Iceland Within the Northern Atlantic, Volume 2

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Группа авторов. Iceland Within the Northern Atlantic, Volume 2

Table of Contents

List of Illustrations

List of Tables

Guide

Pages

Iceland Within the Northern Atlantic 2. Interactions between Volcanoes and Glaciers

List of Abbreviations

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

R

S

T

U

W

Preface

Introduction

1. Young Icelandic Volcanism and its Implications

1.1. Introduction

1.2. Icelandic magma series. 1.2.1. Lava types

1.2.2. Geochemical diversity of young Icelandic basalts and their sources

1.2.3. Some geochemical constraints concerning the origin and geodynamic evolution of Iceland

1.3. Central volcanoes and active fissural systems. 1.3.1. Central volcanoes

1.3.2. Fissural volcanism and subaerial lava flows. 1.3.2.1. Modes of emplacement

1.3.2.2. The diversity of subaerial lava flows

1.3.3. Hydromagmatism

1.3.3.1. Submarine or Surtseyan volcanism

1.3.3.2. Sub-lacustrine or sub-glacial hydromagmatism

1.3.3.3. Phreatomagmatism

1.4. Volcanic hazards in Iceland. 1.4.1. Hazards related to lava flows

1.4.2. Hazards related to explosions and gas emissions

1.4.3. Jökulhlaups and associated hazards

1.4.3.1. Morphological and sedimentological impacts

1.4.3.2. Retroaction on volcanism

1.4.3.3. Jökulhlaups and climate

1.4.3.4. Jökulhlaups and humans

1.4.4. Icelandic dust: a consequence of volcanism

1.4.4.1. Tephras

1.4.4.2. Loess

1.4.4.3. Continental dunes

1.5. References

2. Volcanism and Glaciations: Forcings and Chronometers

2.1. Subglacial volcanic landforms

2.1.1. Subglacial isolated volcanoes or tuyas

2.1.2. Hyaloclastite ridges or tindar

2.2. Volcanism, deglaciation and climate. 2.2.1. General features: deglaciation, discharge and partial melting

2.2.1.1. The facts

2.2.1.2. Plausible explanations for variations in partial melting

2.2.2. Deglaciation and climate feedback

2.3. The hypothesis of a link between volcanism and climate and its test by dating

Box 2.1.Carbon-14 or radiocarbon dating

2.3.1. The K-Ar chronometer. 2.3.1.1. Principle

2.3.1.2. Experimental approaches

2.3.1.3. Sample preparation

2.3.1.4. The unspiked K-Ar method

2.3.1.5. The40Ar/39Ar method

2.3.1.6. Step-heating experiments

2.3.1.7. Single grain dating experiments

2.3.2. The combination of K-Ar and40Ar/39Ar methods for dating Icelandic volcanism. 2.3.2.1. Methodological considerations

2.3.2.2. Sample selection

2.3.2.3. Results of K-Ar dating

2.3.3. A link between volcanism and climate according to K-Ar ages?

2.3.4. A rhyolitic volcanism synchronous with deglaciations? 2.3.4.1. Contribution of the dating of rhyolites

2.3.4.2. Geological context of the dated rhyolites. 2.3.4.2.1. The Þórsmörk ignimbrite

2.3.4.2.2. The Torfajökull obsidian

2.3.4.2.3. The Fannborg rhyolite

2.3.4.2.4. The Snæffel (East Iceland)

2.3.4.3. Results of the new40Ar/39Ar datings. 2.3.4.3.1. 40Ar/39Ar age of the Þórsmörk ignimbrite

2.3.4.3.2. 40Ar/39Ar age of the Rauðfossafjöll (Torfajökull volcano)

2.3.4.3.3. 40Ar/39Ar age of the Fannborg (Kerlingarfjöll volcano)

