; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Williams, M I; Galla, A; Giehl, I; Greene, A M; Hoffmann, C; Jakobs, K; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Coyle, P; Diaconu, C A; Etienne, F; Konstantinidis, N P; Leroy, O; Motsch, F; Payre, P; Rousseau, D; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Aleppo, M; Ragusa, F; Berlich, R; Blum, Walter; Brown, D; Büscher, V; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Stenzel, H; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Chen, S; Choi, Y; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Höcker, A; Jacholkowska, A; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Schune, M H; Simion, S; Tournefier, E; Veillet, J J; Videau, I; Zerwas, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Palla, Fabrizio; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Venturi, A; Verdini, P G; Blair, G A; Bryant, L M; Chambers, J T; Gao, Y; Green, M G; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Maley, P; Norton, P R; Thompson, J C; Wright, A E; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Black, S N; Dann, J H; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Boswell, R; Brew, C A J; Cartwright, S L; Combley, F; Kelly, M S; Lehto, M H; Newton, W M; Reeve, J; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Grupen, Claus; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Charles, E; Elmer, P; Ferguson, D P S; Gao, Y S; González, S; Greening, T C; Hayes, O J; Hu, H; Jin, S; McNamara, P A; Nachtman, J M; Nielsen, J; Orejudos, W; Pan, Y B; Saadi, Y; Scott, I J; Walsh, J; Wu Sau Lan; Wu, X; Yamartino, J M; Zobernig, G

    1997-01-01

    A measurement of $R_b$ using five mutually exclusive hemisphere tags has been pe rformed by ALEPH using the full LEP1 statistics. Three tags are designed to sele ct the decay of the $Z^0$ to $b$ quarks, while the remaining two select $Z^0$ decays to $c$ and light quarks, and are used to measure the tagging efficiencies. The result, {$R_b~=~0.2159~\\pm~0.0009\\mbox{(stat)}~\\pm 0.0011\\mbox{(syst)}$}, is in agreement with the electroweak theory prediction of $0.2158 \\pm 0.0003$.

  12. A measurement of Rb using a lifetime-mass tag

    Science.gov (United States)

    Barate, R.; Buskulic, D.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Lucotte, A.; Minard, M.-N.; Nief, J.-Y.; Pietrzyk, B.; Casado, M. P.; Chmeissani, M.; Comas, P.; Crespo, J. M.; Delfino, M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Juste, A.; Martinez, M.; Miquel, R.; Mir, Ll. M.; Orteu, S.; Padilla, C.; Park, I. C.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Gelao, G.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Alemany, R.; Becker, U.; Bazarko, A. O.; Bright-Thomas, P.; Cattaneo, M.; Cerutti, F.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Harvey, J.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Lutters, G.; Mato, P.; Minten, A.; Moneta, L.; Pacheco, A.; Pusztaszeri, J.-F.; Ranjard, F.; Rensing, P.; Rizzo, G.; Rolandi, L.; Schlatter, D.; Schmitt, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Wachsmuth, H.; Wagner, A.; Ajaltouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Ferdi, C.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rosnet, P.; Rossignol, J.-M.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Rensch, B.; Wäänänen, A.; Daskalakis, G.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Focardi, E.; Parrini, G.; Zachariadou, K.; Corden, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Casper, D.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Scarr, J. M.; Smith, K.; Teixeira-Dias, P.; Thompson, A. S.; Thomson, E.; Thomson, F.; Turnbull, R. M.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Schmidt, M.; Sommer, J.; Tittel, K.; Werner, S.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Girone, M.; Goodsir, S.; Martin, E. B.; Moutoussi, A.; Nash, J.; Sedgbeer, J. K.; Stacey, A. M.; Williams, M. D.; Dissertori, G.; Ghete, V. M.; Girtler, P.; Kuhn, D.; Rudolph, G.; Betteridge, A. P.; Bowdery, C. K.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Sloan, T.; Williams, M. I.; Galla, A.; Giehl, I.; Greene, A. M.; Hoffmann, C.; Jakobs, K.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Coyle, P.; Diaconu, C.; Etienne, F.; Konstantinidis, N.; Leroy, O.; Motsch, F.; Payre, P.; Rousseau, D.; Talby, M.; Sadouki, A.; Thulasidas, M.; Trabelsi, K.; Aleppo, M.; Ragusa, F.; Berlich, R.; Blum, W.; Brown, D.; Büscher, V.; Dietl, H.; Dydak, F.; Ganis, G.; Gotzhein, C.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; St. Denis, R.; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Chen, S.; Choi, Y.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Höcker, A.; Jacholkowska, A.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Nikolic, I.; Schune, M.-H.; Simion, S.; Tournefier, E.; Veillet, J.-J.; Videau, I.; Zerwas, D.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; dell'Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Vannini, C.; Venturi, A.; Verdini, P. G.; Blair, G. A.; Bryant, L. M.; Chambers, J. T.; Gao, Y.; Green, M. G.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Maley, P.; Norton, P. R.; Thompson, J. C.; Wright, A. E.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Perez, P.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Black, S. N.; Dann, J. H.; Johnson, R. P.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Kelly, M. S.; Lehto, M.; Newton, W. M.; Reeve, J.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Cowan, G.; Grupen, C.; Saraiva, P.; Smolik, L.; Stephan, F.; Apollonio, M.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Charles, E.; Elmer, P.; Ferguson, D. P. S.; Gao, Y. S.; González, S.; Greening, T. C.; Hayes, O. J.; Hu, H.; Jin, S.; McNamara, P. A.; Nachtman, J. M.; Nielsen, J.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Scott, I. J.; Walsh, J.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zobernig, G.

