Determination of radium isotope ratios and abundances in geological samples by thermal ionization mass spectrometry

Volpe, Alan M.; Olivares, José A.; Murrell, M. T.

doi:10.1021/ac00009a015

Cited by 99 publications

(57 citation statements)

References 7 publications

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“…Procedures for measurement of Ra and Ba are based on those from Volpe et al (1991), with the following major exceptions:…”

Section: Introduction Analytical Methodsmentioning

confidence: 99%

Uranium-Series Chronology of Subsurface Basalts, 9°31'N East Pacific Rise

Goldstein¹

1995

Proceedings of the Ocean Drilling Program, 142 Scientific Results

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Mass spectrometric measurements of 226 Ra/ 230 Th and 231 Pa/ 235 U disequilibria for subsurface axial basalts recovered during Leg 142 of the Ocean Drilling Program were used to determine relative crustal residence ages for mid-ocean ridge basalt (MORB) lavas and to investigate the temporal characteristics of crustal accretion within the axial summit caldera at 9°3l'N East Pacific Rise. Two core samples from the massive "ODP flow," located 0-6.6 m below surface, have lower 226 Ra/ 230 Th and 23ip a /235rj activity ra ti O s than a surface sample from this unit. The subsurface samples also have higher U, Th, and Ba concentrations, and higher Ba/Th but similar Th/U ratios relative to the surface sample. The variations in 226 Ra^3 0 Th and 231 Pa/ 235 U between the surface and subsurface samples can be attributed to differences in crustal residence age of 0.4-0.7 ± 0.3 ka and 0.3-1.3 ± 1.1 ka, respectively. Consequently, this upper extrusive unit appears to be composed of lavas with small differences in chemical composition and distinct eruption and/or magma chamber residence ages. Assuming that the oldest sample represents a stratigraphic and temporal endmember for this upper extrusive unit, a vertical accumulation rate of >IO m/ka can be estimated.

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“…Procedures for measurement of Ra and Ba are based on those from Volpe et al (1991), with the following major exceptions:…”

Section: Introduction Analytical Methodsmentioning

confidence: 99%

Uranium-Series Chronology of Subsurface Basalts, 9°31'N East Pacific Rise

Goldstein¹

1995

Proceedings of the Ocean Drilling Program, 142 Scientific Results

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“…(7) gives, respectively by the radium isotopes may serve to internally test and validate the model. As mass-spectrometric analyses of 226 Ra and 228 Ra (Volpe et al, 1991, Foster et al, 2004 and delay-coincidence counting of 224 Ra and 223 Ra (e.g., Moore and Arnold, 1996) in small-volume fluid samples continue to advance, such tests are feasible.…”

Section: Extending the Model To Ra And Th Isotopesmentioning

confidence: 99%

Modeling non-steady state radioisotope transport in the vadose zone – A case study using uranium isotopes at Peña Blanca, Mexico

Luo

Goldstein

et al. 2009

Geochimica et Cosmochimica Acta

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Current models using U-and Th-series disequilibria to study radioisotope transport in groundwater systems mostly consider a steady-state situation. These models have limited applicability to the vadose zone (UZ) where the concentration and migratory behavior of radioisotopes in fluid are often transitory. We present here, as a first attempt of its kind, a model simulating the non-steady state, intermittent fluid transport in vadose layers. It provides quantitative constraints on in-situ migration of dissolved and colloidal radioisotopes in terms of retardation factor and rock-water interaction (or water transit) time. For uranium, the simulation predicts that intermittent flushing in the UZ leads to a linear relationship between reciprocal U concentration and 234 U/ 238 U ratio in percolating waters, with the intercept and slope bearing information on the rates of dissolution and α-recoil of U isotopes, respectively. The general validity of the model appears to be borne out by the measurement of uranium isotopes in UZ waters collected at various times over a period during 1995-2006 from a site in the Peña Blanca mining district, Mexico, where the Nopal I uranium deposit is located. Enhanced 234 U/ 238 U ratios in vadose-zone waters resulting from lengthened non-flushing time as prescribed by the model provide an interpretative basis for using 234 U/ 238 U in cave calcites to reconstruct the regional changes in hydrology and climate. We also provide a theoretical account of the model's potential applications using radium isotopes.

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“…greater precision, smaller sample size and much faster determination Volpe et al, 1991). This new technique allowed to use 226 Ra as a tracer and/or chronometer for: i) recent magmatic processes (Volpe and Goldstein, 1993;ClaudeIvanaj et al, 1998;, ii) Holocene studies Staubwasser et al, submitted), iii) river, groundwater and hydrothermal systems Vigier et al, 2001) and iv) océanographie studies .…”

Section: Ii1 Introductionmentioning

confidence: 99%

“…This new technique allowed to use 226 Ra as a tracer and/or chronometer for: i) recent magmatic processes (Volpe and Goldstein, 1993;ClaudeIvanaj et al, 1998;, ii) Holocene studies Staubwasser et al, submitted), iii) river, groundwater and hydrothermal systems Vigier et al, 2001) and iv) océanographie studies . However, the determination of 226 Ra by TIMS requires the separation of a very high purity Ra fraction, because the presence of trace of elements such as Ca and Ba tends to inhibit the ionization of radium Volpe et al, 1991;. Usually, Ra extraction and purification have been performed in two distinct steps.…”

Section: Ii1 Introductionmentioning

confidence: 99%

“…Firstly, Ra and Ba are extracted from bulk samples using a cationic exchange resin. Secondly, the Ra-Ba separation is carried out by using either a cationic resin with ammonium EDTA elution Volpe et al, 1991) or a chromatographic Sr spec™ resin in HNO 3 . This last procedure provides an easier and more efficient Ba-Ra separation technique For seawater analysis, the low concentrations of 226 Ra (from 0.07 dpm/kg to 0.2 dpm/kg, see ) make necessary the processing of a large volume of water (a few hundred ml to several litres) even using the TIMS technique.…”

Section: Ii1 Introductionmentioning

confidence: 99%

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Traçage de la mobilité des radionucléides naturels en milieu sédimentaire profond à l'aide des déséquilibres radioactifs (234 U/238U) :

Deschamps¹

2004

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Determination of radium isotope ratios and abundances in geological samples by thermal ionization mass spectrometry

Cited by 99 publications

References 7 publications

Uranium-Series Chronology of Subsurface Basalts, 9°31'N East Pacific Rise

Uranium-Series Chronology of Subsurface Basalts, 9°31'N East Pacific Rise

Modeling non-steady state radioisotope transport in the vadose zone – A case study using uranium isotopes at Peña Blanca, Mexico

Traçage de la mobilité des radionucléides naturels en milieu sédimentaire profond à l'aide des déséquilibres radioactifs (234 U/238U) :

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