The mineral Davemaoite (CaSiO3-perovskite, the third most abundant mineral in lower mantle layer of ໂລກ interior) has been discovered on the surface of the ແຜ່ນດິນໂລກ for the first time. It was found trapped inside a diamond. Perovskite is found naturally ONLY in lower mantle layer of the interior of the ແຜ່ນດິນໂລກ under extremely high temperature and pressure conditions. This first-ever discovery of interior earth mineral in nature is important to geology for better understanding of dynamics of deep ແຜ່ນດິນໂລກ.
Perovskite ແມ່ນແຮ່ທາດທີ່ປະກອບດ້ວຍທາດການຊຽມ titanium oxide (CaTiO3). ແຮ່ທາດອື່ນໆທີ່ມີໂຄງສ້າງຜລຶກຄ້າຍຄືກັນແມ່ນເອີ້ນວ່າ perovskite. ນີ້ເຮັດໃຫ້ perovskite ເປັນປະເພດທາດປະສົມທີ່ມີໂຄງສ້າງຜລຶກປະເພດດຽວກັນກັບ CaTiO3 (ໂຄງສ້າງ perovskite).
ແຄວຊຽມ-ຊິລິໂຄນ perovskite (CaSiO3-perovskite ຫຼື CaPv) ເປັນແຮ່ທາດທີ່ສໍາຄັນເພາະວ່າມັນເປັນແຮ່ທາດທີ່ອຸດົມສົມບູນອັນດັບສາມ1 (7% ໂດຍປະລິມານ) ໃນຊັ້ນ mantle ຕ່ໍາຂອງ ໂລກ interior and plays a significant role in the heat dynamics of ໂລກ interior. To put things in perspective, of the three layers of ແຜ່ນດິນໂລກ, the mantle layer, between dense super-heated core and thin outer crust layer, makes up 84% of ໂລກ total volume while the lower mantle layer alone comprises 55 percent of the ແຜ່ນດິນໂລກ and extends from 670 and 2900 km in depth. The below table gives a snapshot view of place of perovskite in ໂລກ ພາຍໃນ.
ຕາຕະລາງ: ສະຖານທີ່ຂອງຊັ້ນອຸດົມສົມບູນ perovskite ໃນພາຍໃນຂອງໂລກ
Perovskites along with other minerals in the mantle layer play a key role in the dynamics of deep earth involving heat transfer from core towards surface, called mantle convection. Despite its abundance and importance, perovskite has never been retrieved from the lower mantle layer, because it loses its structure on being removed from its high-pressure conditions.
Researchers have now reported ການຄົ້ນພົບ of calcium silicate perovskite as a diamond inclusion in a natural sample. The diamond was found in Orapa mine, Botswana decades ago and was purchased by a mineralogist of USA in 1987. The team of researchers had been studying the diamond for few years for any entrapped deep-ແຜ່ນດິນໂລກ ແຮ່ທາດ.
ທີມງານຄົ້ນຄ້ວານໍາໂດຍ Oliver Tschauner ໄດ້ຈ້າງ synchrotron x-ray diffraction ເພື່ອສຶກສາໂຄງສ້າງພາຍໃນຂອງ specks ຊ້ໍາຂະຫນາດນ້ອຍ infinitesimally ໃນເພັດຄິດວ່າ perovskite ຈາກຊັ້ນ mantle ຕ່ໍາແລະສາມາດຊອກຫາຫຼັກຖານທີ່ແນ່ນອນຂອງໂຄງສ້າງ cubic CaSiO3-perovskite ເກັບຮັກສາໄວ້. ຢູ່ທີ່ນັ້ນ2.
Further structural and chemical studies indicated that the mineral had large amounts of trapped potassium implying that this perovskite could host three of the major heat-producing elements (uranium and thorium were previously known) which influence heat generation in ໂລກ interior. They named the mineral “davemaoite” (after geophysicist Ho-kwang “Dave” Mao) which was approved as a new natural mineral. The researchers think that the mineral may have originated from lower mantle layer between 650 and 900 km deep below the Earth’s surface 3,4.
ເປັນເລື່ອງແປກທີ່, CaSiO3 perovskite was reported to be discovered in a deep-Earth diamond from South Africa in 2018 however the research team had not claimed official discoveryhttps://www.scientificeuropean.co.uk/sciences/biology/discovery-of-nitrogen-fixing-cell-organelle-nitroplast-in-a-eukaryotic-algae/ of a new mineral 5.
ການຄົ້ນພົບນີ້, ຄຽງຄູ່ກັບການຄົ້ນພົບແຮ່ທາດເພີ່ມເຕີມໃນອະນາຄົດ, ຄວນຈະເສີມສ້າງຄວາມເຂົ້າໃຈກ່ຽວກັບການວິວັດທະນາການຂອງ mantle ຂອງໂລກ.
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ເອກະສານ:
- Zhang Z., et al 2021. ການນໍາຄວາມຮ້ອນຂອງ CaSiO3 perovskite ຢູ່ໃນສະພາບຂອງ mantle ຕ່ໍາ. ການທົບທວນຄືນທາງກາຍ B. ເຫຼັ້ມທີ 104, ສະບັບທີ 18 – 1. ຈັດພີມມາໃນວັນທີ 4 ພະຈິກ 2021. DOI: https://doi.org/10.1103/PhysRevB.104.184101
- ເຟຍ, ຢ. 2021. Perovskite ດຶງມາຈາກ mantle ຕ່ໍາ, ວິທະຍາສາດ. ຈັດພີມມາ 11 ພະຈິກ 2021. ສະບັບ 374, ສະບັບ 6569 ຫນ້າ 820-821. ວິທະຍາສາດ (2021). DOI: https://doi.org/10.1126/science.abm4742
- Tschauner, O. et al. ການຄົ້ນພົບ davemaoite, CaSiO3-perovskite, ເປັນແຮ່ທາດຈາກຊັ້ນລຸ່ມ. ວິທະຍາສາດ. 11 ພະຈິກ 2021. ສະບັບ 374, ສະບັບ 6569 ໜ້າ 891-894. DOI: https://doi.org/10.1126/science.abl8568
- ມະຫາວິທະຍາໄລເນວາດາ 2021. ຂ່າວ - ການຄົ້ນຄວ້າໂດຍຫຍໍ້: ແຮ່ທາດພາຍໃນໂລກທຳອິດທີ່ຄົ້ນພົບໃນທຳມະຊາດ. [ຈັດພີມມາວັນທີ 15 ພະຈິກ 2021. ມີໃຫ້ອອນໄລນ໌ຢູ່ https://www.unlv.edu/news/release/research-brief-first-ever-interior-earth-mineral-discovered-nature
- Nestola, F., Korolev, N., Kopylova, M. et al. CaSiO3 perovskite ໃນເພັດຊີ້ໃຫ້ເຫັນເຖິງການເອົາຄືນຂອງເປືອກມະຫາສະຫມຸດເຂົ້າໄປໃນຊັ້ນລຸ່ມ. ທຳມະຊາດ 555, 237–241 (2018). https://doi.org/10.1038/nature25972
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