The earth is bombed every year by rocky remains, but the rate of meteorites coming in may change over time. Finding enough meteorites that are scattered on the surface of the planet can be challenging, especially if you are interested in rebuilding how often they land. Now, researchers have revealed a wealth of meteorites that have kept them well, which allowed them to recreate the rate of meteorites that have fallen over the last two million years.
"Our purpose in this work was to see how the meteorite flux changed to the Earth over large schedules – millions of years, consistent with astronomical phenomena," said Alexis Drouard, Aix-Marseille Université, lead author of the newspaper. is Geology.
To restore a meteorite record for millions of years, the researchers went to the Atacama Desert. Drouard says that they need a study site and would keep a wide range of terrestrial ages where the meteorites could continue over a long time.
Although Antarctica and hot desert support a large percentage of meteorites on Earth (about 64% and 30% respectively), Drouard says, "Meteorites found in hot deserts or Antarctica are rarely more than half t million years. " It adds that meteorites disappear naturally due to weathering processes (eg wind erosion), but because these locations themselves are young, the meteorites found on the surface are also young.
"The Atacama Desert in Chile is very old ([over] 10 million years), "said Drouard." It also maintains the world's largest collection of meteorites. "
The team collected 388 meteorites and focused on 54 stony samples from the El Médano area in the Atacama Desert. Using cosmogenic age dating, the mean age was found to be 710,000 years old. In addition, 30% of the samples were older than a million years, and two samples were over two million. All of the 54 meteorites were common gondrites, or stony meteorites containing fine grains, but spanning three different types.
"We were expecting more young metals than some old ones (as the old ones were lost to weathering)," said Drouard. "But it is clear that the age distribution is explained perfectly by a constant accumulation of meteorites for millions of years." The authors note that this is the oldest meteorite collection on the Earth's surface.
Drouard says that this terrestrial meteorite crop in the Atacama can generate further research on the study of meteorite flux over large timescales. "We found that the meteorite flux has remained constant over this [two-million-year] period in numbers (222 meteorites more than 10 g per square kilometer per million years), but not in composition, "Drouard said the team intends to expand their work, measuring more samples and reducing the amount of time it is. The meteorites "This will tell us about the journey of these meteorites of their parent body to the surface of the Earth."
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Meteorite flux last 2 m. has been recorded in the Atacama Desert, t Geology, doi.org/10.1130/G45831.1, pubs.geoscienceworld.org/gsa/g… st-2-m-y-recorded in
Ancient meteorite collection on Earth to be found in one of the driest places (2019, May 23)
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