The Return of ‘
            <i>The Fan That Never Was</i>
            ’: Westphalian Turbidite Systems in the Variscan Culm Basin: Bude Formation (Southwest England)

Burne, Robert V.

doi:10.1002/9781444304091.ch5

Cited by 11 publications

(58 citation statements)

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“…Although many researchers have recognized the possible existence of¯ow types transitional between end-member turbidity currents and debris¯ows, and numerous local studies have described muddy sandstones or mixed beds in terms of slurries or slurry¯ows (e.g. Wood & Smith, 1959;Burne, 1970Burne, , 1995, there has been little evidence until now that transitional¯ows might play a major role in sedimentation, that they might leave distinctive deposits or that they need to be treated separately in discussions of deep-water sedimentation.…”

Section: Discussionmentioning

confidence: 99%

“…Chemical engineers commonly use the term slurry flow to describe any two‐phase, solid–fluid flow (Shook & Roco, 1991). Wood & Smith (1959) and Burne (1970, 1995) used the term ‘slurry beds’ to refer to deposits showing features suggestive of both cohesive and turbulent behaviour, and the terms slurries, slurry flows, slurry breccias and slurry sandstones have been applied by a number of investigators to watery debris flows or muddy turbidity currents and their deposits (Hampton, 1972; Carter, 1975; Hiscott & Middleton, 1979; Strong & Walker, 1981; Pierson & Costa, 1987; Jordan et al ., 1991). In the present study, the term slurry flows will be used to refer to muddy sand‐rich sediment flows that exhibit both turbulent and cohesive sediment support and are transitional between end‐member turbidity currents and cohesive debris flows.…”

Section: Introductionmentioning

confidence: 99%

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Slurry‐flow deposits in the Britannia Formation (Lower Cretaceous), North Sea: a new perspective on the turbidity current and debris flow problem

Lowe¹,

Guy²

2000

Sedimentology

260

193

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The Lower Cretaceous Britannia Formation (North Sea) includes an assemblage of sandstone beds interpreted here to be the deposits of turbidity currents, debris flows and a spectrum of intermediate flow types termed slurry flows. The term ‘slurry flow’ is used here to refer to watery flows transitional between turbidity currents, in which particles are supported primarily by flow turbulence, and debris flows, in which particles are supported by flow strength. Thick, clean, dish‐structured sandstones and associated thin‐bedded sandstones showing Bouma Tb–e divisions were deposited by high‐ and low‐density turbidity currents respectively. Debris flow deposits are marked by deformed, intraformational mudstone and sandstone masses suspended within a sand‐rich mudstone matrix. Most Britannia slurry‐flow deposits contain 10–35% detrital mud matrix and are grain supported. Individual beds vary in thickness from a few centimetres to over 30 m. Seven sedimentary structure division types are recognized in slurry‐flow beds: (M1) current structured and massive divisions; (M2) banded units; (M3) wispy laminated sandstone; (M4) dish‐structured divisions; (M5) fine‐grained, microbanded to flat‐laminated units; (M6) foundered and mixed layers that were originally laminated to microbanded; and (M7) vertically water‐escape structured divisions. Water‐escape structures are abundant in slurry‐flow deposits, including a variety of vertical to subvertical pipe‐ and sheet‐like fluid‐escape conduits, dish structures and load structures. Structuring of Britannia slurry‐flow beds suggests that most flows began deposition as turbidity currents: fully turbulent flows characterized by turbulent grain suspension and, commonly, bed‐load transport and deposition (M1). Mud was apparently transported largely as hydrodynamically silt‐ to sand‐sized grains. As the flows waned, both mud and mineral grains settled, increasing near‐bed grain concentration and flow density. Low‐density mud grains settling into the denser near‐bed layers were trapped because of their reduced settling velocities, whereas denser quartz and feldspar continued settling to the bed. The result of this kinetic sieving was an increasing mud content and particle concentration in the near‐bed layers. Disaggregation of mud grains in the near‐bed zone as a result of intense shear and abrasion against rigid mineral grains caused a rapid increase in effective clay surface area and, hence, near‐bed cohesion, shear resistance and viscosity. Eventually, turbulence was suppressed in a layer immediately adjacent to the bed, which was transformed into a cohesion‐dominated viscous sublayer. The banding and lamination in M2 are thought to reflect the formation, evolution and deposition of such cohesion‐dominated sublayers. More rapid fallout from suspension in less muddy flows resulted in the development of thin, short‐lived viscous sublayers to form wispy laminated divisions (M3) and, in the least muddy flows with the highest suspended‐load fallout rates, direct suspension sedimentation form...

