Caracterización y datación de una unidad carbonática de edad Noriense (Fm. Zamoranos) en el Trías de la zona subbética

Resumo

The study of microfacies of the carbonate Triassic allows us to attribute a Norian age to a dominantly carbonatic formation belonging to the in Triassic germanic facies of the Subbetic Zone in the Betic Cordillera. These carbonates were formerly considered as Muschelkalk facies of Ladinian-age. The Zamoranos Formation has been subdivided in three members. The lowermost (0.25 to 1.75 m in thickness) is the "Carniolar Limestones Member", which is overlied by the "Ferruginous Detrital Member", about 1 m thick. And the uppermost member (rangin in thickness between 20 and 40 m) is "Laminated Limestones and Dolostones Member". The intermediate member is the most typical of the Zamoranos Formation due to its red colour and siliciclastic (mostly argillaceous) nature. This formation is built up by typical facies of a carbonate ramp, with well-developed intertidal facies. Preliminary palynological studies suggest a Middle Norian-age for this formation on the basis of the presence of Classopollis sp and Granulopereulatipollis rudis. Moreover, this age has been corroborated on the basis of typically Middle Norian to Upper Norian foraminifera (Earlandia tintinniformis, Glomospira ej. sinensis ... ) and coprolite (Parafavreina thoronetensis and Palaxius salataensis) assemblages. Some forms of Late Triassic characteristic bivalves (i.e. Chlamys ej. valoniensis) have been also found.