The upper Pleistocene (1.8–0.7 Ma) explosive eruptive history of Las Cañadas, ocean-island volcano, Tenerife
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2023-04
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Journal Article
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Abstract
While most ocean-island volcanism is effusive, recent evidence has demonstrated that intraplate ocean island volcanoes can exhibit protracted explosive histories, with catastrophic eruption styles and hazardous behaviour more typically associated with volcanoes in continental and plate-margin settings. Tenerife is the largest explosive ocean-island volcano on Earth, with a prolonged (∼2 Ma) post-erosional history of caldera-forming, plinian and ignimbrite eruptions of evolved composition. The 0.7–1.8 Ma succession with 20 newly defined formations is reported for southern Tenerife, Canary Islands. In the last 2 Myr, the Las Cañadas volcano has produced >42 pumice-fall eruptions, 21 with extensive ignimbrites, and 12 inferred caldera collapse events. Pyroclastic density currents have repeatedly travelled more than15 km from source to the ocean, filling valleys and burying extensive interfluves. A robust whole-rock chemistry dataset, selected mineral chemistry, coupled with new 40Ar/39Ar ages of units through the pyroclastic stratigraphy, allow recognition of magmatic trends within the system on the order of 100 ky. The catastrophic explosive eruptions form three, 0.2–0.5 Myr-duration clusters (the Ucanca, Guajara and Diego-Hernandez) that do not appear to correspond simply with geochemical cycles, or to cycles of increasing eruption size or explosivity as has been previously proposed. During the clusters, large eruption frequencies averaged 1 every 20–45 kyrs. The eruption clusters were separated by hiatuses of ∼240–260 kyr, recorded by soils and unconformities, and may reflect marked changes in geographic dispersals following giant landslide breaches in Las Cañadas caldera wall. Two concurrent evolutionary magmatic trends are distinguished: one producing crystal-rich magmas, the other formed the cooler crystal-poor magmas: both spanned over a million years until 0.66 Ma, when the former ceased.
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published
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Volume
436
Pages / Article No.
107777
Publisher
Elsevier
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Subject
Pyroclastic stratigraphy; Phonolitic rocks; Caldera collapse; Ignimbrite; 40Ar/39Ar dating