Intermountain Basins Research Articles

A Preliminary Fuzzy Inference System for Predicting Atmospheric Ozone in an Intermountain Basin

High concentrations of ozone in the Uinta Basin, Utah, can occur after sufficient snowfall and a strong atmospheric anticyclone creates a persistent cold pool that traps emissions from oil and gas operations, where sustained photolysis of the precursors builds ozone to unhealthy concentrations. The basin’s winter-ozone system is well understood by domain experts and supported by archives of atmospheric observations. Rules of the system can be formulated in natural language (“sufficient snowfall and high pressure leads to high ozone”), lending itself to analysis with a fuzzy-logic inference system. This method encodes human expertise as machine intelligence in a more prescribed manner than more complex, black-box inference methods such as neural networks, increasing user trustworthiness of our model prototype before further optimization. Herein, we develop an ozone forecasting system, Clyfar, informed by an archive of meteorological and air-chemistry measurements. This prototype successfully demonstrates proof-of-concept despite rudimentary tuning. We describe our framework for predicting future ozone concentrations if input values are drawn from numerical weather prediction forecasts rather than observations as Clyfar initial conditions. We evaluate inferred values for one winter, finding our prototype demonstrates mixed performance but promise after optimization to deliver useful forecast guidance for decision-makers when forecast data are used as input. This early version model is the basis of ongoing optimization through machine learning.

Big river channel formation and deformation in the intermountain basin (case study of the Yana River within the Kular mountain massif)

The incised pebble-boulder channels of large mountain rivers (including the Yana in its mountainous area), their morphology and history of formation are well studied. However, local conditions within the intermountain depressions lead to the emergence of specific features of the channel development and its morphology — in this case, the formation of finger-shaped meander. The paper analyzes the historical and modern features of the formation of the Yana riverbed in the “Porogi” section located in the depression inside Kular range, and describes the negative impact of channel processes on navigation. Using this case study, we consider the characteristic features of the channel development of a large river under the influence of a complex of factors — the regional geological conditions (which caused active incision of the channel), discharge, and channel sediment composition. Characteristics of lateral migration and curvature development of meander controlled by bedrock and narrowing of the valley are presented. The discharge conditions under which the displacement of riffles is possible are calculated. The forecast of the further channel development and recommendations for sustainable navigation are given.

Assessment of the resistance of landscapes of the Altai Republic
 to anthropogenic impacts

Currently, there are many points of view on assessing the resistance of landscapes to anthropogenic impact, but there are no generally accepted methods for quantitative assessment of the emergent properties of geosystems. Various methods and approaches have been developed that are based on indices of sustainability and well-being, as well as classification models, the vast majority of which are based on a score-index approach. The work provides an integral assessment of the environmental sustainability of the landscapes of the Altai Republic, which is based on a number of physical and geographical factors that influence the stability of the existing geosystems. The most important among them are: relief (especially the steepness of slopes), vegetation cover, soils, density of the river network, water balance and land types. As a result, it was established that there is a general pattern - with increasing altitude above sea level, the ecological sustainability of landscapes decreases. Against the background of this pattern, flattened areas of intermountain basins stand out, where stability increases somewhat. Thus, in the north-west of the republic, landscapes of high environmental sustainability predominate, which are succeded by less stable landscapes of the central regions, and on the slopes of the North and South Chuysky, Katunsky ridges, the Tabyn-Bogdo-Ola massif, the ecological sustainability of landscapes is noticeably reduced.

Оценка секвестрационного потенциала осиново-березовых древостоев островных лесостепей Средней Сибири

