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  • 1
    Online Resource
    Online Resource
    Upward-thickening patterns and lateral continuity of Permian sand-rich turbidite channel fills, Laingsburg Karoo, South Africa : Topographically controlled channel-overbank system
    Wiley ; 2003
    In:  Sedimentology Vol. 50, No. 5 ( 2003-08-27), p. 831-853
    Details
    In: Sedimentology, Wiley, Vol. 50, No. 5 ( 2003-08-27), p. 831-853
    Type of Medium: Online Resource
    ISSN: 0037-0746 , 1365-3091
    URL: Article
    DOI: 10.1046/j.1365-3091.2003.00576.x
    RVK:
    RB 10121
    Language: English
    Publisher: Wiley
    Publication Date: 2003
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  • 2
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    Transport and deposition of mud in deep‐water environments: Processes and stratigraphic implications
    Wiley ; 2019
    In:  Sedimentology Vol. 66, No. 7 ( 2019-12), p. 2894-2925
    Details
    In: Sedimentology, Wiley, Vol. 66, No. 7 ( 2019-12), p. 2894-2925
    Abstract: Deep‐water mudstones are often considered as background sediments, deposited by vertical suspension fallout, and the range of transport and depositional processes are poorly understood compared with their shallow‐marine counterparts. This study presents a dataset from a 538·50 m thick cored succession through the Permian muddy lower Ecca Group of the Tanqua depocentre (south‐west Karoo Basin, South Africa). This study aims to characterize the range of mudstone facies, transport and depositional processes, and stacking patterns recorded in deep‐water environments prior to deposition of the Tanqua Karoo sandy basin‐floor fans. A combination of macroscopic and microscopic description techniques and ichnological analysis has defined nine sedimentary facies that stack in a repeated pattern to produce 2 to 26 m thick depositional units. The lower part of each unit is characterized by bedded mudstone deposited by dilute, low‐density turbidity currents with evidence for hyperpycnal‐flow processes and sediment remobilization. The upper part of each unit is dominated by more organic‐rich bedded mudstone with common mudstone intraclasts, deposited by debris flows and transitional flows, with scarce indicators of suspension fallout. The intensity of bioturbation and burrow size increases upward through each depositional unit, consistent with a decrease in physicochemically stressed conditions, linked to a lower sediment accumulation rate. This vertical facies transition in the single well dataset can be interpreted to represent relative sea‐level variations; the hyperpycnal stressed conditions in the lower part of the units were driven by relative sea‐level fall, and the more bioturbated upper part of the units represent backstepping, related to relative sea‐level rise. Alternatively, this facies transition may represent autogenic compensational stacking. The prevalence of sediment density flow deposits, even in positions distal or lateral to the sediment entry point, challenges the idea that deep‐water mudstones are primarily the deposits of passive rainout along continental margins.
    Type of Medium: Online Resource
    ISSN: 0037-0746 , 1365-3091
    URL: Issue
    URL: Article
    DOI: 10.1111/sed.v66.7
    DOI: 10.1111/sed.12614
    RVK:
    RB 10121
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 2020955-1
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  • 3
    Online Resource
    Online Resource
    Anatomy, geometry and sequence stratigraphy of basin floor to slope turbidite systems, Tanqua Karoo, South Africa
    Wiley ; 2001
    In:  Sedimentology Vol. 48, No. 5 ( 2001-10-21), p. 987-1023
    Details
    In: Sedimentology, Wiley, Vol. 48, No. 5 ( 2001-10-21), p. 987-1023
    Type of Medium: Online Resource
    ISSN: 0037-0746 , 1365-3091
    URL: Article
    DOI: 10.1046/j.1365-3091.2001.00405.x
    RVK:
    RB 10121
    Language: English
    Publisher: Wiley
    Publication Date: 2001
    detail.hit.zdb_id: 2020955-1
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  • 4
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    Online Resource
    Distribution of soft-sediment deformation structures in clinoform successions of the Permian Ecca Group, Karoo Basin, South Africa
    Elsevier BV ; 2011
    In:  Sedimentary Geology Vol. 235, No. 3-4 ( 2011-4), p. 314-330
    Details
    In: Sedimentary Geology, Elsevier BV, Vol. 235, No. 3-4 ( 2011-4), p. 314-330
    Type of Medium: Online Resource
    ISSN: 0037-0738
    URL: Article
    DOI: 10.1016/j.sedgeo.2010.09.011
    RVK:
    RA 1000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2011
    detail.hit.zdb_id: 216739-6
    detail.hit.zdb_id: 2012818-6
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  • 5
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    Discriminating stacked distributary channel from palaeovalley fill sand bodies in foreland basin settings
    Elsevier BV ; 2020
    In:  Sedimentary Geology Vol. 398 ( 2020-03), p. 105592-
    Details
    In: Sedimentary Geology, Elsevier BV, Vol. 398 ( 2020-03), p. 105592-
    Type of Medium: Online Resource
    ISSN: 0037-0738
    URL: Article
    DOI: 10.1016/j.sedgeo.2020.105592
    RVK:
    RA 1000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2020
    detail.hit.zdb_id: 216739-6
