Former long-lived passive margins – Cradles for major Sn, W, and Au provinces

• Long-lived passive margins accumulate copious volumes of clastic sediments. • Continent-derived sedimentary rocks are the metal sources. • Most sutures were reactivated several times during later collisional events. • Reworking of passive margin sediments generated major mineral belts. • Giant critical metal deposits in South China are related to suture reactivation. The metal sources for deposits of Sn, W, and Au at former continent margins are continent-derived sedimentary rocks. Long-lived passive margins may accumulate copious volumes of clastic sediments and, therefore, have a great potential to develop major mineral belts of granite-related critical metal deposits when being reworked in an active margin setting. This relation applies globally, possibly most prominently in South China that hosts numerous belts with critical metal deposits. Here we argue that the abundance of Sn and W deposits in southern China is directly related to (i) the formation of the late Neoproterozoic Jiangnan orogenic belt, which formed by the collision of the Yangtze Block with the Cathaysia Block, and (ii) the Phanerozoic assembly of Asia. This latter process involved the separation of Asian terranes from Gondwana, which created extensive shelf areas, and the subsequent collision of these terranes with growing Asia during the closure of the Prototethys, Paleotethys, Mesotethys, and Neotethys oceans. During these collisional processes, the shelf sediments deposited at former passive margins were stacked in accretionary complexes and eventually melted to form granite-related deposits along the suture zones between the blocks that had collided. The oldest deposits along these sutures broadly reflect the accretion and collision of continental blocks with mainland Asia. Most sutures were reactivated several times during later collisional events and, therefore, have several age groups of younger mineralization. Actually, most deposits and in particular the giant deposits in southern China seem to be related to the reactivation rather than to the formation of the various sutures. The reworking of passive margin sediments in an active margin setting also produced major mineral belts in other regions, most importantly the mineral belts at the Mesozoic and Tertiary western margins of South America, North America, and Sibumasu (all in an accretion or subduction setting) and the Carboniferous to Permian Variscan Orogen (in collisional and post-collisional extensional settings).