Bathymetric constraints on the tectonic and volcanic evolution of Deception Island Volcano, South Shetland Islands

Deception Island is the largest volcano in the actively extending Bransfield Basin, a marginal basin situated behind the extinct South Shetland Islands arc. Deception Island has been well studied but its submerged flanks have not. A multibeam bathymetry survey was conducted around the island in 2005. Data from the flooded caldera show no evidence for recent localized resurgence. The gently-sloped bottom of the caldera basin is consistent with either a broad zone of resurgence on its east side associated with trap door deformation or with higher rates of sediment supply from the east side of the island. Around the island, numerous tectonic and volcanic features on the volcano's east and west flanks are nearly all aligned with the regional strike (similar to 060 degrees) of the Bransfield rift and there is very little evidence for the other fault populations that have been identified on the island. We infer that models that link the ongoing tectonic development of Deception Island to complex regional tectonics are less likely than models in which the dominant regional extension in Bransfield Strait is modulated by the local effects of caldera. collapse and possibly a small right-lateral transfer zone offsetting the primary extension axes in the Central and Western Bransfield Basins.