Late Holocene Tectonoclimatic driven river avulsion and lake formation impacting societies in the Central Ganga Basin

The Ganga Basin is a Food Bowl of India, marked by a dynamic landscape which has been shaped by tectonic activity and Indian Summer Monsoon (ISM). To decipher past climatic variability and possible climate-cultural linkages across South Asia, we present a high-resolution Late Holocene record from a paleooxbow lake located near Sahaswan, Uttar Pradesh. The reconstruction is supported by a robust age–depth model using 23 AMS 14 C dates from a 3.30 m deep trench representing an age from ∼4467 to 525 cal yr BP. This study is based on most comprehensive chronology from the Central Ganga Basin (CGB). Multi-proxy analyses reveal distinct episodes of reduced ISM strength during ∼4467 to 4000 cal yr BP (4.2 ka event), 3200 to 3000 cal yr BP (3.2 ka event), 1400 to 1000 cal yr BP (Dark Ages Cold Period), and 650 to 525 cal yr BP (Little Ice Age or LIA). Phases of intensified ISM prevailed between 4000 and 3200 cal yr BP, 3000 and 1400 cal yr BP (including the Roman Warm Period, ∼550 BCE to 350 CE), and from 1000 to 650 cal yr BP (Medieval Climate Anomaly). These hydroclimatic oscillations likely influenced fluvial dynamics and settlement patterns across the CGB, underscoring a strong linkage between climate variability, landscape evolution, and cultural transformations during the Late Holocene. The lake began to decrease in its size and extent since ∼800 cal yr BP and was completely dried up at the beginning of the LIA (∼650 cal yr BP), when the ISM weakened.