The eastern Jura: Relations between thin-skinned and basement tectonics, local and regional

Laubscher, H. P.

doi:10.1007/bf01820630

Cited by 81 publications

(67 citation statements)

References 6 publications

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“…the most likely and plausible relationship was formulated by Laubscher (1985) who speculated about the role of a disrupted basal triassic décolle-ment level as a 'nucleation line' that triggered the ramping up of the basal Jura thrust, thus leading to the formation of ramp anticlines within the 'thin skinned' cover (Fig. 10).…”

Section: Alps External Zone: Ae_1 To Ae_13 Zonesmentioning

confidence: 99%

Seismic source zone characterization for the seismic hazard assessment project PEGASOS by the Expert Group 2 (EG1b)

Burkhard

Grünthal

2009

Swiss J. Geosci.

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A comprehensive study of the seismic hazard related to the four NNP sites in NW switzerland was performed within the project PEGAsOs. to account for the epistemic uncertainties involved in the process of the characterization of seismic source zones in the frame of probabilistic seismic hazard assessments, four different expert teams have developed and defended their models in the frame of an intensive elicitation process.Here, the results of one out of four expert groups are presented. the model of this team is based first of all on considerations regarding the large scale tectonics in the context of the Alpine collision, and neotectonic constraints for defining seismic source zones. this leads to a large scale subdivision based on the structural 'architectural' considerations with little input from the present seismicity. Each of the eight large zones was characterized by the style of present-day faulting, fault orientation, and hypocentral depth distribution. A further subdivision of the larger zones is performed based on information provided by the seismicity patterns. 58 small source zones have been defined in this way, each of them characterized by the available tectonic constrains, as well as the pros and cons of different existing geologic views connected to them. Of special concern in this respect were the discussion regarding thin skinned vs. thick skinned tectonics, the tectonic origin of the 1356 basel earthquake, the role of the Permo-carboniferous graben structures, and finally the seismogenic orientation of faults with respect to the recent crustal stress field. the uncertainties connected to the delimitations of the small source zones have been handled in form of their regrouping, formalized by the logic tree technique.the maximum magnitudes were estimated as discretized probability distribution functions. After declustering the used EcOs earthquake catalogue and an analysis of data completeness as a function of time the parameters of the frequency-magnitude relations were derived within their uncertainties. Introductionthe sites of the four nuclear power plants (NPP) in NW switzerland have been subject to a comprehensive analysis of seismic hazard evaluated in the frame of the PEGAsOs project (Abrahamson et al. 2004; coppersmith et al., this volume). the definition of seismic source zones (ssZ) and the derivation of the parameters characterizing the seismic activity in each ssZ are integral parts of any probabilistic seismic hazard assessment. Here we present the results of one of the four expert groups (EG1b) responsible for the delineation of ssZ and determining the seismic activity parameters in the source zones.the study area was set up as the envelope of the radii of 300 km around all sites studied. this guarantees that the study area encompasses all seismic sources which have a seismic influence on the target sites. It extends well beyond the territory of switzerland, covering the southwestern parts of Germany, the western parts of Austria, the adjacent parts of northern Italy and n...

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Section: Alps External Zone: Ae_1 To Ae_13 Zonesmentioning

confidence: 99%

Seismic source zone characterization for the seismic hazard assessment project PEGASOS by the Expert Group 2 (EG1b)

Burkhard

Grünthal

2009

Swiss J. Geosci.

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“…1), located about 70 km east of our working area, but exactly along-strike above the eastern continuation of the Permo-Carboniferous trough, thick-skinned compressive neotectonic reactivation should at least not be ruled out. According to most authors (Müller et al 1984;Laubscher 1986;Sprecher & Müller 1986;Diebold et al 1991;Naef et al 1995), the Mandach structure has initiated as an extensional flexure above the northern border fault of the Permo-Carboniferous trough, which later led to the nucleation of a thin-skinned, N-vergent thrust fault, concomitant with the formation of the Folded Jura further S. Haldimann et al (1984) identified an ENE-trending ridge of easily erodible Aalenian clays underneath Pleistocene gravels along the Aare river in the eastern along-strike prolongation of the Mandach thrust. Haldimann (1987) treated the existence of this ridge as evidence for late Pleistocene uplift of the southern hangingwall along the Mandach thrust.…”

Section: Kinematic Framework Of Neotectonic Activity In the Southern Urgmentioning

confidence: 99%

Latest Pliocene to recent thick-skinned tectonics at the Upper Rhine Graben – Jura Mountains junction

