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A craton (/ ˈ k r eɪ t ɒ n / KRAYT-on, / ˈ k r æ t ɒ n / KRAT-on, or / ˈ k r eɪ t ən / KRAY-tən; [1] [2] [3] from Ancient Greek: κράτος kratos "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust and the uppermost mantle.
The Slave Craton shows a long history of continental lithospheric mantle formation. Diamond formation is relatively extensive throughout the Slave Craton and requires a thick cratonic root. [ 13 ] The oldest diamonds derived from the mantle were between 3.5 and 3.3 Ga, which suggest that the Slave Protocraton would have formed a thick crustal ...
A craton is an ancient part of the Earth's continental crust which has been more or less stable since Precambrian times. Cratons whose ancient rocks are widely exposed at the surface, often with relatively subdued relief, are known as shields.
The thin mantle root, which is the lowest part of lithosphere, is the reason for its instability. [1] The thinning of the mantle root caused the craton to destabilize, weakening the seismogenic layer, which then allows earthquakes to happen in the crust. [1]
Researchers at McGill University found a rock with a very old model age for extraction from the mantle (3.8 to 4.28 billion years ago) in the Nuvvuagittuq greenstone belt on the coast of Hudson Bay, in northern Quebec; [2] the true age of these samples is still under debate, and they may actually be closer to 3.8 billion years old. [3]
[29] [32] [33] They suggest the head of the mantle plume, which was sited beneath the South China Block, led to rifting and bimodal magmatism since 825 Ma. The discovery of 825 Ma komatiitic basalts in Yiyang, which is indicative of a hot mantle source, provides an indisputable evidence for the presence of a mantle plume. [34]
The craton appears to have formed when three Archean cratons fused: Leo-Man-Ghana, Taoudeni and Reguibat. The first two docked around 2.1 Ga (billion years ago), and the Reguibat Craton docked with the craton around 2 Ga. The roots of the combined craton extend to a depth of over 300 km (190 mi) in the sub-continental lithospheric mantle. [4]
A location map of the Eastern Block of the North China Craton. Shaded area represents the Eastern Block. Generated from GeoMapApp (Ryan et al., 2009). [1] The Eastern Block of the North China Craton is one of the Earth's oldest pieces of continent. It is separated from the Western Block by the Trans-North China Orogen. [1]
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