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The Proterozoic evolution of Laurentia involved intermittent orogens and arc-related crustal growth along a modern-style convergent margin, termed the Great Proterozoic Accretionary Orogen (GPAO). The major lithotectonic provinces of the GPAO in the United States are exposed as telescoped equivalents within the thrust stack of the Grenville Province in Canada. We report zircon U Pb and Lu Hf isotope analyses for two orthogneisses and one quartzite from Archean and Paleoproterozoic domains in the gneiss belt of the SW Grenville Province, Canada. The data constrains Paleoproterozoic crustal growth and sedimentation for this part of the Laurentian margin. The orthogneisses have similar zircon U Pb and Lu Hf isotope systematics that reflect igneous reworking (ca. 1700–1660 Ma) of a Penokean aged (ca. 1.9 Ga) depleted mantle derived source, along with metamorphic reactivation at both ca. 1.45 Ga and during the Grenville Orogeny (1.2–1.0 Ga). The quartzite has a bimodal Paleoproterozoic (2.1–1.8 Ga) and Archean (> 2.5 Ga) detrital zircon age spectrum. The Paleoproterozoic detrital zircon grains have a wide range of Hf(t) compositions (εHf(t) = −12.5 to 10) reflecting co-eval interaction of Archean and depleted Paleoproterozoic sources, contrasted by a more restricted range for the Archean population (εHf(t) = −7 to 4). The new data support the presence of reworked ca. 1.9 Ga depleted mantle sources in the Paleoproterozoic Parautochthon, which extend further east than previously thought. They also identify correlations amongst detrital zircon age spectra and Hf isotope compositions in quartzites from different locations of the Archean Parautochthon. • Juvenile Penokean sources (∼1.9 Ga) extend into the SW Grenville Province. • Penokean (∼1.9 Ga) crust-mantle mixing recorded by detrital zircon Lu Hf isotopes. • Erosion and redeposition of sedimentary sinks can mask orogen detrital systematics. [ABSTRACT FROM AUTHOR]

New whole-rock Sr-Nd-Pb-O isotope data are combined with previously published results for Sr and Nd isotopes and major and trace element chemistry to examine the petrogenetic and tectonic environments of a suite of ca. 980 Ma potassic to ultrapotassic dykes (PUD) from the Canyon domain, central Grenville Province in Canada. The PUD suite can be divided into two geochemically distinct groups that exhibit characteristic source mineralogy, depth of partial melting, and multi-stage metasomatism of heterogeneous mantle sources. Major and trace element data suggest involvement of both fertile and depleted sources involving spinel and garnet peridotite, while trace element and isotope data indicate long-term LREE and LILE enrichments and HFSE depletions in ancient subduction settings. Low time-integrated Rb/Sr, Sm/Nd, and U/Pb ratios suggest enriched mantle EM-I metasomatized by ancient subduction of continental upper crust and/or carbonate sediments. A latest phase of fluid/melt metasomatism is attributed to a late-Grenvillian intracontinental subduction and limited lithospheric extension. The late-Grenvillian tectonic setting is proposed here to be characterized by shallow-angle underthrusting of the foreland beneath the Grenvillian hinterland, where SCLM, initially of Proterozoic age and eventually of Late Archean age, became transported beneath the orogenic core. The intracontinental collision was short-lived and probably terminated because of buoyancy constraints related to the refractory character of the subducted Archean lithospheric mantle. • Late Grenvillian potassic to ultrapotassic dykes from the orogenic hinterland in Canada are geochemically and isotopically characterized. • Late Archean and Proterozoic lithospheric mantle sources record ancient subduction metasomatism and late fluid metasomatism prior to dyke emplacement. • Tectonic setting characterized by shallow-angle or flat underthrusting of the foreland lithosphere beneath the hinterland. [ABSTRACT FROM AUTHOR]