T82 Source to Surface Magma Thermodynamics and Transport: Interdisciplinary Approaches to Documenting the How, Where, and When of Magma Generation and Evolution during Ascent, Storage, and Eruption I

Monday, 10 October 2022
8:00 AM - 12:00 PM
502

SPATIAL AND TEMPORAL VARIATIONS OF ALKALINE MAGMATISM ON TENERIFE, CANARY ISLANDS, SPAIN: COMPARING TEPHRIPHONOLITE AND PHONOLITE EVOLUTION OF SUMMIT AND FLANK ERUPTIONS AT THE TEIDE-PICO VIEJO COMPLEX

Paper number: T82-4
Program: Technical Sessions
Time: 8:35 AM – 8:50 AM

Authors

Abstract

The 0.18 Ma Las Cañadas Caldera, which hosts the Teide-Pico Viejo Complex, Tenerife, Canary Islands is characterized by a complete range of alkali-rich lavas ranging from basanites to phonolites with lavas becoming increasingly more evolved through time. The Teide-Pico Viejo complex is located at the intersection of the northeast (Dorsal) and the northwest (Santiago Del Teide) rift systems. Alkali feldspar bearing Teide-Pico Viejo tephriphonolites and phonolites reflect different degrees of evolution, which contrasts with a phonotephrite that is less evolved and contains plagioclase. Two tephriphonolite/phonolite types are present. A less-evolved group is characterized by generally higher Ba and Sr, and a more-evolved group is characterized by lower Ba and Sr. A single phonolite and the tephriphonolite have high Ba (>1000 ppm) and Sr (>200 ppm) concentrations, while the remaining phonolite has ~45 ppm Ba and ~6 ppm Sr, which is similar to previously analyzed summit phonolites (Brown et al., 2022). Both magma types have 87Sr/86Sr ratios of ~0.7031 and 143Nd/144Nd ratios of ~0.51288 without flank or summit distinction. Flank lavas do not however exhibit any late-stage alteration effects, which have been attributed to the assimilation of altered/high Rb-Sr material or seawater causing higher 87Sr/86Sr ratios in some Teide-Pico Viejo phonolites (Brown et al., 2022). Overall, results are consistent with two variably differentiated alkaline magma reservoirs, one more-evolved (low Ba and Sr), and one less-evolved (high Ba and Sr). Both apparently generate flank and summit eruptions but likely tapped either separate magmas or separate parts of the same magma reservoir. Results allow for further investigation of spatial and temporal tephriphonolite/phonolite generation trends between edifice and flank eruptions on Tenerife.

Brown, et al., 2022, Unleashing alkali feldspar: Ra/Th ages and chemical and isotopic constraints on Holocene phonolite magmatism, Canary Islands: Geology,. https://doi.org/10.1130/G50112.1

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-383682

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