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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Eurasian Arctic ice sheets in transitions:consequences for climate, environment and ocean circulation

Kaparulina, E. (Ekaterina) 16 January 2018 (has links)
Abstract In this Ph.D. thesis sediment cores from the central Arctic Ocean, southwestern Barents Sea and sediment exposures from the Kola Peninsula were investigated in order to reveal interactions between the late middle Pleistocene and late Pleistocene Arctic ice sheets, between Marine Isotope Stages 6 and 1 (MIS 6 and MIS 1). One of the main objectives of this work is to establish provenance areas for the sediments studied in the central Arctic, the southwestern (SW) Barents Sea and the Kola Peninsula, their transport mechanisms and through that their relationship to glaciations in the Arctic and to development in the Kola Peninsula during the late middle and late Pleistocene. Mineralogical and geochemical data from the core 96/12-1pc on the Lomonosov Ridge, central Arctic Ocean was studied to evaluate ice transport from circum-Arctic ice sheets and variability in sediment drainage systems associated with their decay. SW Barents Sea sediments contain important information on Late Glacial and Holocene sediment provenance characteristics in relation to ice flow patterns and ice rafting from different regional sectors. The studied SW Barents Sea sediment cores show that sediments were most likely derived from a combination of far-field Fennoscandian sources, local subcropping Mesozoic strata below the seafloor and sea ice transport. The investigation carried out on the Kola Peninsula indicates that the Eemian (MIS 5e) marine environment in the White Sea Basin and onshore coastal areas gradually changed into a glaciolacustrine environment during MIS 5d to MIS 5a. Subsequently, the Scandinavian Ice Sheet (SIS) covered the Kola Peninsula, most probably during MIS 4. The final deglaciation of the SIS on the Kola Peninsula took place, however, during the late Weichselian (MIS 2) between 16–12 ka. / Tiivistelmä Tässä väitöstutkimuksessa tutkittiin sedimenttikairanäytteitä keskeiseltä Jäämereltä ja Lounais-Barentsinmereltä sekä tarkasteltiin sedimenttiseurantoja Kuolan niemimaalla tarkoituksena selvittää myöhäisen keskipleistoseeni- ja myöhäispleistoseeniajan Arktisten jääkenttien keskinäiset vuorovaikutukset erityisesti merellisten isotooppivaiheiden 6 ja 1 (MIS 6 ja MIS 1) välillä. Tämän työn yhtenä päätavoitteena on määritellä sedimenttien lähdealueet keskeisellä Arktiksella, lounaisella Barentsinmerellä ja Kuolan niemimaalla, sedimenttien kuljetusmekanismit ja näiden perusteella riippuvuudet Arktisiin jäätiköihin ja Kuolan niemimaalla tapahtuneeseen myöhäiskeski- ja myöhäispleistoseenin kehitykseen. Mineraloginen ja geokemiallinen tieto Lomonosovin harjanteen kairauksesta 96/12-1pc, keskeisellä Jäämerellä on perusta arvioitaessa jääkuljetusmekanismeja ympäröiviltä sirkum-Arktisilta jäätiköiltä ja arvioitaessa valuma-alueiden osuutta suhteessa näiden jäätiköiden häviämiseen. Lounaisen Barentsinmeren sedimentit sisältävät tärkeätä tietoja viimeisen jäätiköitymisen loppuvaiheen ja holoseeni-ajan sedimenttien lähdealueista ja suhteista jäävirtauksiin ja jääkuljetukseen eri aluesektoreilta. Tutkitut Lounais-Barentsinmeren sedimentit osoittavat, että sedimentit olivat todennäköisimmin peräisin suhteellisen kaukaisilta Fennoscandian lähdealueilta, paikallisista mesotsoosista merenpohjan kerrostumista ja merijään kuljettamasta materiaalista. Kuolan niemimaalla tehty tutkimus osoittaa, että Eem-kauden (MIS 5e) meriympäristö Vienanmeren altaassa ja rannikkoalueilla vähitellen muuttui glaciolakustriseksi ympäristöksi MIS 5d:n ja MIS 5a:n välisenä aikana. Sen jälkeen Skandinavian jääkenttä (SIS) peitti Kuolan niemimaan, todennäköisimmin koko MIS:n 4 ajanjakson. SIS:n lopullinen deglasiaatio alkoi Kuolan niemimaalla kuitenkin myöhäisen Veiksel-jääkauden (MIS 2) aikana noin 16–12 ka sitten.
2

