Magmatism in the Ocean Basins Geological Society Special Publications Series Editor K. COE GEOLOGICAL SOCIETY SPECIAL PUBLICATION NO 42
Magmatism in the Ocean Basins
EDITED BY A. D. SAUNDERS & M. J. NORRY Department of Geology The University Leicester LEI 7RH
1989
Published for The Geological Society by Blackwell Scientific Publications
OXFORD LONDON EDINBURGH
BOSTON MELBOURNE Published for DISTRIBUTORS The Geological Society by USA and Canada Blackwell Scientific Publications Publishers' Business Services Osney Mead, Oxford OX2 0EL PO Box 447 Tel. 0865-240201) (Orders: Brookline Village 8 John Street, London WC1N 2ES Massachusetts 02147 23 Ainslie Place, Edinburgh EH3 6AJ (Orders: Tel. (617) 524-7678) 3 Cambridge Center, Suite 208 Cambridge, Massachusetts 02142, USA Canada 107 Barry Street, Carlton, Victoria 3053 Oxford University Press Australia 70 Wynford Drive Don Mills First published 1989 Ontario M3C 1J9 (Orders: Tel. (416) 441-2941) 1989 The Geological Society. Authorization to Australia photocopy items for internal or personal use, or the Blackwell Scientific Publications internal or personal use of specific clients, is granted (Australia) Pty Ltd by The Geological Society for libraries and other 107 Barry Street, Carlton users registered with the Copyright Clearance Center Victoria 3053 (CCC) Transactional Reporting Service, providing (Orders: Tel. (03) 347-0300) that a base fee of $03.00 per copy is paid directly to CCC, 27 Congress Street, Salem, MA 01970, USA. British Library Cataloguing in Publication Data 0305-8719/89 $03.00 Magmatism in the ocean basins. Typeset by Setrite Ltd, Hong Kong 1. Oceans. Beds. Magmatism. Printed and bound at I. Saunders, A.D. II. Norry, M.J. Cambridge University Press III. Geological Society of London IV. Series 551.46'08 ISBN 0-632-02384-8
Library of Congress Cataloging-in-Publication Data Magmatism in the ocean basins. (Geological Society special publication; no. 42) Bibliography: p. Includes index. 1. Magmatism. 2. Ocean bottom. I. Saunders, A. D. II. Norry, M.J. III. Series. QE461.M23784 1989 551.46'08 88-16828 ISBN 0-632-02384-8 Contents
SAUNDERS, A. D. & NORRY, M. J. Introduction vii
GASS, I. G. Magmatic processes at and near constructive plate margins as deduced from the Troodos (Cyprus) and Semail Nappe (N Oman) ophiolites 1
WHITE, R. S. Asthenospheric control on magmatism in the ocean basins 17
SPRAY, J. G. Upper mantle segregation processes: evidence from alpine-type peridotites 29
NATLAND, J. H. Partial melting of a lithologically heterogeneous mantle: inferences from crystallization histories of magnesian abyssal tholeiites from the Siqueiros Fracture Zone 41
DICK, H. J. B. Abyssal peridotites, very slow spreading ridges and ocean ridge magmatism 71
BLOOMER, S. H., NATLAND, J. H. & FISHER, R. L. Mineral relationships in gabbroic rocks from fracture zones of Indian Ocean ridges: evidence for extensive fractionation, parental diversity, and boundary-layer recrystallization 107
ELTHON, D. Pressure of origin of primary mid-ocean ridge basalts 125
FuJn, T. Genesis of mid-ocean ridge basalts 137
PALACZ, Z. A. • WOLFF, J. A. Strontium, neodymium and lead isotope characteristics of the Granadilla Pumice, Tenerife: a study of the causes of strontium isotope disequilibrium in felsic pyroclastic deposits 147
STOREY, M., WOLFF, J. A., NORRY, M. J. & MARRINER, G. F. Origin of hybrid lavas from Agua de Pau volcano, Sao Miguel, Azores 161
THOMPSON, G., BRYAN, W. B. & HUMPHRIS, S. E. Axial volcanism on the East Pacific Rise, 10-12 ~ N 181
HELGASON, J. The Fjallgardar volcanic ridge in NE Iceland: an aborted early stage plate boundary or a volcanically dormant zone? 201
FLOYD, P. A. Geochemical features of intraplate oceanic plateau basalts 215
DAVIES, G. R., NORRY, M. J., GERLACH, D. C. & CLIFF, R. A. A combined chemical and Pb-Sr-Nd isotope study of the Azores and Cape Verde hotspots: the geodynamic implications 231
CHAFFEY, D. J., CLIFF, R. A. & WILSON, B. M. Characterization of the St Helena magma source 257
JORON, J.-L. & TREUIL, M. Hygromagmaphile element distributions in oceanic basalts as fingerprints of partial melting and mantle heterogeneities: a specific approach and proposal of an identification and modelling method 277
FISHER, D. E. Evaluation of rare gas data in relation to oceanic magmas 301
SON, S.-s. & MCDONOUGH, W. F. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes 313
MURTON, B. J. Tectonic controls on boninite genesis 347
Index 379