Mud Volcanoes and Fluid Migration in the Sorokin Trough

Sebastian Krastel¹, Michelle Wagner-Friedrichs¹, Volkhard Spiess¹, Leonid Meisner², Gerhard Borhmann¹, and Michael Ivanov^3
1Bremen University, Bremen, Germany
²Okeangeofizika Research Institute, Gelendzhik, Russia
³Moscow State University

The Sorokin Trough forms structural depression along the south-eastern margin of the Crimean Peninsula. Compressive deformation affects the growth of diapiric ridges and facilitates fluid flow to the seafloor and the evolution of mud volcanoes above the diapirs. The main objective of a high-resolution multi-channel seismic survey carried out by Bremen University (Germany) was to study the evolution and formation of mud volcanoes correlated to gas/fluid migration and gas hydrates occurrences. We grouped mud volcanoes in the Sorokin Trough in three areas. The different geological setting influences the evolution of the individual mud volcanoes and hence their morphology. Collapsed depressions dominate in Area 1 in the western survey area. A 2.5D seismic data set was collected across the Sevastopol Mud Volcano representing a typical collapsed depression located above a complex diapiric structure with two ridges. Bright Spots in direct vicinity of the conduit of the mud volcano probably mark the base of the gas hydrate stability zone. We postulate that overpressured fluids initiated an explosive eruption generating the collapsed depression of the Sevastopol mud volcano and subsequent mud extrusions formed cones within the depression. The homogeneous fan deposits of the Palaeo Don-Kuban Fan in the central and eastern Sorokin Trough are characterized by increased permeability resulting in quiet effusive mud extrusions in Areas 2 and 3. Mud volcanoes in the central Area 2 reach enormous dimensions with diameters up to 2000 m and heights of about 100 m where faults with large offsets allow high mud flow rates.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece