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Sample records for bambui group neoproterozoic

  1. Influence of geological and hydrogeological factors on the high natural fluoride concentrations in groundwaters in Bambui Group (Neoproterozoic), northern of Minas Gerais state, Brazil; Influencia de los factores geologicos e hidrogeologicos en las altas concentraciones naturales de fluoruro en las aguas subterraneas del Grupo Bambui (Neoproterozoico), norte del estado de Minas Gerais, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Iglesias Martinez, M.; Velasquez, L. N.M.; Fantinel, L. M.; Uhlein, A.; Melo da Silva, S.; Rodrigues, P. C. H.

    2010-07-01

    In the northern semi-arid and semi-humid region of Minas Gerais State, in the southeast Brazil, substantial part of the water supplying is produced by means of deep wells. In several localities the fluoride concentrations are higher than 1.5 mg/L, maximum acceptable limit for drinking water, endangering the public supply and the public health. Endemies of dental fluorosis have been detected since the decade of 1990. The cause of this problem has been associated to the consumption of local drinking water. Current studies indicate the occurrences of fluorite in the limestones of the Bambui Group as the main mineral-source for the fluoride content in the groundwater, however without identifying the specific contribution of each hydrostratigraphic unit. This work shows the results of stratigraphic studies and hydro-chemical analysis of 144 deep wells and the influence of the carbonatic facies in the fluoride concentrations of the water. Fluoride concentrations are related to fluorite occurrences/mineralizations (lithostratigraphic control) and to circulation depth of groundwater (geochemical control), newly distinguishing three hydrostratigraphic units. The correlation analysis of hydrogeochemic parameters (F-, Mg{sub 2}+, SO{sub 4}{sup 2}- and electric conductivity) corroborates these grouping into three units. The probability of the contamination by fluoride, as a function of the hidroestratigraphic units, in decreasing order, seems to be: top level of the Sete Lagoas Formation; Lagoa do Jacare Formation; and botton and middle levels of the Sete Lagoas Formation. (Author)

  2. Isotope ratio 87Sr/86Sr in limestones from Bambui group, Brazil (MG)

    International Nuclear Information System (INIS)

    Kawashita, K.; Mizusaki, A.M.P.; Kiang, C.H.

    1987-01-01

    The Sr composition of ancient seawater can be estimated from the analysis of carbonate rocks and, in some cases, used to estimate the age of the analyzed carbonate. The normalized 87Sr/86Sr ratios in calcium carbonate fractions from 14 core samples in the Bambui Group near Montalvania, MG, were found to range between .7077 and .7280. The higher values are attributable to Sr isotopic exchange between silicate and carbonate phases during diagenesis. The ratio of .7077 obtained in two pure calcium carbonate samples is here suggested as the best aproximation for the 87Sr/86Sr value for the Bambui sea. This ratio is compatible with an age of about 700 Ma., estimated from the published 87Sr/86Sr curve of Veizer and others, an age in accordance with Quadros recent (1987, in preparation) identification of marine acritarchs from the latest Precambrian (Vendian). (author) [pt

  3. Mineralogy of the fraction and age estimation rubidium - strontium of the Bambui Group, MG, Brazil

    International Nuclear Information System (INIS)

    Bonhomme, M.G.

    1976-01-01

    A study of the illite crystallinity of sediments of the Upper Precambrian Bambui Group, MG, has been done to determine the zones without metamorphism, the only ones able to give the age of the sedimentation. Only the region of Januaria escaped from any sensible thermo-tectonic event. The Bambui sediments contain well crystallized vermiculite probably formed during the anchimetamorphism. The rubidium-strontium age obtained in Januaria (619 + - 17 m.y.) corresponds in fact to the main phase of the Brazilian orogenic cycle. The late isotopic homogeneization was caused by a strong late diagenesis. The anchimetamorphic phosphateous sediments in Cedro do Abate show that the ferro-magnesian illite is a more easely open system than aluminous illite, and in this case dates the later event of the Brazilian cycle at 445 + - 25 m.y. The age of 600 m.y. for the metamorphism is a younger limit for the real age of the Bambui, the late Precambrian age of which is confirmed

  4. Isotope stratigraphy of the Neoproterozoic Togari group, Tasmania

    International Nuclear Information System (INIS)

    Calver, C.R.

    1998-01-01

    A carbon and strontium isotope study of the Togari Group, northwest Tasmania. provides significant new age constraints based on chemostratigraphic correlation with key Neoproterozoic sections on other continents. The Black River Dolomite is late Riphean (middle Cryogenian: ca 750-650 Ma) on δ 13 C, δ 87 Sr/ 86 Sr and stromatolite-biostratigraphic evidence. In the upper part of the Black River Dolomite, a diamictite unit (the Julius River Member) is associated with a negative δ 13 C excursion and may correlate with the Sturtian glaciation. The succeeding rift volcanics and clastics of the Kanunnah Subgroup, and the probably correlative Crimson Creek Formation of western Tasmania, are inferred to be late Cryogenian to early Neoproterozoic III in age (ca 650-580 Ma). The Smithton Dolomite is middle to late Neoproterozoic III (i.e. Ediacarian/Vendian: ca 580-545Ma) on δ 13 C and 87 Sr/ 86 Sr evidence. The rise in 87 Sr/ 86 Sr through the Smithton Dolomite (0.7079-0.7085) is consistent with previous work showing a monotonic rise in the ratio through the Vendian. Dolostones in the Black River Dolomite and lower Smithton Dolomite are syndepositional or early diagenetic and little altered in δ 13 C. In contrast, crystalline, isotopically altered massive dolostones comprise most of the upper two- thirds of the Smithton Dolomite, but minor interbedded limestones retain little-altered δ 13 C and 87 Sr/ 86 Sr. Copyright (1998) Blackwell Science Asia

  5. The Neoproterozoic Tillite Group from Ella Ø, East Greenland

    DEFF Research Database (Denmark)

    Buchardt, Bjørn; Kristiansen, Kasper K.; Houmark-Nielsen, Michael

    is ~1200 m. The Ulvesø Fm rests conformably on shales and stromatolithic calcareous rocks of suggested warm water origin, and the Storeelv Fm is conformably overlain by clastic rocks showing pseudomorphoses after halite in the uppermost unit. The two diamictitic units are separated by the ~250 m thick Area...... compositions of the stromatolithic carbonates of Bed Group 18 are significantly enriched compared to modern values with a mean of +7‰ V-PDB. The shift from calcareous rocks of Bed Group 18 to shaly and cherty sediments of Bed Group 19 is accompanied by a negative shift in d13C of more that 15‰, and average...... diamictitic units. The Canyon Fm overlying the Storeelv diamictite shows a gradual shift in d13C(carbonate) to values close to 0‰ as also found in the Cambrian rocks above. Comparison to published carbon isotope curves from other Neoproterozoic glacial events makes it tempting to correlate the marked negative...

  6. Pb/Pb isochron ages and Pb isotope geochemistry of Bambui Group carbonate rocks from the southern portion of the Sao Francisco Basin

    International Nuclear Information System (INIS)

    Babinski, M.

    1993-01-01

    This study involves the establishment of chemical and analytical procedure for Pb/Pb dating of Neo proterozoic carbonate rocks and their application to obtaining isochron ages of Bambui Group rocks from the southern portion of the Sao Francisco Basin, Minas Gerais State. The Pb isotopic compositions and U and Pb concentrations determined on more than 90 samples (≅ 600 analyses) from Sete Lagoas do Jacare formations, Bambui Group, from different parts of the basin, showed four distinct types of Pb, here called types I, II, III and IV. Type I Pb was found in samples with low Pb concentrations and relatively high U concentrations. Type II Pb is present in samples with relatively high Pb concentrations and low U concentrations it is non-radiogenic crustal Pb. Type III Pb is also found in samples with high Pb concentrations and low U concentrations but it is radiogenic crustal Pb. Type IV Pb occurs in samples with U/Pb ratios lower than 1 and is intermediate in composition between Type III and Type I Pb. According to the data presented in this paper it is suggested that carbonate rocks from Sete Lagoas Formations were deposited before 686±69 Ma. Rocks from the Lagoa do Jacare Formation, contained only Type II Pb, which does not permit determination of a Pb/Pb age. During the interval from 690 to 500 Ma, the Pb isotope system of the carbonate rocks from the Sao Francisco Basin was disturbed, and in some areas it was totally reset. The imprecise U/Pb ages of 550-600 Ma obtained from some of the carbonate rocks reflect this disturbance. The ages determined in this study are in agreement with most of the published ages of the tectonism from the Brasiliano fold belts marginal to Sao Francisco Craton, showing that the isotopic systems of Sao Francisco Basin rocks were largely affected by brasiliano tectonism. (author)

  7. Profile characterization of soil developed on pelitic rocks from the Bambui Group through chemical analysis, X-ray diffraction and Moessbaur spectroscopy

    International Nuclear Information System (INIS)

    Almeida Barbosa, L.C. de.

    1986-07-01

    Five sample from a Red-yellow latosol developed on pelitic rocks from the Bambui Group, located close to Paraopeba, state of Minas Gerais, Brazil, were collected and studied. The sample with color patterns varying from yellowish (sample SL11; 0.3m depth), in superficial horizons, to reddish (SL12; 1.0m) in intermediate profile positions, and various shades (SL14A and SL14V; 3.0m), in deeper horizons, were studied through Moessbauer spectroscopy in order to characterize, in detail, the ferruginous species present. The total iron content within the soil is practically constant in relation to the depth. Yet, the hematite/goethite content ratio varies within the expected sequence according to the color. A linear relationship was observed between the reddish intensity and the hematite content of the argillaceous fraction. The hematite contents are proportionally less in the SL14A sample, apparently due to deficient drainage in the past, and in the SL11 sample, due to organic matter effects. This latter sample is also characterized by at least two goethite populations: one with 20% mol replacing aluminum and another with certainly more than 30% mol. In to explan this difference, three hypothesis were elaborated. The most suitable one suggests that the goethite is destroyed and formed again through the soil column, in response to pedo environmental changes closer to the surface. (D.J.M.) [pt

  8. Multiproxy isotope constraints on ocean compositional changes across the late Neoproterozoic Ghaub glaciation, Otavi Group, Namibia

    DEFF Research Database (Denmark)

    Rodler, Alexandra; Frei, Robert; Gaucher, C.

    2017-01-01

    of the Otavi Group, Namibia, stretching over four stages from preglacial setting to retreat of the late Neoproterozoic Ghaub glaciation (∼635 Ma). The fluctuating but generally heavy δ53Cr signals indicate oxygenated shallow seawater prior to the glaciation (stage 1). Sustained high δ13Ccarb signatures...... the carbon cycle and oxygen availability (stage 2). Prior to the Ghaub diamictite, a sequence of 87Sr/86Sr in the range typical of late Neoproterozoic seawater occurs with high Sr concentrations, low Mn/Sr and low Mg/Ca. Enhanced detrital input after the Ghaub glaciation (stage 3) indicates elevated...... records typical late Neoproterozoic seawater 87Sr/86Sr ratios. The carbonate δ53Cr signatures at the base of the postglacial sequence are characterized by values even below the range of bulk silicate Earth (BSE). We hypothesize that this is due to (i) redox cycling of Cr in seawater, e.g. by (partial...

  9. The Neoproterozoic Tillite Group from Ella Ø, East Greenland

    DEFF Research Database (Denmark)

    Buchardt, Bjørn; Kristiansen, Kasper K.; Houmark-Nielsen, Michael

    values of carbonates in Bed Group 19 are close to -10‰. Organic carbon from Bed Group 19 has d13C values close to -34‰ indicating a carbonate to organic carbon fractionation of ~25‰ similar to present-day conditions. Similar depleted carbon isotope compositions are found in the Arena Fm between the two...

  10. The Mesoproterozoic to early Neoproterozoic passive margin Lajeado Group and Apiaí Gabbro, Southeastern Brazil

    Directory of Open Access Journals (Sweden)

    G.A.C. Campanha

    2016-07-01

    Full Text Available The Lajeado Group in the Ribeira Belt, southeastern Brazil, corresponds to an open-sea carbonate platform, comprised of seven overlapping siliciclastic and carbonatic formations, intruded in its upper portion by the Apiaí Gabbro. These rocks have a Neoproterozoic tectonometamorphic overprint related to arc magmatism and the Brasiliano collisional orogeny. Geochronological constraints are given by new U-Pb SHRIMP and LA-ICP-MS data for Lajeado Group detrital zircons and for magmatic zircons from the Apiaí Gabbro. The youngest detrital zircons in the Lajeado Group are 1400–1200 Ma, and constrain its maximum age of deposition to be <1200 Ma, whereas the 877 ± 8 Ma age for magmatic zircons in the Apiaí Gabbro give the minimum age. Detritus source areas are mainly Paleoproterozoic (2200–1800 Ma with some Archean and Mesoproterozoic contribution (1500–1200 Ma, with distal or tectonic stable cratonic character. The Lajeado Group should be a Stenian–Tonian carbonate platform passive margin of a continent at this time, namely the Columbia/Nuna or the Rodinia. The Apiaí Gabbro displays similar age to other intrusive basic rocks in the Lajeado and Itaiacoca groups and represents tholeiitic MORB-like magmatism that we relate to the initial break-up of a Mesoproterozoic continent and the formation of the Brasiliano oceans.

  11. Mineralizations of the Lavalleja Group (Uruguay), a Probable Neoproterozoic Volcano-sedimentary Sequence

    International Nuclear Information System (INIS)

    Sanchez Bettucci, L.; Oyhantcabal, P.; Loureiro, J.; Basei, M.; Ramos, V.; Preciozzi, F.; Basei, M.

    2004-01-01

    The Lavalleja Group is located in the southern extreme of the Dom Feliciano Belt, being tentatively correlated with the Porongos and Brusque Groups of Brazil. The basement of the Lavalleja Group is probably represented by granitic gneissic rocks of the Campanero Unit with ages, in the southern portion, ranging from 1.75 to 2.1 Ga (U-Pb in zircon). The Lavalleja Group is characterized by narrow bands of meta sedimentary and meta volcanic rocks and it is separated in three formations, namely (from base to top): Zanja del Tigre, Fuente del Puma and Minas. Outcrops assigned to the Minas Formation have been recently correlated with the Arroyo del Soldado Group. Only the Fuente del Puma formation hosts base metals, Au and Ag occurrences. The Fuente del Puma formation is divided into three informal units: sedimentary, volcanic and hornblenditic gabbros. The sedimentary unit is characterized by an important amount of carbonates. Syn collisional to pos tectonic granitic bodies (Carapé Complex) intrudes the Lavalleja Group and the Campanero Unit. Several mineralizations are located in the Fuente del Puma Formation, those associated to Arrospide, Ramallo-Reus, Chape, Valencia, La Oriental, Apolonia, Redondo Hill, La China and La Paloma mines are the most important. In addition, many occurrences of Cu-Zn-Pb were recognized in the region. The Cu-Zn-Pb mineralization includes massive sulfides with pyrite-chalcopyrite-sphalerite-galena-pyrrothyte, arsenopyrite-hematite into small bodies with lenticular shape. The host rock shows frequently hydrothermal alteration. The geochemistry and the geological features of the mineralizations suggest Besshi Massive Sulphide Zn-Cu-Pb and SEDEX Zn-Pb as most probably genetic models for the deposits related to the Neoproterozoic orogeny. Early mineralizations are syngenetic and were formed on the sea floor, although the main mineralizations are related to remobilization during syn- to late-metamorphic events and thrusting

  12. Southern Brasilia Belt (SE Brazil): tectonic discontinuities, K-Ar data and evolution during the Neoproterozoic Brasiliano orogeny

    Energy Technology Data Exchange (ETDEWEB)

    Valeriano, Claudio Morrison de [Universidade do Estado, Rio de Janeiro, RJ (Brazil)]. E-mail: cmval@uerj.br; Teixeira, Wilson [Sao Paulo Univ., SP (Brazil); Simoes, Luiz Sergio Amarante [UNESP, Sao Paulo, SP (Brazil); Heilbron, Monica [Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), Brasilia, DF (Brazil)

    2000-03-01

    This paper focuses the tectonic evolution of the southern brasilia belt, with emphasis on the Furnas segment, along the 21 deg C S parallel. The uppermost structural unit (Passos Nappe - PN) comprises a highly deformed metasedimentary succession interpreted as a fragment of the Neoproterozoic passive margin of western Sao francisco craton. An inverted metamorphic gradient ranging from greensvhits to lower granulite facies of medium to high-pressure regime characterizes the PN as relict of a subduction zone. The External Domain display a complex imbrication of basement rocks (Archean Piumhi greenstones, a turbiditic gaywacke succession and a calc-alkaline granitoid suite) with undated siliciclast low-grade metasedimentary rocks. The Sao Francisco Craton (SFC) comprises pre-1.8 Ga basement rocks covered by anchimetamorphic Neoproterozoic carbonatic shallow marine platform deposits of the Bambui group. The Brasiliano thrust stacking generated a coarse clastic influx of molassic character on the foreland zone of Sao Francisco Craton, coeval with the exhumation of the External Domain thrust sheets. New K-Ar determinations on mineral separates are presented an interpreted among previous data. The SFC basement rocks display Paleo-to Meesoproterozoic cooling ages. The allochthonous units, in contrast, display K-Ar ages within the 560-675 Ma range. Brasiliano thrust stacking is therefore interpreted to have taken place onto a cold Sao Francisco craton foreland, in a thin-skinned style, as basement rocks were not heated enough to have their-K-ar systems reset during the allochthony. (author)

  13. Lavalleja group (Uruguay), a neoproterozoic metavolcanic-metasedimentary sequence:geochemistry and geochronological features

    International Nuclear Information System (INIS)

    Preciozzi, F.; Sanchez Bettucci, L.; Basei, M.

    2003-01-01

    The Lavalleja Group is located in the southern portion of the Dom Feliciano Belt, being correlated with the Porongos and Brusque Groups in Brazil. This Group has a granitic-gneissic basement probably associated to the Valentines Block and Pavas Terrane, with ages ranging from 1.75 to 2.1 Ga (U-Pb determination). An older basement probably occurs. This Group is characterized by narrow bands of metasedimentary and metavolcanic rocks and is subdivided into three formations (Sánchez-Bettucci, 1998). The first one includes lithologies with a very low to anquimetamorphism degree; the second one is formed by rocks with low metamorphism degree (lower greenschist facies) and the last one presents an upper greenschist facies in transition to upper and lower amphibolite facies. They correspond respectively to the Minas, Fuente del Puma and Zanja del Tigre Formations. The Minas Formation includes only metasedimentary rocks: limestones, dolomites, metapelites, quartzites and arkoses. The Fuente del Puma Formation is formed by three units (Sanchez-Bettucci, 1998): the sedimentary, volcanic and hornblenditic gabbros units. The Zanja del Tigre Formation shows lithologies of medium metamorphism degree, developed to the east of the two other Formations. Syn-collisional to postectonic granitic bodies are associated to the Lavalleja Group. These granitic bodies correspond to the Carapé Complex. The paleoproterozoic basement of Lavalleja Group and Carapé Complex is named Campanero Unit

  14. The Neoproterozoic Lavalleja group in Uruguay: geology and base metal deposits

    International Nuclear Information System (INIS)

    Sánchez-Bettucci, L.; Preciozzi, F.; Ramos, V.; Basei, M.

    2003-01-01

    The Lavalleja Group, which is exposed along the Dom Feliciano Belt is located in the southeast of Uruguay and is represented by metavolcano-sedimentary rocks. It is developed during late Proterozoic-Early Paleozoic Brasiliano orogeny. Based on geochemical signature of the rocks of the Lavalleja Group, mainly metagabbros, basic and acidic metavolcanic rocks, a back-arc basin tectonic setting is suggested by Sánchez-Bettucci et al. (2001). The metamorphic grade increases to the southeast, ranging from lower greenschist facies to lower amphibolite facies in the Fuente del Puma and Zanja del Tigre Formations (Sánchez-Bettucci et al., 2001). The non-metamorphic to anchimetamorphic Minas Formation of Sánchez-Bettucci et al. (2001) is a junior synonim of the Arroyo del Soldado Group, previously defined by Gaucher et al. (1996). The metamorphic mineral assemblages correspond to a low-pressure regional metamorphism associated with a high thermal gradient (Sánchez-Bettucci et al., 2001).A compressive deformational event, that probably corresponds to the basin closure of the Lavalleja Group during a continental collision was recognized. The petrology, geochemistry, metamorphism grade, and tectonic setting are consistent with a back-arc basin for the Lavalleja Group (Sánchez-Bettucci et al., 2001)

  15. Lavalleja group (Uruguay) a neoproterozoic metavolcanic-sedimentary sequence: ore deposits

    International Nuclear Information System (INIS)

    Sanchez Bettucci, L.; Preciozzi, F.; Ramos, V.

    2003-01-01

    The Lavalleja meta volcano-sedimentary Group, exposed along the Dom Feliciano Belt, is located in the southeast of Uruguay and formed by meta gabbros, basic and acid meta volcanic rocks. It was developed during late Proterozoic-Early Paleozoic Brasiliano orogeny. Based on the geochemical signature, Sánchez-Bettucci et al. (2001) suggested a back-arc basin tectonic setting. The metamorphic grade increases to the southeast, ranging from very low grade to lower green schist facies in the Minas formation, to lower amphibolite facies in the Fuente del Puma and Zanja del Tigre Formations (Sánchez-Bettucci et al., 2001). The metamorphic mineral assemblages correspond to a low-pressure regional metamorphism associated with a high thermal gradient (Sánchez-Bettucci et al., 2001).A compressive deformational event, that probably corresponds to the basin closure of the Lavalleja Group during a continental collision was recognized. The petrology, geochemistry, metamorphism grade, and tectonic setting are consistent with a back-arc basin as suggested by Sánchez-Bettucci et al. (2001)

  16. Chemostratigraphy of Neoproterozoic Banded Iron Formation (BIF)

    DEFF Research Database (Denmark)

    Gaucher, Claudio; Sial, Alcides N.; Frei, Robert

    2015-01-01

    Neoproterozoic banded iron formations (BIFs) are not restricted to the middle Cryogenian, c. 715 Ma glaciation, occurring in Tonian, Cryogenian, and Ediacaran successions. Many Neoproterozoic BIFs were deposited in glacially influenced settings, such as the Rapitan Group (Canada), Jacadigo Group (W...... for the study of BIFs include rare earth element distribution, especially Eu and Ce normalized concentrations, iron speciation, and Nd and Cr isotopes (δ53Cr). Whereas Rapitan type BIFs exhibit no Eu or Ce anomalies, the Algoma-type Neoproterozoic BIFs show both. Positive δ53Cr values characterize glacially...

  17. The Neoproterozoic Malani magmatism of the northwestern Indian ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Neoproterozoic; Malani; Sindreth Group; felsic volcanism; crust building. Proc. Indian Acad. Sci. (Earth Planet. Sci.), 113, No. 4, December 2004, pp. 795–807 ...... Tectonic evolution. The Neoproterozoic crustal building process in western Rajasthan is marked with the intrusion of. 1000 Ma old diorite and gabbro in the south ...

  18. Pre-vegetation fluvial floodplains and channel-belts in the Late Neoproterozoic-Cambrian Santa Bárbara group (Southern Brazil)

    Science.gov (United States)

    Marconato, André; de Almeida, Renato Paes; Turra, Bruno Boito; Fragoso-Cesar, Antônio Romalino dos Santos

    2014-03-01

    One key element to the understanding of the dynamics of pre-vegetation fluvial systems is the reconstruction of processes operating on their floodplains given that, in modern systems, channel banks and floodplains are the environments most affected by plant colonization. Notwithstanding, few pre-vegetation floodplains have been described, and major questions regarding their most basic characteristics are still unresolved. In order to address these questions, detailed analysis of coeval channel-belt, fluvial floodplain and alluvial-fan deposits from the Santa Bárbara Group (Late Neoproterozoic to Early Cambrian, southern Brazil) was performed. While floodplain facies resemble ephemeral stream deposits, being coarser-grained than modern floodplains and marked by the stacking of flood event cycles, channel-belt deposits show composite bars, which do not present conclusive evidence for high water discharge variation. The floodplain deposits show particular features common to other pre-vegetation fluvial systems, such as better preserved small-scale structures, lack of bioturbation, and abundance of cross-laminated sandstones, while other features differ from previous depositional models, namely abundant mudcracks and evidence of soil formation. The lateral variation of depositional systems recorded in the Santa Bárbara Group shows contrasting signatures of water discharge variation in sand-dominated coeval environments, and offers an example of the relation between different alluvial environments before the evolution of land plants.

  19. Geochemistry and Isotope Stratigraphy (C, O, Sr, Nd, Cr) of the Ediacaran Sete Lagoas Cap Carbonate, Bambui Group, Brazil: Insights into Earth's Oceanic and Atmosphere Geochemical Cycles After a Snowball Glaciation.

    Science.gov (United States)

    Caxito, F.; Frei, R.; Uhlein, G. J.; Uhlein, A.

    2016-12-01

    We studied a basal Ediacaran cap carbonate profile pertaining to the base of the Bambuí Group (Sete Lagoas Formation) in the central portion of the São Francisco basin, east central Brazil. The section begins with a two-meter thick pink dolostone which grades upward into a reddish limestone. The basal dolostone preserves a drop of δ13C values from -3.8 to -4.2‰, and δ18O values from -4.5 to -5.1‰. The red laminated limestone yielded δ13C values averaging -5‰ for about 60 m up section. Above 60 m, the δ13C values shift abruptly to around -0.5‰. The section is capped by black calcarenites with positive δ13C (+0.9‰); these high [Sr] carbonates (>1000 ppm) yield 87Sr/86Sr around 0.7076. Overall, there is an upwards-decreasing trend of ɛNd(630 Ma) values, from -6.0 in the base to -7.2 towards the top, and also upwards-decreasing trends of trace metal concentrations, especially for Cr (10-4 ppm), Sc (4.3-1.7 ppm), Co (3.7-0.8 ppm), Cu (4-0.3 ppm), Zn (29-0.6 ppm), and Ti (80-10 ppm). δ53Cr values of the basal pink cap dolostone are about -0.3‰, with an upwards-increasing trend to about +0.2‰ at the topmost carbonates. Thus, the cap carbonate is characterized by upwards-decreasing trends of ɛNd(630 Ma) and trace metal concentrations and upwards-increasing trends of δ13C, δ18O and δ53Cr. These fluctuations can be interpreted to reflect increased continentally-derived input into the shallow seawater. The higher ɛNd(630 Ma) and trace metal contents, as well as negative δ13C and δ53Cr of the basal cap dolostone all point to a higher contribution of less-fractionated sources to seawater geochemical composition, probably due to the fact that oceanic geochemical cycles were not yet fully restored after isolation by ice caps from atmospheric and continental weathering inputs. Upwards, in the limestone section, decreasing ɛNd(630 Ma), increasing δ13C and increasingly positively fractionated δ53Cr values suggest a recovery of Earth

  20. Geochemistry and petrogenesis of Neoproterozoic Mylliem ...

    Indian Academy of Sciences (India)

    The Mylliem granitoids of the Meghalaya Plateau, northeastern India, represent one of the disharmonic. Neoproterozoic igneous plutons, which are intrusive into low-grade Shillong Group of metasediments. Field studies indicate that the Mylliem granitoids cover an area of about 40 km2 and is characterized by development ...

  1. Zircon U-Pb Geochronology, Hf Isotopic Composition and Geological Implications of the Neoproterozoic Huashan Group in the Jingshan Area, Northern Yangtze Block, China

    Science.gov (United States)

    Yang, Z.; Yang, K.

    2015-12-01

    In the northern Yangtze Block, a clear angular unconformity between the Mesoproterozoic sequences (e.g. Dagushi Group) and the overlying Neoproterozoic strata (e.g. Huashan Group) marks the the Jinning orogeny. A combined study of Lu-Hf isotopes and U-Pb ages for detrital zircons from Huashan Group can provide information on the crustal evolution of sedimentary provenances and the timing of the Jinning orogeny. Detrital zircons from Huashan Group have two major U-Pb age populations of about 2.0Ga, 2.65Ga, and three subordinate age groups of about 0.82Ga, 2.5Ga, 2.9Ga with minor >3.0Ga ages. The youngest five analyses yield a weighted average age of 816±9Ma, which is consistent with that of interlayered basalt (824±9Ma, Deng et al., 2013) and roughly defines the minimum depositional age of Huashan Group. Detrital zircons of Huashan Group mostly have two stage Hf isotope model ages (TDM2) between 3.0 to 3.3Ga, indicating that the northern Yangtze Block experienced significant continental crustal growth during the Paleo- to Meso-archean. Similar U-Pb ages of detrital zircons have been obtained from Precambrian sedimentary rocks in the northern Yangtze Block from previous studies (Liu et al., 2008; Guo et al., 2014 and references therein). Recently, ca. 2.65Ga A-type granites had been reported from the Kongling and Huji area, which likely record the thermally stable lithosphere (Chen et al., 2013; Zhou et al., 2015). In combination with this study, it documents the widespread 2.6-2.7Ga magmatic rocks in the northern Yangtze Block. Zhao et al. (2013) demonstrated both the ca. 850Ma tonalite and trondhjemite of the Huangling igneous complex were formed in a continental arc setting. This suggests the Miaowan-Huashan oceanic basin proposed by Bader et al. (2013) has not been closed at ca. 850Ma. This evidence, together with the depositional age of the Huashan Group, indicates the Jinning orogeny took place at 850-820 Ma. [1] Bader et al., 2013 Tectonics [2] Deng et al

  2. Aplication of uranium isotopes as tracers in ground water studies (Bambui - Bahia, Brazil)

    International Nuclear Information System (INIS)

    Gomes, F.V.M.

    1978-03-01

    Analyses of 234 U/ 238 U activity ratios and the uranium concentration in 42 underground water samples have provided better in formation about the recharge area and the flow direction in the Bambui limestone, Bahia (Brazil). In the main recharge area, the activity ratios were found to range from 3 to 6 and the uranium concentration averaged 1 μg/l. The activity ratio increases northward with the highest values close to 10. The 234 U excess from a basic of ratio of activity (fundamental leaching ratio) also increases northward in agreement with the age of the water, an observation confirmed by C-14. This 234 U excess is attributed to the alpha-recoil process. The system was calibrated and the age of the waters in the calcareous region was determined. (Author) [pt

  3. The use of chemical and isotopic data as indicators of the origin of waters and dissolved salts in the Bambui calcareous aquifer (Bahia-Brazil)

    International Nuclear Information System (INIS)

    Siqueira, A.F.

    1978-10-01

    Samples of 25 wells located in the Bambui limestone aquifer in the region of Irece - Bahia, have been analised for the isotopic ratio 18 O/ 16 O and the major chemical species Ca, Mg, Na, K, Cl, SO 4 and bicarbonate. The oxygen-18 data have been found to range between -2,62/00(in a thousand) to -6,66/00(in a thousand) relative to the universal Standard Mean Ocean Water (SMOW) and are compared with the values of the precipitation in the localities of Jacobina and Lencois (meteorological stations nearby) and with the values of the groundwater in sedimentary basins in northeastern Brazil. The comparison suggests that aquifer system is recharged by precipitation originated in northeastern Brazil, instead of originating on coast of Bahia, east of the area. Furthermore, the waters in aquifer are not found homogenized, having widely varying 18 O and chemical composition and being of different ages. The strong correlation between the observations Ca, Mg, Na, Cl and TDS (total dissolved solids) suggests an aerosol origin of salts, not excluding the hypothesis of dissolution of rock, which concentrations. The comparison of characteristic ratios Mg/Ca, SO 4 /Cl and (Cl-Na)/Cl, a Piper diagrama and a dendrogram established by cluster analysis, indicates that the wells may be separated in to two groups according to the isotopic or geochemical environment to which they belong. These groups may represent the differents sources of salt proposed, one being from the limestone, the other having come from aerosols. (Author) [pt

  4. Reconstructing Rodinia by Fitting Neoproterozoic Continental Margins

    Science.gov (United States)

    Stewart, John H.

    2009-01-01

    Reconstructions of Phanerozoic tectonic plates can be closely constrained by lithologic correlations across conjugate margins by paleontologic information, by correlation of orogenic belts, by paleomagnetic location of continents, and by ocean floor magmatic stripes. In contrast, Proterozoic reconstructions are hindered by the lack of some of these tools or the lack of their precision. To overcome some of these difficulties, this report focuses on a different method of reconstruction, namely the use of the shape of continents to assemble the supercontinent of Rodinia, much like a jigsaw puzzle. Compared to the vast amount of information available for Phanerozoic systems, such a limited approach for Proterozoic rocks, may seem suspect. However, using the assembly of the southern continents (South America, Africa, India, Arabia, Antarctica, and Australia) as an example, a very tight fit of the continents is apparent and illustrates the power of the jigsaw puzzle method. This report focuses on Neoproterozoic rocks, which are shown on two new detailed geologic maps that constitute the backbone of the study. The report also describes the Neoproterozoic, but younger or older rocks are not discussed or not discussed in detail. The Neoproterozoic continents and continental margins are identified based on the distribution of continental-margin sedimentary and magmatic rocks that define the break-up margins of Rodinia. These Neoproterozoic continental exposures, as well as critical Neo- and Meso-Neoproterozoic tectonic features shown on the two new map compilations, are used to reconstruct the Mesoproterozoic supercontinent of Rodinia. This approach differs from the common approach of using fold belts to define structural features deemed important in the Rodinian reconstruction. Fold belts are difficult to date, and many are significantly younger than the time frame considered here (1,200 to 850 Ma). Identifying Neoproterozoic continental margins, which are primarily

  5. Carbon and Oxygen Isotope Stratigraphy of the Ediacaran Jaíba Formation, Upper Bambuí Group, Brazil: Insights into Paleogeography and Sedimentary Environments after a Neoproterozoic Glaciation.

    Science.gov (United States)

    Caxito, F.; Uhlein, G. J.; Sial, A. N.; Uhlein, A.

    2015-12-01

    The Neoproterozoic Era was a time of extreme climatic variation as recorded in sedimentary rocks of this age across the globe, leading to a number of controversial hypotheses (e.g. the Snowball Earth glaciations). In eastern Brazil, the Bambuí Gr. is a thick carbonatic-siliciclastic unit that covers the São Francisco Craton and preserves remnants of a Neoproterozoic glaciation and their respective cap carbonate (1). Recent findings of Cloudina in the Januária region (2) suggest that at least part of the sequence might be upper Ediacaran or even Cambrian. Here we present the first carbon-oxygen isotope data for the Jaíba Fm., a ca. 50 m thick carbonate unit that occurs in the topmost portion of the Bambuí Gr. in this same region. The Jaíba Fm. post-dates the cap carbonate sequence and the fossil-bearing layers, and thus was probably deposited in the Ediacaran-Cambrian transition. Three stratigraphic columns were analyzed, and yielded similar ratios. Values of δ13CVPDB are between 0.8 and 3.4 ‰, while δ18OVPDB values are mostly around -8 ‰. These values contrasts with the negative δ13C values found for the base of the Bambuí Gr., followed by highly positive δ13C (up to +14‰) on its middle portion. The unusually high δ13C values are commonly interpreted as evidence for deposition on a restricted basin, such as in a foreland setting. The return to values which are close to the PDB standard in the uppermost Bambuí Gr. might thus indicate a change in the paleogeography and tectonic environment of the basin, suggesting an open, ventilated environment along with a recovery of the biological and hydrological cycle after a Late Neoproterozoic glaciation. Ongoing detailed sedimentological, geochemical and isotopic work might help to further clarify these issues and to provide new clues for unraveling Late Neoproterozoic paleoclimate, paleogeography and ocean chemistry. We thank FAPEMIG (Brazil) for finnacial support through grants n. APQ-00914-14 and PPM

  6. Geological evolution of the Neoproterozoic Bemarivo Belt, northern Madagascar

    Science.gov (United States)

    Thomas, Ronald J.; De Waele, B.; Schofield, D.I.; Goodenough, K.M.; Horstwood, M.; Tucker, R.; Bauer, W.; Annells, R.; Howard, K. J.; Walsh, G.; Rabarimanana, M.; Rafahatelo, J.-M.; Ralison, A.V.; Randriamananjara, T.

    2009-01-01

    The broadly east-west trending, Late Neoproterozoic Bemarivo Belt in northern Madagascar has been re-surveyed at 1:100 000 scale as part of a large multi-disciplinary World Bank-sponsored project. The work included acquisition of 14 U-Pb zircon dates and whole-rock major and trace element geochemical data of representative rocks. The belt has previously been modelled as a juvenile Neoproterozoic arc and our findings broadly support that model. The integrated datasets indicate that the Bemarivo Belt is separated by a major ductile shear zone into northern and southern "terranes", each with different lithostratigraphy and ages. However, both formed as Neoproterozoic arc/marginal basin assemblages that were translated southwards over the north-south trending domains of "cratonic" Madagascar, during the main collisional phase of the East African Orogeny at ca. 540 Ma. The older, southern terrane consists of a sequence of high-grade paragneisses (Sahantaha Group), which were derived from a Palaeoproterozoic source and formed a marginal sequence to the Archaean cratons to the south. These rocks are intruded by an extensive suite of arc-generated metamorphosed plutonic rocks, known as the Antsirabe Nord Suite. Four samples from this suite yielded U-Pb SHRIMP ages at ca. 750 Ma. The northern terrane consists of three groups of metamorphosed supracrustal rocks, including a possible Archaean sequence (Betsiaka Group: maximum depositional age approximately 2477 Ma) and two volcano-sedimentary sequences (high-grade Milanoa Group: maximum depositional age approximately 750 Ma; low grade Daraina Group: extrusive age = 720-740 Ma). These supracrustal rocks are intruded by another suite of arc-generated metamorphosed plutonic rocks, known as the Manambato Suite, 4 samples of which gave U-Pb SHRIMP ages between 705 and 718 Ma. Whole-rock geochemical data confirm the calc-alkaline, arc-related nature of the plutonic rocks. The volcanic rocks of the Daraina and Milanoa groups also

  7. Tidal shelf sedimentation in the Neoproterozoic Chattisgarh ...

    Indian Academy of Sciences (India)

    The Neoproterozoic Kansapathar Sandstone of the Chattisgarh basin, a shallow marine shelf bar sequence, consists of mineralogically and texturally mature sandstones with subordinate siltstones, mudstones and conglomerates. The sediments were transported, reworked and deposited in subtidal environments by strong ...

  8. Neoproterozoic Stromatolites and Microphytolites of the Spitsbergen Archipelago

    Science.gov (United States)

    Anisimov, Artem; Anisimova, Svetlana; Kosteva, Natalia

    2017-04-01

    The Svalbard archipelago is located in the extreme North-West of the Barents Sea. On the archipelago in the framework of large-scale exploration of the continental shelf exploration work carried out by employees of the Polar Marine Geological Expedition (PMGE). The authors were further explored and tested the Neoproterozoic sections of the Groups Veteranen, Akademikarbreen and Polarisbreen on the East and West banks of the Sorgfjorden (the Northern part of the Ny Friesland Peninsula) and in the moraine of the glacier Duner. The rocks carbonate-terrigenous Veteranen Group (upper Riphean) is set in the rocky outcrops on the Western and Eastern banks of Sorgfjorden and in ice-dressed rocks of the Bay. The Group consists of four Formations (bottom to top): Kortbreen, Kingbreen, Glasgowbreen and Oxfordbreen. The rocks carbonate-terrigenous Akademikarbreen Group (upper Riphean) have a lower areal distribution than the breed Veteranen Group in the project area is established only in the southern part of the Bay, in the valleys Kluftdalen, Rivnedalen and small-unnamed streams, as well as on the plateau Fleinfjellet and Vidarfjellet. The Groups consists of four formation (bottom to top): Grusdievbreen, Svanbergfjellet, Draken and Backlundtoppen. According to previous researchers, limestone in Kingbreen Formation (Veteranen Group) met with radial-rayed Microphytolites group Radiosus. And in light grey, cream, pink and red limestones of the Academikarbreen Group, in the Svanbergfjellet Formation defined columnar branching Stromatolites Inzeria djejimi Raab., Gymnosolen aff. ramsayi Steinm. Stromatolites of Conophyton miloradovichi Raab. in the dolomites of the overlying sediments Draken and Backlundtoppen Formations contain Vendian the bubbles Microphytolites Vesicularites bothrydioformis Krasnop. In carbonate rocks of the Akademikerbreen Group were confirmed by the finds of Neoproterozoic microbial entities identified by previous researchers, and identified new locations of

  9. The Neoproterozoic Puga (Varanger) cap carbonate, Amazon Craton, Brazil

    Science.gov (United States)

    Riccomini, C.; Nogueira, A. C.; Sial, A. N.; Moura, C. A.; Fairchild, T. R.

    2003-04-01

    Based on stratigraphic and isotopic data the basal carbonates of the Araras Group overlying diamictites of the Puga Formation at the southwest margin of the Amazon Craton are interpreted as a Neoproterozoic cap carbonate. Deposited below wavebase on a carbonate platform, this cap consists of two units separated by a transgressive erosional surface. The lower unit comprises moderately deep to shallow-water pinkish dolomudstone with stratiform fenestrate stromatolites, fenestrate planar lamination, ridge ("tepee-like structures") and tubiform structures. The upper unit includes deep-water bituminous lime mudstones with terrigenous grains, and subordinate shales. Alternating thin calcite crusts and lime mudstone laminae are commonly disrupted by calcite crystal fans (pseudomorphs after aragonite). Brecciated, faulted, and slumped limestone beds with multiple generations of cement indicate localized synsedimentary deformation. Negative excursions of δ13C and variations in 87Sr/86Sr are consistent with a Varanger age. However, unlike other cap carbonates, the basal contact with diamictites exhibits soft-sediment deformation, providing unequivocal sedimentological evidence of rapid dolostone precipitation after ice-melting. This fact confirms the existence of an abrupt change from icehouse to extreme greenhouse conditions, as proposed in the snowball earth hypothesis for Neoproterozoic glaciation. (Financial support: FAPESP grant 00/02903-8, CNPq and Pró-Reitoria de Pós-Graduação, USP).

  10. Neoproterozoic marine carbonates and their paleoceanographic significance

    Science.gov (United States)

    Hood, Ashleigh van Smeerdijk; Wallace, Malcolm William

    2018-01-01

    The primary mineralogy of marine carbonate precipitates has been a crucial factor in constraining the major element composition of ancient oceans. Secular changes in Phanerozoic marine chemistry, including Mg/Ca, have been well-documented using the original carbonate mineralogy of ooids, marine cements and biominerals. However, the history of Precambrian seawater chemistry is not as well constrained, partially due to the prevalence of dolomitisation in the Precambrian geological record. The Neoproterozoic ( 1000 Ma to 541 Ma) record of primary carbonate mineralogy is documented here using a combination of literature data and new analysis of marine carbonate precipitates from the Otavi Fold Belt, Namibia, the Death Valley succession, USA and the Adelaide Fold Belt, Australia. These data suggest that the last 460 million years of the Proterozoic were dominated by aragonite and high-Mg calcite precipitation in shallow marine settings. In contrast, low-Mg calcite has only been recognised in a small number of formations. In addition to aragonite and calcite precipitation, marine dolomite precipitation was widespread in Neoproterozoic oceans, including mimetic (syn-sedimentary) dolomitisation and primary dolomite marine cementation. The combination of marine aragonite, high Mg-calcite and dolomite precipitation during the Neoproterozoic suggests extremely high seawater Mg/Ca conditions relative to Phanerozoic oceans. Marine dolomite precipitation may also be linked to widespread marine anoxia during this time.

  11. Zircon Typology as Indicator of Provenance in Neoproterozoic Sandstones of the Voltaian Basin, Ghana

    OpenAIRE

    Chris Anani; Masaaki Tateishi; Daniel Asiedu; David Atta-Petters; Johnson Manu

    2012-01-01

    An investigation to identify the suitability of zircon crystals as provenance indicators of the relatively mature sandstones of the Neoproterozoic strata in the Voltaian Basin was conducted. A total of 154 zircon grains were critically studied, all extracted from 14 sandstones samples; 7 from Lower Voltaian Kwahu-Morago Group and 7 from the Middle Voltaian Oti-Pendjari Group. Zircon typology analysis indicates anatectic origin with some contribution of a volcanic material for the Kwahu-Morago...

  12. The use of carbon isotopes in the study of groundwater of the Bambui calcareous-central region of Bahia (Brazil)

    International Nuclear Information System (INIS)

    Cabral, F.C.F.

    1978-06-01

    Groundwater of 34 wells and of a spring of the Bambui limestone aquifer, in central Bahia, Brazil, were analized for the 14 C and 13 C content. One sample of soil CO 2 and four of soil organic matter were analized for 13 C. From these data were calculated the 14 C ages of these waters. A major difficulty in the use of radiocarbon in groundwater hydrology is the estimation of the initial 14 C concentration. In many cases, this can be simply determined by the fraction of carbon derived from soil gas, relative to the total carbon dissolved, by the use of Δ 13 C of the soil organic matter, limestone and dissolved carbon in water. This approach does not seem to be completely valid in arid ou semi-arid regions, specially where the pH of the soil is relatively high. In this case, the isotopic composition of the soil water can be determined if the pCO 2 and pH of the soil can be estimated and if the isotopic composition of the soil CO 2 can be known. The final isotopic composition of the groundwater is a combination of the isotopic composition of the soil water and any limestone thereafter dissolved. The 14 C ages of the water samples analized ranged from modern to about 13000 years. The recharge areas of the aquifer are clearly indicated, as the probable underground flow directions. The interpretation of the radiocarbon data is in accord with the hydrologic data. (Author) [pt

  13. Organic matter in the Neoproterozoic cap carbonate from the Amazonian Craton, Brazil

    Science.gov (United States)

    Sousa Júnior, Gustavo R.; Nogueira, Afonso C. R.; Santos Neto, Eugênio V.; Moura, Candido A. V.; Araújo, Bruno Q.; Reis, Francisco de A. M.

    2016-12-01

    Bitumen found in Neoproterozoic carbonates from the southern Amazonian Craton, Brazil, represents a great challenge for its geochemical characterization (origin, thermal maturity and the degree of preservation) within a context of petroleum system. This organic material occurs in the basal Araras Group, considered as a Neoproterozoic cap carbonate, composed of dolostones (Mirassol d'Oeste Formation) overlaid by limestones and shales (Guia Formation). Geochemical analyses in samples of carbonate with bitumen from two open pits (Terconi and Tangará quarries) have shown low to very low total organic carbon content. Analyses of representative samples of Guia and Mirassol d'Oeste formations allowed us to obtain Gas chromatography (GC) traces and diagnostic biomarkers. n-C14 to n-C37 alkane distribution patterns in all samples suggests a major contribution of marine algae. Mid-chain monomethyl alkanes (C14sbnd C25) identified in both sets of samples were also reported in all mid to late Proterozoic oils and source rocks. However, there are significant differences among terpane distribution between the Mirassol d'Oeste and Tangará da Serra regions. The integration of organic geochemistry data and geological information suggests an indigenous origin for studied bitumen, primarily accumulated as hydrocarbon fluids migrated to carbonate rocks with higher porosity and permeability, and afterwards, altered to bitumen or migrabitumen. Although further investigations are required, this work provides a significant contribution to the knowledge about the remnant of this hypothetical Neoproterozoic petroleum system developed in the Southern Amazonian Craton.

  14. Genomic African and Native American Ancestry and Chagas Disease: The Bambui (Brazil) Epigen Cohort Study of Aging.

    Science.gov (United States)

    Lima-Costa, M Fernanda; Macinko, James; Mambrini, Juliana Vaz de Mello; Peixoto, Sérgio Viana; Pereira, Alexandre Costa; Tarazona-Santos, Eduardo; Ribeiro, Antonio Luiz Pinho

    2016-05-01

    The influence of genetic ancestry on Trypanosoma cruzi infection and Chagas disease outcomes is unknown. We used 370,539 Single Nucleotide Polymorphisms (SNPs) to examine the association between individual proportions of African, European and Native American genomic ancestry with T. cruzi infection and related outcomes in 1,341 participants (aged ≥ 60 years) of the Bambui (Brazil) population-based cohort study of aging. Potential confounding variables included sociodemographic characteristics and an array of health measures. The prevalence of T. cruzi infection was 37.5% and 56.3% of those infected had a major ECG abnormality. Baseline T. cruzi infection was correlated with higher levels of African and Native American ancestry, which in turn were strongly associated with poor socioeconomic circumstances. Cardiomyopathy in infected persons was not significantly associated with African or Native American ancestry levels. Infected persons with a major ECG abnormality were at increased risk of 15-year mortality relative to their counterparts with no such abnormalities (adjusted hazard ratio = 1.80; 95% 1.41, 2.32). African and Native American ancestry levels had no significant effect modifying this association. Our findings indicate that African and Native American ancestry have no influence on the presence of major ECG abnormalities and had no influence on the ability of an ECG abnormality to predict mortality in older people infected with T. cruzi. In contrast, our results revealed a strong and independent association between prevalent T. cruzi infection and higher levels of African and Native American ancestry. Whether this association is a consequence of genetic background or differential exposure to infection remains to be determined.

  15. Araxa Group in the type-area: A fragment of Neoproterozoic oceanic crust in the Brasilia Fold Belt; Grupo Araxa em sua area tipo: um fragmento de crosta oceanica Neoproterozoica na faixa de dobramentos Brasilia

    Energy Technology Data Exchange (ETDEWEB)

    Seer, Hildor Jose [Centro Federal de Educacao Tecnologica de Araxa, (CEFET), MG (Brazil); Brod, Jose Affonso; Fuck, Reinhardt Adolfo; Pimentel, Marcio Martins; Boaventura, Geraldo Resende; Dardenne, Marcel Auguste [Brasilia Univ., DF (Brazil). Inst. de Geociencias

    2001-09-01

    This study reviews the geological characteristics and puts forward a new evolution model for the Araxa Group in its type-area, the southern segment of the Neo proterozoic Brasilia Belt, Minas Gerais, Brazil. The Araxa Group is confined within a thrust sheet belonging to a syn formal regional fold, the Araxa Syn form, overlying two other thrust sheets made of the Ibia and Canastra Groups. The Araxa Group is described as a tectono stratigraphic terrane in the sense of Howell (1993). It comprises an igneous mafic sequence, with fine and coarse grained amphibolites, associated with pelitic meta sedimentary rocks, and subordinate psanmites. All rocks were metamorphosed to amphibolite facies at ca. 630 Ma ago and were intruded by collisional granites. The amphibolites represent original basaltic and gabbroic rocks, with minor ultramafic (serpentinite/ amphibole-talc schist). The basalts are similar to high Fe O tholeiites, with REE signatures that resemble E-MORB and {epsilon}{sub Nd(T)} =+ 1.1. The meta sedimentary rocks are interpreted as the result of a marine deep-water sedimentation. They have Sm-Nd model ages of 1,9 Ga, and {epsilon}{sub Nd(T)} = -10.21. The amphibolites and metasediments could represent a fragment of back-arc oceanic crust. The data presented here differ significantly from the original definition of Barbosa et al. (1970) who describe the Araxa Group as a pelitic/psanmitic sequence and the collisional granites as a basement complex. (author)

  16. C, O, and Sr isotopic variations in Neoproterozoic-Cambrian carbonate rocks from Sete Lagoas Formation (Bambuí Group, in the Southern São Francisco Basin, Brazil

    Directory of Open Access Journals (Sweden)

    Cristian Guacaneme

    2017-08-01

    Full Text Available ABSTRACT: High-resolution chemostratigraphic data of carbonates from the Sete Lagoas Formation (Bambuí Group show large variations on the C, O, and Sr isotope compositions. Impure limestones at the base show primal δ13C values between -1.0 and 0‰, and δ18O values between -12.0 and -8.0‰. However, some dolostones demonstrate δ13C values varying from +2.8 to -6.8‰, highly radiogenic 87Sr/86Sr ratios (>0.7111, and low Sr concentrations (900 ppm. They are linked to depositional controls on the carbonate platform, such as fluvial and/or submarine water influx, in which carbonates deposited on the proximal sector exhibit significant Sr isotopic variations and those on the distal sector were not subject to such controls, resulting in very homogeneous Sr isotope profiles. However, 87Sr/86Sr ratios of the distal carbonates are less radiogenic than carbonates expected for late Ediacaran (~0.7085. This discrepancy suggests a restricted marine basin without Sr isotopic homogenization with contemporary oceans and, in this case, global correlations based on Sr isotope stratigraphy are not reliable.

  17. Biogeochemical and micropaleontological study of black chert, Sete Lagoas Formation, Bambui Group (Late Proterozoic), Sao Gabriel (GO), Brazil

    International Nuclear Information System (INIS)

    Subacius, S.M.R.

    1985-01-01

    The biogeochemical study of amorphous and structured organic matter (OM) in two samples of thinly laminated black cherts (SG-1 and SG-2) from Sete Lagoas Formation, State of Goias, Brazil, is presented. The spectra analysis of infra-red, electron paramagnetic resonance and isotope ratio of C-12 and C-13 shown that: the amorphous OM consists of a soluble fraction (SF) and a insoluble fraction (Kerogen), which only the latter is syngenetic; the allochthonous SF comes from several sources, mainly from Phanerozoic sediments and soil contamination; the SG-1 and SG-2 Kerogens have δ 13 C values (-27.2 per mille and - 29.2 per mille respectively), which suggest OM photosynthetized and submitted to a mild thermal hystory; although the preserved microbiota is dominated by allochthonous elements (colonial fragments) and planktonic forms, both Kerogens were derived for the most part from photo-autotrophic benthonic communities, probably responsible for the lamination in the original carbonate rock, both SG-1 and SG-2 Kerogens exhibits O/C and H/C ratios comparable to Proterozoic humic Kerogens (type IV); the preserved microflora represents a microbial community of the chert-algae facies typical of the Middle and upper Proterozoic; and the occurence of rare acritarchs (Kildinella spp.) in the microflora is biostratigraphically significant in that it suggests a Late Riphean or Vendian age (950-570 m.y.) for the Sete Lagoas Formation. (Author) [pt

  18. Palaeomagnetism of neoproterozoic formations in the volta basin ...

    African Journals Online (AJOL)

    The Volta basin lies on the southern part of the West African craton, more precisely on the Leo (or Man) craton. The Dahomeyides chain is thrust onto its eastern fringe. The Volta basin is filled with Neoproterozoic to Cambro- Ordovician sediments. From bottom to top they are: the Boumbouaka Supergroup made of ...

  19. Neoproterozoic tectonics of the Arabian-Nubian Shield

    NARCIS (Netherlands)

    Blasband, B.

    2006-01-01

    The Neoproterozoic tectonic development of the Arabian-Nubian Shield (ANS) can be divided in three parts: 1) the oceanic stage; 2) the arc-accretion stage; 3) the extensional stage. Three key-areas in the Arabian-Nubian Shield, namely the Bi'r Umq Complex, The Tabalah and Tarj Complex and the Wadi

  20. In situ gamma radiation measurements in the Neoproterozoic rocks ...

    Indian Academy of Sciences (India)

    Keywords. Gamma ray spectrometry; Neoproterozoic; uranium; Sirohi; Sindreth; NW India. ... variable in their signatures reflecting their variable source rocks. In the area between the Balda and Paladi villages, northeast of Sirohi, measurements in vicinity of a N–S running shear zone, have shown U enrichment up to 8 ppm.

  1. Palaeomagnetism of neoproterozoic formations in the volta basin ...

    African Journals Online (AJOL)

    The palaeolatitudes of the older formations about 44.9° S and that of the younger sites about 9.1° S show a migration of the West African craton from medium to low latitude during the Neoproterozoic, in conformity with the Snowball Earth hypothesis. KEYWORDS: West African craton, Volta basin, Virtual Geomagnetic Pole, ...

  2. palaeomagnetism of neoproterozoic formations in the volta basin

    African Journals Online (AJOL)

    Admin

    9.1° S show a migration of the West African craton from medium to low latitude during the Neoproterozoic, in conformity with the ..... rocks from the Juiz de Fora. Complex, SE Brazil. Earth and Planetary. Sciences Letters 209, 131–147. Raposo, M.I., McReath, I., and D'Agrella-Filho, M.S.,. 2006. Magnetic fabrics, rock.

  3. Continental rift-setting and evolution of Neoproterozoic Sindreth ...

    Indian Academy of Sciences (India)

    The Neoproterozoic Sindreth Basin, NW India, and its surrounding area represent a half graben structure situated between the undeformed Malani Igneous Suite (MIS) in the west and a corridor of coeval Cryogenian ductile deformation, anatexis and granite intrusion in the east. The main lithologies observed in the basin ...

  4. Testing the "Mudball Earth" Hypothesis: Are Neoproterozoic Glacial Deposits Capped with Supraglacial Dust?

    Science.gov (United States)

    Goodman, J. C.; Alvim Lage, C.

    2014-12-01

    The Snowball Earth hypothesis has inspired several variants which may help to explain some of the great mysteries of the Neoproterozoic glaciations. One of these, the "Mudball Earth", proposes that as the Earth remained completely frozen for millions of years, a layer of dust accumulated on the ice surface. This dust layer would darken the planet, making it easier for the Earth to escape from the highly stable snowball climate state. This hypothesis is testable: after the ice melted at the end of a glacial era, this dust would sink to the bottom of the ocean, possibly forming a distinct clay, mud, or silt layer on the top of the glacial till deposits: this "clay drape" would then be covered by the cap carbonates that mark a return to warm climate. Sublimation and ice flow during the glacial episode should make this layer thicker at the equator and thinner or absent in the poles. Is this clay layer actually present in the rock record? Is it more prevalent at the paleoequator, as predicted? A clay drape has been noticed anecdotally, but no global survey has been done to date. We conducted a thorough literature review of all sites where Neoproterozoic glacial diamictites have been observed, identifying the type of rock that lies between the diamictite and the postglacial cap carbonate, when present, during both Sturtian and Marinoan glacial periods. Only a few publications identify a distinct clay/silt/mud layer that might represent weathered dust. These sites are not grouped by paleolatitude in any obvious way. With access only to published reports, we cannot determine whether such a layer is absent, went unreported, or was misinterpreted by us. With this work we hope to attract the attention of Neoproterozoic field geologists, inviting them to comment on the presence or absence of strata which could confirm or reject the "Mudball" hypothesis.

  5. Iron isotope biogeochemistry of Neoproterozoic marine shales

    Science.gov (United States)

    Kunzmann, Marcus; Gibson, Timothy M.; Halverson, Galen P.; Hodgskiss, Malcolm S. W.; Bui, Thi Hao; Carozza, David A.; Sperling, Erik A.; Poirier, André; Cox, Grant M.; Wing, Boswell A.

    2017-07-01

    Iron isotopes have been widely applied to investigate the redox evolution of Earth's surface environments. However, it is still unclear whether iron cycling in the water column or during diagenesis represents the major control on the iron isotope composition of sediments and sedimentary rocks. Interpretation of isotopic data in terms of oceanic redox conditions is only possible if water column processes dominate the isotopic composition, whereas redox interpretations are less straightforward if diagenetic iron cycling controls the isotopic composition. In the latter scenario, iron isotope data is more directly related to microbial processes such as dissimilatory iron reduction. Here we present bulk rock iron isotope data from late Proterozoic marine shales from Svalbard, northwestern Canada, and Siberia, to better understand the controls on iron isotope fractionation in late Proterozoic marine environments. Bulk shales span a δ 56Fe range from -0.45 ‰ to +1.04 ‰ . Although δ 56Fe values show significant variation within individual stratigraphic units, their mean value is closer to that of bulk crust and hydrothermal iron in samples post-dating the ca. 717-660 Ma Sturtian glaciation compared to older samples. After correcting for the highly reactive iron content in our samples based on iron speciation data, more than 90% of the calculated δ 56Fe compositions of highly reactive iron falls in the range from ca. -0.8 ‰ to +3 ‰ . An isotope mass-balance model indicates that diagenetic iron cycling can only change the isotopic composition of highly reactive iron by seawater iron reservoir, control the isotopic composition of highly reactive iron. Considering a long-term decrease in the isotopic composition of the iron source to the dissolved seawater Fe(II) reservoir to be unlikely, we offer two possible explanations for the Neoproterozoic δ 56Fe trend. First, a decreasing supply of Fe(II) to the ferrous seawater iron reservoir could have caused the reservoir

  6. The Mafic Lower Crust of Neoproterozoic age beneath Western Arabia: Implications for Understanding African Lower Crust

    Science.gov (United States)

    Stern, R. J.; Mooney, W. D.

    2011-12-01

    We review evidence that the lower crust of Arabia - and by implication, that beneath much of Africa was formed at the same time as the upper crust, rather than being a product of Cenozoic magmatic underplating. Arabia is a recent orphan of Africa, separated by opening of the Red Sea ~20 Ma, so our understanding of its lower crust provides insights into that of Africa. Arabian Shield (exposed in W. Arabia) is mostly Neoproterozoic (880-540 Ma) reflecting a 300-million year process of continental crustal growth due to amalgamated juvenile magmatic arcs welded together by granitoid intrusions that make up as much as 50% of the Shield's surface. Seismic refraction studies of SW Arabia (Mooney et al., 1985) reveal two layers, each ~20 km thick, separated by a well-defined Conrad discontinuity. The upper crust has average Vp ~6.3 km/sec whereas the lower crust has average Vp ~7.0 km/sec, corresponding to a granitic upper crust and gabbroic lower crust. Neogene (Yemen to Syria. Many of these lavas contain xenoliths, providing a remarkable glimpse of the lower-crustal and upper-mantle lithosphere beneath W. Arabia. Lower crustal xenoliths brought up in 8 harrats in Saudi Arabia, Jordan, and Syria are mostly 2-pyroxene granulites of igneous (gabbroic, anorthositic, and dioritic) origin. They contain plagioclase, orthopyroxene, and clinopyroxene, and a few contain garnet and rare amphibole and yield mineral-equilibrium temperatures of 700-900°C. Pyroxene-rich and plagioclase-rich suites have mean Al2O3 contents of 13% and 19%, respectively: otherwise the two groups have similar elemental compositions, with ~50% SiO2 and ~1% TiO2, with low K2O (time. Lower crust of Arabia clearly formed during Neoproterozoic time, about the same time as its upper crust complement; a similar origin for the lower crust beneath the broad expanses of Neoproterozoic crust in N and E Africa is likely. There is no evidence that any of the mafic lower crust of Arabia formed due to underplating by

  7. Is the Neoproterozoic oxygen burst a supercontinent legacy?

    Directory of Open Access Journals (Sweden)

    Melina eMacouin

    2015-09-01

    Full Text Available The Neoproterozoic (1000–542 Myr ago witnessed the dawn of Earth as we know it with modern-style plate tectonics, high levels of O2 in atmosphere and oceans and a thriving fauna. Yet, the processes leading to the fully oxygenation of the external envelopes, its exact timing and its link with the inner workings of the planet remain poorly understood. In some ways, it is a chicken and egg question: did the Neoproterozoic Oxygenation Event (NOE cause life blooming, low-latitudes glaciations and perturbations in geochemical cycles or is it a consequence of these phenomena? Here, we suggest that the NOE may have been triggered by multi-million years oxic volcanic emissions along a protracted period at the end of the Neoproterozoic when continents were assembled in the Rodinia supercontinent. We report a very oxidized magma source at the upper mantle beneath a ring of subducting margins around Rodinia, and detail here the evidence at the margin of the Arabian shield. We investigate the 780 Ma Biotite and Pink granites and associated rocks of the Socotra Island with rock magnetic and petrographic methods. Magnetic susceptibility and isothermal remanent magnetization acquisitions show that, in these granites, both magnetite and hematite are present. Hematite subdivides magnetite grains into small grains. Magnetite and hematite are found to be primary, and formed at the early magmatic evolution of the granite at very high oxygen fugacity. Massive degassing of these oxidized magmas would reduce the sink for oxygen, and consequently contribute to its rise in the atmosphere with a net O2 flux of at least 2.25 x 107 Tmol. Our conceptual model provides a deep Earth link to the NOE and implies the oxygenation burst has occurred earlier than previously envisaged, paving the way for later changes in the outer envelopes of the planet epitomized on the extreme Neoproterozoic glaciations and the appearance of the first animals.

