A review of U-Pb detrital zircon systematics from CambrianLower Devonian rocks of the Moroccan Meseta

Abstract

U-Pb geochronological analysis of detrital zircon grains is a powerful tool to decipher the pre-Mesozoic paleogeography. In this work, we present a sediment provenance study based on a compilation of 41 Cambrian-Early Devonian siliciclastic samples from the Moroccan Meseta. All of them are characterized by late Tonian-Ediacaran (c. 600 Ma, c. 50% of the data), Rhyacian-Orosirian (c. 2100 Ma, c. 20% of the data), and Neoarchean (c. 2500 Ma, c. 4% of the data) detrital zircon age populations indicating a strong West African Craton affinity. Minor populations are: (i) Cambrian-Ordovician (c. 500 Ma), particularly relevant in Lower Ordovician samples, which were probably sourced by local volcanic centers formed during an aborted rift; (ii) Stenian-early Tonian (c. 1000 Ma); and (iii) Orosirian-Statherian (c. 1800 Ma). These two latter populations were probably fed by paleocurrents from NE-African regions (e.g., Sahara Metacraton and Arabian-Nubian Shield) that reached only intermittently the studied area. Finally, the spatial and chronological distribution of the detrital zircon age populations suggests that the tectonic boundaries normally used to separate internal subdomains in northern Morocco did not imply far-travelled terranes during early-middle Paleozoic times.