Revised Genesis for Scotland's Largest Pb-Zn deposit

The Leadhills-Wanlockhead (L-W) deposit has a documented mining history dating back to the 13th century and has produced >400,000 t of epigenetic vein type Pb-Zn-Ag-Cu, making it one of Scotland's most historic and productive metal mining districts. Here, we re-evaluate mineral paragenesis and combine novel dating with new stable isotope data to constrain ore forming processes. Vein cross-cutting relationships and colloform banding revealed that hematite pre-dates Pb-Zn mineralisation. (U-Th)/Ne-21 dating of wbotryoidal hematite from Glengonnar mine yields an age of 210 +/- 12 Ma, at least similar to 50 Ma younger than previously suggested. Mean delta S-34 of vein galena and sphalerite is remarkably homogeneous respectively: -9.7 +/- 0.8 parts per thousand (n=40); -6.3 +/- 0.5 parts per thousand (n=16) across a variety of veins and is consistent with derivation from underlying Lower Palaeozoic shales and greywacke. Homogeneity suggests that S source, ore fluid temperature, and oxidation state remained stable during the mineralisation process with sulphides precipitating at or near equilibrium similar to 190 +/- 40 degrees C. Data is consistent with earliest vein mineralisation being related to faulting in the Late Triassic. Faulting may have allowed for deep hydrothermal convection and mixing of fluid in underlying basement and adjacent basin lithologies