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Showing 1 to 20 of 25 for “"d18O"”.
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Oxygen isotopes in diatom silica : a new understanding of silica-water oxygen isotope fractionation in diatom frustules and an application of diatom d180 values as a record of paleohydrologic variability in a middle-Pleistocene lacrustine core from the Valles Caldera, New Mexico
… fractionation. Post-mortem alteration of silica d18O values occurs within 0.5 years in diatom frustules from a lacustrine setting in the Valles Caldera, New Mexico resulting in an increase of ~7.4° in the d18O values. The rapid post-mortem alteration of diatom d18O values explains much of the …
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Climate significance of stable isotope records from Alpine ice cores
Tiefenprofile der stabilen Wasserisotopomere (d18O und dD) dreier tiefer Eisbohrkerne vom Monte Rosa Massiv (Schweizer Alpen) wurden im Hinblick auf möglicherweise aufgezeichnete Temperatursignale ausgewertet. Durch eine neuartige Methode der Wasserreduktion sind On-line dD Messungen mit einer …
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Fluidassoziierte Brekzien als Monitor dolomitisierender und dedolomitisierender Lösungsströme in der Kantabrischen Zone (Nordspanien)
… für alle vier Brekzienlokalitäten 95-145 °C. Die d18O-Werte der Barcaliente Formation zeigen einen großen Schwankungsbereich (-12,73 bis 1,51 d18O ? PDB). Die d13C-Werte (PDB) zeigen keine große Varianz (2,56 bis 5,43 d13C ? PDB). Die Dolomite der Brekzienlokalitäten weisen geringere d18O- (PDB) …
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Massenspektrometrische Th/U-Datierung von Höhlensintern aus dem Oman: Klimaarchive des asiatischen Monsuns
… zu erstellen, um die Periodizitäten des d18O exakt zu datieren. Durch die Fortschritte der Thermionen-Massenspektrometrie (TIMS) und das hohe Datierungspotential der Proben konnte eine hochgradige Datierungspräzision mit einem Maximum von 0,5 erreicht werden. Ein aus mehreren …
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Provenancing humans: the real uncertainty of stable isotope data
… variation in the isotopic variability of d18O both within, and between individuals. It also indicated that there was no significant difference between the isotope values obtained from the left and right femora of the same individual, however there was significant variation between a number …
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STABLE ISOTOPE RATIOS AS A PROXY FOR HUMAN GEOGRAPHIC PROVENANCE: BIOGEOGRAPHICAL EVIDENCE FROM THE 2H, 18O, AND 13C SIGNATURES IN MODERN HUMAN TEETH
… were not significant. The pooled mean d18OVSMOW value for enamel samples was 24.39 ‰, while individual subject mean d18OVSMOW values ranged from 23.76 ‰ to 25.18 ‰. Marked offsets (0.01 ‰ - 0.51 ‰) in mean d18OVSMOW values for each pair of third molars were observed. While subject …
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Aspects of material transport and polycrystal growth in fractures
… 5 presents microstructural, stable (d13C, d18O) and radiogenic (87Sr/86Sr) isotope of antitaxial fibrous calcite veins from the Swiss Alps and New York State, USA. At least some veins are isolated in three dimensions, vein formation is initated by transgranular fracturing. Isotope data …
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Multi-isotope analysis and the reconstruction of prey species palaeomigrations and palaeoecology
… bone, including strontium (87Sr/86Sr), oxygen (d18O), carbon(d13C), nitrogen (d15N) and sulphur (d34S). Teeth (enamel and dentine) were sequentially-sampled in order to reconstruct time-series isotopic profiles at an intra- and inter-individual scale, allowing an assessment of the applicability …
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Changes in monsoonal precipitation and atmospheric circulation during the Holocene reconstructed from stalagmites from Northeastern India
… pattern of seasonal changes in stable isotopes (d18O and d2H) in rainfall. I show that although in tropical and subtropical regions the amount effect is commonly called to explain strongly depleted isotope values during enhanced rainfall, alone it cannot account for observed rainwater isotope …
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Establishing High-Resolution Hydrogeological, Geochemical and Isotopic Baseline Conditions of the Fresh Water Zone at a Field Research Site Near Brooks, Alberta, Canada
