Reconstructing monsoon variability during the Late Holocene at Ia Bang Lake, Central Highlands of Vietnam

Vietnam is highly sensitive to ongoing climate change, with variations in monsoon intensity exerting significant socio-ecological impacts. However, paleoclimate reconstructions from Central Vietnam remain scarce and have predominantly focused on the Central Highlands. This study presents a 4500-year sediment record from Ia Bang Lake (IAB), combining sedimentological (grain-size) and geochemical (XRF) analyses to reconstruct Late-Holocene hydroclimatic variability. A pronounced transition at ~4200 cal BP (2250 cal BCE) indicates a local response to regionally recognized drought events marking the onset of the Late-Holocene. The IAB record correlates with other Asian archives, documenting a humid Medieval Climate Anomaly (900–1300 cal CE) that likely supported societal expansion, followed by an abrupt shift to drier conditions during the early Little Ice Age (1300–1850 cal CE). Notably, a return to more humid conditions after ~1600 cal CE aligns with evidence from northern Vietnam. Contrasting geochemical proxies (Rb/Sr and Si/Ti ratios) reveal coincident drought and pluvial signals, interpreted as enhanced climatic and hydrological variability. These findings suggest that during prolonged arid phases, monsoonal rainfall became increasingly episodic and intense, promoting erosion and generating concurrent pluvial signatures. The IAB record thus underscores the complexity of Late-Holocene monsoon dynamics in Central Vietnam.