PLEISTOCENE GLACIATIONS OF THE SE ALTAI, RUSSIA, BASED ON GEOMORPHOLOGICAL DATA AND ABSOLUTE DATING OF GLACIAL DEPOSITS IN CHAGAN REFERENCE SECTION

Abstract Geomorphological evidence of at least two Pleistocene glacial epochsis noted within the Chagan-Uzun river basin, SE Altai. A review and analysis of all available absolute dates for reference Chagan section is presented. The highest correlation amongst all TL dates is observed for the lens of glacio-lacustrine sediments – the most suitable among glacial deposits for luminescence dating, and indicates its possible Middle Pleistocene age. IRSL dates obtained from feldspar indicate a Middle Pleistocene age of moraines already in the upper part of the section. The small number of obtained IRSL dates does not allow making geochronological reconstructions of the Pleistocene glaciations, but gives the possibility for further experiments with different variation of OSL (IRSL) techniques. Strong low temperature peak in TL signal and strong response to IR stimulation are specific regional quartz features, which could be explained by combination of short transportation distance and low number of depositional cycles for mineral grains. Available radiocarbon dates of carbonate concretions from this section are not related to the age of moraine sedimentation and most likely indicate the period of the Chagan river incision into the ancient glacial deposits. This study has shown that TL method is not valid for dating glacial sediments and TL dates cannot be utilized as chronostratigraphic markers. Generally, the Chagan section could hardly serve as a reference section for the Altai stratigraphy; available depositional correlation schemes for the Russian Altai and Siberia which are based on several TL dates obtained in the last century needs to be improved.</jats:p

RECURRENCE INTERVAL OF STRONG EARTHQUAKES IN THE SE ALTAI, RUSSIA REVEALED BY TREE-RING ANALYSIS AND RADIOCARBON DATING

Abstract This paper presents the results of paleoseismogeological investigations including tree-ring analysis and radiocarbon dating in pleistoseist zone of the 2003 Chuya earthquake, SE Altai, Russia. Twenty-five radiocarbon dates of previously unknown evidences of prehistoric earthquakes along the fault bounders of the Chagan-Uzun massif, North Chuya and South Chuya ranges are reported. Perspectives of applying dendroseismological approach within the high mountainous seismically active southeastern part of Russian Altai are demonstrated. In addition to estimating the germination ages of trees growing on the bare surfaces of seismically triggered landslides, analysis of wood penetrating injuries in the individual tree ring series was applied for dating paleorock-falls. Analysis of distribution patterns of tree-ring anomalies and injured trees suggests a criterion of recognizing seismic origin of past rock-falls. Dendrochronologically obtained dates of abrupt intensifications of rock-falls can be considered as supposed dates of past earthquakes, which should be verified by alternative proxy data. Obtained results argue for the high regional seismicity in the second half of the Holocene. Strong earthquakes occurred here AD 1532, and 600–700, 1300–1500, 2400–2700, 3400–3700, 3800–4200 cal BP. This data clarifies the chronology of seismic events within the SE Altai. The specified recurrence interval of strong earthquakes is about 400 years during the last 4000 years.</jats:p

New Data on Iron-Smelting Sites in the Kuektanar and Turgun Valleys, Southeastern Altai

This paper presents the findings relating to iron-smelting furnaces in the Kuektanar and Turgun valleys of the Russian Altai, which were part of the Chuya-Kurai metallurgical province and are undergoing rapid erosion. On the Chuya River, downstream of the mouth of the Kuektanar, we discovered hitherto unknown (and completely eroded) remains of furnaces. Radiocarbon dating of charcoal fragments from smelting furnaces (bloomeries) at Kuektanar-1 and 2 and Turgun-1, using both scintillation and AMS techniques, suggests the use of trees that grew in 5th–10th centuries AD as a fuel for metallurgical production. Dates of charcoal relating to the same iron-smelting event differ by over 300 years, probably because various parts of adult larches (Larix sibirica Ledeb.) were used, creating an “old wood” effect. Samples of uncharred bark in bloomery 2 at Kuektanar-1 suggest that the last smelting occurred in 655–765 AD. The totality of radiocarbon dates makes it possible to conclude that the furnaces were active during the Old Turkic period. The proximity of iron ore sources and the abundance of forest vegetation account for the wide use of iron-smelting by the nomads in the region. The erosion of the river bank where the furnaces are located allowed us to assess the erosion rate since their construction to be approximately 0.5 cm per year. © 2018 A.R. Agatova, R.K. Nepop, I.Y. Slyusarenko, V.S. Panov.The study was performed under Public Contract (Project No. 0330-2016-0015); archaeological studies were supported by the Russian Science Foundation (Project No. 14-50-00036), geological and geomorphological studies, including radiocarbon dating, were supported by the Russian Foundation for Basic Research (Project No. 16-05-01035)

Archaeological sites as markers of Neopleistocene-Holocene hydrological system transformation in the Kurai and Chuya basins, Southeastern Altai: Results of geomorphological and geoarchaeological studies

