Meteorites, also known as "meteorites", are unburned stony or iron materials from outer space that fall onto the surface of Earth or other planets. As the "messenger" of the universe, it not only brings scientific researchers the opportunity to explore other planets and the wider universe, but also attracts the attention of many people with its mysterious color.
Since it has landed on earth, you must also want to know, where to pick up such a "fragment of a star"? The most suitable areas on Earth to look for meteorites at the moment are deserts (natural "drying boxes" for meteorite preservation) and Antarctica (natural "refrigerators" for meteorite preservation).
In recent years, a team of researchers and meteorite hunters has collected a large number of meteorites in the desert areas of northern and western China. The research team of Researcher Li Shijie of the Institute of Geochemistry of the Chinese Academy of Sciences and colleagues at home and abroad have carried out a series of studies on the distribution of meteorites found in the continental desert, the characteristics of mineral petrology, the genesis, the history of cosmic ray exposure and the time of surface accumulation, and the results have been published in academic journals at home and abroad. This has certain reference value for scientific researchers, meteorite enthusiasts and meteorite hunters to carry out meteorite research and collection work.
Part.1
Where are the desert meteorites in China?
Desert meteorites on the mainland are mainly distributed in the Gobi region in western and northern China. The International Meteorite Society refers to the specific area where meteorites are found as dense meteorite collection areas (note: this concept is misleading, and the presence of meteorites may not necessarily enrich meteorites). To date, a total of 42 meteorite-rich areas have been found in China.
Distribution map of desert meteorites in China (Fan et al., 2022)
However, the number of meteorites collected in different meteorite-rich areas varies greatly. A team of researchers and meteorite hunters collected a large number of meteorites in some of the meteorite-rich areas around the Kumutag Desert, such as the Kumtag meteorite enrichment area (a total of 64 meteorites), the Alatage Mountain meteorite enrichment area (a total of 47 meteorites), the Loulan Yizhi meteorite enrichment area (a total of 46 meteorites), The Hami meteorite enrichment area (21 meteorites were collected in total) and the Lop Nur meteorite enrichment area (15 meteorites were collected in total) (Figure 1). There are also enrichment areas where only 1 meteorite is collected, such as the Qira enrichment area and the Tazhong enrichment area distributed on the edge of the Taklamakan Desert.
Part.2
Types of desert meteorites in China
As we all know, things are more precious than rare, and the same is true for meteorites. For example, lunar meteorites and Martian meteorites are favored by researchers and meteorite enthusiasts because of their high scientific research value. So how many meteorites were collected in the desert regions of China, and did they contain special types of meteorites? Unfortunately, lunar meteorites and Martian meteorites have never been collected in the desert regions of China.
So far, a total of 300 meteorites have been officially named by the International Society of Meteorites, including 287 ordinary chondrite meteorites, 6 iron meteorites, 1 CO3 chondrite meteorite, 1 diogenite meteorite, 1 ureilite meteorite, 1 brachinite meteorite, 1 ecorite meteorite and 1 EL7 chondrite meteorite. Of course, this list is still being updated!
Hand specimen photographs of some Chinese desert meteorites | Images courtesy of meteorite hunters (or collectors) Wang Zijian, Zhao Yuxian, Chen Pengli, Ma Weijun, Wang Peng, Zhao Zhiqiang, Guo Jianbin and Wen Xinping
After meteorite pairing (all meteorites that landed at the same time were counted as 1), ordinary chondrite meteorites accounted for 72% of desert meteorites in China, including 63 group H meteorites, 133 group L meteorites, and 20 group LL meteorites.
Part.3
The advantage of going to the desert to pick up meteorites
Gathering Benefits:
Meteorite collection in desert areas has significant advantages over meteorite collection in Antarctica. First of all, the Antarctic has low temperatures and harsh working environments throughout the year; although the desert temperature is high, the climate is still relatively pleasant compared to Antarctica; secondly, in terms of transportation, going to the desert is more convenient than going to Antarctica, even if "one person and one car" can work. Traveling to Antarctica requires huge expenses and a lot of human support; the economic cost of scientists and meteor hunters to travel to the desert is much lower than traveling to Antarctica. The above advantages can greatly increase the participation of non-researchers in the collection of desert meteorites.
(a) The research team carried out meteorite collection work in the Kumtag Desert;
(b) Antarctic expedition members are searching for meteorites in Grove Hill / Provided by Chen Hongyi
Research Advantages:
Meteorites that land in Antarctica usually move with the movement of glaciers, and when moving glaciers are blocked by mountains, meteorites within glaciers will enrich at the junction of mountains and glaciers, which greatly increases the difficulty of identifying paired meteorites. However, meteorites that land in desert areas can often be preserved for a long time at the landing site, which facilitates the judgment of pairs of meteorites.
