3-D Structural Geology

3-D Structural Geology

Tectonophysics 320 (2000) 167–168 www.elsevier.com/locate/tecto Book review 3-D Structural Geology by R.H. Groshong. Springer-Verlag, Berlin, 1999, h...

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Tectonophysics 320 (2000) 167–168 www.elsevier.com/locate/tecto

Book review 3-D Structural Geology by R.H. Groshong. Springer-Verlag, Berlin, 1999, hardcover, xv+324 pp., ISBN 3-540-65422-4

Groshong has written a clear and straightforward book about the three-dimensional interpretation of geological structures with the use of maps, well-logs and seismic profiles. The book fills an interesting niche, being about three-dimensional problem-solving and interpretation in structural geology; there is little on the theoretical background to structures that is dealt with by various other textbooks. It is stated in the Introduction that the book is aimed at geoscience professionals, but I believe it would also be ideal for geology undergraduates. Good reference lists are provided, enabling further study beyond the introductory level of this book. The text is refreshingly free of verbiage, the figures are generally simple and clear in spite of the small size of the pages (155 mm× 235 mm), and the questions are linked well with the text. Chapter 1 gives an introduction to the elements of stratigraphic and structural geometries that are used to interpret geological maps. It provides an ideal introduction to the geometries of folds and faults for non-specialists. Chapter 2 is largely about trigonometry, discussing methods for locating points in three-dimensions, and for determining the dip of planes, orientations of lines and thicknesses of units from maps and wells. Contouring of beds and the use of structure contours are discussed in Chapter 3. Chapter 4 is about how dips of bedding may be used to interpret the three-dimensional geometry of folds. Chapter 5 deals with faults, fault displacements and unconformities, showing how

they may be recognised and their geometries characterised from a wide range of data-types. A range of fault-related subjects are dealt with in Chapter 6, including the more complicated geometries of cross-cutting and interacting faults. Chapter 7 gives guidelines for cross-section construction, and shows how cross-sections may be used to illustrate and interpret structures. Chapter 8 is a short discussion of validating three-dimensional interpretations of geological structures, and in particular of the use of restoration to the original, pre-deformation geometry. Throughout the book, the effects of measurement errors are discussed and emphasised. Although I believe this book is useful, well-written and well-illustrated, I do have some minor complaints. First, some important subjects are not dealt with. Relay ramps are described, but other types of transfer zones are not (e.g., Morley et al., 1990). There is discussion of the length to maximum displacement relationships of faults, but nothing else on fault scaling relationships, an important subject through the 1990s. Second, although I enjoy the economy of writing, brevity does lead to confusion in places. Again taking the section on relay ramps, there is an apparently selfcontradictory passage that reads: ‘‘Faults exhibiting a relay pattern may appear to be unrelated on a map because a single fault will have the displacement pattern of an isolated fault that dies out along strike (Figs. 5.31, 5.32a). The sympathetic variation of displacement on the two faults reveals their relationship to be that of displacement transfer.’’ So, does the displacement profile of a fault indicate transfer of displacement onto another fault via a relay ramp or not? Third, it is a shame that non-SI

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D.Peacock / Tectonophysics 320 (2000) 167–168

units are still being used in science around the start of the new millennium. Most figures do have a scale bar in SI units as well as non-SI units, but some only have non-SI units (e.g., Fig. 1.47). What are ‘decifeet’ ( Fig. 4.31)? Fourth, although the questions are clear and fairly simple, it is a shame that answers are not given. Readers may have benefited from worked examples.

References Morley et al., 1990. Bulletin of the American Association of Petroleum Geologists 74, 1234–1253.

David Peacock Department of Geology, State University of New York, Buffalo, NY 14260, USA