Lithostratigraphy and depositional environments in the Waterberg-Erongo area, central Namibia, and correlation with the main Karoo Basin, South Africa

1999 ◽  
Vol 29 (1) ◽  
pp. 105-123 ◽  
Author(s):  
Frank Holzförster ◽  
Harald Stollhofen ◽  
Ian G. Stanistreet
Keyword(s):  
South Africa ◽  
Depositional Environments ◽  
Karoo Basin

scholarly journals The origin and 3D architecture of a km-scale deep-water scour-fill: example from the Skoorsteenberg Fm., Karoo Basin, South Africa

2021 ◽  
Author(s):  
Larissa Hansen ◽  
Rachel Healy ◽  
Luz Gomis Cartesio ◽  
David Lee ◽  
David Hodgson ◽  
...  
Keyword(s):  
South Africa ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Large Scale ◽  
Sedimentary Facies ◽  
Depositional Environments ◽  
Sediment Delivery ◽  
Marine Systems ◽  
Karoo Basin ◽  
Erosion Surface

Scours, and scour fields, are common features on the modern seafloor of deep-marine systems, particularly downstream of submarine channels, and in channel-lobe-transitions-zones. High-resolution images of the seafloor have improved the documentation of the large scale, coalescence, and distribution of these scours in deep-marine systems. However, their scale and high aspect ratio mean they can be challenging to identify in outcrop. Here, we document a large-scale, composite erosion surface from the exhumed deep-marine stratigraphy of Unit 5 from the Permian Karoo Basin succession in South Africa, which is interpreted to be present at the end of a submarine channel.This study utilizes 24 sedimentary logs, 2 cored boreholes, and extensive palaeocurrent and thickness data across a 126 km2 study area. Sedimentary facies analysis, thickness variations and correlation panels allowed identification of a lower heterolithic-dominated part (up to 70 m thick) and an upper sandstone-dominated part (10-40 m thick) separated by an extensive erosion surface. The lower part comprises heterolithics with abundant current and sinusoidal ripples, which due to palaeocurrents, thickness trends and adjacent depositional environments is interpreted as the aggradational lobe complex fringes. The base of the upper part comprises 2-3 medium-bedded sandstone beds interpreted as precursor lobes cut by a 3-4 km wide, 1-2 km long, and up to 28 m deep, high aspect ratio (1:100) composite scour surface. The abrupt change from heterolithics to thick-bedded sandstones marks the establishment of a new sediment delivery system, which may have been triggered by an updip channel avulsion. The composite scour and subsequent sandstone fill support a change from erosion- and bypass-dominated flows to depositional flows, which might reflect increasingly sand-rich flows as a new sediment route matured. This study provides a unique outcrop example with 3D stratigraphic control of the record of a new sediment conduit, and development and fill of a large-scale composite scour surface at the channel mouth, providing a rare insight into how scours imaged on seafloor data can be preserved in the rock record.

scholarly journals Sedimentary facies, stratigraphy, and depositional environments of the Ecca Group, Karoo Supergroup in the Eastern Cape Province of South Africa

2021 ◽  
Vol 13 (1) ◽  
pp. 748-781
Author(s):  
Christopher Baiyegunhi ◽  
Kuiwu Liu
Keyword(s):  
South Africa ◽  
Water Depth ◽  
Facies Analysis ◽  
Sedimentary Facies ◽  
Depositional Environments ◽  
Eastern Cape Province ◽  
Eastern Cape ◽  
Borehole Data ◽  
Karoo Basin ◽  
Facies Associations

Abstract The stratigraphy of the Ecca Group has been subdivided into the Prince Albert, Whitehill, Collingham, Ripon, and Fort Brown Formations in the Eastern Cape Province, South Africa. In this article, we present detailed stratigraphic and facies analyses of borehole data and road-cut exposures of the Ecca Group along regional roads R67 (Ecca Pass), R344 (Grahamstown-Adelaide), R350 (Kirkwood-Somerset East), and national roads N2 (Grahamstown-Peddie) and N10 (Paterson-Cookhouse). Facies analysis of the Ecca Group in the study area was performed to deduce their depositional environments. Based on the lithological and facies characteristics, the stratigraphy of the Prince Albert, Whitehill, Collingham, and Fort Brown Formations is now subdivided into two informal members each, while the Ripon Formation is subdivided into three members. A total of twelve lithofacies were identified in the Ecca Group and were further grouped into seven distinct facies associations (FAs), namely: Laminated to thin-bedded black-greyish shale and mudstones (FA 1); Laminated black-greyish shale and interbedded chert (FA 2); Mudstone rhythmite and thin beds of tuff alternation (FA 3); Thin to thick-bedded sandstone and mudstone intercalation (FA 4); Medium to thick-bedded dark-grey shale (FA 5); Alternated thin to medium-bedded sandstone and mudstone (FA 6); and Varved mudstone rhythmite and sandstone intercalation (FA 7). The FAs revealed gradually change of sea-level from deep marine (FA 1, FA 2, FA 3 and FA 4, FA 5, and FA 6) to prodelta environment (FA 7). This implies that the main Karoo Basin was gradually filling up with Ecca sediments, resulting in the gradual shallowing up of the water depth of the depositional basin.

