Late Variscan Magmatic Evolution of the Alpine Basement

Bonin, Bernard; Brändlein, P.; Bussy, F.; Desmons, Jacqueline; Eggenberger, Urs; Finger, Friedrich; Graf, Kelly; Marro, C.; Mercolli, I.; Oberhänsli, Roland; Ploquin, Alain; Quadt, Albrecht von; Raumer, Jürgen von; Schaltegger, Urs; Steyrer, Hans-Peter; Visonà, Dario; Vivier, Gérard Du

doi:10.1007/978-3-642-84640-3_11

Cited by 66 publications

(50 citation statements)

References 32 publications

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“…The widespread Stephanian-Early Permian (305-285 Ma) alkaline intrusive and extrusive magmatism of the Variscan domain and its foreland is mantle-derived and locally shows evidence of crustal contamination (Bonin 1990;Bonin et al 1993;Neumann et al 1995;Marx et al 1995;Benek et al 1996;Cortesogno et al 1998;Breitkreuz and Kennedy 1999;Neumann et al 2004). Melt generation by partial melting of the uppermost asthenosphere and the lithospheric thermal boundary layer was probably triggered by a rise in the potential temperature of the asthenosphere and by its localised transtensional decompression.…”

Section: Stephanian-early Permian Disruption Of the Variscan Orogenmentioning

confidence: 99%

Evolution of the lithosphere in the area of the Rhine Rift System

Ziegler

Dèzes

2005

Int J Earth Sci (Geol Rundsch)

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The Rhine Rift System (RRS) forms part of the European Cenozoic Rift System (ECRIS) and transects the Variscan Orogen, Permo-Carboniferous troughs and Late Permian to Mesozoic thermal sag basins. Crustal and lithospheric thicknesses range in the RRS area between 24-36 km and 50-120 km, respectively. We discuss processes controlling the transformation of the orogenically destabilised Variscan lithosphere into an end-Mesozoic stabilised cratonic lithosphere, as well as its renewed destabilisation during the Cenozoic development of ECRIS. By end-Westphalian times, the major sutures of the Variscan Orogen were associated with 45-60 km deep crustal roots. During the Stephanian-Early Permian, regional exhumation of the Variscides was controlled by their wrench deformation, detachment of subducted lithospheric slabs, asthenospheric upwelling and thermal thinning of the mantlelithosphere. By late Early Permian times, when asthenospheric temperatures returned to ambient levels, lithospheric thicknesses ranged between 40 km and 80 km, whilst the thickness of the crust was reduced to 28-35 km in response to its regional erosional and local tectonic unroofing and the interaction of mantle-derived melts with its basal parts. Re-equilibration of the lithosphere-asthenosphere system governed the subsidence of Late Permian-Mesozoic thermal sag basins that covered much of the RRS area. By end-Cretaceous times, lithospheric thicknesses had increased to 100-120 km. Paleocene mantle plumes caused renewed thermal weakening of the lithosphere. Starting in the late Eocene, ECRIS evolved in the Pyrenean and Alpine foreland by passive rifting under a collision-related north-directed compressional stress field. Following endOligocene consolidation of the Pyrenees, west-and northwest-directed stresses originating in the Alps controlled further development of ECRIS. The RRS remained active until the Present, whilst the southern branch of ECRIS aborted in the early Miocene. Extensional strain across ECRIS amounts to some 7 km. Plume-related thermal thinning of the lithosphere underlies uplift of the Rhenish Massif and Massif Central. Lithospheric folding controlled uplift of the VosgesBlack Forest Arch.

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Section: Stephanian-early Permian Disruption Of the Variscan Orogenmentioning

confidence: 99%

Evolution of the lithosphere in the area of the Rhine Rift System

Ziegler

Dèzes

2005

Int J Earth Sci (Geol Rundsch)

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“…The prevalence of Na 2 O over K 2 O is a common feature (K 2 O/ Na 2 O by weight = 0.25-1.15), including the porphyritic "Prašivá" type granite whose alkali ratio is close to 1. The medium-to high-K calc-alkaline character is a common attribute of the European Variscan granitoids (Bonin et al 1993). Biotite is the dominant ferromagnesian mafic mineral, whereas hornblende occurs only rarely in dioritic enclaves.…”

Section: Resultsmentioning

confidence: 99%

“…There exist many similarities between the Variscan granitic rocks of the Alpine "Neo-Europa" and those of the European Variscan belt in the Iberian Massif, the Massif Central, and the Bohemian Massif that represent "Meso-Europa" in sense of Stille (1924). The varieties of granitoid suites include: (a) high-K-Mg, (b) peraluminous, (c) calc-alkaline; (d) ferro-potassic, (e) subalkaline, and (f) anorogenic -alkaline (Bonin et al 1993;Finger et al 1997;Schaltegger 1997;Bussy et al 2000;Kohút 2002, among others). These suites were generated during main and late-Variscan orogenic stages.…”

