Geomorphological structure and neotectonics of the Lena delta

New data about geomorphological structure and neotectonic movements of the Lena Delta is presented. Thet are based on results of the Russian-German expeditions Lena-2013, Lena-2014, Lena-2015 and Lena-2018 and include geomorphological profiling with high quality satellite instruments and a number of radiocarbon dates on the Sobo-Sise, Kurungnakh, Jangylakh-Sis and Khardang-Sise islands. These islands consist of the Late Pleistocene Ice Complex (IC) remnants eroded by river and sea, and the first terrace of the Delta, which adjoins the remnants. The first terrace started to form 8,000 years ago in the western part of the Delta and was finally formed in the last millennium in the eastern part of the Delta. From the previous works, it is known that the western part of the Delta is higher than the eastern part. In our work, we explain it by the eneven movements of the Earth’s crust in this region. The aim of the paper is to study the quantitative characteristics of the tectonic movements in the Lena River Delta. For this purpose we present the geomorphological schemes and descriptions of the islands mentioned and compare the terraces heights in the different parts of the Delta. In the Late Pleistocene, according to the heights of the IC remnants, the western part of the Delta rose 1 mm per year faster than its eastern part. In the Holocene the speed difference increased to approximately 2 mm per year, which is shown by the terrace surface’s altitude. The amplitude between the western and eastern parts of this surface is about 4 m. Finally, according to 60-years observation period of the water level in the Laptev Sea, the modern speed difference of the western and eastern parts movement in the Lena Delta is 2 mm per year. As a result, we can observe changes in the main flow direction in the Delta channels from the Olenekskaya branch at the beginning of Holocene to the Bykovskaya branch today.

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Lithology and palynology of neogene-quaternary sediments of Sardakh island (the Lena river delta)

Недропользование. Горное дело. Направления и технологии поиска, разведки и разработки месторождений полезных ископаемых. Экономика. Геоэкология: Материалы XVI международной конференции (20-24 апреля 2020, Новосибирск) ◽

10.18303/b978-5-4262-0102-6-2020-011 ◽

2020 ◽

Author(s):

Andrei A. Kartoziia ◽

◽

Olga B. Kuzmina ◽

Irina V. Khazina ◽

Leonid B. Khazin ◽

...

Keyword(s):

Structure Analysis ◽

Late Miocene ◽

Taxonomic Composition ◽

Middle Part ◽

Early Pleistocene ◽

Quaternary Sediments ◽

Quaternary Deposits ◽

Lena River ◽

Lena River Delta ◽

Lena Delta

Results of the study of Neogene-Quaternary deposits of Sardakh Island (the Lena Delta) are described here. Taxonomic composition and spore-pollen spectra structure analysis indicated that sandstones, which are located in the section bottom have middle-late Miocene age. The middle part of the studied section has a Pliocene - early Pleistocene age. The upper part has a late Pleistocene age. We assume that sediments were deposited in the river environments.

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Late Pleistocene-Holocene tectonic asymmetry of the Lena Delta

10.5194/egusphere-egu2020-2749 ◽

2020 ◽

Author(s):

Aleksei Aksenov ◽

Dmitriy Bolshiyanov ◽

Aleksandr Makarov ◽

Sergei Pravkin ◽

Elena Lazareva ◽

...

Keyword(s):

