New Miscellany: fine tuning from plate tectonics (General)

by David Turell , Wednesday, March 19, 2025, 14:48 (15 days ago) @ dhw

DAVID: This universe will allow life wherever it is habitable. We agree but you don't like it served up the way I view it.

dhw: I don’t like demonstrably false statements, and the fact that they are 30 years old does not make them any more acceptable. Yes, the universe will allow life wherever it is habitable, but a) the entire universe is not habitable, and (b) even if a place is habitable, that still doesn’t mean it’s fine-tuned for life, because the biochemical components of which all living things are made must also be fine-tuned.

A new study of how plate tectonics started:

https://www.science.org/content/article/deep-earth-layer-may-have-primed-planet-plate-t...

"New research published last week in Geology suggests a deep Earth layer called the mantle transition zone may be the culprit, based on an analysis of water trapped in the newly formed sea floor.

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"Earth didn’t always have tectonic movement. The planet’s tumultuous early years saw a magma ocean give way to the watery world we know. But today, the liquid water in lakes, rivers, and oceans combines for only about one-quarter of the planet’s total water. The rest is tied up as hydrogen and hydroxide ions, water’s ingredients, bound inside the minerals that make up Earth’s interior.

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"Water weakens these rocks and lets them bend and slide under one another—a crucial feature of plate tectonics called subduction. In addition, water makes rocks less viscous, helping them break through the crust’s hardest layers, rise through as magma, and harden into new land.

Esteban Gazel, a geochemist at Cornell University, and his colleagues study water’s role in "plate tectonics by examining the water content of magmas, which records the temperatures and pressures a given magma felt as it journeyed through Earth. Tiny bits of cooled magma trapped within rocks, called melt inclusions, tell this story best.

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"In that zone, the extraordinary pressure and temperature create minerals with high water-storage capacities, soaking up water like a sponge, Gazel says. The researchers suggest that in ancient Earth, plumes of water-rich rock could have risen from the mantle transition zone. The water in this plume could then have weakened the rigid rocks that capped Earth’s surface at the time, allowing oozing magma to break out, essentially providing the grease to start Earth’s geological machinery. The mantle transition zone was then replenished as tectonic plates subducted, dragging water-filled minerals back down into Earth."

Comment: a fascinating study. Our life must have plate tectonics to arrive and survive. A part of fine tuning.