    detail.hit.zdb_id: 2012818-6
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  • 6
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    Aseismic controls on in situ soft‐sediment deformation processes and products in submarine slope deposits of the Karoo Basin, South Africa
    Wiley ; 2009
    In:  Sedimentology Vol. 56, No. 5 ( 2009-08), p. 1201-1225
    Details
    In: Sedimentology, Wiley, Vol. 56, No. 5 ( 2009-08), p. 1201-1225
    Abstract: Intervals of soft‐sediment deformation features, including vertical fluid escape and load structures, are common and well‐exposed in Permian lower slope deposits of the Tanqua Depocentre, Karoo Basin. The structures mainly comprise elongated flames and load structures associated with ruptured sandstones and structureless siltstones, observed over a range of scales. The presence of an upper structureless siltstone layer linked to the flames, interpreted as a product of the debouching of fine‐grained material transported through the flame onto the palaeo‐seabed, together with the drag and upward folding of lower sandstone layers is evidence that the flames were formed in situ by upward movement of sediment‐rich fluids. Flames are oriented parallel to the deep‐water palaeoslope in lateral splay deposits between two major slope channel complexes. Statistical correlation and regression analyses of 180 flame structures from seven stratigraphic intervals suggest a common mechanism for the deformation and indicate the importance of fluidization as a deformation mechanism. Importantly, deformation occurred in an instantaneous and synchronous manner. Liquefaction and fluidization were triggered by incremental movement of sediment over steeper local gradients that were generated by deposition of a lateral splay on an inherited local north‐west‐facing slope. Seismic activity is not invoked as a trigger mechanism because of the restricted spatial occurrence of these features and the lack of indications of earthquakes during the time of deposition of the deep‐water succession. The driving mechanisms that resulted in the final configuration of the soft‐sediment deformation structures involved a combination of vertical shear stress caused by fluidization, development of an inverse density gradient and a downslope component of force associated with the local slope. Ground‐penetrating radar profiles confirm the overall north‐east orientation of the flame structures and provide a basis for recognition of potential larger‐scale examples of flames in seismic reflection data sets.
    Type of Medium: Online Resource
    ISSN: 0037-0746 , 1365-3091
    URL: Issue
    URL: Article
    DOI: 10.1111/sed.2009.56.issue-5
    DOI: 10.1111/j.1365-3091.2008.01029.x
    RVK:
    RB 10121
    Language: English
    Publisher: Wiley
    Publication Date: 2009
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  • 7
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    Online Resource
    Exhumed lateral margins and increasing flow confinement of a submarine landslide complex
    Wiley ; 2018
    In:  Sedimentology Vol. 65, No. 4 ( 2018-06), p. 1067-1096
    Details
    In: Sedimentology, Wiley, Vol. 65, No. 4 ( 2018-06), p. 1067-1096
    Abstract: Submarine landslides, including the basal shear surfaces along which they fail, and their subsequent infill, are commonly observed in modern seabed and seismic reflection data sets; their resultant relief impacts sediment routing and storage patterns on continental margins. Here, three stacked submarine landslides are documented from the Permian Ecca Group, Laingsburg depocentre, Karoo Basin, South Africa, including two superimposed lateral margins. The stratigraphic framework includes measured sections and correlated surfaces along a 3 km long, 150 m high outcrop. Two stacked 2·0 to 4·5 km wide and 90 m and 60 m deep erosion surfaces are recognized, with lateral gradients of 8° and 4°, respectively. The aim of this study was to understand the evolution of a submarine landslide complex, including: evolution of basal shear surfaces/zones; variation of infill confinement; and location of the submarine landslides in the context of basin‐scale sedimentation and degradation rates. Three stages of formation are identified: (i) failure of submarine landslide 1, with deposition of unconfined remobilized deposits; (ii) failure of submarine landslide 2, forming basal shear surface/zone 1, with infill of remobilized deposits and weakly confined turbidites; and (iii) failure of submarine landslide 3, forming basal shear surface/zone 2, with infill of remobilized deposits and confined turbidites, transitioning stratigraphically to unconfined deposits. The expression of basal shear varies laterally, from metres thick zones in silt‐rich strata to sharp stepped surfaces in sand‐rich strata. Faulting and rotation of overlying bedding suggest that the shear surfaces/zones were dynamic. Stacking of landslides resulted from multi‐phase slope failure, increasing down‐dip topography and confinement of infilling deposits. The failure slope was probably a low supply tilted basin margin evidenced by megaclast entrainment from underlying basin‐floor successions and the lack of channel systems. This study develops a generic model of landslide infill, as a function of sedimentation and degradation rates, which can be applied globally.
