Ancient Rocks were published when Earth’s plate tectonics began


Tosh and Munker developed a powerful new method of finding tungsten traces from ancient stones. Then they went to look for the stone.

They first analyzed Archian rocks collected in the Isua region of western Greenland. Touch has been analyzing the samples for 11 months, but in the end his The tungsten-182 data was flat, There is no significant variation in the samples. The researchers speculated that the rocks in Greenland had become distorted and heated in their history, shaking their geochemical data.

They needed better rock, so they headed for Pilbar in Western Australia. “It contains some of the best preserved Archean rocks on the entire planet,” Moncar said. “They didn’t look very hot when compared to the same rocks of that era.”

“I was really interested in looking for samples that didn’t display the same values ​​over and over again,” Tush said.

Directed by co-author Martin van Cranandonak At the University of New South Wales, the team crossed the outback in an off-road truck, touring the rusty-red outcrops where ancient volcanic rocks and vegetation mimicked each other: extrinsic spinifex shrubs are part of the silica that makes them spiky and invisible. The promised half-ton hit rocks and lavas that formed from 2.7 billion to 3.5 billion years ago.

To analyze the tungsten isotope ratio in ancient rock, geologists extracted and refined their tungsten using a process called ion exchange chromatography. A molten rock sample is loaded into an acidic solution, resulting in vertical splitting of the various elements.Courtesy of Jonas Tush

Back in Germany, Tosh started working. He used a rock to get the fresh rock inside each sample, then cut it into small pieces and made a converter for microscopy at half the width of the hair. He crushed the rest and concentrated the tungsten, then analyzed the tungsten isotope ratio on a mass spectrometer.

For almost two years, the results were effective. This time the isotope ratio was not flat. “It was really nice to see,” Tush commented.

Tungsten-182 concentrations began high among rocks formed 3.3 billion years ago, indicating that the lining is still not mixing. Then 3.1 billion years ago, they declined in value for 200 million years until they reached the modern level. This decrease reflects the decline of the ancient tungsten-162 signal as the mantle begins to mix beneath the pillar. The mix of play tectonics began.

The earth will transform from one to the other The world of water With volcanic islands like Iceland the continent has mountains, rivers and floodplains, lakes and shallow seas

Creating a new world for life

The date of the beginning of about 3.2 billion years ago helps to explain how plate tectonics affected life on Earth.

Before life began, 3.9 billion years ago, And Hamoki was making small stacks in the silt of Pilbara called Stromatolites. 3.48 billion years ago. This shows that plate tectonics is not a prerequisite for life at the most basic level of its life. Yet this is probably not a coincidence Life is diverse Plate tectonics continues as it is.

Shallow sunlight with plate tectonics The oceans and lakes are irrigated with nutrients surrounded by continental rocks. Bacteria grew in these environments to collect sunlight through photosynthesis, Oxygen production.

The fossil record shows an explosion of complex and various animal life about 540 million years ago. One of the most abundant and iconic animals of that era was the trilobite, an armored animal that evolved over millions of years. Illustrated here, a fossil of trilobite Elrathia Kingi.Courtesy Micah L. Razor

For another half-billion years, this oxygen remains barely shaking in the sky, as it reacts immediately with iron and other chemicals. Also, each oxygen molecule produced in photosynthesis matches the carbon atom and these easily reunite in carbon dioxide without gaining a net amount of oxygen in the atmosphere, unless the carbon is buried.

Gradually, though, plate tectonics provided land and sediment to bury more carbon (also Provides plenty of phosphorus To stimulate photosynthetic bacteria). The atmosphere finally became oxygen 2.4 billion years ago.

Oxygen set the planet for the emergence of oxygen-based metabolic plants, animals, and almost everything. Life requires larger and more complex fuels than set germs, and organisms can do much more than they can produce vital, energy-carrying molecules called ATP, including ataxine. “Oxygen is really important for what we think of as complex life,” he said. Athena Easter Of the Massachusetts Institute of Technology.



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