A Tonian volcano-sedimentary succession in Newfoundland, eastern North America: A post-Grenvillian link to the Asgard Sea?

Early Tonian bimodal volcanic and sedimentary rocks (the Pine Pond succession) were identified in the Appalachians of eastern Laurentia for the first time, with U-Pb ages of igneous zircon at 951.4 +/- 9 Ma for a felsic tuff and 952 +/- 10 Ma for a crosscutting granite sheet. This Neoproterozoic succession is part of the East Pond metamorphic suite on the Baie Verte Peninsula (Newfoundland, Canada), which also contains 1491 Ma orthogneiss and is consistent with deposition over Mesoproterozoic basement in a pre-Iapetan extensional setting. Collectively, the data suggest a correlation with the southern Labrador Pinware terrane of the Grenville Province, where 1.52-1.46 Ga bedrock is intruded by 975-950 Ma granite. In addition, the age and location of this 952 Ma succession are consistent with deposition on the western margin of the Asgard Sea. Thus, the Pine Pond succession provides a link between key events in the assembly of the supercontinent Rodinia: the end of the Grenville orogeny, which led to the amalgamation of Laurentia and Amazonia, and the early Neoproterozoic evolution of the Asgard Sea, which separated Laurentia and Baltica.