Astronomical forcing associated with Earth’s orbital and inclination parameters (Milankovitch forcing) exerts a major control on climate as recorded in the sedimentary rock record, but its influence in deep time is largely unknown. Banded iron formations, iron-rich marine sediments older than 1.8 billion years, offer unique insight into the early Earth’s environment. Their origin and distinctive layering have been explained by various mechanisms, including hydrothermal plume activity, the redox evolution of the oceans, microbial and diagenetic processes, sea-level fluctuations, and seasonal or tidal forcing. However, their potential link to past climate oscillations remains unexplored. Here we use cyclostratigraphic analysis combined with high-precision uranium–lead dating to investigate the potential influence of Milankovitch forcing on their deposition. Field exposures of the 2.48-billion-year-old Kuruman Banded Iron Formation reveal a well-defined hierarchical cycle pattern in the weathering profile that is laterally continuous over at least 250 km. The isotopic ages constrain the sedimentation rate at 10 m Myr⁻¹ and link the observed cycles to known eccentricity oscillations with periods of 405 thousand and about 1.4 to 1.6 million years. We conclude that long-period, Milankovitch-forced climate cycles exerted a primary control on large-scale compositional variations in banded iron formations.

与地球轨道和倾角参数相关的天文强迫（米兰科维奇强迫）对沉积岩记录中记录的气候产生了重大控制，但其在深部时间的影响在很大程度上是未知的。带状铁地层，富含铁的海洋沉积物超过 18 亿年，提供了对早期地球环境的独特见解。各种机制解释了它们的起源和独特的分层，包括热液羽流活动、海洋的氧化还原演化、微生物和成岩过程、海平面波动以及季节性或潮汐强迫。然而，它们与过去气候波动的潜在联系仍未得到探索。在这里，我们使用环形地层分析结合高精度铀铅测年来研究米兰科维奇强迫对其沉积的潜在影响。具有 24.8 亿年历史的库鲁曼带状铁组的野外曝光揭示了风化剖面中定义明确的分级循环模式，该模式在至少 250 公里范围内横向连续。同位素年龄将沉降速率限制在 10 m Myr^-1并将观测到的周期与已知的离心率振荡联系起来，周期为 40.5 万年和大约 1.4 到 160 万年。我们得出结论，长期的米兰科维奇强迫气候周期对带状铁地层的大规模成分变化发挥了主要控制作用。