Abstract:

Mud volcano structures appear as discontinuous blank to chaotic reflections with weak amplitudes in seismic facies,and are in columnar uncomformable contact with adjacent rocks.Controlled by stress field and tectonic active belt of the basin,the mud structures are better developed in the piedmont thrust belt on the basin margin in the center of subsidence.In the same structural belt,mud volcanoes occur in paternoster distribution along trend of the major fault and anticlinal zone.Mud volcano structures are characterized by episodic eruption with radial normal faults and slump structures developed in shallow layers.The volcano structures can be classified into anticlinal,strike-slip fault,and thrust types,according to their origins and characteristics.Geological background,tectonic activity in compressional strike-slip stress field,rapid sedimentation and abnormal formation pressure,are the major reason behind the formation of mud volcano structures.The mud volcano structures exert influences over the hydrocarbon generation,migration,accumulation,preservation,and destruction as well as trap formation,and development of reservoirs.

Key words: mud volcano, structural feature, structural type, forming mechanism, rapid sedimentation, hydrocarbon accumulation, South Caspian basin