Dwyka Group

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Dwyka Group
Stratigraphic range: Late Carboniferous-Early Permian
~317–288  Ma
Type Geologic group
Sub-units Mbizane, Elandsvlei & Tshidzi Formations
Underlies Ecca Group
Overlies Cape Supergroup, Natal Supergroup, Namaqua-Natal Province, Archean basement rocks
Lithology
Primary Diamictite, tillite, claystone, mudstone
Other Quartzite, sandstone shale
Location
Coordinates 26°00′S29°30′E / 26.0°S 29.5°E / -26.0; 29.5
Approximate paleocoordinates 76°12′S52°12′W / 76.2°S 52.2°W / -76.2; -52.2
Region Western, Northern Cape, Free State, North-West, Limpopo, Eastern Cape, and KwaZulu-Natal
CountryFlag of South Africa.svg  South Africa
Flag of Namibia.svg  Namibia
Flag of Botswana.svg  Botswana
Flag of Zimbabwe.svg  Zimbabwe
Type section
Named forDwyka
Geology of Karoo Supergroup.png
A simplified geological map of the outcrops of Karoo Supergroup rocks in Southern Africa. The Dwyka Group deposits are represented by the red key on the map

The Dwyka Group is one of four geological groups that compose the Karoo Supergroup. It is the lowermost geological group and heralds the commencement of sedimentation of the Karoo Supergroup. Based on stratigraphic position, lithostratigraphic correlation and palynological analyses, these lowermost Karoo strata range between the Late Carboniferous (Pennsylvanian) to Early Permian in age. [1] [2] [3] [4]

Contents

Background

At the commencement of the deposition of the Dwyka Group, it is thought that the development of the Karoo supergroup foreland system had begun approximately 30 million years prior. This foreland system was caused by crustal uplift that had previously begun to take course due to the subduction of the Palaeo-pacific plate beneath the Gondwanan plate. This resulted in the rise of the Gondwanide mountain range in what is known as the Gondwanide orogeny. The continuation of the orogenic pulses from the growing Gondwanides mountain chain and associated subduction created accommodation space for sedimentation in the Karoo Basin which ran along an east to west trending foreland trough. The formation of the Karoo Basin resulted in the preservation of the Dwyka Group rocks and all succeeding rocks that make up the greater Karoo Supergroup. Southern Africa at this time was part of the supercontinent, Gondwana, and was positioned over the antarctic circle at this time. The result was the development of the Permo-Carboniferous glacial environment where massive ice sheets entombed the early Karoo Basin in the surrounding highlands and permanent, floating glaciers in the lowlands. [5] [6] [7] [8] [9] [10]

Caption: 1-South-America 2-Africa; 3-India; 4-Australia; 5-Antarctica; 6-Fossil remains of Cynognathus, a Triassic land reptile, approximately 3m long; 7- Fossil remains of the freshwater reptile Mesosaurus; 8-Fossil of the fern Glossopteris found in all of the southern continents show that they were once joined; 9-Fossil evidence of the Triassic land reptile Lystrosaurus Snider-Pellegrini Wegener fossil map-i18n.png
Caption: 1-South-America 2-Africa; 3-India; 4-Australia; 5-Antarctica; 6-Fossil remains of Cynognathus, a Triassic land reptile, approximately 3m long; 7- Fossil remains of the freshwater reptile Mesosaurus; 8-Fossil of the fern Glossopteris found in all of the southern continents show that they were once joined; 9-Fossil evidence of the Triassic land reptile Lystrosaurus

Geographic extent

The geological formations of the Dwyka Group are restricted to the edges of the Karoo Basin and achieve their greatest thickness in its southern deposits at approximately 800m, progressively thinning out towards the north. In the south outcrops and exposures are known from Prince Albert, Matjiesfontein, Laingsburg, Sutherland, and as far south as Worcester. Western to northern exposures are known from Calvinia, Carnarvon, Kimberley, and then from Vryheid and Durban in the east.

