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Nannofossils and their applications
Book reviews Let us begin with the text. This is generally very good and admirably avoids the tendency of palaeogeographic descriptions to sound like the weather forecast. There are refreshingly few unsupported descriptions of the mysterious rises and falls of the sea or 'phases of uplift'. Having said this, I feel that the text is still a little under-referenced in places, given that it will be widely used as an entry to the literature. The overviews at the beginning of each chapter are variable. My preference is for those, such as that for the Triassic, which give a clear picture of what rocks are where and how the stratigraphy has been divided for portrayal on the maps. I found the information on the definition of the Devonian System Global Stratotype Section and Point almost the last thing I wanted to know about the British Devonian. All of these introductory explanations would have been much improved by a chart showing the principal chronostratigraphic subdivisions of the period, the distribution of the principal lithostratigraphic units and the 'time slices' covered by the maps. Ideally, these would be linked to specific localities marked on the maps with some indication of biostratigraphic control, in the manner of the exemplary volumes published by the French Bureau de Recherches G~ologiques et Minidres. Without such a chart it is all too easy for those unfamiliar with a period to become lost in a maze of unfamiliar stratigraphic nomenclature. It is with the maps as definitive statements of what is known that I have the greatest problem. The separation
of observation (lithological symbols) from interpretation (environmental colours) has been well handled in a qualitative way, but there is no precise, quantitative information: one can only speculate as to the limit of outcrop or subcrop. Key sections and boreholes are not generally marked and referenced. There is no isopach information. Little has been done to characterize the bedrock geology or vegetation of areas of erosion. No palaeolatitude information has been included on the maps and there is no systematic attempt to address the wider issues of Britain's global palaeogeographic, climatic and oceanographic setting. In short, no answers will be found in this volume to so many questions which might be asked by the advanced student of British palaeogeography, and which might reasonably be addressed given the immense scope of British stratigraphic and sedimentological research. To be fair, the production of such a suite of maps would be a prodigious undertaking requiring commitment, one suspects, well beyond that which most of the authors of this volume felt able to contribute. In conclusion, as a definitive work on British stratigraphy the atlas is disappointing and does not justify its £295 price tag. It is, however, a very useful summary and, having acquired a copy, I am sure that I will refer to it frequently.
Neil Parkinson
Department of Earth Sciences, University of Oxford, UK
Nannofossils and Their Applications Edited by J. A. Crux and S. E. van Heck Ellis Horwood British Micropalaeontological Society Series; 1989; ISBN 0 7458 0237 0; 356 pp. Price: £69.50 Fourteen of the research papers scheduled for presentation at the International Nannofossil Association Conference in London in 1987 are brought together in this 356-page volume. Although these papers vary widely in subject matter, they are loosely bound under the sectional headings: morphology, systematics and evolution; palaeoenvironmental and palaeogeographical applications; and biostratigraphical applications. However, there is a great deal of overlap between them. The opening paper is by Young who, through his investigations into the ontogeny, structure and geometry of heterococcolith rims, deduced their structural complexity to be primarily a result of elaborate crystal unit structure rather than the production of numerous separate cycles of crystal units. These ideas are presented in this paper with particular reference to the Reticulofenestra and so complements the paper by Gallagher. He presents a critical review of the taxonomy and evolution of the Reticulofenestra and its phylogenetic relationships with other noelaerhabdaceans. Evolutionary changes in rim structure are given primary importance at generic level, whereas central-area architecture is considered to be a specific ranking feature. A formal emendation of the genus is made, followed by a comprehensive classification of 45 commonly referenced Reticulofenestra species. This is an admirable piece of work which suffers only from the absence of an equally comprehensive set of SEM and light microscope photographs. Aubry presents her ideas on the importance of understanding the taxonomic relationships between nannofossil groups for the interpretation of processes behind geological events, commenting on the vista between the palaeontological concept of coccolithophorales species and the biological concept. A case for the use of phylogenetically based taxonomy for deciphering evolutionary patterns is presented, citing the Cretaceous-Tertiary boundary event as an example. Moshkovitz and Osmond review the optical properties of crystals and their application to the study of the taxonomy,
