Quantification and restoration of extensional deformation along the Western Iberia and Newfoundland rifted margins

Sutra, Emilie; Manatschal, Giänreto; Mohn, Geoffroy; Unternehr, Patrick

doi:10.1002/ggge.20135

Cited by 197 publications

(299 citation statements)

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“…These necking domains separate the proximal domain from the hyperextended domains in which the continental crust is strongly thinned (e.g. Sutra et al, 2013). Recent studies on magma-poor margins indicate that the continental lithosphere can be significantly extended and necked over several hundreds of kilometres without a lithospheric breakup, which would result in the formation of new oceanic crust at a mid ocean ridge (Sutra et al, 2013).…”

Section: Lithospheric Neckingmentioning

confidence: 99%

“…Sutra et al, 2013). Recent studies on magma-poor margins indicate that the continental lithosphere can be significantly extended and necked over several hundreds of kilometres without a lithospheric breakup, which would result in the formation of new oceanic crust at a mid ocean ridge (Sutra et al, 2013). Assuming that pre-rift (initial) geometrical perturbations of crustal thickness have an amplitude (A 0 ) of the order of 100 m requires an amplification, A/A 0 , of 10 5 to thin an initially 30 km thick crust to 10 km.…”

Section: Lithospheric Neckingmentioning

confidence: 99%

“…Lithospheric necking is also important, for example, in the formation of rift basins ) and of magma-poor passive continental margins, because many of these margins are characterised by so-called necking domains in which the crustal thickness decreases from normal crustal thickness (30-35 km) to ca. 5-10 km (Sutra et al, 2013). Lithospheric necking can also generate a crustal-scale pinch-andswell structure (Fletcher and Hallet, 1983;Gueguen et al, 1997;Fig.…”

Section: Introductionmentioning

confidence: 99%

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

Schmalholz

Mancktelow

2016

Solid Earth

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Abstract. The shortening and extension of mechanically layered ductile rock generates folds and pinch-and-swell structures (also referred to as necks or continuous boudins), which result from mechanical instabilities termed folding and necking, respectively. Folding and necking are the preferred deformation modes in layered rock because the corresponding mechanical work involved is less than that associated with a homogeneous deformation. The effective viscosity of a layered rock decreases during folding and necking, even when all material parameters remain constant. This mechanical softening due to viscosity decrease is solely the result of fold and pinch-and-swell structure development and is hence termed structural softening (or geometric weakening). Folding and necking occur over the whole range of geological scales, from microscopic up to the size of lithospheric plates. Lithospheric folding and necking are evidence for significant deformation of continental plates, which contradicts the rigid-plate paradigm of plate tectonics. We review here some theoretical and experimental results on folding and necking, including the lithospheric scale, together with a short historical overview of research on folding and necking. We focus on theoretical studies and analytical solutions that provide the best insight into the fundamental parameters controlling folding and necking, although they invariably involve simplifications. To first order, the two essential parameters to quantify folding and necking are the dominant wavelength and the corresponding maximal amplification rate. This review also includes a short overview of experimental studies, a discussion of recent developments involving mainly numerical models, a presentation of some practical applications of theoretical results, and a summary of similarities and differences between folding and necking.

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Section: Lithospheric Neckingmentioning

confidence: 99%

Section: Lithospheric Neckingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Schmalholz

Mancktelow

2016

Solid Earth

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“…Understanding of this margin type is based on geophysical and drill core data from the conjugate margins of Iberia and Newfoundland, and studies of presumed analogues in the Alps (e.g. Boillot et al, 1987;Whitmarsh et al, 1996;Manatschal and Nievergelt, 1997; Tucholke et al, 2004;Sutra et al, 2013). Based on this work, the basement at these margins is dominated by mantle lithologies, from whose geochemically determined continental or oceanic affinities the COB can be interpreted.…”

