RODINIA: PROBLEMS, ISSUES AND ACRONYMS

The Proterozoic supercontinent of Rodinia was proposed in the early 1990’s. Subsequent work focused on the configuration, the timing of amalgamation and the timing of breakup of the supercontinent, but no consensus is at hand. One key observation is that Laurentia is surrounded by Neoproterozoic-Paleozoic rift margins whilst Gondwana is dissected by similar-aged collisional belts. This relationship is consistent with the breakup of one supercontinent followed rapidly by the assembly of Gondwana; however, the exact makeup of the antecedent supercontinent is poorly known. This talk focuses on (present-day coordinates are used): (1) SWEAT, AUSWUS or AUSMEX: The original SWEAT hypothesis is based on piercing points between Antarctica and southwestern United States, but subsequent models place Australia further south (e.g. AUSWUS) or much further south (AUSMEX). Whilst the models are paleomagnetically acceptable, they leave a considerable length of rifted margins without conjugates. (2) SIBCOR, SIBARC or SIBNOT- The positioning of Siberia within Rodinia is controversial. The ‘archetypal’ position of Siberia is along the Arctic margin of Laurentia(SIBARC). Others place Siberia adjacent to cordilleran margin of western Laurentia (SIBCOR). Recent suggestions eschew the inclusion of Siberia within Rodinia (SIBNOT). (3) AMABAL, AMASWUS SPUEG or AMAWRONG?- Baltica was originally placed along the Greenland margin in a Pangea-type fit. The South American cratons, Amazonia and Rio Plata, ‘filled-in’ the remaining length with Amazonia adjacent to southern Baltica (AMABAL). New paleomagnetic data place Amazonia adjacent to the Llano region of southwestern U.S. (AMASWUS) and Baltica is ‘inverted’, but positioned close to the Greenland margin (SPUEG). (4) GONDWANA- East Gondwana is traditionally modeled as a single block during the assembly and breakup of Rodinia. Recent work suggests that a piecemeal assembly of East Gondwana parallels the assembly of greater Gondwana during the terminal Neoproterozoic. What was the sequence of events that led to final Gondwana assembly?