Deciphering the late Quaternary climatic signature from the Ramganga paleolake, Kumaun Himalaya, India

High-resolution paleoclimate records from the Indian subcontinent are crucial for understanding the spatiotemporal variability of the Indian Summer Monsoon (ISM) from lake sediments of the north-western Himalayas, where long, continuous multiproxy records from tectonically controlled paleolakes remain comparatively limited. Here, we present a ~ 40 ka multiproxy reconstruction based on sedimentological (grain size) and geochemical proxies (Total Organic Carbon - TOC, δ13C, elemental ratios, such as Mg/Al, Ti/Al, K/Al, Fe/Al, Mn/Al) from a 5 m exposed section recovered from the tectonically influenced Ramganga Paleolake, Kumaun Himalaya. Four hydroclimatic zones are identified, capturing the major global and regional climate transitions that have occurred since the late Pleistocene. The Pre-Last Glacial Maximum (LGM) period (39.7–25 ka BP) is characterized by a weak monsoon and shallow lake conditions under a cold, arid climate. The LGM (25–18 ka BP) was characterized by intensified aridity, reduced lake productivity, and reduced runoff. Deglaciation and the Bølling–Allerød interval (~ 18–11.7 ka BP) marked a strengthening of the ISM, with a temporary weakening during the Younger Dryas. The Early Holocene recorded peak monsoon intensity and enhanced weathering, while the mid-Holocene showed a decline in precipitation. Despite regional drying, the Late Holocene in the Ramganga basin remained humid, likely due to orographic precipitation and sustained runoff. This study provides a detailed reconstruction of the ISM in the northwestern Himalaya, highlighting local hydroclimatic resilience and insights into monsoon dynamics during Quaternary climate shifts.