Post-collisional Potassic–Ultrapotassic Magmatism of the Variscan Orogen: Implications for Mantle Metasomatism during Continental Subduction

Soder, Christian; Romer, Rolf L.

doi:10.1093/petrology/egy053

Cited by 86 publications

(54 citation statements)

References 132 publications

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“…The RSF syn-kinematic granite band, referred to as Granite des Crêtes and emplaced at ca 337 Ma (Tabaud et al, 2015), offsets sinistrally the Central Vosges granitegneiss and migmatites-granulite and bounds the fossiliferous volcano-sedimentary units of the Southern Vosges intruded by the Ballons granite complex. It is worth noting that numerous lamprophyre dykes are present across the Central and Southern Vosges units (Soder and Romer, 2018), very likely associated to the vaugnerite intrusions and the ultra-potassic Crêtes and Ballons granitoid complexes. Age data are lacking to provide a precise view of the dynamics of this major late-orogenic ultra-potassic magmatic event.…”

Section: Outcrop-scale Observations and Samplingmentioning

confidence: 99%

“…Crêtes granite, Ballons granite, Visean volcanites: data from Tabaud et al (2015) and André (1983). Vosges lamprophyres are 57 analyses from Soder and Romer (2018). Small circles: Crêtes Mg-K granites (18 anal.…”

Section: Zircon Chemistry and Thermometry 441 Zircon Th And Umentioning

confidence: 99%

“…The involvement of the mantle in this late orogenic event has been proposed, in particular, through the existence within the anatectic granitic suites of peculiar ultra-potassic mafic magmatic rocks: vaugnerite-durbachite and lamprophyre-type rocks (e.g. Gerdes et al, 2000;Bonin, 2004;Janousek and Holub, 2007;von Raumer et al, 2013;Couzinié et al, 2016;Soder and Romer, 2018;Janousek, 2019). These specific rocks, also referred to in the recent literature as Mg-K (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…1) i.e. the French Massif Central (Sabatier, 1980;Montel and Weisbrod, 1986;Michon, 1987;Barbey et al, 2015;Solgadi et al, 2007;Couzinié et al, 2014;Laurent et al, 2017), the Armorican and Cornwall massifs (Exley et al, 1983;Le Gall et al, 1989;Dupuis et al, 2015), the Vosges-Black Forest-Saxothuringian massifs (Gagny, 1978;André, 1981;Hegner et al, 1998;von Seckendorff et al, 2004b;Tabaud et al, 2014;Tabaud et al, 2015;Soder and Romer, 2018), the Bohemian massif (Holub, 1997;Gerdes et al, 2000;Seifert, 2008;Zeitlhofer et al, 2016;Kubínová et al, 2017), the External Crystalline massifs of the Western Alps and Corsica (Banzet, 1987;Bussy et al, 1998;Bonin et al, 1998;Debon et al, 1998;Rossi et al, 2009) and some Variscan massifs from Spain (Scarrow et al, 2008(Scarrow et al, , 2011.…”

Section: Introductionmentioning

confidence: 99%

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Zircon age of vaugnerite intrusives from the Central and Southern Vosges crystalline massif (E France): contribution to the geodynamics of the European Variscan belt

Guillot

Averbuch

Dubois

et al. 2020

BSGF - Earth Sci. Bull.

