Abstract

RODRIGUEZ-GARCIA, Gabriel  and  SABRICA, Carlos. Redefinition of La Cocha-Río Téllez Migmatitic Complex, based on new field data, petrography, lithogeochemistry, and geochronology. Bol. cienc. tierra [online]. 2023, n.54, pp.7-26.  Epub Mar 15, 2024. ISSN 0120-3630.  https://doi.org/10.15446/rbct.n54.108075.

The La Cocha-Río Téllez Migmatitic Complex is located on the eastern flank of the Colombian Andes, between the departments of Nariño and Putumayo. It crops out as windows between recent volcanic and fluvio-volcanic deposits. Under the name of La Cocha-Río Téllez Migmatitic Complex, granitoids, quartz-feldspar-moscovite and biotite gneisses, tonalites, mylonitic metatonalites and migmatitic amphibolites of different age and geological environment were grouped. According to our results, in this contribution we propose to stop using the name La Cocha-Río Téllez Migmatitic Complex and henceforth use the formal names of five units that represent different metamorphic and igneous events, formed between the Devonian (?) and Oligocene, which we propose to call as follows: the Sibundoy Gneiss to the unit with metamorphism ages between 365.97 ± 12.8 Ma and 386.78 ± 15.9 Ma, the San Francisco Schists with ages around 163 Ma, the Motilón Granodiorite to the pluton with crystallization ages between 172. 7±1.4 and 152.2 ± 0.31 Ma, the Alisales Tonalite to the pluton with crystallization ages of 32.4 ± 0.58 Ma, and the Tellez River Amphibolites to the unit with metamorphism ages of 80.4 ± 1.5 Ma.

Keywords : Colombia; geochemistry; U-Pb ages.

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