Sea Level ◽

Late Pleistocene ◽

High Quality ◽

Flow Measurements ◽

Radiocarbon Age ◽

Speed Difference ◽

Sea Level Fluctuations ◽

Digital Elevation ◽

Geophysical Investigations ◽

Lena Delta

<p>The Lena Delta is the largest arctic delta in the world (about 29000 km<sup>2</sup>). Unlike other deltas, its formation was the result of both erosion and accumulation during Late Pleistocene and Holocene. It was caused by combination of continuous sea-level fluctuations and neotectonic movements. The last ones have different speed and direction. From previous studies it is known that western part of delta has uprising tectonic movements while the eastern one is sinking. This asymmetry develops along the fracture extended submeridially across the delta. The aim of this research is to measure the amplitude and speed of these movements by using geomorphologic methods. For that purpose results of German-Russian expedition &#8220;Lena&#8221; were used. In 2013, 2014, 2015 surface morphology of the biggest delta&#8217;s islands Sobo-Sise, Kurungnakh, Jangylakh-Sis and Khardang-Sise located in both eastern and western parts was investigated with high-quality sattelite instruments. These islands consist of the Late Pleistocene Ice Complex (IC) remnants with altitude 20-66 m above sea-level (a.s.l.), eroded by river and sea, and the first accumulative terrace of the delta with 2-15 m a.s.l. IC remnants accumulated in the Late Pleistocene 50-17 ka cal BP. The first terrace was forming in Holocene from 8 ka cal BP to 2 ka cal BP. So, there were made a number of geomorphologic profiles with use of high-quality satellite instruments across river terrace and IC remnants during the expeditions. In this study, we equated them to one level and compared. With use of radiocarbon age and digital elevation models (DEM) data we compared heights and age of islands in eastern and western parts and estimated neotectonic movements&#8217; speed difference. Since 2000 years BP tectonic asymmetry represented in terrace surfaces has been increasing with rate about 2 mm per year. Before 2000 cal BP speed difference approximately values 1 mm per year. Our data correlates with water-flow measurements in the delta, modern water-level observations in Laptev Sea and geophysical investigations.</p>

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The cryostratigraphy of the Yedoma cliff of Sobo-Sise Island (Lena delta) reveals permafrost dynamics in the central Laptev Sea coastal region during the last 52 kyr

The Cryosphere ◽

10.5194/tc-14-4525-2020 ◽

2020 ◽

Vol 14 (12) ◽

pp. 4525-4551

Author(s):

Sebastian Wetterich ◽

Alexander Kizyakov ◽

Michael Fritz ◽

Juliane Wolter ◽

Gesine Mollenhauer ◽

...

Keyword(s):

Late Pleistocene ◽

Coastal Region ◽

The Arctic ◽

Laptev Sea ◽

Coarse Silt ◽

Lena River ◽

Mis 3 ◽

D Values ◽

Δ18o And Δd ◽

Lena Delta

Abstract. The present study examines the formation history and cryolithological properties of the late-Pleistocene Yedoma Ice Complex (IC) and its Holocene cover in the eastern Lena delta on Sobo-Sise Island. The sedimentary sequence was continuously sampled at 0.5 m resolution at a vertical Yedoma cliff starting from 24.2 m above river level (a.r.l.). The sequence differentiates into three cryostratigraphic units: Unit A, dated from ca. 52 to 28 cal kyr BP; Unit B, dated from ca. 28 to 15 cal kyr BP; Unit C, dated from ca. 7 to 0 cal kyr BP. Three chronologic gaps in the record are striking. The hiatus during the interstadial marine isotope stage (MIS) 3 (36–29 cal kyr BP) as well as during stadial MIS 2 (20–17 cal kyr BP) might be related to fluvial erosion and/or changed discharge patterns of the Lena river caused by repeated outburst floods from the glacial Lake Vitim in southern Siberia along the Lena river valley towards the Arctic Ocean. The hiatus during the MIS 2–1 transition (15–7 cal kyr BP) is a commonly observed feature in permafrost chronologies due to intense thermokarst activity of the deglacial period. The chronologic gaps of the Sobo-Sise Yedoma record are similarly found at two neighbouring Yedoma IC sites on Bykovsky Peninsula and Kurungnakh-Sise Island and are most likely of regional importance. The three cryostratigraphic units of the Sobo-Sise Yedoma exhibit distinct signatures in properties of their clastic, organic, and ice components. Higher permafrost aggradation rates of 1 m kyr−1 with higher organic-matter (OM) stocks (29 ± 15 kg C m−3, 2.2 ± 1.0 kg N m−3; Unit A) and mainly coarse silt are found for the interstadial MIS 3 if compared to the stadial MIS 2 with 0.7 m kyr−1 permafrost aggradation, lower OM stocks (14 ± 8 kg C m−3, 1.4 ± 0.4 kg N m−3; Unit B), and pronounced peaks in the coarse-silt and medium-sand fractions. Geochemical signatures of intra-sedimental ice reflect the differences in summer evaporation and moisture regime by higher ion content and less depleted ratios of stable δ18O and stable δD isotopes but lower deuterium excess (d) values during interstadial MIS 3 if compared to stadial MIS 2. The δ18O and δD composition of MIS 3 and MIS 2 ice wedges shows characteristic well-depleted values and low d values, while MIS 1 ice wedges have elevated mean d values between 11 ‰ and 15 ‰ and surprisingly low δ18O and δD values. Hence, the isotopic difference between late-Pleistocene and Holocene ice wedges is more pronounced in d than in δ values. The present study of the permafrost exposed at the Sobo-Sise Yedoma cliff provides a comprehensive cryostratigraphic inventory, insights into permafrost aggradation, and degradation over the last approximately 52 kyr as well as their climatic and morphodynamic controls on the regional scale of the central Laptev Sea coastal region in NE Siberia.

