A Giant Rock Structure Beneath Antarctica Could Potentially Affect Sea Levels

Scientists have discovered a massive granite structure buried beneath the Pine Island Glacier ice cap in West Antarctica. This ancient granite measures about 100 km in width and is approximately 7 km thick. It is estimated that this granite was formed approximately 175 million years ago during the Jurassic period. This discovery was made by a team from the British Antarctic Survey using a combination of ground-based geological data and airborne geophysical data.

The investigation began with researchers' discovery of unusual pink granite boulders in the nearby Hudson Mountains, which is a volcanic range located close to Pine Island Glacier. Granite is rarely present in this part of Antarctica, which immediately drew attention towards it. When the rocks were analyzed and dated, researchers found that they were about 175 million years old, which might tell us that they likely originated from a much larger granite body buried beneath the ice sheet. These boulders provided the first clue that a significant geological structure might exist below the glacier, as reported by scientists from the British Antarctic Survey.

Researchers conducted airborne gravity surveys across Pine Island Glacier to investigate further. These surveys measure small variations in Earth’s gravitational field, which can show differences in rock density beneath the surface. When scientists analyzed the data, they detected a large gravitational anomaly beneath the glacier that matched the expected density of granite. The results confirmed that a large granite formation is present and lies deep beneath the West Antarctic Ice Sheet (British Antarctic Survey).

It is extremely important for scientists to understand the bedrock below Antarctica to study glacier dynamics. The shape, composition, and hardness of rocks beneath the ice can have a great influence on how glaciers move, how quickly they melt, and how water flows beneath them. This is particularly important in the case of Pine Island Glacier, which is one of the fastest-changing glaciers in Antarctica and contributes massively to ice loss from the West Antarctic Ice Sheet. Granite is typically harder and more resistant to erosion than many other rock types. Because of this, the newly identified granite body may affect how the glacier interacts with the ground beneath it. The structure could influence friction at the base of the ice as well as the pathways through which meltwater flows beneath the glacier. These factors are important for scientists trying to predict how quickly Antarctic glaciers might retreat as global temperatures rise (Phys.org).

The discovery provides new insight into Antarctica’s ancient history: About 175 million years ago, during the Jurassic period, when dinosaurs roamed, the continents were rearranged into a different configuration as part of an ancient supercontinent called Gondwana. The geological events of that time probably constructed the granite massif long before the continent was locked under thick ice. Scientists say that learning about these unseen structures helps us fine-tune our understanding of how glaciers behave when the oceans warm up. Scientists can better predict what will happen to the ice sheets in the future and what role the West Antarctic Ice Sheet plays in the global sea-level rise by mapping the underlying bedrock beneath the ice sheets.