Lateglacial and Holocene environmental changes in Ganga plain, Northern India

Abstract

Stable isotope, elemental geochemistry and pollen analysis of a sediment profile from Sanai lake, Central Ganga Plain, were used to document climatic oscillations during the last ∼15,000 yr in Indian subcontinent. Micaceous sandy sediments at the base of the profile indicate an active channel and humid conditions before ∼15,000 14C yr BP. The channel was abandoned during comparatively arid conditions (15,000–13,000 14C yr BP) and converted into a swamp. Enhanced humidity around 13,000 14C yr BP led to submergence of marshes and establishment of a large lake. A dry phase is also identified around an estimated age of 11,500–10,500 14C yr BP which might correspond to the Younger Dryas event witnessed globally. The Early to Mid-Holocene climatic optimum (∼10,000–5800 14C yr BP) is characterised by a lake environment. Occurence of warmth loving aquatic plants, lower δ 18O values of gastropod aragonite, heavier δ 13C org values indicate a sensitive response of the lake ecology to the climatic warming and increased rainfall. This is followed by an arid event during 5000–2000 14C yr BP and from ∼1700 14C yr BP there is evidence of climatic amelioration. The sequence and magnitude of the millenium-scale climatic oscillations documented along the lake profile correlate well with records from other parts of the Indian subcontinent indicating that the recorded changes are an expression of broad scale, probably global and climatic change.