Dwyka Group deposits are also found outside of and north of the Karoo Basin. These deposits found north of the Karoo Basin are found as the lowermost geological formation of the Springbok Flats, Tshipise, northern Lebombo, Tuli, and Ellisras (Lephalale) Basins of north-northeastern South Africa.

In its southern, western, and eastern deposits, the Dwyka Group conformably overlies rocks of the Cape Supergroup, which includes the Cape Fold Belt, and the Natal Supergroup. It also unconformably overlies the Namaqua-Natal Metamorphic Province in some localities in the west-northwest of South Africa. Its north and northeastern Karoo Basin deposits and all deposits found north of the Karoo Basin unconformably overlie the Transvaal Supergroup, Ventersdorp Group, or Archean and Proterozoic basement rocks. In all South African localities, the Dwyka Group underlies rocks of the Ecca Group.

The geographical range of the Dwyka Group is large with its deposits also being found in other localities in southern Africa. Dwyka-aged deposits that are considered to correlate in age to those found in South Africa have been located in the southern Karasburg and Kalahari Basins of southern Namibia – in and around the Fish River Canyon – in the Huab Basin of northern-western Namibia, the Waterberg and Owambo Basins of northern Namibia, the Dukwi Formation of the Kalahari Basin of Botswana, and the Save Basin of southeastern Zimbabwe. [11]

Stratigraphic units

The Dwyka Group deposits have been categorized by those found as part of the Karoo Basin and smaller formations found in different basins north of the Karoo Basin. In the Karoo Basin, the Dwyka Group is known by two distinctive lithological facies. These two facies are represented in its northern and southern deposits respectively and are recognized as the two geological formations below:

Greenish laminated siltstones of the Elandsvlei Fm, Dwyka Group, near Laingsburg, RSA, containing a solitary pebble which was apparently a dropstone, with thinned laminae draped over the top. Drop pebble in varves of the Elandsvlei Fm, Dwyka Group, near Laingsburg, RSA.jpg
Greenish laminated siltstones of the Elandsvlei Fm, Dwyka Group, near Laingsburg, RSA, containing a solitary pebble which was apparently a dropstone, with thinned laminae draped over the top.

The diamictites are highly compacted and overlie stratified diamictites and mudrocks. The southern facies is interpreted as suspension or melt-out deposits that were deposited in low energy subglacial or subaqueous rain-out from either semi-grounded or floating ice sheets. All sedimentation occurred below the water surface in a deep marine environment. More evidence to support this is that turbidites are often found in Elandsvlei Formation deposits. [12] [13]

North of the Karoo Basin outcrops of another geological formation that correlates in age to the main Karoo Basin's Dwyka-aged deposits. This formation is the lowermost unit of the Springbok Flats, Tshipise, northern Lebombo, Tuli, and Ellisras (Lephalale) Basins. This geological formation is recognized and differentiated below due to its unique lithological facies from its main Karoo Basin counterparts: [20] [21] [22]

Paleontology

The Dwyka Group is mainly known for petrified wood which increase in species diversity in the younger sequences. [24] [25] The cold, glacial environment that the sedimentary rocks of the Dwyka Group were deposited in was not conducive for high plant diversity. Fossil wood species identified include lycopods, especially from the Karasburg, Kalahari, and Huab Basins in Namibia. Glossopteris leaf impressions, the petrified remains of Dadoxylon , coprolites, fossil pollen, and trace fossils of bony fishes, crustaceans, and other arthropods have been found from the Dwyka Group and correlated geological formations from other basins. [26] [27] [28] [29] [30]

See also

Related Research Articles

<span class="mw-page-title-main">Late Paleozoic icehouse</span> Ice age

The late Paleozoic icehouse, also known as the Late Paleozoic Ice Age (LPIA) and formerly known as the Karoo ice age, was an ice age that began in the Late Devonian and ended in the Late Permian, occurring from 360 to 255 million years ago (Mya), and large land-based ice-sheets were then present on Earth's surface. It was the second major icehouse period of the Phanerozoic. It is named after the tillite found in the Karoo Basin of western South Africa, where evidence for the ice age was first clearly identified in the 19th century.

