Late Pleistocene-Holocene tectonic asymmetry of the Lena Delta

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 “Lena” were used. In 2013, 2014, 2015 surface morphology of the biggest delta’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’ 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>

A Hypothesis for the Sawlike Pattern of World Sea-Level Fluctuations

1985 ◽  
Vol 24 (3) ◽  
pp. 285-294 ◽  
Author(s):  
A. B. Kazanskiy
Keyword(s):  
Sea Level ◽  
Late Pleistocene ◽  
Theoretical Curve ◽  
Ocean Water ◽  
Surface Evaporation ◽  
Sea Level Fluctuations ◽  
Two Parameters ◽  
Continental Glaciation ◽  
The Last Glacial Maximum ◽  
The Last Glacial

A theory of the world's sea-level fluctuations during late Pleistocene time, based on the analysis of the general equation of the mass balance between ocean water and inland water, suggests that the exchange of water masses between the ocean and the land, where at continental glaciation periods water is stored as ice, occurs only as a result of global climatic changes. The tectonic effect is considered insignificant for late Pleistocene time. The proposed theory explains the asymmetric character and the sawlike shape of the curve of the main cycles of sea-level fluctuations. The theory also makes it possible to construct a diagram of sea-level fluctuations from the last glacial maximum to the present time. This diagram is governed by two parameters, the amount of the average “effective” evaporation from the world's ocean surface (evaporation minus rainfall) and the rate of the sea-level rise at the present time. The resulting theoretical curve agrees well with known estimates of sea level within the time span being considered. The comparison of the theoretical curve with these estimates eliminates the apparent discrepancy between data obtained by different methods: measurements of old coastline and the isotopic composition of bottom sediments.

Sedimentary evolution of a Late Pleistocene temperate red algal reef (Coralligène) on Rhodes, Greece: correlation with global sea-level fluctuations

Sedimentology ◽  
2008 ◽  
Vol 55 (6) ◽  
pp. 1747-1776 ◽  
Author(s):  
JÜRGEN TITSCHACK ◽  
CAMPBELL S. NELSON ◽  
TIM BECK ◽  
ANDRÉ FREIWALD ◽  
ULRICH RADTKE
Keyword(s):  
Sea Level ◽  
Late Pleistocene ◽  
Sea Level Fluctuations ◽  
Sedimentary Evolution ◽  
Red Algal ◽  
Global Sea Level ◽  
Algal Reef

scholarly journals Geomorphological structure and neotectonics of the Lena delta

2019 ◽  
Vol 65 (2) ◽  
pp. 186-200
Author(s):  
D. Y. Bolshiyanov ◽  
A. O. Aksenov ◽  
A. S. Makarov ◽  
E. I. Lazareva ◽  
S. A. Pravkin ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Flow Direction ◽  
Radiocarbon Dates ◽  
Lena River ◽  
Speed Difference ◽  
Main Flow Direction ◽  
Lena River Delta ◽  
Tectonic Movements ◽  
Lena Delta ◽  
Observation Period

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.

Sea-Level History, 45,000 to 30,000 yr B.P., Inferred from Benthic Foraminifera, Gulf St. Vincent, South Australia

1988 ◽  
Vol 29 (2) ◽  
pp. 153-175 ◽  
Author(s):  
John H. Cann ◽  
Antonio P. Belperio ◽  
Victor A. Gostin ◽  
Colin V. Murray-Wallace
Keyword(s):  
Sea Level ◽  
Late Pleistocene ◽  
Water Depth ◽  
Benthic Foraminifera ◽  
Size Fraction ◽  
South Australia ◽  
Sea Levels ◽  
Radiocarbon Age ◽  
Sediment Size ◽  
Shallow Water Species

Surficial sediments of Gulf St. Vincent, South Australia, are predominantly bioclastic, cool-temperate carbonates. Benthic foraminifera are abundant and distribution of species is closely related to water depth. For example, Massilina milletti is most common at depths ca. 40 m, while Discorbis dimidiatus is characteristics of shallow, subtidal environments. Elphidium crispum, a shallow-water species, and E. macelliforme, favoring deeper water, provide a useful numerical ratio. Their logarithmic relative abundance, in the sediment size fraction 0.50–0.25 mm, correlates strongly with water depth. Vibrocores SV 4 and SV 5 recovered undisturbed sections of Quaternary strata from the deepest part (ca. 40 m) of Gulf St. Vincent. Amino acid racemization and radiocarbon age determinations show that late Pleistocene sections of the cores were deposited over the time ca. 45,000 to 30,000 yr B.P. Species of fossil foraminifera, recovered from these sections, are mostly extant in modern Gulf St. Vincent, thus allowing paleoecological inferences of late Pleistocene sea levels. These inferred sea-level maxima can be correlated with those determined from study of Huon Peninsula coral reef terraces. Initial estimates of tectonically corrected sea levels for transgressions in Gulf St. Vincent at 40,000 and 31,000 yr B.P. are −22.5 m and −22 m, respectively. The intervening regression lowered sea level to −28 m.

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