Journal
GONDWANA RESEARCH
Volume 93, Issue -, Pages 73-88Publisher
ELSEVIER
DOI: 10.1016/j.gr.2021.02.001
Keywords
Detrital zircon provenance; Moroccan Mesetas; syn-collisional sediments; Avalonian magmatic arc
Categories
Funding
- Ministerio de Economia y Competitividad (MINECO) of Spain [CGL2015-71692, BES-2016-078168]
- AuScope
- Australian Government via the National Collaborative Research Infrastructure Strategy (NCRIS)
- Australian Research Council LIEF program [LE150100013]
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The U-Pb dating and Hf isotopic analyses of detrital zircon grains from Cambrian-Devonian strata in the Moroccan Mesetas provide insights into the Paleozoic paleogeographic evolution. The presence of significant detrital zircon populations from various ages suggests the main sediment source for northern Morocco was the West African Craton. The collisional evolution began with the approach of an Avalonian promontory to the northern Gondwana continental margin, resulting in the formation of a magmatic arc in the upper plate.
U-Pb dating and Hf isotopic analyses of detrital zircon grains from Cambrian-Devonian strata in the Moroccan Mesetas were undertaken in order to constrain its Paleozoic paleogeographic evolution. In this work, we analyzed 12 Late Devonian-Late Carboniferous samples of syn-collisional detrital rocks from the Western and Eastern Moroccan Mesetas. All our samples present significant Ediacaran (ca. 620 Ma) and Rhyacian (ca. 2.1 Ga) detrital zircon populations, suggesting that the West African Craton remained the main source of sediments for northern Morocco at least until the Late Carboniferous. Locally, a Stenian-Tonian (ca. 1.0 Ga) detrital zircon population is also present, probably fed from intermittent and distant source areas located in NE Africa (e.g. Sahara Metacraton). The collisional evolution started with the approach of an Avalonian promontory to the northern Gondwana continental margin (latest Devonian earliest Carboniferous), after the closure of the Rheic Ocean. This process entailed the former subduction of the Rheic oceanic lithosphere underneath the Avalonian continental terrane and the formation of a magmatic arc in the upper plate. In this scenario, the first syn-collisional sediments (Tournaisian; Tiflet and Debdou-Mekkam areas) are characterized by a Devonian detrital zircon population (ca. 370 Ma), presumably derived from the magmatic arc, and an increasing number of Mesoproterozoic dates, putatively also sourced from the continental crust of the Avalonian terrane. After the initial collision, only the Visean samples located in areas close to the exotic terrane (e.g. Ben Slimane area) displayed a minor Avalonian component. Finally, the Late Carboniferous samples from the Jerada area recorded an important Middle Carboniferous (ca. 330 Ma) detrital zircon population, probably sourced from Variscan granitoids emplaced in the Eastern Moroccan Meseta and attesting to crustal thickening and subsequent thermal maturation of the Gondwana continental crust in this area. (c) 2021 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.
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