earth science

Nama Group

Nama Group is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Nama Group rather than just read about it. In short: The Nama Group is a 125,000 square kilometres (48,000 sq mi) megaregional Ediacaran group of stratigraphic sequences deposited in the Nama foreland basin in central and southern Namibia. The Nama Basin is a peripheral foreland basin, and the Nama Group was deposited in two early basins, the Zaris and Witputs, to the north, while the South African Vanrhynsdorp Group was deposited in the southern third.

Key takeaways

Nama Group belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Nama Group to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Nama Group from memory before moving on to harder problems.

Reference excerpt

The Nama Group is a 125,000 square kilometres (48,000 sq mi) megaregional Ediacaran group of stratigraphic sequences deposited in the Nama foreland basin in central and southern Namibia. The Nama Basin is a peripheral foreland basin, and the Nama Group was deposited in two early basins, the Zaris and Witputs, to the north, while the South African Vanrhynsdorp Group was deposited in the southern third. The Nama Group is made of fluvial and shallow-water marine sediments, both siliciclastic and carbonate. La Tinta Group in Argentina is considered equivalent to Nama Group.

Description

The group extends from the Gariep Belt in the south to outcrops of pre-Damara basement in the north. Thrombolite-stromatolite reefs in the Nama Group are best developed in the Kuibis Subgroup of the Zaris subbasin, and in the Huns platform of the Witputs subbasin. The Nama Group is a series of interbedded shallow marine carbonates and siliciclastics deposited in a storm-dominated ramp setting. "Nama-type preservation" is an Ediacaran type preservation that presents sandstone castings of fossil creatures in which organisms are preserved in three dimensions, within fine-grained beds that were deposited in single storm or mudflow events: an example is Ausia fenestrata. Analysis performed in 2018 on Namacalathus and Cloudina skeletons from the Ediacaran Omkyk Member of the Nama Group demonstrates that both organisms originally produced aragonitic skeletons, which later underwent diagenetic conversion to calcite.

Stratigraphy The Nama Group is subdivided into:

Ages The lower and upper part of the Spitskop Member of the Urusis Formation, Schwarzrand Subgroup, had originally been dated on the basis of zircons to 545.1 ± 1 Ma and 543.3 ± 1 Ma respectively. Recalibration of the Spitskop radiometric data indicates revised dates of 542.68 ± 1.25 Ma (terminal Ediacaran) and 540.61 ± 0.67 Ma (within error of the Ediacaran–Cambrian boundary), respectively. An ash bed from the Hoogland Member towards the base of the Nama Group (Zaris Formation, Kuibus Subgroup) has yielded an age of 547.4 ± 0.3 Ma, in 2018 slightly modified to 547.32 ± 0.31 Ma. The lower part of the Nomtsas Formation has yielded an age of 539.4 ± 1 Ma, in the same year recalibrated to 538.18 ± 1.11 Ma.

Fossil content

Nama-type Ediacaran fossils found in the group include:

Gallery

See also

List of fossiliferous stratigraphic units in Namibia Geology of Namibia Puncoviscana Formation Sierra Bayas Group

