FORMATION OF NEOPLEISTOCENE EROSIONAL ACCUMULATIVE CYCLES OF MOUNTAIN RIVERS

S. A. Nesmeyanov

Sergeev Institute of Environmental Geoscience, Russian Academy of Sciences,

Ulanskii per. 13, str. 2, Moscow, 101000 Russia

*Е-mail: voa49@mail.ru

The concept about the structure of erosional and accumulative cycles in mountain-river terrace formation are getting gradually more complex as new data are being accumulated and original ideas appear. At first, four successive stages were distinguished in alluvium accumulation, i.e., the instrative, substrative, constrative, and perstrative stages. Later, it was realized that the boundary between the erosive and accumulative phases of the cycle lies within the substrative stage, whereas the boundary between the cycles of different age is found within the perstrative stage. The erosion phase is divided into subphases of deepening and lateral erosion. The deepening erosion subphase includes the end of the perstrative and the beginning of the instrative stages. The lateral erosion subphase, which controls the valley floor width, belongs to the substratum stage. A narrow instrative cutting deepens the substative valley bottom. The bulk of the alluvium is formed at the constrative stage. The erosion cutting depth depends on the orogenic force, whereas the cutting width is controlled by the climate-dependent water capacity. Deepening erosion predominates upon cooling and mountain glaciation, and the substrate stage coincides with the maximal climate warming. The progressive orogenesis forms a rear terrace sequence (a staircase) in mountain valleys. The age of its steps stands for the time of deepening erosion end and conservation of this valley section. Valley glaciers crawl from step to step, with their frontal moraines being facially replaced by fluvioglacial and alluvial deposits of the same age.

Keywords: terrace; erosional and accumulative cycle; erosional and accumulative phases; subphases of deepening and lateral erosion; instrative, substrative, constrative, perstrative stages of alluvium formation; rear terrace staircase

REFERENCES

1. Velikanov, M.A. Strukturnye formy ruslovoi turbulentnosti [Structural forms of channel turbulence]. Izvestiya AN SSSR, ser. geofizich., 1951, no. 3. (in Russian)

2. Kostenko, N.P. O printsipakh sostavleniya spetsal`noi geomorfologicheskoi karty [On the principles of compiling a special geomorphological map]. Byulleten’ MOIP, 1961, no. 26, pp. 20-34. (in Russian)

3. Kostenko, N.P. Geomorfologiya [Geomorphology], 2^nd edition, Moscow, MSU Publ., 1999, 383 p. (in Russian)

4. Makarova, N.V., Makarov, V.I., Akinin, B.E. Osnovnye zakonomernosti stroeniya chetvertichnogo allyuviya i stadii formirovaniya terras gornykh rek Srednei Azii [Basic regularities of the Quaternary alluvium structure and the formation stages of mountain river terraces in Central Asia]. Byulleten’ KIChP, 1979, no. 49, pp. 90-104. (in Russian).

5. Makarova, N.V., Makarov, V.I., Solov`eva, L.I. O pererabotke drevnego rel`efa gornykh stran chetvertichnym oledeneniem [About the processing of the ancient relief in mountain areas by Quaternary glaciation]. Geomorfologiya, 1980, no. 1, pp. 48-54. (in Russian)

6. Makarova, N.V., Chistyakov, A.A., Akinin, B.E. Zakonomernosti formirovaniya moshnosti allyuviya gornykh rek [Regularities in the alluvium thickness formation in mountain rivers. Byulleten’ KIChP, 2008, no. 68, pp. 70-81. (in Russian)

7. Makarova, N.V., Makarov, V.I., Postolenko, G.A., Akinin, B.E. Predstavitel`nost` allyuviya dlya stratigrafii i korrelyatsii chetvertichnykh otlozhenii [Representativeness of alluvium for stratigraphy and correlation of Quaternary deposits]. Stratigrafiya. Geologicheskaya korrelyatsiya, 2011, vol. 19, no. 4, pp. 1-23. (in Russian)

8. Makkaveev, N.I. Stok i ruslovye protsessy [Runoff and channel processes]. Moscow, MSU Publ., 1971. 115 p. (in Russian)

9. Mamedov, E.D. O plyuvial`nykh paleoklimatakh pustyn` v pleistocene [On pluvial paleoclimates of deserts in the Pleistocene] Problemy osvoeniya pustyn`, 1985, no. 3, pp. 10-16. (in Russian)

