Middle/Late Cambrian intracontinental rifting in the central West Sudetes, NE Bohemian Massif (Czech Republic): geochemistry and petrogenesis of the bimodal metavolcanic rocks

0145353 - GLU-S 20013246 RIV GB eng J - Journal Article
Dostal, J. - Patočka, František - Pin, CH.
Middle/Late Cambrian intracontinental rifting in the central West Sudetes, NE Bohemian Massif (Czech Republic): geochemistry and petrogenesis of the bimodal metavolcanic rocks.
Geological Journal. Roč. 36, č. 1 (2001), s. 1-17. ISSN 0072-1050. E-ISSN 1099-1034
R&D Projects: GA ČR GA205/93/0341; GA AV ČR IAA3111102
Institutional research plan: CEZ:AV0Z3013912
Keywords : bimodal metavolcanics * Early Palaeozoic * northern Gondwana
Subject RIV: DB - Geology ; Mineralogy
Impact factor: 1.476, year: 2001

The Early Palaeozoic East Krkonoše Complex situated in the central West Sudetes, NE Bohemian Massif, is a volcano-sedimentary suite containing abundant mafic and felsic volcanics metamorphosed to greenschist facies.The trace element distribution patterns and Nd isotope signatures (ENd500 = +3.1 to +6.6) of the metabasalts indicate that they may be related to a rising mantle diapir associated with intracontinental rifting. At the early stage, limited melting of an upwelling asthenosphere produced alkali basalts and enriched tholeiites which compositionally resembled oceanic island basalts. A later stage of rifting larger degrees of melting at shallower depths generated tholeiitic basalts with E-MORB to N-MORB characteristics.The values of (87Sr/86Sr)i = 0.706 and ENd500 = -5,1 of the metarhyolites as well as the lack of rocks with intermediate composition suggest that the felsic rocks were formed by partial melting of continental crust triggered by mantle melts.The geochemistry of the bimodal metavolcanics and their association with abundant terrigenous metasediments suggest that the felsic-mafic volcanic suite was generated during an early stage of intracontinental rifting. This process, widespread in Western and Central Europe during the Early Palaeozoic, is an evidence of large-scale fragmentation of the northern margin of the Gondwana supercontinent.
Permanent Link: http://hdl.handle.net/11104/0042961