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Lacustrine petroleum source rocks
Book reviews sedimentary geochemical processes. Particularly useful features of the chapter are the careful, and in my experience unique, linkages made between organic and inorganic geochemical terminology and processes, and simple stochiometry and isotopic fractionations. The section on diagenesis discusses the depth sequence of oxidation, sulphate reduction, methanogenesis, and manganese and iron reduction with respect to organic matter contents, sedimentation rates and water column sulphate concentrations. While the section on diagenesis mentions the precipitation of early cements only in passing, the section on deeper catagenetic processes deals mainly with carbon and oxygen isotopic evidence for precipitation of ferroan dolomite and calcite resulting from kerogen or acetate decarboxylation and carbon dioxide (carbonic acid) evolution. A rather limited discussion of the development of secondary porosity and the precipitation of authigenic silicates in reservoirs follows. This chapter commendably ends with speculation on future research topics such as the role of clay mineral catalysis in oil generation reactions, and of early catagenetic reactions in permeability enhancement in migration pathways. The Organic Geochemistry of Aromatic Hydrocarbons is reviewed by Matthias Radke, who also discusses a significant amount of previously unpublished work. In an essentially chemical chapter, the basic structure of, and analytical procedures for. geoaromatics are outlined followed by a review of their presence in living organisms, recent sediments, ancient sediments (including coals) and crude oils. The bulk of the chapter relates to the application of aromatics in oil exploration, reviewing their use in thermal maturation studies (the author's specialist area), methyl and dimethyl phenanthrene and naphthalene ratios. A final brief section points to the utility of aromatics for the correlation of altered crude oils. Finally, a review by R. P. Philp on Surface Prospecting Methods for Hydrocarbon Accumulations provides an excellent survey of the literature but strangely provides no clear final recommendations on the utility of this contentious
approach. It is essentially an extension of an article written by the author and P. T. Crisp published in the Journal of Geochemical Exploration (Vol 17. pp. 1-34) in 1982. The chapter discusses separately onshore prospecting methods in terms of free, absorbed and dissolved gas analysis together with approaches used in interpreting the anomaly patterns recorded. In the offshore, examples of sniffers, sea floor sediment samples and gas bubble collection are reviewed. The final section of this chapter is a mish-mash of alternative methods including carbon isotopic analyses of free and absorbed gases or derived carbonate cements, soil helium, and microbiological soil culturing methods, in addition to low frequency electromagnetic induction, remote laser spectrometry and LandSat results. These latter techniques can be considered as direct imaging of surface hydrocarbon indicators (e.g. soil type, cements, special hydrocarbon-tolerant vegetation), or merely as indicators of surface geology (traps, fault lineations, etc.). In general, the book does not reflect its title. The subjects are not really advances in petroleum geochemistry but rather personal reviews of existing subject areas. Only in the case of R. W. Jones's chapter on Organic Facies (and parts of M. Radke's chapter) is an attempt made to advance the subject. Much of the criticism must be laid at the feet of the editors: some of the papers could have been greatly improved with tighter editorial control, ensuring consistency of thought, obviating typographic errors, spotting unlisted references and upgrading the index. The one outstanding omission is the lack of titles for the listed references: for a book purporting to provide topical reviews thiis is unforgivable. The book is well presented with clear text, pleasing typesetting and excellent reproduction of figures. 1-aken together with Volume 1, the series does provide documentation of modern petroleum geochemistry. I look forv~ard to seeing Volume 3 and hope that the constructive criticisms offered above will be addressed.
