Syn-convergent high-temperature metamorphism and magmatism in the Variscides: a discussion of potential heat sources

Henk, Andreas; Blanckenburg, Friedhelm von; Finger, Friedrich; Schaltegger, Urs; Zulauf, Gernold

doi:10.1144/gsl.sp.2000.179.01.23

Cited by 69 publications

(46 citation statements)

References 60 publications

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“…These facts are clearly at variance with models that designate collisional crustal thickening and radiogenic heat production as the main reasons for granite magma formation in the south-western Bohemian Massif. Since late Variscan subduction models have turned out to be unlikely for the Bohemian Massif (Franke 2000), we hold the view that a process of post-collisional delamination of lithospheric mantle (Bird 1979;Houseman et al 1981;Henk et al 2000) can probably best explain the plutonic phenomena observed in the SDGB.…”

Section: In Search Of a Tectonic Scenariomentioning

confidence: 72%

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The Saxo-Danubian Granite Belt: magmatic response to post-collisional delamination of mantle lithosphere below the southwestern sector of the Bohemian Massif (Variscan orogen)

Finger¹,

Gerdes

René³

et al. 2009

Geologica Carpathica

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Abstract:On the basis of the synchronicity of geochronological data and the similarity of granite types, it is proposed that the mid-Carboniferous Fichtelgebirge/Erzgebirge Batholith in the Saxothuringian Zone of the central European Variscan Fold Belt and the South Bohemian Batholith in the Moldanubian Zone (including the intervening Oberpfalz and Bavarian Forest granite areas) belong to one coherent and cogenetic, ca. 400 km long plutonic megastructure. Unlike older (syn-collisional) plutonic structures in the Bohemian Massif, this Saxo-Danubian Granite Belt (nov. nom.) has developed discordant to the Devonian/Early Carboniferous collision-related tectonic architecture of the Bohemian Massif. It is argued that the Saxo-Danubian Granite Belt formed in response to a post-collisional detachment of lithospheric mantle below the south-western sector of the Bohemian Massif.

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Section: In Search Of a Tectonic Scenariomentioning

confidence: 72%

“…Zwart & Dornsiepen 1980;Henk et al 2000). Various tectonic scenarios have been invoked to explain it.…”

Section: In Search Of a Tectonic Scenariomentioning

confidence: 99%

The Saxo-Danubian Granite Belt: magmatic response to post-collisional delamination of mantle lithosphere below the southwestern sector of the Bohemian Massif (Variscan orogen)

Finger¹,

Gerdes

René³

et al. 2009

Geologica Carpathica

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“…The style of orogenic collapse of the French Massif Central has been compared with that of the Tibetan plateau and the Basin and Range province (Mattauer et al 1988; Ménard and Molnar 1988). The geodynamic processes responsible for the cessation of contractional deformation and the onset of orogenic collapse in the Variscides, however, are still the subject of much interest and the roles of slab detachment, delamination and convective removal of the mantle lithosphere remain hotly debated (e.g., Schaltegger 1997;Zulauf 1997a;Thompson et al 1997;Willner et al 2002;Bruguier et al 2003;Schott and Schmeling 1998;Henk et al 2000;Arnold et al 2001;Schulmann et al 2002Schulmann et al , 2005.…”

Section: Introductionmentioning

confidence: 99%

Elevator tectonics and orogenic collapse of a Tibetan-style plateau in the European Variscides: the role of the Bohemian shear zone

Dörr

Zulauf

2008

Int J Earth Sci (Geol Rundsch)

