The Garn Formation (Bajocian‐Bathonian) in the Kristin Field, Halten Terrace

Messina, Carlo; Nemec, Wojciech; Martinius, Allard W.; Elfenbein, Carsten

doi:10.1002/9781118920435.ch18

Cited by 19 publications

(21 citation statements)

References 81 publications

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“…However, it is difficult to envisage an open shelf, or even the open marine-facing distal part of an embayed shelf, without wave action (cf. Messina et al, 2014), and, in our study areas, the fine facies lack the characteristics of storm-related event beds or specific evidence for wave action.…”

Section: Discussioncontrasting

confidence: 53%

Deposition and preservation of fluvio‐tidal shallow‐marine sandstones: A re‐evaluation of the Neoproterozoic Jura Quartzite (western Scotland)

et al. 2019

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The 2-5 km thick, sandstone-dominated (>90%) Jura Quartzite is an extreme example of a mature Neoproterozoic sandstone, previously interpreted as a tide-influenced shelf deposit and herein re-interpreted within a fluvio-tidal deltaic depositional model. Three issues are addressed: (1) evidence for the re-interpretation from tidal shelf to tidal delta; (2) reasons for vertical facies uniformity; and (3) sand supply mechanisms to form thick tidal-shelf sandstones. The predominant facies (compound cross-bedded, coarse-grained sandstones) represents the lower parts of metres to tens of metres high, transverse fluviotidal bedforms with superimposed smaller bedforms. Ubiquitous erosional surfaces, some Page 1 of 98 Sedimentology JURA QUARTZITE with granule-pebble lags, record erosion of the upper parts of those bedforms. There was selective preservation of the higher energy, topographically-lower, parts of channel-bar systems. Strongly asymmetric, bimodal, palaeocurrents are interpreted as due to associated selective preservation of fluvially-enhanced ebb tidal currents. Finer-grained facies are scarce, due largely to suspended sediment bypass. They record deposition in lower-energy environments, including channel mouth bars, between and downdepositional-dip of higher energy fluvio-ebb tidal bars. The lack of wave-formed sedimentary structures and low continuity of mudstone and sandstone interbeds, support deposition in a non-shelf setting. Hence, a sand-rich, fluvial-tidal, current-dominated, largely sub-tidal, delta setting is proposed. This new interpretation avoids the problem of transporting large amounts of coarse sand to a shelf. Facies uniformity and vertical stacking are likely due to sediment oversupply and bypass rather than balanced sediment supply and subsidence rates. However, facies evidence of relative sea level changes is difficult to recognise, which is attributed to (1) the areally extensive and polygenetic nature of the preserved facies, and (2) a large stored sediment buffer that dampened response to relative sea level and/or sediment supply changes. Consideration of preservation bias towards high-energy deposits may be more generally relevant, especially to thick Neoproterozoic and Lower Palaeozoic marine sandstones.

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Section: Discussioncontrasting

confidence: 53%

Deposition and preservation of fluvio‐tidal shallow‐marine sandstones: A re‐evaluation of the Neoproterozoic Jura Quartzite (western Scotland)

et al. 2019

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“…When the cross-sectional area of the strait exceeds S c , tidal currents are no longer amplified and thus they cannot have influence on the sea bed or are subordinated to wave action, as documented in other case studies (e.g. Anastas et al, 2006;Messina et al, 2014). The critical S c is not a dimensionally fixed element, but it depends upon: (i) the total discharge volume of water exchanged throughout the strait; and (ii) the mean velocity of the tidal currents [Q and U in the Allen equation (Eq.…”

Section: Transgressive Facies Modelmentioning

confidence: 82%

Three‐dimensional to two‐dimensional cross‐strata transition in the lower Pleistocene Catanzaro tidal strait transgressive succession (southern Italy)

