caa a22 4500 606150102 CHVBK 20210128100537.0 cr unu---uuuuu 210128e20150701xx s 000 0 eng 10.1007/s00531-015-1149-3 doi (NATIONALLICENCE)springer-10.1007/s00531-015-1149-3 The multistage crystallization of zircon in calc-alkaline granitoids: U-Pb age constraints on the timing of Variscan tectonic activity in SW Iberia [Elektronische Daten] [M. Pereira, M. Chichorro, P. Moita, J. Santos, A. Solá, I. Williams, J. Silva, R. Armstrong] CL imaging and U-Th-Pb data for a population of zircons from two of the Évora Massif granitoids (Ossa-Morena Zone, SW Iberia) show that both calc-alkaline granitoids have zircon populations dominated by grains with cores and rims either showing or not showing differences in Th/U ratio, and having ages in the range ca. 350-335Ma (Early Carboniferous). Multistage crystallization of zircon is revealed in two main growth stages (ca. 344-342Ma and ca. 336-335Ma), well represented by morphologically complex zircons with cores and rims with different ages and different Th/U ratios that can be explained by: (1) crystallization from melts with different compositions (felsic peraluminous to felsic-intermediate metaluminous; 0.001<Th/U ratio<0.5) and (2) transient temperature fluctuations in a system where anatectic felsic melts periodically underwent injection of more mafic magmas at higher temperatures. The two studied calc-alkaline granitoids do not include inherited zircons (pre-Carboniferous), probably because they were formed at the highest grade of metamorphism (T>837°C; granulite facies) and/or because they were derived from inheritance-poor felsic and mafic rocks from a previous cycle, as suggested by the internal structures of zircon cores. These Variscan magmatic rocks with crystallization ages estimated at ca. 336-335Ma are spatially and temporally related to high-temperature metamorphism, anatexis, processes of interaction between crustal- and mantle-derived magmas and intra-orogenic extension that acted in SW Iberia during the Early Carboniferous. Springer-Verlag Berlin Heidelberg, 2015 Igneous zircon nationallicence U-Th-Pb SHRIMP data nationallicence Crustal- and mantle-derived magmas nationallicence Intra-orogenic extension nationallicence Early Carboniferous nationallicence Ossa-Morena Zone nationallicence Pereira M. IDL/Departamento de Geociências, ECT, Universidade de Évora, Évora, Portugal aut Chichorro M. CiCEGE/Departamento de Ciências da Terra, Universidade Nova de Lisboa, Lisbon, Portugal aut Moita P. Centro de Geofísica de Évora/Departamento de Geociências, ECT, Universidade de Évora, Évora, Portugal aut Santos J. Geobiotec, Departamento de Geociências da, Universidade de Aveiro, Aveiro, Portugal aut Solá A. LNEG, Unidade de Geologia e Cartografia Geológica, Porto, Portugal aut Williams I. Research School of Earth Sciences, The Australian National University, Acton, Australia aut Silva J. IDL/Departamento de Geologia, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal aut Armstrong R. Research School of Earth Sciences, The Australian National University, Acton, Australia aut International Journal of Earth Sciences Springer Berlin Heidelberg 104/5(2015-07-01), 1167-1183 1437-3254 104:5<1167 2015 104 531 https://doi.org/10.1007/s00531-015-1149-3 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00531-015-1149-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pereira M. IDL/Departamento de Geociências, ECT, Universidade de Évora, Évora, Portugal aut NATIONALLICENCE 700 1- Chichorro M. CiCEGE/Departamento de Ciências da Terra, Universidade Nova de Lisboa, Lisbon, Portugal aut NATIONALLICENCE 700 1- Moita P. Centro de Geofísica de Évora/Departamento de Geociências, ECT, Universidade de Évora, Évora, Portugal aut NATIONALLICENCE 700 1- Santos J. Geobiotec, Departamento de Geociências da, Universidade de Aveiro, Aveiro, Portugal aut NATIONALLICENCE 700 1- Solá A. LNEG, Unidade de Geologia e Cartografia Geológica, Porto, Portugal aut NATIONALLICENCE 700 1- Williams I. Research School of Earth Sciences, The Australian National University, Acton, Australia aut NATIONALLICENCE 700 1- Silva J. IDL/Departamento de Geologia, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal aut NATIONALLICENCE 700 1- Armstrong R. Research School of Earth Sciences, The Australian National University, Acton, Australia aut NATIONALLICENCE 773 0- International Journal of Earth Sciences Springer Berlin Heidelberg 104/5(2015-07-01), 1167-1183 1437-3254 104:5<1167 2015 104 531