U-Pb dating of a speleothem of Quaternary age

Richards, David A.; Bottrell, Simon H.; Cliff, R. A.; Strohle, K; Rowe, Peter

doi:10.1016/s0016-7037(98)00256-7

Cited by 96 publications

(57 citation statements)

References 26 publications

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“…It is applicable to materials from less than 1 million years old (e.g., Richards et al, 1998) to the age of the solar system (e.g., Amelin et al, 2002). This is in part a result of the dual decay of 238 U and 235 U, which aids evaluation of closed-system behaviour, the precision to which the U decay constants have been determined (±0.11 and 0.14% 2r for k 238 U and k 235 U respectively; Jaffey et al, 1971;Mattinson, 2010), and the occurrence of minerals that preferentially incorporate U over Pb during crystallisation (e.g., zircon, xenotime etc.…”

Section: Introductionmentioning

confidence: 99%

Metrology and Traceability of U-Pb Isotope Dilution Geochronology (EARTHTIME Tracer Calibration Part I)

Condon¹,

Schoene²,

McLean³

et al. 2017

Preprint

113

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Mixed 235 U-233 U-205 Pb (-202 Pb) tracers for U-Pb isotope-dilution isotope ratio mass spectrometry have been prepared under the auspices of the EARTHTIME Initiative. The methods and results for the preparation and calibration of the U/Pb ratio and isotopic abundances are given, and the various sources of uncertainty are discussed and quantified. The accuracy of the EARTHTIME U-Pb tracer isotopic composition can be traced back to SI units via a series of assay and isotopic composition reference materials combined with the experiments described herein. The parameters used in calculating U/Pb ratios (and inferentially U-Pb dates) have correlated uncertainties that result in a total uncertainty contribution to 206 Pb/ 238 U dates of ± < 0.03% (95% confidence). For suitable terrestrial materials such as zircon, when other sources of uncertainty have been minimised (e.g., open-system behaviour, 238 U/ 235 U variation, intermediate daughter product disequilibrium, common Pb, etc.) the U-Pb tracer calibration uncertainty is a limiting factor in the accuracy of U-Pb geochronology -but less so than the uncertainty in the 238 U and 235 U decay constants (±0.11 and 0.14% 2r). The calibration approach of the mixed EARTHTIME 235 U-233 U-205 Pb (-202 Pb) tracers, in addition to updated values for reference materials (e.g., mixed gravimetric reference solutions), and parameters (e.g., Pb reference material assay), can be applied to other laboratory-specific U-Pb tracers and will facilitate the generation of accurate and directly inter-comparable U-Pb data.

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Section: Introductionmentioning

confidence: 99%

Metrology and Traceability of U-Pb Isotope Dilution Geochronology (EARTHTIME Tracer Calibration Part I)

Condon¹,

Schoene²,

McLean³

et al. 2017

Preprint

113

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“…calcite) have been the subject of scientific interest due to the use of trace element ratios in carbonate minerals for paleoenvironmental reconstruction [1][2][3] and in dating techniques [4,5]. It has also been proposed that divalent radionuclides (such as 60 Co 2+ and 90 Sr 2+ ) can be sequestered during subsurface in situ carbonate mineral formation offering a suitable route for limiting their migration at contaminated land sites [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Enhanced Strontium Uptake into Calcite via an Amorphous Calcium Carbonate Crystallization Pathway

Littlewood

Shaw

Peacock

et al. 2017

Crystal Growth & Design

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ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Mechanism of enhanced strontium uptake into calcite via an amorphous calcium carbonate (ACC) crystallisation pathway

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“…Cave breccias have been the focus of much previous geological research (Brain, 1958;Partridge, 1979;Herries, Curnoe, & Adams, 2009) due to their direct association with the fauna. Speleothems (cave precipitates) are less closely associated with the faunal remains, but are far more amenable to geochemical techniques such as uranium-lead dating (Richards et al, 1998;Walker, Cliff, & Latham, 2006) and paleoenvironmental reconstruction using light stable isotopes (McDermott, 2004;Hopley et al, 2007b).…”

Section: Introductionmentioning

confidence: 99%

Speleothem preservation and diagenesis in South African hominin sites implications for paleoenvironments and geochronology

2009

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Plio-Pleistocene speleothems from australopithecine-bearing caves of South Africa have the potential to yield paleoenvironmental and geochronological information using isotope geochemistry. Prior to such studies it is important to assess the preservation of geochemical signals within the calcitic and aragonitic speleothems, given the tendency of aragonitic speleothems to recrystallize to calcite. This study documents the geochemical suitability of speleothems from the principal hominin-bearing deposits of South Africa. We use petrography, together with stable isotope and trace element analysis, to identify the occurrence of primary aragonite, primary calcite, and secondary calcite. This study highlights the presence of diagenetic alteration at many of the sites, often observed as interbedded primary and secondary fabrics. Trace element and stable isotopic values distinguish primary calcite from secondary calcite and offer insights into geochemical aspects of the past cave environment. O. High carbon isotope values in these deposits are associated with the effects of recrystallization and rapid outgassing of CO 2 during precipitation. Mg/Ca and Sr/Ca ratios differ between primary and secondary calcite speleothems, aiding their identification. Carbon and oxygen isotope values in primary calcite reflect the proportion of C 3 and C 4 vegetation in the local environment and the oxygen isotope composition of rainfall. Primary calcite speleothems preserve the pristine geochemical signals vital for ongoing paleoenvironmental and geochronological research.

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U-Pb dating of a speleothem of Quaternary age

Cited by 96 publications

References 26 publications

Metrology and Traceability of U-Pb Isotope Dilution Geochronology (EARTHTIME Tracer Calibration Part I)

Metrology and Traceability of U-Pb Isotope Dilution Geochronology (EARTHTIME Tracer Calibration Part I)

Mechanism of Enhanced Strontium Uptake into Calcite via an Amorphous Calcium Carbonate Crystallization Pathway

Speleothem preservation and diagenesis in South African hominin sites implications for paleoenvironments and geochronology

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