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These regions are theorized to have formed at ancient oceanic spreading centers and island arcs. [2] In simple terms, greenstone belts are described as metamorphosed volcanic belts. Being one of the few most well-preserved Archean portions of the crust, with Archean felsic volcanic rocks, the BGB is well studied. It provides present geologic ...
The Barberton Greenstone Belt is located on the Kaapvaal craton, which covers much of the southeastern part of Africa, and was formed by the emplacement of granitoid batholiths. [7] The Kaapvaal craton was once part of a supercontinent geologists term Vaalbara that also included the Pilbara craton of western Australia. [ 7 ]
A large number of geological and geochemical methods have been applied to the rocks of the Isua Greenstone Belt. These include subdivision of the various lithologies and units within the belt using a combination of geological mapping and U-Pb zircon dating, typically using sensitive high-resolution ion microprobe (SHRIMP), analyses; [3] major and trace element chemistry; [11] [12] structural ...
The Archean Eon (IPA: / ɑːr ˈ k iː ə n / ar-KEE-ən, also spelled Archaean or Archæan), in older sources sometimes called the Archaeozoic, is the second of the four geologic eons of Earth's history, preceded by the Hadean Eon and followed by the Proterozoic. The Archean represents the time period from (million years
The Leonean Orogeny 3.5 to 2.9 billion years ago and the Liberian Orogeny 2.9 to 2.5 billion years ago both influenced the Archean rocks.. Greenstone belts, sequences of metamorphic and volcanic rocks associated with cratons and used by geologists to study early tectonics are found in south-central Liberia, dating to 2.1 billion years ago.
Archean anorthosites represent the second largest anorthosite deposits on Earth. Most have been dated between 3,200 and 2,800 Ma, and commonly associated with basalts and/or greenstone belts. [1] Archean anorthosites are distinct texturally and mineralogically from Proterozoic anorthosite bodies.
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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]