Sample records for CORRIMIENTO ISOTOPICO (isotopic shift)
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3

Trophic experiments to estimate isotope discrimination factors

Caut, Stephane; Angulo, Elena; Courchamp, Franck; Figuerola, Jordi
2010-01-01

Digital.CSIC (Spain)

4

Thermobarometric implications of clinopyroxene chemistry in the Plio-Quaternary magmas of Gran Canaria (Canary Islands, Spain)

Aulinas, M.; Gimeno, D.; Fernandez-Turiel, J. L.; Pérez Torrado, F. J.; Rodríguez González, A.; Gasperini, Daniela
2009-06-01

Digital.CSIC (Spain)

5

Theoretical mean-field and experimental occupation probabilities in the double-beta decay system Ge-76 to Se-76

Moreno, Óscar; Moya de Guerra, Elvira; Sarriguren, Pedro; Faessler, Amand
2010-04-06

Digital.CSIC (Spain)

6

The palaeohydrological evolution of Lago Chungara´ (Andean Altiplano, northern Chile) during the Lateglacial and early Holocene using oxygen isotopes in diatom silica

Hernández, Armand; Bao, Roberto; Giralt, Santiago; Leng, Melanie J.; Barker, Philips A.; Sáez, Alberto; Pueyo Mur, Juan José; Moreno Caballud, Ana; Valero-Garcés, Blas L.; Sloane, Hilary J.
2008-05-01

Digital.CSIC (Spain)

7

Sudden change in the nuclear charge distribution of very light gold isotopes

Wallmeroth, K.; Bollen, G.; Dohn, A.; Egelhof, P.; Grüner, J.; Lindenlauf, F.; Krönert, U.; Campos, J.; Rodríguez Yunta, A.; García Borge, María José; Venugopalan, A.; Wood, J. L.; Moore, R. B.; Kluge, H.-J.; [ISOLDE Collaboration]
1987-04-13

Digital.CSIC (Spain)

8

Spectroscopy with β2p and β-ν recoil shifts

Fynbo, H. O. U.; Axelsson, L.; Äystö, J.; Bergmann, U. C.; García Borge, María José; Fraile, Luis M.; Honkanen, A.; Hornshøj, P.; Jading, Y.; Jokinen, A.; Jonson, B.; Martel, Ismael; Mukha, I.; Nilsson, T.; Nyman, G.; Oinonen, M.; Riisager, K.; Siiskonen, T.; Smedberg, M. H.; Thaysen, J.; Tengblad, Olof; Wenander, F.
2002-01-06

Digital.CSIC (Spain)

11

Palynological signal of the Younger Dryas in the tropical Venezuelan Andes

Rull, Valentí; Nathan, D. Stansell; Montoya, Encarnación; Bezada, Maximiliano; Abbott, Mark B.
2010-01-01

Digital.CSIC (Spain)

13

Nuclear shape transition in neutron-deficient gold isotopes

Wallmeroth, K.; Bollen, G.; García Borge, María José; Campos, J.; Dohn, A.; Egelhof, P.; Grüner, J.; Kluge, H.-J.; Krönert, U.; Lindenlauf, F.; Moore, R. B.; Rodriguez, A.; Venugopalan, A.; Wood, J. L.; [ISOLDE Collaboration]
1987-03-01

Digital.CSIC (Spain)

14

Nuclear shape transition in light gold isotopes

Wallmeroth, K.; Bollen, G.; Dohn, A.; Egelhof, P.; Krönert, U.; García Borge, María José; Campos, J.; Rodríguez Yunta, A.; Heyde, K.; De Coster, C.; Wood, J. L.; Kluge, H.-J.; [ISOLDE Collaboration]
1989-03-06

Digital.CSIC (Spain)

15

Multiproxy reconstruction of the palaeoclimate and palaeoenvironment of the Middle Miocene Somosaguas site (Madrid, Spain) using herbivore dental enamel

