Early subduction dynamics recorded by the metamorphic sole of the Mt. Albert ophiolitic complex (Gaspé, Quebec)

Abstract The metamorphic sole of the Mt. Albert ophiolitic complex (Gaspe peninsula, Quebec, Canada) is a sliver of Ordovician oceanic crust accreted to the base of an incomplete ophiolitic sequence, along a suture zone throughout the north-eastern Appalachians linked to the Taconian orogeny. A detailed mineralogical study of the rocks in the metamorphic section of the sole is provided in this publication: these rocks record valuable information in terms of petrological processes and conditions of accretion, with limited retrogression. The petrology of the metamorphic sole shows that it originates from ocean floor and that it is the equivalent of the Shick-Shock volcanics group, metamorphosed to granulite/higher amphibolite facies. Presence of aluminosilicate bearing metapelites allows constraining pressure conditions in a more robust way than in the case of the famous Semail ophiolite (Oman). Thermobarometric estimates for peak metamorphic conditions for the metamorphic sole of the Mont Albert ophiolitic complex indicate temperatures above 800 °C close to the contact with the overlying peridotite, decreasing to ~650 °C within