The transition from a nearly anoxic atmosphere (<10^-5 PAL) to permanently oxygenated conditions during the Great Oxidation Event (GOE; 2.43–2.06 Ga) is partially recorded in early marine red beds. Deciphering the formational mechanisms of these deposits is crucial for understanding early marine redox fluctuations and the broader evolution of planetary habitability. Here, we present integrated geochemical data from the drill core samples, targeting the Gordon Lake and Lorrain formations of the North American Huronian Supergroup. Our results reveal that the magnesium (Mg) isotopic compositions of the Gordon Lake mudstones and Lorrain sandstones are significantly heavier than the Bulk Silicate Earth baseline (-0.25‰), fingerprinting a regime of intense continental chemical weathering. Contemporaneously, uranium and molybdenum enrichments, alongside Fe_HR/Fe_T ratios ranging from 0.10 to 0.69 in the mudstones, suggest a dynamic marine environment oscillating between oxic and ferruginous states. Given the preferential partitioning of heavy Fe isotopes into oxidized phases, the enriched heavy Fe isotopic signatures observed in these sedimentary units directly reflect the partial oxidation of marine dissolved Fe²⁺. We propose a genetic model wherein enhanced continental oxidative weathering during the early GOE increased nutrient fluxes, thereby stimulating biological productivity and driving surface water oxygenation. Subsequent upwelling of anoxic deep waters into these oxidizing settings led to the partial oxidation of Fe²⁺ to Fe³⁺, precipitating as hematite across the continental margin and ultimately resulting in the deposition of earth’s oldest red beds.