A scientist has discovered a method for detecting and better defining meteorite impact sites that have long lost their tell-tale craters. The discovery could further the study of not only Earth’s geology but also that of other bodies in our solar system.

The key, according to work by associate research professor Gunther Kletetschka at the UAF Geophysical Institute, is in the greatly reduced level of natural remanent magnetization of rock that has been subjected to the intense forces from a meteor as it nears and then strikes the surface.

Rocks unaltered by humanmade or non-Earth forces have 2% to 3% natural remanent magnetization, meaning they consist of that quantity of magnetic mineral grains — usually magnetite or hematite or both. Kletetschka found that samples collected at the Santa Fe Impact Structure in New Mexico contained less than 0.1% magnetism.

Kletetschka determined that plasma created at the moment of impact and a change in the behavior of electrons in the rocks’ atoms are the reasons for the minimal magnetism.

Kletetschka reported his findings in a paper published Wednesday in the journal Scientific Reports.

The Santa Fe Impact Structure was discovered in 2005 and is estimated to be about 1.2 billion years old. The site consists of easily recognized shatter cones, which are rocks with fantail features and radiating fracture lines. Shatter cones are believed to only form when a rock is subjected to a high-pressure, high-velocity shock wave such as from a meteor or nuclear explosion.

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