Reconstruction of the mid-Devonian HP-HT metamorphic event in the Bohemian Massif (European Variscan belt)

Geoscience Frontiers

卷:13

Karel Schulmann¹  Pavla Štípská²  Yingde Jiang²  Stephen Collett³  Vít Peřestý³  Piérig Deiller³  Marc Ulrich³  Jitka Míková⁴  Luc de Hoÿm de Marien⁵ 

[1] Corresponding author.;

[2] Institut Terre et Environnement de Strasbourg, UMR 7063 Université de Strasbourg — CNRS, 1 Rue Blessig, 67084 Strasbourg, Cedex, France;

[3] Centre for Lithospheric Research, Czech Geological Survey, Klárov 3, 118 21 Praha 1, Czech Republic;

[4] Institute of Petrology and Structural Geology, Charles University, Albertov 6, Praha 2 128 43, Czech Republic;

关键词: Variscan Orogeny;    Avalonian-Cadomian Orogeny;    Eclogite;    Geochemistry;    Zircon Lu–Hf geochronology;   

DOI  :  

来源: DOAJ

【 摘 要 】

Mid-Devonian high-pressure (HP) and high-temperature (HT) metamorphism represents an enigmatic early phase in the evolution of the Variscan Orogeny. Within the Bohemian Massif this metamorphism is recorded mostly in allochthonous complexes with uncertain relationship to the major tectonic units. In this regard, the Mariánské Lázně Complex (MLC) is unique in its position at the base of its original upper plate (Teplá-Barrandian Zone). The MLC is composed of diverse, but predominantly mafic, magmatic-metamorphic rocks with late Ediacaran to mid-Devonian protolith ages. Mid-Devonian HP eclogite-facies metamorphism was swiftly followed by a HT granulite-facies overprint contemporaneous with the emplacement of magmatic rocks with apparent supra-subduction affinity. New Hf in zircon isotopic measurements combined with a review of whole-rock isotopic and geochemical data reveals that the magmatic protoliths of the MLC, as well as in the upper plate Teplá-Barrandian Zone, developed above a relatively unaltered Neoproterozoic lithospheric mantle. They remained coupled with this lithospheric mantle throughout a geological timeframe that encompasses separate Ediacaran and Cambrian age arc magmatism, protracted early Paleozoic rifting, and the earliest phases of the Variscan Orogeny. These results are presented in the context of reconstructing the original architecture of the Variscan terranes up to and including the mid-Devonian HP-HT event.

【 授权许可】

Unknown