5:15 PM - 7:15 PM
[SMP29-P04] Amorphization of albite under shock compression
Keywords:shock experiments, in situ XRD, albite
Throughout the solar system's history, impact events have played an important role in the evolution of planetary surfaces (French 1998, LPI Contribution No. 954). Shock metamorphism records past impacts via structural and chemical changes in minerals subjected to rapid loading during natural shock events (Stöffler et al., Meteorit. Planet. Sci. 53, 5 (2018); Miyahara et al., Prog. Earth Planet. Sci. 8, 59 (2021)). Building an accurate shock classification system is required to understand the impact history.
Feldspars are aluminum-silicate minerals that make up the most common mineral group found on the surface of the Earth, the Moon, and other planets. The crystal structure of feldspars is composed of a three-dimensional network of silicon ions linked by shared oxygens. Amorphization of the felspars can be observed in natural shocked samples, known as maskelynite, and has been used as an indicator of impact events where shock pressures exceeded 45 GPa (Stöffler et al., Geochim. Cosmochim. Acta 55, 3845 (1991)). However, it is difficult to determine the exact amorphization shock pressure from recovered samples because of the “memory effect”.
Static high-pressure experiments for feldspars reported that re-crystallization occurred after amorphization below a certain pressure boundary, which is known as the memory effect (Daniel et al., J. Geophys. Res. 102, B5 (1997); Sims et al., J. Geophys. Res. 47:12 (2020)). This behavior is also reported in shock experiments. In situ time-resolved XRD data show complete amorphization at ~30 GPa, followed by re-crystallization under a shock wave by a 20-ns laser pulse (Gleason et al., Meteorit. Planet. Sci. 57, 653 (2022)). Recently, we have conducted in situ time-resolved XRD combined with a gas-gun induced plate impact for feldspars at the Dynamic Compression Sector at the Advanced Photon Source. With the longer shock wave pulse duration (~250 ns) compared to the previous laser shock experiments, no re-crystallization was observed after amorphization (Takagi et al. AIP Conference Proceedings (2024)). Static high-pressure experiments also reported the time duration effect on the re-crystallization behavior, where longer duration can play a role in the retention of the amorphous state (Sims et al., J. Geophys. Res. 47:12 (2020)).
Here, we report the results of laser shock experiments for albite with shorter (nano-second order) pulse duration of shock compression. Natural pure albite samples from New Idria, California, were used in this study. The samples were crushed, and sintered at ~1100°C, 50 MPa, for a 10 min holding time. The laser shock experiments were conducted at BL3 EH5 endstation at SPring-8 Angstrom Compact free electron LAser (SACLA). The long pulse laser system with a pulse width of ~5 ns was used for the shock driving source. The crystal structure dynamics under the shock conditions were observed using X-ray Free Electron Laser (XFEL), and velocity was observed simultaneously by velocity interferometer system for any reflector (VISAR) system. Data were collected up to ~50 GPa of shock pressure. The data is currently being analyzed, and we will present the data and discuss the amorphization and recrystallization behavior in the presentation.
Feldspars are aluminum-silicate minerals that make up the most common mineral group found on the surface of the Earth, the Moon, and other planets. The crystal structure of feldspars is composed of a three-dimensional network of silicon ions linked by shared oxygens. Amorphization of the felspars can be observed in natural shocked samples, known as maskelynite, and has been used as an indicator of impact events where shock pressures exceeded 45 GPa (Stöffler et al., Geochim. Cosmochim. Acta 55, 3845 (1991)). However, it is difficult to determine the exact amorphization shock pressure from recovered samples because of the “memory effect”.
Static high-pressure experiments for feldspars reported that re-crystallization occurred after amorphization below a certain pressure boundary, which is known as the memory effect (Daniel et al., J. Geophys. Res. 102, B5 (1997); Sims et al., J. Geophys. Res. 47:12 (2020)). This behavior is also reported in shock experiments. In situ time-resolved XRD data show complete amorphization at ~30 GPa, followed by re-crystallization under a shock wave by a 20-ns laser pulse (Gleason et al., Meteorit. Planet. Sci. 57, 653 (2022)). Recently, we have conducted in situ time-resolved XRD combined with a gas-gun induced plate impact for feldspars at the Dynamic Compression Sector at the Advanced Photon Source. With the longer shock wave pulse duration (~250 ns) compared to the previous laser shock experiments, no re-crystallization was observed after amorphization (Takagi et al. AIP Conference Proceedings (2024)). Static high-pressure experiments also reported the time duration effect on the re-crystallization behavior, where longer duration can play a role in the retention of the amorphous state (Sims et al., J. Geophys. Res. 47:12 (2020)).
Here, we report the results of laser shock experiments for albite with shorter (nano-second order) pulse duration of shock compression. Natural pure albite samples from New Idria, California, were used in this study. The samples were crushed, and sintered at ~1100°C, 50 MPa, for a 10 min holding time. The laser shock experiments were conducted at BL3 EH5 endstation at SPring-8 Angstrom Compact free electron LAser (SACLA). The long pulse laser system with a pulse width of ~5 ns was used for the shock driving source. The crystal structure dynamics under the shock conditions were observed using X-ray Free Electron Laser (XFEL), and velocity was observed simultaneously by velocity interferometer system for any reflector (VISAR) system. Data were collected up to ~50 GPa of shock pressure. The data is currently being analyzed, and we will present the data and discuss the amorphization and recrystallization behavior in the presentation.