Spatial and temporal variations in incised valley systems from the Durban continental shelf, KwaZulu-Natal, South Africa

Green, Andrew N.; Dladla, N.N.; Garlick, G. Luke

doi:10.1016/j.margeo.2012.11.002

Cited by 51 publications

(31 citation statements)

References 34 publications

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“…Classic studies of fluvial sediments accumulating over unconformity surfaces describe these deposits with a chaotic internal configuration of reflectors (Nordfjord et al 2006, Green 2009, Green et al 2013. In contrast, our records represent fluvial facies with moderate architectural organization in the form of concentric infilling and moderate symmetry, similar to examples reported by Fielding et al (2005) and Gibling (2006).…”

Section: Lowstand System Tractsupporting

confidence: 81%

“…The amplitude homogeneity in reflectors of Facies A probably represents an infilling by homogeneous sediment, while the variable reflectors of Facies B might reflect alternation between muddy and sandy sediments. This organized infilling architecture recognized in fluvial paleochannels contrasts with seismo-stratigraphic classical models (Nordfjord et al 2006, Green et al 2013 and are similar to the descriptions of Fielding et al (2005) and Gibling (2006). The rivers lose transport competence during subtle relative sea level rises or stillstands that occurred since MIS 5e (Fig.…”

Section: Discussionsupporting

confidence: 67%

“…Classic studies based on Fisk (1944) applied the concepts of "forced regression" or "falling-stage systems tracts" as periods of incision with sediment bypass through the valley, associating the valley infilling with the lowstand and subsequent sea level rising (Posamentier & Vail 1988, Van Wagoner et al 1990, Dalrymple et al 1992, 1994, Posamentier et al 1992, Nordfjord et al 2006, Green 2009, Green et al 2013. The Falling-Stage System Tract term was applied by Catuneanu et al (2011) in reference to deposits accumulated after the onset of sea level fall, and, before the start of the next relative sea-level rise, this work was a nomenclature review about sequence stratigraphy.…”

Section: Falling-stage System Tractmentioning

confidence: 99%

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Incised valley paleoenvironments interpreted by seismic stratigraphic approach in Patos Lagoon, Southern Brazil

2018

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The Rio Grande do Sul (RS) coastal plain area (33,000 km 2) had its physiography modified several times through the Quaternary, responding to allogenic and autogenic forcings. The Patos Lagoon covers a significant area of RS coastal plain (10,000 km 2), where incised valleys were identified in previous works. About 1,000 km of high resolution (3.5 kHz) seismic profiles, radiocarbon datings, Standard Penetration Test (SPT) and gravity cores were analyzed to interpret the paleoenvironmental evolution as preserved in incised valley infills. Seismic facies were recognized by seismic parameters. The sediment cores were used to ground-truth the seismic interpretations and help in the paleoenvironmental identification. Key surfaces were established to detail the stratigraphical framework, and seismic facies were grouped into four seismic units, which one classified in respective system tracts within three depositional sequences. The oldest preserved deposits are predominantly fluvial and estuarine facies, representing the falling stage and lowstand system tracts. The Holocene transgressive records are dominated by muddy material, mainly represented by estuarine facies with local variations. The transgression culminated in Late Holocene deposits of Patos Lagoon, representing the highstand system tract. The depositional pattern of the vertical succession was controlled by eustatic variations, while the autogenic forcing (paleogeography and sediment supply) modulated the local facies variation.

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Section: Lowstand System Tractsupporting

confidence: 81%

Section: Discussionsupporting

confidence: 67%

Section: Falling-stage System Tractmentioning

confidence: 99%

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Incised valley paleoenvironments interpreted by seismic stratigraphic approach in Patos Lagoon, Southern Brazil

2018

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“…2-4). This surface is the youngest subaerial unconformity in the study area and is accorded a Last Glacial Maximum age on this basis (cf Green, 2009;Green et al, 2013b). In some areas, this is housed within the previously formed subaerial unconformity, in other areas it completely exhumes the underlying Surface 1 (Figs.…”

Section: Seismic Stratigraphic Interpretationmentioning

confidence: 88%

Seismic architecture, stratigraphy and evolution of a subtropical marine embayment: Maputo Bay, Mozambique

et al. 2015

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“…Their net preservation potential as persistent features in the stratigraphy is thus low. Isolated examples of smaller in situ drowned barrier spits have been imaged in a series of incised valleys offshore of the southest African coast (Green et al, ), though these are uncommon and probably relate to a lower antecedent gradient and greater amount of back‐barrier accommodation that allowed for their survival from transgressive ravinement processes (Green et al, ).…”

Section: Discussionmentioning

confidence: 99%

Overwash‐dominated stratigraphy of barriers with intermittent inlets

Green

Pillay

Cooper³

et al. 2019

Earth Surf Processes Landf

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The morphodynamics and structure of barriers with persistent tidal inlets have been well studied. In contrast the stratigraphy and functioning of barrier systems with ephemeral inlets is poorly understood. This article examines the barrier-inlet systems of two intermittently closed open lagoons or temporarily open closed estuaries on the east coast of South Africa. Multiple geophysical surveys using ground-penetrating radar (GPR) were correlated with exposed sections of the barrier where inlet formation revealed the internal stratigraphy. Stratigraphic observations were placed in the context of the contemporary wave dynamics and mesoscale geomorphic evolution. The integrated databases reveal an absence of migrating channel features. Instead the stratigraphy is dominated by landward dipping sheets of alternating high-and low-amplitude reflectors. These correlate with gravel, shell debris and heavy mineral-lined beds formed by overwash processes. Where ephemeral inlet structures are preserved in the stratigraphy, their fills comprise aggrading, high-amplitude reflectors, linked to washover infilling of the inlet mouth. Multiple small channels in the more distal portions of the barrier in georadar stratigraphy are related to channelized washover flow.These barriers often breach during high swell and are subsequently sealed during fairweather wave conditions. Time series analysis of waves and satellite imagery shows a link between storms from the south and breach events. This is consistent with the truncations in subsurface images and inferred barrier lowering by overwash channelling. These barriers experience quasi-stable oscillations in their landward and seaward shore position, punctuated by periods of barrier rollover associated with the most intense storms. As overwash is responsible in part for both the constructive and destructive phases of the barrier, these barriers have low preservation potential. Persistent rollover driven by overwashing will terminate once accommodation space is eliminated and the barriers are eroded by storm activity.

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Spatial and temporal variations in incised valley systems from the Durban continental shelf, KwaZulu-Natal, South Africa

Cited by 51 publications

References 34 publications

Incised valley paleoenvironments interpreted by seismic stratigraphic approach in Patos Lagoon, Southern Brazil

Incised valley paleoenvironments interpreted by seismic stratigraphic approach in Patos Lagoon, Southern Brazil

Seismic architecture, stratigraphy and evolution of a subtropical marine embayment: Maputo Bay, Mozambique

Overwash‐dominated stratigraphy of barriers with intermittent inlets

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