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The first data on the late pleistocene ostracodes of the Kuray depression (Gorny Altai)

Доклады Академии наук ◽

10.31857/s0869-56524864451-454 ◽

2019 ◽

Vol 486 (4) ◽

pp. 451-454

Author(s):

L. B. Khazin ◽

A. R. Agatova ◽

R. K. Nepop ◽

B. N. Shurygin

Keyword(s):

Late Pleistocene ◽

Middle Miocene ◽

Deciduous Trees ◽

Deciduous Species ◽

Mixed Forests ◽

Lena River ◽

Gorny Altai ◽

Field Works ◽

Trees And Shrubs ◽

Lena River Delta

During the field works in the summer of 2018, in the Lena River delta on the Sardakh-Sisse Island, prints of leaf flora belonging to species of broad and small-leaved deciduous trees were found. The prints found by us are confined to the layer of ferruginous sandstones at the base of the section. The following taxa established: Platanus sp., Alnus sp., Fagus sp., Salix sp. In addition, a fossilized fruit belonging to Magnolia sp. The findings allow to conclude that there are mixed forests in the early-middle Miocene in this region, consisting of coniferous, small- and broad-leaved deciduous species of trees and shrubs.

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The occurrence of the new zooplankton species in the Lena river delta

Proceedings of the Zoological Institute RAS ◽

10.31610/trudyzin/2016.320.4.473 ◽

2016 ◽

Vol 320 (4) ◽

pp. 473-487

Author(s):

E.N. Abramova ◽

I.A. Zhulay

Keyword(s):

Local Population ◽

Spring Tide ◽

Passive Dispersal ◽

Zooplankton Species ◽

Local Fauna ◽

Lena River ◽

Water Ecosystems ◽

Sida Crystallina ◽

Lena River Delta ◽

Observation Period

The Lena River impact on the water bodies of its catchment area increases in connection of climate warming. During spring floods the river water enters the numerous floodplain water basins, further promotes the passive dispersal of their fauna in the northern direction. The occurrences of new (for the local fauna) zooplankton species repeatedly documented in the lakes on Samoylov Island in the south part of the Lena Delta over the last 15 years. Seven “invasive species” belong to Cladocera, four to Copepoda and one species of Rotifera. Some cladocerans –Sida crystallina (O.F. Muller, 1776), Limnosida frontosa (Sars, 1862), Diaphanasoma brachyurum (Lievin, 1848) and Polyphemus pediculus (Linnaeus, 1761) – several times appeared and disappeared in the floodplain aquatic habitats on Samoilovsky Island during the observation period. Simocephalus vetulus (O.F. Muller, 1776) found conditions here to be favorable and formed the local population in the floodplain pools. Acroperus harpae (Baird, 1834) and Holopedium gibberum Zaddach, 1855 started to settle from low floodplain in neighboring water ecosystems of the first delta terrace with a height of 10–16 m. The spread of resting stages of zooplankton are likely to occur with the participation of waterfowl. In years with extremely high spring tide, the expansion of species, not typical for the area, was of a catastrophic nature. A massive invasion of certain species, for example Holopedium gibberum Zaddach, 1855, can cause a rapid restructuring of the lake biocoenosis and disturb the ecological balance in it, resulting in parasitic epizootic.

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The cryostratigraphy of the Yedoma cliff of Sobo-Sise Island (Lena Delta) reveals permafrost dynamics in the Central Laptev Sea coastal region during the last about 52 ka

10.5194/tc-2020-179 ◽

2020 ◽

Cited By ~ 1

Author(s):

Sebastian Wetterich ◽

Alexander Kizyakov ◽

Michael Fritz ◽

Juliane Wolter ◽

Gesine Mollenhauer ◽

...

