C¹²-enrichment along intraformational unconformities within Proterozoic Bhander Limestone, Son valley, India and its implication

Abstract

The late Proterozoic Bhander Limestone in Son valley, India developed in a very shallow epeiric ramp setting that partially emerged time and again above the sea surface. Landward extensive karstified sediments attest to three events of considerable regressions.The resultant intraformational unconformities are characterized by C¹²-enrichment in the scale of their Phanerozoic equivalents. Early diagenetic void-fill cements in these karsts are even more enriched. These sediments and cements in relatively seaward part show relatively lesser degree of enrichment, possibly because of shorter duration of exposure. The late Proterozoic meteoric water seems to have turned rich in C¹² with contribution from land plants similar to Phanerozoic meteoric water.