URL: https://geoscience.data.qld.gov.au/dataset/cr131188
This report was produced by R. Chandler, A. D. Burnham and J. Mavrogenes from the Australian National University Research School of Earth Sciences (ANU - RSES) for the Geological Survey of Queensland as part of the New Economy Minerals Initiative (NEMI)
The epigenetic Cu, Au and U deposits of the eastern Mount Isa Inlier show varying enrichments in a wide range of secondary elements including F, Ba, Co and the Rare Earth Elements (REE). There are two distinct styles of mineralisation within the eastern Mount Isa Inlier that show significant REE-enrichment in addition to Cu, Au and U resources: F-Ba rich IOCGs, and U-Cu-Au skarns.
The first is characterised by late fluorite-barite mineralisation with bulk rock compositions displaying positive correlations between light REEs and Cu, and REE patterns with distinct positive Eu anomalies, and flat to concave light REEs. This second is typified by early REE- (and likely U-) rich skarn formation followed by Cu-Au mineralisation with bulk rock geochemistry displaying no correlation between REE and Cu, and REE patterns with distinct negative Eu anomalies, cnd onvex-upward light REEs. In addition to these two styles, two deposits (SWAN and Milo) show characteristics of both styles, suggested to be intermediate deposits, between these two end members.
LA-ICP-MS mineral trace element analyses of allanite, apatite and REE carbonates highlight a number of features seen in bulk rock geochemistry including persistent positive Eu anomalies in late-stage minerals from the F-Ba rich IOCGs. The skarn systems were found to have minerals with consistent REE patterns, showing consistently negative Eu anomalies and conspicuously low heavy REE.