LOS CUERPOS ÍGNEOS NEÓGENOS DEL CERRO DE LAS MINAS (35.3° LS ? 69.9° LO), CORDILLERA PRINCIPAL DE LOS ANDES, SO DE MENDOZA: GEOLOGÍA, PETROGRAFÍA Y GEOQUÍMICA

JOSEFINA PONS; FRANCHINI, MARTA; LEOPOLDO LÓPEZ-ESCOBAR

Revista de la Asociación Geológica Argentina

Asociación Geológica Argentina

Lugar: Buenos Aires; Año: 2007 vol. 62 p. 267 - 282

0004-4822

The Cerro de las Minas (35.3°LS ? 69.9° LW) consists of four epizonal igneous units: diorite-tonalite, granodiorite and granite plutons and andesite dikes and sills. These units are part of the Neogene magmatic arc of SW Mendoza. They intrude the Jurassic Puchenque and Auquilco sedimentary formations. Near the contacts with plutons, these sedimentary rocks are altered to biotite and pyroxene hornfels, recrystallized limestones and superposed banded Fe-skarns. Geochemically, they are cogenetic plutons with a wide compositional range. They are metaluminous, subalkaline with calc-alkaline affinity, similar to I- type plutons, like other plutons, from convergent margins, associated with Fe skarns. They evolved through a fractional crystallization process involving their main mineral components, pl + px + amph + mt + (Fe-Ti) oxides, mingling between the diorite and granodiorite magmas. Their incompatible trace elements and REE patterns are similar to those of ingenous rocks a) from the Neogene volcano-plutonic arc (Andesita Huincán), b) associated with Fe skarns of SW Mendoza (Hierro Indio and El Kaiser), c) of the Cerro Nevazón, from the Paleogene volcano-plutonic Arc of NW Neuquén, and c) from the Andean Quaternary volcanic rocks of the TSVZ (34.5°-37° SL), such as Planchón-Peteroa ( 35.2 º S) and Nevados de Chillán (36.9º S), volcanic groups, wich are emplaced on a relatively thin continental crust (35-50 m). This suggests that the parental magma of the Cerro de las Minas rocks are calc-alkaline and metaluminous and derived from primary magmas generated in a similar mantle source, with little or no residual garnet.