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The magnetic anisotropy of rocks
TECTONOPHYSICS Tectonophysics
230 (1994) 142
The Magnetic Anisotropy of Rocks, by D.H. Tarling and F. Hrouda.
Chapman and Hall, London, UK,
1993, xi + 217 pp., hardcover, f40.00, ISBN o-412-49880-4. This new book by Tarling and Hrouda should be of interest to paleomagnetists, rock magnetists, structural geologists, sedimentologists, volcanologists and other earth scientists since it is the only book available which covers magnetic anisotropy of rocks and sediments and its application to a wide range of physical earth processes. Anisotropy of magnetic susceptibility and anhysterestic remanence are rightfully enjoying increasing attention by earth scientists because magnetic anisotropy allows a reasonably quick and non-destructive method of examining rock and sediment fabrics. These fabrics can allow documentation of finite strain in deformed rocks, current flow directions in sediments and sedimentary rocks, primary depositional fabrics in sediments, magmatic flow in intrusive igneous rocks and tuffs, and regional metamorphic processes. For this reason, the book will probably be read and referred to by a wide spectrum of earth scientists. The book is divided into roughly two parts; the first three chapters cover the “how to” aspects of conducting magnetic anisotropy research. The first chapter explains the physical and theoretical background of magnetic anisotropy including an important section on statistical analysis of magnetic anisotropy results. Unfortunately, the authors urge the reader to use the shape and magnitude parameters developed by Jelinek and then proceed to use them throughout the book. Although these parameters are quite useful, this may give the wrong impression to the reader not fully engaged in the field since these parameters are not in wide use by magnetic anisotropy practitioners. The second chapter covers the magnetic properties of minerals and rocks and provides a useful summary of this topic. When the very important topic of deformation of the two most common magnetic minerals, magnetite and 0040-1951/94/$07.00 0 1994 Elsevier SSDI 0040-1951(93)E0200-E
Science
hematite, is discussed the authors inexplicably restrict their comments to mechanisms that occur at temperatures higher (650°C) than that experienced by rocks typically analyzed for magnetic anisotropy. The third chapter provides information about sampling, measurement and analysis of magnetic anisotropy results and will provide a good starting point for those interested in acquiring their own magnetic anisotropy results. The second part of the book provides examples of how magnetic anisotropy results may be used to investigate different earth processes. Two chapters are devoted to primary fabrics in sedimentary and igneous rocks and the magnetic fabrics of deformed rocks. The final chapter of the book essentially covers the prospects for future work. These last three chapters of the book are structured more as a survey of the literature rather than a synthesis of our current understanding of the topics. For this reason the major points can be somewhat difficult to extract. Since the coverage is heavily grounded in the literature, it has the advantage of bringing the reader up-todate fairly painlessly, but the potential for becoming outdated quickly. My only reservation about this portion of the book is that the literature actually cited appears to reflect the authors’ particular bias and is incomplete in some instances. For this reason it will give the reader a slightly biased understanding of the literature. In summary, the book by Tarling and Hrouda provides the only comprehensive book on a subject that is important to a wide range of earth scientists. If used as a starting point for learning how to acquire and analyze magnetic anisotropy data and for delving into the literature on this fascinating subject, the reader can’t go wrong.
B.V. All rights reserved
K.P. KODAMA
(Bethlehem, PA, USA)
230 (1994) 142
The Magnetic Anisotropy of Rocks, by D.H. Tarling and F. Hrouda.
Chapman and Hall, London, UK,
1993, xi + 217 pp., hardcover, f40.00, ISBN o-412-49880-4. This new book by Tarling and Hrouda should be of interest to paleomagnetists, rock magnetists, structural geologists, sedimentologists, volcanologists and other earth scientists since it is the only book available which covers magnetic anisotropy of rocks and sediments and its application to a wide range of physical earth processes. Anisotropy of magnetic susceptibility and anhysterestic remanence are rightfully enjoying increasing attention by earth scientists because magnetic anisotropy allows a reasonably quick and non-destructive method of examining rock and sediment fabrics. These fabrics can allow documentation of finite strain in deformed rocks, current flow directions in sediments and sedimentary rocks, primary depositional fabrics in sediments, magmatic flow in intrusive igneous rocks and tuffs, and regional metamorphic processes. For this reason, the book will probably be read and referred to by a wide spectrum of earth scientists. The book is divided into roughly two parts; the first three chapters cover the “how to” aspects of conducting magnetic anisotropy research. The first chapter explains the physical and theoretical background of magnetic anisotropy including an important section on statistical analysis of magnetic anisotropy results. Unfortunately, the authors urge the reader to use the shape and magnitude parameters developed by Jelinek and then proceed to use them throughout the book. Although these parameters are quite useful, this may give the wrong impression to the reader not fully engaged in the field since these parameters are not in wide use by magnetic anisotropy practitioners. The second chapter covers the magnetic properties of minerals and rocks and provides a useful summary of this topic. When the very important topic of deformation of the two most common magnetic minerals, magnetite and 0040-1951/94/$07.00 0 1994 Elsevier SSDI 0040-1951(93)E0200-E
Science
hematite, is discussed the authors inexplicably restrict their comments to mechanisms that occur at temperatures higher (650°C) than that experienced by rocks typically analyzed for magnetic anisotropy. The third chapter provides information about sampling, measurement and analysis of magnetic anisotropy results and will provide a good starting point for those interested in acquiring their own magnetic anisotropy results. The second part of the book provides examples of how magnetic anisotropy results may be used to investigate different earth processes. Two chapters are devoted to primary fabrics in sedimentary and igneous rocks and the magnetic fabrics of deformed rocks. The final chapter of the book essentially covers the prospects for future work. These last three chapters of the book are structured more as a survey of the literature rather than a synthesis of our current understanding of the topics. For this reason the major points can be somewhat difficult to extract. Since the coverage is heavily grounded in the literature, it has the advantage of bringing the reader up-todate fairly painlessly, but the potential for becoming outdated quickly. My only reservation about this portion of the book is that the literature actually cited appears to reflect the authors’ particular bias and is incomplete in some instances. For this reason it will give the reader a slightly biased understanding of the literature. In summary, the book by Tarling and Hrouda provides the only comprehensive book on a subject that is important to a wide range of earth scientists. If used as a starting point for learning how to acquire and analyze magnetic anisotropy data and for delving into the literature on this fascinating subject, the reader can’t go wrong.
B.V. All rights reserved
K.P. KODAMA
(Bethlehem, PA, USA)