An outcrop of bedded 3.23-billion- to 3.26-billion-year-old barite in greenstone (the Mapepe Formation in the Barberton
Greenstone Belt) in South Africa. The rock has barite domes within the formation that were analysed by the team.
Posted on 04/26/2021 11:55:18 PM PDT by LibWhacker
The first emergence and persistence of continental crust on Earth during the Archaean (4 billion to 2.5 billion years ago) has important implications for plate tectonics, ocean chemistry and biological evolution. This happened about a half-billion years earlier than previously thought, according to new research being presented at the EGU General Assembly 2021.
Once land becomes established through dynamic processes like plate tectonics, it begins to weather and add crucial minerals and nutrients to the ocean. A record of these nutrients is preserved in the ancient rock record. Previous research used strontium isotopes in marine carbonates, but these rocks are usually scarce or altered in rocks older than 3 billion years.
Now, researchers are presenting a new approach to trace the first emergence of old rocks using a different mineral: barite.
Barite forms from a combination of sulfate from ocean water mixing with barium from hydrothermal vents. Barite holds a robust record of ocean chemistry within its structure, useful for reconstructing ancient environments. "The composition of the piece of barite we pick up in the field now that has been on Earth for 3.5 billion years is exactly the same as it was when it when it actually precipitated," says Desiree Roerdink, a geochemist at University of Bergen, Norway, and team leader of the new research. "So in essence, it is really a great recorder to look at processes on the early Earth."
An outcrop of bedded 3.23-billion- to 3.26-billion-year-old barite in greenstone (the Mapepe Formation in the Barberton
Greenstone Belt) in South Africa. The rock has barite domes within the formation that were analysed by the team.
An outcrop of bedded 3.23-billion- to 3.26-billion-year-old barite in greenstone (the Mapepe Formation in the Barberton Greenstone Belt) in South Africa. The rock has barite domes within the formation that were analysed by the team. Credit: Desiree Roerdink Roerdink and her team tested six different deposits on three different continents, ranging from about 3.2 billion to 3.5 billion years old. They calculated the ratio of strontium isotopes in the barite, and from there, inferred the time where the weathered continental rock made its way to the ocean and incorporated itself into the barite. Based on the data captured in the barite, they found that weathering started about 3.7 billion years ago—about 500 million years earlier than previously thought.
"That is a huge time period," Roerdink says. "It essentially has implications for the way that we think about how life evolved." She added that scientists usually think about life starting in deep sea, hydrothermal settings, but the biosphere is complex. "We don't really know if it is possible that life could have developed at the same time on land," she noted, adding "but then that land has to be there."
Lastly, the emergence of land says something about plate tectonics and the early emergence of a geodynamic Earth. "To get land, you need processes operating to form that continental crust, and form a crust that is chemically different from the oceanic crust," Roerdink says.
These guys just throw this crap out to keep their phony baloney jobs.
Always liked my continents crusty. A continent without crust is just a piece of limp land.
Ping.
Remember, the science is
...settled.
/runs for exit, ducking for cover>
It’s hard to tell if the author doesn’t know what she’s talking about, and is trying to cover it up, or if the researchers are the culprits. It could be both.
I told those guys to use Barite like 6 years ago.
WHAT!? “Science” was WRONG! /s
Thanks Redcitizen.
A half billion here, a half billion there and pretty soon you’re talkin’ real time!...................
My studies say it was closer to 491 million years ago.
In before it can’t possibly be older than 6,025 years this October...
Ev? ;^)
Interesting-they admit they have likely miscalculated-so the science isn’t settled...
If the science isn’t settled on the time solid rock formed continents, then it damn sure can’t be settled when it comes to insubstantial things like climate change, man-made or otherwise...
Yes, because "settled science" is strictly a political term, or a religious one -- nothing to do with the scientific method.
Imagine you’re a young, insecure Earth and someone comes up to you, “Hey, your crust is showing.” That can be devastating.
Well, when do they figure the planets collide, moon blob gets thrown up thing happened? If that’s what happened?
I seriously doubt that any real scientist has even attempted to prove the man-made climate change theory/theories using the scientific method-high school science class used to show how to use the scientific method to prove a theory-I guess not any more...
In the creation myth of the Heliopolitan form of ancient Egyptian religion, Benben was the mound that arose from the primordial waters Nu upon which the creator deity Atum settled. The Benben stone (also known as a pyramidion) is the top stone of the pyramid.
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