TY - JOUR A1 - Seybold, Lina A1 - Trepmann, Claudia A. A1 - Hölzl, Stefan A1 - Pollok, Kilian A1 - Langenhorst, Falko A1 - Dellefant, Fabian A1 - Kaliwoda, Melanie T1 - Twinned calcite as an indicator of high differential stresses and low shock pressure conditions during impact cratering Y1 - 2023-08-02 VL - 58 IS - 9 SP - 1287 EP - 1305 JF - Meteoritics & Planetary Science DO - 10.1111/maps.14056 PB - N2 -
Shock‐related calcite twins are characterized in calcite‐bearing metagranite cataclasites within crystalline megablocks of the Ries impact structure, Germany, as well as in cores from the FBN1973 research drilling. The calcite likely originates from pre‐impact veins within the Variscan metagranites and gneisses, while the cataclasis is due to the Miocene impact. Quartz in the metagranite components does not contain planar deformation features, indicating low shock pressures (<7 GPa). Calcite, however, shows a high density (>1/μm) of twins with widths <100 nm. Different types of twins (