The forest-steppes of Central Siberia occupying submontane troughs and intermountain basins separated by taiga vegetation are considered insular. Forest woody vegetation is mainly represented by birch, aspen, larch and pine stands. A decisive role in the ecological sustainability of forest areas is played by larch plantations. This study has aimed to identify the characteristics of the dynamics of individual forest elements in the mixed deciduous stands within the forest area. The tasks have been to identify the characteristics of the forest area, characterize the dynamics of the taxation parameters of major and minor elements of the mixed stands and assess the contribution of the stands to the carbon balance. The work is based on the data of 548 strata. We have established the characteristics of the forest area age structure and how the stands of various completeness and productivity are represented in it. We have also estimated the variability of the average stands taxation parameters in different age periods. The average values obtained have become the basis for mathematical modeling of the table of the dynamics of the taxation parameters of the mixed stands. It turns out that the process to a reasonable degree of adequacy is reflected by the Weibull distribution. The accuracy of the equations has been estimated by the value of the coefficient of determination (R2) and the standard error of the equation (S). On the basis of the obtained mathematical models, we have constructed the table of the dynamics of the average taxation parameters of the stands of the forest elements and of the mixed stand as a whole. The biological system of forest woody vegetation under consideration has a significant carbon sequestration potential. However, there is currently no generally accepted procedure for assessing the effectiveness of this process. Russian and foreign researchers have collected a large amount of data from different regions, but they have been using different methods. To estimate carbon stocks in the stands that are the object of the study, we have used the conversion-volume method for estimating carbon stocks in forest plantations. The result is the obtained data illustrating the dynamics of carbon stocks in the aspen-birch stands in the insular forest-steppes of Central Siberia.

Tectonically induced travertine deposition in the Middle Miocene Levač intramountain basin (Central Serbia)

ABSTRACTTravertines are terrestrial carbonates that are commonly associated with fault activity in extensional and transtensional basins. The faults serve as conduits for the rising and mixing of carbonate‐enriched fluids with thermal and meteoric CO2 inputs promoting travertine precipitation at the surface. Therefore, travertine successions provide key constraint on the faulting, depositional environments, fluid flow and climate. This work focuses on the travertine succession in the Miocene Levač Basin, the marginal basin of the Morava Corridor situated at the junction of the Dinarides and the southernmost Carpathians. Detailed sedimentological, geochronological (U–Pb age, laser ablation – inductively coupled plasma – mass spectrometry) and structural analyses of the travertines are used to reconstruct the evolution of the feeding geoothermal system. Furthermore, these data were used to understand the controlling factors governing alternation of fluid flows enriched in thermally generated and meteoric CO2, and precipitation of travertines in Levač Basin, and finally to elucidate the late stage of basin evolution. Four facies associations are distinguished within the succession, i.e. travertine slope, ridge, flat, and travertine flat under the fluvial influence. The results demonstrated that travertine deposition was controlled by north‐west/south‐west and north‐east/south‐east normal fault arrays. Stable isotope data show positive δ13C values (with δ18O being negative) shifting to negative in the distal and stratigraphically younger deposits implying dilution of deep hydrothermal fluids by mixing with meteoric waters. Finally, travertine deposits yielded a new U–Pb age of ca 14 Ma indicating that the Middle Miocene extensional phase known from other intermountain basins in the Dinarides reached as far east as the Levač Basin and Morava Corridor.

Anatolian Short-Horned Grasshoppers Unveiled: Integrating Biogeography and Pest Potential.

Biogeographically, Anatolia harbours a rich diversity of short-horned grasshoppers (Orthoptera, Caelifera). The number of species recorded from Anatolia so far stands at 300. They inhabit diverse habitats ranging from arid Eremial to Euro-Siberian-like montane meadows, aligning with the topographical and climatological heterogeneity of Anatolia. Alongside some swarming species, the pest potential of several pullulating species needs attention. This is especially important concerning global warming, a scenario expected to be more severe in the Northern Mediterranean Basin in general and Anatolia specifically. A faunal list of biogeographic Anatolia, the area extending from the Aegean Sea in the west to the intermountain basin of the Caucasus in the northeast, the lowlands of Lake Urmia in the east, and Mesopotamia in the southeast, was developed. The recorded species were classified according to the phytogeographical provinces of Anatolia. Distributions of the species with the potential for pullulating were modelled using ecological-niche-modelling approaches for the present and future. The results have the potential to lead to the development of a concept that merges biogeography and the pest potential of certain Anatolian grasshopper species. Our results reveal the following: (i) Acrididae and Pamphagidae are the most diverse families represented in Anatolia; (ii) roughly 40% of Caelifera and 71% of Pamphagidae are endemics, suggesting Anatolia is a biodiversity hotspot; (iii) according to Caelifera diversity, the phytogeographical provinces of Anatolia follow an order of Irano-Anatolia, Euro-Siberia, Mediterranean, and Mesopotamia; and (iv) based on ecological modelling and personal observations, Dociostaurus maroccanus, Locusta migratoria, Calliptamus italicus, Heteracris pterosticha, Notostaurus anatolicus, Oedipoda miniata, and O. schochii should be monitored regarding their pest potential.

