Carlin-style gold deposits, Youjiang Basin, China: tectono-thermal and structural analogues of the Carlin-type gold deposits, Nevada, USA

The Triassic gold deposits of the Youjiang Basin, southern China, have been variously correlated to Carlin-style and orogenic gold deposits or classified as a new intermediate deposit type. However, in terms of a multi-scale mineral system approach, they show remarkable similarities to the Tertiary Carlin-type deposits of Nevada and distinct contrasts to orogenic gold deposits. Both the Nevada and Youjiang deposit groups formed in a continent-scale post-orogenic extension event on fragmented continental crust underlain by metasomatized lithosphere. Both form roughly orthogonal deposit trends that subparallel near-orthogonal margins of a continental crustal block, with deposits controlled by gentle anticlines, monoclines or half-horsts and extensional faults, not tight, “locked-up” anticlines, and shear zones. The mineralogy and ore geochemistry of the two groups are similar, with differences consistent with slightly deeper and higher temperature of formation of the older Chinese deposits, commensurate with deeper erosional levels. The Youjiang gold deposits should be classified as Carlin-type, rather than Carlin-like or other terminologies, with their lower gold endowment probably related to a more distal thermal and fluid source than the Nevada Carlin-type deposits.