Abstract Concepts of seismic and sequence stratigraphy as outlined in publications since 1977 made a substantial impact on sedimentary geology. The notion that changes in relative sea level shape sediment in predictable packages across the planet was intuitively attractive to many sedimentologists and stratigraphers. The initial stratigraphic record of Mesozoic and Cenozoic depositional sequences, laid down in response to changes in relative sea level, published in Science in 1987 was greeted with great, albeit mixed, interest. The concept of sequence stratigraphy received much acclaim whereas the chronostratigraphic record of Mesozoic and Cenozoic sequences suffered from a perceived absence of biostratigraphic and outcrop documentation. The Mesozoic and Cenozoic Sequence Stratigraphy of European Basins project, which began officially with an international meeting in Dijon France in 1992, was designed to address the lack of documentation by inviting sedimentologists and stratigraphers to collectively build a documented chronostratigraphic and outcrop record of depositional sequences calibrated across a large number of basins in a geographically restricted area. The choice of Europe as a backdrop to this calibration and documentation effort is rooted in the philosophy that the cumulative stratigraphic data base for European Basins, which have been studied for over hundred years and are home to most Mesozoic and Cenozoic stage stratotypes, is uniquely suited for such a calibration project. European basins offer a variety of climatic provinces and their depositional systems range from siliciclastic systems in the northern part of the study area to carbonate dominated systems in the tethyan area. Sequence interpretations for a large number of European basins were presented at poster sessions in Dijon. Papers in this volume, many of them based on the Dijon posters, form an integral part of the sequence documentation presented here.

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 well-calibrated 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 the 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 40 Ar/ 39 Ar 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 ( 87 Sr/ 86 Sr), 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.

Abstract Four Mesozoic major transgressive/regressive cycles have been recognized within Western European basins. They are named as: (1) Eastern Tethys Cycle, (2) Ligurian Cycle, (3) North Sea Cycle, and (4) North Atlantic Cycle, following the four main phases of rifting that affected the whole Western European Craton and its borders during Mesozoic times. Such cycles are bounded by major unconformities, whose names from oldest to youngest are: Hardegsen or Solling (Scythian), Early Cimmerian (Late Norian), Mid-Cimmerian (Aalenian), Late Cimmerian (Berriasian) and Laramide (Palaeocene). Major transgressive/regressive cycles record outpaces the area of every individual basin, which suggests that local tectonic features were not the principal causes.

Abstract Transgressive/regressive facies cycle analysis combines the approaches of sequence stratigraphy at outcrop/core/well-log scales and seismic stratigraphy at seismic scales (large-scale stratal pattern and termination), to determine the facies stacking pattern and the partitioning of sediments following long-term changes in shelfal accommodation. Thus, it is an interdependent approach with the main purpose being to build a hierarchy of stratigraphic cycles. The building blocks of transgressive/regressive (T/R) facies cycles are 3rd-order depositional sequences. Four types of 3rd-order depositional sequences may develop within a 2nd-order transgressive/regressive facies cycle: infilling and forestepping during the regressive phase and aggrading and backstepping during the transgressive phase. These four types of sequences do not occur systematically together within a second-order cycle. Four end-members of T/R cycles can be defined depending on (1) the capability of sediment deposition to keep up with relative sea-level rises; (2) the rates at which accommodation space changes. The four end-members will include (1) T/R cycle with or without aggrading sequences and (2) T/R cycles with or without forestepping sequences. About 18 T/R cycles have been found within the Western European Mesozoic stratigraphic successions. At the craton scale, some of the characteristic surfaces and events are very synchronous. This synchroneity suggests a tectono-eustatic control. Cycles which are not synchronous within a basin usually result from variations in local sea-floor subsidence/uplift. This can be seen particularly in the syn-rift and syn-compressional successions. Both the type and occurrence of 3rd-order sequences (in respect to stratigraphy, depositional environments, reservoirs, source rocks and facies) depends of the type of 2nd-order cycle to which they belong. A full understanding of these characteristics observed in the data is essential to the analysis of the stratigraphic signature of a basin.

