PROTEROZOIC INTERACTIONS BETWEEN AUSTRALIA AND NORTH AMERICA

We examine the relationship between eastern Australia and western North America during the Early and Middle Proterozoic (c. 1.9-1.1 Ga). The two continents have a long history of interaction that significantly predates the proposed "Grenvillean" assembly of Rodinia. We reassess the various geological pinning points that span the proposed c. 650 Ma conjugate rift margins of the two continents and propose a modified internal configuration of the Early to Middle Proterozoic Australian continent that honours correlations between the Mount Isa Inlier, Georgetown Inlier, Willyama Inlier and Gawler Craton. The Early to Middle Proterozoic (c. 1.88-1.67 Ga) mobile terranes of Arunta Inlier and Gawler Craton are aligned into a continuous belt that can be correlated with the accretionary terranes (Yavapai and Mazatzal) of southwest North America. The two continents were located to the north of a long-lived convergent plate boundary. Despite this correlation the available evidence does not support a continuous link between eastern Australia and western North America. Instead a sequence of complex interactions between the two continents are recorded along a north-south oriented corridor that includes the eastern Proterozoic terranes of Australia and the western Proterozoic terranes of North America. Several episodes of continental collision and amalgamation, represented by the Rimbey Suture (c. 1.85-1.79 Ga), the Isan and Olarian orogenies (c. 1.58-1.50 Ga) and the Grenville Orogeny (c. 1.30-1.10 Ga), were separated by long-lived periods of intermittent extension and transient phases of continental separation.