Diatom ecology in fast ice environment: Insights from laminated sedimentary patterns in Edisto Inlet, Antarctica

Laminated biogenic sediments are widespread in Antarctica coastal areas and generally represent the most recent depositional environments. In Edisto Inlet (northern Victoria Land, Ross Sea, Antarctica), Holocene sedimentation is marked by the presence of biogenic laminated deposits. However, the conditions controlling their formation and accumulation remain poorly understood. Here, we investigate the oceanographic significance of these laminated sequences and their relationship to past fast-ice conditions through an integrated analysis of diatom assemblages, sedimentological features, and geochemical proxies. Our findings reveal two distinct types of laminae- light and dark- each representing different depositional regimes due to different oceanographic conditions. Light laminae reflect rapid sedimentation during summers characterised by prolonged ice-free conditions and represent sediment burial over a unique summer. In contrast, dark laminae are associated with brief summer openings and represent sediment accumulation over multiple years. This study enhances our understanding of diatom ecology and sediment processes in Antarctic coastal settings, providing new insights into past fast-ice dynamics and offering a framework for interpreting modern and future trends.