Search results for "pluto"
showing 10 items of 90 documents
Record of 1.82 Ga Andean-type continental arc magmatism in NE Rajasthan, India: Insights from zircon and Sm–Nd ages, combined with Nd–Sr isotope geoc…
2009
Abstract We document a Palaeoproterozoic Andean-type continental arc granitoid emplacement event in the northwestern segment of the Aravalli mountain range, NW India. Our study is focused on the Jasrapur pluton which is dominated by monzogranites with a subordinate amount of granodiorite and quartz monzodiorite. These rocks carry typical continental arc geochemical signatures, such as high-K calc-alkaline, mildly peraluminous, I-type and magnesian features, as well as high Rb and low Nb, Y and Rb/Zr ratios, decoupling between LILE and HFSE, and negative Nb–Ta and Ti anomalies. Conventional geothermobarometric estimates suggest high temperature (~ 800 °C) and pressure (≥ 600 MPa) conditions …
Speciation of the oxidation states of plutonium in aqueous solutions by UV/Vis spectroscopy, CE-ICP-MS and CE-RIMS
2007
For the speciation of the plutonium oxidation states in aqueous solutions, the online coupling of capillary electrophoresis (CE) with inductively coupled plasma mass spectrometry (ICP-MS) has been developed. Depending on the radius/electrical charge ratio, the oxidation states III, IV, V, and VI of plutonium are separated by CE, based on the different migration times through the capillary and are detected by ICP-MS. The detection limit is 20 ppb,i.e.109–1010atoms (10-12–10-13g) for one oxidation state with an uncertainty of the reproducibility of the migration times of ≤1% and ≤5% for the peak area. The redox kinetics of the different plutonium oxidation states in the presence of humic subs…
Stabilization of polynuclear plutonium(IV) species by humic acid
2014
Abstract Although the formation of tetravalent plutonium (Pu(IV)) polymers with natural organic matter was previously observed by spectroscopy, there is no quantitative evidence of such reaction in batch experiments. In the present study, Pu(IV) interaction with humic acid (HA) was investigated at pH 1.8, 2.5 and 3, as a function of HA concentration and for Pu total concentration equal to 6 × 10−8 M. The finally measured Pu(IV) concentrations ([Pu(IV)]eq) are below Pu(IV) solubility limit. Pu(IV)–HA interaction can be explained by the complexation of Pu(IV) monomers by HA up to [Pu(IV)]eq ∼ 10−8 M. However, the slope of the log–log Pu(IV)–HA binding isotherm changes from ∼0.7 to ∼3.5 for hi…
Plutonium(III) complexation by humic substances studied by X-ray absorption fine structure spectroscopy
2006
Abstract We determined structural parameters for the near-neighbor surrounding of plutonium(III) in complexes with humic and fulvic acids at pH 1 and for the purpose of comparison also for the plutonium(III) aquo ion by means of X-ray absorption fine structure (XAFS) spectroscopy. It could be shown that in the complexes with humic substances as well as in the plutonium(III) aquo ion sample the trivalent oxidation state of plutonium was stable within the time of the experiment. In the humate and fulvate complexes, the plutonium(III) is surrounded by about eight oxygen atoms with an average Pu–O distance of 2.48 ± 0.02 A. The structural parameters determined for plutonium(III)–humate and –ful…
Sesquiterpene lactones from Anthemis plutonia.
1998
Abstract Aerial parts of Anthemis plutonia furnished three guaianolides, one of them new.
Depth profiling of Pu, 241Am and 137Cs in soils from southern Belarus measured by ICP-MS and alpha- and gamma-spectrometry
2003
The depth distribution of plutonium, americium, and Cs-137 originating front the 1986 accident at the Chernobyl Nuclear Power Plant (NPP) was investigated in several soil profiles in the vicinity from Belarus. The vertical migration of transuranic elements in soils typical of the 30 km relocation area around Chernobyl NPP was studied using inductively coupled plasma mass spectrometry (ICP-MS), alpha spectrometry, and gamma spectrometry. Transuranic concentrations in upper soil layers ranged from 6 x 10(-12) g g(-1) to 6 x 10(-10) g g(-1) for plutonium and from 1.8 x 10(-13) g g(-1) to 1.6 x 10(-11) g g(-1) for americium. These concentrations correspond to specific activities of Pu239+240 of…
Temperature, fluid content and rheology of localized ductile shear zones in subsolidus cooling plutons
2020
Temperature and fluid content are critical parameters that control rock rheology and strain localization in the continental crust. Here, we determine by thermodynamic modelling the urn:x-wiley:02634929:media:jmg12553:jmg12553-math-0004 of localized ductile shearing during cooling of three different granitoid plutons: the Rieserferner and the Adamello plutons in the Italian Alps, and the Lake Edison pluton in the Sierra Nevada—USA. Shear zones exploited precursor joints, associated veins and alteration zones. urn:x-wiley:02634929:media:jmg12553:jmg12553-math-0005 and P−T phase diagram sections were computed with Perple_X in the system MnO−Na2O−CaO −K2O−FeO−MgO−Al2O3−SiO2−H2O−Fe2O3. The phase…
Variscan evolution of the Tanneron Massif, SE France, examined through U-Pb monazite ages
2008
The Tanneron massif belongs to the southernmost segment of the Variscan belt in France and is composed of migmatitic orthogneisses and paragneisses cross-cut by a main tonalite–granite complex. Late Carboniferous detrital basins are bounded by north–south-trending ductile to brittle normal faults and delineate three distinct zones. Our new isotope dilution U–Pb monazite dating indicates a pre-Variscan history in the central part of the massif recorded by monazites from an orthogneiss yielding ages from 440 to 410 Ma, whereas monazites from a migmatitic paragneiss record a late Carboniferous high- T event at 317 ± 1 Ma. In the eastern part, a migmatization event is recorded by monazites from…
Pressure-temperature evolution during two granulite-facies metamorphic events (2.62 and 2.02 Ga) in rocks from the Central Zone of the Limpopo Belt, …
2018
Abstract The Central Zone of the Limpopo Belt in southern Africa is a classical example of a polymetamorphic terrane that experienced three metamorphic events at 3.22 Ga (M1), 2.66–2.61 Ga (M2) and 2.02 (M3). However, the geodynamic significance of these events is controversial as their P-T evolution was poorly constrained. We present new petrological and geochronological data for the M2 and M3 events. The Neoarchean M2 event is well-preserved in samples from a newly discovered enclave of supracrustal and magmatic rocks in the 2.612 Ga Bulai pluton that shielded the enclave against a Paleoproterozoic M3 overprint, which is dominant in rocks exposed outside the pluton. P-T pseudosection mode…
How to make a transverse triple junction—New evidence for the assemblage of Gondwana along the Kaoko-Damara belts, Namibia
2016
T-shaped orogenic triple junctions between mobile belts usually form in two unrelated stages by subsequent and oblique continental collisions separated by a significant time span. Besides these “oblique triple junctions”, another type, named “transverse triple junctions”, may exist. Such junctions are created by a more complex mechanism of partly contemporaneous convergence of three cratons in a restricted time frame, involving strike slip. The Neoproterozoic–Cambrian Kaoko-Damara junction between the Rio de la Plata, Congo, and Kalahari cratons in Namibia is an example of such a transverse orogenic triple junction, formed by at least four subsequent but partly related deformation events. I…