The possible roles of Precambrian biota in the origin of magmatogene and hydrothermal silver-bearing vein deposits
The origins of silver-bearing, polyelement vein associations in the Great Bear Lake region and elsewhere in the world might be traced back to possible organic-rich, Precambrian sedimentary protoliths. These protoliths could have yielded a characteristic spectrum of elements to hydrothermal systems during regional metamorphism or during anatexis to form S-type granitoids. Wholesale capture of metals and metalloids by microbiota and their remains may have been a characteristic of some Early Proterozoic marginal marine, mesosaline environments. Two possible atmosphere–hydrosphere–lithosphere models are considered in light of recent theories. The metallogenic effects of Early Proterozoic organic-rich sedimentary environments could be of great significance: they might account for the polyelemental signatures of many younger, remobilized metal liferous systems.