A 75 Ka Record of Palaeoclimatic Changes Inferred from Crystallinity of Illite from Nal Sarovar, Western India

The crystallinity of the clay mineral illite, which is a climatically sensitive parameter, was studied for palaeoclimatic inferences from a core raised from Nal Sarovar in western India. The changes in crystallinity of illite in the top 3m of the core showed that the climate was wetter than present from ∼6.3-4.6 ka BP and was followed by a relatively dry phase which has continued up to the present. These palaeoclimatic observations are largely similar to those obtained from δ¹³C and C/N ratio variations in the top 3m of the core. From the deeper (>3m) section, a wet spell around 50 ka BP was identified in an otherwise continuous spell of aridity between 7 and 73 ka BP. The presence of a red bed dated to -50 ka BP (depth 1285-1324 cm) also suggested that the climate was wet followed by dry conditions during this period.

This interpretation of palaeoclimatic changes deciphered from the Nal Sarovar core differs in some detail from the Rajasthan palaeoclimatic record and that available from south India.