espanolEl Batolito de Acandi es un cuerpo intrusivo con amplias variaciones composicionales (Gonzalez y Londono, 2002) que data del Oligoceno (Restrepo y Toussaint, 1976), a su vez intruido por cuerpos subvolcanicos de andesitas, dacitas, y diques de basaltos. Debido a la diferencia composicional de este cuerpo en la cordillera Occidental, se realiza la integracion e interpretacion de datos del analisis petrografico, geoquimico e isotopico de muestras recolectadas en la parte norte del Golfo de Uraba entre los municipios de Acandi y Unguia en el departamento de Choco. En esta zona, las rocas del Batolito son gabros: rocas melanocraticas, masivas, equigranulares de grano fino a medio, subhedrales, de textura faneritica; y las de los cuerpos subvolcanicos y diques son: rocas leucocraticas, masivas, inequigranulares, de grano fino a medio, subhedrales, con textura porfiritica y rocas melanocraticas afaniticas (basaltos). Petrografia detallada muestra que las rocas del Batolito son compuestas por plagioclasa, piroxenos y anfiboles, como accesorios pirita diseminada, apatita, magnetita e ilmenita. Son rocas holocristalinas, melanocraticas, inequigranulares, subhedrales, de fino a groso granulares, con presencia de texturas ofiticas y subofiticas, con coronas de reaccion y zonacion en plagioclasas. Las rocas subvolcanicas que intruyen el batolito son basaltos afaniticos, dacitas y andesitas con texturas porfiriticas, con plagioclasa y hornblenda como minerales principales. Son inequigranulares, de tamano muy fino a grueso, con texturas cumuloporfiriticas, vesiculares y amigdulares. Los analisis geoquimicos e isotopicos indican que tanto las rocas del batolito como las de los cuerpos que lo intruyen, son de afinidad subalcalina de la serie calco-alcalina de bajo a medio K, metaluminosas, con enriquecimiento en elementos de tierras raras leves en relacion a las tierras raras pesadas. Los datos geoquimicos e isotopicos de Nd y Sr sugieren que estas rocas se forman a partir de procesos en arcos de islas, asociados a zonas de subduccion, siendo posteriormente acrecionadas al margen continental. EnglishThe Acandi’s batholith is a large intrusive body with a wide compositional variation (Gonzalez and Londono, 2002) dating from the Oligocene (Restrepo and Toussaint, 1976), and intruded by subvolcanic andesites and dacites bodies and basalt dikes. Due to the compositional difference of this body in the Western Cordillera, it is performed integration and interpretation of new petrographic, geochemical and isotopic data from samples collected in the northern Gulf of Uraba between the towns of Acandi and Unguia it is done in Choco department. For this area, batholith rocks are gabbros: melanocratic rocks, massive, equigranular fine to medium grained, subhedral, phaneritic texture; and the subvolcanic bodies and dikes are: leucocratic, massive and inequigranular rocks, fine to medium grained, subhedral, with sporphyritic texture and aphanitic melanocratic rocks (basalts). Detailed petrography shows that the rocks from the Batolith are constituted by plagioclase, pyroxene and amphibole, with disseminated pyrite, apatite, magnetite and ilmenite as accessory phases. The batholith rocks are holocrystalline, melanocratic, inequigranular, subhedral, from fine to granular roughly, with the presence of ophitic and subophitic textures, with reaction rings (coronas) and zoning in plagioclase. The intrusive subvolcanic rocks that crosscut the Batholith are afanitic basalts, dacites, and andesites with porphiritic textures, having plagioclase and hornblende as main minerals. They are inequigranular, very fine to coarse grained, with glomeroporphyritic texture and also vesicular and amygdular textures. Geochemical and isotopic analyses indicate that both batholiths and intrusive rocks are sub-alkaline from the calc-alkaline series of low to medium K, metaluminous with light rare earth elements enrichment in relation to the heavy rare earth elements. The geochemical and Nd and Sr isotopic data suggest that these rocks are formed in island arcs, associated with subduction zones, being later added to a continental margin.