Hawaiian hot spot study uncovers evidence of true polar wander
On Earth, everything is moving. The planet spins, the tectonic plates shift and the spin axis wobbles, as do the magnetic poles, which makes determining how things move a rather tricky proposition. For Rice University's Richard Gordon, this problem came up when he was trying to understand the history of the Hawaiian hot spot, the deep-mantle source of the volcanism that created the…
Recent research conducted by Rice University geophysicists Richard Gordon and Daniel Woodworth has uncovered evidence of a phenomenon called "true polar wander" on Earth. This phenomenon involves the entire solid Earth reorienting relative to its spin axis, rather than just the movement of tectonic plates or the hot spot beneath the Pacific plate.
The study, published in the Journal of Geophysical Research: Solid Earth, reveals that around 56-48 million years ago, the Earth's spin axis shifted, resulting in the formation of a bend in the Hawaiian-Emperor seamount chain. This finding challenges previous assumptions that the solid Earth's location relative to the spin axis has remained stable over the past 100 million years.
By analyzing paleomagnetic data and the apparent polar wander path of Pacific hotspots, Gordon and Woodworth determined that the Pacific plate likely jumped south in a relatively quick movement before the bend formed. However, when considering all the drivers of tectonic plate movement, it becomes clear that the Pacific plate's movement could not have been in multiple directions simultaneously.
The researchers conclude that the Pacific plate's movement is best explained by a change in the Earth's orientation relative to the spin axis, rather than the movement of the Hawaiian hot spot itself. This discovery highlights the dynamic nature of Earth's geology and suggests that substantial true polar wander can occur on a timescale of a few million years.
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