Continental drift: tectonic activity from 3.5 bya (Introduction)

by David Turell , Friday, September 22, 2017, 18:31 (2620 days ago) @ David Turell

A new study using titanium finds tectonic activity started 3.5 billion years ago:

https://phys.org/news/2017-09-analysis-titanium-ancient-upheaval-history.html

"A new study led by UChicago geochemists rearranges the picture of the early Earth by tracing the path of metallic element titanium through the Earth's crust across time. The research, published Sept. 22 in Science, suggests significant tectonic action was already taking place 3.5 billion years ago—about half a billion years earlier than currently thought.

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"Dauphas and his team looked at titanium in the shales over time. This element doesn't dissolve in water and isn't taken up by plants in nutrient cycles, so they thought the data would have fewer biases with which to contend.

"They crushed samples of shale rocks of different ages from around the world and checked in what form its titanium appeared. The proportions of titanium isotopes present should shift as the rock changes from mafic to felsic. Instead, they saw little change over three and a half billion years, suggesting that the transition must have occurred before then.

"This also would mark the beginning of plate tectonics, since that process is believed to be needed to create felsic rock.

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"The question about nutrients is important for our understanding of the circumstances around a mysterious but crucial turning point called the great oxygenation event. This is when oxygen started to emerge as an important constituent of Earth's atmosphere, wreaking a massive change on the planet—and making it possible for multi-celled beings to evolve.

"The flood of oxygen came from a surge of photosynthetic microorganisms; and in turn their work was fostered by a surge of nutrients to the oceans, particularly phosphorus. "Phosphorus is the most important limiting nutrient in the modern ocean. If you fertilize the ocean with phosphorus, life will bloom," Dauphas said.

"The titanium timeline suggests that the primary trigger of the surge of phosphorus was the change in the makeup of mafic rock over time. As the Earth cooled, the mafic rock coming out of volcanoes and underground melts became richer in phosphorus.

"'We've known for a long time that mafic rock changed over time, but what we didn't know was that their contribution to the crust has stayed rather consistent," Ptáček said."

Comment: If God uses evolutionary processes, to create a complex-life-giving Earth, He certainly started early enough.