Sediment Provenance using Detrital-Zircons, Nd-Sr Isotopes, and Bulk Rock Geochemistry: Implications for Sediment Routing in the Neoproterozoic Windermere Supergroup, Southern Canadian Cordillera

Abstract

High-resolution sampling of Neoproterozoic basin-floor to slope deposits in the Windermere Supergroup, east-central British Columbia indicates three distinct stratigraphically ascending clusters suggesting temporal changes in sediment provenance. Assemblage 1 has a characteristic northwestern Laurentia bimodal detrital zircon distribution with low εNd values, and intermediate to mafic igneous provenance as indicated by discriminant function analysis of major elements, low Th/Sc and Zr/Sc, high Co/Th, and high Cr abundance. This suggests derivation from western Laurentia basement rocks and Archean mafic and ultramafic suites from the Central Hearne province supracrustal belt. Assemblage 2, although compositionally similar, has an additional 655 Ma detrital zircon age population, higher εNd values, and felsic igneous to recycled provenance, suggesting a significant Neoproterozoic igneous rift-related source. Assemblage 3 marks the end of input from the juvenile ca. 655 Ma source and felsic igneous to recycled provenance, suggesting a return to western Laurentian cratonic sources.