PROTEROZOIC FE-CU-(REE) DEPOSITS IN SW CHINA AND NW VIETNAM
Numerous Fe-Cu-(REE) deposits are hosted in Proterozoic metasedimentary-metavolcanic successions in SW China and NW Vietnam, forming the Kangdian IOCG metallogenic province. The Yinachang and Sin Quyen deposits are typical of the province.
The Yinachang deposit contains economic concentrations of Fe and Cu, and is enriched in the LREE. The ore minerals were associated with abundant F- and CO2-rich minerals. This deposit was formed at ~1700 Ma in an intracontinent extensional setting. The mineralization was largely associated with Paleoproterozoic magmatism. The Sin Quyen deposit contains economic concentrations of Cu, Au and LREE, and sub-economic concentration of U. The ore minerals were associated with abundant Cl-bearing gangue minerals. The mineralization occurred at ~840 Ma in a subduction-related (Andean-type) setting. Subduction-related magmatism may provide abundant fluid and ore metals for mineralization.
Results in this study show that IOCG-like deposits can be produced in both intracontinent setting and continent margins. The ore-forming tectonic environment may influence the composition of ore-forming fluids, which in turn determine the mineralogy of ores.