  8. Geochronology of Neoproterozoic Plutons and Sandstones in the Western Jiangnan Orogen: a Reappraisal of Amalgamation between Yangtze and Cathaysia Blocks in South China

    Science.gov (United States)

    Ma, X.; Yang, K.

    2015-12-01

    Widespread exposure of Meso-Neoproterozoic strata and abundant Neoproterozoic plutons occur along the Jiangnan orogenic belt, a tectonic suture between the composite Cathaysia and Yangtze Blocks in South China, with remarkable angular unconformities between the Xiajiang Group and the underlying Sibao. LA-ICP-MS U-Pb dating of the basement sedimentary sequences (e.g. Xiajiang Group and Sibao Group) and the relevant granitic pluton (Motianling pluton) provides new information about the pre-Cambrian evolution of the southeastern Yangtze block margin along the western Jiangnan orogen. The depositional age of Sibao Group located in the Southeast Guizhou Province can be constrained at 825-835 Ma by the youngest detrital zircon ages and crystallization age of the intrusive Motianling granitic pluton. The maximum depositional age of the Xiajiang Group is estimated to be ca. 795 Ma. Four main age populations are evident in Sibao Group: 0.83-1.0 Ga, 1.3-1.5 Ga, 1.6-1.8 Ga and 2.2-2.6 Ga. The distinguished age populations in the Xiajiang Group are identical to those in the Sibao Group but lack in ranges of 1.3-1.5 Ga. Local abundant (China Block in the breakup the Rodinia, it is more reasonable to place Yangtze and Cathaysia Blocks on the western margin rather than the center of Rodinia supercontinent during the late-Neoproterozoic time.

  9. Association of cognitive impairment, activity limitation with latent traits in the GHQ-12 in the older elderly. The Bambui Health and Aging Study (BHAS).

    Science.gov (United States)

    Castro-Costa, Erico; Uchoa, Elizabeth; Firmo, Josélia Oliveira Araújo; Lima-Costa, Maria Fernanda; Prince, Martin

    2008-12-01

    The 12 item-General Health Questionnaire (GHQ-12) is the shortest version of GHQ. The questionnaire works as well as the longer instruments and is used more frequently in epidemiological surveys. It is an effective instrument for aging studies because of its brevity and absence of somatic symptoms. Previous studies of Principal Component Analysis (PCA) were carried out in adult populations only, demonstrating two- and three-factor solutions. This study involved 392 participants over 75 years old in a population-based survey in Bambui, Brazil. Both PCA and Confirmatory Factor Analysis (CFA) were performed. In CFA, several factor structures were compared using different goodness-of-fit indices. (The association between factor scores of the model with the best fit and participant characteristics were analyzed by linear regression). PCA suggested a three-factor model. Graetz's three-factor solution (Anxiety Depression, Social Dysfunction and Loss of Confidence) was the best model in CFA according to goodness-of-fit indices. Activity limitation and poor self-reported global health were associated with the anxiety/depression and social dysfunction factors. Cognitive impairment and female gender were associated with social dysfunction. Loss of confidence was not associated with these or other relevant variables. The three-factor solution proposed by Graetz seems to be the best fit also for people over 75 years old. Further studies are needed to understand the conceptual and practical relevance of these underlying factors, particularly loss of confidence in the elderly population.

  10. Selenium isotope evidence for progressive oxidation of the Neoproterozoic biosphere

    Science.gov (United States)

    Pogge von Strandmann, Philip A. E.; Stüeken, Eva E.; Elliott, Tim; Poulton, Simon W.; Dehler, Carol M.; Canfield, Don E.; Catling, David C.

    2015-01-01

    Neoproterozoic (1,000–542 Myr ago) Earth experienced profound environmental change, including ‘snowball' glaciations, oxygenation and the appearance of animals. However, an integrated understanding of these events remains elusive, partly because proxies that track subtle oceanic or atmospheric redox trends are lacking. Here we utilize selenium (Se) isotopes as a tracer of Earth redox conditions. We find temporal trends towards lower δ82/76Se values in shales before and after all Neoproterozoic glaciations, which we interpret as incomplete reduction of Se oxyanions. Trends suggest that deep-ocean Se oxyanion concentrations increased because of progressive atmospheric and deep-ocean oxidation. Immediately after the Marinoan glaciation, higher δ82/76Se values superpose the general decline. This may indicate less oxic conditions with lower availability of oxyanions or increased bioproductivity along continental margins that captured heavy seawater δ82/76Se into buried organics. Overall, increased ocean oxidation and atmospheric O2 extended over at least 100 million years, setting the stage for early animal evolution. PMID:26679529

  11. Biomarkers of a Low-Latitude Neoproterozoic Glaciation

    Science.gov (United States)

    Olcott, A. N.; Sessions, A. L.; Corsetti, F. A.; Kaufman, A. J.

    2005-12-01

    Neoproterozoic low-latitude glaciations are often considered times of great biologic limitation because of the hypothesized presence of thick, global sea ice. Alternatively, climate models have suggested that tropical oceans could have remained ice-free, or covered by only thin sea ice, allowing life to continue unimpeded throughout the glaciations. The analysis of organic remains from synglacial sediments provides an approach to address the debate. Here we describe molecular, isotopic, and petrographic analyses of organic rich strata (up to 3.0 percent TOC) deposited in southeastern Brazil during Neoproterozoic low-latitude glaciation ca. 700 Ma. These strata contain extractable biomarkers, including 2-α-methyl hopanes, 2,3,6-trimethylarylisoprenoids, C29-C31 hopanes, and C27-C29 steranes. The preserved biomarkers reflect the presence of a complex and productive ecosystem comprised of both aerobic and anaerobic phototrophs, heterotrophs, and eukaryotes. The biomarker data indicate euxinia extending into the photic zone, providing evidence that the oceans were strongly stratified. Significantly, the occurrence of photosynthetic cyanobacteria and green sulfur bacteria at this time indicates that sea-ice cover at this location was thin to nonexistent, and is incompatible with models for snowball Earth that envision kilometers of ice thickness.

  12. Socioeconomic Position, But Not African Genomic Ancestry, Is Associated With Blood Pressure in the Bambui-Epigen (Brazil) Cohort Study of Aging.

    Science.gov (United States)

    Lima-Costa, M Fernanda; Mambrini, Juliana Vaz de Mello; Leite, Maria Lea Corrêa; Peixoto, Sérgio Viana; Firmo, Josélia Oliveira Araújo; Loyola Filho, Antônio Ignácio de; Gouveia, Mateus H; Leal, Thiago P; Pereira, Alexandre Costa; Macinko, James; Tarazona-Santos, Eduardo

    2016-02-01

    The study objective is to examine the role of African genome origin on baseline and 11-year blood pressure trajectories in community-based ethnoracially admixed older adults in Brazil. Data come from 1272 participants (aged ≥60 years) of the Bambui cohort study of aging during 11 years of follow-up. Outcome measures were systolic blood pressure, diastolic blood pressure, and hypertension control. Potential confounding variables were demographic characteristics, socioeconomic position (schooling and household income), and health indicators (smoking, sedentary lifestyle, high-density lipoprotein cholesterol, waist circumference, diabetes mellitus, and cardiovascular diseases), including antihypertensive drug use. We used 370 539 single-nucleotide polymorphisms to estimate each individual's African, European, and Native American trihybrid ancestry proportions. Median African, European, and Native American ancestry were 9.6%, 84.0%, and 5.3%, respectively. Among those with African ancestry, 59.4% came from East and 40.6% from West Africa. Baseline systolic and diastolic blood pressure, controlled hypertension, and their respective trajectories, were not significantly (P>0.05) associated with level (in quintiles) of African genomic ancestry. Similar results were found for West and East African subcontinental origins. Lower schooling level (higher) showed a significant and positive association with systolic blood pressure (Adjusted β=2.92; 95% confidence interval, 0.85-4.99). Lower monthly household income per capita (higher) showed an inverse association with hypertension control (β=-0.35; 95% confidence interval, -0.63 to -0.08, respectively). Our results support the view that favors social and environmental factors as determinants of blood pressure and hypertension control. © 2015 American Heart Association, Inc.

  13. Towards a quantitative understanding of the late Neoproterozoic carbon cycle

    DEFF Research Database (Denmark)

    Bjerrum, Christian Jannik; Canfield, Donald Eugene

    2011-01-01

    The cycles of carbon and oxygen at the Earth surface are intimately linked, where the burial of organic carbon into sediments represents a source of oxygen to the surface environment. This coupling is typically quantified through the isotope records of organic and inorganic carbon. Yet, the late...... Neoproterozoic Eon, the time when animals first evolved, experienced wild isotope fluctuations which do not conform to our normal understanding of the carbon cycle and carbon-oxygen coupling. We interpret these fluctuations with a new carbon cycle model and demonstrate that all of the main features...... of the carbonate and organic carbon isotope record can be explained by the release of methane hydrates from an anoxic dissolved organic carbon-rich ocean into an atmosphere containing oxygen levels considerably less than today....

  14. Integrated Geochemical-Petrographic Insights on Neoproterozoic Ocean Oxygenation

    Science.gov (United States)

    Hood, A.; Planavsky, N.; Wallace, M. W.; Wang, X.; Gueguen, B.

    2015-12-01

    Novel isotope systems have the potential to provide new insights into biogeochemical cycling in Earth's evolving oceans. However, much recent paleo-redox work has been done without extensive consideration of sample preservation or paleoenvironmental setting. Neoproterozoic reef complexes from South Australia provide a perfect setting to test geochemical redox proxies (e.g. uranium isotopes and trace metal chemistry) within a well-defined sedimentological and petrographic context. These reefs developed significant frameworks over ~1km of steep platform relief from the seafloor, and contain a variety of carbonate components including primary dolomite marine cements. Analysis of a variety of components within these reefs reveals significant variation in uranium isotope composition and trace metal chemistry between components, even within a single sample. Marine cements, which precipitated directly from seawater, have much lower contamination element concentrations (e.g. Al, Zr, Th) than depositional micrites, and appear to represent the best archive of ancient ocean conditions. These cements have high levels of Fe, Mn in shallow and deep reef facies (e.g. 2-3wt% Fe), but only Fe-oxide inclusions in peritidal settings. This distribution suggests ferruginous conditions under a surficial chemocline in this Neoproterozoic seawater. Uranium isotopes from pristine marine cements have relatively heavy values compared to modern seawater (median = -0.22 δ238U). These values are essentially unfractionated from riverine inputs, which we interpret as tracking extensive near quantitative low-T reduction of U(VI) to U(IV) by abundant soluble iron in seawater. Depositional components and late stage cements have a much lighter and more variable U isotope compositions (-0.71 to -0.08 δ238U). This work highlights the need for fundamental petrographic constraints on the preservation of depositional geochemical signatures in the future use and development of sedimentary redox proxies.

  15. Rare late Neoproterozoic detritus in SW Scandinavia as a response to distant tectonic processes

    Czech Academy of Sciences Publication Activity Database

    Sláma, Jiří

    2016-01-01

    Roč. 28, č. 6 (2016), s. 394-401 ISSN 0954-4879 Institutional support: RVO:67985831 Keywords : zircon * tectonic processes * Neoproterozoic * orogenic processes Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.214, year: 2016

  16. Microanalyzes of remarkable microfossils of the Late Mesoproterozoic-Early Neoproterozoic

    Science.gov (United States)

    Cornet, Yohan; Beghin, Jérémie; Baludikay, Blaise; François, Camille; Storme, Jean-Yves; Compère, Philippe; Javaux, Emanuelle

    2016-04-01

    The Late Mesoproterozoic-Early Neoproterozoic is an important period to investigate the diversification of early eukaryotes [1]. Following the first appearance of red algae in the Late Mesoproterozoic, other (morphological or molecular) fossils of crown groups are recorded during the Early Neoproterozoic, including green algae, sponges, amoebozoa and possibly fungi. Other microfossils also includes unambiguous eukaryotes, including several distinctive forms for that time period, such as the acritarchs Cerebrosphaera buickii (˜820-720 Ma), Trachyhystrichosphaera aimika and T . botula (1100-720 Ma), and the multicellular eukaryotic problematicum taxon Jacutianema solubila (1100-?720 Ma). To further characterize the taxonomy of these microfossils and to test hypotheses about their possible relationships to crown groups, we combine analyzes of their morphology, wall ultrastructure and microchemistry, using optical microscopy, Scanning and Transmission Electron microscopy (SEM and TEM), as well as Raman and FTIR microspectroscopy respectively. Cerebrosphaera populations from the Svanbergfjellet formation, Spitsbergen, and from the Kanpa Formation, Officer Basin, Australia, include organic vesicles with dark and robust walls ornamented by cerebroid folds [2]. Our study shows the occurrence of complex tri- or bi-layered wall ultrastructures and a highly aromatic composition [3]. The genus Trachyhystrichosphaera includes various species characterized by the presence of a variable number of hollow heteromorphic processes [2]. Preliminary infrared microspectroscopy analyzes performed on two species, T. aimika and T. botula, from the 1.1 Ga Taoudeni Basin, Mauritania, and from the ˜1.1 - 0.8 Ga Mbuji-Mayi Supergroup, RDC, indicate a strong aliphatic and carbonyl composition of the wall biopolymer, with some differences linked to thermal maturity between the two locations. TEM is also performed to characterize the wall ultrastructure of these two species. Various morphotypes

  17. A Sulfate Aerosol Trigger for the Sturtian Neoproterozoic Snowball Event

    Science.gov (United States)

    Wordsworth, R. D.; Macdonald, F. A.

    2017-12-01

    Despite the dominance of the carbon cycle in determining the evolution of Earth's climate in general, certain events defy easy explanation via atmospheric CO2 changes alone. Here we discuss the particular role that transient planetary albedo changes via sulfate aerosol formation can play in major climate transitions. Specifically, we propose that SO2 outgassing associated with the eruption of the Franklin Large Igneous Province (LIP) led to the first Neoproterozoic Snowball event, the Sturtian, 716 Ma. We summarize U/Pb zircon and baddeleyite dating indicating the synchronicity of the Franklin eruptions and the onset of the Sturtian, and paleomagnetic data indicating that the Franklin erupted close to the equator. We then discuss in detail the modeling we have performed of eruption rate, the plume height achieved during basaltic fissure volcanism, the chemistry and microphysics of sulfate aerosol formation, and the dependence of aerosol longwave and shortwave radiative effects on atmospheric loading, particle size and surface albedo. We discuss the critical importance of the latitude of eruption, the tropopause height, and ocean dynamics in determining the strength and sign of aerosol radiative forcing. We finish by comparing the Franklin event with other LIP emplacement events in Earth history and make suggestions for future modeling.

  18. Polyphase Neoproterozoic orogenesis within the east Africa- Antarctica orogenic belt in central and northern Madagascar

    Science.gov (United States)

    Key, R.M.; Pitfield, P.E.J.; Thomas, Ronald J.; Goodenough, K.M.; Waele, D.; Schofield, D.I.; Bauer, W.; Horstwood, M.S.A.; Styles, M.T.; Conrad, J.; Encarnacion, J.; Lidke, D.J.; O'connor, E. A.; Potter, C.; Smith, R.A.; Walsh, G.J.; Ralison, A.V.; Randriamananjara, T.; Rafahatelo, J.-M.; Rabarimanana, M.

    2011-01-01

    Our recent geological survey of the basement of central and northern Madagascar allowed us to re-evaluate the evolution of this part of the East Africa-Antarctica Orogen (EAAO). Five crustal domains are recognized, characterized by distinctive lithologies and histories of sedimentation, magmatism, deformation and metamorphism, and separated by tectonic and/or unconformable contacts. Four consist largely of Archaean metamorphic rocks (Antongil, Masora and Antananarivo Cratons, Tsaratanana Complex). The fifth (Bemarivo Belt) comprises Proterozoic meta-igneous rocks. The older rocks were intruded by plutonic suites at c. 1000 Ma, 820-760 Ma, 630-595 Ma and 560-520 Ma. The evolution of the four Archaean domains and their boundaries remains contentious, with two end-member interpretations evaluated: (1) all five crustal domains are separate tectonic elements, juxtaposed along Neoproterozoic sutures and (2) the four Archaean domains are segments of an older Archaean craton, which was sutured against the Bemarivo Belt in the Neoproterozoic. Rodinia fragmented during the early Neoproterozoic with intracratonic rifts that sometimes developed into oceanic basins. Subsequent Mid- Neoproterozoic collision of smaller cratonic blocks was followed by renewed extension and magmatism. The global 'Terminal Pan-African' event (560-490 Ma) finally stitched together the Mid-Neoproterozoic cratons to form Gondwana. ?? The Geological Society of London 2011.

  19. Neoproterozoic extension in the greater dharwar craton: A reevaluation of the "betsimisaraka suture" in madagascar

    Science.gov (United States)

    Tucker, R.D.; Roig, J.-Y.; Delor, C.; Amlin, Y.; Goncalves, P.; Rabarimanana, M.H.; Ralison, A.V.; Belcher, R.W.

    2011-01-01

    The Precambrian shield of Madagascar is reevaluated with recently compiled geological data and new U-Pb sensitive high-resolution ion microprobe (SHRIMP) geochronology. Two Archean domains are recognized: the eastern Antongil-Masora domain and the central Antananarivo domain, the latter with distinctive belts of metamafic gneiss and schist (Tsaratanana Complex). In the eastern domain, the period of early crust formation is extended to the Paleo-Mesoarchean (3.32-3.15 Ga) and a supracrustal sequence (Fenerivo Group), deposited at 3.18 Ga and metamorphosed at 2.55 Ga, is identified. In the central domain, a Neoarchean period of high-grade metamorphism and anatexis that affected both felsic (Betsiboka Suite) and mafic gneisses (Tsaratanana Complex) is documented. We propose, therefore, that the Antananarivo domain was amalgamated within the Greater Dharwar Craton (India + Madagascar) by a Neoarchean accretion event (2.55-2.48 Ga), involving emplacement of juvenile igneous rocks, high-grade metamorphism, and the juxtaposition of disparate belts of mafic gneiss and schist (metagreenstones). The concept of the "Betsimisaraka suture" is dispelled and the zone is redefined as a domain of Neoproterozoic metasedimentary (Manampotsy Group) and metaigneous rocks (Itsindro-Imorona Suite) formed during a period of continental extension and intrusive igneous activity between 840 and 760 Ma. Younger orogenic convergence (560-520 Ma) resulted in east-directed overthrusting throughout south Madagascar and steepening with local inversion of the domain in central Madagascar. Along part of its length, the Manampotsy Group covers the boundary between the eastern and central Archean domains and is overprinted by the Angavo-Ifanadiana high-strain zone that served as a zone of crustal weakness throughout Cretaceous to Recent times.

  20. Unraveling the tectonic evolution of a Neoproterozoic-Cambrian active margin in the Ribeira Orogen (Se Brazil): U-Pb and Lu-Hf provenance data

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Gabriel Lamounier de F. [Servico Geologico do Estado do Rio de Janeiro (DRM-RJ), Niteroi, RJ (Brazil); Schmitt, Renata; Bongiolo, Everton M.; Mendes, Julio [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Basei, Miguel S. [Universidade de Sao Paulo (USP), SP (Brazil)

    2015-07-01

    Full text: The Neoproterozoic-Ordovician Central Ribeira Orogen, in SE Brazil, presents two contrasting tectonic domains in its southern portion: (a) The Arc Domain constituted of Neoproterozoic to Paleozoic magmatic rocks and low P-high T metamorphic para (Sao Fidelis Group) - and ortho- derived units (in Oriental Terrane); and (b) The Basement Domain, constituted of a Paleoproterozoic and Neoproterozoic medium P-high T metamorphic para (Palmital-Buzios Succession)- and ortho-derived units (in Cabo Frio Tectonic Domain). Our work focuses on paraderived rocks sequences from both domains. The provenance analysis using U-Pb and Lu-Hf in zircon grains is presented here as an effective tool to unravel the paleogeography and nature of the pre-collisional sedimentary basins. We performed 505 analyses (U-Pb) on detrital zircon grains and some metamorphic overgrowths from six paragneiss samples. Besides, 141 analyses (Lu-Hf) in six samples only on the detrital zircon grains domains. All samples present a main peak from Neoproterozoic sources (750-570 Ma) and the other minor peak in the Stenian/Tonian periods (1200-850Ma), this indicate an orogenic contribution for this basin. Scarce register from the Mesoproterozoic and two peaks in the Archean/Paleoproterozoic (2.6 and 1.9 Ga) are recognized as a contribution from an ancient continent. The Lu-Hf data reveals a juvenile source for the detrital zircon grains from Buzios Succession while Palmital and Sao Fidelis Group units show a main crustal signature for their detrital zircon population. Based on the U-Pb and Lu-Hf data presented here, plus petrological data, geological correlations, and compilation of data from literature, we propose a tectonic model for the origin of para-derived rocks from the eastern part of the Ribeira Orogen. Starting with an extensional environment of ca. 600 Ma in a back-arc basin (Buzios succession deposition) and continuing as an active margin between 570 and 550 Ma in the fore-arc and prism

  1. Continental flood basalt weathering as a trigger for Neoproterozoic Snowball Earth

    Science.gov (United States)

    Cox, Grant M.; Halverson, Galen P.; Stevenson, Ross K.; Vokaty, Michelle; Poirier, André; Kunzmann, Marcus; Li, Zheng-Xiang; Denyszyn, Steven W.; Strauss, Justin V.; Macdonald, Francis A.

    2016-07-01

    Atmospheric CO2 levels and global climate are regulated on geological timescales by the silicate weathering feedback. However, this thermostat has failed multiple times in Earth's history, most spectacularly during the Cryogenian (c. 720-635 Ma) Snowball Earth episodes. The unique middle Neoproterozoic paleogeography of a rifting, low-latitude, supercontinent likely favored a globally cool climate due to the influence of the silicate weathering feedback and planetary albedo. Under these primed conditions, the emplacement and weathering of extensive continental flood basalt provinces may have provided the final trigger for runaway global glaciation. Weathering of continental flood basalts may have also contributed to the characteristically high carbon isotope ratios (δ13 C) of Neoproterozoic seawater due to their elevated P contents. In order to test these hypotheses, we have compiled new and previously published Neoproterozoic Nd isotope data from mudstones in northern Rodinia (North America, Australia, Svalbard, and South China) and Sr isotope data from carbonate rocks. The Nd isotope data are used to model the mafic detrital input into sedimentary basins in northern Rodinia. The results reveal a dominant contribution from continental flood basalt weathering during the ca. 130 m.y. preceding the onset of Cryogenian glaciation, followed by a precipitous decline afterwards. These data are mirrored by the Sr isotope record, which reflects the importance of chemical weathering of continental flood basalts on solute fluxes to the early-middle Neoproterozoic ocean, including a pulse of unradiogenic Sr input into the oceans just prior to the onset of Cyrogenian glaciation. Hence, our new data support the hypotheses that elevated rates of flood basalt weathering contributed to both the high average δ13 C of seawater in the Neoproterozoic and to the initiation of the first (Sturtian) Snowball Earth.

  2. Ti-Zr placer mineralization in Neoproterozoic (Uppe r Riphean rocks of Kildin Formation and in contemporary beach sands of Sredny and Rybachy Peninsulas, Kola Region

    Directory of Open Access Journals (Sweden)

    Chickiryov I. V.

    2017-03-01

    Full Text Available Concentration mechanisms of titanium-zirconium placer mineralizat ion in Neoproterozoic terrigenous rocks of Zemlepakhtinskaya Formation, Kildin Group, and in contempo rary beach deposits from Sredny Peninsula and Motka Cape from Rybachy Peninsula (Kola region have been considered i n the paper. It has been shown that the rocks of Zemlepakhtinskaya Formation are facially variable. The shallow littoral facies are confined to the western and central parts of Sredny Peninsula, the deeper sublitt oral facies are confined to the eastern part of Sredny Peninsula and to Motka Cape of Rybachy Peninsula. It has b een established that lenses and beds with titanium-zirconium placer mineralization occur solely in littoral facies. The ore minerals in aleurite-psamite of Zemlepakhtinskaya Formation are represented by leucoxene, rutile and zircon, and in contemporary beach deposits – by ilmenite, rutile and minor zircon. Paleogeograp hic reconstruction indicates that almost all deposits of Neoproterozoic (Upper Riphean Kildin Group were accumulated in shallow (littoral and sublittoral environment during dominant humid climate and intense weat hering of source area. Thus, not only deposits of Zemlepakhtinskaya Formation, but also the whole succession of Kildin Group can be regarded perspective for placers' accumulation. The low grade of heavy minerals (mainly Ti an d Zr minerals in contemporary beach deposits from Sredny Peninsula and Motka Cape from Rybachy Peninsu la is related to weak weathering of the Baltic Shield during Quaternary and to accumulation of coarse debris in littoral zone, preventing the differentiation of sand by wave action.

  3. 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)

  4. Isotopic evidence for two neoproterozoic high-grade metamorphic events in the Brazilia belt

    International Nuclear Information System (INIS)

    Pimentel, Marcio Martins; Fuck, Reinhardt Adolfo; Piuzanna, Danielle; Moraes, Renato de; Gioia, Simone Maria C.L

    2001-01-01

    The Brasilia Belt is part of a Brasiliano/Pan African orogen developed between the Amazon and Sao Francisco cratons. The stabilization of the belt occurred after the last metamorphic event at ca. 620 Ma. There has been increasing geochronological evidence, however, for an older Neoproterozoic metamorphic event at ca. 780 Ma, observed mainly in high grade rocks of three large mafic-ultramafic complexes in the northern part of the belt. In this study we present: (i) new U-Pb and Sm-Nd geochronological data, (ii) a review of the existing metamorphic ages in the Brasilia Belt, and (iii) a discussion on the tectonic model to explain the two Neoproterozoic metamorphic ages (au)

  5. Lead isotope evolution across the Neoproterozoic boundary between craton and juvenile crust, Bayuda Desert, Sudan

    Science.gov (United States)

    Evuk, David; Lucassen, Friedrich; Franz, Gerhard

    2017-11-01

    Metaigneous mafic and ultramafic rocks from the juvenile Neoproterozoic Arabian Nubian Shield (ANS) and the Proterozoic, reworked Saharan Metacraton (SMC) have been analysed for major- and trace elements and Sr, Nd, and Pb isotopes. Most of the rocks are amphibolites metamorphosed at amphibolite facies conditions, some with relicts of a granulite facies stage. The other rocks are metapyroxenites, metagabbros, and some ultramafic rocks. Trace element compositions of the metabasaltic (dominantly tholeiitic) rocks resemble the patterns of island arcs and primitive lavas from continental arcs. Variable Sr and Nd isotope ratios indicate depleted mantle dominance for most of the samples. 207Pb/204Pb signatures distinguish between the influence of high 207Pb/204Pb old SMC crust and depleted mantle signatures of the juvenile ANS crust. The Pb isotope signatures for most metabasaltic rocks, metapyroxenites and metagabbros from SMC indicate an autochthonous formation. The interpretation of the new data together with published evidence from mafic xenoliths on SMC and ophiolite from ANS allows an extrapolation of mantle evolution in time. There are two lines of evolution in the regional mantle, one, which incorporates potential upper crust material during Neoproterozoic, and a second one with a depleted mantle signature since pre-Neoproterozoic that still is present in the Red Sea and Gulf of Aden spreading centres.

  6. Neoproterozoic granitoids and rhyolites of Wrangel Island: Geochemical affinity and geodynamic setting in the Eastern Arctic region

    Science.gov (United States)

    Luchitskaya, Marina V.; Moiseev, Artem V.; Sokolov, Sergey D.; Tuchkova, Marianna I.; Sergeev, Sergey A.; O'Sullivan, Paul B.; Verzhbitsky, Vladimir E.; Malyshev, Nikolay A.

    2017-11-01

    volcanic rocks lead us to assume a heterogeneous source of magmas, which included both crustal and mafic mantle components. Similar rift-related geodynamic settings were proposed for orthogneisses (565 Ma) and gabbro (540 Ma) of the Seward Peninsula, Alaska (Amato et al., 2009, 2014) and orthogneisses (656 and 574 Ma) of the Koolen gneiss dome, Chukotka, which indicate intense rifting. The rocks also exhibit some analogies with Neoproterozoic volcano-plutonic complexes of the Timanides grouped into I- and A-types (Kuznetsov et al., 2006; Pease et al., 2004). I-type granitoids are 700-515 Ma old and represent constituents of the volcanic-plutonic series of an active continental margin. A-type granitoids have isotopic ages of 565-500 Ma and are associated with volcanic rocks of the bimodal basalt-rhyolite series formed in extensional environments.

  7. Fertility of late Archaean basement granite in the vicinity of U-mineralized Neoproterozoic Bhima basin, peninsular India

    International Nuclear Information System (INIS)

    Senthil Kumar, P.; Srinivasan, R.

    2002-01-01

    Late Archaean granitoids constituting the basement for the Neoproterozoic Bhima Group are exposed along the southern margin of the Bhima basin in southern India. These are rich in accessory minerals such as sphene, allanite, apatite and zircon, which are the main carriers of uranium and thorium. In situ gamma-ray spectrometric analysis reveals that these granitoids have higher abundances of Th, U and K (Th range 10-43 ppm, mean 26 ppm; U range 3-21 ppm, mean 8 ppm; K range 1.2-5.2%, mean 4.0%) relative to granitoids occurring farther away from the basin. Thus, they belong to the class of fertile granitoids from the point of view of uranium mineralization. The granitoids have been mylnotized and hydrothermally altered in the Gugi-Ukkinal fault zone, which constitutes the zone of uranium mineralization discovered recently along the southern margin of the Bhima basin. Uranium apparently derived from hydrothermal leaching of basement granitoid rocks may have got deposited in the fault zone at the contact of carbonate rocks, which provided favourable geochemical environment (Eh-pH conditions) for uranium precipitation. (author)

  8. The strata and palaeo-geomorphology framework at the end of neoproterozoic and development mode of source rocks at the beginning of Cambrian in Tarim Basin, China

    Directory of Open Access Journals (Sweden)

    Xin Yang

    2017-12-01

    Full Text Available Referred to the new recognition from petroleum exploration of the Sinian to Cambrian in South China, it could be considered that the distribution of the early Cambrian source rocks was controlled by the palaeo-geomorphology at the end of Neoproterozoic in the Tarim Basin. Based on the zircon U-Pb dating of pyroclastic rock samples from the clastic rock stratum under the bottom of Cambrian carbonate rocks, the stratigraphic correlation of the Sinian to Cambrian was conducted to build the palaeo-geomorphology framework at the end of Neoproterozoic in Tarim Basin. Lastly, according to the development mode of source rocks at the beginning of Cambrian, the distribution of source rocks was predicted initially through the division of seismic facies. The youngest zircon concordia age of pyroclastic rocks from the bottom of well Tong 1 is 707±8Ma. It was revealed by the strata framework of the Sinian to Cambrian, the palaeo-geomorphology at the end of Neoproterozoic in Tarim Basin was characterized by an uplift highland in Bachu-Tazhong area, the south north high-low, and the west is higher than the east. The distribution of source rocks in the bottom of the Cambrian on the palaeo-platform and slopes was coincident with the Upper Sinian dolomite basically. But the contemporaneous sediment happened to be absent or changed in sedimentary facies on the uplift and its edges. From the seismic facies of the strata under the bottom of Cambrian, it could be concluded that source rocks in the type of the Xishanbraque Group (∈1xs was limited in the Manjiaer Depression, while the source rocks in the type of the Yuertusi Group (∈1y are widely distributed in south of Tabei Uplift, east Awat Depression, and even the Maigt Slope. However, among the west Awat Depression and western Tanguzibasi Depression, and the middle area of the Bachu-Tazhong Uplifts, the contemporaneous source rocks may have changed into sedimentary facies of tidal flat and lagoon, instead of

  9. Paleogeographic Evolution of the Late Neoproterozoic and Early Phanerozoic with New Paleomagnetic Constraints from West African Craton

    Science.gov (United States)

    Robert, B.; Besse, J.; Blein, O.; Greff-Lefftz, M.; Baudin, T.; Fernando, L.; Meslouh, S.; Belbadaoui, M.

    2015-12-01

    The paleogeographic evolution of the late Neoproterozoic and early Phanerozoic is dominated by the dispersion of Rodinia and the assembly of Gondwana. The timing of these two episodes is still highly debated, partly due to the low number of good quality paleomagnetic data. In order to better constrain the paleogeography for this epoch, we bring new paleomagnetic data on volcanic series from the West African Craton (WAC), which is a key block to understand the evolution of these two supercontinents. We have sampled well dated pyroclastic and lava flows from the groups of Ouarzazate (upper Ediacaran) and Taroudant (lower Cambrian) in the Anti-Atlas (Morocco). 500 samples from 105 sites were thermally demagnetized in laboratory. Our results highlight two major groups of directions, mainly carried by minerals of the titano-hematite family. Magnetite may also contribute sometimes to the magnetization. The first group displays a single polarity direction, with a shallow inclination and a south-east declination. This direction close to the expected direction derived from the Permo-Carboniferous segment of the Gondwana apparent polar wander path (APWP) is due to a remagnetization acquired during the Kiaman reversed polarity superchron (320-262Ma). The second group, observed in the Ouarzazate and Taroudant groups, consists of a dual polarity high inclination direction and may represent the characteristic magnetization. On the basis of geologic and paleomagnetic data from literature, we constructed an APWP for both WAC and Amazonia between 615 and 530Ma, assuming these two blocks were already accreted. We found a paleomagnetic solution in which Laurentia and WAC-Amazonia remained attached from ~615Ma up to the late Ediacaran, Laurentia remaining at low latitude during this period. Around ~550Ma, WAC-Amazonia separated from Laurentia and finally collided with the other Gondwanan blocks during the lower Cambrian, marking the final accretion of Gondwana.

  10. Organic carbon cycling as the keystone of Neoproterozoic climate evolution (Invited)

    Science.gov (United States)

    Pierrehumbert, R.

    2009-12-01

    Snowball glaciations are the most charismatic feature of the Neoproterozoic, but the central problem of Neoproterozoic climate evolution is the operation of the carbon cycle, as evidenced in the return of extreme 13C fluctuations after nearly a billion years of quiescence. A key organizing principle for the Neoproterozoic is the existence of a massive hypothetical organic carbon pool in the ocean, which is oxidized by the end of the Neoproterozoic (as laid out by Fike, et al. 2006 ). The carbon cycle couples to climate through its influence on atmospheric greenhouse gas content -- notably CO2 and CH4; accumulation of atmospheric O2 feeds back on this through atmospheric and oceanic chemistry. Evolution of oxygenic photosynthesis unquestionably occurred long before the dawn of the Neoproterozoic, so the Neoproterozoic climate and carbon turmoil is a product of the organic carbon storage dynamics rather than gross biological innovation. In this talk I will discuss how certain key components of the physical and geochemical system operate, though a comprehensive model accounting for all crucial aspects of the geological record is still lacking. Conversion of CO2 to O2 by photosynthesis and carbon burial, converts a greenhouse gas to a non-greenhouse gas,cooling the climate. Conversely, oxidation of an organic carbon pool either through respiration or sulfate reduction, releases CO2 and acts as a warming influence,also leading to a negative carbonate 13C excursion, as probably happened during the Shuram. If the Marinoan excursion has a similar mechanism we face the question of how such an event could initiate a glaciation, whereas the much stronger Shuram excursion did not. (The Gaskiers glaciation came long after the Shuram , and was not a Snowball). I will discuss how the climate response depends on the time scale of the exchange, with emphasis on buffering due to the response of silicate weathering. Insofar as the organic carbon pool existed at all, the key question

  11. Pressure-temperature evolution of Neoproterozoic metamorphism in the Welayati Formation (Kabul Block), Afghanistan

    Science.gov (United States)

    Collett, Stephen; Faryad, Shah Wali

    2015-11-01

    The Welayati Formation, consisting of alternating layers of mica-schist and quartzite with lenses of amphibolite, unconformably overlies the Neoarchean Sherdarwaza Formation of the Kabul Block that underwent Paleoproterozoic granulite-facies and Neoproterozoic amphibolite-facies metamorphic events. To analyze metamorphic history of the Welayati Formation and its relations to the underlying Sherdarwaza Formation, petrographic study and pressure-temperature (P-T) pseudosection modeling were applied to staurolite- and kyanite-bearing mica-schists, which crop out to the south of Kabul City. Prograde metamorphism, identified by inclusion trails and chemical zonation in garnet from the micaschists indicates that the rocks underwent burial from around 6.2 kbar at 525 °C to maximum pressure conditions of around 9.5 kbar at temperatures of around 650 °C. Decompression from peak pressures under isothermal or moderate heating conditions are indicated by formation of biotite and plagioclase porphyroblasts which cross-cut and overgrow the dominant foliation. The lack of sillimanite and/or andalusite suggests that cooling and further decompression occurred in the kyanite stability field. The results of this study indicate a single amphibolite-facies metamorphism that based on P-T conditions and age dating correlates well with the Neoproterozoic metamorphism in the underlying Sherdarwaza Formation. The rocks lack any paragenetic evidence for a preceding granulite-facies overprint or subsequent Paleozoic metamorphism. Owing to the position of the Kabul Block, within the India-Eurasia collision zone, partial replacement of the amphibolite-facies minerals in the micaschist could, in addition to retrogression of the Neoproterozoic metamorphism, relate to deformation associated with the Alpine orogeny.

  12. Age of Neoproterozoic bilatarian body and trace fossils, White Sea, Russia: implications for metazoan evolution.

    Science.gov (United States)

    Martin, M W; Grazhdankin, D V; Bowring, S A; Evans, D A; Fedonkin, M A; Kirschvink, J L

    2000-05-05

    A uranium-lead zircon age for a volcanic ash interstratified with fossil-bearing, shallow marine siliciclastic rocks in the Zimnie Gory section of the White Sea region indicates that a diverse assemblage of body and trace fossils occurred before 555.3 +/- 0.3 million years ago. This age is a minimum for the oldest well-documented triploblastic bilaterian Kimberella. It also makes co-occurring trace fossils the oldest that are reliably dated. This determination of age implies that there is no simple relation between Ediacaran diversity and the carbon isotopic composition of Neoproterozoic seawater.

  13. The 131-134 Ma A-type granites from northern Zhejiang Province, South China: Implications for partial melting of the Neoproterozoic lower crust

    Science.gov (United States)

    Hu, Qinghai; Yu, Kaizhang; Liu, Yongsheng; Hu, Zhaochu; Zong, Keqing

    2017-12-01

    different parent rocks. These granites have two-stage Nd model (TDM2(Nd)) ages of 1099 Ma-838 Ma, and zircons from these granites and the Neoproterozoic basement in the Gan-Hang Belt plot on the same evolutionary trend in the εHf(t)-age diagram. It is interesting to note that the collection of literature data shows a positive correlation between SiO2 and εNd(t) for the late Mesozoic A-granites in the Gan-Hang Belt, and the Neoproterozoic A-granites in the Gan-Hang Belt cluster in two groups of the high-SiO2-εNd(t) group and low-εNd(t) group. The positive correlation of SiO2-εNd(t) demonstrated by the late Mesozoic A-granites can be well explained by a high-degree of melting of mixtures between the two groups of Neoproterozoic A-granites. We thus suggest that the late Mesozoic A-type granites in the Gan-Hang Belt could have been derived from the rejuvenated Neoproterozoic rocks rather than directly from the Mesoproterozoic metamorphic basement as a result of subduction.

  14. Provenance and tectonic setting of siliciclastic rocks associated with the Neoproterozoic Dahongliutan BIF: Implications for the Precambrian crustal evolution of the Western Kunlun orogenic belt, NW China

    Science.gov (United States)

    Hu, Jun; Wang, He; Wang, Min

    2017-10-01

    The Late Neoproterozoic Dahongliutan BIF is associated with siliciclastic rocks in the Tianshuihai terrane of the Western Kunlun orogenic belt (WKO), NW China. The sedimentary rocks have various weathering indices (e.g., CIA = 57-87, PIA = 61-96 and Th/U = 4.85-12.45), indicative of varying degrees of weathering in the source area. The rocks have trace element ratios, such as Th/Sc = 0.60-1.21 and Co/Th = 0.29-1.67, and light rare earth element (LREE) enriched chondrite-normalized REE patterns, suggesting that they were mainly sourced from intermediate and felsic rocks. Available U-Pb ages of detrital zircon from these rocks reveal that the detrital sources may have been igneous and metamorphic rocks from the WKO and the Tarim Block. Our study suggests that the Dahongliutan BIF and hosting siliciclastic rocks may have deposited in a setting transitional from a passive to active continental margin, probably related to the Late Neoproterozoic-Early Cambrian seafloor spreading and subduction of the Proto-Tethys Ocean. U-Pb dating of 163 detrital zircons defines five major age populations at 2561-2329 Ma, 2076-1644 Ma, 1164-899 Ma, 869-722 Ma and 696-593 Ma. These age groups broadly correspond to the major stages of supercontinent assembly and breakup events widely accepted for Columbia, Rodinia and Gondwana. Some zircons have TDM2 model ages of 3.9-1.8 Ga and negative εHf(t) values, suggesting that the Archean to Paleoproterozoic (as old as Eoarchean) crustal materials were episodically reworked and incorporated into the late magmatic process in the WKO. Some Neoproterozoic zircons have TDM2 model ages of 1.47-1.07 Ga and 1.81-1.53 Ga and positive εHf(t) values, indicating juvenile crustal growth during the Mesoproterozoic. Our new results, combined with published data, imply that both the Tianshuihai terrane in the WKO and the Tarim Block share the same Precambrian tectonic evolution history.

  15. Sulfur and strontium isotopic compositions of carbonate and evaporite rocks from the late Neoproterozoic–early Cambrian Bilara Group (Nagaur-Ganganagar Basin, India): Constraints on intrabasinal correlation and global sulfur cycle

    Digital Repository Service at National Institute of Oceanography (India)

    Mazumdar, A.; Strauss, H.

    Sulfur and strontium isotope ratios are presented for carbonate and evaporite rocks from the late Neoproterozoic and early Cambrian Bilara and Hanseran Evaporite Groups, NW India. The sulfur isotopic compositions of trace sulfate in carbonate rocks...

  16. Neoproterozoic Rosetta Gabbro from northernmost Arabian-Nubian Shield, south Jordan: Geochemistry and petrogenesis

    Science.gov (United States)

    Jarrar, Ghaleb H.; Stern, Robert J.; Theye, Thomas; Yaseen, Najel; Pease, Victoria; Miller, Nathan; Ibrahim, Khalil M.; Passchier, Cees W.; Whitehouse, Martin

    2017-07-01

    An Ediacaran mafic intrusion of south Jordan is a distinctive appinitic igneous rock with a possibly unique texture, characterized by spherical clots up to 40 mm in diameter composed of amphibole cores from which plagioclase euhedra radiate; we call it the Rosetta Gabbro. It is exposed as a small (ca. 750 m2) outcrop in the Neoproterozoic basement of south Jordan. A second outcrop of otherwise similar gabbro is located about 400 m to the north of the Rosetta Gabbro, but it lacks the distinctive texture. The Rosetta Gabbro could represent a magma pipe. It intrudes the Aqaba Complex ( 600 Ma) granitoids and metasediments of the Janub Metamorphic Complex (633-617 Ma). The gabbro is an Ol- to QZ tholeiite with the following chemical characteristics: SiO2 = 46.2-47.8 wt.%; Al2O3 = 16.4-17.7 wt.%, TiO2 = 1.70-2.82 wt.%, Na2O = 1.27-2.83 wt.%. K2O = 0.82-1.63 wt.%; Mg# 58-63; Σ REE = 70-117 ppm; La/Yb 6 to 8; and Eu/Eu* = 1.05-1.2. The investigated gabbro has the geochemical features of a continental flood tholeiitic basalt emplaced in a within-plate tectonic setting. Two varieties of amphiboles are found: 1) large, 3-5 mm, brown ferri-titanian-tschermakite (K0.09Na0.28)(Na0.20Ca1.80)(Mn0.04Fe3 +1.1Mg2.34Fe2 +0.90Ti0.29Al0.22)(Al1.85Si6.15)O22(OH)1.95 of the calcic amphibole group which is riddled with opaques; and 2) acicular yellowish-light green ferrian-magnesiohornblende (K0.04Na0.153)(Ca1.755Na0.245) (Fe3 +0.66Mn0.01Fe2 +1.01Mg3.03Ti0.06Al0.22)(Al1.03Si6.97)O22(OH)1.95. Scattered flakes of phlogopite also occur. Tabular radiating plagioclase (An64-79) are complexly twinned, with broad lamellae that show no zoning. Laser-ablation ICP-MS analyses of amphibole and plagioclase reveal considerable variation in trace element abundance, in spite of more subtle major element variations except for TiO2 in amphibole. The REE in the amphibole shows an order of magnitude variation with a concave-downward pattern and a positive Eu anomaly Eu/Eu* = 0.6-2, though far less

  17. Timing and sources of pre-collisional Neoproterozoic sedimentation along the SW margin of the Congo Craton (Kaoko Belt, NWNamibia)

    Czech Academy of Sciences Publication Activity Database

    Konopásek, J.; Košler, J.; Sláma, Jiří; Janoušek, V.

    2014-01-01

    Roč. 26, č. 1 (2014), s. 386-401 ISSN 1342-937X Institutional support: RVO:67985831 Keywords : detrital zircons * protolith ages * geochronology * Neoproterozoic Kaoko Belt * geochronology (Namibia) Subject RIV: DB - Geology ; Mineralogy Impact factor: 8.235, year: 2014

  18. New paleomagnetic poles from Arctic Siberia support Indian Ocean option for the Neoproterozoic APWP of the Siberian craton.

    Science.gov (United States)

    Pasenko, A.; Malyshev, S. V.

    2017-12-01

    Quantity and quality of paleomagnetic poles obtained so far for Neoproterozoic of Siberia are still insufficient even to outline the general trend of APWP of Siberia for this huge and very interesting time interval. Meanwhile, the solution of this problem is crucial for choice of polarity option for Siberian proterozoic paleomagnetic directions, for construction and testing of world paleotectonic and paleogeographic reconstructions. For example, whether or not the Siberian craton could be connected with Laurentia within the supercontinent Rodinia depends directly on paleomagnetic polarity option choice, which , in its turn, is determined by either we choose for neoproterozoic drift of Siberian paleomagnetic poles Pacific ocean trend [Smethurst et al., 1998] or Indian ocean [Pavlov et al., 2015] trend. To advance in solution of this problem we have carried out the paleomagnetic investigations of several sedimentary sections and sills of Arctic Siberia considered to be meso-neoproterozoic in age. In particular we have studied the terrigenous Udza and Unguohtah Formations and basic sills of the Udzha Uplift; the carbonate Khaipakh Formation of the Olenek Uplift; the carbonate Burovaya Formation of the Turukhansk Uplift; basic sills of the Kparaulakh Mountains.In this report we present the paleomagnetic poles obtained, discuss their bearing on construction of the adequate Siberian neoproterozoic APWP and show that our new data rather support the Indian ocean option.This research were supported by Grant from RF President #MK-739.2017.5

  19. The Neoproterozoic Drift History of Laurentia: a Critical Evaluation and new Palaeomagnetic Data from Northern and Eastern Greenland

    DEFF Research Database (Denmark)

    Christiansen, Jørgen Løye

    Laurentia occupies a critical position in palaeogeographic models for the Neoproterozoic, forming the core of Rodinia Supercontinent. The breakup of Rodinia in the late Neoproterozic was marked by the dispersal of its various constituent continental fragments, concomitant with major episodes of g......: one which argues that Laurentia has drifted into high latitudes by c. 630Ma and then back to equatorial latitudes, and the other which argues that Laurentia essentially remained in low latitudes throughout. The choice of one or other model depends on the choice, interpretation, and age...... of the available poles. We present new palaeomagnetic data from the Neoproterozoic sucessions of northern and eastern Greenland that confirm that Laurentia drifted into high latitudes during the late Neoproterozoic. Detailed investigation of the uppermost Eleonore Bay Supergroup (Sturtian?), yields a stable...... margin at a latitude of ~17° at this time. Collectively these data agree with models that have Laurentia moving into high latitudes in the latest Neoproterozoic. The required plate velocities, although high, are in the range for Phanerozoic continents. --------------------------------------------------------------------------------...

  20. Petrogenesis of the Jiaoziding granitoids and associated basaltic porphyries: Implications for extensive early Neoproterozoic arc magmatism in western Yangtze Block

    Science.gov (United States)

    Li, Jun-Yong; Wang, Xiao-Lei; Gu, Zhi-Dong

    2018-01-01

    Middle Neoproterozoic (ca 860-750 Ma) granitoids are widely distributed in the western margin of the Yangtze Block, China, yet their magma sources and tectonic settings are unclear. The geochronology and geochemistry of the granitoids and associated basaltic porphyries, which intruded the 970 Ma Tongmuliang arc volcanic rocks in the Jiaoziding area (east of Pingwu county), were investigated in this study. LA-ICP-MS zircon U-Pb dating indicates that the Jiaoziding granitoids and basaltic porphyries were formed at 795 ± 6 Ma and 790 ± 20 Ma, respectively. The granitoids have high SiO2 (69.2-76.9 wt%), K2O (2.3-5.6 wt%), and Na2O (3.2-5.1 wt%) contents, and a low Al2O3 (12.4-14.5 wt%) content. The basaltic porphyries contain high concentrations of TiO2 ( 3 wt%) and high field strength elements, have steep rare earth element patterns, and are depleted in Nd and Hf isotopes. Batch partial-melting modelling indicates that the Jiaoziding granitoids could have been derived by 5% and 50-70% partial melting of Tongmuliang mafic rocks and quartz-keratophyres, respectively. Formation of the basaltic porphyries by melting of upwelling asthenospheric mantle would have been facilitated by extensive lithospheric delamination during the Neoproterozoic. This study established a link between mid-Neoproterozoic granitic magmatism and 970 Ma juvenile arc crust, indicating that extensive early Neoproterozoic juvenile arc crust, and partial melting of this crust in an extensional setting, favoured the formation of middle Neoproterozoic granitic rocks along the W-NW margin of the Yangtze Block.

  1. Genesis and petrology of Late Neoproterozoic pegmatites and aplites associated with the Taba metamorphic complex in southern Sinai, Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Abdelfadil, K.M.; Asimow, P.D.; Azer, M.K.; Gahlan, H.A.

    2016-07-01

    We present new field, petrographical, mineralogical and geochemical data from late Neoproterozoic pegmatites and aplites in southern Sinai, Egypt, at the northernmost limit of the Arabian-Nubian Shield. The pegmatites cross-cut host rocks in the Taba Metamorphic Complex (TMC) with sharp contacts and are divided into massive and zoned pegmatites. Massive pegmatites are the most common and form veins, dykes and masses of variable dimensions; strikes range mainly from E-W through NW-SE to N-S. Mineralogically, the massive pegmatites are divided into K-feldspar-rich and albite-rich groups. Zoned pegmatites occur as lenses of variable dimensions, featuring a quartz core, an intermediate zone rich in K-feldspars and an outer finer-grained zone rich in albite. All compositions are highly evolved and display geochemical characteristics of post-collisional A-type granites: high SiO2, Na2O+K2O, FeO*/MgO, Ga/Al, Zr, Nb, Ga and Y alongside low CaO, MgO, Ba and Sr. They are rich in Rare Earth Elements (REE) and have extreme negative Eu anomalies (Eu/Eu*= 0.03–0.09). A genetic linkage between the pegmatites, aplites and alkali granite is confirmed by their common mild alkaline affinity and many other geochemical characteristics. These pegmatites and aplites represent the last small fraction of liquid remaining after extensive crystallization of granitic magma, injected along the foliation and into fractures of the host metamorphic rocks. The extensional tectonic regime and shallow depth of emplacement are consistent with a post-collisional environment. (Author)

  2. Giant submarine landslide grooves in the Neoproterozoic/Lower Cambrian Phe Formation, northwest Himalaya: Mechanisms of formation and palaeogeographic implications

    Science.gov (United States)

    Draganits, E.; Schlaf, J.; Grasemann, B.; Argles, T.

    2008-04-01

    Giant groove casts have been found in the upper Proterozoic to Lower Cambrian Phe Formation (Haimanta Group), a siliciclastic sandstone/shale succession in the Tethyan Zone of the Higher Himalaya tectonic unit. The grooves are among the largest linear erosion structures related to submarine mass-movements observed in the geologic record. They are up to 4 m wide, about 0.2 m deep and can be traced for more than 35 m without changing their character. The grooves are straight, subparallel to cross-cutting striations with shallow semi-circular cross-sections and well-defined superimposed minor ridges and grooves. Groove casts exist on the soles of several sandstone beds within a 73 m thick logged section, commonly associated with flute casts. Their characteristics were compared with several other types of ancient and modern submarine linear erosion structures. A sand-rich, non-channelized basin floor depositional environment is inferred from the lithofacies, the combination of sedimentary structures, the lack of coarse-grained pebbly facies, the lateral continuity of beds, and the lack of channel structures. The grooves probably formed by laminar debris flows/concentrated density flows dragging blocks of already lithified sediment across the basin floor. When the bedding is structurally rotated back to horizontal, the groove casts show consistent North-South oriented palaeocurrent trends, with South-directed palaeocurrent directions indicated by flute casts. These palaeocurrent orientations contrast with previous palaeogeographic reconstructions of this area, which propose sediment delivery from the South. We therefore suggest a new "double provenance" model for the spatial relationship of late Proterozoic to Early Cambrian strata of the Himalaya, in which Lesser and Tethyan Himalayan age-equivalent sediment was deposited in a connected basin, where the former received detritus from the South, and the latter from a hitherto unknown source in the North. One possible

  3. The Neoproterozoic Abu Dahr ophiolite, South Eastern Desert, Egypt: petrological characteristics and tectonomagmatic evolution

    Science.gov (United States)

    Gahlan, Hisham A.; Azer, Mokhles K.; Khalil, Ahmed E. S.

    2015-10-01

    The Neoproterozoic Abu Dahr ophiolite, South Eastern Desert, Egypt, is one of the best preserved and least dismembered ophiolite successions in the Arabian-Nubian Shield. It contains a Penrose-type ophiolite sequence from mantle section below mafic crust upward to oceanic sedimentary cover overlying mafic volcanics, although the original magmatic (stratigraphic) contact between the mantle and crustal sections is disrupted by tectonism. The Abu Dahr ophiolite is metamorphosed under greenschist facies conditions, and low-temperature alteration is widespread. Petrography reveals that: (i) the mantle is homogenous, serpentinized, and dominated by harzburgite and less abundant dunite; (ii) the cumulate ultramafics are represented by wehrlite and pyroxenite; and (iii) the crustal section is represented by metagabbros, meta-anorthosites and metabasalts. The Abu Dahr serpentinized peridotites show high Mg# (0.92-0.93), with enrichment of Ni, Cr and Co, and depletion of Al2O3 and CaO, and nearly flat and unfractionated REE chondrite-normalized pattern. Major and trace element characteristics of the Abu Dahr metagabbro and metabasalt (crustal section) indicate a tholeiitic to calc-alkaline affinity. Units of the crustal section have low-Nb and Zr concentrations, low Dy/Yb and relatively elevated La/Yb ratios, high U/Yb and Th/Yb ratios, and LREE enriched chondrite-normalized pattern. All of the Abu Dahr ophiolite units have trace-element signatures characterized by enrichment of LILE over HFSE. Rare and trace element patterns indicate a genetic link between the Abu Dahr mantle, cumulate ultramafics, and crust. Chromian spinel has survived metamorphism and is used as a petrogenetic indicator in the Abu Dahr serpentinized peridotites. The spinel is homogeneous with a limited composition, and shows high-Cr# (>0.6) combined with low-TiO2 character (mostly <0.1 wt.%). The Abu Dahr ophiolite is interpreted as a fragment of depleted oceanic lithosphere that experienced high degrees

  4. Orogen styles in the East African Orogen: A review of the Neoproterozoic to Cambrian tectonic evolution

    Science.gov (United States)

    Fritz, H.; Abdelsalam, M.; Ali, K. A.; Bingen, B.; Collins, A. S.; Fowler, A. R.; Ghebreab, W.; Hauzenberger, C. A.; Johnson, P. R.; Kusky, T. M.; Macey, P.; Muhongo, S.; Stern, R. J.; Viola, G.

    2013-10-01

    The East African Orogen, extending from southern Israel, Sinai and Jordan in the north to Mozambique and Madagascar in the south, is the world´s largest Neoproterozoic to Cambrian orogenic complex. It comprises a collage of individual oceanic domains and continental fragments between the Archean Sahara-Congo-Kalahari Cratons in the west and Neoproterozoic India in the east. Orogen consolidation was achieved during distinct phases of orogeny between ∼850 and 550 Ma. The northern part of the orogen, the Arabian-Nubian Shield, is predominantly juvenile Neoproterozoic crust that formed in and adjacent to the Mozambique Ocean. The ocean closed during a protracted period of island-arc and microcontinent accretion between ∼850 and 620 Ma. To the south of the Arabian Nubian Shield, the Eastern Granulite-Cabo Delgado Nappe Complex of southern Kenya, Tanzania and Mozambique was an extended crust that formed adjacent to theMozambique Ocean and experienced a ∼650-620 Ma granulite-facies metamorphism. Completion of the nappe assembly around 620 Ma is defined as the East African Orogeny and was related to closure of the Mozambique Ocean. Oceans persisted after 620 Ma between East Antarctica, India, southern parts of the Congo-Tanzania-Bangweulu Cratons and the Zimbabwe-Kalahari Craton. They closed during the ∼600-500 Ma Kuungan or Malagasy Orogeny, a tectonothermal event that affected large portions of southern Tanzania, Zambia, Malawi, Mozambique, Madagascar and Antarctica. The East African and Kuungan Orogenies were followed by phases of post-orogenic extension. Early ∼600-550 Ma extension is recorded in the Arabian-Nubian Shield and the Eastern Granulite-Cabo Delgado Nappe Complex. Later ∼550-480 Ma extension affected Mozambique and southern Madagascar. Both extension phases, although diachronous,are interpreted as the result of lithospheric delamination. Along the strike of the East African Orogen, different geodynamic settings resulted in the evolution of

  5. Micro-analysis by U-Pb method using LAM-ICPMS and its applications for the evolution of sedimentary basins: the example from Brasilia Belt; Micro-analise pelo metodo U-Pb usando LAM-CIPMS e suas aplicacoes para a evolucao de bacias sedimentares: o exemplo da faixa Brasilia

    Energy Technology Data Exchange (ETDEWEB)

    Pimentel, Marcio Martins; Matteini, Massimo; Junges, Sergio Luiz; Giustina, Maria Emilia Schutesky Della; Dantas, Elton Luiz; Buhn, Bernhard, E-mail: marcio@unb.br [Universidade de Brasilia (UnB), DF (Brazil). Instituto de Geociencias; Rodrigues, Joseneusa Brilhante [Servico Geologico do Brasil (CPRM), Brasilia, DF (Brazil)

    2015-07-01

    The U-Pb geochronological method using LAM-MC-ICPMS represents an important tool to investigate the geological evolution of sedimentary basins, as well as its geochronology, through the determination of upper limits for the depositional ages of detrital sedimentary rocks. The method has been applied in the Geochronology Laboratory of the Universidade de Brasilia, and in this study, a brief review of the provenance data for the sediments of the Neoproterozoic Brasilia Belt is presented and their significance for the evolution of the orogen is discussed. The results indicate that the Paranoa and Canastra Groups represent passive margin sequences formed along the western margin of the Sao Francisco-Congo continent. The Vazante Group presents similar provenance patterns, although Sm-Nd isotopic results suggest that its upper portions had contributions from younger (Neoproterozoic) sources, possibly from the Neoproterozoic Goias Magmatic Arc. On the other hand, metasediments of the Araxa and Ibia groups contain an important proportion of material derived from Neoproterozoic sources, demonstrating that they represent syn-orogenic basins. The provenance pattern of the Bambui Group is marked by an important Neoproterozoic component, showing that it constitutes a sedimentary sequence which is younger than 600 Ma, representing a foreland basin to the Brasilia Belt. (author)

  6. An age-marker acanthomorph from the Bhander group, upper ...

    Indian Academy of Sciences (India)

    Mcllroy D, Crimes T P and Pauley C J 2005 Fossils and mat grounds from the Neoproterozoic Longmyndian Super- group, Shropshire, U K; Geological Magazine 142(4). 441–455. Mendelson C V and Schopf J W 1992 Proterozoic and early. Cambrian acritarchs; In: The Proterozoic Biosphere,. (eds) J W Schopf and C Klein ...

  7. Mid amphibolite facies metamorphism of harzburgites in the Neoproterozoic Cerro Mantiqueiras Ophiolite, southernmost Brazil

    Directory of Open Access Journals (Sweden)

    HARTMANN LÉO A.