Abstract Four types of stratigraphic cycles with a time duration greater than 10,000 years are recognized in the sedimentary record. In order of decreasing time duration and scale they are: (i) continental encroachment cycles, (ii) regression-transgression cycles, (iii) sequence cycles and (iv) parasequence cycles. Continental encroachment cycles are defined on the basis of their onlapping against cratons and are bounded by the unconformities associated with the formation of supercontinents. They are reflected by long-term shoreline displacements induced by first-order eustasy. Continental encroachment cycles can be subdivided into subcycles which are defined using the same criteria at smaller scales. Regression-transgression cycles are defined on the basis of short-term shoreline displacements induced by second-order eustacy and are bounded by major downlap surfaces. Sequence cycles are defined on the basis of shelfal accommodation changes and are bounded by unconformities induced by relative sea-level falls associated with third-order eustasy. Sequence cycles are complete when all systems tracts are present. These complete sequence cycles occur in areas with high rates of sedimentation where all available shelfal space is filled. Incomplete sequence cycles do not have all the systems tracts and occur in areas with low rates of sedimentation where only part of the available shelfal space is filled. Parasequence cycles are intervals bounded by flooding surfaces or their correlative conformities. The recognition and understanding of the architecture of the continental encroachment cycles, subcycles and/or the regression-transgression cycles and the location of the major downlap surfaces are important steps in the study of petroleum systems. They allow explorationists to locate the most likely marine source rocks. On seismic data, continental encroachment cycle and subcycle interpretations are used, particularly in the proximal part of sedimentary basins, where the encroachment is relatively easy to recognize. As an alternative, in the intermediate parts of the basins, where the offlap-breaks are usually identifiable, regression-transgression cycle interpretations can also be used to locate potential marine source rocks. In this paper, applications of the continental encroachment cycle and subcycle concept in locating potential marine source rocks using seismic data are presented, together with comments on the stratigraphic distribution of major potential marine source rocks.

Abstract Sequence and biostratigraphic analysis of the margin of the Apulian carbonate platform in the Montagna della Maiella (central Italy) reveal a platform margin evolution that is controlled by long-term sea-level changes, tectonism and changing platform morphology. The Upper Cretaceous to Miocene strata can be subdivided into six supersequences that are separated by deeply incised truncation surfaces. Biostratigraphy documents a major hiatus for all but one of these boundaries. The supersequences reflect distinct stages of platform development, thus the depositional systems remained the same within each supersequence but changed across the supersequence boundaries. The Apulian platform grew on a passive margin of the Jurassic-Cretaceous (Neo-) Tethys. During the early platform history, subsidence rates decreased exponentially with time and controlled the long-term aggradation potential of the platform. The generally decreasing total subsidence rates permitted the basin in front of the platform to be filled up by the Late Campanian strata (Supersequence [SS] 1), resulting in a change from aggradation to progradation. This enabled slope carbonates of Late Campanian to Late Eocene age (SS 2 to 4 and lower part of SS 5) and finally shallow-water platform carbonates of Late Eocene to Late Miocene age (upper part of SS 5 to SS 6) to prograde basinwards. The supersequence boundaries are to a large extent controlled by long-term (2nd-order) eustatic sea-level changes, but climate and tectonism influenced their duration and expression. Climate, initially tropical to subtropical but temperate in Miocene time, and the respective evolution of flora and fauna were major controls on sequence architecture but did not significantly influence the formation of the supersequence boundaries. The tectonic movements related to Alpine orogeny and foreland basin development were not able to completely obliterate the long-term eustatic signal but greatly enhanced the boundaries, although the exact amount of this influence cannot be assessed. Platform morphology was very influential on sequence architecture. From at least Early Cretaceous to Late Campanian time, the presence of a steep escarpment resulted in detached sequences, consisting of an onlapping basinal part and an aggrading part on the platform top, separated by a bypass slope. In Late Campanian to Oligocene time, a distally steepened slope profile was deeply incised, most pronounced along the platform margin and the upper slope, during 2nd-order sea-level lowstands. Sea-level fluctuations along the gently inclined Miocene shelf resulted in deposition of deepening-upward sequences under conditions of low carbonate productivity.

