Lateral juxtapositions of channel and lobe elements in distributive submarine fans: Three-dimensional outcrop study of the Ross Sandstone and geometric model

Pyles, David R.; Strachan, Lorna J.; Jennette, David C.

doi:10.1130/ges01042.1

Cited by 25 publications

(27 citation statements)

References 44 publications

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“…). The emphasis of Ross Formation studies to date has been mainly at the depositional element scale with a particular focus on thickening‐upward cycles (Chapin et al ., ; Lien et al ., ; MacDonald et al ., ), sheet and channel sandbody geometries (Collinson et al ., ; Elliott, ; Pyles, ; Pyles et al ., ), and the impact of erosion and bypass (Chapin et al ., ; Elliott, ; Lien et al ., ). Bed‐scale details have received less attention, although Barker (), Haughton et al .…”

Section: Geological Settingmentioning

confidence: 99%

“…1). The emphasis of Ross Formation studies to date has been mainly at the depositional element scale with a particular focus on thickening-upward cycles (Chapin et al, 1994;Lien et al, 2003;MacDonald et al, 2011), sheet and channel sandbody geometries (Collinson et al, 1991;Elliott, 2000a;Pyles, 2008;Pyles et al, 2014), and the impact of erosion and bypass (Chapin et al, 1994;Elliott, 2000b;Lien et al, 2003). Bed-scale details have received less attention, although Barker (2005), Haughton et al (2009) and Pyles & Jennette (2009) drew attention to hybrid event beds (linked turbidite-debrite beds of Pyles & Jennette, 2009) in the lowermost part of the succession that is only well-exposed at Ballybunion (Fig.…”

Section: Ross Sandstone Formationmentioning

confidence: 99%

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Variable character and diverse origin of hybrid event beds in a sandy submarine fan system, Pennsylvanian Ross Sandstone Formation, western Ireland

et al. 2018

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Hybrid event beds comprising both clean and mud‐rich sandstone are important components of many deep‐water systems and reflect the passage of turbulent sediment gravity flows with zones of clay‐damped or suppressed turbulence. ‘Behind‐outcrop’ cores from the Pennsylvanian deep‐water Ross Sandstone Formation reveal hybrid event beds with a wide range of expression in terms of relative abundance, character and inferred origin. Muddy hybrid event beds first appear in the underlying Clare Shale Formation where they are interpreted as the distal run‐out of the wakes to flows which deposited most of their sand up‐dip before transforming to fluid mud. These are overlain by unusually thick (up to 4·4 m), coarse sandy hybrid event beds (89% of the lowermost Ross Formation by thickness) that record deposition from outsized flows in which transformations were driven by both substrate entrainment in the body of the flow and clay fractionation in the wake. A switch to dominantly fine‐grained sand was accompanied initially by the arrest of turbulence‐damped, mud‐rich flows with evidence for transitional flow conditions and thick fluid mud caps. The mid and upper Ross Formation contain metre‐scale bed sets of hybrid event beds (21 to 14%, respectively) in (i) upward‐sandying bed set associations immediately beneath amalgamated sheet or channel elements; (ii) stacked thick‐bedded and thin‐bedded hybrid event bed‐dominated bed sets; (iii) associations of hybrid event bed‐dominated bed sets alternating with conventional turbidites; and (iv) rare outsized hybrid event beds. Hybrid event bed dominance in the lower Ross Formation may reflect significant initial disequilibrium, a bias towards large‐volume flows in distal sectors of the basin, extensive mud‐draped slopes and greater drop heights promoting erosion. Higher in the formation, hybrid event beds record local perturbations related to channel switching, lobe relocations and extension of channels across the fan surface. The Ross Sandstone Formation confirms that hybrid event beds can form in a variety of ways, even in the same system, and that different flow transformation mechanisms may operate even during the passage of a single flow.

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Section: Geological Settingmentioning

confidence: 99%

Section: Ross Sandstone Formationmentioning

confidence: 99%

Variable character and diverse origin of hybrid event beds in a sandy submarine fan system, Pennsylvanian Ross Sandstone Formation, western Ireland

et al. 2018

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“…The lower portion of the succession, the Shannon Group ( Fig. 1B; Clare Shale, Ross Sandstone and Gull Island formations), represents deep-marine and slope depositional environments (Hodson & Lewarne, 1961;Rider, 1974;Gill, 1979;Chapin et al, 1994;Wignall & Best, 2000Lien et al, 2003;Martinsen et al, 2003Martinsen et al, , 2017Pyles & Jennette, 2009;Pyles et al, 2011Pyles et al, , 2014Pierce et al, 2018). The Pennsylvanian (Namurian) Central Clare Group overlies these deposits ( Fig.…”