    Type of Medium: Online Resource
    ISSN: 0037-0746 , 1365-3091
    URL: Issue
    URL: Article
    DOI: 10.1111/sed.2018.65.issue-4
    DOI: 10.1111/sed.12415
    RVK:
    RB 10121
    Language: English
    Publisher: Wiley
    Publication Date: 2018
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  • 8
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    Aggradational lobe fringes: The influence of subtle intrabasinal seabed topography on sediment gravity flow processes and lobe stacking patterns
    Wiley ; 2017
    In:  Sedimentology Vol. 64, No. 2 ( 2017-02), p. 582-608
    Details
    In: Sedimentology, Wiley, Vol. 64, No. 2 ( 2017-02), p. 582-608
    Abstract: Seabed topography is ubiquitous across basin‐floor environments, and influences sediment gravity flows and sediment dispersal patterns. The impact of steep (several degrees) confining slopes on sedimentary facies and depositional architecture has been widely documented. However, the influence of gentle (fraction of a degree) confining slopes is less well‐documented, largely due to outcrop limitations. Here, exceptional outcrop and research borehole data from Unit A of the Permian Laingsburg Formation, South Africa, provide the means to examine the influence of subtle lateral confinement on flow behaviour and lobe stacking patterns. The dataset describes the detailed architecture of subunits A.1 to A.6, a succession of stacked lobe complexes, over a palinspastically restored 22 km across‐strike transect. Facies distributions, stacking patterns, thickness and palaeoflow trends indicate the presence of a south‐east facing low angle (fraction of a degree) lateral intrabasinal slope. Interaction between stratified turbidity currents with a thin basal sand‐prone part and a thick mud‐prone part and the confining slope results in facies transition from thick‐bedded sandstones to thin‐bedded heterolithic lobe fringe‐type deposits. Slope angle dictates the distance over which the facies transition occurs (hundreds of metres to kilometres). These deposits are stacked vertically over tens of metres in successive lobe complexes to form an aggradational succession of lobe fringes. Extensive slides and debrites are present at the base of lobe complexes, and are associated with steeper restored slope gradients. The persistent facies transition across multiple lobe complexes, and the mass flow deposits, suggests that the intrabasinal slope was dynamic and was never healed by deposition during Unit A times. This study demonstrates the significant influence that even subtle basin‐floor topography has on flow behaviour and depositional architecture of submarine lobe complexes. In addition, we present a new aggradational lobe fringe facies associations and recognition criteria for subtle confinement in less well‐exposed and subsurface basin fills.
