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Sed-Century
Sed~menta,ry Geology ELSEVIER
Sedimentary Geology 100 (1995) 1-3
Sed-Century To achieve one hundred volumes, through an age when journal titles have proliferated exponentially, underlines the fact that this journal has been providing a significant scientific service to the sedimentological community. The first part of Volume 1 was published in 1967 as a sister journal to Sedimentology, serving as an international outlet for papers in regional and applied sedimentology. This has remained its essential role through 100 volumes. The papers for Volume 1 were selected by an Editorial Board, which included Keith Crook (one of the current Editorsin-Chief) as one of its members. The first paper was by Ida Valeton, on bauxite-bearing laterites in India. Also in Volume 1 were papers on the petrology of Recent sands, several papers on deltaic facies (then all the rage), and significant contributions on temperate water carbonates (by Conolly and Von der Borch) and Cretaceous tidal deposits (by D.J.P. Swift and D. Heron). With the publication of Volume 2 came the appointment of J.D. de Jong (Leiden, and subsequently Wageningen) as the sole Editor-in-Chief, a post which he retained until his retirement in 1987 (Volume 55). The current Editors-in-Chief assumed their responsibilities with the publication of Volume 54 (1987), overseeing the change to the larger (present) format which accompanied the publication of Volume 56, a Special Issue on Late Paleozoic and Mesozoic eolian deposits in the Western Interior of the USA (edited by Gary Kocurek). Another milestone (in addition to a growing number of very significant Special Issues) was the publication of Volume 50 (1987), with invited contributions coming from John Allen, Harry Elsevier Science B.V. SSDI 0 0 3 7 - 0 7 3 8 ( 9 5 ) 0 0 0 9 9 - 2
Roberts, Gerry Friedman, George de Vries Klein, Franco Ricci Lucchi, Ken Glennie, van Loon and Brodzikowski, and Lynton Land, Kitty Milliken and Earle McBride. Volume 100 incorporates some invited contributions and some papers selected from the normal range of submitted papers, which thus illustrates the scope and strength of papers we now receive. In its infancy the journal too often seemed to become the repository of papers that had been excluded from other journals, and its reputation suffered in consequence. Our policy, since 1987, has been to continue to provide a broadly based journal in the sedimentary field, and one giving the opportunity for papers of a regional (not local) character, as well as those concerned with exploring the general principles of sedimentology and its frontier areas. We also initiated ExpresSed as a rapid publication outlet for short, topical and original contributions. Excellent contributions on 'hot topics' are generally accepted within one month of submission and published in about six months. As editors of Sedimentary Geology we are proud to have stimulated the birth of the bi-monthly newspaper SEDabstracts which aims to promote visibility and awareness of research in softrock geology. To the continuation of the ends stated above Volume 100 stands witness, like a sedimentological 'mask of Janus', but looking mostly forward with just a backwards glance. In the first paper in this volume Andrew Miall considers future trends in stratigraphy. With his article Whither stratigraphy he traces the course of sedimentological thinking through its three major revolutions: the development of process-re-
2
Sed-Centut3'
sponse models, the application of plate-tectonic concepts to basin analysis, and subsequent development of sequence stratigraphy, the latter drawing together the main results of the first two. He goes on to consider current developments in the field, such as the formulation of sequence architecture models, the mechanisms of sequence generation, and the refinement of time-scale and the precision of stratigraphic correlation (application of mathematical modelling, concepts derived from Milankovitch theory and the birth of cyclostratigraphy). John Allen, using the Severn Estuary of Southern England as an experimental system (as he did with his 'preliminary study' in Volume 50) but now employing a zero-dimensional numerical model, addresses the problem of evaluating the mechanics of an actual sea-level rise, namely that of the Flandrian. Decimetre relative fluctuations of sea level, in the model, create stratigraphic sequences similar to those observed in the Severn system. He considers the possibility that similar small-scale fluctuations, on a time scale of hundreds of years, may have been superimposed on the overall Flandrian rise. Lag effects in facies responses are also considered, particularly involving marsh sediments and these effects, and other factors, are shown to lead to potentially large errors in sea-level curves based on radio-carbondated peats. Tom Aigner and colleagues from Tiibingen approach the problem of analysing sedimentary architecture at outcrop through gamma-ray logging. These techniques are used in three different systems, all of which are Triassic in age. They are: (1) shoaling-upwards cycles in Upper Muschelkalk carbonates; (2) evaporite to redbed cycles in the Gipskeuper; and (3) fluvial architecture in the Stubensandstein. They show how this approach is helpful in calibrating subsurface information, and in providing quantitative heterogeneity data important in reservoir and aquifer modelling. Peter Bruckschen and others (including Jan Veizer), from Bochum, have been able to characterise the SVSr/86Sr ratio in Early Carboniferous (Dinantian) sea water, which is defined by a declining trend, and they recognise fourth-order fluctuations superimposed on this trend with an
