Nova Terra 52

Vol.:(0123456789) 3 International Journal of Earth Sciences (2021) 110:467–485 https://doi.org/10.1007/s00531-020-01963-0 ORIGINAL PAPER Geochemistry and Sm–Nd isotopic sources of Late Ediacaran siliciclastic series in the Ossa–Morena Complex: Iberian–Bohemian correlations Esther Rojo-Pérez 1 · José M. Fuenlabrada 2 · Ulf Linnemann 3 · Ricardo Arenas 1 · Sonia Sánchez Martínez 1 · Rubén Díez Fernández 4 · Luis Miguel Martín Parra 4 · Jerónimo Matas 4 · Pilar Andonaegui 1 · Javier Fernández-Suárez 1 Received: 6 April 2020 / Accepted: 10 November 2020 / Published online: 2 January 2021 © Geologische Vereinigung e.V. (GV) 2021 Abstract The Cadomian basement in central and southern Europe is composed by Ediacaran–Early Cambrian sequences that appear dismembered along the Variscan Orogen. These ancient series contain geochemical and isotopic keys related to their depo- sition in different basins located along the paleo margin of Gondwana. The southwest of Iberian Massif (Ossa–Morena Complex) contains an excellent representation of Cadomian basement. The oldest sedimentary succession of this region, the Serie Negra Group (c. 600–541 Ma), is composed by the Montemolín Formation which consists of metapelites, meta- greywackes and abundant amphibolites; and the Tentudía Formation which consists of metagreywackes, black quartzites and metapelites. The whole-rock and Nd isotopic geochemistry of the Montemolín and Tentudía formations, are consistent with a deposition in a back-arc or fore-arc setting. Their Nd isotopic composition shows highly negative ε Nd ( t ) values in a range between −6.9 and −11.5, resulting in old Paleoproterozoic Nd model ages between 1.9 and 1.7 Ga. The Nd isotopic signatures obtained for the Cadomian basement in the Iberian Massif are almost identical to those obtained for equivalent sedimentary series in the Saxo-Thuringian Zone (Bohemian Massif), where Nd model ages range between 2 and 1.6 Ga. The limited variability of these Nd-T DM ages suggests that the southwestern Iberian and North Bohemian series shared a common source during Ediacaran times, which would be located close to the periphery of the West African Craton. The Nd isotopic data considered herein provide solid evidence about the peri-Gondwanan location and correlation between the Cadomian basement of southwestern Iberia and North Bohemia. Keywords Late Ediacaran series · Iberian massif · Bohemian massif · Nd isotope geochemistry · Variscan correlation · Peri-Gondwana paleogeography * Esther Rojo-Pérez e.rojo@ucm.es José M. Fuenlabrada jmfuenla@ucm.es Ulf Linnemann ulf.linnemann@senckenberg.de Ricardo Arenas rarenas@ucm.es Sonia Sánchez Martínez s.sanchez@geo.ucm.es Rubén Díez Fernández r.diez@igme.es Luis Miguel Martín Parra lm.martin@igme.es Jerónimo Matas j.matas@telefonica.net Pilar Andonaegui andonaeg@ucm.es Javier Fernández-Suárez jfsuarez@ucm.es 1 Departamento de Mineralogía y Petrología and Instituto de Geociencias (UCM, CSIC), Facultad de Geología, Universidad Complutense de Madrid, C/José Antonio Novais, no 2, 28040 Madrid, Spain 2 Unidad de Geocronología (CAI de Ciencias de la Tierra y Arqueometría), Universidad Complutense, 28040 Madrid, Spain 3 Museum Für Mineralogie Und Geologie, Senckenberg Naturhistorische Sammlungen Dresden, Königsbrücker Landstr. 159, 01109 Dresden, Germany 4 Instituto Geológico y Minero de España, 28760 Tres Cantos, Madrid, Spain