Hydrothermal Processes at Seafloor Spreading Centers PDF
Preview Hydrothermal Processes at Seafloor Spreading Centers
HYDROTHERMAL PROCESSES AT SEAFLOOR SPREADING CENTERS NATO CONFERENCE SERIES Ecology II Systems Science III Human Factors IV Marine Sciences V Air-Sea Interactions VI Materials Science IV MARINE SCIENCES Volume I Marine Natural Products Chemistry edited by D. J. Faulkner and W. H. Fenical Volume 2 Marine Organisms: Genetics, Ecology, and Evolution edited by Bruno Battaglia and John A. Beardmore Volume 3 Spatial Pattern in Plankton Communities edited by John H. Steele Volume 4 Fiord Oceanography edited by Howard J. Freeland, David M. Farmer, and Colin D. Levings Volume 5 Bottom-interacting Ocean Acoustics edited by William A. Kuperman and Finn B. Jensen Volume 6 Marine Slides and Other Mass Movements edited by Svend Saxov and J. K. Nieuwenhuis Volume 7 The Role of Solar Ultraviolet Radiation in Marine Ecosystems edited by John Calkins Volume 8 Structure and Development of the Greenland-Scotland Ridge edited by Martin H. P. Bott, Svend Saxov, Manik Talwani, and Jarn Thiede Volume 9 Trace Metals in Sea Water edited by C. S. Wong, Edward Boyle, Kenneth W. Bruland, J. D. Burton, and Edward D. Goldberg Volume IDA Coastal Upwelling: Its Sediment Record Responses of the Sedimentary Regime to Present Coastal Upwelling edited by Erwin Suess and Jarn Thiede Volume I DB Coastal Upwelling: Its Sediment Record Sedimentary Records of Ancient Coastal Upwelling edited by Jarn Thiede and Erwin Suess Volume 11 Coastal Oceanography edited by Herman G. Gade, Anton Edwards, and Harald Svendsen Volume 12 Hydrothermal Processes at Seafloor Spreading Centers edited by Peter A. Rona, Kurt Bostrom, Lucien Laubier, and Kenneth L. Smith, Jr. Photograph of mounds surmounted by elongate chimneys several meters high com pos(!d primarily of polymetallic sulfide minerals discharging high-temperature pure hydrothermal solutions as "black smokers." A white crab is present near the center of the photograph on one of the chimneys. The objects in the foreground are water sampling bottles. The photograph was taken from the Deep Submergence Research Vehicle Alvin at a water depth of about 2000 meters at the "Hanging Gardens" hydrothermal site near the axis of the East Pacific Rise at latitude 210 North (K. Kim, Isotope Laboratory, Scripps Institution of Oceanography). A thicket of the vestimentiferan worm Riftia consisting of tubes about one meter in length with a red absorptive organ protruding into a mixture of ambient seawater that supplies oxygen, and hydrothermal effluent that supplies hydrogen sulfide visi ble as a milky haze in the water column; carbon dioxide is supplied by both sources. The objects in the foreground are the tops of water sampling bottles. The photograph was taken from the Deep Submergence Research Vehicle Alvin at a water depth of about 2000 meters at the "Hanging Gardens" hydrothermal site near the axis of the East Pacific Rise at latitude 210 North (K. Kim, Isotope Laboratory, Scripps Institution of Oceanography). HYDROTHERMAL PROCESSES AT SEAFLOOR SPREADING CENTERS Edited by Peter A. Rona National Oceanic and Atmospheric Administration Atlantic Oceanographic and Meteorological Laboratories Miami, Florida Kurt Bostrom University of Stockholm Stockholm, Sweden Lucien Laubier National Center for Ocean Exploitation Paris, France and Kenneth L. Smith, Jr. Scripps Institution of Oceanography University of California La Jolla, California SPRINGER SCIENCE+BUSINESS MEDIA, LLC Library of Congress Cataloging in Publication Data Main entry under title: Hydrothermal processes at seafloor spreading centers. (NATO conference series. IV, Marine sciences; v. 12) "Proceedings of a NATO Advanced Research Institute, held April 5-8, 1982, at the Department of Earth Sciences of Cambridge University, England"-T.p verso. Includes bibliographical references and index. 1. Sea-floor spreading-Congresses 2. Hydrothermal deposits-Congresses. 3. Heat budget (Geophysics)-Congresses. 4. Chemical oceanography-Congresses. 5. Hydrothermal vent ecology-Congresses. I. Rona, Peter A. II. Series. QE511.7.H93 1983 551.46'08 83-17747 ISBN 978-1-4899-0404-1 ISBN 978-1-4899-0402-7 (eBook) DOI 10.1007/978-1-4899-0402-7 Proceedings of a NATO Advanced Research Institute, held April 5-8, 1982, at the Department of Earth Sciences of Cambridge University, England © 1983 Spnnger SClence+Buslness Media New York Onglnally published by Plenum Press. New York In 1983 Softcover repnnt of the hardcover 1st edition 1983 All rights reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher PREFACE During the past ten years, evidence has developed to indicate that seawater convects through oceanic crust driven by heat derived from creation of lithosphere at the Earth-encircling oceanic ridge-rift system of seafloor spreading centers. This has stimulated multiple lines of research with profound implications for the earth and life sciences. The lines of research comprise the role of hydrothermal convection at seafloor spreading centers in the Earth's thermal regime by cooling of newly formed litho sphere (oceanic crust and upper mantle); in global geochemical cycles and mass balances of certain elements by chemical exchange between circulating seawater and basaltic rocks of oceanic crust; in the concentration of metallic mineral deposits by ore-forming processes; and in adaptation of biological communities based on a previously unrecognized form of chemosynthesis. The first work shop devoted to interdisciplinary consideration of this field was organized by a