Análisis estadístico de la composición química del vulcanismo andino cenozoico (41° -43°S)

MERODIO J.C.; BERTONE, L.M.; RAPELA, C.W.; MAZZONI, M.

COMUNICACIONES - DEPARTAMENTO DE GEOLOGIA. FACULTAD DE CIENCIAS FISICAS Y MATEMATICAS. UNIVERSIDAD DE CHILE

Universidad de Chile

Lugar: Santiago; Año: 1989 p. 69 - 81

0069-357X

The Andean region under study is characterized by development of Cenozoic volcanic belts of different ages. Early Tertiary effusion products are better represented on the eastern slope of the Andes, where two main belts are distinguished: the eastern one (Pilcaniyeu) of Paleocene-Eocene age and a western belt (El Maiten) of Oligocene age. Pleistocene to Recent strato-volcanoes predominate in the High Andes Cordillera. The application of multivariate methods (Hotelling’s T2 and Discriminant Analysis) to the mayor element chemistry of rocks of these belts, ranging in Si02 from 45 to 57°/o and in MgO from 5 to 7º/o, shows statistically significant differences between the Pleistocene— Recent and the Early Tertiary basalts and basaltic andesites. Both Ear/y Tertiary belts are, however, statistically uniform ¡ii composition. Relative to the Pleistocene —Recent basaltic rocks, the Early Tertiary ones are enriched in Na20, K20, Ti02 and P205, but depleted in CaO. These compositional differences suggest different tectomagmatic conditions during the Ear/y and Late Cenozoic times.