# $^{81}$Kr dating at the Guliya ice cap, Tibetan Plateau

## TL;DR

This study applies advanced $^{81}$Kr radiometric dating to glacier ice at the Guliya ice cap, providing more recent age estimates that challenge previous chronologies based on $^{36}$Cl and $$O data.

## Contribution

First application of $^{81}$Kr dating on mid-latitude glacier ice, demonstrating its effectiveness with reduced sample size and providing new age constraints.

## Key findings

- $^{81}$Kr ages range from 15 to 74 ka, much younger than previous estimates.
- $^{81}$Kr dating offers a reliable alternative for ice core chronology.
- Results suggest revisions to the Guliya ice core age model.

## Abstract

We present radiometric $^{81}$Kr dating results for ice samples collected at the outlets of the Guliya ice cap in the western Kunlun Mountains of the Tibetan Plateau. This first application of $^{81}$Kr dating on mid-latitude glacier ice was made possible by recent advances in Atom Trap Trace Analysis, particularly a reduction in the required sample size down to 1 $\mu$L STP of krypton. Eight ice blocks were sampled from the bottom of the glacier at three different sites along the southern edges. The $^{81}$Kr data yield upper age limits in the range of 15-74 ka (90% confidence level). This is an order of magnitude lower than the ages exceeding 500 ka which the previous $^{36}$Cl data suggest for the bottom of the Guliya ice core. It is also significantly lower than the widely used chronology up to 110 ka established for the upper part of the core based on $\delta^{18}$O in the ice.