Cenozoic Tectonic Reconstruction and the Initial Distribution of Porphyry Copper Deposits in the Sonoran Desert Region of Southwestern North America: Implications for Metallogenesis

Abstract The numerous porphyry copper deposits in the Sonoran Desert region of southwestern North America are mostly within the Basin and Range tectonic province where they have been displaced and dispersed by middle to late Cenozoic tectonic extension. Reconstruction of this extension, based largely on evaluation of displacements on low-angle normal faults associated with metamorphic core complexes, restores these deposits to their approximate positions at the end of Laramide orogenesis (~50 Ma). This restoration places the 39 largest known deposits in five linear belts, four of which trend easterly to northeasterly at high angles to the Laramide continental margin. The east to northeast trends of these four belts are interpreted to reflect elevated copper and molybdenum fertility in linear zones in the deep crust and/or upper mantle that parallel the tectonic fabric of the Paleoproterozoic Yavapai-Mazatzal orogenic belt.