Genesis of the carbonate-hosted zinc–lead deposits in the southwestern Yangtze Craton, SW China: Insights from the Maoping deposit

The southwestern Yangtze Craton represents one of the world's largest zinc–lead provinces and contains over 26 million tons of zinc–lead resources. It comprises more than four hundred carbonate-hosted zinc–lead deposits with various sizes; however, genesis of the deposits has long been debated and still remains controversial, due to a lack of comprehensive understanding on the geology and metallogeny. Located in the north of the area, the giant Maoping zinc–lead deposit (Zn + Pb: 3 Mt @ 10–30 wt%) provides an ideal objective to illustrate this issue. In this paper, we conduct detailed field geological investigation at Maoping and present new in situ LA–ICP–MS data of sulfur and lead isotopes and trace elements from 25 sulfide samples. The δ34S values of the sulfides vary from −22.8 ‰ to +22.5 ‰, and the ratios of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb of the sulfides vary in ranges of 18.247–18.767, 15.712–15.768, and 38.548–39.435, respectively. Combined with previous studies, we interpret that reduced sulfur is likely sourced from marine sulfates in the carbonate of the Upper Devonian Zaige Formation, and ore metals are mainly derived from the Neoproterozoic basement and the Zaige Formation carbonate. Titanium, Cr, Mn, Co, Ni, Cu, Zn, Ge, As, Se, Ag, Cd, Sb, and Pb are enriched in pyrite within the Maoping deposit, and low abundances of Co and Ni (0.01 × 10−6–21.09 × 10−6) and low Co/Ni ratios (0.04–4.95) in pyrite constrain its low-temperature hydrothermal origin. New geological and geochemical data demonstrate that geology, mineralization, and geochemistry of the Maoping deposit coincide with those of the Mississippi-Valley type (MVT) deposits worldwide. Together with previous studies, we suggest that genesis of the carbonate-hosted zinc–lead deposits in the southwestern Yangtze Craton resemble the MVT deposits.