Carbonate Rocks Resedimentation: The Relationship Between Tillite and Gravity-Flow Deposits

Carbonate resedimentation is commonly recorded in the geological record; however, glaciation-controlled carbonate resedimentation events are relatively scarce, and research on glacial resedimentation processes within carbonate platform and slope settings remains poorly understood. Through comparative analysis of the sedimentary structures, lithofacies characteristics, and assemblage relationships of tillite and gravity-flow deposits in the Ediacaran Fengtai Formation, this study summarizes the diagnostic criteria for these two deposit types and explores their genetic and evolutionary interconnections. It is proposed that glacially driven mechanical erosion and transport not only generate tillite but also supply material for gravity flows. Post-glacial sea-level rise or tectonic activity can induce destabilization of platform margins, triggering gravity-flow processes including slumping, debris flows, and turbidity currents, and thereby forming redeposited carbonate sediments. Although the two deposit types exhibit similarities in certain depositional characteristics, they differ markedly in dynamic mechanisms and depositional environments. Within the context of regional depositional evolution, tillite may act as both a precursor trigger and a sediment source for gravity-flow deposits; together, they constitute integral components of the glacial carbonate resedimentation system. Strengthened investigation into the erosion, transport, and depositional-diagenetic processes of weathered carbonate rocks, and the consequent refinement of the carbonate source-to-sink system, are of significant importance for paleoenvironmental reconstruction and the evaluation of hydrocarbon resource distribution.