Environmental evolution of a coastal lake in the Larsemann Hills, East Antarctica during the Holocene: a multi-proxy perspective

Coastal lakes in Antarctica provide exceptional archives of past climatic and environmental change. Their evolution is closely linked to variations in relative sea level (RSL) driven by deglaciation, making them ideal natural laboratories for investigating marine-lacustrine transitions and reconstructing ancient sea levels. This study presents a high-resolution reconstruction of mid- to late-Holocene paleoenvironmental changes from Heart Lake, a low-elevation coastal lake in the Larsemann Hills, East Antarctica. Multiple proxies, including diatom assemblages, environmental magnetic parameters, geochemical indicators, and sedimentological features, were employed to decipher the regional paleoclimate and environmental history. The lake existed as a submarine basin from approximately 6.37 to 3.07 cal ka BP. Around 4.3 cal ka BP, increasing chemical weathering indices suggest a trend toward warmer conditions in the lake. The first appearance of lacustrine diatoms around 3.07 cal ka BP marks the onset of environmental transition within the basin. By ~ 1.75 cal ka BP, the lake had become an isolated freshwater system. This shift from a marine to a lacustrine environment was likely driven by a post-glacial isostatic rebound and the consequent uplift of the land surface.