… were characterized by lower flow rates, higher d18O and d2H values of water and variable water types. Methane and ethane concentrations were lower compared to samples obtained from coals and d13C-CH4 values ranged between -75‰ and -60‰. The domestic well yielded groundwater with chemical and …
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Petrogenesis of the Mesoproterozoic anorthosite, syenite and carbonatite suites of NW Namibia and their contribution to the metasomatic formation of the Swartbooisdrif sodalite deposits
… from fractionated basaltic liquids, with the d18O values (5.88 ± 0.19 ‰) proving their derivation from mantle-derived magmas. The results obtained for the felsic suite, provide evidence against consanguinity of the anorthosites and the syenites, i.e. (1) compositional gaps between the …
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Chemical Weathering History of Antarctica During A Late Eocene Glacial Event
… of early Oligocene Antarctic glaciation. The d18O values for both the fine fraction carbonate and benthic foraminifera (Cibicidoides spp.) increased ~0.6 ppm, reflecting a combination of ice sheet growth and deep water cooling. Fossil fish teeth and detrital sediments were analyzed for eNd, a …
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Investigation of the Oxygen Isotope Exchange Between Carbon Dioxide and O3 via O(1D)
… enrichment for 17O according to d17O =1.7 d18O. This is contrary to tropospheric CO2 where d17O ~ 0.5d18O. These isotope enrichments are transferred from O3 into CO2, but details of the mechanism are not understood yet. A systematic study was carried out using O2 and CO2 gases of different …
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Study of atmospheric carbon monoxide and methane
… d13C and dD of atmospheric CH4 as well as d13C, d18O and the 14CO concentrations of atmospheric CO at Izana, Tenerife, from 1996 to 1999. We report the first directly measured dD seasonality for atmospheric background CH4. The large seasonal cycles in mixing and isotopic ratios of CH4 and CO …
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Geochemistry of a volcanic hydrothermal system at Mount Spurr, Alaska
… (around 50 degrees C), acidic, bicarbonate-poor, d18O and dD-enriched waters from Crater Lake; 2) low temperature (14-40 degrees C), neutral, bicarbonate and Mg-rich, slightly d18O and dD-enriched peripheral waters from Crater Canyon, Kid Canyon, and South Spurr; and 3) cold (less than 9 degrees …
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Paläotemperaturstudie mit Edelgasen im Grundwasser der Nordchinesischen Tiefebene
… Differenz zwischen dem mittleren Wert für die d18O-Signatur in Phasen mit schwachem und starkem Monsun beträgt etwa 1.5(±0.2)‰.
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Spurenelementverteilungen in orogenen Granat-Peridotiten und Granat-Olivin-Websteriten als Indikator ihrer geochemischen und metamorphen Entwicklung
… charakterisiert. Die d18O-Werte der Porphyroklasten beider Peridotite deuten auf eine unterschiedliche Herkunft und Entwicklung der beiden Körper hin. Der Kalskaret-Granat-Olivin-Websterit zeichnet sich hinsichtlich der Haupt- und Spurenelemente durch sehr gut …
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Paleoclimate reconstructions over the last century from a tropical speleothem on Niue Island, South Pacific
… that interannual variability in the stalagmite d18O and d13C time series agrees well with instrumental-derived ENSO phases (El Niño and La Niña events during 1866-2002) and the sea level pressure differential (Samoa-Fiji)-based SPCZ index (SPI) that controls the interdecadal hydroclimate …
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Hydrogeologie, Hydrogeochemie und Isotopie der Grund- und Grubenwässer im Einzugsgebiet des Burgfeyer Stollens bei Mechernich/Eifel
… of environmental isotopes (d34S, d13C, d2H, d18O, d15N, 3H) and trace gases (CFC) of the upper and middle bunter sandstone groundwaters and of the mine waters have been performed in order derive a genetic model for the outflow waters of the Burgfeyer Stollen and identify the main chemical and …
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Petrology, geochemistry, stable and radiogenetic isotopy of the Guelb Moghrein iron oxide copper gold cobalt deposit, Mauritania
… by depletion of d13C values and enrichment of d18O values attributed to the partial decarbonation of siderite and subsequent equilibration with the hydrothermal fluid. The occurrence of graphite with siderite and magnetite, and the very light isotopic composition of graphite are consistent with …
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