Domingo, Laura; Cuevas-González, Jaime; Grimes, Stephen T.; Hernández Fernández, M.; Lopez-Martinez, N.
2009-02-01

Digital.CSIC (Spain)

16

Investigation of the alpha-cluster structure of Ne-22 and Mg-22

Goldberg, V. Z.; Rogachev, G. V.; Trzaska, W. H.; Kolata, J. J.; Andreyev, A.; Angulo, C.; García Borge, María José; Cherubini, S.; Chubarian, G.; Crowley, G.; Van Duppen, P.; Gorska, M.; Gulino, M.; Huyse, M.; Jesinger, P.; Källman, K. M.; Lattuada, M.; Lönnroth, T.; Mutterer, M.; Raabe, R.; Romano, S.; Rozhkov, M. V.; Skorodumov, B. B.; Spitaleri, C.; Tengblad, Olof; Tumino, A.
2004-02-10

Digital.CSIC (Spain)

17

Geomorfología y sedimentología de la Cuenca Superior del Río Salado (Sur de Santa Fe y Noroeste de Buenos Aires, Argentina)/ Geomorphology and sedimentology of the upper basin of the Salado River (Southern Santa Fe and NW Buenos Aires provinces; Argentina)

Iriondo, Martín; Kröhling, Daniela
2007-07-01

Resumen en español El S de la provincia de Santa Fe y el NO de la provincia de Buenos Aires forman parte del Mar de Arena Pampeano (Sistema Eólico Pampeano), que ha sufrido una secuencia de episodios áridos y húmedos a lo largo de los últimos períodos del Pleistoceno. El paisaje actual resulta fundamentalmente de la influencia del período húmedo del Estadio Isotópico 3 (EIO 3; 64-36 ka) y de la actividad eólica durante un clima seco del Holoceno tardío (3,5-1,4 ka). La secuencia d (mas) e eventos sedimentológicos y geomorfológicos fue la siguiente: Durante el período húmedo del EIO 3 se desarrolló una red fluvial de llanura, que actualmente forma la alta cuenca del Río Salado de Buenos Aires, labrada sobre sedimentos de la Fm Carcarañá. Posteriormente se depositó la Formación Teodelina, por sedimentación eólica. Esta tiene 10 a 12 m de espesor típico y unos 5 m en áreas sometidas a erosión; está compuesta por limo grueso arenoso y arena fina limosa, con modas principales entre 125-250 y 53-62 μm, color 10YR 6/4 (marrón amarillento) y similares. La composición mineralógica de la fracción entre 53 y 62 μm está dominada por vidrio volcánico, con feldespato, cuarzo y alteritas como accesorios. La redondez y esfericidad de los granos varían entre bajas y moderadas, con dos poblaciones. En el Pleistoceno final ocurrió un episodio eólico predominantemente erosivo, dominado por vientos del oeste que labraron cientos de depresiones de miles de metros de extensión. Ocurrió una sedimentación discontinua de loess arenoso de hasta 2 m de espesor con granulometría bimodal. El período Hypsithermal del Holoceno Medio (8,5-3,5 ka) estuvo caracterizado por un clima cálido y húmedo con régimen údico, que generó un suelo en los terrenos loéssicos y produjo el ascenso del nivel del agua en las lagunas y pantanos. El Holoceno tardío, entre 3,5 y 1,4 ka, estuvo dominado por un clima seco, con formación de campos de dunas denominadas aquí Formación San Gregorio. Está formada por arena muy fina a fina, suelta, masiva, color marrón amarillento, y compuesta por trizas vítreas, alteritas y feldespatos como componentes principales y cuarzo como componente secundario; los minerales pesados son de procedencia serrana. La época actual está caracterizada por un exceso de agua en el paisaje; el proceso sedimentológico más relevante es la movilización de grandes volúmenes de sales disueltas, particularmente cloruros y sulfatos. Resumen en inglés The geomorphology, Late Quaternary stratigraphy, sedimentology and hydrology of the upper basin of the Salado River were investigated. The study area is located in S Santa Fe and NW Buenos Aires provinces (11.000 km²) and comprises the NE sector of the Pampean Sand Sea (defined by Iriondo and Kröhling, 1995; Figures 1 and 2). The methodology applied in this study produced conclusions of stratigraphic and paleoclimatic nature. Works were performed in photographic and ima (mas) ges cabinet, in the field and laboratory. In cabinet, the geological cartography produced by the first author in former projects was issued, particularly the geological map of Santa Fe province, in 1:500.000 scale (Iriondo, 1987; Figure 3), the map of the South American plains (Iriondo, 1990a; Petit Maire et al., 1999) and the map of the Pampean Sand Sea in scale 1:1.000.000 (Iriondo, 1992). That was complemented with satellite images and photomosaic analyses, integrated with classical topographic quadrangles of IGM. Field works made in the region covered a period of two decades. The first expedition was done in the year 1985, during a dry inter-annual period which favored the description of geological profiles and collection of fossils in the bottom of channels. Further expeditions