Amphibolite facies metamorphic event within the Upper Sebtides tectonic units (Internal Rif, Morocco): a record of a hyperextended margin at the border of the western Tethys

Located at the westernmost tip of Mediterranean, Gibraltar Arc is a segment Alpine belt that exhibits peridotite massifs associated with high-grade crustal metamorphic units. The timing and mechanisms exhumation these crust–mantle associations are still debated in Rif Morocco as well Betic Cordilleras Spain. A structural, petrographic, geochronological study ( 40 Ar– 39 Ar method) performed Beni Bousera region (Internal Rif) on Upper Sebtides units consist Paleozoic basement Permo-Triassic metasedimentary rocks. We point out that, metagreywackes, an early assemblage K-feldspar, plagioclase, quartz, muscovite, biotite, garnet, which diagnostic amphibolite facies metamorphism. By dating white mica porphyroclasts from this assemblage, we provide first evidence internal metamorphism Triassic age. assume belong to ancient continental margin Western Tethys, thus, interpret event framework hyperextended coeval subcontinental mantle during Triassic. Afterward, underwent greenschist Lower Miocene due thermal related back-arc opening Alboran Basin.