The Nama Group is a megaregional

Vendian The Ediacaran Period ( ) is a geological period that spans 96 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 538.8 Mya. It marks the end of the Proterozoic Eon, and the ...

to Cambrian group of stratigraphic sequences deposited in the Nama foreland basin in central and southern

Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...

. 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 Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...

n 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.Meert et al., 1997, p.639 Thrombolite-

stromatolite Stromatolites () or stromatoliths () are layered sedimentary formations ( microbialite) that are created mainly by photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria). T ...

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.Wood & Curtis, 2015, p.114 "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 ''Namacalathus'' is a problematic metazoan fossil occurring in the latest Ediacaran. The first, and only described species, ''N. hermanastes'', was first described in 2000 from the Nama Group of central and southern Namibia. A U–Pb zircon ag ...

'' 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.Pruss et al., 2018, p.763

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

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of t ...

s 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.Buatois et al., 2018

Fossil content

Nama-type Ediacaran fossils found in the group include: * '' Ausia fenestrata'' * '' Bergaueria'' - Kuibis SubgroupCrimes & Germs, 1982, p.890 * '' Brooksella'' - Schwarzrand Subgroup * '' ?Chondrites'' - Schwarzrand Subgroup * '' Cloudina'' - Zaris Formation * '' ?Diplichnites'' - Nomtsas Formation * '' Neonereites biserialis'', '' N. uniserialis'' - Nomtsas Formation * ''

Diplocraterion ''Diplocraterion'' is an ichnogenus describing vertical U-shaped burrows having a spreite (weblike construction) between the two limbs of the U. The spreite of an individual ''Diplocraterion'' trace can be either protrusive (between the paired ...

'' - Schwarzrand Subgroup * '' Enigmatichnus africani'' - Fish River Subgroup * '' Ernietta'' - Naldaus & Dabis Formations * '' Namacalathus hermanastes'' - Zaris FormationThrombolite Reef, Schwarzrand Subgroup
at Fossilworks.org * '' Namalia villiersiensis'' - Kuibis Quartzite * '' Namapoikia rietoogensis'' - Dabis Formation * '' Nereites'' - Schwarzrand Subgroup * '' Protechiurus edmondsi'' - Kuibis Quartzite & Dabis Formation * '' Pteridinium carolinaense'', '' P. simplex'' - Naldaus & Dabis FormationsVendian fauna, Kuibis Formation, - Glaessner 1979
at Fossilworks.orgFarm Swartpunt
at Fossilworks.org * '' Rangea schneiderhoehni'' - Naldaus & Dabis FormationsNiederhagen Member, Naldaus Fm., - Jenkins 1985
at Fossilworks.orgKliphoek Member, Dabis Fm., - Jenkins 1985
at Fossilworks.org * ''

Skolithos ''Skolithos'' (formerly spelled ''Scolithus'' or ''Skolithus'') is a common trace fossil ichnogenus that is, or was originally, an approximately vertical cylindrical burrow. It is produced by a variety of organisms in shallow marine environmen ...

'' - Fish River & Schwarzrand Subgroups * '' Streptichnus narbonnei'' - Urusis Formation * '' Swartpuntia germsi'' - Urusis Formation * ''

Treptichnus pedum ''Treptichnus'' (formerly named ''Phycodes'', ''Manykodes'' by J. Dzik, and also known as ''Trichophycus''See e.gfossiilid.info: paleodiversity in Baltoscandia: Trichophycus pedum/ref>) is the preserved burrow of an animal. As such, it is regar ...

'' - Nomtsas FormationSonntagsbrunn Farm, Nomtsas Fm., Valley Fill 2, Visionarium
at Fossilworks.org

Gallery

File:Swartpuntiagermsi.png, Reconstruction of '' Swartpuntia germsi'' File:Namacalathus.svg, Reconstruction of '' Namacalathus hermanastes'' File:Cloudina.svg, Reconstruction of '' Cloudina''

References

Bibliography

* * * * * * * {{Cite journal , last=Wood , first=R. , last2=Curtis , first2=A. , year=2015 , title=Extensive metazoan reefs from the Ediacaran Nama Group, Namibia: the rise of benthic suspension feeding , url=https://www.geos.ed.ac.uk/homes/acurtis/Wood_Curtis_2015.pdf , journal=

Geobiology Geobiology is a field of scientific research that explores the interactions between the physical Earth and the biosphere. It is a relatively young field, and its borders are fluid. There is considerable overlap with the fields of ecology, evolutio ...

, volume=13 , issue=2 , pages=112–122 , access-date=2018-08-25, doi=10.1111/gbi.12122 , pmid=25556318 , hdl=20.500.11820/5f33c6b7-a2ac-4d1b-9f8d-a0ee6409af28 , hdl-access=free

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 Geologic groups of Africa Geologic formations of Namibia Cambrian System of Africa Ediacaran Africa Sandstone formations Siltstone formations Mudstone formations Limestone formations Fluvial deposits Reef deposits Paleontology in Namibia Ediacaran life Omaheke Region Hardap Region Geography of ǁKaras Region