Lithostratigraphy of the Skoorsteenberg Formation (Ecca Group, Karoo Supergroup), South Africa

2017 ◽  
Vol 120 (3) ◽  
pp. 433-446
Author(s):  
H. de V. Wickens ◽  
D.I. Cole
Keyword(s):  
South Africa ◽  
Deep Water ◽  
Regional Distribution ◽  
Water Systems ◽  
Fine Grained ◽  
Karoo Basin ◽  
Porosity And Permeability ◽  
Basin Floor ◽  
Primary Porosity ◽  
Lower Slope

Abstract The Middle Permian Skoorsteenberg Formation is part of the Ecca Group (Karoo Supergroup) of South Africa. It is also known as the ‘Tanqua fan complex’ due to its origin as a deep-water sedimentation unit associated with a prograding deltaic system. The Skoorsteenberg Formation crops out over approximately 650 km2 along the western margin of the Main Karoo Basin. It thins out in a northerly and easterly direction and therefore has a limited extent with cut-off boundaries to the south and north. It is underlain by the Tierberg Formation and overlain by the Kookfontein Formation, the latter being limited to the regional distribution of the Skoorsteenberg Formation. The Skoorsteenberg Formation has a composite thickness of 400 m and comprises five individual sandstone packages, separated by shale units of similar thickness. The sandstones are very fine- to fine-grained, light greyish to bluish grey when fresh, poorly sorted and lack primary porosity and permeability. The Tanqua fan complex is regarded as one of the world’s best examples of an ancient basin floor to slope fan complex associated with a fluvially dominated deltaic system. It has served as analogue for many deep-water systems around the world and continues to be a most sought after “open-air laboratory” for studying the nature of fine-grained, deep-water sedimentation. The fan systems are essentially tectonically undeformed, outstandingly well exposed and contain an inexhaustible amount of information on the deep-water architecture of lower slope to basin floor turbidite deposits.

Contribution of research borehole data to modelling fine-grained turbidite reservoir analogues, Permian Tanqua–Karoo basin-floor fans (South Africa)

2006 ◽  
Vol 12 (2) ◽  
pp. 175-190 ◽  
Author(s):  
Stefan M. Luthi ◽  
David M. Hodgson ◽  
Cees R. Geel ◽  
Stephen S. Flint ◽  
Jan Willem Goedbloed ◽  
...  
Keyword(s):  
South Africa ◽  
Borehole Data ◽  
Fine Grained ◽  
Karoo Basin ◽  
Basin Floor

Age Controls on the Tanqua and Laingsburg Deep-Water Systems: New Insights on the Evolution and Sedimentary Fill of the Karoo Basin, South Africa

2007 ◽  
Vol 77 (11) ◽  
pp. 901-908 ◽  
Author(s):  
A. Fildani ◽  
N. J. Drinkwater ◽  
A. Weislogel ◽  
T. McHargue ◽  
D. M. Hodgson ◽  
...  
Keyword(s):  
South Africa ◽  
Deep Water ◽  
Water Systems ◽  
Karoo Basin ◽  
Sedimentary Fill

scholarly journals Deep-water channel-lobe transition zone dynamics: Processes and depositional architecture, an example from the Karoo Basin, South Africa

2018 ◽  
Vol 130 (9-10) ◽  
pp. 1723-1746 ◽  
Author(s):  
Hannah L. Brooks ◽  
David M. Hodgson ◽  
Rufus L. Brunt ◽  
Jeff Peakall ◽  
Menno Hofstra ◽  
...  
Keyword(s):  
South Africa ◽  
Transition Zone ◽  
Deep Water ◽  
Water Channel ◽  
Karoo Basin ◽  
Depositional Architecture

Stratigraphic Evolution of Fine-Grained Submarine Fan Systems, Tanqua Depocenter, Karoo Basin, South Africa

2006 ◽  
Vol 76 (1) ◽  
pp. 20-40 ◽  
Author(s):  
D. M. Hodgson ◽  
S. S. Flint ◽  
D. Hodgetts ◽  
N. J. Drinkwater ◽  
E. P. Johannessen ◽  
...  
Keyword(s):  
South Africa ◽  
Submarine Fan ◽  
Fine Grained ◽  
Karoo Basin ◽  
Stratigraphic Evolution

scholarly journals Fringe or background: Characterizing deep-water mudstones beyond the basin-floor fan sandstone pinchout

2020 ◽  
Vol 90 (12) ◽  
pp. 1678-1705
Author(s):  
Kévin Boulesteix ◽  
Miquel Poyatos-Moré ◽  
David M. Hodgson ◽  
Stephen S. Flint ◽  
Kevin G. Taylor
Keyword(s):  
Deep Water ◽  
Turbidity Currents ◽  
Stratigraphic Correlation ◽  
Low Density ◽  
Karoo Basin ◽  
Depositional Processes ◽  
Stratigraphic Architecture ◽  
Sand Supply ◽  
Stacking Pattern ◽  
Basin Floor

