Kolumbo submarine volcano (Greece): An active window into the Aegean subduction system
Rizzo, A.L.; Caracausi, A.; Chavagnac, V.; Nomikou, P.; Polymenakou, P.N.; Mandalakis, M.; Kotoulas, G.; Magoulas, A.; Castillo, A.; Lampridou, D. (2016). Kolumbo submarine volcano (Greece): An active window into the Aegean subduction system. NPG Scientific Reports 6(28013): 9 pp. http://dx.doi.org/10.1038/srep28013 In: Scientific Reports (Nature Publishing Group). Nature Publishing Group: London. ISSN 2045-2322; e-ISSN 2045-2322, more |   |
| Authors | | Top | - Rizzo, A.L.
- Caracausi, A.
- Chavagnac, V.
- Nomikou, P.
| - Polymenakou, P.N.
- Mandalakis, M.
- Kotoulas, G., more
| - Magoulas, A.
- Castillo, A.
- Lampridou, D.
|
| Abstract | Submarine volcanism represents similar to 80% of the volcanic activity on Earth and is an important source of mantle-derived gases. These gases are of basic importance for the comprehension of mantle characteristics in areas where subaerial volcanism is missing or strongly modified by the presence of crustal/atmospheric components. Though, the study of submarine volcanism remains a challenge due to their hazardousness and sea-depth. Here, we report He-3/He-4 measurements in CO2-dominated gases discharged at 500 m below sea level from the high-temperature (similar to 220 degrees C) hydrothermal system of the Kolumbo submarine volcano (Greece), located 7 km northeast off Santorini Island in the central part of the Hellenic Volcanic Arc (HVA). We highlight that the mantle below Kolumbo and Santorini has a He-3/He-4 signature of at least 7.0 Ra (being Ra the He-3/He-4 ratio of atmospheric He equal to 1.39x10(-6)), 3 Ra units higher than actually known for gases-rocks from Santorini. This ratio is also the highest measured across the HVA and is indicative of the direct degassing of a Mid-Ocean-Ridge-Basalts (MORB)-like mantle through lithospheric faults. We finally highlight that the degassing of high-temperature fluids with a MORB-like He-3/He-4 ratio corroborates a vigorous outgassing of mantle-derived volatiles with potential hazard at the Kolumbo submarine volcano. |
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