GEOCRONOLOGÍA Y CARACTERIZACIÓN ISOTÓPICA Sr-Nd DE LA GRANODIORITA VARVARCO, CRETÁCICO TARDÍO DE LA CORDILLERA DEL VIENTO, NEUQUÉN, ARGENTINA: COMPARACIÓN ENTRE LOS CICLOS GONDWANICO E ANDINO

ASSIS, S.; GALLASTEGUI, G.; HUASER, N.; ZAFFARANA, C.B.; ORTS, D.

Córdoba

Congreso; XIII Congreso de Mineralogía, Petrología Ígnea y Metamórfica, y Metalogenia; 2019

AGA entre otras

The Cordillera del Viento in Neuquén province represents an eroded anticline that exposes rocks from the Neuquén Basin. The cordillera is affected by two orogenic cycles with crust reworked during the Gondwanic and Andean orogenic cycles. This work is oriented to characterize the magmatic styles of both cycles through isotopes Sr-Nd, by particular investigation of the Huingancó and Varvarco plutons that are representative of these cycles. The Huingancó Granite (~259 Ma) consists of granodiorites and monzogranites with ƐHf between 0 and -2. The Varvarco Granodiorite (~67 Ma) consists of granodiorites and tonalites with porphyritic and mingling textures. The isotopic data in hand show an initial 87Sr/86Sr ratio of 0.70455, an ƐNd of -0.8, and a TDM of 0.8 Ga for the Varvarco Granodiorite and a more radiogenic 87Sr/86Sr ratio of 0.70706, an ƐNd more negative than -4.6, and a TDM of 1.2 Ga for the Huingancó Granite. The magmas produced in the Gondwanic cycle would have assimilated abundant crustal material, whereas the source of the magmas of the Andean cycle show reworking of Neoproterozoic crust and mixture of basic magmas and acid magmas.