Geochronological evidence of Hercynian activity in Newfoundland

Abstract

A RECONSTRUCTION of the continental blocks for the central and North Atlantic has led to the widespread acceptance of the continuity of the Palaeozoic orogenic belts on both sides of the Atlantic. A reconstruction of the land masses during the Carboniferous and Permian shows the Variscan Belt of Europe, the Mauritanides of Morocco, and the Southern Appalachians as being continuous¹. Although the Hercynian Front has now been recognised in New Brunswick² the situation in Newfoundland is unclear. We suggest, on the basis of the geochemical data outlined in Table 1, that the continuation of these belts can be interpolated between New Brunswick and south-west England to include at least the Central Mobile Belt and the Avalon Zone of Newfoundland. We find the earlier correlation by Holmes³ particularly attractive in view of our new isotopic data, a correlation which extends the Hercynian Front westwars from south-west England and Wales into Canada, where it passes along the Cabot Fault into the New Brunswick seaboard and the Bay of Fundy (Fig. 1). Cherkis et al.⁴ link the Charlie Gibbs Fracture Zone to the Hercynian Front on both the European and North American continents, and have recently offered new evidence for the emergence of the front in Newfoundland⁵. The intersection of the Charlie Gibbs Fracture Zone and the continental shelf of Newfoundland lies about 100km east of the Cabot Fault, so that their delineation of the front lies further to the south than the one outlined here.