Multidisciplinary studies using geomorphological, geoarchaeological, and geochronological approaches indicate contrasting environmental changes in Southeastern Altai, beginning in the Late Pleistocene. 29 new radiocarbon dates from the subaerial complex overlying Late Neopleistocene sediments in the high-altitude Kurai and Chuya basins confirm the degradation of a single ice-dammed reservoir in that area before the Early Holocene. In the first half of the Holocene, those basins were filled with isolated lakes. At the mouth of the Baratal River in the western Kurai basin, a reservoir with a water-level of at least 1480 m a.s.l. emerged ca 10–6.5 ka cal BP; whereas in the Chuya depression, numerous residual lakes existed at least 8 ka cal BP. Landslide- and moraine-dammed lakes between the depressions in the Chuya River valley existed until 7–3 ka cal BP, when they drained away. The state of preservation of in situ archaeological sites, their cultural affiliation, and their locations within the depressions and along the main Chuya valley attest to spatial and temporal changes in the hydrological system. This evolution in the second half of the Holocene did not entail major consequences for humans. All cataclysmic flood events took place (occurred) before 10–8 ka cal BP. © 2016 A.R. Agatova, R.K. Nepop, I.Y. Slyusarenko, V.S. Myglan, V.V. Barinov.Geomorphological studies, including radiocarbon dating, were supported by the Russian Foundation for Basic Research (Projects No. 15-05-06028 and 16-05-01035); archaeological and dendrochronological studies were supported by the Russian Science Foundation (Projects No. 14-50-00036 and 15-14-30011 respectively)

Археологические памятники как маркер перестройки неоплейстоцен-голоценовой гидросети Курайской и Чуйской впадин (Юго-Восточный Алтай): результаты геолого-геоморфологических и геоархеологических исследований

Multidisciplinary studies using geomorphological, geoarchaeological, and geochronological approaches indicate contrasting environmental changes in southeastern Altai beginning from the Late Pleistocene. Twenty-eight new radiocarbon dates from the subaerial complex overlying Late Neopleistocene sediments in the high-altitude Kurai and Chuya basins confi rm the degradation of a single ice-dammed reservoir in that area during the Early Holocene. In the first half of the Holocene, those basins were filled with isolated lakes. At the Baratal River mouth in the western Kurai basin, a reservoir with a water level of at least 1480 m a.s.l. emerged ca 10-6.5 ka BP, whereas in the Chuya depression, numerous residual lakes had existed at least 8 ka BP. Landslide- and morainedammed lakes between the depressions in the Chuya valley had existed until 7-3 ka BP, when they drained away. The preservation state of in situ archaeological sites, their cultural affiliation, and their location within the depressions and along the main Chuya valley attest to spatial and temporal changes of the hydrological system. This evolution occurred in the second half of the Holocene and did not entail major consequences for humans. © 2016 Siberian Branch of the Russian Academy of Sciences.Geomorphological studies, including radiocarbon dating, were supported by the Russian Foundation for Basic Research (Projects No. 15-05-06028 and 16-05-01035); archaeological and dendrochronological studies were supported by the Russian Science Foundation (Projects No. 14-50-00036 and 15-14-30011 respectively)

Влияние землетрясения 1988 г. на оледенение и рельеф массива Цамбагарав (Западная Монголия)

Early documentation of the consequences of the Tsambagarav earthquake happened on July 23, 1988 (M = 6.4) compiled by Soviet and Mongolian specialists allowed the authors, using the example of Tsambagarav (Mongolian Altai), to assess the impact of the seismic process on the reduction of mountain glaciation and topography of the trough valleys in the arid region of Central Asia. In 1988, in upper part of the Zuslan river valley, 13 days after the earthquake, the release of a fragment of one of the glaciers gave rise to an ice-rock avalanche «on an air cushion». Its deposits with a thickness of up to 30 m blocked the valley over a distance of 5 km. Analysis of space images taken in different time together with field researches revealed that as a result of the earthquake the glacier № 15 simultaneously lost 0.1 km2 of its tongue (10.4% of total area), as the whole in 1988–2015 it lost 56% of its area, whereas neighboring glaciers № 16 and 17, similar in size and the same exposure, lost significantly less – 35 and 15% of the area, respectively. Rapid shrinking of not only the glacier tongue, but also of its accumulation zone; the established deficit of ice volume in the broken off ice fragment (in comparison with initial assessment), and the abnormally long path of the avalanche made it possible to clarify the factors and mechanism of its initiation: the fall of the ice-snow ledge from the accumulation zone could lead to the rapid release of the broken ice fragment in the tongue part of the glacier. In 2004, 16 years after the avalanche, the buried ice in its deposits was still partially preserved, having completely degraded by 2019. The long time of the ice degradation process was caused by the high content (about half of the volume) of debris that armored the surface of avalanche sediments. The debris material of the avalanche repeats the relief of the underlying Pleistocene moraines, which may complicate the reconstruction of the number, scale and age of glacial events in avalanchehazardous areas. The relatively high rate of leveling of the avalanche traces and, as a consequence, the difficulties of their subsequent identification in the relief allow us to assume a greater number of avalanche releases, including seismic ones, in the recent geological past than it can be established at present in the Altai ridges.Ледник № 15 (по [3]), потерявший в результате Цамбагаравского землетрясения 1988 г. магнитудой М = 6,4 фрагмент языка (10,4% всей площади) и часть объёма в области аккумуляции, в период 1988–2015 гг. сократился на 56%, что больше сокращения соседних ледников (15–35%). Погребённый лёд в отложениях ледово-каменной лавины, заполнивших долину р. Зуслан на протяжении 5 км, частично сохранялся и в 2004 г.; полностью он растаял к 2019 г. Обломочный материал лавины повторяет рельеф подстилающих плейстоценовых морен, что может осложнить реконструкцию ледниковых событий в регионе. Уточнены факторы, определившие возникновение лавины на «воздушной подушке»

Geographic Factors of Tourism Development in the Se Altai by the Example of Unique Geomorphological and Archeological Sites in the Chuya Valley

Potential of applying the results of geomorphological and geoarchaeological studies for tourism industry is demonstrated by the example of the Chuya valley between Chuya and Kurai depressions. © 2018 Published under licence by IOP Publishing Ltd.Presented multidisciplinary investigations show the contrasting environmental changes and unique historical heritage of the region, preserved in landforms, sedimentation records and artifacts. Available material can reliably contribute to the development of local tourism industry. Study was partly funded by RFBR (grants 16-05-01035 and 18-05-00998)