Analysis of the dynamics of agricultural lands of the Republic of Tyva using satellite images

The analysis of the dynamics of agricultural lands of the Republic of Tyva (Russia) is carried out. Satellite images from the Landsat-8 spacecraft for the summer period 1987–2021 were used to analyze the spatial distribution of ecosystems on the territory of intermountain basins. Digital land use maps reflect the current situation and contain information about arable land, deposits of different ages, pastures. To determine the age of the deposit, field materials were used, which made it possible to identify the composition of vegetation, varying depending on the age of the deposit, which was reflected in the images. For the first time in the post-Soviet period, a comprehensive analysis of data obtained on the basis of reconnaissance and field work, land use maps using digital technologies was carried out, which allowed us to reveal the current use of more than 30% of arable land, deposits of different ages make up 17–37% of steppe territories, most of the agricultural land is pastures. The interpretation of satellite images made it possible to draw up a map-scheme of the distribution of ecosystems on the territory of the basins. Steppe vegetation is restored on abandoned arable lands. In many fallow areas, bushes of Caragana bungei Ledeb. grow. The processes of desertification and salinization are observed in the territory under consideration.

Evolution and Transformation Analysis of Land-use in Mountainous “Granary”—Evidence from Typical Basin in Karst Mountainous Areas of Southwest China

Intermountain basins are the granaries of the karst mountains of southwest China. Revealing the process and trend of land-use transformation in typical mountainous “granaries” is of great significance to optimizing land-use, food security, and rural revitalization in the karst mountains of southwest China. Lianjiang basin in Huishui County is the largest in Guizhou Province of southwest China, and a typical mountainous “granary” is used as a case study area. Based on seven periods of high-definition remote sensing images from 1966 to 2020 and on-the-spot investigation, we adopt the analysis methods of landscape pattern, moving window, and buffer zone and conduct an in-depth study on the spatial evolution of land-use and the land-use transformation law of the typical “granaries” of karst mountainous areas in southwest China from the perspectives of changes in the quantity of land-use, changes in the types of land-use, and changes in the landscape pattern. The results showed that the transformation of land-use in the basin was mainly manifested in the transformation of the function of cultivated land and the diversification of the function of cultivated land. The landscape pattern of the basin was gradually transformed from traditional rural landscape to modern agricultural landscape. The gradient effect of land-use evolution and transformation in the study basin was obvious. Traffic, location, and land resources significantly affect land-use transformation in the basin. Based on the above analysis, this paper proposes that the “granary” basins in karst mountainous areas should optimize the land-use of the basin by the trade-off between regional socio-economic development, ecological protection, and food security. The results of this paper provide a reference for land-use optimization and rural development in the granary-type basins and other similar areas in the karst mountains of southwest China.

Using multiple isotopes to determine groundwater source, age, and renewal rate in the Beishan preselected area for geological disposal of high-level radioactive waste in China

Understanding hydrogeological conditions is crucial for selecting and assessing the long-term safety performance of a high-level radioactive waste (HLW) disposal repository. Utilizing environmental isotopes as effective markers for analysing groundwater movement, this study investigates groundwater recharge sources, age, and renewal rates using multiple isotopes in China's potential HLW repository site, the Beishan area. The results indicated deep bedrock groundwater primarily derives from ancient precipitation infiltration under cold climatic conditions. A noteworthy distinction is that loose sedimentary groundwater exhibits higher tritium content (>10 TU) compared to bedrock groundwater (<3.2 TU). Groundwater within the recharge area, especially within gullies and piedmont slope deposits, is relatively youthful, with an age of less than 30 years and an annual renewal rate exceeding 5 %. In contrast, the shallow groundwater age in the intermountain basins and depressions of the discharge area generally exceeds 50 years, with an annual renewal rate often falling below 0.5 %. At the Beishan underground research laboratory site, deep groundwater at the disposal repository depth displays a corrected 14C age exceeding 8,000 years, indicating an extremely slow movement and alteration rate. As a result, the hydrogeological conditions in the Beishan area are expected to be relatively beneficial for ensuring the safety of HLW repository.

