Search

Geochronological studies on the timing of deformation and metamorphism along the Laurentian margin have shown that the ages of metamorphic events change along-strike within the Newfoundland southern Quebec segment of the Canadian Appalachians. The Gaspé Peninsula is located at mid-point of the two extremities of this segment. New single-grain laser [sup40]Ar/[sup39]Ar plateau ages solely reflect latest Middle Late Ordovician metamorphism. Samples taken within the internal Humber zone in the Shickshock Group rocks yield [sup40]Ar/[sup39]Ar muscovite and hornblende ages ranging from 457 to 454 Ma. Samples from the Amphibolite du Diable, the metamorphic sole of the Mont Albert ophiolite, yield [sup40]Ar/[sup39]Ar muscovite and hornblende ages ranging from 459 to 457 Ma. Ordovician ages of the internal Humber zone are consistent with [sup40]Ar/[sup39]Ar ages from southern Quebec and arc interpreted as the result of the emplacement onto the margin of both the ophiolitc and its metamorphic sole. [ABSTRACT FROM AUTHOR]