Paphsanias Volcano (Ägäis), 2017 – FS Poseidon – Cruise POS512

The next morning, the diving robot PHOCA was deployed on the southern flank of volcano 2 and here, too, lava flows appeared, some of them quite young, but also sediment-covered. During this dive 15 samples were collected, apparently ranging from basaltic to andesitic composition. The basaltic lavas occur as relatively young lava flows on sediments and contain olivine. Although the volcanic structures are small, they exhibit complex magmatic evolution and apparently some of the magmas are quite different from those on the Methana Peninsula, where basaltic lavas do not occur. A subsequent dive on the northern flank of volcano 2 yielded an additional 6 lava samples of presumably andesitic composition, so volcano 2 was also very well sampled. During the following night, the Epidavros Basin was further mapped and on the morning of April 29, the Poseidon steamed to the small port of Pachi on the northern edge of the Saronic Gulf to receive spare parts for the diving robot. In the afternoon, a dive was made on the northern flank of Volcano 3, which appears to be the oldest structure to date. Thick sediments cover the lower part of this lava flow and the rock outcrops that appear are covered with carbonate crusts of red algae and serpels. Therefore, only four lava samples could be taken, as well as some samples of the carbonate crusts. This was followed by continued mapping in the Epidavros Basin and on April 30 dives on volcanoes 4 and 5 and again on the SW flank of volcano 3. These structures are all relatively old compared to volcanoes 1 and 2 and we were only able to recover three lava samples as outcrops are covered by thick carbonate crusts.