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Geochronology and Thermochronology by the 40Ar39Ar Method
0016.7037189153.W + .XJ
Gedwmco ec Cosmochimrca Am Vol. 53. pp. 3107-3109 Copyright 0 1989 Pergamon Press pk.Pnnted in U.S.A.
BOOK REVIEWS
Geochronology and Thermochronology b.v the ‘OAr/j9Ar Method by Ian McDouaall and T. Mark Hatison. Oxford University Press, 1988, 212p., U.S.%SS.OO(ISBN O-19-504302-2). SINCE THE 40Ar/39ArMETHOD of K-Ar dating was lint conceived in the mid-1960s its usefulness to geology has steadily increased. In its various forms it can be used to determine the ages of altered and thermally disturbed rocks, decipher thermal histories of complex terrains, and measure the ages of single crystals weighing as little as I 0m6 grams. It is, without question, the most versatile dating technique in the geochronologists’ bag of tricks. Over the past quarter century the literature of 4oAr/39Ardating has grown with the increasing application and versatility of the method. What has been lacking, however, is a comprehensive review of the methodology and its application. That deficiency has now been fixed with the appearance of this new book by Ian McDougall, one of the pioneers of K-Ar dating, and his former student, Mark Harrison, who has become one of the leading authorities in 40Ar/39Artherm~hronology. The book contains six chapters. Chapter 1 is introductory and contains primarily a brief history of the development of the method. The basis of the 40Ar/39Armethod. including the derivation of the necessary equations and a discussion of the suitability of various minerals and rocks for dating. is the subject of Chapter 2. Chapter 3 is concerned with the technical aspects of the method and contains discussions of (1) the characteristics of the various nuclear reactors used for 40Ar/“9Ardating, (2) the interfering neutron reactions with Ca, K, and Cl, (3) the optimization of irradiation parameters, (4) some of the effects that large doses of fast neutrons have on samples.
(5) the extraction apparatus and mass spectrometers used for the analyses, and (6) the equations used for reduction of the raw Arisotope data. The incremental heating method, including the theory, use, and interpretation of age spectra and isotope correlation diagrams are discussed in Chapter 4. The subject of Chapter 5 is thermochronology, the means by which geochronologists attempt to calculate environmental temperature as a function of time. This chapter provides a solid theoretical and mathematical foundation for this increasingly important and rapidly advancing use of ~Ar/39Ar data. Chapter 6 contains a few case histories of the application of the “Ar/ 39Artechnique to the solution of some geological problems; included are examples from the literature of lunar geochronology’, as well as from studies involving both episodic and slow heating. This is a very good book. Despite its modest size, it gives thorough coverage to the various aspects of “Ar/39Ar dating and reflects the authors’ considerable expertise in the subject. It contains answers and information for the expert as well as the uninitiated. The book is also well-written and nicely produced, with a practical but pleasing design and a readable type on decent stock. It is an essential addition to the bookshelf of anyone who works in the field of&A@‘Ar dating, utilizes 40Ar/39Ardata in their research, or has occasion to rely on. or even refer to, the 40Ar/39Arliterature. If your work involves the Earth, Moon, or meteorites, then I suggest you keep a copy close at hand. You will not regret it. U.S. Geological Survey Branch of isotope Geolog) ~~enlo Park CA 94025. t’S.A.
Highlights in Gravitation and Cosmology edited by B. R. Iyer, A. Kembhavi, J. V. Narlikar, and C. V. Vishveshwara. Cambridge University Press. 1988, 44tp., cloth U.S. $59.50. (ISBN O-52136 1125-7).