ABSTRACT A Cretaceous (Aptian) to Cenozoic composite oxygen isotope curve is presented and correlated to eustatic records and to global tectonic events. The curve was built using deep water benthonic foraminifera from DSDP/ODP sites. In addition, well-dated outcrop and subsurface whole rock samples were used. This composite record provides insight about the evolution of deep-water temperatures and/or ice volume changes from the Aptian to the present. Two important observations can be made from the isotope record. First, three low-frequency isotope cycles are recognized, encompassing most of the Upper Cretaceous (named Uki), most of the Paleogene (named Pi) and most of the Neogene (named Ni) period. These low-frequency cycles correspond well with the sequence stratigraphic supercycle sets Upper Zuni A, Tejas B and Tejas A, respectively. Second, oxygen isotope values for deep-water benthonic foraminifera during the Aptian to lower Albian and Campanian to Maastrichtian are similar to those observed during middle Eocene. Due to the evidence for middle Eocene Antarctic glaciation, similarity between Cretaceous and Eocene isotope values could indicate the presence of polar ice as early as the Aptian.

Abstract Neogene deposits discussed in the six papers submitted for this volume are situated in the North Sea basin, Pannonian Basin, Piedmont Basin and the Central Mediterranean Basin (Sicily). Contributions for the North Sea Basin discuss the Paleogene and Neogene deposits of the eastern subsurface offshore Denmark and its southern rim in Belgium. Studies of the Pannonian Basin (Hungary) and Piedmont Basin (Italy) address Oligocene through middle Miocene deposits. Two papers on the Central Mediterranean Basin in Sicily describe the Plio-Pleistocene record. Neogene Alpine compressive tectonics led to a general uplift of Europe except for the present offshore North Sea basin. Neogene deposits in northwestern Europe are generally thin, stratigraphically incomplete and often marginal to non-marine. In the Alpine/Carpathian realm, localized tectonic events formed isolated basins such as the Piedmont and Pannonian Basins. The Mediterranean area was undergoing major tectonic rearrangements in the Neogene. Stratigraphic calibration of proposed sequence records to the integrated Berggren et al. (1995) time scale could only be achieved with confidence for lower to middle Miocene and Plio-Pleistocene deposits laid down under open-marine conditions in mid latitude settings in the Pannonian, Piedmont and Mediterranean Basins. The incomplete record for the upper Miocene could not be reliably calibrated to the Berggren et al. (1995) time scale and the Haq et al. (1987) record for the upper Miocene is retained on the Cenozoic chronostratigraphic chart.

Abstract The stratigraphic position of sequences on the new Cenozoic chronostratigraphic chart is based on information from papers submitted for publication in this volume. Much of this data was presented at poster sessions of the Sequence Stratigraphy of European Basins Meeting in Dijon, France in 1992. Of the eleven papers addressing Cenozoic sequence stratigraphy in this volume, four papers include sequence information for both Neogene and Paleogene, three papers address sequence stratigraphy in the Neogene and four papers deal with the Paleogene. Paleogene sedimentary basins described in the papers submitted for this volume occur in compressional, extensional, and passive margin settings and are filled with sediments deposited in paleoenvironments that varied from non-marine to bathyal depths. Despite the variability, deposits of this age can be widely correlated due to an integrated biochronostratigraphic calibration that encompasses every type of available stratigraphic marker. In general, studies on Paleogene sequence stratigraphy fall into two major geographical areas: the greater North Sea basin, and the greater Mediterranean basin. Much of the detail in the new European Basins Cycle Chart comes from the greater North Sea basin. This province has been intensely studied for biostratigraphy, lithostratigraphy and sequence stratigraphy for much of the last 25 years. The International Geologic Correlation Program (IGCP) #124 (Vinken et al., 1988) gathered stratigraphic information from many different sources to erect a stratigraphic calibration that contributed to the present studies. Subsequent work has refined that framework even more and now combines physical (sequence) stratigraphy with the more traditional biostratigraphic and lithostratigraphic approach. The publication of "A Revised Cenozoic Geochronology and Chronostratigraphy" (Berggren et al., 1995) provided a state of the art temporal framework.