committee consisting of the co-editors of this volume under the auspices of a NATO Advanced Research Institute (ARI) held 5-8 April 1982 at the Department of Earth Sciences of Cambridge University in England. This volume is a product of that workshop. The papers were written by members of a pioneering research community of marine geologists, geophysicists, geochemists and biologists whose work is at the stage of initial description and interpretation of hydrothermal and associated phenomena at seafloor spreading centers. The papers are grouped by subject into eight sections each with an introductory paper that places the papers in that section in context of the subject as a whole. The subjects treated comprise geologic settings of hydrothermal activity at slow-, intermediate-, and fast-spreading oceanic ridges (section 1); the nature of hydrothermal circulation inferred from crustal sections exposed on land and modeled at seafloor spreading centers (section 2); the exchange of elements between basalt and seawater at elevated temperatures and pressures determined experimentally in the laboratory and the application of these findings to interpretation of natural hydrothermal systems and basalt alteration at oceanic ridges (section 3); comparison of chemical and physical processes at submarine oceanic ridges with those on Iceland, a subaerial portion of an oceanic ridge (section vii viii PREFACE 4); the chemistry of submarine hot springs determined where primary hydrothermal solutions were first sampled at an oceanic ridge, and the role of such solutions in geochemical mass balances and budgets, as well as in the maturation of hydrocarbons (section 5); a reconsideration of ferromanganese deposits including manga nese nodules in light of the new knowledge of seafloor hydrother mal processes (section 6); hydrothermal ore-forming processes directly observed at an oceanic ridge and inferred from mineral deposits in certain slices of oceanic crust exposed on land (section 7); the adaptation of biologic communities to the envi ronment of active hydrothermal vents at oceanic ridges (section 8). A chronological list of landmarks in studies of hydrothermal processes at seafloor spreading centers presented in the Appendix helps to place the papers in perspective of the development of the entire field. The papers consolidate previous work and delineate a research frontier that is advancing rapidly. The interdisciplinary overview reveals the immense potential of the study of hydrothermal processes at seafloor spreading centers for continued progress on both basic and applied levels. On a basic level the field is at an early stage in developing understanding of permeability and magmatic heat sources as controls of hydrothermal convection in oceanic crust; mass and heat transfer by high-temperature hydrothermal convection, low temperature hydrothermal convection, and other submarine pro cesses; the contribution of each of these processes to local and global geochemical mass balances and budgets and their roles in geochemical cycles; and the dynamics of biologic adaptation at active submarine hydrothermal vents. The development of under standing of hydrothermal processes at seafloor spreading centers has brought the field to the threshold of deciphering the role these processes in the evolution of the hydrosphere, lithosphere and biosphere. On an applied level, basalt-seawater exchange in hydrothermal systems is a component to be considered in evaluation of the capa city of the oceans to assimilate toxic substances. The concentra tion of polymetallic mineral deposits by hydrothermal processes at seafloor spreading centers constitutes a resource for the future, and provides an analog to model ore-forming processes that apply to the understanding of and exploration for economic hydrothermal mineral deposits on land. The study of bacterial chemosynthesis at hydrothermal vents may lead to developments in mariculture, metal fixation, and medicine. It is a pleasure to acknowledge those who made the NATO ARI and this volume possible. The NATO Special Program Panel on Marine Sciences under the chairmanship of J. D. Burton of Southampton University offered the opportunity to organize the ARI. The NATO Scientific Affairs Division provided funding with PREFACE ix supplemental support donated by the Centre National Pour l'Exploitation des Oceans (CNEXO) of France, and the National Oceanic and Atmospheric Administration (NOAA) of the United States. F. Webster gave guidance and support in his dual capa cities as member of the NATO Panel and as Assistant Administrator for NOAA Research and Development. N. A. Ostenso provided encouragement as Deputy Assistant Administrator for NOAA Research and Development. E. R. Oxburgh and M. I. Johnston, in their respective positions as Chairman and Administrator of the Depart ment of Earth Sciences at Cambridge University, made available an ideal place to convene the ARI and facilitated local arrangements. P. M. Vann and L. Schmidt in their respective positions as Asso ciate Editor and Assistant to the Managing Editor of the Plenum Publishing Corporation ably handled the production of this volume. Finally, acknowledgment is extended to the authors who presented the latest results of their investigations at the ARI, to other participants whose discussion contributed to vigorous interaction at the sessions, and to reviewers whose critical comments have benefited the papers in this volume. Peter A. Rona Kurt Bostrom Lucien Laubier Kenneth L. Smith, Jr.
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