scholarly journals The Origin and 3D Architecture of a Km-Scale Deep-Water Scour-Fill: Example From the Skoorsteenberg Fm, Karoo Basin, South Africa

2021 ◽  
Vol 9 ◽  
Author(s):  
L. A. S. Hansen ◽  
R. S. Healy ◽  
L. Gomis-Cartesio ◽  
D. R. Lee ◽  
D. M. Hodgson ◽  
...  
Keyword(s):  
South Africa ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Large Scale ◽  
Sedimentary Facies ◽  
Depositional Environments ◽  
Sediment Delivery ◽  
Marine Systems ◽  
Karoo Basin ◽  
Erosion Surface

Scours, and scour fields, are common features on the modern seafloor of deep-marine systems, particularly downstream of submarine channels, and in channel-lobe-transition-zones. High-resolution images of the seafloor have improved the documentation of the large scale, coalescence, and distribution of these scours in deep-marine systems. However, their scale and high aspect ratio mean they can be challenging to identify in outcrop. Here, we document a large-scale, composite erosion surface from the exhumed deep-marine stratigraphy of Unit 5 from the Permian Karoo Basin succession in South Africa, which is interpreted to be present at the end of a submarine channel. This study utilizes 24 sedimentary logs, 2 cored boreholes, and extensive palaeocurrent and thickness data across a 126 km2 study area. Sedimentary facies analysis, thickness variations and correlation panels allowed identification of a lower heterolithic-dominated part (up to 70 m thick) and an upper sandstone-dominated part (10–40 m thick) separated by an extensive erosion surface. The lower part comprises heterolithics with abundant current and sinusoidal ripples, which due to palaeocurrents, thickness trends and adjacent depositional environments is interpreted as the aggradational lobe complex fringes. The base of the upper part comprises 2-3 medium-bedded sandstone beds interpreted as precursor lobes cut by a 3–4 km wide, 1–2 km long, and up to 28 m deep, high aspect ratio (1:100) composite scour surface. The abrupt change from heterolithics to thick-bedded sandstones marks the establishment of a new sediment delivery system, which may have been triggered by an updip channel avulsion. The composite scour and subsequent sandstone fill support a change from erosion- and bypass-dominated flows to depositional flows, which might reflect increasingly sand-rich flows as a new sediment route matured. This study provides a unique outcrop example with 3D stratigraphic control of the record of a new sediment conduit, and development and fill of a large-scale composite scour surface at a channel mouth transition zone, providing a rare insight into how scours imaged on seafloor data can be filled and preserved in the rock record.

scholarly journals A Lacustrine Glacier Retreat Sequence from the Permo-Carboniferous Dwyka Formation, Republic of South Africa

1983 ◽  
Vol 29 (103) ◽  
pp. 515-520
Author(s):  
J. N. J. Visser
Keyword(s):  
South Africa ◽  
Lacustrine Sediments ◽  
Glacier Retreat ◽  
Marine Transgression ◽  
Northern Margin ◽  
Valley Fill ◽  
Karoo Basin ◽  
Ice Retreat ◽  
Glacier Advance

Abstract The upper part of a Permo-Carboniferous glacial valley fill along the northern margin of the Karoo Basin includes glacio-lacustrine sediments. During the last glacier advance into the lake, a bedded heterogeneous diamictite facies was deposited and, on glacier retreat, a sequence of deformed siltstones with diamictite lenses and sandstone beds, varved shale and rhythmite shale was laid down. Black carbonaceous mud was deposited during the subsequent marine transgression. According to varve counts, the glacier receded from the valley over a period of 500 to 1 000 years and it is concluded that the overall ice-retreat rate during the Permo-Carboniferous deglaciation was relatively high.

Latest Permian insects from Wapadsberg Pass, southern Karoo Basin, South Africa

2021 ◽  
Author(s):  
Abraham I Pretorius ◽  
Conrad C Labandeira ◽  
André Nel ◽  
Rose Prevec
Keyword(s):  
South Africa ◽  
Karoo Basin
Sign in / Sign up

Export Citation Format

Share Document