estimated Ma range. The recognised oscillations appear to have a higher frequency in the late Dinantian than in preceding intervals, in concert with a greater degree of sedimentary cyclicity generally recognised in the Visean, as compared to the Tournaisian. They evaluate the potential of the Sr isotopic curve as being an excellent geochronological and chronostratigraphic tool, particularly for the Hastarian to lower Chadian interval. T h e p a p e r by A1-Aasm, Coniglio and Desrochers (from Windsor, Waterloo and Ottawa, Ontario) considers the formation of complex calcite veins in the Upper Triassic of Western Canada. Through detailed petrography, coupled with geochemistry (e.g. 6~3C and 6~80 measurements) they show that these calcites most probably relate to hydrothermal discharge associated with the effects of early Mesozoic plutonism. Their study demonstrates the potential significance of hydrothermal input during the evolution of pore waters within particular basins. Clari, Dela Pierre and Martire (Torino, Italy) present a classification of discontinuities within carbonate successions. This paper, which focuses on the classic Jurassic to Tertiary successions of the southern Alps and central Apennines, defines the variety of discontinuity surfaces (DS) within platform to pelagic successions and discusses both their significance and potential in sequence stratigraphic interpretation. Based upon a detailed study of the Cenozoic limestones of New Zealand, Shaun Hayton, Campbell Nelson and Steven Hood (Waikato, New Zealand) have refined Alan Lees' well known term foramol and provide a classification scheme for non-tropical carbonates, on the basis of skeletal composition. In future years, the seven assemblages that they define (barnamol, bimol, brymol, echinofor, nannofor, rhodalgal and rhodechfor) are likely to become as well known, to workers on temperate-water carbonates, as Lees' terms foramol and chlorozoan. The paper by Paul Wright and associates from Reading, Schlumberger and the University of the West of England, presents a classification of root-formed calcretes, citing case studies from the Mesozoic of Spain and France. They describe
Sed-Century
calcretes in which plants have controlled calcrete development, having formed largely through the action of plant root calcification. They provide examples of calcretes that resulted from the accumulation of calcified root cells (Microcodium) and show how chronosequences may be identified in root-related calcretes. Greg Price, Paul Valdes and Bruce Sellwood (Reading) evaluate, sedimentologically, the performance of atmospheric general circulation models (GCMs) as a means of providing insights into the climatic behaviour of the Mesozoic earth, a time of possible 'greenhouse' conditions. The strengths and weaknesses of these models are discussed, as well as their ability to predict economically significant resources such as petroleum source-rocks and phosphorites. The future use of GCMs in the forward modelling of sequence stratigraphic evolution and in predicting the diagenetic characteristics of reservoir units in frontier exploration areas is also considered. It is emphasised that the sedimentary record provides the only way in which GCMs may themselves be evaluated, and this is important because these same GCMs are being used to predict future climate change. The final papers comprise a delightfully elegant discussion, by Doug Shearman (Imperial College, London), of an eloquent paper by Calvo and colleagues (Madrid) on the origin of gypsum deposits in the Miocene of Spain. In a nutshell,
3
these deposits were initially described in an earlier volume (Rodrigues-Aranda et al., 1995, in Sedimentary Geology, 95, pp. 123-132), the authors describing the contained gypsum in some petrographic detail. Shearman, from their detailed petrography and fifty years of experience, speculates on whether the entire sequence is inverted or whether the gypsum crystals grew in a pendant manner, downwards, from the surface of the original brine pools. Calvo (one of the original authors) and colleagues, vigorously defend their original proposal, reiterating that this is a new growth form for the mineral. Such are the splendid controversies that should continue to grace the pages of this journal. The range of papers presented here, then, helps to underline the main principle which Keith Crook, Andrew Miall and myself enunciated on becoming Editors-in-Chief of Sedimentary Geology. Firstly that the quality of the work published should be of a very high international standard and secondly that the scope of the journal should be immensely broad ('unlimited'). We shall continue to operate with these same principles towards Volume 200 and we invite you to submit to us the fruits of your very best work. KE1TH CROOK ANDREW MIALL BRUCE W. SELLWOOD (Editors-in-Chief)
