Modeling the stratigraphic record of glacioeustatic sea-level rise and sediment starvation following Snowball Earth

Abstract

Cap carbonates overlying Neoproterozoic Snowball Earth glacial deposits are often interpreted as reflecting either rapid deglaciation or prolonged periods of post-glacial sediment starvation. To evaluate these contrasting depositional models, we use 3D stratigraphic forward modeling to assess the impact of glacioeustatic sea-level rise on continental shelf sedimentation. Our models, which incorporate real-world sediment supply data and margin configurations, demonstrate that the rapid, high-amplitude sea-level rise characteristic of a Snowball Earth deglaciation triggers prolonged periods of terrigenous sediment starvation on continental shelves. The duration of this sediment-starved period is positively correlated with shelf accommodation (highest in glacially influenced settings) and negatively correlated with sediment supply (lower in post-glacial settings). These results suggest that extensive hiatuses would have occurred across many post-Snowball Earth margins. While our models do not simulate the geochemical mechanisms driving cap carbonate precipitation, they show that general carbonate deposition during the siliciclastic hiatus is typically sharp-based, thickens basinward, and has a more gradational upper contact. These trends align with observations from Australian cap carbonate sequences, suggesting that sediment starvation played a role in their genesis. This research underscores the potential for extended periods of sediment starvation following Snowball Earth events and highlights the critical need to investigate the broader implications of such events on Earth's systems during this pivotal phase of its evolution.