References

Bibliography Buatois, Luis A.; Almond, John; Mángano, M. Gabriela; Jensen, Sören; Germs, Gerard J.B. (2018). "Sediment disturbance by Ediacaran bulldozers and the roots of the Cambrian explosion". Scientific Reports. 8 (1) 4514. Bibcode:2018NatSR...8.4514B. doi:10.1038/s41598-018-22859-9. PMC 5852133. PMID 29540817. Crimes, T. Peter; Germs, Gerard J.B. (1982). "Trace Fossils from the Nama Group (Precambrian-Cambrian) of Southwest Africa (Namibia)". Journal of Paleontology. 56 (4): 890–907. JSTOR 1304708. Grotzinger, John P (2000). "Facies and paleoenvironmental setting of Thrombolite-Stromatolite Reefs, Terminal Proterozoic Nama Group (ca. 550-543 Ma), central and southern Namibia" (PDF). Communications of the Geological Survey of Namibia. 12: 251–264. Retrieved 2018-08-25. Meert, Joseph G.; Eide, Elizabeth A.; Torsvik, Trond H. (1997). "The Nama Group revisited" (PDF). Geophysical Journal International. 129 (3): 637–650. Bibcode:1997GeoJI.129..637M. doi:10.1111/j.1365-246X.1997.tb04499.x. Retrieved 2018-08-25. Pruss, Sara B.; Blättler, Clara L.; Macdonald, Francis A.; Higgins, John A. (2018). "Calcium isotope evidence that the earliest metazoan biomineralizers formed aragonite shells". Geology. 46 (9): 763–766. Bibcode:2018Geo....46..763P. doi:10.1130/G45275.1. Winterleitner, G.; Le Heron, D.P.; Mapani, B.; Vining, B.A.; McCaffrey, K.J.W. (2015). "Styles, origins and implications of syndepositional deformation structures in Ediacaran microbial carbonates (Nama Basin, Namibia)". Geological Society, London, Special Publications. 418 (1): 87–109. Bibcode:2015GSLSP.418...87W. doi:10.1144/SP418.12. S2CID 131352816. Retrieved 2018-08-25. Wood, R.; Curtis, A. (2015). "Extensive metazoan reefs from the Ediacaran Nama Group, Namibia: the rise of benthic suspension feeding" (PDF). Geobiology. 13 (2): 112–122. Bibcode:2015Gbio...13..112W. doi:10.1111/gbi.12122. hdl:20.500.11820/5f33c6b7-a2ac-4d1b-9f8d-a0ee6409af28. PMID 25556318. S2CID 904616. Retrieved 2018-08-25.

Further reading 2009 - Cohen, Phoebe A., Alexander Bradley, Andrew H. Knoll, John P. Grotzinger, Soren Jensen, John Abelson, Kevin Hand, Gordon Love, Joannah Metz, Nicola McLoughlin, Patrick Meister, Rebekah Shepard, Mike Tice, and Jonathan P. Wilson - Tubular compression fossils from the Ediacaran Nama Group, Namibia. Journal of Paleontology 83, no. 1: 110-122 M. F. Glaessner. 1979. An echiurid worm from the Late Precambrian. Lethaia 12(2):121-124 D. Grazhdankin and A. Seilacher. 2002. Underground Vendobionta from Namibia. Palaeontology 45(1):57-78 J. P. Grotzinger, W. A. Watters, and A. H. Knoll. 2000. Calcified metazoans in thrombolite-stromatolite reefs of the terminal Proterozoic Nama Group, Namibia. Paleobiology 26(3):334-359 R. J. F. Jenkins. 1985. The enigmatic Ediacaran (Late Precambrian) genus Rangea and related Forms. Paleobiology 11(3):336-355 S. Jensen and B. N. Runnegar. 2005. A complex trace fossil from the Spitskop Member (terminal Ediacaran–? Lower Cambrian) of southern Namibia. Geological Magazine 142(5):561-569 G. M. Narbonne, B. Z. Saylor, and J. P. Grotzinger. 1997. The youngest Ediacaran fossils from southern Africa. Journal of Paleontology 71(6):953-967 J. P. Wilson, J. P. Grotzinger, W. W. Fischer, K. P. Hand, S. Jensen, A. H. Knoll, J. Abelson, J. M. Metz, N. Mcloughlin, P. A. Cohen, and M. M. Tice. 2012. Deep-water incised valley deposits at the Ediacaran-Cambrian boundary in Southern Namibia contain abundant Treptichnus pedum. Palaios 27:252-273 R. A. Wood, J. P. Grotzinger, and J. A. D. Dickson. 2002. Proterozoic Modular Biomineralized Metazoan from the Nama Group, Namibia. Science 296(5577):2383-2386

Illustrations

Worked examples

Example 1 — a first encounter with Nama Group

Start with the simplest possible case. Write down what Nama Group claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Nama Group before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Nama Group ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Nama Group

In research: Nama Group appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Nama Group in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Nama Group is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cambrian System of Africa, Ediacaran Africa, Ediacaran life, so understanding it makes those chapters shorter.
In everyday life: Look for Nama Group outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Nama Group in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Nama Group means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Nama Group out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Nama Group in simple terms?

Why does Nama Group matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Nama Group?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Nama Group.