The Columbia supercontinent: Retrospective, status, and a statistical assessment of paleomagnetic poles used in reconstructions

Abstract

The proposal that a Paleo-Mesoproterozoic supercontinent, Columbia, preceded the existence of Rodinia was forwarded in 2002. A similar proposal that same year provided a detailed discussion of 2.1–1.8 Ga orogenic belts distributed throughout the globe thought to represent the assembly of Columbia. In the 20 years that followed, evidence in favor of Columbia has grown but its exact configuration and geometrical relationships between various cratons remains elusive. One of several challenges in reconstructing Columbia is the paucity of high-quality paleomagnetic data. Progress is slow, but steady, in this realm as it requires painstaking field and laboratory work to generate a new pole. Despite large gaps in the database, we have generated testable models of Columbia. Unfortunately, there are seldom coeval poles from many continents and reconstructions represent small time-slices in Columbia's lifespan. In this contribution, we review the history of the Columbia hypothesis, evidence mounted in support of the idea and status of the model. We present a statistical method to evaluate goodness of fit in paleomagnetically based reconstructions where data are separated in both time and space. Baltica and Amazonia are often linked together with eastern Laurentia to form a long-lived accretionary orogenic margin of Columbia. This so-called SAMBA model was originally posited as a one billion year long (1.8–0.8 Ga) fixture in both Columbia and Rodinia. Paleomagnetic data are supportive of this connection from ∼ 1.75–1.5 Ga, but not during younger times. We also test a recent model of Columbia based on the highest quality paleomagnetic poles available at that time. Our analysis reveals numerous discrepancies between data and models that will need to be addressed as work towards reconstructing Columbia continues unabated.