634
evolution and diagenesis of calcareous nannofossils. Exemplified by the Arkhangelskiellaceae and other Late Cretaceous nannofossils, this paper is accompanied by a wonderful set of photographs. The final paper in this section, by Bown and Cooper, is a review of the classificaton, morphology and evolutionary relationships between a number of conical nannofossils from the Mesozoic. The phenomenon of homeomorphy is used to explain the existence of these apparently unrelated lineages. The second section (palaeoenvironmental and palaeogeographic applications of nannofossils) begins with a paper by Gard on the nannoftoras of the last glacial cycle. She interprets the variations in distribution and relative abundance of assemblages from the North Atlantic and Indian Oceans as reflecting changing surface water conditions. This is the only Quaternary paper, with the remaining four papers of this section being Early Cretaceous studies. Two papers are presented on the temperature-controlled migrations of calcareous nannofossils in north-west Europe; firstly Mutterlose in the Aptian, followed by Crux on the Ryazanian to Barremian. They each cite examples during which the nannofloras exhibited strong Tethyan or Boreal-Arctic provincialism which they correlate with transgressions, regressions and palaeogeographic changes in north-west Europe. These rapid changes in nannofossil assemblages have enabled Crux to divide the Ryazanian to Barremian interval into 16 nannofossil zones which he integrates with macrofossil zonations. Fourteen plates illustrate the key species that Crux mentions throughout this comprehensive paper. Applegate et al. present a comparison between Neocomian nannofossil assemblages of the Tethyan circum-North Atlantic province with those of the Boreal North Sea, revealing major assemblage differences despite their geographical proximity. This provincialism is attributed to the existence of a land barrier isolating the North Sea from the Tethys during Late Valanginian to Late Barremian times. The final paper in this section by Cooper provides a global view of nannofossil
Marine and Petroleum Geology, 1993, Vol 10, December
Book reviews provincialism in the Kimmeridgian to Valanginian. He uses the quantitative analysis of nannofossil assemblages, grouped at family level, as a method with which to differentiate the Boreal and Tethyan Realms. The final section deals with the biostratigraphic applications of calcareous nannofossils. Flores and Sierro present a paper on the Tortonian-Messinian boundary interval of the north-east Atlantic, Spain and Morocco. They successfully test a succession of calcareous nannofossil and planktonic foraminiferal events previously established in the Guadalquivir basin (Spain). They report a trend towards the cooling of surface waters throughout this interval, punctuated by intermittent warm water pulses of varying intensity. The rapid evolutionary rates during the Palaeocene enable Varol to define two highly detailed Palaeocene calcareous nannofossil stratigraphies: one with global (low to mid latitude) application, the other specifically for the North Sea area. The key taxa are well illustrated in five plates. The Palaeogene theme continues with a paper by Toker in which a standard calcareous nannofossil zonation scheme for the Turkish Palaeocene-Eocene is presented. Eighteen zones are recognized (all previously published) attributing the absence of some zonal marker species to palaeoecological factors. The zones are correlated with planktonic foraminiferal zones to achieve greater stratigraphic resolution. The final paper by Girgis presents the results of a morphometric
analysis of the Arkhangelskiella group from Egyptian sequences of Maastrichtian-Danain age. Four distinct nannofossil units are identified which are stratigraphically useful, especially in the absence of conventional marker species. Palaeoenvironmental aspects are also considered, relating the reduction in size just before the K/T boundary to the onset of stressful environmental conditions. The editors have succeeded in controlling the uniformity of format and high quality of illustrations, which is a difficult task when dealing with what is, in effect, a conference volume. Although the quality of papers is patchy at times and refereeing could arguably have been stricter, the volume overall is of a very high standard, packed with much previously unpublished data. Despite these papers originally being presented over five years ago, the ideas and interpretations are still current. The book is completed by a full index of those taxa mentioned, in addition to a general index. Thus concludes a volume which already has a proved track record as an invaluable aid to calcareous nannofossil specialists, serving its time at the side of many a microscope.