Sedimentary Geology 100 (1995) 1-3
Sed-Century To achieve one hundred volumes, through an age when journal titles have proliferated exponentially, underlines the fact that this journal has been providing a significant scientific service to the sedimentological community. The first part of Volume 1 was published in 1967 as a sister journal to Sedimentology, serving as an international outlet for papers in regional and applied sedimentology. This has remained its essential role through 100 volumes. The papers for Volume 1 were selected by an Editorial Board, which included Keith Crook (one of the current Editorsin-Chief) as one of its members. The first paper was by Ida Valeton, on bauxite-bearing laterites in India. Also in Volume 1 were papers on the petrology of Recent sands, several papers on deltaic facies (then all the rage), and significant contributions on temperate water carbonates (by Conolly and Von der Borch) and Cretaceous tidal deposits (by D.J.P. Swift and D. Heron). With the publication of Volume 2 came the appointment of J.D. de Jong (Leiden, and subsequently Wageningen) as the sole Editor-in-Chief, a post which he retained until his retirement in 1987 (Volume 55). The current Editors-in-Chief assumed their responsibilities with the publication of Volume 54 (1987), overseeing the change to the larger (present) format which accompanied the publication of Volume 56, a Special Issue on Late Paleozoic and Mesozoic eolian deposits in the Western Interior of the USA (edited by Gary Kocurek). Another milestone (in addition to a growing number of very significant Special Issues) was the publication of Volume 50 (1987), with invited contributions coming from John Allen, Harry Elsevier Science B.V. SSDI 0 0 3 7 - 0 7 3 8 ( 9 5 ) 0 0 0 9 9 - 2
Roberts, Gerry Friedman, George de Vries Klein, Franco Ricci Lucchi, Ken Glennie, van Loon and Brodzikowski, and Lynton Land, Kitty Milliken and Earle McBride. Volume 100 incorporates some invited contributions and some papers selected from the normal range of submitted papers, which thus illustrates the scope and strength of papers we now receive. In its infancy the journal too often seemed to become the repository of papers that had been excluded from other journals, and its reputation suffered in consequence. Our policy, since 1987, has been to continue to provide a broadly based journal in the sedimentary field, and one giving the opportunity for papers of a regional (not local) character, as well as those concerned with exploring the general principles of sedimentology and its frontier areas. We also initiated ExpresSed as a rapid publication outlet for short, topical and original contributions. Excellent contributions on 'hot topics' are generally accepted within one month of submission and published in about six months. As editors of Sedimentary Geology we are proud to have stimulated the birth of the bi-monthly newspaper SEDabstracts which aims to promote visibility and awareness of research in softrock geology. To the continuation of the ends stated above Volume 100 stands witness, like a sedimentological 'mask of Janus', but looking mostly forward with just a backwards glance. In the first paper in this volume Andrew Miall considers future trends in stratigraphy. With his article Whither stratigraphy he traces the course of sedimentological thinking through its three major revolutions: the development of process-re-
2
Sed-Centut3'
sponse models, the application of plate-tectonic concepts to basin analysis, and subsequent development of sequence stratigraphy, the latter drawing together the main results of the first two. He goes on to consider current developments in the field, such as the formulation of sequence architecture models, the mechanisms of sequence generation, and the refinement of time-scale and the precision of stratigraphic correlation (application of mathematical modelling, concepts derived from Milankovitch theory and the birth of cyclostratigraphy). John Allen, using the Severn Estuary of Southern England as an experimental system (as he did with his 'preliminary study' in Volume 50) but now employing a zero-dimensional numerical model, addresses the problem of evaluating the mechanics of an actual sea-level rise, namely that of the Flandrian. Decimetre relative fluctuations of sea level, in the model, create stratigraphic sequences similar to those observed in the Severn system. He considers the possibility that similar small-scale fluctuations, on a time scale of hundreds of years, may have been superimposed on the overall Flandrian rise. Lag effects in facies responses are also considered, particularly involving marsh sediments and these effects, and other factors, are shown to lead to potentially large errors in sea-level curves based on radio-carbondated peats. Tom Aigner and colleagues from Tiibingen approach the problem of analysing sedimentary architecture at outcrop through gamma-ray logging. These techniques are used in three different systems, all of which are Triassic in age. They are: (1) shoaling-upwards cycles in Upper Muschelkalk carbonates; (2) evaporite to redbed cycles in the Gipskeuper; and (3) fluvial architecture in the Stubensandstein. They show how this approach is helpful in calibrating subsurface information, and in providing quantitative heterogeneity data important in reservoir and aquifer modelling. Peter Bruckschen and others (including Jan Veizer), from Bochum, have been able to characterise the SVSr/86Sr ratio in Early Carboniferous (Dinantian) sea water, which is defined by a declining trend, and they recognise fourth-order fluctuations superimposed on this trend with an
