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Magmatic processes and plate tectonics
294
Book rec~ws
to tectonic reconstructions. Do the faults described in the text form one contiguous zone activated by the same tectonic processes, or were there a number of tectonic events acting simultaneously with similar manifestations of deformation? In either case, the contents in the book
significantly contribute to our understanding of the tectonic framework and evolution of a large region of the globe and provide a strong basis for continued research in the area. STUART GILDER (Santa Cruz, CA)
Magmatic Processes and Plate Tectonics, edited by H.M. Prichard, T. Alabaster, N.B.W. Harris and C.R. Neary. Geological Society of London, Special Publication No 78, 526 pp., 1993. Price £65.00 (ISBN 0-903317-94-X) This volume was designed to celebrate the retirement of Professor Ian Gass of the Open University, UK, but sadly by the time it reached publication it became a tribute to his memory. Unlike most of the volumes in this series of Special Publications, which normally focus on a particular theme, the 'theme' of this one simply ranges over the research interests of Ian Gass. Although these interests were established early in his career as a survey geologist in Sudan and Cyprus, they fortunately cover the basic features of the Wilson Cycle of Plate Tectonics - mantle-derived magmas, rifting, ocean crust and ophiolites, subduction and orogeny - - so, amongst the 26 contributions, there is something here for almost everybody. Whilst readers might find the odd article difficult to digest, or find that some papers contain new results that could have been published elsewhere, most come over as very useful 'state of the art' summaries of issues that were the prime concern of I.G. Gass. The reference lists attached to individual articles accordingly range from a single column to seven pages. A particularly interesting and valuable feature is that there are some synthesis articles here that would not otherwise have been written for a regular journal or book. The first section concerns mantle and magmatic processes. It includes a comprehensive review of almost all possible features of basaltic volcanoes (Walker), a 3D update of O'Hara's views of trace-element behaviour during melting and in magma chambers, a synthesis of possible petrogenetic models to explain the wide variety of
lavas erupted at the Galapagos hotspot (McBirney), and some penetrating comments on the nature of the lithosphere beneath China (Menzies et al.). There are few petrologists who wouldn't find something useful here. The second section (11 papers) deals with ophiolites and oceanic crust, with particular useful summaries of relationships in the Troodos Complex and other Tethyan ophiolites. As there are well over 100 publications on Troodos, and more on other Tethyan complexes, readers might find these syntheses a valuable source of lecture material. Of course, if Troodos actually represents the accreted forearc of a primitive Tethyan island-arc system (like forearc spreading in primitive West Pacific arcs: see Stern & Bloomer, 1992, BGSA 104: 1621-1636) then using Troodos as a classic model for ocean crust accretion may need to be revised. Robertson & Xenophontos fully discuss development of concepts concerning Troodos, Dietrich & Spencer the extension-related faulting, MacLeod & Murton focus on the Arakapas fossil transform zone, Malpas et al. evaluate the associated Mamonia Complex rocks in relation to Troodos, and Shelton re-evaluates gravity evidence for the structure of Troodos. In the wider field, Smith provides a very useful synthesis of all the Hellenic-Dinaric ophiolites, Bartholomew discusses the significance of mantle fabrics, and there interesting contributions by Roberts & Neary and by Prichard & Lord on Cr and P G E mineralisation, respectively, in ophiolites. Finally, Elderfield et al. assess the global significance of mid-ocean ridge hydrothermal ac-
295
B o o k ret, iews
tivity in the light of recent results on the TAG hydrothermal field; Menzies et al. follow this with experimental studies of the effect of basaltseawater interaction on trace elements and isotope ratios. The fourth section, dealing with convergent plate margins, is more varied. Dewey et al. further develop concepts of orogenic collapse and argue that coesite-bearing eclogites indicate precollapse crustal thicknesses of 120 km. Shackleton provides an improved tectonic interpretation of the late Proterozoic Mozambique Belt in East Africa, while Harris et al. discuss the geochemistry of crustal growth processes in the late Proterozoic of the Arabian Shield. A different approach is provided by Pearce and Parkinson who use trace element models to clarify the magma generating processes in modern island arcs, in particular trying to clarify the contributions from the slab and from the mantle wedge. Many will welcome the review by Wyllie & Wolf in appraising all the experimental work related to the melting of amphibolite, pertinent to subduction zones. A final paper by Vita-Finzi considers Recent uplift in the Eastern Mediterranean. The final section contains papers on rifting and the start of the Wilson Cycle. MacDonald & Upton compare and contrast magmatism in the Proterozoic Gardar zone with that in the East African Rift system; models for both require un-
