What's in a name? The Columbia (Paleopangaea/Nuna) supercontinent

Abstract

Supercontinents play an important role in Earth's history. The exact definition of what constitutes a supercontinent is difficult to establish. Here the argument is made, using Pangæa as a model, that any supercontinent should include ~75% of the preserved continental crust relevant to the time of maximum packing. As an example, Rodinia reached maximum packing at about 1.0Ga and therefore should include 75% of all continental crust older than 1.0Ga. In attempting to ‘name’ any supercontinent, there is a clear precedent for models that provide a name along with a testable reconstruction within a reasonable temporal framework. Both Pangæa and Rodinia are near universally accepted names for the late Paleozoic and Neoproterozoic supercontinent respectively; however, there is a recent push to change the Paleo-Mesoproterozoic supercontinent moniker from “Columbia” to “Nuna”. A careful examination of the “Nuna” and “Columbia” proposals reveals that although the term “Nuna” was published prior to “Columbia”, the “Nuna” proposal is a bit nebulous in terms of the constitution of the giant continent. Details of “Nuna” given in the original manuscript appear to be principally based on previously published connections between Laurentia, Baltica and, to a lesser extent the Angara craton of Siberia (i.e. “the lands bordering the northern oceans”). Therefore the proposal is made that “Columbia” consists of several core elements one of which is “Nuna”.