Deep-Water Pockmarks in the Kyparissiakos Gulf (S. Ionian Sea) and Geochemical Evidence for Methane Seepage

A multidisciplinary survey was carried out by Oceanus-Lab (University of Patras) and HelleniQ Upstream on board the R/V AEGAEO (HCMR) for the detection of gas related morphological features and possible gas seepages at the Kyparissiakos Gulf. For the survey, acoustics (multibeam echosounders, MBES), seismics (airgun), geochemical (gas geochemistry) and sensors (methane) approaches were used. The initial selection of the survey area was based on seismic interpretation and other data provided by HelleniQ Upstream. The multibeam and airgun survey showed an important pockmark field in the lower slope of Kyparissiakos Gulf at water depth of 1050m. The field consisted by two pockmark groups is located close to a deep-sea channel and seems to be related to gravitative mass movements. Moreover, subbottom profiling data, collected in the wider area, showed acoustic anomalies which are related to gas charged sediments (gas chimneys). The isotopic composition of seepage gases from a pockmark in group B showed thermogenic origin.