For the AMS 14C analyses, our samples were sent to the NationalIsotope Centre of the Institute of Geological and Nuclear Sciences Ltd (GNSScience) in New Zealand.
The resulting dates correspond uncalibrated years Before
Present (BP). An uncalibrated BP date cannot be used directly as a calendar
date, because the level of atmospheric 14C has not been constant during the past
60000 years, as the level of 14C is affected by variations in the cosmic ray intensity
due to variations in the Earth's magnetosphere.
To calibrate our dates we used the software CalibRev 6.0 (Stuiverand Reimer, 1993) choosing the MARINE09 calibration data set. We also have to determine
a reservoir age, this means to establish how old was the carbon of the water
before it was integrated in the carbonate that formed the shells of the
foraminifera. We choose a 400 years reservoir age and we keep it constant along
the entire core.
