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A
0 ? ?
100
1.2 Ga
1.6 Ga
200
B
0
melt
100 Mantle convection
Kilometers
200
Subduction
indicators
C
Collision indicators
0
Subduction
indicators
100
200
Figure 4. Cartoon showing three tectono-magmatic episodes and key characteristics of each discussed in this paper. (A) Early to Mid-
Mesoproterozoic single-lid episode; (B) Late Mesoproterozoic regime; and (C) Neoproterozoic and younger plate-tectonic regime.
A—A-type granites; An—anorthosite.
into plate tectonics. We can’t understand evidence for a single-lid tectonic regime. publish this paper, to Peter Cawood for a second
the evolution of plate tectonics without bet- The Mesoproterozoic is the best interval of review, and to Mihai Ducea for speedy editorial
ter understanding Earth’s episodes of single- Earth history for this exploration to begin. handling. This is University of Texas at Dallas geo-
sciences contribution #1376.
lid behavior, when these were, and what the
magmatic and tectonic styles of each were. ACKNOWLEDGMENTS REFERENCES CITED
The single-lid tectonic history of our planet Without Kent Condie’s help, I wouldn’t know Ashwal, L.D., 2010, The temporality of anorthosites:
needs to be explored if we are to understand how to start to think about the Mesoproterozoic. Canadian Mineralogist, v. 48, p. 711–728, https://
how the modern solid Earth came to be. Also, thanks to Jean Bédard, Peter Cawood, and an doi.org/10.3749/canmin.48.4.711.
anonymous referee for incisive reviews of an earlier
Negative evidence that plate tectonics did not version of this manuscript, to Jerry Dickens for sug- Ashwal, L.D., and Bybee, G.M., 2017, Crustal evo-
occur should be combined with positive gesting that GSA Today might be a good place to lution and the temporality of anorthosites:
www.geosociety.org/gsatoday 9