2014

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Sandstone tidal cross-strata are the predominant sedimentary feature of strait-fill stratigraphic successions. However, although widely described in numerous studies, tidal strait-fill two-dimensional and three-dimensional cross-strata have\ud rarely been reported to occur in discrete intervals which are laterally adjacent or vertically stacked, and the meaning of this stratigraphic architecture has not yet been fully investigated. Understanding of the processes responsible for changes\ud in the internal features of modern and ancient tidal bedforms is essential in order to predict lateral and vertical heterogeneities in analogous reservoir strata.\ud This facies-based study aims to interpret the three-dimensional to two-dimensional cross-strata transition observed in the lower Pleistocene mixed siliciclastic/bioclastic sandstone filling the Catanzaro Strait, in southern Italy, during a continuous phase of tectonically driven marine transgression. Tidal cross-strata\ud disappear in the uppermost interval of the studied succession, where mudstone strata prevail. This stratigraphic trend is interpreted as the evidence of an important change in the tidal strait hydrodynamics due to a phase of relative sea-level rise. At the beginning of the transgression, three-dimensional tidal dunes migrated throughout the ca 3 to 4 km wide and ca 30 km long, WNW–ESE-oriented Catanzaro Strait, due to strong tidal currents amplified through the seaway and flowing in semi-diurnal phase opposition. As the intermediate phase of transgression enlarged the seaway width, the tidal current strength decreased as tidal water exchange occurred over a larger cross-sectional area.\ud The progressive reduction of the bed shear stress modified three-dimensional tidal dunes into an extensive two-dimensional bedform field. At the end of the transgression, the further widening of the Catanzaro Strait into a ca 10 to 12 km\ud wide marine passageway changed the tidally dominated strait into a non-tidal open shelf. The results of this research suggest the presence of a ‘critical cross-sectional area’ in the narrowest strait-centre zone which controls the activation and deactivation of tidal current amplification along a marine seaway

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“…The deposits of Facies 2d record sedimentation in areas partially isolated from the major tidal current pathways and are interpreted to represent ridge environments or sub-environments belonging to the dune-field complexes but localized along the troughs of large-scale bedforms or their lateral swales (e.g. Dumas et al, 2005;Messina et al, 2014). In modern dune fields developed in open-shelf current-dominated settings (e.g.…”

Section: Scalloped Foresets Showingmentioning

confidence: 99%

Anatomy of a mixed bioclastic–siliciclastic regressive tidal sand ridge: Facies‐based case study from the lower Pleistocene Siderno Strait, southern Italy

et al. 2021

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Sand ridges, a common feature of modern open shelves, reflect persistent currents and sediment availability under recent transgressive conditions. They represent the largest bedforms in the oceans and, as such, can yield information on long-term oceanographic processes. However, there is a limited number of tidal sand ridges documented from the rock record, examples of regressive tidal sand ridges are scarce and studies describing ridges in straits are even more rare. This study analyses a Gelasian succession within a structurally controlled, tide-dominated strait in the Siderno Basin, southern Italy. The strait connected two wider basins, and accumulated sediments reworked by amplified tidal (bi-directional) currents. A series of tidal sand ridges with superimposed dunes developed close to the south-eastern end of the strait, where bathymetry was deeper and flow expansion occurred. One of the best-exposed tidal sand ridges, 65 m thick, crops out along a ca 2 km long cliff. Large-scale, ESE-prograding, seaward-offlapping shingles contain sets of bioclastic-siliciclastic, coarse-grained, cross-stratified sandstones, erosionally overlying upper Pliocene shelf marls and fine-grained sandstones. Cross-strata show angular, tangential and sigmoidal foresets with compound architectures and a SSE migration, i.e. oblique to the main growth direction.Fossil content indicates open-marine conditions. The succession changes abruptly across an erosion surface to non-tidal, highly burrowed mixed siliciclastic-bioclastic fine-grained sandstones, less than 15 m thick. Documented features reflect stages of nucleation, active accretion and abandonment of an individual sand ridge, during a complete cycle of relative sea-level change. The ridge formed during a phase of normal regression, with accretion occurring during an initial highstand and the ensuing falling stage.

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The Garn Formation (Bajocian‐Bathonian) in the Kristin Field, Halten Terrace

Cited by 19 publications

References 81 publications

Deposition and preservation of fluvio‐tidal shallow‐marine sandstones: A re‐evaluation of the Neoproterozoic Jura Quartzite (western Scotland)

Deposition and preservation of fluvio‐tidal shallow‐marine sandstones: A re‐evaluation of the Neoproterozoic Jura Quartzite (western Scotland)

Three‐dimensional to two‐dimensional cross‐strata transition in the lower Pleistocene Catanzaro tidal strait transgressive succession (southern Italy)

Anatomy of a mixed bioclastic–siliciclastic regressive tidal sand ridge: Facies‐based case study from the lower Pleistocene Siderno Strait, southern Italy

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