The Pre-Pan-African rifting of Saghro (Anti-Atlas, Morocco): example of the middle Neoproterozoic Basin of Boumalne

Bulletin - Societie Geologique de France - Tập 173 Số 1 - Trang 25-35 - 2002
Abdelilah Fekkak1, André Pouclet2, Lakhlifi Badra3
1Faculté des sciences, Université Chouaïb Doukkali, B.P. 20, 24 000 El Jadida, Maroc
2ISTO-UMR 6113, Faculté des sciences, Université d’Orléans, B.P. 6759, 45067 Orléans cedex 2, France
3Faculté des sciences, Université Moulay Ismaïl, B.P. 4010, Meknès, Maroc

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Abstract In the Anti-Atlas, the Boumalne basin includes 3,000 m of Middle Neoproterozoic sediments. It consists of turbiditic deposits folded during the major Pan-African event ca 685 Ma. A syn-sedimentary basaltic pile of lava flows is interbedded in the upper part of the lower formation. These lavas show an initial rift tholeiite (IRT) chemical signature. Petrographical analysis of sediments and typology of detrital zircons indicate a continental margin sedimentation, without any volcano-sedimentary supply from a close volcanic arc. It is concluded that the Boumalne Basin formed in a continental passive margin evolving from an intracontinental rift. This interpretation differs clearly from that of a back-arc basin which is commonly accepted. Hence, the opening of this basin is related to the pre-Pan-African Saghro rift synchronous to the Central Anti-Atlas oceanization, and not to the demise of this oceanic domain along an active margin.

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Bulletin - Societie Geologique de France

Tập 173 Số 1

25-35

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