Abstract

ZAPATA GARCIA, Gilberto  and  RODRIGUEZ GARCIA, Gabriel. PETROGRAPHY, GEOCHEMISTRY AND AGE OF THE FARALLONES GRANODIORITE AND ASSOCIATED VOLCANIC ROCKS. bol.geol. [online]. 2013, vol.35, n.1, pp.81-96. ISSN 0120-0283.

The Farallones Granodiorite is located on the western flank of the Cordillera Occidental of Colombia, is formed by tonalite, granodiorite, quarz diorite, monzodiorite, quarz monzodiorite, diorite, gabbro and quarz monzonite. The content of silica in the rocks varies between 67.76 and 52,07%, the body is not homogeneous and there are alkaline rocks in the southern part of the body and subalcalines in the northern sector of the pluton. There are rich rocks K2O ranging from medium K to shoshonitic series, they are metaluminous but near the edges of the pluton they are peraluminous due to contamination by sediments. The Farallones Granodiorite correspond to midly evolved magmas with impoverishment of HREE8 respect to LREE, that correspond to a pluton formed in an arc enviroment. The age of the Farallones Granodiorite in hornblende for the method K/Ar 11± 2 Ma (Calle et al., 1980a) and two in Arboleda et al. (2009) by the method Ar/Ar 11.9 and 9. 8± 0.2, which correspond to the Late Miocene. This geological unit intrudes the Sandstones, siltstones and mudstones of Penderisco, and in turn, it is intruded by the diatremic brecchas of Farallones.

Keywords : Farallones Granodiorite; Cordillera Occidental of Colombia; Farallones diatremic breccia.

        · abstract in Spanish     · text in Spanish     · Spanish ( pdf )