    1997-02-01

    ALEPH's published measurement of Rb = Γ(Z -> bb)/Γ(Z -> hadrons) using a lifetime tag is updated using the full LEP 1 data sample. Considerable effort has been devoted to understanding systematic effects. Charm background is better controlled by combining the lifetime tag with a tag based on the b/c hadron mass difference. Furthermore, the algorithm used to reconstruct the event primary vertex is designed so as to reduce correlations between the two hemispheres of an event. The value of Rb is measured to be 0.2167 +/- 0.0011 (stat) +/- 0.0013 (syst).

  13. Particle-phonon coupling in the odd-A Rb isotopes

    International Nuclear Information System (INIS)

    Krishan, K.; Basu, S.K.; Sen, S.

    1976-01-01

    The level properties of 83 Rb and 85 Rb have been calculated in a quasiparticle-phonon coupling model which couples the proton quasiparticle motion in the 1fsub(5/2), 2psub(1/2), 2psub(3/2) and 1gsub(9/2) orbitals to the vibrations of the neighbouring even core. The calculated level spectra, spectroscopic factors and B(E2) values for several levels are found to be in good agreement with available experimental data. Branching ratios for transitions originating from several levels are also reproduced. (author)

  14. Rb*Hen exciplexes in solid 4He

    International Nuclear Information System (INIS)

    Hofer, A.; Moroshkin, P.; Nettels, D.; Ulzega, S.; Weis, A.

    2006-01-01

    We report the observation of emission spectra from Rb*He n exciplexes in solid 4 He. Two different excitation channels were experimentally identified, viz., exciplex formation via laser excitation to the atomic 5P 3/2 and to the 5P 1/2 levels. While the former channel was observed before in liquid helium, on helium nanodroplets, and in helium gas by different groups, the latter creation mechanism occurs only in solid helium or in gaseous helium above 10 K. The experimental results are compared to theoretical predictions based on the extension of a model, used earlier by us for the description of Cs*He n exciplexes. We also report the observation of fluorescence from atomic rubidium in solid helium, and discuss striking differences between the spectroscopic features of Rb-He and Cs-He systems

