Thermal history of ordinary chondrites from Moessbauer spectroscopy data
Abstract
Moessbauer spectroscopy was used to determine the ordering of Fe(2+) with respect to the positions M1 and M2 in the pyroxene structure from L- and H-group chondrites of various petrological types, both for natural specimens and for specimens heated to 550 and 1000 C. It is shown that impacts at intensities greater than 500 kbar lead to cathion disorder analogous to heating above 850 C. The data confirm an earlier finding according to which pyroxenes from the nonequilibrium chondrites Krymka L3 and Saratov L3, 4 cooled rapidly after crystallization. Pyroxenes from L-group chondrites are found to have cooled faster than those belonging to group H.
- Publication:
-
Geokhimiia
- Pub Date:
- September 1977
- Bibcode:
- 1977Geokh.....1288M
- Keywords:
-
- Chondrites;
- Meteoritic Microstructures;
- Mossbauer Effect;
- Spectroscopic Analysis;
- Cooling;
- Crystallization;
- Impact Damage;
- Order-Disorder Transformations;
- Pyroxenes