Figure 18

Shocked quartz grain from TeH palace. (a) SEM image of a 750-µm-wide fragment of meltglass breccia from the palace, containing melted and partially melted grains surrounded by Ca–Al–Si meltglass. Shocked quartz grain in red at arrow; other grains are not shocked. (b) Transmitted light photomicrograph using an optical microscope (OM); 155-µm-wide HF-etched quartz grain is same as in panel ‘a’. Lamellae are labeled as Miller-Bravais indices (hkil) (ANIE program⁵⁵). Three sets in lower crystallite are all closely-spaced PDFs crossing the entire crystallite. Blue dotted line marks the boundary of one crystallite in polycrystalline grain, containing only one set of lamellae, the (0001) plane with its pole parallel to the c axis. (c) SEM image of same HF-etched grain displaying visible lamellae, which excludes them as tectonic lamellae. (d) SEM-CL image of same grain showing multiple closely-spaced non-luminescent lamellae (black), indicative of amorphous quartz (AQ). (e) Close-up SEM image of same grain, showing visible lamellae, all of which display short-range feather features (FF) that form at ≥ 7 GPa. (f) SEM-CL close-up image, showing black non-luminescent centers of lamellae, indicative of amorphous quartz. Lamellar spacing is ~ 3–5 µm.