A potential hidden layer of meteorites below the ice surface of Antarctica.
A potential hidden layer of meteorites below the ice surface of Antarctica.
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DOI：
10.1038/ncomms10679
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发表时间：
2016-02-16
影响因子：
16.6
通讯作者：
Abrahams ID
中科院分区：
文献类型：
--
作者：
Evatt GW;Coughlan MJ;Joy KH;Smedley AR;Connolly PJ;Abrahams ID
南极洲是地球上收集陨石最多的地区之一。这些小面积的冰川冰被称为陨石搁浅区，在那里向上流动的冰与高消融率相结合，将大量的冰川运输的陨石集中在它们的表面。然而，陨石收集数据显示，与地球上所有其他地点相比，这些地区的铁和石铁陨石的代表性明显不足。在这里，我们解释了这种差异如何可能是由于冰川太阳变暖，从而陨石几十厘米以下的冰面可以被加热到足以导致其周围的冰融化和下沉。我们发现，具有足够高的热导率的陨石（例如，铁陨石）可以以足以抵消每年向上的冰运输总量的速度下沉，因此可能会永久地将它们困在冰面以下，并解释它们在收集数据中的缺失。 收集数据表明，从南极洲回收的铁基陨石的比例明显低于世界其他地区。在这里，作者提出了一种机制来解释这种差异，表明被太阳能加热的铁陨石可以通过冰向下移动，而不是重新出现。
Antarctica contains some of the most productive regions on Earth for collecting meteorites. These small areas of glacial ice are known as meteorite stranding zones, where upward-flowing ice combines with high ablation rates to concentrate large numbers of englacially transported meteorites onto their surface. However, meteorite collection data shows that iron and stony-iron meteorites are significantly under-represented from these regions as compared with all other sites on Earth. Here we explain how this discrepancy may be due to englacial solar warming, whereby meteorites a few tens of centimetres below the ice surface can be warmed up enough to cause melting of their surrounding ice and sink downwards. We show that meteorites with a high-enough thermal conductivity (for example, iron meteorites) can sink at a rate sufficient to offset the total annual upward ice transport, which may therefore permanently trap them below the ice surface and explain their absence from collection data. Collection data suggest the proportion of iron-based meteorites recovered from Antarctica is significantly lower than the rest of the world. Here, the authors propose a mechanism to explain this discrepancy, showing that iron meteorites heated by solar energy can move down through the ice, not to re-emerge.