Timing of Quaternary volcanism and its relationship with tectonics in the central segment of the Ecuadorian Andes

Blossoming of the Pleistocene volcanism in the Ecuadorian Andes: a review based on new and recent geochronological data

“…Twelve samples were carefully selected for radiometric dating after thin-section examination (photographs available on Appendix A). We used the K-Ar dating method applying the unspiked Cassignol-Gillot technique (Gillot et al, 2006), which was previously successfully applied to the Ecuadorian volcanic arc (Alvarado et al, 2014;Bablon et al, 2018Bablon et al, , 2019Bablon et al, , 2020bSantamaría et al, 2022Santamaría et al, , 2023, as well as to subduction and hotspot volcanism worldwide (e.g., Grosse et al, 2018Grosse et al, , 2020Hildenbrand et al, 2018;Dibacto et al, 2020). The Cassignol-Gillot technique is particularly suitable for dating volcanic rocks with low radiogenic argon ( 40 Ar*) contents diluted in 40 Ar derived from the atmosphere, such as young Low-K lavas encountered in the Ecuadorian arc.…”

“…Considering the available data, it is highly plausible that the eruptive history of most of these poorly studied volcanoes occurred during this stage, i.e., in the last ~ 600 ka. As the eruptive histories of the Ibarra, Machachi, Latacunga, Ambato, and Riobamba segments were presented in details elsewhere (Bablon et al, , 2020aSantamaría et al, 2023), we only detail here the eruptive history of the Quito segment.…”

“…Their activity resulted in the formation of thick volcaniclastic sequences over which heavily populated areas are presently located, including the capital of Ecuador, Quito (Hall and Mothes, 2008b). Several authors also pointed out a possible link between the spatial distribution of volcanism and its geochemical variability, in relation to the subduction of the Carnegie Ridge, crustal tectonics, and the slab geometry (e.g., Litherland and Aspden, 1992; Barberi et al, 1988;Gutscher et al, 1999;Samaniego et al, 2002Samaniego et al, , 2005 Recently, several geochronological studies shade light on the development of ancient volcanism with emphasis on the southern termination of the arc, and its central and northern segments (e.g., Bablon et al, 2019Bablon et al, , 2020aSantamaría et al, 2023). In this work, in addition to compiling radiometric ages at the arc scale, we especially focus on the central zone of the arc, which has a relatively limited number of dated volcanic complexes.…”