Detrital zircon similarities and dissimilarities between the Iberian Pyrite Belt, Ossa-Morena Zone and Meguma

Abstract

Acknowledgement. We thank Ícaro Dias da Silva and an anonymous reviewer for their constructive comments and suggestions. We also acknowledged Jose Javier Álvaro Blasco and Laura Rincón for editorial handling. We acknowledge the support of FCT through PhD grant SFRH/BD/138791/2018 to João Lains Amaral and through project UIDB/50019/2020 to Instituto Dom Luiz.

Despite the so-called exotic nature of the South Portuguese Zone relatively to the other major domains of the Iberian Massif of peri-Gondwanan affinity, Devonian detrital rocks of the oldest strata in the Iberian Pyrite Belt have a remarkable resemblance with the Ossa-Morena Zone's Neoproterozoic-Cambrian rocks and the West Meguma's Cambrian-Ordovician rocks, presenting the so-called "West African signature". Using published U-Pb detrital zircon data, we discuss the similarities and dissimilarities between the Iberian Pyrite Belt, Ossa-Morena Zone and West Meguma Terrane through multidimensional scaling, comparing them with other zones of the Iberian Massif, Saxo-Thuringian Zone, Avalonia-Ganderia, and the North African cratonic regions. Our findings show that multidimensional scaling is not entirely effective in displaying the dissimilarities between the peri-Gondwanan terranes due to the background noise caused by the overwhelming number of CadomianPanafrican ages. However, it becomes a powerful tool if these ages are filtered. A dominant Meguma-type provenance (Cambro-Ordovician) for the middle-upper Devonian rocks of the Iberian Pyrite Belt is demonstrated, mainly attending to their similar Birimian-Eburnean pattern. The possibility of minor contributions from the lower Cambrian rocks of the Ossa-Morena Zone into the Iberian Pyrite Belt quartzites is unlikely, as the latter lack the 1.9Ga peak that characterises the Ossa-Morena Zone sediments. Additionally, the remarkable similarities between Ossa-Morena Zone and West Meguma's detrital rocks strongly suggest a similar paleogeographic setting (but diachronic?) for both terrains from the Ediacaran to Lower Ordovician times relative to the North African blocks.