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To provide a better definition of the geodynamical processes active at the Variscan suture zones during the late collisional stage (particularly regarding the evolution of the orogenic system towards HT conditions), we focused here on specific mafic Mg-K magmatic rocks (the vaugnerites), intrusive into the granite-gneiss sequences of the Variscan Vosges crystalline massif. Those rocks, though subordinate in volume, are frequently associated with late collisional granites. In the Central-Southern Vosges, they appear either as (1) pluton margin of the Southern Vosges Ballons granite complex or (2) composite dykes intrusive into migmatite and metamorphic sequences classically referred to as granite-gneiss unit (Central Vosges). Both types correspond to melanocratic rocks with prominent, Mg-rich, biotite and hornblende (20- 40 % vol., 64 < mg# < 78), two-feldspar and quartz. Those Vosges vaugnerites display geochemical signatures characteristic of mafic to intermediate, metaluminous to slightly peraluminous rocks of calc-alkaline affinity. Zircon U-Pb ages were obtained by Laser Ablation Inductively Coupled Plasma Mass Spectrometry. Zircons were extracted from a sillimanite-bearing gneiss from the granite-gneiss unit hosting the Central Vosges vaugnerites. They yielded an age at 451 ± 9 Ma, indicating a pre- Variscan Upper Ordovician protolith for the host sequence. Zircon from the four vaugnerite intrusives display U-Pb ages (± 2s) of 340 ± 2.5 Ma (Ballons), 340 ± 25 Ma, 340 ± 7 Ma and 336 ± 10 Ma (Central Vosges). Synchronous within uncertainty, vaugnerite age data thus give consistent results suggesting a relatively early emplacement of the vaugnerites regarding the Late Variscan collisional history, i.e. during Middle Visean times. These results are in line with previously published ages within the Southern Vosges volcano-sedimentary sequences (Oderen- Markstein) and the nearby Mg-K granite complexes from the Central and Southern Vosges (Ballons, Crêtes) thereby arguing for a Mg-K magmatic event of regional significance. Recent petrological studies on vaugnerites suggest that they derive from partial melting of a metasomatized mantle contaminated to some different degrees by elements of continental crust. We propose here the major Mg-K magmatic pulse at 340-335 Ma to be the marker of a significant evolution into the dynamics of the Rhenohercynian subduction system below the Central-Southern Vosges. In the light of recent thermo-mechanical modelling experiments on mature continental collision, it could traduce the first effects of a syn-collisional lithospheric delamination mechanism involving (1) first, continental subduction evolving towards (2) the underthrusting of the Avalonian continental margin lower crust and (3) the initiation of lithospheric delamination within the supra-subduction retro-wedge (Saxothuringian- Moldanubian continental block). This process would drive the emplacement of an asthenospheric upwelling, initially localized along the Variscan suture zones, and gradually propagating towards the southern front of the belt during the Late Carboniferous, as the delamination front migrated at the base of the crust.

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Section: Outcrop-scale Observations and Samplingmentioning

confidence: 99%

Section: Zircon Chemistry and Thermometry 441 Zircon Th And Umentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Zircon age of vaugnerite intrusives from the Central and Southern Vosges crystalline massif (E France): contribution to the geodynamics of the European Variscan belt

Guillot

Averbuch

Dubois

et al. 2020

BSGF - Earth Sci. Bull.

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“…Considerable amounts of studies had been conducted on ultrapotassic rocks which are mostly focusing on their mantle source and partial melting processes (e.g., Thompson et al, 1990;Conticelli and Peccerillo, 1992;Foley and Peccerillo, 1992;Rogers et al, 1992;Zhang et al, 1995;Miller et al, 1999;Lobach-Zhuchenko et al, 2008;Gaeta et al, 2016). Metasomatized mantle sources and relatively low degree of melting process had been proposed for the generation of ultrapotassic primary melts (e.g., Dawson, 1987;Marks et al, 2008;Sun et al, 2014;Bodeving et al, 2017;Soder and Romer, 2018;Sokół et al, 2018). Nevertheless, most of the ultrapotassic rocks are not solidified from primary mantlederived liquids, thus the subsequent differentiation processes of ultrapotassic magmas in the crust including fractionation crystallization, crustal contamination, magma (un-)mixing and mingling, and exsolution/transportation of both magmatic and post-magmatic fluids could also play important roles in the formation of them (e.g., Ferlito and Lanzafame, 2010;Jeffery et al, 2013;Brenna et al, 2015;Wolff, 2017;Burchardt, 2018).…”

Section: Introductionmentioning

confidence: 99%

Mineralogical and Geochemical Study on the Yaojiazhuang Ultrapotassic Complex, North China Craton: Constraints on the Magmatic Differentiation Processes and Genesis of Apatite Ores

