December 1, 2021

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Part of the former Cecilia supercontinent has been discovered in New Zealand

In the summer of 2018, as the heat hit California, Rose Turnbull lined up fine sand grains using the cooling of a windowless foundation. A New Zealand-based geologist at the time was working in a fellow laboratory at California State University in Northridge. In an attempt to solve the mysteries of the Eighth Continent, she sought out small crystals of zircon, also known as TeRiu-a-Māui In Maori.

This task was practical and grease the elbow or in this case, the nose. Mrs. Turnbull gave a small demonstration about the zoom. She wore her tweezers on the outside of her nose to collect some skin. This technique prevents sand grains from scattering throughout the room when picked up.

The crystals came from rocks collected in the New Zealand Islands, which is one of the few pieces of evidence that came from Cecilia. The submerged continent stretches More than 5 million km.. The most submerged, thin and young continent ever discovered. Its existence was recently recognized by the scientific community. Emme Turnbull Works for GNS Science, a research and advisory group in New Zealand. She and her colleagues wanted to know more about the processes that shape this strange land.

The results they received took them by surprise. It hid part of a supercontinent for more than a billion years on the east coast of the South Island and under Stewart Island in New Zealand. This finding suggests that they should not be as young as they think. This age difference may support his eligibility as a continent.

“Continents are like many kinds of glaciers,” he explains Keith Klebs, Research teacher and structural geologist at the University of Vermont. “What you see on the surface doesn’t really represent the full size of the beast.”

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This invention, Described in the review Geography, May help scientists solve a mystery that has been confusing for years. Most continents have a rocky outcrop called the Cretan. In general, part of this land is billions of years old and serves as a permanent base for the formation of continents. By far, the oldest continental crust ever found in Sicily is only 500 million years old, geographically relatively young. If Cecilia is really a continent, why does it seem that its crust has disappeared?

The recently discovered ancient rock may be part of a missing part of the continent. According to Ms Turnbull, the invention “picks the final box”. “We are on a continent. “

In addition, these observations indicate how Cecilia, or any other continental crust, formed Joshua Swartz, Research professor and granite geologist at California State University in Northridge.

“The layer that aligns the Earth’s surface, which we call the crust, is so thin that all the activities necessary for life take place. Built. “

In a continuous search for the lost

Scientists have been monitoring Cecilia for decades, but defining what a continent really is is no small feat. “The terrible secret of geography is that there is no real precise and clear definition of a continent,” Swartz explains.

One of the key components is the composition of the rocks. The ocean floor around Sicily is not made up of magnesium and iron-rich rocks, which make up most of the other marine surfaces. In contrast, it is made from silica-rich rocks such as granite, which is very common in continental crusts. These rocks extend over a wide area, usually much thicker and higher than the ocean surface surrounding a continent.

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Led team of scientists Nick Mortimer, GNS Science, among others, defined these different points when they were firmly guarded. Their purpose is to treat Sicily as a continent However, Mortimer and his team noted an interest: the apparent absence of a croton.

“It’s weird,” Klebsi notices. The continental crust is stronger than its maritime number. It is therefore highly resistant to processes that allow surface rocks to be recycled. The nucleus formed by the croton forms a stable base for the continents. At the same stage of formation, the slow progression of tectonic plates creates island arches and other landscapes along their shores.

For example, Mr. When Swartz spent a family vacation in New Mexico, he said he was “south of Wyoming Groton”. This expansion of the rocks, some of them reach In three billion years, Is one of the crotons that make up the stable inner surface of the North American continent. Mr. The rocks of Santa Fe, where Swartz set his feet, meanwhile, were recently glued to the mainland when a series of islands collided with the ancient coast.

For now, it is believed that the oldest Sicilian crust ever discovered formed when the continent was on the edge of the largest continent. Kondwana, 500 million years ago. Clues to the presence of old rocks have been found in Cecilia, from which there are fragments of the old mantle. 2.7 billion years, But no fragments of the old crust were revealed.

The new study focuses on 169 specimens from the South Island and Stewart Island in the south of New Zealand. Some were collected by Mrs. Turnbull and her team during several trips to the area. Others are from the country’s mineralogy list. Therefore, the collection sites are full representatives of the two islands.

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Back in the lab, they crushed the rocks and sorted the grains according to their density and magnetism. They continued this selection until all the rest were sand and zircon crystals. Ms. Turnbull then took thousands of zircons and placed them on microscope slides. Then, they were covered with epoxy resin and finally polished before undergoing chemical analysis.

“It’s a complete process,” he insists.