Origin and influence of the superficial structure on the morphogenesis (Eocene plateaux of the eastern Paris Basin)

Pierre, Guillaume; Devos, Alain; Bollot, Nicolas

doi:10.1016/j.grj.2017.04.002

Cited by 2 publications

(1 citation statement)

References 18 publications

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“…L'origine des mardelles est associée aux déformations qui affectent les marnes du Keuper et à la formation de conduits permettant le soutirage des produits d'altération des marnes (argiles et limons résiduels). Les failles ou plis observées sur les coupes peuvent être liées à l'héritage tectonique ou à la déstabilisation des terrains causée par une dissolution en profondeur(Pierre et al, 2017). A une échelle spatiale plus large, le rôle de la fracturation du substratum est mis en évidence par les alignements de mardelles détectés sur le relevé Lidar dont les orientations sont proches celles du réseau de drainage naturel local.…”

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Origine, processus de formation et évolution des mardelles du Nord-Est du Bassin Parisien (France)

Ollive¹,

Wiethold²,

Klag³

et al. 2021

BSGF - Earth Sci. Bull.

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Thousands of sub-circular closed depressions or “mardelles” are observed on Keuper marls of the North-eastern Paris Basin. Their anthropogenic or geological origin is highly debated by archaeologists and naturalists since the first half of the 19th century. During rescue archaeological excavations along the high speed train line ‘LGV-Est Européenne’ seven closed sub-circular depressions were investigated to resolve the question of their origin, their formation processes and their evolution of their sedimentary filling. To that goal, a new field methodological approach combining geoarchaeology, archaeobotany and archaeology was carried out by the optimization of mechanical excavator. The realisation of long and deep trenches allowed direct observations of both substratum and sedimentary filling. This study evidences the natural origin of closed depressions by the play of the following processes: (1) Initiation of closed depressions is realised by ancient fractures affecting the Triassic marls; (2) Deepening of closed depressions is realised by alteration of superficial marls and residual clays passage down several wells formed through existing faults; (3) When the closed depression exists, the modifications of the shape of the closed depression's edges, is due to degradation of marl blocks; (4) The following sedimentary filling traduces environmental conditions influenced by forest evolution and land use changes since Antiquity. Direct observations at the scale of closed depression complete spatial information from a Lidar survey along the LGV-Est line. The analysis of this survey shows alignments of closed depressions with orientations similar to those of the drainage system, the origin of which is probably linked to the fracturing of the Keuper marls. Finally, even if a process of natural formation is envisaged, a role of human activity in the initiation of the process could be envisaged in particular by the action on the evolution of the land use (plant cover) and thus in the marls karstogenesis.

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Origine, processus de formation et évolution des mardelles du Nord-Est du Bassin Parisien (France)

Ollive¹,

Wiethold²,

Klag³

et al. 2021

BSGF - Earth Sci. Bull.

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Hydrogeology of a landslide: a case study in the Montagne de Reims (Paris basin, France)

Bollot

Pierre

Devos

et al. 2022

QJEGH

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Investigations of hydric and hydrogeological mechanisms that contribute to the current reactivation of mass-movements feed predictive models that can be useful for risk management. Ours are based on an approach combining 1/ a large scale analysis of the landforms, using LiDAR imagery and field observations, 2/ a characterization of the groundwater (piezometry, conductivity and temperature), both in the landslide and in the stable slope, and 3/ electrical resistivity profiles. These combined data allow the reconstruction of the structure of the landslide to determine its influence on groundwater flow. The Saint Maur landslide bars the main aquifer of the Upper Ypresian sands whose slow flow results in lower piezometric level fluctuations and stronger mineralization than found in the unconfined aquifer on either side of the slip. The confined aquifer emptying occurs through the sliding plane so that the landslide aquifer is fed essentially by capillary rise from the shear plane and to a lesser extent by surface infiltration. Therefore, the amount of water in the landslide and the resulting probability of mass movement are weakly correlated with rainfall events. In addition, the wide dispersion of the conductivity values of the landslide aquifer reflects a weak mixing of the water. Groundwater circulation modelling allows to correct in situ – i.e. underground – the flows causing reactivations, and confirms stabilization by hydro-geological action to be more efficient than a surface drainage.Thematic collection: This article is part of the Role of water in destabilizing slopes collection available at: https://www.lyellcollection.org/cc/role-of-water-in-destabilizing-slopes

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Origin and influence of the superficial structure on the morphogenesis (Eocene plateaux of the eastern Paris Basin)

Cited by 2 publications

References 18 publications

Origine, processus de formation et évolution des mardelles du Nord-Est du Bassin Parisien (France)

Origine, processus de formation et évolution des mardelles du Nord-Est du Bassin Parisien (France)

Hydrogeology of a landslide: a case study in the Montagne de Reims (Paris basin, France)

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