Significance of a Cambrian date from galena lead-isotope data for the stratiform Cottonbelt deposit in the Monashee Complex, southeastern British Columbia

The Cottonbelt deposit is a large stratiform lead–zinc–magnetite layer within cover rocks of Frenchman Cap dome in the Monashee Complex in southeastern British Columbia. Lead-isotope analyses of galena samples from the deposit plot close to the Cambrian–Hadrynian boundary on lead-isotope ratio diagrams and are similar to analyses of Early Cambrian stratiform deposits in the Anvil Camp in the Yukon Territory. These data suggest that the Cottonbelt deposit and host succession are Cambrian in age, in contrast to other interpretations that suggest considerably older ages for the cover succession of Frenchman Cap dome. These cover rocks, therefore, are considered calcareous and pelitic facies of lower Paleozoic shelf rocks now exposed in the Kootenay Arc to the southeast and the Selkirk Mountains to the east.