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VAALBARA was an Archean supercontinent consisting of the Kaapvaal Craton (now located in eastern South Africa
South Africa
) and the Pilbara Craton (now found in north-western Western Australia
Western Australia
). E.S. Cheney derived the name from the last four letters of each craton's name. The two cratons consist of crust dating from 2.7 to 3.6 Gya , which would make Vaalbara
Vaalbara
Earth
Earth
's earliest supercontinent.

CONTENTS

* 1 Existence and lifespan * 2 Evidence for Vaalbara
Vaalbara
* 3 Origin of life * 4 See also

* 5 References

* 5.1 Notes * 5.2 Sources

EXISTENCE AND LIFESPAN

Life timeline view • discuss • edit -4500 — – -4000 — – -3500 — – -3000 — – -2500 — – -2000 — – -1500 — – -1000 — – -500 — – 0 — WATER Single-celled life PHOTOSYNTHESIS EUKARYOTES Multicellular life LAND LIFE DINOSAURS MAMMALS FLOWERS ← Earliest Earth
Earth
(−4540 ) ← Earliest water ← Earliest life ← LHB meteorites ← Earliest oxygen ← Atmospheric oxygen ← Oxygen crisis ← Earliest sexual reproduction ← Ediacara biota ← Cambrian explosion ← Earliest humans P h a n e r o z o i c

P r o t e r o z o i c

A r c h e a n H a d e a n Pongola Huronian Cryogenian Andean Karoo Quaternary Axis scale : millions of years . Orange labels: known ICE AGES. Also see: Human
Human
timeline and Nature timeline

There has been some debate as to when and whether Vaalbara
Vaalbara
existed.

An Archaean-Palaeoproterozoic (2.8–2.1 Ga) link between South Africa
Africa
and Western Australia
Western Australia
was first proposed by Button 1976 . He found a wide range of similarities between the Transvaal Basin in South Africa
South Africa
and the Hamersley Basin
Hamersley Basin
in Australia. Button, however, placed Madagascar between Africa
Africa
and Australia and concluded that Gondwana must have had a long stable tectonic history. Similarly, in the reconstruction of Rogers 1993 , 1996 the oldest continent is Ur . In Rogers' reconstructions, however, Kaapvaal and Pilbara are placed far apart already in their Gondwana configuration, a reconstruction contradicted by later orogenic events and incompatible with the Vaalbara
Vaalbara
hypothesis.

Cheney 1996 , nevertheless, found a three-fold stratigraphic similarity and proposed that the two cratons once formed a continent which he named Vaalbara. This model is supported by the palaeomagnetic data of Zegers, de Wit ">3,870 million years the two cratons could have been part of the same supercontinent. Both the Pilbara and Kaapvaal cratons show extensional faults which were active about 3,470 million years ago during felsic volcanism and coeval with the impact layers.

ORIGIN OF LIFE

See also: Abiogenesis

The Pilbara and Kaapvaal cratons are some of the oldest rocks in the world and they contain well-preserved Archaean microfossils. A series of international drilling projects has revealed traces of microbial life and photosynthesis from the Archaean in both Africa
Africa
and Australia. The oldest widely accepted evidence of photosynthesis by early life forms is molecular fossils found in 2.7 Ga-old shales in the Pilbara Craton. These fossils have been interpreted as traces of eukaryotes and cyanobacteria , though some scientists argue that these biomarkers must have entered these rocks later and date the fossils to 2.15–1.68 Ga. This later time span agrees with estimates based on molecular clocks which dates the eukaryote last common ancestor at 1866–1679 Ma. If the Pilbara fossils are traces of early eukaryotes, they could represent groups that went extinct before modern groups emerged.

SEE ALSO

* Columbia (supercontinent) * Ur (continent)

REFERENCES

NOTES

* ^ Zegers, de Wit for Button's reconstruction see fig. 20f, p. 286 * ^ de Kock, Evans & Beukes 2009 , Introduction, pp. 145–146 * ^ Zhao et al. 2004 , pp. 96–98 * ^ Strik et al. 2003 , Implications for the Vaalbara
Vaalbara
Hypothesis, pp. 19–20, fig. 11 * ^ Nelson, Trendall & Altermann 1999 , Independent development of the Pilbara and Kaapvaal cratons — implications, pp. 186–187 * ^ Smirnov et al. 2013 , Abstract * ^ Marschall et al. 2010 , Geology of the Grunehogna Craton, pp. 2278–2280 * ^ Marschall et al. 2010 , Conclusions, p. 2298 * ^ A B Zegers, de Wit & White 1998 , Discussion, pp. 255–257 * ^ Wingate 1998 , Abstract * ^ Biggin et al. 2011 , p. 326 * ^ de Kock 2008 , p. VII * ^ Byerly et al. 2002 , Abstract * ^ Nitescu, Cruden & Bailey 2006 , Fig. 1, p. 2 * ^ A B C Erickson 1993 , p. 27 * ^ Lowe & Byerly 1986 , p. 83 * ^ A B C Zegers Waldbauer et al. 2009 , Conclusions, p. 45 * ^ Rasmussen et al. 2008 , p. 1101 * ^ Parfrey et al. 2011 , Discussion, p. 13626

