Age of Saurashtra miliolites by U-Th decay series methods: possible implications to their origin

The miliolite deposits of Saurashtra have been dated by 234U, 230Th, 231Pa and 14C methods. Concordant ages of approximately 105 years using the U decay series isotopes are obtained which agree with the ages of the coral reefs of Okha-Dwaraka coast suggesting a contemporaneous origin for both. The lower 14C ages (<= 40,000 years) may be due to a recent influx of seawater or ground water. Quartz and clay minerals together constitute only <= 10% by weight, as such the aeolin characteristics of quartz grains may not be relevant to the origin of the miliolites. (auth.)