derplating and lithospheric thinning, but it is not easy to account for the differences. Cox et al. then provide an update of the petrogenesis of the alkali basalts of Yemen, a study began almost 30 yrs ago with Ian Gass; Rogers compares the geochemistry of basalts from the volcanic islands of the southern Red Sea with those from the adjacent Rift systems and tries to account for differences in terms of plume activity and the degree of extension. Davis et al. interpret the compositions of Tertiary basalts from New Mexico in terms of variable asthenosphere-lithosphere interaction. The last word comes from Walker who discusses the mechanics of dyke intrusion on Skye. Almost as an Appendix, there is a paper by Potts et al. reviewing historically advances in analytical geochemistry. This reflects well the importance that Ian Gass attached to progressively developing (from nothing) advanced geochemical instrumentation in order to support a viable Petrological Research Group. In summary, the volume contains quite a number of excellent review or synthesis papers that many geoscientists will find valuable aids to teaching or research. The Editors have done a good job. There are few errors, and there is a useful index. JOHN TARNEY (Leicester, UK) SSDI
0040-1951(94)00097-S
Introduction to Elastic Wave Propagation, by A. Bedford and D.S. Drumheller, John Wiley & Sons, Chichester, U.K., 1994, Hardcover, XIII + 297 pp. Price £39.95 (ISBN 0-471-93884-X) This volume is the latest entry into the already well-populated field of elastic wave propagation pedagogy. The competition is stiff. There are numerous books on the subject, including those by Achenbach, Aki and Richards, Ben Menahem and Singh, Hudson, Kennett, Miklowitz, Pilant, Teisseyre. My apologies go to authors whose books are not listed here. To enter into this competition requires an act of courage; one must acknowledge the valor of the authors. The cover to the book tells us that the audience is the engineering community, but with an
acknowledgment to the earthquake, exploration, deeper earth structure, nondestructive testing and medical communities. Tantalized by an agenda that would cater to such a broad audience, I opened this book eagerly to explore how it might be used in my own course in elastic waves, which is also directed toward geophysicists and engineers. What I found was a book that put forth the fundamentals of elastic wave propagation, but did not get into the applications. For the geophysicist, there is no treatment of wave propagation in multilayered media, free oscillations, attenuation,
Book rec~ws
to tectonic reconstructions. Do the faults described in the text form one contiguous zone activated by the same tectonic processes, or were there a number of tectonic events acting simultaneously with similar manifestations of deformation? In either case, the contents in the book
significantly contribute to our understanding of the tectonic framework and evolution of a large region of the globe and provide a strong basis for continued research in the area. STUART GILDER (Santa Cruz, CA)
Magmatic Processes and Plate Tectonics, edited by H.M. Prichard, T. Alabaster, N.B.W. Harris and C.R. Neary. Geological Society of London, Special Publication No 78, 526 pp., 1993. Price £65.00 (ISBN 0-903317-94-X) This volume was designed to celebrate the retirement of Professor Ian Gass of the Open University, UK, but sadly by the time it reached publication it became a tribute to his memory. Unlike most of the volumes in this series of Special Publications, which normally focus on a particular theme, the 'theme' of this one simply ranges over the research interests of Ian Gass. Although these interests were established early in his career as a survey geologist in Sudan and Cyprus, they fortunately cover the basic features of the Wilson Cycle of Plate Tectonics - mantle-derived magmas, rifting, ocean crust and ophiolites, subduction and orogeny - - so, amongst the 26 contributions, there is something here for almost everybody. Whilst readers might find the odd article difficult to digest, or find that some papers contain new results that could have been published elsewhere, most come over as very useful 'state of the art' summaries of issues that were the prime concern of I.G. Gass. The reference lists attached to individual articles accordingly range from a single column to seven pages. A particularly interesting and valuable feature is that there are some synthesis articles here that would not otherwise have been written for a regular journal or book. The first section concerns mantle and magmatic processes. It includes a comprehensive review of almost all possible features of basaltic volcanoes (Walker), a 3D update of O'Hara's views of trace-element behaviour during melting and in magma chambers, a synthesis of possible petrogenetic models to explain the wide variety of
