The giant Imiter silver deposit: Neoproterozoic epithermal mineralization in the Anti-Atlas, Morocco
The world-class Imiter silver deposit, in the Anti-Atlas Mountains of Morocco, is a Neoproterozoic epithermal vein deposit genetically associated with a felsic volcanic event, and formed within a regional extensional tectonic regime. Rhyolitic volcanism related to ore formation has been dated at 550±3 Ma by ion-probe U/Pb on zircons. The economic silver mineralization is superimposed on an older, discrete base-metal assemblage associated with calc-alkaline granodioritic magmatism. The magmatism is dated at 572±5 Ma by ion-probe U/Pb dating on zircons, and by 40Ar/39Ar dating on hydrothermal muscovites. In the Anti-Atlas Mountains, the Precambrian–Cambrian transition appears as an important period for the formation of major, productive precious-metal deposits associated with volcanic events and extensional tectonics. The Imiter silver deposit constitutes a Precambrian analogue to modern epithermal deposits.
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