  15. Cloning and Molecular Characterization of the Schistosoma mansoni Genes RbAp48 and Histone H4

    Directory of Open Access Journals (Sweden)

    Patrícia P Souza

    2002-10-01

    Full Text Available The human nuclear protein RbAp48 is a member of the tryptophan/aspartate (WD repeat family, which binds to the retinoblastoma (Rb protein. It also corresponds to the smallest subunit of the chromatin assembly factor and is able to bind to the helix 1 of histone H4, taking it to the DNA in replication. A cDNA homologous to the human gene RbAp48 was isolated from a Schistosoma mansoni adult worm library and named SmRbAp48. The full length sequence of SmRbAp48 cDNA is 1036 bp long, encoding a protein of 308 amino acids. The transcript of SmRbAp48 was detected in egg, cercariae and schistosomulum stages. The protein shows 84% similarity with the human RbAp48, possessing four WD repeats on its C-terminus. A hypothetical tridimensional structure for the SmRbAp48 C-terminal domain was constructed by computational molecular modeling using the b-subunit of the G protein as a model. To further verify a possible interaction between SmRbAp48 and S. mansoni histone H4, the histone H4 gene was amplified from adult worm genomic DNA using degenerated primers. The gene fragment of SmH4 is 294 bp long, encoding a protein of 98 amino acids which is 100% identical to histone H4 from Drosophila melanogaster.

  16. Geochemistry of trace elements and Sr- Nd isotopes of foraminifera shell from the Okinawa Trough

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Trace elemental associations and Sr - Nd isotopic compositions are of important to recognition of biogenic material from mixed marine sediments. The foraminifera shell from the Okinawa Trough strongly enrichesSr, P, Mn andBa, enriches Li, U, Th, Sc, Co, Cu, Pb, Zn, Cr, Rb, Y, Sb and light rare earth elements, slightly enriches V, Ga, Zr, Nb, Cd and middle rare earth elements,is short of Mo, In, Sn, Cs, Hf, Ta, W, Ti, Bi and heavy rare earth elements. The mechanism of elemental enrichment in forminifera is the concentrations of trace elements in sea water and selective absorption of trace elements during foraminifera living, as well as the geochemical affinity between major elements and trace elements. The REE (rare earth elements) partition pattern of foraminifera shell of the Okinawa Trough shows enrichment of middle rare earth elements with slightly negative Ce anomaly,which are different from those of foraminifera of the Pacific Ocean. The Sr, Nd isotopic ratios of the Okinawa Trough foraminifera are 0.709 769 and 0.512 162, respectively, which are different not only from those of oceanic water, but also from those of river water of China's Mainland, the former is slightly higher than those of oceanic water, but much lower than those of river water; the latter is slightly lower than those of oceanic water, but higher than those of river water, demonstrating that the Okinawa Trough sea water has been influenced by river water of China's Mainland.

  17. Phase formation in the Li2MoO4-Rb2MoO4-Ln2(MoO4)3 systems and the properties of LiRbLn2(MoO4)4

    International Nuclear Information System (INIS)

    Basovich, O.M.; Khajkina, E.G.; Vasil'ev, E.V.; Frolov, A.M.

    1995-01-01

    Phase equilibria within subsolidus range of ternary salt systems Li 2 MoO 4 -Rb 2 MoO 4 -Ln 2 (MoO 4 ) 4 (Ln - Nd, Er) are analyzed. Formation of ternary molybdate LiRbNd 2 (MoO 4 ) 4 is proved along LiNd(MoO 4 ) 2 -RbNd(MoO 4 )-2 cross-section. Phase diagram of this cross-section is plotted. Similar compounds are synthesized for Ln = La-Eu. The parameters of their monoclinic elementary cells are determined. Luminescent properties of LiRbLa 2 (MoO 4 ) 4 -Nd 3+ are studied. 17 refs., 4 figs., 2 tabs

  18. Metastable honeycomb SrTiO_3/SrIrO_3 heterostructures

    International Nuclear Information System (INIS)

    Anderson, T. J.; Ryu, S.; Podkaminer, J. P.; Ma, Y.; Eom, C. B.; Zhou, H.; Xie, L.; Irwin, J.; Rzchowski, M. S.; Pan, X. Q.

