Iceland Within the Northern Atlantic, Volume 2: Interactions between Volcanoes and Glaciers

The volcanic island of Iceland is a unique geological place due both to its position in the middle of the Atlantic Ocean and its repeated glaciations. It has been an accurate recorder of geodynamic and regional climatic evolutions for at least the last 15 million years. This book studies the Quaternary magmatism associated with the deep Iceland hotspot and, in particular, its distinctive geochemical and volcanological characteristics. It also analyzes that Arctic glacierization as it relates to the opening of the North Atlantic and the appearance of today’s ocean currents. We will also investigate the Quaternary glaciation as it affected Iceland in its oceanic context, particularly on the basis of radiometric dating, looking at the formation of the Greenland and Scandinavian ice sheets and data from marine sediment. Finally, it explores the specific environmental features of the island, from the end of the last ice age to global warming today. This book brings together the internal and external geodynamics of our planet to understand how Iceland functions and its role as a recorder of the paleoclimatic evolution of the Northern Hemisphere.

Table of Contents:
List of Abbreviations ix Preface xv Brigitte VAN VLIET-LANOË and Françoise BERGERAT Introduction xix Brigitte VAN VLIET-LANOË and René MAURY Chapter 1. Young Icelandic Volcanism and its Implications 1 René MAURY and Brigitte VAN VLIET-LANOË 1.1. Introduction 1 1.2. Icelandic magma series 3 1.2.1. Lava types 3 1.2.2. Geochemical diversity of young Icelandic basalts and their sources 8 1.2.3. Some geochemical constraints concerning the origin and geodynamic evolution of Iceland 13 1.3. Central volcanoes and active fissural systems 14 1.3.1. Central volcanoes 14 1.3.2. Fissural volcanism and subaerial lava flows 17 1.3.3. Hydromagmatism 26 1.4. Volcanic hazards in Iceland 31 1.4.1. Hazards related to lava flows 31 1.4.2. Hazards related to explosions and gas emissions 32 1.4.3. Jökulhlaups and associated hazards 37 1.4.4. Icelandic dust: a consequence of volcanism 44 1.5. References 51 Chapter 2. Volcanism and Glaciations: Forcings and Chronometers 57 Hervé GUILLOU, René MAURY and Brigitte VAN VLIET-LANOË 2.1. Subglacial volcanic landforms 57 2.1.1. Subglacial isolated volcanoes or tuyas 58 2.1.2. Hyaloclastite ridges or tindar 61 2.2. Volcanism, deglaciation and climate 65 2.2.1. General features: deglaciation, discharge and partial melting 65 2.2.2. Deglaciation and climate feedback 69 2.3. The hypothesis of a link between volcanism and climate and its test by dating 70 2.3.1. The K-Ar chronometer 71 2.3.2. The combination of K-Ar and 40Ar/39Ar methods for dating Icelandic volcanism 80 2.3.3. A link between volcanism and climate according to K-Ar ages? 86 2.3.4. A rhyolitic volcanism synchronous with deglaciations? 88 2.4. References 95 Chapter 3. Cenozoic Evolution of Iceland and the Cryosphere 103 Brigitte VAN VLIET-LANOË and Hervé GUILLOU 3.1. Ice ages and the opening of the Atlantic 103 3.1.1. The Middle and Final Miocene cooling 108 3.1.2. The acceleration of the Middle Pliocene 109 3.1.3. The Middle Pleistocene Transition 112 3.1.4. The initiation of thermohaline circulation 114 3.2. Iceland’s Quaternary glaciations 116 3.2.1. Conditions for the development and functioning of ice caps 116 3.2.2. Glacio-isostasy 119 3.2.3. Icelandic data 123 3.2.4. The Icelandic record 126 3.3. The last glacial episode and its deglaciation 142 3.3.1. The Weichselian 142 3.3.2. The Last Glacial Maximum 144 3.3.3. Deglaciation and the Holocene 150 3.4. Iceland today, its climate and vegetation 161 3.4.1. The climate 161 3.4.2. Ocean circulation and climate 162 3.4.3. Soil, people and climate 167 3.4.4. Soils and erosion 173 3.5. References 179 Conclusion 193 Brigitte VAN VLIET-LANOË, René MAURY and Hervé GUILLOU References 199 List of Authors 213 Index 215 Summary of Volume 1 221

About the Author :
Brigitte Van Vliet-Lanoë is Emeritus Research Director at CNRS and is part of the Ocean Geosciences Laboratory at the University of Western Brittany, France. A surface geologist, she is a specialist in stratigraphy and the sedimentary formations of cold continental environments and their deformation by paleoseismicity.