|Title:||Ultrafast olivine-ringwoodite transformation during shock compression|
|Authors:||Okuchi, Takuo https://orcid.org/0000-0001-6907-0945 (unconfirmed)|
Hartley, Nicholas J.
Pikuz, Tatiana A.
Tanaka, Kazuo A.
|Author's alias:||奥地, 拓生|
|Keywords:||Asteroids, comets and Kuiper belt|
|Journal title:||Nature Communications|
|Abstract:||Meteorites from interplanetary space often include high-pressure polymorphs of their constituent minerals, which provide records of past hypervelocity collisions. These collisions were expected to occur between kilometre-sized asteroids, generating transient high-pressure states lasting for several seconds to facilitate mineral transformations across the relevant phase boundaries. However, their mechanisms in such a short timescale were never experimentally evaluated and remained speculative. Here, we show a nanosecond transformation mechanism yielding ringwoodite, which is the most typical high-pressure mineral in meteorites. An olivine crystal was shock-compressed by a focused high-power laser pulse, and the transformation was time-resolved by femtosecond diffractometry using an X-ray free electron laser. Our results show the formation of ringwoodite through a faster, diffusionless process, suggesting that ringwoodite can form from collisions between much smaller bodies, such as metre to submetre-sized asteroids, at common relative velocities. Even nominally unshocked meteorites could therefore contain signatures of high-pressure states from past collisions.|
|Description:||天体衝突を記録する結晶の生成を超高速計測 --レーザー衝撃圧縮実験による太陽系史の読解--. 京都大学プレスリリース. 2021-08-02.|
|Rights:||© The Author(s) 2021|
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|Appears in Collections:||Journal Articles|
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