Mud Volcanoes of the Black Sea

Alexey Meisner¹ and Leonid Meisner^2
1DCS, Schlumberger, Moscow, Russian Federation
²Yuzhmorgeologia, Moscow, Russian Federation

In the Black Sea investigations of mud volcanoes began in the mid-1980s. About fifty mud volcanoes of various scales were discovered on the basis of seismic, sidescan sonar, subbottom profiler, multibeam, gravity corer, TV-guided grab data at water depths between 1600 and 2150 m. The data were summarized to understand some structural aspects controlling formation and distribution mud volcanoes in the Black Sea.

As a rule mud volcanoes are conic build-up, with a maximum relief of 120 m over the sea floor. Their tops are complicated by caldera-like depressions and rims with diameter up to 2 km. Mud volcanoes occur mainly within shale diapirs, but some of them coincide with smooth anticlines on the eastern margin of the ancient buried Western Black Sea Basin. Some features on seismic sections could be interpreted as signs of buried mud volcanoes. All known mud volcanoes were found on the modern continental slope or on the periphery of ancient buried basins. These areas are characterized by numerous faults. Faults have been acting as major migration pathways for fluids. Some of pathways have been developing as mud volcano feeder-cannels. The seismic sections show feeder-cannel base in the Eocene deposits at the depth up to 8 km. But, the most of mud volcano breccia clasts are the Upper Oligocene in age. The Eocene-Oligocene shale thickness varies from 1 to 6 km thick.

Following main conclusions can be derived:
1. Formation and distribution of mud volcanoes depend on tectonic activity of sea-floor areas.
2. Spatial distribution of mud volcanoes is associated with periphery of modern and ancient basins.
3. Mud volcano feeder-cannels can be traced down to 8 km below the sea floor.
4. Most likely the main mud volcano source rock is the Eocene-Oligocene shale.

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