Terrane boundary and spatio-temporal distribution of ore deposits in the Sanjiang Tethyan Orogen: insights from zircon Hf-isotopic mapping

Abstract

The Sanjiang Tethyan Orogen (SJTO) of the eastern Tethyan tectonic belt in China records a transition from Late Paleozoic Tethys realm to Cenozoic continental collision associated with the formation of large metallic mineral deposits. This contribution combines geological and Hf-isotopic data for igneous rocks from the SJTO, together with the salient features associated with mineralization to gain insights into the crustal architecture and metallogeny. Integrating the available information from tectonic events, sedimentary successions, paleobiogeography, and paleolatitude based on paleomagnetic data, the Hf isotopic maps that we construct highlight the Changning-Menglian Suture as an important tectonic boundary between the Gondwana and Cathaysian continents. The Changning-Menglian Suture separates two distinct Hf isotopic domains with an old, reworked, crustal block to the southwestern part of the SJTO, and a juvenile crustal block with significant mantle-derived components to the northeastern part of the orogen.The Hf isotopic mapping of the SJTO also provides important indications on the location of different deposits. The Jinshajiang-Ailaoshan Suture appears to have exerted a first-order control on the localisation of Cenozoic magmatism and intrusion-related mineral systems. The magmatic source for intrusions in the eastern high-εHf, low TDMc domain, is dominated by mantle components and gave rise to porphyry and porphyry-skarn Cu-(Mo) mineralization. In contrast, the magma sources for intrusions in the low-εHf, high TDMc domains contain an old and reworked crustal component and gave rise to granite-related Sn-W mineralization. Those for the intrusions characterized by variable εHf and TDMc are dominantly reworked older crustal components together with subordinate juvenile material which generated the granite-related Pb-Zn-Cu-Ag mineralization.