Keyword(s):

Late Pleistocene ◽

Coastal Region ◽

The Arctic ◽

Laptev Sea ◽

Coarse Silt ◽

Lena River ◽

Mis 3 ◽

D Values ◽

Δ18o And Δd ◽

Lena Delta

Abstract. The present study examines the formation history and cryolithological properties of late Pleistocene Yedoma Ice Complex (IC) and its Holocene cover in the eastern Lena Delta on Sobo-Sise Island. The sedimentary sequence was continuously sampled in 0.5 m resolution at a vertical Yedoma cliff starting from 24.2 m above rivel level (arl). The sequence differentiates into three cryostratigraphic units; unit A: dated from ca. 52 to 28 cal ka BP; unit B: dated from ca. 28 to 15 cal ka BP; unit C: dated from ca. 7 to 0 cal ka BP. Three chronologic gaps in the record are striking. The hiatus during the interstadial MIS 3 (36–29 cal ka BP) as well as during stadial MIS 2 (20–17 cal ka BP) might be related to fluvial erosion and/or changed discharge patterns of the Lena River caused by repeated outburst floods from the glacial Lake Vitim in Southern Siberia along the Lena River valley towards the Arctic Ocean. The hiatus during the MIS 2-1 transition (15–7 cal ka BP) is a commonly observed feature in permafrost chronologies due to intense thermokarst activity of the deglacial period. The chronologic gaps of the Sobo-Sise Yedoma record are similarly found at two neighbouring Yedoma IC sites on Bykovsky Peninsula and Kurungnakh-Sise Island, and most likely of regional importance. The three cryostratigraphic units of the Sobo-Sise Yedoma exhibit distinct signatures in properties of their clastic, organic and ice components. Higher permafrost aggradation rates of 1 m ka-1 with higher organic matter (OM) stocks (29±15 kg C m-3, 2.2±1.0 kg N m-3) and mainly coarse silt are found for the interstadial MIS 3 unit A if compared to the stadial MIS 2 unit B with 0.7 m ka-1 permafrost aggradation, lower OM stocks (14±8 kg C m-3, 1.4±0.4 kg N m-3 in unit B) and pronounced peaks in the coarse silt and medium sand fractions. Geochemical signatures of intrasedimental ice reflect the differences in summer evaporation and moisture regime by higher ion contents and less depleted stable δ18O and δD isotope ratios but lower deuterium excess (d) values during interstadial MIS 3 if compared to stadial MIS 2. The δ18O and δD composition of MIS 3 and MIS 2 ice wedges shows characteristic well-depleted values and low d values, while MIS 1 ice wedges have elevated mean d values between 11‰ and 15‰ and surprisingly low δ18O and δD values. Hence, the isotopic difference between late Pleistocene and Holocene ice wedges is more pronounced in d than in δ values. The present study of the permafrost exposed at the Sobo-Sise Yedoma cliff provides a comprehensive cryostratigraphic inventory, insights into permafrost aggradation and degradation over the last about 52 thousand years, and their climatic and morphodynamic controls on the regional scale of the Central Laptev Sea coastal region in NE Siberia.

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Subrecent Spore-Pollen Spectra and Modern Vegetation from the Lena River Delta, Russian Arctic

Сибирский экологический журнал ◽

10.15372/sej20170407 ◽

2017 ◽

Keyword(s):

River Delta ◽

Russian Arctic ◽

Lena River ◽

Lena River Delta

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Calibration of Radiocarbon Dates for the Late Pleistocene Using U/Th Dates on Stalagmites

Radiocarbon ◽

10.1017/s003382220004087x ◽

1997 ◽

Vol 39 (1) ◽

pp. 27-32 ◽

Cited By ~ 40

Author(s):

John C. Vogel ◽

Joel Kronfeld

Keyword(s):

South Africa ◽

Magnetic Dipole ◽

Satisfactory Agreement ◽

Late Pleistocene ◽

Calibration Curve ◽

Dipole Field ◽

Radiocarbon Dates ◽

The Past ◽

The Earth ◽

Magnetic Dipole Field

Twenty paired 14C and U/Th dates covering most of the past 50,000 yr have been obtained on a stalagmite from the Cango Caves in South Africa as well as some additional age-pairs on two stalagmites from Tasmania that partially fill a gap between 7 ka and 17 ka ago. After allowance is made for the initial apparent 14C ages, the age-pairs between 7 ka and 20 ka show satisfactory agreement with the coral data of Bard et al. (1990, 1993). The results for the Cango stalagmite between 25 ka and 50 ka show the 14C dates to be substantially younger than the U/Th dates except at 49 ka and 29 ka, where near correspondence occurs. The discrepancies may be explained by variations in 14C production caused by changes in the magnetic dipole field of the Earth. A tentative calibration curve for this period is offered.

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