Sequence (geology)

Abstract: 1. Introduction 2. Methods of Sequence Stratigraphic Analysis 3. Accommodation and Shoreline Shifts 4. Stratigraphic Surfaces 5. Systems Tracts 6. Sequence Models 7. Time Attributes of Stratigraphic Surfaces 8. Hierarchy of Sequences and Sequence Boundaries 9. Discussion and Conclusions REFERENCES AUTHOR INDEX SUBJECT INDEX

Abstract: Under the auspices of the "Mesozoic-Cenozoic Sequence Stratigraphy of European Basins" project (MCSSEB) an attempt was' made to construct a state-of-the-art biochronostratigraphic record of depositional sequences in European basins for the Mesozoic and Cenozoic. A wellcalibrated regional biochronostratigraphic framework is seen as an essential step towards an eventual demonstration of synchroneity of sequences in basins with different tectonic histories. The Mesozoic sequence stratigraphic and biostratigraphic records for the project (MCSSEB) are calibrated to the Gradstein et al. (1994) temporal scale. The Cenozoic record is calibrated to the Berggren et al. (1995) scale. The primary calibration in the Mesozoic between temporal and standard stratigraphy is based on ammonite biostratigraphy. This calibration was facilitated by h integration of the composite ammonite zonation of the "Sequence Stratigraphy of European Basins" project with the standard stratigraphy, magnetostratigraphy and radiometric data for the Triassic through lower Cretaceous intervals in the Gradstein et al. (1994) time scales. The Triassic through lower Cretaceous composite ammonite zonation in Gradstein et al. (1994) includes the highest resolution, zonal or subzonal, ammonite subdivisions available from tethyan as well as boreal areas in Europe. For the upper Cretaceous, Gradstein et al. (1994) calibrated their temporal scale with the Cobban et al. (1994) ammonite record from the Western Interior Basin in the United States, which is well correlated with 40Ar/39Ar dates from bentonites incorporated in the Obradovich (1993) and Gradstein et al. (1994) time scales. Calibration of the upper Cretaceous Western Interior Basin ammonite record with the European succession is relatively well understood for the Cenomanian through Santonian Stages but largely unresolved for the Campanian and Maastrichtian Stages. An incomplete ammonite record in the type areas in Europe and the lack of calibration between zonations of "cosmopolitan" fossil groups such as planktonic foraminifera, calcareous nannofossils and endemic ammonites in North America as well as Europe prevent adequate correlation. Calibration in the Cenozoic between temporal and standard stratigraphy is based on an integrated framework of magnetostratigraphy, planktonic foraminifera and calcareous nannofossils and selected radiometric ages. Subsequent calibration of sequences, strontium isotope ratios (87Sr/86Sr), oxygen isotope events, and additional fossil groups from oceanic, near shore and non-marine environments, was carried out by a large number of coordinators and contributors. INTRODUCTION was reviewed at workshops in Paris in May and December 1991 ~h~ chronostratigraphic charts presented in this paper are the and a preliminary biochronostratigraphic framework calibrated result of an initiative by Peter Vail and Thieny Jacquin in 1990 to the Haq et al. (1987) time scale was resented at the ~ i j o n to analyze and document depositional sequences in E~~~~~~~ Conference in 1992. After completion of the Gradstein et al. basins and to record their stratigraphic position relative to a (1994) Mesozoic time scale and the ~ e r ~ ~ r e n et al. (1995) Cestate-of-the-art temporal framework accurately calibrated to a ~ O Z O ~ C time scale, all biostratigraphic, isotope stratigraphic and biostratigraphic framework. ~h~ ~ ~ M e s o z o ~ c ~ e n o z o ~ c sesequence stratigraphic entries were recalibrated to the new time quence Stratigraphy of European Basins" project started officially with a meeting in ~ i j o n France organized by Jacquin, de Gracianskv, and Vail. in Mav 1992. Secluence interpretations SEISMIC STRATIGRAPHYISEQUENCE STRATIGRAPHY for a large number of European basins were presented at poster Mitchum et al. (1977) described the depositional sequence sessions in Dijon. Papers in this volume, many of them based as a basic unit for stratigraphic analysis with chronostration the Dijon posters, form an integral part of the sequence documentation for the chronostratigraphic charts. Work on the detailed chronostratigraphic charts for the Mesozoic and Cenozoic began eighteen months before the Dijon Meeting, in December 1990 in Paris with a planning meeting attended by a large number of specialists in a wide range of biostratigraphic disciplines from several European countries. At the Paris meeting, all specialists present were invited to participate in the calibration of fossil groups representing non-marine, shallowand deep-water depositional environments to a revised temporal framework. Invitations were extended to specialists not present at the Paris meeting to complement the expertise in fossil groups essential to the construction of a stratigraphic framework and to the calibration of sequences. Progress graphic significance. They defined the depositional sequence as follows: "A depositional sequence is a stratigraphic unit composed of a relatively conformable succession of genetically related strata and bounded at its top and base by unconformities or their correlative conformities." This definition adds the concept of the "correlative conformity" to the unconformitybounded sequence in the sense of Sloss (1963). Adding the "correlative conformity" to the sequence definition is essential to allow application of sequence stratigraphy in areas of continuous deposition. Even though Mitchum et al. (1977) discussed the chronostratigraphic significance of their sequence, they defined the sequence as a lithologic unit ("A depositional sequence is determined by a single objective criterion, the physical relations of the strata themselves)." They stopped, s Mesozoic and Cenozoic Sequence Stratigraphy of European Basins, SEPM Special Publication N.o. 60 Copyright

Abstract: Siliciclastic Sequence Stratigraphy-Concepts and Applications - Sequence stratigraphy has experienced a virtual explosion of applications in recent years. During that time, the concepts upon which sequence stratigraphy is based have been evolving to conform to new observations as well as new types of data. This volume summarizes the current status of this discipline as it applies to siliciclastic deposits. The emphasis in this volume is on sequence stratigraphy as an ?approach? to geological analysis, rather than as a model to which all data sets must conform. The expression of sequence architecture and the nature of bounding surfaces is illustrated through examples and applications drawn from a range of data types, including outcrop, core, wireline log, and 3-D seismic data. In addition, sequence expression also is illustrated using examples of modern landforms.