Impact shock feature: ballen structures from four new impact sites in Central Europe (Germany, Czech Republic)
Ballen structures in silica form a characteristic texture in quartz that in general is considered a result from various stages of phase transformation and recrystallization of amorphous silica like e.g., diaplectic glass and hence are regarded as shock indicator. A different model has recently been suggested that proposes a formation of ballen in quartz in an extreme thermal shock event.
Ballen structures (photomicrographs, plane light and crossed polarizers; field width 560 µm). – Saarland (Nalbach, Saarlouis) impact.
Ballen structures impact merging into tridymite and cristobalite.(photomicrographs, crossed polarizers and plane light; field width 1.4 mm). – Saarland (Nalbach, Saarlouis) impact.
Ballen structures; Chrudim – Pardubice impact site (Czech Republic); asphaltic polymict impact breccia.
Ballen structures (photomicrograph, plane light); granitic impact melt rock sheet, Bach/Regensburg (Germany) impact site.