<span class="mw-page-title-main">Karoo Supergroup</span> Widespread Mesozoic stratigraphic unit in southern Africa

The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a period of about 120 million years.

<span class="mw-page-title-main">Beaufort Group</span> Third of the main subdivisions of the Karoo Supergroup in South Africa

The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably underlies the Stormberg Group. Based on stratigraphic position, lithostratigraphic and biostratigraphic correlations, palynological analyses, and other means of geological dating, the Beaufort Group rocks are considered to range between Middle Permian (Wordian) to Early Triassic (Anisian) in age.

<span class="mw-page-title-main">Cape Fold Belt</span> Late Paleozoic fold and thrust belt in southwestern South Africa

The Cape Fold Belt is a fold and thrust belt of late Paleozoic age, which affected the sequence of sedimentary rock layers of the Cape Supergroup in the southwestern corner of South Africa. It was originally continuous with the Ventana Mountains near Bahía Blanca in Argentina, the Pensacola Mountains, the Ellsworth Mountains and the Hunter-Bowen orogeny in eastern Australia. The rocks involved are generally sandstones and shales, with the shales persisting in the valley floors while the erosion resistant sandstones form the parallel ranges, the Cape Fold Mountains, which reach a maximum height of 2325 m at Seweweekspoortpiek.

<i>Daptocephalus</i> Assemblage Zone

The Daptocephalus Assemblage Zone is a tetrapod assemblage zone or biozone found in the Adelaide Subgroup of the Beaufort Group, a majorly fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. This biozone has outcrops located in the upper Teekloof Formation west of 24°E, the majority of the Balfour Formation east of 24°E, and the Normandien Formation in the north. It has numerous localities which are spread out from Colesberg in the Northern Cape, Graaff-Reniet to Mthatha in the Eastern Cape, and from Bloemfontein to Harrismith in the Free State. The Daptocephalus Assemblage Zone is one of eight biozones found in the Beaufort Group and is considered Late Permian (Lopingian) in age. Its contact with the overlying Lystrosaurus Assemblage Zone marks the Permian-Triassic boundary.

<i>Pristerognathus</i> Assemblage Zone

The Pristerognathus Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the upper Abrahamskraal Formation and lowermost Teekloof Formation, Adelaide Subgroup of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. The thickest outcrops, reaching not more than 300 metres (980 ft), occur just east of Sutherland through to Beaufort West in the south and Victoria West in the north. Exposures are also found west of Colesberg and south of Graaff-Reinet. The Pristerognathus Assemblage Zone is the third biozone of the Beaufort Group.

<i>Tropidostoma</i> Assemblage Zone

The Tropidostoma Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the lower Teekloof Formation, Adelaide Subgroup of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. The thickest outcrops, reaching approximately 240 metres (790 ft), occur from east of Sutherland through to Beaufort West and Victoria West, to areas south of Graaff-Reinet. Its northernmost exposures occur west/north-west of Colesberg. The Tropidostoma Assemblage Zone is the fourth biozone of the Beaufort Group.

<i>Eodicynodon</i> Assemblage Zone

The Eodicynodon Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the Abrahamskraal Formation, Adelaide Subgroup of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. The thickest outcrops, reaching approximately 620 metres (2,030 ft), occur south-east of Sutherland, north of Prince Albert, and south-east of Beaufort West. The Eodicynodon Assemblage Zone is the lowermost biozone of the Beaufort Group.

<span class="mw-page-title-main">Ecca Group</span> Second of the main subdivisions of the Karoo Supergroup of geological strata in southern Africa

The Ecca Group is the second of the main subdivisions of the Karoo Supergroup of geological strata in southern Africa. It mainly follows conformably after the Dwyka Group in some sections, but in some localities overlying unconformably over much older basement rocks. It underlies the Beaufort Group in all known outcrops and exposures. Based on stratigraphic position, lithostratigraphic correlation, palynological analyses, and other means of geological dating, the Ecca Group ranges between Early to earliest Middle Permian in age.

