Plutons and domes: the consequences of anatectic magma extraction—example from the southeastern French Massif Central

Villaros, Arnaud; Laurent, Oscar; Couzinié, Simon; Moyen, Jean‐François; Mintrone, Michaël

doi:10.1007/s00531-018-1630-x

Cited by 34 publications

(33 citation statements)

References 116 publications

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“…In addition to the HP granulite facies migmatites that are part of the UGU, MP and LP migmatites, developed to the expense of late Neoproterozoic to early Paleozoic paragneisses and orthogneisses, are exposed at the lowest structural level of the nappe pile in the Limousin, Velay and Montagne Noire (Williamson et al, 1996;Downes et al, 1997;Ledru et al, 2001;Gébelin et al, 2009;Barbey et al, 2015;Villaros et al, 2018). In the Limousin, PT conditions of 850-750°C and 5-6 kbar have been estimated for the cordierite-bearing migmatitic gneisses and associated lenses of leucosomes of the Millevaches massif in the Limousin dated at c. 315 Ma (Gébelin et al, 2009).…”

Section: Migmatites and Granulitesmentioning

confidence: 99%

“…These migmatites contain monazite that yield microprobe U-Pb ages ranging from c. 329 to 314 Ma (Mougeot et al, 1997;Cocherie et al, 2005;Bé Mézémé et al, 2006). In contrast, migmatites coring the Velay dome have recorded fluid-absent biotite melting in the cordierite stability field with P-T estimates of 2-5 kbar and 760-850°C (Montel et al, 1992;Barbey et al, 1999Barbey et al, , 2015Villaros et al, 2018). These migmatites display a Rb-Sr whole rock age of 298 ± 8 Ma (Rb-Sr whole-rock, Caen-Vachette et al, 1981) and contain monazite dated at 301 ± 5 Ma by U-Pb (Mougeot et al, 1997).…”

Section: Migmatites and Granulitesmentioning

confidence: 99%

“…-Peraluminous granites and leucogranites correspond to muscovite or muscovite þ biotite bearing granites sensustricto equivalent to the muscovite-bearing peraluminous granitoids (MPG) of Barbarin (1999). They are attributed to relatively cold (< 850°C, water present-or muscovite breakdown) melting of metasediments (Gardien et al, 1995;Villaros et al, 2018) and might represent the first melt extracted from the partially molten source at the onset of partial melting. -Peraluminous granites to granodiorites, corresponding to the cordierite-bearing peraluminous granitoids (CPG) of Table 3.…”

Section: Late Devonian To Carboniferous Plutonic Rocksmentioning

confidence: 99%

“…Barbarin (1999). They probably relate to relatively hot (≥ 850°C, biotite breakdown) melting of a continental felsic source (ortho or paragneisses) (Gardien et al, 1995;Barbey et al, 1999;Villaros et al, 2018). They might represent a partially molten source with a high-melt fraction (i.e.…”

Section: Late Devonian To Carboniferous Plutonic Rocksmentioning

confidence: 99%

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Flow of partially molten crust controlling construction, growth and collapse of the Variscan orogenic belt: the geologic record of the French Massif Central

Vanderhaeghe

Laurent

Gardien

et al. 2020

BSGF - Earth Sci. Bull.