G. Brent Dalrymple
made from a “camera ready” format resulting in a style largely determined by the authors. This leads to a format that is as uneven as the scientific content. However. for any scientist interested in the development of general relativity during the past quarter century, there is much of interest here that can be comprehended. The reviews of exact solutions to Einstein’s equation by MacCullum and the conventional view of astrophysical cosmology by Longhair were ~~~cuiarly thorough, with the latter being exceptionally well written. MacCullum’s observations on the rediscovery of exact solutions seem to have wider implications to the depth of scholarly research in general than just this specific area of genera1 relativity. Some of the papers by distinguished astrophysicists were di~p~inting, perhaps because I expected more from them based on their past work. Even allowing for my lack of expertise in the field, the papers on quantum gravity were particularly difficult to follow. However, the paper by Astekar on “New perspectives in canonical quantum gravity” is worth perusing if for no other reason than the glimpses of the “holy grail” of physics “seen through a glass darkly” that it urovides the reader. The papers on Black Holes and Compact Objects are largely comprehensible, and the summary of the workshop on Hawking radiation is quite interesting. It certainly seems that this volume contains papers that researchers in the areas mentioned above wit1want to reference. While the book seems a bit “pricey” for the physicist with a casual interest in these subjects, it does warrant a trip to the library and perhaps an afternoon of browsing.
A QUARTER OF A CENTURY AGO at the First Texas Symposium on Relativity Theory and Astrophysics, relativists and astrophysicists met and surprised each other. The announcement by Maarten Schmidt of the discovery of what came to be called quasars brought new physical relevance to the field of general relativity. This field has become a wide ranging and multifaceted discipline with each facet becoming so specialized that the experts have trouble understanding each other. This book contains the proceedings of the international conference on ~vitation and cosmology held at Goa, India, in December of 1987, and is a fine example ofthe fruits ofthe rejuvenation spawned by that symposium. Like most conferences, the scope is broader than is prudent for the time allowed and the range in papers is larger than the average reader can hope to encompass. Thus, it is likely that no single individual will feel comfo~ble with all aspects ofthese proceedings. However, the very breadth of the subject matter means that there is something for almost everybody who has a nodding acquaintance with general relativity or cosmology. The proceedings have been organized into five main areas: Classical Relativity, quantum Gravity. Cosmology, Black Holes and Comoact Objects, &dGravitational Radiation and Gravity Experiments. Each area contains a number of invited papers which range from broad reviews to highly technical reports of work in progress. In addition to these papers. a workshop was held on the first four areas mentioned above. The results of these workshops are summarized by a designated author. Like most recent conference proceedings, the publication is
Department ofdstronom) Ohio State University Columbxs, OH 43210-i 106, U.S.A. 3107
George W. Collins II
Gedwmco ec Cosmochimrca Am Vol. 53. pp. 3107-3109 Copyright 0 1989 Pergamon Press pk.Pnnted in U.S.A.
BOOK REVIEWS
Geochronology and Thermochronology b.v the ‘OAr/j9Ar Method by Ian McDouaall and T. Mark Hatison. Oxford University Press, 1988, 212p., U.S.%SS.OO(ISBN O-19-504302-2). SINCE THE 40Ar/39ArMETHOD of K-Ar dating was lint conceived in the mid-1960s its usefulness to geology has steadily increased. In its various forms it can be used to determine the ages of altered and thermally disturbed rocks, decipher thermal histories of complex terrains, and measure the ages of single crystals weighing as little as I 0m6 grams. It is, without question, the most versatile dating technique in the geochronologists’ bag of tricks. Over the past quarter century the literature of 4oAr/39Ardating has grown with the increasing application and versatility of the method. What has been lacking, however, is a comprehensive review of the methodology and its application. That deficiency has now been fixed with the appearance of this new book by Ian McDougall, one of the pioneers of K-Ar dating, and his former student, Mark Harrison, who has become one of the leading authorities in 40Ar/39Artherm~hronology. The book contains six chapters. Chapter 1 is introductory and contains primarily a brief history of the development of the method. The basis of the 40Ar/39Armethod. including the derivation of the necessary equations and a discussion of the suitability of various minerals and rocks for dating. is the subject of Chapter 2. Chapter 3 is concerned with the technical aspects of the method and contains discussions of (1) the characteristics of the various nuclear reactors used for 40Ar/“9Ardating, (2) the interfering neutron reactions with Ca, K, and Cl, (3) the optimization of irradiation parameters, (4) some of the effects that large doses of fast neutrons have on samples.