<span class="mw-page-title-main">Clarens Formation</span> Geological formation of the Stormberg Group in southern Africa

The Clarens Formation is a geological formation found in several localities in Lesotho and in the Free State, KwaZulu-Natal, and Eastern Cape provinces in South Africa. It is the uppermost of the three formations found in the Stormberg Group of the greater Karoo Supergroup rocks and represents the final phase of preserved sedimentation of the Karoo Basin.

<span class="mw-page-title-main">Molteno Formation</span> Triassic geological formation in the Stormberg Group in Lesotho and South Africa

The Molteno Formation is a geological formation found in several localities in Lesotho and South Africa. It lies mainly south of Maseru, near Burgersdorp, Aliwal North, Dordrecht, Molteno, and Elliot. It extends as far north as Matatiele in the Eastern Cape. The formation's localities lie along the Drakensberg Mountains in Kwazulu-Natal, and near Ladybrand in the Free State of South Africa. The Molteno Formation is the lowermost of the three formations in the Stormberg Group of the greater Karoo Supergroup. The Molteno Formation represents the initial phase of preserved sedimentation of the Stormberg Group.

<span class="mw-page-title-main">Stormberg Group</span> Triassic/Jurassic geological group in the Karoo Supergroup in South Africa

The Stormberg Group is one of the four geological groups that comprises the Karoo Supergroup in South Africa. It is the uppermost geological group representing the final phase of preserved sedimentation of the Karoo Basin. The Stormberg Group rocks are considered to range between Lower Triassic (Olenekian) to Lower Jurassic (Pliensbachian) in age. These estimates are based on means of geological dating including stratigraphic position, lithostratigraphic and biostratigraphic correlations, and palynological analyses.

<span class="mw-page-title-main">Abrahamskraal Formation</span> Geological formation of the Beaufort Group in South Africa

The Abrahamskraal Formation is a geological formation and is found in numerous localities in the Northern Cape, Western Cape, and the Eastern Cape of South Africa. It is the lowermost formation of the Adelaide Subgroup of the Beaufort Group, a major geological group that forms part of the greater Karoo Supergroup. It represents the first fully terrestrial geological deposits of the Karoo Basin. Outcrops of the Abrahamskraal Formation are found from the small town Middelpos in its westernmost localities, then around Sutherland, the Moordenaarskaroo north of Laingsburg, Williston, Fraserburg, Leeu-Gamka, Loxton, and Victoria West in the Western Cape and Northern Cape. In the Eastern Cape outcrops are known from Rietbron, north of Klipplaat and Grahamstown, and also southwest of East London.

The Escarpment Grit is a Triassic geologic formation. It is also referred to as the Nyoka Grit.

<span class="mw-page-title-main">Lower Karoo Group</span>

The Lower Karoo Group is a sequence of late Carboniferous and Permian sandstone sedimentary rocks of the Karoo Supergroup, found in Botswana, Zambia, Zimbabwe, and Mozambique.

The Ellisras Basin is a geological basin that spans the border between South Africa and Botswana, extending west from the town of Lephalale in Limpopo province. Basin fill consists of sedimentary rocks of the Karoo Supergroup, with maximum thickness of 1,500 metres (4,900 ft).

<span class="mw-page-title-main">Balfour Formation</span> Geological formation in the Beaufort Group of South Africa

The Balfour Formation is a geological formation that is found in the Beaufort Group, a major geological group that forms part of the greater Karoo Supergroup in South Africa. The Balfour Formation is the uppermost formation of the Adelaide Subgroup which contains all the Late Permian-aged biozones of the Beaufort Group. Outcrops and exposures of the Balfour Formation are found from east of 24 degrees in the highest mountainous escarpments between Beaufort West and Fraserburg, but most notably in the Winterberg and Sneeuberg mountain ranges near Cradock, the Baviaanskloof river valley, Graaff-Reniet and Nieu Bethesda in the Eastern Cape, and in the southern Free State province.

