Structural and temporal framework of the Coen Region, north Queensland: implications for major tectonothermal events in east and north Australia

The character and chronology of tectonothermal events are described for provinces and subprovinces exposed in the Coen Region (Coen and Yambo Inliers) of north Queensland. These include the Proterozoic Yambo Subprovince, Savannah and iron Range Provinces, and the Palaeozoic Pama and Kennedy Provinces. North Queensland underwent two major crust-forming periods on a pre-1800 Ma basement, a Proterozoic period (1800-1550 Ma) and a second Palaeozoic period (430-280 Ma). The intervening similar to 1000 million years of relative geological quiescence was interrupted by minor Grenville-age modification (1300-1000 Ma). Rocks of this age have important implications for Rodinian reconstructions and the location of Grenville piercing points. The Coen Region is significant in that most events can be correlated with the better known and studied regions of east and central Australia. The region is located in the east of the Australian continent and most events were intraplate (in)onto a pre-1800 Ma crust. Therefore, plate-margin processes must have occurred further east than the present-day exposure. Crustal buildup of northeastern Australia in the Proterozoic was not a result of simple eastward accretion onto the Australian craton because older rocks (Yambo Subprovince) are found to the east of younger rocks (Savannah Province). Rifting-type models as traditionally applied to Mt Isa and Broken Hill may also be applicable to the Proterozoic basins of the Coen Region.