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U–Pb dating of cements in Mesozoic ammonites

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U–Pb dating of cements in Mesozoic ammonites. / Li, Q.; Parrish, R. R.; Horstwood, M. S. A.; McArthur, J. M.

In: Chemical Geology, Vol. 376, 29.05.2014, p. 76-83.

Research output: Contribution to journalArticlepeer-review

Harvard

Li, Q, Parrish, RR, Horstwood, MSA & McArthur, JM 2014, 'U–Pb dating of cements in Mesozoic ammonites', Chemical Geology, vol. 376, pp. 76-83. https://doi.org/10.1016/j.chemgeo.2014.03.020

APA

Li, Q., Parrish, R. R., Horstwood, M. S. A., & McArthur, J. M. (2014). U–Pb dating of cements in Mesozoic ammonites. Chemical Geology, 376, 76-83. https://doi.org/10.1016/j.chemgeo.2014.03.020

Vancouver

Li Q, Parrish RR, Horstwood MSA, McArthur JM. U–Pb dating of cements in Mesozoic ammonites. Chemical Geology. 2014 May 29;376:76-83. https://doi.org/10.1016/j.chemgeo.2014.03.020

Author

Li, Q. ; Parrish, R. R. ; Horstwood, M. S. A. ; McArthur, J. M. / U–Pb dating of cements in Mesozoic ammonites. In: Chemical Geology. 2014 ; Vol. 376. pp. 76-83.

Bibtex

@article{896306001ae2414ab6d28490dded268d,
title = "U–Pb dating of cements in Mesozoic ammonites",
abstract = "Dating sedimentary carbonates using the U-Pb method can help improve the Phanerozoic timescale. Using a novel combination of laser-ablation, multi-collector, inductively-coupled-plasma, mass-spectrometry (LA–MC–ICP–MS) and thermal ionization multi-collector mass spectrometry (TIMS), U-Pb numerical ages were obtained on early-diagenetic calcite cements in Jurassic ammonites in which concentrations of U range from 0.47 to 5.3 ppm. The calcite cements of two ammonites, IS1 and IS2, from the uppermost Bifrons Zone of the Toarcian (179–180 Ma) of the UK, gave TIMS-normalized LA U–Pb dates of 164.9 ± 5.3 Ma and 166.7 ± 4.8 Ma respectively. Normalizing LA–ICP–MC–MS data to an in-house calcite standard gave a more precise date of 165.5 ± 3.3 Ma for IS1 cement. An unzoned ammonite, SS2, of Bajocian age (168–170 Ma) yield a TIMS-normalized LA U–Pb age of 158.8 ± 4.3 Ma for its early-diagenetic cement. Both the combined LA–MC–ICP–MS and TIMS approach, and the use of a calcite laser ablation standard can result in accurate ages of cements with uncertainties of 2–3% (2σ). The later, however, is more efficient and precise. These U-Pb dates of cements are 10 to 20 Myr younger than the numerical ages of the biostratigraphic intervals from which the ammonites derive. The U-Pb dates are taken to represent the time at which the aragonite shell of the ammonite inverted to calcite and released its U to precipitate in a late-diagenetic alteration of early-diagenetic fringing cements. Concentrations of U and Pb in a range of other pristine biogenic carbonates were found too low (U < 0.01 ppm) for meaningful dating using laser ablation method.",
author = "Q. Li and Parrish, {R. R.} and Horstwood, {M. S. A.} and McArthur, {J. M.}",
note = "Open Access funded by Natural Environment Research Council",
year = "2014",
month = may,
day = "29",
doi = "10.1016/j.chemgeo.2014.03.020",
language = "English",
volume = "376",
pages = "76--83",
journal = "Chemical Geology",
issn = "0009-2541",
publisher = "Elsevier",

}

RIS

TY - JOUR

T1 - U–Pb dating of cements in Mesozoic ammonites

AU - Li, Q.

AU - Parrish, R. R.

AU - Horstwood, M. S. A.