N. Hine
British Geological Survey, Keyworth, Nottingham, UK
Tectonics and Seismic Sequence Stratigraphy Edited by G. D. Williams and A. Dobb Geological Society Special Publication No. 71 ; ISBN 0 903317 87 7; Price: US$75/£45 (Geological Society Members US$35/£21 ) The eight papers in this book form part of a larger set read at the Meeting of the Geological Society in 1991. Since the publication of the now classical A A P G M e m o i r 26 on seismic stratigraphy, seismic sequence stratigraphy has evolved into sequence stratigraphy (Van Wagoner et al., 1990) with background noise being amply provided by spirited debate on the merits or otherwise of the Vail (1977) and latterly Haq et al. sea level curves. In one sense, the book is a little outdated because the papers do not make the necessary link between wells and the seismic data - - the stratigraphy record after all reflects the sedimentary response to tectonism, sea level changes etc. Nevertheless, the papers are all usual contributions to the important topic of seismic sequence stratigraphy. A short introductory review by G. D. Williams on tectonics and seismic sequence stratigraphy sets the subject in context of the eight papers, of which six deal with seismic sequences in rift related basins and will be reviewed first. S. Prosser discusses rift linked depositional systems and their seismic expression. Her paper deals mainly with characterizing rift infill patterns using the concept of tectonic systems tract analysis. This approach can only be used in fault controlled basins. Waltham et al. in 'Sediment geometries and domino faulting' describe a forward modelling scheme to produce a model of sediment geometries in half grabens. In addition, the forward model is used to build synthetic seismic sections to better compare models with observations. Roberts et al. also discuss the 'domino' model using North Sea data in 'Tectonic and bathymetric controls on stratigraphic sequences within evolving half grabens'. Their model successfully models the synrift stratigraphy but they note the importance of well data and that there are too many unconstrained variables, i.e. tectonics versus sea level, to allow a unique interpretation. Joy analyses the 'pattern of post rift subsidence in the Central and Northern North Sea Basin'. The author notes accelerated Palaeocene subsidence in the North Sea and relates it to the opening of the North Atlantic Ocean.
Higgs and McClay present an elegant paper on analogue modelling of Miocene extensional faulting in the Outer Moray Firth. Their paper combines structural interpretation of seismic data with analogue model results. However, the faults do not penetrate below the top Palaeocene and the accommodation of the extension remains difficult to explain. In a more regional paper, Light et al. describe the seismic sequence stratigraphy and tectonics of the entire offshore Namibia passive margin. Although illustrated with full colour plates, none of the seismic sections given in the paper are located and there is little support for many of the seismic facies interpretations offered by the authors - - there were only three closely spaced wells along the 1200 km shelf. Of the two remaining papers, one deals with 'Thrust tectonics and sequence stratigraphy in foredeeps' using data from the Pyrenees. This is the only paper in the memoir that utilizes maximum flooding surfaces and sequence boundaries to decipher basin development - - in this case the evolution of syn-orogenic basins. This is an important and useful paper for the interpretation of seismic data in foredeep basins. Finally, the first paper in the memoir by Cartwright et al. discusses the 'Lateral extent of sequence boundaries'. The paper questions many of the axioms of seismic sequence stratigraphy and concludes that sequence boundaries are unlikely to develop as regionally discrete surfaces. However, sequence boundaries are well established as regional surfaces in a variety of basin settings. The memoir is a useful background read but the price of £45 is far too high for the content. At £21, it is marginal even for Geological Society members. The type of paperback memoirs produced by the A A P G and G S A might bring the cost down and make the memoir affordable and available to a wider readership.
D. G. Roberts
BP Exploration, Uxbridge, UK
Marine and Petroleum Geology, 1993, Vol 10, December
635
of observation (lithological symbols) from interpretation (environmental colours) has been well handled in a qualitative way, but there is no precise, quantitative information: one can only speculate as to the limit of outcrop or subcrop. Key sections and boreholes are not generally marked and referenced. There is no isopach information. Little has been done to characterize the bedrock geology or vegetation of areas of erosion. No palaeolatitude information has been included on the maps and there is no systematic attempt to address the wider issues of Britain's global palaeogeographic, climatic and oceanographic setting. In short, no answers will be found in this volume to so many questions which might be asked by the advanced student of British palaeogeography, and which might reasonably be addressed given the immense scope of British stratigraphic and sedimentological research. To be fair, the production of such a suite of maps would be a prodigious undertaking requiring commitment, one suspects, well beyond that which most of the authors of this volume felt able to contribute. In conclusion, as a definitive work on British stratigraphy the atlas is disappointing and does not justify its £295 price tag. It is, however, a very useful summary and, having acquired a copy, I am sure that I will refer to it frequently.