C. Cornford
Integrated Geochemical Interpretation Ltd, UK
Lacustrine Petroleum Source Rocks A. J. Fleet, K. Kelts and M. R. Talbot (Eds) Geological Society Special Publication No 40; Blackwell Scientific Publications; 1988; ISBN 0 632 01803 8. Price £75.00 This book is a collection of papers which were presented at a meeting held at the Geological Society in London in September 1988. Twenty five of the papers are presented in full and a further four presented as extended abstracts. The book addresses the problem that in spite of the fact that lacustrine sediments are of economic importance, their subsurface prediction is still at a rudimentary level, mainly due to the dominating interest of the oil industry in marine source rocks. The stated aims of the book are to bring together synthesised concepts, techniques and real examples in order to provide ideas for both the interpretation and prediction of lacustrine petroleum source rocks. To a large extent it achieves these objectives, but lays a greater emphasis on examples than on concepts and techniques. This is no criticism of the editors who were constrained by the papers offered to them. The papers included in the collection come from over 50 different authors and cover deposits from over l(/ countries ranging in age from Devonian to Recent. There is a strong emphasis on examples from Africa, UK, Australia and China. The papers from China offer a very interesting insight into some little studied basins. Aspects covered include topics as disparate as palaeoclimatology, stratigraphy and organic geochemistry, and yet the book maintains a holism by means of careful juxtapositioning of linked papers by the editors and by subdivision into three
linked sections dealing in turn with the tectonic, geological and biological features which bring about organic matter preservation in lake sediments, the palaeoenvironments of these sediments and finishing with a large section containing case studies. Part one contains four full papers and two extended abstracts. Kelts provides a useful introduction to the environments of deposition of lacustrine source rocks. The following extended abstract of a paper by Talling on modern phytoplankton is too short to do anything but transmit a few statistics on productivity. The following three papers by Talbot, DeDekber and Oremland et al. give good modern analogues and offer important insight into lacustrine depositional processes. Part 2 contains eight papers which concentrate mainly on geochemical and biological indications of palaeoenvironments. Here there is emphasis again on modern lake systems, with three papers concerned with African lake systems, one with a West German lake, two with general consideration of early diagenetic processes in modern sediments and only two with ancient lake deposits. The final section on case studies contains 13 full papers and two extended abstracts. The first three papers by Duncan and Hamilton, Hillier and Marshall and Powell deal with aspects of the geochemistry palaeolimnology and burial history of the Orcadian basin of Scotland. Following this there are two papers on the Dinantian Oil Shales of Scotland and one on a
Marine and Petroleum Geology, 1990, Vol 7, May
199
Book reviews Mesozoic rift basin in Virginia USA. Four papers cover some very interesting details of Chinese non-marine source rocks. In spite of some poor diagram quality, for example the paper by Brassell et al. On biological markers in Chinese oil shales, these papers provide a useful insight into the petroleum surce rocks in some of the world's less publicised non-marine basins. The remaining papers feature lake sequences from Australia, SE Asia, Spain and Africa, completing a vary varied and interesting group of case studies.
In general this book will be of interest to both academics working on non-marine deposits and to oil geologists wishing to maximise identification of potential petroleum source rocks. It contains papers which inevitably vary in quality, but good papers predominate. The editors are to be congratulted.
L. E. Frostick
Royal Holloway and Bedford New College,
University of London, UK
Productivity of the Ocean" Present and Past W. H. Berger, V. S. Smetacek and G. Wefer (Eds) John Wiley and Sons, 1989; ISBN 0 471 92246 3. Price: £65.00 As the preface of this book explains, it has become apparent over the last few years that the content of carbon dioxide in the atmosphere has changed considerably on time scales of thousands of years. The mechanisms producing these changes must largely be sought m the ocean, and especially in the fluctuating productivity of the ocean. This book is a report of the Dahlem Workshop on Productivity of the Ocean, held in Berlin, April 1988. This workshop brought together a selected tcam of marinc biologists, geochemists, palaeontologists and sedimentologists to assess the state of knowledge and ignorance concerning the processes which lead to the export of organic matter from the photic zone, its transit to the scafloor, and its burial within the sedimentary record, Their goal wits to clarify how productivity changes through time and how it can be reconstructed from biogenic signals within the sediment. Such reconstructions are necessarx m order to model the carbon dioxide fluctuations of the atmosphere on medium to long time-scales. The book is divided into four mare themes, each summarized bv a group report. I h e first part of the book is devoted to factors affecting primary productivity in the photic zone and the export of organic matter out of this zone to underlying waters or sediment. An mervicw of ocean productivity and palaeoproductivity by Bergcr c{ al. introduces some of the basic concepts. It is suggested that Quaternar} glacial episodes produced more vigorous circulation and higher primary productivity (especially new production based on inorganic nitrate and phosphate supply from below the photic zone), much of it exported below the photic zone during episodic blooms: this resulted in the removal of