Restoration of new volcanic gas analyses from basalts of the afar region: Further evidence of CO2 -degassing trends

The restored compositions for approximately 70 new analyses reported recently for Erta'Alelava lake (LeGuern et al., 1979) are in good agreement with restored compositions (Gerlach, 1980a) based on previously published data. The results confirm earlier indications that gas collections taken at different times from the lava lake are related principally by variations in CO₂ content. Restored compositions for gas samples collected in the final stages of a November 1978 Ardoukoba eruption along the Asal Rift spreading axis resemble the Erta'Ale gases except for a much lower CO₂ content. The Ardoukoba gases fall close to a CO₂-decreasing control line for gases with initial compositions similar to the 1971–1973 Erta'Ale gases. These results suggest that gases released from basaltic lava along zones of crustal spreading follow compositional trends dominated by changes in CO₂ content.