(5) the extraction apparatus and mass spectrometers used for the analyses, and (6) the equations used for reduction of the raw Arisotope data. The incremental heating method, including the theory, use, and interpretation of age spectra and isotope correlation diagrams are discussed in Chapter 4. The subject of Chapter 5 is thermochronology, the means by which geochronologists attempt to calculate environmental temperature as a function of time. This chapter provides a solid theoretical and mathematical foundation for this increasingly important and rapidly advancing use of ~Ar/39Ar data. Chapter 6 contains a few case histories of the application of the “Ar/ 39Artechnique to the solution of some geological problems; included are examples from the literature of lunar geochronology’, as well as from studies involving both episodic and slow heating. This is a very good book. Despite its modest size, it gives thorough coverage to the various aspects of “Ar/39Ar dating and reflects the authors’ considerable expertise in the subject. It contains answers and information for the expert as well as the uninitiated. The book is also well-written and nicely produced, with a practical but pleasing design and a readable type on decent stock. It is an essential addition to the bookshelf of anyone who works in the field of&A@‘Ar dating, utilizes 40Ar/39Ardata in their research, or has occasion to rely on. or even refer to, the 40Ar/39Arliterature. If your work involves the Earth, Moon, or meteorites, then I suggest you keep a copy close at hand. You will not regret it. U.S. Geological Survey Branch of isotope Geolog) ~~enlo Park CA 94025. t’S.A.
Highlights in Gravitation and Cosmology edited by B. R. Iyer, A. Kembhavi, J. V. Narlikar, and C. V. Vishveshwara. Cambridge University Press. 1988, 44tp., cloth U.S. $59.50. (ISBN O-52136 1125-7).
G. Brent Dalrymple
made from a “camera ready” format resulting in a style largely determined by the authors. This leads to a format that is as uneven as the scientific content. However. for any scientist interested in the development of general relativity during the past quarter century, there is much of interest here that can be comprehended. The reviews of exact solutions to Einstein’s equation by MacCullum and the conventional view of astrophysical cosmology by Longhair were ~~~cuiarly thorough, with the latter being exceptionally well written. MacCullum’s observations on the rediscovery of exact solutions seem to have wider implications to the depth of scholarly research in general than just this specific area of genera1 relativity. Some of the papers by distinguished astrophysicists were di~p~inting, perhaps because I expected more from them based on their past work. Even allowing for my lack of expertise in the field, the papers on quantum gravity were particularly difficult to follow. However, the paper by Astekar on “New perspectives in canonical quantum gravity” is worth perusing if for no other reason than the glimpses of the “holy grail” of physics “seen through a glass darkly” that it urovides the reader. The papers on Black Holes and Compact Objects are largely comprehensible, and the summary of the workshop on Hawking radiation is quite interesting. It certainly seems that this volume contains papers that researchers in the areas mentioned above wit1want to reference. While the book seems a bit “pricey” for the physicist with a casual interest in these subjects, it does warrant a trip to the library and perhaps an afternoon of browsing.
A QUARTER OF A CENTURY AGO at the First Texas Symposium on Relativity Theory and Astrophysics, relativists and astrophysicists met and surprised each other. The announcement by Maarten Schmidt of the discovery of what came to be called quasars brought new physical relevance to the field of general relativity. This field has become a wide ranging and multifaceted discipline with each facet becoming so specialized that the experts have trouble understanding each other. This book contains the proceedings of the international conference on ~vitation and cosmology held at Goa, India, in December of 1987, and is a fine example ofthe fruits ofthe rejuvenation spawned by that symposium. Like most conferences, the scope is broader than is prudent for the time allowed and the range in papers is larger than the average reader can hope to encompass. Thus, it is likely that no single individual will feel comfo~ble with all aspects ofthese proceedings. However, the very breadth of the subject matter means that there is something for almost everybody who has a nodding acquaintance with general relativity or cosmology. The proceedings have been organized into five main areas: Classical Relativity, quantum Gravity. Cosmology, Black Holes and Comoact Objects, &dGravitational Radiation and Gravity Experiments. Each area contains a number of invited papers which range from broad reviews to highly technical reports of work in progress. In addition to these papers. a workshop was held on the first four areas mentioned above. The results of these workshops are summarized by a designated author. Like most recent conference proceedings, the publication is
Department ofdstronom) Ohio State University Columbxs, OH 43210-i 106, U.S.A. 3107
George W. Collins II