(a) Distribution of Alatage Mountain 001 meteorite rain (Li et al., 2021) ;(b) Distribution of meteorite rain in Three Peaks Mountain (Li Et al., 2017) ;(c) Distribution of Kumtag meteorite rain (Du et al., 2021) distribution of ;(d) Kumtag 016 meteorite rain distribution (Zeng et al., 2018)
In addition, the landing position information recorded by the samples of meteorite rains in desert areas (the phenomenon that the meteoroid bursts during the process of falling and produces many small pieces, and then lands and spreads in a certain surface area) is especially important for studying the rupture process, landing direction and angle of incidence of the meteoroid. Due to the large number and mass of meteorite samples in the meteorite rain, they are more likely to be found than the individual meteorites with smaller masses, so the meteorite rain samples are more important for the calculation of the accumulation time of meteorites in the discovery area.
Part.4
Where in China is the best place to look for meteorites?
The study found that meteorite landings are random events that are relatively evenly distributed across the global surface. Then, the area suitable for searching for meteorites must have a relatively stable surface environment and an older surface age.
More meteorites were found in the southern part of the Hami enrichment area and contained at least five meteorite rains, indicating that the area was more suitable for meteorite collection. To assess the region's ability to preserve meteorites, the team estimated the time for meteorite accumulation in the region.
Meteorite distribution maps were collected within the naming areas of Hami, Kumtag, and Mount Alatag. Region C is currently the most suitable area for meteorite collection in the Chinese desert (Fan et al., 2022)
Since there has been no systematic search for meteorites in this area before, it is more accurate to estimate the accumulation time of meteorites from meteorite rain samples that are more likely to be found in the area (large quantity and mass). Combining the previous study of meteorite fluxes with the mass and distribution area of the five meteorite rains in the region, the research team estimated that the accumulation time of meteorites in this area is not less than 10,000 years, which indicates that this area is currently the most suitable area in the Chinese desert to collect meteorites, and it is likely to find rare types such as lunar or Martian meteorites.
In 2019, two meteorite hunters discovered a 2.54 kg brachinite meteorite in the Gobi region south of Hami. Only 54 brachinite meteorites are currently named by the International Meteorite Society (excluding pairs), which are rarer than lunar and Martian meteorites, which may also indicate that the Gobi region south of Hami has a longer accumulation time. In addition, the large area of light-colored granite distribution in southern Hami is convenient for searchers to identify meteorites in the wild (usually meteorites are darker in color), there are railways and roads nearby, transportation is convenient, and proximity to cities, towns or mining areas is convenient for the supply of field materials, which are good conditions for meteorite search.
"Star Hunters", let's go!
bibliography:
Li Shaolin,Xu Weibiao. (2014). Meteorite enrichment area found in Lop Nur area of Xinjiang. [J]. Chinese Science Bulletin, 59, 2091-2097.
[2] Shi Feng, Li Shijie*, Li Xiongyao, Wang Shijie, Liu Jianzhong, Hu Sen, Yang Benyong, Zeng Xiaojia, 2016. Effects of weathering on the physical properties of ordinary chondrite meteorites. Acta Mineralogica Sinica, 36(1): 1-6.
[3] LI Shijie,WANG Shijie,TANG Junlin,WANG Peng,ZENG Xiaojia,LI Yang. (2017). Chondrite rain found in eastern Lop Nur in Xinjiang. [J]. Chinese Science Bulletin 21, 2407-0415.
[4] Zeng, X. J., Li, S. J., Leya, I., Wang, S. J., Smith, T., Li, Y., and Wang, P. 2018. The Kumtag 016 L5 Strewn Field, Xinjiang Province, China. Meteoritics & Planetary Science 53: 1113–30.
Gao Tianjing,Feng Caixia,Song Guangming,Liu Shen,Li Shijie. (2021). Petrology, mineralogical characteristics and genesis of Iwueucrite meteorites. Acta Geologica Sinica, 95(9), 8.]
[6] Du, K. E., Li, S., Leya, I., Smith, T., Zhang, D., and Wang, P. 2021. The Kumtag Meteorite Strewn Field. Advances in Space Research 67: 4089–4098.
[7] Li, S. J., Leya, I., Wang, S. J., Smith, T., Bao, H. M., Fan, Y., and Mo, B. 2021. Exposure History, Petrology, and Shock Induced Vulcanization Reaction of Alatage Mountain 001 Strewn Field Samples. Meteoritics & Planetary Science 56(7), 1293-1310.8
[8] Fan, Y., Li, S. J., Liu, S., Peng, H., Song, G. M., and Smith, T. 2022. The distribution of the desert meteorites in China and their classification. Meteoritics & Planetary Science, 1-19.
Source: National Astronomical State of China
Author: Li Shijie
(Researcher, Institute of Geochemistry, Chinese Academy of Sciences,
Mainly engaged in meteorite research)
Fan Yan
(Northwest University and the Institute of Geochemistry, Chinese Academy of Sciences jointly train doctoral students, mainly engaged in planetary science related research)
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