Section: Geological Settingmentioning

confidence: 99%

Early burial mud diapirism and its impact on stratigraphic architecture in the Carboniferous of the Shannon Basin, County Clare, Ireland

et al. 2018

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Delta fronts are often characterized by high rates of sediment supply that result in unstable slopes and a wide variety of soft‐sediment deformation, including the formation of overpressured and mobile muds that may flow plastically during early burial, potentially forming mud diapirs. The coastal cliffs of County Clare, western Ireland, expose Pennsylvanian (Namurian) delta‐front deposits of the Shannon Basin at large scale and in three dimensions. These deposits include decametre‐scale, internally chaotic mudstone masses that clearly impact the surrounding sedimentary strata. Evidence indicates that these were true mud (unlithified sediment) diapirs that pierced overlying strata. This study documents a well‐exposed ca 20 m tall mud diapir and its impact on the surrounding mouth‐bar deposits of the Tullig Cyclothem. A synsedimentary fault and associated rollover dome, evident from stratal thicknesses and the dip of the beds, define one edge of the diapir. These features are interpreted as recording the reactive rise of the mud diapir in response to extensional faulting along its margin. Above the diapir, heterolithic sandstones and siltstones contain evidence for the creation of localized accommodation, suggesting synsedimentary filling, tilting and erosion of a shallow sag basin accommodated by the progressive collapse of the diapir. Two other diapirs are investigated using three‐dimensional models built from ‘structure from motion’ drone imagery. Both diapirs are interpreted to have grown predominantly through passive rise (downbuilding). Stratal relationships for all three diapirs indicate that they were uncompacted and fluid‐rich mud beds that became mobilized through soft‐sediment deformation during early burial (i.e. <50 m, likely <10 m depth). Each diapir locally controlled the stratigraphic architecture in the shallow subsurface and potentially influenced local palaeocurrents on the delta. The mud diapirs studied herein are distinct from deeper ‘shale diapirs’ that have been inferred from seismic sections worldwide, now largely disputed.

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“…The principle of compensational stacking has been suggested to be widely developed at various scales of lobe deposition from beds to lobe complexes (e.g. Mutti and Sonnino, 1981;Pickering et al, 1989;Gervais et al, 2006;Deptuck et al, 2008;Prelat et al, 2009;Bourget et al, 2010;Prelat et al, 2010;Straub and Pyles, 2012;Prelat and Hodgson, 2013;Pyles et al, 2014;Zhang et al, 2015).…”

Section: Stacking Patterns Of Turbidite Lobe Depositsmentioning

confidence: 99%

Deepwater Turbidite Lobe Deposits: A Review of the Research Frontiers

Zhang

Mao

Wang

2017

Acta Geologica Sinica - English Edition

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Deepwater/deep‐marine turbidite lobes are the most distal part of a siliciclastic depositional system and hold the largest sediment accumulation on the seafloor. As many giant hydrocarbon provinces have been discovered within deepwater lobe deposits, they represent one of the most promising exploration targets for hydrocarbon industry. Deepwater exploration is characterized by high cost, high risk but insufficient data because of the deep/ultra–deepwater depth. A thorough understanding of the deepwater turbidite lobe architecture, hierarchy, stacking pattern and internal facies distribution is thus vital. Recently, detailed outcrop characterizations and high–resolution seismic studies have both revealed that the deepwater lobe deposits are characterized into four–fold hierarchical arrangements from “beds”, to “lobe elements”, to “lobes” and to “lobe complex”. Quantitative compilations have shown that hierarchical components of lobe deposits have similar length to width ratios but different width to thickness ratios depending on different turbidite systems. At all hierarchical scales, sand–prone hierarchical lobe units are always separated by mud–prone bounding units except when the bounding units are eroded by their overlying lobe units thus giving rise to vertical amalgamation and connectivity. Amalgamations often occur at more proximal regions suggesting high flow energy. A mixed flow behavior may occur towards more distal regions, resulting in deposition of “hybrid event beds”. These synthesized findings could (1) help understand the lobe reservoir distribution and compartmentalization therefore benefit the exploration and development of turbidite lobes within the deep marine basins (e.g. South China Sea) and (2) provide rules and quantitative constraints on reservoir modeling. In addition, the findings associated with deepwater turbidite lobes might be a good starting point to understand the sedimentology, architecture and hierarchy of turbidites in deep lacustrine environment.

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Lateral juxtapositions of channel and lobe elements in distributive submarine fans: Three-dimensional outcrop study of the Ross Sandstone and geometric model

Cited by 25 publications

References 44 publications

Variable character and diverse origin of hybrid event beds in a sandy submarine fan system, Pennsylvanian Ross Sandstone Formation, western Ireland

Variable character and diverse origin of hybrid event beds in a sandy submarine fan system, Pennsylvanian Ross Sandstone Formation, western Ireland

Early burial mud diapirism and its impact on stratigraphic architecture in the Carboniferous of the Shannon Basin, County Clare, Ireland

Deepwater Turbidite Lobe Deposits: A Review of the Research Frontiers

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