Neil Parkinson
Department of Earth Sciences, University of Oxford, UK
Nannofossils and Their Applications Edited by J. A. Crux and S. E. van Heck Ellis Horwood British Micropalaeontological Society Series; 1989; ISBN 0 7458 0237 0; 356 pp. Price: £69.50 Fourteen of the research papers scheduled for presentation at the International Nannofossil Association Conference in London in 1987 are brought together in this 356-page volume. Although these papers vary widely in subject matter, they are loosely bound under the sectional headings: morphology, systematics and evolution; palaeoenvironmental and palaeogeographical applications; and biostratigraphical applications. However, there is a great deal of overlap between them. The opening paper is by Young who, through his investigations into the ontogeny, structure and geometry of heterococcolith rims, deduced their structural complexity to be primarily a result of elaborate crystal unit structure rather than the production of numerous separate cycles of crystal units. These ideas are presented in this paper with particular reference to the Reticulofenestra and so complements the paper by Gallagher. He presents a critical review of the taxonomy and evolution of the Reticulofenestra and its phylogenetic relationships with other noelaerhabdaceans. Evolutionary changes in rim structure are given primary importance at generic level, whereas central-area architecture is considered to be a specific ranking feature. A formal emendation of the genus is made, followed by a comprehensive classification of 45 commonly referenced Reticulofenestra species. This is an admirable piece of work which suffers only from the absence of an equally comprehensive set of SEM and light microscope photographs. Aubry presents her ideas on the importance of understanding the taxonomic relationships between nannofossil groups for the interpretation of processes behind geological events, commenting on the vista between the palaeontological concept of coccolithophorales species and the biological concept. A case for the use of phylogenetically based taxonomy for deciphering evolutionary patterns is presented, citing the Cretaceous-Tertiary boundary event as an example. Moshkovitz and Osmond review the optical properties of crystals and their application to the study of the taxonomy,
634
evolution and diagenesis of calcareous nannofossils. Exemplified by the Arkhangelskiellaceae and other Late Cretaceous nannofossils, this paper is accompanied by a wonderful set of photographs. The final paper in this section, by Bown and Cooper, is a review of the classificaton, morphology and evolutionary relationships between a number of conical nannofossils from the Mesozoic. The phenomenon of homeomorphy is used to explain the existence of these apparently unrelated lineages. The second section (palaeoenvironmental and palaeogeographic applications of nannofossils) begins with a paper by Gard on the nannoftoras of the last glacial cycle. She interprets the variations in distribution and relative abundance of assemblages from the North Atlantic and Indian Oceans as reflecting changing surface water conditions. This is the only Quaternary paper, with the remaining four papers of this section being Early Cretaceous studies. Two papers are presented on the temperature-controlled migrations of calcareous nannofossils in north-west Europe; firstly Mutterlose in the Aptian, followed by Crux on the Ryazanian to Barremian. They each cite examples during which the nannofloras exhibited strong Tethyan or Boreal-Arctic provincialism which they correlate with transgressions, regressions and palaeogeographic changes in north-west Europe. These rapid changes in nannofossil assemblages have enabled Crux to divide the Ryazanian to Barremian interval into 16 nannofossil zones which he integrates with macrofossil zonations. Fourteen plates illustrate the key species that Crux mentions throughout this comprehensive paper. Applegate et al. present a comparison between Neocomian nannofossil assemblages of the Tethyan circum-North Atlantic province with those of the Boreal North Sea, revealing major assemblage differences despite their geographical proximity. This provincialism is attributed to the existence of a land barrier isolating the North Sea from the Tethys during Late Valanginian to Late Barremian times. The final paper in this section by Cooper provides a global view of nannofossil
Marine and Petroleum Geology, 1993, Vol 10, December
Book reviews provincialism in the Kimmeridgian to Valanginian. He uses the quantitative analysis of nannofossil assemblages, grouped at family level, as a method with which to differentiate the Boreal and Tethyan Realms. The final section deals with the biostratigraphic applications of calcareous nannofossils. Flores and Sierro present a paper on the Tortonian-Messinian boundary interval of the north-east Atlantic, Spain and Morocco. They successfully test a succession of calcareous nannofossil and planktonic foraminiferal events previously established in the Guadalquivir basin (Spain). They report a trend towards the cooling of surface waters throughout this interval, punctuated by intermittent warm water pulses of varying intensity. The rapid evolutionary rates during the Palaeocene enable Varol to define two highly detailed Palaeocene calcareous nannofossil stratigraphies: one with global (low to mid latitude) application, the other specifically for the North Sea area. The key taxa are well illustrated in five plates. The Palaeogene theme continues with a paper by Toker in which a standard calcareous nannofossil zonation scheme for the Turkish Palaeocene-Eocene is presented. Eighteen zones are recognized (all previously published) attributing the absence of some zonal marker species to palaeoecological factors. The zones are correlated with planktonic foraminiferal zones to achieve greater stratigraphic resolution. The final paper by Girgis presents the results of a morphometric
analysis of the Arkhangelskiella group from Egyptian sequences of Maastrichtian-Danain age. Four distinct nannofossil units are identified which are stratigraphically useful, especially in the absence of conventional marker species. Palaeoenvironmental aspects are also considered, relating the reduction in size just before the K/T boundary to the onset of stressful environmental conditions. The editors have succeeded in controlling the uniformity of format and high quality of illustrations, which is a difficult task when dealing with what is, in effect, a conference volume. Although the quality of papers is patchy at times and refereeing could arguably have been stricter, the volume overall is of a very high standard, packed with much previously unpublished data. Despite these papers originally being presented over five years ago, the ideas and interpretations are still current. The book is completed by a full index of those taxa mentioned, in addition to a general index. Thus concludes a volume which already has a proved track record as an invaluable aid to calcareous nannofossil specialists, serving its time at the side of many a microscope.
