Yankerbara Hypothesis
There has been some debate when and whether Vaalbara existed.
An Archaean-Palaeoproterozoic (2.8–2.1 Ga) link between South Africa and Western Australia was first proposed by Button 1976. He found a wide range of similarities between the Transvaal Basin in South Africa and the Hamersley Basin in Australia. Button, however, placed Madagascar between Africa and Australia and concluded that Gondwana must have had a long stable tectonic history.[2] 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 hypothesis.[3] …show more content…
This model is supported by the palaeomagnetic data of Zegers, de Wit & White 1998.[4] Reconstructions of the palaeolatitudes of the two cratons at 2.78–2.77 Ga are ambiguous however. In the reconstruction of Wingate 1998 they fail to overlap, but they do in more recent reconstructions, for example Strik et al. 2003.[5]
Other scientists dispute the existence of Vaalbara and explain similarities between the two cratons as the product of global processes. They point to, for example, thick volcanic deposits on other cratons such as Amazonia, São Francisco, and Karnataka.[6]
Zimgarn, another proposed supercraton composed of the Zimbabwe and Yilgarn cratons at 2.41 Ga, is distinct from Vaalbara. Zimgarn should have disintegrated around 2.1–2.0 Ga to reassemble as the Kalahari and West Australian (Yilgarn and Pilbara) cratons around 1.95–1.8 …show more content…
Grunehogna collided with the rest of East Antarctica during the Mesoproterozoic assembly of the supercontinent Rodinia and the Grenville orogeny. The Neoproterozoic Pan-African orogeny and the assembly of Gondwana/Pannotia produced large shear zones between Grunehogna and Kalahari. During the Jurassic break-up of Gondwana these shear zones finally separated Grunehogna and the rest of Antarctica from Africa.[8] In the Annandags Peaks, the only exposed parts of Grunehogna, detrital zircons from several crustal sources have been dated to 3.9–3.0 Ga suggesting intracrustal recycling was an important part in the formation of the first
An Archaean-Palaeoproterozoic (2.8–2.1 Ga) link between South Africa and Western Australia was first proposed by Button 1976. He found a wide range of similarities between the Transvaal Basin in South Africa and the Hamersley Basin in Australia. Button, however, placed Madagascar between Africa and Australia and concluded that Gondwana must have had a long stable tectonic history.[2] 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 hypothesis.[3] …show more content…
This model is supported by the palaeomagnetic data of Zegers, de Wit & White 1998.[4] Reconstructions of the palaeolatitudes of the two cratons at 2.78–2.77 Ga are ambiguous however. In the reconstruction of Wingate 1998 they fail to overlap, but they do in more recent reconstructions, for example Strik et al. 2003.[5]
Other scientists dispute the existence of Vaalbara and explain similarities between the two cratons as the product of global processes. They point to, for example, thick volcanic deposits on other cratons such as Amazonia, São Francisco, and Karnataka.[6]
Zimgarn, another proposed supercraton composed of the Zimbabwe and Yilgarn cratons at 2.41 Ga, is distinct from Vaalbara. Zimgarn should have disintegrated around 2.1–2.0 Ga to reassemble as the Kalahari and West Australian (Yilgarn and Pilbara) cratons around 1.95–1.8 …show more content…
Grunehogna collided with the rest of East Antarctica during the Mesoproterozoic assembly of the supercontinent Rodinia and the Grenville orogeny. The Neoproterozoic Pan-African orogeny and the assembly of Gondwana/Pannotia produced large shear zones between Grunehogna and Kalahari. During the Jurassic break-up of Gondwana these shear zones finally separated Grunehogna and the rest of Antarctica from Africa.[8] In the Annandags Peaks, the only exposed parts of Grunehogna, detrital zircons from several crustal sources have been dated to 3.9–3.0 Ga suggesting intracrustal recycling was an important part in the formation of the first