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Geochronology Advances in geochronological science
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https://doi.org/10.5194/gchron-2020-11
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gchron-2020-11
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

  05 May 2020

05 May 2020

Review status
This preprint is currently under review for the journal GChron.

An evaluation of Deccan Traps eruption rates using geochronologic data

Blair Schoene1, Michael P. Eddy2, C. Brenhin Keller3, and Kyle M. Samperton4 Blair Schoene et al.
  • 1Department of Geosciences, Princeton University, Princeton, NJ 08544, USA
  • 2Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47907, USA
  • 3Department of Earth Sciences, Dartmouth College, Hanover, NH 03755, USA
  • 4Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA

Abstract. Recent attempts to establish the eruptive history of the Deccan Traps large igneous province have used both U-Pb (Schoene et al., 2019) and 40Ar/39Ar (Sprain et al., 2019) geochronology. Both of these studies report dates with high precision and unprecedented coverage for a large igneous province, and agree that the main phase of eruptions began near the C30n-C29r magnetic reversal and waned shortly after the C29r-C29n reversal, totaling ~700-800 ka duration. Nevertheless, the eruption rates interpreted by the authors of each publication differ significantly. The U-Pb dataset was interpreted to indicate four major eruptive pulses, while the 40Ar/39Ar dataset was used to argue for an increase in eruption rates coincident with the Chicxulub impact (Renne et al., 2015; Richards et al., 2015). Although the overall agreement in duration is an achievement for geochronology, the disparate eruption models may act to undermine this achievement in the eyes of the broader geologic community. Here, we generate chronostratigraphic models for both datasets using the same statistical techniques and conclude that 1) age modeling of the 40Ar/39Ar dataset results in constant eruption rates with relatively large uncertainties through the duration of the Deccan Traps, and cannot verify or disprove the pulses identified by the U-Pb data, 2) the stratigraphic position of the Chicxulub impact within the 40Ar/39Ar dataset is much more uncertain than was presented in Sprain et al. (2019), and 3) neither dataset supports an increase in eruption rate as a result of the Chicxulub impact. While the production of precise and accurate geochronologic data is of course essential to studies of Earth History, our analysis underscores that the accuracy of a final result also is critically dependent on how such data are interpreted and presented to the broader community of geoscientists.

Blair Schoene et al.

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Blair Schoene et al.

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Latest update: 26 Sep 2020
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Short summary
We compare two published U-Pb and 40Ar/39Ar geochronologic datasets used to produce different eruption rate models for the Deccan Traps LIP. We conclude that differences in eruption rates arise not from inaccuracy of dates, but instead from the way the data were presented. Applying the same statistical approach to each dataset, the resulting models agree well, but the higher precision U-Pb dataset generates a more nuanced eruption model that is untestable with the lower precision 40Ar/39Ar data.
We compare two published U-Pb and 40Ar/39Ar geochronologic datasets used to produce different...
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