Resumen

GARCIA, Yohanna K.  y  SANCHEZ, John J.. Geological contributions to the conceptual geothermal model in the region of the volcanoes Chiles - Cerro Negro (Colombia-Ecuador). bol.geol. [online]. 2019, vol.41, n.1, pp.151-171. ISSN 0120-0283.  https://doi.org/10.18273/revbol.v41nl-2019008.

A preliminary conceptual geothermal model for the Chiles-Cerro Negro Volcanic Complex (CCNVC) is refined through the addition of details related to lithology, geotechnical properties, and hydrology of the system. A total of 21 sites were visited, mostly located within the area of the Tufiño-Chiles-Cerro Negro Binational Geothermal Project. The petrography and geochemical classification were obtained for four samples using the K2O vs SiO2, SiO2 - FeO/MgO, AFM and Na2O + K2O vs SiO2 diagrams. The geotechnical classification of five sites followed the Rock Mass Rating-RMR system. Lithology varies between hard rocks (andesite and dacite lavas) and unconsolidated deposits of variable nature, including talus, till, lahars and pyroclastic flows. The geotechnical parameters of rock masses vary in the following ranges and have median values: 90 ≤ %RQD ≤ 96; 52 ≤ RMR ≤ 77; 8,89 ≤ σ cm ≤ 35,67; y -1,13 ≤ σ tm < -0,11; RQD median =92%; RMR median =69%; σ cm-median =22,87 MPa; y σ tm-median =-0,494 MPa. The porosity and permeability of the study area exhibit moderate to high values. It is concluded that the varying lithology and structures influence the regional and local permeability, which favors circulation of aqueous fluids between the recharge and discharge areas of the geothermal system.

Palabras clave : Chiles-Cerro Negro Volcanic Complex; geothermal system; conceptual geothermal model.

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