标题：The Oued Dayr Formation: first evidence of a new Miocene late-orogenic cycle on the Ghomaride complex (Internal Domains of the Rifian Maghrebian Chain, Morocco)
摘要：This work deals with the first evidence in the Rifian Maghrebids of a Miocene clastic succession, named Oued Dayr Fm, uncorformably resting on the Ghomaride Complex. The formation starts with polymictic conglomerates, consisting of clasts coming from all the Rifian Internal Units, sharply or gradationally evolving to graded and stratified calcareous sandstones, siltstones and massive marls. The occurrence of nannofossils starting from the NN5 Biozone of Martini indicates an age no older than middle Langhian. However, considering the possible reworking of taxa and the regional framework, the possibility of a younger age cannot be excluded. The sedimentary evolution points out a subsidence rate exceeding the detritic supply, within a thrust-top basin originated during an extensional tectonic phase, affecting the exhumed internal nappe stack. The Oued Dayr Fm constitutes the first evidence of a new Miocene late-orogenic sedimentary cycle resting on the Rifian Internal Units, intermediate between the Burdigalian Oued Gharraq-Sidi Abdeslam cycle and the Pliocene deposits. In a regional framework, no middle Miocene unconformable deposits are known on the Internal Units of both the Betic Cordillera and Maghrebian Chain, while Tortonian deposits everywhere occur. A Tortonian age, therefore, can be suggested for the Oued Dayr Fm, but data demonstrating this hypothesis at present are lacking.
