Lead and zinc are found in two distinct associations in sedimentary rocks: carbonate-hosted and shale-hosted. The carbonate-hosted ores are generally agreed to be epigenetic, deposited from low temperature hydrothermal fluids. The shale-hosted deposits are more controversial, but most appear to be at least partly syngenetic. Shale-hosted orebodies can be exceptionally large, and are perhaps the most popular exploration targets among sedimentary ores at the present time. A transitional form between these two, one that is accordingly given considerable attention, is syngenetic ore in carbonate rocks, such as at Tynagh, in Ireland.
KeywordsZinc Arsenic Boron Sandstone Calcite
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