Preprints
https://doi.org/10.5194/egusphere-2024-2325
https://doi.org/10.5194/egusphere-2024-2325
05 Aug 2024
 | 05 Aug 2024

U-Pb direct dating on calcite paleosol nodules: first absolute age constraints on the Miocene continental succession of the Paris Basin

Vincent Monchal, Remi Rateau, Kerstin Drost, Cyril Gagnaison, Bastien Mennecart, Renaud Toullec, and David Chew

Abstract. Continental sedimentary successions are typically less complete and more poorly preserved than the marine record, leading to limited correlations between basins. Traditionally, intra-basin correlation employs radiometric dating of volcanic markers or relative dating based on the fossil record. However, volcanic markers may not always be present, and biostratigraphy relies on index fossils which are often sparse to absent in continental successions. Recent progress in carbonate U-Pb dating can improve correlations between continental successions by providing absolute age constraints on carbonate deposition and/or on syn- to post-depositional processes such as pedogenesis.

In this study, we analysed pedogenic calcite nodules within a continental Miocene succession in the southwestern Paris Basin (the important paleontological site at Mauvières quarry, France). Following multimethod petrographic characterisation of the samples, LA-ICP-MS U-Pb dating was employed to obtain formation ages on the pedogenic calcite nodules. The Tera-Wasserburg intercept ages from five nodules from the same horizon (19.3±1.3/1.4 Ma, 18.0±3.2/3.2 Ma, 19.11±0.84/0.94 Ma, 19.0±2.3/2.3 Ma and 19.4±2.7/2.7 Ma) are in excellent agreement with previous biostratigraphic constraints on the sequence. Petrographic evidence points to a single crystallisation event, and we conclude that the formation of the calcite nodules occurred at 19.34 ± 0.58/0.73 Ma (central age from a radial plot of the five Tera-Wasserburg intercept ages). This calcite formation age is regarded to represent a minimum depositional age of the strata hosting the root nodules. It provides the first direct age for the continental Miocene succession (and Neogene mammal zone MN3) of the Paris Basin and allows correlation with other continental basins independent of their fossil assemblages or when the fossil content is missing.

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Vincent Monchal, Remi Rateau, Kerstin Drost, Cyril Gagnaison, Bastien Mennecart, Renaud Toullec, and David Chew

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2325', Perach Nuriel, 09 Sep 2024
  • RC2: 'Comment on egusphere-2024-2325', Andreas Möller, 21 Nov 2024
Vincent Monchal, Remi Rateau, Kerstin Drost, Cyril Gagnaison, Bastien Mennecart, Renaud Toullec, and David Chew

Data sets

Supplementary Tables : U-Pb direct dating on calcite paleosol nodules: first absolute age constraints on the Miocene continental succession of the Paris Basin V. Monchal et al. https://doi.org/10.5281/zenodo.12799549

Vincent Monchal, Remi Rateau, Kerstin Drost, Cyril Gagnaison, Bastien Mennecart, Renaud Toullec, and David Chew

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Short summary
Sedimentary rocks are typically dated indirectly, by comparing the fossil content of basins with the geological timescale. In this study, we employed an absolute dating approach to date 19 million year old sediments in the Paris Basin, using uranium-lead dating of calcite nodules associated with soil formation. The precision of our new ages enable more accurate comparisons (independent of their fossil contents) between the Paris Basin and other basins of similar age.