Problems in the Extension of the Radiocarbon Calibration Curve (10-13 Kyr BP)

Abstract

Radiocarbon dating of varved lake sediments shows that, during the Late Glacial (10-12 kyr BP), the offset between the 14C and the absolute time scales was ca. 1 kyr. Varve counting and accelerator mass spectrometry (AMS) dating were used to build absolute and 14C time scales of sediments from two lakes-—Soppensee, Switzerland and Holzmaar, Germany. The resulting chronologies extend back to ca. 12.9 kyr cal BP (12.1 kyr BP) in the case of Soppensee and to ca. 13.8 kyr cal BP (12.6 kyr BP) in the Holzmaar record. They compare well with each other but differ significantly from the 14C-U/Th chronology of corals (Bard et al.1993; Edwards et al.1993).