Inherited arc signature in Ediacaran and Early Cambrian basins of the Ossa-Morena Zone (Iberian Massif, Portugal): Paleogeographic link with European and North African Cadomian correlatives

From Cadomian arc to Ordovician passive margin: geochemical records preserved in metasedimentary successions of the Orlica-Śnieżnik Dome in SW Poland

“…In contrast, the GQ correspond to sediments deposited on the Gondwanan PM after separation of avalonia. The evolutionary scheme for the sedimentary basins and tectonic settings proposed for the OSD metasediments described in the present work is in agreement with the tectonic scenario suggested for the evolution of the neoproterozoic to Ordovician volcano-sedimentary successions preserved in the Saxo-Thuringian in Germany, and the Ossa-Morena and Central Iberian Zones in Portugal and Spain (e.g., Pereira et al 2006;linnemann et al 2008). Moreover, it corroborates current hypotheses for the formation of the Rheic Ocean (e.g., arenas et al 2007, Sánchez-García et al 2008Martinez et al 2009).…”

“…Moreover, the identical chemical characteristics of the MF and SF rocks despite their different depositional ages suggest that there was, over time, no important change in sediment source or in detritus type filling those basins. This same situation has already been recognized both for the neoproterozoic and the Early Cambrian metasediments of the Saxo-Thuringian (linnemann and Romer 2002) and the Ossa-Morena Zones (Pereira et al 2006). Moreover, the geochemical similarity of the rocks of the MF and the SF to sediments from the Saxo-Thuringian Zone (linnemann and Romer 2002) suggests that a common tectonic setting may be key to explaining the origin of the neoproterozoic to Cambrian volcanosedimentary successions in the OSD and other fragments of the Cadomian orogen preserved in the European Variscan Belt.…”

“…Thus, the volcano-sedimentary successions preserved in the OSD shows a very similar lithostratigraphic scheme to that observed in other parts of the Variscan Belt of Europe, e.g., the Saxo-Thuringian zone in Germany, and the OssaMorena and Central Iberian Zones in Spain and Portugal where relatively well-preserved fragments of Cadomian basement are covered by Cambrian and Ordovician successions (e.g., linnemann et al 2008;Pereira et al 2006). This conclusion is reinforced by the occurrence of basic and felsic metavolcanics preserved in the volcano-sedimentary successions of the OSD.…”

“…Data presented here document strong similarities between neoproterozoic and Early Palaeozoic rock Units in the OSD and Saxo-Thuringian Zone and consequently also other rock successions of similar age cropping out in the western part of the Variscan Belt of Europe (e.g., OssaMorena Zone, Pereira et al 2006). This implies that these Table 4 Elemental ratios typical of granites, andesites, ophiolites and sands from basic and silicic rocks The upper continental crust (UCC), lower continental crust (lCC) and oceanic crust (OC), and from examined rocks reported in this study a Condie (1993) b Spadea et al (1980) c Taylor and Mclennan (1985) Ratio crustal fragments were collectively part of the northern Gondwana margin and consequently bear a record of similar geodynamic scenario for neoproterozoic and Early Palaeozoic times.…”

“…This arc was later detached from the edge of Gondwana during late Cambrian-Early Ordovician times and drifted northward, resulting in the opening of the Rheic Ocean Murphy et al 2009;nance et al 2010). Cadomian rock complexes exposed within the Variscan Belt are composed of neoproterozoic basement intruded by latest Cambrian ca 540-480 Ma granitoids and covered by metamorphosed sediments of Cambrian to Ordovician age (e.g., linnemann and Romer 2002; Pereira et al 2006). a typical feature of this metasedimentary cover is the existence of a sedimentation gap related to the Cadomian orogenesis (the Cadomian unconformity) which affected at least the earliest Cambrian.…”