Deep crustal-scale controls of orogenic gold mineral systems - Hodgkinson metallogenic zone, north Queensland, Australia

The bulk of significant orogenic gold deposits in the late Paleozoic Hodgkinson Province in north Queensland occur in a narrow belt (<20 km wide), discordant to most of the surface geological structures. This metallogenic zone lies along the inferred edge of the Proterozoic Etheridge Province underlying the southwestern Hodgkinson Province in the middle crust. The position of this deep crustal feature is indicated by a recent deep seismic survey and marked by a change from l- and A-type Carboniferous to Permian magmatism and the sub-greenschist facies regional metamorphic grade in the south-western Hodgkinson Province to the S-type Permian magmatism and the greenschist facies in the rest of the province. The geometry and architecture of the Paleo-Proterozoic continental margin affected both the initial development of the Hodgkinson Province and the subsequent structural and thermal history of its southwestern part. The combination of these factors resulted in the formation of a discrete orogenic gold metallogenic zone within a much larger geological province. Similar deep crustal metallogenic zone-scale controls probably operated in central Victoria (the Selwyn Block) and in the Charters Towers region.