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The Tuareg Shield is an area lying between the West African craton and the Saharan Metacraton in West Africa. It has complex geology, reflecting the collision between these cratons and later events. It covers parts of Algeria, Niger and Mali. ==Origins== The shield is mainly composed of Archean or Paleoproterozoic terranes and Neoproterozoic terranes that amalgamated during the Pan African orogeny when the West African craton and the Saharan metacraton converged. The shield originated in oceanic island arcs that formed on the cratons during 900 Ma to 680 Ma, of which relics remain as thrust sheets on top of more rigid bodies.〔 In Mali, the Tilemsi belt is a complex of intraoceanic arcs that formed above a subduction zone sloping down to the east and were accreted to the shield during the Pan-African orogeny.〔 The western part of the Hoggar massif is made of material from the Pharusian Ocean including oceanic basalts, arc volcanic and sedimentary rocks and sediments that were shed into the Pharusian Ocean by the West African craton and the eastern Hoggar. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tuareg Shield」の詳細全文を読む スポンサード リンク
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