Rochechouart crater: statistical geochemical investigations and meteoritic contamination.
Abstract
Analyses by atomic absorption spectrometry of Rochechouart samples confirm the Ni anomaly of allochthonous breccias and the meteoritic origin of this Ni enrichment. The average Ni content of impact melt rocks is 10 times that of the target, suevite breccias 5 times, polymict breccias 2.5 times. Metallic particles are not detected in the glass fraction and are probably now all destroyed. The particular setting of Ni in secondary minerals reflects the Ni mobility. Ni moved from the melt and was trapped in the clast fraction, even probably outside of the melt area. Consequently Ni content of impact melts is too low and Ni content of polymict breccias too high. The Ni mobility is restricted to the fall back breccias unit. The disymmetric distribution of the Ni anomaly may be due to an inclined trajectory of the Rochechouart projectile. Geochemical investigations for Fe/Mg indicate that the recovered melt of Rochechouart was probably generated in the deep part of the target, not far from the actual ground level corresponding to the crater floor at the time of impact.
- Publication:
-
Impact and Explosion Cratering: Planetary and Terrestrial Implications
- Pub Date:
- 1977
- Bibcode:
- 1977iecp.symp..449L
- Keywords:
-
- Absorption Spectroscopy;
- Earth Surface;
- Geochemistry;
- Metals;
- Meteorite Craters;
- Breccia;
- France;
- Impact Damage;
- Iron;
- Magnesium;
- Mineralogy;
- Nickel;
- Rocks;
- Lunar and Planetary Exploration;
- Meteorite Craters