Development of the Ósmelur sedimentary sequence in Hvalfjörður, W-Iceland

Sedimentary structures of the Ósmelur sediment formation are studied in this thesis in order to determine its formation and development. Presented are eight stratigraphical sections which were investigated with state-of-the-art field techniques, along with interpretation of aerial images, bathymetri...

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Bibliographic Details
Main Author: Ríkey Júlíusdóttir 1984-
Other Authors: Háskóli Íslands
Format: Thesis
Language:English
Published: 2019
Subjects:
Online Access:http://hdl.handle.net/1946/33556
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record_format openpolar
spelling ftskemman:oai:skemman.is:1946/33556 2023-05-15T16:21:44+02:00 Development of the Ósmelur sedimentary sequence in Hvalfjörður, W-Iceland Myndun Ósmels í Hvalfirði Ríkey Júlíusdóttir 1984- Háskóli Íslands 2019-06 application/pdf http://hdl.handle.net/1946/33556 en eng http://hdl.handle.net/1946/33556 Jarðfræði Ósmelur (Kjósarsýsla) Setlög Thesis Master's 2019 ftskemman 2022-12-11T06:51:44Z Sedimentary structures of the Ósmelur sediment formation are studied in this thesis in order to determine its formation and development. Presented are eight stratigraphical sections which were investigated with state-of-the-art field techniques, along with interpretation of aerial images, bathymetric data, radiometric datings of shells and chemical analyses of tephra. Although the Ósmelur formation represents both vertical and lateral changes in sedimentary facies, five major sedimentary units are recognized along with two glacial deposits. Radiocarbon datings on shells from the lowest and oldest unit yielded a median probability age of 14.191 cal. ka BP. Unit 2 shows signs of a regressive phase, with sandy, fluvial deposits. Unit 3 suggests climate deterioration and transgression of relative sea level, established with Unit 4, which contains radiocarbon dated shells which yielded median probability age of 13.199 cal. ka BP. Unit 5 consists of cobbles and boulders, deposited in a regressive phase in a littoral, high energy environment when isostatic rebound was occurring due to a glacier retreat. A hiatus divides Ósmelur into two parts, a table-shaped one to the west, and a terrace-shaped one to the east. This study reveals that this hiatus was caused by an erosional event, when a glacial river and a glacier from the Miðdalur valley eroded the upper/younger part of the eastern part in late Allerød or early Younger Dryas, leaving glaciofluvial sediments and a meltout till on top of it. This glacier did not reach the western formation, but a glacier from Hvalfjörður fjord reached its shoulder, leaving evidences such as diamicton and striated clasts. Setlög Ósmels voru rannsökuð til að ákvarða um uppbyggingu þeirra. Alls voru átta snið rannsökuð með klassískri aðferðafræði í feltvinnu, þar sem byggingareinkennum einstakra laga er lýst nákvæmlega. Til hliðsjónar var notast við loftmyndir af svæðinu, ásamt hafsbotnskorti, aldursákvörðuðum skeljum og efnagreindri gjósku sem fannst í tveimur sniðum. Mikill ... Thesis glacier Iceland Kjósarsýsla Skemman (Iceland) Hvalfjörður ENVELOPE(-21.663,-21.663,64.376,64.376) Kjósarsýsla ENVELOPE(-21.500,-21.500,64.250,64.250) Miðdalur ENVELOPE(-21.642,-21.642,64.115,64.115)
institution Open Polar
collection Skemman (Iceland)
op_collection_id ftskemman
language English
topic Jarðfræði
Ósmelur (Kjósarsýsla)
Setlög
spellingShingle Jarðfræði
Ósmelur (Kjósarsýsla)
Setlög
Ríkey Júlíusdóttir 1984-
Development of the Ósmelur sedimentary sequence in Hvalfjörður, W-Iceland
topic_facet Jarðfræði
Ósmelur (Kjósarsýsla)
Setlög
description Sedimentary structures of the Ósmelur sediment formation are studied in this thesis in order to determine its formation and development. Presented are eight stratigraphical sections which were investigated with state-of-the-art field techniques, along with interpretation of aerial images, bathymetric data, radiometric datings of shells and chemical analyses of tephra. Although the Ósmelur formation represents both vertical and lateral changes in sedimentary facies, five major sedimentary units are recognized along with two glacial deposits. Radiocarbon datings on shells from the lowest and oldest unit yielded a median probability age of 14.191 cal. ka BP. Unit 2 shows signs of a regressive phase, with sandy, fluvial deposits. Unit 3 suggests climate deterioration and transgression of relative sea level, established with Unit 4, which contains radiocarbon dated shells which yielded median probability age of 13.199 cal. ka BP. Unit 5 consists of cobbles and boulders, deposited in a regressive phase in a littoral, high energy environment when isostatic rebound was occurring due to a glacier retreat. A hiatus divides Ósmelur into two parts, a table-shaped one to the west, and a terrace-shaped one to the east. This study reveals that this hiatus was caused by an erosional event, when a glacial river and a glacier from the Miðdalur valley eroded the upper/younger part of the eastern part in late Allerød or early Younger Dryas, leaving glaciofluvial sediments and a meltout till on top of it. This glacier did not reach the western formation, but a glacier from Hvalfjörður fjord reached its shoulder, leaving evidences such as diamicton and striated clasts. Setlög Ósmels voru rannsökuð til að ákvarða um uppbyggingu þeirra. Alls voru átta snið rannsökuð með klassískri aðferðafræði í feltvinnu, þar sem byggingareinkennum einstakra laga er lýst nákvæmlega. Til hliðsjónar var notast við loftmyndir af svæðinu, ásamt hafsbotnskorti, aldursákvörðuðum skeljum og efnagreindri gjósku sem fannst í tveimur sniðum. Mikill ...
author2 Háskóli Íslands
format Thesis
author Ríkey Júlíusdóttir 1984-
author_facet Ríkey Júlíusdóttir 1984-
author_sort Ríkey Júlíusdóttir 1984-
title Development of the Ósmelur sedimentary sequence in Hvalfjörður, W-Iceland
title_short Development of the Ósmelur sedimentary sequence in Hvalfjörður, W-Iceland
title_full Development of the Ósmelur sedimentary sequence in Hvalfjörður, W-Iceland
title_fullStr Development of the Ósmelur sedimentary sequence in Hvalfjörður, W-Iceland
title_full_unstemmed Development of the Ósmelur sedimentary sequence in Hvalfjörður, W-Iceland
title_sort development of the ósmelur sedimentary sequence in hvalfjörður, w-iceland
publishDate 2019
url http://hdl.handle.net/1946/33556
long_lat ENVELOPE(-21.663,-21.663,64.376,64.376)
ENVELOPE(-21.500,-21.500,64.250,64.250)
ENVELOPE(-21.642,-21.642,64.115,64.115)
geographic Hvalfjörður
Kjósarsýsla
Miðdalur
geographic_facet Hvalfjörður
Kjósarsýsla
Miðdalur
genre glacier
Iceland
Kjósarsýsla
genre_facet glacier
Iceland
Kjósarsýsla
op_relation http://hdl.handle.net/1946/33556
_version_ 1766009724165160960