Detrital Zircon Geochronology and Provenance of the Mesoproterozoic Husky Creek Formation: A fluvial sandstone recording the waning stages of one of Earth’s largest magmatic episodes.

Abstract

The Mesoproterozoic Husky Creek Formation is an interlayered redbed and basalt package that overlies a ca. 2.5 km thick, regionally extensive basaltic plateau linked to the 1.27 Ga Mackenzie Large Igneous Province. This succession provides an opportunity to study the interaction between contemporaneous fluvial sedimentation and flood-basalt volcanism. The Husky Creek Formation is approximately 1900 m thick, consisting predominantly of fluvial-channel and subordinate floodplain and eolian strata dominated, by lithic detritus intercalated with basalt flows. U-Pb dating of detrital-zircon grains collected from four stratigraphic levels in the Husky Creek Formation reveal two main age groupings: (1) a 1270 Ma peak attributed to the Mackenzie Large Igneous Province; and (2) Pre-1.6 Ga detrital zircon ages, which reflect sources from a broad region of northwestern Laurentia and are interpreted to be recycled from underlying sedimentary rocks, of the Hornby Bay Basin. An up-section decrease in the proportion of ca. 1270 Ma zircon grains, coupled with increasing sandstone compositional maturity, reflects the expansion of the drainage basin during burial of a volcanic pile, with recycling becoming more dominant as the Husky Creek Formation accumulated. The Husky Creek Formation was deposited in the waning stages of the Mackenzie Igneous Event by west flowing rivers into a geographically restricted basin above an extensive mafic volcanic plateau. This paper provides insight into fluvial basin development during the aftermath of one of Earth’s largest igneous events.