Characteristics of features formed by gas hydrate and free gas in the continental slope and abyssal plain of the Middle Caspian Sea

Physicochemical conditions are proper to form gas hydrate and free gas in the Caspian Sea which are considered both for geohazard assessment and future possible source of energy. Gas migration, hydrate formation and decomposition cause different types of features to form in the seabed and sediments which can be affected by geological and physical conditions of sea. In this study, high-resolution marine seismoacoustic profiles were interpreted to investigate features formed by gas hydrate and free gas and assess their characteristics in the continental slope and abyssal plain of the middle Caspian Sea. A mud volcano, gas chimneys, pockmarks, gas pipes, sediment disturbances, a crater, a giant landslide and a big gentle diapir were investigated and reported in the present study. The geological and physical conditions including bathymetry, tectonic activity, sediments supply and water depth are different in the continental slope and abyssal plain, thereby the features of these two environments were compared to understand the effect of different conditions.

Automated summary

This study investigated features formed by gas hydrate and free gas in the continental slope and abyssal plain of the Caspian Sea. The analysis was based on high-resolution marine seismoacoustic profiles, revealing various features such as mud volcanoes, gas chimneys, pockmarks, gas pipes, sediment disturbances, craters, landslides, and diapirs. Comparisons were made between the geological and physical conditions of the continental slope and abyssal plain to better understand the impact of different environments on the formation of these features.