Calcite U-Pb geochronology of Huayuan carbonate-hosted Zn-Pb mineralization in Central Yangtze Craton, South China

Abstract

The Yangtze Craton hosts significant Zn-Pb deposits in Neoproterozoic to Carboniferous carbonates (> 60 Mt Pb + Zn metals), accounting for 30% of China's Zn-Pb resources. However, determining the timing of zinc and lead mineralization in these reservoirs is challenging. This study employs LA-ICP-MS U-Pb geochronology on calcites to date Zn-Pb deposits hosted in Lower Cambrian limestone in the Huayuan orefield. Three generations of calcite formation were dated: the first recorded the pre-ore deposition of Lower Cambrian limestone at 517 ± 10 Ma, the second marked a hydrothermal event linked to stratiform sphalerite ore formation at 501.4 ± 8.4 Ma, and the third was associated with discordant breccia-hosted Zn-Pb mineralization at 397.5 ± 9.6 Ma. Our results indicate that Paleozoic carbonate-hosted Pb-Zn mineralization in the Yangtze Craton is linked to (1) the final assembly of Gondwana in the late Cambrian-early Ordovician (520 − 480 Ma); and (2) the intracontinental orogeny response to Jiangnan Uplift (420 − 400 Ma). This study highlights the spatial-temporal relationship between low temperature carbonate-hosted mineralization and orogenic events that are consistent with classic Mississippi Valley-type models worldwide. Furthermore, it demonstrates the potential of in situ U-Pb calcite geochronology to date ore deposits lacking syn-ore minerals suitable for traditional dating methods.