Abstract The Cenozoic evolution of the epicontinental North Sea Basin is described on the basis of sequence stratigraphy, comprising analyses of seismic sections, petrophysical logs and biostratigraphic studies of foraminifera, dinoflagellates and calcareous nannofossils. Stratigraphic, palaeogeographic and palaeoecological information from the Danish onshore area is integrated in the study. The deposits are subdivided into 21 sequences, which group into seven informal major units. The sequence boundaries are identified by differences in seismic facies and by seismic onlap, toplap and truncation features. The maximum flooding surfaces are placed at internal downlap surfaces which correlate with high values on the gamma-ray logs. The source of sediments and the direction of sediment transport changed several times during Cenozoic deposition. Transport was mainly from the north during the Late Paleocene and Early Eocene, from the west during the Middle and Late Eocene and from the north and northeast during the Oligocene to Quaternary times. The depocenters of the seven major units are generally located marginally, apparently adjoining the source areas. There is only minor evidence for changes in subsidence rates in the basin. A constant rate is assumed from Paleocene to mid Middle Miocene time. For the remaining part of the Cenozoic time an increased rate is indicated. A tentative relative sea-level curve for the North Sea Basin is proposed. The overall trends of the curve are broadly comparable with the global sea-level curve of Haq et al. (1988). Discrepancies may be caused by differences in the biostratigraphic calibrations. The most pronounced Oligocene sea-level fall is dated as latest Oligocene.

Abstract The Tertiary deposits in Belgium are marine shelf to coastal deposits formed in the southern part of the North Sea Basin. Lithologically they vary from calcareous deposits at the beginning of the Paleogene, almost indistinguishable from the underlying Maastrichtian chalks, to marls, clays and sands towards the top. In northern Belgium, these deposits reach thicknesses of several hundreds of meters. Stratigraphically they cover almost the whole Tertiary, albeit with many important hiatal intervals. The stratigraphy in the region was established quite firmly from outcrops, already in the former century. International stage names such as Ypresian and Rupelian are derived from well studied outcrop areas in this region, and several more regionally used stage names were defined in Belgium such as Montian, Landenian, Bruxellian, Ledian, Wemmelian and Tongrian. As these chronostratigraphic names have become obsolete, the names of their type localities are now reserved for lithostratigraphic units: groups, formations and members (Maréchal, 1991). In fact this is even more appropriate as these stratigraphic units were originally individualized on the basis of lithological characteristics and much less on grounds of stratigraphically significant fossils.

ABSTRACT Large-scale correlations and sequence stratigraphic analyses have been carried out in the central Mediterranean region, a tectonically active area crossing the extensional margin of the southern Tyrrhenian, the compressional front of the Siculo-Maghrebian Tertiary chain and the North African foreland. The Plio-Pleistocene marine record has been subdivided in sequences and systems tracts on the basis of both original data and correlations. We provide seismic, well-log and outcrop data supporting the occurrence of regional unconformities of constant age, related to glacio-eustatic oscillations. Evidence of transgressive-regressive facies cycles having different orders of duration, major erosional truncations and basin starvation events contributed to the construction of a new sea-level cycle chart based on the available Mediterranean high-resolution biochronology and magnetostratigraphy. We largely used the deep-sea correlative conformities of sequence boundaries in order to improve the age calibration of the cycle chart. The chart, based on a new Plio-Pleistocene time scale, can resolve boundary ages up to 5th-order paracycles based on correlations to the high-frequency oscillations of the deep-sea record. Outcrop evidence of correlations between individual parasequences and 41 ky astronomical and climatic oscillations of the deep-sea record is supported by high-resolution biochronology. A comparison with the Mediterranean Plio-Pleistocene sequence chart confirms the general validity of the Gulf of Mexico cycle chart of Wornardt and Vail (1991), except for minor differences in age and number of 4th-order sequences. The sequence stratigraphic subdivisions are recognizable even in active sectors where stratal analysis separates the eustatic from the tectonic component; from this perspective, our experience support the regional synchroneity of sequences and systems tracts occurring in the studied interval independently of local tectonic factors.

