Nickel mineralization in the Wuxu Sb-Zn-Sn district, Danchi Fold-and-Thrust Belt, South China

This is the authors' abstract. We don't add key points for this paper.

The first discovered nickel orebody in the Shuiluo Ni-Zn-Sb occurrence (1.53% Ni, 1.01% Zn, and 0.94% Sb) occurs as a lenticular body within Late Devonian Wuzhishan Formation (D 3 w ) limestone and is spatially associated with paleo-manganese nodules in the Wuxu Sb-Zn-Sn district of the Danchi Fold-and-Thrust Belt (DFTB), South China. The nickel orebody of the Shuiluo occurrence offers an opportunity to understand the ore-forming process and genesis of this unusual nickel mineralization in the world-renowned tin belt. Field observations, micro-X-ray fluorescence ( μ -XRF) mapping, TESCAN Integrated Mineral Analyzer (TIMA) analysis, and electron probe microanalysis (EPMA) indicate that the Shuiluo orebody records three stages: an early sedimentary Ni-Mn pre-enrichment stage, a later Zn-Sb hydrothermal overprinting stage, and a final supergene enrichment stage. Nickel occurs mainly in three species: Ni hosted by Mn-rich phases and limonite, Ni associated with Zn-W-bearing hydrothermal overprinting, and discrete Ni-rich minerals, including josephinite, annabergite, and Ni-bearing chlorite. We propose that regional Late Devonian Mn-bearing strata provided a Ni-bearing background, whereas paleo-manganese nodules acted as the primary trap for Ni pre-enrichment under oxidizing marine conditions. Subsequent Late Cretaceous Zn-Sb-W-bearing hydrothermal fluids modified the Ni-enriched nodules along permeable structures, and post-Cretaceous weathering and leaching further upgraded Ni to form the local ore-grade Shuiluo Ni orebody. This multi-stage process differs from typical magmatic sulfide, lateritic, hydrothermal, and marine sedimentary Ni deposits, and may represent a previously under-recognized style of Ni mineralization in Sn-polymetallic metallogenic belts. The Late Devonian Mn-bearing Wuzhishan and Liujiang formations in South China may be prospective for similar Ni-Co mineralization where Mn-nodule-rich horizons have experienced hydrothermal overprinting and subsequent supergene weathering and oxidation.