Spatial and temporal variations in the distribution of eastern Australian post-orogenic granites and related mineral deposits: metallogenic and tectonic significance

Post-orogenic granites and related mineralisation within the Tasman Element of eastern Australia exhibit systematic spatial and temporal patterns that refine our understanding of regional tectonic evolution. In southeastern Australia, two west-younging trends are recognised: post-Benambran granites (435–410 Ma) extending from northeastern New South Wales to southwestern Victoria, and post-Bindian granites (410–350 Ma) from southeastern New South Wales to western Tasmania. Both trends young inboard from an inferred west-dipping convergent margin, reflecting progressive inboard migration of post-tectonic extension, crustal thinning, decompression melting and granite-related mineralisation. In northeastern Queensland, 320–260 Ma granites show a north-younging trend, broadly parallel to the coeval convergent margin, possibly linked to along-strike variations in convergence. In the New England Orogen, syn- to post-Hunter–Bowen granites (260–230 Ma) young eastward, opposing the west-younging trends in the southeastern Australia, while older 320–260 Ma granites display a south-younging progression. These patterns likely record an outboard shift in extensional processes controlling granite emplacement and mineralisation. Associated granite-related mineral systems—including alkalic porphyry copper, granite-hosted rare metals (Sn, W, Mo) and intrusion-related gold—closely follow these granite age trends. Similar relationships occur along other convergent margins globally, underscoring their broader geodynamic significance. However, the specific mechanisms driving the migration of post-tectonic granites remain uncertain, and interpretations presented here are preliminary. Further research is required to resolve the geodynamic controls underlying these spatial and temporal relationships is needed.