The head of the project: Olga N. Solomina
The title of the project: Glacial history and catastrophic processes in Russia Altai in the Late Pleistocene - Holocene
Key words: Alpine glaciations, megafloods, large paleoearthquakes, Pleistocene, Holocene, Last Glacial Maximum, luminescence dating, rock surface dating, terrestrial cosmogenic nuclides, Gorny Altai, Pre-Altai Plain
Summary
The history of glaciation in the geological past in the mountain systems of the south of Russia remains controversial. There is no agreement in the research community on the time of maximum spread of glaciation, in particular, when there was a regional glacial maximum in the late Pleistocene and whether it corresponded to the global glacial maximum (LGM). The reason for this is the lack of a sufficient number of direct dating of glacial and associated sediments. The difficulties of dating are related to the fact that the radiocarbon method widely used in Russia is rarely applicable to this type of deposits due to the rare occurrence of organic residues in them. In addition, the age of a significant part of the key sedimentary strata goes beyond the limits of the radiocarbon method. To bring the issue of the chronology of glacial events in the mountain systems of Russia to the international level, it is necessary to apply modern dating techniques that have proven themselves well in world practice in recent decades - luminescent (OSL, pIRIR, rock surface dating) and terrestrial cosmogenic isotope (TCN).
Due to the works of the classics of Russian glacial geomorphology, the most studied mountain system in relation to the glacial history is the Russian Altai. The large available data makes Altai an optimal proving ground for solving problems in the chronology of glacial history, working out approaches and methods that can later be applied to other mountain systems of Russia. In addition, natural events of world rank are associated with the Russian Altai - glacial superflooding, ranked by most of the researchers as one of the largest hydro-disasters in the geological history of the Earth. The discussion of the parameters and time of occurrence of these floods, which are directly related to the glacier history, has been going on for more than three decades and can only be completed by obtaining reliable direct geochronological data. The trigger of glacial catastrophes could be seismic events, the impact of which could break the stability of moraine and ice dams and lead to rapid outbursts of glacial lakes. On the other hand, local loading and rebound of the earth's crust in connection with the filling / descent of dammed reservoirs could contribute to the occurrence and release of lithospheric stresses in the form of seismic events. Seismogenic landslides caused the damming of rivers, comparable in scale to glacial ones.
The project aims to reconstruct the history of the glaciation of the Russian Altai and the associated exo- and endodynamic processes in the last 150 thousand years. A comprehensive study of the glacial history of Altai includes the study of both the actual glacial formations and related phenomena, limno-glacial, fluvio-glacial, and seismic. Therefore, to achieve this goal, the following tasks will be solved:
- determination of the age and boundaries of the maximum and minor phases of mountain glaciation in the Late Pleistocene, the dynamics of glaciers in the Holocene;
- determination of the epochs of activation of the breakthrough of large glacial-dammed and landslide-dammed lakes in the Pleistocene - Holocene, the distance of propagation of flood waves in the foothill areas.
- identification of traces of ancient seismic catastrophes in the landscape and in the Pleistocene-Holocene sediments, estimation of parameters and age of paleoseismic events, analysis of the spatial and temporal distribution of ancient and historical seismicity;
- the establishment of paragenetic links between glacial phases, the formation and descent of subsurface reservoirs and paleo-seismic events.
The novelty of the project is that massive geochronological data will be obtsained in order to solve the long-discussed questions of the Quaternary history of Altai. The most up-to-date geochronological methods will be used that were previously only limitedly or not at all applied in the region. Against the background of classical approaches (lithologic, stratigraphic, geomorphological, paleoseismological) optically stimulated (OSL) and infrared luminescence (IRSL) will be used - for dating lake and flood sediments, accumulation of cosmogenic isotopes - for dating the exposure of rock surfaces (dropstones, moraine and landslide blocks, the walls of the detachment of rock slides), luminescent dating of the time of burial of rocky surfaces (megaflood blocks). The possibilities of 14С, AMS 14C and dendrochronological methods will also be used to date the ages of the paleo-earthquakes. Geophysical methods will also be applied (GPR sounding, seismic and electrical prospecting), and the construction of detailed digital elevation models using unmanned aerial vehicles.
