Post-caldera evolution of Deception Island (Bransfield Strait, Antarctica) over Holocene timescales

The study of palaeoclimatic changes in fast warming regions can contribute to the understanding of the forcing mechanisms responsible for the global changes that are presently happening. Deception is an active volcanic island in the Bransfield basin that has a complex history strongly influenced by both magmatic and tectonic processes. However, without accurate information on the distribution of melt, depth of sediments and Holocene timescales of its volcanic eruptions, the models for the post-caldera evolution of Deception Island are poorly constrained. Although this region has undergone severe environmental changes due to recent eruptions, hindering the location of potential study areas of paleo-volcanic eruptions, it is still possible to reconstruct post-caldera evolution at a local scale. Employing analyses such as radiocarbon dating, stable carbon and nitrogen isotopic compositions and particle-size distributions in subsoil horizons, we have studied the coastal areas of Whalers Bay and between Wensleydale Beacon and Cross Hill to identify the major periods of alluvial sedimentation on Deception Island. Whalers Bay was influenced by a large amount of moving water generated by ice melting. The coastal location of both sampling sites contributes to preserve the sedimentation history in their soil profiles, despite the severe environmental changes due to recent eruptions. Our findings indicate that from approximately 13 to 5 cal kyr BP, the accumulation of organic matter was stable and the landforms were not altered. After that time, post-caldera eruptions occurred, melting the glacier and, consequently, flooding surficial soil layers with mud. These changes are consistent with old 14C ages for subsoil organic matter and, therefore, with the occurrence of intense cryogenic disturbance processes.