AU - McArthur, J. M.

N1 - Open Access funded by Natural Environment Research Council

PY - 2014/5/29

Y1 - 2014/5/29

N2 - Dating sedimentary carbonates using the U-Pb method can help improve the Phanerozoic timescale. Using a novel combination of laser-ablation, multi-collector, inductively-coupled-plasma, mass-spectrometry (LA–MC–ICP–MS) and thermal ionization multi-collector mass spectrometry (TIMS), U-Pb numerical ages were obtained on early-diagenetic calcite cements in Jurassic ammonites in which concentrations of U range from 0.47 to 5.3 ppm. The calcite cements of two ammonites, IS1 and IS2, from the uppermost Bifrons Zone of the Toarcian (179–180 Ma) of the UK, gave TIMS-normalized LA U–Pb dates of 164.9 ± 5.3 Ma and 166.7 ± 4.8 Ma respectively. Normalizing LA–ICP–MC–MS data to an in-house calcite standard gave a more precise date of 165.5 ± 3.3 Ma for IS1 cement. An unzoned ammonite, SS2, of Bajocian age (168–170 Ma) yield a TIMS-normalized LA U–Pb age of 158.8 ± 4.3 Ma for its early-diagenetic cement. Both the combined LA–MC–ICP–MS and TIMS approach, and the use of a calcite laser ablation standard can result in accurate ages of cements with uncertainties of 2–3% (2σ). The later, however, is more efficient and precise. These U-Pb dates of cements are 10 to 20 Myr younger than the numerical ages of the biostratigraphic intervals from which the ammonites derive. The U-Pb dates are taken to represent the time at which the aragonite shell of the ammonite inverted to calcite and released its U to precipitate in a late-diagenetic alteration of early-diagenetic fringing cements. Concentrations of U and Pb in a range of other pristine biogenic carbonates were found too low (U < 0.01 ppm) for meaningful dating using laser ablation method.

AB - Dating sedimentary carbonates using the U-Pb method can help improve the Phanerozoic timescale. Using a novel combination of laser-ablation, multi-collector, inductively-coupled-plasma, mass-spectrometry (LA–MC–ICP–MS) and thermal ionization multi-collector mass spectrometry (TIMS), U-Pb numerical ages were obtained on early-diagenetic calcite cements in Jurassic ammonites in which concentrations of U range from 0.47 to 5.3 ppm. The calcite cements of two ammonites, IS1 and IS2, from the uppermost Bifrons Zone of the Toarcian (179–180 Ma) of the UK, gave TIMS-normalized LA U–Pb dates of 164.9 ± 5.3 Ma and 166.7 ± 4.8 Ma respectively. Normalizing LA–ICP–MC–MS data to an in-house calcite standard gave a more precise date of 165.5 ± 3.3 Ma for IS1 cement. An unzoned ammonite, SS2, of Bajocian age (168–170 Ma) yield a TIMS-normalized LA U–Pb age of 158.8 ± 4.3 Ma for its early-diagenetic cement. Both the combined LA–MC–ICP–MS and TIMS approach, and the use of a calcite laser ablation standard can result in accurate ages of cements with uncertainties of 2–3% (2σ). The later, however, is more efficient and precise. These U-Pb dates of cements are 10 to 20 Myr younger than the numerical ages of the biostratigraphic intervals from which the ammonites derive. The U-Pb dates are taken to represent the time at which the aragonite shell of the ammonite inverted to calcite and released its U to precipitate in a late-diagenetic alteration of early-diagenetic fringing cements. Concentrations of U and Pb in a range of other pristine biogenic carbonates were found too low (U < 0.01 ppm) for meaningful dating using laser ablation method.

U2 - 10.1016/j.chemgeo.2014.03.020

DO - 10.1016/j.chemgeo.2014.03.020

M3 - Article

VL - 376

SP - 76

EP - 83

JO - Chemical Geology

JF - Chemical Geology

SN - 0009-2541

ER -

ID: 4233527