Geology, lithogeochemistry, and sulfur isotope geochemistry of hydrothermal mudstones from the Duck Pond volcanogenic massive sulfide (VMS) deposit, Newfoundland Appalachians, Canada

Sulfide-rich nnudstones from the Duck Pond volcanogenic massive sulfide (VMS) deposit are pyrrhotite-pyrite-rich and occur associated with pillow lavas and rhyolitic volcaniclastic rocks. They have elevated Fe2O3 and base and trace metal content, and have a low detrital element content, suggesting they are hydrothermal in origin. While hydrothermal, they have low Eu/Eu*, variable to high Y/Ho values, mostly low Ce/Ce*, and elevated oxyanion contents. The sulfur isotopic data (delta S-34) from sulfides in the mudstones is predominantly negative, with the exception of euhedral pyrite, which is distinctively positive, suggesting variable contributions biogenic (diagenetic?) and hydrothermal sulfur, respectively. The collective geochemical and isotopic data from the suggest that the Duck Pond mudstones formed from low temperature discharge associated with a buoyant hydrothermal plume, where particles had significant residence time in the water column so as to scavenge oxyanions from oxygenated Cambrian seawater. They also had abundant diagenetic transformations and scavenging of diagenetic sulfur, whereas their hydrothermal sulfur contents were likely minor.