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.
KeywordsFluid Inclusion Carbonaceous Shale Saline Brine Seawater Sulfate Western Fault
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