Simulated meteorite impacts and volcanic explosions: Ejecta analyses and planetary implications

Details Simulated meteorite impacts and volcanic explosions: Ejecta analyses and planetary implications Simulated meteorite impacts and volcanic explosions: Ejecta analyses and planetary implications

Sep 1992

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1992lmip.conf...31g&link_type=abstract

In Lunar and Planetary Inst., International Conference on Large Meteorite Impacts and Planetary Evolution p 31-32 (SEE N93-10112

Computer Science

Cratering, Earth Crust, Ejecta, Explosions, Hypervelocity Impact, Meteorite Collisions, Meteorite Craters, Volcanoes, Bolides, Breccia, Crystallinity, Deposits, Light Gas Guns, Morphology, Petrography, Simulation

Scientific paper

Past cratering studies have focused primarily on crater morphology. However, important questions remain about the nature of crater deposits. Phenomena that need to be studied include the distribution of shock effects in crater deposits and crater walls; the origin of mono- and polymict breccia; differences between local and distal ejecta; deformation induced by explosive volcanism; and the production of unshocked, high-speed ejecta that could form the lunar and martian meteorites found on the Earth. To study these phenomena, one must characterize ejecta and crater wall materials from impacts produced under controlled conditions. New efforts at LLNL simulate impacts and volcanism and study resultant deformation. All experiments use the two-stage light-gas gun facility at LLNL to accelerate projectiles to velocities of 0.2 to 4.3 km/s, including shock pressures of 0.9 to 50 GPa. We use granite targets and novel experimental geometries to unravel cratering processes in crystalline rocks. We have thus far conducted three types of simulations: soft recovery of ejecta, 'frozen crater' experiments, and an 'artificial volcano. Our ejecta recovery experiments produced a useful separation of impactites. Material originally below the projectile remained trapped there, embedded in the soft metal of the flyer plate. In contrast, material directly adjacent to the projectile was jetted away from the impact, producing an ejecta cone that was trapped in the foam recovery fixture. We find that a significant component of crater ejecta shows no signs of strong shock; this material comes from the near-surface 'interference zone' surrounding the impact site. This phenomenon explains the existence of unshocked meteorites on the Earth of lunar and martian origin. Impact of a large bolide on neighboring planets will produce high-speed, weakly shocked ejecta, which may be trapped by the Earth's gravitational field. 'Frozen crater' experiments show that the interference zone is highly localized; indeed, disaggregation does not extend beyond approx. 1.5 crater radii. A cone-shaped region extending downward from the impact site is completely disaggregated, including powdered rock that escaped into the projectile tube. Petrographic analysis of crater ejecta and wall material will be presented. Finally, study of ejecta from 0.9- and 1.3-GPa simulations of volcanic explosions reveal a complete lack of shock metamorphism. The ejecta shows no evidence of PDF's, amorphization, high-pressure phases, or mosaicism.

Affiliated with

Also associated with

No associations

Rating

Simulated meteorite impacts and volcanic explosions: Ejecta analyses and planetary implications does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Simulated meteorite impacts and volcanic explosions: Ejecta analyses and planetary implications, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Simulated meteorite impacts and volcanic explosions: Ejecta analyses and planetary implications will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1769371