Advances in sequence stratigraphy and the development of depositional models have helped explain the origin of genetically related sedimentary packages during sea level cycles. These concepts have provided the basis for the recognition of sea level events in subsurface data and in outcrops of marine sediments around the world. Knowledge of these events has led to a new generation of Mesozoic and Cenozoic global cycle charts that chronicle the history of sea level fluctuations during the past 250 million years in greater detail than was possible from seismic-stratigraphic data alone. An effort has been made to develop a realistic and accurate time scale and widely applicable chronostratigraphy and to integrate depositional sequences documented in public domain outcrop sections from various basins with this chronostratigraphic framework. A description of this approach and an account of the results, illustrated by sea level cycle charts of the Cenozoic, Cretaceous, Jurassic, and Triassic intervals, are presented.

https://science.sciencemag.org/content/sci/235/4793/1156.full.pdf

Chronology of fluctuating sea levels since the triassic.

Analysis of data from 280 rivers discharging to the ocean indicates that sediment loads/yields are a log-linear function of basin area and maximum elevation of the river basin. Other factors controlling sediment discharge (e.g., climate, runoff) appear to have secondary importance. A notable exception is the influence of human activity, climate, and geology on the rivers draining southern Asia and Oceania. Sediment fluxes from small mountainous rivers, many of which discharge directly onto active margins (e.g., western South and North America and most high-standing oceanic islands), have been greatly underestimated in previous global sediment budgets, perhaps by as much as a factor of three. In contrast, sediment fluxes to the ocean from large rivers (nearly all of which discharge onto passive margins or marginal seas) have been overestimated, as some of the sediment load is subaerially sequestered in subsiding deltas. Before the proliferation of dam construction in the latter half of this century, rivers...

Geomorphic/Tectonic Control of Sediment Discharge to the Ocean: The Importance of Small Mountainous Rivers

We review Phanerozoic sea-level changes [543 million years ago (Ma) to the present] on various time scales and present a new sea-level record for the past 100 million years (My). Long-term sea level peaked at 100 ± 50 meters during the Cretaceous, implying that ocean-crust production rates were much lower than previously inferred. Sea level mirrors oxygen isotope variations, reflecting ice-volume change on the 10 4 - to 10 6 -year scale, but a link between oxygen isotope and sea level on the 10 7 -year scale must be due to temperature changes that we attribute to tectonically controlled carbon dioxide variations. Sea-level change has influenced phytoplankton evolution, ocean chemistry, and the loci of carbonate, organic carbon, and siliciclastic sediment burial. Over the past 100 My, sea-level changes reflect global climate evolution from a time of ephemeral Antarctic ice sheets (100 to 33 Ma), through a time of large ice sheets primarily in Antarctica (33 to 2.5 Ma), to a world with large Antarctic and large, variable Northern Hemisphere ice sheets (2.5 Ma to the present).