<span class="mw-page-title-main">Katberg Formation</span> Geological formation in the Beaufort Group of the Karoo Supergroup in South Africa

The Katberg Formation is a geological formation that is found in the Beaufort Group, a major geological group that forms part of the greater Karoo Supergroup in South Africa. The Katberg Formation is the lowermost geological formation of the Tarkastad Subgroup which contains the Lower to Middle Triassic-aged rocks of the Beaufort Group. Outcrops and exposures of the Katberg Formation are found east of 24 degrees on wards and north of Graaff-Reniet, Nieu Bethesda, Cradock, Fort Beaufort, Queensdown, and East London in the south, and ranges as far north as Harrismith in deposits that form a ring around the Drakensberg mountain ranges.

<span class="mw-page-title-main">Middleton Formation</span> Late middle Permian geological formation in the Eastern Cape

The Middleton Formation is a geological formation that extends through the Northern Cape, Western Cape, and Eastern Cape provinces of South Africa. It overlies the lower Abrahamskraal Formation, and is the eastern correlate, East of 24ºE, of the Teekloof Formation. Outcrops and exposures of the Middleton Formation range from Graaff-Reinet in the Eastern Cape onwards. The Middleton Formation's type locality lies near the small hamlet, Middleton, approximately 25 km south of Cookhouse. Other exposures lie in hillsides along the Great Fish River in the Eastern Cape. The Middleton Formation forms part of the Adelaide Subgroup of the Beaufort Group, which itself forms part of the Karoo Supergroup.

<span class="mw-page-title-main">Teekloof Formation</span> Late Permian geological formation that forms part of the Beaufort Group of South Africa

The Teekloof Formation is a geological formation that forms part of the Beaufort Group, one of the five geological groups that comprises the Karoo Supergroup in South Africa. The Teekloof Formation is the uppermost formation of Adelaide Subgroup deposits West of 24ºE and contains Middle to Late Permian-aged deposits and four biozones of the Beaufort Group. It overlies the Abrahamskraal Formation. The Teekloof Formation does not underlie other units other than the younger Karoo dolerites and sills that relate to the emplacement of the Early Jurassic Drakensberg Group to the east. Outcrops and exposures of the Teekloof Formation range from Sutherland through the mountain escarpments between Fraserburg and Beaufort West. The northernmost localities of the Teekloof Formation are found by Loxton, Victoria West and Richmond.