    2003-01-01

    Full Text Available Valuable information is retrieved from the integrated investigation of the field relationships, microstructure and mineral compositions of harzburgites from the Neoproterozoic Cerro Mantiqueiras Ophiolite. This important tectonic marker of the geological evolution of southernmost Brazilian Shield was thoroughly serpentinized during progressive metamorphism, because the oldest mineral assemblage is: olivine + orthopyroxene + tremolite + chlorite + chromite. This M1 was stabilized in mid amphibolite facies - 550-600ºC as calculated from mineral equilibria. No microstructural (e.g. ductile deformation of olivine or chromite or compositional (e.g. mantle spinel remnant of mantle history was identified. A metamorphic event M2 occurred in the low amphibolite facies along 100 m-wide shear zones, followed by intense serpentinization (M3 and narrow 1-3 m-wide shear zones (M4 containing asbestos.

  8. Understanding and modelling Neo-proterozoic glaciations and their associated phenomena

    International Nuclear Information System (INIS)

    Le Hir, Guillaume

    2007-01-01

    The objective of this research thesis is to provide a consistent image of extreme glaciations which occurred during the Neo-proterozoic era. By using climate and carbon cycle models (or model of bio-geochemical cycles), the author aims at answering various scientific questions raised by the Snowball Earth hypothesis. After a description of the main geological features which characterize the Proterozoic, scientific problems are presented. The author then reports the study of carbon cycle during glaciation in order to understand its operation. Based on this constraint, a consistent scenario of exit from glaciation is defined. The physical-chemical evolution of the ocean during and after a global glaciation is then quantified in order to assess its potential effects on the environment and on the Precambrian biosphere. The last part focuses on the post-glacial evolution to establish the delay for a return to equilibrium of climate after such an extreme event [fr

  9. The neoproterozoic Goias magmatic arc, central Brazil: a review and new Sm-Nd isotopic data

    Energy Technology Data Exchange (ETDEWEB)

    Pimentel, Marcio Martins; Fuck, Reinhardt Adolfo; Gioia, Simone Maria Costa Lima [Brasilia Univ., DF (Brazil). Inst. de Geociencias]. E-mail: marcio@unb.br

    2000-03-01

    In this study we review the main characteristics and geochronological/isotopic data of metaigneous rocks of the juvenile Neoproterozoic Goias Magmatic Arc in central Brazil. Some new Sm-Nd isotopic data are also presented for both the southern (Arenopolis) and northern (Mara Rosa) sections of the arc. In the south, granitoids of the Choupana-Turvania area yielded a Sm-Nd whole-rock isochron age of 863{+-} 97 Ma and e{sub Nd} (T) of +4.1 T{sub D}M model ages vary between 0.94 and 1.13 Ga. Metavolcanic rocks in the Pontalina region have a Sm-Nd whole rock isochron age of 762 {+-} 77 Ma and e{sub Nd} (T) of +2.9. T {sub DM} values are between 0.96 and 1.10 Ga. In the northern section of the Goias Arc, mylonitic gneisses of the Serra Azul ridge, an important N30E shear zone, were investigated and have a Sm-Nd isochron age of 3058 {+-} 120 Ma and initial e{sub Nd} value of ca.+ 2.1. This data suggests that the Serra Azul ridge might represent either a mylonitized fragment of the Archaen terranes exposed just to the south, or the sialic basement of the Araguaia Belt supracrustal, along the eastern margin of the Amazon Craton. The geochronological data available so far indicate a long history of arc formation and amalgamation on the western margin of the Sao Francisco-Congo continent during the Neoproterozoic. The history of convergence of continental masses is partially coeval with the fragmentation of Rodinia, indicating that the western margin (present geographic reference) of that continent occupied a peripheral setting in the Rodinia super continent. (author)

  10. Biological feedbacks as cause and demise of the Neoproterozoic icehouse: astrobiological prospects for faster evolution and importance of cold conditions.

    Directory of Open Access Journals (Sweden)

    Pekka Janhunen

    Full Text Available Several severe glaciations occurred during the Neoproterozoic eon, and especially near its end in the Cryogenian period (630-850 Ma. While the glacial periods themselves were probably related to the continental positions being appropriate for glaciation, the general coldness of the Neoproterozoic and Cryogenian as a whole lacks specific explanation. The Cryogenian was immediately followed by the Ediacaran biota and Cambrian Metazoan, thus understanding the climate-biosphere interactions around the Cryogenian period is central to understanding the development of complex multicellular life in general. Here we present a feedback mechanism between growth of eukaryotic algal phytoplankton and climate which explains how the Earth system gradually entered the Cryogenian icehouse from the warm Mesoproterozoic greenhouse. The more abrupt termination of the Cryogenian is explained by the increase in gaseous carbon release caused by the more complex planktonic and benthic foodwebs and enhanced by a diversification of metazoan zooplankton and benthic animals. The increased ecosystem complexity caused a decrease in organic carbon burial rate, breaking the algal-climatic feedback loop of the earlier Neoproterozoic eon. Prior to the Neoproterozoic eon, eukaryotic evolution took place in a slow timescale regulated by interior cooling of the Earth and solar brightening. Evolution could have proceeded faster had these geophysical processes been faster. Thus, complex life could theoretically also be found around stars that are more massive than the Sun and have main sequence life shorter than 10 Ga. We also suggest that snow and glaciers are, in a statistical sense, important markers for conditions that may possibly promote the development of complex life on extrasolar planets.

  11. Scent of a supercontinent: Gondwana's ores as chemical tracers—tin, tungsten and the Neoproterozoic Laurentia-Gondwana connection

    Science.gov (United States)

    De Wit, Maarten J.; Thiart, Christien; Doucouré, Moctar; Wilsher, Wendy

    The birth of Gondwana is inextricably linked to the break-up of the earlier Neoproterozoic supercontinent Rodinia. In detail, the Neoproterozoic reconstructions of Rodinia are unsolved and without them a detailed kinematic history of the birth of Gondwana cannot be constructed. This paper shows that Gondwana's ore deposits provide chemical "scents" that can be effectively used to trace the tectonic history of Gondwana; and the heterogenous distribution of Gondwana's ore deposits are used to evaluate Late Neoproterozoic reconstructions, which place Laurentia against West Gondwana along a common belt of Grenville age rocks. West Gondwana (including its Grenville-like rocks) is anomalously enriched in Sn and W relative to the rest of Gondwana. The Grenville Province of Laurentia and its immediate hinterland are devoid of Sn-W deposits and even occurrences of any significance. Therefore, Rodinia reconstructions which juxtapose East Laurentia against the west coast of South America result in juxtaposition of distinctly different metalliferous crustal blocks. These reconstructions may not be correct, and other models should be (re-)explored.

  12. MESO-NEOPROTEROZOIC GRENVILLE-SVECONORWEGIAN INTRACONTINENTAL OROGEN: HISTORY, TECTONICS, GEODYNAMICS

    Directory of Open Access Journals (Sweden)

    M. V. Mints

    2017-01-01

    Full Text Available The objective of this paper is to represent the main features inherent to Grenville-Sveconorwegian Orogen (GSNO and to propose a model of tectonic and geodynamic evolution of this orogen based on the results of research concerning similar Precambrian tectonic units in the East European Craton. The studies of the conditions and settings related to origin and evolution of GSNO are of special interest, because it is located geographicaly and in a certain sense ideologically in the center of Rodinia, a supposed Neoproterozoic supercontinent. GSNO originated in the MezoNeoproterozoic in the inner region of the Lauroscandia continent. At present, the synformal tectonic structure of GSNO is divided into two portions: Grenville sector along the southeastern margin of the Canadian Shield, and Sveconorwegian sector in the southwestern Scandinavia. The integrity of Lauroscandia was twice disturbed in the MezoNeoproterozoic when oceanic structures resembling the Atlantic Ocean were formed. Later on, the continuity of the continent was restored with the involvement of oceanic lithosphere subduction and accretion and obduction of the island-arc and oceanic terranes. We distinguish two stages in the GSNO history: (1 ‘preparatory’ stage (from ~1.90 to ~1.16 Ga, and (2 formation of GSNO proper (from ~1.19 to ~0.90 Ga. The manifestations of granulite-facies metamorphism were repeatedly recorded before the Grenville Orogeny at 1.67–1.66, 1.47–1.45, 1.37–1.35, and 1.20–1.18 Ga. The Ottawan stage of the Grenville metamorphism proper is dated between 1.16 and 1.05–1.03 Ga. Metamorphism at the base of Allochthonous Belt corresponds to high-pressure granulite facies and, in a number of places, to hightemperature eclogite facies (800–900 °C at pressure in the range between 14 and 20 kbar. The age of metamorphism of rocks within Paraautochthonous Belt is 1.05–0.95 Ga; metamorphic grade increases from the greenschist facies near the Grenville front to

  13. Repeated granitoid intrusions during the Neoproterozoic along the western boundary of the Saharan metacraton, Eastern Hoggar, Tuareg shield, Algeria: An AMS and U-Pb zircon age study

    Science.gov (United States)

    Henry, B.; Liégeois, J. P.; Nouar, O.; Derder, M. E. M.; Bayou, B.; Bruguier, O.; Ouabadi, A.; Belhai, D.; Amenna, M.; Hemmi, A.; Ayache, M.

    2009-09-01

    The N-S oriented Raghane shear zone (8°30') delineates the western boundary of the Saharan metacraton and is, with the 4°50' shear zone, the most important shear zone in the Tuareg shield. It can be followed on 1000 km in the basement from southern Aïr, Niger to NE Hoggar, Algeria. Large subhorizontal movements have occurred during the Pan-African orogeny and several groups of granitoids intruded during the Neoproterozoic. We report U-Pb zircon datings (laser ICP-MS) showing that three magmatic suites of granitoids emplaced close to the Raghane shear zone at c. 790 Ma, c. 590 and c. 550 Ma. A comprehensive and detailed (158 sites, more than 1000 cores) magnetic fabric study was performed on 8 plutons belonging to the three magmatic suites and distributed on 200 km along the Raghane shear zone. The main minerals in all the target plutons do not show visible preferential magmatic orientation except in narrow shear zones. The AMS study shows that all plutons have a magnetic lineation and foliation compatible with the deformed zones that are zones deformed lately in post-solidus conditions. These structures are related to the nearby mega-shear zones, the Raghane shear zone for most of them. The old c. 793 Ma Touffok granite preserved locally its original structures. The magnetic structures of the c. 593 Ma Ohergehem pluton, intruded in the Aouzegueur terrane, are related to thrust structures generated by the Raghane shear zone while it is not the case of the contemporaneous plutons in the Assodé-Issalane terrane whose structures are only related to the subvertical shear zones. Finally, the c. 550 Ma granite group has magnetic structure related to the N-S oriented Raghane shear zone and its associated NNE-SSW structures when close to them, but NW-SE oriented when further. These NW-SE oriented structures appear to be characteristic of the late Neoproterozoic evolution of the Saharan metacraton and are in relation to the convergence with the Murzuq craton. This

  14. Low oxygen and argon in the Neoproterozoic atmosphere at 815 Ma

    Science.gov (United States)

    Yeung, Laurence Y.

    2017-12-01

    The evolution of Earth's atmosphere on >106-yr timescales is tied to that of the deep Earth. Volcanic degassing, weathering, and burial of volatile elements regulates their abundance at the surface, setting a boundary condition for the biogeochemical cycles that modulate Earth's atmosphere and climate. The atmosphere expresses this interaction through its composition; however, direct measurements of the ancient atmosphere's composition more than a million years ago are notoriously difficult to obtain. Gases trapped in ancient minerals represent a potential archive of the ancient atmosphere, but their fidelity has not been thoroughly evaluated. Both trapping and preservation artifacts may be relevant. Here, I use a multi-element approach to reanalyze recently collected fluid-inclusion data from halites purportedly containing snapshots of the ancient atmosphere as old as 815 Ma. I argue that those samples were affected by the concomitant trapping of air dissolved in brines and contaminations associated with modern air. These artifacts lead to an apparent excess in O2 and Ar. The samples may also contain signals of mass-dependent fractionation and biogeochemical cycling within the fluid inclusions. After consideration of these artifacts, this new analysis suggests that the Tonian atmosphere was likely low in O2, containing ≤10% present atmospheric levels (PAL), not ∼50% PAL as the data would suggest at face value. Low concentrations of O2 are consistent with other geochemical constraints for this time period and further imply that the majority of Neoproterozoic atmospheric oxygenation occurred after 815 Ma. In addition, the analysis reveals a surprisingly low Tonian Ar inventory-≤60% PAL-which, if accurate, challenges our understanding of the solid Earth's degassing history. When placed in context with other empirical estimates of paleo-atmospheric Ar, the data imply a period of relatively slow atmospheric Ar accumulation in the Paleo- and Meso

  15. Origin and paleoenvironmental interpretation of aluminum phosphate-sulfate minerals in a Neoproterozoic Baltic paleosol

    Science.gov (United States)

    Vircava, Ilze; Somelar, Peeter; Liivamägi, Sirle; Kirs, Juho; Kirsimäe, Kalle

    2015-04-01

    Aluminum phosphate-sulfate (APS) mineral solid-solutions occur as accessory phases in different sedimentary and hydrothermal deposits. Their composition is a sensitive environmental indicator recording changes in pH, temperature and chemical composition of the weathering, diagenetic or hydrothermal fluids. In this contribution we studied APS mineralization in a Neoproterozoic paleotropical paleosol developed on Paleo-Mesoproterozoic crystalline basement in the Baltic Basin. Small and disseminated APS minerals occur in high abundance (up to 4 wt.% of crystalline phases) in the weathering profile developed on gabbroic rocks rich in magmatic apatite. APS minerals belonging to a goyazite-florencite-svanbergite-woodhouseite solid-solution series occur in the uppermost part of the weathering profile and are replaced down-profile with secondary apatite. The change from APS minerals to secondary apatite precipitates reflects a paleo-pH gradient in the weathering profile from acidic (pH meters in the APS precipitation zone, to neutral or near neutral at 4-5 m-depth from the paleoweathered surface where secondary apatite occurs. Typically uniform < 5 μm-size APS crystallites suggest rapid precipitation in a highly supersaturated solution, but these crystals show a fine zonal structure whose nature and formation mechanism remain unclear.

  16. Gammaspectrometry identification covering Neoproterozoic supracrustal sequences in the Serido Belt , northeastern Brazil; Identificacao gamaespectrometrica de placeres rutilo-monaziticos neoproterozoicos no sul da Faixa Serido, nordeste do Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Sebastiao Milton P. da, E-mail: smpsilva@cchla.ufrn.br, E-mail: sebastiaomilton@gmail.com [Laboratorio de Geoprocessamento, Departamento de Geografia, Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Crosta, Alvaro P., E-mail: alvaro@ige.unicamp.br [Instituto de Geociencias, Universidade Estadual de Campinas (Unicamp), SP (Brazil); Ferreira, Francisco J.F., E-mail: francisco.ferreira@ufpr.br [Laboratorio de Pesquisas em Geofisica Aplicada- LPGA, Departamento de Geologia, Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil); Beurlen, Hartmut, E-mail: beurlen@terra.com.br [Programa de Pos-Graduacao em Geociencias, Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Silva, Adalene M., E-mail: adalene@unb.br [Laboratorio de Geofisica Aplicada, Instituto de Geociencias da Universidade de Brasilia (UnB), DF (Brazil); Silva, Marcelo R.R. da, E-mail: marcelor@ufpe.br [Departamento de Geologia, Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

    2010-01-15

    Aerial gamma-ray survey data covering Neoproterozoic supracrustal sequences in the Serido Belt were processed and analyzed together with ground gamma-ray data, air photos and geological data for lithogeophysical characterization and mapping of granitic rocks, related pegmatites fields and lithological units of Serido Group. Interpretation was based on individual and ternary images of the three radio-elements and the eU/eTh and eTh/K ratios, and allowed the discovery of thorium anomalies associated with coarse-grained metarenites and metaconglomerates facies intercalated with quartzites of the Equador Formation. High contents of iron oxides, ilmenite, monazite, rutile, titanite and zircon were identified by ore microscopy of polished sections in the metaconglomerate's matrix. Semiquantitative scanning electron microscopy (SEM) analyses in minerals of two samples revealed up to 79.4% of Th0{sub 2} and 87.7% of REE in monazites; up to 99.2% of Ti0{sub 2} in ilmenite and rutile and up to 1.81 % of HfO{sub 2} in zircon. Gamma-ray anomalies due to thorium were also identified in association with sediments of Cenozoic age in the region. (author)

  17. Ediacaran stromatolites and intertidal phosphorite of the Salitre Formation, Brazil: Phosphogenesis during the Neoproterozoic Oxygenation Event

    Science.gov (United States)

    Caird, R. A.; Pufahl, P. K.; Hiatt, E. E.; Abram, M. B.; Rocha, A. J. D.; Kyser, T. K.

    2017-04-01

    of hydrothermal veins range from - 4.7‰ to - 3.0‰ (mean = - 4.2‰) reflecting equilibration with temperatures > 80 °C. δ13C values are between - 7.0‰ and + 5.6‰ (mean = - 1.8‰,). Late lateritic weathering produced calcretes with δ18O values between - 3.3‰ and - 1.3‰, and δ13C values from - 9.2‰ to - 8.0‰ (mean values are - 1.8‰ and - 8.7‰, respectively). Petrographic analysis, generally low δ18O, and high δ13C values suggest hydrothermal dolomitization and remobilization of P led to secondary phosphate mineralization of intertidal stromatolite biostromes to produce economic phosphorite. Collectively, these results suggest that the benthic P-cycle in the Neoproterozoic was more complex than previously surmised and emphasize the multifaceted significance of microbial, paleoenvironmental, and diagenetic processes that allowed phosphorite to accumulate on the São Franciscan craton. Such information further elucidates attributes of the onset of Earth's second major phosphogenic episode, which is roughly coincident with the Neoproterozoic Oxygenation Event (NOE) and the evolution of multicellular animals.

  18. Late Neoproterozoic Nuqara Dokhan Volcanics, Central Eastern Desert, Egypt: Geochemistery and petrogenesis

    Science.gov (United States)

    Hassan, Tharwat; Asran, Asran; Amron, Taha; Natflos, Theo

    2014-05-01

    The Nuqara volcanic is one of the northernmost outcrops of the Arabian-Nubian Shield Dokhan volcanics. The origin and tectonic setting of the late Neoproterozoic Dokhan volcanics (ca. 610-560 Ma) in the Egyptian Eastern Desert is highly debated. The debate concerns the tectonic setting where they formed during transition between convergent to extensional regime or after the East- and the West-Gondwana collision (~600Ma). In order to solve this problem, lavas from Nuqara area were studied geologically and geochemically. Nuqara Dokhan volcanics comprises two main rock suites: (a) an intermediate volcanic suite, consisting of basaltic andesite, andesite and their associated pyroclastics rocks; and (b) a felsic volcanic suite composed of dacite, rhyolite and ignimbrites. The two suites display well-defined major and trace element trends and continuum in composition with wide ranges in SiO2 (52-75.73%), CaO (9.19-0.22%), MgO (5.29-0.05%), Sr (1367-7.4 ppm), Zr (688.5-172.7 ppm), Cr (207-0.4 ppm), and Ni (94.3-0.2 ppm). The Nuqara Dokhan volcanics are characterized by strong enrichment in LILE relative to HFSE and affiliated to the calc-alkaline subducted - related magmatism. Geochemical Modeling displays that the evolution of these rocks was governed by fractional crystallization of plagioclase, amphiboles, pyroxene, magnetite and apatite in the intermediate varieties and plagioclase, amphibole, magnetite, apatite and zircon in the felsic varieties. The obtained mineral chemistry of these volcanics reveals: (a) Plagioclase range in composition from An55 to An40 in basaltic andesite and from An39 to An24 in andesite. (b) Alkali feldspars have sanidine composition. (c) Clinopyroxenes have augite composition. The low Al2O3 contents (1.94-5.588 wt %) indicate that clinopyroxene crystallized at low - pressure conditions. (d) Amphiboles have magnesio- hornblende composition.

  19. Triple oxygen isotope evidence for elevated CO2 levels after a Neoproterozoic glaciation.

    Science.gov (United States)

    Bao, Huiming; Lyons, J R; Zhou, Chuanming

    2008-05-22

    Understanding the composition of the atmosphere over geological time is critical to understanding the history of the Earth system, as the atmosphere is closely linked to the lithosphere, hydrosphere and biosphere. Although much of the history of the lithosphere and hydrosphere is contained in rock and mineral records, corresponding information about the atmosphere is scarce and elusive owing to the lack of direct records. Geologists have used sedimentary minerals, fossils and geochemical models to place constraints on the concentrations of carbon dioxide, oxygen or methane in the past. Here we show that the triple oxygen isotope composition of sulphate from ancient evaporites and barites shows variable negative oxygen-17 isotope anomalies over the past 750 million years. We propose that these anomalies track those of atmospheric oxygen and in turn reflect the partial pressure of carbon dioxide (P(CO2)) in the past through a photochemical reaction network linking stratospheric ozone to carbon dioxide and to oxygen. Our results suggest that P(CO2) was much higher in the early Cambrian than in younger eras, agreeing with previous modelling results. We also find that the (17)O isotope anomalies of barites from Marinoan (approximately 635 million years ago) cap carbonates display a distinct negative spike (around -0.70 per thousand), suggesting that by the time barite was precipitating in the immediate aftermath of a Neoproterozoic global glaciation, the P(CO2) was at its highest level in the past 750 million years. Our finding is consistent with the 'snowball Earth' hypothesis and/or a massive methane release after the Marinoan glaciation.

  20. Tibet- Himalayan Analogs of Pan-African Shear Zones : Implications for Neoproterozoic Tectonics

    Science.gov (United States)

    Attoh, K.; Brown, L. D.

    2009-12-01

    Large-scale shear zones are distinct features of Tibet-Himalayan orogen and the Pan-African Trans-Saharan belt. Prominent examples in the Pan-African-belt extend for ~2500 km from the Sahara to the Gulf of Guinea and are characterized by right-slip movements. The NS shear zones, such as 4°50’-Kandi shear zone (KSZ) are complemented by NE-SW shear zones that preserve a record of sinistral movements and are represented by the Central Cameroon shear zone (CCSZ) in the eastern part of the Pan-African domain. The West African shear zones project into similar structures in the Borborema Province of northeast Brazil. In addition, the Pan-African belt preserves structures and rock assemblages that indicate subduction-collision tectonics We propose that structures of Tibet-Himalayan collisional orogen are instructive analogs of the Pan-African structures where: (i) the Pan-African front corresponds to the Main Himalayan thrust and it’s splays; (ii) the main Pan-African suture zone is analogous to the Indus-Tsangpo suture in the Tibet-Himalayan belt; (iii) the 4°50’-KSZ corresponds to Karakoram and it’s linkages with Jiali fault system and (iv) left-slip CCSZ and related shear zones are analogs of Altyn Tagh and Kumlun faults and their splays. This suggests the operation of escape-type tectonics in the Neoproterozoic belt of West-Africa and predicts the nature of the deep structures in the Cenozoic Tibet-Himalayan orogen.

  1. Age and geochemistry of Neoproterozoic granitoids in the Songnen-Zhangguangcai Range Massif, NE China: Petrogenesis and tectonic implications

    Science.gov (United States)

    Luan, Jin-Peng; Xu, Wen-Liang; Wang, Feng; Wang, Zhi-Wei; Guo, Peng

    2017-10-01

    This study presents new zircon U-Pb ages and geochemical data for Neoproterozoic granitoids in the Songnen-Zhangguangcai Range Massif (SZRM) of NE China. This dataset provides insights into the Neoproterozoic tectonic setting of the SZRM and the links between this magmatism and the evolution of the Rodinia supercontinent. The zircon U-Pb dating indicates that the Neoproterozoic magmatism within the SZRM can be subdivided into two stages: (1) a ∼917-911 Ma suite of syenogranites and monzogranites, and (2) an ∼841 Ma suite of granodiorites. The 917-911 Ma granitoids contain high concentrations of SiO2 (67.89-71.18 wt.%), K2O (4.24-6.91 wt.%), and Al2O3 (14.89-16.14 wt.%), and low concentrations of TFe2O3 (1.63-3.70 wt.%) and MgO (0.53-0.88 wt.%). They are enriched in the light rare earth elements (LREE) and the large ion lithophile elements (LILE), are depleted in the heavy REE (HREE) and the high field strength elements (HFSE; e.g., Nb, Ta, and Ti), and have slightly positive Eu anomalies, indicating that they are geochemically similar to high-K adakitic rocks. They have zircon εHf (t) values and TDM2 ages from -4.4 to +1.5 and 1915 Ma to 1592 Ma, respectively, suggesting that they were derived from a primary magma generated by the partial melting of ancient thickened lower crustal material. In comparison, the 841 Ma granodiorites contain relatively low concentrations of Al2O3 (14.50-14.58 wt.%) and K2O (3.27-3.29 wt.%), relatively high concentrations of TFe2O3 (3.78-3.81 wt.%) and the HREE, have negative Eu anomalies, and have zircon εHf (t) values and TDM2 ages from -4.7 to +1.0 and 1875 to 1559 Ma, respectively. These granodiorites formed from a primary magma generated by the partial melting of ancient crustal material. The ∼917-911 Ma magmatism within the SZRM is inferred to have formed in an orogenic setting, whereas the ∼841 Ma magmatism formed in an anorogenic setting related to either a post-orogenic tectonic event or the onset of Neoproterozoic

  2. A connection between the Neoproterozoic Dom Feliciano (Brazil/Uruguay) and Gariep (Namibia/South Africa) orogenic belts – evidence from a reconnaissance provenance study •

    International Nuclear Information System (INIS)

    Basei, M.; Frimmel, H.; Nutman, A.; Preciozzi, F.; Jacob, J.

    2005-01-01

    A provenance study of Neoproterozoic siliciclastic successions in the stratigraphically and tectonically lowermost and uppermost parts of the Pan-African Gariep Belt (Stinkfontein Subgroup and Oranjemund Group, respectively) in southwestern Africa, as well as in the Rocha Group of the Punta del Este Terrane (Dom Feliciano Belt) in Uruguay, revealed that the Oranjemund and Rocha Groups can be correlated and most likely formed in the same basin. Thus the Rocha Group is considered to represent the fill of the westernmost part of a re-activated Vendian Gariep Basin. The lower parts of the Oranjemund and Rocha Groups reflect erosion of mafic rocks, whereas the upper parts are derived from a predominantly felsic source area. Oceanic islands of within-plate geochemistry in the immediate vicinity were the most likely source of the mafic input into the lower part of the Oranjemund Group, with most of the other sediments derived from a passive continental margin, i.e. the western margin of the Kalahari Craton. Age spectra obtained by U-Pb SHRIMP analyses of detrital zircon grains from the Stinkfontein Subgroup (Port Nolloth Group), the Oranjemund Group and the Rocha Group are very similar, except for a lack of the youngest age group around 600 Ma in the Stinkfontein Subgroup. In all three units, zircon grains of 1000 – 1200 Ma dominate, with a further peak in the age distribution between 1700 and 2000 Ma. These ages compare well with the pre-Gariep basement geology in southwestern Africa, where the former age range corresponds to magmatic and high-grade metamorphic activity in the Mesoproterozoic Namaqua-Natal Belt and the latter to an extensive Palaeoproterozoic Andean-type volcanic arc (Richtersveld Terrane). Comparable ages are conspicuously absent in the basement of the Rio de la Plata Craton in South America. Derivation of the Rocha Group sediments from a similar source as the contemporaneous Oranjemund Group sediments is therefore suggested. The most likely source of

  3. Signatures of Late Neoproterozoic Gondwana assembly and Maronian glaciation in Lesser Himalaya: a palaeogeographical and stratigraphical approach

    Science.gov (United States)

    Umar, Muhammad; Betts, Peter; Saud Khan, Malik Muhammad; Amjad Sabir, Muhammad; Farooq, Muhammad; Zeb, Asif; Khan Jadoon, Umair; Ali, Shoaib

    2015-03-01

    Stratigraphical and sedimentological analyses of Late Neoproterozoic successions in Lesser Himalaya are combined herein with palaeogeographical considerations and comparisons with equivalent successions in India and South China. The succession starts with the Hazara Formation, which contains complete and incomplete Bouma sequences suggesting its deposition in deep marine turbidite settings. The overlying Tanawal Formation, rich in massive sandstone, shale and siltstone, was deposited in shallow marine conditions, as indicated by the presence of parallel lamination, large scale tabular, trough cross- and hummocky cross-stratifications. The Tanawal Formation facies shift laterally from proximal (south-southeast) to distal (north-northwest). The glaciogenic Tanaki Boulder Bed, overlying the Tanawal Formation, was deposited during the Maronian glaciation. It is equivalent to the Blaini Formation of India, and to the Sinian diamictites of South China. The Abbottabad Formation of Cambrian age overlies the Tanaki Boulder Bed, and is composed of dolomite, chert nodules and phosphate-rich packages; similar successions are documented in India and South China at the same stratigraphical interval. The similarities of the Neoproterozoic successions of Lesser Himalaya (both in Pakistan and India) and South China suggests their possible proximity during the break-up of Rodinia and the assembly of the Gondwana Supercontinent.

  4. Sedimentary environment and tectonic deformations of the Neoproterozoic Iron formation at the Wadi El-Dabbah greenstone sequence, Central Eastern Desert, Egypt

    Science.gov (United States)

    Kiyokawa, S.; Suzuki, T.; Ikehara, M.; Horie, K.; Takehara, M.; Abd-Elmonem, H.; Dawoud, A. D. M.; El-Hasan, M. M.

    2017-12-01

    El-Dabbah area Central Eastern Desert of the Nubia Shield preserved Neoproterozoic lower green schist faces volcaniclastics greenstone sequence and covered strike-slip deformation related subaerial sedimentary sequence (Hammamat Group). The volcaniclastics greenstone sequence (El-Dabbah Formation) preserved several iron beds bearing well stratified sequence. Four tectonic deformation identified as this area; thrust deformation (D1), strike-slip deformation with transtension normal fault and strong left-lateral shear (D2), subaerial pull apart sediments basin formed strike-slip deformations (D3), and extensional deformation after the Hammamat Group sedimentation (D4). New age data from intrusions identified about 638 Ma white granite and about 660 Ma quartz porphyry. Based on the detail mapping, we reconstruct more than 5000m thick volcano sedimentary succession. At least, 10 iron rich sections were identified within 3500m thick volcano-sedimentary sequence. There are 14 iron formation sequence identified in this greenstone sequence. Each Iron sequences are bedded with greenish-black shales within massive volcaniclastics and lava flow. Iron formation is formed mostly fine grain magnetite deposited within volcanic mudstone and siltstone with gradual distribution. Timing of this iron sediment is identified within Sturtian glaciation (730-700Ma). However, there is no geological direct support evidence in the Snowball earth event at this greenstone sequence. The volcanic activities at this ocean already produced many Fe2+ to ocean water. Repeated iron precipitation occur during volcanic activity interphase period which produced oxidation of iron and produce oxyhydroxide with mud-silt sediment at bottom of ocean.

  5. Geochemistry, geochronology, and Sr-Nd isotopes of the Late Neoproterozoic Wadi Kid volcano-sedimentary rocks, Southern Sinai, Egypt: Implications for tectonic setting and crustal evolution

    Science.gov (United States)

    Moghazi, Abdel-Kader M.; Ali, Kamal A.; Wilde, Simon A.; Zhou, Qin; Andersen, Tom; Andresen, Arild; Abu El-Enen, Mahrous M.; Stern, Robert J.

    2012-12-01

    The Kid Group is one of the few exposures of Neoproterozoic metavolcano-sedimentary rocks in the basement of southern Sinai in the northernmost Arabian-Nubian Shield. It is divided into the mostly metamorphosed volcaniclastic Melhaq and siliciclastic Um Zariq formations in the north and the mostly volcanic Heib and Tarr formations in the south. The Heib, Tarr, and Melhaq formations reflect an intense episode of igneous activity and immature clastic deposition associated with core-complex formation during Ediacaran time, but Um Zariq metasediments are relicts of an older (Cryogenian) sedimentary sequence. The latter yielded detrital zircons with concordant ages as young as 647 ± 12 Ma, which may indicate that the protolith of Um Zariq schist was deposited after ~ 647 Ma but 19 concordant zircons gave a 206Pb/238U weighted mean age of 813 ± 6 Ma, which may represent the maximum depositional age of this unit. In contrast, a cluster of 11 concordant detrital zircons from the Melhaq Formation yield a weighted mean 206Pb/238U age of 615 ± 6 Ma. Zircons from Heib Formation rhyolite clast define a 206Pb/238U weighted mean age of 609 ± 5 Ma, which is taken to approximate the age of Heib and Tarr formation volcanism. Intrusive syenogranite sample from Wadi Kid yields a 206Pb/238U weighted mean age of 604 ± 5 Ma. These constraints indicate that shallow-dipping mylonites formed between 615 ± 6 Ma and 604 ± 5 Ma. Geochemical data for volcanic samples from the Melhaq and Heib formations and the granites show continuous major and trace element variations corresponding to those expected from fractional crystallization. The rocks are enriched in large ion lithophile and light rare earth elements, with negative Nb anomalies. These reflect magmas generated by melting of subduction-modified lithospheric mantle, an inference that is further supported by ɛNd(t) = + 2.1 to + 5.5. This mantle source obtained its trace element characteristics by interaction with fluids and melts

  6. High-pressure thermal aureoles around two Neoproterozoic synorogenic magmatic epidote-bearing granitoids, Northeastern Brazil

    Science.gov (United States)

    Caby, Renaud; Sial, Alcides N.; Ferreira, Valderez P.

    2009-02-01

    Unusual high-pressure inner thermal aureoles are described from the Minador and Angico Torto epidote-bearing tonalitic plutons that emplaced into greenschist-facies metasedimentary rocks of the Neoproterozoic Cachoeirinha-Salgueiro belt, northeastern Brazil. The foliated pelitic hornfelses display the mineral assemblage garnet, kyanite, staurolite, muscovite, biotite, plagioclase ± quartz. Rare fibrolite is only found very close to the contacts. Hornfelses display steep mineral lineations and steeply-dipping foliations concordant with magmatic contacts. Leucocratic veinlets containing quartz, oligoclase, garnet, kyanite, staurolite, rutile and ilmenite suggest that limited melting conditions were reached very close to magmatic contacts ( T ⩾ 650 °C, P around 8 kbar). These high-pressure hornfelses form a few meters thick, rigid envelopes around the two plutons. Contrary to known examples of kyanite-bearing hornfelses that recorded high-temperature decompression, the nearly isobaric cooling down to ca. 450 °C is constrained by 3.20-3.30 Si contents of retrogressive phengites from both inner hornfelses and ductilely-deformed tonalite at the pluton margins. Isograds and bathograds are, therefore, apparently telescoped due to HP/LT shearing, possibly caused by subsequent differential vertical movements affecting these two solidified plutons. The unusual depth of emplacement of these syn-kinematic calc-alkaline plutons is explained by a tentative geodynamic model involving a pre-620 Ma-subduction setting. Resumen Las aureolas internas que rodean dos plutones tonalíticos emplazados dentro de rocas cajas en facies esquistos verdes del Cinturón-plegado Cachoeirinha-Salgueiro al noreste de Brasil, contienen hornfelses pelíticos foliados con granate, kyanita, estaurolita, muscovita, biotita, plagioclasa ± cuarzo. Fibrolita es rara ó es encontrada solamente cerca de las zonas de contacto. Los hornfelses desarrollaron foliaciones concordantes con buzamiento fuerte

  7. Paleoenvironments, δ13C and δ18O signatures in the Neoproterozoic carbonates of the Comba Basin, Republic of Congo: Implications for regional correlations and Marinoan event

    Science.gov (United States)

    Préat, Alain; Delpomdor, Franck; Ackouala Mfere, Anna Perla; Callec, Yannick

    2018-01-01

    The Ediacaran Schisto-Calcaire Group is a ∼1300 m-thick succession belonging to the West Congo Supergroup in Central Africa. In the Comba Basin, it consists of three carbonate-dominated units defined as formations (SCI to SCIII) that are unconformably overlain by clastic deposits (Mpioka Group) interpreted as a molassic formation associated with the Panafrican Orogen. The underlying Upper Tillite and Cap Carbonate (SCIa) units, considered as markers of the Snowball Earth event were studied in three sections. We investigated the carbonates of the Schisto-Calcaire Group by defining new microfacies (MF1-MF7) and we performed C and O isotopic analyses in order to constraint the depositional and diagenetic events directly after the Marinoan interval. Stratigraphic variations of the stable isotopes are important in the series with lighter δ18O values (>1.5‰) than those of the Neoproterozoic ocean in the SCIc unit. According to regional stratigraphy a temperature effect can be dismissed and a freshwater surface layer is the origin of such negative δ18O values in this unit. The negative δ13C anomaly (-3.5‰ on average) of the Cap Carbonate is similarly to the δ18O values (-6.4‰ on average) in the range of the marine domain during postglacial sea level rise. The sample suite as a whole (SCII and SCIII formations) displays heavier δ18O and δ13C than those of the lower part (SCI unit) of the Schisto-Calcaire Group. The comparison with the Lower Congo (Democratic Republic of Congo) and Nyanga (Gabon) basins shows that the meteoric flushing in SCIc unit of the Schisto-Calcaire Group was regional and not local, and could be derived from a climatic evolution. Although an overall overprint is present, our isotopic relationships argue against overall diagenetic resetting of primary compositions and suggest that with careful examination combined with detailed petrographic analysis general depositional and diagenetic controls can be discerned in oxygen and carbon

  8. Neoproterozoic rift basins and their control on the development of hydrocarbon source rocks in the Tarim Basin, NW China

    Science.gov (United States)

    Zhu, Guang-You; Ren, Rong; Chen, Fei-Ran; Li, Ting-Ting; Chen, Yong-Quan

    2017-12-01

    The Proterozoic is demonstrated to be an important period for global petroleum systems. Few exploration breakthroughs, however, have been obtained on the system in the Tarim Basin, NW China. Outcrop, drilling, and seismic data are integrated in this paper to focus on the Neoproterozoic rift basins and related hydrocarbon source rocks in the Tarim Basin. The basin consists of Cryogenian to Ediacaran rifts showing a distribution of N-S differentiation. Compared to the Cryogenian basins, those of the Ediacaran are characterized by deposits in small thickness and wide distribution. Thus, the rifts have a typical dual structure, namely the Cryogenian rifting and Ediacaran depression phases that reveal distinct structural and sedimentary characteristics. The Cryogenian rifting basins are dominated by a series of grabens or half grabens, which have a wedge-shaped rapid filling structure. The basins evolved into Ediacaran depression when the rifting and magmatic activities diminished, and extensive overlapping sedimentation occurred. The distributions of the source rocks are controlled by the Neoproterozoic rifts as follows. The present outcrops lie mostly at the margins of the Cryogenian rifting basins where the rapid deposition dominates and the argillaceous rocks have low total organic carbon (TOC) contents; however, the source rocks with high TOC contents should develop in the center of the basins. The Ediacaran source rocks formed in deep water environment of the stable depressions evolving from the previous rifting basins, and are thus more widespread in the Tarim Basin. The confirmation of the Cryogenian to Ediacaran source rocks would open up a new field for the deep hydrocarbon exploration in the Tarim Basin.

  9. Detrital zircon geochronology of some neoproterozoic to triassic rocks in interior alaska

    Science.gov (United States)

    Bradley, D.C.; McClelland, W.C.; Wooden, J.L.; Till, A.B.; Roeske, S.M.; Miller, M.L.; Karl, S.M.; Abbott, J.G.

    2007-01-01

    We report 777 U-Pb SHRIMP detrital zircon ages from thirteen sandstones and metasandstones in interior Alaska. About sixty grains per sample were analyzed; typically, half to three-fourths of these were concordant within ?? 10%. Farewell terrane. Two quartzites were collected from Ruby quadrangle and a third from Taylor Mountains quadrangle. All three are interpreted to represent a low stratigraphic level in the Nixon Fork platform succession; the samples from Ruby quadrangle are probably late Neoproterozoic, and the sample from Taylor Mountains quadrangle is probably Cambrian in age. The youngest detrital zircon in any of the three is 851 Ma. The two Ruby quadrangle samples area almost identical: one has a major age cluster at 1980-2087 and minor age clusters at 944-974 and 1366-1383 Ma; the other has a major age cluster at 1993-2095 Ma and minor age clusters at 912-946 and 1366-1395 Ma. The Taylor Mountains sample shows one dominant peak at 1914-2057 Ma. Notably absent are zircons in the range 1800-1900 Ma, which are typical of North American sources. The detrital zircon populations are consistent with paleontological evidence for a peri- Siberian position of the Farewell terrane during the early Paleozoic. Mystic subterrane of the Farewell terrane. Three graywackes from flysch of the Mystic subterrane, Talkeetna quadrangle, were sampled with the expectation that all three were Pennsylvanian. Asample from Pingston Creek is Triassic (as revealed by an interbedded ash dated at ca. 223 Ma) and is dominated by age clusters of 341-359 and 1804-1866 Ma, both consistent with a sediment source in the Yukon-Tanana terrane. Minor age clusters at 848-869 and 1992-2018 Ma could have been sourced in the older part of the Farewell terrane. Still other minor age clusters at 432-461, 620-657, 1509-1536, and 1627-1653 Ma are not readily linked to sources that are now nearby. Asample from Surprise Glacier is mid-Mississippian or younger. Adominant age cluster at 1855-1883 and a

  10. Diachronism in the late Neoproterozoic-Cambrian arc-rift transition of North Gondwana: A comparison of Morocco and the Iberian Ossa-Morena Zone

    Science.gov (United States)

    Álvaro, J. Javier; Bellido, Félix; Gasquet, Dominique; Pereira, M. Francisco; Quesada, Cecilio; Sánchez-García, Teresa

    2014-10-01

    In the northwestern border of the West African craton (North Gondwana), a transition from late Neoproterozoic subduction/collision to Cambrian rift processes was recorded in the Anti-Atlas (Morocco) and in the Ossa-Morena Zone (Iberia). Cambrian rifting affected both Pan-African and Cadomian basements in a stepwise and diachronous way. Subsequently, both areas evolved into a syn-rift margin episodically punctuated by uplift and tilting that precluded Furongian sedimentation. A comparison of sedimentary, volcanic and geodynamic evolution is made in the late Neoproterozoic (Pan-African and Cadomian) belts and Cambrian rifts trying to solve the apparent diachronous (SW-NE-trending) propagation of an early Palaeozoic rifting regime that finally led to the opening of the Rheic Ocean.

  11. Late Paleoproterozoic-Neoproterozoic multi-rifting events in the North China Craton and their geological significance: A study advance and review

    Science.gov (United States)

    Zhai, Mingguo; Hu, Bo; Zhao, Taiping; Peng, Peng; Meng, Qingren

    2015-11-01

    An important Paleoproterozoic mobile belt event took place in the North China Craton (NCC), termed the Hutuo Movement. This event has been interpreted to represent cratonic reworking characterized by rifting-subduction-collision processes. The NCC then evolved into a stable platform or para-platform tectonic setting in Earth's middle age period more than ~ 1.0 Ga. Thick Late Paleoproterozoic-Neoproterozoic sedimentary sequences were extensively deposited on the early metamorphic basement. The major sedimentary basins include the Xiong'er aulacogen system in the south-central NCC, the Yan-Liao aulacogen system in the north-central NCC, the Northern marginal rift system in the northwestern NCC and the Eastern marginal rift system in the eastern NCC. The following four stages of magmatic activity are recognized in the Late Paleoproterozoic to Neoproterozoic interval: (1) ~ 1800 to 1780 Ma Xiong'er igneous province (XIP), (2) ~ 1720 to 1620 Ma anorogenic magmatic association, (3) ~ 1350 to 1320 Ma diabase sill swarms, and (4) ~ 900 Ma mafic dyke swarms. These four magmatic events suggest that the NCC was situated in an intra-plate setting for a long time from ~ 1.8 Ga to ~ 0.7 Ga or even younger, and the magmatic events were associated with multi-stage rifting activities. We document that the NCC was in a long-term extensional tectonic setting during Late Paleoproterozoic-Neoproterozoic era. The main ore deposits in this period are magmatic type iron deposits related to anorthosite-gabbro bodies, REE-Nb-Fe and Pb-Zn-Cu-Fe deposits related to Mesoproterozoic-Neoproterozoic rifts. Orogenic metal deposits are absent. There is no evidence indicating that the Grenville or other orogenic events affected the NCC. The reason for the absence of Grenvillian aged events in the NCC is probably because it was far from the edge of the Nuna supercontinent, if such a supercontinent did exist. There is another possibility that the Earth's middle age represented a particular tectonic

  12. Neoproterozoic Oxygenation of Earth Surface Environments Reflected in the Late Evolution of the O2-Dependent Vitamin B12 Biosynthesis Pathway

    Science.gov (United States)

    Saito, M. A.; Bertrand, E. M.; Anbar, A.

    2008-12-01

    There are multiple lines of evidence for a significant rise of O2 in the Earth's atmosphere ~2.4 Ga. A second oxygenation event in the Neoproterozoic is not as well constrained. These changes in environmental redox affected the abundances of bioessential elements. Trace elements such as Co, Fe, and Ni were likely favored in the early evolution of metalloenzymes, prior to the first oxidation event. Consistent with this expectation, vitamin B12 is a Co-containing biomolecule whose biosynthesis is thought to have evolved prior to the origin of oxygenic photosynthesis and the first rise in O2. However, biochemical characterization of the many enzymes involved in B12 biosynthesis has revealed two distinct pathways: an O2-independent pathway and an O2-dependant pathway. The major difference between these pathways involves the timing of the insertion of Co. We examined the amino acid sequences of enzymes in the B12 biosynthesis pathway from a set of 100 phylogenetically diverse microbial genomes, focusing on enzymes exclusive to each pathway as well as enzymes shared by both. Molecular clock and phylogenetic analyses were performed on alignments of the sequences obtained from these study genomes. This approach focused on functional genes rather than the phylogeny of microbes in an attempt to understand the evolution of the pathway itself, rather than its presence in individual phylogenetic groups. Clear differences in age are apparent between representatives of each pathway. The O2-independent pathway and enzymes shared in both pathways show the most ancient last common ancestors. In contrast, the enzymes associated exclusively with the O2-dependent pathway diverged from a common ancestor less than a billion years ago. Phylogenetic analysis suggests that these enzymes were recruited from other biochemical pathways. From these results it seems likely that the evolution of the O2-dependent pathway occurred long after the initial evolution of the B12 biosynthesis. This

  13. 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.

  14. Volcanosedimentary Basins in the Arabian-Nubian Shield: Markers of Repeated Exhumation and Denudation in a Neoproterozoic Accretionary Orogen

    Directory of Open Access Journals (Sweden)

    Victoria Pease

    2013-07-01

    Full Text Available The Arabian-Nubian Shield (ANS includes Middle Cryogenian-Ediacaran (790–560 Ma sedimentary and volcanic terrestrial and shallow-marine successions unconformable on juvenile Cryogenian crust. The oldest were deposited after 780–760 Ma shearing and suturing in the central ANS. Middle Cryogenian basins are associated with ~700 Ma suturing in the northern ANS. Late Cryogenian basins overlapped with and followed 680–640 Ma Nabitah orogenesis in the eastern ANS. Ediacaran successions are found in pull-apart and other types of basins formed in a transpressive setting associated with E-W shortening, NW-trending shearing, and northerly extension during final amalgamation of the ANS. Erosion surfaces truncating metamorphosed arc rocks at the base of these successions are evidence of periodic exhumation and erosion of the evolving ANS crust. The basins are evidence of subsequent subsidence to the base level of alluvial systems or below sea level. Mountains were dissected by valley systems, yet relief was locally low enough to allow for seaways connected to the surrounding Mozambique Ocean. The volcanosedimentary basins of the ANS are excellently exposed and preserved, and form a world-class natural laboratory for testing concepts about crustal growth during the Neoproterozoic and for the acquisition of data to calibrate chemical and isotopic changes, at a time in geologic history that included some of the most important, rapid, and enigmatic changes to Earth’s environment and biota.

  15. Hypothesized link between Neoproterozoic greening of the land surface and the establishment of an oxygen-rich atmosphere

    Science.gov (United States)

    Kump, Lee R.

    2014-01-01

    Considerable geological, geochemical, paleontological, and isotopic evidence exists to support the hypothesis that the atmospheric oxygen level rose from an Archean baseline of essentially zero to modern values in two steps roughly 2.3 billion and 0.8–0.6 billion years ago (Ga). The first step in oxygen content, the Great Oxidation Event, was likely a threshold response to diminishing reductant input from Earth’s interior. Here I provide an alternative to previous suggestions that the second step was the result of the establishment of the first terrestrial fungal–lichen ecosystems. The consumption of oxygen by aerobes respiring this new source of organic matter in soils would have necessitated an increase in the atmospheric oxygen content to compensate for the reduced delivery of oxygen to the weathering environment below the organic-rich upper soil layer. Support for this hypothesis comes from the observed spread toward more negative carbon isotope compositions in Neoproterozoic (1.0–0.542 Ga) and younger limestones altered under the influence of ground waters, and the positive correlation between the carbon isotope composition and oxygen content of modern ground waters in contact with limestones. Thus, the greening of the planet’s land surfaces forced the atmospheric oxygen level to a new, higher equilibrium state. PMID:25225378

  16. Paleo-climatic and paleo-environmental evolution of the Neoproterozoic basal sedimentary cover on the Río de La Plata Craton, Argentina: Insights from the δ13C chemostratigraphy

    Science.gov (United States)

    Gómez-Peral, Lucía E.; Sial, Alcides N.; Arrouy, M. Julia; Richiano, Sebastián; Ferreira, Valderez P.; Kaufman, Alan J.; Poiré, Daniel G.

    2017-05-01

    The Sierras Bayas Group of the Tandilia System constitutes the Neoproterozoic sedimentary cover of the Río de La Plata Craton in Argentina that accumulated amid the breakup of the Rodinia supercontinent and subsequent assembly of Gondwanaland. Evidence for glaciation in the Villa Mónica Formation (VMF) at the base of the succession comes in the form of iron-rich laminated sediments containing dropstones composed predominantly of basement crystalline rocks and quartzites that, are sequentially overlain by a phosphatic mudstone and a 40 m thick stromatolitic dolomite. Subtidal facies preserve columnar forms similar to post-glacial tubestone stromatolites seen in the Neoproterozoic records. These morphologies suggest rapid growth associated with elevated seawater alkalinity and high rates of carbonate accumulation records. The VMF dolomites in our four studied sections near Olavarría-Sierras Bayas area reveal a pronounced negative-to-positive δ13C up section that is similarly to these cap carbonates and others worldwide. Our sedimentological and geochemical study of the VMF sections reveal consistent carbon and oxygen isotope trends that may be useful for detailed intra-basinal correlations. Samples of the VMF fabric-retentive dolomite preserve an unusually narrow range of non-radiogenic strontium isotopic compositions (0.7068 to 0.7070) that are consistent with Cryogenian limestone facies in the potential Namibian and Brazilian equivalents. Exceptional preservation of 87Sr/86Sr compositions suggest the possibility of primary dolomite precipitation in post-glacial seawater, and furthermore that REE patterns and distributions may yield similar insights to redox conditions in the depositional basin. In particular, the VMF dolomites reveal depleted LREE abundances, a negative Ce anomaly, positive La and Gd anomalies, and low Y/Ho values. As a whole, these observations suggest oxidizing post-glacial seawater conditions associated with significant freshwater inputs

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

    Science.gov (United States)

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

    2018-01-01

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

  18. The importance of XRD analysis in provenance and palaeoenvironmental studies of the Piedras de Afilar Formation, Neoproterozoic of Uruguay

    Science.gov (United States)

    Pamoukaghlian, K.; Poiré, D. G.; Gaucher, C.; Uriz, N.; Cingolani, C.; Frigeiro, P.

    2009-04-01

    The Piedras de Afilar Formation crops out in the southeast part of Uruguay, forming part of the Tandilia Terrane (sensu Bossi et al. 2005). Pamoukaghlian et al. (2006) and Gaucher et al. (2008) have published δ13C, δ18O and U/Pb SHRIMP results, which indicate a Neoproterozoic age for this formation. The palaeoenvironment has been defined as a shallow marine platform based on the presence of interference ripples, hummocky and mega-hummocky cross-stratification. X-ray diffraction (XRD) analyses help to better constrain the palaeoenvironment: the presence of chlorite/smectite found in black shales, suggest a reducing environment, and abundant illite indicates a cold to temperate climate. Provenance studies have been undertaken that utilise a combination of detailed palaeocurrent measurements, petrographic descriptions, XRD analyses, and geochemical isotopic analyses, including U/Pb SHRIMP determinations. Mineral compositional diagrams for sandstones suggest a stable cratonic provenance. Palaeocurrents are mainly from the NNE, indicating a provenance from the cratonic areas of the Tandilia Terrane. The illite crystal index indicates diagenetic to low-metamorphic conditions for the sequence; this is important to confirm that the identified minerals are authigenic. Clay minerals identified by XRD analysis of sandstones from the siliciclastic member are illite (80 - 90%), kaolinite (5 - 10%), and chlorite (5 - 10%). This is consistent with a provenance from the cratonic areas (quartz-feldspar dominated rock types). Isotopic analyses have been undertaken to provide better constraints on the tectonic setting. U/Pb SHRIMP ages for the youngest zircons are 990 Ma (Gaucher et al. 2008), and the basal granite (Granito de la Paz) is 2056 ± 11 Ma (Hartmann et al. 2001), suggesting a provenance from the Archaean basement for the Piedras de Afilar Formation, like its counterparts in the Rio de la Plata Craton. References Bossi, J., Piñeyro, D., Cingolani, C. (2005). El l

  19. Slab break-off triggered lithosphere - asthenosphere interaction at a convergent margin: The Neoproterozoic bimodal magmatism in NW India

    Science.gov (United States)

    Wang, Wei; Pandit, Manoj K.; Zhao, Jun-Hong; Chen, Wei-Terry; Zheng, Jian-Ping

    2018-01-01

    The Neoproterozoic Malani Igneous Suite (MIS) is described as the largest felsic igneous province in India. The linearly distributed Sindreth and Punagarh basins located along eastern margin of this province represent the only site of bimodal volcanism and associated clastic sediments within the MIS. The in-situ zircon U-Pb dating by LA-ICPMS reveals that the Sindreth rhyolites were erupted at 769-762 Ma. Basaltic rocks from both the basins show distinct geochemical signatures that suggest an E-MORB source for Punagarh basalts (low Ti/V ratios of 40.9-28.2) and an OIB source (high Ti/V ratios of 285-47.6) for Sindreth basalts. In the absence of any evidence of notable crustal contamination, these features indicate heterogeneous mantle sources for them. The low (La/Yb)CN (9.34-2.10) and Sm/Yb (2.88-1.08) ratios of Punagarh basalts suggest a spinel facies, relatively shallow level mantle source as compared to a deeper source for Sindreth basalts, as suggested by high (La/Yb)CN (7.24-5.24) and Sm/Yb (2.79-2.13) ratios. Decompression melting of an upwelling sub-slab asthenosphere through slab window seems to be the most plausible mechanism to explain the geochemical characteristics. Besides, the associated felsic volcanics show A2-type granite signatures, such as high Y/Nb (5.97-1.55) and Yb/Ta (9.36-2.57) ratios, consistent with magma derived from continental crust that has been through a cycle of continent-continent collision or an island-arc setting. A localized extension within an overall convergent scenario is interpreted for Sindreth and Punagarh volcanics. This general convergent setting is consistent with the previously proposed Andean-type continental margin for NW Indian block, the Seychelles and Madagascar, all of which lay either at the periphery of Rodinia supercontinent or slightly off the Supercontinent.

  20. Thrusting and multiple folding in the Neoproterozoic Pan-African basement of Wadi Hodein area, south Eastern Desert, Egypt

    Science.gov (United States)

    Abdeen, M. M.; Sadek, M. F.; Greiling, R. O.

    2008-09-01

    Detailed field mapping and structural studies of the area around the mouth of Wadi Hodein, some 20 km west of Shalatein at the Red Sea coast in the south Eastern Desert of Egypt, revealed four phases of structural deformation (D1-D4) affecting the Neoproterozoic Pan-African basement rocks. D1 is related to arc-arc collision and is represented by ENE-WSW oriented megascopic upright open folds associated with low angle thrusts and mesoscopic tight, overturned and recumbent F1 folds. Kinematic indicators indicate thrusting towards the SSE. D2 is represented by NNW-SSE oriented megascopic and mesoscopic folds, which are tight, verge towards the WSW and display a left-stepping en echelon pattern. D3 includes major NNW-SSE trending sinistral shear zones that show subordinate reverse fault components and dip steeply towards the ENE. These sinistral shear zones are comparable with the Najd Fault System, as they display a similar sense of movement and relationships to earlier structures. Therefore, they are interpreted to be the continuation of the Najd Shear System in southern Egypt. D2 and D3 are related to accretion of east and west Gondwana. D4 is represented by E-W oriented dextral faults with left-stepping segments. The first three deformation events are in agreement with the general evolutionary model for the East African Orogen in the Arabian-Nubian Shield that begins with NNW-SSE shortening, followed by ENE-WSW compression and subsequent deformation by the NNW-SSE striking Najd Fault System. The E-W dextral faults may be the conjugate shear fractures to the D3 NNW-SSE oriented sinistral wrench faults or are related to a subsequent event, D4. NW-SE oriented gold-bearing quartz veins originated during D1 and were subsequently deformed by D2-D4 events.

  1. Geology of the Mount Rogers area, revisited: Evidence of Neoproterozoic continental rifting, glaciation, and the opening and closing of the Iapetus ocean, Blue Ridge, VA–NC–TN

    Science.gov (United States)

    Merschat, Arthur J.; Southworth, C. Scott; Holm-Denoma, Christopher S.; McAleer, Ryan J.; Merschat, Arthur J.

    2016-01-01

    Recent field and geochronological studies in eight 7.5-minute quadrangles near Mount Rogers in Virginia, North Carolina and Tennessee recognize important stratigraphic and structural relationships for the Neoproterozoic Mount Rogers and Konnarock formations, the northeast end of the Mountain City window, the separation of Mesoproterozoic rocks of the Blue Ridge into three age groups, and timing and emplacement of the Blue Ridge thrust sheet. The study area includes folded and faulted Paleozoic strata of the Valley and Ridge to metamorphic and igneous rocks of the Blue Ridge. In the Valley and Ridge, Cambrian to Middle Ordovician carbonate and clastic rocks are exposed in a syncline on the Pulaski thrust sheet; these rocks are overridden by the Blue Ridge thrust sheet. The northeast end of the Mountain City window is interpreted as a simple window; the Stone Mountain fault is folded and continues as the Iron Mountain fault on the NW-side of the window. The Stone Mountain fault does not exist to the NE near the Razor Ridge volcanic center. Instead a continuous section of Proterozoic gneisses, Mount Rogers Formation, Konnarock Formation and Chilhowee Group is now recognized. Rhyolites of the Mount Rogers Formation range from 760–749Ma, with detrital zircon age populations from associated volcaniclastic rocks indicating magmatism and rifting began by ~780 Ma. Rhyolite blocks in the Konnarock Formation and a change from rift-related clastic rocks of the Mount Rogers Formation transitioning to maroon laminites and laminites with dropstones, suggest that the Konnarock Formation may be as old as ~749 Ma. Mesoproterozoic crystalline rocks of the Blue Ridge, previously referred to as the Cranberry Gneiss, are separated based on field relationships and SHRIMP U–Pb geochronology: (1) pre-Grenvillian crust,1.33 Ga; (2) 1190–1140 Ma granitoids; and (3) 1075–1030 Ma granitoids. Multiple greenschist-facies high-strain zones, including the 2–11 km wide Fries high

  2. A normalised seawater strontium isotope curve. Possible implications for Neoproterozoic-Cambrian weathering rates and the further oxygenation of the Earth

    International Nuclear Information System (INIS)

    Shields, G.A.

    2007-01-01

    The strontium isotope composition of seawater is strongly influenced on geological time scales by changes in the rates of continental weathering relative to ocean crust alteration. However, the potential of the seawater 87 Sr/ 86 Sr curve to trace globally integrated chemical weathering rates has not been fully realised because ocean 87 Sr/ 86 Sr is also influenced by the isotopic evolution of Sr sources to the ocean. A preliminary attempt is made here to normalise the seawater 87 Sr/ 86 Sr curve to plausible trends in the 87 Sr/ 86 Sr ratios of the three major Sr sources: carbonate dissolution, silicate weathering and submarine hydrothermal exchange. The normalised curve highlights the Neoproterozoic-Phanerozoic transition as a period of exceptionally high continental influence, indicating that this interval was characterised by a transient increase in global weathering rates and/or by the weathering of unusually radiogenic crustal rocks. Close correlation between the normalised 87 Sr/ 86 Sr curve, a published seawater δ 34 S curve and atmospheric pCO 2 models is used here to argue that elevated chemical weathering rates were a major contributing factor to the steep rise in seawater 87 Sr/ 86 Sr from 650 Ma to 500 Ma. Elevated weathering rates during the Neoproterozoic-Cambrian interval led to increased nutrient availability, organic burial and to the further oxygenation of Earth's surface environment. Use of normalised seawater 87 Sr/ 86 Sr curves will, it is hoped, help to improve future geochemical models of Earth System dynamics. (orig.)

  3. Intraplate earthquake swarm in Belo Jardim, NE Brazil: reactivation of a major Neoproterozoic shear zone (Pernambuco Lineament)

    Science.gov (United States)

    Lopes, Afonso E. V.; Assumpção, Marcelo; do Nascimento, Aderson F.; Ferreira, Joaquim Mendes; Menezes, Eduardo A. S.; Barbosa, José Roberto

    2010-03-01

    Intraplate earthquakes in stable continental areas have been explained basically by reactivation of pre-existing zones of weakness, stress concentration, or both. Zones of weakness are usually identified as sites of the last major orogeny, provinces of recent alkaline intrusions, or stretched crust in ancient rifts. However, it is difficult to identify specific zones of weakness and intraplate fault zones are not always easily correlated with known geological features. Although Northeastern Brazil is one of the most seismically active areas in the country (magnitudes 5 roughly every 5 yr), with hypocentral depths shallower than ~10 km and seismic zones as long as 30-40 km, no clear relationship with the known surface geology can be usually established with confidence, and a clear identification of zones of weakness has not yet been possible. Here we present the first clear case of seismic activity occurring as reactivation of an old structure in Brazil: the Pernambuco Lineament, a major Neoproterozoic shear zone. The 2004 earthquake swarm of Belo Jardim (magnitudes up to 3.1) and the recurrent activities in the nearby towns of São Caetano and Caruaru (magnitudes up to 4.0 and 3.8), show that the Pernambuco Lineament is a weak zone. A local seismic network showed that the Belo Jardim swarm of 2004 November occurred by normal faulting on a North dipping, E-W oriented fault plane in close agreement with the E-W trending structures within the Pernambuco Lineament. The Belo Jardim activity was concentrated in a 1.5 km (E-W) by 2 km (downdip) fault area, and average depth of 4.5 km. The nearby Caruaru activity occurs as both strike-slip and normal faulting, also consistent with local structures of the Pernambuco Lineament. The focal mechanisms of Belo Jardim, Caruaru and S. Caetano, indicate E-W compressional and N-S extensional principal stresses. The NS extension of this stress field is larger than that predicted by numerical models such as those of Coblentz

  4. Syn- and Post-Accretionary Structures in the Neoproterozoic Central Allaqi-Heiani Suture Zone, Southeastern Egypt

    Science.gov (United States)

    Abdeen, M. M.; Abdelghaffar, A. A.

