Vent precipitates from hydrothermal active subantarctic volcanic systems – examples from Kemp Caldera

The South Sandwich Islands (SSI) constitute an active volcanic arc situated in the Scotia Sea, which is a part of the South Atlantic Ocean. The submarine caldera west of Kemp Seamount in the southern part of the volcanic arc is of particular interest. This area is known as Kemp Caldera and has a north-south extension of about 6500 m and a rim-to-rim width of roughly 8600 m from east to west. Extinct chimneys and white smoker vent fields were found around a resurgent cone in the middle of the caldera, but are poorly imaged in the bathymetry of the seafloor. A peculiarity is the occurrence of elemental sulfur at these white smokers because this elemental sulfur, which occurs in liquid as well as fine-crystalline form, precipitates in a much less acidic environment as it is known from acid sulfate fluids.

During the research cruise PS119 in 2019, ROV dives were deployed to collect vent precipitates from the hydrothermally active sites in the Kemp Caldera. Comprehensive investigations of these samples were carried out using suitable laboratory methods including geochemical and mineralogical analysis such as XRD, optical light microscopy and SEM-EDX.

This project reveals the first mineralogical results of hydrothermal precipitates found in the Kemp Caldera during the PS119 expedition. In detail, the focus of this work is set on the specialty of the occurrence of elemental sulfur in the submarine caldera and its formation.

Contacts: Victoria Kürzinger, Gerhard Bohrmann