delta O-18 of O-2 in a Tibetan Ice Core Constrains Its Chronology to the Holocene

Dating of the Tibetan ice cores is often challenging with great uncertainties. The significant age difference between the Guliya ice core (similar to 760 ka [thousand years]) and other Tibetan ice cores (Holocene origin) necessitates new approaches to resolve the inconsistency. Here, we present the atmospheric O-2 delta O-18 (delta O-18(atm)) profile of the 216.6 m Chongce ice core. Our data suggest that post depositional alterations significantly changed delta O-18(atm). We reject samples with melt layers, and reconstruct the delta O-18(atm) values with two extreme correction approaches: a minimum isotopic correction based on gas loss fractionation, and a maximum isotopic correction based on respiration fractionation. We consequently estimate the age range of the Chongce ice core to be 2.763-7.192 ka at the depth of 215.14 m, and similar to 3-9.799 ka at the depth of 215.61 m. Our work provides an independent line of evidence for the Holocene origin of the Chongce ice core.