carbon dioxide from the atmosphere. In preglacial oceans, however. primary productivity is more likely to have been limited by the delivery of nutrients such its nitrate and phosphate. The export of organic matter is shown bv Peinert e; al. to be greatest all3ong svvarlrl grazers, such as fish, krill and salps. ~hich produce large faecal pellets that settle rapidly. ttvdrodvnamical singularities, such as upwelling zones, greatly increase the export production, according to Legendre and Le Fcxre, partly because of blooms of larger cells such as diatoms that sink more rapidly. But there may be too much of such emphasis on particulate organic matter, according to Toggweiler. who shows that dissolved organic carbon and nitrogen may be important, especially as a substrate for bacteria in the water column and on the scafloor. The nlethodology of assessing new production is reviewed by Eppelcy and the section closes with a group report which highlights some of the above points. An
important conclusion for the geologist is that primary productivity will be difficult to reconstruct, since it may rely on the regeneration of nutrients in the photic zone under stable hydrodynamic conditions: but the sediments may record evidence of higher export production during unstable conditions. The second theme of the book concerns the flux of organic matter to the seafloor. Here we discover that Ba 2* may be the best indicator of ocean surface productivity (Bishop), that deep sea sediments record seasonal surface productivity events (Wefer) and that mesopelagic herbiw~res are larger at higher latitudes aild may export more organic matter (Angel). The amount of shelf production reaching the deep sea floor is then reviewed by Walsh. followed by a second group report. This helpfully reviews tracers of palaeoproductivity such as biomarkcrs, biotninerals, carbon isotopes and trace metals. The third theme of thc book examines the transformation of fluxes arriving on the seafloor into the sedimentary record. Both bioturbation and anoxia ma 5 lead to greater "burial of carbon since deepcr, anaerobic diagencsis is less able to decompose less labile organic matter (Reimers). Stable carbon isotopes of fossil benthic foraminifera, which comprise up to 53".i, of benthic /',iomass, nlav reflect the pattern of global productivit> in cpifaunal species but of local pore water chemistry in hlfaunal species (Altenbach and Sarntheim). Lipid biomarkers may also provide a geochemical tool (Prahl and Muehlhausen). The final part of the book is concerned with geological reconstructions of marine productivity. Mix reviews the seminal work on Pleistocene forammifcral isotopes and the problems of distinguishing productivit 3 from anoxic gradients. The strong correlation between high nutrient concentrations and siliceous oozes ix rc\,'ie~xed by Barren and Baldauf, with reference to the Cenozoic. The enigmatic black shales of mid-Cretaceous times arc then examined by Thiersten and related, controversially, to slm~ deep water renewal and low fertility. Codispoti argues that nitrogen is the main limiting nutrient in present day oceans, though phosphorus may have been so in the past. A useful appendix is provided of global maps of ocean productivity by W. If. Berger. This is altogether a most useful, stimulating imd timely wflume that should greatly encourage this developing field of palaeoceanography.
M. Brasier
University of Oxford, UK
Carbonate Diagenesis and Porosity C.H. Moore Elsevier Science Publishers BV, 1989; ISBN 0 444 87416 X. Price: US$47.25; Df1490.000 Sedimentology is a vitally important discipline in the search for petroleum, but few attempts have been made in textbook format to demonstrate its application to the industry. This is
200
Marine and Petroleum Geology, 1990, Vol 7, May
the commendable objective of Clyde Moore's book Carbonate Diagenesis and Porosilr. The work is intended to be not simply a textbook on diagencsis, but also a handbook
approach. It is essentially an extension of an article written by the author and P. T. Crisp published in the Journal of Geochemical Exploration (Vol 17. pp. 1-34) in 1982. The chapter discusses separately onshore prospecting methods in terms of free, absorbed and dissolved gas analysis together with approaches used in interpreting the anomaly patterns recorded. In the offshore, examples of sniffers, sea floor sediment samples and gas bubble collection are reviewed. The final section of this chapter is a mish-mash of alternative methods including carbon isotopic analyses of free and absorbed gases or derived carbonate cements, soil helium, and microbiological soil culturing methods, in addition to low frequency electromagnetic induction, remote laser spectrometry and LandSat results. These latter techniques can be considered as direct imaging of surface hydrocarbon indicators (e.g. soil type, cements, special hydrocarbon-tolerant vegetation), or merely as indicators of surface geology (traps, fault lineations, etc.). In general, the book does not reflect its title. The subjects are not really advances in petroleum geochemistry but rather personal reviews of existing subject areas. Only in the case of R. W. Jones's chapter on Organic Facies (and parts of M. Radke's chapter) is an attempt made to advance the subject. Much of the criticism must be laid at the feet of the editors: some of the papers could have been greatly improved with tighter editorial control, ensuring consistency of thought, obviating typographic errors, spotting unlisted references and upgrading the index. The one outstanding omission is the lack of titles for the listed references: for a book purporting to provide topical reviews thiis is unforgivable. The book is well presented with clear text, pleasing typesetting and excellent reproduction of figures. 1-aken together with Volume 1, the series does provide documentation of modern petroleum geochemistry. I look forv~ard to seeing Volume 3 and hope that the constructive criticisms offered above will be addressed.
