Modélisation géométrique 3D des granites stéphaniens du massif du Pelvoux (Alpes, France)

Strzerzynski, Pierre; Guillot, Stéphane; Courrioux, Gabriel; Ledru, Patrick

doi:10.1016/j.crte.2005.06.008

Cited by 10 publications

(15 citation statements)

References 16 publications

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“…A third boundary between Devono-Dinantian and older basement rocks has also been traced between the outer and inner parts of the Oisans Massif. Le Fort and Ehstrom [1969] described this boundary as a major fault and recent structural investigations suggest that it is a Stephanian normal fault [Guillot et Ménot, 1999] with a sinistral component along an initial NW-SE direction [Strzerzynski et al, 2005]. The prolongation of this normal fault corresponds northwards to the conjugated GrandesRousses-Chatelard dextral-strike slip fault ( fig.…”

Section: Stephanian-permian Extension and Strike-slip Faulting (D5)mentioning

confidence: 96%

“…8d) and Grandes Rousses Massifs and a NNW-SSE ductile sinistral slip fault in the inner zone of the Oisans Massif in which granite emplaced [Strzerzynski et al, 2005]. The close association between strike-slip faulting and normal faulting along a lithospheric shear zone is very common as observed in the Tertiary Ailo Shan shear zone in Indochina [Leloup et al, 1995] In the Oisans Massif, the Devonian nappe pile is crosscut by the intrusion of Stephanian granites along a N160 o E sinistral ductile strike-slip fault [Strzerzynski et al, 2005]. A ductile normal fault outcrops on the western flank of the Oisans Massif where syn-migmatization extensional structures oriented N160 o E to N010 o E and dipping 50 o W are observed.…”

Section: Stephanian-permian Extension and Strike-slip Faulting (D5)mentioning

confidence: 98%

“…Some stocks display a monzogranitic and syenogranitic composition, but the most striking difference with the Mg-K granites is the absence of mafic enclaves. In the ECM, the Al-Fe magmatism is well defined in age, between 305 and 295 Ma [Debon and Lemmet, 1999], and all granites with high Al and Fe have been interpreted to be emplaced during the Stephanian transtension regime [Strzerzynski et al, 2005]. Granites are abundant in the Oisans Massif and associated with Upper Carboniferous Crd-bearing migmatites [Le Fort and Ehstrom, 1969].…”

Section: The Eastern Domainmentioning

confidence: 99%

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Suture zones and importance of strike-slip faulting for Variscan geodynamic reconstructions of the External Crystalline Massifs of the western Alps

Guillot

Paola²,

Ménot

et al. 2009

Bulletin De La Société Géologique De France

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International audienceThis paper reviews the geodynamic evolution of the Belledonne, Grandes Rousses and Oisans massifs in the western Alps from Early Ordovician to Permian times. Three domains are distinguished. The eastern domain, which includes the NE Belledonne massif and the inner Oisans massif, records the subduction of the Central-European ocean along a NW dipping subduction zone. The western domain is marked by Cambro-Ordovician back-arc rifting (Chamrousse ophiolite) initiating the opening of the Rheic ocean. It was followed by Mid-Devonian obduction of the back-arc Chamrousse ophiolite, towards the NW in relation with the SE dipping subduction of the Saxo-Thuringian ocean. The central domain, including the SW part of the Belledonne massif, the Grandes Rousses massif and the outer Oisans massif, records the Devonian to Carboniferous orogenic activity that produced calc-alkaline magmatism, Mg-K granite intrusions and syn-collisional sedimentation related to Visean nappe stacking that we relate to the closure of the Saxo-Thuringian ocean. Based on tectonostratigraphic correlations we propose that these domains initially correspond to the northeastward extension of the Bohemian massif. During the late Carboniferous, the External Crystalline Massifs including Sardinia and Corsica were stretched towards the SW along the > 600 km long dextral External Crystalline Massifs shear zone. Offset of the Saxo-Thuringian and eo-Variscan suture zones from the Bohemian massif to the ECM suggests a possible dextral displacement of about 300 km along the ECM shear zone

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Section: Stephanian-permian Extension and Strike-slip Faulting (D5)mentioning

confidence: 96%

Section: Stephanian-permian Extension and Strike-slip Faulting (D5)mentioning

confidence: 98%

Section: The Eastern Domainmentioning

confidence: 99%

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Suture zones and importance of strike-slip faulting for Variscan geodynamic reconstructions of the External Crystalline Massifs of the western Alps

