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 Volume 1 Chapter 10

Chapter 10

Fragments of a Permian Arc on the Western Margin of the Neoproterozoic Basement of Colombia

By Gabriel RODRÍGUEZ–GARCÍA, Ana María CORREA–MARTÍNEZ, Juan Pablo ZAPATA–VILLADA and Gloria OBANDO–ERAZO

Pages 204–245

Manuscript accepted October 29, 2018


Abstract 


New petrographic, whole–rock geochemical and U–Pb–zircon geochronologic data combined with data from previous studies enabled identification of a fragmented Permian magmatic arc with ages ranging from 294 to 260 Ma in the Colombian Andes. The arc is exposed along the southeastern slope of the Central Cordillera towards the Upper Magdalena Valley (UMV), San Lucas range (SLR) and Sierra Nevada de Santa Marta (SNSM). The arc fragments consist of plutons on the western margin of the Neoproterozoic basement and show wide lithological variation in both igneous (monzodiorites, quartz monzonites, tonalites, granodiorites, monzogranites, and syenogranites) and metamorphic (migmatites, gneisses and mylonitic gneisses) rocks. The granites have a metaluminous to peraluminous character and correspond to calc–alkaline to high–potassium calc–alkaline series formed in a continental arc environment. Some bodies are associated with metamorphic rocks (the La Plata Granite and Icarco Complex), which may correspond to the roots of the arc, and others show superimposed dynamic metamorphism (the Nechí Gneiss and El Encanto Orthogneiss). The Permian plutons, unidentified in previous studies because of their lithological similarities to the large volume of magmatism that occurred during the Early to Middle Jurassic, are dispersed along with the Neoproterozoic basement. The Permian magmatism that intruded the basement of the northern Andes possibly originated in a subduction zone located on the western margin of Gondwana.

Keywords:   geochemistry, UPb geochronology, Colombian Andes, igneous, metamorphic rocks.