2007

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The southernmost Upper Rhine Graben and adjacent Jura experienced basement-rooted shortening that occurred after the deposition of the Pliocene fluvial "Sundgau gravels". Folds affecting the base of these gravels systematically trend NE to ENE. Combined evidence from reflection seismic lines and contour maps of the base-Tertiary and base-Pliocene levels indicates that these folds probably formed by thick-skinned reactivation of both NNE-SSW and WSW-ENE-striking faults. This thick-skinned shortening is NW-SE oriented, i.e. parallel to the maximum horizontal stresses inferred from seismotectonics. NNE-SSW-striking faults (paralleling the Upper Rhine Graben) have been reactivated in sinistral strike-slip mode. However, dextrally transpressive reactivation of the WSW-ENE-trending faults that belong to the Rhine-Bresse Transfer Zone is interpreted to predominate.Deflections of recent river courses around the crests of en-échelon-aligned surface anticlines suggest that the deformation is ongoing at present.Retro-deformation of the folds affecting the base of the Sundgau gravels indicates horizontal displacement rates of about 0.05 mm/a. This corresponds to a minimum strain rate in the order of 2·10 -16 s -1 , given the maximum time span of 2.9 Ma for this deformation, i.e. the biostratigraphically determined minimum age of the gravels. A change from thin-skinned tectonics, that prevailed during the main phase of Jura folding, to very probably still ongoing thick-skinned tectonics is inferred to have occurred in the Late Pliocene. We speculate that this change might be linked to the incipient inversion of Permo-Carboniferous troughs within the Alpine foreland in general. This inversion in dextrally transpressive or purely compressive mode along a WNW-ESE-trending basement fault, that is part of the Rhine-Bresse Transfer Zone, which in turn was prestructured during the formation of the Permo-Carboniferous troughs, could have triggered the 1356 Basel earthquake.

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“…They are referred to as faulted flexures (Laubscher, 1986) and result from the deep reactivation of average WNW -ESE striking faults bordering the underlying Paleozoic trough which induced offsets or flexures of the Triassic décollement levels. These deep normal faults are thought to extent westward along the Jura northern front.…”

Section: Cover and Basement Deformation During The Paleogenementioning

confidence: 99%

“…8D). However, stress concentrations and stress permutations occurred near pre-existing fault-related offsets, flexures and pinch outs of the décollement levels (Laubscher, 1986;Philippe et al, 1996), as well as near the inherited cover discontinuities where thrusts nucleated and folding concentrated. The structural style of the external Jura varies according to the initial conditions (Fig.…”

Section: Late Miocene Fold-and-thrust Tectonics and The Role Of Strucmentioning

confidence: 99%

“…Deformation was active from about 10 to 5 Ma ago and is referred to as the ''Jura Phase'' or the Late Miocene tectonics (for a review, see Burkhard, 1990;Laubscher, 1992). Early deformation in the Jura Mountains has been locally identified (e.g., Mathis, 1974;Laubscher, 1972Laubscher, , 1986Chauve et al, 1988), but the detailed fracture pattern and corresponding stress fields have not been considered for the whole Jura Mountains. In addition, origin of pre-orogenic deformation in the Jura and in neighboring areas is controversial (Sopena and Soulas, 1973;Illies, 1975;Buchner, 1981;Bergerat and Geyssant, 1987;Homberg et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

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Structural inheritance and cenozoic stress fields in the Jura fold-and-thrust belt (France)

et al. 2002

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Based on an analysis of 8000 minor fault-slip data in the Jura Mountains (France), we discuss the influence of pre-existing discontinuities on the development of fold-and-thrust belts. We present palinspastic maps showing the stress fields and active faults during the Cenozoic pre-orogenic events in the Jura belt prior to the main Late Miocene fold-and-thrust tectonics. During the Eocene, a N -S strike-slip regime produced a few NNE -SSW sub-vertical strike-slip faults in the central external Jura and a few E -W reverse faults in the eastern Jura near the future frontal thrust. During the Oligocene, an average WNW -ESE extension, with irregular stress trajectories, resulted in normal faulting along N -S to NE -SW trends in the external part of the belt, WNW -ESE trends along the future northern and northeastern frontal thrust, and NW -SE trends in the internal Jura. The Late Miocene tectonics began with a strike-slip regime with a fan-shaped compressional trajectory. It was followed by a stress field with similar stress direction, but local r 2 /r 3 stress permutation resulted in strike-slip regime domains contrasting with reverse regime domains. Stress deflections and permutations occurred near inherited cover and basement discontinuities. Major deformation zones, like the Jura frontal thrust onto the foreland, the thrust of the internal central Jura onto the external Jura, and the narrow deformation bands within the flat-lying plateaus formed close to the inherited faults. The structural style of the Jura belt thus partly mimics the pre-orogenic fault pattern. Stress deflections point to the pre-orogenic faults, express the indentation process of the Jura by its hinterland, and highlight successive slip events along major faults during the fold-and-thrust tectonics. This case study illustrates the relevance of minor fault-slip studies for characterizing both the pre-orogenic tectonics and the kinematics of the deformation. D

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The eastern Jura: Relations between thin-skinned and basement tectonics, local and regional

Cited by 81 publications

References 6 publications

Seismic source zone characterization for the seismic hazard assessment project PEGASOS by the Expert Group 2 (EG1b)

Seismic source zone characterization for the seismic hazard assessment project PEGASOS by the Expert Group 2 (EG1b)

Latest Pliocene to recent thick-skinned tectonics at the Upper Rhine Graben – Jura Mountains junction

Structural inheritance and cenozoic stress fields in the Jura fold-and-thrust belt (France)

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