West African proximity of the Avalon terrane in the latest Precambrian

Abstract

Considerable debate surrounds the Late Neoproterozoic paleogeographic position of the Avalon terrane, specifically whether it was adjacent to West Africa or Amazonia. New paleomagnetic results from upper Neoproterozoic rocks in the Avalon terrane challenge the latter position. Samples collected from the ca. 580‐570 Ma Marystown Group in the southern part of the Burin peninsula of Newfoundland, Canada, yield high-temperature magnetic components, including dual-polarity directions, which are considered to be primary, on the basis of positive fold and agglomerate tests. The resultant tilt-corrected inclination is 538, representing a paleolatitude of deposition of 34 81 88/‐78 for the Marystown Group. Given the likelihood that Amazonia and Laurentia were still juxtaposed around 580‐570 Ma, the Marystown Group results reveal that the paleolatitude of Avalon is significantly lower than would be expected if it was part of Amazonia. In fact, Avalon was separated from northern Amazonia by at least 1100 km at ca. 580 Ma. If West Africa was juxtaposed to Amazonia, opposite Laurentia, by this time, these results place Avalon at the same paleolatitude as the northern margin of the West African craton.