Vaca M. A., Bablon M., Andrade S. D., Hidalgo S., Quidelleur X., Vasconez F. J., Lahitte P., Samaniego Pablo, Mueller A. V. (2023). New geological and geochronological constraints on the evolution of the Cotacachi-Cuicocha volcanic complex (Ecuador). Journal of South American Earth Sciences, 128, 104489 [18 p.]. ISSN 0895-9811.
Titre du document
New geological and geochronological constraints on the evolution of the Cotacachi-Cuicocha volcanic complex (Ecuador)
Année de publication
2023
Auteurs
Vaca M. A., Bablon M., Andrade S. D., Hidalgo S., Quidelleur X., Vasconez F. J., Lahitte P., Samaniego Pablo, Mueller A. V.
Source
Journal of South American Earth Sciences, 2023,
128, 104489 [18 p.] ISSN 0895-9811
Extensive fieldwork at the Cotacachi-Cuicocha Volcanic Complex (CCVC, North of Ecuador) resulted in a new collection of geological data including cartography, chronology, petrography, geochemistry, and morphology. This volcanic complex is formed by a central volcano (Cotacachi: 4939 m asl, current bulk volume of 56 ± 4 km3), several peripheral domes, and a 3 km wide volcanic caldera (Cuicocha: 4.2 ± 0.1 km3). CCVC comprises three stratigraphic members: The first, Cotacachi Basal, represents the initial phase of construction, which started at 173 ± 4 ka with a basal andesitic lava flow succession (average 500 m-thick) including isolated basaltic-andesitic lavas (Verde Tola unit; NE: 113 ± 6 ka, SE: 133 ± 9 ka), the construction of some peripheral amphibole-bearing andesitic domes, such as Muyurcu and Loma Negra (138 ± 4 ka and <108 ka, respectively), and a debris-avalanche deposit to the north-west (0.5-1.8 km3, older than 108 ka). The second member, Upper Cotacachi, consists of an andesitic lava flow succession ( average 300 m-thick), younger than 108 ± 6 ka. A gap of activity occurred afterwards from 100 to 70 ka, during which a second debris-avalanche (0.2-1.1 km3, 108 to 65 ka) occurred to the NE, followed by the effusion of the dacitic Piribuela dome (65 ± 2 ka). Afterwards, several superimposed andesitic lava flows were emplaced at the summit, possibly around 15-10 ka since they lack glacial erosion. The third member includes the extrusion of the andesitic Cuicocha pre-caldera domes, which marks the beginning of a new eruptive stage of activity of CCVC during the Holocene, resulting in a violent eruption (3525 ± 35 to 2980 ± 30 a BP; VEI = 5) that partially destroyed the young dome and formed a funnel-shaped caldera (Cuicocha Caldera-Lake), ending with the emplacement of the Wolf and Yerovi post-caldera domes.
Plan de classement
Géologie et formations superficielles [064]
;
Géophysique interne [066]
Description Géographique
EQUATEUR
Localisation
Fonds IRD [F B010090092]
Identifiant IRD
fdi:010090092