Abstract Syn-sedimentary deformation occurred during late Neogene time in the foreland and piggyback basins of Sicily, located between the South-Tyrrhenian belt and the North Africa foreland. The geometric relationships of the Plio-Pleistocene syntectonic strata (5.3–0.5 Ma) with structures like thrust-related folds are spectacularly preserved, together with the modifications in the stacking pattern of the parasequences. In some expanded successions, it is evident that significant pulses in the synsedimentary growth of structures occur on the time scale of Milankovitch cycles, producing stratal geometries that may become unpredictable by current models. Due to tectonic compressive stresses, the tectonic subsidence (or uplift) rate may exceeds the eustatic rate, generating stratal expansions or local unconformity surfaces, formed at the scale of systems tracts of the 4 th order depositional cycles. High-resolution biochronostratigraphy and sequence stratigraphic interpretations allow precise evaluations of the vertical absolute growth and growth rates relative to very short time intervals. In the Caltanissetta area, central Sicily, structures having the amplitude of tens of meters are generated within the duration of Milankovitch cycles (5 th order). In central and western Sicily, the available data indicate that the duration order of 0.4-1 my seems to be the necessary time interval to complete the growth of structures having the amplitude of some hundred meters; the resulting growth rates are between 0.5 and 2 m/ky. The total amount of uplift within the studied structures, calculated at the 3 rd -, 4 th - and 5 th -order of duration, is not much greater than the thickness of the syntectonic strata that onlap the growth anticlines bordering the basins; this explains the evidence that the tectonic unconformities are only locally extended. Since individual growth events are unable to produce regional surfaces of erosion during the considered time intervals, the sequence stratigraphic analysis has been profitably applied in this setting of active compression. Regionally-extended unconformities with constant age on wide areas related to glacio-eustasy can be recognized, dated and used for large scale correlations.

ABSTRACT In this paper we attempt to show the relationship between geodynamics and sequence stratigraphy, emphasizing the effects of regional and local tectonics and their interaction with eustasy. These factors contributed to the final architecture of an area located in the frontal region of the Gibraltar Arc. The Plio-Pleistocene succession located in the Atlantic margin offshore of northern Morocco represents a well-developed Neogene progradational succession. Flexural loading in response to thrusting and extensional collapse of the Gibraltar Arc accretionary wedge, followed by widespread late orogenic uplift are the major mechanisms that controlled accomodation space along the margin. The main stratigraphic units have been subdivided into sequences and systems tracts and reveal nine Pleistocene fourth-order sequences interpreted as glacio-eustatic cycles. The role of minor structures, such as diapirs, ramp anticlines and normal faults that were active during sedimentation affects stratal patterns but does not modify the presence and timing of sequence boundaries and maximum flooding surfaces. The final stratigraphic signature of the Pleistocene in the study area is the result of the complex interaction of regional tectonics, glacio-eustasy, local tectonics and sedimentary processes.

