Antarctica is one of the harshest environments in the world covered in ice and remaining in sub-zero temperatures all year round but it is one of the most productive regions in the world for meteorite collection due to large numbers of meteorites congregating in zones called meteorite stranding zones (MSZs) due to upward flowing ice and high ablation rates causing clusters of meteorites to be found in zones on the surface of the ice. However, research has shown that meteorites that fall to the ice could possibly melt further down due to a phenomenon known as englacial solar warming.
A study published recently on Nature Communications explores the potential of such a layer of meteorites beneath the ice of Antarctica.
Due meteorites being guided to MSZs via ice flows it leads to the efficient recovery of many meteorites on the Antarctic continent. Up to December 2015 34,927 meteorites were recovered, currently awaiting names from the Meteoritical Nomenclature Committee (MNC), accounting for 66.3% of the worlds collected meteorite specimens. This shows the importance that Antarctica has to meteorologists due to the sheer number of meteorites collected and the data can be gained from the specimens collected.
However, research has shown that meteorites, especially meteorites with high thermal conductivity, have the potential to be heated up and consequently melt the surrounding ice causing them to sink further beneath the ice forming a potential layer of meteorites beneath the ice of Antarctica. This process is known as englacial solar warming.
Englacial solar warming will cause meteorites to be warmed up as they rise through the ice via MSZs. As a meteor gets closer to the surface there is more solar energy available to the meteorite, this will result in surrounding ice melting and the temperature of the meteorite to increase- causing the meteorite to sink further as its warmer temperature will cause further melting of the ice enabling it to sink further.
However not every type of meteorite will sink further beneath the ice due to englacial solar warming. Only meteorites that have high thermal conductivity will be able to sustain warm enough temperatures enabling them to melt further beneath the ice. These meteorites are generally iron or stony iron meteorites. Due to the lack of iron meteorites and stony-iron meteorites found in MSZs it has lead researchers to believe that a layer of these types of meteorite have sank further beneath the ice than normal stony asteroids, due to their high thermal conductivity.
There are three main types of meteorite: Iron meteorites, Stone meteorites and Stony-iron meteorites. Iron meteorites have a 90-95% iron concentration and the other 5-10% is made up of trace elements and nickel. Due to the very high metal concentration these types of meteorite have high thermal conductivity enabling them to sink further beneath the ice after being heated up via englacial solar warming. Iron meteorites are said to originate from the core of a planet. The next type of meteorite is the stony meteorites. The stony meteorites are the most commonly found of the meteorites and are comprised of mainly rock but the do contain enough iron to be drawn to a magnet. Stony meteorites are said to originate from the outer crust of a planet or from a meteor. The last type of meteorite is the Stony-iron meteorite. The stony-iron meteorites are the least abundant of all the meteorites, accounting for less than 2% of all found meteorites on earth. Stony-iron meteorites are made up of equal parts nickel/iron and stone and are said to have originated from the mantle/core region of the planet they were from.
The results calculated from the recent research carried out show that iron meteorites on average sink lower and are not brought up to the surface of the ice through MSZs. Scientists devised a model that calculated the rate that iron rich meteorites would sink in comparison to non-iron rich meteorites. The results found support the theory of a potential layer of iron rich meteorites further beneath the ice of Antarctica. These meteorites are believed to be trapped 50-100cm beneath the ice and are believed they will never reach the surface as they have sunk too deep to be affected by MSZs.
This has opened up a world of potential for many meteorologists as they can potentially find out more about many early planetary/asteroid bodies from all over the universe by analyzing the data from these iron meteorites that originate from the core of planetary bodies. This could result in many new discoveries about the geology of planets across the universe.