CONSTRAINTS ON THE MOTIONS OF SOUTH AMERICAN AND AFRICAN SHIELDS DURING THE PROTEROZOIC: I. ⁴⁰Ar/³⁹Ar AND PALEOMAGNETIC CORRELATIONS BETWEEN VENEZUELA AND LIBERIA.

The Encrucijada pluton of Venezuela and amphibolites near Harper, Liberia, are located on opposite sides of the Liberian Pan-African mobile belt, when South America is restored in a fit described in the literature with respect to Africa. Both units yield stable, bipolar, high-temperature magnetizations that appear to be indistinguishable in age at 1. 9 to 2. 0 Ga. With South America in this reconstruction, the corresponding paleomagnetic poles suggest that 1000 km of right-lateral strike-slip motion has occured between the West African and Guayana Shields. The Encrucijada and Harper poles are distinct from the 1. 9- to 2. 0-Ga paleomagnetic poles from the Kalahari Shield and suggest that relative motion has occurred between the Kalahari Shield and the West African and Guayana Shields since that time. Refs.