    2012-04-01

    The Allaqi-Heiani suture (AHS) is the western part of the main Allaqi-Heiani-Gerf-Onib-Sol Hamed-Yanbu suture and represents one of the Neoproterozoic, arc-arc sutures in the Arabian-Nubian Shield (ANS). It separates the ca. 750 Ma South Eastern Desert terrane in the north from the ca. 830-720 Ma Gabgaba terrane in the south. The AHS is a deformed belt of ophiolitic rocks, syn-tectonic granitoids and metasediments. The central AHS zone is divided into three structural domains. The western domain (Ι) is characterized by NNE low thrusts and SSW-vergent folds. The central domain (ΙΙ) includes upright tight to isoclinal NNW-SSE oriented folds and transpressional faults. The eastern domain (ΙΙΙ) shows NNW-SSE oriented open folds. Structural analysis indicates that the area has a poly-phase deformation history involving at least two events. Event D1 was an N-S to NNE-SSW regional shortening generating the SSW-verging folds and the NNE dipping thrusts. Event D2 was an ENE-WSW shortening producing NNW-SSE oriented folds in the central and eastern parts of the study area and reactivating older thrusts with oblique-slip reverse fault movement. The tectonic evolution of the area involves two episodes of collision: an early collision between the South Eastern Desert terrane and the Gabgaba terrane along the AHS after the consumption of a basin floored by oceanic crust above a north-dipping subduction zone; and a later collision between East- and West-Gondwanas at ca. 750-650 Ma, leading to the closure of the Mozambique Ocean. This collision deformed the AHS along N-S trending shortening zones and produced NW-SE and NE-SW oriented sinistral and dextral transpressional faults, respectively. The early collision episode is related to the terrane accretion during the early Pan-African orogen, while the later phase is related to a late Pan-African or Najd orogen.

  5. Transition from island-arc to passive setting on the continental margin of Gondwana: U-Pb zircon dating of Neoproterozoic metaconglomerates from the SE margin of the Teplá-Barrandian Unit, Bohemian Massif

    Czech Academy of Sciences Publication Activity Database

    Sláma, Jiří; Dunkley, D. J.; Kachlík, V.; Kusiak, M. A.

    2008-01-01

    Roč. 461, 1-4 (2008), s. 44-59 ISSN 0040-1951 Institutional research plan: CEZ:AV0Z30130516 Keywords : Bohemian Massif * Teplá–Barrandian Unit * Neoproterozoic * Armorican Terrane Assemblage * Gondwana * zircon dating Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.677, year: 2008

  6. Genomic Ancestry, Self-Rated Health and Its Association with Mortality in an Admixed Population: 10 Year Follow-Up of the Bambui-Epigen (Brazil) Cohort Study of Ageing.

    Science.gov (United States)

    Lima-Costa, M Fernanda; Macinko, James; Mambrini, Juliana Vaz de Melo; Cesar, Cibele C; Peixoto, Sérgio V; Magalhães, Wagner C S; Horta, Bernardo L; Barreto, Mauricio; Castro-Costa, Erico; Firmo, Josélia O A; Proietti, Fernando A; Leal, Thiago Peixoto; Rodrigues, Maira R; Pereira, Alexandre; Tarazona-Santos, Eduardo

    2015-01-01

    Self-rated health (SRH) has strong predictive value for mortality in different contexts and cultures, but there is inconsistent evidence on ethnoracial disparities in SRH in Latin America, possibly due to the complexity surrounding ethnoracial self-classification. We used 370,539 Single Nucleotide Polymorphisms (SNPs) to examine the association between individual genomic proportions of African, European and Native American ancestry, and ethnoracial self-classification, with baseline and 10-year SRH trajectories in 1,311 community dwelling older Brazilians. We also examined whether genomic ancestry and ethnoracial self-classification affect the predictive value of SRH for subsequent mortality. European ancestry predominated among participants, followed by African and Native American (median = 84.0%, 9.6% and 5.3%, respectively); the prevalence of Non-White (Mixed and Black) was 39.8%. Persons at higher levels of African and Native American genomic ancestry, and those self-identified as Non-White, were more likely to report poor health than other groups, even after controlling for socioeconomic conditions and an array of self-reported and objective physical health measures. Increased risks for mortality associated with worse SRH trajectories were strong and remarkably similar (hazard ratio ~3) across all genomic ancestry and ethno-racial groups. Our results demonstrated for the first time that higher levels of African and Native American genomic ancestry--and the inverse for European ancestry--were strongly correlated with worse SRH in a Latin American admixed population. Both genomic ancestry and ethnoracial self-classification did not modify the strong association between baseline SRH or SRH trajectory, and subsequent mortality.

  7. Genomic Ancestry, Self-Rated Health and Its Association with Mortality in an Admixed Population: 10 Year Follow-Up of the Bambui-Epigen (Brazil Cohort Study of Ageing.

    Directory of Open Access Journals (Sweden)

    M Fernanda Lima-Costa

    Full Text Available Self-rated health (SRH has strong predictive value for mortality in different contexts and cultures, but there is inconsistent evidence on ethnoracial disparities in SRH in Latin America, possibly due to the complexity surrounding ethnoracial self-classification.We used 370,539 Single Nucleotide Polymorphisms (SNPs to examine the association between individual genomic proportions of African, European and Native American ancestry, and ethnoracial self-classification, with baseline and 10-year SRH trajectories in 1,311 community dwelling older Brazilians. We also examined whether genomic ancestry and ethnoracial self-classification affect the predictive value of SRH for subsequent mortality.European ancestry predominated among participants, followed by African and Native American (median = 84.0%, 9.6% and 5.3%, respectively; the prevalence of Non-White (Mixed and Black was 39.8%. Persons at higher levels of African and Native American genomic ancestry, and those self-identified as Non-White, were more likely to report poor health than other groups, even after controlling for socioeconomic conditions and an array of self-reported and objective physical health measures. Increased risks for mortality associated with worse SRH trajectories were strong and remarkably similar (hazard ratio ~3 across all genomic ancestry and ethno-racial groups.Our results demonstrated for the first time that higher levels of African and Native American genomic ancestry--and the inverse for European ancestry--were strongly correlated with worse SRH in a Latin American admixed population. Both genomic ancestry and ethnoracial self-classification did not modify the strong association between baseline SRH or SRH trajectory, and subsequent mortality.

  8. Neoproterozoic diamictite-bearing sedimentary rocks in the northern Yili Block and their constraints on the Precambrian evolution of microcontinents in the Western Central Asian Orogenic Belt

    Science.gov (United States)

    He, Jingwen; Zhu, Wenbin; Zheng, Bihai; Wu, Hailin; Cui, Xiang; Lu, Yuanzhi

    2015-12-01

    The origin and tectonic setting of Precambrian sequences in the Central Asian Orogenic Belt (CAOB) have been debated due to a lack of high resolution geochronological data. Answering this question is essential for the understanding of the tectonic framework and Precambrian evolution of the blocks within the CAOB. Here we reported LA-ICP-MS detrital zircon U-Pb ages and in-situ Hf isotopic data for Neoproterozoic sedimentary cover in the northern Yili Block, an important component of the CAOB, in order to provide information on possible provenance and regional tectonic evolution. A total of 271 concordant U-Pb zircon ages from Neoproterozoic sedimentary cover in the northern Yili Block define three major age populations of 1900-1400 Ma, 1300-1150 Ma and 700-580 Ma, which are quite different from cratons and microcontinents involved in the CAOB. Although it is not completely consistent with the local basement ages, an autochthonous provenance interpretation is more suitable. Some zircon grains show significant old Hf model ages (TDMC; 3.9-2.4 Ga) and reveal continental crust as old as Paleoarchean probably existed. Continuous Mesoproterozoic zircon age populations exhibit large variations in the εHf(t) ratios, suggesting the long-time involvement of both reworked ancient crust and juvenile material. Similar Mesoproterozoic evolution pattern is identified in many continental terranes involved in the CAOB that surround the Tarim Craton. Based on our analysis and published research, we postulate that the northern Yili Block, together with Chinese Central Tianshan, Kyrgyz North Tianshan and some other microcontinents surrounding the Tarim Craton, once constituted the continental margin of the Tarim Craton in the Mesoproterozoic, formed by long-lived accretionary processes. Most of the late Neoproterozoic zircons exhibit significant positive εHf(t) ratios, suggesting the addition of juvenile crust. It is consistent with the tectonic event related to the East Africa

  9. Relict zircon U-Pb age and O isotope evidence for reworking of Neoproterozoic crustal rocks in the origin of Triassic S-type granites in South China

    Science.gov (United States)

    Gao, Peng; Zheng, Yong-Fei; Chen, Yi-Xiang; Zhao, Zi-Fu; Xia, Xiao-Ping

    2018-02-01

    Granites derived from partial melting of sedimentary rocks are generally characterized by high δ18O values and abundant relict zircons. Such relict zircons are valuable in tracing the source rocks of granites and the history of crustal anatexis. Here we report in-situ U-Pb ages, O isotopes and trace elements in zircons from Triassic granites in the Zhuguangshan and Jiuzhou regions, which are located in the Nanling Range and the Darongshan area, respectively, in South China. Zircon U-Pb dating yields magma crystallization ages of 236 ± 2 Ma for the Zhuguangshan granites and 246 ± 2 Ma to 252 ± 3 Ma for the Jiuzhou granites. The Triassic syn-magmatic zircons are characterized by high δ18O values of 10.1-11.9‰ in Zhuguangshan and 8.5-13.5‰ in Jiuzhou. The relict zircons show a wide range of U-Pb ages from 315 to 2185 Ma in Zhuguangshan and from 304 to 3121 Ma in Jiuzhou. Nevertheless, a dominant age peak of 700-1000 Ma is prominent in both occurrences, demonstrating that their source rocks were dominated by detrital sediments weathered from Neoproterozoic magmatic rocks. Taking previous results for regional granites together, Neoproterozoic relict zircons show δ18O values in a small range from 5 to 8‰ for the Nanling granites but a large range from 5 to 11‰ for the Darongshan granites. In addition, relict zircons of Paleozoic U-Pb age occur in the two granitic plutons. They exhibit consistently high δ18O values similar to the Triassic syn-magmatic zircons in the host granites. These Paleozoic relict zircons are interpreted as the peritectic product during transient melting of the metasedimentary rocks in response to the intracontinental orogenesis in South China. Therefore, the relict zircons of Neoproterozoic age are directly inherited from the source rocks of S-type granites, and those of Paleozoic age record the transient melting of metasedimentary rocks before intensive melting for granitic magmatism in the Triassic.

  10. Neoproterozoic tectonic evolution of the Jebel Saghro and Bou Azzer - El Graara inliers, eastern and central Anti-Atlas, Morocco

    Science.gov (United States)

    Walsh, Gregory J.; Aleinikoff, John N.; Harrison, Richard W.; Burton, William C.; Quick, James E.; Benziane, Foudad; Yazidi, Abdelaziz; Saadane, Abderrahim

    2012-01-01

    New mapping, geochemistry, and 17 U–Pb SHRIMP zircon ages from rocks of the Sirwa, Bou Azzer–El Graara, and Jebel Saghro inliers constrain the Neoproterozoic evolution of the eastern Anti-Atlas during Pan-African orogenesis. In the Sirwa inlier, Tonian quartzite from the pre Pan-African passive margin deposits of the Mimount Formation contains detrital zircon derived entirely from the West African Craton (WAC), with most grains yielding Eburnean Paleoproterozoic ages of about 2050 Ma. Cryogenian Pan-African orogenic activity (PA1) from about 760 to 660 Ma included northward-dipping subduction to produce a volcanic arc, followed by ophiolite obduction onto the WAC. In the Bou Azzer–El Graara inlier, calc-alkaline granodiorite and quartz diorite, dated at 650–646 Ma, are syn- to post-tectonic with respect to the second period of Pan-African orogenesis (PA2), arc-continent accretion, and related greenschist facies metamorphism. Slab break-off and lithospheric delimination may have provided the source for the supra-subduction calc-alkaline plutons. At about 646 Ma, quartz diorite intruded the Tiddiline formation placing an upper limit on molassic deposition. Widespread Ediacaran high-K calc-alkaline to shoshonitic plutonism and volcanism during the final stage of Pan-African orogenesis (PA3) occurred in a setting related to either modification of the margin of the WAC or formation of a continental volcanic arc above a short-lived southward-dipping subduction zone. In the Saghro inlier, eight plutonic rocks yield ages ranging from about 588 to 556 Ma. Sampled plutonic rocks previously considered to be Cryogenian yielded Ediacaran ages. Peraluminous rhyolitic volcanic rocks in the lower part of the Ouarzazate Supergroup, including ash-flow tuffs of the Oued Dar’a caldera, yield ages between about 574 and 571 Ma. The Oued Dar’a caldera developed in a pull-apart graben produced by a left-step in a northeast-trending, left-lateral strike-slip fault zone, and

  11. Adakite-gabbro-anorthosite magmatism at the final (576-546 Ma) development stage of the Neoproterozoic active margin in the south-west of the Siberian craton

    Science.gov (United States)

    Vernikovskaya, A. E.; Vernikovsky, V. A.; Matushkin, N. Yu.; Kadilnikov, P. I.; Romanova, I. V.; Larionov, A. N.

    2017-12-01

    In the late Neoproterozoic a prolonged active continental margin mode dominated the southwestern margin of the Siberian craton. Based on results of geological, petrological-geochemical, U-Th-Pb and Sm-Nd, Rb-Sr isotope investigations, for the first time we established that on the final evolution stage of this margin 576-546 Ma, intrusions of adakites and gabbro-anorthosites of the Zimoveyniy massif were emplaced in the South Yenisei Ridge. These new data indicate genetic relationships of the studied adakites and host NEB-metabasites. The formation of adakites could have been due to a crustal or a mantle-crustal source in a setting of transform sliding of lithospheric plates after the subduction stopped.

  12. New Sm/Nd and U/Pb geochronological constraints of the Archean to neoproterozoic evolution of the Amparo basement complex of the Central Ribeira Belt, Southeastern Brazil

    International Nuclear Information System (INIS)

    Fetter, A.H.; Hackspacher, P.C.; Ebbert, H.D; Dantas, E.L; Costa, A.C.D. da

    2001-01-01

    The Amparo Basement Complex is a distinctive collage of migmatitic tronjhemitetonalite- granodiorite (TTG) orthogneisses that represents the older basement exposures within the Central Ribeira Belt, a Late Neoproterozoic (ca. 600 Ma) collisional belt in southeastern Brazil. These basement gneisses are overlain by Mesoproterozoic to Neoproterozoic supracrustal sequences, and intruded by Neoproterozoic collisional granitoids. Pioneering Rb/Sr, Pb/Pb and K/Ar geochronological studies of the Amparo Complex, e.g. (Wernick et al., 1981; Wernick and Oliveira, 1986; Arthur, 1988; Tassinari, 1988; Campos Neto, 1991) provided some initial insights into the antiquity and geologic evolution of the complex, but little about the crustal evolution of the constituent gneisses. Furthermore, the susceptibility of these systems to partial isotopic resetting, left some doubt about the timing and true number of geologic events recorded by these polydeformed rocks. Recent Sm/Nd whole rock (Dantas et al., 2000) and new U/Pb single crystal zircon and monazite data obtained from the Amparo Complex, however, now furnish information on the crustal growth history of the basement and provide precise age constraints on the timing of events related to the geologic evolution of the complex. Based on these new data, it appears that the oldest rocks within the complex are polymigmatized tronjhemitic gneisses located near the town of Amparo. The oldest phase of this migmatite yields a U/Pb zircon age of 3,024 +/- 9 Ma. Sm/Nd data from this locale yields a Nd T(DM) model age of 3.28 Ga suggesting that the genesis of this crustal unit involved some input from yet older crust. Data from banded tonalitic gneisses collected ca. 50 km south of Amparo indicate that subsequent Archean crustal growth around the older core occurred around 2.77 Ga (U/Pb zircon age of 2,772 +/- 26 Ma. A Nd T(DM) model age of 3.02 Ga obtained from these tonalites also indicate enrichment from older crustal sources during their

  13. The role of post-collisional strike-slip tectonics in the geological evolution of the late Neoproterozoic volcano-sedimentary Guaratubinha Basin, southern Brazil

    Science.gov (United States)

    Barão, Leonardo M.; Trzaskos, Barbara; Vesely, Fernando F.; de Castro, Luís Gustavo; Ferreira, Francisco J. F.; Vasconcellos, Eleonora M. G.; Barbosa, Tiago C.

    2017-12-01

    The Guaratubinha Basin is a late Neoproterozoic volcano-sedimentary basin included in the transitional-stage basins of the South American Platform. The aim of this study is to investigate its tectonic evolution through a detailed structural analysis based on remote sensing and field data. The structural and aerogeophysics data indicate that at least three major deformational events affected the basin. Event E1 caused the activation of the two main basin-bounding fault zones, the Guaratubinha Master Fault and the Guaricana Shear Zone. These structures, oriented N20-45E, are associated with well-defined right-lateral to oblique vertical faults, conjugate normal faults and vertical flow structures. Progressive transtensional deformation along the two main fault systems was the main mechanism for basin formation and the deposition of thick coarse-grained deposits close to basin-borders. The continuous opening of the basin provided intense intermediate and acid magmatism as well as deposition of volcaniclastic sediments. Event E2 characterizes generalized compression, recorded as minor thrust faults with tectonic transport toward the northwest and left-lateral activation of the NNE-SSW Palmital Shear Zone. Event E3 is related to the Mesozoic tectonism associated with the South Atlantic opening, which generated diabase dykes and predominantly right-lateral strike-slip faults oriented N10-50W. Its rhomboidal geometry with long axis parallel to major Precambrian shear zones, the main presence of high-angle, strike-slip or oblique faults, the asymmetric distribution of geological units and field evidence for concomitant Neoproterozoic magmatism and strike-slip movements are consistent with pull-apart basins reported in the literature.

  14. Petrogenesis of Bir Madi Gabbro-Diorite and Tonalite-Granodiorite Intrusions in Southeastern Desert, Egypt: Implications for Tectono-Magmatic Processes at the Neoproterozoic Shield

    Directory of Open Access Journals (Sweden)

    M. A. OBEID

    2010-06-01

    Full Text Available The Neoproterozoic rocks of the Bir Madi area, south eastern desert, comprise a Metagabbro-Diorite Complex (GDC and a Tonalite-Granodiorite Suite (TGrS. The GDC has a weak tonalitic to strong calc-alkaline character and is made up of olivine gabbro, hornblende gabbro, diorite and monzodiorite. The olivine gabbro is characterized by abun-dance of augite and labradorite with pseudomorphic serpentine. The hornblende gabbro is mainly composed of horn-blende, labradorite, andesine and minor amounts of quartz with or without augite. The diorite consists essentially of andesine, hornblende, biotite and quartz. The GDC is compositionally broad, with a wide range of SiO2 (46-57 % and pronounced enrichment in the LILE (Ba and Sr relative to the HFSE (Nb, Y and Zr. The GDC rocks exhibit petrological and geochemical characteristics of arc-related mafic magmas, derived possibly from partial melting of a mantle wedge above an early Pan-African subduction zone of the Neoproterozoic Shield. The tonalite and granodiorite have a calc-alkaline affinity and show the geochemical signatures of I-type granitoids. The TGrS contains amphibolite enclaves and foliated gabbroic xenoliths. Based on the field evidence and geochemical data, the GDC and TGrS are not related to a single magma type through fractional crystallization. The presence of microgranular amphibolite enclaves in the tonalitic rocks suggest against their generation by partial melting of a mantle-derived basaltic source. The tonalitic magma originated from partial melting of an amphibolitic lower crust by anatexis process at a volcanic arc regime during construction of the Arabian-Nubian Shield. Fractional crystallization of K-feldspar and biotite gave more developed granodiorite variety from the tonalitic magma. The gabbroic xenoliths are similar in the chemical composition to the investigated metagabbros. They are incompletely digested segments from the adjacent metagabbro rocks incorporated into the

  15. Detrital zircon analysis of Mesoproterozoic and neoproterozoic metasedimentary rocks of northcentral idaho: Implications for development of the Belt-Purcell basin

    Science.gov (United States)

    Lewis, R.S.; Vervoort, J.D.; Burmester, R.F.; Oswald, P.J.

    2010-01-01

    The authors analyzed detrital zircon grains from 10 metasedimentary rock samples of the Priest River complex and three other amphibolite-facies metamorphic sequences in north-central Idaho to test the previous assignment of these rocks to the Mesoproterozoic Belt-Purcell Supergroup. Zircon grains from two samples of the Prichard Formation (lower Belt) and one sample of Cambrian quartzite were also analyzed as controls with known depositional ages. U-Pb zircon analysis by laser ablation - inductively coupled plasma - mass spectrometry reveals that 6 of the 10 samples contain multiple age populations between 1900 and 1400 Ma and a scatter of older ages, similar to results reported from the Belt- Purcell Supergroup to the north and east. Results from the Priest River metamorphic complex confirm previous correlations with the Prichard Formation. Samples from the Golden and Elk City sequences have significant numbers of 1500-1380 Ma grains, which indicates that they do not predate the Belt. Rather, they are probably from a relatively young, southwestern part of the Belt Supergroup (Lemhi subbasin). Non-North American (1610-1490 Ma) grains are rare in these rocks. Three samples of quartzite from the Syringa metamorphic sequence northwest of the Idaho batholith contain zircon grains younger than the Belt Supergroup and support a Neoproterozoic age. A single Cambrian sample has abundant 1780 Ma grains and none younger than ~1750 Ma. These results indicate that the likely protoliths of many high-grade metamorphic rocks in northern Idaho were strata of the Belt-Purcell Supergroup or overlying rocks of the Neoproterozoic Windermere Supergroup and not basement rocks.

  16. U-Pb zircon geochronology of the Paleoproterozoic Tagragra de Tata inlier and its Neoproterozoic cover, western Anti-Atlas, Morocco

    Science.gov (United States)

    Walsh, G.J.; Aleinikoff, J.N.; Benziane, F.; Yazidi, A.; Armstrong, T.R.

    2002-01-01

    New U-Pb zircon data obtained by sensitive high resolution ion microprobe (SHRIMP) from the Tagragra de Tata inlier in the western Anti-Atlas, Morocco establish Paleoproterozoic ages for the basement schists, granites, and metadolerites, and a Neoproterozoic age for an ignimbrite of the Ouarzazate Series in the cover sequence. The age of interbedded felsic metatuff in the metasedimentary and metavolcanic sequence of the basement schists is 2072 ?? 8 Ma. This date represents: (1) the first reliable age from the metasedimentary and metavolcanic sequence; (2) the oldest reliable age for the basement of the Anti-Atlas; (3) the first date on the timing of deposition of the sediments on the northern edge of the Paleoproterozoic West African craton; (4) a lower age limit on deformation during the Eburnean orogeny; and (5) the first date obtained from the non-granitic Paleoproterozoic basement of Morocco. Ages of 2046 ?? 7 Ma (Targant granite) and 2041 ?? 6 Ma (Oudad granite) support earlier interpretations of a Paleoproterozoic Eburnean igneous event in the Anti-Atlas. The granites post-date the Eburnean D1 deformation event in the Paleoproterozoic schist sequence, and place a ???2046 Ma limit on short-lived Eburnean deformation in the area. Cross-cutting metadolerite is 2040 ?? 6 Ma; this is the first date from a metadolerite in the western Anti-Atlas. All of the dolerites in the area post-date emplacement of the two granites and the new age constrains the onset of late- or post-Eburnean extension. Ignimbrite of the Ouarzazate Series, immediately above the Paleoproterozoic basement is 565 ?? 7 Ma. This Neoproterozoic age agrees with ages of similar volcanic rocks elsewhere from the Ouarzazate Series. The date also agrees with the ages of associated hypabyssal intrusions, and marks the second and final stage of Pan-African orogenic activity in the western Anti-Atlas. ?? 2002 Elsevier Science B.V. All rights reserved.

  17. Fluctuations in late Neoproterozoic atmospheric oxidation - Cr isotope chemostratigraphy and iron speciation of the late Ediacaran lower Arroyo del Soldado Group (Uruguay)

    DEFF Research Database (Denmark)

    Frei, Robert; Gaucher, Claudio; Stolper, Daniel

    2013-01-01

    . Neodymium isotopes reveal that these oxygenation pulses were followed by increased influxes to the basin of continental crust-derived detrital components of Paleoproterozoic (Nd T-DM model ages=2.1-2.2 Ga) provenance typical of the Rio de la Plata Craton. The association of positive delta Cr-53-ferruginous...

  18. Signification des ferruginisations des formations néoprotérozoïques du Nord-Burkina Faso (Afrique de l'Ouest)Meaning of ironstones in the sedimentary Neoproterozoic formations of the northern Burkina Faso (western Africa)

    Science.gov (United States)

    Blot, Alain

    2002-09-01

    There are many small ferruginous outcrops of different facies, often breccia-like, in the Neoproterozoic sedimentary formations in northern Burkina. These outcrops are made up of goethite and quartz, and are often along with high grades of various elements. It could be a question of gossans. Their large distribution in this part of the Taoudéni Basin offers it prospects as a province geochemically rich in Cu, Pb, Zn, Mo, As, Cd, Co... This basin would be a geochemical bin for ancient formations, which would have been evacuated before the Neoproterozoic. The ironstones would be the mark of further concentrations. To cite this article: A. Blot, C. R. Geoscience 334 (2002) 909-915.

  19. Neoproterozoic fragmentation of the Scottish Sector of Laurentia - an ancient analogue for the Iberian and UK/Irish ocean-continent transition zones

    Science.gov (United States)

    Leslie, G.; Krabbendam, M.

    2009-04-01

    The Neoproterozoic Dalradian Supergroup of Scotland and Ireland is intensively deformed and metamorphosed by mid-Ordovician arc-accretion (c. 460 Ma) during the Caledonian Orogeny. Emplacement of an extensive suite of Siluro-Devonian Caledonian granitoids further complicates reading the sedimentary record. Nevertheless we can determine a history of stretching and break-up affecting the Neoproterozoic supercontinent of Rodinia and leading to creation of the Iapetus Ocean. Three key intervals of late-Neoproterozoic sediment accumulation are recognised - new geological mapping, isotopic datasets (Sr, O and C, U/Pb zircon, Sm/Nd WR), and sequence stratigraphical approaches are refining constraints on the lithostratigraphical architecture and basin evolution of the Dalradian Supergroup. Thick siliciclastic deposits accumulated (pre-800 Ma?) during an early stretching phase (distributed high angle faulting) that led to crustal thinning (low angle shearing). Three major limestone - pelite - quartzite depositional cycles succeeded these earlier siliciclastic deposits, recording episodic subsidence in an intracratonic but largely marine environment; the second cycle overlaps the late Precambrian (Cryogenian) glaciation and concludes with the distinctive Marinoan tillite succession (c. 635Ma). The last of the three cycles is terminated, in some parts of the Dalradian, by deposition of serpentinitic muds and conglomerates and volcaniclastic sediments; pods and lenses of both massive and serpentinised ultramafic rock also interrupt the sedimentary record at this level (thus possibly indicating mantle exhumation). In other areas, a major part of the ‘type' Dalradian succession is absent and we now recognise a major overstep unconformity at this level. From this level onwards across the Dalradian, rapid foundering of the margin, and the transition from rift- to drift-dominated processes, resulted in an overstepping accumulation of laterally and vertically variable

  20. Structural controls on Neoproterozoic mineralization in the South Eastern Desert, Egypt: an integrated field, Landsat TM, and SIR-C/X SAR approach

    Science.gov (United States)

    Kusky, Timothy M.; Ramadan, Talaat M.

    2002-07-01

    The Arabian-Nubian Shield represents a complex amalgam of arcs and microcontinents assembled during Neoproterozoic closure of the Mozambique Ocean. The 750-720 Ma Allaqi suture is an arc/arc collision zone, formed when the Gerf terrane in the north overrode the circa 830-720 Ma Gabgaba terrane in the south, prior to closure of the Mozambique Ocean. Neoproterozoic rocks include ophiolitic ultramafic-mafic rocks, metasediments, intermediate metavolcanic rocks, intrusive gabbro-diorite rocks, granodiorites, biotite granites, and leucocratic granites. High-pressure/low-temperature metamorphism has been documented in rocks of the suture zone. Mineral deposits include nickel-copper-platinum and podiform chromite in ultramafic rocks, marble, gold-bearing quartz-veins in D 2 and D 3 shear zones, and radioactive mineralization associated with late leucocratic granitic rocks. Integrated field mapping and remote sensing techniques are used to distinguish and map the relationships between rock units, structures, and alteration zones associated with mineral deposits along the Allaqi suture of Egypt's SE Desert. Landsat TM images processed using a band ratioing technique show different rock types remarkably well, and are able to distinguish between alteration zones associated with ultramafic rocks (listwaenites) and those associated with leucocratic granitic rocks (greisenization, silicification and albitization). Black and white L-band SIR-C/X SAR images outline foliations, faults and folds that control mineralization at several deposits in the area, whereas color composite multiband Chh-Lhh-Lhv SIR-C/X SAR images reveal some elliptical granitic bodies that host radioactive mineralization. E-trending, tight to isoclinal, gently dipping folds, thrust faults and subvertical shear zones related to the Allaqi suture are overprinted by N-oriented structures related to the Wadi Ungate shear zone, formed during collision of east and west Gondwana during closure of the Mozambique Ocean

  1. Deeply concealed half-graben at the SW margin of the East European Craton (SE Poland — Evidence for Neoproterozoic rifting prior to the break-up of Rodinia

    Directory of Open Access Journals (Sweden)

    P. Krzywiec

    2018-01-01

    Full Text Available Baltica was one of continents formed as a result of Rodinia break-up 850–550 Ma. It was separated from Amazonia(? by the Tornquist Ocean, the opening of which was preceded by Neoproterozoic extension in a network of continental rifts. Some of these rifts were subsequently aborted whereas the Tornquist Rift gave rise to splitting of Rodinia and formation of the Tornquist Ocean. The results of 1-D subsidence analysis at the fossil passive margin of Baltica provided insight in the timing and kinematics of continental rifting that led to break-up of Rodinia. Rifting was associated with Neoproterozoic syn-rift subsidence accompanied by deposition of continental coarse-grained sediments and emplacement of continental basalts. Transition from a syn-rift to post-rift phase in the latest Ediacaran to earliest early Cambrian was concomitant with deposition of continental conglomerates and arkoses, laterally passing into mudstones. An extensional scenario of the break-up of Rodinia along the Tornquist Rift is based on the character of tectonic subsidence curves, evolution of syn-rift and post-rift depocenters in time, as well as geochemistry and geochronology of the syn-rift volcanics. It is additionally reinforced by the high-quality deep seismic reflection data from SE Poland, located above the SW edge of the East European Craton. The seismic data allowed for identification of a deeply buried (11–18 km, well-preserved extensional half-graben, developed in the Palaeoproterozoic crystalline basement and filled with a Neoproterozoic syn-rift volcano-sedimentary succession. The results of depth-to-basement study based on integration of seismic and gravity data show the distribution of local NE–SW elongated Neoproterozoic depocenters within the SW slope of the East European Craton. Furthermore, they document the rapid south-eastwards thickness increase of the Neoproterozoic succession towards the NW–SE oriented craton margin. This provides evidence

  2. The kinematic evolution of the Serra Central Salient, Eastern Brazil: A Neoproterozoic progressive arc in northern Espinhaço fold-thrust belt

    Science.gov (United States)

    Bersan, Samuel Moreira; Danderfer, André; Lagoeiro, Leonardo; Costa, Alice Fernanda de Oliveira

    2017-12-01

    Convex-to-the-foreland map-view curves are common features in fold-thrust belts around cratonic areas. These features are easily identifiable in belts composed of supracrustal rocks but have been rarely described in rocks from relatively deeper crustal levels where plastic deformation mechanisms stand out. Several local salients have been described in Neoproterozoic marginal fold-thrust belts around the São Francisco craton. In the northern part of the Espinhaço fold-thrust belt, which borders the eastern portion of the São Francisco craton, both Archean-Paleoproterozoic basement rocks and Proterozoic cover rocks are involved in the so-called Serra Central salient. A combination of conventional structural analysis and microstructural and paleostress studies were conducted to characterize the kinematic and the overall architecture and processes involved in the generation of this salient. The results allowed us to determine that the deformation along the Serra Central salient occur under low-grade metamorphic conditions and was related to a gently oblique convergence with westward mass transport that developed in a confined flow, controlled by two transverse bounding shear zones. We propose that the Serra Central salient nucleates as a basin-controlled primary arc that evolves to a progressive arc with secondary vertical axis rotation. This secondary rotation, well-illustrated by the presence of two almost orthogonal families of folds, was dominantly controlled by buttress effect exert by a basement high located in the foreland of the Serra Central salient.

  3. 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)

  4. Neoproterozoic Evolution and Najd‒Related Transpressive Shear Deformations Along Nugrus Shear Zone, South Eastern Desert, Egypt (Implications from Field‒Structural Data and AMS‒Technique)

    Science.gov (United States)

    Hagag, W.; Moustafa, R.; Hamimi, Z.

    2018-01-01

    The tectonometamorphic evolution of Nugrus Shear Zone (NSZ) in the south Eastern Desert of Egypt was reevaluated through an integrated study including field-structural work and magnetofabric analysis using Anisotropy of Magnetic Susceptibility (AMS) technique, complemented by detailed microstructural investigation. Several lines of evidence indicate that the Neoproterozoic juvenile crust within this high strain zone suffered an impressive tectonic event of left-lateral transpressional regime, transposed the majority of the earlier formed structures into a NNW to NW-directed wrench corridor depicts the northwestern extension of the Najd Shear System (NSS) along the Eastern Desert of Egypt. The core of the southern Hafafit dome underwent a high metamorphic event ( M 1) developed during the end of the main collisional orogeny in the Arabian-Nubian Shield (ANS). The subsequent M 2 metamorphic event was retrogressive and depicts the tectonic evolution and exhumation of the Nugrus-Hafafit area including the Hafafit gneissic domes, during the origination of the left-lateral transpressive wrench corridor of the NSS. The early tectonic fabric within the NSZ and associated highly deformed rocks was successfully detected by the integration of AMS-technique and microstructural observations. Such fabric grain was checked through a field-structural work. The outcomes of the present contribution advocate a complex tectonic evolution with successive and overlapped deformation events for the NSZ.

  5. The evolution of Neoproterozoic magmatism in Southernmost Brazil: shoshonitic, high-K tholeiitic and silica-saturated, sodic alkaline volcanism in post-collisional basins

    Directory of Open Access Journals (Sweden)

    Sommer Carlos A.

    2006-01-01

    Full Text Available The Neoproterozoic shoshonitic and mildly alkaline bimodal volcanism of Southernmost Brazil is represented by rock assemblages associated to sedimentary successions, deposited in strike-slip basins formed at the post-collisional stages of the Brasilian/Pan-African orogenic cycle. The best-preserved volcano sedimentary associations occur in the Camaquã and Campo Alegre Basins, respectively in the Sul-riograndense and Catarinense Shields and are outside the main shear belts or overlying the unaffected basement areas. These basins are characterized by alternation of volcanic cycles and siliciclastic sedimentation developed dominantly on a continental setting under subaerial conditions. This volcanism and the coeval plutonism evolved from high-K tholeiitic and calc-alkaline to shoshonitic and ended with a silica-saturated sodic alkaline magmatism, and its evolution were developed during at least 60 Ma. The compositional variation and evolution of post-collisional magmatism in southern Brazil are interpreted as the result mainly of melting of a heterogeneous mantle source, which includes garnet-phlogopite-bearing peridotites, veined-peridotites with abundant hydrated phases, such as amphibole, apatite and phlogopite, and eventually with the addition of an asthenospheric component. The subduction-related metasomatic character of post-collisional magmatism mantle sources in southern Brazil is put in evidence by Nb-negative anomalies and isotope features typical of EM1 sources.

  6. North Qinling Terrain as a provenance of Kuanping Group: LA-ICP-MS U-Pb Geochronology of detrital zircons

    Science.gov (United States)

    Hu, B.; Li, S.; Zhai, M.; Wu, J.; Jia, X.

    2017-12-01

    Though some Neoproterozoic S-type granites in the North Qinling Terrain (NQT), China indicate the collision between the NQT and an unknown block, there are still controversial. The LA-ICP-MS U-Pb ages of detrital zircons of meta-sandstones from the Kuanping Group in Luonan area, NQT, provide sedimentology evidence to prove that the NQT and an unknown block from Rodinia supercontinent have been collided during Meso-Neoproterozoic. The U-Pb ages of detrital zircons from the Kuanping Group show that the main age peaks are at 2.58 Ga, 2.46 Ga, 2.0 Ga, 1.78 Ga, 1.6 Ga, 1.45 Ga and 1.27 Ga. The youngest age of 880 Ma indicates that the sedimentary age of the Kuanping Group is less than 880 Ma. The provenances, which provide 1.45 - 0.88 Ga sediments may come from NQT, which magmatic and metamorphic rocks during this period outcropped. Whereas provenances providing 2.6- 1.6 Ga sediments may come from an unknown block. This indicates that the Kuangping Group received both NQT and the unknown block materials. Therefore, the NQT and the unknown block may have collided before 880 Ma. 889 - 848 Ma A-type granites distributing the NQT was considered forming under a post-collisional tectonics. According the youngest detrital zircon ages of 880 Ma, it is inferred that the Kuanping Basin may also form in the same tectonic environments. Neoproterozoic Kuanping basin and 889 - 848 Ma A-type granites may be a result which NQT broken off a block of Rodinia supercontinent. Acknowledgments: This research is supported by National Key Research and Development Plan of China (2016YFC0601002), Special Fund for Basic Scientific Research of Central Colleges, Chang'an University (310827172201, 0009-2014G1271067) and National Nature Science Foundation of China (41402042).

  7. The metamorphic basement of the southern Sierra de Aconquija, Eastern Sierras Pampeanas: Provenance and tectonic setting of a Neoproterozoic back-arc basin

    Science.gov (United States)

    Cisterna, Clara Eugenia; Altenberger, Uwe; Mon, Ricardo; Günter, Christina; Gutiérrez, Antonio

    2018-03-01

    The Eastern Sierras Pampeanas are mainly composed of Neoproterozoic-early Palaeozoic metamorphic complexes whose protoliths were sedimentary sequences deposited along the western margin of Gondwana. South of the Sierra de Aconquija, Eastern Sierras Pampeanas, a voluminous metamorphic complex crops out. It is mainly composed of schists, gneisses, marbles, calk-silicate schists, thin layers of amphibolites intercalated with the marbles and granitic veins. The new data correlate the Sierra de Aconquija with others metamorphic units that crop out to the south, at the middle portion of the Sierra de Ancasti. Bulk rock composition reflects originally shales, iron rich shales, wackes, minor litharenites and impure limestones as its protoliths. Moreover, comparisons with the northern Sierra de Aconquija and from La Majada (Sierra de Ancasti) show similar composition. Amphibolites have a basaltic precursor, like those from the La Majada (Sierra de Ancasti) ones. The analyzed metamorphic sequence reflects low to moderate weathering conditions in the sediments source environment and their chemical composition would be mainly controlled by the tectonic setting of the sedimentary basin rather than by the secondary sorting and reworking of older deposits. The sediments composition reveal relatively low maturity, nevertheless the Fe - shale and the litharenite show a tendency of minor maturity among them. The source is related to an acid one for the litharenite protolith and a more basic to intermediate for the other rocks, suggesting a main derivation from intermediate to felsic orogen. The source of the Fe-shales may be related to and admixture of the sediments with basic components. Overall the composition point to an upper continental crust as the dominant sediment source for most of the metasedimentary rocks. The protolith of the amphibolites have basic precursors, related to an evolving back-arc basin. The chemical data in combination with the specific sediment association

  8. Replacement of benthic communities in two Neoproterozoic-Cambrian subtropical-to-temperate rift basins, High Atlas and Anti-Atlas, Morocco

    Science.gov (United States)

    Clausen, Sébastien; Álvaro, J. Javier; Zamora, Samuel

    2014-10-01

    The ‘Cambrian explosion’ is often introduced as a major shift in benthic marine communities with a coeval decline of microbial consortia related to the diversification of metazoans and development of bioturbation (‘Agronomic Revolution’). Successive community replacements have been reported along with ecosystem diversification and increase in guild complexity from Neoproterozoic to Cambrian times. This process is recorded worldwide but with regional diachroneities, some of them directly controlled by the geodynamic conditions of sedimentary basins. The southern High Atlas and Anti-Atlas of Morocco record development of two rifts, Tonian (?) - early Cryogenian and latest Ediacarian-Cambrian in age, separated by the onset of the Pan-African Orogeny. This tectonically controlled, regional geodynamic change played a primary control on pattern and timing of benthic ecosystem replacements. Benthic communities include microbial consortia, archaeocyathan-thromboid reefal complexes, chancelloriid-echinoderm-sponge meadows, and deeper offshore echinoderm-dominated communities. Microbial consortia appeared in deeper parts of the Tonian (?) - early Cryogenian fluvio-deltaic progradational rift sequences, lacustrine environments of the Ediacaran Volcanic Atlasic Chain (Ouarzazate Supergroup) and the Ediacaran-Cambrian boundary interval, characterized by the peritidal-dominated Tifnout Member (Adoudou Formation). They persisted and were largely significant until Cambrian Age 3, as previous restricted marine conditions precluded the immigration of shelly metazoans in the relatively shallow epeiric parts of the Cambrian Atlas Rift. Successive Cambrian benthic communities were replaced as a result of distinct hydrodynamic and substrate conditions, which allow identification of biotic (e.g., antagonistic relationships between microbial consortia and echinoderms, and taphonomic feedback patterns in chancelloriid-echinoderm-sponge meadows) and abiotic (e.g., rifting

  9. Petrology and SHRIMP zircon geochronology of granulites from Vesleknausen, Lützow-Holm Complex, East Antarctica: Neoarchean magmatism and Neoproterozoic high-grade metamorphism

    Directory of Open Access Journals (Sweden)

    Toshiaki Tsunogae

    2014-03-01

    Full Text Available We report new petrological data and geochronological measurements of granulites from Vesleknausen in the highest-grade section of the Lützow-Holm Complex, part of the Gondwana-assembling collisional orogen in East Antarctica. The locality is dominated by felsic to intermediate orthogneiss (charnockite and minor biotite gneiss, mafic orthogneiss, and hornblende-pyroxene granulite, with deformed and undeformed dykes of metagranite and felsic pegmatite. Pseudosection analysis of charnockite in the system NCKFMASHTO, supported by geothermometry of mafic orthogneiss, was used to infer peak metamorphic temperatures of 750–850 °C, approximately 150 °C lower than those estimated for metasedimentary gneisses from Rundvågshetta, 6 km to the northeast. SHRIMP U-Pb analysis of zircons from feldspar-pyroxene gneiss, which corresponds to a partially molten patch around mafic orthogneiss, yielded a Concordia upper intercept ages of 2507.9 ± 7.4 Ma, corresponding to the time of formation of the magmatic protolith to the orthogneiss. Partial melting during peak metamorphism probably took place between 591 and 548 Ma, as recorded in rims overgrew around magmatic zircon. Our results suggest that Rundvågshetta-Vesleknausen-Strandnibba region in southwestern Lützow-Holm Bay, where orthogneisses are dominant, consists of a single crustal block, possibly formed by ca. 2.5 Ga arc magmatism. The Neoarchean magmatic terrane was tectonically mingled with other fragments (such as metasedimentary units in northern Lützow-Holm Bay by subduction/collision events during the assembly of Gondwana supercontinent, and subsequently underwent ∼850 °C granulite-facies metamorphosed during Neoproterozoic to Cambrian final collisional event.

  10. Composition, age, and origin of the ~620 Ma Humr Akarim and Humrat Mukbid A-type granites: no evidence for pre-Neoproterozoic basement in the Eastern Desert, Egypt

    Science.gov (United States)

    Ali, Kamal A.; Moghazi, Abdel-Kader M.; Maurice, Ayman E.; Omar, Sayed A.; Wang, Qiang; Wilde, Simon A.; Moussa, Ewais M.; Manton, William I.; Stern, Robert J.

    2012-10-01

    The Humr Akarim and Humrat Mukbid plutons, in the central Eastern Desert of Egypt, are late Neoproterozoic post-collisional alkaline A-type granites. Humr Akarim and Humrat Mukbid plutonic rocks consist of subsolvus alkali granites and a subordinate roof facies of albite granite, which hosts greisen and Sn-Mo-mineralized quartz veins; textural and field evidence strongly suggest the presence of late magmatic F-rich fluids. The granites are Si-alkali rich, Mg-Ca-Ti poor with high Rb/Sr (20-123), and low K/Rb (27-65). They are enriched in high field strength elements (e.g., Nb, Ta, Zr, Y, U, Th) and heavy rare earth elements (La n /Yb n = 0.27-0.95) and exhibit significant tetrad effects in REE patterns. These geochemical attributes indicate that granite trace element distribution was controlled by crystal fractionation as well as interaction with fluorine-rich magmatic fluids. U-Pb SHRIMP zircon dating indicates an age of ~630-620 Ma but with abundant evidence that zircons were affected by late corrosive fluids (e.g., discordance, high common Pb). ɛNd at 620 Ma ranges from +3.4 to +6.8 (mean = +5.0) for Humr Akarim granitic rocks and from +4.8 to +7.5 (mean = +5.8) for Humrat Mukbid granitic rocks. Some slightly older zircons (~740 Ma, 703 Ma) may have been inherited from older granites in the region. Our U-Pb zircon data and Nd isotope results indicate a juvenile magma source of Neoproterozoic age like that responsible for forming most other ANS crust and refute previous conclusions that pre-Neoproterozoic continental crust was involved in the generation of the studied granites.

  11. Deeply concealed half-graben at the SW margin of the East European Craton (SE Poland) — Evidence for Neoproterozoic rifting prior to the break-up of Rodinia

    OpenAIRE

    P. Krzywiec; P. Poprawa; M. Mikołajczak; S. Mazur; M. Malinowski

    2018-01-01

    Baltica was one of continents formed as a result of Rodinia break-up 850–550 Ma. It was separated from Amazonia(?) by the Tornquist Ocean, the opening of which was preceded by Neoproterozoic extension in a network of continental rifts. Some of these rifts were subsequently aborted whereas the Tornquist Rift gave rise to splitting of Rodinia and formation of the Tornquist Ocean. The results of 1-D subsidence analysis at the fossil passive margin of Baltica provided insight in the timing and ki...

  12. Relationship between Precambrian North Korean Peninsula and the North China Craton: Evidence from LA-ICP-MS U-Pb ages of detrital zircons from Neoproterozoic tillites of North Korea and Southern North China Craton

    Science.gov (United States)

    Hu, B.; Zhai, M.; Peng, P.; Zhang, Y.; Wu, J.; Jia, X.; Zhang, H.; Lei, W.; Zhuang, G.

    2016-12-01

    Relationship between Precambrian Korean Peninsula and the North China Craton (NCC) is focus of attention. There are Neoproterozoic tillites in Phyongnam Basin, Nangrim massif, North Korea (NK) and Southern NCC. Nangrim massif was regarded as a part of the NCC according to similar Precambrian basements between Nangrim massif and Longgang massif in the Northeast NCC. But the comparation of Neoproterozoic rocks is lacked between NK and NCC. Detrital zircon LA-ICP-MS U-Pb ages of 2 pebbly phyllite samples of Pirangdong Series in Phyongnam Basin and 2 argillaceous cemented mix-conglomeate samples of Luoquan Series in Southern NCC was analyzed in this research. Detrital zircon ages of pebbly phyllites of Pirangdong Series distribute mainly at 1.85 Ga, 1.8 Ga, 1.6 Ga, 1.4 Ga and 1.2 Ga. A small number of them are at 3.2 Ga, 2.6 - 2.5 Ga, 2.3 Ga, 2.1 Ga and 900 - 860 Ma. Detrital zircon ages of mix-conglomeates of Luoquan Series mainly focus on 2.5 Ga, 2.2 Ga, 2.0 Ga, 1.8 Ga and 1.6 Ga. Minor of them distribute at 1.12 Ga. The similar age distribution of Pirangdong and Luoquan Series of 2.6 - 2.5 Ga, 2.1 - 2.0 Ga, 1.85 - 1.8 Ga and 1.6 Ga corresponds to Precambrian significant tectonic- magmatic- thermal events of the NCC, which indicates that the Precambrian basement rocks of the NCC are main provenances of both Pirangdong and Luoquan Series. This also confirm that the Phyongnam Basin is a part of Neoproterozoic sedimentary covers of the NCC. It is worth to mention that 1.2 - 1.0 Ga and 900 - 850 Ma magmatic rocks in the NCC are seldom reported which relate to the assemblage and breakup of Rodinia Supercontinent. whereas they crop out widely in the South China Craton (SCC) and was always regarded as a mark distingusing the two craton. 1.2 - 1.0 Ga and 900 - 850 Ma zircon ages preserved in sedimentary rocks not only in North Korea and Southern NCC but also in Northeast NCC and East NCC provide data to compare Neoproterozoic strata between NCC and SCC and important clues to

  13. Reevaluating the age of the Walden Creek Group and the kinematic evolution of the western Blue Ridge, southern Appalachians

    Science.gov (United States)

    Thigpen, J. Ryan; Hatcher, Robert D.; Kah, Linda C.; Repetski, John E.

    2016-01-01

    An integrated synthesis of existing datasets (detailed geologic mapping, geochronologic, paleontologic, geophysical) with new paleontologic and geochemical investigations of rocks previously interpreted as part of the Neoproterozoic Walden Creek Group in southeastern Tennessee suggest a necessary reevaluation of the kinematics and structural architecture of the Blue Ridge Foothills. The western Blue Ridge of Tennessee, North Carolina, and Georgia is composed of numerous northwest-directed early and late Paleozoic thrust sheets, which record pronounced variation in stratigraphic/structural architecture and timing of metamorphism. The detailed spatial, temporal, and kinematic relationships of these rocks have remained controversial. Two fault blocks that are structurally isolated between the Great Smoky and Miller Cove-Greenbrier thrust sheets, here designated the Maggies Mill and Citico thrust sheets, contain Late Ordovician-Devonian conodonts and stable isotope chemostratigraphic signatures consistent with a mid-Paleozoic age. Geochemical and paleontological analyses of Walden Creek Group rocks northwest and southeast of these two thrust sheets, however, are more consistent with a Late Neoproterozoic (550–545 Ma) depositional age. Consequently, the structural juxtaposition of mid-Paleozoic rocks within a demonstrably Neoproterozoic-Cambrian succession between the Great Smoky and Miller Cove-Greenbrier thrust sheets suggests that a simple foreland-propagating thrust sequence model is not applicable in the Blue Ridge Foothills. We propose that these younger rocks were deposited landward of the Ocoee Supergroup, and were subsequently plucked from the Great Smoky fault footwall as a horse, and breached through the Great Smoky thrust sheet during Alleghanian emplacement of that structure.

  14. New aeromagnetic data of eastern Dronning Maud Land: implications for the spatial extent of a major Early Neoproterozoic juvenile crustal province

    Science.gov (United States)

    Ruppel, A. S.; Jacobs, J.; Eagles, G.; Läufer, A.; Jokat, W.

    2017-12-01

    A long-standing collaboration between Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) and the Federal Institute for Geosciences and Natural Resources (BGR) aims to investigate the sub-ice crustal architecture and tectonic evolution of East Antarctica. Its main emphasis is on Dronning Maud Land (DML). During the austral summers 2014 and 2015, ca. 40.000 line kilometre of new magnetic, gravity and ice-penetrating radar data were collected with 10 km line spacing. Here, we report on magnetic anomaly data to the east and south of Sør Rondane (eastern DML), analysed with several filtering techniques. These data are integrated with exposure information from Sør Rondane, the Belgica Mts., and the Yamato Mts.. The study area covers the eastern part of a major, recently revealed Early Neoproterozoic juvenile crustal block, the Tonian Oceanic Arc Super Terrane (TOAST). The western extent of the TOAST is well defined by the Forster Magnetic Anomaly and characterized by a province of subdued SE-striking parallel positive magnetic anomalies in the mostly ice-covered region of south-eastern DML (the SE DML province). Geological investigations showed that this area can be correlated with exposures in Sør Rondane and scattered nunataks west of it. U-Pb ages of ca. 1000-900 Ma, are documented from zircons of gabbro-trondhjemite-tonalite-granodiorite (GTTG) suites in both areas. Further, geochemical analyses prove a juvenile character of the GTTGs, which are interpreted as oceanic arc complexes. Glacial drift from southern Sør Rondane points to an inland continuation of the TOAST, so far of unknown dimensions. The new magnetic data constrain the southern and eastern minimum extent of the TOAST, which we think has a minimum area of 450.000 km2. The spatial extent of this major juvenile crustal province has major significance for the tectonic reconstruction of East Antarctica and its involvement in Rodinia since it is suggested having evolved

  15. Neoproterozoic A-type granitoids of the central and southern Appalachians: Intraplate magmatism associated with episodic rifting of the Rodinian supercontinent

    Science.gov (United States)

    Tollo, R.P.; Aleinikoff, J.N.; Bartholomew, M.J.; Rankin, D.W.

    2004-01-01

    Emplacement of compositionally distinctive granitic plutons accompanied two pulses (765-680 and 620-550Ma) of crustal extension that affected the Rodinian craton at the present location of the central Appalachians during the Neoproterozoic. The dominantly metaluminous plutons display mineralogical and geochemical characteristics of A-type granites including high FeO t/MgO ratios, high abundances of Nb, Zr, Y, Ta, and REE (except Eu), and low concentrations of Sc, Ba, Sr, and Eu. These dike-like, sheet complexes occur throughout the Blue Ridge province of Virginia and North Carolina, and were emplaced at shallow levels in continental crust during active extension, forming locally multiple-intrusive plutons elongated perpendicular to the axis of extension. New U-Pb zircon ages obtained from the Polly Wright Cove (706??4Ma) and Suck Mountain (680??4Ma) plutons indicate that metaluminous magmas continued to be replenished near the end of the first pulse of rifting. The Suck Mountain body is presently the youngest known igneous body associated with earlier rifting. U-Pb zircon ages for the Pound Ridge Granite Gneiss (562??5Ma) and Yonkers Gneiss (563??2Ma) in the Manhattan prong of southeastern New York constitute the first evidence of plutonic felsic activity associated with the later period of rifting in the U.S. Appalachians, and suggest that similar melt-generation processes were operative during both intervals of crustal extension. Fractionation processes involving primary minerals were responsible for much of the compositional variation within individual plutons. Compositions of mapped lithologic units in a subset of plutons studied in detail define overlapping data arrays, indicating that, throughout the province, similar petrologic processes operated locally on magmas that became successively more chemically evolved. Limited variation in source-sensitive Y/Nb and Yb/Ta ratios is consistent with results of melting experiments and indicates that metaluminous

  16. Neoproterozoic anorogenic magmatism in the Southern Bahia Alkaline Province of NE Brazil: U-Pb and Pb-Pb ages of the blue sodalite syenites

    Science.gov (United States)

    Rosa, Maria de Lourdes da Silva; Conceição, Herbet; Macambira, Moacir José Buenano; Galarza, Marco Antonio; Cunha, Mônica Pringsheim; Menezes, Rita Cunha Leal; Marinho, Moacyr Moura; Filho, Basílio Elesbão da Cruz; Rios, Débora Correia

    2007-08-01

    Blue sodalite syenite is a rare rock, and the Southern Bahia Alkaline Province (SBAP) is the only place in Brazil where economic deposits are found. This province forms part of the Archaean to Paleoproterozoic São Francisco craton, and contains a few batholiths, a large number of stocks and hundreds of dykes. Its southern part lies close to the tectonic contact between the craton and the Neoproterozoic Araçuaí mobile melt. Blue sodalite-bearing syenites are found in almost all the igneous bodies of the SBAP as dykes or pegmatitic masses hosted by nepheline syenite. Economically viable quantities for the production of dimension stones are found only in the Floresta Azul alkaline complex, the Itaju do Colônia and Rio Pardo stocks and the Itarantim batholith.U-Pb ages obtained for titanite from Itaju do Colônia (732 ± 8 Ma) and Rio Pardo (714 ± 8) and Pb-Pb evaporation ages of zircon from Floresta Azul (696 ± 3 Ma) and Itarantim (722 ± 5 Ma). The geochronology of the SBAP shows that the anorogenic alkaline magmatism persisted for at least 58 Ma, demonstrating an extensional tectonic environment in the southern part of the São Francisco craton at this time. The data show that the rift phase which preceded the formation of the Araçuaí orogen was active until at least 700 Ma. The reported ages are similar to those found for the nepheline syenite host bodies, which supports the conclusions of the previous petrologic study demonstrating that blue sodalite is formed during the crystallization of these bodies. Two different processes are involved. In the magmatic process, sodalite occurs as disseminated and interstitial crystals among alkali feldspar crystals, and is associated with calcite and cancrinite formed by destabilization of nepheline. In the metasomatic process, discontinuous bands of sodalite are in sharp contact with nepheline syenite pegmatite, and its crystal aggregates often contain relict textures of nepheline and albite been replaced by sodalite.

  17. Late Neoproterozoic layered mafic intrusion of arc-affinity in the Arabian-Nubian Shield: A case study from the Shahira layered mafic intrusion, southern Sinai, Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Azer, M.K.; Obeid, M.A.; Gahalan, H.A.

    2016-07-01

    The Shahira Layered Mafic Intrusion (SLMI), which belongs to the late Neoproterozoic plutonic rocks of the Arabian-Nubian Shield, is the largest layered mafic intrusion in southern Sinai. Field relations indicate that it is younger than the surrounding metamorphic rocks and older than the post-orogenic granites. Based on variation in mineral paragenesis and chemical composition, the SLMI is distinguished into pyroxene-hornblende gabbro, hornblende gabbro and diorite lithologies. The outer zone of the mafic intrusion is characterized by fine-grained rocks (chilled margin gabbroic facies), with typical subophitic and/or microgranular textures. Different rock units from the mafic intrusion show gradational boundaries in between. They show some indications of low grade metamorphism, where primary minerals are transformed into secondary ones. Geochemically, the Shahira layered mafic intrusion is characterized by enrichment in LILE relative to HFSE (e.g. Nb, P, Zr, Ti, Y), and LREE relative to HREE [(La/Lu)n= 4.75–8.58], with subalkaline characters. It has geochemical characteristics of pre-collisional arc-type environment. The geochemical signature of the investigated gabbros indicates partial melting of mantle wedge in a volcanic-arc setting, being followed by fractional crystallization and crustal contamination. Fractional crystallization processes played a vital role during emplacement of the Shahira intrusion and evolution of its mafic and intermediate rock units. The initial magma was evolved through crystallization of hornblende which was caused by slight increasing of H2O in the magma after crystallization of liquidus olivine, pyroxene and Ca-rich plagioclase. The gabbroic rocks crystallized at pressures between 4.5 and 6.9kbar (~15–20km depth). Whereas, the diorites yielded the lowest crystallization pressure between 1.0 to 4.4Kbar (<10km depth). Temperature was estimated by several geothermometers, which yielded crystallization temperatures ranging from 835

  18. Timing of maturation of a Neoproterozoic oceanic arc during Pan-African Orogeny: the Asmlil complex (Anti-Atlas, South Morocco)

    Science.gov (United States)

    Triantafyllou, Antoine; Berger, Julien; Baele, Jean-Marc; Bruguier, Olivier; Diot, Hervé; Ennih, Nasser; Plissart, Gaëlle; Monnier, Christophe; Watlet, Arnaud; Vandycke, Sara

    2016-04-01

    Many intra-oceanic paleo-arcs are exposed in the Pan-African belt surrounding the West African Craton. In the Moroccan Anti-Atlas, remnants of Intra-Oceanic Subduction Zone (IOSZ) are preserved in few erosional windows moulded along the Anti-Atlas Major fault. These complexes highlight a Neoproterozoic paleo-suture made of 760 My back-arc ophiolites thrusted to the south onto a dismembered band of oceanic arc relics. The Asmlil arc complex, located in the southern part of the Bou Azzer inlier, is made of (i) 755 to 745 My- intermediate banded gneiss interpreted as metavolcanic products of a juvenile oceanic arc. This latter has been intruded by (ii) medium-grained hornblende-gabbro and dioritic magmas, in turn intruded by (iii) medium- to coarse grained hornblenditic-granodioritic decametric intrusions under sub-magmatic HT conditions. Hornblende-gabbros are made of garnet + amphibole/cpx relics + epidote + rutile paragenesis. Calculated pseudosections yielded P ~ 11-12 kbar for T ranging between 600 and 720°C for garnet growth. Measured Zr-in-rutile thermometer gave slightly higher temperature ranging between 710-790°C. On the field, garnet-rich leucocratic veinlets suggest that moderate partial melting of the mafic rock or localized dehydration reactions took place under garnet-granulite conditions (>800°C for hydrated chemical system). New geochronological data on garnet-bearing leucogabbros constrain their emplacement at 700 ±7 My (U-Pb zircon with low Th/U volcanic to subvolcanic massifs. Second event occurred around 700 My and results from mafic products intruding previous arc. A last event also dated at 660-650 My in the Sirwa window marks the emplacement of hot hornblenditic arc-magmas into older arc massifs during the tectonic extrusion of the arc section. This late event is also related to intense melt production at different level of the arc contributing to differentiation of the whole arc complex. We thus interpreted the Asmlil complex as the final

  19. W-Au skarns in the Neo-Proterozoic Seridó Mobile Belt, Borborema Province in northeastern Brazil: an overview with emphasis on the Bonfim deposit

    Science.gov (United States)

    Souza Neto, João Adauto; Legrand, Jean Michel; Volfinger, Marcel; Pascal, Marie-Lola; Sonnet, Philippe

    2008-02-01

    The Seridó Mobile Belt (SMB) is located in the Borborema Province in northeastern Brazil and consists of a gneiss basement (Archean to Paleo-Proterozoic), a metasedimentary sequence (marble, quartzites, and schists), and the Brasiliano igneous suite (both of Neo-Proterozoic age). In this region, skarns occur within marble and at the marble-schist contact in the metasedimentary sequence. Most of the skarn deposits have been discovered in the early 1940s, and since then, they have been exploited for tungsten and locally gold. Recently, the discovery of gold in the Bonfim tungsten skarn has resulted in a better understanding of the skarn mineralization in this region. The main characteristics of the SMB skarns are that they are dominantly oxidized tungsten skarns, with the exception of the Itajubatiba and Bonfim gold-bearing skarns, which are reduced based on pyrrhotite as the dominant sulfide, garnet with high almandine and spessartine component, and elevated gold contents. In the Bonfim deposit, pressure estimates indicate that the skarns formed at 10- to 15-km depth. The mineralized skarns present the prograde stage with almandine, diopside, anorthite, and actinolite-magnesio-hornblende, and titanite, apatite, allanite, zircon, and monazite as accessory minerals. The retrograde stage is characterized by alkali feldspar, clinozoisite-zoisite-sericite, calcite, and quartz. Scheelite occurs in four ore-shoots distributed within the marble and at the marble-schist contact. The main ore body is 5-120 cm wide and contains an average of 4.8-wt.% WO3, which occurs in the basal marble-schist contact. Fold hinges appear to control the location of high-grade scheelite. The late-stage gold mineralization contains bismite (Bi2O3), fluorine-bearing bismite, native bismuth, bismuthinite (Bi2S3), and joseite [Bi4(Te,S)3], and also chlorite, epidote, prehnite, chalcopyrite, and sphalerite. This gold-bismuth-tellurium mineralization exhibits a typical late character and occurs as a

  20. Extensional collapse in the Neoproterozoic Araçuaí orogen, eastern Brazil: a setting for reactivation of asymmetric crenulation cleavage

    Science.gov (United States)

    Marshak, Stephen; Alkmim, Fernando F.; Whittington, Alan; Pedrosa-Soares, Antônio Carlos

    2006-01-01

    The Araçuaí orogen of eastern Brazil is one of many Brasiliano/Pan African orogens formed during the Neoproterozoic assembly of Gondwana. Its western edge, bordering the São Francisco craton, is the Serra do Espinhaço fold-thrust belt, in which top-up-to-the-west (reverse-sense) faults, west-verging folds (F 1), and east-dipping spaced to phyllitic cleavage (S 1) developed. We have found that the kinematics of deformation changes markedly at the hinterland margin of this fold-thrust belt. Here, beneath a plateau known as the Chapada Acauã, metadiamictite and fine-grained pelitic schist comprise an east-dipping belt that contains an assemblage of structures indicative of top-down-to-the-east (normal-sense) shear. This assemblage includes a cascade of F 2 folds that refold F 1 folds and verge down the dip of the belt's enveloping surfaces, vertical tension gashes, and top-down-to-the-east rotated clasts. Based on the presence of these structures, we propose that the plateau exposes a regional-scale normal-sense shear zone, here called the Chapada Acauã shear zone (CASZ). Because F 2 folds refold F 1 folds, normal-sense shear in the CASZ occurred subsequent to initial west-verging thrusting. Considering this timing of motion in the CASZ, we suggest that the zone accommodated displacement of the internal zone of the Araçuaí orogen down, relative to its foreland fold-thrust belt, and thus played a role in extensional collapse of the orogen. The CASZ trends parallel to preserved thrusts to the west, and thus may represent an inverted thrust fault. Notably, throughout the CASZ, S 1 schistosity has been overprinted by a pervasive, west-dipping asymmetric crenulation cleavage (S 2). The sigmoid shape of S 1 surfaces in S 2 microlithons require that slip on each S 2 surface was top-down-to-the-west. S 2 cleavage is axial-planar to the down-dip verging F 2 folds. Based on its geometry, we suggest that S 2 cleavage initiated either as an antithetic extensional

  1. Mineral chemistry and geochemistry of the Late Neoproterozoic Gabal Abu Diab granitoids, Central Eastern Dessert, Egypt: Implications for the origin of rare metal post-orogenic A-type granites

    Science.gov (United States)

    Sami, Mabrouk; Ntaflos, Theodoros; Farahat, Esam S.; Ahmed, Awaad F.; Mohamed, Haroun A.