estimated Ma range. The recognised oscillations appear to have a higher frequency in the late Dinantian than in preceding intervals, in concert with a greater degree of sedimentary cyclicity generally recognised in the Visean, as compared to the Tournaisian. They evaluate the potential of the Sr isotopic curve as being an excellent geochronological and chronostratigraphic tool, particularly for the Hastarian to lower Chadian interval. T h e p a p e r by A1-Aasm, Coniglio and Desrochers (from Windsor, Waterloo and Ottawa, Ontario) considers the formation of complex calcite veins in the Upper Triassic of Western Canada. Through detailed petrography, coupled with geochemistry (e.g. 6~3C and 6~80 measurements) they show that these calcites most probably relate to hydrothermal discharge associated with the effects of early Mesozoic plutonism. Their study demonstrates the potential significance of hydrothermal input during the evolution of pore waters within particular basins. Clari, Dela Pierre and Martire (Torino, Italy) present a classification of discontinuities within carbonate successions. This paper, which focuses on the classic Jurassic to Tertiary successions of the southern Alps and central Apennines, defines the variety of discontinuity surfaces (DS) within platform to pelagic successions and discusses both their significance and potential in sequence stratigraphic interpretation. Based upon a detailed study of the Cenozoic limestones of New Zealand, Shaun Hayton, Campbell Nelson and Steven Hood (Waikato, New Zealand) have refined Alan Lees' well known term foramol and provide a classification scheme for non-tropical carbonates, on the basis of skeletal composition. In future years, the seven assemblages that they define (barnamol, bimol, brymol, echinofor, nannofor, rhodalgal and rhodechfor) are likely to become as well known, to workers on temperate-water carbonates, as Lees' terms foramol and chlorozoan. The paper by Paul Wright and associates from Reading, Schlumberger and the University of the West of England, presents a classification of root-formed calcretes, citing case studies from the Mesozoic of Spain and France. They describe
Sed-Century
calcretes in which plants have controlled calcrete development, having formed largely through the action of plant root calcification. They provide examples of calcretes that resulted from the accumulation of calcified root cells (Microcodium) and show how chronosequences may be identified in root-related calcretes. Greg Price, Paul Valdes and Bruce Sellwood (Reading) evaluate, sedimentologically, the performance of atmospheric general circulation models (GCMs) as a means of providing insights into the climatic behaviour of the Mesozoic earth, a time of possible 'greenhouse' conditions. The strengths and weaknesses of these models are discussed, as well as their ability to predict economically significant resources such as petroleum source-rocks and phosphorites. The future use of GCMs in the forward modelling of sequence stratigraphic evolution and in predicting the diagenetic characteristics of reservoir units in frontier exploration areas is also considered. It is emphasised that the sedimentary record provides the only way in which GCMs may themselves be evaluated, and this is important because these same GCMs are being used to predict future climate change. The final papers comprise a delightfully elegant discussion, by Doug Shearman (Imperial College, London), of an eloquent paper by Calvo and colleagues (Madrid) on the origin of gypsum deposits in the Miocene of Spain. In a nutshell,
3
these deposits were initially described in an earlier volume (Rodrigues-Aranda et al., 1995, in Sedimentary Geology, 95, pp. 123-132), the authors describing the contained gypsum in some petrographic detail. Shearman, from their detailed petrography and fifty years of experience, speculates on whether the entire sequence is inverted or whether the gypsum crystals grew in a pendant manner, downwards, from the surface of the original brine pools. Calvo (one of the original authors) and colleagues, vigorously defend their original proposal, reiterating that this is a new growth form for the mineral. Such are the splendid controversies that should continue to grace the pages of this journal. The range of papers presented here, then, helps to underline the main principle which Keith Crook, Andrew Miall and myself enunciated on becoming Editors-in-Chief of Sedimentary Geology. Firstly that the quality of the work published should be of a very high international standard and secondly that the scope of the journal should be immensely broad ('unlimited'). We shall continue to operate with these same principles towards Volume 200 and we invite you to submit to us the fruits of your very best work. KE1TH CROOK ANDREW MIALL BRUCE W. SELLWOOD (Editors-in-Chief)