Other Reconstructions for Rodinia based on sources for Mojavia

The Archaen source for Mojavia has been proposed to be from various continents, such as Siberia, Baltica, Tasmania, besides the AUSWUS and SWEAT theories.

South China:

On the left is the paleoconstruction of Laurentia juxtaposed with South China (Li et al., 2002).

Cathaysis, a Precambrian block of southern China has U-Pb evidence of a Grenvillian orogeny (Li et al., 2002). Cathaysis would then be a potential source for the Belt supergroup (see figure on left). Li argues that AUSWUS and SWEAT do not account for the Grenville orogeny that truncates southern Laurentia at 1.4Ga. His configuration matches 1.43Ga granites in Hainan Island, south China to the Grenville-deformed Yavapai-Mazatzal province. Mojavia is matched with northern Cathaysis which has U-Pb basement age of 1766 +/- 19 Ma and an Archean protolith. But there is no crustal age for this Archean component, so can it truly be a good match for Mojavia?

 

 

 

 


Paleoconstruction of Laurentia fit with Siberia (Sears and Price, 2000).

Sears and Price (2000) reevaluate their earlier hypothesis that Siberia was next to western Laurentia and found more supporting evidence. They believe that the Belt supergroup was fed from sediments of the Udza trough, which would be located southwest of the formation, coinciding with what previous workers have suggested as the source direction (Stewart et al., 2001). The Udzha trough would link the Belt supergroup with southwestern Laurentia, where 1.5 Ga volcanics exist (Sears adn Price, 2000). Paleomagnetic data has not been used to support or disprove this fit. Nor is there Neodymium work to support this configuration.

 

 

 

 

 

 

 

 

 

 


Paleoconstruction of Laurentia with Mojavia attached to Tasmania (Berry et al., 2001). This model is described as an "intermediate reconstruction" between SWEAT and AUSWUS. Detrital zircon work from Proterozoic and Cambrian rocks in Tasmania show that Tasmania was located near Nevada ca. 800-500Ma. This configuration differs from the AUSWUS model previously supported by Berry (Burrett and Berry, 2000 and 2001). In the SWEAT model, Tasmania is near British Columbia, which Berry et al., (2001) remarke as a bad fit from zircon dates (BC is 1.9-2.4Ga while Tasmania is 1.7Ga and 1.4Ga). The AUSWUS model is close to this reconstruction, but would imply a larger Grenville age component in Tasmanian zircons. Like the south China reconstruction, the authors believe the Grenville age connection provides a good fit; the minor 1.4 Ga dates are used to place Tasmania not completely near the Grenville deformed rocks in Arizona.

 

 

 

 

 

 


These three models have supporting evidence which on their own may make a powerful argument, but with the other data (Mojavia crustal ages, Proterozoic sources, little or no paleomagnetic data) they are not fully supported. So which model is correct? Based on the data that we have, can we strongly support one model over the rest?