Шинэ судалгаагаар дэлхий дээрх амьдралын асар их хохирлыг галт уулын идэвхжил бус, харин солирын мөргөлдөөн шууд өдөөсөн болохыг нотолжээ.
“Proceedings of the National Academy of Sciences” сэтгүүлд нийтлэгдсэн судалгаагаар 66 сая жилийн өмнө тохиолдсон үлэг гүрвэлүүдийн мөхөл нь солирын цохилтын шууд үр дагавар гэдгийг тогтоосон байна. GFZ Helmholtz Centre for Geosciences-ийн эрдэмтэд далайн ёроолын хурдас болон чулуужсан бичил биетүүдийн бүрхүүлд агуулагдах борын изотопыг шинжилснээр энэхүү дүгнэлтэд хүрчээ. Шинжилгээгээр солир унахаас өмнө далайн усны хүчиллэг чанар ихэссэн гэх ул мөр илрээгүй бөгөөд харин мөргөлдөөний дараа огцом өөрчлөлт гарсан нь тогтоогдсон байна.
Судлаачид Нидерланд дахь агуйгаас олдсон солирын цохилтын дараах зузаан шаварлаг давхаргад тулгуурлан далайн химийн найрлага хэрхэн өөрчлөгдсөнийг нарийвчлан судалжээ. Солир мөргөлдөх үед хүхэрлэг чулуулгууд ууршиж, агаар мандалд тархсан нь хүхрийн хүчлийн бороо болон орж, далайн усыг огцом хүчиллэгжүүлсэн байна. Энэхүү байгалийн гэнэтийн цочрол нь кальцийн карбонатаар бүрхүүлээ бүтээдэг далайн бичил биетүүдийг сүйрүүлж, улмаар фотосинтезийн үйл ажиллагааг бууруулжээ.
Майкл Хенехан тэргүүтэй эрдэмтдийн баг энэ үйл явц нь дэлхийн уур амьсгалын тогтолцоог хэдэн сая жилийн турш алдагдуулсныг онцолсон байна. Судалгааны үр дүн нь Чикшулуб кратер болон дэлхий даяар тархсан иридиумын давхарга зэрэг өмнөх нотолгоонуудтай бүрэн нийцэж байгаа юм. Ирээдүйд илүү нарийн технологийн тусламжтайгаар дэлхийн уур амьсгалын өөрчлөлтийн түүхийг өндөр нарийвчлалтайгаар нөхөн сэргээх боломжтой болно гэж эрдэмтэд үзэж байна.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
The asteroid that struck Earth 66 million years ago appears to have been the decisive cause of the mass extinction that wiped out the non-avian dinosaurs. A new study found no evidence that the oceans were already becoming more acidic before the impact.
The extinction that marked the end of the Cretaceous has been studied for decades, yet one question has remained at the center of the debate: was the asteroid impact enough to trigger such a massive loss of life, or had volcanic activity already pushed ecosystems to the brink? The new research leans firmly toward the first explanation.
According to a study published in Proceedings of the National Academy of Sciences (PNAS), scientists reconstructed ocean conditions using microscopic fossils and found signs of a sudden environmental shock rather than a gradual decline. The findings, reported by the GFZ Helmholtz Centre for Geosciences, add new evidence that the Chicxulub impact was the event that set the extinction in motion.
Ancient Fossils Reveal What Happened In The Oceans
To understand how the oceans responded to the impact, researchers measured boron isotopes preserved in the shells of fossil foraminifera. These tiny marine organisms record changes in seawater chemistry, making them valuable archives of past environmental conditions.
The isotope data showed a clear pattern. Based on the study, published by PNAS, there was a rapid episode of ocean acidification immediately after the asteroid struck, but no detectable increase beforehand.
“Our data speak against a gradual deterioration in environmental conditions 66 million years ago,” lead author Michael Henehan said, according to the GFZ Helmholtz Centre for Geosciences. He added that the team found no evidence of increasing ocean acidification before the impact event.
The results also fit with other evidence linked to the extinction, including the Chicxulub crater in the Gulf of Mexico and the worldwide layer of iridium found in sediments dating to the same period.
Marine Life Was Transformed by Ocean Acidification
The team combined fossil evidence from deep-sea drill cores with samples collected from rocks formed around the time of the impact. The GFZ Helmholtz Centre for Geosciences reported that sulfur-rich rocks vaporized during the collision released material into the atmosphere that later returned as sulfuric acid, causing the oceans to become rapidly more acidic.
That sudden change had major consequences for marine organisms that built shells from calcium carbonate. Many of them could no longer survive, leading to a sharp decline in life in the upper layers of the ocean.
As those organisms disappeared, photosynthesis in the oceans also dropped, reducing carbon uptake by roughly half. This phase lasted for several tens of thousands of years before calcareous algae became widespread again. The recovery of marine ecosystems was much slower, taking several million years before the carbon cycle reached a new equilibrium.
A Rare Rock Layer Preserved The Aftermath
One of the study’s key discoveries came from a cave in the Netherlands, where researchers examined an unusually thick clay layer deposited immediately after the asteroid impact. Sites like this are uncommon because sediments often accumulate too slowly to preserve rapid events in detail.
“In this cave, an especially thick layer of clay from the immediate aftermath of the impact accumulated, which is really quite rare,” Henehan said.
The thick deposit provided enough fossil material to capture the transition across the extinction event with unusual precision. Most of the research was carried out at Yale University, where Henehan previously worked. He is now continuing the work at GFZ, using the HELGES laboratory’s femtosecond laser to measure the same chemical signals from much smaller samples. The research team explained that:
“This will in the future enable us to reconstruct disturbances in the Earth-climate system at really high resolution in time, even from locations with very low sedimentation rates.”
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