Geochemical And Geothermal Constraints On Magma Bodies Associated With Historic Activity, Tenerife (Canary Islands)

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Journal Article: Geochemical And Geothermal Constraints On Magma Bodies Associated With Historic Activity, Tenerife (Canary Islands)

Abstract
The present morphostructure of the island of Tenerife is to a great extent conditioned by the large central structure of the Teide (3717 m), constructed on a large caldera with a collapse 17 km in diameter and whose base is located some 2000 m above sea-level. Nevertheless, in addition to this central system with current fumarolic activity, there have been a series of isolated historic eruptions on the island whose structures are aligned with two main tectonic direction lines which delimit the caldera: NE - SW and NW - SE. Groundwater is collected on the island for human and agricultural supply by way of horizontal galleries of lengths generally between 1000 and 5000 m which radially penetrate the large central structure. The frequent anomalies of temperature (up to 45°C), chemical composition (SiO2, B, NH4+, SO42-, CO3H-) and high gas contents (CO2, H2) detected in these galleries, which are located between the base of the caldera (2000 m) and sea level, enable us to evaluate, from a geochemical point of view, the current residual volcanic emanations of the island. It is concluded that these are generated at around 300°C and that they interfere with the basal aquifers of the island at 130-150°C, leading to the said anomalies. Processes are graded by height, and so the highest galleries (~ 1500 - 1800 m) which are rich in CO2 give rise to considerable carbonate deposits by the interaction at 25-40°C of the gas with the water of the upper perched aquifers. The flow of gases necessary to maintain this activity is around 175-1725 kg/m2 per day in each anomalous zone, which coincide with the sites of the historic volcanoes.

Authors 
A. Valentin, J. F. Albert-Beltran and J. L. Diez








Published Journal 
Journal of Volcanology and Geothermal Research, 1990





DOI 
Not Provided
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Citation

A. Valentin,J. F. Albert-Beltran,J. L. Diez. 1990. Geochemical And Geothermal Constraints On Magma Bodies Associated With Historic Activity, Tenerife (Canary Islands). Journal of Volcanology and Geothermal Research. (!) .