Springer Oceanography Roger Hekinian Sea Floor Exploration Scientific Adventures Diving into the Abyss Sea Floor Exploration Springer Oceanography For further volumes: http://www.springer.com/series/10175 Roger Hekinian Sea Floor Exploration Scientific Adventures Diving into the Abyss 123 Roger Hekinian Saint-Renan France ISBN 978-3-319-03202-3 ISBN 978-3-319-03203-0 (eBook) DOI 10.1007/978-3-319-03203-0 Springer Cham Heidelberg New York Dordrecht London Library of Congress Control Number: 2013955911 Ó Springer International Publishing Switzerland 2014 This work is subject to copyright. 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Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) I dedicate this book to my children Aram, Diran and Anna, and to the future, which will be discovered by my grandchildren Preface I decided to write about my experience at sea on the 8th of October 2002, while sailing on board the German research vessel F.S. SONNE. Looking out at the ocean, I suddenly noticed that time was passing too quickly and I seemed to have more difficulty remembering previous cruises and discoveries. At that time, I thought this would have been my last cruise and I should summarize what I have learned during all these years. Now that I have finished writing this text, I must admit that 2002 was certainly not the year of my last cruise. Indeed, since then I continued to go to sea every year until 2005. The Research Vessel F.S. SONNE is particularly important to me because I have navigated more than 14 months on this ship from 1986 to 2005. That is more time than I’ve spent on any other research vessel. The history of our planet Earth is written in the rocks. The record left on the emerged continents indicates that water has been a major architect shaping our planet. Since the magma ocean forming our early planet more than 4 billion years ago cooled and gave rise to blue seawater and the atmosphere, Earth has become a haven for living organisms. Many species have evolved and disappeared, while other new ones have appeared and flourished ever since the first organisms, in the form of bacteria, were born in the earliest periods of Earth’s existence. As humans, our impact during our short time on Earth is insignificant. Humans cannot alter the course of Earth’s evolution but rather they have to adapt. Our living planet is in constant motion; its outer shell is created through the transfer of molten mantle at spreading ridge axes and will eventually disappear inside the deep Earth to regenerate itself again. This book concludes with my last diving experience looking at an area near the Tonga-Kermadec subduction zone, where old crust is being returned to the mantle to be re-melted once again. While old lithosphere is disappearing, new crust is being created to form a volcanic arc. When looking at a map of the Earth it might appear that the ocean and the continents are immutable, and one might think that they have always been there, that nothing has changed since their creation. This is just an illusion due to the brief time we humans have spent on this planet, as opposed to the Earth’s rocks, which have a geological time scale and are related to the beginning of the Universe, which occurred 15 billion years ago. vii viii Preface I have written this book to give the reader the fruit of my experience and some of the information we have gleaned during my 45 years as a marine geologist and volcanologist. If you close this book a bit wiser about the mysteries of our planet, I will be pleased to think that I have fulfilled my work as an author. Acknowledgments I would like to thank my wife for her help and encouragement in writing this book, and for her patience and encouragement during my years of activity as a scientist. Having lived though so many exciting experiences while learning about our planet, my retirement has been like a prison where I’ve chafed at the confinements of living a ‘‘normal life’’ each day. My wife says I am like a dormant volcano, just waiting for another chance to explode, to explore, and to meet the new challenges that life has to offer. Maybe she is right. This book would not have been possible without the collaboration and help of my colleagues, many of whom were involved in the sea-going expeditions I have participated in over the years. I am particularly indebted to the captains and officers that were responsible for the research vessels and the submersibles. The ships’ crews, and the groups involved in the maintenance and the operational aspect of the submersible dives are also warmly acknowledged. I would also like to thank Prof. Rodey Batiza, Peter Stoffers, and Steven Scott who have taken time to comment parts of this work. ix Contents 1 An Overview of Oceanographic Exploration ................ 1 Introduction. 1 Historical Background . 2 Ocean Explorers and Pioneers in Oceanography . 2 Colleagues and Collaborators . 6 Lamont-Doherty Earth Observatory (LDEO) . 8 Chronic Seasickness . 9 Back to Lamont. 10 Cnexo-Ifremer . 11 Personal Feelings and Experience . 11 Scientific Projects . 13 Preparing an Expedition . 15 Life on Board a Research Vessel . 17 Team Work. 19 Communicating Scientific Results . 19 References . 21 2 Our Haven, Planet Earth .............................. 23 The Birth of Planet Earth . 24 The Solid Earth’s Interior . 26 The Core . 29 The Mantle . 30 The Lithosphere-Crust . 31 Water on Earth . 32 Why Seawater is Salty . 34 How Deep Can Seawater Penetrate into the Earth’s Lithosphere? . 35 Hydrosphere-Atmosphere Interaction . 35 Formation of Continents . 36 Large Igneous Provinces (LIP) as a Nucleus for Continent Accretion . 39 Volcanic Arcs: Possible Sites of Crustal Accretion . 40 Continental Drift . 41 Plate Tectonics . 41 Mantle Convection Currents . 44 xi xii Contents Sea Floor Renewal . 46 Earth’s Magnetism . 48 What is the Source of the Earth’s Magnetic Field? . 49 References . 49 3 Diving into the Abysses................................ 53 Why Do We Explore the Sea Floor? . 53 Bathymetric Mapping and Sea Floor Imagery . 54 Navigation Systems and Other Vital Equipment . 57 Early Underwater Exploration . 57 Bathyscaphes. 59 Archimède . 59 Manned and Unmanned Submersibles . 61 Alvin . 61 Cyana. 63 Nautile . 63 Pisces . 64 Unmanned Submersibles and Robots . 65 Diving in a Manned Submersible. 69 A Normal Diving Day . 69 References . 74 4 Sea Floor Rocks ..................................... 75 Rocks: A Combination of Several Basic Minerals . 76 Basaltic Rocks. 78 Mid-Ocean Ridge Basalt (MORB) . 79 Alkali Basalts/Intraplate Oceanic Basalts (IOBs) . 80 Model for Explaining Small-Scale Magma Heterogeneities in Sea Floor Basalt. 81 Silica-Rich Lava and Obsidian . 82 Composition of Silica-Enriched Rocks . 84 Origin of Silica-Rich Lavas. 85 Gabbroic Rocks . 87 Peridotites . 90 Emplacement and Distribution of Peridotite . 92 Melt Impregnation of Peridotites . 98 Section of the Oceanic Lithosphere . 99 Sea Floor Exposed Through Time . 99 Present Day Exposed Sea Floor . 100 Stratigraphic Columns . 100 The Brittle and Ductile Transition Zone . 102 References . 104 Contents xiii 5 Earth’s Mantle Melting and Volcanism .................... 109 Magma Reservoirs Underneath Spreading Ridges . 109 Volcanic Landscape . 112 Lava Morphology . 113 Pillow Lava and Sheet Flows . 115 Lava Pond. ..