Abstract

GARCIA-RAMIREZ, Carlos Alberto; RIOS-REYES, Carlos Alberto; CASTELLANOS-ALARCON, Oscar Mauricio  and  MANTILLA-FIGUEROA, Luis Carlos. PETROLOGY, GEOCHEMISTRY AND GEOCHRONOLOGY OF THE ARQUÍA COMPLEX´S METABASITES AT THE PIJAO-GÉNOVA SECTOR, CENTRAL CORDILLERA, COLOMBIAN ANDES. bol.geol. [online]. 2017, vol.39, n.1, pp.105-126. ISSN 0120-0283.  https://doi.org/10.18273/revbol.v39n1-2017005.

Metabasites belonging to the Arquía Complex and outcropping along the Pijao-Génova strip (western edge of the Central Cordillera of the Colombian Andes) consist of chlorite schists, actinolite schists with and without garnet, amphibolites, garnet-amphibolites, eclogites and metabasalts. Some bodies of serpentinized peridotites are observed along with metabasites. Both rock types are confined to the tectonic block bordered by the Cauca-Almaguer and Silvia-Pijao fault systems and their satellite faults. Metabasites were affected by a regional metamorphism, reaching their peak of metamorphism at the amphibolite facies. The Rare Earth Elements (REEs) (normalized to the C1 chondrite) from the studied rocks show a Light REEs depletion and a flat or no-fractionated Heavy REEs patterns. The metabasites´ REEs patterns, along with their La/Sm ratio < 0.6 and positive Nb, Ta and Ti anomalies, may suggest their protoliths are MORBtype related. The lithologic association between metabasites, few metapelites and deformed ultramafic rocks suggest that the rocks of the Complex Arquía can represent remnants of an ophiolite sequence of N-MORB type series. The whole rock-garnet Lu-Hf geochronology from metabasites yield an age of 128.7±3.5 Ma. This age has been interpreted as the age at which these rocks reached the eclogite facies, which in turn coincides with the roll-back process of the subducted ocean lithosphere and the Quebradagrande magmatic arc formation

Keywords : Petrology; metabasites; Arquía Complex; Cordillera Central; Colombia.

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