Preprints
https://doi.org/10.5194/se-2021-2
https://doi.org/10.5194/se-2021-2

  04 Feb 2021

04 Feb 2021

Review status: a revised version of this preprint is currently under review for the journal SE.

U-Pb dating of middle Eocene-middle Pleistocene multiple tectonic pulses in the Alpine foreland

Luca Smeraglia1,2,a, Nathan Looser3, Olivier Fabbri2, Flavien Choulet2, Marcel Guillong3, and Stefano M. Bernasconi3 Luca Smeraglia et al.
  • 1National Research Council, IGAG, Rome, Italy
  • 2Chrono-Environnement, UMR 6249, Université de Bourgogne-Franche Comté, 25000 Besançon, France
  • 3Geological Institute, ETH Zürich, Sonneggstrasse 5, 8092 Zürich, Switzerland
  • aformerly at: Dipartimento di Scienze della Terra, Sapienza Università di Roma, P.le Aldo Moro 5, 00185, Roma

Abstract. Foreland fold-and-thrust belts record long-lived tectonic-sedimentary activity, from passive margin sedimentation, flexuring, and further involvement into wedge accretion ahead of an advancing orogen. Therefore, dating fault activity is fundamental for plate movement reconstruction, resource exploration, or earthquake hazard assessment. Here, we report U-Pb ages of syntectonic calcite mineralizations from four thrusts and three tear faults sampled, at the regional scale, across the Jura fold-and-thrust belt in the northwestern Alpine foreland (eastern France). Four regional tectonic phases are recognized in the middle Eocene-middle Pleistocene interval: (1) pre-orogenic faulting at 44.7 ± 2.6 and 48.4 ± 1.5 Ma associated to the uplift of the Alpine forebulge, (2) syn-orogenic thrusting at 11.4 ± 1.1, 10.6 ± 0.5, 9.7 ± 1.4, 9.6 ± 0.3, and 7.5 ± 1.1 Ma associated to possible in-sequence thrust propagation, and (3) syn-orogenic tear faulting at 10.5 ± 0.4, 9.1 ± 6.5, 7.3 ± 1.9, 5.7 ± 4.7, 4.8 ± 1.7, and at 0.7 ± 4.2 Ma including the reactivation of a pre-orogenic fault as tear fault at 3.9 ± 2.9 Ma. Previously unknown faulting events at 44.7 ± 2.6 and 48.4 ± 1.5 Ma predate by ~ 10 Ma the accepted late Eocene age for tectonic activity onset in the Alpine foreland. In addition, we dated the previously inferred strike-slip faults re-activation as tear fault. The U-Pb ages demonstrate the long-lived tectonic history at the plate boundary between European and African plates and that the deformation observed in the foreland is directly linked to continental collision.

Luca Smeraglia et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on se-2021-2', Olivier Lacombe, 26 Feb 2021
    • AC1: 'Reply on RC1', Nathan Looser, 04 Jun 2021
  • RC2: 'Comment on se-2021-2', Nick Roberts, 22 Mar 2021
    • AC2: 'Reply on RC2', Nathan Looser, 04 Jun 2021

Luca Smeraglia et al.

Luca Smeraglia et al.

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