MINERAL COMPOSITION AND FORMATION CONDITIONS OF BOTTOM SEDIMENTS OF THE SMALL LAKES IF THE UKOK PLATEAU (ALTAI)&lt;a href="#FN1"&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;/a&gt;

Numerous modern lakes appeared in the intermountain basins and on the high-elevation plateaus of Altai within the immediate distribution of glaciation in the Neo-Pleistocene. There is little known about the geochemical processes of autigenic mineral formation in lake systems under conditions of nival sedimentogenesis. The study of cores of bottom sediments of 8 high-altitude lakes of Altai showed that the waters of the lakes are fresh bicarbonate with variations in the cationic composition of Ca–Na. The bottom sediments of lakes are characterized by different ratios of mineral detrital material, autigenic minerals (calcite, gypsum, pyrite, illite) and mortmass of plant residues. In the bottom sediments of lakes located within the same basin (Bertek or Tarkhatinskaya), the absolute concentrations of elements differ within one standard deviation, with the exception of significant variations in the contents of individual elements (Mo, U, Li, Be). The enrichment of bottom sediments of lakes (Argamdzhi, Teply Klyuch, Krasnoe) with these elements is associated with the presence of ore concentrations (Mo, U, Li, Be) in the local catchment areas of a single lake. The mineral associations of the sediments of the studied lakes differ from each other in the composition of autigenic minerals, and from rocks, soils of catchment areas in the composition of layered silicates. In the composition of fine-scaled, tangled fibrous aggregates of the bottom sediment illite, the amount of iron is 2-4 times greater than in the composition of lamellar aggregates of micas, chlorites from rocks, soils of catchment areas. Cryogenic processes have determined the crystallization of gypsum nodules in the lakes Argamdzhi and Small Tarkhatinskoye; and calcite aggregates in Zerlyukol-Nur and Large Tarkhatinskoye in significant volumes for lakes with fresh water composition.

Erratum to: The Neotectonics and Geological Structure of the Sevan Intermountain Basin (Armenia): New Structural and Palaeontologic Data

Erratum to: The Neotectonics and Geological Structure of the Sevan Intermountain Basin (Armenia): New Structural and Palaeontologic Data

Dissolved Carbon Concentrations and Emission Fluxes in Rivers and Lakes of Central Asia (Sayan–Altai Mountain Region, Tyva)

The carbon (C) cycle in inland waters, including carbon concentrations in and carbon dioxide (CO2) emissions from water surfaces, are at the forefront of biogeochemical studies, especially in regions strongly impacted by ongoing climate change. Towards a better understanding of C storage, transport and emission in Central Asian mountain regions, an area of knowledge that has been extremely poorly studied until now, here, we carried out systematic measurements of dissolved C and CO2 emissions in rivers and lakes located along a macrotransect of various natural landscapes in the Sayan–Altai mountain region, from the high mountains of the Western Sayan in the northwest of Tyva to the arid (dry) steppes and semideserts in the intermountain basins in the southeast of Tyva on the border with Mongolia. New data on major hydrochemical parameters and CO2 fluxes (fCO2) gathered by floating chambers and dissolved organic and inorganic carbon (DOC and DIC, respectively) concentrations collected over the four main hydrological seasons allowed us to assess the current C biogeochemical status of these water bodies in order to judge possible future changes under climate warming. We further tested the impact of permafrost, river watershed size, lake area and climate parameters as well as ‘internal’ biogeochemical drivers (pH, mineralization, organic matter quality and bacterial population) on CO2 concentration and emissions in lakes and rivers of this region and compared them with available data from other subarctic and mountain settings. We found strong environmental control of the CO2 pattern in the studied water bodies, with thermokarst lakes being drastically different from other lakes. In freshwater lakes, pCO2 negatively correlated with O2, whereas the water temperature exerted a positive impact on pCO2 in large rivers. Overall, the large complexity of counteracting external and internal drivers of CO2 exchange between the water surfaces and the atmosphere (CO2-rich underground DIC influx and lateral soil and subsurface water; CO2 production in the water column due to dissolved and particulate OC biodegradation; CO2 uptake by aquatic biota) precluded establishing simple causalities between a single environmental parameter and the fCO2 of rivers and lakes. The season-averaged CO2 emission flux from the rivers of Tyva measured in this study was comparable, with some uncertainty, to the C uptake fluxes from terrestrial ecosystems of the region, which were assessed in other works.

