New insights into hydrothermal vent processes in the unique shallow-submarine arc-volcano, Kolumbo (Santorini), Greece
Stephanos P. Kilias
Paraskevi Nomikou
Dimitrios Papanikolaou
Paraskevi N. Polymenakou
Athanasios Godelitsas
Ariadne Argyraki
Steven Carey
Platon Gamaletsos
Theo J. Mertzimekis
Eleni Stathopoulou
Joerg Goettlicher
Ralph Steininger
Konstantina Betzelou
Isidoros Livanos
Christos Christakis
Katherine Croff Bell
Michael Scoullos
We report on integrated geomorphological, mineralogical, geochemical and biological investigations of the
hydrothermal vent field located on the floor of the density-stratified acidic (pH , 5) crater of the Kolumbo
shallow-submarine arc-volcano, near Santorini. Kolumbo features rare geodynamic setting at convergent
boundaries, where arc-volcanism and seafloor hydrothermal activity are occurring in thinned continental
crust. Special focus is given to unique enrichments of polymetallic spires in Sb and Tl (6Hg, As, Au, Ag, Zn)
indicating a new hybrid seafloor analogue of epithermal-to-volcanic-hosted-massive-sulphide deposits.
Iron microbial-mat analyses reveal dominating ferrihydrite-type phases, and high-proportion of microbial
sequences akin to "Nitrosopumilus maritimus", a mesophilic Thaumarchaeota strain capable of
chemoautotrophic growth on hydrothermal ammonia and CO2. Our findings highlight that acidic
shallow-submarine hydrothermal vents nourish marine ecosystems in which nitrifying Archaea are
important and suggest ferrihydrite-type Fe31-(hydrated)-oxyhydroxides in associated low-temperature iron
mats are formed by anaerobic Fe21-oxidation, dependent on microbially produced nitrate.
(EN)
