Constraining the sedimentology and stratigraphy of submarine intraslope lobe deposits using exhumed examples from the Karoo Basin, South Africa

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1016/j.sedgeo.2015.03.013.

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Authors

Yvonne Spychala , David M Hodgson, Stephen Flint, Nigel Mountney

Abstract

Intraslope lobe deposits provide a record of the infill of accommodation on submarine slopes and their recognition enables the accurate reconstruction of the stratigraphic evolution of submarine slope systems. Extensive exposures of discrete sand-prone packages in Units D/E and E, Fort Brown Formation, Karoo Basin, South Africa, permit analysis of the sedimentology and stacking patterns of three intraslope lobe complexes and their palaeogeographic reconstruction via bed-scale analysis and physical correlation of key stratal surfaces. The sand-prone packages comprise tabular, aggradationally to slightly compensationally stacked lobe deposits with constituent facies associations that can be attributed to lobe axis, lobe off-axis, lobe-fringe and distal lobe-fringe environments. Locally, intraslope lobe deposits are incised by low aspect ratio channels that mark basinward progradation of the deepwater system. The origin of accommodation on the slope for lobe deposition is interpreted to be due to differential compaction or healing of scars from mass wasting processes. The stacking patterns and sedimentary facies arrangement identified in this study are distinct from those of more commonly recognised basin-floor lobe deposits, thereby enabling the establishment of recognition criteria for intraslope lobe deposits in other less well exposed and studied fine-grained systems. Compared to basin floor lobes, intraslope lobes are smaller volume, influenced by higher degrees of confinement, and tend to show aggradational stacking patterns.

DOI

https://doi.org/10.31223/osf.io/jpbg8

Subjects

Earth Sciences, Physical Sciences and Mathematics, Sedimentology

Keywords

submarine slope, Karoo Basin, Facies stacking pattern, Facies variability, Intraslope lobes, Slope topography

Dates

Published: 2017-10-31 14:01

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License

Academic Free License (AFL) 3.0

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