Applicability of meteoric 10Be in dating marine sediment cores

Quaternary paleoclimatic and paleomagnetic reconstructions using marine sediment cores require appropriate dating techniques in order to build the chronology. Due to the widespread use of the radiocarbon dating method, the majority of studies focusing on paleo reconstructions are restricted to the last 50 ka. There are very few methods those can be used to obtain chronology beyond the radiocarbon dating limit. Marine sediment cores as old as 10–12 Ma can be dated using 10Be because of its comparatively long half-life of 1.39 Ma. However, there are various intricacies which restrict this method to date young marine sediment cores (<1 Ma). In this study, we provide the findings of measurements obtained for beryllium isotopes (10Be and 9Be) in a sediment core from the central Indian Ocean. It was observed that the changes associated with the decay of 10Be are much smaller than the Be isotopic fluctuations related to variations in geomagnetic field intensity. While ignoring the points showing high anomalous 10Be/9Be ratios, a continuous decrease in the 10Be/9Be ratio with depth was observed as a function of the decay of 10Be. Based on the decay of 10Be, the sediment core was dated to be ∼350 ka (at 570 cm depth) with an average sedimentation rate of 1.6 cm/ka.