DIFFUSE EMISSION OF CARBON-DIOXIDE, METHANE, AND HE-3 FROM TEIDE VOLCANO, TENERIFE, CANARY-ISLANDS

Diffuse emission of CO2, CH4 and He-3 was investigated In the summit c rater of Teide volcano, Tenerife. Canary Islands. The results indicate that Teide volcano releases abundant CO2 not only from its active cra ter, but also from its flanks as diffuse soil emanations. The spatial distribution of these emanations correlates quite closely with that of geothermal anomalies and manifestations. Our flux measurements indica te a total output of 380 ton.day(-1) of CO2 and 1.6 ton.day(-1) of CH4 by diffuse degassing. From the He-3/CO2 ratios and the CO2 flux we es timate a diffuse He-3 flux of 0.052 mol.year(-1). Isotopic analysis of carbon in soil gas samples from sites of high soil CO2 flux indicates a magmatic origin for the CO2, also reported by high He-3/He-4 ratios of 5.50 and 5.87 Ra. The origin of methane is more uncertain with low delta(13)C values suggesting a biogenic contribution.