Variation of olivine chondrule textures has been produced by varying the FeO (FeO + MgO) ratio between average Type IA and Type II chondrule compositions for a constant initial melting temperature and heating time. Earlier experiments produced the same variation of olivine chondrule textures by varying the initial heating temperature for a constant FeO (FeO + MgO) ratio. If chondrule textures are produced by heterogeneous nucleation with no external seeding, then the degree of melting directly affects the number of growth sites (nuclei and relic crystals) remaining after the initial chondrule forming event. The degree of melting can be controlled either by changing liquidus temperature [i.e., FeO (FeO + MgO) ratio] or initial melting temperature. A range of heating times and masses of precursor spheres causes variation in the degree of melting and produces variation in chondrule textures. Such effects could be minor in nature compared to initial heating temperatures or bulk composition. Chondrule textures are distributed on a graph of initial temperature vs. FeO (FeO + MgO) ratios as bands parallel to the olivine disappearance curve. Using this graph, chondrule textures can be predicted for FeO (FeO + MgO) ratios at specific initial melting temperatures. Therefore, whether chondrules formed within a restricted temperature range or not, bulk composition was an important variable affecting their textures.
All Science Journal Classification (ASJC) codes
- Geochemistry and Petrology