Abstract. An accurate chronology is the essential first step for a sound understanding of ice core records, however, dating of ice cores drilled from the high elevation glaciers is challenging and often problematic, leading to great uncertainties. The Guliya ice core, drilled to bedrock (308.6 m in length) from the northwestern Tibetan Plateau (TP) and widely used as a benchmark for paleoclimate research, is believed to reach > 500 ka (thousand years) at its bottom. Meanwhile other Tibetan ice cores (i.e., Dasuopu and East Rongbuk in the Himalayas, Puruogangri in the central TP, and Dunde in the northeastern TP) are mostly of the Holocene origin. In this study, we drilled ice cores to bedrock from the Chongce ice cap ~ 30 km from the Guliya ice core drilling site. We performed measurements of 14C, 210Pb, tritium and β-activity for the ice cores, and used these values in a two-parameter flow model to establish the ice core depth-age relationship. The modeled ages of two Chongce ice cores at the ice-bedrock contact are 8.3 ± 6.2/3.6 ka B.P. and 9.0 ± 7.9/3.6 ka B.P. respectively. The significant discrepancy between the Guliya and all other Tibetan ice core chronologies calls for a revisit of this legend ice core record.
A 36Cl Profile in Greenland Ice from AD 1265 to 1865