Petrochronology of the East Pond Metamorphic Suite eclogite, Baie Verte Peninsula, Newfoundland, Canada

The East Pond Metamorphic Suite (EPMS) in the Baie Verte Peninsula, Newfoundland, Canada, provides a unique record of tectono-metamorphic processes during the Middle Ordovician Taconic orogeny. This study utilizes petrochronology to investigate the complex evolution of the EPMS eclogites, revealing new insights into the subduction and exhumation history of parts of the early Paleozoic Laurentian margin. U-Pb geochronology of zircon, rutile, titanite, and apatite—integrated with trace element data—as well as Rb-Sr mineral isochrons constrain the timing and conditions of metamorphism. We also document late Taconic magmatism on the Laurentian margin, indicated by zircon U-Pb dates from pegmatite intrusions crosscutting the eclogite boudins at ca. 444 Ma. These metamorphic rocks exhibit a multistage metamorphic history with eclogite-facies conditions at ca. 483 Ma, followed by retrograde amphibolite-facies overprint during protracted deformation. Subsequent stages of exhumation and cooling are recorded by Rb-Sr mineral isochrons at ca. 460 Ma as well as titanite and apatite at ca. 459 Ma and ca. 452 Ma, respectively. New constraints on exhumation rates indicate that a protracted phase of residence at ultrahigh-pressure conditions was followed by a short-lived pulse of rapid ascent and late Taconic magmatism, suggesting that exhumation of the EPMS was buoyancy driven and modulated by transient thermal perturbations linked to changes in deep subduction dynamics. We establish a new chronological framework providing insights into the tectono-metamorphic evolution of the Laurentian margin and the Notre Dame arc during the Middle Ordovician Taconic orogeny. Additionally, we link tectonic and magmatic events during subduction and collision, highlighting the complex interplay between these processes at different crustal levels.