U-Pb LA-ICP-MS GEOCHRONOLOGY AND GEOCHEMISTRY OF JURASSIC VOLCANIC AND PLUTONIC ROCKS FROM THE PUTUMAYO REGION (SOUTHERN COLOMBIA): TECTONIC SETTING AND REGIONAL CORRELATIONS

Abstract

New field data, geochemical analyses and zircon U-Pb LA-ICP MS data were obtained on plutonic and volcanic rocks of the Mocoa Batholith and Saldaña Formation in southern Colombia Putumayo region. Results suggest that the plutonic and volcanic activities are closely related to a common magmatic history. This volcano-plutonic association presents a well-defined LILE and LREE enrichment and negative Nb and Ti negative anomalies characteristic of continental magmatic arcs. Volcanic and plutonic rocks crystallized between 180-186 Ma as revealed by U-Pb zircon geochronology. The magmatic activity is temporally and chemically correlatable with other magmatic arc exposures in Colombia and Ecuador. These units may represent the remnants of a single belt which includes several units from 4°N in Colombia and 5°S in Ecuador. This arc is related to the widespread Jurassic continental magmatic arc setting that characterized the continental margins of the Americas after Pangea break-up.