2020

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The differentiation process of ultrapotassic magmas is enigmatic and poorly understood. The Yaojiazhuang ultrapotassic complex is concentrically zoned by late-intruded syenite in the core and early emplaced clinopyroxenite in the periphery, combining a "bi-modal" lithology. Spatially, apatite and iron oxide-apatite (IOA) ores, glimmerite and pseudoleucite occur in the upper part of clinopyroxenite. The syenite and clinopyroxenite are composed of variable amounts of clinopyroxenite, biotite, K-feldspar, magnetite, apatite with minor analcite, titanite, and primary calcite. The pseudoleucite clinopyroxenite contains mainly clinopyroxene, biotite and garnet in the matrix, and nepheline-K-feldspar intergrowth with muscovite and minor celestine in the leucite pseudomorph. Geochemically, rocks of the Yaojiazhuang complex are significantly enriched in potassium (K), light rare earth elements (LREE), and large ion lithophile elements (LILE). Crustal contamination by Archean tonalite-trondhjemite-granodiorite (TTG) gneisses basement may play an important role to convert the syenitic melts from silica-undersaturation to saturation. Fractionation crystallization is supported by the mineral crystallization sequence to explain the bimodal lithologies instead of silicate liquid immiscibility. During the magmatic evolution, decompression, fractionation of volatilepoor clinopyroxene and the enhancement by CO 2 may result in the exsolution of an aqueous fluid. The late-stage interactions between existing minerals and magmatic fluids in the crystal mush could be a key process in the generation of both leucite pseudomorphs and apatite/IOA ores.

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Petrogenesis of the Late Mesozoic gabbros in the eastern Jiangnan Orogen, South China: Characteristics of the lithospheric mantle

Wang

Yan

et al. 2020

Geological Journal

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As we know, mantle‐derived mafic rocks can be used to effectively trace the nature of the mantle source and constrain the regional tectonic setting and evolution. Recently, a Late Mesozoic mafic intrusive body (Huangmao pluton) has been found in the eastern Jiangnan Orogen (EJO). In this study, we investigate this pluton using petrography, whole‐rock geochemistry, Sr–Nd–Pb isotopes, and geochronology. The Huangmao pluton is primarily composed of a fine‐grained gabbro‐diabase, which is characterized by consistent SiO2, MgO, Fe2O3T, and TiO2 contents. These gabbros exhibit continental crust‐like trace element signatures, i.e., enriched in large‐ion lithophile elements (LILE), Pb, and light rare earth elements (LREE), but depleted in high‐field‐strength elements (HFSE). In addition, the Huangmao gabbros have moderate initial 87Sr/86Sr ratio (0.7065–0.7080) and slightly negative to weakly positive εNd(t) value (−2.06 to +0.84). Finally, U–Pb zircon dating confirms that the Huangmao pluton was emplaced in the Late Jurassic (152.6 ± 3.1 Ma). Through an integrated geochemical analysis, these Late Mesozoic gabbros were genetically originated from an enriched lithospheric mantle source, which formed by a metasomatic reaction between mantle peridotite and sediment‐derived felsic melt. Consequently, the lithologies of the metasomatite were predominantly pyroxenites with a small amount of pyroxene‐rich peridotites. Considering the large distance between the modern trench and the EJO, the flat‐slab subduction and rollback model of the palaeo‐Pacific Plate is the most reasonable interpretation of the geodynamic setting that resulted in Late Mesozoic magmatism in the EJO.

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Post-collisional Potassic–Ultrapotassic Magmatism of the Variscan Orogen: Implications for Mantle Metasomatism during Continental Subduction

Cited by 86 publications

References 132 publications

Zircon age of vaugnerite intrusives from the Central and Southern Vosges crystalline massif (E France): contribution to the geodynamics of the European Variscan belt

Zircon age of vaugnerite intrusives from the Central and Southern Vosges crystalline massif (E France): contribution to the geodynamics of the European Variscan belt

Mineralogical and Geochemical Study on the Yaojiazhuang Ultrapotassic Complex, North China Craton: Constraints on the Magmatic Differentiation Processes and Genesis of Apatite Ores

Petrogenesis of the Late Mesozoic gabbros in the eastern Jiangnan Orogen, South China: Characteristics of the lithospheric mantle

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