Richat Structure is an eroded dome, 40 kilometres in diameter, exposing sedimentary rock in layers which appear as concentric rings. Igneous rock is exposed inside and there are spectacular rhyolites and gabbros which have undergone hydrothermal alteration, and a central megabreccia. Structure is also the location of exceptional accumulations of Acheulean archaeological artifacts.
About Richat Structure in brief
Richat Structure is an eroded dome, 40 kilometres in diameter, exposing sedimentary rock in layers which appear as concentric rings. Igneous rock is exposed inside and there are spectacular rhyolites and gabbros which have undergone hydrothermal alteration, and a central megabreccia. The structure is also the location of exceptional accumulations of Acheulean archaeological artifacts. It was first described in the 1930s to 1940s, as Richât Crater orRichât buttonhole. In the 1960s it was briefly considered that it was formed by terrestrial impact, but closer study has found no evidence of any type of shock or deformation indicative of a extraterrestrial impact. It is now thought to be the result of a laccolithic thrust.
The sedimentary rocks composing this structure dip outward at 10–20°. Differential erosion of resistant layers of quartzite has created high-relief circular cuestas. Its center consists of a siliceous breccia covering an area that is at least 30 kilometres in diameter. The rhyolitic rocks consist of lava flows and hydrothermally altered tuffaceous rocks that are part of two distinct eruptive centers. A kimberlitic plug and several sills have been found within the northern part of the Richat Structure. The carbonatite rocks have been dated as having cooled between 94 and 104 million years ago. These intrusive igneous rocks are interpreted as indicating the presence of a large alkaline igneous intrusion.
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This page is based on the article Richat Structure published in Wikipedia (as of Dec. 09, 2020) and was automatically summarized using artificial intelligence.