    2015-04-01

    The Neoproterozoic Gabal Abu Diab pluton is a part of the Arabian Nubian shield (ANS) continental crust and located in the Central Eastern Desert (CED) of Egypt. It constitutes multiphase granitic pluton intruded into granodiorite and metagabbro-diorite rocks with sharp and nonreactive contacts. Based on field observations, colors, structural variations and petrographic investigations, this granitic outcrop consists of an inner core of two-mica granite (TMG) followed outward by garnet bearing muscovite granite (GBMG) and albite granite (AG). Petrographical study indicated that medium to coarse-grained TMG is dominated by K-feldspar (Or88-98), quartz, plagioclase (albite, An0-7), muscovite and biotite with hypidiomorphic texture. With exception the appearance of garnet and the disappearance of biotite the GBMG resembles the TGM, while AG is leucocratic without any mafic mineral. The main accessories are zircon, Nb and Ta-bearing rutile, columbite, ilmenorutile, ilmenite, magnetite and apatite. This mineralogical similarity and the existence of columbite group minerals (CGM) in all granitoids, indicates a cogenetic relationship. Microprobe analyses reveal that, besides the CGM, rutile and ilmenite are the main repository phases for Nb-Ta-Ti. Columbite-(Mn) exists as individual subhedral crystals (up to 100μm in size) or intimate intergrowth with Nb-bearing rutile and/or ilmenite. The CGM are represented mostly by columbite-(Mn) with Ta/(Ta+Nb) and Mn/(Mn+Fe) ratio ranging from 0.02-0.08 and 0.4-0.9, respectively suggesting extreme degree of magmatic fractionation. Rutile contains significant amounts of Ta (up to 4 wt.% Ta2O5) and Nb (up to 22 wt.% Nb2O5). Biotites are phlogopite-annite in composition (Ann47-60Phlog40-53,on average) and are enriched with AlIV that characterize peraluminous granites. Garnets contain 60-69 mol.% spessartine and 28-36 mol.% almandine where, the ratio of spessartine and almandine together exceeds 95 mole percent, similar to garnet occur

  2. Detrital zircon U-Pb geochronology and whole-rock Nd-isotope constraints on sediment provenance in the Neoproterozoic Sergipano orogen, Brazil: From early passive margins to late foreland basins

    Science.gov (United States)

    Oliveira, E. P.; McNaughton, N. J.; Windley, B. F.; Carvalho, M. J.; Nascimento, R. S.

    2015-11-01

    SHRIMP U-Pb detrital zircon geochronology and depleted-mantle Nd-model ages of clastic rocks were combined to understand the sediment provenance in the Neoproterozoic Sergipano Belt. The Sergipano is the main orogenic belt between the Borborema province and the São Francisco Craton, eastern South America; it is divisible into several lithostratigraphic domains from North to South: Canindé, Poço Redondo-Marancó, Macururé, Vaza Barris, and Estância. Nd model ages (TDM) and detrital zircon U-Pb SHRIMP geochronology indicate that the protoliths of clastic metasedimentary rocks from the Marancó and Macururé domains were mostly derived from eroded late Mesoproterozoic to early Neoproterozoic rocks (1000-900 Ma), whereas detritus of similar rocks from the Canindé domain came from a younger source (ca. 700 Ma and 1000 Ma). Samples from the Vaza Barris domain show the greatest scatter of both TDM and zircon ages amongst all domains, but with important contributions from Proterozoic sources (690-1050 Ma and ca. 2100 Ma) and less from Archaean sources. The Estância domain samples have zircon population peaks at 570 Ma, 600 Ma, and 920-980 Ma, with a few older grains; one diamictite contains only ca. 2150 Ma zircon grains. Our preliminary results support a model in which sediments of the Marancó and Macururé domains were deposited on a continental margin of the ancient Borborema plate before its collision with the São Francisco Craton; the Canindé domain is likely to be an aborted Neoproterozoic rift assemblage within the southern part of the Borborema plate (Pernambuco-Alagoas massif). The basal units of the Vaza Barris and Estância domains have clast sources from the São Francisco Craton and are best interpreted as passive margin sediments. However, the uppermost units of the Estância and Vaza Barris domains come from foreland basins formed during collision of Borborema plate with the São Francisco Craton.

  3. Wilson-cycle "kick-off": Constraining the influence of a Large Igneous Province during the Neoproterozoic evolution of the pre-Caledonian margin of Baltica

    Science.gov (United States)

    Jørgen Kjøll, Hans; Andersen, Torgeir B.; Tegner, Christian; Corfu, Fernando; Planke, Sverre

    2016-04-01

    The supercontinent Rodinia broke up in the late Neoproterozoic to form the oceans and margins separating paleocontinents such as Baltica, Avalonia and Laurentia, which in turn later collided to form the Caledonian - Appalachian mountain belts. Some of the geological products of the complex evolution from passive-margin- to break-up are presently found in nappe complexes within the Scandinavian Caledonides. As described by P-G. Andreasson and co-workers in several papers from the 1990's, the break-up was associated with emplacement of major dolerite dike-complexes of Ediacaran age (c. 600 Ma), probably constituting a pre-Caledonian Large Igneous Province (pCLIP). The dominantly dolerite-dike swarms intruded a thinned continental crust comprising both crystalline basement and marine sediments deposited in pre- to early syn-rift basins. During peak rifting a sheeted dike complex defining the ocean-continent transition (OCT) evolved. More than 100 Myr later, during early stages of plate convergence, distal parts of the margin and the OCT experienced high to ultra-high pressure metamorphism, before the remnants of the dike swarms and the OCT were finally thrusted onto Baltica as the Seve and Särv Nappe Complexes. This occurred during the Scandian phase of the Caledonian orogeny at c. 425 Ma. Parts of the ancient magma-rich rifted margin are now exposed in the Scandinavian Caledonides. The best-preserved parts provide a remarkable analogue to present day OCTs and adjacent areas that generally only is observable in seismic sections. In order to understand the dynamics of the continental break-up, we will investigate the exposed areas to better constrain the active mechanisms that eventually produced oceanic crust. Also, with an improved understanding of magma-rich segments, a better comprehension may be achieved for magma-poor segments, which in the present study area occur both to the south and north of the pCLIP-segment in central Scandinavia. This presentation reports

  4. C- and Sr-isotope stratigraphy of the São Caetano complex, Northeastern Brazil: a contribution to the study of the Meso-Neoproterozoic seawater geochemistry

    Directory of Open Access Journals (Sweden)

    Juan C. Silva

    2005-03-01

    Full Text Available C-isotope and 87Sr/86Sr values for five carbonate successions from the São Caetano Complex, northeastern Brazil, were used to constrain their depositional age and to determine large variations in the C- and Sr-isotopic composition of seawater under the framework of global tectonic events. Three C-isotope stages were identified from base to top in a composed chemostratigraphic section: (1 stage in which delta13C values vary from +2 to +3.7‰ PDB and average 3‰ PDB, (2 stage with delta13C values displaying stronger oscillations (from -2‰ to +‰ PDB, and (3 stage with an isotopic plateau with values around +3.7‰ PDB. Constant 87Sr/86Sr values (~ 0.70600 characterize C-isotope stage 1, whereas slightly fluctuating values (from 0.70600 to 0.70700 characterize C-isotope stage 2. Finally, 87Sr/86Sr values averaging 0.70600 characterize C-isotope stage 3. The C- and Sr- chemostratigraphic pathways permit to state: (a the C- and Sr-isotope secular curves registered primary fluctuations of the isotope composition of seawater during late Mesoproterozoic- early Neoproterozoic transition in the Borborema Province, and (b onset of the Cariris Velhos/Greenville cycle, widespread oceanic rifting, continental magmatic arc formation and onset of the agglutination of Rodinia supercontinent, mostly controlled the C- and Sr-isotope composition of seawater during the C-isotope stages 1, 2 and 3.Valores de isótopos de C e 87Sr/86Sr de cinco seqüências de carbonatos do Complexo São Caetano, nordeste do Brasil; foram usados para estimar a sua idade de deposição e relacionar variações da composição isotópica na água do mar com eventos tectônicos globais. Três estágios de variação de isótopos de carbono foram identificados de base para o topo numa seção quimioestratigráfica composta: (1 estágio em que delta13C varia de +2 a +3.7‰PDB (media 3‰PDB, (2 estágio no qual delta13C varia consideravelmente (de -2 a +3‰PDB e (3 est

  5. Middle Neoproterozoic (ca. 705-716 Ma) arc to rift transitional magmatism in the northern margin of the Yangtze Block: Constraints from geochemistry, zircon U-Pb geochronology and Hf isotopes

    Science.gov (United States)

    Wang, Ruirui; Xu, Zhiqin; Santosh, M.; Xu, Xianbing; Deng, Qi; Fu, Xuehai

    2017-09-01

    The South Qinling Belt in Central China is an important window to investigate the Neoproterozoic tectono-magmatic processes along the northern margin of the Yangtze Block. Here we present whole-rock geochemistry, zircon U-Pb geochronology and Lu-Hf isotopes of a suite of Middle Neoproterozoic intrusion from the Wudang Uplift in South Qinling. Zircon LA-ICP-MS U-Pb ages reveal that these rocks were formed at ca. 705-716 Ma. Geochemical features indicate that the felsic magmatic rocks are I-type granitoids, belong to calcic- to calc-alkaline series, and display marked negative Nb, Ta and Ti anomalies. Moreover, the enrichment of light rare earth elements (LREEs) and large ion lithophile elements (LILEs), combined with depletion of heavy rare earth elements (HREEs) support that these rocks have affinity to typical arc magmatic rocks formed in Andean-type active continental margins. The REE patterns are highly to moderately fractionated, with (La/Yb)N = 5.13-8.10 in meta-granites, and 2.32-2.35 in granodiorite. The granitoids have a wide range of zircon εHf(t) values (-29.91 to 14.76) and zircon Hf two-stage model ages (696-3482 Ma). We suggest that the ca. 705-716 Ma granitoids were sourced from different degrees of magma mixing between partial melting of the overlying mantle wedge triggered by hydrous fluids released from subducted materials and crustal melting. The hybrid magmas were emplaced in the shallow crust accompanied by assimilation and fractional crystallization (AFC). Both isotopic and geochemical data suggest that the ca. 705-716 Ma felsic magmatic rocks were formed along a continental arc. These rocks as well as the contemporary A-type granite may mark a transitional tectonic regime from continental arc to rifting, probably related to slab rollback during the oceanic subduction beneath the northern margin of Yangtze Block.

  6. Gold and uranium metallogenesis in the framework of Neo-proterozoic crust growth and differentiation: example of the Mayo-Kebbi Massif (Chad) in the Central Africa Orogenic belt

    International Nuclear Information System (INIS)

    Mbaguedje, Diondoh

    2015-01-01

    The Mayo Kebbi massif located in southwestern Chad between the Congo craton in the South, the West African craton in the west and the Sahara meta-craton to the east exposes a segment of Neo-proterozoic juvenile crust accreted in the Central African orogenic belt during the Pan African orogeny. It consists of two greenstone belts (Zalbi and Goueygoudoum) separated by the May Kebbi calc-alkaline batholith complexes and intruded by calc-alkaline high-K granitic plutons. The whole is covered by Phanerozoic sedimentary formations. The greenstone belts contain sulphide zones hosted mainly by meta-plutonic rocks (granodiorites) and meta-basalts and meta-volcaniclastics. The mineralization comprises pyrite, pyrrhotite, arsenopyrite, chalcopyrite, pentlandite, pentlandite silver, pentlandite cobaltiferous, sphalerite, cobaltite. These sulphides are disseminated, aggregated in form of layers or are filling veins and cracks. The greenstones also contain quartz veins with calcite and chlorite comprising a mineralization made of pyrite, chalcopyrite, galena and gold. Gold is present both as native crystals and as electrum. The high-K calc-alkaline Zabili granitic pluton hosts uranium mineralization related to a superposition of: (1) ductile deformation and metasomatic alteration implying the interaction between magmatic minerals with a Na-rich fluid, of potential magmatic origin, coeval to the main deposition of uranium oxides, followed by (2) brittle deformation and deposition of secondary hydrated uranium silicates involving a Na-Ca-rich fluid. We propose that these uranium mineralizations represent the extreme expression of crustal differentiation as a result of Pan-African reworking of a Neo-proterozoic juvenile crustal segment. (author) [fr

  7. Lead isotope evidence for recent uranium mobility in geological formations of Brazil: implications for radioactive waste disposal

    International Nuclear Information System (INIS)

    Iyer, S.S.; Babinski, M.; Marinho, M.M.; Barbosa, J.S.F.; Sato, I.M.; Salvador, V.L.

    1999-01-01

    Lead-lead isotope data from whole rock samples are used to investigate the recent (last few million years) mobility of U and Th. The method is based on the comparison of the calculated present day U and Th concentrations required to yield the Pb isotope composition in the samples with the actual present day concentrations of U and Th obtained by direct measurement. The geological formations studied include the Neoproterozoic carbonate sediments of the Bambui Group, Archean/Paleoproterozoic granite-greenstone terrain of the Contendas-Mirante Complex and a Proterozoic ortho-gneisses hosting U deposit in Lagoa Real. All these formations are in the Sao Francisco Craton, Brazil. The data show high U mobility in the carbonate sediments and in the deformed ortho-gneisses set in a ductile shear zone. Infiltration of groundwater through fault zones seems to have facilitated the U mobility. The Pb isotope approach is a useful technique complementing U-series disequilibrium studies and may be included for site characterization studies for radioactive waste disposal. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  8. Group X

    Energy Technology Data Exchange (ETDEWEB)

    Fields, Susannah

    2007-08-16

    This project is currently under contract for research through the Department of Homeland Security until 2011. The group I was responsible for studying has to remain confidential so as not to affect the current project. All dates, reference links and authors, and other distinguishing characteristics of the original group have been removed from this report. All references to the name of this group or the individual splinter groups has been changed to 'Group X'. I have been collecting texts from a variety of sources intended for the use of recruiting and radicalizing members for Group X splinter groups for the purpose of researching the motivation and intent of leaders of those groups and their influence over the likelihood of group radicalization. This work included visiting many Group X websites to find information on splinter group leaders and finding their statements to new and old members. This proved difficult because the splinter groups of Group X are united in beliefs, but differ in public opinion. They are eager to tear each other down, prove their superiority, and yet remain anonymous. After a few weeks of intense searching, a list of eight recruiting texts and eight radicalizing texts from a variety of Group X leaders were compiled.

  9. Group Flow and Group Genius

    Science.gov (United States)

    Sawyer, Keith

    2015-01-01

    Keith Sawyer views the spontaneous collaboration of group creativity and improvisation actions as "group flow," which organizations can use to function at optimum levels. Sawyer establishes ideal conditions for group flow: group goals, close listening, complete concentration, being in control, blending egos, equal participation, knowing…

  10. Isopermutation group

    Energy Technology Data Exchange (ETDEWEB)

    Muktibodh, A. S. [Department of Mathematics, Mohota College of Science, NAGPUR-440009 India E-mail: amukti2000@yahoo.com (India)

    2015-03-10

    The concept of ‘Isotopy’ as formulated by Ruggero Maria Santilli [1, 2, 3] plays a vital role in the development of Iso mathematics. Santilli defined iso-fields of characteristic zero. In this paper we extend this definition to define Iso-Galois fields [4] which are essentially of non-zero characteristic. Isotopically isomorphic realizations of a group define isopermutation group which gives a clear cut distinction between automorphic groups and isotopic groups.

  11. Permutation groups

    CERN Document Server

    Passman, Donald S

    2012-01-01

    This volume by a prominent authority on permutation groups consists of lecture notes that provide a self-contained account of distinct classification theorems. A ready source of frequently quoted but usually inaccessible theorems, it is ideally suited for professional group theorists as well as students with a solid background in modern algebra.The three-part treatment begins with an introductory chapter and advances to an economical development of the tools of basic group theory, including group extensions, transfer theorems, and group representations and characters. The final chapter feature

  12. Reflection groups

    International Nuclear Information System (INIS)

    Eggermont, G.

    2006-01-01

    In 2005, PISA organised proactive meetings of reflection groups on involvement in decision making, expert culture and ethical aspects of radiation protection.All reflection group meetings address particular targeted audiences while the output publication in book form is put forward

  13. Group Theatre.

    Science.gov (United States)

    Clark, Brian

    The group interpretation approach to theatre production is defined as a method that will lead to production of plays that will appeal to "all the layers of the conscious and unconscious mind." In practice, it means that the group will develop and use resources of the theatre that orthodox companies too often ignore. The first two chapters of this…

  14. Dynamical Groups

    Science.gov (United States)

    Paldus, Josef

    The well known symmetry (invariance, degeneracy) dynamical groups or algebras of quantum mechanical Hamiltonians provide quantum numbers (conservation laws, integrals of motion) for state labeling and the associated selection rules. In addition, it is often advantageous to employ much larger groups, referred to as the dynamical groups (noninvariance groups, dynamical algebras, spectrum generating algebras), which may or may not be the invariance groups of the studied system [4.1,2,3,4,5,6,7]. In all known cases, they are Lie groups (LGs), or rather corresponding Lie algebras (LAs), and one usually requires that all states of interest of a system be contained in a single irreducible representation (irrep). Likewise, one may require that the Hamiltonian be expressible in terms of the Casimir operators of the corresponding universal enveloping algebra [4.8,9]. In a weaker sense, one regards any group (or corresponding algebra) as a dynamical group if the Hamiltonian can be expressed in terms of its generators [4.10,11,12]. In nuclear physics, one sometimes distinguishes exact (baryon number preserving), almost exact (e.g., total isospin), approximate (e.g., SU(3) of the "eightfold way") and model (e.g., nuclear shell model) dynamical symmetries [4.13]. The dynamical groups of interest in atomic and molecular physics can be conveniently classified by their topological characteristic of compactness. Noncompact LGs (LAs) generally arise in simple problems involving an infinite number of bound states, while those involving a finite number of bound states (e.g., molecular vibrations or ab initio models of electronic structure) exploit compact LG's.

  15. SHRIMP U-Pb zircon geochronology and Nd signatures of supracrustal sequences and orthogneisses constrain the Neoproterozoic evolution of the Pernambuco-Alagoas domain, southern part of Borborema Province, NE Brazil

    Science.gov (United States)

    Da Silva Filho, A. F.; Guimarães, I. P.; Van Schmus, W. R.; Armstrong, R. A.; Rangel da Silva, J. M.; Osako, L. S.; Cocentino, L. M.

    2014-11-01

    The Borborema Province is the western part of a major Brasiliano belt that extends from Brazil through NW Africa in pre-drift reconstructions. This province resulted from convergence and collision among the West African, Congo-São Francisco, and Amazonian cratons about 600 Ma. This study focuses on the Pernambuco-Alagoas (PEAL) domain, which is a complex of magmatic, migmatitic, and metamorphic rocks, located in the southern part of the Borborema Province. U-Pb geochronology and Sm-Nd data for metasedimentary sequences (Rio Una, Inhapi) of the PEAL domain and a sample from a sequence of the Transversal Zone domain suggest that their deposition occurred during a Cryogenian extensional event, within the interval 850-631 Ma (or slightly younger). This extensional event occurred in the PEAL, Transversal Zone, and Sergipano domains before the onset of the Brasiliano collision and was followed by syn- and post-collisional magmatism. The Rio Una sequence and the sequence from Transversal Zone domain were deposited over a Rhyacian (ca. 2.0-2.2) basement having a juvenile Palaeoproterozoic Nd signature, whereas the Inhapi sequence was deposited over an Early Neoproterozoic (Tonian) basement. The deposition of the studied sequences is coeval with metasedimentary sequences to the north and south in other domains of the Borborema Province. However, differences in Nd isotopic signatures between the sequences from PEAL, Transversal Zone, and Sergipano domains suggest that they were formed in distinct basins. Metasedimentary sequences from the PEAL domain have Meso- and Palaeoproterozoic T DM model ages. These data suggest that the orogens where the metasedimentary sequences are located have a strong ensialic component. T DM model ages of ca. 1.0 Ga and ɛNd (0.6 Ga) values around zero recorded in granites from the southern part of the PEAL, suggesting that juvenile material was accreted to the southern part of the PEAL domain crust during the Tonian. The migmatites from the

  16. Identification of Cr-magnetite in Neoproterozoic serpentinites resulting of Cr-Spinel alteration in a past hydrothermal system: Aït Ahmane ultramafic unit (Bou Azzer ophiolite, Anti Atlas, Morocco)

    Science.gov (United States)

    Hodel, Florent; Macouin, Mélina; Carlut, Julie; Triantafyllou, Antoine; Berger, Julien; Trindade, Ricardo; Ennih, Nasser; Rousse, Sonia

    2017-04-01

    If magnetite is a common serpentinization product, centimetric, massive and almost pure magnetite veins are rarely observed in serpentinites. Unique examples of these, in the Aït Ahmane ultramafic unit (Bou Azzer Neoproterozoic ophiolite, Anti-Atlas, Morocco), offer the opportunity to assess the hydrothermal processes that prevailed at the end of the Precambrian. Pseudomorphic lizardite/chrysotile texture of unaltered serpentinites suggests an oceanic-like first serpentinization stage, under static and low temperature conditions (T characterized by relatively small sized magnetite grains, mainly pseudo-single domain magnetites. Hysteresis parameters and first order reversal curves (FORC) diagram denote a magnetic grains size that increases with the alteration. This well-marked tendency is also reveals by a shift of the isothermal remanent magnetization (IRM) components toward lower coercivities for altered serpentinites. This grain size increase is associated with the emergence of a new magnetic phase with the hydrothermal alteration, the Cr-magnetite, evidenced by thermomagnetic measurements with Tc around 540 °C. This ultimate Cr-spinel alteration product is associated with another Cr-spinel alteration mineral, the ferritchromite, also identifiable on thermomagnetic curves by a rapid increase of the magnetite susceptibility at 130 °C due to its transformation during heating. Thermomagnetic curves allow us to propose a proxy, the CrM/M ratio providing a quantification of the Cr-magnetite contribution to the magnetic susceptibility, relatively to the pure magnetite one. This CrM/M ratio increases drastically with the hydrothermal alteration of serpentinites and Cr-spinels, attesting of a change of the magnetic mineralogy. Combined with petrography, mineral and bulk chemistry, these magnetic data allow us to propose that a Cl-rich acidic hydrothermal event, involving temperatures below 350 °C, appears to have been responsible of an intense magnetite leaching in

  17. Group Grammar

    Science.gov (United States)

    Adams, Karen

    2015-01-01

    In this article Karen Adams demonstrates how to incorporate group grammar techniques into a classroom activity. In the activity, students practice using the target grammar to do something they naturally enjoy: learning about each other.

  18. Computer group

    International Nuclear Information System (INIS)

    Bauer, H.; Black, I.; Heusler, A.; Hoeptner, G.; Krafft, F.; Lang, R.; Moellenkamp, R.; Mueller, W.; Mueller, W.F.; Schati, C.; Schmidt, A.; Schwind, D.; Weber, G.

    1983-01-01

    The computer groups has been reorganized to take charge for the general purpose computers DEC10 and VAX and the computer network (Dataswitch, DECnet, IBM - connections to GSI and IPP, preparation for Datex-P). (orig.)

  19. Group technology

    International Nuclear Information System (INIS)

    Rome, C.P.

    1976-01-01

    Group Technology has been conceptually applied to the manufacture of batch-lots of 554 machined electromechanical parts which now require 79 different types of metal-removal tools. The products have been grouped into 7 distinct families which require from 8 to 22 machines in each machine-cell. Throughput time can be significantly reduced and savings can be realized from tooling, direct-labor, and indirect-labor costs

  20. Lie groups and algebraic groups

    Indian Academy of Sciences (India)

    . These fields are interrelated and each of these fields contributes to the other. 2. Examples and classification. We first give some examples of Lie groups. The most frequently occurring ones are the linear classical groups GLn(R), GLn(C), ...

  1. Lie groups and algebraic groups

    Indian Academy of Sciences (India)

    M S RAGHUNATHAN and T N VENKATARAMANA. ∗. School of Mathematics, Tata Institute of Fundamental ... linear classical groups GLn(R), GLn(C), SOn(R),. SOn(C), Spn(R) and Spn(C). Let us call a con- nected Lie ..... split groups due respectively to C C Moore and. V Deodhar. B Sury solved the congruence subgroup ...

  2. Abelian groups

    CERN Document Server

    Fuchs, László

    2015-01-01

    Written by one of the subject’s foremost experts, this book focuses on the central developments and modern methods of the advanced theory of abelian groups, while remaining accessible, as an introduction and reference, to the non-specialist. It provides a coherent source for results scattered throughout the research literature with lots of new proofs. The presentation highlights major trends that have radically changed the modern character of the subject, in particular, the use of homological methods in the structure theory of various classes of abelian groups, and the use of advanced set-theoretical methods in the study of undecidability problems. The treatment of the latter trend includes Shelah’s seminal work on the undecidability in ZFC of Whitehead’s Problem; while the treatment of the former trend includes an extensive (but non-exhaustive) study of p-groups, torsion-free groups, mixed groups, and important classes of groups arising from ring theory. To prepare the reader to tackle these topics, th...

  3. Group learning

    DEFF Research Database (Denmark)

    Pimentel, Ricardo; Noguira, Eloy Eros da Silva; Elkjær, Bente

    The article presents a study that aims at the apprehension of the group learning in a top management team composed by teachers in a Brazilian Waldorf school whose management is collective. After deciding to extend the school, they had problems recruiting teachers who were already trained based...... with which they coexist. To achieve this, the research adopted phenomenology as a method and ethnography as strategy, using participant observation, in-depth interviews, and interviews-to-the-double. The results show that the collective management practice is a crossroad of other practices......, and they are interrelated to the group learning as the construction, maintenance and reconstruction of the intelligibility of practices. From this perspective, it can be said that learning is a practice and not an exceptional phenomenon. Building, maintaining and rebuilding the intelligibility is the group learning...

  4. U-Pb (LA-ICPMS) zircon ages and Nd isotopes for granitoids of the Tamboril-Santa Quiteria Complex, Ceara Central Domain: implication for neoproterozoic syncollisional magmatism in north Borborema Province, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Felipe Grandjean da; Araujo, Carlos Eduardo Ganade de; Vasconcelos, Antonio Maurilio, E-mail: felipe.costa@cprm.gov.br, E-mail: caegeo@gmail.com, E-mail: maurilio.vasconcelos@cprm.gov.br [Servico Geologico do Brasil (CPRM), Fortaleza, CE (Brazil); Amaral, Wagner da Silva, E-mail: wamaral@ufc.br [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Departamento de Geologia; Rodrigues, Joseneusa Brilhante, E-mail: joseneusa.rodrigues@cprm.gov.br [Servico Geologico do Brasil (CPRM), Brasilia, DF (Brazil)

    2013-06-15

    The Tamboril-Santa Quiteria Complex (TSQC) is one of the largest Neoproterozoic plutonic manifestations in the north Borborema Province (NE Brazil). It represents an anatectic/igneous association characterized by a number of magmatic pulses that occurred in the 650-610 Ma interval. In this paper, we present U-Pb (LA-MC-ICP-MS) zircon ages and Nd isotopes for quartz monzonite and quartz diorites of the southern part of TSQC. The quartz monzonite belong to a hybrid granitoid association, including monzonite, syenites and quartz syenites, all with abundant mafic magmatic enclaves. A quartz monzonite sample yielded a U-Pb zircon age of 634 {+-} 10 Ma and a TDM age of 2.69 Ga. The quartz diorites are much more homogeneous in composition and yielded a U-Pb zircon age of 618 {+-} 23 Ma and a TDM age of 2.19 Ga. The presence of coeval mantle-derived magmatism and diatexites (crustal anatexis) post-dating high-pressure metamorphism (ca. 650 Ma), and together with high-temperature metamorphism (ca. 630-610 Ma), suggests that this large magmatic manifestation evolved in a collisional setting, probably related to slab break off during the Western Gondwana amalgamation. (author)

  5. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2011-01-01

    The CMS Communications Group, established at the start of 2010, has been busy in all three areas of its responsibility: (1) Communications Infrastructure, (2) Information Systems, and (3) Outreach and Education. Communications Infrastructure There are now 55 CMS Centres worldwide that are well used by physicists working on remote CMS shifts, Computing operations, data quality monitoring, data analysis and outreach. The CMS Centre@CERN in Meyrin, is the centre of the CMS offline and computing operations, hosting dedicated analysis efforts such as during the CMS Heavy Ion lead-lead running. With a majority of CMS sub-detectors now operating in a “shifterless” mode, many monitoring operations are now routinely performed from there, rather than in the main Control Room at P5. The CMS Communications Group, CERN IT and the EVO team are providing excellent videoconferencing support for the rapidly-increasing number of CMS meetings. In parallel, CERN IT and ...

  6. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2011-01-01

    The CMS Communications Group has been busy in all three areas of its responsibility: (1) Communications Infrastructure, (2) Information Systems, and (3) Outreach and Education. Communications Infrastructure The 55 CMS Centres worldwide are well used by physicists working on remote CMS shifts, Computing operations, data quality monitoring, data analysis and outreach. The CMS Centre@CERN in Meyrin, is the centre of the CMS Offline and Computing operations, and a number of subdetector shifts can now take place there, rather than in the main Control Room at P5. A new CMS meeting room has been equipped for videoconferencing in building 42, next to building 40. Our building 28 meeting room and the facilities at P5 will be refurbished soon and plans are underway to steadily upgrade the ageing equipment in all 15 CMS meeting rooms at CERN. The CMS evaluation of the Vidyo tool indicates that it is not yet ready to be considered as a potential replacement for EVO. The Communications Group provides the CMS-TV (web) cha...

  7. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2010-01-01

    The CMS Communications Group, established at the start of 2010, has been strengthening the activities in all three areas of its responsibility: (1) Communications Infrastructure, (2) Information Systems, and (3) Outreach and Education. Communications Infrastructure The Communications Group has invested a lot of effort to support the operations needs of CMS. Hence, the CMS Centres where physicists work on remote CMS shifts, Data Quality Monitoring, and Data Analysis are running very smoothly. There are now 55 CMS Centres worldwide, up from just 16 at the start of CMS data-taking. The latest to join are Imperial College London, the University of Iowa, and the Università di Napoli. The CMS Centre@CERN in Meyrin, which is now full repaired after the major flooding at the beginning of the year, has been at the centre of CMS offline and computing operations, most recently hosting a large fraction of the CMS Heavy Ion community during the lead-lead run. A number of sub-detector shifts can now take pla...

  8. Group play

    DEFF Research Database (Denmark)

    Tychsen, Anders; Hitchens, Michael; Brolund, Thea

    2008-01-01

    Role-playing games (RPGs) are a well-known game form, existing in a number of formats, including tabletop, live action, and various digital forms. Despite their popularity, empirical studies of these games are relatively rare. In particular there have been few examinations of the effects of the v......Role-playing games (RPGs) are a well-known game form, existing in a number of formats, including tabletop, live action, and various digital forms. Despite their popularity, empirical studies of these games are relatively rare. In particular there have been few examinations of the effects...... of the various formats used by RPGs on the gaming experience. This article presents the results of an empirical study, examining how multi-player tabletop RPGs are affected as they are ported to the digital medium. Issues examined include the use of disposition assessments to predict play experience, the effect...... of group dynamics, the influence of the fictional game characters and the comparative play experience between the two formats. The results indicate that group dynamics and the relationship between the players and their digital characters, are integral to the quality of the gaming experience in multiplayer...

  9. Cardiovascular group

    Science.gov (United States)

    Blomqvist, Gunnar

    1989-01-01

    As a starting point, the group defined a primary goal of maintaining in flight a level of systemic oxygen transport capacity comparable to each individual's preflight upright baseline. The goal of maintaining capacity at preflight levels would seem to be a reasonable objective for several different reasons, including the maintenance of good health in general and the preservation of sufficient cardiovascular reserve capacity to meet operational demands. It is also important not to introduce confounding variables in whatever other physiological studies are being performed. A change in the level of fitness is likely to be a significant confounding variable in the study of many organ systems. The principal component of the in-flight cardiovascular exercise program should be large-muscle activity such as treadmill exercise. It is desirable that at least one session per week be monitored to assure maintenance of proper functional levels and to provide guidance for any adjustments of the exercise prescription. Appropriate measurements include evaluation of the heart-rate/workload or the heart-rate/oxygen-uptake relationship. Respiratory gas analysis is helpful by providing better opportunities to document relative workload levels from analysis of the interrelationships among VO2, VCO2, and ventilation. The committee felt that there is no clear evidence that any particular in-flight exercise regimen is protective against orthostatic hypotension during the early readaptation phase. Some group members suggested that maintenance of the lower body muscle mass and muscle tone may be helpful. There is also evidence that late in-flight interventions to reexpand blood volume to preflight levels are helpful in preventing or minimizing postflight orthostatic hypotension.

  10. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2010-01-01

    The recently established CMS Communications Group, led by Lucas Taylor, has been busy in all three of its main are areas of responsibility: Communications Infrastructure, Information Systems, and Outreach and Education Communications Infrastructure The damage caused by the flooding of the CMS Centre@CERN on 21st December has been completely repaired and all systems are back in operation. Major repairs were made to the roofs, ceilings and one third of the floor had to be completely replaced. Throughout these works, the CMS Centre was kept operating and even hosted a major press event for first 7 TeV collisions, as described below. Incremental work behind the scenes is steadily improving the quality of the CMS communications infrastructure, particularly Webcasting, video conferencing, and meeting rooms at CERN. CERN/IT is also deploying a pilot service of a new videoconference tool called Vidyo, to assess whether it might provide an enhanced service at a lower cost, compared to the EVO tool currently in w...

  11. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2012-01-01

      Outreach and Education We are fortunate that our research has captured the public imagination, even though this inevitably puts us under the global media spotlight, as we saw with the Higgs seminar at CERN in December, which had 110,000 distinct webcast viewers. The media interest was huge with 71 media organisations registering to come to CERN to cover the Higgs seminar, which was followed by a press briefing with the DG and Spokespersons. This event resulted in about 2,000 generally positive stories in the global media. For this seminar, the CMS Communications Group prepared up-to-date news and public material, including links to the CMS results, animations and event displays [http://cern.ch/go/Ch8thttp://cern.ch/go/Ch8t]. There were 44,000 page-views on the CMS public website, with the Higgs news article being by far the most popular item. CMS event displays from iSpy are fast becoming the iconic media images, featuring on numerous major news outlets (BBC, CNN, MSN...) as well as in the sci...

  12. COMMUNICATIONS GROUP

    CERN Multimedia

    L. Taylor

    2011-01-01

    Communications Infrastructure The 55 CMS Centres worldwide are well used by physicists working on remote CMS shifts, Computing operations, data quality monitoring, data analysis and outreach. The CMS Centre@CERN in Meyrin is particularly busy at the moment, hosting about 50 physicists taking part in the heavy-ion data-taking and analysis. Three new CMS meeting room will be equipped for videoconferencing in early 2012: 40/5B-08, 42/R-031, and 28/S-029. The CMS-TV service showing LHC Page 1, CMS Page 1, etc. (http://cmsdoc.cern.ch/cmscc/projector/index.jsp) is now also available for mobile devices: http://cern.ch/mcmstv. Figure 12: Screenshots of CMS-TV for mobile devices Information Systems CMS has a new web site: (http://cern.ch/cms) using a modern web Content Management System to ensure content and links are managed and updated easily and coherently. It covers all CMS sub-projects and groups, replacing the iCMS internal pages. It also incorporates the existing CMS public web site (http:/...

  13. Neoproterozoic-Early Paleozoic Peri-Pacific Accretionary Evolution of the Mongolian Collage System: Insights From Geochemical and U-Pb Zircon Data From the Ordovician Sedimentary Wedge in the Mongolian Altai

    Science.gov (United States)

    Jiang, Y. D.; Schulmann, K.; Kröner, A.; Sun, M.; Lexa, O.; Janoušek, V.; Buriánek, D.; Yuan, C.; Hanžl, P.

    2017-11-01

    Neoproterozoic to early Paleozoic accretionary processes of the Central Asian Orogenic Belt have been evaluated so far mainly using the geology of ophiolites and/or magmatic arcs. Thus, the knowledge of the nature and evolution of associated sedimentary prisms remains fragmentary. We carried out an integrated geological, geochemical, and zircon U-Pb geochronological study on a giant Ordovician metasedimentary succession of the Mongolian Altai Mountains. This succession is characterized by dominant terrigenous components mixed with volcanogenic material. It is chemically immature, compositionally analogous to graywacke, and marked by significant input of felsic to intermediate arc components, pointing to an active continental margin depositional setting. Detrital zircon U-Pb ages suggest a source dominated by products of early Paleozoic magmatism prevailing during the Cambrian-Ordovician and culminating at circa 500 Ma. We propose that the Ordovician succession forms an "Altai sedimentary wedge," the evolution of which can be linked to the geodynamics of the margins of the Mongolian Precambrian Zavhan-Baydrag blocks. This involved subduction reversal from southward subduction of a passive continental margin (Early Cambrian) to the development of the "Ikh-Mongol Magmatic Arc System" and the giant Altai sedimentary wedge above a north dipping subduction zone (Late Cambrian-Ordovician). Such a dynamic process resembles the tectonic evolution of the peri-Pacific accretionary Terra Australis Orogen. A new model reconciling the Baikalian metamorphic belt along the southern Siberian Craton with peri-Pacific Altai accretionary systems fringing the Mongolian microcontinents is proposed to explain the Cambro-Ordovician geodynamic evolution of the Mongolian collage system.

  14. From the plutonic root to the volcanic roof of a continental magmatic arc: a review of the Neoproterozoic Araçuaí orogen, southeastern Brazil

    Science.gov (United States)

    Gonçalves, Leonardo; Alkmim, Fernando F.; Pedrosa-Soares, Antônio; Gonçalves, Cristiane C.; Vieira, Valter

    2018-01-01

    The Araçuaí-West Congo orogen (AWCO) is one of the various components of the Brasiliano/Pan-African orogenic network generated during the amalgamation of West Gondwana. In the reconstructions of Gondwana, the AWCO, encompassing the Araçuaí orogen of South America and the West Congo belt of Southwestern Africa, appears as a tongue-shaped orogenic zone embraced by the São Francisco-Congo craton. Differing from the vast majority of the known orogens owing to its singular confined setting, the AWCO contains a large amount of orogenic igneous rocks emplaced in all stages of its tectonic evolution. We present new and revised information about the oldest Ediacaran granitic assemblage, the G1 Supersuite, which together with the Rio Doce Group defines the Rio Doce magmatic arc, and then we propose a new tectonic setting for the arc. Field relationships and mineralogical compositions of the G1 Supersuite allow us to characterize three lithofacies associations, Opx-bearing rocks, enclave-rich Tonalite-Granodiorite and enclave-poor Granite-Tonalite, suggesting different crustal levels are exposed in the central part of the Araçuaí orogen. The region is interpreted to represent a tilted crustal section, with deep arc roots now exposed along its western border. Chemically, these plutonic associations consist mostly of magnesian, metaluminous to slightly peraluminous, calc-alkaline to alkali-calcic and medium- to high-K acidic rocks. The dacitic and rhyolitic rocks of the Rio Doce Group are mainly magnesian, peraluminous, calcic to calc-alkaline, and medium- to high-K acidic rocks. Zircon U-Pb data constrain the crystallization of the granitoids between ca. 625 and 574 Ma, while the age of the metamorphosed volcanic rocks is around ca. 585 Ma. Thus, within errors, these rock associations likely belong to the same magmatic event and might represent the subduction-related, pre-collisional, evolution of the Araçuaí orogen. In addition, whole-rock Sm-Nd isotopic compositions

  15. Atum: Scalable Group Communication Using Volatile Groups

    OpenAIRE

    Guerraoui, Rachid; Kermarrec, Anne-Marie; Pavlovic, Matej; Seredinschi, Dragos-Adrian

    2016-01-01

    This paper presents Atum, a group communication middleware for a large, dynamic, and hostile environment. At the heart of Atum lies the novel concept of volatile groups: small, dynamic groups of nodes, each executing a state machine replication protocol, organized in a flexible overlay. Using volatile groups, Atum scatters faulty nodes evenly among groups, and then masks each individual fault inside its group. To broadcast messages among volatile groups, Atum runs a gossip protocol across the...

  16. Which finite simple groups are unit groups?

    DEFF Research Database (Denmark)

    Davis, Christopher James; Occhipinti, Tommy

    2014-01-01

    We prove that if G is a finite simple group which is the unit group of a ring, then G is isomorphic to either (a) a cyclic group of order 2; (b) a cyclic group of prime order 2^k −1 for some k; or (c) a projective special linear group PSLn(F2) for some n ≥ 3. Moreover, these groups do all occur...

  17. Tidal shelf sedimentation in the Neoproterozoic Chattisgarh ...

    Indian Academy of Sciences (India)

    ... or 3D dunes mantled with lag pebble deposits at different points. With continued shoaling and progradation, thebars amalgamated into large sandstone sheets with the development of high energy beach depositsand coastal sand flats in the uppermost part of the sequence. The presence of rill marks, flat-topped ripples, ...

  18. Geochemistry and petrogenesis of Neoproterozoic Mylliem ...

    Indian Academy of Sciences (India)

    100. PG/109. PG/136. Quartz. 34.1. 18.5. 24.7. 23.9. 20.5. 37.8. 22.9. 22.9. 28.7. 21.1. 19.5. 23.3. 20.1. 29.4. 20.6. 20.8. K-feldspar. 13.8. 60.9. 25.2. 52.8. 20.2. 11.0. 49.5. 43.4. 30.8. 38.3. 61.5. 38.84. 52.0. 32.8. 53.6. 39.4. Plagio clase. 47.1. 13.1.

  19. Geochemistry and petrogenesis of Neoproterozoic Mylliem ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 120; Issue 3. Geochemistry and petrogenesis of ... Petrographically, Mylliem granitoids are characterized by pink to white phenocrysts of prismatic microcline/perthite and lath-shaped plagioclase (An20–An29). Groundmass material is characterized by quartz, ...

  20. New U-Pb age constraints on the upper Banxi Group and synchrony of the Sturtian glaciation in South China

    Directory of Open Access Journals (Sweden)

    Gaoyuan Song

    2017-09-01

    Full Text Available The Nanhua basin in South China hosts well-preserved middle–late Neoproterozoic sedimentary and volcanic rocks that are critical for studying the basin evolution, the breakup of the supercontinent Rodinia, the nature and dynamics of the “snowball” Earth and diversification of metazoans. Establishing a stratigraphic framework is crucial for better understanding the interactions between tectonic, paleoclimatic and biotic events recorded in the Nanhua basin, but existing stratigraphic correlations remain debated, particularly for pre-Ediacaran strata. Here we report new Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS U-Pb zircon ages from the middle and topmost Wuqiangxi Formation (the upper stratigraphic unit of the Banxi Group in Siduping, Hunan Province, South China. Two samples show similar age distribution, with two major peaks at ca. 820 Ma and 780 Ma and one minor peak at ca. 910 Ma, suggesting that the Wuqiangxi sandstone was mainly sourced from Neoproterozoic rocks. Two major age peaks correspond to two phases of magmatic events associated with the rifting of the Nanhua basin, and the minor peak at ca. 910 Ma may correspond to the Shuangxiwu volcanic arc magmatism, which represents pre-collision/amalgamation subduction on the southeastern margin of the Yangtze Block. The youngest zircon group from the topmost Wuqiangxi Formation has a weighted mean age of 714.6 ± 5.2 Ma, which is likely close to the depositional age of the uppermost Banxi Group. This age, along with the ages reported from other sections, constrains that the Banxi Group was deposited between ca. 820 Ma and ca. 715 Ma. The age of 714.6 ± 5.2 Ma from the top of the Wuqiangxi Formation is indistinguishable with the SIMS U-Pb age of 715.9 ± 2.8 Ma from the upper Gongdong Formation in the Sibao village section of northern Guangxi, South China. It is also, within uncertainties, overlapped with two TIMS U-Pb ages from pre

  1. Group Cohesion in Experiential Growth Groups

    Science.gov (United States)

    Steen, Sam; Vasserman-Stokes, Elaina; Vannatta, Rachel

    2014-01-01

    This article explores the effect of web-based journaling on changes in group cohesion within experiential growth groups. Master's students were divided into 2 groups. Both used a web-based platform to journal after each session; however, only 1 of the groups was able to read each other's journals. Quantitative data collected before and…

  2. Probability groups as orbits of groups

    International Nuclear Information System (INIS)

    Bhattarai, H.N.

    2003-11-01

    The set of double cosets of a group with respect to a subgroup and the set of orbits of a group with respect to a group of automorphisms have structures which can be studied as multigroups, hypergroups or Pasch geometries. When the subgroup or the group of automorphisms are finite, the multivalued products can be provided with some weightages forming so-called Probability Groups. It is shown in this paper that some abstract probability groups can be realized as orbit spaces of groups. (author)

  3. Group typicality, group loyalty and cognitive development.

    Science.gov (United States)

    Patterson, Meagan M

    2014-09-01

    Over the course of childhood, children's thinking about social groups changes in a variety of ways. Developmental Subjective Group Dynamics (DSGD) theory emphasizes children's understanding of the importance of conforming to group norms. Abrams et al.'s study, which uses DSGD theory as a framework, demonstrates the social cognitive skills underlying young elementary school children's thinking about group norms. Future research on children's thinking about groups and group norms should explore additional elements of this topic, including aspects of typicality beyond loyalty. © 2014 The British Psychological Society.

  4. AREVA group overview; Presentation du groupe AREVA

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-02-08

    This document presents the Group Areva, a world nuclear industry leader, from a financial holding company to an industrial group, operating in two businesses: the nuclear energy and the components. The structure and the market of the group are discussed, as the financial assets. (A.L.B.)

  5. Réactivation du craton ouest-africain au Panafricain: paléocontraintes déduites de la fracturation des grès néoprotérozoïques de Karey Gorou (Niger, Afrique de l'Ouest)Reactivation of the West-African craton during the Panafrican tectonic cycle: evidence of paleostresses recorded by brittle deformation in the Neoproterozoic sandstones of Karey Gorou (Niger, West Africa).

    Science.gov (United States)

    Affaton, Pascal; Gaviglio, Patrick; Pharisat, André

    2000-11-01

    One distensive and three compressive episodes are displayed by faults in the Neoproterozoic sandstones lying on the eastern margin of the Palaeoproterozoic West-African craton in the Karey Gorou area in Niger. It concerns the submeridian distension related to reactivation of a fragmentation stage of this craton and with which are associated the doleritic veins dated at ca. 1 400 Ma. The three compressive episodes, striking NNW-SSE, WNW-ESE and WSW-ENE, are related to the Panafrican tectonic phases. In the Hoggar, these events are dated at ca. 680 Ma, ca. 600 Ma and 560-530 Ma respectively.

  6. Introduction to Sporadic Groups

    Directory of Open Access Journals (Sweden)

    Luis J. Boya

    2011-01-01

    Full Text Available This is an introduction to finite simple groups, in particular sporadic groups, intended for physicists. After a short review of group theory, we enumerate the 1+1+16=18 families of finite simple groups, as an introduction to the sporadic groups. These are described next, in three levels of increasing complexity, plus the six isolated ''pariah'' groups. The (old five Mathieu groups make up the first, smallest order level. The seven groups related to the Leech lattice, including the three Conway groups, constitute the second level. The third and highest level contains the Monster group M, plus seven other related groups. Next a brief mention is made of the remaining six pariah groups, thus completing the 5+7+8+6=26 sporadic groups. The review ends up with a brief discussion of a few of physical applications of finite groups in physics, including a couple of recent examples which use sporadic groups.

  7. Experience with Group Supervision

    OpenAIRE

    Chen, Weiqin

    2006-01-01

    Supervision can take a few different forms. For example, it can be one-to-one supervision and it can also be group supervision. Group supervision is an important process within the scientific community. Many research groups use this form to supervise doctoral- and master students in groups. Some efforts have been made to study this process. For example, Samara (2002) studied the group supervision process in group writing. However, group supervision has not been studied thorough...

  8. Group Work: How to Use Groups Effectively

    Science.gov (United States)

    Burke, Alison

    2011-01-01

    Many students cringe and groan when told that they will need to work in a group. However, group work has been found to be good for students and good for teachers. Employers want college graduates to have developed teamwork skills. Additionally, students who participate in collaborative learning get better grades, are more satisfied with their…

  9. Free Boolean Topological Groups

    Directory of Open Access Journals (Sweden)

    Ol’ga Sipacheva

    2015-11-01

    Full Text Available Known and new results on free Boolean topological groups are collected. An account of the properties that these groups share with free or free Abelian topological groups and properties specific to free Boolean groups is given. Special emphasis is placed on the application of set-theoretic methods to the study of Boolean topological groups.

  10. Provenance and paleogeography of the Devonian Durazno Group, southern Parana Basin in Uruguay

    Science.gov (United States)

    Uriz, N. J.; Cingolani, C. A.; Basei, M. A. S.; Blanco, G.; Abre, P.; Portillo, N. S.; Siccardi, A.

    2016-03-01

    A succession of Devonian cover rocks occurs in outcrop and in the subsurface of central-northern Uruguay where they were deposited in an intracratonic basin. This Durazno Group comprises three distinct stratigraphic units, namely the Cerrezuelo, Cordobés and La Paloma formations. The Durazno Group does not exceed 300 m of average thickness and preserves a transgressive-regressive cycle within a shallow-marine siliciclastic shelf platform, and is characterized by an assemblage of invertebrate fossils of Malvinokaffric affinity especially within the Lower Devonian Cordobés shales. The sedimentary provenance of the Durazno Group was determined using petrography, geochemistry, and morphological studies of detrital zircons as well as their U-Pb ages. Sandstone petrography of Cerrezuelo and La Paloma sequences shows that they have a dominantly quartz-feldspathic composition with a minor contribution of other minerals. Whole-rock geochemical data indicate that alteration was strong in each of the three formations studied; chondritic-normalized REE patterns essentially parallel to PAAS, the presence of a negative Eu-anomaly, and Th/Sc and La/Hf ratios point to an average source composition similar to UCC or slightly more felsic. Within the Cerrezuelo Formation, recycling of older volcano-metasedimentary sources is interpreted from Zr/Sc ratios and high Hf, Zr, and REE concentrations. U-Pb detrital zircon age populations of the Cerrezuelo and La Paloma formations indicate that the principal source terranes are of Neoproterozoic age, but include also minor populations derived from Mesoproterozoic and Archean-Paleoproterozoic rocks. A provenance from the Cuchilla Dionisio-Dom Feliciano, Nico Pérez and Piedra Alta terranes of Uruguay and southern Brazil is likely. This study establishes an intracratonic extensional tectonic setting during Durazno time. Considering provenance age sources, regional paleocurrent distributions and the established orogenic history recorded in SW

  11. Profinite graphs and groups

    CERN Document Server

    Ribes, Luis

    2017-01-01

    This book offers a detailed introduction to graph theoretic methods in profinite groups and applications to abstract groups. It is the first to provide a comprehensive treatment of the subject. The author begins by carefully developing relevant notions in topology, profinite groups and homology, including free products of profinite groups, cohomological methods in profinite groups, and fixed points of automorphisms of free pro-p groups. The final part of the book is dedicated to applications of the profinite theory to abstract groups, with sections on finitely generated subgroups of free groups, separability conditions in free and amalgamated products, and algorithms in free groups and finite monoids. Profinite Graphs and Groups will appeal to students and researchers interested in profinite groups, geometric group theory, graphs and connections with the theory of formal languages. A complete reference on the subject, the book includes historical and bibliographical notes as well as a discussion of open quest...

  12. Group purchasing: an overview.

    Science.gov (United States)

    Wetrich, J G

    1987-07-01

    The various types and operational methods of purchasing groups are described, and evaluation of groups is discussed. Since group purchasing is increasing in popularity as a method of controlling drug costs, community and hospital pharmacy managers may need to evaluate various groups to determine the appropriateness of their services. Groups are categorized as independent, system based, or alliance or association based. Instead of "purchasing," some groups develop contracts for hospitals, which then purchase directly from the vendor. Aside from this basic difference between groups that purchase and groups that contract, comparisons among groups are difficult because of the wide variation in sizes and services. Competition developing from diversification among groups has led to "super groups," formed from local and regional groups. In evaluating groups, advantages and disadvantages germane to accomplishing the member's objectives must be considered. To ensure a group's success, members must be committed and support the group's philosophies; hospital pharmacists must help to establish a strong formulary system. To select vendors, groups should develop formal qualification and selection criteria and should not base a decision solely on price. The method of solicitation (bidding or negotiating), as well as the role of the prime vendor, should be studied. Legal implications of group purchasing, especially in the areas of administrative fees and drug diversion, must also be considered. The most advantageous group for each organization will include members with common missions and will be able to implement strategies for future success.

  13. Ordered groups and infinite permutation groups

    CERN Document Server

    1996-01-01

    The subjects of ordered groups and of infinite permutation groups have long en­ joyed a symbiotic relationship. Although the two subjects come from very different sources, they have in certain ways come together, and each has derived considerable benefit from the other. My own personal contact with this interaction began in 1961. I had done Ph. D. work on sequence convergence in totally ordered groups under the direction of Paul Conrad. In the process, I had encountered "pseudo-convergent" sequences in an ordered group G, which are like Cauchy sequences, except that the differences be­ tween terms of large index approach not 0 but a convex subgroup G of G. If G is normal, then such sequences are conveniently described as Cauchy sequences in the quotient ordered group GIG. If G is not normal, of course GIG has no group structure, though it is still a totally ordered set. The best that can be said is that the elements of G permute GIG in an order-preserving fashion. In independent investigations around that t...

  14. Citizens' action group

    International Nuclear Information System (INIS)

    Andritzky, W.

    1978-01-01

    For the first empirical study of citizens' action groups 331 such groups were consulted. Important information was collected on the following aspects of these groups: their self-image, areas and forms of activities, objectives and their extent, how long the group has existed, successes and failures and their forms of organisation. (orig.) [de

  15. When Groups Go Wrong.

    Science.gov (United States)

    Schopler, Janice H.; Galinsky, Maeda J.

    1981-01-01

    Studied social workers' perceptions of group dimensions that had negative effects on members. Found that group leaders viewed group composition as a major source of harmful interaction while members and observers saw group norms as a more frequent cause of negative effects. (Author/JAC)

  16. Group Psychotherapy in Germany.

    Science.gov (United States)

    Weber, Rainer; Strauss, Bernhard

    2015-10-01

    This article gives an overview of the development of group psychotherapies in Germany originating from a psychodynamic tradition. The German health system provides access to inpatient and outpatient psychotherapy for all of its citizens. Whereas groups are common in inpatient settings, the provision of outpatient group treatment still could be improved, as it is the case for the general training of group psychotherapists. Group research in Germany largely reflects clinical practice, with more studies coming from the inpatient field. It is stated that the general image of group treatment seems to be largely positive, which could provide a basis for political initiatives to improve the dissemination of group therapy in this country.

  17. Handbook of group actions

    CERN Document Server

    Papadopoulos, Athanase; Yau, Shing-Tung

    2015-01-01

    Groups and group actions are probably the most central objects in mathematics. Comprising volumes 31 and 32 of the ALM series (with further volumes forthcoming), the Handbook of Group Actions presents survey articles on the topic of group actions and how they appear in several mathematical contexts. The general subject matter is organized under the following sections: geometry, mapping class groups, knot groups, topology, representation theory, deformation theory, and discrete groups. The various articles deal with both classical material and modern developments. They are written by specialists in their respective subject areas, and addressed to graduate students who want to learn the theory, as well as to specialists as a reference.

  18. Innovation in business groups

    OpenAIRE

    Sharon Belenzon; Tomer Berkovitz

    2007-01-01

    Using novel data on European firms, this paper investigates the relationship between business groups and innovation. Controlling for various firm characteristics, we find that group affiliates are more innovative than standalones. We examine several hypotheses to explain this finding, focusing on group internal capital markets and knowledge spillovers. We find that group affiliation is particularly important for innovation in industries that rely more on external funding and in groups with mo...

  19. Group Psychotherapy in Iceland.

    Science.gov (United States)

    Ívarsson, Ómar

    2015-10-01

    In this overview of group psychotherapy in Iceland, an attempt will be made to describe how it is practiced today, give some glimpses into its earlier history, and clarify seven issues: (1) the standing of group psychotherapy in Iceland, its previous history, and the theoretical orientation of dynamic group therapy in the country; (2) the role of group therapy in the health care system; (3) how training in group therapy is organized; (4) the relationship between group psychotherapy research and clinical practice; (5) which issues/processes can be identified as unique to therapy groups in Iceland; and (6) how important are group-related issues within the social background of the country; and (7) what group work holds for the future.

  20. Independent student study groups.

    Science.gov (United States)

    Hendry, Graham D; Hyde, Sarah J; Davy, Peter

    2005-07-01

    Teachers and students regulate learning to varying degrees in educational programmes in higher education. We present evidence that students in a student-centred medical programme self- and co-regulate their learning in independently formed study groups. We describe the perceived benefits of study groups and the effect of study group membership on student achievement. Years 1-2 of a 4-year, graduate-entry problem-based medical programme. We surveyed 233 year 2 students about features of their study groups and their study group membership in years 1-2. We compared study group membership with students' scores on a written summative assessment held at the end of their second year. For students who joined 1 study group, the length of time their group stayed together was positively related to achievement in the written summative assessment. There were no differences in summative assessment results between students who had been in a study group and students who had not been in a study group. Effective study groups are supportive, socially cohesive groups who generate mutual trust and loyalty, and self- and co-regulate their learning by giving and receiving explanations and summaries and motivating individual study. Teachers can support the formation of study groups by using small-group teaching/learning activities, providing clear learning outcomes and assessment criteria, minimising competition for grades and allocating room space.

  1. Nilpotent -local finite groups

    Science.gov (United States)

    Cantarero, José; Scherer, Jérôme; Viruel, Antonio

    2014-10-01

    We provide characterizations of -nilpotency for fusion systems and -local finite groups that are inspired by known result for finite groups. In particular, we generalize criteria by Atiyah, Brunetti, Frobenius, Quillen, Stammbach and Tate.

  2. Group Decision Process Support

    DEFF Research Database (Denmark)

    Gøtze, John; Hijikata, Masao

    1997-01-01

    Introducing the notion of Group Decision Process Support Systems (GDPSS) to traditional decision-support theorists.......Introducing the notion of Group Decision Process Support Systems (GDPSS) to traditional decision-support theorists....

