Picture of the month – ballen structures

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.

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Ballen structures (plane light and crossed polarizers), Chiemgau impact meteorite crater strewn field; Stöttham archeological excavation, catastrophe layer.       Click the LPSC poster!

Ballen structures; Chrudim – Pardubice impact site (Czech Republic); asphaltic polymict impact breccia.

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Ballen structures (photomicrograph, plane light); granitic impact melt rock sheet, Bach/Regensburg (Germany) impact site.