were made in the 1990's, resulting in the elaboration of the regional stratigraphy (Figure 4; Kröhling, 1998; Iriondo and Kröhling, 1995). The last three field surveys, between the years 2001 and 2004 (during the present humid period), were focused on the studies of dune fields, with areal sampling (about 50 samples) and the recovering of sedimentary cores (41 m drilled). Four stratigraphic boreholes were made in the study area and a complementary one outside it, with recovering of undisturbed samples and complemented with geotechnical S.P.T. tests. The main boreholes were drilled in Teodelina (34°11´lat. S; 61°31´long.W; 88 m a.s.l.; Santa Fe; Figure 5) and in San Gregorio (34°17' lat. S y 61°55´ long. W; 102 m a.s.l, Santa Fe). Laboratory analises comprises grain size analysis by sieving at intervals of ¼ Φ between 125 and 37 μm. For mineralogical determinations were applied loose grain techniques (in the very fine sand fraction) and X-ray diffractometry (on total samples; Figure 6). Complementary, morphoscopic determinations were carried out in the 74 μm fraction. Two geological formations of eolian origins are widespread in the region, Teodelina Fm (Late Pleistocene) and San Gregorio Fm (Late Holocene), which are formally defined here. The Teodelina Fm has a typical thickness of 10 to 12 m and has been eroded up to 5 m in some areas; it is composed of sandy coarse silt and silty fine sand, with main modes at 125-250 μm and 53-62 μm; the colour is yellowish brown and similar ones. The mineral composition of the 53-62 μm fraction is dominated by volcanic glass, with feldspars, quartz and alterites as accessory minerals. Roundness and sphericity of the grains vary from low to moderate, with two populations. The San Gregorio Fm is more than 7 m thick. It is composed of loose, massive, yellowish brown in color, very fine to fine sand (Figures 7a and 7b). The mineral composition is dominated by vitreous shards, alterites and feldspars as its main components and quartz as a secondary component; main heavy minerals were originated in the Pampean Ranges. The geomorphology of the area and the present hydric dynamics are controlled by eolian geoforms generated during the Late Quaternary. The exception is the fluvial collector in S Santa Fe which is a paleochannel of the Tercero river, controlled by tectonics (Figure 8). The study area underwent a sequence of dry and humid episodes during the Late Quaternary. Basically, the present landscape is the result of the influence of a humid climate which took place in the Oxygen Isotopic Stage 3 (OIS 3; 64-36 ka) and the eolian activity produced by a dry climate in the Late Holocene (3.5- 1.4 ka). The sequence of sedimentary and geomorphic events deduced from the data of this research was the following: during the humid OIS 3, a fluvial net developed; it forms at present the upper basin of the Salado River of Buenos Aires, and is carved in the Carcarañá Formation (OIS 3; Kröhling, 1999). In a subsequent dry episode (Late Pleistocene), the Teodelina Formation was sedimented by eolian and associated processes. A largelly erosive eolian phase occurred after Teodelina Fm accumulation; it was characterized by Western winds that carved hundreds of large deflation hollows. A discontinuous sedimentation of a sandy loess up to 2 m thick with bimodal grain size distribution covered the minor accidents of the landscape. The humid period of the Middle Holocene (8.5-3.5 ka) was characterized by a warm and humid climate with an udic soil regime, which generated a soil profile on the loessic terrains and provoked the water level rising in lakes and swamps. The Late Holocene, from 3.5 to 1.4 ka BP, was characterized by a dry climate that produced the development of parabolic dune fields, named here as the San Gregorio Formation. An interesting geomorphological feature of the study area is represented by numerous shallow lakes occupying large deflation hollows generated by W winds. That indicates a shift of the Westerlies to the N up to 34° lat. S at the Upper Pleistocene-Lower Holocene interval (Figure 9). During the Little Ice Age the studied area underwent an arid climate with dominance of SW winds that produced a general mobilization of sand to the NE (Figure 10); the inherited shallow lakes were transformed in playas (Dangavs and Mormeneo, 2006). The present dynamics is dominated by an excess of water in the landscape as a consequence of the Present humid climate and the morphosedimentological control referred above. The significant sedimentological process is the mobilization of large volumes of dissolved salts, mainly chlorides and sulphates.

