Figure 21

Shocked quartz from known airbursts. (a) SEM image of 140-µm-wide shocked quartz grain from Tunguska airburst. Discontinuous lamellae formed along the (0001) plane. (b) Close-up SEM-CL image of same grain as in panel ‘a’. Lamellae spacing ranges from ~ 0.3 to 5 µm. Black lamellae indicate amorphous quartz (AQ). (c) Epi-illumination photomicrograph of 240-µm-wide shocked quartz grain embedded in trinitite that was ejected ~ 400 m from ground zero of the Trinity detonation. Discontinuous, sub-planar, sub-parallel lamellae are oriented along the (0001) plane. (d) Close up SEM-CL image of same grain as in panel ‘c’. Lamellae spacing ranges from ~ 2.5 to 6.5 µm. Black lamellae indicate amorphous quartz (AQ). (e) Epi-illumination photomicrograph of 520-µm-wide shocked quartz grain from Russia's Joe-1/4 nuclear detonations; displays discontinuous sub-planar, sub-parallel micro-fractures and lamellae, just as reported for impact-shocked grains in the Charlevoix crater⁵⁶. There are four sets of lamellae, one of which is oriented parallel to the (0001) plane. (f) Close up SEM-CL image of same grain as in panel ‘e’. Lamellae spacing ranges from ~ 0.3 to 1.3 µm. Black lamellae indicate amorphous quartz (AQ).