C. Cornford
Integrated Geochemical Interpretation Ltd, UK
Lacustrine Petroleum Source Rocks A. J. Fleet, K. Kelts and M. R. Talbot (Eds) Geological Society Special Publication No 40; Blackwell Scientific Publications; 1988; ISBN 0 632 01803 8. Price £75.00 This book is a collection of papers which were presented at a meeting held at the Geological Society in London in September 1988. Twenty five of the papers are presented in full and a further four presented as extended abstracts. The book addresses the problem that in spite of the fact that lacustrine sediments are of economic importance, their subsurface prediction is still at a rudimentary level, mainly due to the dominating interest of the oil industry in marine source rocks. The stated aims of the book are to bring together synthesised concepts, techniques and real examples in order to provide ideas for both the interpretation and prediction of lacustrine petroleum source rocks. To a large extent it achieves these objectives, but lays a greater emphasis on examples than on concepts and techniques. This is no criticism of the editors who were constrained by the papers offered to them. The papers included in the collection come from over 50 different authors and cover deposits from over l(/ countries ranging in age from Devonian to Recent. There is a strong emphasis on examples from Africa, UK, Australia and China. The papers from China offer a very interesting insight into some little studied basins. Aspects covered include topics as disparate as palaeoclimatology, stratigraphy and organic geochemistry, and yet the book maintains a holism by means of careful juxtapositioning of linked papers by the editors and by subdivision into three
linked sections dealing in turn with the tectonic, geological and biological features which bring about organic matter preservation in lake sediments, the palaeoenvironments of these sediments and finishing with a large section containing case studies. Part one contains four full papers and two extended abstracts. Kelts provides a useful introduction to the environments of deposition of lacustrine source rocks. The following extended abstract of a paper by Talling on modern phytoplankton is too short to do anything but transmit a few statistics on productivity. The following three papers by Talbot, DeDekber and Oremland et al. give good modern analogues and offer important insight into lacustrine depositional processes. Part 2 contains eight papers which concentrate mainly on geochemical and biological indications of palaeoenvironments. Here there is emphasis again on modern lake systems, with three papers concerned with African lake systems, one with a West German lake, two with general consideration of early diagenetic processes in modern sediments and only two with ancient lake deposits. The final section on case studies contains 13 full papers and two extended abstracts. The first three papers by Duncan and Hamilton, Hillier and Marshall and Powell deal with aspects of the geochemistry palaeolimnology and burial history of the Orcadian basin of Scotland. Following this there are two papers on the Dinantian Oil Shales of Scotland and one on a
Marine and Petroleum Geology, 1990, Vol 7, May
199
Book reviews Mesozoic rift basin in Virginia USA. Four papers cover some very interesting details of Chinese non-marine source rocks. In spite of some poor diagram quality, for example the paper by Brassell et al. On biological markers in Chinese oil shales, these papers provide a useful insight into the petroleum surce rocks in some of the world's less publicised non-marine basins. The remaining papers feature lake sequences from Australia, SE Asia, Spain and Africa, completing a vary varied and interesting group of case studies.
In general this book will be of interest to both academics working on non-marine deposits and to oil geologists wishing to maximise identification of potential petroleum source rocks. It contains papers which inevitably vary in quality, but good papers predominate. The editors are to be congratulted.
