V.I. Shegai, A.V. Tolstikov
North-eastern Sakhalin Shelf: features of structural and tectonic evolution in view of new seismic data
Key words: Okhotomorsky region; Sakhalin Island; pull-apart tectonics; hydrocarbon potential; oil; gas.
For citation: Shegai V.I., Tolstikov A.V. North-eastern Sakhalin Shelf: features of structural and tectonic evolution in view of new seismic data. Geologiya nefti i gaza. 2022;(4):39–51. DOI: 10.31087/0016-7894-2022-4-39-51. In Russ.
Analysis of new seismic data showed that three stages of tectonic activity, which largely determined the current outlook of north-eastern Sakhalin and neighbouring shelf, can be identified in the Cenozoic interval of structural and tectonic evolution of Sakhalin Island. In Early Miocene stage, most of strike-slip dislocations in the north-eastern shelf of Sakhalin Island originated. It was found that configuration of strike-slip faults is radial. They take their rise at the joint of Pogranichny block of Okhotomorsky Plate (Sovgavansky/Mynginsky fault) and Khokkaido-Sakhalinsky strike-slip fault, and open in eastern and north-eastern directions. Activation of this system of strike-slip dislocations against the background of lithosphere expansion and formation of the Deryuginsky Basin situated to the east of the study area was a most likely cause of destruction of Kirinsky Paleogene mega-high and formation of Kirinsky and South Kirinsky structures there. Some of the large blocks (Nogliksky, Lopatinsky, Deryuginsky, Norsky, and Ulvinsky) move far towards the east. Judging by their current position, amplitude of the movement at that time could be hundreds of kilometers or more. Middle Miocene and Pliocene-Quaternary stages of tectogenesis are pronounced in the activity of the East Sakhalinsky strike-slip fault. Group of structures extending along the East Sakhalinsky strike-slip fault grow intensively. Synchronous evolution during Miocene and Pliocene allowed combining them into a single Odoptinsky-Schmidtovsky upstanding zone. The conclusion that Pliocene-Quaternary strike-slip activity may result in partial violation of seal above the accumulations was the important result of the studies conducted. The proximity of the East Odoptinsky strike-slip fault is supposed to be a most probable cause of gas escape from the Neptun field pools.