3D Black Sea - Sevastopol Mud Volcano

3-D seismic investigations carried out across the Sevastopol mud volcano in the Sorokin Trough present detailed subsurface images of a mud volcano in the Black Sea. The study reveals a complex three-dimensional morphology of a collapsed mud volcano structurewhich allows to reconstruct its evolution. 

The Sevastopol mud volcano is located above a buried diapiric structure with two ridges. Its controlled by fluid migration along a deep fault system, which developed during the growth of the diapirs in a compressional tectonic regime. Overpressured fluids initiated an explosive eruption generating the collapse depression of the Sevastopol mud volcano. Several cones were formed within the depression by subsequent quiet mud extrusions. 

Although gas hydrates have been recovered at various mud volcanoes in the Sorokin Trough, no gas hydrates were sampled at the Sevastopol mud volcano. A BSR (bottom-simulating reflector) is missing in the seismic data; however, high-amplitude reflections (bright spots) observed above the diapiric ridge near the mud volcano at a relatively constant depth correspond to the approximate depth of the base of the gas hydrate stability zone (BGHSZ). It seems that gas hydrates are present locally where gas/fluid flow occurs related to mud volcanism, i.e., above the diapir and close to the feeder channel of the mud volcano. Depth variations of the bright spots of up to 200 ms TWT might be caused by temperature variations produced by variable fluid flow.

Publication

Wagner-Friedrichs, Michelle, Krastel S., Spiess V., Ivanov M., Bohrmann G., Meisner L. (2008) Threedimensional seismic investigations of the Sevastopol mud volcano in correlation to gas/fluid migration pathways and gas hydrate occurrences in the Sorokin Trough (Black Sea). Geochemistry, Geophysics, Geosystems, 9, Q05012, https://doi.org/10.1029/2007GC001685