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Non-biostratigraphical methods of dating and correlation
172
Rook rer~iew.s
one must work with models that describe reality as closely as possible. The approach in this book is to attempt to describe the fundamental processes as completely as possible, which at local scales may be possible, but which at regional scales may lead to models of great complexity with impossible data requirements. The scale issue returns repeatedly as “modelling migrain”linking processes at different scales, or modelling the large-scale effects of small-scale processes remains difficult. What are the limits for environmental modelling-conceptual formulation, availability of data or computer power? Different authors cite different reasons; in particular the global climate modellers dream of massively parallel computers, while others cite lack of data or insufficient insights into the physical processes. The answer will be a combination of all three, for as computers provide more power, and automated data recording and collection provide more data, so we will achieve new insights, which will of course require new conceptual models. The “grand challenge” has a long time to run yet. P.A. Burrough, Utrecht SSDI 0012-8252(95)00048-8
Geochronology
R.E. Dunay and E.A. Hailwood (Editors), 1995. Non-biostratigraphical Methods of Dating and Correlation. Geological Society Special Publication No. 89. The Geological Society, London, U.K. Hardcover, 265 pp. Price: f60.00. ISBN l-897799-30-6. In a book titled Non-biostratigraphical methods of dating and correlation, we immediately expected to see geochronological papers on state of the art 4oAr/ 39Ar, i4C and cosmogenic isotope exposure ages; and correlation papers on methods such as magnetostratigraphy, paleomagnetic susceptibility, tephrostratigraphy, seismic sequence stratigraphy, 180 and i3C isotope stratigraphy and geochemical fingerprinting of lavas and
intrusives. These topics are not found in this book. Instead it contains a selection of papers on techniques that pertain mainly to petroleum exploration studies of sedimentary rocks from drill core samples and data. The Editors (Dunay and Hailwood) acknowledge the real focus of the book in their introduction and note the important omission of paleomagnetic and susceptibility studies. The geographical coverage of the papers presented are rather bipolar and unbalanced. Of the eleven papers, most relate to the European region and in particular the North Sea oil fields, with a notable exception of one solely on Australia, and a study that includes Thailand. The stratigraphic coverage is also selective. All of the papers are on Mesozoic or Paleozoic strata (mostly older than Triassic), except two that focus solely on the Quaternary. Papers in this publication demonstrate the difficulty of dating and correlation of non-fossiliferous strata when only partial cores or cuttings are available to work with. The first two papers (Morton and Hurst; Mange-Rajetzky) describe the use of heavy mineral mineralogy (e.g. zircon, tourmaline) for provenance studies, but also refer to the correlation potential. It would appear that mineral morphology is relied on heavily. The next paper by Jeans discusses clay mineralogy of sedimentary rocks and the problems posed by diagenesis. Carter et al. present work on zircon and apatite fission-track dating and paleotemperature histories of red beds. They clearly demonstrate the chronological potential of these methods, even when the thermal history of the sediments is uncertain. Racey et al. use ICP-AES to geochemically fingerprint sedimentary rocks. This bulk sample method can be affected by diagenesis and mineralogical heterogeneity. We note that they determined some of their SiO, contents by difference from lOO%, for quartz-rich rocks! This work shows some potential for discriminating rocks from different well sites, but little for positive correlation between sites. Using a similar laboratory approach, Pearce and Jarvis present work on the geochemical correlation of Quaternary turbidites (with great success). Using a variety of major and trace elements they can correlate individual units for several hundred km, and can even
Book Reviews
trace lateral variations caused by mineralogical sorting and depletion. There is no coverage of other geochemical analytical techniques such as XRF, electron microprobe, and ICP-MS that can provide a variety of data on minerals and whole rocks, and are now rapid and cost effective (important in the oil industry). Three isotopic dating methods are offered in the book. First, the use of an ion-probe to determine spot U-Pb ages on zircon crystals from tuffs is nicely highlighted by Roberts et al. Using a 20 pm beam they can obtain Carboniferous ages with an uncertainty of 5 Ma, which rivals “‘Ar/ 39Ar data. The direct dating of ancient sedimentary rocks remains a problem. Russell demonstrates the use of direct Pb-Pb dating of stromatoporoids, but there are still problems with diagenesis of some samples. Dalland et al. discuss the use of Sm-Nd provenance ages in correlation studies. A brief review of luminescence dating is presented by Rendell, who notes the new focus on optical studies as opposed to thermoluminescence. It would appear that many of these studies still require testing by independent age control. Surprisingly, seismic sequence stratigraphy or the recognition and correlation of sedimentary cycles within basins did not receive significant coverage in this book. These subjects are very topical in sedimentary geology. However, the final paper (Yang and Kouwe) deals with cyclicity analysis from wireline log data. As a book on techniques applicable to petroleum exploration (as intended), the collection of papers serves their purpose well. However, in this context it would seem that luminescence and ion probe U-Pb studies are out of place. As a book on dating and correlation in general, as the title implies, the coverage is unbalanced and many major techniques are omitted. A minor change to the title to restrict it to petroleum studies would have been in order. Nevertheless, it is exciting to see that the sole reliance on fossil remains for chronology is diminishing in the wake of new techniques to replace or complement existing age data. This book shows the growing interest in studying terrestrial and
17.7
other nonfossiliferous strata, which traditionally has received less attention. T. Black and P. Shane, Toronto,
Ont.