lavas erupted at the Galapagos hotspot (McBirney), and some penetrating comments on the nature of the lithosphere beneath China (Menzies et al.). There are few petrologists who wouldn't find something useful here. The second section (11 papers) deals with ophiolites and oceanic crust, with particular useful summaries of relationships in the Troodos Complex and other Tethyan ophiolites. As there are well over 100 publications on Troodos, and more on other Tethyan complexes, readers might find these syntheses a valuable source of lecture material. Of course, if Troodos actually represents the accreted forearc of a primitive Tethyan island-arc system (like forearc spreading in primitive West Pacific arcs: see Stern & Bloomer, 1992, BGSA 104: 1621-1636) then using Troodos as a classic model for ocean crust accretion may need to be revised. Robertson & Xenophontos fully discuss development of concepts concerning Troodos, Dietrich & Spencer the extension-related faulting, MacLeod & Murton focus on the Arakapas fossil transform zone, Malpas et al. evaluate the associated Mamonia Complex rocks in relation to Troodos, and Shelton re-evaluates gravity evidence for the structure of Troodos. In the wider field, Smith provides a very useful synthesis of all the Hellenic-Dinaric ophiolites, Bartholomew discusses the significance of mantle fabrics, and there interesting contributions by Roberts & Neary and by Prichard & Lord on Cr and P G E mineralisation, respectively, in ophiolites. Finally, Elderfield et al. assess the global significance of mid-ocean ridge hydrothermal ac-
295
B o o k ret, iews
tivity in the light of recent results on the TAG hydrothermal field; Menzies et al. follow this with experimental studies of the effect of basaltseawater interaction on trace elements and isotope ratios. The fourth section, dealing with convergent plate margins, is more varied. Dewey et al. further develop concepts of orogenic collapse and argue that coesite-bearing eclogites indicate precollapse crustal thicknesses of 120 km. Shackleton provides an improved tectonic interpretation of the late Proterozoic Mozambique Belt in East Africa, while Harris et al. discuss the geochemistry of crustal growth processes in the late Proterozoic of the Arabian Shield. A different approach is provided by Pearce and Parkinson who use trace element models to clarify the magma generating processes in modern island arcs, in particular trying to clarify the contributions from the slab and from the mantle wedge. Many will welcome the review by Wyllie & Wolf in appraising all the experimental work related to the melting of amphibolite, pertinent to subduction zones. A final paper by Vita-Finzi considers Recent uplift in the Eastern Mediterranean. The final section contains papers on rifting and the start of the Wilson Cycle. MacDonald & Upton compare and contrast magmatism in the Proterozoic Gardar zone with that in the East African Rift system; models for both require un-
derplating and lithospheric thinning, but it is not easy to account for the differences. Cox et al. then provide an update of the petrogenesis of the alkali basalts of Yemen, a study began almost 30 yrs ago with Ian Gass; Rogers compares the geochemistry of basalts from the volcanic islands of the southern Red Sea with those from the adjacent Rift systems and tries to account for differences in terms of plume activity and the degree of extension. Davis et al. interpret the compositions of Tertiary basalts from New Mexico in terms of variable asthenosphere-lithosphere interaction. The last word comes from Walker who discusses the mechanics of dyke intrusion on Skye. Almost as an Appendix, there is a paper by Potts et al. reviewing historically advances in analytical geochemistry. This reflects well the importance that Ian Gass attached to progressively developing (from nothing) advanced geochemical instrumentation in order to support a viable Petrological Research Group. In summary, the volume contains quite a number of excellent review or synthesis papers that many geoscientists will find valuable aids to teaching or research. The Editors have done a good job. There are few errors, and there is a useful index. JOHN TARNEY (Leicester, UK) SSDI
0040-1951(94)00097-S
Introduction to Elastic Wave Propagation, by A. Bedford and D.S. Drumheller, John Wiley & Sons, Chichester, U.K., 1994, Hardcover, XIII + 297 pp. Price £39.95 (ISBN 0-471-93884-X) This volume is the latest entry into the already well-populated field of elastic wave propagation pedagogy. The competition is stiff. There are numerous books on the subject, including those by Achenbach, Aki and Richards, Ben Menahem and Singh, Hudson, Kennett, Miklowitz, Pilant, Teisseyre. My apologies go to authors whose books are not listed here. To enter into this competition requires an act of courage; one must acknowledge the valor of the authors. The cover to the book tells us that the audience is the engineering community, but with an
acknowledgment to the earthquake, exploration, deeper earth structure, nondestructive testing and medical communities. Tantalized by an agenda that would cater to such a broad audience, I opened this book eagerly to explore how it might be used in my own course in elastic waves, which is also directed toward geophysicists and engineers. What I found was a book that put forth the fundamentals of elastic wave propagation, but did not get into the applications. For the geophysicist, there is no treatment of wave propagation in multilayered media, free oscillations, attenuation,