References

  1. ↑ Visser, J.N.J. (1986). "Lateral lithofacies relationships in the glacigene Dwyka Formation in the western and central parts of the Karoo Basin". Transactions of the Geological Society of South Africa. 89: 373–383.
  2. ↑ Isbell, John L., Douglas I. Cole, and Octavian Catuneanu. "Carboniferous-Permian glaciation in the main Karoo Basin, South Africa: Stratigraphy, depositional controls, and glacial dynamics." In Resolving the Late Paleozoic ice age in time and space, vol. 441, pp. 71–82. Geological Society of America Special Paper, 2008. Link: https://www.researchgate.net/profile/John_Isbell/publication/235926635_Carboniferous-Permian_glaciation_in_the_main_Karoo_Basin_South_Africa_Stratigraphy_depositional_controls_and_glacial_dynamics/links/00463514485423265a000000/Carboniferous-Permian-glaciation-in-the-main-Karoo-Basin-South-Africa-Stratigraphy-depositional-controls-and-glacial-dynamics.pdf
  3. ↑ Smith, R.M.H., Eriksson, P.G., Botha, W.J. (1993-01-01). "A review of the stratigraphy and sedimentary environments of the Karoo-aged basins of Southern Africa". Journal of African Earth Sciences (and the Middle East). 16 (1–2): 143–169. Bibcode:1993JAfES..16..143S. doi:10.1016/0899-5362(93)90164-L. ISSN   0899-5362.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. ↑ Bamford, M. K. (2004-01-01). "Diversity of the Woody Vegetation of Gondwanan Southern Africa". Gondwana Research. 7 (1): 153–164. Bibcode:2004GondR...7..153B. doi:10.1016/S1342-937X(05)70314-2. ISSN   1342-937X.
  5. ↑ Thomas, R.J.; von Veh, M.W.; McCourt, S. (1993-01-01). "The tectonic evolution of southern Africa: an overview". Journal of African Earth Sciences (and the Middle East). 16 (1–2): 5–24. Bibcode:1993JAfES..16....5T. doi:10.1016/0899-5362(93)90159-N. ISSN   0899-5362.
  6. ↑ Catuneanu, O.; Hancox, P.J.; Rubidge, B.S. (1998-12-01). "Reciprocal flexural behaviour and contrasting stratigraphies: a new basin development model for the Karoo retroarc foreland system, South Africa". Basin Research. 10 (4): 417. Bibcode:1998BasR...10..417C. doi:10.1046/j.1365-2117.1998.00078.x. ISSN   1365-2117. S2CID   56420970.
  7. ↑ O. Catuneanu, P.J. Hancox and B.S. Rubidge (2002-11-01). "Foredeep submarine fans and forebulge deltas: orogenic off-loading in the underfilled Karoo Basin". Journal of African Earth Sciences. 35 (4): 489–502. Bibcode:2002JAfES..35..489C. doi:10.1016/S0899-5362(02)00154-9. ISSN   1464-343X.
  8. ↑ Catuneanu, Octavian (2004). "Basement control on flexural profiles and the distribution of foreland facies: The Dwyka Group of the Karoo Basin, South Africa". Geology. 32 (6): 517. Bibcode:2004Geo....32..517C. doi:10.1130/G20526.1. ISSN   0091-7613.
  9. ↑ Visser, J.N.J. (1989-05-01). "The Permo-Carboniferous Dwyka Formation of Southern Africa: Deposition by a predominantly subpolar marine ice sheet". Palaeogeography, Palaeoclimatology, Palaeoecology. 70 (4): 377–391. Bibcode:1989PPP....70..377V. doi:10.1016/0031-0182(89)90115-6. ISSN   0031-0182.
  10. ↑ Thomas, R.J., Marshall, C.G.A., Du Plessis, A., Fitch, F.J., Miller, J.A., Von Brunn, V. and Watkeys, M.K., 1992. Geological studies in southern Natal and Transkei: implications for the Cape Orogen. Inversion Tectonics of the Cape Fold Belt, Karoo and Cretaceous Basins of Southern Africa. Balkema, Rotterdam, pp.229–236. Link: https://www.researchgate.net/profile/Bob_Thomas4/publication/290693065_Geological_studies_in_southern_Natal_and_Transkei_implications_for_the_Cape_Orogen/links/5772141e08ae6219474a6519.pdf
  11. ↑ Bangert, Berthold; Stollhofen, Harald; Lorenz, Volker; Armstrong, Richard (1999-07-01). "The geochronology and significance of ash-fall tuffs in the glaciogenic Carboniferous-Permian Dwyka Group of Namibia and South Africa". Journal of African Earth Sciences. 29 (1): 33–49. Bibcode:1999JAfES..29...33B. doi:10.1016/S0899-5362(99)00078-0. ISSN   1464-343X.
  12. ↑ Theron, J.N. and Blignault, H.J., 1975. A model for the sedimentation of the Dwyka glacials in the southwestern Cape. Gondwana Geology, pp.347–356.