SSDI 0012-8252(95)00054-2
Metamorphism
Ralph Kretz, 1994. Metamorphic Crystallization. John Wiley & Sons, Chichester, pp. xiv + 506. Price: f22.50. ISBN O-471-94214-6 The purpose of this book is stated to be an “introduction to the science of metamorphism, prepared for senior undergraduate and graduate students in geology and geochemistry” (p. xi). The author tried to achieve this goal by combining standard geology and petrology with two modern theoretical approaches (equilibrium and non-equilibrium thermodynamics) and information deduced from material science, especially crystal growth. The outcome is excellent, but the goal is only partially achieved: many obscure points remain which defy a satisfactory result at the student level. However, this approach will certainly be followed, and in the near future will probably turn out to be a workable one even for undergraduates. Out of the five very long chapters of this book the first one, which covers the geological background with such conventional points as the definition of metamorphism, metamorphic minerals, assemblages, zones, facies and isograds (pp. l-52), appears to be the one which is indeed comprehensive but too concise to be an introduction, unless for skilled graduate students; it is not exactly adequate for an introductory book aimed at undergraduates, and is better suited to refresh information to anyone already well acquainted with the subject. Moreover, I find that something is lacking, e.g. a deeper treatment of the relationships existing between plate tectonics and metamorphism would have added valuably. In the second chapter Kretz shifts to equilibrium thermodynamics, and gives an excellent sur-
Rook rer~iew.s
one must work with models that describe reality as closely as possible. The approach in this book is to attempt to describe the fundamental processes as completely as possible, which at local scales may be possible, but which at regional scales may lead to models of great complexity with impossible data requirements. The scale issue returns repeatedly as “modelling migrain”linking processes at different scales, or modelling the large-scale effects of small-scale processes remains difficult. What are the limits for environmental modelling-conceptual formulation, availability of data or computer power? Different authors cite different reasons; in particular the global climate modellers dream of massively parallel computers, while others cite lack of data or insufficient insights into the physical processes. The answer will be a combination of all three, for as computers provide more power, and automated data recording and collection provide more data, so we will achieve new insights, which will of course require new conceptual models. The “grand challenge” has a long time to run yet. P.A. Burrough, Utrecht SSDI 0012-8252(95)00048-8
Geochronology
R.E. Dunay and E.A. Hailwood (Editors), 1995. Non-biostratigraphical Methods of Dating and Correlation. Geological Society Special Publication No. 89. The Geological Society, London, U.K. Hardcover, 265 pp. Price: f60.00. ISBN l-897799-30-6. In a book titled Non-biostratigraphical methods of dating and correlation, we immediately expected to see geochronological papers on state of the art 4oAr/ 39Ar, i4C and cosmogenic isotope exposure ages; and correlation papers on methods such as magnetostratigraphy, paleomagnetic susceptibility, tephrostratigraphy, seismic sequence stratigraphy, 180 and i3C isotope stratigraphy and geochemical fingerprinting of lavas and
intrusives. These topics are not found in this book. Instead it contains a selection of papers on techniques that pertain mainly to petroleum exploration studies of sedimentary rocks from drill core samples and data. The Editors (Dunay and Hailwood) acknowledge the real focus of the book in their introduction and note the important omission of paleomagnetic and susceptibility studies. The geographical coverage of the papers presented are rather bipolar and unbalanced. Of the eleven papers, most relate to the European region and in particular the North Sea oil fields, with a notable exception of one solely on Australia, and a study that includes Thailand. The stratigraphic coverage is also selective. All of the papers are on Mesozoic or Paleozoic strata (mostly older than Triassic), except two that focus solely on the Quaternary. Papers in this publication demonstrate the difficulty of dating and correlation of non-fossiliferous strata when only partial cores or cuttings are available to work with. The first two papers (Morton and Hurst; Mange-Rajetzky) describe the use of heavy mineral mineralogy (e.g. zircon, tourmaline) for provenance studies, but also refer to the correlation potential. It would appear that mineral morphology is relied on heavily. The next paper by Jeans discusses clay mineralogy of sedimentary rocks and the problems