Systematics of detrital zircon U–Pb ages from Cambrian–Lower Devonian rocks of northern Morocco with implications for the northern Gondwanan passive margin

• Published in: Precambrian research 2021-10, Vol.365, p.106366, Article 106366
• Main Authors: Accotto, Cristina, Martínez Poyatos, David, Azor, Antonio, Talavera, Cristina, Evans, Noreen J., Jabaloy–Sánchez, Antonio, Tahiri, Abdelfatah, El Hadi, Hassan, Azdimousa, Ali
• Format: Article
• Language: English
• Subjects: Cambrian rifting; Moroccan Mesetas; Northern Gondwanan margin; NW African Variscides; Provenance study; West African Craton
• ISSN: 0301-9268; 1872-7433
• DOI: 10.1016/j.precamres.2021.106366

[Display omitted] •A total of 41 samples (25 from literature and 16 new) are reported.•The nearby West African Craton was the main sediment source.•A change from Cadomian to Pan-African sources occurred at Middle Ordovician time.•540–450 Ma zircon grains sourced from local rift-related magmatic centers.•A sporadic input of 1 Ga zircon grains from NE African cratons is locally detected. The systematic acquisition of U–Pb geochronological data from detrital zircon grains has become an essential tool in tectonic studies focused on reconstructing the pre–Variscan geography of the northern Gondwanan passive margin. New detrital zircon ages for 16 samples from the Cambrian–Lower Devonian succession of the Moroccan Mesetas (northern Morocco) are reported here. The results, combined with previously published data, reassert the strong West African Craton affinity of the Paleozoic sedimentary rocks, characterized by dominant Cadomian/Pan–African (c. 850–540 Ma) and Eburnean (c. 2.2–1.9 Ga) detrital zircon populations and a minor Leonian/Liberian (c. 2.5 Ga) population. Primary sources of these zircon grains are well established as the West African Craton located just to the south, but also in the Precambrian basement that locally crops out in the Moroccan Mesetas themselves. During the Cambrian–Early Ordovician, erosion preferentially dismantled Cadomian (c. 590–540 Ma) arc–derived rocks of the Gondwanan continental margin, while later, the slightly older Pan–African (c. 650–600 Ma) basement became the main sediment source. In the studied samples, irregularly present minor detrital zircon populations suggest additional sediment provenance from secondary sources such as: (i) remote northeastern African cratons (e.g., Saharan Metacraton and/or Arabian–Nubian Shield) that likely could have provided the c. 1.1–0.9 Ga and, possibly, the c. 1.9–1.7 Ga zircon grains, and (ii) rift–related Cambrian–Early Ordovician volcanic centers in the Moroccan Mesetas that supplied heterogeneously distributed – although locally dominant in small areas – sedimentary detritus before rift abortion and burial underneath the overlying passive margin sedimentary succession.