The igneous petrogenesis and rare metal potential of the peralkaline volcanic complex of the southern Peak Range, Central Queensland, Australia

摘要

The Oligocene Peak Range Volcanics (PRV) of central Queensland have intruded through, and erupted onto, Permian sedimentary rocks of the Bowen Basin above what is likely to be a lithospheric-scale suture zone. The southern PRV consists of domes and flows of augite (bearing) trachyte, hornblende trachyte, hornblende rhyolite, arfvedsonite rhyolite and aegirine rhyolite. The aegirine rhyolite bodies represent the most evolved rock types, with peralkaline index (molar Na + K/A) values of N1.3 and extreme enrichment in trace elements, including the rare metals Zr, Hf, Nb, Ta, and REE. Clarrys Dome, one of three aegirine rhyolite domes, features a late stage magmatic agpaitic assemblage of dalyite (K2ZrSi6O15), a eudialyte-likemineral and aegirine, which is variably replaced and overprinted by secondary REE carbonates and Zr silicates.