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Ice advance-retreat sediment successions along the Logata River, Taymyr Peninsula, Arctic Siberia

Bernhardson, Martin LU (2013) In Dissertations in Geology at Lund University GEOR02 20131
Department of Geology
Abstract
A number of sites were investigated in river sections along the Logata River on the Taymyr Peninsula, Russia, and its adjacent areas to shed more light on the glaciation history over the last glacial cycles. The sediments exposed at the investigated sites are correlated and put into a local stratigraphic scheme divided into five main units.

Unit 1 is positioned lowest in the stratigraphy and consists of greyish yellow sand with gravel horizons made up of shale. The poor exposure of the unit obstructs any attempt to interpret the depositional environment of the unit.

Unit 2 is a matrix-supported silty clayey diamicton with glaciotectonic lamination and sand boudins; it is interpreted as a subglacial traction till deposited from NE.
... (More)
A number of sites were investigated in river sections along the Logata River on the Taymyr Peninsula, Russia, and its adjacent areas to shed more light on the glaciation history over the last glacial cycles. The sediments exposed at the investigated sites are correlated and put into a local stratigraphic scheme divided into five main units.

Unit 1 is positioned lowest in the stratigraphy and consists of greyish yellow sand with gravel horizons made up of shale. The poor exposure of the unit obstructs any attempt to interpret the depositional environment of the unit.

Unit 2 is a matrix-supported silty clayey diamicton with glaciotectonic lamination and sand boudins; it is interpreted as a subglacial traction till deposited from NE.

Unit 3 consists of intercalated massive and laminated beds of silt and clay with a varying abundance of marine molluscs and drop clasts (IRD). The unit is interpreted as deposited in an off-shore glaciomarine depositional environment.

Unit 4 is made up of sorted sediments, primarily sand, but also coarser and finer sediments. Organic detritus is common in the unit. Unit 4 is interpreted as a fluvial depositional environment of a meandering river.

Unit 5 is the uppermost unit in the local stratigraphic scheme and contains properties typical of so called ice complex deposits; it consists of sorted sediments of silt and sand with peat inclusions and an abundance of ground ice. Organic detritus and mega fauna fossils are common in the unit.

The sites examined in detail were sampled for radiocarbon, OSL and ESR dating. All radiocarbon datings (13) on mollusc shells and organic macro remains yield infinite ages, while the results from the ESR and OSL datings are still pending. All units together suggest a full glacial-deglaciation cycle with a Kara Sea ice sheet advancing and retreating within a marine basin, and with an isostatically driven regression thereafter, ending with a terrestrial environment. The most probable timing is the Early Weichselian (100-80 kyr BP). (Less)
Abstract (Swedish)
Ett antal flodskärningar undersöktes längs Logatafloden och dess omkringliggande områden för att ge en ökad förståelse om de senaste istiderna för denna del av världen. De påträffade sedimenten vittnade om en marin miljö efter en isframstöt och därefter en landhöjning som ledde till dagens flod- och tundralandskap.

Det finns många teorier angående hur utbredd inlandsisen var över arktiska Sibirien under Weichselistiden (ca 115 000 – 11 700 år sedan). Detta gäller särskilt den senare delen av istiden där vissa teorier förespråkar ett gigantiskt istäcke över större delen av Arktis, medan andra föreslår ett mycket mindre istäcke, framförallt över Sibirien.

En internationell forskningsexpedition tillbringade närmare två månader på... (More)
Ett antal flodskärningar undersöktes längs Logatafloden och dess omkringliggande områden för att ge en ökad förståelse om de senaste istiderna för denna del av världen. De påträffade sedimenten vittnade om en marin miljö efter en isframstöt och därefter en landhöjning som ledde till dagens flod- och tundralandskap.

Det finns många teorier angående hur utbredd inlandsisen var över arktiska Sibirien under Weichselistiden (ca 115 000 – 11 700 år sedan). Detta gäller särskilt den senare delen av istiden där vissa teorier förespråkar ett gigantiskt istäcke över större delen av Arktis, medan andra föreslår ett mycket mindre istäcke, framförallt över Sibirien.