ABSTRACT Mud dominates volumetrically the fraction of sediment delivered and deposited in deep-water environments, and mudstone is a major component of basin-floor successions. However, studies of basin-floor deposits have mainly focused on their proximal sandstone-prone part. A consequent bias therefore remains in the understanding of depositional processes and stratigraphic architecture in mudstone-prone distal settings beyond the sandstone pinchouts of basin-floor fans. This study uses macroscopic and microscopic descriptions of over 500 m of continuous cores from research boreholes from the Permian Skoorsteenberg Formation of the Karoo Basin, South Africa, to document the sedimentology, stratigraphy, and ichnology of a distal mudstone-prone basin-floor succession. Very thin- to thin-bedded mudstones, deposited by low-density turbidity currents, stack to form bedsets bounded by thin packages (< 0.7 m thick) of background mudstones. Genetically related bedsets stack to form bedset packages, which are bounded by thicker (> 0.7 m thick) background mudstones. Stratigraphic correlation between cores suggests that bedsets represent the distal fringes of submarine fan lobe elements and/or lobes, and bedset packages represent the distal fringes of lobe complexes and/or lobe complex sets. The internal stacking pattern of bedsets and bedset packages is highly variable vertically and laterally, which records dominantly autogenic processes (e.g., compensational stacking, avulsion of feeder channels). The background mudstones are characterized by remnant tractional structures and outsize particles, and are interpreted as deposited from low-density turbidity currents and debris flows before intense biogenic reworking. These observations challenge the idea that mud accumulates only from hemipelagic suspension fallout in distal basin-floor environments. Thin background mudstones separating bedsets (< 0.7 m thick) are interpreted to mainly represent autogenically driven lobe abandonment due to up-dip channel avulsion. The thicker background mudstones separating bedset packages (> 0.7 m thick) are interpreted to dominantly mark allogenically driven regional decrease of sand supply to the basin floor. The recognition of sandstone-prone basin-floor fans passing into genetically linked distal fringe mudstones suggests that submarine lobes are at least ∼ 20 km longer than previously estimated. This study provides sedimentological, stratigraphic, and ichnological criteria to differentiate mudstones deposited in different sub-environments in distal deep-water basin-floor settings, with implications for the accurate characterization of basin-floor fan architecture, and their use as archives of paleoenvironmental change.

Lithostratigraphy of the Kookfontein Formation (Ecca Group, Karoo Supergroup), South Africa

2017 ◽  
Vol 120 (3) ◽  
pp. 447-458
Author(s):  
H. de V. Wickens ◽  
D.I. Cole
Keyword(s):  
South Africa ◽  
Depositional Environment ◽  
Delta Front ◽  
Southwestern Part ◽  
Fine Grained ◽  
Karoo Basin ◽  
Deformation Features ◽  
Stratigraphic Position ◽  
Shelf Margin ◽  
Upper Slope

Abstract The Permian Kookfontein Formation forms part of the upper Ecca Group in the southwestern part of the main Karoo Basin of South Africa. It occupies a stratigraphic position between the underlying Skoorsteenberg Formation and the overlying Waterford Formation, with its regional extent limited to the cut-off boundaries of the Skoorsteenberg Formation. The Kookfontein Formation has an average thickness of 200 m, coarsens upwards, and predominantly comprises dark grey shale, siltstone and thin- to thick-bedded, fine- to very fine-grained, feldspathic litharenite. Characteristic upward-coarsening and thickening successions and syn-sedimentary deformation features reflect rapid deposition and progradation of a predominantly fluvially-dominated prodelta and delta front slope environment. The upward increase in the abundance of wave–ripple marks further indicates a gradual shallowing of the depositional environment through time. The upper contact with the Waterford Formation is gradational, which indicates a transition from deposition in an unstable upper slope/shelf margin environment to a more stable shelf setting.

Delineation of sandstone reservoirs of Pletmos Basin offshore South Africa into Flow Units using Core Data

2020 ◽  
Vol 123 (4) ◽  
pp. 479-492
Author(s):  
M. Opuwari ◽  
M. Amponsah-Dacosta ◽  
S. Mohammed ◽  
N. Egesi
Keyword(s):  
South Africa ◽  
Gamma Ray ◽  
Rock Type ◽  
Low Flow ◽  
Flow Zone ◽  
Fine Grained ◽  
Rock Types ◽  
Porosity And Permeability ◽  
Sandstone Reservoirs ◽  
Permeability Data

Abstract The present study is focused on the comparison of petrophysical rock typing and zonation methods of the Valanginian age sandstone in the Pletmos Basin offshore South Africa, to produce a zonation scheme for the low-permeability shaly sandstone reservoirs from core porosity and permeability data. The Valanginian age sediments of the Lower Cretaceous consist predominantly of a shallow marine sequence with interbeds of siltstone, claystone, generally fine-grained sandstone, and glauconitic, with varying amounts of an argillaceous matrix. A core description report was used in conjunction with a gamma-ray log to group rock types into different facies based on texture and grain size. Three different facies were identified as facies 1, a moderately sorted fine to medium-grained glauconitic sandstone; facies 2, a fine to very fine-grained glauconitic sandstone, moderately sorted; facies 3, a very fine sandstone to siltstone, laminated, argillaceous and bioturbated. Three independent reservoir zonation methods (Winland r35 pore throat, Hydraulic Flow Unit, and Stratigraphic Modified Lorenz Plot) were applied to three wells (SW1, SW2, and SW3) for which wireline logs, core porosity, and permeability data are available. Results were analyzed and compared with facies used as a context for the identification of rock types and zones. The results revealed eleven zones, grouped as moderate, very-low, and tight zones. The moderate flow zone is the best reservoir quality rock composed of macroporous rock type, ranked, as good rock type associated with facies 1. Three very-low flow zones were identified, which are of a microporous rock type, ranked as poor quality rock, associated with facies 2. Eight tight zones were revealed, which are of nanoporous rock type ranked as an impervious rock. The tight flow zone is the most reduced rock quality associated with facies 3. This study has developed a zonation scheme that will be used to locate other flow zones as well as to investigate whether the units/zones identified extend to other parts of the field.

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