10. Nesmeyanov, S.A. K voprosu o stratigraficheskikh skhemakh chetvertichnykh otlozhenii Zapadnogo Tyan`-Shanya (v svyazi s sushhestvuyushhimi predstavleniyami o razvitii erozionnykh tsiklov) [On the question of stratigraphic schemes of Quaternary deposits of the Western Tien Shan (in connection with existing ideas about the development of erosion cycles)]. Byull. KIChP, 1965, no 30, pp. 136-144. (in Russian)

11. Nesmeyanov, S.A. Korrelyatsiya kontinental`nykh tolshch [Correlation of continental strata]. Moscow, Nedra Publ., 1977, 144 p. (in Russian)

12. Nesmeyanov, S.A. Metodika izucheniya terrasovogo geneticheskogo kompleksa dlya analiza paleoekologii paleoliticheskikh stoyanok v gornykh oblastyakh [Methods of studying the terrace genetic complex for the analysis of paleoecology of Paleolithic sites in mountain areas] Metodicheskie problemy rekonstruktsii v arkheologii i paleoekologii [Methodical problems of reconstruction in archeology and paleoclimatology]. Novosibirsk, Nauka Publ., 1989, pp. 225260. (in Russian)

13. Nesmeyanov, S.A. Geomorfologicheskie aspekty paleoekologii gornogo paleolita (na primere Zapadnogo Kavkaza) [Geomorphological aspects of Paleolithic paleoecology in mountain regions (by the example of the Western Caucasus)]. Moscow, Nauchnyi mir, 1999, 392 p. (in Russian)

14. Nesmeyanov, S.A. Geneticheskie kompleksy kontinental`nykh otlozhenii. [Genetic complexes of continental deposits]. Moscow, Kniga i biznes Publ., 2012, 397 p. (in Russian).

15. Nesmeyanov, S.A. Orotektonicheskii metod [Orotectonic method]. Moscow, Mittel Press, 2017, 376 p. (in Russian)

16. Nesmeyanov, S.A., Barkhatov, I.I. Noveishie i seismogeneriruyushchie struktury Zapadnogo Gissaro-Alaya [The newest and seismogenerating structures of the Western Gissar-Alai]. Moscow, Nauka Publ., 1978, 120 p. (in Russian)

17. Nesmeyanov, S.A., Voeikova, O.A., Muryi, A.A. Metodika postroeniya srednemasshtabnykh kolichestvennykh paleorekonstruktsii rel`efa primorskogo orogena [Methodology for constructing medium-scale quantitative paleoreconstructions of the Primorsky orogen relief]. Geoekologiya, 2016, no. 1, pp. 3-24. (in Russian)

18. Skvortsov, Yu.A. Metod geomorfologicheskogo analiza i kartirovaniya [Method of geomorphological analysis and mapping]. Izvestiya AN SSSR. Ser. Geogr. i geofiz., no. 4-5, 1941, pp. 501-522. (in Russian)

19. Chediya, O.K. Yug Srednei Azii v noveishuyu epokhu goroobrazovaniya. Kn. 1. Kontinental`nye kainozoiskie nakopleniya i geomorfologiya [The South of Central Asia in the modern era of mountain formation. Book 1. Continental Cenozoic accumulations and geomorphology]. Frunze, Ilim Publ., 1971, 332 p. (in Russian)

20. Chediya, O.K. Yug Srednei Azii v noveishuyu epokhu goroobrazovaniya. Kn. 2. Noveishaya tektonika i paleogeografiya. [The South of Central Asia in the modern era of mountain formation. Book 2. Recent tectonics and paleogeography]. Frunze, Ilim Publ., 1972, 226 p. (in Russian)

21. Shul`ts, S.S. K voprosu o genezise i morfologii rechnykh terras [On the question of the genesis and morphology of river terraces]. Tr. KIChP, 1934, vol. 3, is. 2, pp. 65-80. (in Russian)

22. Shul`ts, S.S. Opyt geneticheskoi klassifikatsii rechnykh terras [Experience in genetic classification of river terraces]. Izv. VGO, 1940, vol. 72, is. 6, pp. 739-750. (in Russian)

23. Shchukin, I.S. Obshchaya geomorfologiya. [General geomorphology]. Vol. 1. Moscow, MSU Publ., 1960, 616 p. (in Russian)

24. Eksperimental`naya geomorfologiya [Experimental geomorphology]. Vol. 2. Moscow, MSU Publ., 1969, 180 p. (in Russian)