ASSESSING THE STRATIGRAPHIC INTEGRITY OF PLANKTIC AND BENTHIC 14C RECORDS IN THE WESTERN PACIFIC FOR Δ14C RECONSTRUCTIONS AT THE LAST GLACIAL TERMINATION

Abstract

ABSTRACTThere is a growing database of radiocarbon (14C) reconstructions from biogenic carbonate taken from marine sediment cores being used to investigate changing ocean circulation and carbon cycling at the end of the last great ice age. Reported here are 14C results from a marine core taken in the Makassar Straits of the western equatorial Pacific that was intended to test whether there was evidence of geologic carbon release to the ocean during the glacial termination. A thorough investigation of planktic and benthic 14C ages with stable isotopes and CT-scans revealed extensive burrowing in the upper 2 m of the core that displaced younger sediments downward by more than half a meter into the glacial section of the core. The vertical displacement is evident in both planktic and benthic fossils. However, the extent of displacement and the stratigraphic disturbance became evident only after multiple measurements of different species and genera. A CT-scan prior to sampling would be an effective screening tool to avoid sampling problem cores such as this.