En internationell forskningsexpedition tillbringade närmare två månader på Tajmyrhalvön i Ryssland under sommaren 2012. En del av denna tid spenderades längs Logatafloden söder om Byrrangabergen där ett flertal flodskärningar undersöktes. En mängd prover togs för att kunna åldersbestämma sedimenten från flodskärningarna, varav bara AMS <sup>14</sup>C-dateringarna, dvs. datering av organiskt material, användes i den här uppsatsen.

Sedimenten från flodskärningarna vittnade om ett landskap som en gång var täckt av en inlandsis och som därefter översvämmades av havsvatten när isen drog sig tillbaka. Den efterföljande landhöjningen gjorde att den marina miljön övergick till det flod- och tundralanskap som går att se idag. De marina sedimenten innehöll en fauna som trivs i arktiskt vatten, medan de yngre sedimenten innehöll fossil av megafauna, såsom mammut.

Samtliga dateringar var äldre än maxåldern för dateringsmetoden, dvs. >45 000 år. Detta innebär att inlandsisen antagligen härstammar från början av Weichselistiden, ca 100 000 – 80 000 år sedan. Dessa fynd bestrider att Tajmyrhalvön ska ha varit täckt av ett gigantiskt istäcke under slutet av denna istid, ca 20 000 år sedan. (Less)
Please use this url to cite or link to this publication:
author
Bernhardson, Martin LU
supervisor
organization
alternative title
Isframstötar och isreträtter längs Logatafloden, Tajmyrhalvön, arktiska Sibirien : en sedimentologisk och stratigrafisk studie
course
GEOR02 20131
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Sibirien, Tajmyrhalvön, Weichselian glaciation, Ice advance-retreat stages, Russia, Taymyr Peninsula, Siberia, Ryssland, isframstötar-isreträtter, Weichselistiden
publication/series
Dissertations in Geology at Lund University
report number
332
language
English
id
3625623
date added to LUP
2013-03-26 14:16:41
date last changed
2013-03-26 14:16:41
@misc{3625623,
  abstract     = {A number of sites were investigated in river sections along the Logata River on the Taymyr Peninsula, Russia, and its adjacent areas to shed more light on the glaciation history over the last glacial cycles. The sediments exposed at the investigated sites are correlated and put into a local stratigraphic scheme divided into five main units. 

Unit 1 is positioned lowest in the stratigraphy and consists of greyish yellow sand with gravel horizons made up of shale. The poor exposure of the unit obstructs any attempt to interpret the depositional environment of the unit. 

Unit 2 is a matrix-supported silty clayey diamicton with glaciotectonic lamination and sand boudins; it is interpreted as a subglacial traction till deposited from NE.

Unit 3 consists of intercalated massive and laminated beds of silt and clay with a varying abundance of marine molluscs and drop clasts (IRD). The unit is interpreted as deposited in an off-shore glaciomarine depositional environment. 

Unit 4 is made up of sorted sediments, primarily sand, but also coarser and finer sediments. Organic detritus is common in the unit. Unit 4 is interpreted as a fluvial depositional environment of a meandering river. 

Unit 5 is the uppermost unit in the local stratigraphic scheme and contains properties typical of so called ice complex deposits; it consists of sorted sediments of silt and sand with peat inclusions and an abundance of ground ice. Organic detritus and mega fauna fossils are common in the unit. 

The sites examined in detail were sampled for radiocarbon, OSL and ESR dating. All radiocarbon datings (13) on mollusc shells and organic macro remains yield infinite ages, while the results from the ESR and OSL datings are still pending. All units together suggest a full glacial-deglaciation cycle with a Kara Sea ice sheet advancing and retreating within a marine basin, and with an isostatically driven regression thereafter, ending with a terrestrial environment. The most probable timing is the Early Weichselian (100-80 kyr BP).},
  author       = {Bernhardson, Martin},
  keyword      = {Sibirien,Tajmyrhalvön,Weichselian glaciation,Ice advance-retreat stages,Russia,Taymyr Peninsula,Siberia,Ryssland,isframstötar-isreträtter,Weichselistiden},
  language     = {eng},
  note         = {Student Paper},
  series       = {Dissertations in Geology at Lund University},
  title        = {Ice advance-retreat sediment successions along the Logata River, Taymyr Peninsula, Arctic Siberia},
  year         = {2013},
}