http://www.geokniga.org/bookfiles/geokniga-2000emsbo.pdf "Newly...

http://www.geokniga.org/bookfiles/geokniga-2000emsbo.pdf

"Newly recognized gold-rich sedimentary-exhalative (sedex) mineralization in Nevada, with an average
gold grade of 14 g/tonne (t), and the occurrence of significant amounts of gold in classic sedex deposits
like Rammelsberg, Germany (30 Mt at 1 g/t), Anvil, Canada (120 Mt at 0.7 g/t), and Triumph, Idaho
(? at 2.2 g/t) demonstrate that basin brines can form gold ore. The sedex Au mineralization in Nevada
represents a previously unrecognized end member in a spectrum of sedex deposits that also includes
large Zn-Pb, intermediate Zn-Pb-Ba ± Au, and barite deposits"

"Intermediate Zn-Pb-Ba ± Au deposits like Rammelsberg in Germany, the Tom and Jason deposits, and those of the Anvil district in the Selwyn basin are generally smaller with <50 Mt, of slightly lower Zn-Pb grades, have associated high-grade barite, and can contain significant gold grades"

Again no expert but if anyone is more skilled at geology possibly some useful info in here.