Factors Controlling the Composition and Lithofacies Characteristics of the Paleoproterozoic Bar River Formation, Huronian Supergroup

The Bar River Formation of the Paleoproterozoic Huronian Supergroup is one of the earliest sedimentary formations deposited following Earth’s Great Oxidation Event. Ten quartz-rich lithofacies were identified near Flack Lake, Ontario. Lithofacies associations resemble multiple, stacked tidal inlet fill sequences, common to mesotidal shorelines. Sedimentary structures, such as herringbone cross-stratification, reactivation surfaces, and wave ripples, support tidal and wave action. Paleocurrent patterns are bimodal to polymodal with a mean paleoflow to the southeast. Potential sources northwest of the study area include Archean Superior Province rocks and the Paleoproterozoic Lorrain Formation. Major and trace element, and oxygen isotope geochemistry support either granitoid/gneissic, or a sedimentary source derived from erosion of older granitoid rocks. Zirconium enrichment and well rounded grains indicate that recycling occurred. The relationship with the overlying Gordon Lake Formation points to a transgressive barrier island system that developed along a passive continental margin ca. 2.3 b.y. ago