Paleomonsoonal shifts during ∼13700 to 3100 yr BP in the central Ganga Basin, India with a severe arid phase at ∼4.2 ka

Abstract

We present a multiproxy record of grain size and stable carbon isotope from the Lilaur lake, Ganga Basin, India to understand the history of lake formation linked to changes in Indian monsoon precipitation during ~13714 to 3073 calibrated year before Present (cal yr BP). A comparison is made between Lilaur lake proxy record with those from other parts of South Asia as well as North Atlantic to understand extent and causes of monsoon variability and its influence on the fauna and flora of the region. Chronology of lake core was constrained using AMS 14C and optically stimulated luminescence (OSL) dates. This study suggests a transition from river to lake during ~5800 to 5189 cal yr BP which is supported by reduced precipitation with weakening of the Indian summer monsoon (ISM). This river to lake transition culminated in a severe arid phase during 4250 to 4050 cal yr BP (4.2 ka event), corresponding to enhanced El Niño activity, southward shift of the Inter-Tropical Convergence Zone, and aridification of India when the ISM was weak.