    Type of Medium: Online Resource
    ISSN: 0037-0746 , 1365-3091
    URL: Issue
    URL: Article
    DOI: 10.1111/sed.2017.64.issue-2
    DOI: 10.1111/sed.12315
    RVK:
    RB 10121
    Language: English
    Publisher: Wiley
    Publication Date: 2017
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  • 9
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    Stratigraphic change in flow transformation processes recorded in early post‐rift deep‐marine intraslope lobe complexes
    Wiley ; 2023
    In:  Sedimentology Vol. 70, No. 5 ( 2023-08), p. 1379-1412
    Details
    In: Sedimentology, Wiley, Vol. 70, No. 5 ( 2023-08), p. 1379-1412
    Abstract: The Early Jurassic Los Molles Formation in the Neuquén Basin of western Argentina is a rare example of well‐exposed syn‐rift to post‐rift stratigraphy. In the Chachil Graben, the onset of the early post‐rift stage is marked by drowning of a carbonate system and the development of two deep‐marine intraslope lobe complexes. This field‐based study in the Chachil Graben involved field mapping and correlating eleven stratigraphic logs, and petrographic analysis to document how grain size and texture within intraslope lobe sandstones change from the lobe centre to their frontal pinch‐out. Eight different bed‐scale facies are identified and inferred to be formed by turbulent (turbidites; Type A and B beds), transient turbulent–laminar (transitional flow deposits; Type C, D, E and F beds), laminar gravity flows (debrites; Type G) and post‐depositional clastic injections (injectites; Type H beds). Fifteen lobes form two stacked lobe complexes that show stratigraphic evolution from a lower argillaceous sandstone‐dominated lobe complex, built by transitional flow deposits, to an upper coarser‐grained, sandier lobe complex largely constructed by turbidites. Petrographic analysis quantified sandstone mineralogy, matrix content, grain size and sorting, revealing that both lobe complexes are volcanic arc‐sourced. This study proposes that the differences in the character of the two lobe complexes are due to maturation of sediment transport routes through progressive healing of the intraslope relief, with a concomitant decrease in substrate erosion and flow bulking. Also proposed here is a model for intraslope lobe complex development that accounts for the impact of flow‐confinement on flow behaviour and transformation induced by the inherited topography. Bed type distribution suggests that high‐density flows terminate more abruptly against confining slopes and produce greater depositional variability than lower‐density flows. This integrated petrographic, architectural and sedimentary process model provides new insights into how post‐rift intraslope lobe systems may act as hydrocarbon reservoirs, aquifers and carbon storage sites.
    Type of Medium: Online Resource
    ISSN: 0037-0746 , 1365-3091
    URL: Issue
    URL: Article
    DOI: 10.1111/sed.v70.5
    DOI: 10.1111/sed.13086
    RVK:
    RB 10121
    Language: English
    Publisher: Wiley
    Publication Date: 2023
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  • 10
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    Shelf‐margin clinothem progradation, degradation and readjustment: Tanqua depocentre, Karoo Basin (South Africa)
    Wiley ; 2018
    In:  Sedimentology Vol. 65, No. 3 ( 2018-04), p. 809-841
    Details
    In: Sedimentology, Wiley, Vol. 65, No. 3 ( 2018-04), p. 809-841
    Abstract: Degradation of basin‐margin clinothems around the shelf‐edge rollover zone may lead to the generation of conduits through which gravity flows transport sediment downslope. Many studies from seismic‐reflection data sets show these features, but they lack small‐scale (centimetre to metre) sedimentary and stratigraphic observations on process interactions. Exhumed basin‐margin clinothems in the Tanqua depocentre (Karoo Basin) provide seismic‐reflection‐scale geometries and internal details of architecture with depositional dip and strike control. At the Geelhoek locality, clinothem parasequences comprise siltstone‐rich offshore deposits overlain by heterolithic prodelta facies and sandstone‐dominated deformed mouth bars. Three of these parasequences are truncated by a steep (6 to 22°), 100 m deep and 1·5 km wide asymmetrical composite erosion surface that delineates a shelf‐incised canyon. The fill, from base to top comprises: (i) thick‐bedded sandstone with intrabasinal clasts and multiple erosion surfaces; (ii) scour‐based interbedded sandstone and siltstone with tractional structures; and (iii) inverse‐graded to normal‐graded siltstone beds. An overlying 55 m thick coarsening‐upward parasequence fills the upper section of the canyon and extends across its interfluves. Younger parasequences display progressively shallower gradients during progradation and healing of the local accommodation. The incision surface resulted from initial oversteepening and high sediment supply triggering deformation and collapse at the shelf edge, enhanced by a relative sea‐level fall that did not result in subaerial exposure of the shelf edge. Previous work identified an underlying highly incised, sandstone‐rich shelf‐edge rollover zone across‐margin strike, suggesting that there was migration in the zone of shelf edge to upper‐slope incision over time. This study provides an unusual example of clinothem degradation and readjustment with three‐dimensional control in an exhumed basin‐margin succession. The work demonstrates that large‐scale erosion surfaces can develop and migrate due to a combination of factors at the shelf‐edge rollover zone and proposes additional criteria to predict clinothem incision and differential sediment bypass in consistently progradational systems.
    Type of Medium: Online Resource
    ISSN: 0037-0746 , 1365-3091
    URL: Issue
    URL: Article
    DOI: 10.1111/sed.2018.65.issue-3
    DOI: 10.1111/sed.12406
    RVK:
    RB 10121
    Language: English
    Publisher: Wiley
    Publication Date: 2018
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