Scientific Electronic Library Online (Spanish)

18

Fisicoquímica de salmueras e hidrocarburos en cuencas petroleras y en depósitos minerales tipo Mississippi Valley y asociados. Parte II: ejemplos de la Cuenca de Sabinas y la Cuenca del Sureste, México/ Physicochemical characteristics of brines and hydrocarbons in petroliferous basins and Mississipppi Valley type and associated ore deposits. Part II: examples in the Sabinas and Southeast basins, Mexico

González-Partida, Eduardo; Camprubí, Antoni; Canet, Carles; González-Sánchez, Francisco
2008-01-01

Resumen en español En el presente trabajo se utilizan datos procedentes del análisis de inclusiones fluidas a fin de caracterizar el papel de salmueras de cuenca en las cuencas de Sabinas y del Sureste en México, en las que dichas salmueras fueron responsables de la formación de depósitos tipo Mississippi Valley (MVT) y asociados, así como de la migración y acumulación de petróleo, respectivamente. Los depósitos MVT de Pb-Zn presentan salinidades entre 7 y 22 wt.% NaCl equiv. y Th (mas) entre 75° y 150°C. Los mantos de barita asociados al tipo MVT presentan salmueras cloruradas sódicas y calcicas con predominio de esta última, en un rango de 1 a 2 wt.% NaCl y de 8 a 24 wt.% CaCl2, con Th entre 50° y 190°C. Los mantos de celestina asociados al tipo MVT presentan fluidos en inclusiones con salinidades entre 1 y 12 wt.% NaCl equiv. y Th entre 70° y 160°C. Los mantos y brechas de fluorita asociados al tipo MVT presentan fluidos acuosos en inclusiones con salinidades entre 6 y 14 wt.% NaCl equiv. y Th entre 50° y 170°C, e inclusiones de hidrocarburos con Th entre 45° y 90°C. Dichos hidrocarburos son generalmente de dos tipos: (1) con poca concentración de metano (>20% mol) y bajas Th (45° a 60°C), y (2) con concentraciones próximas al 30-40% mol de metano, con Th más altas (60° a 90°C). Las inclusiones de hidrocarburos que presentan una fase acuosa tienen una salinidad de 14 wt.% de NaCl equiv., presentan generalmente baja concentración de CO2 y de azufre, y relaciones CH2/CH3 elevadas, lo que corresponde a alkanos de la cadena C16 formados a presiones de 300 a 160 bar. En la Cuenca del Sureste, los paleofluidos más precoces relacionados a las rocas generadoras de petróleo presentan Th entre 55°C y 145°C, y salinidades entre 0.5 y 1 wt.% NaCl y entre 3 a 21 wt.% CaCl2. Las inclusiones con hidrocarburos presentan Th entre 1 º y 87°C. Las salmueras acuosas presentan concentraciones altas en metano, formadas a presiones ~1200 bar, sugiriendo que las rocas estaban sobrepresurizadas en el momento de la circulación de los paleofluidos. En la etapa de migración se produjeron al menos cinco generaciones de dolomita y se pasó de un régimen litostático a uno hidrostático, a presiones entre 900 y 500 bar y temperaturas de 130° a 150°C, con salinidades entre 1.6 y 12 wt.% NaCl equiv. El llenado de los reservorios se produjo a temperaturas análogas por salmueras acuosas con salinidades entre 2 y 8 wt.% NaCl equiv., mientras que las inclusiones de hidrocarburos presentan una Th entre 40° y 100°C y representan el regreso a condiciones de presión hidrostática, entre 400 y 600 bar. La geoquímica de halógenos, tanto en yacimientos de hidrocarburos como en yacimientos tipo MVT, sugiere la intervención de aguas derivadas de evaporación de agua marina, que sobrepasaron el punto de precipitación de la halita, en equilibrio con procesos de dolomitización. Los valores de δ13C y δ18O en carbonatas de la Cuenca del Sureste presentan valores entre -5 y 2.8‰, y entre -10 y 1.9‰, respectivamente. Tales variaciones en el comportamiento isotópico de los carbonatas se deben principalmente a (1) la introducción de carbono orgánico en el fluido a partir del que se formó la dolomita, derivado de la oxidación del metano, y (2) a un bajo proceso de interacción agua/roca, teniendo la temperatura un papel muy secundario. Para los yacimientos tipo MVT, los valores de δ13C y δ18O se presentan en rangos entre -8 y 2.8‰, y entre -15 y -0.1‰, respectivamente. Estas composiciones se interpretan como debidas a mezclas entre aguas meteóricas y salmueras de cuenca calientes que provocaron la maduración de materia orgánica de la roca encajonante al momento del depósito de las menas. Resumen en inglés Fluid inclusion data are used in this paper to explain the role ofbasinal brines for both the Sabinas and Southeast basins in Mexico, in -which such brines -were responsible for the formation of MVT and associated deposits, and for the migration and accumulation of petroleum, respectively. Salinities and temperatures of homogenization (Th) of fluid inclusions of the Pb-Zn MVT deposits of the Sabinas Basin range from 7 to 22 wt.