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Article
Geologica Carpathica, 1995, vol. 46, no. 3
A TECTONIC MODEL FOR THE EASTERN VARISCIDES: INDICATION FROM A CHEMICAL STUDY OF AMPHIBOLITES IN THE SOUTH-EASTERN BOHEMIAN MASSIF
Abstract
Metabasaltic amphibolites are a common rock type in the South-Eastern Bohemian Massif. Most of them range chemically from WPB type to MORB type, however, some data suggest local influxes from a subduction modified mantle source. The rocks appear to document passive rifting in the back arc realm of the northern Gondwana margin in the Early Paleozoic. Geological evidence suggests that a marginal Panafrican plutonic arc terrane (Moravo-Silesian plate) split off from Gondwana, opening a small Variscan sea behind (Raabs sea). This Raabs sea closed again by southward subduction below another Gondwana derived ”Moldanubian” continental terrane, which finally overrode the Moravo-Silesian terrane during the Variscan collision.
We propose that the Raabs sea was originally situated in the eastern continuation of the Saxothuringian rift, and that the Moravo-Silesian plate correlates with the Cadomian basement of mid Germany and North Brittanny, i.e. with the northern branch of the Variscan orogen. According to our model, the northern flank of the Variscan fold belt bends sharply southwards in the Eastern Bohemian Massif, in response to the forceful indentation of a Moldanubian terrane from the south.
Pages:
137 - 150
Published online:
0. 0. 1995