Northeastern extension of Neogene magmatism in Africa: Evidence from the Zitouna rhyolite, Algeria

Abstract

espanolLa riolita de Zitouna es la representacion mas oriental del magmatismo neogeno en el noreste de Argelia. Esta formada por dos cuerpos intrusivos rioliticos: el primer afloramiento es vagamente conocido y no ha sido datado; el segundo es de mayores dimensiones y no ha sido descrito previamente. Se trata de una roca bien diferenciada que no excede de los 12 Ma (Post-Serravaliense). Los datos geoquimicos muestran que corresponde a un granito de tipo S con alto caracter peraluminico, lo que corrobora un protolito cortical. La riolita de Zitouna es considerada como la continuacion de otros episodios magmaticos vecinos y puede ser relacionada con la evolucion tectono-magmatica del noreste africano durante el Neogeno superior. EnglishThe Zitouna rhyolite is the easternmost representative of the Neogene magmatism in the Northeast of Algeria. It is composed of two intrusive rhyolitic apexes: the first outcrop is poorly known and not dated; the second one is greater, and not previously described. It is a well-differentiated rock that does not exceed 12 Ma (Post-Serravallian). Geochemical data show that it belongs to S-type granites with a high peraluminous character corroborating a crustal protolith. The Zitouna rhyolite is considered as the continuation of other neighbouring magmatic episodes and can be related to the late Neogene tectono-magmatic evolution of northeast Africa.Keywords: rhyolite, post-Serravallian, S-type granites, peraluminous, Zitouna, Algeria.