Privileged Planet: earliest date for plate tectonics start (Introduction)

by David Turell , Friday, May 14, 2021, 21:11 (1070 days ago) @ David Turell

Studying zircons:

https://phys.org/news/2021-05-earth-oldest-minerals-date-onset.html

"Scientists led by Michael Ackerson, a research geologist at the Smithsonian's National Museum of Natural History, provide new evidence that modern plate tectonics, a defining feature of Earth and its unique ability to support life, emerged roughly 3.6 billion years ago.

"Earth is the only planet known to host complex life and that ability is partly predicated on another feature that makes the planet unique: plate tectonics. No other planetary bodies known to science have Earth's dynamic crust, which is split into continental plates that move, fracture and collide with each other over eons. Plate tectonics afford a connection between the chemical reactor of Earth's interior and its surface that has engineered the habitable planet people enjoy today, from the oxygen in the atmosphere to the concentrations of climate-regulating carbon dioxide. But when and how plate tectonics got started has remained mysterious, buried beneath billions of years of geologic time.

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"A zircon's age can be determined with a high degree of precision because each one contains uranium. Uranium's famously radioactive nature and well-quantified rate of decay allow scientists to reverse engineer how long the mineral has existed.

"The aluminum content of each zircon was also of interest to the research team. Tests on modern zircons show that high-aluminum zircons can only be produced in a limited number of ways, which allows researchers to use the presence of aluminum to infer what may have been going on, geologically speaking, at the time the zircon formed.

"After analyzing the results of the hundreds of useful zircons from among the thousands tested, Ackerson and his co-authors deciphered a marked increase in aluminum concentrations roughly 3.6 billion years ago.

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"Prior research on the 4 billion-year-old Acasta Gneiss in northern Canada also suggests that Earth's crust was thickening and causing rock to melt deeper within the planet.

"'The results from the Acasta Gneiss give us more confidence in our interpretation of the Jack Hills zircons," Ackerson said. "Today these locations are separated by thousands of miles, but they're telling us a pretty consistent story, which is that around 3.6 billion years ago something globally significant was happening.'"

Comment: Plate tectonics support life. Life may have appeared as early as 3.8 billion years ago. This means life and supporting tectonics arrived simultaneously. Sure looks like a designed plan, doesn't it?.