Polycyclic magmatism in the Tagragra d’Akka and Kerdous–Tafeltast inliers (Western Anti-Atlas, Morocco)
✍ Scribed by D. Gasquet; P. Chevremont; T. Baudin; F. Chalot-Prat; C. Guerrot; A. Cocherie; J. Roger; B. Hassenforder; A. Cheilletz
- Publisher
- Elsevier Science
- Year
- 2004
- Tongue
- English
- Weight
- 717 KB
- Volume
- 39
- Category
- Article
- ISSN
- 1464-343X
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✦ Synopsis
Four events have been identified in the Tagragra dÕAkka and Tafeltast-Kerdous inliers: (i) a middle Palaeoproterozoic (Orosirian, ca. 2.047 Ga) event corresponding to the emplacement of calc-alkaline and peraluminous granites containing older inherited zircon (2.07-2.15 Ga), (ii) an upper Palaeoproterozoic (Statherian) event corresponding to the emplacement of pegmatites and porphyritic microgranites (ca. 1.76 Ga), intimately associated with numerous mafic dikes assumed to be, at least partly, of the same age, (iii) an upper Neoproterozoic event corresponding to dacite dikes (600 ± 5 Ma), (iv) a Variscan (301 ± 7 Ma) hydrothermal event corresponding to the crystallization of muscovites related to Au-quartz veins. A polycyclic magmatism (Eburnian-Birimian, Pan-African and Variscan) is now evidenced in these two inliers of the western Anti-Atlas. The Pan-African orogeny is very homogeneous all along the Anti-Atlas during Neoproterozoic time. No inherited Archaean component has been found in zircons from granites or dikes. It appears that the northern border of the West African craton is an important juvenile cratonic limit submitted to periodical continental growth since 2.05 Ga at least.