  3. UPIN Group File

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Group Unique Physician Identifier Number (UPIN) File is the business entity file that contains the group practice UPIN and descriptive information. It does NOT...

  4. Introduction to topological groups

    CERN Document Server

    Husain, Taqdir

    2018-01-01

    Concise treatment covers semitopological groups, locally compact groups, Harr measure, and duality theory and some of its applications. The volume concludes with a chapter that introduces Banach algebras. 1966 edition.

  5. Free paratopological groups

    Directory of Open Access Journals (Sweden)

    Ali Sayed Elfard

    2015-10-01

    Full Text Available Let FP(X be the free paratopological group on a topological space X in the sense of Markov. In this paper, we study the group FP(X on a $P_\\alpha$-space $X$ where $\\alpha$ is an infinite cardinal and then we prove that the group FP(X is an Alexandroff space if X is an Alexandroff space. Moreover, we introduce a~neighborhood base at the identity of the group FP(X when the space X is Alexandroff and then we give some properties of this neighborhood base. As applications of these, we prove that the group FP(X is T_0 if X is T_0, we characterize the spaces X for which the group FP(X is a topological group and then we give a class of spaces $X$ for which the group FP(X has the inductive limit property.

  6. Group B streptococcus - pregnancy

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000511.htm Group B streptococcus - pregnancy To use the sharing features on this page, please enable JavaScript. Group B streptococcus (GBS) is a type of bacteria that ...

  7. Gestalt Interactional Groups

    Science.gov (United States)

    Harman, Robert L.; Franklin, Richard W.

    1975-01-01

    Gestalt therapy in groups is not limited to individual work in the presence of an audience. Describes several ways to involve gestalt groups interactionally. Interactions described focus on learning by doing and discovering, and are noninterpretive. (Author/EJT)

  8. Informal group discussion

    Science.gov (United States)

    Hans Nienstaedt; Dean W. Einspahr; J. Douglas Brodie

    1973-01-01

    Editor's note: The morning's presentations were discussed during the afternoon by three groups, each group discussing one of the morning's three topics. Summaries of the discussions, prepared by the discussion leaders, follow.

  9. Multicultural group work

    DEFF Research Database (Denmark)

    Hansen, Annette Skovsted

    2014-01-01

    Motivation for the activity I use this strategy for forming groups to ensure diverse/multicultural groups that combine a variety of different strengths and resources based on student's academic, disciplinary, linguistic, national, personal and work backgrounds.......Motivation for the activity I use this strategy for forming groups to ensure diverse/multicultural groups that combine a variety of different strengths and resources based on student's academic, disciplinary, linguistic, national, personal and work backgrounds....

  10. AREVA group overview

    International Nuclear Information System (INIS)

    2002-01-01

    This document presents the Group Areva, a world nuclear industry leader, from a financial holding company to an industrial group, operating in two businesses: the nuclear energy and the components. The structure and the market of the group are discussed, as the financial assets. (A.L.B.)

  11. Quantum isometry groups

    Indian Academy of Sciences (India)

    Jyotishman Bhowmick

    2015-11-07

    Nov 7, 2015 ... NONcommutative spaces. 2. Banica and Bichon defined quantum symmetry groups for finite metric spaces, finite graphs, etc. 3. Lots of examples computed leading to discovery of completely new kinds of quantum groups. Jyotishman Bhowmick (Indian Statistical Institute). Quantum isometry groups. 07.11.

  12. Higher arithmetic Chow groups

    DEFF Research Database (Denmark)

    Gil, J. I. Burgos; Feliu, Elisenda

    2012-01-01

    We give a new construction of higher arithmetic Chow groups for quasi-projective arithmetic varieties over a field. Our definition agrees with the higher arithmetic Chow groups defined by Goncharov for projective arithmetic varieties over a field. These groups are the analogue, in the Arakelov co...

  13. Asymmetry within social groups

    DEFF Research Database (Denmark)

    Barker, Jessie; Loope, Kevin J.; Reeve, H. Kern

    2016-01-01

    Social animals vary in their ability to compete with group members over shared resources and also vary in their cooperative efforts to produce these resources. Competition among groups can promote within-group cooperation, but many existing models of intergroup cooperation do not explicitly account...

  14. Tectaria group: Arthropteris

    NARCIS (Netherlands)

    Nooteboom, H.P.; Leonardía, A.A.P.

    2012-01-01

    Holttum, R.E., Tectaria group. Flora Malesiana, Ser. II, 2 (1991) 1–132 defined this group without the genus Arthropteris. Later molecular studies indicated that this genus belongs to Tectariaceae, the Tectaria group of Holttum. The genus contains two species in Malesia. Illustration is by one

  15. Change through Group Work.

    Science.gov (United States)

    McAllan, Les; Friedman, Amy; Spears, Evans

    Perhaps the most well known treatment modalities in the field of prevention and treatment of addiction are groups. Group settings serve to bring individuals with addictions together at one time in one place to work on relevant issues together. Groups may serve as a safe environment for learning new social and relationship skills, gaining…

  16. Group Psychotherapy in Denmark.

    Science.gov (United States)

    Jørgensen, Lars Bo; Thygesen, Bente; Aagaard, Søren

    2015-10-01

    This is a short article on the history and training standards in the Institute of Group Analysis in Copenhagen (IGA-CPH). We describe theoretical orientations and influences in the long-term training program and new initiatives, like courses in mentalization-based group treatment and a dynamic short-term group therapy course, as well as research in group psychotherapy in Denmark. Some group analytic initiatives in relation to social issues and social welfare are presented, as well as initiatives concerning the school system and unemployment.

  17. Group theory I essentials

    CERN Document Server

    Milewski, Emil G

    2012-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Group Theory I includes sets and mapping, groupoids and semi-groups, groups, isomorphisms and homomorphisms, cyclic groups, the Sylow theorems, and finite p-groups.

  18. Lectures on Chevalley groups

    CERN Document Server

    Steinberg, Robert

    2016-01-01

    Robert Steinberg's Lectures on Chevalley Groups were delivered and written during the author's sabbatical visit to Yale University in the 1967-1968 academic year. The work presents the status of the theory of Chevalley groups as it was in the mid-1960s. Much of this material was instrumental in many areas of mathematics, in particular in the theory of algebraic groups and in the subsequent classification of finite groups. This posthumous edition incorporates additions and corrections prepared by the author during his retirement, including a new introductory chapter. A bibliography and editorial notes have also been added. This is a great unsurpassed introduction to the subject of Chevalley groups that influenced generations of mathematicians. I would recommend it to anybody whose interests include group theory. -Efim Zelmanov, University of California, San Diego Robert Steinberg's lectures on Chevalley groups were given at Yale University in 1967. The notes for the lectures contain a wonderful exposition of ...

  19. E-groups training

    CERN Multimedia

    HR Department

    2012-01-01

    There will be an e-groups training course on 16 March 2012 which will cover the main e-groups functionalities i.e.: creating and managing e-groups, difference between static and dynamic e-groups, configuring posting restrictions and archives, examples of where e-groups can be used in daily work. Even if you have already worked with e-groups, this may be a good opportunity to learn about the best practices and security related recommendations when using e-groups. You can find more details as well as enrolment form for the training (it’s free) here. The number of places is limited, so enrolling early is recommended.   Technical Training Tel. 72844

  20. Geometric group theory

    CERN Document Server

    Bestvina, Mladen; Vogtmann, Karen

    2014-01-01

    Geometric group theory refers to the study of discrete groups using tools from topology, geometry, dynamics and analysis. The field is evolving very rapidly and the present volume provides an introduction to and overview of various topics which have played critical roles in this evolution. The book contains lecture notes from courses given at the Park City Math Institute on Geometric Group Theory. The institute consists of a set of intensive short courses offered by leaders in the field, designed to introduce students to exciting, current research in mathematics. These lectures do not duplicate standard courses available elsewhere. The courses begin at an introductory level suitable for graduate students and lead up to currently active topics of research. The articles in this volume include introductions to CAT(0) cube complexes and groups, to modern small cancellation theory, to isometry groups of general CAT(0) spaces, and a discussion of nilpotent genus in the context of mapping class groups and CAT(0) gro...

  1. Blood groups systems

    Directory of Open Access Journals (Sweden)

    Ranadhir Mitra

    2014-01-01

    Full Text Available International Society of Blood Transfusion has recently recognized 33 blood group systems. Apart from ABO and Rhesus system, many other types of antigens have been noticed on the red cell membranes. Blood grouping and cross-matching is one of the few important tests that the anaesthesiologist orders during perioperative period. Hence, a proper understanding of the blood group system, their clinical significance, typing and cross-matching tests, and current perspective are of paramount importance to prevent transfusion-related complications. Nonetheless, the knowledge on blood group system is necessary to approach blood group-linked diseases which are still at the stage of research. This review addresses all these aspects of the blood groups system.

  2. CLASSIFICATION OF CRIMINAL GROUPS

    OpenAIRE

    Natalia Romanova

    2013-01-01

    New types of criminal groups are emerging in modern society.  These types have their special criminal subculture. The research objective is to develop new parameters of classification of modern criminal groups, create a new typology of criminal groups and identify some features of their subculture. Research methodology is based on the system approach that includes using the method of analysis of documentary sources (materials of a criminal case), method of conversations with themembers of the...

  3. Presentations of groups

    CERN Document Server

    Johnson, D L

    1997-01-01

    The aim of this book is to provide an introduction to combinatorial group theory. Any reader who has completed first courses in linear algebra, group theory and ring theory will find this book accessible. The emphasis is on computational techniques but rigorous proofs of all theorems are supplied. This new edition has been revised throughout, including new exercises and an additional chapter on proving that certain groups are infinite.

  4. What's your group worth?

    Science.gov (United States)

    Greenberg, M R

    1986-01-01

    With the advent of acquisitions and mergers of healthcare organizations, it has become necessary for medical group practices to know what they are worth. The traditional balance sheet valuation ignores what is perhaps the most important consideration of all: a group's earning potential. Discussed in this article are the many facets of the complex valuation process, including both tangible and intangible assets, and the author provides a method for adequately determining a range of values for a medical group.

  5. The maximal acceleration group

    International Nuclear Information System (INIS)

    Brandt, H.E.

    1984-01-01

    On the basis of the maximal proper acceleration relative to the vacuum, a line element and differential geometry of eight-dimensional phase space are constructed. The maximal acceleration group is defined as the mathematical transformation group under which the eight dimensional line element is invariant. In the classical limit of vanishing Planck's constant, the maximal acceleration group and geometry reduce to those of general relativity

  6. Study Groups in Denmark

    DEFF Research Database (Denmark)

    Hjorth, Poul G.

    2007-01-01

    Since 1998 European Study Groups have been held in Denmark, and Danish companies from LEGO and NOVO to very small high-tech firms have participated. I briefly describe the history, the organisation and the format of the Danish Study Groups, and highlight a few problem solutions.......Since 1998 European Study Groups have been held in Denmark, and Danish companies from LEGO and NOVO to very small high-tech firms have participated. I briefly describe the history, the organisation and the format of the Danish Study Groups, and highlight a few problem solutions....

  7. Explosive Technology Group

    Data.gov (United States)

    Federal Laboratory Consortium — The Explosive Technology Group (ETG) provides diverse technical expertise and an agile, integrated approach to solve complex challenges for all classes of energetic...

  8. The normal holonomy group

    International Nuclear Information System (INIS)

    Olmos, C.

    1990-05-01

    The restricted holonomy group of a Riemannian manifold is a compact Lie group and its representation on the tangent space is a product of irreducible representations and a trivial one. Each one of the non-trivial factors is either an orthogonal representation of a connected compact Lie group which acts transitively on the unit sphere or it is the isotropy representation of a single Riemannian symmetric space of rank ≥ 2. We prove that, all these properties are also true for the representation on the normal space of the restricted normal holonomy group of any submanifold of a space of constant curvature. 4 refs

  9. Lie groups for pedestrians

    CERN Document Server

    Lipkin, Harry J

    2002-01-01

    According to the author of this concise, high-level study, physicists often shy away from group theory, perhaps because they are unsure which parts of the subject belong to the physicist and which belong to the mathematician. However, it is possible for physicists to understand and use many techniques which have a group theoretical basis without necessarily understanding all of group theory. This book is designed to familiarize physicists with those techniques. Specifically, the author aims to show how the well-known methods of angular momentum algebra can be extended to treat other Lie group

  10. Environmental groups in politics

    International Nuclear Information System (INIS)

    Lowe, P.; Goyder, J.

    1983-01-01

    The subject is covered in chapters, entitled: introduction; (Part I) the environmental movement (environmental groups and the attentive public; the episodic development of the environmental movement; the underlying values of environmentalism; the roots of environmental concern; the social limits to growth; elite manipulation of values); the organisation of environmental groups; environmental groups in national politics; environmental groups in local politics; (Part II) the Henley Society; Friends of the Earth; the National Trust; the Royal Society for Nature Conservation; the European Environmental Bureau. (U.K.)

  11. Trajectory grouping structure

    Directory of Open Access Journals (Sweden)

    Maike Buchin

    2015-03-01

    Full Text Available The collective motion of a set of moving entities like people, birds, or other animals, is characterized by groups arising, merging, splitting, and ending. Given the trajectories of these entities, we define and model a structure that captures all of such changes using the Reeb graph, a concept from topology. The trajectory grouping structure has three natural parameters that allow more global views of the data in group size, group duration, and entity inter-distance. We prove complexity bounds on the maximum number of maximal groups that can be present, and give algorithms to compute the grouping structure efficiently. We also study how the trajectory grouping structure can be made robust, that is, how brief interruptions of groups can be disregarded in the global structure, adding a notion of persistence to the structure. Furthermore, we showcase the results of experiments using data generated by the NetLogo flocking model and from the Starkey project. The Starkey data describe the movement of elk, deer, and cattle. Although there is no ground truth for the grouping structure in this data, the experiments show that the trajectory grouping structure is plausible and has the desired effects when changing the essential parameters. Our research provides the first complete study of trajectory group evolvement, including combinatorial,algorithmic, and experimental results.

  12. Combinatorial Group Theory

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 11. Combinatorial Group Theory Group Theory via Generators and Relations. B Sury. General Article Volume 1 Issue 11 November 1996 pp 42-50. Fulltext. Click here to view fulltext PDF. Permanent link:

  13. Beam dynamics group summary

    Science.gov (United States)

    Peggs, S.

    This paper summarizes the activities of the beam dynamics working group of the LHC Collective Effects Workshop that was held in Montreux in 1994. It reviews the presentations that were made to the group, the discussions that ensued, and the consensuses that evolved.

  14. Quantum isometry groups

    Indian Academy of Sciences (India)

    Jyotishman Bhowmick

    2015-11-07

    Nov 7, 2015 ... Lots of examples computed leading to discovery of completely new kinds of quantum groups. Jyotishman Bhowmick (Indian Statistical Institute). Quantum ... on a noncommutative Riemannian manifold ( given by a spectral data ). Jyotishman Bhowmick (Indian Statistical Institute). Quantum isometry groups.

  15. Democratic Group Work

    Science.gov (United States)

    Laursen, Erik K.; Tate, Thomas F.

    2012-01-01

    For a century, democratic values have called for abandoning coercive approaches and teaching children and youth to be responsible citizens. The authors explore strategies for creating respectful environments and positive group cultures with challenging youth. They offer suggestions to adult group facilitators to support youth in developing…

  16. Group Work. Research Brief

    Science.gov (United States)

    Walker, Karen

    2010-01-01

    According to Johnson and Johnson, group work helps increase student retention and satisfaction, develops strong oral communication and social skills, as well as higher self-esteem (University of Minnesota, n.d.). Group work, when planned and implemented deliberately and thoughtfully helps students develop cognitive and leadership skills as well as…

  17. Supervision and group dynamics

    DEFF Research Database (Denmark)

    Hansen, Søren; Jensen, Lars Peter

    2004-01-01

     An important aspect of the problem based and project organized study at Aalborg University is the supervision of the project groups. At the basic education (first year) it is stated in the curriculum that part of the supervisors' job is to deal with group dynamics. This is due to the experience...

  18. Cohesion in group therapy.

    Science.gov (United States)

    Burlingame, Gary M; McClendon, Debra Theobald; Alonso, Jennifer

    2011-03-01

    Cohesion is the most popular of several relationship constructs in the clinical and empirical group therapy literature. This article reviews the most frequently cited definitions and studied measures of group cohesion. We briefly introduce a new measure, the Group Questionnaire, which elucidates group relationships by suggesting two latent factors of cohesion-relationship quality (positive bond, positive work, and negative relationship) and structure factors (member-leader and member-member). To further understand the literature, we conducted a meta-analysis examining the relationship between cohesion and treatment outcome in 40 studies. Results indicate cohesion that the weighted aggregate correlation was statistically significant with outcome r = .25, k (40), N (3,323), z = 6.54 (p cohesion outcome correlation (age, theoretical orientation, length, and size of group, as well as interventions intended to enhance cohesion). Consideration of measures and practices to improve treatment outcome are highlighted. (PsycINFO Database Record (c) 2011 APA, all rights reserved).

  19. Natural analogue working group

    International Nuclear Information System (INIS)

    Come, B.; Chapman, N.

    1986-01-01

    A Natural Analogue Working Group was established by the Commission of the European Communities in 1985. The purpose of this group is to bring together modellers with earth scientists and others, so that maximum benefit can be obtained from natural analogue studies with a view to safe geological disposal of radioactive waste. The first meeting of this group was held in Brussels from November 5 to 7, 1985. The discussions mainly concerned the identification of the modellers' needs and of the earth scientists' capacity to provide for them. Following the debates, a written statement was produced by the Group; this document forms the core of the present Report. Notes and outlines of many of the presentations made are grouped in four appendixes. The valuable contribution of all those involved in the meeting is gratefully acknowledged

  20. Ordered groups and topology

    CERN Document Server

    Clay, Adam

    2016-01-01

    This book deals with the connections between topology and ordered groups. It begins with a self-contained introduction to orderable groups and from there explores the interactions between orderability and objects in low-dimensional topology, such as knot theory, braid groups, and 3-manifolds, as well as groups of homeomorphisms and other topological structures. The book also addresses recent applications of orderability in the studies of codimension-one foliations and Heegaard-Floer homology. The use of topological methods in proving algebraic results is another feature of the book. The book was written to serve both as a textbook for graduate students, containing many exercises, and as a reference for researchers in topology, algebra, and dynamical systems. A basic background in group theory and topology is the only prerequisite for the reader.

  1. Group prenatal care.

    Science.gov (United States)

    Mazzoni, Sara E; Carter, Ebony B

    2017-06-01

    Patients participating in group prenatal care gather together with women of similar gestational ages and 2 providers who cofacilitate an educational session after a brief medical assessment. The model was first described in the 1990s by a midwife for low-risk patients and is now practiced by midwives and physicians for both low-risk patients and some high-risk patients, such as those with diabetes. The majority of literature on group prenatal care uses CenteringPregnancy, the most popular model. The first randomized controlled trial of CenteringPregnancy showed that it reduced the risk of preterm birth in low-risk women. However, recent meta-analyses have shown similar rates of preterm birth, low birthweight, and neonatal intensive care unit admission between women participating in group prenatal care and individual prenatal care. There may be subgroups, such as African Americans, who benefit from this type of prenatal care with significantly lower rates of preterm birth. Group prenatal care seems to result in increased patient satisfaction and knowledge and use of postpartum family planning as well as improved weight gain parameters. The literature is inconclusive regarding breast-feeding, stress, depression, and positive health behaviors, although it is theorized that group prenatal care positively affects these outcomes. It is unclear whether group prenatal care results in cost savings, although it may in large-volume practices if each group consists of approximately 8-10 women. Group prenatal care requires a significant paradigm shift. It can be difficult to implement and sustain. More randomized trials are needed to ascertain the true benefits of the model, best practices for implementation, and subgroups who may benefit most from this innovative way to provide prenatal care. In short, group prenatal care is an innovative and promising model with comparable pregnancy outcomes to individual prenatal care in the general population and improved outcomes in some

  2. Groups and Violence

    Science.gov (United States)

    Bhavnani, Ravi; Miodownik, Dan; Riolo, Rick

    Violence can take place along a multitude of cleavages, e.g., (1) between political groups like the Kach Movement, pitting West Bank settlers against Israeli governments supporting the land-for-peace agenda; (2) between religious groups, such as Christians and Muslims in the Nigerian cities of Jos and Kaduna; (3) along class lines, as in India between Dalits and members of the Brahminical upper castes, upwardly mobile intermediate castes, and even other backward castes such as the Thevars; and (4) between ethnic groups such as the Hutu and Tutsi, both within and across state boundaries in Rwanda and neighboring Burundi.

  3. Doing focus group research

    DEFF Research Database (Denmark)

    Lindegaard, Laura Bang

    2014-01-01

    Scholars of ethnomethodologically informed discourse studies are often sceptical of the use of interview data such as focus group data. Some scholars quite simply reject interview data with reference to a general preference for so-called naturally occurring data. Other scholars acknowledge......, not as something that pre-exists or goes beyond the situated interaction. This article, however, challenges not only the first, but also the second position and suggests that it is, after all, possible to do committedly ethnomethodological studies of focus group data that demonstrate how members of a focus group...

  4. Products of Finite Groups

    CERN Document Server

    Ballester-Bolinches, Adolfo; Asaad, Mohamed

    2010-01-01

    The study of finite groups factorised as a product of two or more subgroups has become a subject of great interest during the last years with applications not only in group theory, but also in other areas like cryptography and coding theory. It has experienced a big impulse with the introduction of some permutability conditions. The aim of this book is to gather, order, and examine part of this material, including the latest advances made, give some new approach to some topics, and present some new subjects of research in the theory of finite factorised groups.

  5. Group key management

    Energy Technology Data Exchange (ETDEWEB)

    Dunigan, T.; Cao, C.

    1997-08-01

    This report describes an architecture and implementation for doing group key management over a data communications network. The architecture describes a protocol for establishing a shared encryption key among an authenticated and authorized collection of network entities. Group access requires one or more authorization certificates. The implementation includes a simple public key and certificate infrastructure. Multicast is used for some of the key management messages. An application programming interface multiplexes key management and user application messages. An implementation using the new IP security protocols is postulated. The architecture is compared with other group key management proposals, and the performance and the limitations of the implementation are described.

  6. [A kibbutz group].

    Science.gov (United States)

    Moreau, A

    1976-01-01

    Kibbouts-group: three therapeutic or growth factors together: manual work, community life and group technics (group dynamic, Gestalt, psychodrama, bio-energetic) during two weeks. The work of growing and therapy is becoming more concrete and facilitated by the absence of difference between members and leader who share the work and the community life. Important and rapid changes are frequent: a particular attention is given to the "unmedicalisation" of symptoms (fatigue) and to the "unpsychiatrisation" of conflicts. A sample and authentical life style, together with a high degree of communication, favor the desinhibition of attitudes, the clarification of conflicts and the reenforcement of the personality.

  7. The Military Cooperation Group

    National Research Council Canada - National Science Library

    Renzi, Jr, Alfred E

    2006-01-01

    .... This thesis will describe a structure to assist with both those needs. The premise is that an expanded and improved network of US Military Groups is the weapon of choice for the war on terror, and beyond...

  8. Generalized quantum groups

    International Nuclear Information System (INIS)

    Leivo, H.P.

    1992-01-01

    The algebraic approach to quantum groups is generalized to include what may be called an anyonic symmetry, reflecting the appearance of phases more general than ±1 under transposition. (author). 6 refs

  9. Homogenous finitary symmetric groups

    Directory of Open Access Journals (Sweden)

    Otto‎. ‎H‎. Kegel

    2015-03-01

    Full Text Available We characterize strictly diagonal type of embeddings of finitary symmetric groups in terms of cardinality and the characteristic. Namely, we prove the following. Let kappa be an infinite cardinal. If G=underseti=1stackrelinftybigcupG i , where G i =FSym(kappan i , (H=underseti=1stackrelinftybigcupH i , where H i =Alt(kappan i , is a group of strictly diagonal type and xi=(p 1 ,p 2 ,ldots is an infinite sequence of primes, then G is isomorphic to the homogenous finitary symmetric group FSym(kappa(xi (H is isomorphic to the homogenous alternating group Alt(kappa(xi , where n 0 =1,n i =p 1 p 2 ldotsp i .

  10. System analysis task group

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    At this meeting, the main tasks of the study group were to discuss their task report with other task groups and to formulate the five-year research program, including next year's plans. A summary of the discussion with other task groups is presented. The general objective of the five-year program is to gather all elements necessary for a decision on the technical feasibility of the subseabed option. In addition, site selection criteria consistent with both radiological assessment and engineering capability will be produced. The task group report discussed radiological assessments, normal or base-case assessments, operational failures, low-probability postdisposal events, engineering studies, radiological criteria, legal aspects, social aspects, institutional aspects, generic comparison with other disposal options, and research priorities. The text of the report is presented along with supporting documents

  11. Homogeneous group, research, institution

    Directory of Open Access Journals (Sweden)

    Francesca Natascia Vasta

    2014-09-01

    Full Text Available The work outlines the complex connection among empiric research, therapeutic programs and host institution. It is considered the current research state in Italy. Italian research field is analyzed and critic data are outlined: lack of results regarding both the therapeutic processes and the effectiveness of eating disorders group analytic treatment. The work investigates on an eating disorders homogeneous group, led into an eating disorder outpatient service. First we present the methodological steps the research is based on including the strong connection among theory and clinical tools. Secondly clinical tools are described and the results commented. Finally, our results suggest the necessity of validating some more specifical hypothesis: verifying the relationship between clinical improvement (sense of exclusion and painful emotions reduction and specific group therapeutic processes; verifying the relationship between depressive feelings, relapses and transition trough a more differentiated groupal field.Keywords: Homogeneous group; Eating disorders; Institutional field; Therapeutic outcome

  12. Group I intron ribozymes

    DEFF Research Database (Denmark)

    Nielsen, Henrik

    2012-01-01

    Group I intron ribozymes constitute one of the main classes of ribozymes and have been a particularly important model in the discovery of key concepts in RNA biology as well as in the development of new methods. Compared to other ribozyme classes, group I intron ribozymes display considerable...... variation both in their structure and the reactions they catalyze. The best described pathway is the splicing pathway that results in a spliced out intron and ligated exons. This is paralleled by the circularization pathway that leads to full-length circular intron and un-ligated exons. In addition......, the intronic products of these pathways have the potential to integrate into targets and to form various types of circular RNA molecules. Thus, group I intron ribozymes and associated elements found within group I introns is a rich source of biological phenomena. This chapter provides a strategy and protocols...

  13. The theory of groups

    CERN Document Server

    Hall, Marshall

    2018-01-01

    This 1959 text offers an unsurpassed resource for learning and reviewing the basics of a fundamental and ever-expanding area. "This remarkable book undoubtedly will become a standard text on group theory." - American Scientist.

  14. The Transport Working Group

    CERN Document Server

    James, D

    2002-01-01

    The Transport Working Group was formed on The 10th November 1999 to study all means of transport required for the installation of the LHC machine in the existing tunnel infrastructure of the LEP. The Groups' main aim is to assess the feasibility of transport propositions offered for the handling to be carried out in the new LHC environment. The working group is composed of Mechanical Engineers, Physicists and Transport Engineers, as well as specialists who are invited to the meetings for their advice on certain aspects of the forthcoming installation. In May 2001 the group mandate was revised to include all means of transport, including surface transport as well as that required in the tunnel. The installation phase requires the handling of approximately 100,000 tonnes of delicate experimental equipment with very strict limits in terms of acceleration and shock loading. This must be installed via vertical shafts up to 140 meters deep.

  15. Fuzzy Soft Topological Groups

    Directory of Open Access Journals (Sweden)

    S. Nazmul

    2014-03-01

    Full Text Available Notions of Lowen type fuzzy soft topological space are introduced and some of their properties are established in the present paper. Besides this, a combined structure of a fuzzy soft topological space and a fuzzy soft group, which is termed here as fuzzy soft topological group is introduced. Homomorphic images and preimages are also examined. Finally, some definitions and results on fuzzy soft set are studied.

  16. Groups, rings, modules

    CERN Document Server

    Auslander, Maurice

    2014-01-01

    This classic monograph is geared toward advanced undergraduates and graduate students. The treatment presupposes some familiarity with sets, groups, rings, and vector spaces. The four-part approach begins with examinations of sets and maps, monoids and groups, categories, and rings. The second part explores unique factorization domains, general module theory, semisimple rings and modules, and Artinian rings. Part three's topics include localization and tensor products, principal ideal domains, and applications of fundamental theorem. The fourth and final part covers algebraic field extensions

  17. Parton Distributions Working Group

    International Nuclear Information System (INIS)

    Barbaro, L. de; Keller, S. A.; Kuhlmann, S.; Schellman, H.; Tung, W.-K.

    2000-01-01

    This report summarizes the activities of the Parton Distributions Working Group of the QCD and Weak Boson Physics workshop held in preparation for Run II at the Fermilab Tevatron. The main focus of this working group was to investigate the different issues associated with the development of quantitative tools to estimate parton distribution functions uncertainties. In the conclusion, the authors introduce a Manifesto that describes an optimal method for reporting data

  18. Parton Distributions Working Group

    Energy Technology Data Exchange (ETDEWEB)

    de Barbaro, L.; Keller, S. A.; Kuhlmann, S.; Schellman, H.; Tung, W.-K.

    2000-07-20

    This report summarizes the activities of the Parton Distributions Working Group of the QCD and Weak Boson Physics workshop held in preparation for Run II at the Fermilab Tevatron. The main focus of this working group was to investigate the different issues associated with the development of quantitative tools to estimate parton distribution functions uncertainties. In the conclusion, the authors introduce a Manifesto that describes an optimal method for reporting data.

  19. Group Capability Model

    Science.gov (United States)

    Olejarski, Michael; Appleton, Amy; Deltorchio, Stephen

    2009-01-01

    The Group Capability Model (GCM) is a software tool that allows an organization, from first line management to senior executive, to monitor and track the health (capability) of various groups in performing their contractual obligations. GCM calculates a Group Capability Index (GCI) by comparing actual head counts, certifications, and/or skills within a group. The model can also be used to simulate the effects of employee usage, training, and attrition on the GCI. A universal tool and common method was required due to the high risk of losing skills necessary to complete the Space Shuttle Program and meet the needs of the Constellation Program. During this transition from one space vehicle to another, the uncertainty among the critical skilled workforce is high and attrition has the potential to be unmanageable. GCM allows managers to establish requirements for their group in the form of head counts, certification requirements, or skills requirements. GCM then calculates a Group Capability Index (GCI), where a score of 1 indicates that the group is at the appropriate level; anything less than 1 indicates a potential for improvement. This shows the health of a group, both currently and over time. GCM accepts as input head count, certification needs, critical needs, competency needs, and competency critical needs. In addition, team members are categorized by years of experience, percentage of contribution, ex-members and their skills, availability, function, and in-work requirements. Outputs are several reports, including actual vs. required head count, actual vs. required certificates, CGI change over time (by month), and more. The program stores historical data for summary and historical reporting, which is done via an Excel spreadsheet that is color-coded to show health statistics at a glance. GCM has provided the Shuttle Ground Processing team with a quantifiable, repeatable approach to assessing and managing the skills in their organization. They now have a common

  20. Cyclic Soft Groups and Their Applications on Groups

    Directory of Open Access Journals (Sweden)

    Hacı Aktaş

    2014-01-01

    Full Text Available In crisp environment the notions of order of group and cyclic group are well known due to many applications. In this paper, we introduce order of the soft groups, power of the soft sets, power of the soft groups, and cyclic soft group on a group. We also investigate the relationship between cyclic soft groups and classical groups.

  1. Coordinating Group report

    International Nuclear Information System (INIS)

    1994-01-01

    In December 1992, western governors and four federal agencies established a Federal Advisory Committee to Develop On-site Innovative Technologies for Environmental Restoration and Waste Management (the DOIT Committee). The purpose of the Committee is to advise the federal government on ways to improve waste cleanup technology development and the cleanup of federal sites in the West. The Committee directed in January 1993 that information be collected from a wide range of potential stakeholders and that innovative technology candidate projects be identified, organized, set in motion, and evaluated to test new partnerships, regulatory approaches, and technologies which will lead to improve site cleanup. Five working groups were organized, one to develop broad project selection and evaluation criteria and four to focus on specific contaminant problems. A Coordinating Group comprised of working group spokesmen and federal and state representatives, was set up to plan and organize the routine functioning of these working groups. The working groups were charged with defining particular contaminant problems; identifying shortcomings in technology development, stakeholder involvement, regulatory review, and commercialization which impede the resolution of these problems; and identifying candidate sites or technologies which could serve as regional innovative demonstration projects to test new approaches to overcome the shortcomings. This report from the Coordinating Group to the DOIT Committee highlights the key findings and opportunities uncovered by these fact-finding working groups. It provides a basis from which recommendations from the DOIT Committee to the federal government can be made. It also includes observations from two public roundtables, one on commercialization and another on regulatory and institutional barriers impeding technology development and cleanup

  2. Matrix groups for undergraduates

    CERN Document Server

    Tapp, Kristopher

    2016-01-01

    Matrix groups touch an enormous spectrum of the mathematical arena. This textbook brings them into the undergraduate curriculum. It makes an excellent one-semester course for students familiar with linear and abstract algebra and prepares them for a graduate course on Lie groups. Matrix Groups for Undergraduates is concrete and example-driven, with geometric motivation and rigorous proofs. The story begins and ends with the rotations of a globe. In between, the author combines rigor and intuition to describe the basic objects of Lie theory: Lie algebras, matrix exponentiation, Lie brackets, maximal tori, homogeneous spaces, and roots. This second edition includes two new chapters that allow for an easier transition to the general theory of Lie groups. From reviews of the First Edition: This book could be used as an excellent textbook for a one semester course at university and it will prepare students for a graduate course on Lie groups, Lie algebras, etc. … The book combines an intuitive style of writing w...

  3. Summary report: injection group

    International Nuclear Information System (INIS)

    Simpson, J.; Ankenbrandt, C.; Brown, B.

    1984-01-01

    The injector group attempted to define and address several problem areas related to the SSC injector as defined in the Reference Design Study (RDS). It also considered the topic of machine utilization, particularly the question of test beam requirements. Details of the work are given in individually contributed papers, but the general concerns and consensus of the group are presented within this note. The group recognized that the injector as outlined in the RDS was developed primarily for costing estimates. As such, it was not necessarily well optimized from the standpoint of insuring the required beam properties for the SSC. On the other hand, considering the extraordinary short time in which the RDS was prepared, it is an impressive document and a good basis from which to work. Because the documented SSC performance goals are ambitious, the group sought an injector solution which would more likely guarantee that SSC performance not be limited by its injectors. As will be seen, this leads to a somewhat different solution than that described in the RDS. Furthermore, it is the consensus of the group that the new, conservative approach represents only a modest cost increase of the overall project well worth the confidence gained and the risks avoided

  4. Frailty Across Age Groups.

    Science.gov (United States)

    Pérez-Zepeda, M U; Ávila-Funes, J A; Gutiérrez-Robledo, L M; García-Peña, C

    2016-01-01

    The implementation of an aging biomarker into clinical practice is under debate. The Frailty Index is a model of deficit accumulation and has shown to accurately capture frailty in older adults, thus bridging biological with clinical practice. To describe the association of socio-demographic characteristics and the Frailty Index in different age groups (from 20 to over one hundred years) in a representative sample of Mexican subjects. Cross-sectional analysis. Nationwide and population-representative survey. Adults 20-years and older interviewed during the last Mexican National Health and Nutrition Survey (2012). A 30-item Frailty Index following standard construction was developed. Multi-level regression models were performed to test the associations of the Frailty Index with multiple socio-demographic characteristics across age groups. A total of 29,504 subjects was analyzed. The 30-item Frailty Index showed the highest scores in the older age groups, especially in women. No sociodemographic variable was associated with the Frailty Index in all the studied age groups. However, employment, economic income, and smoking status were more consistently found across age groups. To our knowledge, this is the first report describing the Frailty Index in a representative large sample of a Latin American country. Increasing age and gender were closely associated with a higher score.

  5. Focus group discussions

    CERN Document Server

    Hennink, Monique M

    2014-01-01

    The Understanding Research series focuses on the process of writing up social research. The series is broken down into three categories: Understanding Statistics, Understanding Measurement, and Understanding Qualitative Research. The books provide researchers with guides to understanding, writing, and evaluating social research. Each volume demonstrates how research should be represented, including how to write up the methodology as well as the research findings. Each volume also reviews how to appropriately evaluate published research. Focus Group Discussions addresses the challenges associated with conducting and writing focus group research. It provides detailed guidance on the practical and theoretical considerations in conducting focus group discussions including: designing the discussion guide, recruiting participants, training a field team, moderating techniques and ethical considerations. Monique Hennink describes how a methodology section is read and evaluated by others, such as journal reviewers or ...

  6. Illinois Wind Workers Group

    Energy Technology Data Exchange (ETDEWEB)

    David G. Loomis

    2012-05-28

    The Illinois Wind Working Group (IWWG) was founded in 2006 with about 15 members. It has grown to over 200 members today representing all aspects of the wind industry across the State of Illinois. In 2008, the IWWG developed a strategic plan to give direction to the group and its activities. The strategic plan identifies ways to address critical market barriers to the further penetration of wind. The key to addressing these market barriers is public education and outreach. Since Illinois has a restructured electricity market, utilities no longer have a strong control over the addition of new capacity within the state. Instead, market acceptance depends on willing landowners to lease land and willing county officials to site wind farms. Many times these groups are uninformed about the benefits of wind energy and unfamiliar with the process. Therefore, many of the project objectives focus on conferences, forum, databases and research that will allow these stakeholders to make well-educated decisions.

  7. Mobilizing Group Membership

    Directory of Open Access Journals (Sweden)

    James N. Druckman

    2013-06-01

    Full Text Available A randomized experiment was conducted to assess the effectiveness of three forms of e-mail appeals to prospective members of a newly formed professional group. The baseline condition consisted of an impersonal appeal; prospective members were sent a mass e-mail encouraging them to join. Participants in the personal condition received an e-mail with the same content, prefaced by a personal note from the group president. Participants in the social pressure condition received a personal note that called attention to the fact that they had previously signed a petition to form the professional group and urged them to make good on their earlier pledge (i.e., signing of the petition. Personalization is found to generate strong and statistically significant treatment effects. Even stronger are the effects of social pressure.

  8. Group B Strep Infection

    Science.gov (United States)

    ... feeding Lethargy (the baby is tired, hard to wake up, limp, or inactive) Difficulty breathing (with severe breathing problems, the baby’s skin, lips, or nails may turn blue) Diagnosis & Tests How will I know I have group B strep? If you’re ...

  9. Gamma gamma technology group

    Indian Academy of Sciences (India)

    The gamma gamma community are concerned that in the rush to prepare for the e+e− machine, allowance is not being made for a future upgrade of the photon linear collider. References. [1] ECFA/DESY Photon Collider Working Group: B Badelek et al, TESLA Technical. Design Report, Part VI, Chapter 1: Photon collider at ...

  10. Groups and Symmetry

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 10. Groups and Symmetry: A Guide to Discovering Mathematics. Geetha Venkataraman. Book Review Volume 4 Issue 10 October 1999 pp 91-92. Fulltext. Click here to view fulltext PDF. Permanent link:

  11. Categorization by Groups

    NARCIS (Netherlands)

    R.W. Hamilton (Rebecca); S. Puntoni (Stefano); N.T. Tavassoli (Nader)

    2006-01-01

    textabstractCategorization is a core psychological process central to consumer and managerial decision-making. While a substantial amount of research has been conducted to examine individual categorization behaviors, relatively little is known about the group categorization process. In two

  12. Unclonable Group Identification

    DEFF Research Database (Denmark)

    Damgård, Ivan Bjerre; Dupont, Kasper; Pedersen, Michael Østergaard

    2006-01-01

    We introduce and motivate the concept of unclonable group identification, that provides maximal protection against sharing of identities while still protecting the anonymity of users. We prove that the notion can be realized from any one-way function and suggest a more efficient implementation...

  13. With the Radiobiology Group

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    The Radiobiology Group carries out experiments to study the effect of radiation on living cells. The photo shows the apparatus for growing broad beans which have been irradiated by 250 GeV protons. The roots are immersed in a tank of running water (CERN Weekly Bulletin 26 January 1981 and Annual Report 1980 p. 160). Karen Panman, Marilena Streit-Bianchi, Roger Paris.

  14. Group: radiation dosimetry

    International Nuclear Information System (INIS)

    Caldas, L.V.E.

    1990-01-01

    The main activities of the radiation dosimetry group is described, including the calibration of instruments, sources and radioactive solutions and the determination of neutron flux; development, production and market dosimetric materials; development radiation sensor make the control of radiation dose received by IPEN workers; development new techniques for monitoring, etc. (C.G.C.)

  15. Working Group Report: Neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    de Gouvea, A.; Pitts, K.; Scholberg, K.; Zeller, G. P. [et al.

    2013-10-16

    This document represents the response of the Intensity Frontier Neutrino Working Group to the Snowmass charge. We summarize the current status of neutrino physics and identify many exciting future opportunities for studying the properties of neutrinos and for addressing important physics and astrophysics questions with neutrinos.

  16. Introduction to quantum groups

    International Nuclear Information System (INIS)

    Monteiro, Marco A.R.

    1994-01-01

    An elementary introduction to quantum groups is presented. The example of Universal Enveloping Algebra of deformed SU(2) is analysed in detail. It is also discussed systems made up of bosonic q-oscillators at finite temperature within the formalism of Thermo-Field Dynamics. (author). 39 refs

  17. INDEPENDENT AND GROUP LEARNING.

    Science.gov (United States)

    DICKINSON, MARIE B.

    IN CONTRAST TO THE TRADITIONAL EMPHASES ON ROTE LEARNING AND FACT ACCUMULATION, RECENT TRENDS EMERGING FROM EDUCATIONAL RESEARCH STRESS THE DEVELOPMENT OF THINKING PROCESSES SUCH AS THE ABILITY TO REASON ABSTRACTLY AND TO SYNTHESIZE. CHILDREN WORKING INDEPENDENTLY OR IN GROUPS MOVE THROUGH A DISCOVERY LEARNING CURRICULUM IN WHICH THE TEACHER…

  18. Convolution Operators on Groups

    CERN Document Server

    Derighetti, Antoine

    2011-01-01

    This volume is devoted to a systematic study of the Banach algebra of the convolution operators of a locally compact group. Inspired by classical Fourier analysis we consider operators on Lp spaces, arriving at a description of these operators and Lp versions of the theorems of Wiener and Kaplansky-Helson.

  19. Toleration, Groups, and Multiculturalism

    DEFF Research Database (Denmark)

    Lægaard, Sune

    2014-01-01

    is routinely defined as involving an objection component, a power requirement and an acceptance component. The objection and acceptance components refer to reasons or dispositions of the subjects of toleration, e.g. public authorities deciding how to act in relation to groups. The power condition refers...

  20. Anaphylaxis vulnerable groups

    African Journals Online (AJOL)

    Ehab

    Professor of Pediatric Allergy and Immunology, Ain Shams University, Cairo, Egypt. Age groups vulnerable to serious attacks of anaphylaxis include infants, teenagers, pregnant women, and the elderly. Concomitant diseases, such as severe or uncontrolled asthma, cardiovascular disease, mastocytosis or clonal mast cell ...

  1. Leukosis/Sarcoma Group

    Science.gov (United States)

    The leukosis/sarcoma (L/S) group of diseases designates a variety of transmissible benign and malignant neoplasms of chickens caused by members that belong to the family Retroviridae. Because the expansion of the literature on this disease, it is no longer feasible to cite all relevant publications ...

  2. Media Criticism Group Speech

    Science.gov (United States)

    Ramsey, E. Michele

    2004-01-01

    Objective: To integrate speaking practice with rhetorical theory. Type of speech: Persuasive. Point value: 100 points (i.e., 30 points based on peer evaluations, 30 points based on individual performance, 40 points based on the group presentation), which is 25% of course grade. Requirements: (a) References: 7-10; (b) Length: 20-30 minutes; (c)…

  3. Lectures on Lie groups

    CERN Document Server

    Hsiang, Wu-Yi

    2017-01-01

    This volume consists of nine lectures on selected topics of Lie group theory. We provide the readers a concise introduction as well as a comprehensive 'tour of revisiting' the remarkable achievements of S Lie, W Killing, É Cartan and H Weyl on structural and classification theory of semi-simple Lie groups, Lie algebras and their representations; and also the wonderful duet of Cartans' theory on Lie groups and symmetric spaces.With the benefit of retrospective hindsight, mainly inspired by the outstanding contribution of H Weyl in the special case of compact connected Lie groups, we develop the above theory via a route quite different from the original methods engaged by most other books.We begin our revisiting with the compact theory which is much simpler than that of the general semi-simple Lie theory; mainly due to the well fittings between the Frobenius-Schur character theory and the maximal tori theorem of É Cartan together with Weyl's reduction (cf. Lectures 1-4). It is a wonderful reality of the Lie t...

  4. Group theory in physics

    CERN Document Server

    Cornwell, J F

    1989-01-01

    Recent devopments, particularly in high-energy physics, have projected group theory and symmetry consideration into a central position in theoretical physics. These developments have taken physicists increasingly deeper into the fascinating world of pure mathematics. This work presents important mathematical developments of the last fifteen years in a form that is easy to comprehend and appreciate.

  5. Hunting in Groups

    Indian Academy of Sciences (India)

    IAS Admin

    [17] M Sato, Chasing and escaping by three groups of species, Physical Review E, Vol.85, p.066102, 2012. [18] K Dutta, How birds fly together: The dynamics of flocking, Resonance, Vol.15, pp.1097–1110, 2010. [19] T Vicsek et al, Novel type of phase transition in a system of self-driven particles, Physical Review Letter, ...

  6. Gartner Group reports

    CERN Document Server

    Gartner Group. Stamford, CT

    Gartner Group is the one of the leading independent providers of research and analysis material for IT professionals. Their reports provide in-depth analysis of dominant trends, companies and products. CERN has obtained a licence making these reports available online to anyone within CERN. The database contains not only current reports, updated monthly, but also some going back over a year.

  7. Lattices in group manifolds

    International Nuclear Information System (INIS)

    Lisboa, P.; Michael, C.

    1982-01-01

    We address the question of designing optimum discrete sets of points to represent numerically a continuous group manifold. We consider subsets which are extensions of the regular discrete subgroups. Applications to Monte Carlo simulation of SU(2) and SU(3) gauge theory are discussed. (orig.)

  8. Public interest group involvement

    International Nuclear Information System (INIS)

    Shelley, P.

    1986-01-01

    Including public interest groups in the siting process for nuclear waste disposal facilities is of great importance. Controversial sitings often result in litigation, but involving public interest groups early in the process will lessen the change of this. They act as surrogates for the general public and should be considered as members of the team. It is important to remember though, that all public interest groups are different. In choosing public panels such as public advisory committees, members should not be chosen on the basis of some quota. Opposition groups should not be excluded. Also, it is important to put the right person in charge of the committee. The goal of public involvement is to identify the conflicts. This must be done during the decision process, because conflicts must be known before they can be eliminated. Regarding litigation, it is important to ease through and around legal battles. If the siting process has integrity and a good faith effort has been shown, the court should uphold the effort. In addition, it is important to be negotiable and to eliminate shortcuts

  9. Tiny vampires in ancient seas: evidence for predation via perforation in fossils from the 780-740 million-year-old Chuar Group, Grand Canyon, USA.

    Science.gov (United States)

    Porter, Susannah M

    2016-05-25

    One explanation for the Early Neoproterozoic expansion of eukaryotes is the appearance of eukaryovorous predators-i.e. protists that preyed on other protists. Evidence for eukaryovory at this time, however, is indirect, based on inferences from character state reconstructions and molecular clocks, and on the presence of possible defensive structures in some protistan fossils. Here I describe 0.1-3.4 µm circular holes in seven species of organic-walled microfossils from the 780-740 million-year-old Chuar Group, Grand Canyon, Arizona, USA, that are similar to those formed today by predatory protists that perforate the walls of their prey to consume the contents inside. Although best known in the vampyrellid amoebae, this 'vampire-like' behaviour is widespread among eukaryotes, making it difficult to infer confidently the identity of the predator. Nonetheless, the identity of the prey is clear: some-and perhaps all-of the fossils are eukaryotes. These holes thus provide the oldest direct evidence for predation on eukaryotes. Larger circular and half-moon-shaped holes in vase-shaped microfossils from the upper part of the unit may also be the work of 'tiny vampires', suggesting a diversity of eukaryovorous predators lived in the ancient Chuar sea. © 2016 The Author(s).

  10. Wave grouping measures

    Energy Technology Data Exchange (ETDEWEB)

    Mansard, E.; Sand, S.E.; Klinting, P.

    1989-02-01

    There are recent indications that distinct wave groupings can be found even in deep water. The main objective has been to give a statistical description suitable for the design of coastal and offshore structures and it is undertaken to make further investigations in this field by analyzing some prototype records using the concepts of run length of high waves and spectrum of squared elevation, the limitations and performances of which in nonlinear waves will be highlighted in this study. An attempt has been made to relate this wave grouping to the surge motion of a floating structure with a simple mooring arrangement and thereby to propose a motion-based grouping measure. It appears that the observed run length statistics can be suitably described by Kimura's predictions if the records are sufficiently long. Records whose duration are equal to, or less than, 0.6 h reflect a large statistical variability in the various wave grouping measures. The filter cut-off proposed in the concept of SIWEH for the estimation of Groupiness Factor appears to be too high to give meaningful contrasts with respect to prototype values of the peakedness factors. It is therefore proposed to use the Hilbert Transform of the time series and a cut-off which is relevant to the natural period of the test structure. In the absence of information about this natural period a cut-off fc less than or equal to f/sub p//15 may work better. The motion equivalent groupiness factor concept could be used effectively to determine the critical sea state conditions to be used for testing of floating structures. The directional resolution of the sea state and theoretical formulations defining statistical variabilities caused by finite record lengths could be useful in evaluating whether the wave grouping is a linear process. (AB) 49 refs.

  11. Attraction to Group, Group Cohesiveness, and Individual Outcome: A Study of Training Groups.

    Science.gov (United States)

    Wright, Thomas L.; Duncan, Douglas

    1986-01-01

    Examined relationships between attraction to group and individual outcome in groups and between group cohesiveness and individual outcome in groups in four groups of 27 graduate students participating in a group psychotherapy experiential training program. Results revealed that attraction to group and group cohesiveness were both related to…

  12. The Areva Group

    International Nuclear Information System (INIS)

    2004-08-01

    This document provides information on the Areva Group, a world nuclear industry leader, offering solutions for nuclear power generation, electricity transmission and distribution and interconnect systems to the telecommunications, computer and automotive markets. It presents successively the front end division including the group business lines involved in producing nuclear fuel for electric power generation (uranium mining, concentration, conversion and enrichment and nuclear fuel fabrication); the reactors and services division which designs and builds PWR, BWR and research reactors; the back end division which encompasses the management of the fuel that has been used in nuclear power plants; the transmission and distribution division which provides products, systems and services to the medium and high voltage energy markets; the connectors division which designs and manufactures electrical, electronic and optical connectors, flexible micro circuitry and interconnection systems. Areva is implemented in Europe, north and south america, africa and asia-pacific. (A.L.B.)

  13. The Ombudperson Initiative Group

    CERN Multimedia

    Laura Stewart

    Following many discussions that took place at some of the ATLAS Women's Network lunch gatherings, a few ATLAS women joined forces with similarly concerned CERN staff women to form a small group last Fall to discuss the need for a CERN-wide Ombudsperson. This has since evolved into the Ombudsperson Initiative Group (OIG) currently composed of the following members: Barbro Asman, Stockholm University; Pierre Charrue, CERN AB; Anna Cook, CERN IT; Catherine Delamare, CERN and IT Ombudsperson; Paula Eerola, Lund University; Pauline Gagnon, Indiana University; Eugenia Hatziangeli, CERN AB; Doreen Klem, CERN IT; Bertrand Nicquevert, CERN TS and Laura Stewart, CERN AT. On June 12, members of the OIG met with representatives of Human Resources (HR) and the Equal Opportunity Advisory Panel (EOAP) to discuss the proposal drafted by the OIG. The meeting was very positive. Everybody agreed that the current procedures at CERN applicable in the event of conflict required a thorough review, and that a professionnally trai...

  14. The OMERACT Ultrasound Group

    DEFF Research Database (Denmark)

    Terslev, Lene; Iagnocco, Annamaria; Bruyn, George A W

    2017-01-01

    at least 1 joint abnormality versus 30% in the EA group. In HC, the findings of SH and PD were predominantly grade 1 whereas all grades were seen in the EA cohort, but SE was rare. In JIA, synovitis can be diagnosed based on B-mode findings alone because of the presence of physiological vascularization......OBJECTIVE: To provide an update from the Outcome Measures in Rheumatology (OMERACT) Ultrasound Working Group on the progress for defining ultrasound (US) minimal disease activity threshold at joint level in rheumatoid arthritis (RA) and for standardization of US application in juvenile idiopathic...... arthritis (JIA). METHODS: For minimal disease activity, healthy controls (HC) and patients with early arthritis (EA) who were naive to disease-modifying antirheumatic drugs were recruited from 2 centers. US was performed of the hands and feet, and scored semiquantitatively (0-3) for synovial hypertrophy (SH...

  15. Working group 4: Terrestrial

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    A working group at a Canada/USA symposium on climate change and the Arctic identified major concerns and issues related to terrestrial resources. The group examined the need for, and the means of, involving resource managers and users at local and territorial levels in the process of identifying and examining the impacts and consequences of climatic change. Climatic change will be important to the Arctic because of the magnitude of the change projected for northern latitudes; the apparent sensitivity of its terrestrial ecosystems, natural resources, and human support systems; and the dependence of the social, cultural, and economic welfare of Arctic communities, businesses, and industries on the health and quality of their environment. Impacts of climatic change on the physical, biological, and associated socio-economic environment are outlined. Gaps in knowledge needed to quantify these impacts are listed along with their relationships with resource management. Finally, potential actions for response and adaptation are presented

  16. Mindfulness for group facilitation

    DEFF Research Database (Denmark)

    Adriansen, Hanne Kirstine; Krohn, Simon

    2014-01-01

    thinking and ‘Eastern’ mindfulness which refers to an open, accepting state of mind, as intended with Buddhist-inspired techniques such as meditation. In this paper, we are interested in the latter type of mindfulness and demonstrate how Eastern mindfulness techniques can be used as a tool for facilitation......In this paper, we argue that mindfulness techniques can be used for enhancing the outcome of group performance. The word mindfulness has different connotations in the academic literature. Broadly speaking there is ‘mindfulness without meditation’ or ‘Western’ mindfulness which involves active....... A brief introduction to the physiology and philosophy of Eastern mindfulness constitutes the basis for the arguments of the effect of mindfulness techniques. The use of mindfulness techniques for group facilitation is novel as it changes the focus from individuals’ mindfulness practice...

  17. Communication from ST Group

    CERN Document Server

    TS Department

    2008-01-01

    Please note that owing the preparations for the Open Days, the FM Group will not able to handle specific requests for waste collection from 2nd to 6th of April, nor removal or PC transport requests between the 31 March and 11 April. We kindly ask you to plan the collection of all types of waste and any urgent transport of office furniture or PCs before 31 March. Waste collection requests must be made by contacting FM Support on 77777 or at the e-mail address mailto:Fm.Support@cern.ch; removal of office furniture or PC transport requests must be made using the EDH ‘Transport request’ form (select "Removals" or "PC transport" from the drop-down menu). For any question concerning the sorting of waste, please consult the following web site: http://dechets-waste.web.cern.ch/dechets-waste/ Thank you for your understanding and collaboration. TS/FM Group

  18. Group and representation theory

    CERN Document Server

    Vergados, J D

    2017-01-01

    This volume goes beyond the understanding of symmetries and exploits them in the study of the behavior of both classical and quantum physical systems. Thus it is important to study the symmetries described by continuous (Lie) groups of transformations. We then discuss how we get operators that form a Lie algebra. Of particular interest to physics is the representation of the elements of the algebra and the group in terms of matrices and, in particular, the irreducible representations. These representations can be identified with physical observables. This leads to the study of the classical Lie algebras, associated with unitary, unimodular, orthogonal and symplectic transformations. We also discuss some special algebras in some detail. The discussion proceeds along the lines of the Cartan-Weyl theory via the root vectors and root diagrams and, in particular, the Dynkin representation of the roots. Thus the representations are expressed in terms of weights, which are generated by the application of the elemen...

  19. Group leaders optimization algorithm

    Science.gov (United States)

    Daskin, Anmer; Kais, Sabre

    2011-03-01

    We present a new global optimization algorithm in which the influence of the leaders in social groups is used as an inspiration for the evolutionary technique which is designed into a group architecture. To demonstrate the efficiency of the method, a standard suite of single and multi-dimensional optimization functions along with the energies and the geometric structures of Lennard-Jones clusters are given as well as the application of the algorithm on quantum circuit design problems. We show that as an improvement over previous methods, the algorithm scales as N 2.5 for the Lennard-Jones clusters of N-particles. In addition, an efficient circuit design is shown for a two-qubit Grover search algorithm which is a quantum algorithm providing quadratic speedup over the classical counterpart.

  20. Metrically universal abelian groups

    Czech Academy of Sciences Publication Activity Database

    Doucha, Michal

    2017-01-01

    Roč. 369, č. 8 (2017), s. 5981-5998 ISSN 0002-9947 R&D Projects: GA AV ČR IAA100190902 Institutional support: RVO:67985840 Keywords : Abelian group Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 1.426, year: 2016 http://www.ams.org/journals/tran/2017-369-08/S0002-9947-2017-07059-8/

  1. Multibunch working group

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    The goal of this working group was to foment discussions about the use and limitations of multi-bunch, representatives from most operating or in-project synchrotron radiation sources (ALS, SPEAR, BESSY-2, SPRING-8, ANKA, DELTA, PEP-2, DIAMOND, ESRF...) have presented their experience. The discussions have been led around 3 topics: 1) resistive wall instabilities and ion instabilities, 2) higher harmonic cavities, and 3) multibunch feedback systems.

  2. Formal groups and applications

    CERN Document Server

    Hazewinkel, Michiel

    2012-01-01

    This book is a comprehensive treatment of the theory of formal groups and its numerous applications in several areas of mathematics. The seven chapters of the book present basics and main results of the theory, as well as very important applications in algebraic topology, number theory, and algebraic geometry. Each chapter ends with several pages of historical and bibliographic summary. One prerequisite for reading the book is an introductory graduate algebra course, including certain familiarity with category theory.

  3. Storage ring group summary

    International Nuclear Information System (INIS)

    King, N.M.

    1980-01-01

    The Storage Ring Group set out to identify and pursue salient problems in accelerator physics for heavy ion fusion, divorced from any particular reference design concept. However, it became apparent that some basic parameter framework was required to correlate the different study topics. As the Workshop progressed, ring parameters were modified and updated. Consequently, the accompanying papers on individual topics will be found to refer to slightly varied parameters, according to the stage at which the different problems were tackled

  4. Combinatorial group theory

    CERN Document Server

    Lyndon, Roger C

    2001-01-01

    From the reviews: "This book (...) defines the boundaries of the subject now called combinatorial group theory. (...)it is a considerable achievement to have concentrated a survey of the subject into 339 pages. This includes a substantial and useful bibliography; (over 1100 ÄitemsÜ). ...the book is a valuable and welcome addition to the literature, containing many results not previously available in a book. It will undoubtedly become a standard reference." Mathematical Reviews, AMS, 1979.

  5. PCORnet's Collaborative Research Groups.

    Science.gov (United States)

    Pletcher, Mark J; Forrest, Christopher B; Carton, Thomas W

    2018-01-01

    The Patient-Centered Outcomes Research Institute (PCORI) launched a multi-institutional "network of networks" in 2013 - Patient-Centered Clinical Research Network (PCORnet) - that is designed to conduct clinical research that is faster, less expensive, and more responsive to the information needs of patients and clinicians. To enhance cross-network and cross-institutional collaboration and catalyze the use of PCORnet, PCORI has supported formation of 11 Collaborative Research Groups focusing on specific disease types (e.g., cardiovascular health and cancer) or particular patient populations (e.g., pediatrics and health disparities). PCORnet's Collaborative Research Groups are establishing research priorities within these focus areas, establishing relationships with potential funders, and supporting development of specific research projects that will use PCORnet resources. PCORnet remains a complex, multilevel, and heterogeneous network that is still maturing and building a diverse portfolio of observational and interventional people-centered research; engaging with PCORnet can be daunting, particularly for outside investigators. We believe the Collaborative Research Groups are stimulating interest and helping investigators navigate the complexity, but only time will tell if these efforts will bear fruit in terms of funded multicenter PCORnet projects.

  6. Social group utility maximization

    CERN Document Server

    Gong, Xiaowen; Yang, Lei; Zhang, Junshan

    2014-01-01

    This SpringerBrief explains how to leverage mobile users' social relationships to improve the interactions of mobile devices in mobile networks. It develops a social group utility maximization (SGUM) framework that captures diverse social ties of mobile users and diverse physical coupling of mobile devices. Key topics include random access control, power control, spectrum access, and location privacy.This brief also investigates SGUM-based power control game and random access control game, for which it establishes the socially-aware Nash equilibrium (SNE). It then examines the critical SGUM-b

  7. Grouping Notes Through Nodes

    DEFF Research Database (Denmark)

    Dove, Graham; Abildgaard, Sille Julie Jøhnk; Biskjær, Michael Mose

    The Post-ItTM note is a frequently used, and yet seldom studied, design material. We investigate the functions Post-ItTM notes serve when providing cognitive support for creative design team practice. Our investigation considers the ways in which Post-ItTM notes function as design externalisations......, both individually and when grouped, and their role in categorisation in semantic long-term memory. To do this, we adopt a multimodal analytical approach focusing on interaction between humans, and between humans and artefacts, alongside language. We discuss in detail examples of four different...

