Nature and evolution of crustal basement beneath the Duolong ore concentration area, northern Tibet, and their constraints on the metallogenesis: Insights from U-Pb ages of inherited zircons from the Bolong volcanic-intrusive rocks

The nature and evolution of crustal basement controlled the types and potentials of ore deposits. The Duolong ore concentration area, located in northern Tibet, is the largest porphyry-epithermal Cu-Au ore district in China. However, the studies of the nature and evolution of crustal basement beneath the Duolong ore concentration area have been very insufficient. The present study reports LA-ICP-MS U-Pb data of inherited zircons from the Bolong volcanic-intrusive rocks in the Duolong ore concentration area. The authors hold that these data indicate the presence of an Archean-Paleoproterozoic crustal basement beneath the Duolong ore concentration area. This Archean-Paleoproterozoic crustal basement was a part of an extended ancient basement beneath the center of the South Qiangtang terrane, and experienced multiple tectonomagmatic events during the Mesoproterozoic-Early Palaeozoic period. It is also known that the ancient basement beneath the Duolong ore concentration area experienced significant addition of juvenile lower crust (i.e., vertical crustal growth) in the Late Mesozoic, which was induced by the underplating of mantle material. This juvenile lower crust would release substantial metals and other ore-forming components into the magmatic-metallogenic system during subsequent remelting and remobilization.