Shelfbreak Physiography: An Overview

Vanney, Jean-René; Stanley, Daniel Jean

doi:10.2110/pec.83.06.0001

Cited by 36 publications

(31 citation statements)

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“…7-8; Vanney and Stanley, 1983;Steckler et al, 1999;Steel and Olsen, 2002;Patruno et al, 2015a). Because of the dominance of short-term progradation and long-term aggradation in cycles of continental shelf outbuilding (Bullimore et al, 2008;, shelf-edge clinoforms show lower progradation/aggradation ratios (with clinoform trajectories as high as 2.4°) and higher progradation resistance ratios (10 −2 -1) than delta-scale clinoforms (Patruno et al, 2015a) (Fig.…”

Section: Shelf-edge Scale Clinoforms (Figs 14-16)mentioning

confidence: 99%

Clinoforms and clinoform systems: Review and dynamic classification scheme for shorelines, subaqueous deltas, shelf edges and continental margins

Patruno

Helland‐Hansen

2018

Earth-Science Reviews

200

166

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A B S T R A C TClinoforms are inclined and normally basinward-dipping horizons developed over a range of spatial and temporal scales in both siliciclastic and carbonatic systems. The study of clinoform successions underpins sequence stratigraphy and all efforts to reconstruct the relative partitioning of reservoir, seal and source rocks along shoreline to basin-floor profiles.Here, we review clinoform research and propose a more systematic description and classification of clinoforms. This is a crucial step to improve predictions of facies and lithology distribution within shoreline to continental shelf and abyssal plain successions, together with the genesis, drivers and dynamics of their constituent sedimentary units.Four basic clinoform types are here distinguished in delta/shorelines, lacustrines and marine environments, on the basis of their overall spatial and temporal scale, morphology, outbuilding dynamic and geodynamic and depositional setting: (1, 2) delta-scale clinoforms, which in turns are sub-divided into shoreline and delta-scale subaqueous clinoforms; (3) shelf-edge clinoforms; and (4) continental-margin clinoforms. Delta-scale clinoform sets are tens of metres high and typically represent 1-10 3 kyr, with progradation rates ranging from 1,000-100,000 m/kyr for shorelines and "subaerial deltas" to 100-20,000 m/kyr for subaqueous deltas; shelfedge clinoform sets are hundreds of metres high and are nucleated and accreted in 0.1-20 Myr (usual progradation rates of 1-100 m/kyr) by successive cross-shelf transits of delta-scale clinoforms; continental-margin clinoform sets are thousands of metres high, hallmark key geodynamic/crustal boundaries (e.g., continent/ocean transition) and slowly prograde basinwards in ca. 5-100 Myr, with typical rates of 0.1-10 m/kyr. As a consequence of the very different progradation rates and of the difficulty of large-scale clinothems to backstep during transgressions, shorelines are the most dynamic clinoforms with regards to position, continental margins the least, and shelf-edges are intermediate. Shortly after a transgression, therefore, the four clinoform types may prograde synchronously along shoreline-to-abyssal plain transects, forming "compound clinoform" systems. During the subsequent regressive cycle, however, due to the dissimilarity in progradation rates, different clinoform types will normally merge progressively with each other, giving rise to "hybrid clinoforms" (e.g., shelf-edge deltas), and fewer depositional breaks-in-slope are distinguished along a single shoreline-toabyssal plain transect. Overall, all clinoform systems are the result of the dynamic evolution of compound and hybrid clinoforms along a temporal and spatial continuum, regulated by the cyclical backstepping of the smallerscale system within natural progradational-retrogradational cycles of larger-scale clinothem outbuilding.All clinothem types may show either an accretionary/active or draping/passive style, depending on the proximity to the sediment source. Draping clinothems are nearly...

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Section: Shelf-edge Scale Clinoforms (Figs 14-16)mentioning

confidence: 99%

Clinoforms and clinoform systems: Review and dynamic classification scheme for shorelines, subaqueous deltas, shelf edges and continental margins

Patruno

Helland‐Hansen

2018

Earth-Science Reviews

200

166

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“…Maximum organic-carbon content occurs in the basal transgressive systems tract and decreases stepwise to background levels at the maximum-flooding downlap surface. The continental slope/basin setting occurs where distinct and significant relief develops (Figure 4c), due in large part to the transition from continental to oceanic crust (Vanney and Stanley, 1983). The position and bathymetry of this setting leads to strong interaction with open-oceanic currents and processes.…”

Section: Sequence-scale Variationsmentioning

confidence: 99%

From Oil-Prone Source Rock to Gas-Producing Shale Reservoir – Geologic and Petrophysical Characterization of Unconventional Shale-Gas Reservoirs

