²³⁰Th/²³⁴U and ¹⁴C dating of the Quaternary carbonate deposits of Saurashtra, India

Abstract

Seventy-eight samples from Quaternary carbonate deposits of the Saurashtra peninsula in Gujarat State, India, were dated by three variants of the ²³⁰Th/²³⁴U technique: (I) using a 5% acetic acid leaching method and applying a correction for detrital Th; (II) using 1 M HC1 leaching with corrections for detrital U and Th; and (III) the isochron method. Twenty-one samples were also used for ¹⁴C age determination. About forty reliable ²³⁰Th/²³⁴U ages were obtained ranging from 45.9 to 204 ka. Of the 21 samples used for ¹⁴C dating, twelve yielded ages > 30 ka whereas the rest ranged from 12.1 to 21.5 ka. Based on the ²³⁰Th/²³⁴U ages it is inferred that miliolite formation took place mainly in three episodes: 50-70, 75-115 and 140-210 ka. Considering the available evidence in favour of tectonic instability of Saurashtra, uplift rates of the miliolite locations are calculated to range from 0.23 to 2.2 mm a⁻¹, which are in good agreement with rates obtained for other regions based on similar studies.