Age and origin of the Yangibana LREE deposit and associated ferrocarbonatites, Gascoyne Province, Western Australia

The Yangibana LREE deposit is hosted within the Proterozoic Gifford Creek Carbonatite Complex (GCCC) of the Gascoyne Province, Capricorn Orogen, Western Australia. At the prospect scale, REE mineralisation is hosted in “ironstone” dykes and sills that intrude the rocks of the GCCC [1]. The “ironstones” are heavily oxidized dykes and sills composed mainly of hematite, quartz, clay minerals, monazite and apatite. Based on detailed mapping of field relationships, we show that the “ironstones” emanate from ferrocarbonatites of the GCCC. The ferrocarbonatite dykes are composed of dolomite, ankerite, siderite, riebeckite, aegirine, annitephlogopite, apatite and monazite. Both the “ironstones” and ferrocarbonatites are enveloped by K-dominant, fenite alteration. Whole rock and trace element geochemical transects conducted across the “ironstones” show depletions of Si, Al, Ca, Na, K, Rb, Ta, and W and enrichment of Mn, P, Sr, Fe, Ni, Cu, Zn, Sr, Pb, Th, U and the REEs when compared to least altered samples. Similar transects conducted across the ferrocarbonatites show similar, though less pronounced, patterns.