Neoproterozoic of the Teplá-Barrandian Unit as a part of the Cadomian orogenic belt: A review and correlation aspects
Bulletin of Geosciences, volume 75, issue 3;
pages: 175 - 196;
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The Neoproterozoic of the Teplá-Barrandian Unit is interpreted as a relic of the Cadomian orogenic belt. Although its original position within the belt is far from being understood, gravimetric and geomagnetic picture of the central and west-European upper crust, lithological, geochemical and structural correlation studies indicate close relationships between the northern part of the Armorican Massif and the Neoproterozoic of the Teplá-Barrandian Unit. Lithologies of these two relics reflect prevailing periods of diastrophic deposition of clastic sediments alternating with periods of relative quiescency characterized by the deposition of black shales, cherts and less frequent limestones. Deposition of black shales and cherts mostly corresponds with periods of increased submarine-hydrothermal activity. In the Teplá-Barrandian Unit as well as in the Armorican Massif, geochemical character of synsedimentary volcanics is characteristic of both arc- and back-arc tectonic setting. The geochemical evolution of volcanic series in the Neoproterozoic of the Teplá-Barrandian Unit points to the evolving maturation of an originally primitive (oceanic) arc crust. The Cadomian evolution of the Neoproterozoic rocks of the Teplá-Barrandian Unit is comparable with the northern part of the Armorican Massif and comprises: (1) formation of volcanic arc, back-arc basin and remnant arc, (2) basin inversion and probably polyphase orogenic deformation associated with synorogenic sedimentation, and (3) post-Cadomian extension period associated with the formation of Cambrian basins. In contrast to other Cadomian relics in the Bohemian Massif (i.e., Lusatian granitoids and Brunovistulicum) and with Armorican Massif, large post-orogenic Cadomian granite and granodiorite massifs are absent from the Neoproterozoic of the Teplá-Barrandian Unit. The emplacement of numerous magmatic bodies of Cambrian age is related to the post-Cadomian extension period.