Submarine valleys of the North-Eastern Okhotsk Sea Region

Abstract

The submarine valleys of the north-western Okhotsk Sea have been describe using the expedition studies, cartographic materials and previously published data. The main factors influencing morphogenesis of the bottom relief include the cold water of Okhotsk Sea, the duration of ice cover, strong tidal currents, and an attenuated wave regime. Complex coastal topography is determined by the geological structure of the study area, seasonal sediments supply by rivers, ice activity, and coastal abrasion. Intensive exogenous processes have formed large morphosculptural forms of complex genesis, including submarine valleys. During the study of the submarine valley in the Penzhinskaya Bay, it was revealed that it has a V-shaped transverse profile. The valleys sides are smooth, with the western sides slightly steeper than the eastern. The width of the valley is 1.5–2 km on the northern tacks, and 0.7–1.0 km on the southern ones. The steepness of the slopes reaches 10–12 degrees. Shelikhov’s trench, which connects Bay of Shelikhov with the Okhotsk Sea, stretches in the meridian direction for almost 300 km and mergers with the TINRO depression. Its width ranges from 30 to 40 km. The northern part of the western side of the TINRO depression is cut by large erosive valleys of the meridional strike. In the southern part a dense network of erosive channels has been developed with an incision depth of up to 100 m and a width of 1–1.5 km. The transverse profiles of the channels have a well pronounced V-shape, which indicates an active flushing regime. The channel network has a dendritic pattern. Regardless the origin of these forms, the main factor controlling their development at the present is intense tidal currents, to clarify the genesis, it is necessary to obtain additional geophysical and hydrological data. The performed studies can be used in predicting the further region’s economic development.