Using Film-Mulched Drip Irrigation to Improve the Irrigation Water Productivity of Cotton in the Tarim River Basin, Central Asia

Climate change has significantly influenced water resource patterns in arid regions. Applying effective water-saving measures to improve irrigation efficiency and evaluate their future water-saving capabilities is crucial for ensuring the sustainable development of irrigation agriculture. Based on the daily meteorological data from 15 global climate models (GCMs) in the sixth phase of the Coupled Model Intercomparison Project (CMIP6), this study used the AquaCrop model to perform high-resolution (0.1° × 0.1°) grid simulations of cotton yields and irrigation requirements. The study also investigated the ability of film-mulched drip irrigation (FMDI) to improve future irrigation efficiency under two shared socio-economic pathways (SSP245 and SSP585) in the Tarim River Basin (TRB), Central Asia, from 2025 to 2100. The results showed that the cotton yield and irrigation water productivity (WPI) in the TRB exhibited an upward trend of 13.82 kg/ha/decade (80.68 kg/ha/decade) and 0.015 kg/m3/decade (0.068 kg/m3/decade), respectively, during the study period. The cotton yield and WPI were higher in the northern, northwestern plains, and northeastern intermountain basin areas, where they reach over 4000 kg/ha and 0.8 kg/m3/decade. However, the cotton yield and WPI were lower in the southwestern part of the study area. Therefore, large-scale cotton production was not recommended there. Furthermore, compared to flood irrigation, the use of FMDI can, on average, improve the WPI by approx. 25% and reduce irrigation water requirements by more than 550 m3/ha. Therefore, using FMDI can save a substantial amount of irrigation water in cotton production, which is beneficial for improving irrigation efficiency and ensuring the future stable production of cotton in the TRB. The research results provide a scientific reference for the efficient utilization and management of water resources for cotton production in the TRB and in similar arid regions elsewhere in the world.

Decoupling external forcings during the development of Miocene fluvial stratigraphy of the North Patagonian Foreland

AbstractThe Patagonian Andean foreland system includes several intermountain basins filled with a Miocene non‐marine record deposited under syn‐tectonic conditions related to the Andean uplift and a regional climate change triggered by a rain shadow effect. Many of those basins, such as the Collón Cura basin in Neuquén Province, Argentina, present a well‐preserved fluvial record (i.e. the Limay Chico Member of the Caleufú Formation). Sedimentological and palaeomagnetic studies have allowed the interpretation of coeval transverse distributary fan and axial mixed‐load fluvial systems deposited between 10.6 ± 0.2 and 12.8 Ma. The basin infill arrangement shows that, while the axial mixed‐load fluvial system exhibits an aggradational stacking pattern, the transverse distributary fluvial fan system denotes three different orders of stratigraphic patterns: (i) large‐scale progradation of the transverse fluvial fan system over a time scale of 106 year; (ii) intermediate‐scale progradational–retrogradational transverse intra‐basinal fluvial fan episodes over a time scale of 105 year; and (iii) small‐scale transverse lobe progradation over a time scale of 105–104 year. These patterns were interpreted as transverse sediment flux variations triggered by variable external forcings. To decouple those forcings, we estimated the Collón Cura basin equilibrium time at 3–5 × 105 year and compared it with the time scale over which different external forcings varied in the Patagonian Andean and foreland regions during Miocene times. Large‐scale progradation is linked to an increase in sediment flux triggered by a long‐term tectonically driven exhumation forcing associated with the Miocene Patagonian Andean contractional phase. Intermediate‐scale progradational–retrogradational episodes are linked to variations in sediment flux due to a mid‐term tectonic forcing associated with the western fault system activity. The small‐scale fan lobe progradation is related to increases in sediment flux triggered by indistinguishable short‐term autogenic processes and/or high‐frequency tectonic and climatic forcings. This contribution shows the applicability and limitations of the basin equilibrium time concept to decouple external forcings from the geological record, considering their magnitude, nature and time scale, as well as the basin characteristics.