Section: Definition and Demarcation Of The Cotz And Cobmentioning

confidence: 99%

Getting over continent ocean boundaries

Eagles

Pérez-Díaz

Scarselli

2015

Earth-Science Reviews

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The idea of a simple linear boundary between continental and oceanic crust at extended continental margins is widely recognised to be an oversimplification. Despite this, such boundaries continue to be mapped because of their perceived utility in palinspastic and plate kinematic reconstructions. To examine whether this perception is justified, we review the data and models on which basis continent ocean boundaries are interpreted, and map a set of such interpretations worldwide from more than 150 publications. The maps show that the location of the continent ocean boundary is rarely consistently estimated within the ~10-100 km observational uncertainty that might be expected of the geophysical data used for doing so, that this is the case regardless of whether the transition zone behind the boundary is classified as magma rich or magma poor, and that the geographical separation of estimates exceeds the width of single-study continent ocean transition zones. The average of global maximum separations across sets of three or more estimates is large (167 km) and mostly a consequence of interpretations published over the last decade. We interpret this to indicate an extra component of uncertainty that is related to authors' understanding of the range of features that are interpretable at extended continental margins. We go on to discuss the implications of this uncertainty for palinspastic and plate kinematic modelling using examples from the literature and from the South Atlantic ocean.We conclude that a precise continent ocean boundary concept with locational uncertainty defined from the ensembles is of limited value for palinspastic reconstructions because the reconstruction process tends to bunch the ensemble within a region that is (i) of similar width to the observational uncertainties associated with continent ocean boundary estimates, (ii) narrower than the regions of uncertainty about rotated features implied by the propagation of uncertainties from plate rotation parameters, and (iii) coincident, within all the above uncertainties, with the more-easily mapped continental shelf gravity anomaly.Secondly, we conclude that estimated continent ocean boundaries are of limited use in developing or testing plate kinematic reconstructions because (i) reconstructions built using them as markers do not, within uncertainty limits defined from the ensembles, differ greatly from those using more-easily determined bathymetric or gravity anomaly contours, and (ii) because it is impossible to segment and date them with useful precision to use as markers of the edges of rigid oceanic lithosphere outside of the constraints of a pre-existing plate kinematic model.

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“…Abbreviations: MTFC -Møre-Trøndelag Fault Complex; JMFZ -Jan Mayen Fracture Zone. Ranero & Pérez-Gussinyé, 2010;Sutra et al, 2013). Since the dredging of serpentinised mantle rocks at the Iberian margin (Boillot et al, 1980) and their subsequent drilling by several ODP Legs (Shipboard Scientific Party, 1987a, b, 1994, 2004, pertinent questions at deep margins relate to the degree of crustal thinning and to whether mantle was exhumed to the seafloor during large-magnitude extension (Whitmarsh et al, 2001;Manatschal et al, 2007;Péron-Pinvidic & Manatschal, 2009;Lundin & Doré, 2011;Péron-Pinvidic et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Extension, hyperextension and mantle exhumation offshore Norway: a discussion based on 6 crustal transects

Osmundsen¹,

Péron‐Pinvidic²,

Ebbing³

et al. 2017

NJG

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In spite of its classification as `magmatic´, the rifted margin off Mid Norway evolved as a hyperextended margin in Late Jurassic and Cretaceous time, with a pre-breakup structural evolution that resembles that of magma-poor margins. Because the distal margin was not drilled to crystalline basement, considerable uncertainty exists with respect to the distribution of lithologies at depth. In this contribution, we discuss the implications of various scenarios for deep-seated lithologies and evaluate the possibilities for mantle exhumation in the deep margin offshore Norway. A suite of JurassicCretaceous, very large-magnitude, extensional faults that exhumed successively deeper structural levels seawards are well imaged in recent long-offset seismic reflection data. Based on these key profiles, we document the structural configuration that created the extremely sharply tapered south Møre margin as well as subhorizontal detachment faults in the distal Vøring margin. The latter were associated with rotated extensional allochthon and supradetachment basins and contributed to the exhumation of very deep levels including rocks from the lower crust and/or upper mantle. In the outer margin, truncation and excision of this system by a new set of incising detachment faults occurred later in the Cretaceous and the earliest Cenozoic. We discuss the relationships between these detachment systems under the distal and outer margins and positive structural features such as the Rån and Gjallar ridges. The interpretation of basement lithologies at depth in the distal margin is ambiguous due to overlap in physical properties. Based on a process-oriented evaluation of the different interpretation scenarios, we favour a model where mantle windows were exhumed in the footwalls of some of the master faults in the Cretaceous.

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Quantification and restoration of extensional deformation along the Western Iberia and Newfoundland rifted margins

Cited by 197 publications

References 76 publications

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

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

Getting over continent ocean boundaries

Extension, hyperextension and mantle exhumation offshore Norway: a discussion based on 6 crustal transects

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