Guillot

Paola²,

Ménot

et al. 2009

Bulletin De La Société Géologique De France

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“…26, TC2016, doi:10.1029/2006TC002022, 2007 Leloup et al, 2005, Figures 3b and 3h]. In the absence of radiometric data from the dikes, we assumed that as in many places in the External Crystalline Massifs, they are related with late stages of the granite emplacement and probably have an upper Stephanian age as it is the case in the Pelvoux [e.g., Strzerzynski et al, 2005]. This implies that the migmatitic gneisses are Variscan in age.…”

Section: Alpine Structures In the Mont Blanc Rangementioning

confidence: 96%

“…On the NW flank of the Mont Blanc, migmatitic gneisses are crosscut by the Mont Blanc granite and by aplitic veins, prior to having been affected by greenschist Alpine deformation [see Leloup et al , 2005, Figures 3b and 3h]. In the absence of radiometric data from the dikes, we assumed that as in many places in the External Crystalline Massifs, they are related with late stages of the granite emplacement and probably have an upper Stephanian age as it is the case in the Pelvoux [e.g., Strzerzynski et al , 2005]. This implies that the migmatitic gneisses are Variscan in age.…”

Section: Alpine Structures In the Mont Blanc Rangementioning

confidence: 99%

Reply to comment by Y. Rolland et al. on “Alpine thermal and structural evolution of the highest external crystalline massif: The Mont Blanc”

Leloup

Arnaud²,

Lacassin

et al. 2007

Tectonics

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Protracted magmatism and crust–mantle interaction during continental collision: insights from the Variscan granitoids of the external western Alps

Fréville,

Jacob,

Vanardois

et al. 2024

Int J Earth Sci (Geol Rundsch)

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Variscan granitoids and associated mafic rocks exposed in the External Crystalline Massifs (ECM) of the Western Alps document the Variscan stages from the early Carboniferous collision to the early Permian post-collisional setting. Our study focuses on the Central part of the ECM, synthesizing newly acquired and existing geochronological, whole-rock geochemical and isotopic data. We identified two distinctive magmatic series: (i) high-K calc-alkaline granitoids, which range from magnesian (MgG) to ferro-magnesian (FeMgG) rocks; (ii) ultra-high-K metaluminous (UHKM) rocks (“durbachites”). These series were emplaced roughly simultaneously between ca. 350 and 300 Ma, with two main episodes during the Visean (ca. 348–335 Ma) and the late Carboniferous (305–299 Ma), with a more limited activity in between. A younger Permian event at ca. 280–275 Ma has also been identified in one granitoid pluton. Contemporaneous emplacement of these two series reflects concomitant crustal anatexis and melting of LILE–LREE-rich metasomatized lithospheric mantle. Trace elements and Nd–Sr isotopes reveal significant hybridization between these two magmatic end members, by magma mixing, or assimilation of crystallized mafic ultrapotassic enclaves in the high-K calc-alkaline granitoids. Granitoid composition evolves over time, especially SiO2, Mg#, Sr/Y, La/Yb and Nb/Ta, possibly explained by increasing differentiation of magmas over time, changes in the crust versus mantle sources mass-balance, and decrease in melting pressure due to the orogenic collapse. The εNdi values of both high-K calc-alkaline granitoids and durbachites decreases from [− 3.8; − 2.9] to [− 6.4; − 5.2] between 345 and 320 Ma, possibly indicating an increasing influence of subducted/relaminated crustal material contaminating the lithospheric mantle source. εNdi values then rise to [− 3.7; − 0.5] during the late Carboniferous, possibly due to progressive exhaustion of the enriched mantle source, or advection of the asthenosphere during the post-collisional stage. Graphic abstract Possible geodynamic scenario along the central-eastern segment of the Variscan Belt, which may account for the temporal evolution of Variscan magmatism in the External Western Alps.

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Modélisation géométrique 3D des granites stéphaniens du massif du Pelvoux (Alpes, France)

Cited by 10 publications

References 16 publications

Suture zones and importance of strike-slip faulting for Variscan geodynamic reconstructions of the External Crystalline Massifs of the western Alps

Suture zones and importance of strike-slip faulting for Variscan geodynamic reconstructions of the External Crystalline Massifs of the western Alps

Reply to comment by Y. Rolland et al. on “Alpine thermal and structural evolution of the highest external crystalline massif: The Mont Blanc”

Protracted magmatism and crust–mantle interaction during continental collision: insights from the Variscan granitoids of the external western Alps

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