Geochemical and geochronological constraints on the origin and emplacement of the Jbel n’Habab magmatic formations, Saghro Massif, Eastern Anti-Atlas, Morocco
Journal of African Earth Sciences, cilt.242, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 242
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.jafrearsci.2026.106259
- Dergi Adı: Journal of African Earth Sciences
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Geobase, INSPEC, Zoological Record
- Anahtar Kelimeler: Eastern Anti-Atlas, Ediacaran, High-K calc-alkaline magmatism, Imiter, Jbel n’Habab, Pan-African, Post-collisional setting
- İstanbul Üniversitesi-Cerrahpaşa Adresli: Evet
Özet
The Jbel n’Habab, located south of the Imiter inlier and north of the Saghro Massif in the eastern Anti-Atlas, represents a key area for reconstructing the magmatic evolution at the end of the Neoproterozoic. This study is based on an integrated approach combining field geological observations, petrographic analyses, geochemical data, and U–Pb zircon dating. Petrographic and geochemical data reveal the presence of two main magmatic complexes: (i) granitoids and their volcanic equivalents, showing a high-K calc-alkaline affinity and a highly evolved composition ranging from intermediate to acidic facies, represented by monzodiorites, quartz diorites, granodiorites, and granites, together with volcanic rocks such as andesites, dacites, and rhyolites; and (ii) a tholeiitic suite corresponding to late microgabbroic dykes and basaltic-andesitic flows. The geochemical trends of the high-K calc-alkaline rocks indicate pronounced fractional crystallization and progressive contamination by continental crustal material. Their rare earth element (REE) patterns show enrichment in LREEs (LaN/LuN: 4.5 to 19.5). The multi-element plot shows negative Eu, Nb, and Ta anomalies. In contrast, the mafic dykes display relatively flat REE patterns with a slight negative Nb anomaly (LaN/LuN: 1.32 to 2.78). U–Pb zircon dating of the Jbel n’Habab granodiorite and rhyolite yielded ages of 545 ± 2.9 Ma and 534 ± 2.7 Ma, respectively. The presence of younger zircons in the rhyolite, dated around 462.7 ± 6.8 Ma, suggests later tectono-thermal reactivations, probably related to hydrothermal circulation or crustal adjustments. Altogether, the geochemical and geochronological data indicate the emplacement of a high-K calc-alkaline magmatism in a post-collisional setting, with a typical volcanic-arc signature developed in a subduction-related context. This implies that the Pan-African orogenic activity persisted until the Ediacaran–Cambrian boundary. The late mafic dykes, displaying an intraplate tholeiitic signature, are associated with Cambrian intracontinental rifting linked to the opening of the Rheic Ocean.