To the left is
the configuration proposed by Burrett and Berry (2000). The similarities they
propose between the two provinces are:The AUSWUS configuration is based on the fitting of Australia with southwestern United States. Burrett and Berry (2000) suggest that Mojavia was connect to the Broken Hill-Olary block in Australia. The Broken Hill-Olary block has a TDM of 2.0-2.2Ga and crystallization ages of 1.6-1.74Ga, very similar to Mojavia.
To the left is
the configuration proposed by Burrett and Berry (2000). The similarities they
propose between the two provinces are:
1. similar crustal model ages--Mojavia has 2.2-2.6 Ga (Ramo and Calzia), Broken Hill has 2.0-2.2Ga
2. similar crystallization ages--Mojavia has 1.67-1.71Ga, Broken Hill has 1.6-1.74 Ga
3. similar deformation ages--Ivanpah Orogeny in Mojavia is 1.696Ga, Olary Orogeny in Broken Hill is 1.69Ga
4. similar aged anorogenic plutons--1.1-1.2Ga diabase and basalts in Mojavia, 1.3-1.5 granites in Broken Hill
5. perhaps similar lead isotope values--The Pb provinces in Australia have not been determined, so this similarity is only an assumption.
But are these similarities good fits? The TDM ages do not seem to match up well; Mojavia appears to have older dates. The Ivanpah orogeny has been dated on synorogenic rocks in Mojavia at 1.71 +/- 0.01 Ga by Anderson et al., (1993). Post orogenic rocks were also dated at 1.69Ga, so the ages of deformation do not actually match up. And while the anorogenic plutons do not appear to match well, work done by Anderson et al., (1993) dates the plutons around 1.4Ga, making for a better age match.
Burrett
and Berry (2001) show that the Broken Hill block in South Wales, Australia
matches with Mojavia for Y (Yttrium) and Nb (Niobium) abundances. Unfortuately,
they do not show how the SWEAT or other models would compare on this graph.
Other authors have supported the AUSWUS reconstruction based on the fit of
paleorift margins, sources for miogeooclinal sediments, and paleomagnetic evidence.
Stewart et al., (2001) suggest that the Proterozoic exotic source for the Apache,
Grand Canyon, and Pahrump groups is Australia, instead of Antarctica, Siberia,
Congo, or Baltica. this is because they believe the provenince for the Proterozoic
in northwestern Mexico is the same for the Proterozoic groups mentioned above.
The other models would have not have one continent for the source of both Mexican
and southwestern US sediments, but two. Also, Stewart et l., (2001) argue that
the only matching zircon population (1.576-1.619Ga) is found in the Priest Complex
in the Gawler craton (Australia). The Gawler craton has also been proposed as
the provinence for the Belt supergroup in Montana (Evans
et al., 2000). The work done by Timmons et al., (2001) on the Grand
Canyon supergroup supports AUSWUS, but mainly because Karl Karlstrom also
proposed the configuration.
Karlstrom et al, (2001) argue that AUSWUS is the best fit for Rodinia because of paleomagnetic data and geological piercing points (figure below).
Like the Burrett and Berry (2000) and the Stewart et al., (2001) reconstruction, Mojavia is matched with the Broken Hill and Gawler craton of Australia. Antarctica is below Australia. The paleomagnetic data for Australia is very uncertain for the Proterozoic; there are some poorly constrained poles for 1.1Ga, and no poles until 750Ma (Meert and Powell, 2001). Thus, the paleomagnetic data cannot be conclusively used to support the AUSWUS or any other model.