L. E. Frostick
Royal Holloway and Bedford New College,
University of London, UK
Productivity of the Ocean" Present and Past W. H. Berger, V. S. Smetacek and G. Wefer (Eds) John Wiley and Sons, 1989; ISBN 0 471 92246 3. Price: £65.00 As the preface of this book explains, it has become apparent over the last few years that the content of carbon dioxide in the atmosphere has changed considerably on time scales of thousands of years. The mechanisms producing these changes must largely be sought m the ocean, and especially in the fluctuating productivity of the ocean. This book is a report of the Dahlem Workshop on Productivity of the Ocean, held in Berlin, April 1988. This workshop brought together a selected tcam of marinc biologists, geochemists, palaeontologists and sedimentologists to assess the state of knowledge and ignorance concerning the processes which lead to the export of organic matter from the photic zone, its transit to the scafloor, and its burial within the sedimentary record, Their goal wits to clarify how productivity changes through time and how it can be reconstructed from biogenic signals within the sediment. Such reconstructions are necessarx m order to model the carbon dioxide fluctuations of the atmosphere on medium to long time-scales. The book is divided into four mare themes, each summarized bv a group report. I h e first part of the book is devoted to factors affecting primary productivity in the photic zone and the export of organic matter out of this zone to underlying waters or sediment. An mervicw of ocean productivity and palaeoproductivity by Bergcr c{ al. introduces some of the basic concepts. It is suggested that Quaternar} glacial episodes produced more vigorous circulation and higher primary productivity (especially new production based on inorganic nitrate and phosphate supply from below the photic zone), much of it exported below the photic zone during episodic blooms: this resulted in the removal of carbon dioxide from the atmosphere. In preglacial oceans, however. primary productivity is more likely to have been limited by the delivery of nutrients such its nitrate and phosphate. The export of organic matter is shown bv Peinert e; al. to be greatest all3ong svvarlrl grazers, such as fish, krill and salps. ~hich produce large faecal pellets that settle rapidly. ttvdrodvnamical singularities, such as upwelling zones, greatly increase the export production, according to Legendre and Le Fcxre, partly because of blooms of larger cells such as diatoms that sink more rapidly. But there may be too much of such emphasis on particulate organic matter, according to Toggweiler. who shows that dissolved organic carbon and nitrogen may be important, especially as a substrate for bacteria in the water column and on the scafloor. The nlethodology of assessing new production is reviewed by Eppelcy and the section closes with a group report which highlights some of the above points. An
important conclusion for the geologist is that primary productivity will be difficult to reconstruct, since it may rely on the regeneration of nutrients in the photic zone under stable hydrodynamic conditions: but the sediments may record evidence of higher export production during unstable conditions. The second theme of the book concerns the flux of organic matter to the seafloor. Here we discover that Ba 2* may be the best indicator of ocean surface productivity (Bishop), that deep sea sediments record seasonal surface productivity events (Wefer) and that mesopelagic herbiw~res are larger at higher latitudes aild may export more organic matter (Angel). The amount of shelf production reaching the deep sea floor is then reviewed by Walsh. followed by a second group report. This helpfully reviews tracers of palaeoproductivity such as biomarkcrs, biotninerals, carbon isotopes and trace metals. The third theme of thc book examines the transformation of fluxes arriving on the seafloor into the sedimentary record. Both bioturbation and anoxia ma 5 lead to greater "burial of carbon since deepcr, anaerobic diagencsis is less able to decompose less labile organic matter (Reimers). Stable carbon isotopes of fossil benthic foraminifera, which comprise up to 53".i, of benthic /',iomass, nlav reflect the pattern of global productivit> in cpifaunal species but of local pore water chemistry in hlfaunal species (Altenbach and Sarntheim). Lipid biomarkers may also provide a geochemical tool (Prahl and Muehlhausen). The final part of the book is concerned with geological reconstructions of marine productivity. Mix reviews the seminal work on Pleistocene forammifcral isotopes and the problems of distinguishing productivit 3 from anoxic gradients. The strong correlation between high nutrient concentrations and siliceous oozes ix rc\,'ie~xed by Barren and Baldauf, with reference to the Cenozoic. The enigmatic black shales of mid-Cretaceous times arc then examined by Thiersten and related, controversially, to slm~ deep water renewal and low fertility. Codispoti argues that nitrogen is the main limiting nutrient in present day oceans, though phosphorus may have been so in the past. A useful appendix is provided of global maps of ocean productivity by W. If. Berger. This is altogether a most useful, stimulating imd timely wflume that should greatly encourage this developing field of palaeoceanography.
M. Brasier
University of Oxford, UK
Carbonate Diagenesis and Porosity C.H. Moore Elsevier Science Publishers BV, 1989; ISBN 0 444 87416 X. Price: US$47.25; Df1490.000 Sedimentology is a vitally important discipline in the search for petroleum, but few attempts have been made in textbook format to demonstrate its application to the industry. This is
200
Marine and Petroleum Geology, 1990, Vol 7, May
the commendable objective of Clyde Moore's book Carbonate Diagenesis and Porosilr. The work is intended to be not simply a textbook on diagencsis, but also a handbook