Long-lived (1.8-1.0 Ga) convergent orogen in southern Laurentia, its extensions to Australia and Baltica, and implications for refining Rodinia

Between 1.8 and 1.0 Ga (Grenville-age), a series of subparallel accretionar y orogens were added progressively to the southern edge of Laurentia. These belts now extend from Greenland/Labrador to southern California and are tr uncated at late Precambrian passive margins, suggesting that they once exte nded farther. We propose that Australia and Baltica contain their continuat ions. Together they comprise a long-lived orogenic system, > 10000 km long, that preserves a record of 800 million years of convergent margin tectonis m. This tectonism culminated during Grenvillian continent-continent collisi ons in the assembly of the supercontinent Rodinia. Our reconstruction of th e Australia-western US part of this assembly (AUSWUS) differs from the SWEA T reconstruction in that Australia is adjacent to the southwestern US rathe r than to northern Canada. The AUSWUS reconstruction is supported by a dist inctive 'fingerprint' of geologic similarities between Australia and the so uthwestern US from 1.8 to 1.0 Ga, by numerous possible piercing points, and by an arguably better agreement between 1.45 and 1.0 Ga paleomagnetic pole s between Australia and Laurentia. Geologic and paleomagnetic data suggest that separation between Laurentia and Australia took place similar to 800-7 55 Ma and between Laurentia and Baltica similar to 610 Ma. The proposed ass ociation of Australia, Laurentia, and Baltica, and the long-lived convergen t margin they expose, provide a set of testable implications for the tecton ic evolution of these cratons, and an important constraint for Proterozoic plate reconstructions. (C) 2001 Elsevier Science B.V. All rights reserved.