Browsing by Author "O'Nions R.K."
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Browsing by Author "O'Nions R.K."
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O'Nions R.K.; Tolstikhin I.N. (1994)The residence time of highly incompatible lithophile elements in the upper mantle such as Th, U and Pb has previously been estimated at ⩽ 1 Ga. The concept of steady-state residence time is extended to include He and other ...
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Zhu X.K.; O'Nions R.K.; Guo Y.; Belshaw N.S.; Rickard D. (2000)Techniques for the high precision measurement of 65Cu/63Cu ratios by multiple-collector plasma-source mass spectrometry has been developed. Two approaches, namely Zn-doping and ''sample-standard bracketing'', have been ...
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Porcelli D.R.; O'Nions R.K.; O'Reilly S.Y. (1986)The isotopic compositions of He and Sr have been obtained for suites of ultramafic xenoliths brought to the surface by Recent volcanic eruptions in continental environments. Samples include a range of petrologic types from ...
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Zhu X.K.; O'Nions R.K.; Belshaw N.S.; Gibb A.J. (1997)A combination of detailed petrography and in situ SIMS 207Pb/206Pb micro-chronometry of monazite has been carried out on samples from the Lewisian high-grade metamorphic terrain, northwest Scotland. Two episodes of ...
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O'Nions R.K.; Tolstikhin I.N. (1996)Geochemical arguments for a layered mantle based upon both lithophile and rare gas element abundances are well established. The negative Clayperon slope, associated with phase changes at 670 km, is expected to impede ...
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O'Nions R.K.; Tolstikhin I.N. (1996)Geochemical arguments for a layered mantle based upon both lithophile and rare gas element abundances are well established. The negative Clayperon slope, associated with phase changes at 670 km, is expected to impede ...
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Zhu X.K.; Guo Y.; Williams R.J.P.; O'Nions R.K.; Matthews A.; Belshaw N.S.; Canters G.W.; de Waal E.C.; Weser U.; Burgess B.K.; Salvato B. (2002)Recent advances in mass spectrometry make it possible to utilise isotope variations of transition metals to address some important issues in solar system and biological sciences. Realisation of the potential offered by ...
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Zhu X.K.; O'Nions R.K. (1999)An investigation of the chemical composition of monazite from a number of localities has been carried out. Samples used include monazites from metamorphic rocks, granitic rocks and a hydrothermal ore deposit. The REE ...
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McKenzie D.; O'Nions R.K. (1991)Inverse theory is used to calculate the melt distribution required to produce the rare earth element concentrations in a wide variety of terrestrial and extra-terrestrial magmas. The concentrations of the major and minor ...
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Zhu X.K.; O'Nions R.K.; Gibb A.J. (1998)The calibration of U-Pb and Th-Pb ratios in Th-U-rich minerals measured by SIMS usually assumes that there are no matrix effects arising from the compositional difference between standard and sample. Matrix effects have ...
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THE EARTHS MISSING XENON: A COMBINATION OF EARLY DEGASSING AND OF RARE GAS LOSS FROM THE ATMOSPHERE Tolstikhin I.N.; O'Nions R.K. (1994)The under-abundance of Xe in the Earth's atmosphere relative to solar system abundances has been long recognised and is usually referred to as the “missing xenon problem”. It is suggested here that this feature of the ...
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David K.; Frank M.; O'Nions R.K.; Belshaw N.S.; Arden J.W. (2001)This paper presents a revised chemical purification method of Hf for the measurement of Hf isotope ratios of Fe-Mn crusts on a new generation of double focusing multiple collector plasma source mass spectrometer (MC-ICP-MS).By ...
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