EDAD Y COMPOSICIÓN DE LOS BASALTOS DE MESETA DE LA SIERRA PIRE MAHUIDA, PROVINCIA DEL CHUBUT

SALANI, F. M.; PARICA, C. A.

Cordoba

Congreso; XIII CONGRESO DE MINERALOGÍA, PETROLOGÍA ÍGNEA Y METAMÓRFICA, Y METALOGÉNESIS; 2019

Asociación Mineralogica Argentina

Age and composition of the Sierra Pire Mahuida Basaltic Plateau. The Pire Mahuida basalts which form the sierra plateau (SW of the Somún Curá plateau) lie over Miocene acid rocks with NW-SE orientation and 35 m thickness. They are porphyritic basalts composed of olivine, plagioclase, clinopyroxene, apatite and ilmenite, with frequent xenolitic orthopyroxenes. Chemically they correspond to alkaline basalts with trace elements and rare earth compositions similar to oceanic islands basalts. Up to the present the age was attributed on the basis of stratigraphic relationships with the acid volcanites of the Pire Mahuida Volcanic Complex. The performed analytical determination (17 ± 1 Ma) indicates a lower Miocene, Burdigalian age, very close to the effusion age of the acidic rocks. The obtainedage is coherent with other Somún Curá Plateau basaltic events.