Experimentelle und Analytische Planetologie
Nature and origins of meteoritic breccias
Meteorite breccias provide information about impact processes on planetary bodies, their collisional evolution and
structure. Fragmental and regolith breccias are abundant in both differentiated and chondritic meteorite groups and
together with rarer impact melt rocks provide constraints on cratering events and catastrophic impacts on
asteroids. These breccias also constrain the stratigraphy of differentiated and chondritic asteroids and the relative
abundance of different rock types among projectiles. Accretional chondritic breccias formed at low impact speeds
(typically tens or hundreds of m/s), while other breccias reflect hypervelocity impacts at higher speeds (~5 km/s)
after asteroidal orbits were dynamically excited. Iron and stony-iron meteorite breccias only formed, when their
parent bodies were partly molten. Polymict fragmental breccias and regolith breccias in some meteorite groups
contain unique types of clasts that do not occur as individual meteorites in our collections. For example ureilite
breccias contain feldspathic clasts from the ureilite parent body as well as carbonaceous chondritic projectile
material. Such clasts provide new rock types from both unsampled parent bodies and unsampled parts of known
parent bodies. We review breccias in all types of asteroidal meteorites and focus on the formation of regolith
breccias and the role of catastrophic impacts on asteroids.
Beteiligte Wissenschaftler:
Veröffentlichungen:
| 