/pdf/the-phanerozoic-record-of-global-sea-level-change-14696qrujw.pdf

The Phanerozoic Record of Global Sea-Level Change

The overall mechanics of fold-and-thrust belts and accretionary wedges along compressive plate boundaries is considered to be analogous to that of a wedge of soil or snow in front of a moving bulldozer. The material within the wedge deforms until a critical taper is attained, after which it slides stably, continuing to grow at constant taper as additional material is encountered at the toe. The critical taper is the shape for which the wedge is on the verge of failure under horizontal compression everywhere, including the basal decollement. A wedge of less than critical taper will not slide when pushed but will deform internally, steepening its surface slope until the critical taper is attained. Common silicate sediments and rocks in the upper 10-15 km of the crust have pressure-dependent brittle compressive strengths which can be approximately represented by the empirical Coulomb failure criterion, modified to account for the weakening effects of pore fluid pressure. A simple analytical theory that predicts the critical tapers of subaerial and submarine Coulomb wedges is developed and tested quantitatively in three ways: First, laboratory model experiments with dry sand match the theory. Second, the known surface slope, basal dip, and pore fluid pressures in the active fold-and-thrust belt of western Taiwan are used to determine the effective coefficient of internal friction within the wedge,/x = 1.03, consistent with Byerlee's empirical law of sliding friction,/at, = 0.85, on the base. This excess of internal strength over basal friction suggests that although the Taiwan wedge is highly deformed by imbricate thrusting, it is not so pervasively fractured that frictional sliding is always possible on surfaces of optimum orientation. Instead, the overall internal strength apparently is controlled by frictional sliding along suboptimally oriented planes and by the need to fracture some parts of the observed geometrically complex structure for continued deformation. Third, using the above values of/at, and/x, we predict Hubbert-Rubey fluid pressure ratios X = Xt, for a number of other active subaerial and submarine accretionary wedges based on their observed tapers, finding values everywhere in excess of hydrostatic. These predicted overpressures are reasonable in light of petroleum drilling experience in general and agree with nearby fragmentary well data in specific wedges where they are available. The pressure-dependent Coulomb wedge theory developed here is expected to break down if the decollement exhibits pressure-independent plastic behavior because of either temperature or rock type. The effects of this breakdown are observed in the abrupt decrease in taper where wedge thicknesses exceed about 15 km, which is the predicted depth of the brittle-plastic transition in quartz-rich rocks for typical geothermal gradients. We conclude that fold-and-thrust belts and accretionary wedges have the mechanics of bulldozer wedges in compression and that normal laboratory fracture and frictional strengths are appropriate to mountain-building processes in the upper crust, above the brittle-plastic transition.

/pdf/mechanics-of-fold-and-thrust-belts-and-accretionary-wedges-39mfymsp74.pdf

Mechanics of fold-and-thrust belts and accretionary wedges

Cenozoic geological and plate tectonic evolution of SE Asia and the SW Pacific: computer-based reconstructions, model and animations

Sequence-stratigraphic concepts are used to identify genetically related strata and their bounding regional unconformities, or their correlative conformities, in seismic, well-log, and outcrop data. Documentation and age dating of these features in marine outcrops in different parts of the world have led to a new generation of Mesozoic and Cenozoic sea-level cycle charts with greater event resolution than that obtainable from seismic data alone. The cycles of sea-level change, interpreted from the rock record, are tied to an integrated chronostratigraphy that combines state-of-the-art geochronologic, magnetostratigraphic and biostratigraphic data. In this article we discuss the reasoning behind integrated chronostratigraphy and list the sources of data used to establish this framework. Once this framework has been constructed, the depositional sequences from sections around the world, interpreted as having been formed in response to sea-level fluctuations, can be tied into the chronostratigraphy.

Four cycle charts summarizing the chronostratigraphy, coastal-onlap patterns, and sea-level curves for the Cenozoic, Cretaceous, Jurassic, and Triassic are presented. A large-scale composite-cycle chart for the Mesozoic and Cenozoic is also included (in pocket). The relative magnitudes of sea-level falls, interpreted from sequence boundaries, are classified as major, medium, and minor, as are the condensed sections associated with the intervals of sediment starvation on the shelf and slope during the phase of maximum shelf flooding during each cycle. Generally, only the sequence boundaries produced by major and some medium-scale sea-level falls can be recognized at the level of seismic stratigraphic resolution; detailed well-log and/or outcrop studies are usually necessary to resolve the minor sequences.

Mesozoic and Cenozoic Chronostratigraphy and Cycles of Sea-Level Change

An Overview of the Fundamentals of Sequence Stratigraphy and Key Definitions

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

Peter R. Vail

Papers

Chronology of fluctuating sea levels since the triassic.

Mesozoic and Cenozoic Chronostratigraphy and Cycles of Sea-Level Change

An Overview of the Fundamentals of Sequence Stratigraphy and Key Definitions

Mesozoic and Cenozoic Sequence Chronostratigraphic Framework of European Basins

Seismic stratigraphy and global changes of sea level, Part 4 : Global cycles of relative changes of sea level