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Cratons of South America and Africa during the Triassic Period when the two continents were joined as part of the Pangea supercontinent. 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 ...
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.
Nevertheless, the oldest cratons on Earth include the Kaapvaal Craton, the Western Gneiss terrane of the Yilgarn Craton (~2.9 – >3.2 Ga), the Pilbara Craton (~3.4 Ga), and portions of the Canadian Shield (~2.4 – >3.6 Ga). Parts of Dharwar Craton in India are greater than 3.0 Ga. The oldest dated rocks of the Baltic Shield are 3.5 Ga old. [10]
Some of the Yilgarn regolith is the oldest in the world, recording weathering events as early as the Cretaceous Period. This has been created by the generally subtropical latitudes and conditions of the Yilgarn craton, with minimal to no glaciation and generally flat topographical relief resulting in comparatively minor erosion.
The Pilbara and Kaapvaal cratons contain well-preserved Archaean microfossils. Drilling has revealed traces of microbial life and photosynthesis from the Archaean in both Africa and Australia. [19] 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.
c. 3,800 Ma – Oldest banded iron formations found. [9] First complete continental masses or cratons, formed of granite blocks, appear on Earth. Occurrence of initial felsic igneous activity on eastern edge of Antarctic craton as first great continental mass begins to coalesce.
A new study says complex life began 1.5 billion years earlier, influenced by ancient volcanic activity, reshaping our understanding of life's timeline on Earth.
The Kalahari Craton is a craton, an old and stable part of the continental lithosphere, that occupies large portions of South Africa, Botswana, Namibia and Zimbabwe. It consists of two cratons separated by the Limpopo Belt : the larger Kaapvaal Craton to the south and the smaller Zimbabwe Craton to the north.