  8. Groups and symmetry

    CERN Document Server

    Farmer, David W

    1995-01-01

    In most mathematics textbooks, the most exciting part of mathematics-the process of invention and discovery-is completely hidden from the reader. The aim of Groups and Symmetry is to change all that. By means of a series of carefully selected tasks, this book leads readers to discover some real mathematics. There are no formulas to memorize; no procedures to follow. The book is a guide: Its job is to start you in the right direction and to bring you back if you stray too far. Discovery is left to you. Suitable for a one-semester course at the beginning undergraduate level, there are no prerequ

  9. Statistical Group Comparison

    CERN Document Server

    Liao, Tim Futing

    2011-01-01

    An incomparably useful examination of statistical methods for comparisonThe nature of doing science, be it natural or social, inevitably calls for comparison. Statistical methods are at the heart of such comparison, for they not only help us gain understanding of the world around us but often define how our research is to be carried out. The need to compare between groups is best exemplified by experiments, which have clearly defined statistical methods. However, true experiments are not always possible. What complicates the matter more is a great deal of diversity in factors that are not inde

  10. Chemostratigraphy of the lower Bambuí Group, southwestern São Francisco Craton, Brazil: insights on Gondwana paleoenvironments

    Directory of Open Access Journals (Sweden)

    Matheus Kuchenbecker

    Full Text Available ABSTRACT: The Bambuí Group, the most extensive carbonate-siliciclastic cover on the São Francisco craton, has been a matter of debate because of its potential correlations to global glacial events. Unfortunately, most available chemostratigraphic data came from samples collected on surface rock exposures, ever susceptible to the aggressive chemical weathering that characterizes the southeastern Brazil. On the other hand, we present here high-resolution chemostratigraphic studies based on C, O and Sr isotopic data from 53 samples collected along a weathering-free, continuous, 175 m thick sedimentary succession. This succession was recovered by borehole drilling in the southwestern São Francisco craton, where occur the Carrancas and Sete Lagoas formations, the lowermost units of the Bambuí Group. The drill cores reveal extremely irregular contacts between the basal diamictite and its basement, an Archaean foliated granodiorite. Geochronological and sedimentological data strongly suggest that the diamictite represents a lodgement till. This glaciogenic deposit is covered by a limestone succession which starts with impure carbonates showing aragonite pseudomorph fans and thin bands of black shale. The limestone pile grades to a marl-mudstone interval, which turns to a carbonate with biological components, succeeded by stromatolitic dolomite at the top. C and O isotopic signatures (referred to V-PDB allow to the subdivision of the lower carbonate-pelite section into three intervals. The first isotopic interval corresponds to a cap carbonate, and displays negative values of δ13C (c . -4‰, and a large oscillation of the δ18O (-6 to -15‰. The Interval II shows a striking homogeneity in δ13C and δ18O, around 1‰ and -7‰, respectively. At the top, Interval III shows a large positive excursion of the δ13C (up to 8‰ and δ18O (-8 to -3‰ values. Unaltered 86Sr/87Sr ratios range from 0.7075 to 0.7077, mainly at the top of the section. The

  11. Public Participation Guide: Focus Groups

    Science.gov (United States)

    A focus group is a small group discussion with professional leadership. Focus groups are used to find out what issues are of most concern for a community or group when little or no information is available.

  12. Communication from ST Group

    CERN Document Server

    TS Department

    2008-01-01

    In order to prepare the organization of the Open Days, please note that FM Group will not able to take into account either specific requests for waste collection from 2nd to 6th of April, either removal or PC transport requests between the 31st and the 11th of March. We kindly ask you to plan the collection of any type of waste and the urgent transport of office furniture or PC before the 31st of March. Waste collection requests shall be formulated contacting FM Support at 77777 or at the email address mailto:Fm.Support@cern.ch; removal of office furniture or PC transport requests must be made using the EDH ‘Transport request’ form selecting the "Removals" or the "PC transport" category from the drop-down menu. For any question concerning the waste sorting, please consult the following web address: http://dechets-waste.web.cern.ch/dechets-waste/. Thank you for your understanding and collaboration. TS/FM Group

  13. Meningococcal group B vaccines.

    Science.gov (United States)

    Findlow, Jamie

    2013-06-01

    Meningococcal disease remains a devastating and feared infection with a significant morbidity and mortality profile. The successful impact of meningococcal capsular group C glyconconjugate vaccines introduced into the UK infant immunization schedule in 1999, has resulted in >80% of disease now being attributable to meningococcal capsular group B (MenB). MenB glyconconjugate vaccines are not immunogenic and hence, vaccine design has focused on sub-capsular antigens. Recently, a four component vaccine to combat MenB disease (4CMenB) has progressed through clinical development and was approved by the European Medicines Agency at the end of 2012. This vaccine has proven safe and immunogenic and has been predicted to provide protection against ~73% of the MenB disease from England and Wales. Recommendation/implementation of the vaccine into the UK infant schedule is currently being evaluated. 4CMenB has the potential to provide protection against a significant proportion of MenB disease in the UK which is currently unpreventable.

  14. Social group and mobbing

    Directory of Open Access Journals (Sweden)

    Baltezarević Vesna

    2009-01-01

    Full Text Available Our reality, having been subject to the numerous social crises during the last decades of the 20th century, is characterized by frequent incidences of powerlessness and alienation. The man is more frequently a subject to loneliness and overcomes the feeling of worthlessness, no matter whether he considers himself an individual or a part of a whole larger social. Such an environment leads to development of aggression in all fields of ones life. This paper has as an objective the pointing out of the mental harassment that is manifested in the working environment. There is a prevalence of mobbing cases, as a mode of pathological communication. The result of this is that a person, subjected to this kind of abuse, is soon faced with social isolation. This research also aspires to initiate the need for social groups self-organization of which victims are part of. The reaction modality of a social group directly conditions the outcome of the deliberate social drama, one is subjected to it as a result of mobbing.

  15. Group Life Insurance

    CERN Multimedia

    2013-01-01

    The CERN Administration would like to remind you that staff members and fellows have the possibility to take out a life insurance contract on favourable terms through a Group Life Insurance.   This insurance is provided by the company Helvetia and is available to you on a voluntary basis. The premium, which varies depending on the age and gender of the person insured, is calculated on the basis of the amount of the death benefit chosen by the staff member/fellow and can be purchased in slices of 10,000 CHF.    The contract normally ends at the retirement age (65/67 years) or when the staff member/fellow leaves the Organization. The premium is deducted monthly from the payroll.   Upon retirement, the staff member can opt to maintain his membership under certain conditions.   More information about Group Life Insurance can be found at: Regulations (in French) Table of premiums The Pension Fund Benefit Service &...

  16. ATLAS Detector Interface Group

    CERN Multimedia

    Mapelli, L

    Originally organised as a sub-system in the DAQ/EF-1 Prototype Project, the Detector Interface Group (DIG) was an information exchange channel between the Detector systems and the Data Acquisition to provide critical detector information for prototype design and detector integration. After the reorganisation of the Trigger/DAQ Project and of Technical Coordination, the necessity to provide an adequate context for integration of detectors with the Trigger and DAQ lead to organisation of the DIG as one of the activities of Technical Coordination. Such an organisation emphasises the ATLAS wide coordination of the Trigger and DAQ exploitation aspects, which go beyond the domain of the Trigger/DAQ project itself. As part of Technical Coordination, the DIG provides the natural environment for the common work of Trigger/DAQ and detector experts. A DIG forum for a wide discussion of all the detector and Trigger/DAQ integration issues. A more restricted DIG group for the practical organisation and implementation o...

  17. Business working group

    International Nuclear Information System (INIS)

    Doroshuk, B.W.

    2000-01-01

    The workshop of 26-27 june 2000, on nuclear power Plant LIfe Management (PLIM), also included working groups in which major issues facing PLIM activities for nuclear power plants were identified and discussed. The third group was on Business. The discussion concerned the following points: There are concerns about retaining experienced/trained personnel, and maintaining a good working relationship among them, as well as about the closure of research facilities, the reduction in staff numbers under increasing economic pressure and the lack of new nuclear power plant constructions. The marginal cost of producing electricity is lower for most existing nuclear power plants than for almost all other energy sources. Refurbishment costs are usually relatively small compared with new investments. The ongoing regulatory reform of the electricity market will bring increasing competition. Although PLIM has been carried out in many countries with favourable results, there are still uncertainties which affect business decisions regarding financial and market risks in PLIM activities. Recommendations were made. (author)

  18. Working Group Report: Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Artuso, M.; et al.,

    2013-10-18

    Sensors play a key role in detecting both charged particles and photons for all three frontiers in Particle Physics. The signals from an individual sensor that can be used include ionization deposited, phonons created, or light emitted from excitations of the material. The individual sensors are then typically arrayed for detection of individual particles or groups of particles. Mounting of new, ever higher performance experiments, often depend on advances in sensors in a range of performance characteristics. These performance metrics can include position resolution for passing particles, time resolution on particles impacting the sensor, and overall rate capabilities. In addition the feasible detector area and cost frequently provides a limit to what can be built and therefore is often another area where improvements are important. Finally, radiation tolerance is becoming a requirement in a broad array of devices. We present a status report on a broad category of sensors, including challenges for the future and work in progress to solve those challenges.

  19. Group theory in physics

    International Nuclear Information System (INIS)

    Cornwell, J.F.

    1984-01-01

    The aim of these two volumes (Vol. 1 includes chapters 1-9, Vol. 2 chapters 10-19) has been to provide a comprehensive and self-contained account of those parts of group theory that have been found to be most useful and of their main applications to physical problems. Starting with basic concepts they also include some of the more recent developments (to 1984). The areas of physics that are covered include atomic physics (chapters 1-6, 10-12), electronic energy bands in solids (chapters 1-6, 8 and 9), molecular vibrations (chapters 1, 2, 4-7), lattice vibrations in solids (chapters 1, 2, 4-9) and elementary particles (chapters 10-19). (U.K.)

  20. Optimised Renormalisation Group Flows

    CERN Document Server

    Litim, Daniel F

    2001-01-01

    Exact renormalisation group (ERG) flows interpolate between a microscopic or classical theory and the corresponding macroscopic or quantum effective theory. For most problems of physical interest, the efficiency of the ERG is constrained due to unavoidable approximations. Approximate solutions of ERG flows depend spuriously on the regularisation scheme which is determined by a regulator function. This is similar to the spurious dependence on the ultraviolet regularisation known from perturbative QCD. Providing a good control over approximated ERG flows is at the root for reliable physical predictions. We explain why the convergence of approximate solutions towards the physical theory is optimised by appropriate choices of the regulator. We study specific optimised regulators for bosonic and fermionic fields and compare the optimised ERG flows with generic ones. This is done up to second order in the derivative expansion at both vanishing and non-vanishing temperature. An optimised flow for a ``proper-time ren...

  1. Group life insurance

    CERN Multimedia

    2013-01-01

    The CERN Administration wishes to inform staff members and fellows having taken out optional life insurance under the group contract signed by CERN that the following changes to the rules and regulations entered into force on 1 January 2013:   The maximum age for an active member has been extended from 65 to 67 years. The beneficiary clause now allows insured persons to designate one or more persons of their choice to be their beneficiary(-ies), either at the time of taking out the insurance or at a later date, in which case the membership/modification form must be updated accordingly. Beneficiaries must be clearly identified (name, first name, date of birth, address).   The membership/modification form is available on the FP website: http://fp.web.cern.ch/helvetia-life-insurance For further information, please contact: Valentina Clavel (Tel. 73904) Peggy Pithioud (Tel. 72736)

  2. Quantum Secure Group Communication.

    Science.gov (United States)

    Li, Zheng-Hong; Zubairy, M Suhail; Al-Amri, M

    2018-03-01

    We propose a quantum secure group communication protocol for the purpose of sharing the same message among multiple authorized users. Our protocol can remove the need for key management that is needed for the quantum network built on quantum key distribution. Comparing with the secure quantum network based on BB84, we show our protocol is more efficient and securer. Particularly, in the security analysis, we introduce a new way of attack, i.e., the counterfactual quantum attack, which can steal information by "invisible" photons. This invisible photon can reveal a single-photon detector in the photon path without triggering the detector. Moreover, the photon can identify phase operations applied to itself, thereby stealing information. To defeat this counterfactual quantum attack, we propose a quantum multi-user authorization system. It allows us to precisely control the communication time so that the attack can not be completed in time.

  3. Graphs, groups and surfaces

    CERN Document Server

    White, AT

    1985-01-01

    The field of topological graph theory has expanded greatly in the ten years since the first edition of this book appeared. The original nine chapters of this classic work have therefore been revised and updated. Six new chapters have been added, dealing with: voltage graphs, non-orientable imbeddings, block designs associated with graph imbeddings, hypergraph imbeddings, map automorphism groups and change ringing.Thirty-two new problems have been added to this new edition, so that there are now 181 in all; 22 of these have been designated as ``difficult'''' and 9 as ``unsolved''''. Three of the four unsolved problems from the first edition have been solved in the ten years between editions; they are now marked as ``difficult''''.

  4. Group Milieu in systemic and psychodynamic group therapy

    DEFF Research Database (Denmark)

    Lau, Marianne Engelbrecht

    subscales: Cohesion (pgroup milieu were seen. The systemic group turned out to be evaluated as the most structured therapy and also...... in a randomized study of systemic versus psychodynamic group therapy, that the short-term outcome for patients who received systemic group psychotherapy was significantly better than the outcome for patients who received psychodynamic group psychotherapy. The current study assessed the group milieu in both groups....... Methods: This randomized prospective study included 106 women: 52 assigned to psychodynamic group psychotherapy and 54 assigned to systemic group psychotherapy. The Group Environment Scale (GES) was filled in the mid phase of therapy and analysed in three dimensions and 10 subscales. Results: The systemic...

  5. Group Milieu in systemic and psychodynamic group therapy

    DEFF Research Database (Denmark)

    Lau, Marianne Engelbrecht

    subscales: Cohesion (psystemic group turned out to be evaluated as the most structured therapy and also...... in a randomized study of systemic versus psychodynamic group therapy, that the short-term outcome for patients who received systemic group psychotherapy was significantly better than the outcome for patients who received psychodynamic group psychotherapy. The current study assessed the group milieu in both groups....... Methods: This randomized prospective study included 106 women: 52 assigned to psychodynamic group psychotherapy and 54 assigned to systemic group psychotherapy. The Group Environment Scale (GES) was filled in the mid phase of therapy and analysed in three dimensions and 10 subscales. Results: The systemic...

  6. Emotional collectives : How groups shape emotions and emotions shape groups

    NARCIS (Netherlands)

    van Kleef, G.A.; Fischer, A.H.

    2016-01-01

    Group settings are epicentres of emotional activity. Yet, the role of emotions in groups is poorly understood. How do group-level phenomena shape group members’ emotional experience and expression? How are emotional expressions recognised, interpreted and shared in group settings? And how do such

  7. Contrasted crustal sources as defined by whole-rock and Sr-Nd-Pb isotope geochemistry of neoproterozoic early post-collisional granitic magmatism within the Southern Brazilian Shear Belt, Camboriú, Brazil

    Science.gov (United States)

    Florisbal, Luana Moreira; de Assis Janasi, Valdecir; de Fátima Bitencourt, Maria; Stoll Nardi, Lauro Valentim; Heaman, Larry M.

    2012-11-01

    The early phase of post-collisional granitic magmatism in the Camboriú region, south Brazil, is represented by the porphyritic biotite ± hornblende Rio Pequeno Granite (RPG; 630-620 Ma) and the younger (˜610 Ma), equigranular, biotite ± muscovite Serra dos Macacos Granite (SMG). The two granite types share some geochemical characteristics, but the more felsic SMG constitutes a distinctive group not related to RPG by simple fractionation processes, as indicated by its lower FeOt, TiO2, K2O/Na2O and higher Zr Al2O3, Na2O, Ba and Sr when compared to RPG of similar SiO2 range. Sr-Nd-Pb isotopes require different sources. The SMG derives from old crustal sources, possibly related to the Paleoproterozoic protoliths of the Camboriú Complex, as indicated by strongly negative ɛNdt (-23 to -24) and unradiogenic Pb (e.g., 206Pb/204Pb = 16.0-16.3; 207Pb/204Pb = 15.3-15.4) and confirmed by previous LA-MC-ICPMS data showing dominant zircon inheritance of Archean to Paleoproterozoic age. In contrast, the RPG shows less negative ɛNdt (-12 to -15) and a distinctive zircon inheritance pattern with no traces of post-1.6 Ga sources. This is indicative of younger sources whose significance in the regional context is still unclear; some contribution of mantle-derived magmas is indicated by coeval mafic dykes and may account for some of the geochemical and isotopic characteristics of the least differentiated varieties of the RPG. The transcurrent tectonics seems to have played an essential role in the generation of mantle-derived magmas despite their emplacement within a low-strain zone. It may have facilitated their interaction with crustal melts which seem to be to a large extent the products of reworking of Paleoproterozoic orthogneisses from the Camboriú Complex.

  8. The benefit of group sparsity

    OpenAIRE

    Huang, Junzhou; Zhang, Tong

    2010-01-01

    This paper develops a theory for group Lasso using a concept called strong group sparsity. Our result shows that group Lasso is superior to standard Lasso for strongly group-sparse signals. This provides a convincing theoretical justification for using group sparse regularization when the underlying group structure is consistent with the data. Moreover, the theory predicts some limitations of the group Lasso formulation that are confirmed by simulation studies.

  9. Paleoproterozoic source contributions to the Sao Roque Group sedimentation: LA-MC-ICPMS U-Pb dating and Sm-Nd systematics of clasts from metaconglomerates of the Boturuna Formation

    Energy Technology Data Exchange (ETDEWEB)

    Henrique-Pinto, Renato; Janasi, Valdecir de Assis; Tassinari, Colombo Celso Gaeta [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Dept. de Mineralogia e Geotectonica; Simonetti, Antonio [University of Notre Dame, South Bend (United States). Dept. of Civil Engineering and Geological Sciences; Heaman, Larry Michael, E-mail: renatohp@usp.br, E-mail: vajanasi@usp.br, E-mail: ccgtassi@usp.br, E-mail: antonio.simonetti.3@nd.edu, E-mail: larry.heaman@ualberta.ca [University of Alberta, Edmonton (Canada). Dept. of Earth and Atmospheric Sciences

    2012-12-15

    The Sao Roque Group is characterized by volcano-sedimentary sequences, in which deposition probably started in the late Paleoproterozoic. U-Pb dating by LA-MC-ICPMS of zircons extracted from predominantly equigranular monzogranites clasts from Morro Doce and Morro do Polvilho regions, yield paleoproterozoic ages of 2199 {+-}8.5 Ma and 2247 {+-}13 Ma, respectively. These represent the ages for the main source of granite for the metaconglomerates from the Boturuna Formation (basal unit of Sao Roque Group). Its polycyclic history is reinforced by the presence of inherited Archean zircons (2694 {+-}29 Ma) found within the clasts. Moreover, these clasts have also been affected by the Neoproterozoic overprinting event as indicated by their lower intercept Concordia ages. Sm-Nd isotope data for the main clast varieties from the Morro Doce metaconglomerates yield T{sub DM} ages of 2.6 to 2.7 Ga, demonstrating that these granites are the recycling products of an Archean crustal component. The metaconglomerate arkosean framework yields slightly lower {epsilon}{sub Nd(t)} values than those for the clasts, indicating that a younger and/or more primitive source also contributed to the Boturuna Formation. (author)

  10. Becoming a group: value convergence and emergent work group identities.

    Science.gov (United States)

    Meeussen, Loes; Delvaux, Ellen; Phalet, Karen

    2014-06-01

    This study examines the process of group identity formation through social interaction in real-life work groups, with a focus on achievement values as content of work group identities. Extending research on social identity formation, we examined the process of value convergence as group members negotiate common group goals. Specifically, we predicted that work group members would influence each other's achievement values and that value convergence over time would underlie emergent work group identities and work group performance. Using a fully cross-lagged multilevel design with four repeated measures in 68 work groups, we find that group members' achievement values converge through mutual social influence. Moreover, multilevel polynomial regression analysis reveals that value convergence - rather than group members' initial value fit - longitudinally predicts work group identification and performance. © 2013 The British Psychological Society.

  11. The Liabilities Management Group

    International Nuclear Information System (INIS)

    Whitehead, A.W.

    1998-01-01

    The Liabilities Management Group (LMG) was initiated by DTI. It is a cooperative forum which was set up in 1995. The current participants are DTI, UKAEA, NLM (for BNFL), MOD and Magnox Electric. The LMG was initiated to produce closer cooperation between public sector liability management organizations, achieve more cost-effective management of UK nuclear liabilities and enhance development of the UK nuclear decommissioning and waste management strategy. The objectives are to compare practices between liabilities management organizations discuss the scope for collaboration identify priority areas for possible collaboration agree action plans for exploring and undertaking such collaboration.Four task forces have been formed to look at specific areas (R and D, safety, contracts, and project management) and each reports separately to the LMG. The LMG has achieved its original aim of bringing together those with public sector liability management responsibilities. All participants feel that the LMG has been useful and that it should continue. Looking to the future, there is a continuing need for the LMG to facilitate removal of barriers to the achievement of best value for money. The LMG might also consider addressing the 'business process' elements that a liability management organization must be good at in order to define best practice in these. (author)

  12. Oklo working group meeting

    International Nuclear Information System (INIS)

    Von Maravic, H.

    1993-01-01

    Natural analogue studies have been carried out for several years in the framework of the European Community's R and D programme on radioactive waste; and within its recent fourth five-year programme on 'Management and storage of radioactive waste (1990-94)' the Community is participating in the Oklo study, natural analogue for transfer processes in a geological repository. The Oklo project is coordinated by CEA-IPSN (F) and involves laboratories from several CEA directorates (IPSN, DTA and DCC) which collaborate with other institutions from France: CREGU, Nancy; CNRS, Strasbourg and ENSMD, Fontainebleau. Moreover, institutes from non-EC member States are also taking part in the Oklo study. The second joint CEC-CEA progress meeting of the Oklo Working Group was held in April 1992 in Brussels and gave the possibility of reviewing and discussing progress made since its first meeting in February 1991 at CEA in Fontenay-aux-Roses. About 40 participants from 15 laboratories and organizations coming from France, Canada, Gabon, Japan, Sweden and the USA underline the great interest in the ongoing research activities. The meeting focused on the different tasks within the CEC-CEA Oklo project concerning (i) field survey and sampling, (ii) characterization of the source term, (iii) studies of the petrographical and geochemical system, and (iv) studies of the hydrogeological system and hydrodynamic modelling. (author) 17 papers are presented

  13. Genomic ancestry and ethnoracial self-classification based on 5,871 community-dwelling Brazilians (The Epigen Initiative).

    Science.gov (United States)

    Lima-Costa, M Fernanda; Rodrigues, Laura C; Barreto, Maurício L; Gouveia, Mateus; Horta, Bernardo L; Mambrini, Juliana; Kehdy, Fernanda S G; Pereira, Alexandre; Rodrigues-Soares, Fernanda; Victora, Cesar G; Tarazona-Santos, Eduardo

    2015-04-27

    Brazil never had segregation laws defining membership of an ethnoracial group. Thus, the composition of the Brazilian population is mixed, and its ethnoracial classification is complex. Previous studies showed conflicting results on the correlation between genome ancestry and ethnoracial classification in Brazilians. We used 370,539 Single Nucleotide Polymorphisms to quantify this correlation in 5,851 community-dwelling individuals in the South (Pelotas), Southeast (Bambui) and Northeast (Salvador) Brazil. European ancestry was predominant in Pelotas and Bambui (median = 85.3% and 83.8%, respectively). African ancestry was highest in Salvador (median = 50.5%). The strength of the association between the phenotype and median proportion of African ancestry varied largely across populations, with pseudo R(2) values of 0.50 in Pelotas, 0.22 in Bambui and 0.13 in Salvador. The continuous proportion of African genomic ancestry showed a significant S-shape positive association with self-reported Blacks in the three sites, and the reverse trend was found for self reported Whites, with most consistent classifications in the extremes of the high and low proportion of African ancestry. In self-classified Mixed individuals, the predicted probability of having African ancestry was bell-shaped. Our results support the view that ethnoracial self-classification is affected by both genome ancestry and non-biological factors.

  14. Saving Face and Group Identity

    DEFF Research Database (Denmark)

    Eriksson, Tor; Mao, Lei; Villeval, Marie-Claire

    2015-01-01

    their self- but also other group members' image. This behavior is frequent even in the absence of group identity. When group identity is more salient, individuals help regardless of whether the least performer is an in-group or an out-group. This suggests that saving others' face is a strong social norm....

  15. Making Cooperative Learning Groups Work.

    Science.gov (United States)

    Hawley, James; De Jong, Cherie

    1995-01-01

    Discusses the use of cooperative-learning groups with middle school students. Describes cooperative-learning techniques, including group roles, peer evaluation, and observation and monitoring. Considers grouping options, including group size and configuration, dyads, the think-pair-share lecture, student teams achievement divisions, jigsaw groups,…

  16. Fermilab Steering Group Report

    Energy Technology Data Exchange (ETDEWEB)

    Beier, Eugene; /Pennsylvania U.; Butler, Joel; /Fermilab; Dawson, Sally; /Brookhaven; Edwards, Helen; /Fermilab; Himel, Thomas; /SLAC; Holmes, Stephen; /Fermilab; Kim, Young-Kee; /Fermilab /Chicago U.; Lankford, Andrew; /UC, Irvine; McGinnis, David; /Fermilab; Nagaitsev, Sergei; /Fermilab; Raubenheimer, Tor; /SLAC /Fermilab

    2007-01-01

    The Fermilab Steering Group has developed a plan to keep U.S. accelerator-based particle physics on the pathway to discovery, both at the Terascale with the LHC and the ILC and in the domain of neutrinos and precision physics with a high-intensity accelerator. The plan puts discovering Terascale physics with the LHC and the ILC as Fermilab's highest priority. While supporting ILC development, the plan creates opportunities for exciting science at the intensity frontier. If the ILC remains near the Global Design Effort's technically driven timeline, Fermilab would continue neutrino science with the NOVA experiment, using the NuMI (Neutrinos at the Main Injector) proton plan, scheduled to begin operating in 2011. If ILC construction must wait somewhat longer, Fermilab's plan proposes SNuMI, an upgrade of NuMI to create a more powerful neutrino beam. If the ILC start is postponed significantly, a central feature of the proposed Fermilab plan calls for building an intense proton facility, Project X, consisting of a linear accelerator with the currently planned characteristics of the ILC combined with Fermilab's existing Recycler Ring and the Main Injector accelerator. The major component of Project X is the linac. Cryomodules, radio-frequency distribution, cryogenics and instrumentation for the linac are the same as or similar to those used in the ILC at a scale of about one percent of a full ILC linac. Project X's intense proton beams would open a path to discovery in neutrino science and in precision physics with charged leptons and quarks. World-leading experiments would allow physicists to address key questions of the Quantum Universe: How did the universe come to be? Are there undiscovered principles of nature: new symmetries, new physical laws? Do all the particles and forces become one? What happened to the antimatter? Building Project X's ILC-like linac would offer substantial support for ILC development by accelerating the

  17. Linear deformations of discrete groups and constructions of multivalued groups

    International Nuclear Information System (INIS)

    Yagodovskii, Petr V

    2000-01-01

    We construct deformations of discrete multivalued groups described as special deformations of their group algebras in the class of finite-dimensional associative algebras. We show that the deformations of ordinary groups producing multivalued groups are defined by cocycles with coefficients in the group algebra of the original group and obtain classification theorems on these deformations. We indicate a connection between the linear deformations of discrete groups introduced in this paper and the well-known constructions of multivalued groups. We describe the manifold of three-dimensional associative commutative algebras with identity element, fixed basis, and a constant number of values. The group algebras of n-valued groups of order three (three-dimensional n-group algebras) form a discrete set in this manifold

  18. Topological K-Kolmogorov groups

    International Nuclear Information System (INIS)

    Abd El-Sattar, A. Dabbour.

    1987-07-01

    The idea of the K-groups was used to define K-Kolmogorov homology and cohomology (over pairs of coefficient groups) which are descriptions of certain modifications of the Kolmogorov groups. The present work is devoted to the study of the topological properties of the K-Kolmogorov groups which lie at the root of the group duality based essentially upon Pontrjagin's concept of group multiplication. 14 refs

  19. Harmonic Analysis and Group Representation

    CERN Document Server

    Figa-Talamanca, Alessandro

    2011-01-01

    This title includes: Lectures - A. Auslander, R. Tolimeri - Nilpotent groups and abelian varieties, M Cowling - Unitary and uniformly bounded representations of some simple Lie groups, M. Duflo - Construction de representations unitaires d'un groupe de Lie, R. Howe - On a notion of rank for unitary representations of the classical groups, V.S. Varadarajan - Eigenfunction expansions of semisimple Lie groups, and R. Zimmer - Ergodic theory, group representations and rigidity; and, Seminars - A. Koranyi - Some applications of Gelfand pairs in classical analysis.

  20. Platinum-group elements

    Science.gov (United States)

    Zientek, Michael L.; Loferski, Patricia J.; Parks, Heather L.; Schulte, Ruth F.; Seal, Robert R.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    The platinum-group elements (PGEs)—platinum, palladium, rhodium, ruthenium, iridium, and osmium—are metals that have similar physical and chemical properties and tend to occur together in nature. PGEs are indispensable to many industrial applications but are mined in only a few places. The availability and accessibility of PGEs could be disrupted by economic, environmental, political, and social events. The United States net import reliance as a percentage of apparent consumption is about 90 percent.PGEs have many industrial applications. They are used in catalytic converters to reduce carbon monoxide, hydrocarbon, and nitrous oxide emissions in automobile exhaust. The chemical industry requires platinum or platinum-rhodium alloys to manufacture nitric oxide, which is the raw material used to manufacture explosives, fertilizers, and nitric acid. In the petrochemical industry, platinum-supported catalysts are needed to refine crude oil and to produce aromatic compounds and high-octane gasoline. Alloys of PGEs are exceptionally hard and durable, making them the best known coating for industrial crucibles used in the manufacture of chemicals and synthetic materials. PGEs are used by the glass manufacturing industry in the production of fiberglass and flat-panel and liquid crystal displays. In the electronics industry, PGEs are used in computer hard disks, hybridized integrated circuits, and multilayer ceramic capacitors.Aside from their industrial applications, PGEs are used in such other fields as health, consumer goods, and finance. Platinum, for example, is used in medical implants, such as pacemakers, and PGEs are used in cancer-fighting drugs. Platinum alloys are an ideal choice for jewelry because of their white color, strength, and resistance to tarnish. Platinum, palladium, and rhodium in the form of coins and bars are also used as investment commodities, and various financial instruments based on the value of these PGEs are traded on major exchanges

  1. Group Leader Development: Effects of Personal Growth and Psychoeducational Groups

    Science.gov (United States)

    Ohrt, Jonathan H.; Robinson, E. H., III; Hagedorn, W. Bryce

    2013-01-01

    The purpose of this quasi-experimental study was to compare the effects of personal growth groups and psychoeducational groups on counselor education students' (n = 74) empathy and group leader self-efficacy. Additionally, we compared the degree to which participants in each group valued: (a) cohesion, (b) catharsis, and (c) insight. There were no…

  2. The path group construction of Lie group extensions

    OpenAIRE

    Vizman, Cornelia

    2007-01-01

    We present an explicit realization of abelian extensions of infinite dimensional Lie groups using abelian extensions of path groups, by generalizing Mickelsson's approach to loop groups and the approach of Losev-Moore-Nekrasov-Shatashvili to current groups. We apply our method to coupled cocycles on current Lie algebras and to Lichnerowicz cocycles on the Lie algebra of divergence free vector fields.

  3. Interagency Advanced Power Group -- Steering group meeting minutes

    Energy Technology Data Exchange (ETDEWEB)

    1993-11-18

    This document contains the draft meeting minutes of the Steering Group of the Interagency Advanced Power Group. Included are the discussions resulting from the presentation of working group reports and the results of a discussion of IAPG policies and procedures. In the appendix are the reports of the following working groups: Electrical, Mechanical, Solar, and Systems.

  4. In-group favouritism and out-group discimination in naturally occurring groups

    OpenAIRE

    Donna Harris; Klaus Abbink

    2012-01-01

    We study in-group favouritism and out-group discrimination in a multiplayer dictator game. An allocator divides a large sum of money among three groups of 20 recipients each and Self. Allocations to groups are divided equally among the group members. The three groups are supporters of the two rival political movements in Thailand (“yellow shirts†versus “red shirts†) and political neutral subjects. A control treatment with artificial groups (“group A†, “group B†, and “non-aff...

  5. Emotional collectives: How groups shape emotions and emotions shape groups.

    Science.gov (United States)

    van Kleef, Gerben A; Fischer, Agneta H

    2016-01-01

    Group settings are epicentres of emotional activity. Yet, the role of emotions in groups is poorly understood. How do group-level phenomena shape group members' emotional experience and expression? How are emotional expressions recognised, interpreted and shared in group settings? And how do such expressions influence the emotions, cognitions and behaviours of fellow group members and outside observers? To answer these and other questions, we draw on relevant theoretical perspectives (e.g., intergroup emotions theory, social appraisal theory and emotions as social information theory) and recent empirical findings regarding the role of emotions in groups. We organise our review according to two overarching themes: how groups shape emotions and how emotions shape groups. We show how novel empirical approaches break important new ground in uncovering the role of emotions in groups. Research on emotional collectives is thriving and constitutes a key to understanding the social nature of emotions.

  6. Genesis and Classification of Soils Containing Carbonates in a Toposequence of the Bambuí Group

    Directory of Open Access Journals (Sweden)

    Deyvid Diego Carvalho Maranhão

    2016-01-01

    Full Text Available ABSTRACT The Bambuí Group, formed from siliciclastic sediments deposited on an extensive epicontinental platform at the end of the Neoproterozoic era, is characterized by limestones with fine to very fine texture. Limestone-derived soils in the southeast of Tocantins state, Brazil, are less notorious than similar soils in other regions of Brazil and their characterization could contribute to the Brazilian System for Soil Classification (SiBCS. Given that little is known of these soils, despitetheir agricultural potential, the objective of this study was to characterize their properties and the processes leading to soil of genesis, and also contribute to developing the Brazilian System of Soil Classification (SiBCS. Soils profiles were located on the summit (P1, shoulder (P2, backslope (P3, and footslope (P4 of a toposequence in the municipality of Lavandeira, Tocantins. Morphological, physical, chemical, and mineralogical properties of the profiles were determined. The soils were classified as: P1 - Chernossolo Rêndzico Lítico típico (Lithic Haplustolls; P2 - Cambissolo Háplico Ta Eutrófico léptico hipocarbonático (Lithic Haplustolls; P3 - Cambissolo Háplico Carbonático léptico (Lithic Haplustepts; and P4 - Luvissolo Háplico Órtico típico (Typic Rhodustalfs. All the profiles showed high contents of silt, calcium, and magnesium, which resulted in high pH and low exchangeable aluminum content. Base saturation and calcium carbonate equivalent contents were also high, and the horizons showed dark colors due to high organic matter content, which contained humin as the dominant fraction. Mineralogical analysis of the clay fraction indicated predominance of hydroxy-interlayered vermiculite, followed by illite, kaolinite, and quartz, whereas the sand fraction exhibited reflections characteristic of the quartz mineral. Given P4 contents of calcium carbonate equivalent above 50 g kg-1 and the relevance of this feature for agriculture, we

  7. 2010 Chemical Working Group Status

    Science.gov (United States)

    Reid, Concha M.

    2010-01-01

    The Steering Group for the Interagency Advanced Power Group (IAPG) held their business meeting on November 30-December 1st in McLean, Virginia. Status reports were presented from each of the IAPG's Working Groups. These charts contain a brief summary of the IAPG Chemical Working Group's activities during 2010 and its plans for 2011.

  8. Reports of Sub-Groups

    Science.gov (United States)

    Indian Journal of Adult Education, 1975

    1975-01-01

    Sub-group proceedings at the 28th all-India Adult Education Conference held in October, 1975, are summarized. Sub-groups discussed the theme "non-formal education" as it applies to one of five population groups: school drop-outs, youth, women, farmers, and industrial workers. The sixth sub-group considered policy and financing for…

  9. Combinatorial Group Theory -42-----------------------------~-----------R ...

    Indian Academy of Sciences (India)

    GENERAL I ARTICLE. Combinatorial Group Theory. Group Theory via Generators and Relations. B Sury is with the School of Mathematics, TIFR,. Mumbai. The concept of groups surfaced with the fundamental works of the great mathematicians. Evariste Galois and Niels Henrik. Abel. The advent of group theory.

  10. Group B Streptococcus and Pregnancy

    Science.gov (United States)

    f AQ FREQUENTLY ASKED QUESTIONS FAQ105 PREGNANCY Group B Strep and Pregnancy • What is group B streptococcus (GBS)? • What does it mean to be ... a planned cesarean birth? •Glossary What is group B streptococcus (GBS)? Group B streptococcus is one of ...

  11. Embeddings of graph braid and surface groups in right-angled Artin groups and braid groups

    OpenAIRE

    Crisp, John; Wiest, Bert

    2003-01-01

    We prove by explicit construction that graph braid groups and most surface groups can be embedded in a natural way in right-angled Artin groups, and we point out some consequences of these embedding results. We also show that every right-angled Artin group can be embedded in a pure surface braid group. On the other hand, by generalising to right-angled Artin groups a result of Lyndon for free groups, we show that the Euler characteristic -1 surface group (given by the relation x^2y^2=z^2) nev...

  12. The contemporary czech art groups

    OpenAIRE

    Nývlt, Matěj

    2011-01-01

    Bachelor's thesis describes the current Czech art droups and their directly related topics. The introduction describes the general problems of creation iside the art group and puts in to historical context of development of Czech art for the last two hundred years. Next is the theme of artistic groups widened by the choice of some of the world's art groups. The current czech art groups are described in several medallions representing the youngest generation groups that are actively involved i...

  13. In situ gamma radiation measurements in the Neoproterozoic rocks ...

    Indian Academy of Sciences (India)

    to the south-west of Sirohi town (figures 1 and 2). The Sirohi region represents large scale faults and shear zones (Just et al. 2011; Pandit et al. 2011; de Wall et al. 2012, 2014) that may have served as pathways for crustal fluids that are supposed to have caused enrichment or deple- tion of radiogenic elements. Locally ...

  14. Continental rift-setting and evolution of Neoproterozoic Sindreth ...

    Indian Academy of Sciences (India)

    Stefan Schöbel

    2017-09-05

    Sep 5, 2017 ... ogy of granites and felsic rocks of the Delhi Fold Belt; Rec. Geol. Surv. India 125 21–23. Sen A, Pande K, Sheth H C, Sharma K K, Sarkar S, Dayal. A M and Mistry H 2013 An Ediacaran-Cambrian thermal imprint in Rajasthan, western India: Evidence from 40Ar-. 39Ar geochronology of the Sindreth volcanics ...

  15. The Neoproterozoic Malani magmatism of the northwestern Indian ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    The Malani rocks do not show any type of regional deformation effects. The Malanis are characterised by bimodal volcanism with ... against a plate subduction setting for their genesis. After the closure of orogenic cycles in the ... and the absence of volcanics in. Sirohi rocks make it different from the metasedi- ments of Delhi ...

  16. Zn and C Isotopic Variations Associated with Neoproterozoic Ice Ages

    Science.gov (United States)

    Thiemens, M. M.; Moynier, F.; Thiemens, M. H.; Shaheen, R.; Chong, K.; Koeberl, C.; Popp, F.; Gyollai, I.

    2012-03-01

    Analysis of Marinoan glacial deposits for C and Zn isotopes shows a correlation between heavy δ^6^6Zn to characteristic light δ^1^3C, indicative of heavy biological activity post glaciation. These measurements can be used for exobiological measurements.

  17. Preservation and fluorescence of the microfossils from Neoproterozoic Doushantuo formation.

    Science.gov (United States)

    Chi, Huimei; Feng, Man; Xiao, Zhongdang; Lu, Zuhong

    2008-04-01

    The phosphatized microfossils from Doushantuo Formation, Southeast China show us the biodiversity about 600 million years ago, which is a unique window for the evolution of the early life on earth. However, the process of phosphatic fossilization in detail still remains unknown. Here we report our study on the preservation state of the fossils by using confocal laser scanning microscopy. We found that fluorescent signal of the fossil could reflect the preservation state when compared with the transmission light microscopy. First, we found the fluorescent signal of the decayed cells of the fossil was weaker than that of the nondecayed part. Second, we found that the three-dimensional reconstruction of the fluorescent signals could help to judge the degree of mineralization of the fossil cells, compared with the observation by transmission light microscope. Third, we found that almost all of the fossil specimens we observed could fluoresce more or less when excited by laser light. Therefore, the fluorescent microscopy provides a useful method for the study of the preservation state of the phosphatic fossil cells. (c) 2007 Wiley-Liss, Inc.

  18. In situ gamma radiation measurements in the Neoproterozoic rocks ...

    Indian Academy of Sciences (India)

    with plane polars (black markings denote minerals, the red line denotes the border of the altered zone); (c) fluid infiltration into wall rocks with hydraulic fracturing (marked with a black circle), (d) photomicrograph of fluid infiltrated Erinpura. Granite (c) shows quartz microveins cross-cutting the ductile shear foliation (red lines) ...

  19. Neoproterozoic metamorphic events in the kekem area (central ...

    African Journals Online (AJOL)

    2009-06-11

    Jun 11, 2009 ... 4-3-1. Metasedimentary rocks. Representative major and trace element compositions of metasediments are given in Table 6. These rock types define a chemical trend parallel to that of average shales. (Fig 5), but with a slightly lower Al2O3/SiO2 ratio. Sillimanite-garnet-biotite gneisses display Fe2O3, MgO.

  20. The Neoproterozoic Malani magmatism of the northwestern Indian ...

    Indian Academy of Sciences (India)

    2) in India. This magmatic activity took place at ∼750Ma post-dating the Erinpura granite (850 Ma) and ended prior to Marwar Supergroup (680 Ma) sedimentation. Malani eruptions occurred mostly on land, but locally sub-aqueous conditions ...

  1. Bhima Basin, Karnataka, India uranium mineralisation in the Neoproterozoic

    International Nuclear Information System (INIS)

    Achar, K.K.; Pandit, S.A.; Natarajan, V.; Kumar, M.K.; Dwivedy, K.K.

    2001-01-01

    Based on the geological analogy of known uranium mineralisation in other Proterozoic basins of India, the Bhima basin in northern Karnataka, covering an area of 5200 sq km, was taken up for uranium exploration. An integrated approach involving exploration techniques such as terrain analysis using satellite imageries, jeep-borne radiation survey, regional hydrogeochemical sampling and ground radiometric surveys were used. In addition gamma-ray logging of borewells drilled for water have enabled delineation of subsurface mineralisation at Gogi. Uranium mineralisation is associated with: (1) altered phosphatic limestone along the cherty limestone-shale boundary as at Ukinal, (2) brecciated non-phosphatic limestone as at Gogi, and (3) basic enclaves in the basement granites, as at Gogi East. Uranium occurs essentially as adsorbed phase on limonite and absorbed in collophane in the phosphatic limestone as at Ukinal. Mineralisation at Gogi is characterised by intense fracturing and brecciation apparently related to E-W trending Kurlagere-Gogi fault and is essentially low temperature (c.200 deg. C) hydrothermal nature represented by coffinite (thin veins and globular aggregates) along with pitchblende, pyrite (both framboidal and euhedral), pyrrhotite, haematite and anatase. Mineralisation is both syngenetic - remobilised as in the phosphatic limestones (Ukinal) and epigenetic hydrothermal (Gogi). The spatial relation of the unconformity, basement faults, and uranium - bearing basic enclaves within the basement points to the importance of the unconformity as a surface for fluid transport and fixation in conducive hosts. Presence of labile uranium in the basement granites with significant groundwater anomalies (up to 309 ppb U) enhances such possibilities. (author)

  2. Continental rift-setting and evolution of Neoproterozoic Sindreth ...

    Indian Academy of Sciences (India)

    Stefan Schöbel

    2017-09-05

    Sep 5, 2017 ... These granites usually show well-preserved magmatic fab- rics; however, in the Sirohi region the granites are porphyroblastic with large zoned orthoclase grains. (several cm in size) and strongly foliated with well-developed gneissic fabric. Locally, mylonitic to ultramylonitic shear zones have also devel-.

  3. Group covariance and metrical theory

    International Nuclear Information System (INIS)

    Halpern, L.

    1983-01-01

    The a priori introduction of a Lie group of transformations into a physical theory has often proved to be useful; it usually serves to describe special simplified conditions before a general theory can be worked out. Newton's assumptions of absolute space and time are examples where the Euclidian group and translation group have been introduced. These groups were extended to the Galilei group and modified in the special theory of relativity to the Poincare group to describe physics under the given conditions covariantly in the simplest way. The criticism of the a priori character leads to the formulation of the general theory of relativity. The general metric theory does not really give preference to a particular invariance group - even the principle of equivalence can be adapted to a whole family of groups. The physical laws covariantly inserted into the metric space are however adapted to the Poincare group. 8 references

  4. Group analysis of differential equations

    CERN Document Server

    Ovsiannikov, L V

    1982-01-01

    Group Analysis of Differential Equations provides a systematic exposition of the theory of Lie groups and Lie algebras and its application to creating algorithms for solving the problems of the group analysis of differential equations.This text is organized into eight chapters. Chapters I to III describe the one-parameter group with its tangential field of vectors. The nonstandard treatment of the Banach Lie groups is reviewed in Chapter IV, including a discussion of the complete theory of Lie group transformations. Chapters V and VI cover the construction of partial solution classes for the g

  5. The influence of ethnic group composition on focus group discussions.

    Science.gov (United States)

    Greenwood, Nan; Ellmers, Theresa; Holley, Jess

    2014-09-20

    Focus groups are commonly used to explore participants' experiences in health and social care research. Although it is suggested that having demographically homogenous groups may help put participants at ease, the evidence is sparse.The aims of the paper are to: explore the impact of relative ethnic homogeneity and heterogeneity of focus group participants on the group discussions; improve understanding of homogeneity and heterogeneity in focus groups; suggest ways to operationalise concepts such as being 'more comfortable' with other focus group participants. Digitally recorded focus groups were undertaken with family carers of stroke survivors and were later transcribed and analysed using framework analysis. Groups were designated as more or less ethnically homogenous. More homogenous groups included, for example, only White British or Asian Indian participants whilst more heterogeneous groups comprised a mixture of, for example, Asian, White British and Black Caribbean participants. Forty-one carers participated in seven focus groups. Analysis revealed differences in discussions around ethnicity between the more or less ethnically homogenous groups. For example, participants in more ethnically homogenous focus groups were more likely to say ethnicity might influence perceptions of social care services. On the other hand, more heterogeneous groups emphasised similarity in carers' experiences, irrespective of ethnicity. Participants in the more homogenous groups were also more likely to make potentially controversial comments relating to ethnic differences. Additionally they appeared to be more at ease with each other discussing the topic. For example, they spontaneously mentioned ethnic differences earlier in these groups.In contrast, analysis of topics not specifically related to ethnicity, such as the difficult experiences of being a carer, produced no discernible patterns when comparing more and less homogenous focus groups. Considerations around focus group

  6. group

    African Journals Online (AJOL)

    Jane T. B, Nlandu M, Matondo M, Evelyn G. L.. Factors Influencing the Use of Traditional versus. Modern Family Planning Methods in Bas Zaire. Studies in Family Planning, November/December. 1885;16(6):332-34l. Peter W. H. A natural method of child spacing. American Journal of Obstetrics and Gynecology,. December ...

  7. group

    African Journals Online (AJOL)

    and promote family planning and child health services to ensure a healthier life for isolated communities during their integration ... traditional methods are still used as the main method of fertility regulation in African societies. The social, cultural and traditional beliefs and practices that are .... An elderly man said, "We space.

  8. Coordinated Control of Vehicle Groups

    National Research Council Canada - National Science Library

    Kumar, Vijay

    2004-01-01

    .... There are three main objectives: (1) to develop a theoretical paradigm for formalizing the concepts of a group, a team, and control of groups, with specified tasks such as exploring, mapping, searching, and transporting objects; (2...

  9. Criminal groups and criminal subculture

    OpenAIRE

    Romanova N.M.

    2013-01-01

    The paper provides a classification of criminal groups, structured by the following parameters: a) operation mode (secret/open), b) law-enforcement and administrative support (presence/absence). We describe four types of criminal groups: a) legitimized criminal organization, b) secret criminal organization engaged in illegal business, c) secret general crime group, and d) general crime group operating openly. The four types differ in the content of criminal subculture. Modern criminal subcult...

  10. Provenances and tectonic implications of Paleozoic siliciclastic rocks from the Baishuijiang Group of the southern Qinling belt, central China

    Science.gov (United States)

    Wang, Tao; Wang, Zongqi; Ma, Zhenhui; Wang, Dongsheng

    2017-05-01

    The Paleozoic Baishuijiang Group is exposed in the southern Qinling belt and consists of turbidite sediments. The provenances of the Paleozoic sedimentary rocks is constrained by the integration of major and trace elements and detrital zircon U-Pb dating, which can help to understand the connection between the provenance and the Paleozoic tectonic evolution of the Qinling orogenic belt. The sandstones and mudstones have intermediate SiO2/Al2O3 and K2O/Na2O ratios, and high Fe2O3 + MgO contents. In comparison with average upper continental crust, they show strong negative Nb-Ta and Sr anomalies, slight depletion of Zr-Hf and Th, but moderate enrichment of Sc, Ni and Cr. These rocks show LREE enrichment, and pronounced negative Eu anomalies in chondrite-normalized REE patterns, similar to post-Archean shales. The weathering trend of the sandstones and mudstones suggests andesitic and granodioritic provenances. These sediments are geochemically similar to continental island arc sediments, and therefore were probably deposited at an active continental margin. Detrital zircon U-Pb dating of five sandstones from the Baishuijiang Group yielded ages ranging from 407 to 3000 Ma, with six peaks at ca. 425, 710, 780, 930, 1800, and 2500 Ma. The youngest age peak at 425 Ma and two zircon grains with a weighted average age of 414 Ma indicate that the maximum depositional age of the Baishuijiang Group is late Paleozoic. Our new age data thus suggest that these turbidite sediments were mainly derived from the northern Qinling belt and the northern margin of the Yangtze Block. We propose that the Paleozoic sediments were deposited in an ocean basin between the northern Qinling belt and the Yangtze Block. Combined with regional geological evidences, our results indicate that there was a paleo-ocean in the Qinling orogenic belt since Neoproterozoic era. The oceanic crust was continually subducted northward, resulting in multiple accretion events from the early Paleozoic to early

  11. Relationship Groups in SNOMED CT

    NARCIS (Netherlands)

    Cornet, Ronald; Schulz, Stefan

    2009-01-01

    Relationship groups are a construct which is particular for the representation of concepts in SNOMED CT. In this paper, the July 2008 version of SNOMED CT is analyzed to determine the usage of relationship groups. Relationship groups are used with 36 out of 65 relations, playing a role in 28% of all

  12. Ability Grouping in Social Studies.

    Science.gov (United States)

    Social Education, 1992

    1992-01-01

    Presents a position statement of the National Council for the Social Studies (NCSS). Reports that the NCSS objects to ability grouping in social studies. Argues that ability grouping disadvantages minority, handicapped, and low ability students. Suggests that ability grouping undermines the democratic ideals that should be the basis of the social…

  13. Strategies for Successful Group Work

    Science.gov (United States)

    Nipp, Mary Beth; Palenque, Stephanie Maher

    2017-01-01

    The thought of group work, or CLC Groups often strikes fear and loathing in the hearts and minds of both students and instructors. According to Swan, Shen, and Hiltz (2006) collaborative work presents the possibilities of many difficulties including a largely unequal contribution of group participants, an inability of the students to manage the…

  14. Group Cooperation in Outdoor Education

    Science.gov (United States)

    Matthews, Bruce E.

    1978-01-01

    Utilizing the Beatles' Yellow Submarine fantasy (e.g., the Blue Meanies), this outdoor education program is designed for sixth graders and special education students. Activities developed at the Cortland Resident Outdoor Education Camp include a series of group stress/challenge activities to be accomplished by everyone in the group, as a group.…

  15. Diagram Techniques in Group Theory

    Science.gov (United States)

    Stedman, Geoffrey E.

    2009-09-01

    Preface; 1. Elementary examples; 2. Angular momentum coupling diagram techniques; 3. Extension to compact simple phase groups; 4. Symmetric and unitary groups; 5. Lie groups and Lie algebras; 6. Polarisation dependence of multiphoton processes; 7. Quantum field theoretic diagram techniques for atomic systems; 8. Applications; Appendix; References; Indexes.

  16. K-Kolmogorov cohomology groups

    International Nuclear Information System (INIS)

    Abd El-Sattar, A. Dabbour.

    1986-07-01

    In the present work we use the idea of K-groups to give a description of certain modification of the Kolmogorov cohomology groups for the case of a pair (G,G') of discrete coefficient groups. Their induced homomorphisms and coboundary operators are also defined, and then we study the resulting construction from the point of view of Eilenberg-Steenrod axioms. (author)

  17. Defense Mechanisms in Group Counseling.

    Science.gov (United States)

    Clark, Arthur J.

    1992-01-01

    Presents considerations and strategies for conceptualizing, recognizing, and modifying defense mechanisms through the group counseling process. Provides awareness of defense mechanisms in planning for and implementation of group counseling, describes interaction patterns for identifying defenses among group participants, and clarifies modification…

  18. Conceptualizing Group Flow: A Framework

    Science.gov (United States)

    Duncan, Jana; West, Richard E.

    2018-01-01

    This literature review discusses the similarities in main themes between Csikszentmihályi theory of individual flow and Sawyer theory of group flow, and compares Sawyer's theory with existing concepts in the literature on group work both in education and business. Because much creativity and innovation occurs within groups, understanding group…

  19. Designing for informed group formation

    DEFF Research Database (Denmark)

    Nicolajsen, Hanne Westh; Juel Jacobsen, Alice; Riis, Marianne

    2012-01-01

    A new design ―project preparation‖ preparing for the group formation in problem based project work is proposed and investigated. The main problem is to overcome group formation based on existing relations. The hypothesis is that theme development and group formation are somewhat counterproductive...

  20. Group Music Therapy for Prisoners

    DEFF Research Database (Denmark)

    Chen, Xi Jing; Hannibal, Niels; Xu, Kevin

    2014-01-01

    study aims to investigate the effectiveness of group music therapy to reduce anxiety and depression, and raise self-esteem in prisoners. One hundred and ninety two inmates from a Chinese prison will be allocated to two groups through randomisation. The experimental group will participate in biweekly...... group music therapy for 10 weeks (20 sessions) while the control group will be placed on a waitlist. Anxiety, depression and self-esteem will be measured by self-report scales three times: before, at the middle, and at the end of the intervention. Logs by the participants and their daily routine...

  1. Concave 1-norm group selection.

    Science.gov (United States)

    Jiang, Dingfeng; Huang, Jian

    2015-04-01

    Grouping structures arise naturally in many high-dimensional problems. Incorporation of such information can improve model fitting and variable selection. Existing group selection methods, such as the group Lasso, require correct membership. However, in practice it can be difficult to correctly specify group membership of all variables. Thus, it is important to develop group selection methods that are robust against group mis-specification. Also, it is desirable to select groups as well as individual variables in many applications. We propose a class of concave [Formula: see text]-norm group penalties that is robust to grouping structure and can perform bi-level selection. A coordinate descent algorithm is developed to calculate solutions of the proposed group selection method. Theoretical convergence of the algorithm is proved under certain regularity conditions. Comparison with other methods suggests the proposed method is the most robust approach under membership mis-specification. Simulation studies and real data application indicate that the [Formula: see text]-norm concave group selection approach achieves better control of false discovery rates. An R package grppenalty implementing the proposed method is available at CRAN. © Published by Oxford University Press 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  2. Group percolation in interdependent networks

    Science.gov (United States)

    Wang, Zexun; Zhou, Dong; Hu, Yanqing

    2018-03-01

    In many real network systems, nodes usually cooperate with each other and form groups to enhance their robustness to risks. This motivates us to study an alternative type of percolation, group percolation, in interdependent networks under attack. In this model, nodes belonging to the same group survive or fail together. We develop a theoretical framework for this group percolation and find that the formation of groups can improve the resilience of interdependent networks significantly. However, the percolation transition is always of first order, regardless of the distribution of group sizes. As an application, we map the interdependent networks with intersimilarity structures, which have attracted much attention recently, onto the group percolation and confirm the nonexistence of continuous phase transitions.

  3. Clifford algebras, spinors, spin groups and covering groups

    International Nuclear Information System (INIS)

    Magneville, C.; Pansart, J.P.

    1991-03-01

    The Dirac equation uses matrices named Υ matrices which are representations of general algebraic structures associated with a metric space. These algebras are the Clifford algebras. In the first past, these algebras are studied. Then the notion of spinor is developed. It is shown that Majorana and Weyl spinors only exist for some particular metric space. In the second part, Clifford and spinor groups are studied. They may be interpreted as the extension of the notion of orthogonal group for Clifford algebras and their spaces for representation. The rotation of a spinor is computed. In the last part, the connexion between the spinor groups and the Universal Covering Groups is presented [fr

  4. [Group cohesion: a concept analysis].

    Science.gov (United States)

    Lin, Yen-Ru; Chen, Yu-Jung; Tzeng, Wen-Chii; Chou, Kuei-Ru

    2007-10-01

    Group cohesion is considered an essential condition for achieving a successful treatment team. High cohesion groups more readily reach their goals, with group members also feeling more secure about their functions and contributions. In clinical practice, nurses use group teaching and group therapy to help patient and family members gain knowledge and skills related to illness treatment and recuperation. Effective group leadership helps minimize non-productive time and manpower and enhance interpersonal interaction. A further advantage of group cohesion is that the more effective administration of nursing programs that results can raise the profession level of staffs and reduce turnover. Walker and Avant (1995) employ concept analysis to use defining attributes in order to apply the same definition and communication to the same profession. The purpose of this paper was to apply this methodology to an analysis of group cohesion. Steps used include a review of the literature on conceptual definitions of group cohesion, a determination of defining attributes, model construction, identification of borderline, contrary, and related cases, and identification of antecedents and consequences and empirical tools. It is hoped that this analysis can help nursing staff to gain a better understanding of the concept of group cohesion and to apply such to clinical practice and nursing administration.

  5. Duality group actions on fermions

    International Nuclear Information System (INIS)

    Pantev, Tony; Sharpe, Eric

    2016-01-01

    In this short paper we look at the action of T-duality and string duality groups on fermions, in maximally-supersymmetric theories and related theories. Briefly, we argue that typical duality groups such as SL(2,ℤ) have sign ambiguities in their actions on fermions, and propose that pertinent duality groups be extended by ℤ 2 , to groups such as the metaplectic group. Specifically, we look at duality groups arising from mapping class groups of tori in M theory compactifications, T-duality, ten-dimensional type IIB S-duality, and (briefly) four-dimensional N=4 super Yang-Mills, and in each case, propose that the full duality group is a nontrivial ℤ 2 extension of the duality group acting on bosonic degrees of freedom, to more accurately describe possible actions on fermions. We also walk through U-duality groups for toroidal compactifications to nine, eight, and seven dimensions, which enables us to perform cross-consistency tests of these proposals.

  6. Strategic Groups: One Perspective on Integrating Strategic and Group Therapies.

    Science.gov (United States)

    Leahey, Maureen; Wallace, Evie

    1988-01-01

    Describes a short-term, strategic, solution-focused self-esteem group in an outpatient mental health setting. Discusses constructs that form foundations of both strategic and group therapies. Training, supervision, and outcome issues arising from integrating the two therapies are addressed. (Author/NB)

  7. Good for the group? Explaining apparent group-level selection

    NARCIS (Netherlands)

    Smallegange, I.M.; Egas, M.

    2015-01-01

    The idea that group selection can explain adaptive trait evolution is still controversial. Recent empirical work proposes evidence for group-level adaptation in a social spider, but the findings can also be explained from an individual-level perspective. The challenge remains to identify situations

  8. Group Journaling: A Tool for Reflection, Fun and Group Development

    Science.gov (United States)

    Asfeldt, Morten

    2012-01-01

    Personal journaling is common practice in outdoor programs and is an important means of reflection and meaning-making. For over 20 years the author has used group journals to promote reflection and understanding, raise important questions, explore difficult issues, develop writing and speaking skills, and enhance group development. In this…

  9. Group lending and the role of the group leader

    NARCIS (Netherlands)

    Eijkel, van R.; Hermes, N.; Lensink, B.W.

    2011-01-01

    This paper investigates strategic monitoring behavior within group lending. We show that monitoring efforts of group members differ in equilibrium due to the asymmetry between members in terms of future profits. In particular, we show that the entrepreneur with the highest future profits also puts

  10. Group lending and the role of the group leader

    NARCIS (Netherlands)

    van Eijkel, R.; Hermes, C.L.M.; Lensink, B.W.

    This paper investigates strategic monitoring behavior within group lending. We show that monitoring efforts of group members differ in equilibrium due to the asymmetry between members in terms of future profits. In particular, we show that the entrepreneur with the highest future profits also puts

  11. Discrepancy in abo blood grouping

    International Nuclear Information System (INIS)

    Khan, M.N.; Ahmed, Z.; Khan, T.A.

    2013-01-01

    Discrepancies in blood typing is one of the major reasons in eliciting a transfusion reaction. These discrepancies can be avoided through detailed analysis for the blood typing. Here, we report a subgroup of blood group type-B in the ABO system. Donor's blood was analyzed by employing commercial antisera for blood grouping. The results of forward (known antisera) and reverse (known antigen) reaction were not complimentary. A detailed analysis using the standard protocols by American Association of Blood Banking revealed the blood type as a variant of blood group-B instead of blood group-O. This is suggestive of the fact that blood group typing should be performed with extreme care and any divergence, if identified, should be properly resolved to avoid transfusion reactions. Moreover, a major study to determine the blood group variants in Pakistani population is needed. (author)

  12. Group Analytic Psychotherapy in Brazil.

    Science.gov (United States)

    Penna, Carla; Castanho, Pablo

    2015-10-01

    Group analytic practice in Brazil began quite early. Highly influenced by the Argentinean Pichon-Rivière, it enjoyed a major development from the 1950s to the early 1980s. Beginning in the 1970s, different factors undermined its development and eventually led to its steep decline. From the mid 1980s on, the number of people looking for either group analytic psychotherapy or group analytic training decreased considerably. Group analytic psychotherapy societies struggled to survive and most of them had to close their doors in the 1990s and the following decade. Psychiatric reform and the new public health system have stimulated a new demand for groups in Brazil. Developments in the public and not-for-profit sectors, combined with theoretical and practical research in universities, present promising new perspectives for group analytic psychotherapy in Brazil nowadays.

