# New insights on the regional architecture and dynamics of mixed fluvio-aeolian deposits from Middle Buntsandstein in the southern margin of the German Basin

Gaspard Dewaele, Sophie Leleu, Rémy Deschamps, Sylvie Bourquin, Fadi H Nader, Jean Marie Mengus, Adrian Hartley

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## To cite this version:

Gaspard Dewaele, Sophie Leleu, Rémy Deschamps, Sylvie Bourquin, Fadi H Nader, et al.. New insights on the regional architecture and dynamics of mixed fluvio-aeolian deposits from Middle Buntsandstein in the southern margin of the German Basin. 29 ème édition de la réunion des sciences de la Terre (RST 2025), Oct 2025, Montpellier, France. pp.658920, 2025. insu-05376516

HAL Id: insu-05376516

https://insu.hal.science/insu-05376516v1

Submitted on 21 Nov 2025

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Distributed under a Creative Commons Attribution 4.0 International License
New insights on the regional architecture and
dynamics of mixed fluvio-aeolian deposits from
Middle Buntsandstein in the southern margin of the
German Basin

Gaspard Dewaele*¹,², Sophie Leleu†¹,³, Rémy Deschamps‡², Sylvie Bourquin§⁴, Fadi H. Nader¶²,⁵, Jean Marie Mengus||², and Adrian Hartley**⁶

¹UMR CNRS 5805 (EPOC) – UMR5805 EPOC, University of Bordeaux, Pessac, France – France

²IFP Energies Nouvelles – IFP Energies Nouvelles, IFP Energies Nouvelles – France

³Institut Polytechnique de Bordeaux – Bordeaux INP, ENSEGID – France

⁴Géosciences Rennes – Université de Rennes, Institut National des Sciences de l'Univers, Centre National de la Recherche Scientifique – France

⁵Universiteit Utrecht / Utrecht University [Utrecht] – Pays-Bas

⁶University of Aberdeen (UoA) – School of Geosciences, Meston Building, Aberdeen AB 24 3 UE, Royaume-Uni

Résumé

During the Lower Triassic, the German Basin in central Europe was bordered by the London-Brabant Massif, the Fennoscandian High, and the Bohemian Massif. This endorheic basin experienced an overall arid climate punctuated by humid phases enhancing runoff from adjacent highlands. Perennial and ephemeral fluvial systems are believed to have occurred across arid alluvial plains in the southern margin of the basin, with interbedded aeolian sediments preserved.

In north-eastern France (southern margin of the basin), well-preserved Lower Triassic con-
tinental sandstones allowed us to undertake a detailed sedimentological analysis based on
outcrops and core data spanning the Middle Buntsandstein. Three main facies associa-
tions can be distinguished, mainly based on sediment transport processes: (i) fluvial facies-
amalgamated cross-bedded pebbly to fine sandstones interpreted as long-lasting or episodic
river systems, (ii) mixed fluvio-aeolian facies-splays deposited attributed to ephemeral lakes
or playas deposits, and (iii) pure aeolian facies-dune and sand-flat deposits supposedly de-
posited in dry or damp interdunes.

This study focuses on a sub-basin inherited from the Saar-Nahe Carboniferous-Permian
basin. A presumed paleo-fairway, bordered by the Bohemian and Rhenish massifs and the

<footnote>*Intervenant</footnote>

<footnote>†Auteur correspondant: sophie.leleu@bordeaux-inp.fr</footnote>

<footnote>‡Auteur correspondant: remy.deschamps@ifpen.fr</footnote>

<footnote>§Auteur correspondant: sylvie.bourquin@univ-rennes.fr</footnote>

<footnote>¶Auteur correspondant: fadi-henri.nader@ifpen.fr</footnote>

<footnote>||Auteur correspondant: jean-marie.mengus@ifpen.fr</footnote>

<footnote>**Auteur correspondant: a.hartley@abdn.ac.uk</footnote>
Variscan belt to the south, guided sediment transport and accumulation. Our dataset in-
cludes a new 140 m-long core within the lowermost part of the succession located in Freyming-
Merlebach and a 2 km-long quarry outcrop with a Digital Outcrop Model, the Barrois quarry,
within the uppermost part of the succession. Within the fairway, the Middle Buntsandstein
succession transitions from proximal fluvial conglomerates to aeolian and playa sandstones,
reflecting variations in aridity. After a maximum of aridity recorded with playa and aeolian
deposits, fluvial systems were reactivated, followed by a major conglomerate progradation
and topped by paleosoils unevenly truncated by the Hardegsen Unconformity. Our study
provides a west-to-east regional-scale log correlation using 3 regional key wells and our new
dataset. This transect shows that during arid periods, preserved dune fields are located
mainly in the west while playa-type deposits are dominant in the east. These facies vari-
ations suggest spatial and temporal facies partitioning due to climate changes and basin
morphology, offering insights into the dynamic evolution of the basin under fluctuating en-
vironmental conditions.

**Mots-Clés:** Middle Buntsandstein, Fluvial and aeolian deposits, Sedimentary architecture, Cyclicity of deposits, Preservation factor