% NaCl equiv. and Th range from 75° to 150° (mas) C. The barite mantos have aqueous fluid inclusions with sodium and calcium chloride brines, -with dominant CaCl2, that range from 1 to 2 wt.% NaCl and from 8 to 24 wt.% CaCl2, and Th that range from 50° to 190°C. The celestine mantos associated to the MVT type have aqueous fluid inclusions with salinities that range from 1 to 12 wt.% NaCl equiv. and Th that range from 70° to 160°C. Thefluorite mantos and breccias associated with the MVT type have aqueous fluid inclusions with salinities that range from 6 to 14 wt.% NaCl equiv. and Th that range from 50° to 170°C, and hydrocarbon inclusion fluids with Th that range from 45° to 90°C. Such hydrocarbon-bearing inclusions can generally be classified as (1) of low CH4 concentration (>20% mol) and low Th (45° a 60°C) inclusions, or (2) inclusions with higher methane concentrations (about 30-40% mol CH) and higher Th (60° to 90°C). Hydrocarbon-bearing inclusions that show an aqueous phase have salinities of about 14 wt.% NaCl equiv. and generally low CO2 and sulfur concentrations, and high CH2/CH3 ratios, which correspond to C16-chain alkanes that formed at pressures between 160 to 300 bar. In the Southeast Basin the earliest paleofluids associated with Tithonian-Kimmeridgian rocks (petroleum generators) are represented by fluid inclusions that show calcic brines with Th that range from 55 °C to 145 °C and salinities that range from 0.5 to 1 wt.% NaCl and from 3 to 21 wt.% CaCl2. The hydrocarbon-bearing inclusions have Th that range from 1° to 87°C. The aqueous brines may have high methane concentrations, and formed at ~1200 bar, suggesting that the rocks were overpressured during the circulation of paleofluids and their interaction with country rocks. During the migration of such fluids no less than five generations of dolomitization occurred, and the pressure regime shifted from lithostatic to hydrostatic, thus forming hydraulic breccias that were cemented by dolomite and late calcite. Such shift occurred at pressures that ranged from 900 to 500 bar and temperatures from 130° to 150°C, and the salinities of associated fluids range from 1.6 to 12 wt.% NaCl equiv. The filling of reservoirs occurred at similar temperatures, with associated aqueous fluids with salinities ranging from 2 and 8 wt.% NaCl equiv, whereas the aqueous fluids in hydrocarbon-bearing inclusions have Th that range from 40° to 100°C. Such inclusions were trapped during a shift back to the hydrostatic pressure regime, between 400 and 600 bar. In both petroleum and MVT deposits the geochemistry of halogens suggests the occurrence of water derived from the evaporation of seawater that reached the over saturation in halite, in equilibrium with dolomitization processes. Such water mixed with mainly meteoric water during the filling of petroleum reservoirs and during the formation of some ores in MVT and associated deposits. The δ13C and δ18O values in carbonates of the Southeast Basin range from -5 and 2.8‰, and from -10 to 1.9‰, respectively. Such variation in isotopic compositions may be due to (1) the introduction of organic carbon in the fluids that produced dolomitization, after the oxidation of methane, and (2) a process of low water/rock interaction in which the role of temperature would have been marginal. The δ13C and δ18O values in carbonates of MVT and associated deposits in the Sabinas Basin range from -8 to 2.8‰, and from -15 to -0.1‰, respectively. Such variation in isotopic compositions is interpreted as due to the mixing between meteoric water and hot basinal brines that induced the maturation of organic matter within country rocks during the formation of ores.

