Deep ice-core drilling to 800 m at Dome A in East Antarctica

Zhengyi Hu,Chunlei An,Guitao Shi,Chuanjin Li,Ke Liu,Tianming Ma,Xiaopeng Fan,Nan Zhang,Pavel Talalay,Jinhai Yu,Yuansheng Li,Cheng Yang,Bing Li,Bowen Liu

doi:10.1017/aog.2021.2

Abstract

AbstractA deep ice core was drilled at Dome A, Antarctic Plateau, East Antarctica, which started with the installation of a casing in January 2012 and reached 800.8 m in January 2017. To date, a total of 337 successful ice-core drilling runs have been conducted, including 118 runs to drill the pilot hole. The total drilling time was 52 days, of which eight days were required for drilling down and reaming the pilot hole, and 44 days for deep ice coring. The average penetration depths of individual runs were 1 and 3.1 m for the pilot hole drilling and deep ice coring, respectively. The quality of the ice cores was imperfect in the brittle zone (650−800 m). Some of the troubles encountered are discussed for reference, such as armoured cable knotting, screws falling into the hole bottom, and damaged parts, among others.

Highlights

Ice cores record information on climate system components at a high resolution and in a stratigraphic sequence, even providing direct access to entrapped atmospheric paleo air
Previous studies indicate that drill sites near ice divides with smooth bedrock topography are favourable, which suggests that dome areas are ideal locations (Dahl-Jensen, 2018)
Bell and others (2011) proposed two diametrically opposed views: (1) the basal ice uplift caused by accretion moves older ice to a higher position in the ice sheet, increasing the potential for the preservation of very old ice in the ice sheet; and (2) the extensive melting necessary to support the freezing process may destroy ice containing paleoclimate records

Summary

Introduction

Ice cores record information on climate system components at a high resolution and in a stratigraphic sequence, even providing direct access to entrapped atmospheric paleo air. Searching for the oldest ice core, with a 1.5 Ma record of climate and greenhouse gases, is one of the priority projects within the International Partnerships in Ice Core Sciences (Fischer and others, 2013) and was proposed during two initial workshops in 2004 and 2005 To address this challenge, China established the Kunlun station at Dome A in January 2009; the deep ice-core drilling site was selected with limited initial knowledge. The most important task for the Chinese inland expedition team is the deep ice coring operation at Kunlun station. There have effectively been 118 shallow ice-core drilling runs, with minimum and maximum penetration depths of 0.1 and 1.45 m, respectively, where 63.6% of the retrieved core lengths were > 1 m (Fig. 8). This season was mainly utilised for testing the deep ice-core

4–18 January 2016

3–21 January 2017

Findings

Conclusions and prospects