The Neotectonics and Geological Structure of the Sevan Intermountain Basin (Armenia): New Structural and Palaeontologic Data

The Neotectonics and Geological Structure of the Sevan Intermountain Basin (Armenia): New Structural and Palaeontologic Data

Control of Structural Landform Evolution on Karst Groundwater Cycle in a Large-Scale Anticlinorium.

Structural landform evolution and hydrogeochemical analyses are crucial for understanding the characteristics of karst groundwater systems and the development of deep karst formed by complex aquifers in a tectonic collision zone. Detailed structural landform evolution analysis was carried out along the large-scale anticlinorium to investigate the temporal evolution of karst aquifer systems and karstification. Results showed that the tectonic activity included weak horizontal compression and slow vertical uplift during the Triassic to Middle Jurassic, forming a denuded clastic platform. This period was mainly preserved in the geological record as burial karst. From the Late Jurassic to the Early Cretaceous, the study area was strongly compressed by S-N-trending stress, and developed E-W-trending high-angle imbricate thrust structures, which controlled the formation of folded and fault-blocked mountains. Vertical multilayered strata underwent a strong horizontal extrusion, forming a large-scale anticlinorium with secondary folds and faults. With the exposure of carbonate rocks due to rapid crustal uplift, karst began to develop, forming a vertical multilayer karst aquifer system and controlling the distribution of karst groundwater. The Fangxian faulted basin was formed from the Late Cretaceous to the Paleogene, whereby landforms were dominated by intermountain basins. Slow crustal uplift caused the retreat of the denudation line to the east, leading to an increase in hydrodynamic conditions and karstification, and the initiation of early karst groundwater systems. Since the Neogene, intermittent and rapid crustal uplift has led to the deepening of rivers, resulting in the formation of peak clusters and canyons, the development of deep karst, and the complete formation of karst groundwater systems. Combined with hydrogeochemical and borehole data, local, intermediate, and regional karst groundwater systems were identified. It has vital significance to the geological route selection or construction of deep-buried tunnels and the utilization of karst groundwater.

Neotectonics and Geological Structure of the Sevan Intermountain Basin (Armenia): New Structural and Paleontological Data

The article presents new data obtained as a result of field research in 2022 Sevan intermountain depression in Armenia. The emergence of the Sevan intermountain depression in the Miocene was associated with the development of the Sevan almond-shaped structure, bounded by the right-lateral Pambak‒Sevan‒Syunik fault zone in the northeast, the Garni zone in the south, and the Arpa‒Zangezur zone in the southwest. Within the Sevan almond-shaped structure, strike-slip structures of Small Sevan (western part of Lake Sevan) and Gavar almond-shaped structure, Gavar horst, a number of faults, as well as extension zones were formed, including the southern part of Greater Sevan (eastern part of Lake Sevan) and axial zone of the Geghama Range. The development of the Sevan intermountain depression continued in the Pliocene under the influence of the uplift of the Lesser Caucasus and the Armenian Highlands. We have summarized the available data on the geological structure and geodynamics of the Sevan intermountain depression, presented the obtained data on the stratigraphy of the Pliocene–Quaternary deposits and their position, and showed that during the Akchagyl transgression at the Pliocene–Pleistocene boundary, sedimentary accumulations did not occur in the Sevan intermountain depression.

