Individual mesothermal gold deposits may comprise economically important parts of large-scale fluid flow systems in the crust. Provenances for major alluvial gold fields in Australia in zones in the Lachland fold belt which comprised parts of larger deformation zones in which the faults acted as major fluid conduits... A feature of deposits in this field is the invariable association of rich veins with calcite and its occurrence in oxidised zones with arsenical pyrites... The gold content of the arsenical pyrites ranges from 50 to 500 oz.t...

Deeply eroded mesothermal ore bodies in Australia, American Rockies and the Urals of Asia have sourced most of the major gold placers worldwide. In most of these deposits the veins are discontinuous and a typical ore shoot structure consists of interspersed zones of high and sub-ore grade vein material.

Reference: Handbook of Gold Exploration and Evaluation/Eoin H. Macdonald

Kherson