Necking of continental crust in magma‐poor rifted margins: Evidence from the fossil Alpine Tethys margins

Mohn, Geoffroy; Manatschal, Giänreto; Beltrando, Marco; Masini, Emmanuel; Kusznir, Nick

doi:10.1029/2011tc002961

Cited by 202 publications

(243 citation statements)

References 118 publications

Supporting

Mentioning

231

Contrasting

Unclassified

Order By: Relevance

“…In this area, a series of horsts and grabens and intense fluid-assisted brecciation and fracturing accompanied the serpentinisation of the peridotites were interpreted as low temperature deformation of the exhumed mantle, after the continental crust breakup and before the onset of true oceanic accretion . These late brittle deformations would correspond to the amplification stage in Figures 17d and e. Whereas mantle rocks have been largely sampled through drilling and diving it must be noted that without in situ sampling of the lower crust and mantle rocks along the West Iberia margin, the validation of the model of mantle exhumation at passive margins ( An interplay between faulting in the brittle layers and decoupling-thinning along localized ductile décollements in ductile middle crust is observed in the fossil Alpine Thetys margins (Mohn et al, 2012). However, the Ronda peridotites in the Western Betics in South Spain (Navarro-Vila and Tubía, 1983), the largest continental peridotites massif worldwide, is the only field example that, up to now, provides quantified information on the deformation mechanisms occurring in the strongly thinned crust part and mantle at margin tip (Frasca et al, 2016) (Fig.…”

Section: Accepted Manuscript 31mentioning

confidence: 99%

Crustal versus mantle core complexes

et al. 2018

View full text Add to dashboard Cite

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Contrary to what is commonly believed, it is argued from analogue and numerical models that detachments that accommodate exhumation of core complexes do not initiate at the onset of extension but in the course of progressive extension when the exhuming ductile crust reaches the surface. In models, convex upward detachments result from a rolling hinge process. A C C E P T E D M A N U S C R I P TMantle core complexes develop in either the oceanic lithosphere, at slow and ultra-slow spreading ridges, or in continental lithospheres, whose initial Moho temperature is lower than 750°C, with "sub-Moho mantle-dominated" strength profiles. It is argued that the mechanism of mantle exhumation at passive margins is a nearly symmetrical necking process at ACCEPTED MANUSCRIPTA C C E P T E D M A N U S C R I P T 2 lithosphere scale without major and permanent detachment, except if strong strain localization could occur in the lithosphere mantle. Distributed crustal extension, by upper crust faulting above a décollement along the ductile crust increases toward the rift axis up to crustal breakup.Mantle rocks exhume in the zone of crustal breakup accommodated by conjugate mantle shear zones that migrate with the rift axis, during increasing extension.

show abstract

Section: Accepted Manuscript 31mentioning

confidence: 99%

Crustal versus mantle core complexes

et al. 2018

View full text Add to dashboard Cite

show abstract

“…1; e.g. Froitzheim and Eberli, 1990;Masini et al, 2011 Mohn et al, 2012). This domain was followed to the west by the Adriatic hyper-extended domain, floored locally by exhumed crust and overlain by extensional allochthons, now sampled in the Lower Austroalpine nappes in the Eastern Swiss Alps [Err nappe (Froitzheim and Eberli, 1990;Manatschal and Nievergelt, 1997;Masini et al, 2011Masini et al, , 2013 and Bernina nappe ] and in the Canavese Zone in the Southern Alps (Ferrando et al, 2004).…”

Section: Jurassic Paleogeography Of the Alpine Tethysmentioning

confidence: 99%

“…Fossil hyper-extended crust and lithosphere characterized by extensional allochthons related to Jurassic rifting have also been extensively detected in sections of Alpine mountain belts that were only marginally affected by orogeny-related deformation and metamorphism (e.g. Froitzheim and Eberli, 1990;Florineth and Froitzheim, 1994;Molli, 1996;Durand-Delga et al, 1997;Manatschal, 2004;Masini et al, 2011;Mohn et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Recognizing remnants of magma-poor rifted margins in high-pressure orogenic belts: The Alpine case study

Beltrando

Manatschal

Mohn

et al. 2014

Earth-Science Reviews

122

104

View full text Add to dashboard Cite

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. Magma-poor rifted margins are being increasingly recognized in present-day Atlantic-type systems. However, findings of fossil areas floored by exhumed mantle or hyper-extended crust are comparatively rare within orogenic belts that were originated through the inversion of pre-existing rifted margins. This discrepancy may be due to the common reactivation of lithological contacts during subduction/orogeny, potentially masking pre-orogenic relationships, and, most importantly, to the frequent lack of a preorogenic layer-cake architecture, hindering retro-deformation of multiply deformed tectonic units. This study outlines a methodology to detect sections of magma-poor, hyper-extended rifted margins without a layer-cake architecture in multiply deformed/metamorphosed terrains. This approach is defined by comparison to well studied examples of fossil analogues preserved in weakly deformed parts of Alpine orogens. In the latter domains, continental basement and hydrated peridotites were exhumed at the basin floor during Jurassic rifting along long-offset detachment systems. Extensional geometries locally resulted in tectonic sampling of laterally discontinuous slivers of allochthonous continental basement and pre-rift sediments from the hanging wall blocks. Lithostratigraphic associations consisting of continental basement rocks directly juxtaposed with syn-to post-rift meta-sediments and/or serpentinized subcontinental mantle are widespread within sections of Alpine-type orogenic belts that underwent high-to ultra-high-pressure metamorphism. However, similar associations may arise from a variety of processes other than rift-related lithospheric thinning in magma-poor environments, including subduction mélange dynamics or deposition of sedimentary mélanges along convergent/divergent margins. The partial preservation of rift-related lithostratigraphic associations may still be assessed, despite the lack of biostratigraphic evidence, by (1) the consistency of the lithostratigraphic architecture over large areas, despite pervasive Alpine deformation, which rules out chaotic mixing during subduction/ exhumation, (2) the presence of clasts of basement rocks in the neighboring meta-sediments, indicating the original proximity of the different lithologies, (3) evidence of brittle deformation in continental basement and ultramafic rocks pre-dating Alpine metamorphism, indicating that they were juxtaposed by fault activity prior to the deposition of post-rift sediments, and (4) the similar Alpine tectono-metamorphic evolution of ophiolites, continental basement and meta-sediments. A re-assessment of basement-cover relationships in...

show abstract

“…tral Alps has been interpreted as an inherited character from the AdriaticEuropean divergent active margin during the Middle Triassic Period, which predates Jurassic rifting (Mohn et al, 2012). According to these authors, the Late Triassic-Early Jurassic stretching, thinning and necking that is related to the Alpine Tethys rifting would have resulted in ductile decoupling and exhumation of the upper portion of LCN (Campo Unit, Froitzheim et al, 1994) along detachment faults from middle crustal levels.…”

Section: Accepted Manuscriptmentioning

confidence: 99%