Production rate variation and changes in sedimentation rate of marine core dated with meteoric 10Be and 14C

Abstract

The first measurement of meteoric beryllium-10 (10Be) using Accelerator Mass Spectrometer (AMS) is reported from PRL-AURiS (Physical Research Laboratory-Accelerator Unit for Radioisotope Studies). Strategically, the meteoric 10Be dating method can date events as old as 10 Myr, and its accuracy while dating marine sediment cores has been well tested with magnetic methods. An attempt is made for a comparative study between radiocarbon (14C) and meteoric 10Be dating methods from a 6 m long sediment core collected from the equatorial Indian Ocean. The core was dated using both radiocarbon and meteoric 10Be and results showed remarkable similarity for both methods in terms of the sedimentation rate. A continuous age offset observed within 50 kyr could be due to a continuous influx of sediment with low 10Be content and that may have caused the meteoric 10Be ages to be younger. The sedimentation rate calculated by changing the 10Be depositional flux rate from 1.5 to 2.5 × 10−2 atoms.cm−2.s−1 shows large variation, indicating the choice of appropriate 10Be depositional flux rate for the region. Additionally, being the first meteoric beryllium-10 measurements using AURiS, we have also discussed and reported the laboratory protocols and efficiency based on repeat standard and blank measurements.