Abstract Detailed sequence stratigraphic analysis allowed the interpretation of seventeen depositional sequences in the Oligocene through middle Miocene succession of the Pannonian Basin (Hungary), the largest basin of the central Paratethyan area (central/eastern Europe). Depositional sequences were identified based on the analysis of published geological descriptions of outcrops and study of 3,000 km of 2D reflection seismic profiles and 45 hydrocarbon exploration wells. Eight depositional sequence boundaries coincided with regional stage boundaries; and additional nine depositional sequence boundaries were identified within the regional stages. The sequences were stratigraphically positioned on the basis of calcareous nannofossil data from 26 wells. Within the constraints of the biostratigraphic resolution in this interval, the stratigraphic position of the sequences correlates well with the previous records of depositional sequences (Haq et al., 1988). Three sequences, one in the Rupelian Stage and two in the Burdigalian Stage, were not identified by Haq et al. (1988). The examined regional stages correlate within the Paratethyan region, from Switzerland to the Caspian Sea and show a direct correlation with the standard stages. Stage boundaries typically correlate with episodic closures of connections between the European epicontinental seas from Oligocene through middle Miocene time. These closures are interpreted to result from short-term glacio-eustatic falls that overprint longer-term local tectonics. Depositional sequences are believed to result from glacioeustasy superimposed on a tectonic signal. The results, obtained in this study, and compared with oxygen isotope records (Abreu and Haddad, this volume), show a close agreement between the number and the stratigraphic position of oxygen isotope events and sequences. This supports that the major driving mechanism of depositional sequence boundary formation is glacioeustasy rather than a local or regional tectonic mechanism, and the identified sequences in this study may thus be global in nature.

Abstract The Tertiary Piedmont Basin (TPB) is bounded by the Western Alps on the south and west, and northward by the northwestern end of the Apennines and is filled with a succession of siliciclastic sediments over 4,000 m thick. It develops internally to a south-dipping suture zone, on a basement consisting of allochthonous Alpine and Apenninic units. The TPB's history began at the end of the Eocene and continued through Oligocene time under mainly extensional tectonic conditions; whereas in the Miocene time the tectonic regime is dominated by compression. In the "Langhe" region, we recognized three groups of depositional sequences. Group A consists of continental to coastal conglomerates, shallow-marine sandstones and hemipelagic mudstones with thickness ranging from a few tens of meters to 600 m, and two depositional sequences (Early Oligocene; locally Late Eocene?) characterize this group. Group B is represented by six depositional sequences (B1-B6) of Late Oligocene to Burdigalian age. Each sequence consists of turbidite sandstones and subordinate resedimented conglomerates in the lower part and hemipelagic mudstones with intercalated thin-bedded turbidites in the upper part. Total thickness of group B may be greater than 1,000 m. Group C is represented by six depositional sequences (C1-C6) of Late Burdigalian-Early Tortonian age. It consists of turbidite systems with sandstone/mudstone ratios ranging from »1 to 1 at the depocentres and of mudstones on the slopes bounding the basin. Total thickness may be more than 2,000 m. Synsedimentary tectonic activity is indicated by the following: (a) angular unconformities (at the B1-B2 transition and at the lower boundary of B6) (b) onlap of turbidite sandstones on slightly folded mudstones (B1-B2 and B2-B3 boundaries) and (c) vertical and lateral evolution of facies which differs from that of the models proposed for eustatically-controlled sequences (Cl, C2 and C5). On the basis of biostratigraphic data (planktonic foraminifers and calcareous nannoplankton), the recognized sequences show the same frequency as 3rd-order global cycles (Haq et al., 1988). Biostratigraphic data provides a tool in correlating the sequences B5, B6, Cl, C2 and probably Bl to 3rd-order cycles 1.4 +ss 1.5 (supercycle TBI), 2.1, 2.2, 2.3 (supercycle TB2) and 1.1 (supercycle TBI) respectively.

