ISSN:
0016-7835
Keywords:
Key words Teplá
;
Barrandian
;
Cadomian orogeny
;
Variscides
;
Bohemian Massif
;
Barrovian-type metamorphism
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
Abstract The Cadomian basement of the Teplá–Barrandian unit is characterized by a classic Barrovian-type metamorphism, the degree of which increases considerably towards the west reaching amphibolite facies conditions in the Domaz˘lice crystalline complex (DCC). The number and volume of plutons also increases towards the west. The emplacement ages of the Te˘s˘ovice granite and the Mrac˘nice trondhjemite have been determined at 521.7±2 Ma and 523+4/–5 Ma, respectively, applying conventional U–Pb analyses of zircons. Pervasive high-temperature prolate fabrics and north-/northwest-dipping, dextral oblique-slip shear zones within the Mrac˘nice trondhjemite suggest a synkinematic melt emplacement within a Lower Cambrian transtensional setting. Transtension is probably related to early-stage rifting that introduced the separation of the Teplá–Barrandian unit (as part of Armorica) from Gondwana. Structural and petrological data of the country rocks show that the Barrovian-type metamorphism and two deformation stages (D1 with unknown kinematics and D2 top-to-the-north shearing) are older than the melt emplacement, and thus can be attributed to the Cadomian orogeny. The intrusion depth of both plutons is nearly the same (ca. 7 km), although the degree of Barrovian-type metamorphism differs significantly within the country rocks. This suggests late Cadomian eastward tilting of the metamorphic isograd planes. The weak post-plutonic, lower-greenschist to subgreenschist facies folding and thrusting result from Variscan northwest/southeast compression.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s005310050164
Permalink