2.3.4.3.4. 40Ar/39Ar age of the Snæffel summit

2.3.4.4. Relationship between rhyolitic volcanism and deglaciation

2.3.4.5. Rhyolitic tephras: temporal markers and interarchive correlation tools

2.4. References

3. Cenozoic Evolution of Iceland and the Cryosphere

3.1. Ice ages and the opening of the Atlantic

3.1.1. The Middle and Final Miocene cooling

3.1.2. The acceleration of the Middle Pliocene. 3.1.2.1. The Middle Pliocene

3.1.2.2. The Pleistocene

3.1.3. The Middle Pleistocene Transition

3.1.4. The initiation of thermohaline circulation

3.2. Iceland’s Quaternary glaciations. 3.2.1. Conditions for the development and functioning of ice caps

3.2.2. Glacio-isostasy. 3.2.2.1. The loading of the earth’s crust

3.2.2.2. Glacio-eustatic implications

3.2.2.3. Sedimentary implications in sequential stratigraphy

3.2.3. Icelandic data. 3.2.3.1. Specifics

3.2.3.2. Volcanic tracers of ice volume

3.2.4. The Icelandic record. 3.2.4.1. The very first glaciations (Mio-Pliocene)

3.2.4.2. The Middle Pleistocene Transition (MPT) from 1 My to 0.53 My

3.2.4.3. Isotopic stage 12, the last very large glaciation (MIS 12) and MIS 10

3.2.4.4. The Saalian II (MIS 8 and 6)

3.2.4.5. The last interglacial (Eemian) and Termination II

3.3. The last glacial episode and its deglaciation. 3.3.1. The Weichselian. 3.3.1.1. The transition with the last glacial episode

3.3.1.2. The beginning of the Weichselian glacial

3.3.1.3. The Middle Pleistocene interstadial

3.3.2. The Last Glacial Maximum. 3.3.2.1. Background

3.3.2.2. Observations

3.3.2.3. Ice streams

3.3.3. Deglaciation and the Holocene. 3.3.3.1. A two-step deglaciation

3.3.3.2. The Holocene evolution of glaciers

3.3.3.3. Neogene and Quaternary erosion

3.4. Iceland today, its climate and vegetation. 3.4.1. The climate

3.4.2. Ocean circulation and climate. 3.4.2.1. Marine currents

3.4.2.2. The sea ice around Iceland and the climate

3.4.3. Soil, people and climate. 3.4.3.1. Humans, fauna, flora and climate in Iceland

3.4.3.2. Icelandic vegetation

3.4.4. Soils and erosion. 3.4.4.1. Permafrost

3.4.4.2. Soils

3.4.4.3. Humans and erosion

3.5. References

Conclusion

C.1. The Icelandic magmas: emplacement and interpretation

C.2. Climatic variations during the Ice Ages: the importance of the North Atlantic and the Icelandic threshold for thermohaline circulation

C.3. The glacial evolution of a volcanic island

References. Key books

Articles, documents and key theses

Websites

List of Authors

Index. A

B

C

D

E

F

G

H

I

J, K, L

M

N

O

P

Q, R

S

T

U, V

Z

Summary of Volume 1

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Отрывок из книги

Geoscience, Field Director – Yves Lagabrielle Lithosphere-Asthenosphere Interactions, Subject Head – René Maury

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This work was then supplemented, from the 2000s, by the geodetic campaigns of the team from the Université de Savoie in Chambéry led by Thierry Villemin in collaboration with Halldór Geirsson and his group. At the beginning of the 1990s, Laurent Geoffroy began (in Paris) work on the Thule basaltic provinces (Scotland, Ireland, Faroe Islands), continued from the 2000s (at the Université du Maine, in Le Mans) on the other side of the Atlantic, in Greenland. The analysis of the morphology of Iceland began in the mid-1990s at the Université de Rennes-I, with Olivier Dauteuil and Brigitte Van Vliet-Lanoë, and then extended to the neighboring ocean in relation to volcanism and the evolution of the North Atlantic. At the same time, the Neogene and Quaternary climatic history of the island, recorded by stratigraphy, was consolidated with dating carried out by Hervé Guillou and his colleagues and by geochemistry carried out at the Université de Bretagne Occidentale, in Brest, in close collaboration with Águst Guðmundsson (Hafnafjördur), Kristjan Sæmundsson and Helgi Björnsson’s team. The last stage of this work is currently being developed in the Géosciences Océan laboratory in Brest, with Laurent Geoffroy and René Maury. It concerns the evolution of the North Atlantic based on Icelandic and Greenlandic data.

The material and logistical support of the Icelandic authorities proved to be very constructive both for field work and for data acquisition and sharing: IMO (Veðurstofa Íslands/Icelandic Meteorological Office); ISOR (Íslenskar orkurannsóknir/Icelandic energy research), formerly Orkustofnun (National Energy Authority); Landsvirkjun (National Power Company) and Vatnajökull National Park. This research would not have been as fruitful without the physical and intellectual help of all our students, at Master’s level and/or with their thesis works: Olivier Bourgeois, Magalie Bellou, Jean-Christophe Embry, Loïc Fourel, Sebastian Garcia, Guillaume Gosselin, Solène Guégan, Romain Plateaux, Lionel Sonnette, Anne Sophie Van Cauwenberge, Ségolène Verrier and Audrey Wayolle.

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