The molybdenum (±Cu-Au) mineralization of the Lanham's prospect, Cloncurry district, Australia

The Lanham's Prospect is located in the Proterozoic Doherty Formation of the Cloncurry District in the Mount Isa Block of northern Australia. The prospect is characterized by molybdenum, copper and gold mineralization. The main rock types include calc-silicates and carbonaceous metapelites, with various degrees of brecciation and metasomatic alteration. The meta-sedimentary units were intruded by gabbros and granitoid bodies of the Williams Batholith. The mineralization is hosted in moderately brecciated calc-silicate rocks. The metasomatic alteration associated with the mineralization comprises four phases, starting with a Na-rich phase that is followed by Cu-Au mineralization that precedes the Mo mineralization. The C-O isotope signatures of mineralized samples suggest a magmatic and/or sedimentary (with up-temperature evolution) signature. The sulfur isotopes of the molybdenite display more likely sedimentary values whereas the chalcopyrite and pyrite have inferred magmatic signatures (delta S-34(Py, Cpy) is between -1 parts per thousand and 3 parts per thousand; the delta S-34(Mo) is between -7 parts per thousand and -6 parts per thousand with two outliers with -3 parts per thousand and 1 parts per thousand). Two models are put forward concerning the fluid source(s) and evolution: one mass source for Mo, S, Cu, Au derived from magmatic-hydrothermal fluids; or multiple sources by mixing of magmatic and sedimentary fluids.