Abstract A new map, the first based on interpretation of satellite imagery, reveals both the complexity of Australia's dunefields and their relationships with topography, climate and substrate. Of the five main sand seas, the Mallee, Strzelecki and Simpson in eastern Australia cover Quaternary sedimentary basins whereas the Great Victoria and Great Sandy dunefields in the west are formed by reworking of valley and piedmont sediments in a non-basinal landscape of low-relief ridge and valley topography. These dunefields cover large areas of the arid zone and semi-arid zone and small areas of dunes in sub-humid areas around the margins of the continent reflecting past expansion of arid climates during glacial stages of the last several glacial cycles. Several areas of low relief stand out as being largely dune-free: the limestone Nullarbor Plain, clay plains of the Georgina Basin and floodplains of rivers in the Carpentaria, Lake Eyre and Murray–Darling drainage basins where sand is rare or not transported by diminished Late Quaternary rivers. The Yilgarn Block of southwestern Australia is also surprisingly free of dunes, possibly as a result of long, deep weathering. Everywhere the history of climate change is evident in dune morphology and distribution, including large areas where the sand dune orientations are markedly divergent from modern sand moving wind directions.

Felsic I-type granites and associated volcanic rocks of Carboniferous age are extensively developed over an area of 15,000 km 2 in northern Queensland. These granites have been subdivided into four supersuites: Almaden, Claret Creek, Ootann and O’Briens Creek. Granites of the Almaden Supersuite are intermediate to felsic (56–72% SiO 2 ) and are characterised by high K 2 O, K/K(K + Na), Rb, Rb/Sr, Th, U and relatively low Ba and Sr. The Claret Creek Supersuite granites are a little more felsic (65–77% SiO 2 ), and are chemically distinctive, having higher A1 2 O 3 , CaO, Na 2 O and Sr, and lower K 2 O, Rb, Th and U than granites of the Almaden Supersuite. Granites of the Ootann and O’Briens Creek supersuites all contain more than 70% SiO 2 and these comprise more than 90% of the total area of granites. These two supersuites are characterised by low Sr, Sr/Y and large negative Eu/Eu*, with the more evolved rocks becoming strongly depleted in TiO 2 , FeO* MgO, CaO, Ba, Sr, Sc, V, Cr, Ni, Eu, Ce N /Y N and K/Rb, and enriched in Rb, Pb, Th, U and Rb/Sr. Granites belonging to the O’Briens Creek Supersuite contain significantly higher abundances of HFSE, HREE and F (0.2–0.5 wt%) than those of the Ootann Supersuite, and as such have developed some characteristics of A-type granites. Geochemical and isotopic properties suggest that all granites are of crustal derivation. The granites of all supersuites have very similar initial 87 Sr/ 86 Sr and ε Nd of 0.710 and −7.0–−8.0, respectively, except where they outcrop within Proterozoic country rocks, when they have more evolved ε Nd (−8.0–−11.0). Depleted-mantle model ages cluster around 1·5 Ga. The isotope and geochemistry indicate that these granites were not derived from the equivalents of any exposed country rocks. Models for the petrogenesis of these granites all appear to require the involvement of a long-lived and isotopically homogeneous crustal protolith, that most probably underplated the crust in the Proterozoic. Granites of the two more felsic supersuites were either derived by varying degrees of partial melting from this protolith of andesitic to dacitic composition, and/or were produced by a two-stage process by remelting of intermediate rocks similar in composition to the mafic end-members of the Almaden Supersuite. The resulting primary partial melts for the Ootann and O’Briens Creek supersuites underwent extensive, high-level, feldspar-dominated, crystal fractionation.