Хятадын Шинжлэх ухаан, технологийн их сургуулийн судлаачид Исландын галт уулын чулуулаг дахь устөрөгчийн изотопын найрлагад дүн шинжилгээ хийж, Дэлхийн гүнээс эртний бодисууд дээш ялгарч буйг нотолсон байна.
Дэлхий үүсэх явцад металл цөмд хуримтлагдсан устөрөгч, гели, вольфрам зэрэг анхдагч бодисууд мантл руу аажмаар нэвчин гарч байгааг судалгаагаар тогтоожээ. Эрдэмтэд машин сургалт болон квант симуляцийн тусламжтайгаар Дэлхийн анхны магман далайн талсжилтын үйл явцыг загварчлан, одоогийн мантл дахь химийн найрлага нь зөвхөн анхны ялгаралтын үлдэгдэл биш болохыг харуулсан байна.
Исланд болон Канадын Баффины аралд байдаг далайн арлын базальт чулуулагт хийсэн шинжилгээгээр устөрөгчийн хөнгөн изотопын хэмжээ таамаглаж байснаас өндөр байгаа нь тогтоогджээ. Энэхүү химийн өвөрмөц ул мөр нь Дэлхийн гүн давхаргууд бүрэн тусгаарлагдаагүй байж болохыг илтгэж байна.
Судлаачдын тэмдэглэснээр, энэхүү үр дүн нь мантлын гүн дэх химийн шинж чанарууд нь Дэлхийн үүслийн эхэн үеийн энгийн үлдэгдэл биш гэдгийг харуулж байна. Уг судалгаа нь Дэлхийн цөм болон мантлын хооронд бодисын солилцоо үргэлжилсээр байгааг нотлох чухал баримт болж байна.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
Earth’s core has been holding onto materials from the planet’s earliest days for roughly 4.5 billion years. Now, scientists have found evidence that some of those ancient ingredients are slowly escaping into the layers above, including hydrogen, helium, and tungsten. And the clues are hiding in volcanic rocks.
When Earth first formed, it looked nothing like the planet we know today. Its surface was covered in molten rock, temperatures were extreme, and heavy metals were sinking toward the center. As the planet gradually cooled, some materials from the cloud of gas and dust that formed the Solar System became trapped deep inside.
For years, scientists have wondered whether the unusual chemical signatures found in Earth’s deep mantle date back to that early period or developed through later exchanges with the core. A team from the University of Science and Technology of China has now taken a closer look, using advanced simulations to investigate what happened to hydrogen billions of years ago.
Earth’s Core Has Been Holding Onto Ancient Hydrogen
Deep inside Earth, hydrogen left over from the Solar System’s formation may still be making its way out of the metallic core. According to a study published in Science Advances, some of this hydrogen originally came from the solar nebula, the enormous cloud of gas and dust that gave birth to the Sun and planets. As hydrogen moves into the mantle, it can contribute to water stored inside minerals. We’re not talking about underground oceans or rivers of liquid water. Instead, the hydrogen becomes part of mineral structures deep beneath our feet.
To understand where this hydrogen came from, the researchers examined the relationship between ordinary hydrogen and deuterium, a heavier version of the same element. This measurement, called the deuterium-to-hydrogen ratio (D/H), helps scientists track the history of hydrogen inside Earth. Using machine-learning-assisted quantum simulations, the team recreated conditions from the planet’s early molten stages.
They found that the crystallization of Earth’s original magma ocean would have left hydrogen isotopes distributed fairly evenly throughout the mantle. Even changing the starting water content to as much as two ocean masses made little difference. That suggests something else has been changing the mantle’s chemical makeup since Earth formed.
Traces of Earth’s Leaking Core
Some of the best evidence comes from places where material from deep inside Earth eventually reaches the surface. Iceland and Baffin Island, in Canada’s Arctic region, contain volcanic rocks known as ocean island basalts. These rocks form from molten material rising through the mantle, sometimes from regions close to the boundary with Earth’s core. And they carry some unusual chemical fingerprints.
When the researchers compared their model with real rocks, a gap appeared. Certain basalts carry more of the lighter hydrogen than expected, pushing their D/H ratios lower. Early crystallization alone struggles to explain it, which leaves open the idea that the core has been feeding hydrogen into the mantle. As the team explained in the paper:
“Collectively, these results indicate that magma ocean crystallization yields a primitive mantle with an essentially homogeneous hydrogen isotope composition, despite large variations in pressure, temperature, and model assumptions.”
Hydrogen Isn’t The Only Ancient Material Escaping
The team also examined helium and tungsten. Helium is especially useful because its two isotopes come from different sources: helium-3 dates back to the birth of the Universe, while helium-4 keeps being generated by radioactive decay within Earth. Some ocean island basalts show unusually high helium-3-to-helium-4 ratios, which may indicate that primordial material is reaching the mantle.
Then there’s tungsten. Most of Earth’s tungsten sank into the core when the planet’s layers separated, so certain tungsten isotope signatures in volcanic rocks can reveal whether anything has moved between the core and the mantle since. The three elements suggest that Earth’s deepest layers may not have stayed fully isolated.
“These findings suggest that even if primordial deep-mantle reservoirs once existed, the hydrogen isotope signatures in the present-day deep lower mantle are unlikely to represent simple relics of early differentiation,” reported the researchers.
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