Recent sea floor studies revealed a planetary system of bottom abyssal currents which embraces the whole floor of the World Ocean abyssal zone. The currents are generated mainly by cool water of the Antarctic shelves, the water due to its high density descends and flows along the continental slope and then spreads over all the ocean floor basins including those in the Northern hemisphere. Arctic and Subarctic deep water adds to the near-bottom currents (f, e. Sea of Okhotsk). Sometimes bottom abyssal currents result from dense water of abnormally high salinity. Bottom abyssal currents velocity may exceed 10 cm/sec, sometimes up to l meter per sec, they can erode sea floor and form abyssal valleys, transport enormous masses of suspended matter (near-bottom clouds-nepheloides) and deposit them where the flow descelerates, forming huge piles of sediments («sedimentary ridges»). Sometimes these currents are responcible for lack of sediments and considerable gaps in geological records. The current activity may change considerably through the geologic history.
At present the «geomorphological correlation» is taken in a very broad sense including correlation of topography with tectonic structures (the basis of morphostructural analysis). Another kind of genetic correlation may be studies of geotectures and morphostructures genetic series, the latter should be considered as historical-genetic systems, with all the main attributes of natural systems. The study of evolutionary (genetic) series is based on the assumption that regular spatial position of landforms which are in genetic connection reflects their evolution through time, this thesis is one of laws of geomorphology.
The map of averaged relief of the Russian Plain gives simple and obvious presentation of the most important topographic features of the area. It emphasizes regional pattern of surface elevations and inclinations distribution and «takes away» small, mostly erosional landforms. An importance of oblique directions of orographic axes is manifested, together with longitudinal and latitudinal directions as well as arcuate connections. A hierarchic structure is clearly seen: landforms of one rank are united in consequtive order to form landforms of higher rank. The technique of the map compiling is described, its contents and some implications are considered.
Геоморфология и народное хозяйство 
Paleo-geomorphological analysis application to hydrocarbons deposits search is shown with special reference to the zone of contact between the Great Caucasus and West-Cuban foredeep. Lithological (drilling) data appeared to be highly compatible with independent paleo-geomorphological reconstructions which permitted to trace Miocene rivers valleys. Several stages of drainage network evolution in miocene are distinguished, i. e. Karaganian, Middle Sarmatian and Meotian stages, the latter being synchronous with the 4th productive horizon formation. Most debeloped river network existed in Middle Sarmatian and Meotian epochs. The technique is shown to be advisable for areas similar in structure to the region considered.
On the basis of Lower Permian sediments lithology and thickness studies a paleogeomorphological analysis of pre-Lower Permian surface is given and a paleogeomorphological map is compiled for the Astrakhan gas-condensate depos't area. Four parts are distinguished within the area differing in endogenous and exogenous processes rate, each part being characterized by a special set of landforms. Processes are described which are favourable for filtering properties and capacity of productive rocks. Distribution of various types of collectors is described.
Методика научных исследований
River valley evolution model simulated by a computer is analysed and the conclusion drawn that the whole history of the geomorphic system (exogenous and endogenous reliei-forming factors history included) is fixed implicitly in the structure observed. This property of the system bihavior may be used for realisation of its automatic reconstruction algorithm. Main stages of the reconstruction technique realisation are discussed.
Various buried destructional landforms can be identified through different relations of stratigraphic bodies above and below tre discontinuity surface, the relations are shown to be resistant to subsequent tectonic deformations. Some regularities established in the relations permit to develop methods of buried landforms reconstruction, including both traditional and new techniques.
Научные сообщения
Multi-stage genetic classification of lake basins is developed for the West Siberian plain. Its structure permits to include new categories of basins if additional data are received.
The substrate lithology impact on petrographic spectra of alluvium is considered with reference to two largest East Siberian rivers such as Lena and Aldan. The desintegration character is proved to influence both granulometry and petrography of alluvium. Coefficients of variation are obtained for petrographic composition in three fraction for different parts of rivers. The correlation was established between petrographic spectrum of alluvium and rocks lithology within a drainage basin. A sequence of rocks is established according to their resistance to abrasion during the channel transport as well as relation of local material (provided by small rivers) and «transit» which is moved along the trunk valleys.
In accordance with new new geomorphological data the highest point of the Russian Plain is the mount Berda (515 m a. s. 1.) situated on the Dniestr-Prut interfluve in Northern Bucovina.
Some results are given of long-term studies of the Pitsunda promontory coastal zone dynamics depending on changes in beach-forming debris discharge of the Bzyb River. Abrasion cycles are established (1926 to 1942 and 1959 to 1983) as well as sedimentation cycles from 1903 to 1926 and 1942 to 1959. Submarine canyons activity is supposed also to undergo cyclic changes.
Complex approach to sea coasts study makes clear many problems which seem difficult when one-sided approach used. It permits also to check up results obtained by various methods.
The alluvial gravel of the ancient valley of the Tola River overlapped by Pliocene red clays and Quaternary proluvial and lacustrine deposits has been revealed within the chain of depressions, e. g. Dzamar Tselin, Tszokhoy. The depressions were formed as a result of neotectonic shifts in blocks which damrned the river and created a chain of lakes. The present-day river network came into being at fer the lakes had been drained.
A number of methods are proposed to identify topographic levels in mountains, some of the methods are used for the purpose for the first time. Analysis of summit surfaces morphology of the Jugjur and Pribrezhny ridges (Western Okhotsk region), their vertical and lateral distribution and correlation of different watersheds types revealed up to six topographic steps in the region, which can be united into 3 levels. The topographic levels mostly resulted from denudational planation and active block tectonics. Planated watersheds of the 3rd and 2nd levels were formed during Paleogene (and later distorted by neotectonic movements), the 1st level formation took place in Pliocene. Topographic steps system was modified and complicated by river erosion, altiplanation and rocks lithology and structure.
Morphological types of the Terek River channel are considered and their succession from the source towards the river mouth is discussed, the latter being preconditioned with the valley geological and geomorphic features. The longitudinal profile transformation is considered in details as well as special features of the bed load granulometric differentiation along the valley.
Дискуссии
Engineering-geomorphological analysis is considered to be an important component of integrated studies aimed for water control measures planning and execution. The analysis includes empirical data gathering, theoretical conclusions and development of recommendations tor practice.
The outflow of basic magma through deep faults on oceanic floor results in forming of effusive covers and compensative subsidence of oceanic lithosphere. The latter is accompanied by submergence of extinct volcanoes cones which can be transformed into guyots.
Рецензии
Словарь терминов по палеогеографии плейстоцена - Маруашвили Л. И. Палеогеографический словарь. М.: Мысль, 1985. 368 с.
Хроника
ISSN 2949-1797 (Online)