  13. Groups, graphs and random walks

    CERN Document Server

    Salvatori, Maura; Sava-Huss, Ecaterina

    2017-01-01

    An accessible and panoramic account of the theory of random walks on groups and graphs, stressing the strong connections of the theory with other branches of mathematics, including geometric and combinatorial group theory, potential analysis, and theoretical computer science. This volume brings together original surveys and research-expository papers from renowned and leading experts, many of whom spoke at the workshop 'Groups, Graphs and Random Walks' celebrating the sixtieth birthday of Wolfgang Woess in Cortona, Italy. Topics include: growth and amenability of groups; Schrödinger operators and symbolic dynamics; ergodic theorems; Thompson's group F; Poisson boundaries; probability theory on buildings and groups of Lie type; structure trees for edge cuts in networks; and mathematical crystallography. In what is currently a fast-growing area of mathematics, this book provides an up-to-date and valuable reference for both researchers and graduate students, from which future research activities will undoubted...

  14. Group discussion improves lie detection.

    Science.gov (United States)

    Klein, Nadav; Epley, Nicholas

    2015-06-16

    Groups of individuals can sometimes make more accurate judgments than the average individual could make alone. We tested whether this group advantage extends to lie detection, an exceptionally challenging judgment with accuracy rates rarely exceeding chance. In four experiments, we find that groups are consistently more accurate than individuals in distinguishing truths from lies, an effect that comes primarily from an increased ability to correctly identify when a person is lying. These experiments demonstrate that the group advantage in lie detection comes through the process of group discussion, and is not a product of aggregating individual opinions (a "wisdom-of-crowds" effect) or of altering response biases (such as reducing the "truth bias"). Interventions to improve lie detection typically focus on improving individual judgment, a costly and generally ineffective endeavor. Our findings suggest a cheap and simple synergistic approach of enabling group discussion before rendering a judgment.

  15. Group conflict and faculty engagement

    DEFF Research Database (Denmark)

    Selmer, Jan; Jonasson, Charlotte; Lauring, Jakob

    2013-01-01

    engagement has been argued to lead to more satisfied, more productive and healthier staff. In this study, based on a sample consisting of 489 members of multicultural university departments, we set out to investigate the relationship between trust, conflict and academic staff engagement. More specifically we...... assessed the effect of group trust, group relational conflict and group task conflict on indicators of behavioural, cognitive and emotional engagement. Our findings show a strong positive association between group trust and all academic staff engagement variables as well as a strong negative association...... between group relational conflict and all staff engagement variables. Task conflict was negatively associated with indicators of staff cognitive engagement. However, surprisingly, group trust did not have any moderating effect. Implications for educational organisation managers and policy makers...

  16. Modelling group dynamic animal movement

    DEFF Research Database (Denmark)

    Langrock, Roland; Hopcraft, J. Grant C.; Blackwell, Paul G.

    2014-01-01

    in non-ideal scenarios, we show that generally the estimation of models of this type is both feasible and ecologically informative. We illustrate the approach using real movement data from 11 reindeer (Rangifer tarandus). Results indicate a directional bias towards a group centroid for reindeer......Group dynamic movement is a fundamental aspect of many species' movements. The need to adequately model individuals' interactions with other group members has been recognised, particularly in order to differentiate the role of social forces in individual movement from environmental factors. However......, to date, practical statistical methods which can include group dynamics in animal movement models have been lacking. We consider a flexible modelling framework that distinguishes a group-level model, describing the movement of the group's centre, and an individual-level model, such that each individual...

  17. Group theory and its applications

    CERN Document Server

    Patra, Prasanta Kumar

    2018-01-01

    Every molecule possesses symmetry and hence has symmetry operations and symmetry elements. From symmetry properties of a system we can deduce its significant physical results. Consequently it is essential to operations of a system forms a group. Group theory is an abstract mathematical tool that underlies the study of symmetry and invariance. By using the concepts of symmetry and group theory, it is possible to obtain the members of complete set of known basis functions of the various irreducible representations of the group. I practice this is achieved by applying the projection operators to linear combinations of atomic orbital (LCAO) when the valence electrons are tightly bound to the ions, to orthogonalized plane waves (OPW) when valence electrons are nearly free and to the other given functions that are judged to the particular system under consideration. In solid state physics the group theory is indispensable in the context of finding the energy bands of electrons in solids. Group theory can be applied...

  18. Statistics of sunspot group clusters

    Directory of Open Access Journals (Sweden)

    Getko Ryszarda

    2013-03-01

    Full Text Available The Zubrzycki method is utilized to find all sunspot groups which are close to each other during each Carrington rotation. The sunspot group areas and their positions for the years 1874–2008 are used. The descending, the ascending and the maximum phases of solar cycles for each solar hemisphere are considered separately. To establish the size of the region D where the clusters are searched, the correlation function dependent on the distance between two groups is applied. The method estimates the weighted area of each cluster. The weights dependent on the correlation function of distances between sunspot groups created each cluster. For each cluster the weighted position is also evaluated. The weights dependent on the areas of sunspot groups created a given cluster. The number distribution of the sunspot groups created each cluster and the cluster statistics within different phases of the 11-year cycle and within all considered solar cycles are also presented.

  19. Geometric group theory an introduction

    CERN Document Server

    Löh, Clara

    2017-01-01

    Inspired by classical geometry, geometric group theory has in turn provided a variety of applications to geometry, topology, group theory, number theory and graph theory. This carefully written textbook provides a rigorous introduction to this rapidly evolving field whose methods have proven to be powerful tools in neighbouring fields such as geometric topology. Geometric group theory is the study of finitely generated groups via the geometry of their associated Cayley graphs. It turns out that the essence of the geometry of such groups is captured in the key notion of quasi-isometry, a large-scale version of isometry whose invariants include growth types, curvature conditions, boundary constructions, and amenability. This book covers the foundations of quasi-geometry of groups at an advanced undergraduate level. The subject is illustrated by many elementary examples, outlooks on applications, as well as an extensive collection of exercises.

  20. Origin of the Ediacaran Porongos Group, Dom Feliciano Belt, southern Brazilian Shield, with emphasis on whole rock and detrital zircon geochemistry and U-Pb, Lu-Hf isotopes

    Science.gov (United States)

    Pertille, Juliana; Hartmann, Léo Afraneo; Philipp, Ruy Paulo; Petry, Thales Sebben; de Carvalho Lana, Cristiano

    2015-12-01

    The Porongos Group is the major component of a fold and thrust belt located in the central portion of the Dom Feliciano Belt in the Sul-Riograndense Shield, Brazil. In this paper, the variations in composition of sediments and the depositional time are presented. Major and trace elements indicate that Porongos Group is composed mostly of immature sediments derived from intermediate felsic sources with minor contribution from mature recycled sources. U-Pb SHRIMP ages for a chlorite schist (sample 300) exhibit a proeminent population of 570-800 Ma, subordinate population of 1800-2250 Ma and minor population of 1200 Ma, whereas for a schist (sample 198) the main population is 1050-1500 and minor populations are 2040-2300 and 580-800 Ma. The ɛHf values of Neoproterozoic grains indicate variable degrees of crustal reworking (ɛHf = -18 to -4) with three main TDM model ages (2.2, 1.8, 1.5 Ga). The Paleoproterozoic grains include a few Archean (3.2-2.5 Ga) TDM ages. The trace elements of all analyzed detrital zircon grains reflect continental crust origin. According to the data set, the sediments of the Porongos Group were derived from locally eroded granitic rocks of the Dom Feliciano Belt and from the uplifted Paleoproterozoic basement (La Plata Craton). Further analytical signal and total magnetic field maps delimit regionally the shape and extension of the Porongos fold and thrust belt and includes the Capané region. We conclude that the duration of Porongos Group basin filling probably lasted from 650 to 570 Ma in a foreland tectonic setting of the Dom Feliciano Belt.

  1. Contractions of group representations. - I

    International Nuclear Information System (INIS)

    Celeghini, E.; Tarlini, M.

    1981-01-01

    A new definition of contraction as a limit on the parameters defining the basis of the space of representations is given. From the representations of the original group, those of the contracted one are directly obtained. The contraction of inner automorphisms into outer automorphisms and the splitting of one representation into representations of the same or different group are discussed and illustrated by examples. The procedure is also a technique for the study of representations of non-semi-simple groups. (author)

  2. Group decision-making: Factors that affect group effectiveness

    Directory of Open Access Journals (Sweden)

    Juliana Osmani

    2016-03-01

    Full Text Available Organizations are operating in a dynamic and turbulent environment. In these conditions, they have to make decisions for new problems or situations. Most of decisions are therefore non-programmed and unstructured, accompanied by risk and uncertainty. Moreover, the problems and situations are complex. All organizations are oriented towards group decisionmaking processes, as useful tools to cope with uncertainty and complexity. Apart from the necessity, companies are turning towards participatory processes also to benefit from the important advantages that these processes offer. Organizations have realized the importance of group decision-making processes to contribute to the creation of sustainable competitive advantages. Main objective of this paper is to show that group decision-making processes do not offer guarantee for good decisions, because the effectiveness of group is affected by many factors. So, the first thing done in this paper is discussing about the benefits and limitations that accompany the use of groups with decision-making purpose. Afterwards, we stop on the different factors that influence the group’s ability to make good decisions. The aim is to emphasize that regardless of the many advantages of groups, some factors as group size, type of communication within the group, leadership style, the norms, the differentiation of roles and statuses, cohesion and compliance degree should be the main elements to keep into consideration because they affect the effectiveness of group. In this regard, is discussed how such factors influence the quality of decision and then we try to draw some conclusions that can improve and make better and easier group decision-making processes.

  3. EDF Group - Annual Report 2013

    International Nuclear Information System (INIS)

    2014-01-01

    The EDF Group is emerging as a global leader in electricity and an industrial benchmark spanning the entire business from generation and networks to sales and marketing. The group is growing stronger and changing. A long-term vision and relentless determination to provide a modern public service underpin its robust business model. This document is EDF Group's annual report for the year 2013. It contains information about Group profile, governance, business, development strategy, sales and marketing, positions in Europe and international activities. The document comprises the Activity Report and the Sustainable Development Indicators

  4. Measuring group climate in prison

    OpenAIRE

    van der Helm, P.; Stams, G.J.; van der Laan, P.

    2011-01-01

    The present study examines the construct validity and reliability of the Prison Group Climate Instrument (PGCI) in a sample of 77 adolescents placed in a Dutch youth prison and 49 adult prisoners living in a Dutch psychiatric prison with a therapeutic living group structure. Confirmatory factor analysis of a four-factor model—with “repression,” “support,” “growth,” and “group atmosphere” as first-order factors—and “overall group climate” as a second-order factor shows an adequate fit to the d...

  5. The didactics of group work

    DEFF Research Database (Denmark)

    Christensen, Gerd

    2017-01-01

    will take its point of departure in pedagogical textbook introductions where group work is often presented as a means to learning social skills and co-workability. However, as most students and teachers know, this is not always the case. Observations of long-term group work show that this can be a tough...... experience for the students (Christensen 2013). Contrary to expectations, the group work seemed to foster anti-social behavior and development of selfish skills. The paper will therefore conclude by suggesting how the (often) laissez-faire group pedagogy, which is dominant in Denmark, could be improved...

  6. Hanford Waste Tank Grouping Study

    International Nuclear Information System (INIS)

    Remund, K.M.; Simpson, B.C.

    1996-01-01

    This letter report discusses the progress and accomplishments of the Tank Grouping Study in FY96. Forty-one single-shell tanks (SSTs) were included in the FY95. In FY96, technical enhancements were also made to data transformations and tank grouping methods. The first focus of the FY96 effort was a general tank grouping study in which the 41 SSTs were grouped into classes with similar waste properties. The second FY96 focus was a demonstration of how multivariate statistical methods can be used to help resolve tank safety issues

  7. Group supervision for general practitioners

    DEFF Research Database (Denmark)

    Galina Nielsen, Helena; Sofie Davidsen, Annette; Dalsted, Rikke

    2013-01-01

    considered important prerequisites for disclosing and discussing professional problems. CONCLUSION: The results of this study indicate that participation in a supervision group can be beneficial for maintaining and developing GPs' skills in dealing with patients with mental health problems. Group supervision......AIM: Group supervision is a sparsely researched method for professional development in general practice. The aim of this study was to explore general practitioners' (GPs') experiences of the benefits of group supervision for improving the treatment of mental disorders. METHODS: One long...

  8. Defining and Classifying Interest Groups

    DEFF Research Database (Denmark)

    Baroni, Laura; Carroll, Brendan; Chalmers, Adam

    2014-01-01

    of lobbying actors coded according to different coding schemes. We systematically assess the performance of different schemes by comparing how actor types in the different schemes differ with respect to a number of background characteristics. This is done in a two-stage approach where we first cluster actors...... in the organizational attributes of specific interest group types. As expected, our comparison of coding schemes reveals a closer link between group attributes and group type in narrower classification schemes based on group organizational characteristics than those based on a behavioral definition of lobbying....

  9. Evolutionary dynamics of group formation.

    Science.gov (United States)

    Javarone, Marco Alberto; Marinazzo, Daniele

    2017-01-01

    Group formation is a quite ubiquitous phenomenon across different animal species, whose individuals cluster together forming communities of diverse size. Previous investigations suggest that, in general, this phenomenon might have similar underlying reasons across the interested species, despite genetic and behavioral differences. For instance improving the individual safety (e.g. from predators), and increasing the probability to get food resources. Remarkably, the group size might strongly vary from species to species, e.g. shoals of fishes and herds of lions, and sometimes even within the same species, e.g. tribes and families in human societies. Here we build on previous theories stating that the dynamics of group formation may have evolutionary roots, and we explore this fascinating hypothesis from a purely theoretical perspective, with a model using the framework of Evolutionary Game Theory. In our model we hypothesize that homogeneity constitutes a fundamental ingredient in these dynamics. Accordingly, we study a population that tries to form homogeneous groups, i.e. composed of similar agents. The formation of a group can be interpreted as a strategy. Notably, agents can form a group (receiving a 'group payoff'), or can act individually (receiving an 'individual payoff'). The phase diagram of the modeled population shows a sharp transition between the 'group phase' and the 'individual phase', characterized by a critical 'individual payoff'. Our results then support the hypothesis that the phenomenon of group formation has evolutionary roots.

  10. Leadership in moving human groups.

    Directory of Open Access Journals (Sweden)

    Margarete Boos

    2014-04-01

    Full Text Available How is movement of individuals coordinated as a group? This is a fundamental question of social behaviour, encompassing phenomena such as bird flocking, fish schooling, and the innumerable activities in human groups that require people to synchronise their actions. We have developed an experimental paradigm, the HoneyComb computer-based multi-client game, to empirically investigate human movement coordination and leadership. Using economic games as a model, we set monetary incentives to motivate players on a virtual playfield to reach goals via players' movements. We asked whether (I humans coordinate their movements when information is limited to an individual group member's observation of adjacent group member motion, (II whether an informed group minority can lead an uninformed group majority to the minority's goal, and if so, (III how this minority exerts its influence. We showed that in a human group--on the basis of movement alone--a minority can successfully lead a majority. Minorities lead successfully when (a their members choose similar initial steps towards their goal field and (b they are among the first in the whole group to make a move. Using our approach, we empirically demonstrate that the rules of swarming behaviour apply to humans. Even complex human behaviour, such as leadership and directed group movement, follow simple rules that are based on visual perception of local movement.

  11. Strategic Groups and Banks’ Performance

    Directory of Open Access Journals (Sweden)

    Gregorz Halaj

    2009-06-01

    Full Text Available The theory of strategic groups predicts the existence of stable groups of companies that adopt similar business strategies. The theory also predicts that groups will differ in performance and in their reaction to external shocks. We use cluster analysis to identify strategic groups in the Polish banking sector. We find stable groups in the Polish banking sector constituted after the year 2000 following the major privatisation and ownership changes connected with transition to the mostly-privately-owned banking sector in the late 90s. Using panel regression methods we show that the allocation of banks to groups is statistically significant in explaining the profitability of banks. Thus, breaking down the banks into strategic groups and allowing for the different reaction of the groups to external shocks helps in a more accurate explanation of profits of the banking sector as a whole.Therefore, a more precise ex ante assessment of the loss absorption capabilities of banks is possible, which is crucial for an analysis of banking sector stability. However, we did not find evidence of the usefulness of strategic groups in explaining the quality of bank portfolios as measured by irregular loans over total loans, which is a more direct way to assess risks to financial stability.

  12. Stick with your group: young children's attitudes about group loyalty.

    Science.gov (United States)

    Misch, Antonia; Over, Harriet; Carpenter, Malinda

    2014-10-01

    For adults, loyalty to the group is highly valued, yet little is known about how children evaluate loyalty. We investigated children's attitudes about loyalty in a third-party context. In the first experiment, 4- and 5-year-olds watched a video of two groups competing. Two members of the losing group then spoke. The disloyal individual said she wanted to win and therefore would join the other group. The loyal individual said she also wanted to win but would stay with her group. Children were then asked five forced-choice questions about these two individuals' niceness, trustworthiness, morality, and deservingness of a reward. The 5-year-olds preferred the loyal person across all questions; results for the 4-year-olds were considerably weaker but in the same direction. The second experiment investigated the direction of the effect in 5-year-olds. In this experiment, children answered questions about either a loyal individual, a disloyal individual, or a neutral individual. Children rated both the loyal and neutral individuals more positively than the disloyal individual across a number of measures. Thus, whereas disloyal behavior is evaluated unfavorably by children, loyal behavior is the expected norm. These results suggest that, at least from 5 years of age, children understand that belonging to a group entails certain commitments. This marks an important step in their own ability to negotiate belonging and become trustworthy and reliable members of their social groups. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Summary of Research 1995, Interdisciplinary Academic Groups (Command, Control & Communications Academic Group, Electronic Warfare Academic Group, Space Systems Academic Group and Undersea Warfare Academic Group)

    OpenAIRE

    Faculty of the Academic Groups

    1995-01-01

    The views expressed in this report are those of the authors and do not reflect the official policy or position of the Department of Defense or the U.S. Government. This report contains information of research projects in the four interdisciplinary groups, Command, Control & Communications Academic Group, Electronic Warfare Academic Group, Space Systems Academic Group and Undersea Warfare Academic Group, which were carried out under funding of the Naval Postgraduate School Research...

  14. Energy Innovation. IVO group`s research and development report

    Energy Technology Data Exchange (ETDEWEB)

    Salminen, P.; Laiho, Y.; Kaikkonen, H.; Leisio, C.; Hinkkanen, S.; Fletcher, R. [eds.

    1997-11-01

    This annual booklet of the IVO Group`s research and development activities presents a number of articles, written by experts from IVO. The products described are examples of the environmentally-oriented selection made available by the IVO Group. In fact, the entire energy technology developed in Finland is environmentally oriented, if seen from the international perspective. The new business potential of environmental technology is great, and it is believed that in the year 2000, exportation of Finnish know-how in the field of energy-saving and efficiency will exceed the value of out energy imports

  15. Punctured torus groups and 2-bridge knot groups

    CERN Document Server

    Akiyoshi, Hirotaka; Wada, Masaaki; Yamashita, Yasushi

    2007-01-01

    This monograph is Part 1 of a book project intended to give a full account of Jorgensen's theory of punctured torus Kleinian groups and its generalization, with application to knot theory. Although Jorgensen's original work was not published in complete form, it has been a source of inspiration. In particular, it has motivated and guided Thurston's revolutionary study of low-dimensional geometric topology. In this monograph, we give an elementary and self-contained description of Jorgensen's theory with a complete proof. Through various informative illustrations, readers are naturally led to an intuitive, synthetic grasp of the theory, which clarifies how a very simple fuchsian group evolves into complicated Kleinian groups.

  16. 2002 annual report EDF group; 2002 rapport annuel groupe EDF

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-07-01

    This document is the 2002 annual report of Electricite de France (EdF) group, the French electric utility. Content: Introductory section (EDF at a glance, Chairman's message, 2002 Highlights); Corporate governance and Group strategy (Corporate governance, sustainable growth strategy, EDF branches); Financial performance (Reaching critical mass, Margins holding up well, Balance sheet); Human resources (Launching Group-wide synergies, Optimising human resources); Customers (Major customers, SMEs and professional customers, Local authorities, Residential customers, Ensuring quality access to electricity); Generation (A balanced energy mix, Nuclear generation, Fossil-fuelled generation, Renewable energies); Corporate social responsibility (Global and local partnerships, Promoting community development)

  17. Energy Innovation. IVO Group`s Research and Development Report

    Energy Technology Data Exchange (ETDEWEB)

    Salminen, P.; Laiho, Y.; Kaikkonen, H.; Leisio, C.; Hinkkanen, S. [eds.

    1996-11-01

    This annual booklet of the IVO Group`s research and development activities presents a number of articles, written by experts from IVO. The products described are examples of the environmentally-oriented selection made available by the IVO Group. In fact, the entire energy technology developed in Finland is environmentally oriented, if seen from the international perspective. The new business potential of environmental technology is great, and it is believed that in the year 2000, exportation of Finnish know-how in the field of energy-saving and efficiency will exceed the value of out energy imports

  18. Group Counseling for Navy Children.

    Science.gov (United States)

    Mitchum, Nancy Taylor

    1991-01-01

    Conducted six-session group counseling program for Navy children (n=22) enrolled in public schools whose fathers were on deployment. Pretest and posttest scores on the Coopersmith Self-Esteem Inventory suggest that participation in the group counseling unit positively affected self-esteem of Navy children whose fathers were on deployment. Found…

  19. All About the Grains Group

    Science.gov (United States)

    ... Grains All about the Grains Group Print Share What foods are in the Grains Group? Any food made ... Whole Grains Food Gallery Take the Grains Quiz What Is MyPlate? Food Guide History MyPlate, MyWins Fruits All About the ...

  20. Group Work with Transgender Clients

    Science.gov (United States)

    Dickey, Lore M.; Loewy, Michael I.

    2010-01-01

    Drawing on the existing literature, the authors' research and clinical experiences, and the first author's personal journey as a member and leader of the transgender community, this article offers a brief history of group work with transgender clients followed by suggestions for group work with transgender clients from a social justice…

  1. Opechowski's theorem and commutator groups

    International Nuclear Information System (INIS)

    Caride, A.O.; Zanette, S.I.

    1985-01-01

    It is shown that the conditions of application of Opechowski's theorem for double groups of subgroups of O(3) are directly associated to the structure of their commutator groups. Some characteristics of the structure of classes are also discussed. (Author) [pt

  2. Group Activities for Math Enthusiasts

    Science.gov (United States)

    Holdener, J.; Milnikel, R.

    2016-01-01

    In this article we present three group activities designed for math students: a balloon-twisting workshop, a group proof of the irrationality of p, and a game of Math Bingo. These activities have been particularly successful in building enthusiasm for mathematics and camaraderie among math faculty and students at Kenyon College.

  3. Working group report: Quantum chromodynamics

    Indian Academy of Sciences (India)

    This is the report of the subgroup QCD of Working Group-4 at WHEPP-9. We present the activities that had taken place in the subgroup and report some of the partial results arrived at following the discussion at the working group meetings. Keywords. Quantum chromodynamics; resummation; extra dimensions; multi-leg.

  4. Group theoretical methods in Physics

    International Nuclear Information System (INIS)

    Olmo, M.A. del; Santander, M.; Mateos Guilarte, J.M.

    1993-01-01

    The meeting had 102 papers. These was distributed in following areas: -Quantum groups,-Integrable systems,-Physical Applications of Group Theory,-Mathematical Results,-Geometry, Topology and Quantum Field Theory,-Super physics,-Super mathematics,-Atomic, Molecular and Condensed Matter Physics. Nuclear and Particle Physics,-Symmetry and Foundations of classical and Quantum mechanics

  5. Factorizable sheaves and quantum groups

    CERN Document Server

    Bezrukavnikov, Roman; Schechtman, Vadim

    1998-01-01

    The book is devoted to the geometrical construction of the representations of Lusztig's small quantum groups at roots of unity. These representations are realized as some spaces of vanishing cycles of perverse sheaves over configuration spaces. As an application, the bundles of conformal blocks over the moduli spaces of curves are studied. The book is intended for specialists in group representations and algebraic geometry.

  6. A Course on Topological Groups

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 8. A Course on Topological Groups - A Pellucid Little Book on Topological Groups. K Parthasarathy. Book Review Volume 2 Issue 8 August 1997 pp 82-83. Fulltext. Click here to view fulltext PDF. Permanent link:

  7. Measuring group climate in prison

    NARCIS (Netherlands)

    Peer van der Helm PhD; P.H. van der Laan; G.J.J.M. Stams

    2011-01-01

    The present study examines the construct validity and reliability of the Prison Group Climate Instrument (PGCI) in a sample of 77 adolescents placed in a Dutch youth prison and 49 adult prisoners living in a Dutch psychiatric prison with a therapeutic living group structure. Confirmatory factor

  8. Understanding Nomadic Collaborative Learning Groups

    Science.gov (United States)

    Ryberg, Thomas; Davidsen, Jacob; Hodgson, Vivien

    2018-01-01

    The paper builds on the work of Rossitto "et al." on collaborative nomadic work to develop three categories of practice of nomadic collaborative learning groups. Our study is based on interviews, workshops and observations of two undergraduate student's group practices engaged in self-organised, long-term collaborations within the frame…

  9. Challenges Facing Group Work Online

    Science.gov (United States)

    Chang, Bo; Kang, Haijun

    2016-01-01

    Online group work can be complicated because of its asynchronous characteristics and lack of physical presence, and its requirements for skills in handling technology, human relationships, and content-related tasks. This study focuses on the administrative, logistical and relationship-related challenges in online group work. Challenges in areas…

  10. The Globalization of Cooperative Groups.

    Science.gov (United States)

    Valdivieso, Manuel; Corn, Benjamin W; Dancey, Janet E; Wickerham, D Lawrence; Horvath, L Elise; Perez, Edith A; Urton, Alison; Cronin, Walter M; Field, Erica; Lackey, Evonne; Blanke, Charles D

    2015-10-01

    The National Cancer Institute (NCI)-supported adult cooperative oncology research groups (now officially Network groups) have a longstanding history of participating in international collaborations throughout the world. Most frequently, the US-based cooperative groups work reciprocally with the Canadian national adult cancer clinical trial group, NCIC CTG (previously the National Cancer Institute of Canada Clinical Trials Group). Thus, Canada is the largest contributor to cooperative groups based in the United States, and vice versa. Although international collaborations have many benefits, they are most frequently utilized to enhance patient accrual to large phase III trials originating in the United States or Canada. Within the cooperative group setting, adequate attention has not been given to the study of cancers that are unique to countries outside the United States and Canada, such as those frequently associated with infections in Latin America, Asia, and Africa. Global collaborations are limited by a number of barriers, some of which are unique to the countries involved, while others are related to financial support and to US policies that restrict drug distribution outside the United States. This article serves to detail the cooperative group experience in international research and describe how international collaboration in cancer clinical trials is a promising and important area that requires greater consideration in the future. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Focus groups as anticipatory methodology

    NARCIS (Netherlands)

    Macnaghten, Phil

    2017-01-01

    Focus group practitioners have tended to emphasize the capacity of the methodology for exploring how people think about topics that are familiar and that have some grounding in everyday experience. Less articulated in the literature is the role of focus groups as an anticipatory methodology, as a

  12. My Career: Group Fitness Instructor

    Science.gov (United States)

    Green, Kathleen

    2013-01-01

    This article presents an interview with Tammy Kenney, who teaches a yoga-Pilates class in several different gyms. In this interview, Kenney talks about her career as a group fitness instructor and gives her best advice for someone who wants to teach group fitness.

  13. Working group report: Quantum chromodynamics

    Indian Academy of Sciences (India)

    Abstract. This is the report of the QCD working sub-group at WHEPP-8 which was part of the QCD and QGP working group. Discussion and work on some aspects of resummation and parton distribution are reported. Keywords. Quantum chromodynamics; resummation; polarised scattering; parton dis- tributions. PACS No.

  14. Working group report: Quantum chromodynamics

    Indian Academy of Sciences (India)

    The participants of the QCD working sub-group are: Rahul Basu, D Indumathi,. E Laenen, Swapan Majhi, Prakash Mathews, Anuradha Misra, Asmita Mukherjee,. R Ratabole, V Ravindran and W Vogelsang. The main focus of this working group had been to concentrate on some issues in resummation which are essential to ...

  15. Groups and Geometries : Siena Conference

    CERN Document Server

    Kantor, William; Lunardon, Guglielmo; Pasini, Antonio; Tamburini, Maria

    1998-01-01

    On September 1-7, 1996 a conference on Groups and Geometries took place in lovely Siena, Italy. It brought together experts and interested mathematicians from numerous countries. The scientific program centered around invited exposi­ tory lectures; there also were shorter research announcements, including talks by younger researchers. The conference concerned a broad range of topics in group theory and geometry, with emphasis on recent results and open problems. Special attention was drawn to the interplay between group-theoretic methods and geometric and combinatorial ones. Expanded versions of many of the talks appear in these Proceedings. This volume is intended to provide a stimulating collection of themes for a broad range of algebraists and geometers. Among those themes, represented within the conference or these Proceedings, are aspects of the following: 1. the classification of finite simple groups, 2. the structure and properties of groups of Lie type over finite and algebraically closed fields of f...

  16. Stereotypes of Norwegian social groups.

    Science.gov (United States)

    Bye, Hege H; Herrebrøden, Henrik; Hjetland, Gunnhild J; Røyset, Guro Ø; Westby, Linda L

    2014-10-01

    We present a pilot study and two main studies that address the nature of stereotypes of social groups in Norway within the framework of the Stereotype Content Model (SCM). The first study focused on stereotypes of a wide range of groups across categories such as gender, age, religious conviction, socioeconomic and health status. The second study focused on stereotypes of immigrant groups. Participants (n = 244 and n = 63, respectively) rated the groups on perceived warmth, competence, status, and competition. Results from both studies support the applicability of the SCM in Norway and provides a unique insight into stereotypes of Norwegian social groups. © 2014 The Authors. Scandinavian Journal of Psychology published by Scandinavian Psychological Associations and John Wiley & Sons Ltd.

  17. Understanding nomadic collaborative learning groups

    DEFF Research Database (Denmark)

    Ryberg, Thomas; Davidsen, Jacob; Hodgson, Vivien

    2018-01-01

    -term collaborations within the frame of Problem and Project Based Learning. By analysing the patterns of nomadic collaborative learning we identify and discuss how the two groups of students incorporate mobile and digital technologies as well as physical and/or non-digital technologies into their group work......The paper builds on the work of Rossitto et al. on collaborative nomadic work to develop three categories of practice of nomadic collaborative learning groups. Our study is based on interviews, workshops and observations of two undergraduate student's group practices engaged in self-organised, long....... Specifically, we identify the following categories of nomadic collaborative learning practices: “orchestration of work phases, spaces and activities,” “the orchestration of multiple technologies” and “orchestration of togetherness.” We found that for both groups of students there was a fluidity, situatedness...

  18. Constraints of detrital zircon U-Pb ages and Hf isotopes on the provenance of the Triassic Yidun Group and tectonic evolution of the Yidun Terrane, Eastern Tibet

    Science.gov (United States)

    Wang, Bai-Qiu; Wang, Wei; Chen, Wei Terry; Gao, Jian-Feng; Zhao, Xin-Fu; Yan, Dan-Ping; Zhou, Mei-Fu

    2013-05-01

    Eastern Tibet to the west of the Yangtze Block consists of the Yidun and Songpan-Ganzi Terranes, separated by the Ganzi-Litang suture zone. The Yidun Terrane includes the Zhongza Massif to the west, but the eastern part of the Yidun terrane is covered by the Yidun Group extending from the south (Shangri-La region) to the north (Changtai region). The Yidun Group, from the base upward, includes the Lieyi, Qugasi, Tumugou and Lanashan formations, which are mainly composed of volcanic-flysch successions. Based on the ages of volcanic interlayers and plutonic intrusions, depositional ages of the Qugasi and Tumugou formations are considered to be slightly older than 230 Ma and ca. 220-230 Ma respectively, which are prominently older than the previous estimates. The Yidun Group in the Changtai region has two prominent detrital zircon age peaks at 400-480 and 880-980 Ma and a minor peak at 2.45-2.50 Ga. This pattern suggests a detritus source from the Zhongza Massif, which was a micro-continent separated from the western Yangtze Block. In contrast, the Yidun Group in the Shangri-La region has various zircon age spectra among different formations. The Qugasi Formation in this region has detrital zircon age patterns similar to the Yidun Group in the Changtai region. However, the overlying Tumugou Formation shows distinct age peaks at Triassic (220-240 Ma), Neoproterozoic (~ 720-880 Ma), and Paleoproterozoic (~ 1.75-1.90 Ga). This age pattern is similar to that of the Xikang Group of the Songpan-Ganzi Terrane to the east. The detrital zircon age difference between the Qugasi and Tumugou formations in this region indicates a transition of sedimentary sources from the Zhongza Massif to locally distributed Triassic magmatic rocks at ~ 230 Ma. It is thus suggested that the Songpan-Ganzi Terrane may have been connected to or collided with the southern part of the Yidun Terrane during the Late Triassic, whereas the Songpan-Ganzi Terrane and the northern part of the Yidun Terrane

  19. Group as social microcosm: Within-group interpersonal style is congruent with outside group relational tendencies.

    Science.gov (United States)

    Goldberg, Simon B; Hoyt, William T

    2015-06-01

    The notion that individuals' interpersonal behaviors in the context of therapy reflects their interpersonal behaviors outside of therapy is a fundamental hypothesis underlying numerous systems of psychotherapy. The social microcosm hypothesis, in particular, claims the interpersonal therapy group becomes a reflection of group members' general tendencies, and can thus be used as information about members' interpersonal functioning as well as an opportunity for learning and behavior change. The current study tested this hypothesis using data drawn from 207 individuals participating in 22 interpersonal process groups. Ratings were made on 2 key interpersonal domains (Dominance and Affiliation) at baseline and at Weeks 2, 5, and 8 of the group. Two-level multilevel models (with participants nested within groups) were used to account for the hierarchical structure, and the social relations model (SRM; Kenny, 1994) was used to estimate peer ratings (target effects in SRM) unconfounded with rater bias. Participants showed consensus at all time points during the interpersonal process groups on one another's levels of dominance and affiliation. In addition, self- and peer ratings were stable across time and correlated with one another. Importantly, self-ratings made prior to group significantly predicted ratings (self- and peer) made within the group, with effect sizes within the medium range. Taken together, these results provide robust support for the social microcosm hypothesis and the conjecture that interpersonal style within-group therapy is reflective of broader interpersonal tendencies. (c) 2015 APA, all rights reserved).

  20. EDF group - annual report 2003; Groupe EDF - rapport annuel 2003

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This document contains the magazine, the financial statements and the sustainable development report of Electricite de France (EdF) group for 2003: 1 - the magazine (chairman's statement, group profile, vision and strategy); 2 - the consolidated financial statements for the period ended 31 December 2003 (statutory auditors' report on the consolidated financial statements, EDF's summary annual financial statements); 3 - sustainable development report (transparency and dialogue, responsibility, commitment, partnerships for progress). (J.S.)

  1. Bayesian Hierarchical Grouping: perceptual grouping as mixture estimation

    Science.gov (United States)

    Froyen, Vicky; Feldman, Jacob; Singh, Manish

    2015-01-01

    We propose a novel framework for perceptual grouping based on the idea of mixture models, called Bayesian Hierarchical Grouping (BHG). In BHG we assume that the configuration of image elements is generated by a mixture of distinct objects, each of which generates image elements according to some generative assumptions. Grouping, in this framework, means estimating the number and the parameters of the mixture components that generated the image, including estimating which image elements are “owned” by which objects. We present a tractable implementation of the framework, based on the hierarchical clustering approach of Heller and Ghahramani (2005). We illustrate it with examples drawn from a number of classical perceptual grouping problems, including dot clustering, contour integration, and part decomposition. Our approach yields an intuitive hierarchical representation of image elements, giving an explicit decomposition of the image into mixture components, along with estimates of the probability of various candidate decompositions. We show that BHG accounts well for a diverse range of empirical data drawn from the literature. Because BHG provides a principled quantification of the plausibility of grouping interpretations over a wide range of grouping problems, we argue that it provides an appealing unifying account of the elusive Gestalt notion of Prägnanz. PMID:26322548

  2. EDF group - Reference Document 2004

    International Nuclear Information System (INIS)

    2005-01-01

    The EDF Group is an integrated energy supplier operating in a wide range of electricity-related businesses: generation, transmission, distribution, sale and trading of energy. It is the main operator in the French electricity market and one of the leading electricity groups in Europe. With an installed capacity of 125,4 GW, it contributes to the supply of energy and services to more than 42 million customers throughout the world (with approximately 36 million customers in Europe, more than 28 million of whom are in France). The EDF Group has built a business model balanced between deregulated and regulated operations in France and an international presence. In 2004, the Group recorded consolidated sales of euros 46,928 million, net income (Group share) of euros 1,341 million, and it achieved earnings before interests, taxes, depreciation and amortization of euros 12,127 million. This document is EDF Group's Reference Document for the year 2004. It contains information about: the Group activities, capital, relations with Gaz de France utility, strategy, industrial environment, history, activity in France, international activity, transverse activities and functions, disputes, arbitration and risk factors, Property, Plants and Equipment, Operating and Financial Review, Administrative, Management, and Supervisory Bodies and Senior Management, Remuneration and Benefits, recent trends and perspectives

  3. Group theory approach to scattering

    International Nuclear Information System (INIS)

    Wu, J.

    1985-01-01

    For certain physical systems, there exists a dynamical group which contains the operators connecting states with the same energy but belonging to potentials with different strengths. This group is called the potential group of that system. The SO(2,1) potential groups structure is introduced to describe physical systems with mixed spectra, such as Morse and Poeschl-teller potentials. The discrete spectrum describes bound states and the continuous spectrum describes bound states and the continuous spectrum describes scattering states. A solvable class of one-dimensional potentials given by Natanzon belongs to this structure with an SO(2,2) potential group. The potential group structure provides us with an algebraic procedure generating the recursion relations for the scattering matrix, which can be formulated in a purely algebraic fashion, divorced from any differential realization. This procedure, when applied to the three-dimensional scattering problem with SO(3,1) symmetry, generates the scattering matrix of the Coulomb problem. Preliminary phenomenological models for elastic scattering in a heavy-ion collision are constructed on the basis. The results obtained here can be regarded as an important extension of the group theory techniques to scattering problems similar to that developed for bound state problems

  4. EDF group - Reference Document 2005

    International Nuclear Information System (INIS)

    2006-01-01

    The EDF Group is an integrated energy supplier operating in a wide range of electricity-related businesses: generation, transmission, distribution, sale and trading of energy. It is the main operator in the French electricity market and one of the leading electricity groups in Europe. With an installed capacity of 130.8 GW (123.9 GW in Europe), it contributes to the supply of energy and services to more than 40 million customers throughout the world (with approximately 36.7 million customers in Europe, more than 28 million of whom are in France). The EDF Group has built a business model balanced between deregulated and regulated operations in France and an international presence. In 2005, the Group recorded consolidated sales of euros 51,051 million, net income (Group share) of euros 3,242 million, and it achieved earnings before interests, taxes, depreciation and amortization of euros 13,010 million. This document is EDF Group's Reference Document for the year 2005. It contains information about: the Group activities, risk factors, Business Overview, Organizational Structure, Property, Plants and Equipment, Operating and Financial Review, Capital Resources, Research and Development, Patents and Licences, Trend Information, Financial Prospects, Administrative, Management, and Supervisory Bodies and Senior Management, Remuneration and Benefits, Board Practices, Employees/Human Resources, Major Shareholders, Related Party Transactions, Financial Information Concerning the Company's Assets and Liabilities, Financial Position and Profits and Losses, Material Contracts, Information on Holdings etc

  5. EDF group - Reference Document 2006

    International Nuclear Information System (INIS)

    2007-01-01

    The EDF Group is an integrated energy supplier operating in a wide range of electricity-related businesses: generation, transmission, distribution, sale and trading of energy. It is the main operator in the French electricity market and holds strong positions in the other three principal European markets (Germany, the United Kingdom, Italy) making it one of the leading electricity groups in Europe, and a recognized actor in the gas market. With an installed capacity of 123.7 GW in Europe (128.2 GW worldwide) it holds, among the major European energy specialists, the largest production fleet and the one emitting the least CO 2 , owing to the share of nuclear technology and hydropower in its generation mix. The EDF group supplies electricity, gas and associated services to more than 37.8 million customers throughout the world and in Europe (more than 28 million of whom are in France). The EDF Group has built a business model balanced between France and the international markets, and between deregulated and regulated operations. In 2006, the Group recorded consolidated sales of euros 58,932 million, net income (Group share) of euros 5,605 million, and it achieved earnings before interest, taxes, depreciation and amortization of euros 13,930 million. From July 1, 2007, the EDF group will carry out its trading activities in a European energy market fully open to competition. This document is EDF Group's Reference Document for the year 2006. It contains information about: the Group activities, risk factors, Business overview, Organizational structure, Property, plants and equipment, Operating and financial review, Capital resources and cash flows, Research and Development, Patents and Licenses, Trend information, Financial forecasts or estimates, Administrative, management and supervisory bodies and senior management, Remuneration and benefits, Board practices, Employees/Human resources, Major shareholders, Related party transactions, Financial information

  6. The Cogema group in Japan

    International Nuclear Information System (INIS)

    1998-12-01

    The partnership between the Cogema group and Japan in the domain of fuel cycle started about 20 years ago and the 10 Japanese nuclear operators are all clients of the Cogema group. The 1997 turnover realized with Japan reached 3.6 billions of francs (11% of the total turnover of the group). This short paper presents briefly the nuclear program of Japan (nuclear park, spent fuels reprocessing-recycling strategy) and the contracts between Cogema and the Japanese nuclear operators (natural uranium, uranium conversion and enrichment, spent fuel reprocessing, plutonium recycle and MOX fuel production markets). (J.S.)

  7. Derived equivalences for group rings

    CERN Document Server

    König, Steffen

    1998-01-01

    A self-contained introduction is given to J. Rickard's Morita theory for derived module categories and its recent applications in representation theory of finite groups. In particular, Broué's conjecture is discussed, giving a structural explanation for relations between the p-modular character table of a finite group and that of its "p-local structure". The book is addressed to researchers or graduate students and can serve as material for a seminar. It surveys the current state of the field, and it also provides a "user's guide" to derived equivalences and tilting complexes. Results and proofs are presented in the generality needed for group theoretic applications.

  8. Wave propagation and group velocity

    CERN Document Server

    Brillouin, Léon

    1960-01-01

    Wave Propagation and Group Velocity contains papers on group velocity which were published during the First World War and are missing in many libraries. It introduces three different definitions of velocities: the group velocity of Lord Rayleigh, the signal velocity of Sommerfeld, and the velocity of energy transfer, which yields the rate of energy flow through a continuous wave and is strongly related to the characteristic impedance. These three velocities are identical for nonabsorbing media, but they differ considerably in an absorption band. Some examples are discussed in the last chapter

  9. Injuries in group kept horses

    DEFF Research Database (Denmark)

    Mejdell, C.M.; Jorgensen, G.M.; Keeling, L.

    2014-01-01

    to categorize 1124 injuries in 478 horses. Most of these horses were allocated to groups to study the effect of group composition (i.e. same age or mixed, same gender or mixed, socially stable or unstable groups) on behaviour and injuries. The material included mainly riding and leisure purpose horses...... of different breeds, age and gender. Most injuries occurred the day after mixing. Injuries of the more severe categories 4 and 5, which normally would necessitate veterinary care and/or loss of function for some time, were not observed at all. The minor injuries categorized as 1-2 counted for 99% of the total...

  10. Geometry, rigidity, and group actions

    CERN Document Server

    Farb, Benson; Zimmer, Robert J

    2011-01-01

    The study of group actions is more than a hundred years old but remains to this day a vibrant and widely studied topic in a variety of mathematic fields. A central development in the last fifty years is the phenomenon of rigidity, whereby one can classify actions of certain groups, such as lattices in semi-simple Lie groups. This provides a way to classify all possible symmetries of important spaces and all spaces admitting given symmetries. Paradigmatic results can be found in the seminal work of George Mostow, Gergory Margulis, and Robert J. Zimmer, among others.The p

  11. 2002 annual report EDF group

    International Nuclear Information System (INIS)

    2002-01-01

    This document is the 2002 annual report of Electricite de France (EdF) group, the French electric utility. Content: Introductory section (EDF at a glance, Chairman's message, 2002 Highlights); Corporate governance and Group strategy (Corporate governance, sustainable growth strategy, EDF branches); Financial performance (Reaching critical mass, Margins holding up well, Balance sheet); Human resources (Launching Group-wide synergies, Optimising human resources); Customers (Major customers, SMEs and professional customers, Local authorities, Residential customers, Ensuring quality access to electricity); Generation (A balanced energy mix, Nuclear generation, Fossil-fuelled generation, Renewable energies); Corporate social responsibility (Global and local partnerships, Promoting community development)

  12. Genodermatoses in paediatric age group

    Directory of Open Access Journals (Sweden)

    Kumar Sunil

    1996-01-01

    Full Text Available Pattern of genodermatoses in paediatric age group was studied. The relative incidence of genodermatoses in paediatric dermatology out patient department was 0.62%. The commonest genodermatoses observed was ichthyosis.

  13. The Group Treatment of Bulimia.

    Science.gov (United States)

    Weinstein, Harvey M.; Richman, Ann

    1984-01-01

    Bulimia has become an increasing problem in the college population. This article describes a group psychotherapeutic treatment approach to the problem. A theoretical formulation of the psychodynamics that may underlie the development of bulimia is offered. (Author/DF)

  14. MOVES Model Review Work Group

    Science.gov (United States)

    The FACA MOVES Review Work Group was formed under the Mobile Sources Technical Review Subcommittee (MSTRS), and is charged to provide input to EPA via the MSTRS and the Clean Air Act Advisory Committee on specific issues regarding MOVES development.

  15. NISE (Nursing Inservice Education Group)

    Science.gov (United States)

    Clubine, Marilyn; And Others

    1973-01-01

    The purpose of the Toronto Inservice Education Group became to meet regularly in order to provide an opportunity to assist and guide those responsible for formulating and carrying out inservice education. Article outlines their objectives. (Author/RK)

  16. Asymptotic invariants of homotopy groups

    Science.gov (United States)

    Manin, Fedor

    We study the homotopy groups of a finite CW complex X via constraints on the geometry of representatives of their elements. For example, one can measure the "size" of alpha ∈ pi n (X) by the optimal Lipschitz constant or volume of a representative. By comparing the geometrical structure thus obtained with the algebraic structure of the group, one can define functions such as growth and distortion in pin(X), analogously to the way that such functions are studied in asymptotic geometric group theory. We provide a number of examples and techniques for studying these invariants, with a special focus on spaces with few rational homotopy groups. Our main theorem characterizes those X in which all non-torsion homotopy classes are undistorted, that is, their volume distortion functions, and hence also their Lipschitz distortion functions, are linear.

  17. Inflation and nonequilibrium renormalization group

    International Nuclear Information System (INIS)

    Zanella, Juan; Calzetta, Esteban

    2007-01-01

    We study the spectrum of primordial fluctuations and the scale dependence of the inflaton spectral index due to self-interactions of the field. We compute the spectrum of fluctuations by applying nonequilibrium renormalization group techniques

  18. Remainder Wheels and Group Theory

    Science.gov (United States)

    Brenton, Lawrence

    2008-01-01

    Why should prospective elementary and high school teachers study group theory in college? This paper examines applications of abstract algebra to the familiar algorithm for converting fractions to repeating decimals, revealing ideas of surprising substance beneath an innocent facade.

  19. On characters of finite groups

    CERN Document Server

    Broué, Michel

    2017-01-01

    This book explores the classical and beautiful character theory of finite groups. It does it by using some rudiments of the language of categories. Originally emerging from two courses offered at Peking University (PKU), primarily for third-year students, it is now better suited for graduate courses, and provides broader coverage than books that focus almost exclusively on groups. The book presents the basic tools, notions and theorems of character theory (including a new treatment of the control of fusion and isometries), and introduces readers to the categorical language at several levels. It includes and proves the major results on characteristic zero representations without any assumptions about the base field. The book includes a dedicated chapter on graded representations and applications of polynomial invariants of finite groups, and its closing chapter addresses the more recent notion of the Drinfeld double of a finite group and the corresponding representation of GL_2(Z).

  20. Medicaid Enrollment - New Adult Group

    Data.gov (United States)

    U.S. Department of Health & Human Services — Total Medicaid Enrollees - VIII Group Break Out Report Reported on the CMS-64 The enrollment information is a state-reported count of unduplicated individuals...

  1. Climate change and group dynamics

    NARCIS (Netherlands)

    Postmes, Tom

    2015-01-01

    The characteristics and views of people sceptical about climate change have been analysed extensively. A study now confirms that sceptics in the US have some characteristics of a social movement, but shows that the same group dynamics propel believers

  2. The theory of nilpotent groups

    CERN Document Server

    Clement, Anthony E; Zyman, Marcos

    2017-01-01

    This monograph presents both classical and recent results in the theory of nilpotent groups and provides a self-contained, comprehensive reference on the topic.  While the theorems and proofs included can be found throughout the existing literature, this is the first book to collect them in a single volume.  Details omitted from the original sources, along with additional computations and explanations, have been added to foster a stronger understanding of the theory of nilpotent groups and the techniques commonly used to study them.  Topics discussed include collection processes, normal forms and embeddings, isolators, extraction of roots, P-localization, dimension subgroups and Lie algebras, decision problems, and nilpotent groups of automorphisms.  Requiring only a strong undergraduate or beginning graduate background in algebra, graduate students and researchers in mathematics will find The Theory of Nilpotent Groups to be a valuable resource.

  3. Metabolomics and Epidemiology Working Group

    Science.gov (United States)

    The Metabolomics and Epidemiology (MetEpi) Working Group promotes metabolomics analyses in population-based studies, as well as advancement in the field of metabolomics for broader biomedical and public health research.

  4. Linear algebra and group theory

    CERN Document Server

    Smirnov, VI

    2011-01-01

    This accessible text by a Soviet mathematician features material not otherwise available to English-language readers. Its three-part treatment covers determinants and systems of equations, matrix theory, and group theory. 1961 edition.

  5. Group Psychotherapy with Deaf Adolescents.

    Science.gov (United States)

    Bonham, H. E. Eugene; And Others

    1981-01-01

    The process and outcome of group psychotherapy with deaf adolescents from a Texas public school is reported to illustrate the medium's use in managing normal adolescent adjustment problems at home and at school. (CL)

  6. Essays in the history of Lie groups and algebraic groups

    CERN Document Server

    Borel, Armand

    2001-01-01

    Lie groups and algebraic groups are important in many major areas of mathematics and mathematical physics. We find them in diverse roles, notably as groups of automorphisms of geometric structures, as symmetries of differential systems, or as basic tools in the theory of automorphic forms. The author looks at their development, highlighting the evolution from the almost purely local theory at the start to the global theory that we know today. Starting from Lie's theory of local analytic transformation groups and early work on Lie algebras, he follows the process of globalization in its two main frameworks: differential geometry and topology on one hand, algebraic geometry on the other. Chapters II to IV are devoted to the former, Chapters V to VIII, to the latter. The essays in the first part of the book survey various proofs of the full reducibility of linear representations of \\mathbf{SL}_2{(\\mathbb{C})}, the contributions of H. Weyl to representations and invariant theory for semisimple Lie groups, and con...

  7. Vocabulary Maintenance Task Group Report

    OpenAIRE

    Baskauf, Steve

    2016-01-01

    This was a presentation at the TDWG Annual Meeting in Costa Rica, 2016-12-08 in a Task Group report session.  Abstract: The Vocabulary Maintenance Task Group has completed drafts of a Standards Documentation Specification and a Vocabulary Management Specification (https://github.com/tdwg/vocab). This session will outline the important aspects of the specifications and answer questions about their content and implementation.

  8. CEC natural analogue working group

    International Nuclear Information System (INIS)

    Come, B.; Chapman, N.A.

    1986-01-01

    The second meeting of the CEC Natural Analogue Working Group took place on June 17-19, 1986, hosted by the Swiss NAGRA in Interlaken (CH). A review of recent progress in natural analogue programmes was carried out, and complemented by detailed discussions about geomicrobiology, archaeological analogues, natural colloids, and use of analogues to increase confidence in safety assessments for radioactive waste disposal. A statement drafted by the Group, and the presentations made, are put together in this report

  9. EDF group - annual report 2003

    International Nuclear Information System (INIS)

    2004-01-01

    This document contains the magazine, the financial statements and the sustainable development report of Electricite de France (EdF) group for 2003: 1 - the magazine (chairman's statement, group profile, vision and strategy); 2 - the consolidated financial statements for the period ended 31 December 2003 (statutory auditors' report on the consolidated financial statements, EDF's summary annual financial statements); 3 - sustainable development report (transparency and dialogue, responsibility, commitment, partnerships for progress). (J.S.)

  10. Molecular invariants: atomic group valence

    International Nuclear Information System (INIS)

    Mundim, K.C.; Giambiagi, M.; Giambiagi, M.S. de.

    1988-01-01

    Molecular invariants may be deduced in a very compact way through Grassman algebra. In this work, a generalized valence is defined for an atomic group; it reduces to the Known expressions for the case of an atom in a molecule. It is the same of the correlations between the fluctions of the atomic charges qc and qd (C belongs to the group and D does not) around their average values. Numerical results agree with chemical expectation. (author) [pt

  11. The EWMA Patient Outcome Group

    DEFF Research Database (Denmark)

    Gottrup, F

    2009-01-01

    Across Europe, clinical experts in wound care and industry representatives have joined forces to propose recommendations for clinical data collection on chronic wound management. Here, the chair of the group, Finn Gottrup, outlines its main objectives.......Across Europe, clinical experts in wound care and industry representatives have joined forces to propose recommendations for clinical data collection on chronic wound management. Here, the chair of the group, Finn Gottrup, outlines its main objectives....

  12. Fifteenth LAMPF users group meeting

    International Nuclear Information System (INIS)

    Cochran, D.R.F.

    1982-03-01

    The Fifteenth LAMPF Users Group Meeting was held November 2-3, 1981 at the Clinton P. Anderson Meson Physical Facility. The program of papers scheduled to be presented was amended to include a Report from Washington by Clarence R. Richardson, US Department of Energy. The general meeting ended with a round-table working group discussion concerning the Planning for a Kaon Factory. Individual items from the meeting were prepared separately for the data base

  13. Bosonic colored group field theory

    Energy Technology Data Exchange (ETDEWEB)

    Ben Geloun, Joseph [Universite Paris XI, Laboratoire de Physique Theorique, Orsay Cedex (France); University of Abomey-Calavi, Cotonou (BJ). International Chair in Mathematical Physics and Applications (ICMPA-UNESCO Chair); Universite Cheikh Anta Diop, Departement de Mathematiques et Informatique, Faculte des Sciences et Techniques, Dakar (Senegal); Magnen, Jacques [Ecole Polytechnique, Centre de Physique Theorique, Palaiseau Cedex (France); Rivasseau, Vincent [Universite Paris XI, Laboratoire de Physique Theorique, Orsay Cedex (France)

    2010-12-15

    Bosonic colored group field theory is considered. Focusing first on dimension four, namely the colored Ooguri group field model, the main properties of Feynman graphs are studied. This leads to a theorem on optimal perturbative bounds of Feynman amplitudes in the ''ultraspin'' (large spin) limit. The results are generalized in any dimension. Finally, integrating out two colors we write a new representation, which could be useful for the constructive analysis of this type of models. (orig.)

  14. Fifteenth LAMPF users group meeting

    Energy Technology Data Exchange (ETDEWEB)

    Cochran, D.R.F. (comp.)

    1982-03-01

    The Fifteenth LAMPF Users Group Meeting was held November 2-3, 1981 at the Clinton P. Anderson Meson Physical Facility. The program of papers scheduled to be presented was amended to include a Report from Washington by Clarence R. Richardson, US Department of Energy. The general meeting ended with a round-table working group discussion concerning the Planning for a Kaon Factory. Individual items from the meeting were prepared separately for the data base.

  15. Applications of blood group genotyping

    Directory of Open Access Journals (Sweden)

    Mariza A. Mota

    2006-03-01

    Full Text Available Introduction: The determination of blood group polymorphism atthe genomic level facilitates the resolution of clinical problemsthat cannot be addressed by hemagglutination. They are useful to(a determine antigen types for which currently available antibodiesare weakly reactive; (b type patients who have been recentlytransfused; (c identify fetuses at risk for hemolytic disease of thenewborn; and (d to increase the reliability of repositories of antigennegative RBCs for transfusion. Objectives: This review assessedthe current applications of blood group genotyping in transfusionmedicine and hemolytic disease of the newborn. Search strategy:Blood group genotyping studies and reviews were searched ingeneral database (MEDLINE and references were reviewed.Selection criteria: All published data and reviews were eligible forinclusion provided they reported results for molecular basis ofblood group antigens, DNA analysis for blood group polymorphisms,determination of fetal group status and applications of blood groupgenotyping in blood transfusion. Data collection: All data werecollected based on studies and reviews of blood grouppolymorphisms and their clinical applications.

  16. EDF Group - Annual Report 2009

    International Nuclear Information System (INIS)

    2010-01-01

    The EDF Group is a leading player in the energy industry, active in all areas of the electricity value chain, from generation to trading and network management, with expanding operations in the natural gas chain. It has a sound business model, evenly balanced between regulated and deregulated activities. The EDF Group is the leader in the French and British electricity markets and has solid positions in Germany and Italy and numerous other European countries, as well as industrial operations in Asia and the United States. Everywhere it operates, the EDF Group is a model of quality public service for the energy sector. With fi rst-rate human resources, R and D capability and generation expertise in nuclear, fossil-fired and renewable energies, particularly hydro, together with energy eco-efficiency offers, the EDF Group delivers competitive solutions that help ensure sustainable economic development and climate protection. This document is EDF Group's annual report for the year 2009. It contains information about Group profile, governance, business, development strategy, sales and marketing, positions in Europe and international activities. The document is made of several reports: the Activity and Sustainable Development Report, the Financial Report, the Management Report, the Report by the Chairman of EDF Board of Directors on corporate governance and internal control procedures, the Milestones report, the 'EDF at a glance' report, and the Sustainable Development Indicators

  17. EDF Group - Annual Report 2010

    International Nuclear Information System (INIS)

    2011-01-01

    The EDF Group is one of the world's leading energy companies, active in all areas from generation to trading and network management. It has a sound business model, evenly balanced between regulated and deregulated activities. With its first-rate human resources, R and D capability, expertise in engineering and operating generation plants and networks, as well as its energy eco-efficiency offers, the Group delivers competitive solutions that help ensure sustainable economic development and climate protection. The EDF Group is the leader in the French and UK electricity markets and has solid positions in Italy and numerous other European countries, as well as industrial operations in Asia and the United States. Everywhere it operates, the Group is a model of quality public service for the energy sector. This document is EDF Group's annual report for the year 2010. It contains information about Group profile, governance, business, development strategy, sales and marketing, positions in Europe and international activities. The document is made of several reports: the Activity and Sustainable Development Report, the Financial Report, the Management Report, the Report by the Chairman of EDF Board of Directors on corporate governance and internal control procedures, the Milestones report, the 'EDF at a glance' report, and the Sustainable Development Indicators

  18. EDF Group - Annual Report 2012

    International Nuclear Information System (INIS)

    2013-01-01

    The EDF Group is one of the world's leading energy companies, active in all areas from generation to trading and network management. It has a sound business model, evenly balanced between regulated and deregulated activities. With its first-rate human resources, R and D capability, expertise in engineering and operating generation plants and networks, as well as its energy eco-efficiency offers, the Group delivers competitive solutions that help ensure sustainable economic development and climate protection. The EDF Group is the leader in the French and UK electricity markets and has solid positions in Italy and numerous other European countries, as well as industrial operations in Asia and the United States. Everywhere it operates, the Group is a model of quality public service for the energy sector. This document is EDF Group's annual report for the year 2012. It contains information about Group profile, governance, business, development strategy, sales and marketing, positions in Europe and international activities. The document is made of several reports: the Activity and Sustainable Development Report, the Financial Report, the 'EDF at a glance' report, and the Sustainable Development Indicators

  19. The Cadmium Isotope Record of the Great Oxidation Event from the Turee Creek Group, Hamersley Basin, Australia

    Science.gov (United States)

    Abouchami, W.; Busigny, V.; Philippot, P.; Galer, S. J. G.; Cheng, C.; Pecoits, E.

    2016-12-01

    The evolution of the ocean, atmosphere and biosphere throughout Earth's history has impacted on the biogeochemistry of some key trace metals that are of particular importance in regulating the exchange between Earth's reservoirs. Several geochemical proxies exhibit isotopic shifts that have been linked to major changes in the oxygenation levels of the ancient oceans during the Great Oxygenation Event (GOE) between 2.45 and 2.2 Ga and the Neoproterozoic Oxygenation Event at ca. 0.6 Ga. Studies of the modern marine biogeochemical cycle of the transition metal Cadmium have shown that stable Cd isotope fractionation is mainly driven by biological uptake of light Cd into marine phytoplankton in surface waters leaving behind the seawater enriched in the heavy Cd isotopes. Here we use of the potential of this novel proxy to trace ancient biological productivity which remains an enigma, particularly during the early stages of Earth history. The Turee Creek Group in the Hamersley Basin, Australia, provides a continuous stratigraphic sedimentary section covering the GOE and at least two glacial events, offering a unique opportunity to examine the changes that took place during these periods and possibly constrain the evolution, timing and onset of oxygenic photosynthesis. Stable Cd isotope data were obtained on samples from the Boolgeeda Iron Fm. (BIFs), the siliciclastic and carbonate successions of Kungara (including the Meteorite Bore Member) and the Kazputt Fm., using a double spike technique by TIMS (ThermoFisher Triton) and Cd concentrations were determined by isotope dilution. The Boolgeeda BIFs have generally low Cd concentrations varying between 8 and 50ppb, with two major excursions marked by an increase in Cd content, reaching similar levels to those in the overlying Kungarra Fm. (≥150 ppb). These variations are associated with a large range in ɛ112/110Cd values (-2 to +2), with the most negative values typically found in the organic and Cd-rich shales and

  20. S3T working group. Report 1: group aims

    International Nuclear Information System (INIS)

    Pouey, M.

    1983-04-01

    The work group S3T which is aimed to designing and developing devices using unconventional holographic optics is presented. These devices find applications that are classified here in four items high resolution spectrometers, high definition imaging, high flux devices, metrology and interferometry. The problems to solve and the aims of the group in each of these cases are presented. Three synthesis of lectures are in this report. The main one concerns stigmatism conditions of concave holographic gratings used in normal incidence. This new process of focusing is very interesting for hot plasma diagnostics [fr