  13. ↑ Visser, Johan N.J.; Young, Grant M. (1990-12-01). "Major element geochemistry and paleoclimatology of the Permo-Carboniferous glacigene Dwyka Formation and postglacial mudrocks in southern Africa". Palaeogeography, Palaeoclimatology, Palaeoecology. 81 (1–2): 49–57. Bibcode:1990PPP....81...49V. doi:10.1016/0031-0182(90)90039-A. ISSN   0031-0182.
  14. ↑ Von Brunn, V. and Visser, J.N.J., 1999. Lithostratigraphy of the Mbizane Formation (Dwyka group). South African Committee for Stratigraphy. Lithostratigraphic Series, (32), p.10.
  15. ↑ Huber, Heinz; Koeberl, Christian; McDonald, Iain; Reimold, Wolf Uwe (2001-06-15). "Geochemistry and petrology of Witwatersrand and Dwyka diamictites from South Africa: search for an extraterrestrial component". Geochimica et Cosmochimica Acta. 65 (12): 2007–2016. Bibcode:2001GeCoA..65.2007H. doi:10.1016/S0016-7037(01)00569-5. ISSN   0016-7037.
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  18. ↑ Brunn, V. von; Marshall, C. G. A. (1989-12-01). "Glaciated surfaces and the base of the Dwyka Formation near Pietermaritzburg, Natal". South African Journal of Geology. 92 (4). ISSN   1012-0750.
  19. ↑ Berthold, Bangert (2000). Tephrostratigraphy, petrography, geochemistry, age and fossil record of the Ganigobis Shale Member and associated glaciomarine deposits of the Dwyka Group, Late Carboniferous, southern Africa (Thesis). Universität Würzburg.
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  21. ↑ von Brunn, V. (1996-10-01). "The Dwyka Group in the northern part of Kwazulu/Natal, South Africa: sedimentation during late Palaeozoic deglaciation". Palaeogeography, Palaeoclimatology, Palaeoecology. 125 (1–4): 141–163. Bibcode:1996PPP...125..141V. doi:10.1016/S0031-0182(96)00028-4. ISSN   0031-0182.
  22. ↑ Von Brunn, V. (1994), "Glaciogenic deposits of the Permo-Carboniferous Dwyka Group in the eastern region of the Karoo Basin, South Africa", Earth's Glacial Record, Cambridge University Press, pp. 60–69, doi:10.1017/CBO9780511628900.005, ISBN   9780511628900 , retrieved 2018-11-23
  23. ↑ Bordy, E.M. (2018-03-01). "Lithostratigraphy of the Tshidzi Formation (Dwyka Group, Karoo Supergroup), South Africa". South African Journal of Geology. 121 (1): 109–118. doi:10.25131/sajg.121.0008. ISSN   1996-8590.
  24. ↑ Bamford, M. K. (2000-07-01). "Fossil woods of Karoo age deposits in South Africa and Namibia as an aid to biostratigraphical correlation". Journal of African Earth Sciences. 31 (1): 119–132. Bibcode:2000JAfES..31..119B. doi:10.1016/S0899-5362(00)00077-4. ISSN   1464-343X.
  25. ↑ Bamford, Marion K. (2004-01-01). "Diversity of the Woody Vegetation of Gondwanan Southern Africa". Gondwana Research. 7 (1): 153–164. Bibcode:2004GondR...7..153B. doi:10.1016/S1342-937X(05)70314-2. ISSN   1342-937X.
  26. ↑ R., McLachlan, I.; Ann, Anderson (1973). "A REVIEW OF THE EVIDENCE FOR MARINE CONDITIONS IN SOUTHERN AFRICA DURING DWYKA TIMES". Palaeontologia Africana. ISSN   0078-8554. Archived from the original on 2018-11-24. Retrieved 2018-11-23.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  27. ↑ Barbolini, N., Bamford, M.K. (2014-12-01). "Palynology of an Early Permian coal seam from the Karoo Supergroup of Botswana". Journal of African Earth Sciences. 100: 136–144. Bibcode:2014JAfES.100..136B. doi:10.1016/j.jafrearsci.2014.06.008. ISSN   1464-343X.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  28. ↑ Bangert, B; Bamford, Marion (2001-01-01). "Carboniferous pycnoxylic woods from the Dwyka group of Southern Namibia". Palaeontologia Africana: 13–23.
  29. ↑ Scheffler, K.; Hoernes, S.; Schwark, L. (2003). "Global changes during Carboniferous–Permian glaciation of Gondwana: Linking polar and equatorial climate evolution by geochemical proxies". Geology. 31 (7): 605. Bibcode:2003Geo....31..605S. doi:10.1130/0091-7613(2003)031<0605:GCDCGO>2.0.CO;2. ISSN   0091-7613.
  30. ↑ Smith, R.M.H., Eriksson, P.G., Botha, W.J. (1993-01-01). "A review of the stratigraphy and sedimentary environments of the Karoo-aged basins of Southern Africa". Journal of African Earth Sciences (and the Middle East). 16 (1–2): 143–169. Bibcode:1993JAfES..16..143S. doi:10.1016/0899-5362(93)90164-L. ISSN   0899-5362.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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