Энэхүү шинэ нээлт нь Улаан гарагийн 4.5 тэр жилийн түүхэн дэх геологийн үйл явцыг судлахад чухал хувь нэмэр оруулах юм.
Эрдэмтэд 2013 онд Сахарын цөлөөс олдсон NWA 8171 Ангарагийн солир дотроос андрадитын гранат агуулсан шинэ төрлийн чулууг илрүүлжээ. Судлаачид тус дээжнээс гранатаар баялаг хэсгийг судалсан бөгөөд энэ нь Ангарагийн царцдас дотор тогтсон байж болзошгүй бөгөөд урьд өмнө нь ийм төрлийн олдвор ягштал олдож байгаагүй юм. Улаан гарагийг олон арван жилийн турш тойрог зам болон газар дээрх төхөөрөмжүүдээр судалж ирсэн хэдий ч тус гарагаас гаралтай солир нь түүний өнгөрсөн үеийн талаарх үнэ цэнтэй мэдээллийг шууд лабораторид судлах боломжийг олгодог байна.
Дэлхий дээр андрадитын гранат нь ихэвчлэн эх газрын плитүүдийн хөдөлгөөнөөс үүдэлтэй өндөр даралт, температурын нөхцөлд үүсдэг бол Ангараг гарагт идэвхтэй плит төктоник байхгүй тул энэхүү нээлт нь эрдэмтдийн анхаарлыг татаж байна. Geochemical Perspectives Letters сэтгүүлд нийтлэгдсэн уг судалгаагаар энэхүү гранатаар баялаг хэсэг нь урьд өмнө ажиглагдаж байгаагүй Ангарагийн метаморф үйл явц эсвэл эртний магмын үүсгэсэн галт уулын чулуулаг байх магадлалтай гэж үзжээ.
NWA 8171 солир нь Ангараг гарагт болсон эртний мөргөлдөөний улмаас бутарч, дахин холилдсон олон хэлтэрхийгээс бүрддэг Ангарагийн полимикт реголит брекчи солирын бүлэгт багтдаг. Судлаачид тус чулуунд хадгалагдсан үлдэгдэл хийн найрлага нь Ангарагийн агаар мандалтай тохирч байгаа бөгөөд эрдсийн хими болон хүчилтөрөгчийн изотопын найрлага нь Ангарагийн гаралтай болохыг баталгаажуулсан байна. NWA 8171 солир нь алдарт “Black Beauty” буюу NWA 7034 солирын хамт ижил солирын уналтад холбогдох 18 хэлтэрхийн нэг юм.
Судалгааны баг солирын хэсэг дэх пироксены мөхлөгүүд болон бусад эрдсийн шинж чанарууд нь Ангарагийн бусад эрдэстэй төстэй болохыг тогтоожээ. Гэсэн хэдий ч реголит брекчи солир нь янз бүрийн түүхтэй материалыг агуулж болох тул эрдэмтэд илүү нарийвчилсан шинжилгээ хийхээр төлөвлөж байна. Энэхүү олдвор нь Ангараг гарагийн геологийн ээдрээтэй түүхийг тайлахад чухал түлхүүр болох юм.
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Scientists have found a new type of rock inside a Martian meteorite that contains andradite garnet, a mineral often associated with gemstones on Earth. The discovery suggests that this garnet may have formed on Mars itself. The rock was discovered inside the NWA 8171 meteorite, which was found in the Sahara Desert in 2013.
Researchers studying the sample found a fragment rich in garnet, something never clearly identified before in a Martian rock that may have formed inside the planet’s crust. The Red planet has been explored for decades by orbiters, landers and rovers, but meteorites that come from the planet continue to provide valuable information about its past. Unlike images from spacecraft, these rocks can be studied directly in laboratories.
Scientists behind the discovery explain that minerals can preserve a record of how a planet changes over time. This new garnet-bearing rock gives researchers another clue about the geological forces that shaped Mars over its 4.5-billion-year history.
A Gemstone Hidden In An Unusual Martian Rock
On Earth, garnet is famous as a colourful gemstone and the traditional January birthstone. But scientists also study it because its chemical composition can reveal the conditions where a rock formed. The garnet found in NWA 8171 belongs to the andradite family. This variety is often yellow or green and can also be used as a gemstone called demantoid. Garnets include several other varieties, such as almandine, pyrope and grossular.
On Earth, andradite garnet usually forms in skarns, rocks created when heat and fluids transform existing materials. These environments are often linked to Earth’s active plate tectonics, where movements of the crust create extreme pressure and temperature conditions.
Mars does not have active plate tectonics, making this discovery particularly interesting. Scientists are still trying to understand how much geological activity happened inside the Martian crust.
The team behind the discovery, published in Geochemical Perspectives Letters, says the garnet-rich fragment could come from a type of Martian metamorphic process never seen before. Another possibility is that it formed from an unusual kind of volcanic rock created by ancient magma.
The Mars Fragment That Tells an Ancient Story
The meteorite containing the garnet fragment is known as NWA 8171 and belongs to a group called Martian polymict regolith breccia meteorites. These rocks are made from many different fragments that were broken apart and later combined again after ancient impacts on Mars.
Researchers confirmed the meteorite’s Martian origin through several types of evidence. The study found that trapped noble gases inside the rock match the atmosphere of Mars, while its mineral chemistry and oxygen isotope composition also fit known Martian signatures.
Oxygen isotopes are especially useful because they act like fingerprints, helping scientists identify where a rock came from. NWA 8171 is one of 18 fragments linked to the same meteorite fall, alongside the famous NWA 7034, also called Black Beauty.
The meteorite’s complicated structure makes the discovery more difficult to interpret. Since different pieces were mixed together after impacts, scientists need to carefully study each fragment to understand its origin.
The Rock Mystery That Refuses to Be Solved
Researchers have found several signs that the garnet-bearing fragment came from Mars. The pyroxene grains mixed with the garnet have chemical characteristics similar to other Martian minerals. The texture of the fragment also looks like other materials found in NWA 8171.
The research team notes that the fragment being embedded in a confirmed Martian meteorite is another strong indication of its origin. Still, scientists are keeping an open mind because regolith breccia meteorites can contain material with different histories.
Since these meteorites are made from many pieces gathered together after impacts, some fragments could theoretically come from other sources, including rare rocks from elsewhere in the Solar System.
A direct measurement of the fragment’s oxygen isotope composition would provide stronger confirmation. This type of analysis requires removing part of the sample, so researchers have chosen to continue studying the meteorite before carrying out the test.
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