Neue Ergebnisse zur Tektonik der Allgäuer und Vilser Alpen

Müller-Wolfskeil, Peter; Zacher, Wolfgang

doi:10.1007/bf01820373

Cited by 3 publications

(2 citation statements)

References 1 publication

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“…Although the Lechtal thrust of the study area is exclusively S-dipping (Fig. 2), it is regionally folded after thrusting, as documented by Müller-Wolfskeil and Zacher (1984).…”

Section: Lechtal Thrustmentioning

confidence: 76%

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Deformation around a detached half-graben shoulder during nappe stacking (Northern Calcareous Alps, Austria)

2018

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This study describes the inversion of a rift-related graben shoulder during emplacement and transport of a major thrust sheet in the external part of the western Northern Calcareous Alps (NCA). Structural fieldwork was carried out along the Lechtal thrust, separating the tectonically deeper Allgäu thrust sheet from the Lechtal thrust sheet. An irregularly shaped Early Jurassic normal fault and an adjacent basin are present in the immediate footwall of the Lechtal thrust. The Early Jurassic age of the basin formation is indirectly established by thickness differences in the syntectonic deposits. Scaly fabric and small-scale drag folds document top S to top SW kinematics at the normal fault. During Alpine orogeny the Lechtal thrust is forced to recess around the graben shoulder in the footwall. A transpressive, dextral tear-fault develops in the hanging wall to compensate for lateral differences of shortening. The normal fault is too steep for inversion, and a shortcut thrust across the half-graben shoulder developed at a shallower angle. It transports the detached half-graben shoulder into the neighbouring basin. Albian to Paleogene transport of the Lechtal thrust sheet caused deformation below the Lechtal thrust, creating a shear zone with isoclinal folds, break thrusts, boudinaged beds and development of S-C fabric. Kinematic analyses of S-C fabrics and small-scale fold axes along the Lechtal thrust show consistent top NW to top N shortening directions in accordance with Cretaceous to Paleogene thrust directions in the NCA. Keywords Jurassic normal faulting Á Basin inversion Á Thrust tectonics Á Northern Calcareous Alps Editorial handling: K. Saric.

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“…Although the Lechtal thrust of the study area is exclusively S-dipping (Fig. 2), it is regionally folded after thrusting, as documented by Müller-Wolfskeil and Zacher (1984).…”

Section: Lechtal Thrustmentioning

confidence: 76%

“…The thrust of the southern slice runs into an anticline to the W (Fig. 2) previously described by Müller-Wolfskeil and Zacher (1984). Both domains are overprinted by a NE striking, sinistral transtensive fault system (coloured yellow in Fig.…”

Section: Structural Overviewmentioning

confidence: 84%

Deformation around a detached half-graben shoulder during nappe stacking (Northern Calcareous Alps, Austria)

2018

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Über die Beziehungen des „Cenomans“ zur Gosau in den Nördlichen Kalkalpen und ihre Auswirkungen auf die paläogeographischen und tektonischen Vorstellungen

Weidich¹

1984

Geol Rundsch

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Determination of a normal orogenic palaeo-geothermal gradient with clay mineral and organic matter indices: a review

Ferreiro Mählmann,

Rahn,

Potel

et al. 2024

Swiss J Geosci

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A collection of large data sets from different orogenic belts was compiled for a correlation between organic matter (OM) versus clay mineral (CM) indices calibrated with the vitrinite reflectance, (VR) vs Kübler-Indices (KI) method. Data selection was based on a normal geothermal gradient (25 to 35 °C/km) as determined in previous studies, e.g. by maturity modelling and clay mineral reaction progress calculations. In the Lower Austroalpine (Eastern Switzerland, European Alps) a 20 myr lasting metamorphic overprint caused an OM–CM thermal equilibrium among the indices used. The observed correlation enables to determine gradual changes in metamorphic factors such as pressure, temperature and time causing sensitive shifts of the gradient slope in the range of normal gradients. For New Caledonia, an identical correlation has been determined. Prior to re-equilibration of the VR/KI indices, sediments in New Caledonia of diagenetic to incipient metamorphic grade underwent a high-pressure subduction event. VR/KI indices are in or close to equilibrium, while slight differences in OM vs CM indices allow for a better understanding of polyphase conditions, especially with respect to pressure. Temperature estimations are identical despite of their poly-phase metamorphic history, which was mainly controlled by the last orogenic thermal event lasting > 5 to < 10 myr. In the eastern Helvetic Alps and Northern Calcareous Alps similar correlations were found with slightly different slopes. Comparison between different regions is possible when using KI standardization and same data discrimination. In both parts of the Alps a complex thermal history of short durations (< 5.0 myr for the Northern Calcareous Alps to 10 myr for the Helvetic Alps) caused similar VR/KI trends, but disequilibrium is suggested by weaker regression parameters. The following correlation is calculated for a moderate geotherm (55 to 74 mWm2, mean = 61 mWm2) and normal temperature gradient conditions (25 to 35 °Ckm−1): KI = 1.134e−0.305VR, (R2 = 0.880, n = 462) with VR given as %Rmax, KI as Δ°2θ (limited to values between 0.2 to 1.0 Δ°2θ). With increasing depth (z) a VR gradient of 1.4 ± 0.2%Rmaxkm−1 is determined and a KI gradient of 0.09 ± 0.002 Δ°2θ km−1 is observed. The study illustrates that a normal geotherm can be described by VR/KI correlation, even if different heating episodes may occur. For the detection of a poly-phase or plurifacial thermal history, several indices of clay minerals and organic matter with very different kinetics should be used, as e.g. demonstrated by strong differences in smectite content at equal VR/KI values versus structural depth. A specific interest is given to the correlation of vitrinite like solid bitumen reflectance as an alternative method to VR, the persistent preservation of liptinite macerals and the stability range of clay minerals and sub-greenschist facies critical minerals compared with VR/KI data. Until now, despite the Alps in this study, systematic liptinite maceral studies have not been published in other orogenic settings.

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Neue Ergebnisse zur Tektonik der Allgäuer und Vilser Alpen

Cited by 3 publications

References 1 publication

Deformation around a detached half-graben shoulder during nappe stacking (Northern Calcareous Alps, Austria)

Deformation around a detached half-graben shoulder during nappe stacking (Northern Calcareous Alps, Austria)

Über die Beziehungen des „Cenomans“ zur Gosau in den Nördlichen Kalkalpen und ihre Auswirkungen auf die paläogeographischen und tektonischen Vorstellungen

Determination of a normal orogenic palaeo-geothermal gradient with clay mineral and organic matter indices: a review

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