Unknown Antarctica: What does the ice hide?
Pavel Talalay, German Leitchenkov, Nan Zhang
Geologically, Antarctica is the least explored continent in the world. Due to the extreme conditions, most of what we know about the region’s geology comes from indirect methods of remote sensing. There is no unified framework for interpreting the data collected from these methods. To date, only five bedrock samples have been taken from beneath the Antarctic ice sheet — a very small number given that Antarctica covers an area of approximately 14 million km², or more than 10% of the Earth's land surface.
Our subglacial research is focused on one of the most intriguing areas of Princess Elizabeth Land in East Antarctica — an east-west trending, high-amplitude, 550 km-long linear magnetic anomaly that marks distinct changes in the magnetic field pattern. The nature of this anomaly remained unclear, but it is thought to be related to the suture zone between Proterozoic terrains, formed during the amalgamation of the Rodinia supercontinent about one billion years ago.
At the end of the field season drilling camp was heavily covered by snow . Photo: Ilnur Abdrakhmanov.
In order to investigate the nature of this mysterious anomaly, a joint Chinese-Russian scientific project was established in 2023, with the main goal of penetrating the Antarctic ice sheet and recovering bedrock samples suitable for geological analysis. The targeted site was selected approximately 30 kilometers from the coast, near an inland route, which made logistical issues more manageable. After nearly two months of preparation and operational work, the drilling team successfully penetrated through 541 meters of ice and retrieved a unique 0.5 meter bedrock sample. Detailed mineralogical, geochemical, and petrological analysis of the bedrock sample is currently underway, and we hope to soon find the answer to the possible origin of the prominent magnetic anomaly.
In addition to new geological discoveries, several amazing findings have been made that could change our understanding of Antarctic ice sheet behavior:
First, the thickness of the basal ice — the ice adjacent to the bedrock — is much thinner (0.3 meters) than expected (7-10 meters).
Second, the upper layer of the ice sheet was found to be very cold, with a negative temperature gradient that extends to an unpredictable depth of at least 135 meters.
Third, the basal ice was solidly frozen to the bedrock, and no signs of melting were observed despite a warm-based interface being predicted as the most likely scenario by preliminary modeling. This means that the Antarctic base may be much colder than currently assumed, and ice flow and thermal models will need to be carefully reviewed.
On the left — the last piece of basal ice, which until a few minutes ago was firmly attached to the bedrock. On the right — a bedrock sample, like a torch held by the driller.
The team drilled through 541 meters of Antarctic ice. On the left — the last piece of basal ice, which until a few minutes ago was firmly attached to the bedrock. On the right — a bedrock sample, like a torch held by the driller. Photo: Yunchen Liu
No doubt, scientific bedrock drilling in Princess Elizabeth Land, East Antarctica, has revealed absolutely new information about the real conditions at the base of the ice sheet. Ideally, geological studies of Antarctic subglacial environments would be carried out through the drilling of grid holes in a systematic and regular pattern, as is typically done in geological exploration on other continents. Unfortunately, this is currently not possible in Antarctica. However, we hope that, in the near future, the most interesting subglacial geological features can be sampled through drilling.