Title

V. A. Zhamoyda, D. V. Ryabchuk, M. A. Spiridonov, A. G. Grigoriev, N. V. Pimenov, A. V. Amantov, Yu. P. Kropachev, I. A. Neevin

Geological and geomorphologic conditions of pock-mark formation in the eastern Gulf of Finland

In 2009–2012 new data concerning distribution of pock-marks in the eastern Gulf of Finland as well as geological and geomorphologic conditions of their formation were gathered within the monitoring of geological environments. Pock-marks of the different genesis are widespread in the gulf bottom. The pock-marks discovered within the areas of silty-clayey sedimentation in the central part of the gulf were formed as a result of biogenic gas-seepage. In the Kopora Bay pock-marks were probably formed as a result of groundwater discharge from the Vendian aquifer system, although it is possible to find some spatial correlation with tectonic faults distribution. The presence of pock-marks of several generations indicates pulsating nature of their occurrence.
Key words: pock-mark, gas-bearing sediments, Gulf of Finland