Scientific Electronic Library Online (Spanish)

20

Determination of the spin of Ar-31

Thaysen, J.; Axelsson, L.; Äystö, J.; García Borge, María José; Fraile, Luis M.; Fynbo, H. O. U.; Honkanen, A.; Hornshøj, P.; Jading, Y.; Jokinen, A.; Jonson, B.; Martel, Ismael; Mukha, I.; Nilsson, T.; Nyman, G.; Oinonen, M.; Riisager, K.; Siiskonen, T.; Smedberg, M. H.; Tengblad, Olof; Wenander, F.; [ISOLDE Collaboration]
1999-11-18

Digital.CSIC (Spain)

21

Decay properties of the 02(+) state and spin parities assigned in Kr-78

Giannatiempo, A.; Nannini, A.; Perego, A.; Sona, P.; García Borge, María José; Tengblad, Olof
1995-11-01

Digital.CSIC (Spain)

23

Charge radii and structural evolution in Sr, Zr, and Mo isotopes

Rodriguez-Guzman, R.; Sarriguren, Pedro; Robledo, L.M.; Perez-Martin, S.
2010-08-01

Digital.CSIC (Spain)

25

A theoretical approach to the vibrational analysis of the nitroenamine system

Chiara, José Luis; Gómez-Sánchez, Antonio; Sánchez Marcos, Enrique
1990-01-01

Digital.CSIC (Spain)

26

A speleothem record of glacial (25–11.6 kyr BP) rapid climatic changes from northern Iberian Peninsula

Moreno Caballud, Ana; Stoll, Heather; Jiménez-Sánchez, Montserrat; Cacho, Isabel; Valero-Garcés, Blas L.; Ito, Emi; Edwards, R. Lawrence
2010-04-01

Digital.CSIC (Spain)