SOURCES

* Biggin, A. J.; de Wit, M. J.; Langereis, C. G.; Zegers, T. E.; Voûte, S.; Dekkers, M. J.; Drost, K. (2011). "Palaeomagnetism of Archaean rocks of the Onverwacht Group, Barberton Greenstone Belt (southern Africa): Evidence for a stable and potentially reversing geomagnetic field at ca. 3.5 Ga". Earth
Earth
and Planetary Science Letters. 302 (3): 314–328. Bibcode :2011E&PSL.302..314B. doi :10.1016/j.epsl.2010.12.024 . Retrieved 2016-09-12. * Button, A. (1976). "Transvaal and Hamersley basins—review of basin development and mineral deposits" (PDF). Mineral Science Engineering. University of the Witwatersrand, Economic Geology Research Unit, Information Circular 107. 8 (4): 262–293. OCLC 13791945 . Retrieved 2016-09-12. * Byerly, G. R.; Lowe, D. R.; Wooden, J. L.; Xie, X. (2002). "An Archean Impact Layer from the Pilbara and Kaapvaal Cratons". Science. 297 (5585): 1325–1327. Bibcode :2002Sci...297.1325B. PMID 12193781 . doi :10.1126/science.1073934 . Retrieved 2016-09-12. * Cheney, E. S. (1996). "Sequence stratigraphy and plate tectonic significance of the Transvaal succession of southern Africa
Africa
and its equivalent in Western Australia". Precambrian Research. 79 (1–2): 3–24. doi :10.1016/0301-9268(95)00085-2 . * de Kock, M. O. (2008). Paleomagnetism of Selected Neoarchean-Paleoproterozoic Cover Sequences on the Kaapvaal Craton and Implications for Vaalbara
Vaalbara
(Ph.D.). University of Johannesburg. Retrieved 2016-09-12. * de Kock, M. O.; Evans, D. A. D.; Beukes, N. J. (2009). "Validating the existence of Vaalbara
Vaalbara
in the Neoarchean". Precambrian Research. 174 (1): 145–154. doi :10.1016/j.precamres.2009.07.002 . Retrieved 2016-09-12. * Erickson, Jon (1993). Craters, Caverns and Canyons – Delving Beneath the Earth’s Surface. ISBN 0-8160-2590-8 . * Lowe, D. R.; Byerly, G. R. (1986). "Early Archean silicate spherules of probable impact origin, South Africa
South Africa
and Western Australia". Geology. Geological Society of America. 14 (1): 83–86. Bibcode :1986Geo....14...83L. doi :10.1130/0091-7613(1986)142.0.CO;2 . Retrieved 2016-09-12. * Marschall, H. R.; Hawkesworth, C. J.; Storey, C. D.; Dhuime, B.; Leat, P. T.; Meyer, H. P.; Tamm-Buckle, S. (2010). "The Annandagstoppane Granite, East Antarctica: evidence for Archaean intracrustal recycling in the Kaapvaal–Grunehogna Craton from zircon O and Hf isotopes" (PDF). Journal of Petrology. 51 (11): 2277–2301. doi :10.1093/petrology/egq057 . Retrieved May 2016. Check date values in: access-date= (help ) * Nelson, D. R.; Trendall, A. F.; Altermann, W. (1999). "Chronological correlations between the Pilbara and Kaapvaal cratons" (PDF). Precambrian Research. 97 (3): 165–189. doi :10.1016/S0301-9268(99)00031-5 . Retrieved April 2016. Check date values in: access-date= (help ) * Nitescu, B.; Cruden, A. R.; Bailey, R. C. (2006). "Crustal structure and implications for the tectonic evolution of the Archean Western Superior craton from forward and inverse gravity modeling". Tectonics. 25 (TC1009). Bibcode :2006Tecto..25.1009N. doi :10.1029/2004TC001717 . * Parfrey, L. W.; Lahr, D. J.; Knoll, A. H.; Katz, L. A. (2011). "Estimating the timing of early eukaryotic diversification with multigene molecular clocks" (PDF). PNAS . 108 (33): 13624–13629. PMC 3158185  . PMID 21810989 . doi :10.1073/pnas.1110633108 . Retrieved April 2016. Check date values in: access-date= (help ) * Philippot, P.; Van Kranendonk, M.; Van Zuilen, M.; Lepot, K.; Rividi, N.; Teitler, Y.; Thomazo, C.; Blanc-Valleron, M.-M.; Rouchy, J.-M.; Grosch, E.; de Wit, M. (2009). "Early traces of life investigations in drilling Archean hydrothermal and sedimentary rocks of the Pilbara Craton, Western Australia
Western Australia
and Barberton greenstone belt, South Africa". Comptes Rendus Palevol. 8 (7): 649–663. doi :10.1016/j.crpv.2009.06.006 . Retrieved 2016-09-12. * Rasmussen, B.; Fletcher, I. R.; Brocks, J. J.; Kilburn, M. R. (2008). "Reassessing the first appearance of eukaryotes and cyanobacteria" (PDF). Nature. 455 (7216): 1101–1104. PMID 18948954 . doi :10.1038/nature07381 . Retrieved April 2016. Check date values in: access-date= (help ) * Rogers, J. J. (1993). "India and Ur". Geological Society of India. 42 (3): 217–222. Retrieved March 2016. (Subscription required (help)). Check date values in: access-date= (help ) * Rogers, J. J. W. (1996). "A history of continents in the past three billion years". Journal of Geology. 104: 91–107, Chicago. Bibcode :1996JG....104...91R. JSTOR 30068065 . doi :10.1086/629803 . * Smirnov, A. V.; Evans, D. A.; Ernst, R. E.; Söderlund, U.; Li, Z. X. (2013). "Trading partners: tectonic ancestry of southern Africa
Africa
and western Australia, in Archean supercratons Vaalbara
Vaalbara
and Zimgarn" (PDF). Precambrian Research. 224: 11–22. doi :10.1016/j.precamres.2012.09.020 . Retrieved March 2016. Check date values in: access-date= (help ) * Strik, G.; Blake, T. S.; Zegers, T. E.; White, S. H.; Langereis, C. G. (2003). "Palaeomagnetism of flood basalts in the Pilbara Craton, Western Australia: Late Archaean continental drift and the oldest known reversal of the geomagnetic field". Journal of Geophysical Research: Solid Earth. 108 (B12). Bibcode :2003JGRB..108.2551S. doi :10.1029/2003jb002475 . Retrieved 2016-09-12. * Waldbauer, J. R.; Sherman, L. S.; Sumner, D. Y.; Summons, R. E. (2009). "Late Archean molecular fossils from the Transvaal Supergroup record the antiquity of microbial diversity and aerobiosis". Precambrian Research. 169 (1): 28–47. doi :10.1016/j.precamres.2008.10.011 . Retrieved April 2016. Check date values in: access-date= (help ) * Wingate, M. T. D. (1998). "A palaeomagnetic test of the Kaapvaal-Pilbara (Vaalbara) connection at 2.78 Ga". South African Journal of Geology . 101 (4): 257–274. Retrieved 2016-09-12. * Zegers, T. E.; de Wit, M. J.; White, S. H. (1998). "Vaalbara, Earth\'s oldest assembled continent? A combined. structural, geochronological, and palaeomagnetic test" (PDF). Terra Nova. 10 (5): 250–259. doi :10.1046/j.1365-3121.1998.00199.x . Retrieved April 2016. Check date values in: access-date= (help ) * Zegers, T. E.; Ocampo, A. (2003). Vaalbara
Vaalbara
and Tectonic Effects of a Mega Impact in the Early Archean 3470 Ma. Third International Conference on Large Meteorite Impacts. Nordlingen, Germany. Retrieved 2016-09-12. * Zhao, G.; Sun, M.; Wilde, S. A.; Li, S. (2004). "A Paleo-Mesoproterozoic supercontinent: assembly, growth and breakup". Earth-Science Reviews. 67 (1): 91–123. Bibcode :2004ESRv...67...91Z. doi :10.1016/j.earscirev.2004.02.003 . Retrieved 2016-09-12.