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We present here a tectonic-geodynamic model for the generation and flow of partially molten rocks and magmatism during the Variscan orogenic evolution from the Silurian to the late Carboniferous based on a synthesis of geological data from the French Massif Central. Eclogite facies metamorphism of mafic and ultramafic rocks records the subduction of the Gondwana hyperextended margin. Part of these eclogites are forming boudins-enclaves in felsic HP granulite facies migmatites partly retrogressed into amphibolite facies attesting for continental subduction followed by thermal relaxation and decompression. We propose that HP partial melting has triggered mechanical decoupling of the partially molten continental rocks from the subducting slab. This would have allowed buoyancy-driven exhumation and entrainment of pieces of oceanic lithosphere and subcontinental mantle. Geochronological data of the eclogite-bearing HP migmatites points to diachronous emplacement of distinct nappes from middle to late Devonian. These nappes were thrusted onto metapelites and orthogneisses affected by MP/MT greenschist to amphibolite facies metamorphism reaching partial melting attributed to the late Devonian to early Carboniferous thickening of the crust. The emplacement of laccoliths rooted into strike-slip transcurrent shear zones capped by low-angle detachments from c. 345 to c. 310 Ma is concomitant with the southward propagation of the Variscan deformation front marked by deposition of clastic sediments in foreland basins. These features reflect the horizontal growth of the Variscan belt and the formation of an orogenic plateau by gravity-driven lateral flow of the partially molten orogenic root. The diversity of the magmatic rocks points to various crustal sources with modest, but systematic mantle-derived input. In the eastern French Massif Central, the southward decrease in age of the mantle- and crustal-derived plutonic rocks from c. 345 Ma to c. 310 Ma suggests southward retreat of a northward subducting slab toward the Paleothethys free boundary. Late Carboniferous destruction of the Variscan belt is dominantly achieved by gravitational collapse accommodated by the activation of low-angle detachments and the exhumation-crystallization of the partially molten orogenic root forming crustal-scale LP migmatite domes from c. 305 Ma to c. 295 Ma, coeval with orogen-parallel flow in the external zone. Laccoliths emplaced along low-angle detachments and intrusive dykes with sharp contacts correspond to the segregation of the last melt fraction leaving behind a thick accumulation of refractory LP felsic and mafic granulites in the lower crust. This model points to the primordial role of partial melting and magmatism in the tectonic-geodynamic evolution of the Variscan orogenic belt. In particular, partial melting and magma transfer (i) triggers mechanical decoupling of subducted units from the downgoing slab and their syn-orogenic exhumation; (ii) the development of an orogenic plateau by lateral flow of the low-viscosity partially molten crust; and, (iii) the formation of metamorphic core complexes and domes that correspond to post-orogenic exhumation during gravitational collapse. All these processes contribute to differentiation and stabilisation of the orogenic crust.

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Section: Migmatites and Granulitesmentioning

confidence: 99%

Section: Migmatites and Granulitesmentioning

confidence: 99%

Section: Late Devonian To Carboniferous Plutonic Rocksmentioning

confidence: 99%

Section: Late Devonian To Carboniferous Plutonic Rocksmentioning

confidence: 99%

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Flow of partially molten crust controlling construction, growth and collapse of the Variscan orogenic belt: the geologic record of the French Massif Central

Vanderhaeghe

Laurent

Gardien

et al. 2020

BSGF - Earth Sci. Bull.

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“…The geotectonic links span from the empirical observation that some tectonic sites are more likely to put the right rocks in the right place. For instance, a collisional orogeny (with considerable crustal thickening) or accretionary orogeny (especially back-arc domains with considerable crustal thinning) are, the most likely places to induce melting of metasediments (Collins 2002;Collins & Richards 2008;Villaros et al 2018;Collins et al 2019;Nabelek 2019). Thus, a geodynamic interpretation implicitly relies on two successive layers of reasoning: (i) linking a type of granite to its plausible source (and melting conditions), and (ii) linking this source and melting conditions to a geodynamic site in which they were both most likely to occur.…”

Section: Diagrams Plotting Experimental Melting Datamentioning

confidence: 99%

Chemical variation, modal composition and classification of granitoids

Bonin

Janoušek

Moyen

2020

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The manuscript will undergo copyediting, typesetting and correction 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 book series pertain. Although reasonable efforts have been made to obtain all necessary permissions from third parties to include their copyrighted content within this article, their full citation and copyright line may not be present in this Accepted Manuscript version. Before using any content from this article, please refer to the Version of Record once published for full citation and copyright details, as permissions may be required.

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Late‐Orogenic Structural Reorganization of the Variscan Belt during the Upper Carboniferous

DENÈLE,

COCHELIN

2023

The Variscan Belt of Western Europe 2

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Plutons and domes: the consequences of anatectic magma extraction—example from the southeastern French Massif Central

Cited by 34 publications

References 116 publications

Flow of partially molten crust controlling construction, growth and collapse of the Variscan orogenic belt: the geologic record of the French Massif Central

Flow of partially molten crust controlling construction, growth and collapse of the Variscan orogenic belt: the geologic record of the French Massif Central

Chemical variation, modal composition and classification of granitoids

Late‐Orogenic Structural Reorganization of the Variscan Belt during the Upper Carboniferous

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