Late Cadomian crustal tilting and Cambrian transtension in the Teplá-Barrandian unit (Bohemian Massif, Central European Variscides)

摘要: The Cadomian basement of the Tepla–Barrandian unit is characterized by a classic Barrovian-type metamorphism, degree which increases considerably towards west reaching amphibolite facies conditions in Domaz˘lice crystalline complex (DCC). number and volume plutons also west. emplacement ages Te˘s˘ovice granite Mrac˘nice trondhjemite have been determined at 521.7±2 Ma 523+4/–5 Ma, respectively, applying conventional U–Pb analyses zircons. Pervasive high-temperature prolate fabrics north-/northwest-dipping, dextral oblique-slip shear zones within suggest synkinematic melt Lower Cambrian transtensional setting. Transtension probably related to early-stage rifting that introduced separation (as part Armorica) from Gondwana. Structural petrological data country rocks show metamorphism two deformation stages (D1 with unknown kinematics D2 top-to-the-north shearing) are older than emplacement, thus can be attributed orogeny. intrusion depth both nearly same (ca. 7 km), although differs significantly rocks. This suggests late eastward tilting metamorphic isograd planes. weak post-plutonic, lower-greenschist subgreenschist folding thrusting result Variscan northwest/southeast compression.