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Cambro–Ordovician anatexis and magmatic recycling at the thinned Gondwana margin: new constraints from the Kouřim Unit, Bohemian Massif
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SYSNO ASEP 0508957 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Cambro–Ordovician anatexis and magmatic recycling at the thinned Gondwana margin: new constraints from the Kouřim Unit, Bohemian Massif Author(s) Soejono, I. (CZ)
Machek, Matěj (GFU-E) ORCID, RID
Sláma, Jiří (GLU-S) SAI, RID, ORCID
Janoušek, V. (CZ)
Kohút, M. (SK)Source Title Journal of the Geological Society. - : Geological Society Publishing House - ISSN 0016-7649
Roč. 177, č. 2 (2020), s. 325-341Number of pages 17 s. Publication form Print - P Language eng - English Country GB - United Kingdom Keywords Kouřim Unit ; Cambro-Ordovician ; lithospheric extension ; crustal anatexis ; Gondwana passive margin ; Bohemian Massif Subject RIV DB - Geology ; Mineralogy OECD category Geology Subject RIV - cooperation Institute of Geology - Geology ; Mineralogy Method of publishing Limited access Institutional support GFU-E - RVO:67985530 ; GLU-S - RVO:67985831 UT WOS 000537276100007 EID SCOPUS 85081136852 DOI 10.1144/jgs2019-037 Annotation The Kouřim Unit represents one of the largest pre-Variscan meta-igneous complexes in the Bohemian Massif and a geochronological, whole-rock geochemical and Sr-Nd isotopic study was conducted to better understand the magmatic evolution of the Early Paleozoic Gondwana margin. Five orthogneisses yield U-Pb zircon ages ranging from 492 +/- 4 to 484 +/- 2 Ma. Two leucogranites give U-Pb zircon ages of 500 +/- 4 and 485 +/- 2 Ma, interpreted to be inherited from their orthogneiss host rock. Two samples from the metasedimentary host rock are dominated by Neoproterozoic-Cambrian detrital zircons. The abundance of zircon inheritance in the orthogneisses and whole-rock Sr-Nd isotopic composition imply an origin from relatively mature continental crustal material. The subalkaline, subaluminous-slightly peraluminous and high-K calc-alkaline arc-like geochemical signature of the orthogneisses is interpreted as inherited from the recycled Cadomian metasedimentary source and both the magmatic and metasedimentary rocks are correlated with similar occurrences in the adjacent Moldanubicum and Tepla-Barrandian Unit. The Late Cambrian-Early Ordovician magmatic activity is linked to crustal anatexis, which was probably initiated by thermal and gravitational relaxation of the thickened Cadomian arc-type crust, followed by lithospheric thinning assisted by far-field forces. The extensional event led to the formation of a passive margin associated with the opening of the Rheic Ocean. Workplace Geophysical Institute Contact Hana Krejzlíková, kniha@ig.cas.cz, Tel.: 267 103 028 Year of Publishing 2021 Electronic address https://jgs.lyellcollection.org/content/177/2/325.abstract
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