Regional Geochemistry of Tertiary Igneous Rocks in Central Chile: Implications for the Geodynamic Environment of Giant Porphyry Copper and Epithermal Gold Mineralization

      The giant porphyry copper-molybdenum deposits of central Chile formed within a thick sequence of Cretaceous to Pliocene volcanic rocks. The predominantly calc-alkaline basaltic andesites of the Cretaceous Las Chilcas Formation are characterized by La/Smn ratios of 1.8 to 2.5 and Sm/Ybn of 1.8 to 2.8. The upper Oligocene to lower Miocene Abanico Formation (variously defined as the Los Pelambres, Abanico, or Coya Machal

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