PROTEROZOIC TECTONICS OF NORTHWESTERN GONDWANALAND - NEW EVIDENCE FROM EASTERN NEWFOUNDLAND

Recent studies have shown that the southern Burin Peninsula, in the Avalon Zone of eastern Newfoundland, is underlain by the following stratigraphie sequences: clastic sediments derived from subaerial acidic volcanic and high-level plutonic rocks; a conformably overlying submarine basaltic assemblage with alkalic affinities at the base but dominated by tholeiite low in K, Ti, and P, with intermittent occurrences of stromatolitic limestone; unconformably overlying bimodal (tholeiite to alkalic) basalt-rhyolite erupted in a subaerial environment; conformably overlying shallow water clastic sediments ranging from Infracambrian to Middle Cambrian in age. This succession indicates a Proterozoic tectonic history of prolonged continental extension and local rupturing, with eventual stabilization during the Paleozoic. Such a tectonic model applies equally well to the late Precambrian-Lower Paleozoic rocks of Gondwanaland throughout the North Atlantic region, and may account for the sporadic occurrences of ophiolitic rocks such as those of Anglesey, southern Brittany, and northwest Africa, and other possible correlatives of the Iberian Peninsula and the Lizard Peninsula of southwest England. © 1979.