Introduction
The apparent geometrical fit of South America and Africa provided impetus to the development of plate tectonic theory. The first proposed fits were based on the idea that the two continents behaved as rigid plates (Taylor 1910, originally presented in 1908; Wegener 1912). Taylor and Wegener arrived at their ideas of fit independently, and each argued for past movement of the continents. Both Taylor and Wegener were drawn to suggest past movement of continents based on the fit of the coastlines of South America and Africa. As Wegener notes “continental drift first came to me…under the direct impression produced by the congruence of the coastlines on either side of the Atlantic” (Wegener 1929; pp 1).
Many reconstructions have been developed and published since Taylor and Wegener proposed that the continents have drifted apart. Subsequent reconstructions have attempted to provide an ever-tighter fit between the continents using improved delineation of ocean floor features (marine magnetic anomalies, fracture zones, and the continent-ocean boundary), and this has provided insight into large-scale processes affecting the movement of continents. Still, the remaining misfit was a vexing issue until the proposition of intra-plate deformation along the Benue Trough-Niger Rift in Africa and in the southern parts of South America.
In this paper, the fit of South America and Africa as proposed by Du Toit (1937), Bullard et al. (1965), Smith and Hallam (1970), Nürnberg and Müller (1991) and Lawver et al. (1999) are reviewed. These reconstructions parameterized the continental movements with Euler rotation axes and angles. Though normally derived from relative movement between specific localized areas of each of the continents, the parameters were applied to the entire continents or large areas as though they were rigid throughout history. Intra-continental deformations in reconstructions have usually been accommodated by breaking large rigid plates into smaller rigid plates and applying knowledge of relative movement between areas within a continent, or between two areas of a continent with respect to a third area of another continent. This results in a chain of Euler rotation parameters which mush be linked to each new subplate as deformation is resolved to smaller and smaller scales.
A new software package, Pplates, handles deformations of a continental plate by allowing areas of a continent to move relative to one another while deforming the interstitial areas of the crust accordingly in compression, extension, or shear deformations. In this paper, Pplates is used to present the previous fits using rigid sub-plates and then to include deformations thus introducing a new approach to software-aided tectonic reconstruction.