* v * t * e

Continents of the world

Africa
Africa

Antarctica
Antarctica

Asia
Asia

Australia

Europe
Europe

North America
North America

South America
South America

Afro-Eurasia

Americas
Americas

Eurasia
Eurasia

Oceania
Oceania

* FORMER SUPERCONTINENTS Gondwana * Laurasia
Laurasia
* Pangaea * Pannotia
Pannotia
* Rodinia * Columbia * Kenorland * Nena * Sclavia * Ur * Vaalbara

* HISTORICAL CONTINENTS Amazonia * Arctica * Asiamerica * Atlantica
Atlantica
* Avalonia * Baltica
Baltica
* Cimmeria * Congo craton * Euramerica * Kalaharia * Kazakhstania * Laurentia * North China * Siberia * South China * East Antarctica * India

* SUBMERGED CONTINENTS Kerguelen Plateau
Kerguelen Plateau
* Zealandia
Zealandia

* POSSIBLE FUTURE SUPERCONTINENTS Pangaea Ultima * Amasia * Novopangaea

* MYTHICAL AND HYPOTHESISED CONTINENTS Atlantis
Atlantis
* Kumari Kandam * Lemuria * Meropis * Mu * Hyperborea
Hyperborea
* Terra Australis

* See also Regions of the world * Continental fragment

* BOOK * CATEGORY

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Vaalbara
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