Zur entstehung der Chondren
Abstract
Based on the theory of FREDRIKSSON (1963) an attempt is made to understand the origin of chondrules by studying examples from the meteorites of Tieschitz, Lanzenkirchen, and Mezö-Madaras. Investigations by means of an electron probe microanalyzer, and structural considerations, lead to the following conclusions: 1. The chondrules are of magmatic origin;
2. The crystallization took place from a strongly undercooled melt; 3. Many chondrules in the meteorites of Tieschitz and Mezö-Madaras started to crystallize in the liquidus-solidus field of the respective primary phase, thus leading to a marked disequilibrium; 4. The crystallization of the primary phases of the chondrules of the meteorite of Lanzen-kirchen and some of the chondrules of the meteorites of Mezö-Madaras and Tieschitz did not start until the subsolidus region was reached; 5. This process led to true coexistent phases, i.e. those phases which crystallized simultaneously are in a true equilibrium, despite their crystallization from an extreme disequilibrium; 6. The structural relationship of phenocrysts and the matrix in many chondrules is a disequilibrium structure, even in so-called "equilibrium" chondrites. The consequences concerning the origin of the chondrules are indicated tentatively.- Publication:
-
Geochimica et Cosmochimica Acta
- Pub Date:
- April 1967
- DOI:
- 10.1016/0016-7037(67)90030-0
- Bibcode:
- 1967GeCoA..31..491K