posed by diagenesis. Carter et al. present work on zircon and apatite fission-track dating and paleotemperature histories of red beds. They clearly demonstrate the chronological potential of these methods, even when the thermal history of the sediments is uncertain. Racey et al. use ICP-AES to geochemically fingerprint sedimentary rocks. This bulk sample method can be affected by diagenesis and mineralogical heterogeneity. We note that they determined some of their SiO, contents by difference from lOO%, for quartz-rich rocks! This work shows some potential for discriminating rocks from different well sites, but little for positive correlation between sites. Using a similar laboratory approach, Pearce and Jarvis present work on the geochemical correlation of Quaternary turbidites (with great success). Using a variety of major and trace elements they can correlate individual units for several hundred km, and can even
Book Reviews
trace lateral variations caused by mineralogical sorting and depletion. There is no coverage of other geochemical analytical techniques such as XRF, electron microprobe, and ICP-MS that can provide a variety of data on minerals and whole rocks, and are now rapid and cost effective (important in the oil industry). Three isotopic dating methods are offered in the book. First, the use of an ion-probe to determine spot U-Pb ages on zircon crystals from tuffs is nicely highlighted by Roberts et al. Using a 20 pm beam they can obtain Carboniferous ages with an uncertainty of 5 Ma, which rivals “‘Ar/ 39Ar data. The direct dating of ancient sedimentary rocks remains a problem. Russell demonstrates the use of direct Pb-Pb dating of stromatoporoids, but there are still problems with diagenesis of some samples. Dalland et al. discuss the use of Sm-Nd provenance ages in correlation studies. A brief review of luminescence dating is presented by Rendell, who notes the new focus on optical studies as opposed to thermoluminescence. It would appear that many of these studies still require testing by independent age control. Surprisingly, seismic sequence stratigraphy or the recognition and correlation of sedimentary cycles within basins did not receive significant coverage in this book. These subjects are very topical in sedimentary geology. However, the final paper (Yang and Kouwe) deals with cyclicity analysis from wireline log data. As a book on techniques applicable to petroleum exploration (as intended), the collection of papers serves their purpose well. However, in this context it would seem that luminescence and ion probe U-Pb studies are out of place. As a book on dating and correlation in general, as the title implies, the coverage is unbalanced and many major techniques are omitted. A minor change to the title to restrict it to petroleum studies would have been in order. Nevertheless, it is exciting to see that the sole reliance on fossil remains for chronology is diminishing in the wake of new techniques to replace or complement existing age data. This book shows the growing interest in studying terrestrial and
17.7
other nonfossiliferous strata, which traditionally has received less attention. T. Black and P. Shane, Toronto,
Ont.
SSDI 0012-8252(95)00054-2
Metamorphism
Ralph Kretz, 1994. Metamorphic Crystallization. John Wiley & Sons, Chichester, pp. xiv + 506. Price: f22.50. ISBN O-471-94214-6 The purpose of this book is stated to be an “introduction to the science of metamorphism, prepared for senior undergraduate and graduate students in geology and geochemistry” (p. xi). The author tried to achieve this goal by combining standard geology and petrology with two modern theoretical approaches (equilibrium and non-equilibrium thermodynamics) and information deduced from material science, especially crystal growth. The outcome is excellent, but the goal is only partially achieved: many obscure points remain which defy a satisfactory result at the student level. However, this approach will certainly be followed, and in the near future will probably turn out to be a workable one even for undergraduates. Out of the five very long chapters of this book the first one, which covers the geological background with such conventional points as the definition of metamorphism, metamorphic minerals, assemblages, zones, facies and isograds (pp. l-52), appears to be the one which is indeed comprehensive but too concise to be an introduction, unless for skilled graduate students; it is not exactly adequate for an introductory book aimed at undergraduates, and is better suited to refresh information to anyone already well acquainted with the subject. Moreover, I find that something is lacking, e.g. a deeper treatment of the relationships existing between plate tectonics and metamorphism would have added valuably. In the second chapter Kretz shifts to equilibrium thermodynamics, and gives an excellent sur-