The actuality of the project tasks is determined by both fundamental scientific and applied aspects. The absence of a reliable timescale for glacial and glacio-fluvial events in Altai, along with other mountain systems of southern Russia, indicates a lagging degree of their knowledge from other mountain systems of the Northern Hemisphere - European (Alps, Pyrenees), Asian (Tibet, Himalayas, Karakorum), North American (Rocky Mountains, Cascade Mountains, Great Basin). Clarification of the age of world-known Altai megafloods, is of great interest to the international scientific community. The applied value is determined by the growing need for studying the spatial-temporal patterns of natural disasters, zoning by the level of danger of catastrophic phenomena in connection with the development of mountain and foothill territories. Compared with the traditional approach of rapid disaster response, prognosis and preventive measures reduce losses by 15 times. For the forecast of modern natural disasters, the identification of the scale, age and number of paleocatastrophic events is of paramount importance.
The expected results
1. The main phases of glaciations in Altai in the Late Pleistocene and Holocene will be established and dated; the maximum phase of glaciation will be revealed.
2. The most powerful megafloods of Altai will be dated.
3. A scheme of regional correlation of the Pleistocene-Holocene marker deposits of paleocatastrophes in the south of Western Siberia will be created;
4. Paleogeographic patterns of the spread of glacial superflooding from the Altai Mountains to the south of the West Siberian Plain will be developed.
5. A catalog of strong paleo-earthquakes of Gorny Altai and a map of the location of ancient epicentral zones will be compiled.
6. A map of the spatio-temporal relationships of endogenous and exogenous paleocatastrophes in the south of Western Siberia will be compiled with the localization of areas of increased occurrence of geological evidence of paleocatastrophes.
The project will put Altai on a par with world leaders in the level of hydrocatastroph studies, such as the Scabland of the Colombian Plateau (outbursts of Lake Missoula) and the Great Basin (outburst of Lake Bonneville). In terms of the level of knowledge of the glacial history, Altai will catch up with similar Eurasian mountain regions, such as the Alps and the Pyrenees.
The use of a set of the newest methodological developments will make it possible to perform more reliable determinations of the absolute age of deposits of catastrophic and paleoseismic events, moraines, fluvial terraces and cover loess-like deposits. The resulting array of absolute ages will solve the key problem of the Altai glacial superflooding, which has been actively discussed in the world scientific literature, the age of the superfloods and their number. As a result, the implementation of this project will allow verification of the absolute dates obtained earlier, and reconstructions created on their basis, as well as create prerequisites for clarifying the existing chronostratigraphic scheme of the late Pleistocene – the early Holocene of Gorny Altai. The project implementation will be the basis for enhancing research on geochronology, the development of dating protocols by domestic laboratories. Mastering new innovative approaches in luminescent dating, such as determining the age of exposure of rocky surfaces and the burial of large blocks, will be possible due to the active participation of the project team in international collaborations with leading world centers.
The obtained results will allow to substantiate a reliable stratigraphic and geochronological correlation of Quaternary deposits, markers of catastrophic events for Gorny Altai and the Pre-Altai plain. In the future, this correlation can be used as a peculiar framework of “fast” geological events in the preparation of a new general correlation scheme for Quaternary sediments in the south of Western Siberia. The catalog and the map of strong ancient earthquakes will be in demand both for the purposes of seismic zoning of the territory, and for studying the general Quaternary geodynamics of Central Asia.
According to the results of the Project, recommendations can be formulated for federal and regional authorities, state and private companies, significantly reducing the financial and social risks from natural exogenous and endogenous disasters in the economic development of Altai and adjacent territories. This is especially important because within the study area there are large cities (Barnaul, Biysk, Gorno-Altaisk) and rural settlements, construction of a gas pipeline to China and a network of small hydropower stations is planned, and tourist infrastructure facilities are being intensively built.
