Recumbent folds: Key structural elements in orogenic belts

Bastida, Fernando; Aller, J.; Fernández, F.J.; Lisle, Richard J.; Bobillo‐Ares, Nilo C.; Menéndez, Omar

doi:10.1016/j.earscirev.2014.05.002

Cited by 30 publications

(10 citation statements)

References 102 publications

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“…8, in which the attitudes of the axial planes of folds originated in layers with initial dip direction of 30°and several dips are plotted. For higher values of the dip direction, the formation of recumbent folds is more difficult (Bastida et al, 2014). The axial planes pass through a stage of low dip that in some cases would give rise to recumbent folds.…”

Section: Forward Modeling: Case Of Recumbent Foldsmentioning

confidence: 99%

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StrainModeler: A Mathematica™-based program for 3D analysis of finite and progressive strain

Bobillo‐Ares

Aller

Bastida

et al. 2015

Computers & Geosciences

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Section: Forward Modeling: Case Of Recumbent Foldsmentioning

confidence: 99%

“…Simple shear and coaxial strain seem to be the most important types of whole-rock strain involved in the development of these folds (Bastida et al, 2014).…”

Section: Forward Modeling: Case Of Recumbent Foldsmentioning

confidence: 99%

StrainModeler: A Mathematica™-based program for 3D analysis of finite and progressive strain

Bobillo‐Ares

Aller

Bastida

et al. 2015

Computers & Geosciences

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“…There are several major differences that Figure 14. Comparison between finite strain from the Morcles nappe (taken from Bastida et al, 2014 showing a recoloured version of the synthetic cross section with strain ellipses from pressure shadows after Casey and Dietrich, 1997, including green strain ellipses from Ramsay and Huber, 1987, the cross section is modified from Dietrich and Casey, 1989) and selected finite strain ellipses from model A.G-1 and model D.G-1.…”

Section: Comparison With the Helvetic Nappe Systemmentioning

confidence: 99%

Control of 3-D tectonic inheritance on fold-and-thrust belts: insights from 3-D numerical models and application to the Helvetic nappe system

et al. 2020

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Abstract. We apply three-dimensional (3-D) thermo-mechanical numerical simulations of the shortening of the upper crustal region of a passive margin in order to investigate the control of 3-D laterally variable inherited structures on fold-and-thrust belt evolution and associated nappe formation. We consider tectonic inheritance by employing an initial model configuration with basement horst and graben structures having laterally variable geometry and with sedimentary layers having different mechanical strength. We use a visco-plastic rheology with a temperature-dependent flow law and a Drucker–Prager yield criterion. The models show the folding, detachment (shearing off) and horizontal transport of sedimentary units, which resemble structures of fold and thrust nappes. The models further show the stacking of nappes. The detachment of nappe-like structures is controlled by the initial basement and sedimentary layer geometry. Significant horizontal transport is facilitated by weak sedimentary units below these nappes. The initial half-graben geometry has a strong impact on the basement and sediment deformation. Generally, deeper half-grabens generate thicker nappes and stronger deformation of the neighbouring horst, while shallower half-grabens generate thinner nappes and less deformation in the horst. Horizontally continuous strong sediment layers, which are not restricted to initial graben structures, cause detachment (décollement) folding and not overthrusting. The amplitude of the detachment folds is controlled by the underlying graben geometry. A mechanically weaker basement favours the formation of fold nappes, while stronger basement favours thrust sheets. The model configuration is motivated by applying the 3-D model to the Helvetic nappe system of the Central Alps of France and Switzerland. Our model reproduces several first-order features of this nappe system, namely (1) closure of a half-graben and associated formation of the Morcles and Doldenhorn nappes, (2) overthrusting of a nappe resembling the Wildhorn and Glarus nappes, and (3) formation of a nappe pile resembling the Helvetic nappes resting above the Infrahelvetic complex. Furthermore, the finite strain pattern, temperature distribution and timing of the 3-D model is in broad agreement with data from the Helvetic nappe system. Our model, hence, provides a 3-D reconstruction of the first-order tectonic evolution of the Helvetic nappe system. Moreover, we do not apply any strain softening mechanisms. Strain localization, folding and nappe transport are controlled by initial geometrical and mechanical heterogeneities showing the fundamental importance of tectonic inheritance on fold-and-thrust belt evolution.

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“…Their identification depends upon the preservation of structural elements that are considered characteristic of nappes (e.g. Ramsay 1981;Bastida et al 2014). These include (but are not limited to) synformal anticlines and antiformal synclines along the overturned lower limb of a nappe, as well as asymmetric, mesoscopic-scale, parasitic folds that verge in the opposite direction of nappe emplacement and are characterised by thinned upper and lower limbs that connect through a steeply-dipping and structurally thickened short limb.…”

Section: Introductionmentioning

confidence: 99%

The south-verging Isortoq Nappe of Baffin Island, Canada: implications on the framework of the northeastern Trans-Hudson Orogen

Saumur¹,

Johnston²,

Skipton³

et al. 2022

Preprint

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The Isortoq Shear Zone (ISZ), a 100km-scale structure in northern Baffin Island, was originally identified through the interpretation of regional geophysical surveys. In the field the ISZ is cryptic, and its significance ambiguous with respect to the regional structural framework of northern Baffin Island. Mapping along the ISZ and within the spatially associated Archean Isortoq and Eqe Bay greenstone belts shows that the two belts form one continuous folded supracrustal package deformed by nappe tectonics likely during the early Paleoproterozoic Trans-Hudson Orogeny. The northern NE-striking, moderately SE-dipping Isortoq belt is structurally thinned, metamorphosed, sheared (by the ISZ) and overturned, with strata younging down-section to the NW. In contrast, the southern NE-striking, steeply dipping Eqe Bay belt is structurally thickened, comparatively less metamorphosed, exhibits weaker deformation, and stratigraphically youngs to the SE. New mapping and available geophysical data show that the two belts are folded around a hinge zone located offshore to the SW, and together form an asymmetric synformal anticline. Structural and stratigraphic relationships are consistent with the fold forming part of the lower limb of a map-scale southeast-verging nappe, with the ISZ formed at the base of this nappe as a consequence of horizontal transport. The Isortoq Nappe occurs along strike with SW-verging Rinkian nappes exposed >200 km to the NE, on Baffin Island and in Greenland. This implies that south-verging tectonics during the THO, opposed to and predating the dominant N-verging nappes of the Foxe Fold Belt, are more important in spatial extent than previously considered.

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Recumbent folds: Key structural elements in orogenic belts

Cited by 30 publications

References 102 publications

StrainModeler: A Mathematica™-based program for 3D analysis of finite and progressive strain

StrainModeler: A Mathematica™-based program for 3D analysis of finite and progressive strain

Control of 3-D tectonic inheritance on fold-and-thrust belts: insights from 3-D numerical models and application to the Helvetic nappe system

The south-verging Isortoq Nappe of Baffin Island, Canada: implications on the framework of the northeastern Trans-Hudson Orogen

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