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Variscan collision of peri-Gondwanan terranes led to a doubly vergent crustal wedge that was thicker than 55 km in the area of the Bohemian Massif. This crustal thickness resulted in a highly elevated Bohemian plateau with a topographic height[3-4 km. The Bohemian plateau was covered with unmetamorphic Paleozoic strata, all of which are today well preserved in the Tepla-Barrandian unit because of crustal-scale vertical slip along the Bohemian shear zone (BSZ). The BSZ forms a subvertical, ca. 500-km long and up to 2-km wide belt of dip-slip mylonites which show several 90°deflections in map view. Tepla-Barrandian-down movements were active under retrograde metamorphic conditions, starting with granulite and ceasing with greenschist facies conditions. As slip along the BSZ was largely vertical and led to a minimum throw of 10 km, this type of crustal-scale deformation is referred to as elevator tectonics. The elevator-style movements caused the juxtaposition of the supracrustal TeplaBarrandian lid (the ''elevator'') against high-grade rocks of the extruding orogenic root. The BSZ has further governed the foci of mantle-derived plutonism. New U-Pb zircon and monazite TIMS dating of six plutons suggest that emplacement of mantle-derived melts along the BSZ lasted for at least 20 m.y., starting with the emplacement of the Klatovy granodiorite at 347 ?4/-3 Ma and ceasing with the emplacement of the Drahotin pluton at 328 ± 1 Ma. When taking into account the new ages of synkinematic plutons, the simultaneous vertical slip along the individual segments of the BSZ (North, West, and Central Bohemian shear zone) is bracketed to the period 343-337 Ma. Elevator tectonics was probably controlled by delamination of thickened mantle lithosphere that caused a dramatic thermal turnover and heating-up of the orogenic root. The overheated lower crust was thermally softened by anatexis and diffusion creep resulting in channel flow, vertical extrusion, fast uplift, and exhumation of the orogenic root.

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“…The viable possibilities include lithospheric thinning in a back-arc region, or asthenospheric mantle upwelling due to slab break-off or ridge subduction and slab window formation (Davies and von Blanckenburg 1995;Thorkelson 1996;Henk et al 2000).…”

Section: Granite Suitementioning

confidence: 99%

Mid-Ordovician and Late Devonian magmatism in the Togtokhinshil Complex: new insight into the formation and accretionary evolution of the Lake Zone (western Mongolia)

Soejono¹,

Buriánek²,

Svojtka³

et al. 2016

J. Geosci.

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New field, petrographic, geochemical and geochronological data from the Togtokhinshil Complex (western margin of the Lake Zone, Central Asian Orogenic Belt) reveal the presence of two separate Early Palaeozoic magmatic pulses: Mid-Ordovician and Late Devonian. The Mid-Ordovician (c. 460 Ma) magmatism produced various types of mafic plutonic rocks (gabbro-diorite suite) emplaced into the volcanosedimentary sequence of the Baatar Fm. Gabbros to gabbrodiorites have metaluminous and mostly low to normal-K calc-alkaline or possibly tholeiitic character. The majorand trace-element as well as Nd isotopic signatures suggest its magmatic-arc geotectonic setting and imply the derivation either exclusively from the mantle or in part from the juvenile mafic crust. The Late Devonian (c. 376 Ma) granite suite intruded the rocks of both the gabbro-diorite suite and the Baatar Fm. Granites are subaluminous and have a high-K calc-alkaline to shoshonitic character. Their magmatic arc-like geochemical signature is interpreted as inherited from the recycled arc-related crustal source. The granite suite seems a product of extensive mantle heat-induced crustal anatexis. The Depleted Mantle Nd model ages (c. 0.75 Ga) indicate derivation of the magmatic rocks of the both suites from relatively juvenile, and geochemically immature, sources. These results provide a clear evidence of the Mid-Ordovician arc-related magmatism in the western part of the Lake Zone. They thus prolong the assumed period of magmatic-arc activity and constrain onset of accretionary processes in this part of the Central Asian Orogenic Belt. The gabbro-diorite suite represents either part of a long-lived magmatic-arc or, more likely, a member of multiple island-arc system along the western margin of the Lake Zone. Newly described Late Devonian magmatism in the Togtokhinshil Complex provides further evidence of tectono-thermal event that was widespread in the Central Asian Orogenic Belt. The geodynamic cause for this event remains uncertain, but effects of lithospheric thinning and/or asthenospheric mantle upwelling are considered the most likely.

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Syn-convergent high-temperature metamorphism and magmatism in the Variscides: a discussion of potential heat sources

Cited by 69 publications

References 60 publications

The Saxo-Danubian Granite Belt: magmatic response to post-collisional delamination of mantle lithosphere below the southwestern sector of the Bohemian Massif (Variscan orogen)

The Saxo-Danubian Granite Belt: magmatic response to post-collisional delamination of mantle lithosphere below the southwestern sector of the Bohemian Massif (Variscan orogen)

Elevator tectonics and orogenic collapse of a Tibetan-style plateau in the European Variscides: the role of the Bohemian shear zone

Mid-Ordovician and Late Devonian magmatism in the Togtokhinshil Complex: new insight into the formation and accretionary evolution of the Lake Zone (western Mongolia)

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