Abstract One of the most difficult challenges of sequence stratigraphy is the establishment of synchrony between events observed in widely separated depositional basins. Problems arise primarily because the chronostratigraphic control in most passive margins is not adequate to constrain the ages of sequence boundaries to better than plus or minus a few million years. This resolution is often insufficient for the correlation of third-order sequences. Furthermore, unless a common mechanism affecting eustasy is assumed, such as variations in the volume of ice on the planet, there is no a priori reason to expect that sequences of similar age in widely separated basins are indeed synchronous. The stable oxygen isotope composition (δ 18 O) of marine carbonates is an independent proxy for ice volume (sea level) which has been under utilized in sequence stratigraphic analyses. This is somewhat surprising given the number of studies that have established a good relationship between foraminifera δ 18 O and ice volume in Pliocene to Pleistocene units. This paper builds on the work of Miller et al. (1987, 1991) and Abreu and Savini (1994) in identifying major Oligocene to middle Miocene isotope events and correlating them to sequence stratigraphic events. Identification of isotope events is based on δ 18 O data from DSDP sites 522, 529, 563, and 608, and ODP Site 747, drilled in abyssal water depths in the Atlantic and Indian oceans. These isotope records were used by Miller et al. (1991) to define Oligocene and Miocene oxygen isotope zones. In addition to the DSDP/ODP sites, we present oxygen and carbon isotope data from Petrobrás Well A drilled in bathyal water depths in the campos Basin on the Brazilian passive continental margin. Detailed biostratigraphy indicates that this well contains a fairly complete Oligocene to middle Miocene record. Ages of common isotope events in DSDP and ODP sites and Well A correspond remarkably well with the ages of Oligocene to middle Miocene sequence boundaries identified by Hardenbol et al. (this volume) and Vakarcs et al. (this volume) and correlated to the new time scale of Berggren et al. (1995). Because of the good correlation between the isotope and sequence stratigraphic records, we reconfirm that ice-volume change is the common mechanism driving both oxygen isotope and sea-level fluctuations from Oligocene to present time. We propose four previously unidentified early Oligocene to middle Miocene heavy oxygen isotope events that correlate with sequence boundaries identified in the Pannonian Basin (Vakarcs et al., this volume) and presented in the new cycle chart of Hardenbol et al. (this volume). Additionally, we suggest new chronostratigraphic positions for most of the heavy oxygen isotope zonal boundaries observed previously by Miller et al. (1991). We also present the chronostratigraphic positions for minimum ice-volume events (maximum flooding surfaces) determined from the isotopic record.

Abstract A sequence stratigraphic analysis of subsurface data from the Paleogene strata of the central North Sea has documented a stratigraphic framework of 18–20 "third-order" depositional sequences nested within 5 "second-order" major regression/transgression facies (R/TF) cycles. Additional sequences have been documented through correlation of the subsurface deposits to outcrop sections of northwest Europe. This paper will document only those sequences observable in the subsurface data and characterize these sequences within a low and high order framework. The order of a cycle is based on observations concerning its constituents and its impact on the depositional systems of the basin, not strictly on its duration. Integration of the composite standard biostratigraphic method enabled the construction of a consistent chronostratigraphy based on the correlation of hiatal intervals identified with graphic correlation data terraces. An ideal relationship of graphic correlation terraces within a sequence stratigraphic model is diagrammed, providing the theoretical basis for the correlations presented. A depositional model is also proposed as a variant of the classic Vail model, considering the effect of depositional profile and sediment supply in the preservation and distribution of systems tracts. Recent revisions in central North Sea lithostratigraphy and sequence stratigraphy provide an opportunity for comparison between different methods and data resolutions.

ABSTRACT During the Eocene, the Alicante region formed part of the southern passive margin of the Iberian continent. Shelf deposits are found in the northwest and north, slope sediments in the south and southeast parts of the region. On the platforms 14 Eocene 3rd-order cycles can be recognized. They are separated by erosional, karstic or dolomitized surfaces, or paleosoils. The coeval slope deposits contain both lowstand wedges (mass flows and calciturbidites) and late-highstand wedges (calciturbidites). Lithoclasts and loose foraminifera in these mass flows and turbidites were used to identify adjacent platforms and their sequence stratigraphic history. Three sequence boundaries are coincident with tectonic events (during the middle Middle Eocene, at the Middle/Late Eocene boundary, and during the late Late Eocene). These tectonic events, together with differential subsidence during cycle deposition and correlation with plate-tectonic events point to tectonic control of the majority of the south Spanish cycles. Glacio-eustatic fall may have made an important contribution in producing the sequence boundary at the Middle/Late Eocene boundary. The sequence boundary at the Eocene/Oligocene boundary may be explained exclusively by glacio-eustasy.