Grain size analysis of a short sediment core from the Lomonosov Ridge, central Arctic Ocean

Fuentes Guerrero, César January 2015 (has links)
Trigger core 07, is a 53 cm long sediment core that was collected during the Danish-Swedish expedition “Lomonosov Ridge off Greenland 2012” on the slope of the Lomonosov Ridge in the Arctic Ocean at a depth of 2522 m. This part of the world has experienced critical environmental changes during the Quaternary. Ice-sheets have advanced and retreated, and deposited sediments through all the Arctic Ocean. Glacial sediments contain coarser material and are gray, whereas interglacial sediments are brown, because of high amounts of manganese, and consist of fine-grained material.  The aim of this project is to make grain size analysis on TC 07 with the purpose to make an interpretation of the grain size data in relation to glaciation history and paleo-oceanography. For that, a correlation with piston core 07 has been made, and also a correlation between piston core 07 and the Arctic Coring Expedition, ACEX. The results showed that fine-grained material is more abundant in the top brown unit down to 32 cm, suggesting an interglacial period. This is followed by a gray-beige unit that goes down to 49 cm, and consist of coarser material, indicating glacial deposits. This unit can be linked to the Marine Isotope Stage 2, MIS 2, which began approximately 29000 years ago and ended about 14000 years ago / ”Trigger core 07” är en 53 cm lång sedimentkärna som togs upp på ett djup av 2522 m från Lomonosovryggen i Arktisk under en dansk-svensk expedition kallad ”Lomonosov Ridge off Greenland 2012”. Den här delen av världen har genomgått kraftiga klimatförändringar under kvartär. Istäcken har vuxit fram och dragit sig tillbaka och avsatt sediment över hela Arktis. Sediment avsatta under istider, kännetecknas av att vara gråa med mycket grovt material, medan sediment avsatta under mellanistider är bruna, vilket är på grund av de höga halterna av mangan och består av finkornigt material. Målet med denna uppsats är att göra en kornstorleksanalys på sedimentkärnan, med syfte i åtanke på att göra en tolkning av informationen i förhållande till istidshistorik och paleo-oceanografi. För att kunna gå tillväga med det, har en korrelation gjorts mellan kärnan och ”piston core 07”, samt en korrelation mellan ”piston core 07” och ”Arctic Coring Expedition, ACEX”. Resultaten visar en brun enhet rik på finkornigt material ned till 32 cm, vilket är typiskt för mellanistider. Den följs av en grå-beige enhet som sträcker sig ned till 49 cm och består av grovkornigt material vilket tyder på istid. Den här enheten kan kopplas till ”Marine Isotope Stage 2, MIS ”, som varade mellan 14000 och 29000 år sedan.
3

The impacts of climate change on environmental geopolitics of the Arctic

Pelletier, Mireille January 2013 (has links)
The new fact that the environment is becoming the main factor of geopolitical transformations in the Arctic region has been triggered mainly by climate change. In the North, this recent aspect of geopolitics, in correlation with the environment, leads sometimes to tensions between countries, but also to a need for cooperation. The question brought by such conditions is, to which extent will this climate change provoke cooperation or conflicts between the Arctic states. The purpose of addressing the problem is to understand what kind of challenges would be facing the international relations between circumpolar countries and how the environment is playing a geopolitical role in them. The objective of the main research question is to assess the importance of climate change over the geopolitics of the Arctic through several spheres of geopolitics: environment and bio-diversity, economic activity of the region, sovereignty and territoriality, security of the circumpolar states, and international and diplomatic relations. The trans-border and transnational nature of environmental issues is another important factor, since nature does not respect human-made boundaries and an environmental concern, such as climate change and its aftermaths, cannot be exclusive to a state along the lines of its borders.

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