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Tectonic Plates Are Moving Faster as Earth Ages

Sep 02, 2014 11:19 AM EDT
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It seems that all this time, the Earth's tectonic plates have just been warming up, and now they've set the treadmill to a higher setting. That is, according to a new study, which claims that Earth's tectonic plates are moving faster now than at any other point in the last two billion years.

The study was recently published in the journal Precambrian Research, and shows that the average speed at which continental tectonics change latitude has doubled after a couple billion years.

This was determined after Kent Condie led a team of geochemists in assessing tectonic activity through two very different approaches. First, the researchers recorded how often new mountain belts form on Earth's surface - an indicator of colliding plates. They then compared those results with data from volcanic rocks. Magnetic readings of these rocks indicate at which latitude they formed, helping investigators piece together how quickly plates moved - releasing instances of lava in the process.

According to Condie, the researchers had expected Earth's tectonic plates to grow more slowly with age, tiring out after a turbulent youth. However, that doesn't seem to be the case.

"We expected to find that the average speed would be slowing down with time, but we didn't get that. Both speeds (rate of collision and plate shift speed) were going up," Condie told New Scientist. "It was a surprise."

Condie goes on to add that this phenomenon can be explained by an increasingly growing and vast ocean trapped beneath the Earth's mantle. This water could be encouraging rock flow - strongly counteracting the expected stiffening of the mantle as our planet ages.

Still, not everyone is convinced. Geoscience experts Martin Van Krenesndonk and Christopher Kirkland published a study in the journal Geology back in 2013 that found evidence indicating that the complete opposite was true.

This study analyzed 3,200 rock samples from around the world for evidence of tectonic activity, finding that activity peaked 1.1 billion years ago, and has been declining ever since.

However, Condie had criticized this study when it was first released, citing concerns that the sample size was too small.

"If those sample are not representative [of the average], the whole argument falls to pieces," he said.

To get to the bottom of this, we may just have to wait another two billion years. If by then there still isn't enough evidence, scientists will have to admit that the Earth is just a tricky girl to read.

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