    2016-01-01

    Recent theory predictions of exotic band topologies in (111) honeycomb perovskite SrIrO_3 layers sandwiched between SrTiO_3 have garnered much attention in the condensed matter physics and materials communities. However, perovskite SrIrO_3 film growth in the (111) direction remains unreported, as efforts to synthesize pure SrIrO_3 on (111) perovskite substrates have yielded films with monoclinic symmetry rather than the perovskite structure required by theory predictions. In this study, we report the synthesis of ultra-thin metastable perovskite SrIrO_3 films capped with SrTiO_3 grown on (111) SrTiO_3 substrates by pulsed laser deposition. The atomic structure of the ultra-thin films was examined with scanning transmission electron microscopy (STEM), which suggests a perovskite layering distinct from the bulk SrIrO_3 monoclinic phase. In-plane 3-fold symmetry for the entire heterostructure was confirmed using synchrotron surface X-ray diffraction to measure symmetry equivalent crystal truncation rods. Our findings demonstrate the ability to stabilize (111) honeycomb perovskite SrIrO_3, which provides an experimental avenue to probe the phenomena predicted for this material system.

  19. RB reactor benchmark cores

    International Nuclear Information System (INIS)

    Pesic, M.

    1998-01-01

    A selected set of the RB reactor benchmark cores is presented in this paper. The first results of validation of the well-known Monte Carlo MCNP TM code and adjoining neutron cross section libraries are given. They confirm the idea for the proposal of the new U-D 2 O criticality benchmark system and support the intention to include this system in the next edition of the recent OECD/NEA Project: International Handbook of Evaluated Criticality Safety Experiment, in near future. (author)

  20. THE STRUCTURE OF THE LITHOSPHERIC MANTLE OF THE SIBERAIN CRATON AND SEISMODYNAMICS OF DEFORMATION WAVES IN THE BAIKAL SEISMIC ZONE

    Directory of Open Access Journals (Sweden)

    A. A. Stepashko

    2013-01-01

    Full Text Available  The evolution and specific features of seismogynamics of the Baikal zones are reviewed in the context of interactions between deep deformation waves and the regional structure of the lithospheric mantle. The study is based on a model of the mantle structure with reference to chemical compositions of mantle peridotites from ophiolotic series located in the south-western framing of the Siberian craton (Fig. 1. The chemical zonation of the lithospheric mantle at the regional scale is determined from results of analyses of the heterogeneity of compositions of peridotites (Fig. 2, Table 1 and variations of contents of whole rock major components, such as iron, magnesium and silica (Fig. 3. According to spatial variations of the compositions of peridotites, the mantle has the concentric zonal structure, and the content of SiO2 is regularly decreasing, while concentrations of FeO∑ and MgO are increasing towards the centre of such structure (Fig. 4. This structure belongs to the mantle of the Siberian craton, which deep edge extends beyond the surface contour of the craton and underlies the north-western segment of the Central Asian orogenic belt.Results of the studies of peridotites of the Baikal region are consistent with modern concepts [Snyder, 2002; O’Reilly, Griffin, 2006; Chen et al., 2009] that suggest that large mantle lenses underlie the Archaean cratons (Fig. 5. The lenses are distinguished by high-density ultrabasic rocks and compose high-velocity roots of cratons which have remained isolated from technic processes. Edges of the mantle lenses may extend a few hundred kilometers beyond the limits of the cratons and underlie orogenic belts that frame the cratons, and this takes place in the south-western segment of the Siberian craton.The revealed structure of the lithospheric mantle is consistent with independent results of seismic and magmatectonical studies of the region. The Angara geoblock is located above the central part of the