Transformation of Paddy Field Use in Intermountain-Type Basins Using Evidence from the Structure and Function Perspective of Karst Mountain Areas in Southwest China

China’s southwestern karst area exhibits many mountains and little flat lands, and intermountain basins (IBs) (locally named “bazi”) are one of their typical landform types. Comparative studies on land use in the core of typical landforms in karst mountain areas are relatively lacking. Studying the evolution and transformation patterns of intermountain basin paddy fields use (IBPFU) to optimize land resources in mountainous areas is important. Based on structural and functional perspectives, this study established a research framework on the evolution and transformation of IBPFU in karst mountainous areas, and analyzed the evolution and transformation patterns of IBPFU in Guizhou Province from 1966 to 2020 by measuring land use change and applying the moving window method and morphological spatial pattern analysis (MSPA) model. The study showed that the evolution of IBPFU is characterized by reversibility and irreversibility, diversity, and stages. The transition of IBPFU requires a trade-off among regional socioeconomic development, ecological protection, and food security. The commonality of land use transitions in IB and sloped land (SL) is reflected in the diversity of their land use functions. This study provides a reference for a comprehensive understanding of land use transitions and sustainable development in the mountainous karst regions of southwest China by providing in-depth examinations of the land use transition of IB, which is different from SL, via the long time series evolution of core land use types. The research framework and research method constructed here also apply to other regions.

NEW RESULTS OF MULTIDISCIPLINARY STUDIES OF MAJOR PLEISTOCENE CLIMATIC EVENTS: GLACIATIONS, FORMATION OF ICE-DAMMED LAKES AND THEIR CATACLYSMIC DRAINING IN ALTAI (MOUNTAINS OF SOUTHERN SIBERIA)

Application of geological geomorphological and geochronological (14C, OSL) methods allowed to establish that the bordering mountains of the Chuya basin (Russian Altai) were affected by glaciation already in the Middle Pleistocene – about 160–180 ka ago (MIS 6). However, the maximal ice-dammed lake with the highest (up to 2100 m a.s.l.) strandlines both in the Chuya and Kurai basins existed later than 90–80 ka ago, in the Late Pleistocene. This chronological benchmark limits the influence of the cataclysmic outburst floods from the largest ice-dammed lakes on the accumulation of the Inya formation in the Chuya and Katun river valleys. It is confirmed that a large ice-dammed lake existed and had a water level of at least 1730 m a.s.l. in MIS 2 in the Kurai basin. It was drained no later than 16 ka ago. Synchronously (about 17–16 ka ago) the accumulation of diluvial-lacustrine cyclites began in the Inya mouth. The Saldzhar formation had been depositing as a result of not only flood events, but also gradual hydrological processes in the Katun river valley between the mouths of the Chuya and Sema rivers during the entire MIS 2. It is necessary to revise the concept adopted by SibRISC in 2018. This concept assumes i) absence of ice-dammed lakes in intermountain basins of the Russian Altai in MIS 2 and ii) accumulation of the Inya and Saldzhar formations deposited by glacial megafloods in the valleys of the Chuya and Katun rivers before 90 ka ago.

Yedoma sediments with gravel and rock debris inclusions: Characteristics and origin

AbstractYedoma ice complex sediments with large syngenetic ice wedges (IW) are usually observed in outcrops in river valleys on permafrost plains and on sea coasts and lake shores in the north of Siberia, Alaska, and Canada. Less frequently, they occur in mountainous and foothill regions of East Siberia, for example, in the Upper Kolyma Upland and in river valleys of the Eastern Sayan Range and the Anabar Plateau, as well as in Alaska and Yukon. The author's materials on gravelly Yedoma with IWs in the intermountain basins, on mountain slopes, and on sea coasts and lake shores are presented. The obtained data allow a conclusion that gravelly Yedoma has mainly alluvial, lacustrine, and colluvial origins with an insignificant participation of aeolian processes. Occurrence of the late Pleistocene gravelly deposits with large syngenetic IWs confirms a hypothesis of polygenetic origin of Yedoma.