A submerged volcanic cone in Deception Island (Antarctica) ¿Benthic communities and proximal volcanism in a rapidly changing sedimentological environment

Scientific Committee on Antarctic Research (SCAR) Online Conference, August 5, 2020Deception Island (DI) is amongst the most active volcanoes, with >20 explosive eruptions in the last two centuries. DI¿s caldera-forming eruption, a volcano-climatic event with hemispheric impact occurred 3980 ± 125c.y. before present, is the largest eruption documented in Antarctica during Holocene. Mortality of benthic organisms occurredby eruptions in 1967, 1969, 1970, with very low abundances from 1967-1973. Volcanic activity post-caldera-forming comprises many scattered eruptive vents across the island. A submarine volcanic axis with several volcanic cones is observed within the caldera, and volcanic edifices, morphologically well-preserved in the southern part of the bay raise from the seafloor up to >50 m. A multidisciplinary team sampled one of the submerged volcanoes, Stanley Patch (SP), in Port Foster (PF). Geophysical data allocated the volcano and characterized its morphology and inner structure. Direct sampling by SCUBA provided sediment and rocks, and photographs/video images of benthic organisms and landscape. Morphology of SP cone and textural characteristics of pyroclastic rocks (vesiculation, bubble shape) indicate an explosive volcanism origin, and fits with the post-caldera magmatic trend. A sediment core from the crater (4 cm Ø, 8 cm length) was collected for sedimentological, geochemical and geochronological analysis. Antarctic climate and seasonal sea ice, together with organic degradation due to high sedimentation rates, explain low TOC data. SP, and the whole PF, provide a unique, great natural laboratory for benchmarking the reestablishment of benthic communities on avolcanological-influenced shallow marine environment, offering relevant data for future studies evaluating global change effects on Antarctic seabed.Thanks are duet o the crew of B.A.E.Gabrielde Castilla for their logistic support during the Antarctic expedition.This is a contribution to the Ant Eco(State of the Antarctic Ecosystem) SCAR Programme.This research was partially supported by the research projects:BLUEBIO(CTM2016-78901-ANT),POSVOLDEC(CTM2016-79617-P)(AEI/FEDER-UE),and CRONOANTAR (CTM2016-77878-P