Tucson Standard

Scientists have long sought to understand the secrets hidden deep within Earth's mantle, a layer that lies 1,800 miles beneath the surface. Although it is impossible to physically reach this area with current technology, researchers have developed methods to study it indirectly. Recent findings published in Nature Communications Earth and Environment shed light on a specific region of the mantle known as the Zealandia-Antarctic domain.

Geologists have identified distinct groupings of rock called domains within the uppermost 250 miles of Earth's mantle. However, the exact number of these domains and their boundaries remain unclear. The new research suggests that the Zealandia-Antarctic domain extends further than previously thought, reaching north of Australia and west of New Zealand. It covers an area approximately twice the size of Africa.

The study was conducted by Jonny Wu from the University of Arizona's Department of Geosciences, Jeremy Tsung-Jui Wu from the University of Nevada Reno, and lead author Shengping Qian from China's Tongji University. "This mantle domain appears to have its distinctive geochemical signature because it was mostly isolated under oceans and did not have much interaction with continents traveling across it in the past 400 million years," said Jonny Wu.

Researchers discovered unexpected results while examining rocks from the Philippine Sea Plate using remote-operated submersibles. They noted discrepancies between expected locations based on current understanding and actual findings, prompting them to create a map showing ancient eruption sites.

Jonny Wu commented on their discovery: "What's cool about this paper is that we found a plate that moved across a large part of the mantle, crossing all three mantle domains that we know about."

These findings suggest that some domains may date back to over 250 million years ago during the Paleozoic Era. Stable mantle domains like these could serve as references for understanding more dynamic movements within Earth's history. As Wu explained, "When we try to rewind the clock to travel back into geologic time, we need references."

Such discoveries could ultimately help scientists create clearer maps illustrating how movements within Earth's interior have shaped its surface over millions of years.