Section: Introductionmentioning

confidence: 99%

Geochemical and isotopic (Sr, Nd and O) constraints on sources for Variscan granites in the Western Carpathians - implications for crustal structure and tectonics

Kohút¹,

Nábělek²

2012

J. Geosci.

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A Sr, Nd, and O isotopic study of Variscan granitoid rocks from the Western Carpathians reveals the dominance of heterogeneous crustal sources for the most of the granitic rocks. Their neodymium crustal index (NCI) is 0.4 to 1.0 (mainly 0.6-0.8 (350) of -0.6 to -6.9 preclude a simple mantle and/or crustal origin for most of granitoids and suggest more complex sources, such as vertically zoned lower crust consisting of old metaigneous, amphibolitic and metasedimentary rocks. Apparent crustal residence ages, indicated by two-stage depleted-mantle Nd model ages ranging from 1.6 to 1.1 Ga, are comparable with other segments of the European Variscan belt. The whole rock δ 18 O (SMOW) values of the granites are heterogeneous and range from 8.4 ‰ in tonalites to 11.3 ‰ in leucogranites, reflecting source compositions ranging from mafic to silicic. Petrographically, these granites are representative of common crustal anatectic rocks with magmatic muscovite; however, their isotopic signature reflects petrogenesis related to subduction processes at active continental margins. Recent metamorphic, sedimentary and/or structural studies of the Variscan basement of the Western Carpathians suggest a continental collisional rather than a volcanic arc setting. The Western Carpathian granitic rocks were most likely generated by partial melting of mainly recycled Proterozoic crustal material during subductioncollisional processes of the Variscan orogeny, with possible input of mafic magmas from the mantle. These mafic magmas may have served as a heat source for melting of the lower crust.

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“…More recently, major and trace element bulk-rock analyses have been used in several studies to reconstruct the tectonic and sedimentary setting of clastic sedimentary basins (Kutterolf et al, 2007). Since different plate tectonic configurations produce diverse magmatic suites (Bonin et al, 1993), of different chemical characteristics (which are transferred from the primary to the sedimentary rock) chemical patterns are used to discriminate geotectonic settings from sediments (Crook, 1974;Bhatia, 1983;Roser and Korsch, 1988), and have been applied in recent publications (Kroonenberg, 1994;Burnett and Quirk, 2001;Zimmermann and Bahlburg, 2003;Armstrong-Altrin et al, 2004;Wanas and Abdel-Maguid, 2006). The geochemical analysis of sedimentary rocks (such as matrix-rich sandstones) is a valuable tool for provenance studies, as long as the bulk composition is not strongly affected by diagenesis, metamorphism or other alteration processes (McLennan et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

Petrography and geochemistry of the late Eocene–early Oligocene submarine fans and shelf deposits on Lemnos Island, NE Greece. Implications for provenance and tectonic setting

Maravelis

Zelilidis

2010

Geological Journal

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Provenance and tectonic history of the late Eocene-early Oligocene submarine fans and shelf deposits on Lemnos Island, NE Greece, were studied using sandstone framework composition, sedimentological data and sandstone and mudstone geochemistry. The resulting tectonicsedimentological model is based on the late Eocene-early Oligocene Lemnos Island being in a forearc basin with the outer arc ridge as a major sediment source. Modal petrographic analysis of the studied sandstones shows that the source area comprises sedimentary, metamorphic and plutonic igneous rocks deposited in the studied area in a recycled orogenic environment. Moreover, within the above sediments, the minor occurrence of volcanic fragments suggests little or no influence of a volcanic source. Provenance results, based on major, trace and rare earth element (REE) data, suggest an active continental margin/continental island arc signature. All the samples are LREE, enriched relative to HREE, with a flat HREE pattern and positive Eu anomalies, suggesting that the processes of intracrustal differentiation (involving plagioclase fractionation) were not of great importance. Results derived from the multi-element diagrams also suggest an active margin character, and a mafic/ultramafic source rock composition, while the positive anomaly of Zr that can be attributed to a passive continental margin source, is most likely associated with reworking and sorting during sediment transfer. Palaeocurrents, with a NE-NNE direction, indicate a northeast flow, towards the location of the late Eocene-early Oligocene magmatic belt in the north-east Aegean region. Conglomerates are composed of chert, gneiss and igneous fragments, such as basalts and gabbros, suggesting this outer arc ridge as a likely source area.

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Late Variscan Magmatic Evolution of the Alpine Basement

Cited by 66 publications

References 32 publications

Evolution of the lithosphere in the area of the Rhine Rift System

Evolution of the lithosphere in the area of the Rhine Rift System

Geochemical and isotopic (Sr, Nd and O) constraints on sources for Variscan granites in the Western Carpathians - implications for crustal structure and tectonics

Petrography and geochemistry of the late Eocene–early Oligocene submarine fans and shelf deposits on Lemnos Island, NE Greece. Implications for provenance and tectonic setting

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