Geophysical processes and biosphere: article

Аnnotation: The article presents a comparative analysis of the isotope-geochemical characteristics of the products of activity of mud volcanoes in the north-west (Azerbaijan) and south-east (Iran) parts of the South Caspian Basin (SCB). Gases of mud volcanoes in the studied regions are mainly of thermocatalytic origin with a predominance of methane. High concentrations of nitrogen (up to 50 %) are noted in the gases of some mud volcanoes in the Iranian sector. A distinctive feature of the mud volcanoes in the Azerbaijani part of the SCB is the presence of isotopically superheavy (> 5 ‰) carbon dioxide, which is not typical for the mud volcanoes in Iran. The waters of the MV of Iran and most of the mud volcanoes of Azerbaijan are of the sodium chloride type. Isotopically heavy bicarbonate and carbonate ions, characteristic of the mud volcanic waters of Azerbaijan, are not typical for the vol-canoes of the Iranian part of the SCB. Organic matter of rock-ejecta of mud volcanoes in the Azerbaijani part of the SCB refers mainly to type II, type II–III kerogen, while in its Iranian part – main-ly to type III kerogen. Mud volcanoes of Azerbaijan are characterized by a wide range of gas generation depths (10–16 km) and, accordingly, significant subvertical migration. The calculated maxi-mum depth of the HC gas source in the Iranian part of the SCB does not exceed 12 km.