Passey¹,

Bohacs²,

Esch³

et al. 2010

Proceedings of International Oil and Gas Conference and Exhibition in China

281

259

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Many currently producing shale-gas reservoirs are overmature oil-prone source rocks. Through burial and heating these reservoirs evolve from organic-matter-rich mud deposited in marine, lacustrine, or swamp environments. Key characterization parameters are: total organic carbon (TOC), maturity level (vitrinite reflectance), mineralogy, thickness, and organic matter type. Hydrogento-carbon (HI) and oxygen-to-carbon (OI) ratios are used to classify organic matter that ranges from oil-prone algal and herbaceous to gas-prone woody/coaly material.Although organic-matter-rich intervals can be hundreds of meters thick, vertical variability in TOC is high (<1-3 meters) and is controlled by stratigraphic and biotic factors. In general, the fundamental geologic building block of shale-gas reservoirs is the parasequence, and commonly 10's to 100's of parasequences comprise the organic-rich formation whose lateral continuity can be estimated using techniques and models developed for source rocks.Typical analysis techniques for shale-gas reservoir rocks include: TOC, X-ray diffraction, adsorbed/canister gas, vitrinite reflectance, detailed core and thin-section descriptions, porosity, permeability, fluid saturation, and optical and electron microscopy. These sample-based results are combined with full well-log suites, including high resolution density and resistivity logs and borehole images, to fully characterize these formations. Porosity, fluid saturation, and permeability derived from core can be tied to log response; however, several studies have shown that the results obtained from different core analysis laboratories can vary significantly, reflecting differences in analytical technique, differences in definitions of fundamental rock and fluid properties, or the millimeter-scale variability common in mudstones that make it problematic to select multiple samples with identical attributes.Porosity determination in shale-gas mudstones is complicated by very small pore sizes and, thus, large surface area (and associated surface water); moreover, smectitic clays that are commonly present in mud have interlayer water, but this clay family tends to be minimized in high maturity formations due to illitization. Finally, SEM images of ion-beam-milled samples reveal a separate nanoporosity system contained within the organic matter, possibly comprising >50% of the total porosity, and these pores may be hydrocarbon wet, at least during most of the thermal maturation process. A full understanding of the relation of porosity and gas content will result in development of optimized processes for hydrocarbon recovery in shale-gas reservoirs.

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“…Degradation of the shelf edge continued throughout the cycle in the model (Fig. 4a) (Vanney & Stanley, 1983). However, the volume of these deep marine deposits, consisting entirely of remobilized sediment, is relatively low (cf.…”

Section: Sediment Distributionmentioning

confidence: 94%

Grain‐Size Sorting of River–Shelf–Slope Sediments during Glacial–Interglacial Cycles: Modelling Grain‐Size Distribution and Interconnectedness Of Coarse‐Grained Bodies

Meijer

2008

Analogue and Numerical Modelling of Sedimentary Systems: From Understanding to Prediction

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Changing conditions during Quaternary glacial and interglacial stages have had a great influence on the location and amount of sedimentation, and on the grain size of deposits. In this modelling study, the volume and grain-size distribution in passive continental margin strata are investigated. A principal aspect of the basin-scale grain-size sorting process is the formation of a subaerial erosional unconformity. During forced regression, deltaic coarsening-up sequences are deposited on the shelf. The relatively coarse-grained topsets of these successions have a lower preservation potential than the finer prodelta deposits. Therefore, erosion on the exposed shelf results in enrichment of river-transported sediments with coarse material during sea-level lowstand. Thus, shelfal strata are depleted of coarse material, increasing the coarse content of deposits on the upper continental slope. In contrast, in the absence of an erosional unconformity, the composition of sediments on the shelf is relatively coarse. The extent to which sediment within a stratigraphic column has been separated into coarse strata, as opposed to mixed compositions, is expressed as a 'differentiation ratio'. Interconnectedness of coarse-grained sediment bodies in the stratigraphy of the continental shelf and slope is closely related to the palaeogeographical evolution, and is consequently a highly variable property.

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Shelfbreak Physiography: An Overview

Cited by 36 publications

References 0 publications

Clinoforms and clinoform systems: Review and dynamic classification scheme for shorelines, subaqueous deltas, shelf edges and continental margins

Clinoforms and clinoform systems: Review and dynamic classification scheme for shorelines, subaqueous deltas, shelf edges and continental margins

From Oil-Prone Source Rock to Gas-Producing Shale Reservoir – Geologic and Petrophysical Characterization of Unconventional Shale-Gas Reservoirs

Grain‐Size Sorting of River–Shelf–Slope Sediments during Glacial–Interglacial Cycles: Modelling Grain‐Size Distribution and Interconnectedness Of Coarse‐Grained Bodies

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