N. Hine
British Geological Survey, Keyworth, Nottingham, UK
Tectonics and Seismic Sequence Stratigraphy Edited by G. D. Williams and A. Dobb Geological Society Special Publication No. 71 ; ISBN 0 903317 87 7; Price: US$75/£45 (Geological Society Members US$35/£21 ) The eight papers in this book form part of a larger set read at the Meeting of the Geological Society in 1991. Since the publication of the now classical A A P G M e m o i r 26 on seismic stratigraphy, seismic sequence stratigraphy has evolved into sequence stratigraphy (Van Wagoner et al., 1990) with background noise being amply provided by spirited debate on the merits or otherwise of the Vail (1977) and latterly Haq et al. sea level curves. In one sense, the book is a little outdated because the papers do not make the necessary link between wells and the seismic data - - the stratigraphy record after all reflects the sedimentary response to tectonism, sea level changes etc. Nevertheless, the papers are all usual contributions to the important topic of seismic sequence stratigraphy. A short introductory review by G. D. Williams on tectonics and seismic sequence stratigraphy sets the subject in context of the eight papers, of which six deal with seismic sequences in rift related basins and will be reviewed first. S. Prosser discusses rift linked depositional systems and their seismic expression. Her paper deals mainly with characterizing rift infill patterns using the concept of tectonic systems tract analysis. This approach can only be used in fault controlled basins. Waltham et al. in 'Sediment geometries and domino faulting' describe a forward modelling scheme to produce a model of sediment geometries in half grabens. In addition, the forward model is used to build synthetic seismic sections to better compare models with observations. Roberts et al. also discuss the 'domino' model using North Sea data in 'Tectonic and bathymetric controls on stratigraphic sequences within evolving half grabens'. Their model successfully models the synrift stratigraphy but they note the importance of well data and that there are too many unconstrained variables, i.e. tectonics versus sea level, to allow a unique interpretation. Joy analyses the 'pattern of post rift subsidence in the Central and Northern North Sea Basin'. The author notes accelerated Palaeocene subsidence in the North Sea and relates it to the opening of the North Atlantic Ocean.
Higgs and McClay present an elegant paper on analogue modelling of Miocene extensional faulting in the Outer Moray Firth. Their paper combines structural interpretation of seismic data with analogue model results. However, the faults do not penetrate below the top Palaeocene and the accommodation of the extension remains difficult to explain. In a more regional paper, Light et al. describe the seismic sequence stratigraphy and tectonics of the entire offshore Namibia passive margin. Although illustrated with full colour plates, none of the seismic sections given in the paper are located and there is little support for many of the seismic facies interpretations offered by the authors - - there were only three closely spaced wells along the 1200 km shelf. Of the two remaining papers, one deals with 'Thrust tectonics and sequence stratigraphy in foredeeps' using data from the Pyrenees. This is the only paper in the memoir that utilizes maximum flooding surfaces and sequence boundaries to decipher basin development - - in this case the evolution of syn-orogenic basins. This is an important and useful paper for the interpretation of seismic data in foredeep basins. Finally, the first paper in the memoir by Cartwright et al. discusses the 'Lateral extent of sequence boundaries'. The paper questions many of the axioms of seismic sequence stratigraphy and concludes that sequence boundaries are unlikely to develop as regionally discrete surfaces. However, sequence boundaries are well established as regional surfaces in a variety of basin settings. The memoir is a useful background read but the price of £45 is far too high for the content. At £21, it is marginal even for Geological Society members. The type of paperback memoirs produced by the A A P G and G S A might bring the cost down and make the memoir affordable and available to a wider readership.
D. G. Roberts
BP Exploration, Uxbridge, UK
Marine and Petroleum Geology, 1993, Vol 10, December
635