Preliminary estimate of CO2 output from Pantelleria Island volcano (Sicily, Italy): evidence of active mantle degassing

Total CO2 output from fumaroles, bubbling and water dissolved gases and soi l gases was investigated at Pantelleria Island volcano, Italy. The prelimin ary results indicate an overall output of 0.39 Mt a(-1) of CO2 from the isl and. The main contribution to the total output was from diffuse soil degass ing (about 0.32 Mt a(-1)), followed by dissolved CO2 (0.034 Mt a(-1)), focu ssed soil degassing (0.028 Mt a(-1)) and bubbling CO2 (0.013 Mt a(-1)). The contribution of CO2 from fumarole gases was found to be negligible(1.4x10( -6) Mt a(-1)). Carbon-13 values for CO2 coupled with those for associated H e in gases from fumaroles and sites of focussed soil degassing clearly rule out any significant organic CO2 component and suggest a common mantle orig in for these gas species. The inferred mantle source beneath Pantelleria wo uld seem to have peculiar geochemical characteristics, quite distinct from those of mantle producing MORE but compatible with those of magmatic source s of central Mediterranean and central European volcanoes. These findings i ndicate that the Pantelleria volcanic complex is a site of active mantle de gassing that is worthy of attention for future geochemical surveillance of the island. (C) 2001 Elsevier Science Ltd. All rights reserved.