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East European Craton, the core of Baltica. Volgo-Uralian Craton, Russia (3.0–2.7 Ga) Baltic Shield, part of the East European Craton; Fennoscandian Shield, the exposed Northwestern part of the Baltic Shield in Norway, Sweden and Finland (3.1 Ga) Karelian Craton, part of the Fennoscandian Shield in Southeast Finland and Karelia Russia, (3.4 Ga)
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.
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During the Wopmay orogeny, subduction occurred as oceanic crust of the Slave Craton was subducted beneath an eastward-moving continental plate. Likewise, during the Trans-Hudson orogeny, rifting at first separated the Superior craton from the rest of the continent. Then the Superior Craton reversed its direction and the ocean basin began to close.
A shield is a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas. [1] These rocks are older than 570 million years and sometimes date back to around 2 to 3.5 billion years.
Cambrian blue clay outcrop at beach of Gulf of Finland in Voka Estonia is part of the East European Craton , with an average continental crust thickness between 40 and 64 kilometers. The crust consolidated during the Svecofennian Orogeny in the late Paleoproterozoic , nearly two billion years ago.
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]
The Pilbara Craton is an old and stable part of the continental lithosphere located in the Pilbara region of Western Australia. The Pilbara Craton is one of only two pristine Archaean 3.8–2.7 Ga (billion years ago) crusts identified on the Earth, along with the Kaapvaal Craton in South Africa.