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Slurry‐flow deposits in the Britannia Formation (Lower Cretaceous), North Sea: a new perspective on the turbidity current and debris flow problem

Lowe¹,

Guy²

2000

Sedimentology

260

193

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“…May not be submarine gravity current deposits. Burne (1995) Higgs (1991, 1998 Britannia Fm. North Sea…”

Section: Textural Analysis From Thin Section: Marnoso Arenacea Formationmentioning

confidence: 99%

Beds comprising debrite sandwiched within co‐genetic turbidite: origin and widespread occurrence in distal depositional environments

Talling¹,

Amy²,

Wynn³

et al. 2004

Sedimentology

212

317

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Co‐genetic debrite–turbidite beds occur in a variety of modern and ancient turbidite systems. Their basic character is distinctive. An ungraded muddy sandstone interval is encased within mud‐poor graded sandstone, siltstone and mudstone. The muddy sandstone interval preserves evidence of en masse deposition and is thus termed a debrite. The mud‐poor sandstone, siltstone and mudstone show features indicating progressive layer‐by‐layer deposition and are thus called a turbidite. Palaeocurrent indicators, ubiquitous stratigraphic association and the position of hemipelagic intervals demonstrate that debrite and enclosing turbidite originate in the same event. Detailed field observations are presented for co‐genetic debrite–turbidite beds in three widespread sequences of variable age: the Miocene Marnoso Arenacea Formation in the Italian Apennines; the Silurian Aberystwyth Grits in Wales; and Quaternary deposits of the Agadir Basin, offshore Morocco. Deposition of these sequences occurred in similar unchannellized basin‐plain settings. Co‐genetic debrite–turbidite beds were deposited from longitudinally segregated flow events, comprising both debris flow and forerunning turbidity current. It is most likely that the debris flow was generated by relatively shallow (few tens of centimetres) erosion of mud‐rich sea‐floor sediment. Changes in the settling behaviour of sand grains from a muddy fluid as flows decelerated may also have contributed to debrite deposition. The association with distal settings results from the ubiquitous presence of muddy deposits in such locations, which may be eroded and disaggregated to form a cohesive debris flow. Debrite intervals may be extensive (> 26 × 10 km in the Marnoso Arenacea Formation) and are not restricted to basin margins. Such long debris flow run‐out on low‐gradient sea floor (< 0·1°) may simply be due to low yield strength (≪ 50 Pa) of the debris–water mixture. This study emphasizes that multiple flow types, and transformations between flow types, can occur within the distal parts of submarine flow events.

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“…Furthermore, in the Culm Basin, the presence of wave-generated structures is not universally acknowledged (e.g. Burne 1998;Reading 1998). Equally, other workers in the Clare Basin have not described abundant wave-and storm-generated structures in either shallow-water or deep-water deposits (e.g.…”

Section: April 2006mentioning

confidence: 99%

Discussion on large sea, small tides: the Late Carboniferous seaway of NW Europe

Higgs¹,

Wells

Allison

et al. 2006

JGS

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The Return of ‘ The Fan That Never Was ’: Westphalian Turbidite Systems in the Variscan Culm Basin: Bude Formation (Southwest England)

Cited by 11 publications

References 0 publications

Slurry‐flow deposits in the Britannia Formation (Lower Cretaceous), North Sea: a new perspective on the turbidity current and debris flow problem

Slurry‐flow deposits in the Britannia Formation (Lower Cretaceous), North Sea: a new perspective on the turbidity current and debris flow problem

Beds comprising debrite sandwiched within co‐genetic turbidite: origin and widespread occurrence in distal depositional environments

Discussion on large sea, small tides: the Late Carboniferous seaway of NW Europe

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