Separation of rifting and lithospheric folding signatures in the NW-Alpine foreland

Abstract

International audienceThe development of the Alpine mountain belt has been governed by the convergence of the African and European plates since the Late Cretaceous. During the Cenozoic, this orogeny was accompanied with two major kinds of intraplate deformation in the NW-European foreland: (1) the European Cenozoic Rift System (ECRIS), a left-lateral transtensional wrench zone striking NNE-SSW between the western Mediterranean Sea and the Bohemian Massif; (2) long-wavelength lithospheric folds striking NE and located between the Alpine front and the North Sea. The present-day geometry of the European crust comprises the signatures of these two events superimposed on all preceding ones. In order to better define the processes and causes of each event, we identify and separate their respective geometrical signatures on depth maps of the pre-Mesozoic basement and of the Moho. We derive the respective timing of rifting and folding from sedimentary accumulation curves computed for selected locations of the Upper Rhine Graben. From this geometrical and chronological separation, we infer that the ECRIS developed mostly from 37 to 17 Ma, in response to north-directed impingement of Adria into the European plate. Lithospheric folds developed between 17 and 0 Ma, after the azimuth of relative displacement between Adria and Europe turned counter-clockwise to NW SE. The geometry of these folds (wavelength = 270 km; amplitude = 1,500 m) is consistent with the geometry, as predicted by analogue and numerical models, of buckle folds produced by horizontal shortening of the whole lithosphere. The development of the folds resulted in ca. 1,000 m of rock uplift along the hinge lines of the anticlines (Burgundy Swabian Jura and Normandy Vogelsberg) and ca. 500 m of rock subsidence along the hinge line of the intervening syncline (Sologne Franconian Basin). The grabens of the ECRIS were tilted by the development of the folds, and their rift-related sedimentary infill was reduced on anticlines, while sedimentary accumulation was enhanced in synclines. We interpret the occurrence of Miocene volcanic activity and of topographic highs, and the basement and Moho configurations in the Vosges Black Forest area and in the Rhenish Massif as interference patterns between linear lithospheric anticlines and linear grabens, rather than as signatures of asthenospheric plumes

The probabilistic seismic hazard assessment of Germany—version 2016, considering the range of epistemic uncertainties and aleatory variability

“…Volcanism accompanied this fragmentation of the upper crust of the WEP at different spots (Bourgeois et al 2007). The last volcanic eruptions occurred in the Eifel (mid-west of Germany) about 11,000 years ago at the Maar of Ulmen and 12,900 years ago at the Lake of Laach volcano (Schmincke 2010).…”

“…They appear as grabens and subgrabens (e.g. Lower Rhine, Upper Rhine, Eger, Bresse), activated during the late Eocene with more pronounced rifting starting in late Oligocene and filled with Cenozoic sediments (Ziegler 1994;Geluk et al 1994;Ziegler andDèzes 2006, 2007;Bourgeois et al 2007). Additionally, a system of horsts, blocks and tilted blocks was formed under a still present NW-directed compressional stress field, emerging in the early Miocene and accelerated in the Pliocene (Ziegler andDèzes 2006, 2007).…”

Folding and necking across the scales: a review of theoretical and experimental results and their applications

“…(35). Cloetingh and Burov (2011) compiled wavelengths of folded lithosphere, including crustal, mantle and whole lithosphere folding, for 17 regions worldwide, including Central Asia (Burov et al, 1993), central Australia (Lambeck, 1983b), the north-east European platform (Bourgeois et al, 2007), the Tibet/Himalayan syntaxes belt (Shin et al, 2015) and the Indian oceanic lithosphere (McAdoo and Sandwell, 1985;Krishna et al, 2001), and showed that all fold wavelengths are between 40 and 700 km. Not surprisingly, wavelengths for crustal folding are the smallest and wavelengths for whole lithosphere folding are the largest.…”

Exploration for deep geothermal reservoirs in Luxembourg and the surroundings - perspectives of geothermal energy use

“…If the preceeding assumptions are correct, the subsidence of the MSD and of the entire ED is entirely postLiassic, and probably largely Cenozoic, i.e., comparatively young, as are the structures studied by Dittrich (2014;and references therein). The current stratigraphical inclination of 0.8°may be entirely attributed to the Cenozoic uplift of the RM in the northeastern realm of the study area, also represented as a rift signature by Bourgeois et al (2007). Moreover, the inclination shown in Figure 5b and the subsidence shown in Figure 5a probably are contemporaneous Cenozoic processes.…”

“…On a larger scale, the RM and adjoining areas are deformed and uplifted due to the development and evolution of the ECRIS (represented by the Lower Rhine Graben (LRG) and the Upper Rhine Graben (URG) in Figure 1b) since the Eocene about 40 Ma ago (Bourgeois et al 2007;Demoulin and Hallot 2009;Fuchs et al 1983;Schmincke 2007;Dèzes et al 2004;Ziegler and Dèzes 2007;and references therein). Intensified tectonic activity in the last 700 ka is expressed by the accelerated uplift of the RM and young volcanism in the Eifel region (Demoulin and Hallot 2009;Fuchs et al 1983;Meyer and Stets 2002;Schmincke 2007).…”